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Cayman Islands Government

Landfill Site Environmental Review Task 2: Environmental Investigations Interpretative Report

9 March 2016

Amec Foster Wheeler Environment

& Infrastructure UK Limited

3 © Amec Foster Wheeler Environment & Infrastructure UK Limited

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Executive summary

Background and Scope

This report has been produced as a deliverable associated with Phase 1 of the National Solid Waste Management Strategy (NSWMS) for the Cayman Islands. It comprises Task 2: Environmental investigations and updated risk assessments for the three operational landfill sites located on the islands. It follows on from Task 1 environmental review (February 2015) which was a review of existing environmental information and initial risk assessment. The Task 1 environmental review provided a series of recommendations for targeted risk based environmental sampling and monitoring which formed the basis of the Task 2 fieldwork, the factual data for which is reported separately. This report is an interpretation of data from both the recent environmental investigation and historical data where appropriate. Environmental risk assessments from the Task 1 environmental review have been updated based on the Task 2 investigation data.

The main landfill site is located at George Town on Grand Cayman and this is where the bulk of the Task 2 environmental investigation work took place. It included the monitoring of existing and new groundwater wells, surface water and sediment sampling in canals/dykes surrounding the site and in North Sound, and dust and landfill gas monitoring. Samples of vegetation surrounding the landfill and also from within North Sound were taken for analysis. Historical monitoring data for groundwater and surface waters has also been considered within the interpretation of environmental effects.

Groundwater boreholes were installed and sampled at Cayman Brac landfill together with sampling of surface waters and monitoring and sampling of landfill gas. At Little Cayman landfill, where wastes are set alight and burned, some soil and surface water sampling was undertaken. There is no significant pre-existing environmental monitoring data for the two sister island landfills.

This environmental data has been collated and screened, primarily against Florida state clean-up assessment criteria for waters and soils. Landfill gas monitoring and analysis was undertaken on the George Town and Cayman Brac sites and based on the collected data air quality modelling has been undertaken for the George Town site. Amenity related issues have also been considered for each site; these are hazards such as dust, landfill fires and nutrients in waters for which there are no direct assessment criteria.

Risk Assessment

Based on appraisal of environmental data and consideration of receptors a qualitative risk assessment has been undertaken for each of the sites. The outcome of the risk assessments in terms of identification of key1 contamination and amenity risks associated with the landfills are as follows:

George Town:

Site users and visitors: arsenic in soils as well as hydrogen sulphide generation on and off the landfill and methane generation on the landfill;

Adjacent residents: nuisance from odour and risks from combustion products in tyre/landfill fires;

Adjacent commercial/industrial site users: hydrogen sulphide from sediments contaminated by various sources including the landfill, as well as nuisance from odour and landfill fires;

Groundwater: hydrocarbons from spills and overtopping of bunds, elevated ammonia contribution to surface water contamination via baseflow;

1 Key contamination risks are regarded as those that are assessed as moderate and above. For amenity risks, which are much more subjective in nature, key risks are defined as high risks only.


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Surface water: hydrocarbons from spills and overtopping of bunds, ammonia and orthophosphates from groundwater; and

North Sound: ammonia and metals from canal water impacting on water quality and ecology, and eutrophication and blanketing of vegetation adjacent to the canal outfall.

The landfill also has a significant visual impact from various viewpoints.

Cayman Brac

Site users and visitors: methane from landfill gas;

Groundwater: hydrocarbons from waste oil storage spills to ground; and

Surface water: metals leaching from landfill.

Little Cayman

Groundwater: hydrocarbons from illegal waste oil disposal pit.

Recommendations

Amec Foster Wheeler’s recommendations resulting from assessment and interpretation of the data in this report and the resultant risk assessments are summarised in the following tables.

Recommendations for Environmental Improvements and Monitoring at George Town Landfill

Ref Source/Risk Proposed Work Objective/Rationale

1 Fugitive gas emissions from the landfill surface

Progressive engineered capping of completed areas of the landfill to minimise landfill gas emission and enable gas collection for energy recovery Application of daily cover to landfilled wastes

Reduction in emission of odorous gas constituents and methane which is a significant greenhouse gas Prevent vermin accessing the landfilled wastes

2 Landfill gas Repeat of flux box tests Bulk gas monitoring in existing gas probes at least every three months Gas pumping trials following first phase of capping

Better definition of landfill gas emission rates Ongoing evaluation of gas quality Recovery of landfill gas and use in electricity generation.

3 Incinerator emissions Establish emissions monitoring programme

Provide quantitative assessment of emissions from incinerator and their likely impact

4 Landfill fires Removal of stockpiled tyres which are a particular fire hazard Monitoring for airborne PAH’s during waste fires

Burning tyres pose a significant risk in terms of combustion Evaluation of potential health impact to offsite receptors (note capping of the wastes will reduce the potential for fires).

5 Groundwater contamination

Progressive capping of the site Monitoring of existing groundwater wells on at least an annual basis

Reduce leaching potential from the wastes and impact on groundwater Continued evaluation of impacts


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6 Surface water contamination

Monitoring in North Canal on at least a six monthly basis

Continued evaluation of impacts

7 Marine water contamination

Reinstate annual DoE sampling in North Sound

Continued evaluation of impacts. Study into eutrophication in North Sound adjacent to the landfill

Recommendations for Environmental Improvements and Monitoring at Cayman Brac Landfill


1 Clinical waste disposal in the landfill

Reinstate the incinerator to prevent direct disposal If continued landfill disposal in the short term then cover the disposal area daily

Cease landfill disposal of clinical waste Good practice and reduced risk of vermin nuisance or public health incident

2 Incinerator emissions Establish emissions monitoring programme when incinerator is operational


3 Landfill gas as a greenhouse gas

Bulk gas monitoring in existing gas probes at least every three months Consideration of whether engineered capping and gas recovery for flaring is of cost benefit

Ongoing evaluation of gas quality Potential reduction in uncontrolled gas emission by may not be economically viable due to small size of landfill


Monitoring of existing groundwater wells on at least an annual basis



Monitoring of shrimp pond on at least an annual basis


Recommendations for Environmental Improvements and Monitoring at Little Cayman Landfill

Ref Source/Risk Proposed Works Objective/Rationale

1 Illegal oil disposal pit Prevent access Further assessment and remediation

Potential health and safety hazard and prevent further disposal Assessment of remediation requirements

2 Continued uncontrolled landfill expansion

Management and restrictions to prevent further expansion of burning area

Limit on uncontrolled site expansion, especially in direction of Booby Pond.


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Contents

1. Introduction 11

1.1 Background 11

1.2 Scope and Terms of Reference 11 George Town Landfill 11 Cayman Brac Landfill 12 Little Cayman Landfill 12

1.3 Structure of the Report 12

2. Assessment Methodology 13

2.1 Assessment Approaches 13

2.2 Land and Water Contamination 13 Approach 13 Assessment Standards 14 Risk Assessment Criteria for Land and Water Contamination 15

2.3 Air Quality Modelling 17

2.4 Amenity Risk 17 Risk Assessment Criteria for Amenity Risk 17

3. Environmental Condition George Town Landfill 19

3.1 Location and Setting 19 Location 19 Topography 19 Surrounding Land Use 19 Site History and Infrastructure 20 Climatological Information 20 Waste Composition and Inputs 20 Geological Setting 20

3.2 Data Sources 21 Previous Environmental Reports 21 Pre-Existing Environmental Monitoring Data 22

3.3 Hydrogeology 22 Regional Setting 22 Abstractions 22 Groundwater Levels 22 Groundwater Quality 23

3.4 Hydrology 25 Drainage Network 25 Surface Water Quality 26 Marine Water Quality 28

3.5 Soil and Biota Sampling 31 Sediment Sampling 31 Biological Sampling 32 Soil Sampling 33

3.6 Landfill Gas 33 Site Inspection 2014 34 Gas Probes 2015 34

3.7 Fugitive Emissions 35 Flux Boxes 2015 35 Hydrogen Sulphide Monitoring 2015 36 Dust Sampling and Deposition Monitoring 2015 37 Other Vapour Sources 39 Fires 39

3.8 Air Quality Modelling 39


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Estimation of LFG Surface Emissions 39 Estimation of Odour Emission Rates 39 Dispersion Model Set-up 39 Data Processing and Outputs 40 Assessment Criteria 41 Results of the Assessment 42 Conclusions 45

3.9 Other Issues 45

3.10 Risk Assessment 46 Approach 46 Conceptual Model 46 Summary of Potential Contamination and Hazards 46 Receptors and Pathways 48 Risk Assessment Methodology 49

3.11 Risk Assessment Outcomes 49 Site Workers and Visitors 49 Adjacent Residents 49 Adjacent Commercial/Industrial Users 50 Groundwater 50 Surface Water Canals 50 North Sound 50

4. Environmental Condition Cayman Brac Landfill 51

4.1 Location and Setting 51 Topography 51 Surrounding Land Use 51

4.2 Site Infrastructure 51

4.3 Data Sources 52

4.4 Site History 52

4.5 Waste Inputs 52

4.6 Geology 52

4.7 Hydrogeology 53 Regional Setting 53 Groundwater Levels 53 Groundwater Quality 53

4.8 Hydrology and Surface Water Quality 55

4.9 Ecological Receptors 56

4.10 Soil Sampling 57

4.11 Landfill Gas 57 Site Inspection 2014 57 Gas Probes 2015 57

4.12 Fugitive Emissions 59 Hydrogen Sulphide Monitoring 2015 59 Dust Deposition Monitoring 2015 59 Other Vapour Sources 59 Fires 59

4.13 Other Issues 60


4.15 Risk Assessment Outcomes 63 Site Workers and Visitors 63 Adjacent Residents 63 Groundwater 63 Shrimp Lagoon 63 Ocean 63


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5. Environmental Condition Little Cayman Landfill 65

5.1 Location and Setting 65 Topography 65 Surrounding Land Use 65

5.2 Site Infrastructure 65

5.3 Data Sources 65

5.4 Site History 66

5.5 Waste Inputs 66

5.6 Ecological Receptors 66

5.7 Geology 66

5.8 Hydrogeology 66

5.9 Hydrology 66 2001 DEH Sampling 66 Amec Foster Wheeler Sampling 2015 67

5.10 Soil Sampling 68

5.11 Fugitive Emissions 69 Dust Deposition Monitoring 2015 69 Smoke 69 Other Vapour Sources 69

5.12 Other Issues 69


5.14 Risk Assessment Outcomes 71 Site Workers and Visitors 72 Adjacent Residents 72 Groundwater and Offsite Pools 72 Booby Pond 72

6. Conclusions and Recommendations 73

6.1 Conclusions 73 Basis of Study and Data 73 George Town Landfill 73 Cayman Brac Landfill 74 Little Cayman Landfill 74

6.2 Recommendations 75

Table 2.1 CLR11 Tiered Framework 13 Table 2.2 Ammonia Standards in Type 7 Rivers (UK) 15 Table 2.3 Reactive Phosphorus Standards in Lowland High Alkalinity Rivers (UK) 15 Table 2.4 Risk Assessment Criteria Land and Water Contamination 16 Table 2.5 Potential Significance of Contaminant-Receptor Linkage Matrix 17 Table 2.6 Assessment Approach for Amenity Risks 18 Table 2.7 Amenity Risk Matrix 18 Table 3.1 Meteorological Summaries for Grand Cayman 20 Table 3.2 Geological Succession George Town Landfill Area 21 Table 3.3 Ammonia in Groundwater 2015 24 Table 3.4 Surface Water Sample Locations 29 Table 3.5 North Sound Water Analysis April 2015 Key Parameters 30 Table 3.6 1991 Sediment Sample Results (4 samples) 31 Table 3.7 Dust Deposition Monitoring Locations - George Town Landfill 38 Table 3.8 ADMS Model Configuration 40 Table 3.9 Trace Pollutants and Assessment Criteria 42 Table 3.10 Odour Results at Discrete Receptors 43 Table 3.11 Trace Pollutant Results at Discrete Receptors – Short Term Averages 44


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Table 3.12 Trace Pollutant Results at Discrete Receptors – Long Term Averages 45 Table 3.13 Summary of On-site Potential Contamination and Hazards 46 Table 3.14 Summary of Offsite Potential Contamination and Hazards 48 Table 3.15 Receptors 48 Table 3.16 Potential Receptors and Pathways 49 Table 4.1 Ammonia in Groundwater 2015 54 Table 4.2 Shrimp Pond Summary of Water Analysis 2001 55 Table 4.3 Dust Deposition Monitoring Locations - Cayman Brac Landfill 59 Table 4.4 Summary of Onsite Potential Contamination and Hazards 61 Table 4.5 Receptors 62 Table 4.6 Potential Receptors and Pathways 62 Table 5.1 Little Cayman Summary of Water Analysis 2001 67 Table 5.2 Dust Deposition Monitoring Locations – Little Cayman Landfill 69 Table 5.3 Summary of Onsite Potential Contamination and Hazards 70 Table 5.4 Receptors 71 Table 5.5 Potential Receptors and Pathways 71 Table 6.1 Recommendations for Environmental Improvements and Monitoring at George Town Landfill 75 Table 6.2 Recommendations for Environmental Improvements and Monitoring at Cayman Brac Landfill 76 Table 6.3 Recommendations for Environmental Improvements and Monitoring at Little Cayman Landfill 76

Figure 1 George Town Landfill - Site Layout Figure 2 George Town Landfill - Groundwater Sampling Locations Figure 3 George Town Landfill - Ammonia in Groundwater Figure 4 George Town Landfill - Orthophosphate in Groundwater Figure 5 George Town Landfill - Surface Water Sampling Locations Figure 6 George Town Landfill - BOD in Surface Water Figure 7 George Town Landfill - Ammonia in Surface Water Figure 8 George Town Landfill - Orthophosphate in Surface Water Figure 9 George Town Landfill - Sediment Sampling Locations Figure 10 George Town Landfill - Gas Probe, Flux Box and Dust Monitoring Locations Figure 11 George Town Landfill - Ambient H2S in Air (11/04/2015) Figure 12 George Town Landfill - Ambient H2S in Air (18/04/2015) Figure 13 George Town Landfill - GasSim Output Graph Figure 14 George Town Landfill - Dispersion Model Domain and Discrete Receptor Locations Figure 15 Wind Rose for Owen Roberts International Airport 2013-2015 Figure 16 George Town Landfill - Odour Dispersion Pattern Figure 17 George Town Landfill - Conceptual Site Model Figure 18 Cayman Brac Landfill - Site Layout Figure 19 Cayman Brac Landfill - Exploratory Hole Locations Figure 20 Cayman Brac Landfill - Sampling Locations Figure 21 Cayman Brac Landfill - Conceptual Site Model Figure 22 Little Cayman Landfill - Site Layout Figure 23 Little Cayman Landfill - Sampling Locations Figure 24 Little Cayman Landfill - Conceptual Site Model

Appendix A Screened Groundwater Data, George Town Landfill Appendix B Screened Surface Water Data, George Town Landfill Appendix C1 Time Series Plots North Canal Water Quality Appendix C2 Time Series Plots North Sound Water Quality Appendix D Screened Soils Data, George Town Landfill Appendix E Risk Assessment Tables, George Town Landfill Appendix F Screened Groundwater Data, Cayman Brac Landfill Appendix G Screened Surface Water Data, Cayman Brac Landfill Appendix H Risk Assessment Tables, Cayman Brac Landfill Appendix I Screened Surface Water Data, Little Cayman Landfill Appendix J Risk Assessment Tables, Little Cayman Landfill


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1. Introduction

1.1 Background

Amec Foster Wheeler Environment & Infrastructure UK Ltd. (Amec Foster Wheeler) has been commissioned by the Cayman Islands Government (CIG) to prepare and assist in the delivery of a National Solid Waste Management Strategy (NSWMS) for the Cayman Islands. This work is being delivered in three main phases:

Phase 1: The preparation of the NSWMS and the delivery of environmental investigations at the existing landfills on the islands;

Phase 2: Preparation of an Outline Business Case to deliver the NSWMS; and

Phase 3: The procurement of the new waste management services and infrastructure in line with the NSWMS.

1.2 Scope and Terms of Reference

This report has been prepared by Amec Foster Wheeler on behalf of the CIG as a deliverable from Phase 1. It comprises Task 2: Environmental investigations and updated risk assessments for the three operational landfill sites located on the islands. It follows on from Task 1 environmental review (February 2015) which was a review of existing environmental information and initial risk assessment. The Task 1 report provided a series of recommendations for targeted risk based environmental sampling and monitoring which formed the basis of the Task 2 fieldwork for which the factual data is reported separately. The Task 2 investigation draft factual report (Amec Foster Wheeler reference 36082rr008i1) is dated June 2015.

The scope of the targeted environmental investigations was agreed with CIG and was generally in line with the Task 1 environmental review recommendations, albeit with some minor variation and additions. The fieldwork was undertaken between 8 and 18 April 2015 and included the following work:

George Town Landfill

Groundwater sampling and analysis in 5 existing wells (MW8, 9, 11, 13 and 14) as well as 4 new monitoring wells (MW15A, MW19, MW20 and MW21);

Groundwater level monitoring of all of the above wells plus continuous level monitoring in wells MW8, MW9 and MW14 by data logger, which appears to show a tidal influence;

Surface water sampling and analysis at 10 locations including within North Sound, the North Canal, nearby ponds and a sample of ponded leachate from within the landfill;

Sediment sampling and analysis at 6 locations in perimeter canals/dykes and the North Sound;

Sampling and analysis of plant samples from 4 locations around the landfill and 6 samples of marine vegetation/algae from North Sound;

Installation of 6 gas probes (GP1-GP6) within the wastes and monitoring and analysis of landfill gas from each probe;

Flux box monitoring of landfill gas surface emissions at three locations across the landfill, including one on a capped area and two on uncapped wastes;

Dust sampling at 2 locations (DM1 and DM2);

Dust deposition measurements at a total of 9 locations across the site during the investigation;

Fugitive hydrogen sulphide surveys on and adjacent to the landfill on two occasions; and

Sampling of soil from the Hurricane Ivan fill area for asbestos (17 samples).


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Cayman Brac Landfill

Groundwater sampling and analysis in 4 new monitoring wells (CB1-CB4);

Surface water sampling and analysis at 3 locations (BSW1-BSW3) from surrounding ponds;

Installation of 4 gas probes (GP21-GP24) within the wastes and monitoring and analysis of landfill gas;

Dust deposition measurements at two locations during the investigation;

Fugitive hydrogen sulphide surveys on the landfill (14 April 2015); and

Sampling of soil from across the landfill, principally for asbestos although the soil sampled from an area of surface staining (BSS6) was also scheduled from diesel range organics (DRO) and polycyclic aromatic hydrocarbons (PAHs).

Little Cayman Landfill

Sampling of soil (LSS1-LSS5) for analysis and leaching tests;

Surface water sampling and analysis at 2 locations (LSW2 and 3); and

Dust deposition measurements in one location during the investigation.

The sampling and monitoring was undertaken by Amec Foster Wheeler staff from the United Kingdom and United States (US). Laboratory analysis was undertaken in the US.

Amec Foster Wheeler were supported during the investigation work by personnel from a number of CIG departments including Department of Environmental Health (DEH), Department of Environment (DoE), Public Works Department (PWD) and Ministry of Home Affairs Health and Culture (MHAH&C). New monitoring wells were completed by Industrial Services & Equipment (ISE) Limited under contract to Amec Foster Wheeler.

This report is an interpretation of the investigation data, the detailed results for which are provided in a separate factual report. It also includes some reference to previous monitoring information, where it exists and which is mainly associated with the George Town site, which was reported in the Task 1 environmental review. Preliminary environmental risk assessments were reported in the Task 1 environmental review; these have been updated in this report based on the findings of the Task 2 investigations and monitoring.

The three landfill sites are all currently operational and receive the majority of waste that is generated on the islands. However, the development of the new NSWMS will be guided by the waste management hierarchy and will aim to significantly reduce the future dependency on landfilling as a waste management option. The current environmental condition of the landfills, nevertheless, remains a significant factor in considering both the short and long term waste management options for the islands and the potential environmental liability they pose now and in the future. These environmental liabilities are discussed in this report which provides some recommendations on further assessment and management of the sites.

1.3 Structure of the Report

The report is structured as follows:

Section 1: Introduction

Section 2: Assessment methodology

Section 3: Environmental condition George Town Landfill;

Section 4: Environmental condition Cayman Brac Landfill;

Section 5: Environmental condition Little Cayman Landfill; and

Section 6: Conclusions and recommendations.


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2. Assessment Methodology

2.1 Assessment Approaches

Three different assessment approaches have been used to evaluate the environmental condition of the landfill sites:

Soil, surface water and groundwater water data has generally been screened against generic assessment criteria (GAC, i.e. a ‘Tier 2’ assessment) based on the Florida Administrative Code (FAC) contaminant clean up target levels2 which are based on human health assessment;

UK proposed standards under the Water Framework Directive (WFD) to protect the water environment have been used for nutrients and some metals within surface waters3;

Air quality data (including landfill gas and dust) have been assessed against UK Environment Agency (EA) and World Health Organisation (WHO) assessment criteria;

Amenity risk, such as windblown litter, for which there are no quantitative assessment standards, has been evaluated in accordance with UK EA H1 Annex A guidance4.

Further detail of the assessment methodologies is provided below.

2.2 Land and Water Contamination

Approach

The tiered approach to assessing risks from land and water contamination is set out in the UK Department for Environment, Food and Rural Affairs (DEFRA) and EA publication Model Procedures for the Management of Land Contamination CLR115. This considers potential contamination sources at the landfill, pathways and receptors in order to identify potential contamination linkages.

Contaminants would include potentially harmful substances in the wastes, soils, sediments, surface waters and groundwater.

Amec Foster Wheeler’s approach to undertaking land and water contamination risk assessment is based on a tiered framework in accordance with CLR11, as outlined in Table 2.1.

Table 2.1 CLR11 Tiered Framework

Tier Description

Tier 1: Preliminary Risk Assessment

Development of a conceptual model; Preliminary Risk Assessment examining potential contaminants, pathways and receptors to identify the potential ‘contaminant linkages’; Identification of further risk assessment requirements.

Tier 2: Generic Quantitative Risk Assessment (GQRA)

Screening of analytical results against GAC for soils and groundwater including Soil Guideline Values, Environmental Quality Standards, etc., to identify issues that require more detailed consideration; Identification of further risk assessment or risk management requirements.

2 Chapter 62-777 contaminant clean-up target levels. Florida Department of State, 2005. 3 DEFRA – Water Framework Directive Implementation in England and Wales: New and Updated Standards to Protect the Water Environment. May 2014. 4 H1 Annex A – Amenity & accident risk from installations and waste activities. v 2.1, Environment Agency, December 2011 5 Model Procedures for the Management of Land Contamination – Contaminated Land Report 11. Environment Agency, September 2004


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Tier Description

Tier 3: Detailed Quantitative Risk Assessment (DQRA)

Refinement of site conceptual model which may require the collection of additional data; Application of detailed quantitative risk assessment procedures in accordance with Environment Agency Guidance to further assess potential contaminant linkages:

With respect to human receptors this may involve assessment of site specific exposure scenarios taking into account toxicological properties of substances to derive site specific assessment criteria (SSAC);

With respect to controlled water receptors this may involve simple analytical calculations of groundwater and/or surface water flow and contaminant attenuation to derive remedial target concentrations.

To undertake the assessment proprietary software such as the CLEA Software, RBCA or RAM may be used;

Identification of further risk assessment or risk management requirements.

In general the application of increased tiers of analysis will result in less conservative remediation targets resulting in less costly remedial action. Therefore the cost for increased tiers of assessment is justified where remediation liabilities are potentially high and less costly solutions can be established as acceptable by detailed risk assessment.

The land and water contamination assessment for the landfills provided within this report is generally based upon a Tier 2 assessment. For the George Town Landfill some historic quantitative monitoring data is available, particularly for surface waters and groundwaters, in addition to that obtained from the recent investigation work. For Cayman Brac and Little Cayman landfills there is very little pre-existing monitoring data prior to the recent investigations.

The contaminant-pathway-receptor relationship allows an assessment of potential environmental risk to be determined based on the nature of the source, the degree of exposure of a receptor to a source and the sensitivity of the receptor. On this basis an assessment is made of the environmental liabilities associated with the risk. These can be expressed, for example, in terms of:

Additional costs associated with site redevelopment or remedial measures;

The potential for costs, fines or penalties imposed for breaches of environmental legislation or third party claims; and

Loss of land value.

Assessment Standards

Florida Administrative Code

Within this report, as part of a Tier 2 risk assessment, chemical analysis data for soils and groundwater are compared with GAC, for determinands where values are available, in order to identify contaminants of concern and determine whether further assessment of risks is required.

The assessment criteria used depends upon the source media (soil, groundwater) and the receptor under consideration. The GAC used in this study are those produced under the FAC chapter 62-777 contaminant clean-up target levels from 2005, referenced on the previous page of this report and available at: http://www.dep.state.fl.us/waste/quick_topics/rules/documents/62-777/62-777_TableI_GroundwaterCTLs.pdf

These are derived based on human health receptors. They are considered to be those which are most directly relevant to the Cayman Islands considering geography, climate and given that the FACs also consider marine surface water criteria which is an important factor for the islands.

UK Proposed Standards to Protect the Water Environment

There are no Florida marine surface water assessment criteria for nutrients including ammonia, nitrate/nitrite and phosphorous. Elevated nutrients have the potential to cause eutrophication with an accelerated growth


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of algae. Ammonia is also toxic to fish at relatively low concentrations. The proposed UK standard6 for unionised ammonia (NH3-N) in marine waters is 0.021 mg/l (long term mean value). There is no proposed equivalent standard for total ammonia (NH4-N) in marine waters but that for rivers is summarised in Table 2.2. The values are appropriate for ‘Type 7’ rivers which are those with alkalinity concentrations exceeding 200 mg/l CaCO3 which correspond with those recorded in the North Canal during April 2015 monitoring.

Table 2.2 Ammonia Standards in Type 7 Rivers (UK)

Type of Standard Total Ammonia (mg NH4-N/l)

High 0.7

Good 1.5

Moderate 2.6

Poor 6.0

UK proposed standards for orthophosphate (also known as reactive phosphorus) in rivers are summarised in Table 2.3. These standards are for lowland high alkalinity rivers (alkalinity >50mg/l CaCO3).

Table 2.3 Reactive Phosphorus Standards in Lowland High Alkalinity Rivers (UK)

Type of Standard Reactive Phosphorus/ Orthophosphate (mg/l)

High 0.0036

Good 0.069

Moderate 0.173

Poor 1.0

There are no specific water quality standards for UK rivers for nitrate but there are proposed assessment standards for groundwater contributions to wetlands. For a swamp/wet woodland the mean proposed annual threshold is 22mg/l.

US National Oceanic & Atmospheric Administration

The US National Oceanic & Atmospheric Administration (NOAA) have some screening quick reference tables see http://response.restoration.noaa.gov/sites/default/files/SQuiRTs.pdf which cover certain inorganic and organics in marine waters. The inorganics are mainly metals. The criteria are either acute or toxic.

Risk Assessment Criteria for Land and Water Contamination

The definitions of potential consequence and likelihood of a contamination linkage are defined in Table 2.4 together with the definition of the potential significance.

6 Water Framework Directive implementation in England and Wales: new and updated standards to protect the water environment. DEFRA, May 2014


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Table 2.4 Risk Assessment Criteria Land and Water Contamination

Potential Consequence of Contaminant Linkage

Severe Acute risks to human health. Short-term risk of pollution of sensitive water resource (e.g. major spillage into controlled waters). Impact on controlled waters e.g. large scale pollution or very high levels of contamination. Catastrophic damage to buildings or property (e.g. explosion causing building collapse). Ecological system effects – irreversible adverse changes to a protected location. Immediate risks.

Medium Chronic risks to human health. Pollution of sensitive water resources (e.g. leaching of contaminants into controlled waters). Ecological system effects – substantial adverse changes to a protected location. Significant damage to buildings, structures and services (e.g. damage rendering a building unsafe to occupy, such as foundation damage).

Mild Non-permanent health effects to human health. Pollution of non-sensitive water resources (e.g. pollution of non-classified groundwater). Damage to buildings, structures and services (e.g. damage rendering a building unsafe to occupy, such as foundation damage). Substantial damage to non-sensitive environments (unprotected ecosystems e.g. crops).

Minor/ Negligible Non-permanent health effects to human health (easily prevented by appropriate use of PPE). Minor pollution to non-sensitive water resources. Minor damage to non-sensitive environments (unprotected ecosystems e.g. crops). Easily repairable effects of damage to buildings, structures, services or the environment (e.g. discoloration of concrete, loss of plants in a landscaping scheme).

Likelihood of Contaminant Linkage

High likelihood An event is very likely to occur in the short term, and is almost inevitable over the long term OR there is evidence at the receptor of harm or pollution.

Likely It is probable than an event will occur. It is not inevitable, but possible in the short term and likely over the long term.

Low likelihood Circumstances are possible under which an event could occur. It is by no means certain that even over a longer period such an event would take place, and less likely in the short term.

Unlikely It is improbable that an event would occur even in the very long term.

Potential Significance

Very High Risk Severe harm to a receptor may already be occurring OR a high likelihood that severe harm will arise to a receptor, unless immediate remedial works/mitigation measures are undertaken.

High Risk Harm is likely to arise to a receptor, and is likely to be severe, unless appropriate remedial actions/mitigation measures are undertaken. Remedial works may be required in the short term, but likely to be required over the long term.

Moderate Risk Possible that harm could arise to a receptor, but low likelihood that such harm would be severe. Harm is likely to be medium. Some remedial works may be required in the long term.

Low Risk Possible that harm could arise to a receptor. Such harm would at worse normally be mild.

The potential significance for each Contaminant Linkage is calculated from the following matrix (Table 2.5).


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Table 2.5 Potential Significance of Contaminant-Receptor Linkage Matrix

Likelihood

High Likelihood Likely Low Likelihood Unlikely

Po

ten

tial

co

nse

qu

ence

Severe Very High High Moderate Moderate/Low

Medium High Moderate Moderate/Low Low

Mild Moderate Moderate/Low Low Negligible

Minor or Negligible

Moderate/Low Low Negligible Negligible

It is generally accepted that risks identified as moderate or higher would require further investigation, assessment or remediation.

2.3 Air Quality Modelling

Surface emission rates of landfill gas (LFG) from the active George Town landfill area have been estimated from use of a GasSim (v2.5) model and these have been used in a dispersion model to estimate ambient concentrations of LFG at sensitive residential receptors (Lakeside Development and Parkside Close) downwind of the landfill. GasSim simulates the fate of landfill gas arising from managed or unmanaged landfill sites and was developed for the UK Environment Agency (EA). The model uses information on waste composition and quantity, landfill engineering, and landfill gas management techniques to enable assessment of the best combination of control measures for a particular design and rate of filling.

From a review of the data on trace components contained in the landfill gas (LFG), acquired by on-site measurements in April 2015, ambient concentrations of trace components, including, for example, hydrogen sulphide and a range of volatile organic compounds, some of which are halogenated, were also estimated at these receptor locations.

Estimates of the emission of odour from the active landfill surface were taken from a recent research study in the UK7 and this was also applied in a dispersion model to assess the likelihood of odour nuisance being experienced at the above receptors as a result of surface emissions of LFG.

2.4 Amenity Risk

The amenity risk assessment approach is based on the identification of a hazard, receptor and pathway. It then considers risk management, probability of exposure and consequence, together with a summary of overall impact. Amenity risk is based on identification of a potential hazard or nuisance, for example landfill fires, for which there are no generic assessment criteria.

Risk Assessment Criteria for Amenity Risk

Table 2.6 summaries the headings for amenity risk assessment evaluation based on UK EA H1 Annex A guidance.

7 SNIFFER (2013) Odour Monitoring and Control on landfill Sites. http://www.sniffer.org.uk/files/2813/7476/3982/ER31_Final_Report.pdf


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Table 2.6 Assessment Approach for Amenity Risks

Hazard Receptor Pathway Risk management

Probability of Exposure

Consequence Overall Impact

E.g. landfill fires

Residents in Lakeside development

Air, receptor downwind of site

None currently High likelihood Waste or tyre combustion products in smoke

High

The risk matrix for amenity risks is presented as Table 2.7.

Table 2.7 Amenity Risk Matrix

Consequence → ↓ Probability

Very Low Low Medium High

Very Low Low Low Low Low

Low Low Low Medium Medium

Medium Low Medium Medium High

High Medium Medium High High


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3. Environmental Condition George Town Landfill

3.1 Location and Setting

Location

The George Town landfill is located to the north of central George Town towards the western coast of Grand Cayman as shown on Figure 1. It is owned by Cayman Islands Government (CIG) and operated by the Department of Environmental Health (DEH). The total site area is approximately 73 acres (30 hectares) in extent and the site boundary is identified on Figure 1. The majority of the site has historically received inputs of waste materials, the exceptions being the western margin of the site, to the west of Esterley Tibbetts Highway and the north-west margin of the site, to the north of the dyke/canal.

The landfill is predominantly a land raise formed by tipping over an area of former mangrove swamp which was partially excavated to recover the underlying marls (calcareous soils). The site has no formal engineered containment (i.e. a basal lining system). Part of the site is capped with a thin layer of soil materials and has re-vegetated in some areas.

Topography

The land surrounding the landfill is mainly flat lying and where developed is formed from reclamation of former mangrove swamp. The height of land surrounding the landfill varies between approximately 2 and 5 feet (0.6-1.5m) above mean sea level (MSL). The highest part of the landfill is at approximately 80 feet (24.4m) above MSL. An updated topographical survey has recently been completed at the site and the output was received shortly before issue of this report.

Surrounding Land Use

The land usage surrounding the landfill is summarised below, with reference to the Task 1 environmental review:

Immediately to the north of the site is a tidal drainage channel which connects with North Sound to the east. The area immediately north of the drainage channel is mangrove swamp. The Cayman International School and Camana Bay development are located approximately 0.2 miles (325 m) and 0.55 miles (880 m) north of the landfill respectively.

Beyond the eastern boundary of the site is land owned by Cayman Water Authority and comprises four large former wastewater treatment lagoons, two of which are still used for sludge storage. The lagoons are lined and variously sludge and water filled. To the south of the lagoons is the current wastewater treatment plant including some buildings and four smaller basins. Some 0.1-0.2 miles (160- 320m) east of the landfill site is land zoned for industrial use. This is mainly undeveloped or used for open storage. DEH lease some land to the east of the wastewater treatment lagoons which is used for storage of waste collection vehicles.

To the south of the site is an area of mangrove with industrial and commercial development beyond. This land is occupied by a variety of businesses, including a concrete batching plant.

Esterley Tibbetts Way (which is the main arterial road to West Bay) is immediately adjacent to the fence line forming the western boundary of the site. The Lakeside residential development is located west of the road and approximately 330 ft (100m) from the landfill boundary and a further 610 ft (185m) from the area currently used for active landfilling of waste. This development comprises a number three-storey residential apartments with car parking and leisure/landscape areas (including a small lake). The landfill is visible from the upper storeys of the lakeside buildings.


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Site History and Infrastructure

The history of development of George Town landfill and a description of infrastructure at the site is described in the Task 1 environmental review.

Climatological Information

General climatological information for Grand Cayman is provided in the Task 1 environmental review and summarised in Table 3.1.

Table 3.1 Meteorological Summaries for Grand Cayman

Month Average Rainfall (inches)a

Average Wind Speed (mph)b

Average Wind Direction

Average Temperature (oF)

January 1.68 11.3 ENE 77.3

February 2.88 9.6 ENE 77.2

March 7.42 9.9 ENE 78.4

April 20.36 10.2 ENE 80.0

May 3.56 8.6 E 81.7

June 1.69 8.9 E 83.3

July 11.51 8.8 E 83.9

August 5.35 8.4 E 83.6

September 3.85 6.7 E 83.1

October 0.71 9.8 ENE 81.8

November 1.97 11.4 ENE 80.7

December 3.36 9.7 ENE 78.7

Sources: a. Cayman Islands Government National Weather Service 30-year average for Georgetown, Grand Cayman Island. b. Cayman Islands Government National Weather Service 21-year average for Georgetown, Grand Cayman Island.

Some specific meteorological data was provided by the National Weather Service to cover the period of the Task 2 fieldwork and this is presented in the Task 2 factual report.

Waste Composition and Inputs

The 2011/12 waste composition and input data for the site is provided in the Task 1 environmental review. The waste input into the George Town site in the year ending June 2014 is estimated by DEH at 62,400T. Weighbridge data from March and July 2015 indicates that historical tonnage data reported from George Town landfill may underestimate the actual tonnages received. The projected input at George Town derived from the March to July weighbridge data indicate an increase to around 73,500T for 2015.

Geological Setting

The geology in the vicinity of the George Town site is described in the Task 1 environmental review and is summarised in Table 3.2.


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Table 3.2 Geological Succession George Town Landfill Area

Elevation (ft) and (m) Thickness (ft) and (m)

Period Series Formation

+1.5 to +4.0ft/ +0.45 to +1.2m 2.5ft/ 0.75m Made ground Made ground Imported fill

0.0 to +1.5ft/ 0.0 to +0.45m 1.5ft/ 0.45m Quaternary Holocene Peat (swamp deposits)

0.0 to -3.0ft/ 0.0 to -0.9m 3.0ft/ 0.9m Quaternary Pleistocene Ironshore Formation (calcareous marl)

-3.0 to -7.5ft/ -0.9 to -2.3m 4.5ft/ 1.4m Quaternary Pleistocene Ironshore Formation (very soft friable limestone)

-7.5 to -25ft/ -2.3 to -7.6m 17.5ft/ 5.3m Quaternary Pleistocene Ironshore Formation (soft friable limestone and marl bands)

-25 to -45ft/ -7.6 to -13.7m 20ft/ 6.1m Tertiary Oligocene- Pliocene Pedro Castle Formation (hard dolomite and limestone)

-45 to >-300ft/ -13.7 to >-91.4m

>250ft/ >76m Oligocene- Pliocene Cayman Formation (dolostone)

Four new groundwater monitoring wells were completed around the margin of the landfill site as part of the Task 2 investigation works. These were rotary drilled by open hole methods (i.e. no cores were recovered). As assessment of the strata was made by Amec Foster Wheeler based on the drilling rate and flush returns.

These wells proved the following:

Made Ground (landfilled wastes of soil with varying amounts of wood, plastic, textile, rubber and metal) to depths of between 4 and 11.8 ft (1.2-3.6 m) below ground level (bgl); overlying

A limestone bedrock, anticipated to form part of the Ironshore Formation, which was typically recovered as coarse sand to coarse gravel-sized grey/white fragments of limestone and coral. The full depth of the limestone was not determined, with all boreholes drilled to approximately 30 ft (9.1m) bgl.

