aoc sediment update_part 1

Contaminated Sediment

Management

Roger Santiago – Environment Canada

2012 RAP Implementation Workshop Getting the Job Done !

Priority Sediment Remediation Sites

Contaminated Site Overview •  Thunder Bay N. Harbour – Hg, Organic material – 350,000 m3 •  Peninsula Harbour – Hg, PCBs – 256,000 m2 •  St. Marys River – PAHs – 50,000 m3 (app.) •  St. Clair River – Hg – 61,000 m3 •  Hamilton Harbour – PAHs, metals – 675,000 m3 •  Niagara River – PCBs – 20,000 m3 (MoNR)

Conceptual Implementation Schedule and Estimated Costs (in $1000)

Implementation estimate based on sediment risk assessment

Implementation estimate based on SMO

Implementation estimate based on Engineering Design

AOCs 2012/13 2013/14 2014/15 2015/16 2016/17 2017/18 2018/19 Total

TB $21,600 $21,600 $21,600 $65,000

PH $7,300 $7,300

SM $5,000 $5,000 $10,000

SC $8,750 $8,750 $17,500

Total Cost (without RR)

$99,800

RR (to 2022) $105,000

TOTAL COST (with RR)

$204,800

Stages of Sediment Projects (7) Post Construction

(6) During Construction

(5) Tender Award

(4) Detailed Engineering Design

(3) Preliminary Engineering Design

(2) Conceptual Design

(1) Sediment Assessment

Sediment Remediation Challenges Cost Estimate Increases

Increasing Certainty in Estimate

Sediment Remediation Challenges

•  Ability to secure1/3 local funding –  Depressed local markets –  Local industry bankruptcy issues –  Lack of interest/responsibility

•  Project lead (Contracting Authority) •  Future Liability for in-situ remediation •  Site Access/Ownership Issues •  Coordinating stakeholder (funding parties) interest •  Cost overruns during implementation •  Cost estimate increases

Science Challenges to GL Sediment Remediation

  Great Lakes Areas of Concern •  Lack of Chemical Guidelines for COC in Sediment •  Absence of confirmed dose-response information for COC •  Development of innovative techniques to identify and manage debris •  Develop and implement feasible pore water sampling methods •  Develop approaches to reduce uncertainty related to identification of

contamination layer •  Understanding the dynamics of natural recovery and recovery post

remediation and the ability to to predict through modelling when short and long term goals will be achieved

•  Addressing temporal variability in benthic community structure related to stressors such as invasive species, climate change, change in abundance of native taxa, watershed disturbance etc.

Thunder Bay North Harbour Sediment Management

RAP Workshop February 8, 2012

Thunder Bay Area of Concern

Thunder Bay Project Site

Thunder Bay North Harbour - Contaminated Sediment Management

Contamination Overview

Contaminated Sediment

Mercury Concentrations in Surficial Sediments

Mercury Concentrations at Depth

Enriched Organic Sediment

Toxicity and Biomagnification

•  Monitored natural recovery

•  Capping (sand or reactive cap)

•  On-site confined disposal facility

•  Dredging with disposal at an off-site confined disposal facility

•  Dredging with upland disposal

Conceptual Sediment Management Schedule

Additional Studies in support of SMO – 2012 Decision on preferred SMO – 2013 Engineering Design/ EA – 2014-2015 Construction (assume 2 to 5 years) – 2016-20?? Long-term monitoring – 15 years

Peninsula Harbour Sediment Management

RAP Workshop February 8, 2012

Peninsula Harbour Area of Concern

Project Description •  Elevated levels of Mercury and PCBs are

present in sediment in Peninsula Harbour with the highest concentration found in Jellicoe Cove.

•  Contaminated sediment in Jellicoe Cove is acting as a source of mercury and PCBs for the rest of the PH and posing risk to biota.

•  Results of Risk Assessment indicated that sediment management action is required

Peninsula Harbour Shoreline 2007

1. Sediment Sampling - Chemistry

Surface concentrations of mercury average 7 ppm, which is 3.5X higher than the guideline.

Average subsurface concentrations are 3X higher than average surface concentrations.