3.2 Data Sources

Previous Environmental Reports

Post, Buckley, Schuh & Jernigan 1991

An environmental assessment of the Grand Cayman Sanitary Landfill (now known as the George Town Landfill) was undertaken in 1991 (reporting date uncertain) by Post, Buckley, Schuh & Jernigan (PBS&J)8. This included the installation of eight groundwater monitoring wells around the landfill site. The study included groundwater level monitoring and sampling with level data reviewed against tidal cycles. The sampling and analysis of waters was also undertaken in some of the ditches around the landfill (these are also known as ‘canals’) including the discharge from the northern canal into the North Sound. Some limited sediment sampling from the ditches and North Sound was also undertaken. Information from this study is summarised in the Task 1 environmental review.

8 Environmental Assessment of Grand Cayman Sanitary Landfill, Grand Cayman Island, BWI. Post Buckley, Schuh & Jernigan Report for CIG, 1991? (Electronic copy with no cover/issue sheet).


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Cardno ENTRIX 2013

In April 2013 Cardno ENTRIX submitted a draft Environmental Statement (ES) for a proposed alternative landfill site on Grand Cayman9. Although this is primarily concerned with a proposed new landfill site near Bodden Town it also contains some reference to the baseline or ‘no action alternative’ of the George Town Landfill (section 4.1.2 of the ES). The ES provides a summary of water quality in the vicinity of George Town Landfill based on information provided by DEH for the period 2006-2010. It also provides a summary of DoE sampling of water quality in North Sound for the period 2003-2012. Annex F6 of the ES includes a short marine environmental evaluation report for the George Town landfill.

Pre-Existing Environmental Monitoring Data

Department of Environmental Health

DEH has provided six sets of monitoring data for surface water and groundwater in the vicinity of the landfill for the period 2006 to 2013 which is when they last undertook the monitoring. Sampling is only undertaken once every one or two years. The position of sampling locations is shown on Figure 2. In addition to water samples some soil samples have previously been taken and analysed from the sides of some of the ditches and adjacent to some monitoring well locations.

Department of Environment

DoE has provided biannual water quality data for North Sound for the period 2006 to 2012 and a single record for January 2013. It is noted that the marine water quality sampling has a limited suite of determinands and no sampling was undertaken in 2014 or 2015 to date.

Other Environmental Data

There is no known landfill gas or air quality monitoring data for the landfill site.

3.3 Hydrogeology

Regional Setting

A summary of the regional hydrogeology is provided in the Task 1 environmental review.

Abstractions

There are no known groundwater abstractions in the immediate vicinity (<1000 ft/ 300m) of the landfill. Water Authority Cayman operates two reverse osmosis plants at its Red Gate Road Water Works for municipal water supply. The works are located approximately 1.0 miles (1.6 km) south-east of the landfill. The plants take saline groundwater from feed water wells cased to 100 ft (30m) depth bgl, open zone from 100ft (30m) to 150ft (45m) or 160ft (48m) bgl. Brine disposal wells on the same site are cased to 210ft below ground level with an open zone from 210ft to 300ft (63m–90m).

Caribbean Utilities Company (CUC) abstract groundwater for cooling purposes at their site off North Sound Road/Sparkys Drive some 0.7miles (1.1km) south-east of the landfill.

Groundwater Levels

In 1991 PBS&J carried out monitoring of groundwater levels in wells located around the landfill site in relation to tidal cycles. A well within the central part of the site (Well 5) was shown to have a head difference of between 0.45ft (0.14m) and 0.68ft (0.2m) (mean 0.56ft/ 0.17m) above the corresponding tidal level in

9 Grand Cayman Waste Management Facility – Draft Environmental Statement. Cardno ENTRIX report for Dart Cayman Islands, April 2013.


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North Sound, the groundwater levels exhibiting a tidal lag. The amplitude of tidal fluctuations in North Sound were 1.2 times that at Well 5. PBS&J estimated a groundwater flow velocity of 12 feet (3.6m) per day from the landfill towards the North Sound.

As part of the Task 2 investigation data loggers were installed in monitoring wells MW8, MW9 and MW14 to record fluctuations in groundwater levels. In general, the data show groundwater variation on the order of 0.6 ft (0.18m) over a 24 hr period and are therefore similar to previous results obtained by PBS&J and indicative of tidal influence.

Groundwater Quality

1991 Investigation

In 1991 PBS&J carried out groundwater sampling and analysis from a number of wells around the landfill site. At that time only the eastern part of the current landfill was developed. Evidence of leachate contamination of groundwater was reported in Well MW3 located on the eastern boundary of the old landfill area (see Figure 2 for location). This was evidenced by elevated ammoniacal nitrogen (400 mg/l), total alkalinity and total organic carbon (TOC) with respect to other wells. Other wells recorded ammoniacal nitrogen concentrations of between 0.04 and 20 mg/l.

Sample analysis from Well MW3 also showed elevated lead, iron and chromium, as did MW5. Benzene, toluene, ethylbenzene and chlorobenzene were also present in MW3 at concentrations of 1.1 to 66 µg/l.

DEH Sampling 2006-2013

DEH undertake periodic sampling and analysis of the groundwater monitoring wells and up to a maximum of six data sets are available for this period. The groundwater monitoring network has been degraded as the landfill footprint has expanded with time and the number of effective monitoring wells has reduced. Wells MW 5, 8, 9, 13, 14, 15, 16 and 18 (see Figure 2 for location) were available for sampling by DEH during the last monitoring round in 2013. In total there are 34 data sets for the period. Wells 16, 17 and 18 were installed in December 2010.

Amec Foster Wheeler Sampling 2015

Amec Foster Wheeler undertook sampling from existing groundwater wells MW 8, 9, 11, 13 and 14 and new wells MW15A, 19, 20 and 21 installed as part of the Task 2 investigation work. Wells 5, 15 and 18 have been lost since the last DEH monitoring round. Well MW16 was not sampled as it contained free product hydrocarbons.

Assessment Criteria

The 2006-2015 sample data has been screened against Florida clean-up standard for poor yield/low quality groundwater. These assessment criteria have been selected due to the brackish nature of the underlying aquifer. The results and assessment criteria are summarised in Appendix A. The nature of the groundwater is summarised below.

General Chemistry 2006-2013

The pH range of the groundwater is typically 7.1-7.6. Specific conductance (laboratory measurements) ranges from 2,000-24,000 µmhos/cm indicating a saline influence.

Ammonia (NH3) concentrations range from <1 to 150mg/l (MW11, 2011) but are generally <50mg/l. The Florida clean-up standard of 28mg/l has been exceeded on seven occasions. Orthophosphate concentrations range from <0.1 to 0.76 mg/l and nitrate (NO3-) plus nitrite (NO2-) up to 0.83mg/l. This data indicates the groundwater contains elevated nutrients.

Biochemical oxygen demand (BOD) concentrations are typically <40mg/l excepting one result of 1,800mg/l in MW15 in 2013. Chemical oxygen demand (COD) concentrations range up to 2,000mg/l. There are no assessment criteria for either determinand.


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Total dissolved solids range up to 13,000 mg/l and are typically 5,000 to 10,000 mg/l. The assessment criteria is 5,000 mg/l.

General Chemistry 2015

The field measurements of pH were in the range 6.7 to 7.1 which is a slightly lower range than that recorded on previous laboratory samples. Conductance ranged from 4,800uS/cm in new monitoring well MW19 near the site entrance to 29,750 uS/cm in MW11 on the eastern margin of the site. Groundwater ammonia varied from 4.4 to 270 mg/l with results from individual wells detailed in Table 3.3 and shown on Figure 2.

Table 3.3 Ammonia in Groundwater 2015

Monitoring Well

MW8 MW9 MW10 MW13 MW14 MW15A MW19 MW20 MW21

Ammonia (mg/l) 28 8 41 9 16 14 4.4 6.6 270

Grey highlighting denotes exceedance of Florida clean-up standard

The Florida clean-up standard of 28 mg/l has been exceeded in MW10 and new monitoring well MW21 which had the highest result yet recorded at the site. Ammonia concentrations are shown on Figure 3. As the groundwater is considered to be in hydraulic conductivity with surface water, the groundwater from all monitoring wells would be regarded as ‘poor’ in respect of ammonia when compared to UK river quality standards (Table 2.2).

Orthophosphate concentrations are shown in Figure 4 and range up to 1.2 mg/l and in some wells exceed concentrations recorded previously. Nitrate (NO3-) plus nitrite (NO2-) concentrations were in all cases recorded below detection level (<0.2mg/l).

COD in groundwater in April 2015 monitoring was typically up to 250 mg/l but recorded at 1,000 mg/l in new monitoring well MW21.

Metals 2006-2013

The majority of metal analysis have returned results below laboratory limits of detection (LoD). Only iron has been detected above the clean-up level of 3 mg/l with results ranging up to 11 mg/l. Magnesium has been recorded at concentrations of up to 530 mg/l reflective of a saline influence.

Mercury has not been detected above the laboratory LoD of 0.02 mg/l in any of the samples. The maximum lead and chromium concentrations of 0.05 mg/l and 0.035 mg/l respectively are below the assessment standard.

Metals 2015

Results are similar to previous observations with the majority of metals present below LoD or at very low concentrations well below the assessment criteria.

Volatile Organic Compounds (VOC) 2006-2013

All VOC results have been less than the LoD excepting carbon disulphide (one sample) and 1,4 dichlorobenzene (two samples) at <3µg/l (LoD is 1µg/l). A concentration of 8.5 µg/l chlorobenzene was recorded in MW10 in 2011.

Volatile Organic Compounds (VOC) 2015

All VOC results from 2015 (5 samples) were less than the LoD.


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PCBs 2006-2013

Polychlorinated Biphenyls (PCB) analysis has been undertaken on 19 groundwater samples. All results are less than the LoD.

PCBs 2015

All PCB analysis results (5 samples) were less than the LoD.

Pesticides/Herbicides 2006-2013

Analysis for a number of pesticide/herbicide compounds has been undertaken on 7 groundwater samples. All results are less than the LoD.

Pesticides/Herbicides 2015

Analysis of 5 samples gave results that were all less than the LoD

Hydrocarbons 2011-2013

Diesel range organics analysis (DRO) has been undertaken on 7 samples of groundwater from 2011 to 2013. Results range from <1 to 3.8mg/l in MW18 in 2013.

DEH has noted that significant hydrocarbon release occurred from the waste oil storage area in 2004 as a consequence of the tidal surge associated with Hurricane Ivan overtopping the containment bund. Oil contamination of the perimeter canals is understood to have occurred, which was subsequently remediated.

Hydrocarbons 2015

DRO was undertaken all samples of groundwater. Results were typically in the range 0.07 mg/l to 1.5 mg/l with an outlier of 18 mg/l in new monitoring well MW21. Gasoline range organic analysis (GRO) was also undertaken on all samples which recorded concentrations below the limit of detection with the exception of new monitoring well MW21 which recorded 0.3mg/l. There is no Florida state assessment standard.

For the purpose of data contextualisation, the WHO guidance10 states that the application of the lowest WHO guideline value for (aliphatic) hydrocarbons (0.3 mg/l for carbon bands C12-C16, i.e. ‘diesel range’) to a total hydrocarbon measurement in water will provide a conservative level of protection. This guideline value has been exceeded in all of the 2015 samples except MW13.

Phenol and Tributyltin 2015

Two groundwater samples were tested for both phenol and tributyltin. Results for both compounds were recorded below the relevant LoD.

3.4 Hydrology

Drainage Network

There is a dyke or canal located along the western margin of the site which aerial photography and site observation would suggest connects with a similar channel located parallel to the northern boundary of the landfill. The northern canal is open to North Sound which is located approximately 2,000 ft (600m) beyond the eastern boundary of the landfill. The water level within these canals will fluctuate with the tide; the tidal variation in the North Sound recorded by PBS&J in 1991 was in the order of 0.8 ft (0.24m). Data from an IOC sea level monitoring station at George Town indicates the tidal variation in North Sound at the time of water sampling on 14 April 2015 was approximately 1 ft (0.3 m). The depth of the canals are such that they will be

10 Petroleum Products in Drinking-water, Background document for development of WHO Guidelines for Drinking-water Quality, WHO (WHO/SDE/WSH/05.08/123).


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in hydraulic conductivity with groundwater. The northern channel has a piped connection below Esterley Tibbetts Highway. The drainage channels are fringed with mangroves.

Historical maps and aerial photographs show that canals also once crossed the landfill site. These canals were created to allow tidal flooding as part of mosquito control practices. Parts of the western margin of the North Sound have previously been subject to marine dredging to supply marl for land reclamation purposes. This includes the area to the east of the landfill site.

A surface water runoff interception trench is constructed along the northern toe of slope of the main landfill area. This trench was constructed to intercept run-off during storm events and prevent any flow direct into the drainage canal just beyond the northern boundary of the site. It was dry during the site inspections in November 2014 and April 2015 but it contains water on occasions as it is included in the DEH monitoring programme.

Within the landfill site are some areas of standing water, mainly in the northern part of Hurricane Ivan fill area. This water was estimated at up to 1 ft (0.3 m) deep in April 2015 and there is visual evidence of contamination by leachate. A sample was taken for analysis and data is reported below. It is noted the amount of standing water had reduced significantly since the site inspection in November 2014; this is consistent with the April 2015 sampling being undertaken at the end of the dry season on the islands.

Surface Water Quality

1991 Investigation

PBS&J carried out some surface water quality monitoring of the canals within and adjacent to the landfill in 1991. The canals within the site have since been removed by sub-water table excavations to recover marl and limestone and the resultant void filled with waste materials.

The findings of the monitoring are summarised as follows:

The surface water was brackish;

Elevated levels of nutrients were detected, including ammoniacal nitrogen up to 5.5 mg/l but generally <1 mg/l;

None of the metals tested were above laboratory LoDs;

Organic constituents were similar to those recorded in groundwater; and

Benzene and toluene were detected at one of the locations within the site.

DEH Monitoring Programme – Perimeter Canals 2006 to 2014

DEH has carried out monitoring of surface water quality at the following locations (as shown on Figure 5):

SW12 on the western canal adjacent to the hazardous waste store;

SW3 on the northern canal adjacent to Esterley Tibbetts Way,

SW2 on the northern canal adjacent to the eastern margin of the landfill; and,

SW1 on the northern canal near the intersection with North Sound.

SW1, SW2 and SW3 have each been monitored on 5 occasions between 2006 and 2013 and SW12 on 3 occasions between 2010 and 2013.


Amec Foster Wheeler undertook surface water sampling in April 2015 at the same four locations historically sampled by DEH.


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Additional samples were taken at:

SW20 (in the north canal on the eastern boundary of the wastewater treatment works);

Pond (a pond lying to the south of the track by the North Canal adjacent to North Sound); and

Leachate (a shallow surface water pond on the landfill).

Locations are identified on Figure 5. Three further samples were taken in North Sound and are reported in the marine water quality section below.

Assessment Criteria

The data from DEH and Amec Foster Wheeler sampling (excepting that for the leachate sample) has been screened against the Florida marine surface water clean-up targets as the canal surface water is in direct continuity with the North Sound. The data and screening criteria are summarised in Appendix B. Time series plots for BOD, COD ammoniacal nitrogen turbidity and suspended solids are included in Appendix C1.

The following summary can be drawn from inspection of the surface water quality results and associated graphical plots.

General Chemistry

The pH range of canal water recorded on lab samples up to 2013 is typically 7.3-8.2. The pH field monitoring in 2015 recorded values of between 6.9 and 7.8. Specific conductance on lab samples up to 2015 ranges from 22,000-130,000 µmhos/cm indicating saline conditions. Field conductivity values recorded in April 2015 range for 13,920 µS/cm at SW12 to 50,270 µS/cm at the canal mouth with North Sound reflecting increasingly saline conditions from west to east.

The BOD recorded in the canals during the 2015 sampling was in the range 10-15 mg/l. The spatial distribution including samples taken in North Sound is shown on Figure 6. Previously recorded (up to 2013) BOD concentrations were up to 30mg/l in the perimeter canals. COD concentrations have historically been recorded up to 11,000mg/l but did not exceed 270mg/l in the April 2015 sampling. Total dissolved solids typically range up to 30,000mg/l. There are no marine water assessment criteria for any of these determinands.

Historical ammonia concentrations up to 2013 range from 0.3 to 13 mg/l. The April 2015 sampling identified concentrations of between 2.0 and 6.5 mg/l in the perimeter canals. The spatial distribution of ammonia in surface water including samples taken in North Sound is shown on Figure 7. The observed ammonia concentrations in the perimeter canals reflect poor water quality based on UK guideline values.

Previously recorded orthophosphate concentrations range up to 0.44mg/l (SW1 in 2013). Concentrations recorded in April 2015 are shown on Figure 8 and were a maximum 0.12mg/l. On the basis of the recent round of data, the observed orthophosphate concentrations reflect moderate water quality based on UK guideline values. Nitrate plus nitrite concentrations were below the LoD in the canal samples.

These data indicates the canal water contains elevated ammonia and orthophosphate but to a lesser extent than in groundwater.

Turbidity is recorded for which there is a Florida marine water clean-up standard of 29 NTU. This has been exceeded on 6 occasions with 2 occasions each at SW1, SW2 and SW3. The maximum recorded value was found at SW3 the canal adjacent to Esterley Tibbets highway at 240 NTU in 2011. At SW1, the outfall to North Sound, a maximum value of 94 NTU was measured in 2010.

Metals

The majority of metal analyses have returned results below laboratory LoDs. Only iron has been detected above the clean-up level of 3 mg/l, on one occasion at SW1 in 2006 and at SW12 in 2010, when elevated chromium was also recorded. Magnesium has been recorded at concentrations of up to 1400 mg/l, which is representatives of a saline influence.


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Mercury has not been detected above the laboratory LoD of 0.02 mg/l in any of the samples. The lead concentrations have not exceeded LoDs.

Dissolved Metals

Dissolved metals analysis was undertaken on samples from SW2, SW3 and SW20. These results have been compared against the total metals analysis and show fairly good agreement. This indicates that much of the concentration of individual metals within the samples is in a dissolved state. The sample from SW3 was analysed for dissolved metals only and recorded exceedences of the relevant clean-up levels for copper and lead.

Volatile Organic Compounds (VOC)

All VOC results from the two samples analysed in 2015 (SW1 and SW3) were less than the LoD. Of the total 21 data sets for sample analysis between2007-2015 all record LoD excepting 13 µg/l of methyl ethyl ketone measured in the sample from SW12 in 2013. The relevant LoD is 10 µg/l.

PCBs

PCB analysis has been undertaken on 14 surface water samples. All results are less than the LoD.

Pesticides

Analysis for a number of pesticide compounds has been undertaken on 6 surface water samples. All results are less than the LoD.

Hydrocarbons

DRO analysis has been undertaken on 7 samples of surface water. Results range from 0.33 to 0.84 mg/l measured in the sample from SW12 in 2013. Two samples for the April 2015 sampling were also tested for GRO and returned results below LoD.

For the purpose of data contextualisation, WHO guidance states that the application of the lowest WHO guideline value for (aliphatic) hydrocarbons (0.3 mg/l for carbon bands C12-C16, i.e. ‘diesel range’) to a total hydrocarbon measurement in water will provide a conservative level of protection. This guideline value has been exceeded in the samples from SW2 (2011 sample) and SW12 (2011, 2013 and 2015 samples). The results from the SW1, SW3 and SW20 (2015 samples) were all below this limit.

DEH Monitoring Programme – Landfill Runoff Interception Trench

In addition to the surface water sampling described above sample SW7 is taken from the northern interception trench within the landfill area when this contains water. Samples have been taken at this location on 6 occasions during the period 2006-2013. The drain was dry during the sampling episode in April 2015. The reported results for ammonia concentrations range between 1.3 and 54 mg/l and are higher than those in the perimeter canals. Iron has been recorded above the marine water assessment criteria on one occasion. Other metal concentrations are below the assessment criteria. VOC concentrations have been less than detection with the exception of 5.2 µg/l carbon disulphide in 2007 (LoD is 2µg/l).

Marine Water Quality

Marine Ecology North Sound

A concise marine environmental evaluation report dated 201211 is included as an annex to the Task 1 environmental review. This reference notes dense turtle grass (Thallassia testudinum) observed three

11 Marine Environmental Evaluation Report for the George Town Landfill, MA Roessler & Associates, 25 May 2012 (Annex to Cardno ENTRIX draft Environmental Statement).


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quarters of the way into the mouth of the northern canal with the grass blades showing moderate epiphyte growth. Nutrients affect the epiphyte density of the sea grasses. A plume of solids from the canal is apparent in an aerial photograph within the report.

The evaluation report notes that approximately 60% of the North Sound is covered by well-developed beds of Thallassia testudinum.

DoE Sampling

DoE has carried out annual sampling of the water quality in the North Sound in the period 2006-2013 for a limited number of parameters. These are:

Conductivity, temperature, pH;

Salinity, dissolved oxygen, suspended solids;

Nitrate-nitrite, reactive phosphate;

Chlorophyll and faecal coliforms.

The following sample points are relevant to this study:

Station 11 in the middle of North Sound which should be representative of background marine water quality;

Station 14 near to the northern canal outfall with North Sound (similar to DEH sample point SW1 and Amec Foster Wheeler 2015 sampling point NS#1); and

Station 13 in North Sound beyond the northern canal outfall.

These locations are shown in Figure 5.

Time series plots for the period 2006-2015 for suspended solids, nitrate-nitrite, reactive phosphorous and chlorophyll for each of these stations are included in Appendix C2. The data shows:

Suspended solid concentration at station 14 are variable from <10 to 60mg/l. Those at station 11 are <5mg/l and indicate that solids leaving the canal system are rapidly dissipated.

Reactive phosphate and nitrate-nitrite concentrations at station 14 are several times those at stations 11 and 13. These data indicate that nutrients leaving the North Canal are rapidly dispersed and bio accumulated.

Chlorophyll levels at Station 14 are typically 5 to 60mg/m3, those at Station 13 <1 to 5 mg/m3 and those at Station 11 are <1 mg/m3. The data indicates that the nutrient loading of waters leaving the North Canal is causing some eutrophication in the adjacent part of North Sound.


Amec Foster Wheeler took water samples for analysis from four locations within North Sound on 13 April 2014. The locations are summarised in Table 3.4 and shown on Figure 5.

Table 3.4 Surface Water Sample Locations

Location Ref Location Description Note

NS#1 North Sound at outflow of North Canal Equivalent to DEH monitoring point SW1

NS#2 North Sound approximately 400 ft (123 m) from North Canal outflow




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Key analytical results are summarised in Table 3.5.

Table 3.5 North Sound Water Analysis April 2015 Key Parameters

NS#1 (SW1) NS#2 NS#3 NS#4 Trend NS#1 to NS#4

Alkalinity, Total - mg/l 200 160 140 120 Decrease

Ammonia - mg/l 2.5 1.1 0.51 <0.020 Decrease

BOD - mg/l 10 3.0 <2.0 <2.0 Decrease

COD - mg/l 260 200 200 200 Generally decrease

Chloride - mg/l 19,000 21,000 20,000 21,000 Similar

Nitrate Nitrite as N - mg/l <0.018 0.044 0.087 0.059 Variable

Nitrogen, Kjeldahl - mg/l 3.7 1.7 1.0 0.38 Decrease

ortho-Phosphate - mg/l 0.10 0.052 0.025 <0.015 Decrease

Salinity – ppth 31 34 34 36 Increase

Sulphate - mg/l 2,600 2,900 2,800 2,900 Variable

Total Dissolved Solids - mg/l 39,000 39,000 43,000 40,000 Variable

Total Organic Carbon - mg/l 10 7.5 4.5 2.7 Decrease

Total Suspended Solids - mg/l

23 20 12 11 Decrease

Turbidity – NTU 3.6 4.1 2.0 0.8 Generally decrease

Faecal coliform CFU/100mL

220 - 6 - Decrease

Dissolved Chromium – mg/l 0.014 0.017 0.012 - Similar

Dissolved Copper – mg/l 0.057 0.066 0.046 - Similar

Dissolved manganese mg/l 0.015 0.0094 0.0055 - Decrease

The final column of the table shows the general trend in concentrations from NS#1 to NS#4 i.e. from the canal mouth out into North Sound. The data shows that the canal is a source of ammonia, orthophosphate, BOD and COD but there is relatively rapid reduction of these parameters within a few hundred metres of the canal discharge into North Sound. Dissolved metal concentrations are very low throughout, and with the exception of chromium, copper and manganese generally below the LoD. The data suggests low levels of dissolved manganese in canal water but this is rapidly diluted in samples further out into North Sound.

Of the three metals recorded above LoD only copper has an assessment value of 0.0048mg/l (acute) based on the NOAA quick screening tables. This was exceeded at NS#1, NS#2 and NS#3.


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3.5 Soil and Biota Sampling

Sediment Sampling

1991 Sediment Investigation

PBS&J carried out some sediment sampling in 1991 within the canal to the north of the landfill and at a point in the North Sound approximately 2575 ft (785m) north of the canal discharge into the sound. The samples were tested for a limited suite of metals and PCBs, with the results summarised in Table 3.6.

Table 3.6 1991 Sediment Sample Results (4 samples)

Determinand SS4 North Canal on east landfill boundary

SS3 North Canal east of water treatment works

SS2 North Canal Outfall to North Sound

SS1 North Sound

Chromium mg/kg

6.72 6.6 4.84 <4

Iron mg/kg 962 816 495 298

Mercury mg/kg <0.02 <0.02 <0.02 <0.02

Lead mg/kg <5 <5 <5 <5

PCB mg/kg 179 2.1 <2 <2

The contamination gradient, based on very limited data, indicates the origin of the canal sediment contamination to be the landfill site.

Amec Foster Wheeler 2015

Amec Foster Wheeler took three sediment samples from the North Canal (SW2, SW3 and Sediment #4), two (which includes a duplicate) at the outfall of the north canal to North Sound (Sediment #1), and two within North Sound (Sediment #2 and Sediment #3). Sediment sample locations are shown on Figure 9.

All samples were tested for metals and four for PCBs and pesticides. Metals results are recorded at less than the LoD with the exception of the following:

Arsenic at 4.7 mg/kg at Sediment #2 in North Sound;

Chromium 63 mg/kg at SW2, 15-20 mg/kg at Sediment #1/duplicate and 4.3-4.5 mg/kg at Sediment #2 and #3;

Cobalt 2.4 mg/kg at SW2;

Copper 16-21 mg/kg at Sediment #1/duplicate, <4mg/kg in all other samples;

Lead 13-18 mg/kg at Sediment #1/duplicate and SW2, ≤5 mg/kg in all other samples;

Mercury max 0.092 mg/kg at SW2;

Nickel 6.4-10 mg/kg at Sediment #1/duplicate and SW2, <3 mg/kg in other samples;

Selenium 7.2-10 mg/kg at Sediment #1/duplicate and SW2, <4mg/kg in other samples;

Vanadium 33-44 mg/kg at Sediment #1/duplicate and SW2, <10 mg/kg in other samples; and

Zinc 55-73 mg/kg at Sediment #1/duplicate, <12 mg/kg elsewhere.


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No PCBs or pesticides were found above the LoD. Sulphate content was elevated at Sediment #1/duplicate at 8,100-9,300 mg/kg with the next highest reading being 3,800 mg/kg at SW2. The elevated sulphate could be a source of the hydrogen sulphide odour noted on occasion near the mouth of the north canal.

The values have been screened against the Florida soil clean up targets relating to leachability to marine water where assessment standards exist for chromium, mercury, nickel and selenium. The concentrations recorded for these metals area all less than the assessment levels with the exception of chromium where the standard was exceeded in SW2. However the standard is derived on the assumption that the chromium in in the hexavalent form, which is very unlikely. Hexavalent chromium was detected in canal surface water at SW2 but at a concentration several times below the Florida clean-up standard for marine surface water.

The US National Oceanic & Atmospheric Administration (NOAA) have some screening quick reference tables see http://response.restoration.noaa.gov/sites/default/files/SQuiRTs.pdf which cover inorganics in marine sediments. Taking the median values derived from Ecotoxicology 1996 Aug;5(4):253-78 which is development of guidelines for Florida coastal waters all results for the 2015 George Town canal samples are less than the screening values.

The metal concentrations in sediment have also been screened against the Florida soil clean-up levels for direct exposure to residential receptors. All concentrations are below these assessment criteria with the exception of arsenic in Sediment#2 which is 2.3 times the clean-up level. Elevated arsenic has also been proven in soils at the landfill site by DEH, see below.

Biological Sampling

1991 Investigation

PBS&J in 1991 collected samples of mangrove from the sides of the canal, algae and sea grass from the north canal at the point of discharge in to the North Sound and Turtle grass from a site in the North Sound. The sampling methodology is unknown. Mercury is reported in two mangrove samples at 50mg/kg (MS - 6/91) and 43.8mg/kg (MW-4 6/91) but these are believed to be erroneous results as it is the same result for iron in an adjacent column of the typed report table and was found at <0.02 mg/kg in a repeat sample MS-3 9/91 and in all other vegetation samples (MW-4 was not resampled). Chromium was detected in the algal sample (8.5 mg/kg) and iron in the Turtle grass sample SS-2 from the mouth of the north canal at 880 mg/kg which is above background.

PBS&J trapped some minnow-sized fish species within one of the canals north of the landfill area (this would have been relatively remote from the area of waste disposal at that time). Some mercury was detected (0.53mg/kg) which was above expected levels.

2015 Investigation

Amec Foster Wheeler collected four samples of mangrove and similar species leaf from trees fringing the canals/dykes around the western and northern perimeters of the site. The test suite was limited to selected metals, including mercury, and PCBs. The following were recorded above the relevant LoD:

Iron: 10-58 mg/kg

Chromium: up to 0.26 mg/kg

Lead: up to 1.4 mg/kg

Potassium: 370-3,500 mg/kg

All mercury and PCB test results were below the relevant LoD.

Five samples of marine vegetation were collected from the sea bed for analysis, two from the mouth of the north canal discharge to North South and four further samples (including one duplicate for sample ref: Manatee Grass #2) at locations further out into North Sound. The test suite was the same as that for the mangrove samples. The following were recorded above the relevant LoD:

Iron: 38-180 mg/kg


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Chromium: up to 1.3 mg/kg

Lead: up to 1.1 mg/kg

Nickel: up to 0.71 mg/kg

Potassium: 1,200-3,000 mg/kg

The higher chromium and nickel values were associated with algae at location NS#1 where the North Canal drains into North Sound. The presence of algae at this location is evidence of eutrophication around the canal discharge. All mercury and PCB test results were below detection.

There are no specific assessment standards for metals in marine vegetation.

Soil Sampling

DEH Soil Sampling 2011-2013

DEH has carried out some sampling of soils from the banks of perimeter canals. Samples were collected above the normal water level adjacent to some of the surface water sample locations and also from surface soils adjacent to some of the MW monitoring point locations. Forty datasets are available for the period 2011-2013. Data has been screened (Appendix D) against the Florida soil clean-up standards for both:

Direct exposure for commercial/industrial use and;

Leachability based on groundwater of low yield/poor quality (assessment criteria are available for a limited number of metals).

Metal concentrations are below the assessment criteria with the exception of arsenic which exceeded the Florida direct exposure clean-up criteria of 12 mg/kg at locations SW7, MW5 and MW13 with a maximum concentration of 60 mg/kg. It is noted the Florida clean-up standard for arsenic is exceptionally low when compared to UK assessment criteria for the same commercial/industrial use scenario (which is 640 mg/kg). Concentrations of up to 40 mg/kg are typical of background in the UK for naturally occurring soils, but this is expected to be less for the limestone derived soils on the Cayman Islands. Another potential source of soil arsenic is from the past burning of treated timber.

No metal values exceed the leachability criteria for groundwater of low yield/poor quality, but would exceed the criteria for leachability for marine surface water.

PCB test results (30 No) for soils are all below LoD. Pesticide suite test results (11 No) are also less than LoD with the exception of:

11 µg/kg 4.4,DDD at MW5 in 2013;

4.1 µg/l 4.4,DDE at MW5 in 2013, and

7.8 µg/l endrin aldehyde at MW15 in 2013.

These compounds are present at concentrations well below assessment standards for direct exposure or leachability to groundwater of poor quality.


Seventeen samples of surface soil were collected from across the Hurricane Ivan fill area for asbestos analysis. No asbestos was detected in any of the samples.

3.6 Landfill Gas

The site receives municipal wastes including organic materials such as food and kitchen wastes, garden wastes, paper, cardboard and timber and can therefore be expected to be producing landfill gas. This is typically a mixture of methane and carbon dioxide together with trace components such as hydrogen,


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hydrogen sulphide and volatile organic compounds including halogenated organics, aromatic hydrocarbons, alkanes and ketones12. The trace compounds present in landfill gas give it an odour.

Site Inspection 2014

There has been no landfill gas monitoring carried out at the site historically. Amec Foster Wheeler undertook some initial measurements during the site inspection on 14 November 2014 by monitoring methane and carbon dioxide concentrations on the landfill surface. The data is reported in the Task 1 environmental review, but in summary, methane concentrations of up to 0.8%v/v were recorded in surface cracks and fissures in the waste which confirms the site is actively generating landfill gas.

Gas Probes 2015

Gas monitoring and sampling was undertaken on 10 April 2015 from gas probes (GP1 to GP6) which were installed within the waste mass in April 2015. The gas probe locations are shown on Figure 10.

Landfill gas monitoring data collected prior to the gas sampling using the portable infra-red gas analyser is presented in the Task 2 investigation factual report. The data shows methane and carbon dioxide concentrations indicative of landfill gas (~50-60% methane and ~25-45% carbon dioxide) with no or little (~2% or less) oxygen in all probes except GP1, located in the north-east of the site adjacent to a haul road. GP1 showed much lower concentrations of methane (1.8% v/v) and carbon dioxide (1.5% v/v) and oxygen around atmospheric concentration (21.5% v/v).

The gas analysis suite consisted of bulk gas constituents (C1-C4 hydrocarbons, carbon dioxide, nitrogen, oxygen, hydrogen and helium) as well as hydrogen sulphide, carbon monoxide and non-methane volatile organic compounds (NMVOCs).

Gas analysis results are included in the Task 2 investigation factual report and are summarised as follows:

Carbon dioxide: 7.8 v/v (GP1) to 43% v/v (GP4) with all results above 30% v/v except GP1 and GP6;

Methane: 11% v/v (GP1) to 59% v/v (GP2) with all results at, or above, 50% except GP1;

Oxygen: 0.39% v/v (GP4) to 18% v/v (GP1) with all results <1% v/v except GP1 and GP6;

Nitrogen: 5.5% v/v (GP2) to 68% v/v (GP1) with all results below 10% v/v except GP1 and GP6;

Carbon monoxide, ethane, ethylene, helium, propane and propene: all results below relevant LoD;

Hydrogen: all results below LoD except GP6 (0.012% v/v);

Hydrogen sulphide: 0.46 ppm (GP1) to 2,300 ppm (GP3) with all results below 20 ppm except GP3 and GP5 (85 ppm);

NMVOCs: below LoD except:

1,2,4-Trimethylbenzene (16-850 ppb, all samples except GP6);

1,2-Dichloroethane (27-57 ppb, GP2, 3 and 5);

1,3,5-Trimethylbenzene (12-450 ppb, all samples except GP3);

2-Butanone (MEK) (44-13,000 ppb, all samples);

4-Methyl-2-pentanone (MIBK) 15-1,000 ppb, (GP1, 3 and 4);

12 Guidance on the Management of Landfill Gas. UK Environment Agency Landfill Technical Guidance Note (LFTGN) 03. September 2004.


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Acetone (2,100-44,000 ppb, all samples);

Benzene (150-2,200 ppb, all samples);

Benzyl chloride (17-590 ppb, GP1, 4 and 5);

Carbon disulphide (78-1,200 ppb, all samples);

Chlorobenzene (37-38 ppb, GP5 and 6);

Chloromethane (780 ppb, GP4);

cis-1,2-Dichloroethene (62-110 ppb, GP2 and GP5);

Dichlorodifluoromethane (38-460 ppb, GP4 and GP6);

Ethylbenzene (82-1,300 ppb, all samples);

m,p-Xylene (74-2,400 ppb, all samples);

Methylene Chloride (14-4,600 ppb, all samples except GP2);

o-Xylene (31-870 ppb, all samples);

Styrene (16-570 ppb, all samples except GP2 and GP3);

Tetrachloroethene (23 ppb, GP5);

Toluene (150-3,300 ppb, all samples);

Trichlorofluoromethane (40 ppb, GP6); and

Vinyl chloride (110-2,400 ppb, GP2 and GP6).

Concentrations of bulk LFG (methane, carbon dioxide, oxygen and nitrogen) are largely consistent with the pre-sampling field data, although the concentrations of methane and carbon dioxide detected in GP1 and the laboratory analysis are substantially higher than the field results, whereas the oxygen concentration is lower. After the pre-sampling field data was taken, each probe was pumped for approximately 5 minutes until readings stabilised to allow sampling. Therefore, the results of the sample analysis are likely to be much more representative than the pre-sampling field data.

The low/below LoD hydrogen concentrations recorded are fairly typical of a landfill in the long methanogenic stage of landfill gas generation.

The hydrogen sulphide concentrations recorded are typical of those usually measured in landfills, although the result from GP3 is around two orders of magnitude higher than the other results. It is possible that the higher concentration recorded in GP3 is attributable to sulphate-based wastes (typically gypsum) landfilled within the vicinity of the probe.

With regard to the NMVOCs, those detected above the relevant LoD are all typical trace components within landfill gas. Some of the trace compounds detected, such as carbon disulphide, toluene and xylene, as well as hydrogen sulphide, are odorous components of landfill gas.

3.7 Fugitive Emissions

Flux Boxes 2015

Flux box monitoring was undertaken on 11 April 2015 in three locations on the landfill surface, including two uncapped areas (Flux Box 2 and 3) and one capped area (Flux Box 1). The flux box monitoring followed the methodology set out in the Task 2 investigation factual report. The flux box locations are shown on Figure 10.

The results of the flux box testing are summarised as follows:


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Flux box 1: No methane was detected during the test (<0.1%). Carbon dioxide concentrations began at 0.1% v/v and increased to 0.2% v/v after 30 minutes. Oxygen concentrations remained around 22% v/v (i.e. atmospheric concentrations) throughout the test.

Flux box 2: No methane was detected during the test (<0.1%). Carbon dioxide concentrations began at 0.2% v/v and increased to 0.3% v/v after 5 minutes. Oxygen concentrations remained around 22% v/v throughout the test.

Flux box 3: No methane was detected during the test (<0.1%). Carbon dioxide concentrations began at 0.0% v/v and increased to 0.1% v/v after 1 minute, 0.2% v/v after 8 minutes, 0.3% v/v after 20 minutes and 0.4% v/v after 25 minutes. Oxygen concentrations remained around 22%v/v throughout the test.

The results show that there are no detectable methane emissions from the landfill surface, although this is based on results obtained with an infra-red landfill gas analyser with a methane detection limit of 0.1% v/v (1,000 ppm). There is an intention to repeat the survey in future using a portable laser methane analyser, which is capable of being air freighted onto the island and can detect methane at a much lower 1 ppm, when a suitable opportunity arises.

For the purposed of air quality modelling gas emission rates have been assessed using GasSim as noted in section 2.3.

Hydrogen Sulphide Monitoring 2015

Fugitive hydrogen sulphide measurements in air were undertaken on and adjacent to the George Town landfill site on 11 April and 18 April 2015, following the methodology set out in the Task 2 investigation factual report. The weather conditions during the duration of each survey was as follows:

11 April wind direction from 700 to 900 at 5-8 knots, 25-27oC;

18 April wind direction from 1200 at 6 knots, 28oC

The survey results for each day are presented on Figures 11 and 12. The results show the following:

The first survey, on 11 April 2015, was undertaken across and around the landfill, at the site entrance, along the North Canal to North Sound and at other off-site locations including the Lakeside development to the west, the International School to the north and the AL Thompson store to the south. The highest result of 195 ppb was on the eastern landfill boundary adjacent to the wastewater treatment facility, with the next highest result of 179 ppb recorded at the mouth of the North Canal into North Sound.

Of the 66 locations surveyed on 11 April, around one third (including the Lakeside Development and the International School) were 0 ppb and around half of the results were between 1 and 10 ppb (the AL Thompson store was 6.65 ppb). There were only 3 locations where >100 ppb hydrogen sulphide was detected, which were all either adjacent to the North Canal or the landfill boundary with the wastewater treatment facility.

In general, the highest readings taken on the landfill were in the north-eastern part, which is adjacent to the wastewater treatment facility. The highest readings on the North Canal were away from the landfill, adjacent to the North Sound, and the concentrations fell sharply when moving away from the canal mouth back towards the landfill. The highest reading within the landfill, away from the boundaries, was 80.16 ppb, recorded near the top of the landfill adjacent to a large open pit used for disposal of animal carcasses and other difficult waste.

The second survey, on 18 April 2015, was undertaken in fewer locations than the first survey, concentrating on areas where the higher results were recorded in the first survey, as well as the North Canal, Lakeside Development and International School. The highest result of 8.06ppb was recorded near GP1 in the north-east of the landfill, adjacent to the boundary with the water treatment works.

Of the 23 locations surveyed on 18 April, some 14 locations (including the Lakeside Development, the International School and the AL Thompson store) were 0 ppb and the


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remainder of the results were between 1 and 10 ppb. At the mouth of the North Canal, a concentration of 5.7 ppb was recorded, with the only other two positive results along the north canal recorded north of the water treatment works to the north-east of the landfill.

By way of comparison, the WHO guideline value13 for hydrogen sulphide for preventing odour nuisance is 7µg/m3, which equates to 4.66 ppb. This value was exceeded in around two-thirds of the results from the first survey and three of the results from the second survey. The WHO long-term and short-term average guideline values are 140 µg/m3 and 150 µg/m3 respectively, which equate to 93.3 ppb and 100 ppb respectively. These guideline values were exceeded in three locations in the first survey, which were all either adjacent to the North Canal or the landfill boundary with the water treatment works, but in no locations during the second survey.

Dust Sampling and Deposition Monitoring 2015

The landfill is a potential source of fugitive dust emissions. Some areas of waste are covered but there are large areas of exposed waste.

Dust sampling was undertaken in two locations (DM1 and DM2) in accordance with the methodology set out in the Task 2 investigation factual report. In each location, and as before, the sampling apparatus were run twice on subsequent days; once with a sampling cartridge for asbestos analysis and once with a sampling cartridge for metal analysis.

The results of the sampling are provided in the Task 2 investigation factual report and show the following:

Asbestos fibres were not detected above the LoD in either sample; and

The suite of metals analysed (antimony, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, lead, nickel, selenium, silver, thallium, vanadium and zinc) were not detected above the relevant LoD in either sample.

Dust deposition monitoring was undertaken in accordance with the methodology set out in in the Task 2 investigation factual report. The dust deposition measurement locations described in Table 3.7 and are shown on Figure 10.

13 Air Quality Guidelines for Europe. Second Edition. WHO, 2000


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Table 3.7 Dust Deposition Monitoring Locations - George Town Landfill

Monitoring Run Location Run time (mins)

Date and comments

Unit 001886 Serial 4442

Run 2 Adjacent to MW14 25 Run on 8 April 2015 during groundwater sampling of MW14 as suitable location downwind of landfill site. Three separate runs (2, 4 and 5) as instrument turned off during rain showers.

Run 4 Adjacent to MW14 44 Run on 8 April during groundwater sampling of MW14 as suitable location downwind of landfill site. Three separate runs (2, 4 and 5) as instrument turned off during rain showers.

Run 5 Adjacent to MW14 228 Run on 8 April during groundwater sampling of MW14 as suitable location downwind of landfill site. Three separate runs (2, 4 and 5) as instrument turned off during rain showers.

Run 6 Adjacent to Gas Probe 1 49 Run 10 April during gas sampling of Gas Probe 1 within landfill.



Unit R10256 Serial 6709

Run 1 Adjacent to MW19 33 Run on 8 April during drilling of MW19. Location downwind of landfill.

Run 2 In waste drop off area at site entrance

16 Run on 8 April during drilling of MW19. Location downwind of landfill.

Run 3 Adjacent to MW14 145 Run on 9 April as suitable location downwind of landfill site.

Run 4 Adjacent to MW8 84 Run on 9 April during groundwater sampling of MW8. Location generally upwind of landfill.

Run 5 Adjacent to MW11 77 Run on 9 April during groundwater sampling of MW11. Two separate runs (5 and 6) as instrument turned off during rain showers. Location generally upwind of landfill.

Run 6 Adjacent to MW11 58 Run on 9 April during groundwater sampling of MW11. Two separate runs (5 and 6) as instrument turned off during rain showers. Location generally upwind of landfill.

Run 7 Adjacent to DM2 129 Run on 11 April. Location downwind of landfill.

Runs 1 and 3 on unit 001886 were aborted and re-run as runs 2 and 4 respectively.

Dust deposition measurement data are included in the Task 2 investigation factual report. In summary, the overall average concentration of dust measured on each run ranged between 0.01 mg/m3 and 0.036 mg/m3 with the highest concentration recorded adjacent to monitoring well MW14 on 8 April 2015. Note that this location is downwind of the main landfill area of the site.

The particle size range of maximum response for the dust deposition monitor is 0.1 to 10 μm (i.e. ‘PM10’). By way of comparison, the EC/UK Air Quality Standard14 for PM10 is 50 µg/m3 (0.05 mg/m3) based on a 24 hour mean, which was not breached in any of the locations monitored.

14 The Air Quality Standards Regulations 2010


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Other Vapour Sources

The waste oils storage area and hazardous waste storage areas are a potential source of vapours. No vapour monitoring is undertaken at the site.

Fires

A number of fires have occurred at the George Town landfill. These have caused particular problems and concerns when they have spread to stockpiled waste tyres.

The local press (Cayman Compass) reported a fourth fire at the landfill in 2014 on 18 August, see: http://www.compasscayman.com/caycompass/2014/08/18/Fire-ignites-again-at-landfill/ and a further fire reported on 1 March 2015 http://www.compasscayman.com/caycompass/2015/03/03/Firefighters-monitor-landfill/

Smoke and combustion products from landfill fires is a potential contaminant source. It is recommended that air monitoring for PAHs be undertaken on the downwind boundary of the landfill during any further fires.

3.8 Air Quality Modelling

Estimation of LFG Surface Emissions

A GasSim model of the Grand Cayman landfill site active tipping area was compiled, based upon the available data supplied on the level and composition of waste inputs. A copy of the output graphs for the model is included in Figure 13.

The peak gas generation rate was estimated to be 595 m3/h across the 6.25 ha of active main landfill surface (see Figure 1 for location, this excludes the old landfill area and Hurricane Ivan fill area). On that basis, the equivalent areal emission rate of landfill gas is calculated to be 0.00952 m3/m2/h. This equates to 3.3 mg LFG/m2/s. Figure 6.7 in the EA technical guidance document LFTGN 03 shows that this would be at the upper end rate for sites with a soil cap. Similarly, this figure also equates to 285 g LFG/m2/day, which, in Figure 6.6 of the above document, is appropriate for sites without active gas controls, which is the case for George Town landfill.

Estimation of Odour Emission Rates

Whilst it would be theoretically possible, using the predicted surface LFG emissions above, to calculate an odour emission rate due to landfill gas emissions, this would be a potential inaccurate under-estimate for two reasons: firstly, it would ignore the odour component arising from the landfilled wastes themselves and, secondly, the odour concentration of the landfill gas is not known. Accordingly, an emission rate was sourced from a recent research report15, where measured odour emission rates from active deposition areas on UK landfills are reported (Table 7 on page 28 of the report). Taking an average of the reported values yielded an odour emission rates from the landfill surface of 0.55 ouE/m2/s, where ‘ouE’ is a European Odour Unit. This emission rate was applied uniformly across the active landfill area.

Dispersion Model Set-up

The dispersion model used in this assessment is the ADMS 5 (Service Pack 1) code16. For near field (up to 100 km from emission sources) modelling studies, ADMS is one of two preferred “new generation” dispersion models in wide use internationally, the other being AERMOD.

The ADMS model was configured as indicated in Table 3.8.

15SNIFFER (2013) Odour Monitoring and Control on landfill Sites. http://www.sniffer.org.uk/files/2813/7476/3982/ER31_Final_Report.pdf 16 http://www.cerc.co.uk/environmental-software/ADMS-model.html


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Table 3.8 ADMS Model Configuration

Parameter Value Comments

Emission Source Polygonal ground-level area source with UTM vertices: 460801, 2135402 460747, 2135421 460476, 2135324 460463, 2135257 460559, 2135139 460689, 2135109 460765, 2135119 460832, 2135183

Emission Source

Receptors A regular Cartesian grid of receptors spaced at 72.5 metre intervals. Discrete receptors with UTM co-ordinates: 460320, 2134932 460284, 2134992 460262, 2135025 460216, 2134997 460167, 2134913 460004, 2135267 459996, 2135336 459982, 2135440 459956, 2135534 459962, 2135606

Parkside Close and the Lakeside Development

Emission rates Odour - 0.55 ouE/m2/s Uniform across active landfill area

Trace Pollutants – Unit emission rate Individual pollutant emission rates calculated from LFG analytical data and factored by dispersion co-efficient in model

Surface roughness 0.5 m Typical for parkland & open suburbia

Meteorological data

3330 hours of non-sequential hourly average wind speed, direction, temperature, relative humidity, cloud cover from Owen Roberts International Airport between April 2013 and May 2015.

Although not a full year of data, considered to cover a representative spread of typical meteorological conditions

Output data Odour - 98th percentile of hourly average concentrations To allow assessment against typical odour annoyance criteria

Trace pollutants – annual (period) average and maximum hourly average

To allow comparison with air quality standards & guidelines

Figure 14 shows a schematic of the model domain, identifying the emission source and discrete receptors and Figure 15 shows a wind rose, constructed from the supplied meteorological data.

Data Processing and Outputs

Odour

Concentrations of odour at discrete receptors and on the receptor grid were calculated as the 98th percentile of hourly averages over the period of meteorological data and are supplied as numerical values and an isopleth (contour) plot, respectively. These values are generated automatically by the ADMS dispersion model.

Trace Pollutants

In order to calculate the ambient concentrations of trace pollutants contained in the emission of LFG from the landfill surface, the ADMS model was set up with a unit emission rate, from which it was then possible to


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derive a dispersion factor from the source to each of the discrete receptors. This dispersion factor for each of the receptors was then multiplied by the calculated emission rate of each individual trace pollutant from the landfill surface, which itself had been calculated from the analysis of LFG samples.

Period (annual) average and maximum hourly average concentrations were derived and compared with relevant assessment criteria (see below).

Assessment Criteria

Odour

Odours are not generally additive in the same way as other annoyance parameters such as decibels for noise17. This reflects the way in which the brain responds to odour. The human brain has a tendency to screen out those odours which are always present or those that are in context to their surroundings. For example, an individual is more likely to be tolerant of an odour from a factory in an industrial area than in the countryside. The human brain will also develop a form of acceptance to a constant background of local odours.

Odour assessments in the UK, EU and some locations outside the EU use the odour unit as the standard reference figure. A European Odour Unit (ouE/m3) is a term used to describe the amount of odour that, when evaporated into a cubic metre of clean air, is sufficient to reach the detection threshold of a panel of screened and selected human subjects. The process of measuring odour is called olfactometry.

Limited research is available into what constitutes an appropriate and workable odour standard for sewage treatment. The Concise Guide18 considers that an odour at five times its detection threshold (effectively 5 ouE/m3) can be considered as having the potential to cause annoyance. Although this is not directly aimed at the waste industry, it provides for a common guideline as to the historical approaches that have been adopted.

Research in the Netherlands19 has highlighted the complexity of the assessment of odours. It states that situations exist where 5 ouE/m3 has been achieved and no complaints have been received, yet cases also exist where 1 ouE/m3 has been achieved and complaints were still received. Here, the Netherlands Emission Guidelines for Air considers that the exposure concentration where complaints escalate is at concentrations above 2.5 ouE/m3 as the 98th percentile of hourly averages.

The conclusion is that an appropriate criterion could lie anywhere between 1 ouE/m3 and 10 ouE/m3 as the 98th percentile of hourly averages at a critical receptor20.

In 2002, the EA published a draft copy of its Horizontal Guidance Document H4 and, in 2011, a final version. This includes a graduated scale of “indicative odour thresholds”, depending upon the perceived offensiveness of the odour, as follows:

1.5 ouE/m3 (98th percentile) for the most offensive odours;

3.0 ouE/m3 (98th percentile) for less offensive odours; and

6.0 ouE/m3 (98th percentile) for the least offensive odours.

These were derived from studies in Holland on the offensiveness of odours from intensive pig farming in rural areas. It is generally considered that sewage treatment works odours fall into the middle category (3.0 ouE/m3), unless there are septic wastewater or sludges on the site, in which case the most stringent criterion would apply. Water Authority Cayman have indicated that some septic wastewater and sludges are received at their site.

17 Environment Agency (2002) DRAFT Horizontal Guidance for Odour Part 1 - Regulation and Permitting. 18 Valentin, F.H.H and North, A.A. (1980). Odour Control - A Concise Guide. Department of the Environment.

19 Information Centre for the Environment (2001). Netherlands Emission Guidelines for Air. InfoMil. 20 Hall, D. L., McIntyre, A. E., (2004). The Derivation of Odour Standards and their Role and the Foundation of Odour Management Plans for Planning Regulation. In Proceedings of the Second National Conference Volume Two September 2004. Ed N. J. Horan.


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For landfill odours, typically a criterion of 3 ouE/m3 as a 98th percentile concentration, has been adopted as an appropriate annoyance metric.

Trace Pollutants

The list of trace pollutants for which some form of assessment criteria (air quality standards/guidelines) are available are contained in Table 3.9.

Table 3.9 Trace Pollutants and Assessment Criteria

Pollutant Criteria, µg/m3 Source

Long Term Short Term

Hydrogen sulphide 140 1501, 72 UK EA H1; WHO

1,2,4-Trimethylbenzene 37,500 UK EA H1

1,2-Dichloroethane 700 UK EA H1

1,3,5-Trimethylbenzene 1,250 37,500 UK EA H1

2-Butanone (MEK) 6,000 89,900 UK EA H1

4-Methyl-2-pentanone (MIBK) 362,000 UK EA H1

Acetone 18 100 UK EA H1

Benzene 5 UK Air quality standard

Benzyl chloride 5.2 158 UK EA H1

Carbon disulphide 64 100 UK EA H1

Chlorobenzene 158 UK EA H1

Chloromethane 1,050 21,000 UK EA H1

Ethylbenzene 4,410 55,200 UK EA H1

Methylene Chloride 700 3,000 UK EA H1

Vinyl chloride 159 1,851 UK EA H1

1 for the protection of human health 2 for the prevention of odour nuisance

Results of the Assessment

Odour

The results of the dispersion modelling exercise for odour at the discrete receptor locations are contained in Table 3.10.


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Table 3.10 Odour Results at Discrete Receptors

Receptor name X(m) Y(m) 98th percentile odour concentration, ouE/m3

Maximum average hour concentration, ouE/m3

Lakeside 1 460320 2134932 1.4 23.7

Lakeside 2 460284 2134992 1.5 19.9

Lakeside 3 460262 2135025 2.0 17.8

Lakeside 4 460216 2134997 1.5 15.9

Lakeside 5 460167 2134913 1.0 13.0

Parkside Close 1 460004 2135267 6.7 17.0

Parkside Close 2 459996 2135336 8.0 16.6

Parkside Close 3 459982 2135440 6.1 15.2

Parkside Close 4 459956 2135534 3.6 13.5

Parkside Close 5 459962 2135606 2.6 12.9

As can be seen, there are four receptor locations at which the odour annoyance criterion of 3 ouE/m3, 98th percentile, is forecast to be exceeded and it is understood that this is consistent with anecdotal reports of detected odours in these locations. In addition, the maximum hourly average odour concentrations forecast to occur would certainly be noticeable, varying between 12.9 and 23.7 ouE/m3.

Figure 16 shows a contour plot of odour dispersion from the landfill site generated by the ADMS dispersion model, incorporating the 98th percentile odour concentrations.

This shows that many of the receptors in Parkside Close are within the 3 ouE/m3 contour and are likely to experience odour at levels that could generate annoyance, whilst most of the Lakeside development sits just outside the same contour level.

Trace Pollutants

The results of the dispersion modelling assessment for the maximum hourly average concentrations of trace pollutants listed in Table 3.9 above are contained in Table 3.11.


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Table 3.11 Trace Pollutant Results at Discrete Receptors – Short Term Averages

Pollutant Lakeside, µg/m3 Parkside, µg/m3 Assessment

Criterion, µg/m3

Maximum Minimum Maximum Minimum

Hydrogen sulphide 64.3 35.3 46.12 35.09 1501, 72

1,2,4-Trimethylbenzene 0.13 0.05 0.09 0.07 37500

1,2-Dichloroethane 0.02 0.01 0.01 0.01 700


2-Butanone (MEK) 0.77 0.29 0.55 0.42 89900

4-Methyl-2-pentanone (MIBK)

0.17 0.06 0.12 0.09 362000

Benzyl chloride 0.14 0.05 0.10 0.07 158

Carbon disulphide 0.15 0.06 0.11 0.08 100

Chlorobenzene 0.02 0.01 0.01 0.01 158

Chloromethane 0.19 0.07 0.13 0.10 21000

Ethylbenzene 0.39 0.15 0.28 0.21 55200

Methylene Chloride 0.39 0.15 0.28 0.21 3000

Vinyl chloride 0.37 0.14 0.27 0.20 1851

1 for the protection of human health 2 for the prevention of odour nuisance

It can be seen that maximum hourly average predicted concentrations of all trace pollutants are well within the specified health-related assessment criteria. However, for hydrogen sulphide, the maximum hourly average concentrations at all of the receptors exceed the WHO guideline value of 7 µg/m3 as a 30-minute average value, proposed to avoid creating an odour nuisance. The minimum hourly average concentration forecast at a receptor is 35 µg/m3, some five times the guideline value.

Table 3.12 contains the results of the assessment in respect of long term average trace pollutant concentrations predicted by the ADMS dispersion model. Usually, these relate to averages over a calendar year. In this case, as a result of the met data period considered, these are termed long term period averages.


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Table 3.12 Trace Pollutant Results at Discrete Receptors – Long Term Averages

Pollutant Lakeside, µg/m3 Parkside, µg/m3 Assessment

Criterion, µg/m3

Maximum Minimum Maximum Minimum

Hydrogen sulphide 1.02 0.54 1.48 0.69 140


2-Butanone (MEK) 0.0123 0.0066 0.0179 0.0083 6000

Acetone 0.0476 0.0254 0.0691 0.0320 18

Benzyl chloride 0.0022 0.0012 0.0032 0.0015 5.2

Carbon disulphide 0.0023 0.0013 0.0034 0.0016 64

Chloromethane 0.0030 0.0016 0.0043 0.0020 1050

Ethylbenzene 0.0062 0.0033 0.0090 0.0041 4410

Methylene Chloride 0.0062 0.0033 0.0090 0.0042 700

Vinyl chloride 0.0059 0.0032 0.0086 0.0040 159

Benzene 0.0048 0.0025 0.0069 0.0032 5

In the case of the long term average modelled concentrations, there are no exceedences of the assessment criteria, by some considerable margin, in most cases.

Conclusions

Estimation of the surface emissions of landfill gas from the Grand Cayman landfill site using a GasSim model has enabled a quantitative modelling assessment of the likely emissions of odour, hydrogen sulphide and airborne trace organic micro-pollutants to be undertaken. The latter quantification of emissions was undertaken using analyses conducted on samples of the landfill gas on the site.

The results of the modelling exercise revealed that detectable ambient concentrations of odour are likely to be experienced off-site at the nearest residential developments downwind of the landfill site. In addition, modelling of hydrogen sulphide emissions showed that short-term (hourly) average concentrations at the nearest residential receptors were likely to exceed the WHO odour nuisance guideline concentration by a significant margin. These model predictions accord well with recent anecdotal reports of odour annoyance.

For the remaining trace organic micro-pollutants, none of these was forecast to exceed relevant assessment criteria as a result of surface emissions from the landfill site.

3.9 Other Issues

The main landfill area is the highest point on Grand Cayman and is visible from a considerable distance. The landfill is also visible to cruise ships moored offshore.

The main landfill area is not capped or restored and therefore is a significant visual intrusion. The visual impact cannot be considered using the risk assessment approach outlined for contamination sources or hazards.


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3.10 Risk Assessment

Approach

The risk assessment approach is described in Chapter 2.

Conceptual Model

A conceptual model has been prepared for the landfill site which identifies potential contaminants and amenity related hazards, potential pathways and receptors. The conceptual model considers both onsite and offsite sources. The conceptual model is summarised in Figure 17.

Summary of Potential Contamination and Hazards

On-Site Sources

From the assessment of historical and current activities and the environmental monitoring data (which have been screened, where appropriate, against generic assessment criteria) the potential on-site sources are identified in Table 3.13. These include contaminants and amenity related hazards.

Table 3.13 Summary of On-site Potential Contamination and Hazards

Location Source Contaminant (C) or Hazard (H)

Type Source Quantitative Data Y= yes N= no

Comment

Soils around waste area

Unknown, could be from former waste burning

C Arsenic Y Exceeds Florida soil clean-up assessment criteria but generally below UK assessment criteria. Noted at three locations. Arsenic containment pit onsite

Waste Oils storage area

Hydrocarbons C Hydrocarbons Y Oil contamination noted by Amec Foster Wheeler within well MW16. 0.84mg/l DRO in surface water at SW12

Groundwater Leaching from wastes

C Ammonia Y The Florida clean-up standard of 28 mg/l has been exceeded in MW10 and new monitoring well MW21 which had the highest result yet recorded at the site in 2015


C Iron Y Detected above the clean-up level of 3 mg/l with results ranging up to 11 mg/l


H Orthophosphate Y Found at reduced concentrations in surface waters

Surface water canal

Leaching from waste and groundwater base flow

C Ammonia Y The April 2015 sampling identified concentrations of between 2.0 and 6.5 mg/l in the perimeter canals

Surface water canal


C/H Metals Y The sample from SW3 recorded exceedences of the relevant clean-up levels for copper and lead.


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Type Source Quantitative Data Y= yes N= no

Comment

Surface water canal


H Elevated nutrients Y Nitrogen and orthophosphate in canal with potential eutrophication impact to North Sound

Surface water canal

Runoff H Turbidity/dissolved solids

Y Some historical issues noted

Sediment at canal mouth to North Sound

Historical run-off C Sulphate Y Potentially associated with hydrogen sulphide generation

Incinerator Stack emission C/H Combustion products N No emission test data

Landfill area Landfill gas C Methane and carbon dioxide

Y Methane potentially explosive and carbon dioxide an asphyxiant

Landfill area Landfill gas C/H Hydrogen sulphide Y Hydrogen sulphide elevated in one of the gas probes

Landfill area Landfill gas C/H Trace gas components

Y Trace gases are a source of odour and a potential hazard within the landfill

Landfill area Municipal waste H Dusts Y Measured deposition rate less than guideline value but limited data

Landfill area Municipal waste H Smoke from fires N Combustion products

Landfill area Municipal waste H Vermin attracted to the wastes

N Spread of food scraps and bones

Landfill area Municipal waste H Flies and insects N Pest control carried out

Landfill area Tyre storage H Combustion products from accidental fires in tyre storage areas

N Combustion products from tyre burning have the potential to impact offsite residential users

Landfill area Municipal waste H Scavenging birds N Scavenging birds attracted to the landfill could increase the bird strike risk to aircraft

Off-Site Sources

From the assessment of historical and current activities a number of contaminative activities or, hazards have been identified and are associated with off-site activities. These are set out in Table 3.14.


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Table 3.14 Summary of Offsite Potential Contamination and Hazards


Type Quantitative Data Y= yes N= no

Comment

Wastewater sludge lagoons

Sludge decomposition C Hydrogen sulphide

N Hydrogen sulphide generation from former/active sludge lagoons indicated by monitoring

Wastewater sludge lagoons

Sludge decomposition H Odour N Odour generation from former/active sludge lagoons

Various Industrial Premises

Soil and aggregate storage

H Dusts N Various sources of dust generation on industrial premises to the south east and south of the site

Receptors and Pathways

Receptor groups have been identified in Table 3.15 together with some notes on their status.

Table 3.15 Receptors

Receptor Groups Comments

Site workers and visitors Site has open access and members of the public can access out of hours

Adjacent residents Lakeside development and Parkside Close located approximately 330ft (100m) from site boundary and downwind of the site. The Camana Bay development is located approximately 0.5 miles beyond the northern boundary.

Adjacent commercial/industrial premises

Industrial and commercial premises to the south and east of the site. The airport is located approximately 1mile beyond the southern boundary of the site.

Groundwater Groundwater is brackish and in continuity with perimeter canals. There are public water supply (PWS) abstractions approximately 1 mile from the site; this water is treated.

Surface water in canals around the landfill

The canals are tidal and brackish water. There is no recreational use.

Marine water in North Sound There is no specific water quality designation for the area of western part of North Sound adjacent to the landfill. However other parts of the Sound are used diving and wildlife interaction and these activities indicate the quality of water required to sustain them.

Ecological receptors Some birds were noted in the ‘leachate’ ponds onsite. The canals are fringed by mangroves which are a roost for birds. Iguanas swim in the canals and were also seen on the landfill. Some large fish were observed in the eastern part of the North Canal during the April 2015 water sampling. North Sound contains a diverse marine ecology.

Potential pathways are considered in Table 3.16.


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Table 3.16 Potential Receptors and Pathways

Receptor Pathway

Site workers and visitors Dermal contact, direct contact, ingestion, inhalation

Adjacent residents Ingestion of dusts, inhalation

Adjacent commercial/industrial premises Ingestion of dusts, inhalation

Groundwater (including PWS extraction) Leaching and migration

Surface Water (canals and North Sound) Run-off (to canal only), migration and groundwater base flow

Ecological receptors offsite Ingestion and bioaccumulation from contaminated waters/sediments. Eutrophication from elevated nutrients affecting marine ecology in North Sound.

Risk Assessment Methodology

The development of the conceptual models have identified a number of potential contaminant and hazard linkages (contaminant/hazard-pathway-receptor linkages) between receptors and the landfill site. These are tabulated in Appendix E.

Each contaminant linkage has been qualitatively assessed using the following criteria:

i) Potential consequence of contaminant/hazard linkage;

ii) Likelihood of contaminant/hazard linkage; and

iii) Risk classification.

The risk assessment criteria assessment methodology is provided within Chapter 2 of this report.

The updated environmental risk assessment for the site is included in Appendix E. This comprises an analysis of potential contaminant/hazard linkages (contaminant/hazard-pathway-receptor) between potential receptors and the landfill site.

3.11 Risk Assessment Outcomes

The outcomes from the risk tables in Appendix E are summarised below. Some further commentary on the rationale for the classification of each risk is given in the tables. The first summary for each receptor considers contaminants and the second amenity hazards. Amenity risk is based on the identification of a potential hazard or nuisance for which there are no generic assessment criteria.

Site Workers and Visitors

Potential risks to site workers and visitors from arsenic in soils are assessed as moderate. The potential risks from hydrogen sulphide, other landfill gas trace components (such as volatile organic compounds) and methane (as a potentially explosive gas) are also all assessed as moderate. The risks to site workers/visitors from hydrocarbons from the waste storage area is assessed as moderate/low, assuming appropriate PPE is worn.

Adjacent Residents

The potential risks from landfill gas trace components and from methane (as a potentially explosive gas) are both assessed as moderate/low. Potential risks to adjacent residents from arsenic in soils are assessed as low.

Potential dust nuisance to adjacent residents is assessed as medium and odour nuisance as high. Potential risks associated with scavenging animals and birds, pests (e.g. flies) mosquitoes and contaminated waters


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used for recreational purposes are assessed as medium. There is a potential high risk associated with nuisance and potential health impacts from landfill fires.

Adjacent Commercial/Industrial Users

The potential risks from landfill gas trace components and from methane (as a potentially explosive gas) from landfill gas are assessed as moderate/low, although the potential risks from landfill gas trace components from contaminated sediments are assessed as moderate. Potential risks to adjacent commercial/industrial users from arsenic in soils are assessed as low.

The potential for the landfill to contribute

Groundwater

The risks to groundwater from hydrocarbons (spills and overtopping of bunds) are assessed as moderate. Potential risks to groundwater from arsenic are assessed as negligible and low with regard to ammonia.

Surface Water Canals

Potential risks to surface water canals from both hydrocarbons (spills and overtopping of bunds) are assessed as high. Risks from ammonia and orthophosphate (from groundwater base flow) are assessed as moderate, and from iron are assessed as moderate/low.

Sediments at the mouth of the North Canal are a possible source of hydrogen sulphide with a moderate risk to humans.

North Sound

The potential risk to water quality in North Sound (adjacent to the canal discharge) from ammonia in canal water is assessed as high. The potential risks to water quality from ammonia from contaminated groundwater is assessed as moderate/low and from metals in canal water is assessed as moderate.

The potential risk to North Sound ecology from ammonia in the canal in the canal is assessed as high as elevated levels were recorded at the mouth of the canal.

Elevated nutrients, iron and solids in the canal pose a potential high risk to aquatic vegetation adjacent to the mouth of the canal from sediment and iron blanketing and eutrophication.

A more detailed assessment of potential impacts on North Sound is outside the scope of this study and is included as a recommendation for further study.


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4. Environmental Condition Cayman Brac Landfill


Cayman Brac landfill is located on the southern side of the island off South Side West Road as shown on Figure 18. The entrance is located to the north of the road and approximately 280 ft (85m) from the beach.

The landfill site is owned by CIG and operated by the DEH. The total site area (excluding that south of the road) is approximately 20 acres (8 hectares) of which very approximately 9 acres (3.7 hectares) appears to have received waste materials. The northern part of the site has been used for municipal waste disposal by landraising against a natural cliff or bluff of limestone which runs along the northern margin of the site. The lower south western part of the site is used for storage of scrap metal (to the west of the site road) and disposal of green (i.e. yard) waste to the east. The south east quadrant of the site has not been filled and includes a pond, known as the Red Shrimp Lagoon (shrimp lagoon).

The landfill is predominantly a landraise formed by tipping over an area of former scrub. The site has no formal engineered containment (i.e. a basal lining system). Part of the municipal waste area is capped with a thin layer of soil materials but there has been no re-vegetation.

Topography

The site is located at the base of a bluff of limestone which is sub-vertical and some 15-20 ft (5-7m) high where exposed above the waste. It is estimated that up to 24 ft (8m) thickness of waste has been placed against the bluff. Ground below the base of the bluff slopes gently south towards the coastline but now comprises a wedge of infill. Ground level on the southern side of the site is around 5 ft (1.5m) above MSL and the shrimp lagoon is brackish.

There is no known topographical survey available for the site and levels have been inferred from LIDAR data included within a GIS (Geographical Information System) package for the site and shown on the aerial photographs included with the Task 1 environmental review.



To the north is a steep rock face covered with scrub and cactus beyond which is a vegetated limestone plateau;

To the east and west is undeveloped scrub land with occasional small pools; and

To the south of South Side West Road is a strip of land some 230 to 300 ft (70 to 100m) wide beyond which is a beach. There are two residential properties to the south of the site entrance which overlook the beach. Beyond the south west corner of the site is a public parking area with beach huts and access to the beach.

4.2 Site Infrastructure

For the purpose of description the site is split into a number of zones identified in Figure 18. The description of each area including photographs is provided in the Task 1 environmental review.

During the April 2015 sampling, the following changes were observed relative to the report based on the November 2014 visit:

The tyre pile had reduced considerably in size with tyres being progressively transferred into containers and shipped to Grand Cayman;


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Waste oil containers had been moved to an area north of the small site building with the intent to pump these out into a steel shipping tank for transfer off-island. However, transfer into the shipping container had not taken place; and

The clinical waste incinerator is still not operating and clinical waste is disposed into a pit (referred to as the difficult waste pit in the Task 1 environmental review) and left uncovered; and

The scrap metal bailer is out of operation pending repair. Several years’ accumulation of scrap metal and end of life vehicles at the site.

4.3 Data Sources

There are no known specific environmental reports or studies relating to the landfill. An environmental impact assessment (EIA) was prepared for an alternative landfill site on the island in 2008 by APEC/Tobin21 but this alternative site, in the centre of the island, did not progress. The EIA contains a brief description of the existing landfill area and some background environmental information for Cayman Brac.

There are no known environmental monitoring data for the landfill other than two surface water samples (locations unknown) taken by DEH in 2001.

4.4 Site History

The site has been in operation since at least 1978 and a brief summary is given in the Task 1 environmental review.

4.5 Waste Inputs

There is no weighbridge at the site. Data provided by DEH indicates the site received approximately 2,240t of waste in 2013. Some 3.9t of waste was processed in the on-site clinical waste incinerator. There is no specific breakdown of waste types but these are considered to be similar to those received at George Town landfill.

4.6 Geology

The central part of Cayman Brac is formed by a plateau known as the Bluff. This is a dolostone and limestone outcrop rising steadily along the length of the island to a maximum 140 ft (42 m) above MSL at the eastern end of the island. The Bluff dolostone and dolomitic limestone grouping includes the Cayman Member and Pedro Castle Member. These are underlain by the Brac Formation.

The Bluff formation forms the outcrop to the north of the landfill. It is characterised by solution weathering with enlarged fissures, and sinkholes. There are a number of caves within the formation.

The south eastern part of the site contains the Red Shrimp Lagoon with an associated small area of mangrove and there are likely to be thin deposits of organic sediments.

Four groundwater monitoring wells (CB1-CB4) were completed at the site in April 2015 using rotary open hole methods (i.e. no cores were recovered). As assessment of the strata was made by Amec Foster Wheeler based on the drilling rate and flush returns. The borehole locations are shown on Figure 19.

These wells proved the following:

21 Environmental Impact Assessment for the Proposed Cayman Brac Waste Management Facility. APEC/Tobin, July 2008.


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Made Ground (landfilled wastes of compacted soil with varying amounts of wood, plastic and metal) to depths of between 3 and 13.8 ft (0.9-4.2 m bgl) (CB1-CB3 only);

Brown fine to coarse sand to 9.8 ft (3 m bgl) (CB4 only); overlying

A limestone bedrock, anticipated to form part of the Bluff formation, which was typically recovered as white fine grained limestone fragments with some shell and coral fragments. The full depth of the limestone was not determined, with all boreholes drilled to approximately 30 ft (9.1m) bgl.

4.7 Hydrogeology

Regional Setting

The Bluff formation is very permeable and groundwater levels are estimated at only 1-3 ft (0.3-0. 9m) above sea level (from APEC/Tobin report).

Potable water on the island is provided by Water Authority Cayman from their seawater desalination plant at West End. The sea water is treated by reverse osmosis. There are no known groundwater abstractions in proximity to the site.

Groundwater Levels

Groundwater levels were measured in all of the new groundwater monitoring wells in April 2015 and the results are presented in the Task 2 investigation factual report. Groundwater levels varied between 0.65 ft (0.2m) bgl in CB1 to 13.81 ft (4.21 m) in CB3. In borehole CB4, which is the closest to the shoreline (i.e. sea level), the measured groundwater level was 7.81 ft (2.38 m). This is much deeper than the estimate from the APEC/Tobin report, although the measured depth to groundwater in CB1, the next closest borehole to sea level, is much closer to this estimate. Note that boreholes CB2 and CB3 are located much higher above sea level, as reflected in the greater measured depth to groundwater in these boreholes (7.38 and 13.81 ft, or 2.25 and 4.21 m bgl, respectively).

As part of the Task 2 investigation data loggers were installed in monitoring wells CB1 and CB3 to record fluctuations in groundwater levels. In general, the data show groundwater variation of 0.92-1.25 ft (0.28- 0.38m) over a 24 hr period and are therefore indicative of a tidal influence.

Groundwater Quality

Due to the fact that the limestones are hydraulically linked to the surrounding ocean there is considerable mixing of fresh and salt water due to tidal oscillations. This mixing causes a transition zone of brackish water to develop between the fresh and salt waters with enhanced mixing in the cavernous sections of the aquifer. Such brackish water is present beneath the landfill site.


Amec Foster Wheeler undertook sampling from new groundwater wells CB1-CB4 installed as part of the Task 2 investigation work on 15 April 2015.

Assessment Criteria

The 2015 sample data has been screened against Florida clean-up standard for poor yield/low quality groundwater. These assessment criteria have been selected due to the brackish nature of the underlying aquifer. The results and assessment criteria are summarised in Appendix F. The nature of the groundwater is summarised below.


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General Chemistry

The field measurements of pH were in the range 7.1 to 7.6 which is neutral to slightly alkaline. Electrical conductivity (i.e. conductance) ranged from 31.5 mS/cm in CB2 to 71.7 mS/cm in CB1. Groundwater ammonia varied from 0.4 to 18 mg/l with results from individual wells detailed in Table 4.1.

Table 4.1 Ammonia in Groundwater 2015

Monitoring Well

CB1 CB2 CB3 CB4

Ammonia (mg/l) 1.2 18 0.44 0.4

Grey highlighting denotes exceedance of Florida clean-up standard

The Florida clean-up standard of 28 mg/l was not exceeded. Orthophosphate concentrations range from below LoD up to 0.1 mg/l (CB2). Nitrate (NO3-) plus nitrite (NO2-) concentrations were below LoD in CB1 and CB2 and were 4.4 and 0.14 mg/l in CB3 and CB4 respectively. These concentrations are well below the Florida clean-up standard.