Sediment Core Sample

2.  In-Situ Tracer Measurements (6/05-7/06)

•  Divers applied a tracer (mineral) in slurry form to measure sediment mixing rate

•  Cores were initially collected to determine background levels

•  One year later, sampling revealed mixing of surface sediment to 8 cm

Conclusion: Mixing generally occurs in top 8 cm of sediment

3a. Rotating Circular Flume Tests

•  Tells us how the sediment resists bottom currents

•  Large diameter sediment cores collected and tested for erosional resistance in a rotating circular flume

Conclusion: Strong bottom currents are required to mobilize sediment that is deeper than 5 cm

Objective: Measure strength of bottom current needed to mobilize sediment

3b. In Situ Flume Experiments (9/07)

•  At 4 sites, flume was deployed in Jellicoe Cove to measure erosional resistance of surface sediments

•  Compared to subsurface sediment, surface fines erode with weaker bottom currents

Conclusion: Surface sediment (1-5 cm) erodes with bottom currents 10x weaker than for deeper sediment

Objective: Measure strength of bottom current needed to mobilize sediment

4. Wave Climate (6/05-7/06 and 11/06-5/07)

•  Bottom currents measured by a current meter (MAVS-3)

•  Year-round •  6 months in high energy

season

Objective: Measure bottom currents in Jellicoe Cove

Conclusion: Currents strong enough to move surface sediment are common. Currents strong enough to move subsurface sediment are rare.

Conclusions

1.  Thin layer capping will help manage the surface sediment that is currently mobile.

2.  Dredging is not required to address subsurface sediment mobility.

Sediment Management Option

•  Thin layer capping was selected to manage the contaminated sediments.

•  Area with > 3 ppm Hg will be covered with 15 to 20 cm of clean sand (approx. 20 hectares – about 40 football fields)

•  Area with >0.34 ppm PCB will be covered with 15 to 20 cm of clean sand (approx. 5 hectares – about 5 football fields)

Thin-Layer Capping

Sediment Profile Imaging Camera

Thin layer cap

Capped sediment

EA Findings

Results of the assessment indicate: • DFO Authorization under section 35(2) of the Fisheries Act is

required. • Town of Marathon may be subjected to truck traffic and noise

during the construction period • AECOM confirmed that local pits in the Marathon area have

suitable cap material. • There are no additional regulatory restrictions on dredging post

cap to allow access to larger vessels • The MPI water intake will be protected during construction.

Sediment Remediation Schedule

MERX Tender Posting – March 2012 Tender Award – April 2012 Mobilization – May 2012 Pilot Scale Demonstration – June 2012 Production Capping – June – Aug 2012 Demobilization – September 2012 Post Engineering Assessment 2013 Long Term Monitoring – 2014

Long Term Monitoring Plan Year Years after Cap Monitoring Component Survey Period 2013 1 Cap Movement and Submerged Aquatic Vegetation fall

Cap Thickness Study summer/fall

2015 3 Cap Movement and Submerged Aquatic Vegetation fall

2017 5 Cap Movement and Submerged Aquatic Vegetation fall Benthic Community/Benthic Tissue/Sediment Chemistry fall Fish Tissue Survey last week of June to end of August

2022 10 Cap Movement Survey fall Benthic Community/Benthic Tissue/Sediment Chemistry fall Fish Tissue Survey last week of June to end of August

2027 15 Cap Movement Survey fall Benthic Community/Benthic Tissue/Sediment Chemistry fall Fish Tissue Survey last week of June to end of August

2032 20 Cap Movement Survey fall Benthic Community/Benthic Tissue/Sediment Chemistry fall Fish Tissue Survey last week of June to end of August

St. Clair River – Sediment Management

RAP Workshop February 8, 2012

St. Clair River

St. Clair River – Contaminated Sediment Management

St. Clair River AOC

St. Clair River Sediment Remediation Project

•  Eddy Pump hydraulic dredge used to remove 13,000 m3 contaminated sediment (Hg, and organics) with physical dewatering and anaerobic bioremediation (biopile) and on-site disposal

Dow River Cleanup

Dow River Cleanup

Habitat Restoration - 2005

•  Restore the area to a state of granular sediment.

•  Enhance fisheries habitat and promote benthic macroinvertebrate recolonization.

Priority Zones for Sediment Management

Three priority zones for management;

1.  Volume near Suncor dock, (25,700m3)

2.  Volume near Shell dock (5,500m3), and

3.  Volume near Guthrie Park (3,750m3)

Suncor

Guthrie Park

Shell

These areas represent depositional areas downstream from the original source.

St. Clair River Priority Areas

1.  Sediment Chemistry •  61% of sediment samples more than

2 mg/kg Hg (Provincial SEL) •  Hg in buried sediment up to 5 times

higher than surface sediment in some places

3.  Sediment Toxicity •  No strong evidence of toxicity to Hg

5.  Changes to Benthic Community •  No strong evidence of community

changes due to Hg compared to reference sites

7.  Potential for Biomagnification •  Negligible risk to wildlife that eat fish •  Risks to some fish species •  Priority Areas identified based on

risk to fish

Management Goals Removal of Hg-contaminated sediment:

1.  as a source to downstream sites 2.  to promote local risk reduction 3.  for contaminant mass removal