COD in groundwater in April 2015 monitoring was between 62 and 120 mg/l. BOD concentrations ranged between below LoD (CB3 and CB4) to 15 mg/l (CB2). There are no Florida clean-up standards for COD or BOD.

Total dissolved solids (TDS) ranged between 5,300 mg/l (CB2) and 20,000 mg/l (CB4). All results exceed the Florida clean-up standard of 5,000 mg/l. The TDS results are indicative of brackish water.

Cyanide analysis was undertaken on all four samples. All results were below the relevant LoD.

Metals

Metals analysis was undertaken on samples from CB1 and CB2. The majority of metals present at below LoD or at very low concentrations well below the relevant assessment criteria.


All VOC results (2 samples, CB1 and CB2) were less than the LoD with the exception of 1,4-Dichlorobenzene in the sample from CB2 (1.3 µg/l). This concentration is well below the Florida clean-up standard of 750 µg/l.

PCBs

All PCB analysis results (2 samples, CB1 and CB2) were less than the LoD.

Pesticides/Herbicides

Analysis on 2 samples (CB1 and CB2) were all less than the relevant LoD.

Hydrocarbons

DRO analysis was undertaken on all 4 samples (CB1 to CB4) of groundwater. Results were in the range 0.12-3.1 mg/l, with the highest result from CB2. GRO analysis was also undertaken on these samples, which recorded concentrations below the relevant LoD with the exception of CB4 (0.059 mg/l). There is no Florida state assessment standard for DRO or GRO.

For the purpose of data contextualisation, WHO guidance states that the application of the lowest WHO guideline value for (aliphatic) hydrocarbons (0.3 mg/l for carbon bands C12-C16, i.e. ‘diesel range’) to a total


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hydrocarbon measurement in water will provide a conservative level of protection. This guideline value has been exceeded in the DRO samples from CB1, CB2 and CB3.

4.8 Hydrology and Surface Water Quality

The high permeability of the fractured dolomitic rocks results in the absence of surface streams and a low water table gradient. A brackish pond, known as the Red Shrimp Lagoon or shrimp pond, is located in the south eastern part of the landfill area. This is part of an area known as The Marshes.

2001 DEH Sampling

DEH took two surface water samples from areas adjacent to the landfill in 2001 recorded as ‘shrimp pond’ which is assumed to be the shrimp lagoon and ‘surface water’. The data for the shrimp pond analysis is summarised in Table 4.2.

Table 4.2 Shrimp Pond Summary of Water Analysis 2001

Determinand Result

pH 8.4

Biochemical oxygen demand (BOD) 2.9 mg/l

Chemical oxygen demand (COD) 760 mg/l

Total dissolved solids (TDS) 1,400 mg/l

Total organic carbon 8.2 mg/l

Ammonia as N 0.095 mg/l

Nitrate plus nitrite 0.11 mg/l

Iron and mercury were recorded below LoD. Selected volatile organic compounds were also recorded below laboratory limits of detection.


In April 2015, Amec Foster Wheeler took two surface water samples from the shrimp lagoon (BSW1, north side and BSW3, south side) and one from a pond to the west of the landfill (BSW2), which are identified on Figure 20.

Assessment Criteria

The data has been screened against the Florida marine surface water clean-up targets as per the surface water samples from the George Town landfill. The data and screening criteria are summarised in Appendix G.

The following summary can be drawn from inspection of the surface water quality results.

General Chemistry

The pH range of the 2015 samples was 8.5-9, which is slightly higher than the 2001 result from the shrimp pond and is indicative of alkaline conditions. Electrical conductivity of the 2015 samples ranged between 54.1 to 56.5 mS/cm.

The 2015 sampling identified ammonia concentrations of below LoD (BSW2), 0.15 mg/l (BSW3) and 0.32mg/l (BSW1). These results are around, or above, the 2001 result of 0.095 mg/l. The observed ammonia concentrations in the surface water samples reflect high water quality based on UK guideline values.


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The 2015 orthophosphate concentrations range from below LoD (BSW1 and BSW3) to 0.017 mg/l (BSW2). On the basis of the recent round of data, the observed orthophosphate concentrations reflect good water quality based on UK guideline values. Nitrate plus nitrite concentrations were below the LoD in all 3 samples.

The previously recorded (2001) BOD concentration in the shrimp lagoon was 2.9 mg/l. BOD recorded in surface water samples from April 2015 ranged between 5.2 mg/l (BSW2) and 21 mg/l (BSW3, shrimp lagoon). A COD concentration of 760 mg/l was recorded in 2001 but did not exceed 540 mg/l in the April 2015 samples. Total suspended solids from the 2015 samples were recorded up to 800 mg/l. There are no marine water assessment criteria for any of these determinands.

Turbidity is recorded for which there is a Florida marine water clean-up standard of 29 NTU. This standard was not exceeded in any of the samples taken in 2015, which recorded results up to 8.9 NTU (BSW3).

Cyanide analysis was undertaken on samples from BSW1 and BSW2, both of which recorded concentrations below the laboratory LoD.

Metals

Metals analysis was undertaken on surface water samples BSW1 and BSW2. The majority of metal analyses returned results below laboratory LoDs. The only exceedences of the clean-up levels were as follows:

Copper was detected above the clean-up level of 0.0037 mg/l, at 0.0065 and 0.005 mg/l in BSW1 and BSW2, respectively; and

Lead was detected above the clean-up level of 0.0085 mg/l, at 0.048 and 0.038 mg/l in BSW1 and BSW2, respectively.

Mercury has not been detected above the laboratory LoD of 0.07mg/l in either of the samples.


All VOC results (BSW1 sample only) are less than the LoD.

PCBs

PCB analysis has been undertaken on surface water samples BSW1 and BSW2. All results are less than the laboratory LoD.

Pesticides

Analysis for a number of pesticide compounds has been undertaken on surface water samples BSW1 and BSW2. All results are less than the laboratory LoD.

Hydrocarbons

DRO analysis was undertaken on samples from BSW1 and BSW2 in April 2015. Results range from 0.62 mg/l (BSW1) to 2.4 mg/l (BSW2). GRO analysis was also undertaken on both samples, with both results below the relevant laboratory LoD.

For the purpose of data contextualisation, WHO guidance states that the application of the lowest WHO guideline value for (aliphatic) hydrocarbons (0.3 mg/l for carbon bands C12-C16, i.e. ‘diesel range’) to a total hydrocarbon measurement in water will provide a conservative level of protection. This guideline value has been exceeded in the samples from BSW1 and BSW2.

4.9 Ecological Receptors

The Red Shrimp Lagoon can be identified as an ecological receptor. There is a boardwalk leading to the southern side of the lagoon from the road to the south.


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National Trust Cayman has acquired some wetland approximately 850 ft (260 m) west of the landfill: (http://www.compasscayman.com/caycompass/2014/09/17/National-Trust-buys-Brac-wetlands/)

Offshore from the public beach to the south east of the site there is a marine designated area of reef and associated dive sites.

4.10 Soil Sampling

In April 2015, Amec Foster Wheeler took five soil samples from the surface of the Hurricane Paloma fill area and a further sample from the former tyre storage area for asbestos analysis. No asbestos was detected in any of the samples.

The sample from below the former tyre storage area was also analysed for PAHs as there was evidence of a previous fire. No PAH compounds were recorded above the laboratory LoD.

4.11 Landfill Gas

The site receives inputs of municipal wastes including organic materials such as food and kitchen wastes, garden wastes, paper, cardboard and timber and therefore likely to produce landfill gas. This is typically a mixture of methane and carbon dioxide together with trace components such as hydrogen, hydrogen sulphide and volatile organic compounds including halogenated organics, aromatic hydrocarbons, alkanes and ketones (Ref. EA LFTGN 03). Trace compounds in landfill gas are responsible for its odour.

Site Inspection 2014

There has been no landfill gas monitoring carried out at the Cayman Brac landfill site. Amec Foster Wheeler undertook some initial measurements during the site inspection by monitoring methane and carbon concentrations at the landfill surface on 18 November 2014.

The data is reported in the Task 1 environmental review, but in summary, methane concentrations of up to 0.2%v/v were recorded in surface cracks and fissures in the waste which confirms the site is actively generating landfill gas.

Gas Probes 2015

Gas monitoring and sampling was undertaken on 14 April 2015 from gas probes (GP21 to GP24) which were installed within the waste mass in April 2015. The gas probe locations are shown on Figure 19. Note that gas probes GP21, GP23 and GP24 only were sampled, as three gas samples are judged to provide sufficient coverage over this relatively small landfill.

Landfill gas monitoring data collected prior to the gas sampling using the portable infra-red gas analyser is presented in the Task 2 investigation factual report. The data shows methane and carbon dioxide concentrations indicative of a relatively poor quality landfill gas (~5.4-31.3% methane and ~16-25.5% carbon dioxide) with no or little (2.1% or less) oxygen in all probes. GP22 showed much lower concentrations of methane (5.4% v/v) and carbon dioxide (16% v/v) compared to the other probes. The highest concentrations of both gases were in GP24.

The gas analysis suite consisted of bulk gas constituents as well as hydrogen sulphide, carbon monoxide and NMVOCs.

Gas analysis results are included in the Task 2 investigation factual report and are summarised as follows:

Carbon dioxide: 24 v/v (GP1) to 28% v/v (GP23);

Methane: 14% v/v (GP21) to 33% v/v (GP24);

Oxygen: 1.3% v/v (GP23) to 2.1% v/v (GP24);

Nitrogen: 40% v/v (GP24) to 62% v/v (GP21);


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Carbon monoxide, ethane, ethylene, propane and propene: all results below relevant LoD;

Helium: 0.056% v/v (GP24 only, other results below LoD);

Hydrogen: 0.082% v/v (GP21) and 0.0081% v/v (GP24), with GP23 below LoD;

Hydrogen sulphide: 5.1 ppm (GP21), 7.1 ppm (GP23) and 1.7 ppm (GP24);

NMVOCs: below LoD except:

1,1 Dichloroethene (1.5 ppb, GP24);

1,2,4-Trimethylbenzene (34 ppb, GP24);

1,3,5-Trimethylbenzene (25 ppb, GP24);

1,4-Dichlorobenzene (2.9 ppb, GP24);

2-Butanone (MEK) (47-6,900 ppb, all samples);

2-Hexanone (100 ppb, GP21);

4-Ethyltoluene (10 ppb, GP24);

4-Methyl-2-pentanone (MIBK) 290 ppb, GP21);

Acetone (320-19,000 ppb, all samples);

Benzene (120-290 ppb, all samples);

Carbon disulphide (4.9-340 ppb, all samples except GP23);

Ethylbenzene (84-850 ppb, all samples);

m,p-Xylene (92-1,000 ppb, all samples);

Methylene Chloride (110-200 ppb, all samples except GP24);

o-Xylene (37-290 ppb, all samples);

Styrene (19-210 ppb, all samples);

Tetrachloroethene (5 ppb, GP24);

Toluene (520-12,000 ppb, all samples);

Trans-1,2-dichloroethene (16 ppb, GP24);

Trichloroethene (64 ppb, GP24); and

Vinyl chloride (18 ppb, GP24).

Concentrations of bulk LFG are largely consistent with the pre-sampling field data, although the field readings for oxygen differ from the laboratory results by around ±2% v/v. After the pre-sampling field data was taken, each sampled probe was pumped for approximately 5 minutes until readings stabilised to allow sampling. Therefore, the results of the sample analysis are likely to be much more representative than the pre-sampling field data.

The low/below LoD hydrogen concentrations recorded are fairly typical of a landfill in the long methanogenic stage of landfill gas generation.

The hydrogen sulphide concentrations recorded are typical of those usually measured in landfills. The laboratory results are higher than the hydrogen sulphide concentrations measured in the groundwater monitoring boreholes (up to 1.645 ppm, CB4, 17 April 2015) although most of the hydrogen sulphide results from the groundwater boreholes were zero.


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With regard to the NMVOCs, those detected above the relevant LoD are generally typical trace components within landfill gas. Some of the trace compounds detected, such as carbon disulphide, toluene and xylene, as well as hydrogen sulphide, are odorous components of landfill gas.


Hydrogen Sulphide Monitoring 2015

Fugitive hydrogen sulphide measurements in air were undertaken around the landfill site on 14 April 2015, following the methodology set out in the Task 2 investigation factual report.

A total of 8 locations were monitored, including areas adjacent to the four new gas probes GP21-GP24, locations around new groundwater monitoring wells CB2 and CB3 and a location near the site entrance. Hydrogen sulphide was not detected in any of these locations.

Dust Deposition Monitoring 2015

Dust deposition monitoring was undertaken in accordance with the methodology set out in in the Task 2 investigation factual report. The dust deposition measurement locations described in Table 4.3 and are shown on Figure 20.

Table 4.3 Dust Deposition Monitoring Locations - Cayman Brac Landfill

Monitoring Run Location Run time (mins) Date and comments


Run 9 Placed on top of electric meter near incinerator near site entrance

153 Run on 13 April during drilling of CB1-CB4. Location downwind of landfill.

Run 10 Placed on top of electric meter near incinerator near site entrance

344 Run on 14 April during site operational hours. Location downwind of landfill.

Run 11 Adjacent to CB2 461 Run on 15 April during site operational hours. Location downwind of landfill.

Dust deposition measurement data are included in the Task 2 investigation factual report. In summary, the overall average concentration of dust measured on each run ranged between 0 and 0.003 mg/m3 with the highest concentration recorded at the incinerator near the site entrance on 14 April 2015. Note that this location is across wind of the main landfill area of the site.

By way of comparison, the EC/UK Air Quality Standard for PM10 is 50 µg/m3 (0.05 mg/m3) based on a 24 hour mean, which was not breached in any of the locations monitored.


The waste oils storage area is a potential source of vapours. No vapour monitoring is undertaken at the landfill site.

Fires

A number of fires have been reported at the landfill. These have caused particular problems when they have spread to tyre stockpile. Smoke and combustion products from landfill fires are a potential contaminant/ hazard source.


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4.13 Other Issues

The landfill is visible from the two properties located to the south of the site between the road and the beach. It is also visible from the road access area to the public beach, but not from the beach itself. The landfill is also visible from the board walk the shrimp pond.


Approach


Conceptual Model

A conceptual model have been prepared for the site which identifies potential contaminants and amenity related hazards, potential pathways and receptors. The conceptual model considers both onsite and offsite sources. The conceptual model is summarised in Figure 21.


On-Site Sources

From the assessment of historical and current activities and environmental monitoring data (which has been screened against generic assessment criteria) the potential onsite sources are identified in Table 4.4.


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Table 4.4 Summary of Onsite Potential Contamination and Hazards

Location Source

Co

nta

min

ant

(C

) H

azar

d (

H)

Type

Qu

an

tita

tive

D

ata

Y=

yes

N

= n

o

Comment


Hydrocarbons C Hydrocarbons Y Some surface spills noted. DRO detected in surface water samples from BSW1 and BSW2 and groundwater samples CB1-CB4 in April 2015. GRO detected in groundwater sample CB4.


C Ammonia Y Detected up to 18mg/l in CB2 but not above Florida clean-up standard

Surface water Leaching from wastes

C Metals Y Elevated concentrations of copper and lead in surface water samples.

Incinerator Stack emission C/H Combustion products N No emission test data and incinerator currently out of use.

Landfill area Landfill Gas C/H Landfill gas trace components/bioaerosols

Y Odours

Landfill area Landfill Gas C Methane and carbon dioxide

Y Methane is potentially explosive and carbon dioxide an asphyxiant

Landfill area Municipal waste H Smoke from fires N Combustion products

Landfill area Municipal waste H Flies and insects N Site has a pest control regime

Landfill area Municipal waste H Scavenging animals N Evidence of scavenging animals on site

Landfill area Clinical Waste H Biohazards N Disposal in uncovered pit within the landfill (clinical waste incinerator not in operation)

Off-Site Sources

No off-site contamination sources or hazards have been identified.




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Table 4.5 Receptors


Site workers and visitors Site has open access and members of the public can access out of hours

Adjacent residents Three properties located immediately south of the site.

Adjacent public recreation areas Public beach located 230 ft (70m) south of the site

Groundwater Groundwater is brackish. There are no known abstractions in the vicinity of the site.

Surface water in shrimp pond Brackish water with possible groundwater base flow.

Marine water Potential groundwater mixing along the coastline

Ecological receptors Some birds were noted in the shrimp lagoon onsite. This forms part of The Marshes wetland area. National Trust for the Cayman Islands own wetland 850 ft (260 m) west of the site. A marine park is located offshore.



Receptor Pathway


Adjacent residents Ingestion of dusts, inhalation

Adjacent public recreation area Ingestion of dusts, inhalation

Groundwater Leaching and migration

Surface Water (shrimp pond) Run-off, migration and groundwater base flow

Marine Water Groundwater base flow/mixing


The development of the conceptual models have identified a number of potential contaminant and hazard linkages (contaminant/hazard-pathway-receptor linkages) between receptors and the landfill site. These are tabulated in Appendix H. Each contaminant linkage has been qualitatively assessed using the following criteria:




The risk assessment criteria assessment methodology is provided in Chapter 2.

The updated environmental risk assessment for the site is included in Appendix H. This comprises an analysis of potential contaminant/hazard linkages (contaminant/hazard-pathway-receptor) between potential receptors and the landfill site.


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The outcomes from the risk tables in Appendix H are summarised below. The first paragraph summary for each receptor considers contaminants and the second amenity hazards.


The potential risks from landfill gas trace components are assessed as moderate to low and from methane (as a potentially explosive gas) as moderate. The risks to site workers/visitors from hydrocarbons from the waste oil storage spills is assessed as low, assuming appropriate PPE is worn.

The risk to site users and visitors from the clinical waste disposed in the uncovered pit within the landfill is assessed as medium.

Adjacent Residents

The potential risks from landfill gas trace components are assessed as low and from methane (as a potentially explosive gas) as moderate/low.

Potential dust and odour nuisance to adjacent residents is assessed as medium. There is a potential medium risk associated with nuisance from landfill fires. Potential risks associated with pests (i.e. insects) are assessed as medium and are low with respect to scavenging animals and birds.

Groundwater

Potential risks to groundwater from hydrocarbons are assessed as moderate and from ammonia are assessed as moderate to low.

Shrimp Lagoon

The potential risks to the shrimp lagoon from metals leached from the landfill are assessed as moderate.

Potentially elevated nutrients and iron from run-off and groundwater base flow have as assessed medium impact on water quality in the shrimp lagoon.

Ocean

There is an assessed medium risk to water quality from potentially elevated nutrients and iron in groundwater base flow.


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5. Environmental Condition Little Cayman Landfill


Little Cayman landfill is located in the central part of the island off Olivine Kirk Drive. The entrance is located to the west of the road and beyond an area occupied by the island power generation plant. It is approximately 0.5 miles (0.8km) from the north coast. Figure 22 identifies the site location.

Little Cayman landfill site is owned by the CIG and operated by the DEH. The total site area is approximately 50 acres (21 hectares) of which approximately 2.2 acres (1 hectare) has received waste materials. The site is flat lying and has very little infrastructure. Deposited municipal wastes are regularly set-alight and the landfill comprises a burning ground with piles of unburned refuse.

Topography

There is no known topographical survey data for the Little Cayman landfill site other than from LIDAR data included within a GIS package for the site and shown on the aerial photographs in the Task 1 environmental review. This indicates the landfill area to be at approximately 5 ft (1.5m) above MSL with higher ground to the north and south. Based on observations made during the site visit the site is relatively flat lying and partially surrounded by mangrove scrubland.



The landfill is surrounded by areas of seasonally flooded mangrove scrubland to the west and dry forest and woodland on slightly higher land to the north and south;

The island power generation plant is located approximately 1,500 ft (450 m) east of the current burning area; and

The nearest residential property is some 1,800 ft (550 m) to the south.

5.2 Site Infrastructure

For the purpose of description the site is split into a number of zones identified in Figure 22. The description of each area including photographs is provided in the Task 1 environmental review.

During the April 2015 sampling the following changes were observed relative to the report based on the November 2014 visit:

It appears that the site has been extended to the west by approximately 25-50m (82-164 ft) into the adjacent mangrove scrubland; and

There is evidence of an illegal waste oil disposal pit at the site, near the plant storage building.

5.3 Data Sources

There are no known specific environmental reports or studies relating to the landfill on Little Cayman and there are no known studies for an alternative waste facility on Little Cayman.

There are no known environmental monitoring data for the landfill other than one surface water sample taken by DEH in 2001. The sample location is unknown.


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5.4 Site History

The site appears to have been constructed at some point between 1971 and 1994. A brief site history is provided in the Task 1 environmental review.

5.5 Waste Inputs

There is no weighbridge at the site and no data on input tonnages, although these are small considering the resident population is approximately 170. There is no specific breakdown of waste types but these are considered to be similar to those received at George Town landfill.

5.6 Ecological Receptors

The National Trust for the Cayman Booby Pond nature reserve is located approximately 0.5 miles (0.8 km) south west of the site. This Nature Reserve is designated as a "Wetland of International Significance" under the terms of the Ramsar Convention.

Some 0.5 miles (0.8km) north of the site is the sea which is designated a marine park with a number of diving sites.

5.7 Geology

Little Cayman is a low lying dolostone and limestone outcrop. There is no specific stratigraphic information but the dolostone and dolomitic limestone grouping probably includes the Cayman Member and Pedro Castle Member. These are underlain by the Brac Formation.

The dolostone and limestone is locally characterised by solution weathering with enlarged fissures.

5.8 Hydrogeology

The dolostone and limestone is likely to be of variable permeability. There are some small ponds shown on the land survey map in proximity to the site. These may be freshwater or brackish pools.

There is no specific hydrogeological information for the site or its surrounding environs. There are no known groundwater abstractions in proximity to the site.

5.9 Hydrology

As noted above, some small surface water pools are identified on survey map in proximity to the site. Some small areas of surface water ponding within the site were noted during the site visits. It is noted the amount of standing water had reduced significantly since the site inspection in November 2014; this is consistent with the April 2015 sampling being undertaken at the end of the dry season on the islands. It is unknown whether the offsite ponds are hydraulic continuity with the site (e.g. via groundwater base flow).

2001 DEH Sampling

DEH took one surface water samples from the landfill (location unknown) in 2001 recorded as ‘Little Cayman Landfill SI’. The data for this sample is summarised in Table 5.1.


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Table 5.1 Little Cayman Summary of Water Analysis 2001

Determinand Result

pH 7.4

BOD <2 mg/l

COD 120 mg/l

Total dissolved solids (TDS) 6,000 mg/l

Total organic carbon 18 mg/l

Ammonia as N 0.48 mg/l

Nitrate plus nitrite <0.05 mg/l

Mercury was recorded below the laboratory LoD. Selected volatile organic compounds were also recorded below laboratory limits of detection.

The TDS result of 6,000 mg/l is indicative of brackish water.


In April 2015, Amec Foster Wheeler took two surface water samples, LSW2 (a small very shallow pond near the midpoint of the southern site boundary form which it was difficult to recover a sufficient volume of water for all analytical suites) and LSW3 (a water body at the end of a track approximately 1 mile/1.5 km west of landfill) which are identified on Figure 23. LSW3 was selected to give an indication of ‘background’ surface water quality on the island. Note that there is no LSW1 sample, which was scheduled to be taken from the Booby Pond which is the main potential receptor south west of the landfill but water within the pond could not be safely accessed for sampling.

Assessment Criteria

The data has been screened against the Florida marine surface water clean-up targets as per the surface water samples from the George Town site. The data and screening criteria are summarised in Appendix I.

The following summary can be drawn from inspection of the surface water quality results.

General Chemistry

The BOD recorded in the 2015 samples were 8.8 mg/l (LSW3) and 57 mg/l (LSW2). These results are at least an order of magnitude higher than the 2001 result. The COD results were 730 mg/l (LSW2) and 960mg/l (LSW3) which are nearly an order of magnitude higher than the 2001 result. There are no marine water assessment criteria for either of these determinands.

The 2015 sampling identified ammonia concentrations of below LoD (LSW3) and 0.31 mg/l (LSW2). These results are below the 2001 result of 0.48 mg/l. The observed ammonia concentrations in the 2015 surface water samples reflect high water quality based on UK guideline values.

The 2015 orthophosphate concentrations were 0.028 mg/l (LSW2) and 0.04 mg/l (LSW3). On the basis of the recent round of data, the observed orthophosphate concentrations reflect good water quality based on UK guideline values.

Total suspended solids from the 2015 samples were recorded up to 43,000 mg/l. There are no marine water assessment criteria for this determinand.

Cyanide analysis was undertaken on the sample from LSW2, which recorded a concentration below the laboratory LoD.


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Metals

Metals analysis was undertaken on surface water sample LSW3. The majority of metal analyses returned results below the relevant laboratory LoD. The only exceedences of the clean-up levels were as follows:

Copper was detected above the clean-up level of 0.0037 mg/l, at 0.014 mg/l; and

Lead was detected above the clean-up level of 0.0085 mg/l, at 0.056 mg/l.

Hydrocarbons

DRO analysis was undertaken on samples from LSW2 and LSW3 in April 2015. Results were 1.9 mg/l (LSW2) and 2.5 mg/l (LSW3). GRO analysis was also undertaken the LSW2 sample, recording a result of 0.059 mg/l.

For the purpose of data contextualisation, WHO guidance states that the application of the lowest WHO guideline value for (aliphatic) hydrocarbons (0.3 mg/l for carbon bands C12-C16, i.e. ‘diesel range’) to a total hydrocarbon measurement in water will provide a conservative level of protection. This guideline value has been exceeded in the samples from LSW2 and LSW3.

The data indicates some low level contamination both in the site SW2 sample and the offsite SW3 sample.

5.10 Soil Sampling

In April 2015, Amec Foster Wheeler took five soil samples from the surface across the site. The laboratory analysis included asbestos, cyanide, metals, water soluble sulphate and PAHs as well as soil leaching tests for metals and PAHs to establish the leachability of soils in relation to potential groundwater impact.

The results are summarised as follows:

No asbestos was detected in any of the samples;

PAHs were not detected in soils above the relevant LoD, with the exception of naphthalene, which was detected at a concentration of 44 µg/kg. This concentration is well below the Florida clean-up standard for commercial/industrial land of 300 mg/kg;

PAHs were not detected in the soil leaching test results above the relevant laboratory LoD;

Metals concentrations in the soil samples were below the relevant laboratory LoD for all samples for beryllium and thallium, and for all but one of the results for silver (0.74 mg/kg, LSS4). Where metals were detected, concentrations were below the relevant Florida soil clean-up target level for commercial/ industrial land with the exception of arsenic, which was detected at concentrations of 14-310 mg/kg against a clean-up target of 12 mg/kg. As before, the Florida clean-up standard for arsenic is exceptionally low when compared to UK assessment criteria for the same commercial/industrial use scenario (which is 640 mg/kg);

Metals concentrations in leaching test results were below the laboratory LoD for all samples for beryllium, cobalt, silver and thallium, with most results for cadmium and nickel also below the LoD. Where metals were detected in leachate, concentrations were below the relevant Florida surface water clean-up target level or marine surface water criteria with the exception of arsenic (LSS4 only, 0.059 mg/l); copper (all samples, up to 0.18 mg/l) and lead (all samples except LSS2 and LSS5, concentrations up to 0.016 mg/l);

Cyanide was detected in all samples except LSS5 at concentrations of up to 0.61 mg/kg (LSS3), although this concentration is well below the Florida clean-up standard for commercial/industrial land of 11,000 mg/kg; and

Water soluble sulphate was detected in all samples at concentrations up to 14,000 mg/kg (LSS3). There is no Florida clean-up standard for sulphates.


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In summary, there were exceedences of the relevant clean-up standards for arsenic in soils (although the clean-up standard is very low compared to that for the UK) and for arsenic, copper and lead in leaching test soil samples submitted for leaching tests.


Dust Deposition Monitoring 2015

The landfill is a potential source of fugitive emissions in terms of dust. Ash and clinker from burning is not covered.

Dust deposition monitoring was undertaken in accordance with the methodology set out in in the Task 2 investigation factual report. The dust deposition measurement location is described in Table 5.2 and is shown on Figure 23.

Table 5.2 Dust Deposition Monitoring Locations – Little Cayman Landfill

Monitoring Run Location Run time (mins) Date and comments


Run 12 Placed on top of metal drum near western boundary

246 Run on 16 April during sampling works during site operational hours. Location downwind of landfill.

Dust deposition measurement data are included in the Task 2 investigation factual report. In summary, the overall average concentration of dust measured on the run was 0 mg/m3. Note that this location is downwind of the main landfill area of the site.

By way of comparison, the EC/UK Air Quality Standard for PM10 is 50 µg/m3 (0.05 mg/m3) based on a 24 hour mean, which was not breached in the location monitored.

Smoke

The site receives municipal wastes including organic materials such as food and kitchen wastes, garden wastes, paper, cardboard and timber. The wastes are routinely burnt and produce smoke. The prevailing wind direction for the Cayman Islands is from the ENE.

As the wastes are burnt at the site is not considered to have any potential for landfill gas generation.


The waste oils storage area is a potential source of vapours although with the relatively small quantities stored this is not considered a significant source. An illegal oil disposal pit was also identified at the site during the April 2015 visit. No vapour monitoring is undertaken at the site.

5.12 Other Issues

The landfill is in an isolated location and is not visible from any residential properties.


Approach



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Conceptual Model

A conceptual model have been prepared for the site which identifies potential contaminants and amenity related hazards, potential pathways and receptors. The conceptual model considers both onsite and offsite sources. The conceptual model is included as Figure 24.


On-Site Sources

From the assessment of historical and current activities and the limited environmental monitoring data (which has been screened against generic assessment criteria) the potential onsite sources are identified in Table 5.3.

Table 5.3 Summary of Onsite Potential Contamination and Hazards

Location Source Contaminant (C) Hazard (H)

Type Quantitative Data Y= yes N= no

Comment


Hydrocarbons C Hydrocarbons Y Some surface spills noted. DRO detected in both surface water samples, GRO in surface water sample LSW2.

Illegal waste oil disposal pit

Hydrocarbons C/H Hydrocarbons N Illegal waste oil disposal pit at the site, near the plant storage building.

Groundwater Leaching from burning area

H/C Metals Y Arsenic, copper and lead detected above relevant standards in soil samples submitted for leaching tests

Offsite pond Leaching from waste and groundwater base flow

H/C Metals Y Copper and lead above relevant Florida clean-up levels

Burning Ground Ash and clinker C Metals Y Arsenic above relevant Florida clean-up level in soils

Burning Ground Smoke C/H Combustion products

N

Off-Site Sources

The island power generation facility is located east of the landfill area. This is a diesel powered facility and a potential source of hydrocarbon contamination. No other off-site contamination sources or hazards have been identified.




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Table 5.4 Receptors


Site workers and visitors Site has open access and members of the public can access at any time.

Offsite residents The nearest properties are some 0.35 miles south of the site.

Groundwater Groundwater depth and quality is unknown. There are no known abstractions in the vicinity of the site.

Surface water in offsite ponds Most likely brackish water with possible groundwater base flow.

Booby Pond nature reserve Internationally important site approximately 0.5 miles south-west of the site.



Receptor Pathway


Adjacent residents Ingestion of dusts, inhalation of smoke

Groundwater Leaching and migration

Surface Water (offsite ponds) Run-off, migration and groundwater base flow

Fauna in Booby Pond nature reserve Smoke and combustion products from waste burning


The development of the conceptual models have identified a number of potential contaminant and hazard linkages (contaminant/hazard-pathway-receptor linkages) between receptors and the landfill site. These are tabulated in Appendix J. Each contaminant linkage has been qualitatively assessed using the following criteria:




The risk assessment criteria assessment methodology is provided within the Task 2 investigation factual report.

The updated environmental risk assessment for the site is included in Appendix J. This comprises an analysis of potential contaminant/hazard linkages (contaminant/hazard-pathway-receptor) between potential receptors and the landfill site.


The outcomes from the risk tables in Appendix J are summarised below. The first paragraph summary for each receptor considers contaminants and the second amenity hazards.


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Potential risks to site workers and visitors from combustion products and metals in soils are assessed as moderate/low and from hydrocarbons in soils are assessed as low.

Adjacent Residents

Potential dust and odour nuisance to adjacent residents is assessed as low due to the distance from the landfill. Potential risks associated with scavenging animals/birds and insects are assessed as low and medium, respectively. There is also a potential medium risk associated with nuisance from landfill fires.

Groundwater and Offsite Pools

Potential risks to groundwater from hydrocarbons are assessed as moderate and from metals are assessed as moderate/low. Risks to groundwater from ammonia are assessed as low. Risks to offsite pools from metals are assessed as moderate/low.

There is also a potential medium risk to offsite pools associated with elevated nutrients, iron and solids.

Booby Pond

Potential risks to the Booby Pond from air transport of smoke and combustion products is assessed as medium.


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6. Conclusions and Recommendations

6.1 Conclusions

Basis of Study and Data

This Task 2 environmental review of the landfill sites on Grand Cayman, Cayman Brac and Little Cayman is an interpretation of data collected from monitoring and survey in April 2015. The scope of the investigations was determined from an earlier Task 1 study (Amec Foster Wheeler, January 2015).

For George Town landfill on Grand Cayman the interpretation also includes consideration of some pre-existing analytical information available from periodic monitoring of groundwater, surface water and marine water in North Sound. No relevant pre-existing environmental monitoring information was available for the smaller landfills on Cayman Brac and Grand Cayman.

This data has been collated and screened against Florida state clean-up assessment criteria for waters and soils. Landfill gas monitoring and analysis was undertaken on the George Town and Cayman Brac sites and based on the collected data air quality modelling has been undertaken for the George Town site.

Amenity related issues have also been considered for each site; these are hazards such as dust, landfill fires and nutrients in waters for which there are no direct assessment criteria.


The George Town site is forecast to receive approximately 73,500t of municipal and commercial waste for disposal within the landfill in 2015. Other materials including scrap metals, tyres and waste oils which are stored pending recycling and account for a further 3,000-4,000t/annum. There are significant stockpiles of metal and tyres representing a number of years accumulation. The waste disposal area is an un-engineered land raise, rising to approximately 80 ft (24.4m) above sea level. The current active landfill area is not capped and has a thin soil cover on one flank. The old landfill area to the south east of the site has a thin soil cap and has to some extent naturally regenerated. A clinical waste incinerator is present in the north east part of the site.

The following have been identified as significant receptors:

Site workers and visitors (the general public have access to parts of the site);

Adjacent residential development to the west (Lakeside and Parkside Close) being only 330 feet (100m) from the landfill boundary and downwind of the site. Other residential development and a school are located north west and north respectively;

Groundwater below the site is brackish and tidal and the hydraulic gradient is believed to be to the east towards the North Sound;

Perimeter canals which flank the site to the west and north with an outfall into North Sound; and

Marine ecology within North Sound.

The contamination and amenity risk assessments have identified the following key22 risks associated with the landfill:

Site users and visitors: arsenic in soils as well as hydrogen sulphide generation on and off the landfill and methane generation on the landfill;

22 Key contamination risks are regarded as those that are assessed as moderate and above. For amenity risks, which are much more subjective in nature, key risks are defined as high risks only.


March 2016 36082rr009i3

Adjacent residents: nuisance from odour and risks from combustion products in tyre/landfill fires;

Adjacent commercial/industrial site users: hydrogen sulphide from sediments contaminated by various sources including the landfill, as well as nuisance from odour and landfill fires;

Groundwater: hydrocarbons from spills and overtopping of bunds, elevated ammonia contribution to surface water contamination via baseflow;

Surface water: hydrocarbons from spills and overtopping of bunds, ammonia and orthophosphates from groundwater; and

North Sound: ammonia and metals from canal water impacting on water quality and ecology, and eutrophication and blanketing of vegetation adjacent to the canal outfall.

The landfill also has a significant visual impact from various viewpoints.


The landfill receives around 2,200T/annum of waste. The site has nominally separate areas for disposal of municipal, green and construction and demolition waste but there is some cross contamination of waste streams. There is no engineered containment or capping of the disposal areas. Large stockpiles of scrap metal are stored at the site. Waste oils and batteries are stored in uncontained areas pending offsite transfer. There is a very small clinical waste incinerator which has intermittent operation and has been put of action since at least November 2015 resulting in clinical waste disposal in a pit in the landfill.

The following significant receptors have been identified:

Site workers and visitors (the general public have unfettered access to the site);

Adjacent residential development, three properties are located south of the site beyond which is a public beach;

Groundwater below the site is brackish and tidal and the hydraulic gradient is likely to be to the ocean to the south; and

A surface water body known as the Red Shrimp lagoon which is present on the site, and the adjacent ocean.

The contamination and amenity risk assessments have identified the following key risks associated with the landfill:

Site users and visitors: methane from landfill gas;

Groundwater: hydrocarbons from waste oil storage spills to ground; and

Surface water: metals leaching from landfill.


There is no measure of waste inputs into the site but the island resident population is small (around 170). Municipal waste deposited at the site is regularly set alight and the disposal area is effectively a burning ground. Scrap metal, waste oil and batteries are stored in uncontained areas pending off-site disposal.

The following significant receptors have been identified:

Site workers and visitors (the general public have unfettered access to the site);

Groundwater, it is unknown if this is freshwater or brackish, the hydraulic gradient is likely to be to the west;

The Booby Pond RAMSAR site located 0.5 miles south west of the site.


March 2016 36082rr009i3

The contamination and amenity risk assessments have identified the following key risks associated with the landfill:

Groundwater: hydrocarbons from illegal waste oil disposal pit.

6.2 Recommendations

Amec Foster Wheeler’s recommendations resulting from assessment and interpretation of the data in this report and the resultant risk assessments are summarised in the following tables.

Table 6.1 Recommendations for Environmental Improvements and Monitoring at George Town Landfill


1 Fugitive gas emissions from the landfill surface

Progressive engineered capping of completed areas of the landfill to minimise landfill gas emission and enable gas collection for energy recovery Application of daily cover to landfilled wastes

Reduction in emission of odorous gas constituents and methane which is a significant greenhouse gas Prevent vermin accessing the landfilled wastes

2 Landfill gas Repeat of flux box tests Bulk gas monitoring in existing gas probes at least every three months Gas pumping trials following first phase of capping

Better definition of landfill gas emission rates Ongoing evaluation of gas quality Recovery of landfill gas and use in electricity generation.

3 Incinerator emissions Establish emissions monitoring programme


4 Landfill fires Removal of stockpiled tyres which are a particular fire hazard Monitoring for airborne PAH’s during waste fires

Burning tyres pose a significant risk in terms of combustion Evaluation of potential health impact to offsite receptors (note capping of the wastes will reduce the potential for fires).


Progressive capping of the site Monitoring of existing groundwater wells on at least an annual basis

Reduce leaching potential from the wastes and impact on groundwater Continued evaluation of impacts


Monitoring in North Canal on at least a six monthly basis


7 Marine water contamination

Reinstate annual DoE sampling in North Sound

Continued evaluation of impacts. Study into eutrophication in North Sound adjacent to the landfill


March 2016 36082rr009i3

Table 6.2 Recommendations for Environmental Improvements and Monitoring at Cayman Brac Landfill


1 Clinical waste disposal in the landfill

Reinstate the incinerator to prevent direct disposal If continued landfill disposal in the short term then cover the disposal area daily

Cease landfill disposal of clinical waste Good practice and reduced risk of vermin nuisance or public health incident

2 Incinerator emissions Establish emissions monitoring programme when incinerator is operational


3 Landfill gas as a greenhouse gas

Bulk gas monitoring in existing gas probes at least every three months Consideration of whether engineered capping and gas recovery for flaring is of cost benefit

Ongoing evaluation of gas quality Potential reduction in uncontrolled gas emission by may not be economically viable due to small size of landfill


Monitoring of existing groundwater wells on at least an annual basis



Monitoring of shrimp pond on at least an annual basis


Table 6.3 Recommendations for Environmental Improvements and Monitoring at Little Cayman Landfill

Ref Source/Risk Proposed Works Objective/Rationale

1 Illegal oil disposal pit Prevent access Further assessment and remediation

Potential health and safety hazard and prevent further disposal Assessment of remediation requirements

2 Continued uncontrolled landfill expansion

Management and restrictions to prevent further expansion of burning area

Limit on uncontrolled site expansion, especially in direction of Booby Pond.

© Amec Foster Wheeler Environment & Infrastructure UK Limited

March 2016 36082rr009i3

Figures

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Figure 2George Town LandfillGroundwater Sampling Locations

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Site Boundary

Groundwater MonitoringWell

Former GroundwaterMonitoring Well

0 50 100 150 20025

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MW17 MW12

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Figure 3George Town LandfillAmmonia in Groundwater


1:5,000Scale at A3:

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Landfil l Site Boundary



0 50 100 150 20025

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MW17 MW12

MW18

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MW21(1.1mg/l)

MW8(0.47mg/l)

MW9(0.06mg/l)

MW15A(0.067mg/l)

MW19(0.052mg/l)

MW13(0.52mg/l)

MW10(mg/l)

MW14(0.99mg/l)

MW11(1.2mg/l)

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Figure 4George Town LandfillOrthophosphate in Groundwater


1:5,000Scale at A3:

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0 50 100 150 20025

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0 160 320 480 640

Feet

ALLIE

B DR

ALLIEB DR

COURTS RD

SUNFIRELN

ATHENA WAY

SPAR

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SLEEPYHOLLOW DR

BLUE LAGOON DR

SPRUCE LN

LINCOLN DR

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LANCASTER CRES

ESTERLEY TIBBETTS HWY

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NS#2 NS#3

NS#4

SW3

SW12

SW20

SW2

Pond

Leachate

SW7

Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AEX, Getmapping, Aerogrid,IGN, IGP, swisstopo, and the GIS User Community

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Figure 5George Town LandfillSurface Water Sampling Locations

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Landfill Site Boundary

Surface Water Sample Site

0 50 100 150 20025

Meters


0 160 320 480 640

Feet

ALLIE

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NS#1(10mg/l)

NS#2(3mg/l)

NS#3(2mg/l)

NS#4(2mg/l)

SW3(15mg/l)

SW12(10mg/l)

SW20(13mg/l)

SW2(10mg/l)

Pond(10mg/l)

Leachate


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Figure 6George Town LandfillBiochemical Oxygen Demandin Surface Waters

July 2015 36082-SHR033.mxd odont

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Client

Surface Water Sampling Site


0 50 100 150 20025

Meters


0 160 320 480 640

Feet

ALLIE

B DR

ALLIEB DR

COURTS RD

SUNFIRELN

ATHENA WAY

SPAR

KYS D

R

SLEEPYHOLLOW DR

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SPRUCE LN

LINCOLN DR

DIANN

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HIDDE

N LAG

OON D

R

MINE

RVA D

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NEXU

S WAY

SEYMOUR RD

LANCASTER CRES


SW3(4.8mg/l)

SW20(6.5mg/l)

SW2(3mg/l)

Pond(3mg/l)

NS#1(2.5mg/l)

SW12(2mg/l)

NS#2(1.1mg/l)

NS#3(0.51mg/l)

NS#4(0.02mg/l)


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Figure 7George Town LandfillAmmonia in Surface Waters

March 2016 36082-SHR032.mxd odont

1:5,000Scale at A3:

Client

Landfill Site Boundary

UK AmmoniaStandards (Rivers) mg/l

High < 0.7

Good 0.7 - 1.5

Moderate 1.5 - 2.6

Poor 2.6 - 6

0 50 100 150 20025

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0 160 320 480 640

Feet

ALLIE

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ALLIEB DR

COURTS RD

SUNFIRELN

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SPAR

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N LAG

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MINE

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SEYMOUR RD

LANCASTER CRES


NS#1(0.1mg/l)

NS#2(0.052mg/l)

NS#3(0.025mg/l)

NS#4(0.015mg/l)

SW3(0.031mg/l)

SW12(0.031mg/l)

SW20(0.11mg/l)

SW2(0.12mg/l)

Pond(0.083mg/l)


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Figure 8George Town LandfillOrthophosphatein Surface Waters


1:5,000Scale at A3:

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UK OrthophosphateStandards (Rivers) mg/l

High <0.0036

Good 0.0036 - 0.069

Moderate 0.069 - 0.173

Poor 0.173 - 1.0

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0 160 320 480 640

Feet

SW3

SW2

Sediment #1

Sediment #2Sediment #3

Sediment #4

ALLIE

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Figure 9George Town LandfillSediment Sampling Locations


1:5,000Scale at A3:

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Feet

GP1

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ALLIE

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LIEBDR

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AVON

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DR

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SUNFIRE LN

LANC

ASTE

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PARKW AY

DR

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FluxBox 2

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Figure 10George Town LandfillGas Probe, Flux Boxand Dust Monitoring Locations


1:5,000Scale at A3:

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Flux Box Site

Dust Sample Site

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4.47

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0

4.53

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4.746.03

10.09

34.46

23.333.27

3.36

63.27

100.4

195

31.36

8.81

0

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21.34

7.91

3.58

0

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4.35

4.81

0

7.93

80.16

17.236.68

11.71

0

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5.6

5.47

004.87

0

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Figure 11George Town LandfillAmbient H2S in Air(11/04/2015)


1:5,000Scale at A3:

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Site Boundary

H2S (ppb)

0.00 - 3.01

3.01 - 13.87

13.87 - 34.46

34.46 - 100.40

100.40 - 195.00

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4.47

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Figure 12George Town LandfillAmbient H2S in Air(18/04/2015)


1:5,000Scale at A3:

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Site Boundary

H2S (ppb)

0.00 - 3.01

3.01 - 13.87

13.87 - 34.46

34.46 - 100.40

100.40 - 195.00

0 50 100 150 20025

Meters


0 160 320 480 640

Feet

0

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1200

May

198

9 Ja

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91 S

epte

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2 M

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994

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1996

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997

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epte

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2 M

ay 2

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Janu

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2006

Sep

tem

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007

May

200

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11 S

epte

mbe

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2 M

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014

Janu

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2016

Sep

tem

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017

May

201

9 Ja

nuar

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21 S

epte

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2 M

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024

Janu

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2026

Sep

tem

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027

May

202

9 Ja

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31 S

epte

mbe

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2 M

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034

Janu

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2036

Sep

tem

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037

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203

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nuar

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41 S

epte

mbe

r 204

2 M

ay 2

044

Janu

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2046

Sep

tem

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047

May

204

9 Ja

nuar

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51 S

epte

mbe

r 205

2 M

ay 2

054

Janu

ary

2056

Sep

tem

ber 2

057

May

205

9 Ja

nuar

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61 S

epte

mbe

r 206

2 M

ay 2

064

Janu

ary

2066

Sep

tem

ber 2

067

May

206

9 Ja

nuar

y 20

71 S

epte

mbe

r 207

2 M

ay 2

074

Janu

ary

2076

Sep

tem

ber 2

077

May

207

9 Ja

nuar

y 20

81 S

epte

mbe

r 208

2 M

ay 2

084

Janu

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2086

Sep

tem

ber 2

087

May

208

9 Ja

nuar

y 20

91 S

epte

mbe

r 209

2 M

ay 2

094

Janu

ary

2096

Sep

tem

ber 2

097

May

209

9 Ja

nuar

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01 S

epte

mbe

r 210

2 M

ay 2

104

Janu

ary

2106

Sep

tem

ber 2

107

May

210

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nuar

y 21

11 S

epte

mbe

r 211

2 M

ay 2

114

Janu

ary

2116

Sep

tem

ber 2

117

May

211

9 Ja

nuar

y 21

21 S

epte

mbe

r 212

2 M

ay 2

124

Janu

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2126

Sep

tem

ber 2

127

May

212

9 Ja

nuar

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31 S

epte

mbe

r 213

2 M

ay 2

134

Janu

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2136

Sep

tem

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137

May

213

9

Bulk

land

fill g

as g

ener

aon

, m³/

hr

Bulk landfill gas genera on at George Town landfill site from GasSim modelling

Average waste scenario Wet waste scenario Saturated waste scenario

Key assump ons:- GasSim modelling based on 30 years of landfilling from 1989-2018 (solid waste management strategy to be in place by 2017)- No liner, capping or gas management system modelled- Site modelled as a land raise- Rainfall based on data from Phase I Environmental Review (1.63 m/yr) with 20% s.d.- Methane/carbon dioxide split in landfill gas derived from gas sample lab analysis (60:40 methane:carbon dioxide)- Total waste volume based on LIDAR data from 2013 (~1.1M m³)- Total waste inputs and composi on based on 2011-14 composi on data with tonnages back-calculated to show an 3-7% year-on-year increase since the start of filling- Waste composi on uses default GasSim 1980s-2010 in absence of site-specific data- Waste types (domes c/commercial and civic amenity) based on 2011/12 data- Total waste tonnage based on average density of 0.6 tonnes/m³ based on informa on in PBS&J report and in range of 0.4-0.8 tonnes/m³

2015 summary:- Bulk landfill gas genera on (June 2015) is 595 m³/hr (average waste), 789 m³/hr (wet waste) and 327 m³/hr (saturated waste)

Cayman Islands GovernmentLandfill Site Environmental Review

Figure 13George Town Landfill - GasSim Output Graph

36082-Shr043.ai holfsJuly 2015


Figure 14George Town Landfill - Dispersion Model Domain and Discrete Receptor Locations


Output grid and points

Specified point

Area / line / volume source

Key

0

0

3

1.5

6

3.1

10

5.1

16

8.2

(knots)

(m/s)

Wind speed

0° 10°20°

30°

40°

50°

60°

70°

80°

90°

100°

110°

120°

130°

140°

150°160°

170°180°190°200°

210°

220°

230°

240°

250°

260°

270°

280°

290°

300°

310°

320°

330°340°

350°

100

200

300

400


Figure 15Wind Rose for Owen Roberts International Airport 2013-2015



Figure 16George Town Landfill - Odour Dispersion Pattern


Output grid and points

Specified point

Area / line / volume source

Key

B

E

D

C A C

D D

B

E

G

F

2 7

5

13

4

6

7

Lake

side

dev

elop

men

t

Man

grov

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Per

imet

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Figure 17George Town Landfill - Conceptual Site Model


Key

Pedro Castle formation (Hard dolomite & limestone)

Transhore formation (Marl & Limestone)

Suface water/sea

Made ground

Pedro Cdolomite

Made gr

Transho(Marl &

Suface w

Landfill

Wastewater sludges

Groundwater/surface water/tidal influence

Pathway

A

B

C

D

E

Pathways:Direct contact, inhalation of dust/vapour

Ingestion of dust/inhalation

Leaching from waste into groundwater

Lateral migration with groundwater

Ingestion and bioaccumulation

Discharge from surface water canal

Runoff

Receptors:Site workers/visitors

Adjacent residents

Adjacent commercial/industrial premises

Groundwater

Surface water in canals

Marine water in North Sound

Ecological receptors

1

2

3

4

5

6

7

Potential Contaminant Sources:

Soils around landfill area: arsenicWaste oil storage: hydrocarbonsGroundwater: ammonia & orthophosphate, metalsPerimeter canal: ammoniaCanal sediments: hydrogen sulphateLandfill: landfill gasIncinerator: emissions

Amenity Hazards:

Surface water: iron & nutrientsLandfill: odour, dust, flies, insects, birds, litter & smoke from fires

F

G

PublicBeach

ScrapMetal

ShrimpPond

HurricanePalomaWaste

GreenWaste

C & DWaste

Tyres

Oil &Batteries

SiteOffice

Incinerator

MunicipalWaste

LandfillCB2

CB3

CB4

GP21

GP22

GP23

GP24

CB1

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Based upon the Ordnance Survey Map with the permiss ion of the Controller of Her Majesty 's Stat ionery Off ice. © Crown Copyright. 100001776

Key

National Solid Waste Management StrategyLandfil l SiteEnvironmental Review

Figure 19Cayman Brac LandfillExploratory Hole Locations


1:2,500Scale at A3:

Client

Groundwater monitoring well

Gas probe

Site Boundary

0 100 200 300 40050

Feet


0 25 50 75 10012.5

Meters

PublicBeach

ScrapMetal Shrimp Pond

MunicipalWaste

Landfill

HurricanePalomaWaste

GreenWaste

C & D Waste

Tyres

Incinerator

Oil &Batteries

BSS1

BSS2BSS3BSS4

BSS6BSW1

BSW2

BSW3

BSS5

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Key


Figure 20Cayman Brac LandfillSampling Locations


1:2,500Scale at A3:

Client

Soil Sample Site


Site Boundary

0 100 200 300 40050

Feet


0 25 50 75 10012.5

Meters

C

D

A

D

C C

E

F

A

22

56

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Figure 21Cayman Brac Landfill - Conceptual Site Model


Key

Cayman formation (dolostone & limestone)

Landfill

Green waste/construction waste

Suface water/ocean

BeachBeach

Cayman(dolosto

Groundwater/surface water/tidal influence

Pathway

A

B

C

D

E



Leaching from wastes into groundwater

Lateral migration in waste groundwater

Ingestion and inhalation

Runoff


Adjacent residents/beach users

Groundwater

Water in shrimp pond

Marine water

Ecological receptors

1

2

3

4

5

6


Waste oil storage: hydrocarbonsGroundwater: ammoniaShrimp pond: metalsLandfill: Landfill gasIncinerator: emissions

Amenity Hazards:

Groundwater: iron & nutrientsShrimp pond: iron & nutrientsLandfill: odour, dust, flies, insects, birds, litter & smoke from firesDifficult waste pit

o

w

wSuface w

Beach

(dolosto

Landfill

w

w

Landfill

Green wGreen w

Suface w F

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LSS3

LSS4

LSS5

LSW2DM1

DisusedIncinerator

OldBurningGround

ScrapMetal

StorageCurrentBurningGround

IslandPowerPlant

Plant StorageBuilding

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Key


Figure 23Little Cayman LandfillSampling Locations


1:2,500Scale at A3:

Client

NameSoil Sample Site


Dust Sample Site


Land Parcel

0 100 200 300 40050

Feet


0 25 50 75 10012.5

Meters

LSW3

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AD

D

E

C

2

3

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Figure 24Little Cayman Landfill - Conceptual Site Model


Key

Limestone/marl (suspected)

Burning ground ash & clinker

Suface water/Brackish lagoon

Surface water pond

Groundwater (level unknown)

Limesto

Burning

Suface w

Surface

Groundw

A

B

C

D

E



Leaching from wastes into groundwater

Lateral migration within groundwater

Smoke from waste burning


Offsite residents

Groundwater

Booby pond

Seasonal pond

1

2

3

4

5


Waste oil storage: hydrocarbonsGroundwater: ammonia & metalsSeasonal pond: metalsBurning ground: metalsIllegal waste oil storage pit: hydrocarbons

Amenity Hazards:

Burning ground: smoke

? ?


March 2016 36082rr009i3

Appendix A Screened Groundwater Data, George Town Landfill

MW9B

MCL Unit Source 2007 2008 2011 2006 2007 2011 2013 2006 2007 2008 2010 2011 2013 2015 2006 2007 2008 2010 2011 2013 2015 2010 2006 2007 2011 2011 2015 2007 2008 2010 2011 2011 2013 2015 2006 2011 2013

General Chemistry

Ammonia 28 mg/l GW Cleanup Target Levels mg/L 1.3 0.073 0.66 30 20 11 22 14 14 21 35 35 28 6.4 6.6 7.4 7.7 8.1 8.0 7.1 41 37 150 16 19 15 9.4 0.74 6.4 6.9 9 13 12

Nitrogen, Kjeldahl mg/L 1.8 1.4 23 17 17 14 2** 17 8.8 8.5 7** 6.6** 46 16 21 17 11 39

Nitrate plus Nitrite, as N 110* mg/l 10X Primary Standard mg/L <0.050 <2.5 0.83 <0.050 <0.050 <0.05 <0.05 0.18 0.15 <0.050 0.69 <0.05 <0.018 <0.050 <0.050 <2.5 <0.050 0.12 <0.05 <0.018 <0.050 <0.050 <0.05 <0.05 <0.018 <0.050 <0.050 <0.050 <0.05 <0.05 <0.018 <0.050 0.093 <0.05

Orthophosphate mg/L <0.050 <0.050 <0.05 0.15 <0.05 0.12 0.51 0.55 0.76 0.63 0.48 0.47 0.071 0.069 <0.050 0.051 <0.05 0.060 <0.050 0.18 0.28 0.71 1.2 0.15 0.16 0.088 0.12 0.58 0.52 0.073 0.11

Phosphorus mg/L 0.13 0.35 0.4 0.2 0.57 0.7 0.53 0.28 <0.10 <0.10 <0.10 <0.10 <0.10 0.41 0.18 0.18 0.19 0.29 0.51

Chemical Oxygen Demand mg/L 310 100 64 340 760 420 230 250 1100 250 2100 800 320 250 240 640 1600 830 470 160 190 620 700 340 260 1300 220 1100 1600 460 570 340 150 330 430 170

pH 7.66 7.44 7.64 7.06 7.2 7.34 7.4 7.39 7.33 7.27 7.34 7.46 7.38 7.28 7.33 7.28 7.33 7.5 7.43 7.36 7.12 7.48 7.17 7.33 7.41 7.34 7.58 7.24 7.38 7.35 7.26 7.38

Specific Conductance umhos/cm 3000 2600 2700 12000 13000 7900 11000 20000 19000 18000 25000 24000 12000 20000 15000 17000 12000 13000 13000 11000 7000 18000 6200 8700 24000 2300 10000 9700 22000 8900 9100 14000

Total Dissolved Solids 5,000 mg/l 10X Second Standard mg/L 4700 1600 1400 6300 7900 4800 6500 11000 9600 9100 9700 13000 7100 15000 9600 7300 8500 4100 3900 7700 8800 5100 4100 9100 4100 4800 18000 12000 13000 3400 5800 13000 16000 4900 4300 8600

Total Suspended Solids mg/L 75 680 87 34 250 170 24 67 18 12 180 28 17 20 16

Turbidity NTU 5.2 74 0.68 50 36 2200 130 220 67 8.9 12 8.5 14 76 50 64 50 3.2 35 25 70 160 160 290 120 70 75 2100 72 400 69 18

Biochemical Oxygen Demand mg/L <2.0 <2.0 <2 4.4 12 7.8 14 18 18 11 19 38 <81.00 38 32 32 <2.0 31 14 <72.00 18 15 26 17 36 <168.00 26 25 14 6 <2 18 42 7.4 6.5

Acetone 63000 ug/L GW Cleanup Target Levels ug/L <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25

Acrylonitrile 420 ug/L GW Cleanup Target Levels ug/L <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20

Benzene 10 ug/L 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.38 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.38 <1 <1 <1 <1 <1 <0.38 <1 <1

Bromochloromethane 910 ug/L GW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.52 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.52 <1 <1 <1 <1 <1 <0.52 <1 <1

Bromodichloromethane 6 ug/L GW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

Bromoform 44 ug/L GW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.71 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.71 <1 <1 <1 <1 <1 <0.71 <1 <1

Carbon disulfide 7000 ug/L GW Cleanup Target Levels ug/L <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 2.5 <2 <2 <2 <2 <2 <2 <2

Carbon tetrachloride 30 ug/L 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

Chlorobenzene 1,000 ug/L 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 8.5 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

Chloroethane 120 ug/L GW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.76 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.76 <1 <1 <1 <1 <1 <0.76 <1 <1

Chloroform 700 ug/L GW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.60 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.60 <1 <1 <1 <1 <1 <0.60 <1 <1

Dibromochloromethane 4 ug/L GW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.85 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.85 <1 <1 <1 <1 <1 <0.85 <1 <1

1,2-Dibromo-3-Chloropropane 2 ug/L 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

1,2-Dibromoethane (EDB) 0.2 ug/L 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

1,2-Dichlorobenzene 6,000 ug/L 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

1,4-Dichlorobenzene 750 ug/L 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.64 <1 <1 <1 <1 <1 <1 3.1 2.4 <1 <0.64 <1 <1 <1 <1 <1 <0.64 <1 <1

trans-1,4-Dichloro-2-butene No Standard ug/L <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2

1,1-Dichloroethane 700 ug/L GW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

1,2-Dichloroethane 30 ug/L 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

1,1-Dichloroethene 70 ug/l 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

cis-1,2-Dichloroethene 700 ug/l 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

trans-1,2-Dichloroethene 1,000 ug/l 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

1,2-Dichloropropane 50 ug/L 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

cis-1,3-Dichloropropene 4 ug/L GW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

trans-1,3-Dichloropropene 4 ug/L GW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

Ethylbenzene 300 ug/L 10X Second Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

2-Hexanone 2800 ug/L GW Cleanup Target Levels ug/L <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

Bromomethane 98 ug/L GW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.98 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.98 <1 <1 <1 <1 <1 <0.98 <1 <1

Chloromethane (methyl chloride) 27 ug/L GW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.83 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.83 <1 <1 <1 <1 <1 <0.83 <1 <1

Dibromomethane (EDB) 0.2 ug/l 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.59 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.59 <1 <1 <1 <1 <1 <0.59 <1 <1

Methylene Chloride 50 ugL 10X Primary Standard ug/L <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <3.0 <5 <5 <5 <5 <5 <5 <5 <5 <5 <3.0 <5 <5 <5 <5 <5 <3.0 <5 <5

Methyl Ethyl Ketone 42000 ug/L GW Cleanup Target Levels ug/L <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

Iodomethane No Standard ug/L <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5

methyl isobutyl ketone 5600 ug/L GW Cleanup Target Levels ug/L <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

Styrene 1,000 ug/L 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1.0 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1.0 <1 <1 <1 <1 <1 <1.0 <1 <1

1,1,1,2-Tetrachloroethane 13 ug/L GW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.52 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.52 <1 <1 <1 <1 <1 <0.52 <1 <1

1,1,2,2-Tetrachloroethane 2 ug/L GW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

Tetrachloroethene 30 ug/L 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.58 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.58 <1 <1 <1 <1 <1 <0.58 <1 <1

Toluene 400 ug/L 10X Second Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.70 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.70 <1 <1 <1 <1 <1 <0.70 <1 <1

1,1,1-Trichloroethane 2,000 ug/L 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

1,1,2-Trichloroethane 50 ug/L 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

Trichloroethene 30 ug/L 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

Trichlorofluoromethane 21000 ug/L GW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.52 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.52 <1 <1 <1 <1 <1 <0.52 <1 <1

1,2,3-Trichloropropane 0.2 ug/L GW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.84 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.84 <1 <1 <1 <1 <1 <0.84 <1 <1

8260B Volatile Organic Compounds

Vinyl acetate 880 ug/L GW Cleanup Target Levels ug/L <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2

Vinyl chloride 10 ug/l 10X Primary Standard ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <0.50 <1 <1

Xylenes, Total 200 ug/l 10X Second Standard ug/L <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 2.5 <2 <2 <2 <2 <2

Antimony 0.06 mg/L 10X Primary Standard mg/L <0.0060 <0.0060 <0.02 <0.0060 <0.0060 <0.02 <0.02 <0.0060 <0.0060 <0.0060 <0.02 <0.02 <0.010 <0.0060 <0.0060 <0.0060 <0.02 <0.02 <0.0060 <0.02 <0.02 <0.010 <0.0060 <0.0060 <0.0060 <0.02 <0.02 <0.010 <0.0060 <0.02 <0.02

Arsenic 0.1 mg/L 10X Primary Standard mg/L <0.010 <0.010 <0.02 <0.010 <0.010 <0.02 <0.02 0.019 <0.010 <0.010 <0.02 <0.02 <0.070 0.013 0.011 <0.010 <0.02 <0.02 <0.010 <0.02 0.044 0.0078 <0.010 <0.010 0.014 <0.02 <0.02 <0.020 0.049 <0.02 <0.02

Barium 20 mg/L 10X Primary Standard mg/L 0.07 0.11 0.095 0.045 0.018 0.085 0.044 0.029 0.019 0.015 0.015 <0.01 0.017 0.014 0.013 0.013 <0.01 <0.01 0.062 0.062 0.051 0.02 0.072 0.082 0.068 0.05 0.022 0.022 0.11 0.068 0.018

Beryllium 0.04 mg/L 10X Primary Standard mg/L <0.0030 <0.0030 <0.004 <0.0030 <0.0030 <0.004 <0.004 <0.0030 <0.0030 <0.0030 <0.004 <0.004 <0.0010 <0.0030 <0.0030 <0.0030 <0.004 <0.004 <0.0030 <0.004 <0.004 <0.0010 <0.0030 <0.0030 <0.0030 <0.004 <0.004 <0.0010 <0.0030 <0.004 <0.004

Cadmium 0.05 mg/L 10X Primary Standard mg/L <0.0050 <0.0050 <0.005 <0.0050 <0.0050 <0.005 <0.005 <0.0050 <0.0050 <0.0050 <0.005 <0.005 <0.0010 <0.0050 <0.0050 <0.0050 <0.005 <0.005 <0.0050 <0.005 <0.005 <0.0010 <0.0050 <0.005 <0.0050 <0.005 <0.005 <0.0010 <0.0050 <0.005 <0.005

Chromium 1 mg/L 10X Primary Standard mg/L <0.010 <0.010 <0.01 0.012 <0.010 <0.01 <0.01 0.03 0.02 <0.010 0.016 0.023 0.018 0.012 <0.010 <0.010 <0.01 <0.01 0.011 <0.01 0.079 0.014 0.011 <0.010 0.015 <0.01 <0.01 0.0060 0.025 <0.01 <0.01

Cobalt 1400 ug/L GW Cleanup Target Levels mg/L <0.010 <0.010 <0.01 <0.010 <0.010 <0.01 <0.01 <0.010 <0.010 <0.010 <0.01 <0.01 <0.0030 <0.010 <0.010 <0.010 <0.01 <0.01 <0.010 <0.01 <0.01 <0.0030 <0.010 <0.010 <0.010 <0.01 <0.01 <0.0030 <0.010 <0.01 <0.01

Copper 10 mg/L 10X Second Standard mg/L 0.033 0.083 <0.02 <0.020 <0.020 <0.02 <0.02 <0.020 <0.020 <0.020 <0.02 <0.02 0.0025 <0.020 <0.020 <0.020 <0.02 <0.02 <0.020 <0.02 <0.02 0.011 <0.020 <0.020 <0.020 <0.02 <0.02 0.0062 <0.020 <0.02 <0.02

Iron 3 mg/L 10X Second Standard mg/L 0.7 3.4 <0.05 5.2 0.8 7.3 6.9 5.6 3.3 0.72 <0.05 <0.05 0.16 0.051 0.096 <0.05 <0.05 6.5 3.6 0.67 0.46 0.066 0.59 <0.05 0.49 0.96 <0.05 <0.05

Lead 0.15 mg/L 10X Primary Standard mg/L 0.014 0.05 <0.01 <0.0050 <0.0050 <0.01 <0.01 <0.0050 <0.0050 <0.0050 <0.01 <0.01 0.0058 <0.0050 <0.0050 <0.0050 <0.01 <0.01 0.042 <0.01 <0.01 0.011 <0.0050 <0.005 <0.0050 <0.01 <0.01 0.0079 <0.0050 <0.01 <0.01

Magnesium No Standard mg/L 58 58 43 180 270 210 280 300 410 310 530 290 330 290 330 270 270 160 170 140 420 <0.010 290 370 590 120 200 320

Nickel 1 mg/L 10X Primary Standard mg/L <0.040 <0.040 <0.04 <0.040 <0.040 <0.04 <0.04 <0.040 <0.040 <0.040 <0.04 <0.04 <0.0030 <0.040 <0.040 <0.040 <0.04 <0.04 <0.040 <0.04 <0.04 <0.0030 <0.040 <0.040 <0.040 <0.04 <0.04 <0.0030 <0.040 <0.04 <0.04

Selenium 0.5 mg/L 10X Primary Standard mg/L <0.010 <0.010 <0.02 <0.010 <0.010 <0.02 <0.04 <0.010 <0.010 <0.010 <0.02 <0.04 <0.0040 <0.010 <0.010 <0.010 <0.02 <0.04 <0.010 <0.02 <0.02 <0.0040 <0.010 <0.010 <0.010 <0.02 <0.04 <0.0040 <0.010 <0.02 <0.04

Silver 1 mg/L 10X Second Standard mg/L <0.010 <0.010 <0.01 <0.010 <0.010 <0.01 <0.01 <0.010 <0.010 <0.010 <0.01 <0.01 <0.0020 <0.010 <0.010 <0.010 <0.01 <0.01 <0.010 <0.01 <0.01 <0.0020 <0.010 <0.010 <0.010 <0.01 <0.01 <0.0020 <0.010 <0.01 <0.01

Thallium 0.02 mg/L 10X Primary Standard mg/L <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.0040 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.0040 <0.025 <0.025 <0.025 <0.025 <0.025 <0.0040 <0.025 <0.025 <0.025

Vanadium 490 ug/L GW Cleanup Target Levels mg/L <0.010 <0.010 <0.01 0.011 0.011 <0.01 <0.01 0.025 0.021 0.011 0.019 0.016 0.013 <0.010 <0.010 <0.010 <0.01 <0.01 <0.010 <0.01 0.018 <0.0030 <0.010 <0.010 <0.010 <0.01 <0.01 <0.0030 <0.010 <0.01 <0.01

Zinc 50 mg/L 10X Second Standard mg/L 0.048 0.19 0.047 0.035 <0.020 <0.02 <0.02 0.027 0.067 0.027 <0.02 <0.02 <0.0080 0.069 0.043 0.12 <0.02 <0.02 0.052 <0.02 <0.02 0.040 0.042 <0.020 0.069 <0.02 <0.02 0.017 0.19 <0.02 <0.02

7470A Mercury in Liquid Waste (Manual Cold Vapor Technique)

Mercury 0.02 mg/L 10X Primary Standard mg/L <0.00020 <0.00020 <0.0002 <0.00020 <0.00020 <0.0002 <0.0002 <0.00020 <0.00020 <0.00020 <0.0002 <0.0002 <0.070 <0.00020 <0.00020 <0.00020 <0.0002 <0.0002 <0.00020 <0.0002 <0.0002 <0.070 <0.00020 <0.00020 <0.00020 <0.0002 <0.0002 <0.070 <0.00020 <0.0002 <0.0002

PCBs

PCB-1016 *** ug/l 10X Primary Standard ug/l <1 <0.95 <0.96 <1 <0.97 <0.11 <1 <19 <0.96 <1 <0.11 <1 <4.8 <0.11 <0.98 <0.96

PCB-1221 *** ug/l 10X Primary Standard ug/l <2 <1.9 <1.9 <2 <1.9 <0.088 <2 <38 <1.9 <2.1 <0.088 <2 <9.5 <0.088 <2 <1.9






Persticides

4,4'-DDD 1 ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.0012 <0.95 <0.0012 <0.24 <0.0012 <0.048

4,4'-DDE 1 ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.00088 <0.95 <0.00088 <0.24 <0.00088 <0.048

4,4'-DDT 1 ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.0016 <0.95 <0.0016 <0.24 <0.0016 <0.048

Aldrin 0.02 ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.0012 <0.95 <0.0012 <0.24 <0.0012 <0.048

alpha-BHC 0.06 ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.0014 <0.95 <0.0014 <0.24 <0.0014 <0.048

beta-BHC 0.2 ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.0012 <0.95 <0.0012 <0.24 <0.0012 <0.048

Chlordane (technical) *** ug/l 10X Primary Standard ug/l <0.48 <0.49 <0.0017 <9.5 <0.0017 <2.4 <0.0017 <0.48

delta-BHC 21 ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.00084 <0.95 <0.00084 <0.24 <0.00084 <0.048

Dieldrin 0.02 ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.0012 <0.95 <0.0012 <0.24 <0.0012 <0.048

Endosulfan I 420 ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.0012 <0.95 <0.0012 <0.24 <0.0012 <0.048

Endosulfan II 420 ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.0030 <0.95 <0.0030 <0.24 <0.0030 <0.048

Endosulfan sulfate 420 ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.00084 <0.95 <0.00084 <0.24 <0.00084 <0.048

Endrin *** ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.0012 <0.95 <0.0012 <0.24 <0.0012 <0.048

Endrin aldehyde *** ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.0011 <0.95 <0.0011 <0.24 <0.0011 <0.048

Endrin ketone *** ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.0015 <0.95 <0.0015 <0.24 <0.0015 <0.048

gamma-BHC (Lindane) *** ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.010 <0.95 <0.010 <0.24 <0.010 <0.048

Heptachlor *** ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.0012 <0.95 <0.0012 <0.24 <0.0012 <0.048

Heptachlor epoxide *** ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.0013 <0.95 <0.0013 <0.24 <0.0013 <0.048

Methoxychlor *** ug/l 10X Primary Standard ug/l <0.048 <0.049 <0.0016 <0.95 <0.0016 <0.24 <0.0016 <0.048

Toxaphene *** ug/l 10X Primary Standard ug/l <4.8 <4.9 <0.12 <95 <0.12 <24 <0.12 <4.8

Hydrocarbons

Diesel Range Organics [C10-C28] No Standard mg/l 1.1 1.4 0.48 0.19 0.066

Gasoline Range Organics (GRO)-C6-C10 No Standard mg/l <0.047 <0.047 <0.047 <0.05 <0.047

Other

Boron 14000 ug/l 10X Minimum criteria mg/l 650 2700 2.5 3.4 3.3 2.5 2.1 1.4 4000 1.8 2.7 2300 1.8

Cyanide, Total *** ug/l 10X Primary Standard mg/l <0.01 <0.01 <0.01 <0.01 <0.01 0.020 <0.01 <0.01 0.022 <0.01 <0.01 0.052 <0.01 <0.01 <0.0070 <0.01 <0.01

*** = Equal to 10 times the value provided in Chapter 62-520, F.A.C. Marks a value above the Florida Clean up Standard

Florida Clean up Standard

Low Yield/ Poor Quality Criteria MW1 MW5

6010B Inductively Coupled Plasma - Atomic Emission Spectometry - Total Recoverable

8260B Volatile Organic Compounds by GC/MS

MW14Reporting

Unit MW10 MW12MW8 MW9 MW11 MW13

H:\Projects\36082 NOR Cayman\Data\Mon Data\GWplots_2006_2015.xlsx Page 1 of 2

MCL Unit Source

General Chemistry

Ammonia 28 mg/l GW Cleanup Target Levels mg/L

Nitrogen, Kjeldahl mg/L

Nitrate plus Nitrite, as N 110* mg/l 10X Primary Standard mg/L

Orthophosphate mg/L

Phosphorus mg/L

Chemical Oxygen Demand mg/L

pH

Specific Conductance umhos/cm

Total Dissolved Solids 5,000 mg/l 10X Second Standard mg/L

Total Suspended Solids mg/L

Turbidity NTU

Biochemical Oxygen Demand mg/L

Acetone 63000 ug/L GW Cleanup Target Levels ug/L

Acrylonitrile 420 ug/L GW Cleanup Target Levels ug/L

Benzene 10 ug/L 10X Primary Standard ug/L

Bromochloromethane 910 ug/L GW Cleanup Target Levels ug/L

Bromodichloromethane 6 ug/L GW Cleanup Target Levels ug/L

Bromoform 44 ug/L GW Cleanup Target Levels ug/L

Carbon disulfide 7000 ug/L GW Cleanup Target Levels ug/L

Carbon tetrachloride 30 ug/L 10X Primary Standard ug/L

Chlorobenzene 1,000 ug/L 10X Primary Standard ug/L

Chloroethane 120 ug/L GW Cleanup Target Levels ug/L

Chloroform 700 ug/L GW Cleanup Target Levels ug/L

Dibromochloromethane 4 ug/L GW Cleanup Target Levels ug/L

1,2-Dibromo-3-Chloropropane 2 ug/L 10X Primary Standard ug/L

1,2-Dibromoethane (EDB) 0.2 ug/L 10X Primary Standard ug/L

1,2-Dichlorobenzene 6,000 ug/L 10X Primary Standard ug/L

1,4-Dichlorobenzene 750 ug/L 10X Primary Standard ug/L

trans-1,4-Dichloro-2-butene No Standard ug/L

1,1-Dichloroethane 700 ug/L GW Cleanup Target Levels ug/L

1,2-Dichloroethane 30 ug/L 10X Primary Standard ug/L

1,1-Dichloroethene 70 ug/l 10X Primary Standard ug/L

cis-1,2-Dichloroethene 700 ug/l 10X Primary Standard ug/L

trans-1,2-Dichloroethene 1,000 ug/l 10X Primary Standard ug/L

1,2-Dichloropropane 50 ug/L 10X Primary Standard ug/L

cis-1,3-Dichloropropene 4 ug/L GW Cleanup Target Levels ug/L

trans-1,3-Dichloropropene 4 ug/L GW Cleanup Target Levels ug/L

Ethylbenzene 300 ug/L 10X Second Standard ug/L

2-Hexanone 2800 ug/L GW Cleanup Target Levels ug/L

Bromomethane 98 ug/L GW Cleanup Target Levels ug/L

Chloromethane (methyl chloride) 27 ug/L GW Cleanup Target Levels ug/L

Dibromomethane (EDB) 0.2 ug/l 10X Primary Standard ug/L

Methylene Chloride 50 ugL 10X Primary Standard ug/L

Methyl Ethyl Ketone 42000 ug/L GW Cleanup Target Levels ug/L

Iodomethane No Standard ug/L

methyl isobutyl ketone 5600 ug/L GW Cleanup Target Levels ug/L

Styrene 1,000 ug/L 10X Primary Standard ug/L

1,1,1,2-Tetrachloroethane 13 ug/L GW Cleanup Target Levels ug/L

1,1,2,2-Tetrachloroethane 2 ug/L GW Cleanup Target Levels ug/L

Tetrachloroethene 30 ug/L 10X Primary Standard ug/L

Toluene 400 ug/L 10X Second Standard ug/L

1,1,1-Trichloroethane 2,000 ug/L 10X Primary Standard ug/L

1,1,2-Trichloroethane 50 ug/L 10X Primary Standard ug/L

Trichloroethene 30 ug/L 10X Primary Standard ug/L

Trichlorofluoromethane 21000 ug/L GW Cleanup Target Levels ug/L

1,2,3-Trichloropropane 0.2 ug/L GW Cleanup Target Levels ug/L


Vinyl acetate 880 ug/L GW Cleanup Target Levels ug/L

Vinyl chloride 10 ug/l 10X Primary Standard ug/L

Xylenes, Total 200 ug/l 10X Second Standard ug/L

Antimony 0.06 mg/L 10X Primary Standard mg/L

Arsenic 0.1 mg/L 10X Primary Standard mg/L

Barium 20 mg/L 10X Primary Standard mg/L

Beryllium 0.04 mg/L 10X Primary Standard mg/L

Cadmium 0.05 mg/L 10X Primary Standard mg/L

Chromium 1 mg/L 10X Primary Standard mg/L

Cobalt 1400 ug/L GW Cleanup Target Levels mg/L

Copper 10 mg/L 10X Second Standard mg/L

Iron 3 mg/L 10X Second Standard mg/L

Lead 0.15 mg/L 10X Primary Standard mg/L

Magnesium No Standard mg/L

Nickel 1 mg/L 10X Primary Standard mg/L

Selenium 0.5 mg/L 10X Primary Standard mg/L

Silver 1 mg/L 10X Second Standard mg/L

Thallium 0.02 mg/L 10X Primary Standard mg/L

Vanadium 490 ug/L GW Cleanup Target Levels mg/L

Zinc 50 mg/L 10X Second Standard mg/L


Mercury 0.02 mg/L 10X Primary Standard mg/L

PCBs

PCB-1016 *** ug/l 10X Primary Standard ug/l







Persticides

4,4'-DDD 1 ug/l 10X Primary Standard ug/l

4,4'-DDE 1 ug/l 10X Primary Standard ug/l

4,4'-DDT 1 ug/l 10X Primary Standard ug/l

Aldrin 0.02 ug/l 10X Primary Standard ug/l

alpha-BHC 0.06 ug/l 10X Primary Standard ug/l

beta-BHC 0.2 ug/l 10X Primary Standard ug/l

Chlordane (technical) *** ug/l 10X Primary Standard ug/l

delta-BHC 21 ug/l 10X Primary Standard ug/l

Dieldrin 0.02 ug/l 10X Primary Standard ug/l

Endosulfan I 420 ug/l 10X Primary Standard ug/l

Endosulfan II 420 ug/l 10X Primary Standard ug/l

Endosulfan sulfate 420 ug/l 10X Primary Standard ug/l

Endrin *** ug/l 10X Primary Standard ug/l

Endrin aldehyde *** ug/l 10X Primary Standard ug/l

Endrin ketone *** ug/l 10X Primary Standard ug/l

gamma-BHC (Lindane) *** ug/l 10X Primary Standard ug/l

Heptachlor *** ug/l 10X Primary Standard ug/l

Heptachlor epoxide *** ug/l 10X Primary Standard ug/l

Methoxychlor *** ug/l 10X Primary Standard ug/l

Toxaphene *** ug/l 10X Primary Standard ug/l

Hydrocarbons

Diesel Range Organics [C10-C28] No Standard mg/l

Gasoline Range Organics (GRO)-C6-C10 No Standard mg/l

Other

Boron 14000 ug/l 10X Minimum criteria mg/l

Cyanide, Total *** ug/l 10X Primary Standard mg/l

*** = Equal to 10 times the value provided in Chapter 62-520, F.A.C.


Low Yield/ Poor Quality Criteria

6010B Inductively Coupled Plasma - Atomic Emission Spectometry - Total Recoverable


Reporting

Unit

Comment

MW-15A MW 17 MW 19 MW 20 MW 21

2015 2006 2007 2011 2013 2015 2006 2013 2011 2011 2013 2015 2015 2015

16 6.6 6.3 6.9 14 3.2 8.3 5.4 12 34 4.4 6.6 270 0.1 22.3 270.0 Ammonia is produced by decaying vegetation

13 8.2 1.4 16.5 46.0

<0.018 <0.050 <0.050 0.69 <0.05 <0.018 <0.050 <0.05 0.15 0.17 <0.05 <0.018 <0.018 <0.018 0.093 0.3 0.8

0.099 0.073 0.055 0.067 0.067 0.16 0.082 <0.05 0.15 0.052 0.061 1.1 0.051 0.3 1.2

0.22 <0.10 1.3 0.13 0.4 1.3

130 240 540 640 210 110 140 290 470 460 430 18 170 1000 18.0 524.0 2100.0

7.53 7.17 7.2 7.42 7.47 7.35 7.29 7.22 7.26 7.1 7.4 7.7

13000 18000 14000 16000 12000 19000 10000 6400 10000 2300.0 12914.6 25000.0

7900 6900 3300 3500 10000 11000 6300 12000 5400 3500 6300 2600 11000 19000 1400.0 7830.6 19000.0 TDS are typically high in seawater and brackish water

33 <5.0 2600 12 253.6 2600.0

120 0.33 17 2.8 330 4 160 3000 41 0.3 253.9 3000.0

<90 11 20 10 1800 5.1 3.8 46 29 18 10 <2.0 20 80 3.8 67.9 1800.0

<25 <25 <25 <25 <25 <25 <25 <25 <25 <25

<20 <20 <20 <20 <20 <20 <20 <20 <20 <20

<1 <1 <1 <1 <1 <1 <1 <0.38 <0.38 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.52 <0.52 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.71 <0.71 <1 <1 <1

<2 <2 <2 <2 <2 <2 <2 <2 2.5 2.5

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 8.5 8.5

<1 <1 <1 <1 <1 <1 <1 <0.76 <0.76 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.60 <0.60 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.85 <0.85 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 Detection limit does not enable comparison with clean up standard

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.64 <0.64 <1 2.8 3.1

<2 <2 <2 <2 <2 <2 <2 <2 <2 <2

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 1 1

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 <1 <1

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10

<1 <1 <1 <1 <1 <1 <1 <0.98 <0.98 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.83 <0.83 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.59 <0.59 <1 <1 <1 Detection limit does not enable comparison with clean up standard

<5 <5 <5 <5 <5 <5 <5 <3.0 <3.0 <5 <5 <5

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10

<5 <5 <5 <5 <5 <5 <5 <5 <5 <5

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10

<1 <1 <1 <1 <1 <1 <1 <1.0 <1.0 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.52 <0.52 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.58 <0.58 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.70 <0.70 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.52 <0.52 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <0.84 <0.84 <1 <1 <1 Detection limit does not enable comparison with clean up standard

<2 <2 <2 <2 <2 <2 <2 <2 <2 <2

<1 <1 <1 <1 <1 <1 <1 <0.50 <0.50 <1 <1 <1

<2 <2 <2 <2 <2 <2 <2 <2 2.5 <2

<0.0060 <0.0060 <0.02 <0.02 <0.0060 <0.02 <0.02 <0.02 <0.02 <0.010 <0.02 <0.02 <0.02

0.031 <0.010 <0.02 <0.02 0.015 <0.02 <0.02 <0.02 <0.02 <0.0040 <0.02 0.02 0.05

0.057 0.014 <0.01 0.014 0.082 0.013 0.061 0.056 0.012 0.018 <0.01 0.05 0.11

<0.0030 <0.0030 <0.004 <0.004 <0.0030 <0.004 <0.004 <0.004 <0.004 <0.0010 <0.004 <0.004 <0.004

<0.0050 <0.0050 <0.005 <0.005 <0.0050 <0.005 <0.005 <0.005 <0.005 <0.0010 <0.005 <0.005 <0.005

0.021 <0.010 <0.01 <0.01 0.035 <0.01 <0.01 <0.01 <0.01 <0.0020 0.0 0.02 0.08

<0.010 <0.010 <0.01 <0.01 <0.010 <0.01 <0.01 <0.01 <0.01 <0.0030 <0.01 <0.01 <0.01

<0.020 <0.020 <0.02 <0.02 0.055 <0.02 <0.02 <0.02 <0.02 <0.0020 0.0 0.04 0.08

3.8 <0.050 <0.05 <0.05 11 1.1 <0.05 <0.05 <0.05 0.1 2.76 11.00 Iron is ubiquitous in the marine environment

<0.0050 <0.0050 <0.01 <0.01 0.034 <0.01 <0.01 <0.01 <0.01 0.0043 0.0 0.03 0.05

210 350 290 350 200 420 200 170 260 43.0 268.31 590.00

<0.040 <0.040 <0.04 <0.04 <0.040 <0.04 <0.04 <0.04 <0.04 <0.0030 <0.04 <0.04 <0.04

<0.010 <0.010 <0.02 <0.04 <0.010 <0.04 <0.02 <0.02 <0.04 <0.0040 <0.04 <0.04 <0.04

<0.010 <0.010 <0.01 <0.01 <0.010 <0.01 <0.01 <0.01 <0.01 <0.0020 <0.01 <0.01 <0.01

<0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.0040 <0.025 <0.025 <0.025 Detection limit does not enable comparison with clean up standard

<0.010 <0.010 <0.01 <0.01 0.037 0.016 <0.01 <0.01 <0.01 <0.0030 <0.01 0.02 0.04

0.46 <0.020 <0.02 <0.02 0.077 <0.02 <0.02 <0.02 <0.02 <0.0080 <0.02 0.10 0.46

<0.00020 <0.00020 <0.0002 <0.0002 0.00032 <0.0002 <0.0002 <0.0002 <0.0002 <0.070 <0.0002 0.0003 0.0003

<0.99 <0.95 <0.99 <1 <0.95 <19 <0.11 <0.11 <0.95 <0.95 <0.95

<2 <1.9 <2 <2 <1.9 <38 <0.088 <0.088 <1.9 <1.9 <1.9

<0.99 <0.95 <0.99 <1 <0.95 <19 <0.040 <0.040 <0.95 <0.95 <0.95

<0.99 <0.95 <0.99 <1 <0.95 <19 <0.014 <0.014 <0.95 <0.95 <0.95

<0.99 <0.95 <0.99 <1 <0.95 <19 <0.0080 <0.0080 <0.95 <0.95 <0.95

<0.99 <0.95 <0.99 <1 <0.95 <19 <0.023 <0.023 <0.95 <0.95 <0.95

<0.99 <0.95 <0.99 <1 <0.95 <19 <0.061 <0.061 <0.95 <0.95 <0.95

<0.048 <0.05 <0.95 <0.0012 <0.0012 <0.049 <0.049 <0.049

<0.048 <0.05 <0.95 <0.00088 <0.00088 <0.049 <0.049 <0.049

<0.048 <0.05 <0.95 <0.0016 <0.0016 <0.049 <0.049 <0.049

<0.048 <0.05 <0.95 <0.0012 <0.0012 <0.049 <0.049 <0.049

<0.048 <0.05 <0.95 <0.0014 <0.0014 <0.049 <0.049 <0.049

<0.048 <0.05 <0.95 <0.0012 <0.0012 <0.049 <0.049 <0.049

<0.48 <0.5 <9.5 <0.0017 <0.0017 <0.49 <0.49 <0.49

<0.048 <0.05 <0.95 <0.00084 <0.00084 <0.049 <0.049 <0.049

<0.048 <0.05 <0.95 <0.0012 <0.0012 <0.049 <0.049 <0.049

<0.048 <0.05 <0.95 <0.0012 <0.0012 <0.049 <0.049 <0.049

<0.048 <0.05 <0.95 <0.0030 <0.0030 <0.049 <0.049 <0.049

<0.048 <0.05 <0.95 <0.00084 <0.00084 <0.049 <0.049 <0.049

<0.048 <0.05 <0.95 <0.0012 <0.0012 <0.049 <0.049 <0.049

<0.048 <0.05 <0.95 <0.0011 <0.0011 <0.049 <0.049 <0.049

<0.048 <0.05 <0.95 <0.0015 <0.0015 <0.049 <0.049 <0.049

<0.048 <0.05 <0.95 <0.010 <0.010 <0.049 <0.049 <0.049

<0.048 <0.05 <0.95 <0.0012 <0.0012 <0.049 <0.049 <0.049

<0.048 <0.05 <0.95 <0.0013 <0.0013 <0.049 <0.049 <0.049

<0.048 <0.05 <0.95 <0.0016 <0.0016 <0.049 <0.049 <0.049

<4.8 <5 <95 <0.12 <0.12 <4.9 <4.9 <4.9

1.0 0.38 1.7 1 3.8 0.61 1.5 18 0.1 2.8 18.0

<0.047 <0.047 <0.05 <0.05 <0.047 <0.047 0.3 <0.05 <0.05 <0.05

1400 1.7 2.1 1900 2000 2.4 <0.1 788.3 4000.0

<0.007 <0.01 <0.01 <0.0070 <0.01 <0.01 <0.01 <0.01 <0.0035 <0.0070 0.15 <0.01 - 0.150

MW15Min Mean Max

MW16 MW 18

H:\Projects\36082 NOR Cayman\Data\Mon Data\GWplots_2006_2015.xlsx Page 2 of 2


March 2016 36082rr009i3

Appendix B Screened Surface Water Data, George Town Landfill

POND near SW1 SW20

General Chemistry MCL Unit Source 2006 2007 2008 2010 20112011

Duplicate2013 2015 2015 2006 2007 2008 2010 2011 2013 2015 2006 2007 2008 2010 2011 2013 2015 2010 2011 2013 2015 2015 2006 2007 2008 2010 2011

Ammonia N/A mg/L SW Cleanup Target Levels mg/L 2.6 0.32 5.5 1.6 1.9 7.8 2.5 3 5.1 1.7 4.4 4.5 13 3.0 5 4.7 0.44 2 6.5 4.8 0.39 1.4 3.6 2 6.5 0.32 3.80 13 54 44 13 1.5

Nitrogen, Kjeldahl mg/L 9.5 4.3 0.61 5.7 3.7 6 12 7.1 2 5 10 11 7.9 4.7 2.5 9.4 1.9 5.5 9.3 0.61 6.01 12 24 64 52 17

Nitrate Nitrite as N N/A mg/L SW Cleanup Target Levels mg/L <0.050 <0.050 <0.050 <0.05 0.16 <0.05 <0.05 <0.018 0.069 <0.050 <0.050 <2.5 <0.050 <0.05 <0.05 <0.018 <0.050 <0.050 <2.5 <0.050 <0.05 <0.05 <0.018 <2.5 <0.05 0.067 <0.018 <0.018 0.067 0.10 0.16 <0.050 0.16 0.3 <0.05 <0.05

Orthophosphate mg/L 0.051 <0.050 <0.05 0.086 0.076 0.44 0.1 0.083 0.078 <0.050 <0.050 0.12 0.32 0.12 <0.050 <0.050 <0.050 <0.05 0.069 0.031 <0.050 <0.05 <0.05 0.031 0.11 0.031 0.12 0.44 <0.050 <0.05 <0.05 <0.05

Phosphorus mg/L 0.26 0.12 <0.10 0.18 0.23 0.17 0.11 0.12 0.24 0.14 0.26 0.1 0.12 0.1 0.17 0.26 0.53 0.28 0.94 0.32

Chemical Oxygen Demand mg/L 1300 3200 10000 2100 1100 1300 49 260 240 1000 2000 11000 1200 910 53 270 1100 2000 1000 1200 590 23 240 210 240 220 39 220 23 1584.96 11000 270 870 4300 260 250

pH 7.43 7.64 8.25 7.45 7.66 7.71 7.43 7.4 7.55 7.75 7.41 7.53 7.41 7.57 7.43 7.56 7.4 7.63 7.34 7.93 8.02 8.12 7.34 7.62 8.25 7.96 7.86 8.25 7.89 7.82

Specific Conductance umhos/cm 60000 61000 95000 22000 49000 48000 39000 46000 57000 130000 20000 43000 36000 47000 46000 110000 15000 31000 33000 7400 7200 15000 7200 46254.55 130000 12000 15000 12000 6600 7600

Total Dissolved Solids N/A mg/L SW Cleanup Target Levels mg/L 31000 220000 38000 12000 31000 27000 24000 39000 36000 24000 27000 33000 8900 27000 23000 32000 24000 27000 21000 3900 17000 23000 31000 3200 4600 9300 7400 28000 3200 29640.74 220000 6300 7600 7000 4200 5000

Total Suspended Solids mg/L 48 18 35 23 41 26 10 23 - 20 32 10 18 - 53 23 40 10 28.57 53 22 11 84

Turbidity 29 NTU 62-302.530 SW Quality Criteria* NTU 12 3.6 13 94 5.8 3.5 48 3.6 12 11 3.2 7.4 58 6.6 75 25 130 5.8 11 6.6 240 15 21 19 10 27 14 10 3.2 32.08 240 10 34 5.8 7.1 16

Biochemical Oxygen Demand mg/L 7.1 3.5 <2.0 13 3.4 3.4 <2 10 10 5.4 4.6 <2.0 13 4.7 <2 10 31 6.8 <2.0 2.5 36 22 15 8.2 4.2 <2 10 13 2.5 10.80 36 22 24 17 5.5 8.1


Acetone 1700 ug/L SW Cleanup Target Levels ug/L <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25

Acrylonitrile 0.2 ug/L SW Cleanup Target Levels ug/L <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20

Benzene 71.28 ug/L 62-302.530 SW Quality Criteria ug/L <1 <1 <1 <1 <1 <1 <0.38 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.38 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Bromochloromethane N/A ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.52 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.52 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Bromodichloromethane 22 ug/L 62-302.530 SW Quality Criteria ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Bromoform 360 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.71 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.71 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Carbon disulfide 110 ug/L SW Cleanup Target Levels ug/L <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 5.2 <2 <2 <2

Carbon tetrachloride 4.42 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Chlorobenzene 17 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Chloroethane N/A ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.76 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.76 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Chloroform 470.8 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.60 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.60 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Dibromochloromethane 34 ug/L 62-302.530 SW Quality Criteria ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

1,2-Dibromo-3-Chloropropane N/A ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

1,2-Dibromoethane (EDB) 13 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

1,2-Dichlorobenzene 99 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

1,4-Dichlorobenzene 3 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.64 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.64 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

trans-1,4-Dichloro-2-butene No Standard ug/L <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <3 <2 <2 <2 <2 <2 <2 <2 <2 <2

1,1-Dichloroethane N/A ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

1,2-Dichloroethane 37 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

1,1-Dichloroethene 3.2 ug/L 62-302.530 SW Quality Criteria ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

cis-1,2-Dichloroethene N/A ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

trans-1,2-Dichloroethene 11000 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

1,2-Dichloropropane 14 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

cis-1,3-Dichloropropene 12 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

trans-1,3-Dichloropropene 12 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Ethylbenzene 610 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

2-Hexanone NA ug/L SW Cleanup Target Levels ug/L <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

Bromomethane 35 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.98 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.98 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Chloromethane (methyl chloride) 470.8 ug/L 62-302.530 SW Quality Criteria ug/L <1 <1 <1 <1 <1 <1 <0.52 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.52 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Dibromomethane (EDB) 13 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.59 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.59 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Methylene Chloride 1580 ug/L 62-302.530 SW Quality Criteria ug/L <5 <5 <5 <5 <5 <5 <3.0 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <3.0 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5

Methyl Ethyl Ketone 120000 ug/L SW Cleanup Target Levels ug/L <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 13 <10 13.00 13 <10 <10 <10 <10

Iodomethane No Standard ug/L <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5

methyl isobutyl ketone 23000 ug/L SW Cleanup Target Levels ug/L <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

Styrene 460 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <1.0 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1.0 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

1,1,1,2-Tetrachloroethane N/A ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.52 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.52 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

1,1,2,2-Tetrachloroethane 10.8 ug/L 62-302.530 SW Quality Criteria ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Tetrachloroethene (Tetrachloroethylene) 8.85 ug/L 62-302.530 SW Quality Criteria ug/L <1 <1 <1 <1 <1 <1 <0.58 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.58 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Toluene 480 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.70 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.70 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

1,1,1-Trichloroethane 270 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

1,1,2-Trichloroethane 16 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Trichloroethene 80.7 ug/L 62-302.530 SW Quality Criteria ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Trichlorofluoromethane N/A ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.52 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.52 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

1,2,3-Trichloropropane 0.2 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.84 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.84 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Vinyl acetate 700 ug/L SW Cleanup Target Levels ug/L <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2

Vinyl chloride 2.4 ug/L SW Cleanup Target Levels ug/L <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <0.50 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

Xylenes, Total 370 ug/L SW Cleanup Target Levels ug/L <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2

Antimony 4.3 mg/L 62-302.530 SW Quality Criteria mg/L <0.0060 <0.0060 <0.0060 <0.02 <0.02 <0.02 <0.02 <0.010 <0.02 <0.0060 <0.0060 <0.0060 <0.02 <0.02 <0.010 <0.02 <0.0060 <0.0060 <0.02 <0.02 <0.02 <0.01 <0.0060 <0.02 <0.02 <0.010 <0.006 <0.02 <0.02 <0.0060 <0.0060 <0.0060 <0.02 <0.02

Arsenic 0.05 mg/L 62-302.530 SW Quality Criteria mg/L <0.010 <0.010 <0.010 <0.02 <0.02 <0.02 <0.02 <0.0040 <0.010 <0.010 <0.010 <0.020 <0.02 <0.02 <0.0040 <0.010 <0.010 <0.010 <0.02 <0.02 <0.02 <0.004 <0.010 <0.02 <0.02 <0.0040 <0.010 <0.02 <0.02 0.026 0.027 0.015 <0.02 <0.02

Barium N/A mg/L SW Cleanup Target Levels mg/L 0.017 0.014 <0.010 0.016 0.022 0.019 0.024 0.010 0.021 0.018 <0.010 0.018 0.022 0.027 0.020 0.021 0.025 0.025 0.011 0.021 0.029 0.021 1.2 0.044 0.042 0.018 0.011 0.08 1.2 0.061 0.088 0.07 0.049 0.041

Beryllium 0.00013 mg/L 62-302.530 SW Quality Criteria mg/L <0.0030 <0.0030 <0.0030 <0.004 <0.004 <0.004 <0.004 <0.0010 <0.0030 <0.0030 <0.0030 <0.0040 <0.004 <0.004 <0.0010 <0.0030 <0.0030 <0.0030 <0.0040 <0.004 <0.004 <0.001 <0.004 <0.004 <0.0010 <0.004 <0.004 <0.004 <0.0030 <0.0030 <0.0030 <0.004 <0.004

Cadmium 0.0088 mg/L 62-302.530 SW Quality Criteria mg/L <0.0050 <0.0050 <0.005 <0.005 0.0051 <0.005 <0.005 <0.0010 <0.0050 <0.0050 <0.0050 <0.0050 <0.005 <0.005 <0.0010 <0.0050 <0.0050 <0.0050 <0.005 <0.005 <0.005 <0.001 <0.0050 <0.005 <0.005 <0.0010 0.0051 0.01 0.0051 <0.0050 <0.0050 <0.0050 <0.005 <0.005

Chromium (Hexavalent) 0.05 mg/L SW Cleanup Target Levels mg/L <0.010 <0.010 <0.010 <0.01 <0.01 <0.01 <0.01 0.01 <0.010 <0.010 <0.010 <0.010 <0.01 <0.01 0.0069 <0.010 <0.010 <0.010 <0.010 <0.01 <0.01 0.016 3.4 <0.01 <0.01 0.012 <0.01 0.86 3.4 0.018 0.03 0.028 0.018 <0.01

Cobalt N/A mg/L SW Cleanup Target Levels mg/L <0.010 <0.010 <0.010 <0.01 <0.01 <0.01 <0.01 <0.0030 <0.010 <0.010 <0.010 <0.010 <0.01 <0.01 <0.0030 <0.010 <0.010 <0.010 <0.010 <0.01 <0.01 0.0034 <0.010 <0.01 <0.01 <0.0030 <0.01 <0.01 <0.01 <0.010 <0.010 <0.010 <0.01 <0.01

Copper 0.0037 mg/L 62-302.530 SW Quality Criteria mg/L <0.020 <0.020 <0.020 <0.02 <0.02 <0.02 <0.02 <0.0020 <0.020 <0.020 <0.020 <0.020 <0.02 <0.02 <0.0020 <0.020 <0.020 <0.020 <0.020 <0.02 <0.02 0.0063 <0.020 <0.02 <0.02 <0.0020 <0.02 <0.02 <0.02 <0.020 <0.020 <0.020 <0.02 <0.02

Iron 0.3 mg/L 62-302.530 SW Quality Criteria mg/L 0.76 0.11 0.058 0.065 <0.05 <0.05 <0.05 0.13 0.14 <0.050 0.065 <0.05 <0.05 <0.050 0.1 <0.050 0.087 <0.05 <0.05 310 0.17 0.16 <0.05 25.99 310 0.12 0.46 0.37 0.3 0.26

Lead 0.0085 mg/L 62-302.530 SW Quality Criteria mg/L <0.0050 <0.0050 <0.005 <0.01 <0.01 <0.01 <0.01 0.0036 <0.0050 <0.0050 <0.0050 <0.010 <0.01 <0.01 0.0036 <0.0050 <0.0050 <0.0050 <0.010 <0.01 <0.01 0.012 <0.0050 <0.01 <0.01 0.0056 <0.01 <0.01 <0.01 <0.0050 <0.0050 <0.0050 <0.01 <0.01

Magnesium No Standard mg/L 960 1300 1400 640 1100 1200 1100 810 1200 1200 550 970 970 770 1100 840 370 660 860 67000 140 340 140 3885.45 67000 170 250 210 140 160

Nickel 0.0083 mg/L 62-302.530 SW Quality Criteria mg/L <0.040 <0.040 <0.040 <0.04 <0.04 <0.04 <0.04 <0.0030 <0.040 <0.040 <0.040 <0.040 <0.04 <0.04 <0.0030 <0.040 <0.040 <0.040 <0.040 <0.04 <0.04 <0.003 <0.04 <0.04 <0.04 <0.0030 <0.04 <0.04 <0.04 <0.040 <0.040 <0.040 <0.04 <0.04

Selenium 71 mg/L 62-302.530 SW Quality Criteria mg/L <0.010 <0.010 <0.010 <0.02 0.028 0.028 <0.04 <0.0040 <0.010 <0.010 <0.010 <0.020 0.023 <0.04 0.0049 <0.010 <0.010 <0.010 <0.020 <0.02 <0.04 <0.004 <0.01 <0.02 <0.04 0.0059 <0.04 0.02 0.028 <0.010 <0.010 <0.010 <0.02 <0.02

Silver 0.0004 mg/L SW Cleanup Target Levels mg/L <0.010 <0.010 <0.010 <0.01 <0.01 <0.01 <0.01 <0.0020 <0.010 <0.010 <0.010 <0.010 <0.01 <0.01 <0.0020 <0.010 <0.010 <0.010 <0.010 <0.01 <0.01 <0.002 <0.01 <0.01 <0.01 <0.0020 <0.01 <0.01 <0.01 <0.010 <0.010 <0.010 <0.01 <0.01

Thallium 0.0063 mg/L 62-302.530 SW Quality Criteria mg/L <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.0040 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.0040 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.004 <0.025 <0.025 <0.025 <0.0040 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025 <0.025

Vanadium N/A mg/L SW Cleanup Target Levels mg/L <0.010 <0.20 <0.05 <0.01 <0.01 <0.01 <0.01 <0.0030 <0.010 <0.20 <0.050 <0.010 <0.01 <0.01 <0.0030 <0.010 <0.20 <0.050 <0.010 <0.01 <0.01 <0.003 2.1 <0.01 <0.01 <0.0030 <0.01 2.10 2.1 <0.010 <0.010 <0.010 <0.01 <0.01

Zinc 0.086 mg/L SW Cleanup Target Levels mg/L <0.020 <0.020 <0.020 <0.02 <0.02 <0.02 <0.02 <0.0080 <0.020 <0.020 <0.020 0.037 <0.02 <0.02 <0.0080 <0.020 <0.020 <0.020 <0.020 <0.02 <0.02 <0.008 2.9 <0.02 <0.02 <0.0080 <0.02 1.47 2.9 0.02 0.0423 0.027 0.035 <0.02


Mercury 0.000025 mg/L 62-302.530 SW Quality Criteria mg/L <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002 <0.0002

PCBs

PCB-1016 ** ug/L Freshwater Surface Water Criteria ug/L <1 <0.98 <9.4 <0.11 <0.98 <20 <0.96 <19 <0.99 <0.95 <20 <20 <20 <0.98

PCB-1221 ** ug/L Freshwater Surface Water Criteria ug/L <2 <2 <19 <0.088 <2 <41 <1.9 <37 <2 <1.9 <41 <41 <41 <2






Persticides

4,4'-DDD 0.0003 ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.0012 <1 <0.94 <0.047 <1 <1 <1

4,4'-DDE 0.0002 ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.00088 <1 <0.94 <0.047 <1 <1 <1

4,4'-DDT ** ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.0016 <1 <0.94 <0.047 <1 <1 <1

Aldrin ** ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.0012 <1 <0.94 <0.047 <1 <1 <1

alpha-BHC 0.005 ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.0014 <1 <0.94 <0.047 <1 <1 <1

beta-BHC ** ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.0012 <1 <0.94 <0.047 <1 <1 <1

Chlordane (technical) ** ug/L Freshwater Surface Water Criteria ug/L <4.7 <0.0017 <10 <9.4 <0.47 <10 <10 <10

delta-BHC NA ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.00084 <1 <0.94 <0.047 <1 <1 <1

Dieldrin ** ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.0012 <1 <0.94 <0.047 <1 <1 <1

Endosulfan I ** ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.0012 <1 <0.94 <0.047 <1 <1 <1

Endosulfan II ** ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.0030 <1 <0.94 <0.047 <1 <1 <1

Endosulfan sulfate ** ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.00084 <1 <0.94 <0.047 <1 <1 <1

Endrin ** ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.0012 <1 <0.94 <0.047 <1 <1 <1

Endrin aldehyde ** ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.0011 <1 <0.94 <0.047 <1 <1 <1

Endrin ketone ** ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.0015 <1 <0.94 <0.047 <1 <1 <1

gamma-BHC (Lindane) ** ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.010 <1 <0.94 <0.047 <1 <1 <1

Heptachlor ** ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.0012 <1 <0.94 <0.047 <1 <1 <1

Heptachlor epoxide ** ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.0013 <1 <0.94 <0.047 <1 <1 <1

Methoxychlor ** ug/L Freshwater Surface Water Criteria ug/L <0.47 <0.0016 <1 <0.94 <0.047 <1 <1 <1

Toxaphene ** ug/L Freshwater Surface Water Criteria ug/L <47 <0.12 <100 <94 <4.7 <100 <100 <100

Hydrocarbons

Diesel Range Organics [C10-C28] No Standard mg/L 0.049 0.33 0.05 0.53 0.84 0.58 0.046 0.046 0.31 0.84

Gasoline Range Organics (GRO)-C6-C10 No Standard mg/L <0.047 <0.05 <0.047 <0.05 <0.05 <0.05

Other

Boron NA ug/L Freshwater Surface Water Criteria mg/L 5.2 4.9 4.2 4.6 4.1 3.2 3.7 1100 1.9 1.9 125.76 1100 1.4

Cyanide, Total ** ug/L Freshwater Surface Water Criteria mg/L <0.01 <0.01 <0.01 <0.0035 <0.01 <0.01 <0.01 <0.01 <0.0035 <0.01 <0.01 <0.0035 <0.0035 <0.01 <0.01 <0.01 <0.01

** = As provided in Chapter 62-302, F.A.C. Marks a value above the Florida Clean up Standard

Reporting

Unit

SW7

6010B Inductively Coupled Plasma - Atomic Emission Spectrometry- Total Recoverable


Marine Surface Water Criteria

min

SW1

mean max

Florida Clean up Standard DEPARTMENT OF ENVIRONMENTAL HEALTH HISTORIC SURFACE WATER MONITORING DATA 2006-2010

SW2 SW3 SW12

H:\Projects\36082 NOR Cayman\Data\Mon Data\SWplots_2006_2015.xlsx Page 1 of 2

General Chemistry MCL Unit Source

Ammonia N/A mg/L SW Cleanup Target Levels mg/L


Nitrate Nitrite as N N/A mg/L SW Cleanup Target Levels mg/L

Orthophosphate mg/L

Phosphorus mg/L

Chemical Oxygen Demand mg/L

pH


Total Dissolved Solids N/A mg/L SW Cleanup Target Levels mg/L


Turbidity 29 NTU 62-302.530 SW Quality Criteria* NTU

Biochemical Oxygen Demand mg/L


Acetone 1700 ug/L SW Cleanup Target Levels ug/L

Acrylonitrile 0.2 ug/L SW Cleanup Target Levels ug/L

Benzene 71.28 ug/L 62-302.530 SW Quality Criteria ug/L

Bromochloromethane N/A ug/L SW Cleanup Target Levels ug/L

Bromodichloromethane 22 ug/L 62-302.530 SW Quality Criteria ug/L

Bromoform 360 ug/L SW Cleanup Target Levels ug/L

Carbon disulfide 110 ug/L SW Cleanup Target Levels ug/L

Carbon tetrachloride 4.42 ug/L SW Cleanup Target Levels ug/L

Chlorobenzene 17 ug/L SW Cleanup Target Levels ug/L

Chloroethane N/A ug/L SW Cleanup Target Levels ug/L

Chloroform 470.8 ug/L SW Cleanup Target Levels ug/L

Dibromochloromethane 34 ug/L 62-302.530 SW Quality Criteria ug/L

1,2-Dibromo-3-Chloropropane N/A ug/L SW Cleanup Target Levels ug/L

1,2-Dibromoethane (EDB) 13 ug/L SW Cleanup Target Levels ug/L

1,2-Dichlorobenzene 99 ug/L SW Cleanup Target Levels ug/L

1,4-Dichlorobenzene 3 ug/L SW Cleanup Target Levels ug/L


1,1-Dichloroethane N/A ug/L SW Cleanup Target Levels ug/L

1,2-Dichloroethane 37 ug/L SW Cleanup Target Levels ug/L

1,1-Dichloroethene 3.2 ug/L 62-302.530 SW Quality Criteria ug/L

cis-1,2-Dichloroethene N/A ug/L SW Cleanup Target Levels ug/L

trans-1,2-Dichloroethene 11000 ug/L SW Cleanup Target Levels ug/L

1,2-Dichloropropane 14 ug/L SW Cleanup Target Levels ug/L

cis-1,3-Dichloropropene 12 ug/L SW Cleanup Target Levels ug/L

trans-1,3-Dichloropropene 12 ug/L SW Cleanup Target Levels ug/L

Ethylbenzene 610 ug/L SW Cleanup Target Levels ug/L

2-Hexanone NA ug/L SW Cleanup Target Levels ug/L

Bromomethane 35 ug/L SW Cleanup Target Levels ug/L

Chloromethane (methyl chloride) 470.8 ug/L 62-302.530 SW Quality Criteria ug/L

Dibromomethane (EDB) 13 ug/L SW Cleanup Target Levels ug/L

Methylene Chloride 1580 ug/L 62-302.530 SW Quality Criteria ug/L

Methyl Ethyl Ketone 120000 ug/L SW Cleanup Target Levels ug/L


methyl isobutyl ketone 23000 ug/L SW Cleanup Target Levels ug/L

Styrene 460 ug/L SW Cleanup Target Levels ug/L

1,1,1,2-Tetrachloroethane N/A ug/L SW Cleanup Target Levels ug/L

1,1,2,2-Tetrachloroethane 10.8 ug/L 62-302.530 SW Quality Criteria ug/L

Tetrachloroethene (Tetrachloroethylene) 8.85 ug/L 62-302.530 SW Quality Criteria ug/L

Toluene 480 ug/L SW Cleanup Target Levels ug/L

1,1,1-Trichloroethane 270 ug/L SW Cleanup Target Levels ug/L

1,1,2-Trichloroethane 16 ug/L SW Cleanup Target Levels ug/L

Trichloroethene 80.7 ug/L 62-302.530 SW Quality Criteria ug/L

Trichlorofluoromethane N/A ug/L SW Cleanup Target Levels ug/L

1,2,3-Trichloropropane 0.2 ug/L SW Cleanup Target Levels ug/L

Vinyl acetate 700 ug/L SW Cleanup Target Levels ug/L

Vinyl chloride 2.4 ug/L SW Cleanup Target Levels ug/L

Xylenes, Total 370 ug/L SW Cleanup Target Levels ug/L

Antimony 4.3 mg/L 62-302.530 SW Quality Criteria mg/L

Arsenic 0.05 mg/L 62-302.530 SW Quality Criteria mg/L

Barium N/A mg/L SW Cleanup Target Levels mg/L

Beryllium 0.00013 mg/L 62-302.530 SW Quality Criteria mg/L

Cadmium 0.0088 mg/L 62-302.530 SW Quality Criteria mg/L

Chromium (Hexavalent) 0.05 mg/L SW Cleanup Target Levels mg/L

Cobalt N/A mg/L SW Cleanup Target Levels mg/L

Copper 0.0037 mg/L 62-302.530 SW Quality Criteria mg/L

Iron 0.3 mg/L 62-302.530 SW Quality Criteria mg/L

Lead 0.0085 mg/L 62-302.530 SW Quality Criteria mg/L


Nickel 0.0083 mg/L 62-302.530 SW Quality Criteria mg/L

Selenium 71 mg/L 62-302.530 SW Quality Criteria mg/L

Silver 0.0004 mg/L SW Cleanup Target Levels mg/L

Thallium 0.0063 mg/L 62-302.530 SW Quality Criteria mg/L

Vanadium N/A mg/L SW Cleanup Target Levels mg/L

Zinc 0.086 mg/L SW Cleanup Target Levels mg/L


Mercury 0.000025 mg/L 62-302.530 SW Quality Criteria mg/L

PCBs

PCB-1016 ** ug/L Freshwater Surface Water Criteria ug/L







Persticides

4,4'-DDD 0.0003 ug/L Freshwater Surface Water Criteria ug/L

4,4'-DDE 0.0002 ug/L Freshwater Surface Water Criteria ug/L

4,4'-DDT ** ug/L Freshwater Surface Water Criteria ug/L

Aldrin ** ug/L Freshwater Surface Water Criteria ug/L

alpha-BHC 0.005 ug/L Freshwater Surface Water Criteria ug/L

beta-BHC ** ug/L Freshwater Surface Water Criteria ug/L

Chlordane (technical) ** ug/L Freshwater Surface Water Criteria ug/L

delta-BHC NA ug/L Freshwater Surface Water Criteria ug/L

Dieldrin ** ug/L Freshwater Surface Water Criteria ug/L

Endosulfan I ** ug/L Freshwater Surface Water Criteria ug/L

Endosulfan II ** ug/L Freshwater Surface Water Criteria ug/L

Endosulfan sulfate ** ug/L Freshwater Surface Water Criteria ug/L

Endrin ** ug/L Freshwater Surface Water Criteria ug/L

Endrin aldehyde ** ug/L Freshwater Surface Water Criteria ug/L

Endrin ketone ** ug/L Freshwater Surface Water Criteria ug/L

gamma-BHC (Lindane) ** ug/L Freshwater Surface Water Criteria ug/L

Heptachlor ** ug/L Freshwater Surface Water Criteria ug/L

Heptachlor epoxide ** ug/L Freshwater Surface Water Criteria ug/L

Methoxychlor ** ug/L Freshwater Surface Water Criteria ug/L

Toxaphene ** ug/L Freshwater Surface Water Criteria ug/L

Hydrocarbons

Diesel Range Organics [C10-C28] No Standard mg/L

Gasoline Range Organics (GRO)-C6-C10 No Standard mg/L

Other

Boron NA ug/L Freshwater Surface Water Criteria mg/L

Cyanide, Total ** ug/L Freshwater Surface Water Criteria mg/L

** = As provided in Chapter 62-302, F.A.C.

Reporting

Unit



Marine Surface Water Criteria


Drain Drain 1 Drain 2 SWA2 SWA4 SWA6 NS #2 NS #3 NS #4

2013 2010 2011 2011 2007 2008 2006 2006 2008 2015 2015 2015

35 150 150 85 1.5 66.5625 150 12 3 0.94 1.1 0.51 <0.020 0.51 5.313333 12

140 17 59.4 140 17 5.6 5.4 5.5 4.9 1.7 1 0.38 0.38 7.68 17

<0.05 2.9 0.066 <0.05 <0.05 0.8565 2.9 <0.050 <2.5 <0.050 <0.050 <2.5 0.044 0.087 0.059 <2.5 <2.5 <2.5

<0.05 <0.05 0.49 <0.05 <0.05 0.49 0.49 <0.050 <0.050 <0.050 0.052 0.025 <0.015 <0.050 <0.050 <0.050

0.55 0.28 0.524 0.94 0.2 0.2 <0.10 <0.050 0.3 <0.050 0.233333 0.3

580 1100 1400 640 250 1074.44 4300 730 310 230 260 250 200 200 200 200 356 730

7.87 7.75 7.67 7.75 7.67 7.86889 8.25 7.71 8.15 8.08 8.09 7.33 7.33 7.872 8.15

16000 5700 6000 7100 5700 9777.78 16000 16000 14000 13000 13000 3700 3700 11940 16000

10000 3900 4300 4200 3900 5833.33 10000 8400 6300 6900 6900 3400 39000 43000 40000 3400 6380 8400

11 39 84 7 17 <5.0 7 10 20 12 11 <5.0 10.25 17

180 23 61 91 5.8 47.5444 180 18 11 3.7 4.8 13 4.1 2 0.8 0.8 10.1 18

25 <2 33 23 <2 19.7 33 15 8.8 4.2 6.8 12 3 <2.0 <2.0 3 9.36 15

<25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25 <25

<20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 <20 Detection limit does not enable comparison with clean up standard

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<2 <2 <2 <2 <2 5.2 5.2 5.5 <2 <2 <2 5.5 5.5

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 1.3 1.3 1.3 1.3 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 2.3 <1 <1 2.3 2.3 <1 <1 <1 <1 <1 <1

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

<5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5 <5

<10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10 <10

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 Detection limit does not enable comparison with clean up standard

<2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2 <2

<1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1

<2 <2 4.6 <2 <2 4.6 4.6 <2 <2 <2 <2 <2 <2

<0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.0060 <0.0060 <0.0060 <0.0060 <0.0060 <0.0060 <0.0060 <0.0060

0.037 0.087 0.073 0.039 0.015 0.04343 0.087 0.013 <0.010 0.011 0.014 <0.010 <0.010 0.012667 0.014

0.081 0.083 0.079 0.14 0.041 0.07689 0.14 0.69 0.043 0.049 0.049 0.076 0.043 0.1814 0.69

<0.004 <0.004 <0.004 <0.004 <0.004 <0.004 <0.004 <0.0030 <0.0030 <0.0030 <0.0030 <0.0030 <0.0030 <0.0030 <0.0030 Detection limit does not enable comparison with clean up standard

<0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.005 <0.0050 <0.0050 <0.0050 <0.0050 <0.0050 <0.0050 <0.0050 <0.0050

0.037 0.12 0.13 0.059 <0.01 0.055 0.13 <0.010 <0.010 <0.010 <0.010 0.011 <0.010 0.011 0.011

<0.01 0.011 <0.01 <0.01 <0.01 0.011 0.011 <0.010 <0.010 <0.010 <0.010 <0.010 <0.010 <0.010 <0.010

<0.02 0.3 0.12 <0.02 <0.02 0.21 0.3 <0.020 <0.020 <0.020 <0.020 0.026 <0.020 0.026 0.026 Detection limit does not enable comparison with clean up standard

0.093 3.6 2.3 3 0.093 1.167 3.6 0.26 0.22 0.17 0.29 1.4 0.17 0.468 1.4 Iron is ubiquitous in the marine environment

<0.01 0.025 <0.01 <0.01 <0.01 0.025 0.025 <0.0050 <0.0050 <0.0050 <0.0050 <0.0050 <0.0050 <0.0050 <0.0050

330 63 69 110 63 166.889 330 300 230 210 200 99 99 207.8 300

<0.04 0.081 0.076 <0.04 <0.04 0.0785 0.081 <0.040 <0.040 <0.040 <0.040 <0.040 <0.040 <0.040 <0.040 Detection limit does not enable comparison with clean up standard

<0.04 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.010 <0.010 <0.010 <0.010 <0.010 <0.010 <0.010 <0.010



<0.01 0.014 0.014 <0.01 <0.01 0.014 0.014 <0.010 <0.010 <0.010 <0.010 <0.010 <0.010 <0.010 <0.010

<0.02 0.3 0.21 0.12 <0.02 0.10776 0.3 0.031 <0.020 <0.020 0.042 0.044 <0.020 0.039 0.044


<0.98 <1 <0.97 <0.98 <0.98 <0.98

<2 <2 <1.9 <2 <2 <2

<0.98 <1 <0.97 <0.98 <0.98 <0.98

<0.98 <1 <0.97 <0.98 <0.98 <0.98

<0.98 <1 <0.97 <0.98 <0.98 <0.98

<0.98 <1 <0.97 <0.98 <0.98 <0.98

<0.98 <1 <0.97 <0.98 <0.98 <0.98

<0.049 <0.049 <0.049 <0.049

<0.049 <0.049 <0.049 <0.049

<0.049 <0.049 <0.049 <0.049

<0.049 <0.049 <0.049 <0.049

<0.049 <0.049 <0.049 <0.049

<0.049 <0.049 <0.049 <0.049

<0.49 <0.49 <0.49 <0.49

<0.049 <0.049 <0.049 <0.049

<0.049 <0.049 <0.049 <0.049

<0.049 <0.049 <0.049 <0.049

<0.049 <0.049 <0.049 <0.049

<0.049 <0.049 <0.049 <0.049

<0.049 <0.049 <0.049 <0.049

<0.049 <0.049 <0.049 <0.049

<0.049 <0.049 <0.049 <0.049

<0.049 <0.049 <0.049 <0.049

<0.049 <0.049 <0.049 <0.049

<0.049 <0.049 <0.049 <0.049

<0.049 <0.049 <0.049 <0.049

<4.9 <4.9 <4.9 <4.9

0.048 0.048 0.048 0.048

3.5 6.1 4 1.4 3.75 6.1

<0.01 0.017 <0.01 <0.01 <0.01 <0.01 <0.0035 <0.0035 <0.0035 <0.0035

Commentmin mean max min mean max

SWA1

H:\Projects\36082 NOR Cayman\Data\Mon Data\SWplots_2006_2015.xlsx Page 2 of 2


March 2016 36082rr009i3

Appendix C 1 Time Series Plots North Canal Water Quality

\\sal-fs12\shared\Projects\36082 NOR Cayman\Data\Mon Data\SWplots_2006_2015 Page 1 of 7

0

20

40

60

80

100

120

140

160

180

200

220

240

2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

Turbidity

(NTU

)

Year

Turbidity at Grand Cayman Landfill surface water monitoring locations

SW1 SW2 SW3


0

10

20

30

40

50

60

2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

Total Suspe

nded

Solids (m

g/l)

Year

Total Suspended Solids at Grand Cayman Landfill surface water monitoring locations

SW1 SW2 SW3


0

5

10

15

20

25

30

35

40

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

Bioche

mical Oxygen De

mand (m

g/l)

Year

Biochemical Oxygen Demand at Grand Cayman Landfill surface water monitoring locations

SW1 POND near SW1 SW2 SW3 SW12 SW20 SW7


0

2000

4000

6000

8000

10000

12000

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

Chem

ical Oxygen De

mand (m

g/l)

Year

Chemical Oxygen Demand at Grand Cayman Landfill surface water monitoring locations



0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

Mercury (m

g/L)

Year

Mercury concentration at Grand Cayman Landfill surface water monitoring locations


No readings above detection limit


0

10

20

30

40

50

60

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

Ammon

ia (m

g/L)

Year

Ammonia concentration at Grand Cayman Landfill surface water monitoring locations



0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

Phosph

orus (m

g/L)

Year

Phosphorus concentration at Grand Cayman Landfill surface water monitoring locations



March 2016 36082rr009i3

Appendix C 2 Time Series Plots North Sound Water Quality

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

20.00

01/01/2003 01/01/2004 01/01/2005 01/01/2006 01/01/2007 01/01/2008 01/01/2009 01/01/2010 01/01/2011 01/01/2012 01/01/2013

Date

Nitrate‐Nitrite Concentrations at Grand Cayman North Sound monitoring locations

Station 11 Station 13 Station 14

0.00

0.50

1.00

1.50

2.00

2.50

3.00

10/01/2003 10/01/2004 10/01/2005 10/01/2006 10/01/2007 10/01/2008 10/01/2009 10/01/2010 10/01/2011 10/01/2012 10/01/2013Axis Title

Reactive Phosphate Concentrations at Grand Cayman North Sound monitoring locations


0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

10/01/2003 10/01/2004 10/01/2005 10/01/2006 10/01/2007 10/01/2008 10/01/2009 10/01/2010 10/01/2011 10/01/2012 10/01/2013

Axis Title

Chlorophyll Concentrations at Grand Cayman North Sound monitoring locations


0.00

20.00

40.00

60.00

80.00

100.00

120.00

140.00

160.00

10/01/2003 10/01/2004 10/01/2005 10/01/2006 10/01/2007 10/01/2008 10/01/2009 10/01/2010 10/01/2011 10/01/2012 10/01/2013

Suspended Solids Concentrations at Grand Cayman North Sound Monitoring LocationsStation 11 Station 13 Station 14


March 2016 36082rr009i3

Appendix D Screened Soils Data, George Town Landfill

MCL Unit Source MCL Unit Source

Drain 2 MW1 B MW1 MW9B MW 10 MW 11 MW12 MW 17 MW 18

2010 2011 2011 Duplicate 2013 2010 2011 2013 2010 2011 2013 2010 2011 2013 2010 2011 2013 2010 2011 2011 2010 2011 2011 2013 2010 2011 2013 2010 2011 2013 2010 2011 2011 2010 2011 2013 2011 2013 2011 2013 2011 2011

B010B Metals (ICP)

Antimony 370 mg/kg Soil Cleanup Target Levels 54 mg/kg Soil Cleanup Target Levels mg/kg <7.4 <3 <3.2 <2.5 <9.7 <3.2 <2.6 <3.9 <3 <2.3 <6 <9.6 <2.3 <2.1 <2.5 <2 <4.6 <2.3 <3 <2.7 6.5 <2.1 <1.9 <3.9 <2.2 <1.8 <4.6 <2.4 <2.4 <2.4 <2.6 <2.7 <2.3 3.2 2.2 <2 <2 <2.2 <1.9 <2.2 <2.5 <2 4.0 6.5

Arsenic 12 mg/kg Soil Cleanup Target Levels *** mg/kg Soil Cleanup Target Levels mg/kg <7.4 <3 4.4 <5 <9.7 <3.2 <5.1 <3.9 <3 <4.5 13 25 60 <2.1 5.4 <20 9.7 5.1 4.5 3.3 9 38 <19 5.7 4.6 <18 <4.6 3.1 <4.8 <2.4 5.6 8.3 4.8 35 16 13 <20 9.7 <19 3.2 <2.5 <2.1 13.0 60

Barium 130000 mg/kg Soil Cleanup Target Levels 16000 mg/kg Soil Cleanup Target Levels mg/kg <3.7 4.8 6 5.5 9.9 5.9 7.8 5.4 7.9 12 32 22 20 1.2 3.9 <9.9 14 14 13 33 76 7.6 14 20 13 20 16 9.3 9.8 11 11 8.8 20 23 38 2.4 23 22 12 9 4.2 <3.7 15.1 76

Berylium 1400 mg/kg Soil Cleanup Target Levels 630 mg/kg Soil Cleanup Target Levels mg/kg <1.5 <0.59 <0.65 <0.5 <1.9 <0.65 <0.51 <0.78 <0.6 <0.45 <1.2 <1.9 <0.46 <0.42 <0.5 <0.4 <0.91 <0.46 <0.6 <0.54 <0.56 <0.42 <0.38 <0.78 <0.44 <0.37 <0.93 <0.48 <0.48 <0.49 <0.52 <0.54 <0.46 <0.52 <0.42 <0.41 <0.4 <0.44 <0.37 <0.45 <0.51 <0.37 <0.37 <0.37

Cadmium 1700 mg/kg Soil Cleanup Target Levels 75 mg/kg Soil Cleanup Target Levels mg/kg <1.8 <0.74 <0.81 <0.63 <2.4 <0.81 <0.64 <0.97 <0.75 <0.57 <1.5 <2.4 <0.58 <0.52 <0.62 <0.5 <1.1 <0.57 <0.75 1.1 2.2 <0.53 <0.48 <0.97 <0.55 <0.46 <1.2 <0.6 <0.6 <0.61 <0.64 <0.67 <0.57 <0.65 1.4 <0.51 <0.49 <0.55 <0.47 <0.56 <0.64 <0.47 1.6 2.2

Chromium 470 mg/kg Soil Cleanup Target Levels 380 mg/kg Soil Cleanup Target Levels mg/kg 4.3 6.1 10 7.3 23 6.5 13 10 14 19 23 38 53 3.4 18 25 34 24 20 30 33 71 20 19 17 30 19 10 13 12 22 21 19 76 59 6.6 39 27 21 9.1 4.7 3.4 22.7 76 (Hexavalent) No SW exceedences, naturally occuring

Cobalt 42000 mg/kg Soil Cleanup Target Levels *** mg/kg Soil Cleanup Target Levels mg/kg <3.7 <1.5 <1.6 <1.3 <4.9 <1.6 <1.3 <1.9 <1.5 <1.1 <3 <4.8 <1.2 <1 <1.2 <0.99 <2.3 <1.1 <1.5 1.7 3.1 1.4 <0.96 <1.9 <1.1 1.2 <2.3 <1.2 <1.2 <1.2 <1.3 1.4 <1.1 2.9 2.5 <1 1.4 1.7 <0.93 <1.1 <1.3 <1 1.9 3.1

Copper 89000 mg/kg Soil Cleanup Target Levels *** mg/kg Soil Cleanup Target Levels mg/kg <9.2 <3.7 <4 <3.1 <12 <4.1 <3.2 <4.9 <3.7 4.9 33 72 65 <2.6 <3.1 4.5 68 59 12 42 110 27 34 27 11 28 9 14 8.3 9 15 <3.3 30 170 120 4.3 68 40 21 5.5 <3.2 <3.2 39.7 170

Iron * mg/kg Soil Cleanup Target Levels *** mg/kg Soil Cleanup Target Levels mg/kg 660 720 1300 1100 4400 1000 3100 1600 2200 4000 2800 14000 4000 310 2900 4800 7200 5400 3700 12000 44000 16000 5000 11000 4300 5000 3300 1800 2200 2400 5200 3700 6100 18000 18000 4000 8000 9000 3600 2200 310 310 6104.9 44000 Not a health concern for direct exposure

Lead 1400 mg/kg Soil Cleanup Target Levels *** mg/kg Soil Cleanup Target Levels mg/kg <3.7 <1.5 <1.6 1.6 5.9 <1.6 3.5 2.7 3.9 8 35 22 47 <1 2.1 3.6 58 70 13 220 530 25 50 13 5.8 11 8.1 35 21 13 29 2 37 80 180 3.1 120 90 12 11 <1.3 <1.3 50.6 530

Magnesium - - No Standard - - No Standard mg/kg 4200 1900 1900 3800 7600 1600 2600 2900 1800 3300 9600 8500 4900 67000 64000 72000 13000 24000 12000 5200 4200 36000 34000 3100 68000 55000 3700 10000 9500 6100 2000 790 13000 9900 5500 6400 39000 8900 2700 5900 3000 790 15572.9 72000

Nickel 35000 mg/kg Soil Cleanup Target Levels 1300 mg/kg Soil Cleanup Target Levels mg/kg <15 <5.9 <6.5 <5 <19 <6.5 <5.1 <7.8 <6 <4.5 <12 <19 <4.6 <4.2 <5 5.7 <9.1 4.9 <6 8.4 22 19 5.8 <7.8 <4.4 6.2 <9.3 <4.8 <4.8 <4.9 5.4 7 <4.6 15 130 <4.1 8 8.1 <3.7 <4.5 <5.1 <3.7 18.9 130

Selenium 11000 mg/kg Soil Cleanup Target Levels 52 mg/kg Soil Cleanup Target Levels mg/kg <9.2 <3.7 <4 <3.1 <12 <4.1 <3.2 <4.9 <3.7 <2.8 <7.5 <12 <2.9 <2.6 <3.1 <2.5 <5.7 <2.9 <3.7 <3.4 <3.5 <2.6 <2.4 <4.8 <2.7 <2.3 <5.8 <3 <3 <3 <3.2 <3.3 <2.9 <3.3 <2.6 <2.5 <2.5 <2.7 <2.3 <2.8 <3.2 <2.3 <2.3 <2.3

Silver 8200 mg/kg Soil Cleanup Target Levels 170 mg/kg Soil Cleanup Target Levels mg/kg <3.7 <1.5 <1.6 <1.3 <4.9 <1.6 <1.3 <1.9 <1.5 <1.1 <3 <4.8 <1.2 <1 <1.2 <0.99 <2.3 <1.1 <1.5 <1.3 <1.4 <1.1 1.4 <1.9 <1.1 <0.92 <2.3 <1.2 <1.2 <1.2 <1.3 <1.3 <1.1 <1.3 <1 <1 <0.99 <1.1 <0.93 <1.1 <1.3 <1 1.4 1.4

Thalium 150 mg/kg Soil Cleanup Target Levels 28 mg/kg Soil Cleanup Target Levels mg/kg <9.2 <3.7 <4 <3.1 <12 <4.1 <3.2 <4.9 <3.7 <2.8 <7.5 <12 <2.9 <2.6 <3.1 <2.5 <5.7 <2.9 <3.7 <3.4 <3.5 <2.6 <2.4 <4.8 <2.7 <2.3 <5.8 <3 <3 <3 <3.2 <3.3 <2.9 <3.3 <2.6 <2.5 <2.5 <2.7 <2.3 <2.8 <3.2 <2.3 <2.3 <2.3

Vanadium 10000 mg/kg Soil Cleanup Target Levels 9800 mg/kg Soil Cleanup Target Levels mg/kg 6.6 4.7 6.2 7 16 2.4 7 6.9 6.6 9.2 7.3 20 6.1 2.1 13 14 18 13 9.4 12 12 28 10 7 12 16 9.6 5.1 5.7 6.3 10 14 9.8 23 14 7.5 13 18 8.7 5.7 2.2 2.1 10.4 28

Zinc 630000 mg/kg Soil Cleanup Target Levels *** mg/kg Soil Cleanup Target Levels mg/kg <7.4 <3 <3.2 <2.5 32 <3.2 12 9.4 9.5 26 140 980 110 2.9 9.4 21 180 81 38 240 700 53 95 250 41 51 78 9600 2600 1100 61 5 81 660 440 24 390 150 84 51 3.5 <2.5 511.4 9600

7471A Mercury (CVAA)

Mercury 17 mg/kg Soil Cleanup Target Levels 21 mg/kg Soil Cleanup Target Levels mg/kg <0.074 0.08 <0.03 0.041 <0.096 <0.027 0.031 <0.041 <0.03 0.044 <0.057 0.16 0.09 0.035 0.068 0.06 0.18 0.26 0.077 0.22 0.11 0.099 0.051 0.075 0.051 0.054 <0.053 0.035 0.04 <0.024 0.062 0.12 0.098 0.21 0.19 0.024 0.056 0.12 0.05 0.024 <0.025 <0.024 0.1 0.26 MWB to be investigated as part of EI

PCBs

PCB-1016 2.6 mg/kg Soil Cleanup Target Levels 170 mg/kg Soil Cleanup Target Levels ug/kg <51 <55 <46 <44 <44 <54 <40 <52 <39 <170 <33 <42 <50 <45 <38 <67 <37 <34 <44 <40 <42 <43 <43 <170 <36 <33 <39 <67 <38 <42 <34 <34 <34







Pesticides

4,4'-DDD 22 mg/kg Soil Cleanup Target Levels 58 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 <2 <2 <1.7 11 <1.7 <2.1 <8.8 <1.7 <3.4 <1.7 11.0 11

4,4'-DDE 15 mg/kg Soil Cleanup Target Levels 180 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 <2 <2 <1.7 4.1 <1.7 <2.1 <8.8 <1.7 <3.4 <1.7 4.1 4.1

4,4'-DDT 15 mg/kg Soil Cleanup Target Levels 110 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 <2 <2 <1.7 <3.5 <1.7 <2.1 <8.8 <1.7 <3.4 <1.7 <1.7 <1.7

Aldrin 0.3 mg/kg Soil Cleanup Target Levels 2 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 <2 <2 <1.7 <3.5 <1.7 <2.1 <8.8 <1.7 <3.4 <1.7 <1.7 <1.7

alpha-BHC 0.6 mg/kg Soil Cleanup Target Levels 0.003 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 <2 <2 <1.7 <3.5 <1.7 <2.1 <8.8 <1.7 <3.4 <1.7 <1.7 <1.7

beta-BHC 2.4 mg/kg Soil Cleanup Target Levels 0.01 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 <2 <2 <1.7 <3.5 <1.7 <2.1 <8.8 <1.7 <3.4 <1.7 <1.7 <1.7

Chlordane (technical) 14 mg/kg Soil Cleanup Target Levels 96 mg/kg Soil Cleanup Target Levels ug/kg <24 <23 <20 <20 <17 <35 <17 <21 <88 <17 <34 <17 <1.7 <1.7

delta-BHC 490 mg/kg Soil Cleanup Target Levels 2 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 <2 <2 <1.7 <3.5 <1.7 <2.1 <8.8 <1.7 <3.4 <1.7 <1.7 <1.7

Dieldrin 0.3 mg/kg Soil Cleanup Target Levels 0.02 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 <2 <2 <1.7 <3.5 <1.7 <2.1 <8.8 <1.7 <3.4 <1.7 <1.7 <1.7

Endosulfan I 7600 mg/kg Soil Cleanup Target Levels 38 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 <2 <2 <1.7 <3.5 <1.7 <2.1 <8.8 <1.7 <3.4 <1.7 <1.7 <1.7

Endosulfan II 7600 mg/kg Soil Cleanup Target Levels 38 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 <2 <2 <1.7 <3.5 <1.7 <2.1 <8.8 <1.7 <3.4 <1.7 <1.7 <1.7

Endosulfan sulfate 7600 mg/kg Soil Cleanup Target Levels 38 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 <2 <2 <1.7 <3.5 <1.7 <2.1 <8.8 <1.7 <3.4 <1.7 <1.7 <1.7

Endrin 510 mg/kg Soil Cleanup Target Levels 10 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 <2 <2 <1.7 <3.5 <1.7 <2.1 <8.8 <1.7 <3.4 <1.7 <1.7 <1.7

Endrin aldehyde 510 mg/kg Soil Cleanup Target Levels 10 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 3.5 <2 <1.7 <3.5 <1.7 <2.1 <8.8 <1.7 7.8 <1.7 5.7 7.8

Endrin ketone 510 mg/kg Soil Cleanup Target Levels 10 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 <2 <2 <1.7 <3.5 <1.7 <2.1 <8.8 <1.7 <3.4 <1.7 <1.7 <1.7

gamma-BHC (Lindane) 2.5 mg/kg Soil Cleanup Target Levels 0.09 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 <2 <2 <1.7 <3.5 <1.7 <2.1 <8.8 <1.7 <3.4 <1.7 <1.7 <1.7

Heptachlor 1 mg/kg Soil Cleanup Target Levels 230 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 <2 <2 <1.7 <3.5 <1.7 <2.1 <8.8 <1.7 <3.4 <1.7 <1.7 <1.7

Heptachlor epoxide 0.5 mg/kg Soil Cleanup Target Levels 6 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 <2 <2 <1.7 <3.5 <1.7 <2.1 <8.8 <1.7 <3.4 <1.7 <1.7 <1.7

Methoxychlor 8800 mg/kg Soil Cleanup Target Levels 1600 mg/kg Soil Cleanup Target Levels ug/kg <2.4 <2.3 <2 <2 <1.7 <3.5 <1.7 <2.1 <8.8 <1.7 <3.4 <1.7 <1.7 <1.7

Toxaphene 4.5 mg/kg Soil Cleanup Target Levels 310 mg/kg Soil Cleanup Target Levels ug/kg <240 <230 <200 <200 <170 <350 <170 <210 <880 <170 <340 <170 <170 <170

Other

Boron 430000 mg/kg Soil Cleanup Target Levels *** mg/kg Soil Cleanup Target Levels mg/kg 28 28 40 <12 19 28 26 30 29 110 <9.9 18 25 20 13 20 11 13 26 23 20 16 40 26 <10 21 16 25 16 <13 <9.9 26.4 110

Cyanide, Total 11000 mg/kg Soil Cleanup Target Levels 8 mg/kg Soil Cleanup Target Levels mg/kg <0.75 <0.82 <0.69 <0.64 <0.66 <0.79 <0.6 <0.76 <0.57 <2.5 <0.49 <0.63 <0.74 <0.7 <0.58 <0.51 <0.54 <0.52 <0.66 <0.61 <0.63 <0.64 <0.66 <0.53 <0.52 <0.49 <0.59 <0.48 <0.56 <0.62 <0.49 <0.49 <0.49

Sulfate - - No Standard - - No Standard mg/kg 1800 2300 2800 <130 1200 1600 1500 1600 <1200 <520 <100 <130 <150 <140 140 <100 <110 1200 <140 780 <130 440 5300 <1100 <110 <1000 <120 2200 <120 <130 <100 1758.5 5300

Note *** Leachability values may be derived using the SPLP Test to calculate site-specific SCTLs

Comment

MW 15SW1 SW2 SW3 SW7 SW12 Drain 1 MW5 MW8 MW9 MW 13

Statistics

Min Mean Max

Reporting

Unit

MW 14

Direct Exposure - Commercial IndustrialLeachability Based on Ground Water of Low

Yield/Poor Quality

Florida Soil Cleanup Standard

DEPARTMENT OF ENVIRONMENTAL HEALTH HISTORIC SOIL MONITORING DATA 2010 - 2013


March 2016 36082rr009i3

Appendix E Risk Assessment Tables, George Town Landfill

Cayman Islands Government: Landfill Site Environmental Review

Appendix E1: George Town Landfill - Summary of Potential Environmental Risks

Item No. Area/ Building Potential

Pollutant

(Source)

Potential Receptor Potential

Pathway to

Receptor

Associated

Hazard

Potential

Consequence of S-

R Link

Likelihood of

Source-

Receptor

Linkage

Significance: Risk

Classification

Comment

1 Soils around

landfill

Arsenic Site workers/visitors Ingestion Toxic Medium Likely Moderate Concentrations above Florida soils

clean-up levels at some locations

2 Soils around

landfill

Arsenic Adjacent residents Ingestion of wind

blown dust

Toxic Medium Unlikely Low Limited wind blown dust potential. No

arsenic detected in dust samples.

3 Soils around

landfill

Arsenic Adjacent

comercial/industrial

users

Ingestion of wind

blown dust

Toxic Medium Unlikely Low Limited wind blown dust potential. No

arsenic detected in dust samples.

4 Soils around

landfill

Arsenic Groundwater Leaching Groundwater

contamination

Mild Unlikely Negligible The dissolution of arsenic is based on

the chemistry of the water and the

soil. Factors that affect arsenic

mobility include pH, dissolved oxygen

(DO), oxidation-reduction potential ,

specific conductivity, temperature,

and soil conditions (McLean et al.,

1992). Arsenic not detected in

groundwater above Florida clean-up

standard.

5 Waste Oil

storage area

Hydrocarbons Site workers/visitors Dermal

contact/inhalatio

n

Toxic: chronic

toxicity

Medium Low Moderate / Low Assumed site staff wear appropriate

PPE

6 Waste Oil

storage area

Hydrocarbons Groundwater Spills to ground

and overtopping

of bund

Water pollution Mild High Moderate Contamination in MW16

7 Waste Oil

storage area

Hydrocarbons Surface water canal Runoff and

groundwater

base flow

Water pollution Medium High High Potential for groundwater in MW16 to

impact adjacent canal. 0.84mg/l DRO

in surface water at SW12 in 2015.

8 Groundwater Ammonia Surface water canal Groundwater

base flow

Surface water

contamination

Mild High Moderate Ammonia recorded in perimeter

canals, harmful to acquatic

organisms. Ammonia detected above

Florida clean-up standard in MW10

and MW21 in 2015. The observed

ammonia concentrations in the

perimeter canals reflect poor water

quality based on UK guideline values.

9 Groundwater Orthophosphate Surface water canal Groundwater

base flow

Surface water

contamination

Mild High Moderate Elevate orthosphosphate

concentrations recorded in

groundwater and to a lesser extent in

surface waters.

10 Groundwater Iron Surface water canal Groundwater

base flow

Surface water

contamination

Mild Likely Moderate / Low Detected above the clean-up level of

3 mg/l with results ranging up to 11

mg/l

11 Groundwater Ammonia Water supply wells Groundwater

migration

Groundwater

contamination

Medium Unlikely Low Water supply wells located approx 1

mile away to south east, shallow

groundwater gradient anticipated to

the east. Abstraction from >150ft and

water treated for potable supply

H:\Projects\36082 NOR Cayman\Calcs\Ph2 interp risk tables\George Town Contamination Risk Table 09/03/2016




Pollutant

(Source)


Pathway to

Receptor

Associated

Hazard

Potential

Consequence of S-

R Link

Likelihood of

Source-

Receptor

Linkage

Significance: Risk

Classification

Comment

12 Groundwater Ammonia North Sound Groundwater

base flow

Marine water

contamination

Medium Low Moderate / Low Consequence reflects ecological

designation of receptor. Ammonia

detected in North Sound as mouth of

North Canal at 2.5 mg/l in 2015 but

concentration falls with distance into

the North Sound.

13 Surface water

canal

Ammonia North Sound Surface water

flow

Marine water

contamination

Medium High High Ammonia recorded in perimeter








14 Groundwater Ammonia North sound ecology Groundwater

migration

Toxic Medium Low Moderate / Low Consequence reflects ecological

designation of receptor. Ammonia

detected in North Sound as mouth of

North Canal at 2.5 mg/l in 2015 but

concentration falls with distance into

the North Sound.

15 Surface water

canal

Ammonia North sound ecology Surface water

flow

Toxic Medium Likely Moderate Ammonia recorded in perimeter








Ammonia detected in North Sound as

mouth of North Canal at 2.5 mg/l in

2015 but concentration falls with

distance into the North Sound.

16 Surface water

canal

Metals North Sound Surface water

flow

Marine water

contamination

Medium Likely Moderate The sample from SW3 recorded

exceedences of the relevant clean-up

levels for copper and lead.

17 Contaminated

sediments

Hydrogen

sulphide and

trace compounds

Site workers/visitors Inhalation Toxic Medium Likely Moderate WHO guideline values were

exceeded in three locations in the first

2015 survey, which were all either

adjacent to the North Canal or the

landfill boundary with the water

treatment works.

18 Contaminated

sediments

Hydrogen

sulphide and

trace compounds

Adjacent


users

Inhalation Toxic Medium Likely Moderate WHO guideline values were

exceeded in three locations in the first

2015 survey, which were all either

adjacent to the North Canal or the

landfill boundary with the water

treatment works.





Pollutant

(Source)


Pathway to

Receptor

Associated

Hazard

Potential

Consequence of S-

R Link

Likelihood of

Source-

Receptor

Linkage

Significance: Risk

Classification

Comment

19 Landfill Gas Hydrogen

sulphide and

trace compounds

Site Workers/visitors Inhalation Toxic Medium Likely Moderate The highest H2S reading within

landfill, away from the boundaries,

was 80.16 ppb, which is below the

WHO long-term and short-term

average guideline values. However,

trace landfill gas components were

detected at concentrations typical of

landfill gas in gas probes.


sulphide and

trace compounds

Adjacent residents Inhalation Toxic Medium Low Moderate / Low Air quality modelling concludes that

modelling of hydrogen sulphide

emissions showed that short-term

(hourly) average concentrations at the

nearest residential receptors were

likely to exceed the WHO odour

nuisance guideline concentration by a

significant margin. For the remaining

trace organic micro-pollutants, none

of these was forecast to exceed

relevant assessment criteria as a

result of surface emissions from the

landfill site.


sulphide and

trace compounds

Adjacent


users

Inhalation Toxic Medium Low Moderate / Low Air quality modelling concludes that

modelling of hydrogen sulphide

emissions showed that short-term

(hourly) average concentrations at the

nearest residential receptors were

likely to exceed the WHO odour

nuisance guideline concentration by a

significant margin. For the remaining

trace organic micro-pollutants, none

of these was forecast to exceed

relevant assessment criteria as a

result of surface emissions from the

landfill site.

22 Landfill Gas Methane Site Workers/visitors Migration Explosion Severe Low Moderate Assumes site management practices

limit potential for methane explosion

23 Landfill Gas Methane Humans (neighbouring

site users)

Migration Explosion Severe Unlikely Moderate / Low Potential for subsurface migration

limited by high groundwater table and

perimeter canals


Appendix E2: George Town Amenity Risk Table

Data and information Judgement Mitigation Action Receptor Hazard Harm Pathway Probability of

exposure

Consequence Magnitude of risk Justification for magnitude Risk management Residual risk

What is at risk?

What do I wish to

protect?

What is the agent

or process with

potential to

cause harm?

What are the

harmful

consequences if

things go wrong?

How might the

receptor come

into contact with

the source?

How likely is this

contact?

How severe will

the

consequences be

if this occurs?

What is the

overall

magnitude of the

risk?

On what did I base my judgement? How can I best

manage the risk to

reduce the

magnitude?

What is the magnitude of

the risk after

management? (This

residual risk will be

controlled by Compliance

Assessment).

Local human

population

Releases of

particulate matter

(dusts) and micro-

organisms

(bioaerosols).

Harm to human

health - respiratory

irritation and

illness.

Air transport then

inhalation.

Medium Medium Medium Waste types include municipal and food

wastes and have a low to moderate

potential to produce bioaerosols, but the

activities will produce some particulate

matter so a medium magnitude risk is

estimated. There is potential for increased

dust generation during prolonged dry

periods. Residential development is

located inclose proximity downwind of the

site. Dust deposition monitoring revealed

low concentrations of PM10 and below

EC/UK air quality standard.

Covering the wastes

and dust

suppression

Low

Local human

population

As above Nuisance - dust on

cars, clothing etc.

Air transport then

deposition

Low Medium Medium As above. Local residents often sensitive

to dust. Dust deposition monitoring

revealed low concentrations of PM10 and

below EC/UK air quality standard.

As above Low

Local human

population

Odour Nuisance, loss of

amenity

Air transport then

inhalation.

High Medium High The results of the modelling exercise

revealed that detectable ambient

concentrations of odour are likely to be

experienced off-site at the two nearest

residential developments downwind of the

landfill site. In addition, modelling of

hydrogen sulphide emissions showed that

short-term (hourly) average concentrations

at the nearest residential receptors were

likely to exceed the WHO odour nuisance

guideline concentration by a significant

margin. These model predictions accord

well with recent anecdotal reports of odour

annoyance.

Covering/capping of

the wastes and gas

collection/utilisation

Low

Local human

population

Scavenging

animals and

scavenging birds

Harm to human

health - from

waste carried off

site and faeces.

Nuisance and

loss of amenity.

Air transport and

over land

Medium Medium Medium Uncovered municipal wastes likely to attract

scavenging animals and birds and may

become nesting / breeding sites. Some

scavenging birds noted during site visits on

landfill area but relatively small numbers.

Cover to exposed

waste. Pest control

programmes.

Low

Local human

population

Pests (e.g. flies) Harm to human

health, nuisance,

loss of amenity

Air transport and

over land

Medium Medium Medium Permitted waste types likely attract pests. As above Very low

Local human

population and

local environment

Ponds on site

providing potential

mosquito breeding

area

Harm to human

health, nuisance

Flying insects Medium Medium Medium Ponds are an attractive breeding area for

mosquitos

Improvement to site

drainage and

mosquito control by

spraying

Low

Local human

population and

local environment.

Accidental fires

causing the

release of polluting

materials to air

(smoke or fumes),

water or land.

Respiratory

irritation, illness

and nuisance to

local population.

Injury to staff and

fire fighters .

Pollution of water

or land.

Air transport of

smoke. Spillages

and contaminated

firewater by direct

run-off from site

and via surface

water drains and

ditches.

High Medium High Municipal wastes and tyre stockpiles are

combustible, past fires reported.

Covering of wastes

and removal of tyre

stockpiles. Control

of potential ignition

sources (smoking

and hot works)

Low

Ecology in North

canal and North

Sound adjacent to

the landfill

Elevated nutrients,

iron and solids

from combination

of run-off,

subsurface and

groundwater base

flow

Sedimentation and

iron blanketing

aquatic vegetation.

Eutrophication

from nutrients

Direct run-off from

site across ground

surface, via

perimeter canals

and groundwater

base flow.

High Medium High Some evidence of elevated nutrients, iron

and solids in North Canal. Potentially

having local impact on North Sound

ecology through eutrophication and iron

and solids blanketing sea bed vegetation .

There is an existing interception trench on

northern landfill boundary preventing direct

runoff into the canal.

Potential solutions:

-Capping of wastes

to minimising

leaching of nutrients

-Diversion of green

wastes (reduction in

source term)

-Run-off

interception

trenches

-Water treatment

areas (e.g. managed

wetlands)

Low

Local human

population

Contaminated

waters used for

recreational

purposes

Potential harm to

human health

through ingestio of

water with

elevated ammonia

concentrationa

Direct contact or

ingestion

Low Medium Medium Some evidence of elevated ammonia,

nutrients, iron and solids in North Canal.

Ingestion unlikely to occur as no

recreational use of perimeter canals.

As above Very low

Overflying aircraft Scavangin birds

on the landfill

Bird strike to

aircraft

Low High Medium Relatively few birds noted scavanging or

roosting on the landfill

Covering the wastes

Bird scarers

Low

Page 1


March 2016 36082rr009i3

Appendix F Screened Groundwater Data, Cayman Brac Landfill

CB1 CB2 CB3 CB4

General Chemistry MCL Unit Source 2015 2015 2015 2015

Ammonia 28 mg/l GW Cleanup Target Levels mg/L 1.2 18 0.44 0.4 0.4 5.01 18


Nitrate Nitrite as N 110* mg/l 10X Primary Standard mg/L <0.018 <0.018 4.4 0.14 <0.018 2.27 4.4

Orthophosphate mg/L 0.019 0.1 0.048 <0.015 <0.015 0.055667 0.1

Phosphorus mg/L

Chemical Oxygen Demand mg/L 120 120 62 100 62 100.5 120

pH


Total Dissolved Solids 5000 mg/l 10X Second Standard mg/L 7600 5300 6700 20000 5300 9900 20000


Turbidity NTU

Biochemical Oxygen Demand mg/L 4.7 15 <2.0 <2.0 <2 9.85 15

Acetone 63000 ug/L GW Cleanup Target Levels ug/L

Acrylonitrile 420 ug/L GW Cleanup Target Levels ug/L

Benzene 10 ug/L 10X Primary Standard ug/L <0.38 <0.38 <0.38 <0.38 <0.38

Bromochloromethane 910 ug/L GW Cleanup Target Levels ug/L <0.52 <0.52 <0.52 <0.52 <0.52

Bromodichloromethane 6 ug/L GW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50 <0.50

Bromoform 44 ug/L GW Cleanup Target Levels ug/L <0.71 <0.71 <0.71 <0.71 <0.71

Carbon disulfide 7000 ug/L GW Cleanup Target Levels ug/L

Carbon tetrachloride 30 ug/L 10X Primary Standard ug/L <0.50 <0.50 <0.50 <0.50 <0.50

Chlorobenzene 1000 ug/L 10X Primary Standard ug/L <0.50 <0.50 <0.50 <0.50 <0.50

Chloroethane 120 ug/L GW Cleanup Target Levels ug/L <0.76 <0.76 <0.76 <0.76 <0.76

Chloroform 700 ug/L GW Cleanup Target Levels ug/L <0.60 <0.60 <0.60 <0.60 <0.60

Dibromochloromethane 4 ug/L GW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50 <0.50

1,2-Dibromo-3-Chloropropane 2 ug/L 10X Primary Standard ug/L

1,2-Dibromoethane (EDB) 0.2 ug/L 10X Primary Standard ug/L

1,2-Dichlorobenzene 6000 ug/L 10X Primary Standard ug/L <0.50 <0.50 <0.50 <0.50 <0.50

1,4-Dichlorobenzene 750 ug/L 10X Primary Standard ug/L <0.64 1.3 <0.64 1.3 1.3


1,1-Dichloroethane 700 ug/L GW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50 <0.50

1,2-Dichloroethane 30 ug/L 10X Primary Standard ug/L <0.50 <0.50 <0.50 <0.50 <0.50

1,1-Dichloroethene 70 ug/l 10X Primary Standard ug/L <0.50 <0.50 <0.50 <0.50 <0.50

cis-1,2-Dichloroethene 700 ug/l 10X Primary Standard ug/L <0.50 <0.50 <0.50 <0.50 <0.50

trans-1,2-Dichloroethene 1000 ug/l 10X Primary Standard ug/L <0.50 <0.50 <0.50 <0.50 <0.50

1,2-Dichloropropane 50 ug/L 10X Primary Standard ug/L <0.50 <0.50 <0.50 <0.50 <0.50

cis-1,3-Dichloropropene 4 ug/L GW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50 <0.50

trans-1,3-Dichloropropene 4 ug/L GW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50 <0.50

Ethylbenzene 300 ug/L 10X Second Standard ug/L <0.50 <0.50 <0.50 <0.50 <0.50

2-Hexanone 2800 ug/L GW Cleanup Target Levels ug/L

Bromomethane 98 ug/L GW Cleanup Target Levels ug/L <0.98 <0.98 <0.98 <0.98 <0.98

Chloromethane (methyl chloride) 27 ug/L GW Cleanup Target Levels ug/L <0.83 <0.83 <0.83 <0.83 <0.83

Dibromomethane (EDB) 0.2 ug/l 10X Primary Standard ug/L <0.59 <0.59 <0.59 <0.59 <0.59

Methylene Chloride 50 ugL 10X Primary Standard ug/L <3.0 <3.0 <3.0 <3.0 <3.0

Methyl Ethyl Ketone 42000 ug/L GW Cleanup Target Levels ug/L


methyl isobutyl ketone 5600 ug/L GW Cleanup Target Levels ug/L

Styrene 1000 ug/L 10X Primary Standard ug/L <1.0 <1.0 <1.0 <1.0 <1.0

1,1,1,2-Tetrachloroethane 13 ug/L GW Cleanup Target Levels ug/L <0.52 <0.52 <0.52 <0.52 <0.52

1,1,2,2-Tetrachloroethane 2 ug/L GW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50 <0.50

Tetrachloroethene (Tetrachloroethylene) 30 ug/L 10X Primary Standard ug/L <0.58 <0.58 <0.58 <0.58 <0.58

Toluene 400 ug/L 10X Second Standard ug/L <0.70 <0.70 <0.70 <0.70 <0.70

1,1,1-Trichloroethane 2000 ug/L 10X Primary Standard ug/L <0.50 <0.50 <0.50 <0.50 <0.50

1,1,2-Trichloroethane 50 ug/L 10X Primary Standard ug/L <0.50 <0.50 <0.50 <0.50 <0.50

Trichloroethene 30 ug/L 10X Primary Standard ug/L <0.50 <0.50 <0.50 <0.50 <0.50

Trichlorofluoromethane 21000 ug/L GW Cleanup Target Levels ug/L <0.52 <0.52 <0.52 <0.52 <0.52

1,2,3-Trichloropropane 0.2 ug/L GW Cleanup Target Levels ug/L <0.84 <0.84 <0.84 <0.84 <0.84


Vinyl acetate 880 ug/L GW Cleanup Target Levels ug/L

Vinyl chloride 10 ug/l 10X Primary Standard ug/L <0.50 <0.50 <0.50 <0.50 <0.50

Xylenes, Total 200 ug/l 10X Second Standard ug/L

Antimony 0.06 mg/L 10X Primary Standard mg/L <0.010 <0.010 <0.010 <0.010 <0.010

Arsenic 0.1 mg/L 10X Primary Standard mg/L 0.0073 0.01 0.0073 0.00865 0.01

Barium 20 mg/L 10X Primary Standard mg/L 0.022 0.063 0.022 0.0425 0.063

Beryllium 0.04 mg/L 10X Primary Standard mg/L <0.0010 <0.0010 <0.0010 <0.0010 <0.0010

Cadmium 0.05 mg/L 10X Primary Standard mg/L <0.0010 <0.0010 <0.0010 <0.0010 <0.0010

Chromium (Hexavalent) 1 mg/L 10X Primary Standard mg/L 0.057 0.0027 0.0027 0.02985 0.057

Cobalt 1400 ug/L GW Cleanup Target Levels mg/L <0.0030 <0.0030 <0.0030 <0.0030 <0.0030

Copper 10 mg/L 10X Second Standard mg/L <0.0020 0.0042 <0.0020 0.0042 0.0042

Iron 3 mg/L 10X Second Standard mg/L

Lead 0.15 mg/L 10X Primary Standard mg/L 0.0085 0.0084 0.0084 0.00845 0.0085


Nickel 1 mg/L 10X Primary Standard mg/L <0.0030 <0.0030 <0.0030 <0.0030 <0.0030

Selenium 0.5 mg/L 10X Primary Standard mg/L <0.0040 0.0058 <0.0040 0.0058 0.0058

Silver 1 mg/L 10X Second Standard mg/L <0.0020 <0.0020 <0.0020 <0.0020 <0.0020

Thallium 0.02 mg/L 10X Primary Standard mg/L <0.0040 <0.0040 <0.0040 <0.0040 <0.0040

Vanadium 490 ug/L GW Cleanup Target Levels mg/L <0.0030 <0.0030 <0.0030 <0.0030 <0.0030

Zinc 50 mg/L 10X Second Standard mg/L <0.0080 <0.0080 <0.0080 <0.0080 <0.0080

Mercury 0.02 mg/L 10X Primary Standard mg/L

PCBs

PCB-1016 *** ug/l 10X Primary Standard ug/L <0.11 <0.11 <0.11 <0.11 <0.11







Persticides

4,4'-DDD 1 ug/l 10X Primary Standard ug/L <0.0012 <0.0012 <0.0012 <0.0012 <0.0012

4,4'-DDE 1 ug/l 10X Primary Standard ug/L <0.00088 <0.00088 <0.00088 <0.00088 <0.00088

4,4'-DDT 1 ug/l 10X Primary Standard ug/L <0.0016 <0.0016 <0.0016 <0.0016 <0.0016

Aldrin 0.02 ug/l 10X Primary Standard ug/L <0.0012 <0.0012 <0.0012 <0.0012 <0.0012

alpha-BHC 0.06 ug/l 10X Primary Standard ug/L <0.0014 <0.0014 <0.0014 <0.0014 <0.0014

beta-BHC 0.2 ug/l 10X Primary Standard ug/L <0.0012 <0.0012 <0.0012 <0.0012 <0.0012

Chlordane (technical) *** ug/l 10X Primary Standard ug/L <0.0017 <0.0017 <0.0017 <0.0017 <0.0017

delta-BHC 21 ug/l 10X Primary Standard ug/L <0.00084 <0.00084 <0.00084 <0.00084 <0.00084

Dieldrin 0.02 ug/l 10X Primary Standard ug/L <0.0012 <0.0012 <0.0012 <0.0012 <0.0012

Endosulfan I 420 ug/l 10X Primary Standard ug/L <0.0012 <0.0012 <0.0012 <0.0012 <0.0012

Endosulfan II 420 ug/l 10X Primary Standard ug/L <0.0030 <0.0030 <0.0030 <0.0030 <0.0030

Endosulfan sulfate 420 ug/l 10X Primary Standard ug/L <0.00084 <0.00084 <0.00084 <0.00084 <0.00084

Endrin *** ug/l 10X Primary Standard ug/L <0.0012 <0.0012 <0.0012 <0.0012 <0.0012

Endrin aldehyde *** ug/l 10X Primary Standard ug/L <0.0011 <0.0011 <0.0011 <0.0011 <0.0011

Endrin ketone *** ug/l 10X Primary Standard ug/L <0.0015 <0.0015 <0.0015 <0.0015 <0.0015

gamma-BHC (Lindane) *** ug/l 10X Primary Standard ug/L <0.010 <0.010 <0.010 <0.010 <0.010

Heptachlor *** ug/l 10X Primary Standard ug/L <0.0012 <0.0012 <0.0012 <0.0012 <0.0012

Heptachlor epoxide *** ug/l 10X Primary Standard ug/L <0.0013 <0.0013 <0.0013 <0.0013 <0.0013

Methoxychlor *** ug/l 10X Primary Standard ug/L <0.0016 <0.0016 <0.0016 <0.0016 <0.0016

Toxaphene *** ug/l 10X Primary Standard ug/L <0.12 <0.12 <0.12 <0.12 <0.12

Hydrocarbons

Diesel Range Organics [C10-C28] No Standard mg/L 0.83 3.1 0.63 0.12 0.12 1.17 3.1

Gasoline Range Organics (GRO)-C6-C10 No Standard mg/L <0.047 <0.047 <0.047 0.059 <0.047 0.059 0.059

Other

Boron 14000 ug/l 10X Minimum criteria mg/L

Cyanide, Total *** ug/l 10X Primary Standard mg/L <0.0035 <0.0070 <0.0035 <0.0035 <0.0035 <0.0035 <0.0070





Florida Clean up Standard AMEC FOSTER WHEELER SURFACE WATER MONITORING DATA 2015Reporting

Unit min mean maxMarine Surface Water Criteria

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March 2016 36082rr009i3

Appendix G Screened Surface Water Data, Cayman Brac Landfill

BSW1 BSW2 BSW3

General Chemistry MCL Unit Source 2015 2015 2015

Ammonia N/A mg/L SW Cleanup Target Levels mg/L 0.32 <0.020 0.15 0.15 0.235 0.32

Nitrogen, Kjeldahl mg/L 8.5 7.8 4.9 4.9 7.066667 8.5

Nitrate Nitrite as N N/A mg/L SW Cleanup Target Levels mg/L <0.018 <0.018 <0.018 <0.018 <0.018 <0.018

Orthophosphate mg/L <0.015 0.017 <0.015 <0.015 0.017 0.017

Phosphorus mg/L

Chemical Oxygen Demand mg/L 540 450 520 450 503.3333 540

pH



Total Suspended Solids mg/L 120 100 800 100 340 800

Turbidity 29 NTU 62-302.530 SW Quality Criteria* NTU 2.6 6.8 8.9 2.6 6.1 8.9

Biochemical Oxygen Demand mg/L 9.4 5.2 21 5.2 11.9 21


Acetone 1700 ug/L SW Cleanup Target Levels ug/L

Acrylonitrile 0.2 ug/L SW Cleanup Target Levels ug/L

Benzene 71.28 ug/L 62-302.530 SW Quality Criteria ug/L <0.38 <0.38 <0.38 <0.38

Bromochloromethane N/A ug/L SW Cleanup Target Levels ug/L <0.52 <0.52 <0.52 <0.52

Bromodichloromethane 22 ug/L 62-302.530 SW Quality Criteria ug/L <0.50 <0.50 <0.50 <0.50

Bromoform 360 ug/L SW Cleanup Target Levels ug/L <0.71 <0.71 <0.71 <0.71

Carbon disulfide 110 ug/L SW Cleanup Target Levels ug/L

Carbon tetrachloride 4.42 ug/L SW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50

Chlorobenzene 17 ug/L SW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50

Chloroethane N/A ug/L SW Cleanup Target Levels ug/L <0.76 <0.76 <0.76 <0.76

Chloroform 470.8 ug/L SW Cleanup Target Levels ug/L <0.60 <0.60 <0.60 <0.60

Dibromochloromethane 34 ug/L 62-302.530 SW Quality Criteria ug/L <0.50 <0.50 <0.50 <0.50

1,2-Dibromo-3-Chloropropane N/A ug/L SW Cleanup Target Levels ug/L

1,2-Dibromoethane (EDB) 13 ug/L SW Cleanup Target Levels ug/L

1,2-Dichlorobenzene 99 ug/L SW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50

1,4-Dichlorobenzene 3 ug/L SW Cleanup Target Levels ug/L <0.64 <0.64 <0.64 <0.64


1,1-Dichloroethane N/A ug/L SW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50

1,2-Dichloroethane 37 ug/L SW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50

1,1-Dichloroethene 3.2 ug/L 62-302.530 SW Quality Criteria ug/L <0.50 <0.50 <0.50 <0.50

cis-1,2-Dichloroethene N/A ug/L SW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50

trans-1,2-Dichloroethene 11000 ug/L SW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50

1,2-Dichloropropane 14 ug/L SW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50

cis-1,3-Dichloropropene 12 ug/L SW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50

trans-1,3-Dichloropropene 12 ug/L SW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50

Ethylbenzene 610 ug/L SW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50

2-Hexanone NA ug/L SW Cleanup Target Levels ug/L

Bromomethane 35 ug/L SW Cleanup Target Levels ug/L <0.98 <0.98 <0.98 <0.98

Chloromethane (methyl chloride) 470.8 ug/L 62-302.530 SW Quality Criteria ug/L <0.83 <0.83 <0.83 <0.83

Dibromomethane (EDB) 13 ug/L SW Cleanup Target Levels ug/L <0.59 <0.59 <0.59 <0.59

Methylene Chloride 1580 ug/L 62-302.530 SW Quality Criteria ug/L <3.0 <3.0 <3.0 <3.0

Methyl Ethyl Ketone 120000 ug/L SW Cleanup Target Levels ug/L


methyl isobutyl ketone 23000 ug/L SW Cleanup Target Levels ug/L

Styrene 460 ug/L SW Cleanup Target Levels ug/L <1.0 <1.0 <1.0 <1.0

1,1,1,2-Tetrachloroethane N/A ug/L SW Cleanup Target Levels ug/L <0.52 <0.52 <0.52 <0.52

1,1,2,2-Tetrachloroethane 10.8 ug/L 62-302.530 SW Quality Criteria ug/L <0.50 <0.50 <0.50 <0.50

Tetrachloroethene (Tetrachloroethylene) 8.85 ug/L 62-302.530 SW Quality Criteria ug/L <0.58 <0.58 <0.58 <0.58

Toluene 480 ug/L SW Cleanup Target Levels ug/L <0.70 <0.70 <0.70 <0.70

1,1,1-Trichloroethane 270 ug/L SW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50

1,1,2-Trichloroethane 16 ug/L SW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50

Trichloroethene 80.7 ug/L 62-302.530 SW Quality Criteria ug/L <0.50 <0.50 <0.50 <0.50

Trichlorofluoromethane N/A ug/L SW Cleanup Target Levels ug/L <0.52 <0.52 <0.52 <0.52

1,2,3-Trichloropropane 0.2 ug/L SW Cleanup Target Levels ug/L <0.84 <0.84 <0.84 <0.84


Vinyl acetate 700 ug/L SW Cleanup Target Levels ug/L

Vinyl chloride 2.4 ug/L SW Cleanup Target Levels ug/L <0.50 <0.50 <0.50 <0.50

Xylenes, Total 370 ug/L SW Cleanup Target Levels ug/L


Antimony 4.3 mg/L 62-302.530 SW Quality Criteria mg/L 0.01 <0.010 <0.010 0.01 0.01

Arsenic 0.05 mg/L 62-302.530 SW Quality Criteria mg/L 0.011 0.0061 0.0061 0.00855 0.011

Barium N/A mg/L SW Cleanup Target Levels mg/L 0.025 0.065 0.025 0.045 0.065

Beryllium 0.00013 mg/L 62-302.530 SW Quality Criteria mg/L <0.0010 <0.0010 <0.0010 <0.0010 <0.0010

Cadmium 0.0088 mg/L 62-302.530 SW Quality Criteria mg/L <0.0010 <0.0010 <0.0010 <0.0010 <0.0010

Chromium (Hexavalent) 0.05 mg/L SW Cleanup Target Levels mg/L 0.013 0.019 0.013 0.016 0.019

Cobalt N/A mg/L SW Cleanup Target Levels mg/L <0.015 <0.015 <0.0030 <0.0030 <0.0030

Copper 0.0037 mg/L 62-302.530 SW Quality Criteria mg/L 0.0065 0.005 0.005 0.00575 0.0065


Lead 0.0085 mg/L 62-302.530 SW Quality Criteria mg/L 0.048 0.038 0.038 0.043 0.048


Nickel 0.0083 mg/L 62-302.530 SW Quality Criteria mg/L <0.015 <0.015 <0.0030 <0.0030 <0.0030

Selenium 71 mg/L 62-302.530 SW Quality Criteria mg/L 0.0078 0.012 0.0078 0.0099 0.012

Silver 0.0004 mg/L SW Cleanup Target Levels mg/L <0.0020 <0.0020 <0.0020 <0.0020 <0.0020

Thallium 0.0063 mg/L 62-302.530 SW Quality Criteria mg/L <0.020 <0.020 <0.0040 <0.0040 <0.0040

Vanadium N/A mg/L SW Cleanup Target Levels mg/L <0.0030 <0.0030 <0.0030 <0.0030 <0.0030

Zinc 0.086 mg/L SW Cleanup Target Levels mg/L <0.0080 <0.0080 <0.0080 <0.0080 <0.0080


Mercury 0.000025 mg/L 62-302.530 SW Quality Criteria mg/L <0.070 <0.070 <0.070 <0.070 <0.070

PCBs

PCB-1016 ** ug/L Freshwater Surface Water Criteria ug/L <0.11 <0.11 <0.11 <0.11 <0.11







Persticides

4,4'-DDD 0.0003 ug/L Freshwater Surface Water Criteria ug/L <0.0012 <0.0012 <0.0012 <0.0012 <0.0012

4,4'-DDE 0.0002 ug/L Freshwater Surface Water Criteria ug/L <0.00088 <0.00088 <0.00088 <0.00088 <0.00088

4,4'-DDT ** ug/L Freshwater Surface Water Criteria ug/L <0.0016 <0.0016 <0.0016 <0.0016 <0.0016

Aldrin ** ug/L Freshwater Surface Water Criteria ug/L <0.0012 <0.0012 <0.0012 <0.0012 <0.0012

alpha-BHC 0.005 ug/L Freshwater Surface Water Criteria ug/L <0.0014 <0.0014 <0.0014 <0.0014 <0.0014

beta-BHC ** ug/L Freshwater Surface Water Criteria ug/L <0.0012 <0.0012 <0.0012 <0.0012 <0.0012

Chlordane (technical) ** ug/L Freshwater Surface Water Criteria ug/L <0.0017 <0.0017 <0.0017 <0.0017 <0.0017

delta-BHC NA ug/L Freshwater Surface Water Criteria ug/L <0.00084 <0.00084 <0.00084 <0.00084 <0.00084

Dieldrin ** ug/L Freshwater Surface Water Criteria ug/L <0.0012 <0.0012 <0.0012 <0.0012 <0.0012

Endosulfan I ** ug/L Freshwater Surface Water Criteria ug/L <0.0012 <0.0012 <0.0012 <0.0012 <0.0012

Endosulfan II ** ug/L Freshwater Surface Water Criteria ug/L <0.0030 <0.0030 <0.0030 <0.0030 <0.0030

Endosulfan sulfate ** ug/L Freshwater Surface Water Criteria ug/L <0.00084 <0.00084 <0.00084 <0.00084 <0.00084

Endrin ** ug/L Freshwater Surface Water Criteria ug/L <0.0012 <0.0012 <0.0012 <0.0012 <0.0012

Endrin aldehyde ** ug/L Freshwater Surface Water Criteria ug/L <0.0011 <0.0011 <0.0011 <0.0011 <0.0011

Endrin ketone ** ug/L Freshwater Surface Water Criteria ug/L <0.0015 <0.0015 <0.0015 <0.0015 <0.0015

gamma-BHC (Lindane) ** ug/L Freshwater Surface Water Criteria ug/L <0.010 <0.010 <0.010 <0.010 <0.010

Heptachlor ** ug/L Freshwater Surface Water Criteria ug/L <0.0012 <0.0012 <0.0012 <0.0012 <0.0012

Heptachlor epoxide ** ug/L Freshwater Surface Water Criteria ug/L <0.0013 <0.0013 <0.0013 <0.0013 <0.0013

Methoxychlor ** ug/L Freshwater Surface Water Criteria ug/L <0.0016 <0.0016 <0.0016 <0.0016 <0.0016

Toxaphene ** ug/L Freshwater Surface Water Criteria ug/L <0.12 <0.12 <0.12 <0.12 <0.12

Hydrocarbons

Diesel Range Organics [C10-C28] No Standard mg/L 0.62 2.4 0.62 1.51 2.4

Gasoline Range Organics (GRO)-C6-C10 No Standard mg/L <0.047 <0.047 <0.047 <0.047 <0.047

Other

Boron NA ug/L Freshwater Surface Water Criteria mg/L

Cyanide, Total ** ug/L Freshwater Surface Water Criteria mg/L <0.0035 <0.0035 <0.0035 <0.0035 <0.0070


Florida Clean up Standard AMEC FOSTER WHEELER SURFACE WATER MONITORING DATA 2015Reporting

Unit min mean maxMarine Surface Water Criteria

H:\Projects\36082 NOR Cayman\Data\Mon Data\Cayman_Brac_SWplots_2015.xlsx Page 1 of 1


March 2016 36082rr009i3

Appendix H Risk Assessment Tables, Cayman Brac Landfill


Appendix H1: Cayman Brac Landfill - Summary of Potential Environmental Risks


Pollutant

(Source)

Potential

Receptor

Potential

Pathway to

Receptor

Associated

Hazard

Potential

Consequence of

S-R Link

Likelihood of

Source-

Receptor

Linkage

Significance: Risk

Classification

Comment

1 Municipal

wastes

Ammonia Groundwater Leaching Groundwater

contamination

Water pollution

Mild Likely Moderate / Low Groundwater is tidally influenced so

ammonia can be released into

marine environment. Ammonia

detected in 2015 groundwater

samples (up to 18 mg/l) but not

above Florida clean-up standard.

2 Municipal

wastes

Metals Shrimp pond Leaching Water pollution Medium Likely Moderate Copper and lead above clean-up

levels in surface water samples.

3 Waste oil

storage spills to

ground

Hydrocarbons Site

workers/visitors

Dermal Contact

Ingestion

Toxic Mild Low Low Assumed site staff wear appropriate

PPE

4 Waste oil

storage spills to

ground

Hydrocarbons Groundwater Migration Groundwater

contamination

Mild High Moderate Some surface spills noted. DRO

detected in surface water samples

from groundwater samples CB1-CB4

in April 2015. GRO detected in

groundwater sample CB4.

5 Landfill gas Hydrogen

sulphide and

trace

compounds

Site

workers/visitors

Inhalation Toxic Medium Low Moderate / Low H2S not detected at the landfill

surface during 2015 survey.

However, trace landfill gas

components were detected at

concentrations typical of landfill gas

in gas probes.

6 Landfill gas Hydrogen

sulphide and

trace

compounds

Adjacent residents Inhalation Toxic Medium Unlikely Low Unlikely due to dispersion

7 Landfill gas Methane Site

workers/visitors

Migration Explosion Severe Low Moderate Site not capped so surface migration

potential limited

8 Landfill gas Methane Adjacent residents Migration Explosion Severe Unlikely Moderate / Low Potential subsurface migration

limited due to shallow groundwater

table

H:\Projects\36082 NOR Cayman\Calcs\Ph2 interp risk tables\Cayman Brac Contamination Risk Table.xls 31/07/2015

Appendix H2: Cayman Brac Amenity Risk Table.xlsx

Data and information Judgement Mitigation Action Receptor Hazard Harm Pathway Probability of

exposure

Consequence Magnitude

of risk

Justification for

magnitude

Risk management Residual risk

What is at risk?

What do I wish

to protect?

What is the

agent or process

with potential to

cause harm?

What are the

harmful

consequences if

things go

wrong?

How might the

receptor come

into contact with

the source?

How likely is

this contact?

How severe will

the

consequences

be if this

occurs?

What is the

overall

magnitude

of the risk?

On what did I base my

judgement?

How can I best

manage the risk to

reduce the

magnitude?

What is the

magnitude of the

risk after

management?

(This residual

risk will be

controlled by

Compliance

Assessment).

Local human

population

Releases of

particulate matter

(dusts) and micro-

organisms

(bioaerosols).

Harm to human

health -

respiratory

irritation and

illness.

Air transport then

inhalation.

Low Medium Medium Waste types include

municipal and food wastes

and have a low to moderate

potential to produce

bioaerosols, but the

activities will produce some

particulate matter. There is

potential for increased dust

generation during

prolonged dry periods.

Residential development is

located in close proximity

but not directly downwind of

the site so probability is low.

Recent dust deposition

monitoring showed very

low/zero average

concentrations of PM10.

Covering the wastes

and dust suppression

Low

Local human

population

As above Nuisance - dust

on cars, clothing

etc.

Air transport then

deposition

Low Medium Medium As above. Local residents

often sensitive to dust.


monitoring showed very

low/zero average

concentrations of PM10.

As above Low

Local human

population

Odour Nuisance, loss of

amenity

Air transport then

inhalation.

Medium Medium Medium Local residents often

sensitive to odour, no

significant odour issues

noted at site boundary

during site visits

Covering/capping of

the wastes and gas

collection/utilisation

Low

Local human

population

Scavenging

animals and

scavenging birds

Harm to human

health - from

waste carried off

site and faeces.

Nuisance and

loss of amenity.

Air transport and

over land

Low Low Low Uncovered municipal

wastes likely to attract

scavenging animals and

birds and may become

nesting / breeding sites. No

birds noted during site visits

Cover to exposed

waste. Pest control

programmes.

Low

Local human

population


health, nuisance,

loss of amenity

Air transport and

over land

Low Medium Medium Permitted waste types likely

attract pests.

As above Very low

Local human

population and

local environment.

Accidental fires

causing the

release of

polluting materials

to air (smoke or

fumes), water or

land.

Respiratory

irritation, illness

and nuisance to

local population.

Injury to staff and

fire fighters .

Pollution of water

or land.

Air transport of

smoke. Spillages

and contaminated

firewater by direct

run-off from site

and via surface

water drains and

ditches.

Medium Medium Medium Municipal wastes and tyre

stockpiles are combustible,

past fires reported.

Adjacent residential

development is not directly

downwind of the site. Tyre

stockpile is being removed.

Covering of wastes

and removal of tyre

stockpiles. Control of

potential ignition

sources (smoking and

hot works)

Low

Shrimp Pond Elevated

nutrients, iron and

solids from

combination of run-

off and

groundwater base

flow

Sedimentation

and iron

blanketing aquatic

vegetation, algal

development with

increased

nutrients

Direct run-off from

site across ground

surface and

groundwater base

flow.

Medium Medium Medium No visual evidence of

significant impact noted

during site visits. Analytical

data does not show

evidence of significant

impact to surface water

quality with regard to

elevated nutrients, etc.


-Capping of wastes to

minimising leaching of

nutrients

-Diversion of green


source term)

-Run-off interception

trenches

-Water treatment

areas (e.g. managed

wetlands)

Low

Site users and

visitors

Disposal in

uncovered pit

within the landfill

(clinical waste

incinerator not in

operation)

Biohazard Air transport then

inhalation, direct

contact

Medium Medium Medium Open pit on site with

evidence of clinincal waste

disposal.

Repair incinerator and

burn clinincal waste.

Ensure clinical waste

disposed in pit is

covered daily.

Low

Marine Water Elevated

nutrients, iron and

solids from

combination of run-

off and

groundwater base

flow

Algal

development with

increased

nutrients

Direct run-off from

site across ground

surface and

groundwater base

flow.

Low Medium Medium Probability assessed as low

due to receptor distance

from the landfill and the

effects of dilution. Analytical

data does not show

evidence of significant

impact to groundwater

quality with regard to

elevated nutrients, etc.




nutrients

-Diversion of green


source term)


trenches

-Water treatment

areas (e.g. managed

wetlands)

Low

Page 1


March 2016 36082rr009i3

Appendix I Screened Surface Water Data, Little Cayman Landfill

LSW2 LSW3

General Chemistry MCL Unit Source 2015 2015

Ammonia N/A mg/L SW Cleanup Target Levels mg/L 0.31 <0.020

Nitrogen, Kjeldahl mg/L 12 5.3

Nitrate Nitrite as N N/A mg/L SW Cleanup Target Levels mg/L

Orthophosphate mg/L 0.028 0.04

Phosphorus mg/L

Chemical Oxygen Demand mg/L 730 960

pH



Total Suspended Solids mg/L 37000 43000

Turbidity 29 NTU 62-302.530 SW Quality Criteria* NTUBiochemical Oxygen Demand mg/L 57 8.8


Antimony 4.3 mg/L 62-302.530 SW Quality Criteria mg/L <0.010

Arsenic 0.05 mg/L 62-302.530 SW Quality Criteria mg/L 0.0097

Barium N/A mg/L SW Cleanup Target Levels mg/L 0.092

Beryllium 0.00013 mg/L 62-302.530 SW Quality Criteria mg/L <0.0010

Cadmium 0.0088 mg/L 62-302.530 SW Quality Criteria mg/L <0.0010

Chromium (Hexavalent) 0.05 mg/L SW Cleanup Target Levels mg/L 0.012

Cobalt N/A mg/L SW Cleanup Target Levels mg/L <0.015

Copper 0.0037 mg/L 62-302.530 SW Quality Criteria mg/L 0.014


Lead 0.0085 mg/L 62-302.530 SW Quality Criteria mg/L 0.056


Nickel 0.0083 mg/L 62-302.530 SW Quality Criteria mg/L <0.015

Selenium 71 mg/L 62-302.530 SW Quality Criteria mg/L 0.0059

Silver 0.0004 mg/L SW Cleanup Target Levels mg/L <0.0020

Thallium 0.0063 mg/L 62-302.530 SW Quality Criteria mg/L <0.020

Vanadium N/A mg/L SW Cleanup Target Levels mg/L <0.0030Zinc 0.086 mg/L SW Cleanup Target Levels mg/L <0.0080

Hydrocarbons

Diesel Range Organics [C10-C28] No Standard mg/L 1.9 2.5Gasoline Range Organics (GRO)-C6-C10 No Standard mg/L 0.059

Other

Boron NA ug/L Freshwater Surface Water Criteria mg/LCyanide, Total ** ug/L Freshwater Surface Water Criteria mg/L <0.0035


Florida Clean up Standard 2015Reporting

Unit Marine Surface Water Criteria

H:\Projects\36082 NOR Cayman\Data\Mon Data\Little_Cayman_SWplots_2015.xlsx Page 1 of 1


March 2016 36082rr009i3

Appendix J Risk Assessment Tables, Little Cayman Landfill


Appendix J1: Little Cayman Landfill - Summary of Potential Environmental Risks


Pollutant

(Source)

Potential

Receptor

Potential

Pathway to

Receptor

Associated

Hazard

Potential

Consequence of

S-R Link

Likelihood of

Source-

Receptor

Linkage

Significance: Risk

Classification

Comment

1 Waste oil

storage

Hydrocarbons Site workers and

visitors

Dermal Contact

Inhalation

Toxic Mild Low Low Some surface spills noted. Illegal

waste oil disposal pit at the site, near

the plant storage building. Likelihood

assumes site staff have appropriate

PPE.

2 Waste oil

storage

Hydrocarbons Groundwater Migration Groundwater

contamination

Medium Likely Moderate Some surface spills noted. Illegal

waste oil disposal pit at the site, near

the plant storage building.

3 Burning ground Ammonia Groundwater Leaching Groundwater

contamination

Mild Low Low No quantitative data on ammonia in

groundwater.

4 Burning ground Metals Groundwater Leaching Groundwater

contamination

Mild Likely Moderate / Low Metals detected above relevant

Florida surface water clean-up target

level or marine surface water criteria

is soil samples submitted for

leaching test analysis.

5 Burning ground Metals Site workers and

visitors

Dermal Contact

Ingestion

Toxic Mild Likely Moderate / Low Arsenic detected above Florida

clean-up target in soils.

6 Burning ground Combustion

products from

burning

Site workers and

visitors

Inhalation Toxic Mild Likely Moderate / Low Regular uncontrolled burning of

waste.

7 Groundwater Metals Offsite ponds Groundwater

baseflow

Water pollution Medium Low Moderate / Low Copper and lead detected above

Florida clean-up target in surface

water samples. Likelihood reflects

dilution between source and

receptor.

H:\Projects\36082 NOR Cayman\Docs\Reports\rr009i1 Appendices\Ph2 interp risk tables\Little Cayman Contamination Risk Table.xls 20/07/2015

Appendix J2: Little Cayman Amenity Risk Table.xlsx

Data and information Judgement Mitigation Action Receptor Hazard Harm Pathway Probability

of exposure

Consequence Magnitude

of risk

Justification for

magnitude

Risk management Residual risk

What is at risk?

What do I wish

to protect?

What is the

agent or process

with potential to

cause harm?

What are the

harmful

consequences if

things go

wrong?

How might the

receptor come

into contact with

the source?

How likely is

this contact?

How severe will

the

consequences

be if this

occurs?

What is the

overall

magnitude

of the risk?

On what did I base my

judgement?

How can I best

manage the risk to

reduce the

magnitude?

What is the

magnitude of the

risk after

management?

(This residual

risk will be

controlled by

Compliance

Assessment).

Local human

population

Releases of

particulate matter

(dusts) and micro-

organisms

(bioaerosols).

Harm to human

health -

respiratory

irritation and

illness.

Air transport then

inhalation.

Very Low Medium Low Waste is burned so has low

potential to produce

bioaerosols, but the burning

activities will produce some

particulate matter. There is

potential for increased dust

generation during

prolonged dry periods.

Residential development is

remote from the site.


monitoring showed zero

average concentrations of

PM10.

Covering the wastes


Low

Local human

population

As above Nuisance - dust

on cars, clothing

etc.

Air transport then

deposition

Very Low Medium Low As above. Local residents

often sensitive to dust.


monitoring showed zero

average concentrations of

PM10.

Covering the wastes


Low

Local human

population

Scavenging

animals and

scavenging birds

Harm to human

health - from

waste carried off

site and faeces.

Nuisance and

loss of amenity.

Air transport and

over land

Low Low Low Uncovered municipal

wastes likely to attract

scavenging animals and

birds but wastes are

routinely burned. Few birds

noted during site visits.

Covering/capping of

the wastes

Low

Local human

population


health, nuisance,

loss of amenity

Air transport and

over land

Medium Medium Medium Unburned municipal waste

will attract pests but

volumes are relatively small.

As above Very low

Local human

population and

local environment.

Waste burning

causing the

release of

polluting materials

to air (smoke or

fumes), water or

land.

Respiratory

irritation, illness

and nuisance to

local population.

Pollution of water

or land.

Air transport of

smoke and

combustion

products

Low Medium Medium Wastes are routinely burned

but there is no adjacent

residential development.

PAHs not detected above

relevant standards in soil or

leaching tests.

Burning in a controlled

environment (e.g.

incinerator)

Low

Offsite pools Elevated

nutrients, iron and

solids from

combination of run-

off and

groundwater base

flow

Poor water quality

and algal

development with

increased

nutrients

Direct run-off from

site across ground

surface and

groundwater base

flow.

Very Low Medium Low Ponds are remote from

active areas of the site.

Results of recent surface

water quality sampling

showed no significant

impact to surface waters

from nutrients.




nutrients

-Diversion of green


source term)


trenches

Very low

Booby Pond Waste burning

causing the

release of

polluting materials

to air (smoke or

fumes), water or

land.

Impact on

RAMSAR site

Air transport of

smoke and

combustion

products

Low Medium Medium Wastes are routinely burned

but Booby pond is in excess

of 0.5 miles from the site,

although downwind, with

potential for dispersion.

PAHs not detected above

relevant standards in soil or

leaching tests from site.

Burning in a controlled

environment (e.g.

incinerator)

Low

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March 2016 36082rr009i3

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