lakelands golfview estate retirement village - nutrient and … · 2017-03-22 · lakelands...

AQUASOL WA TER TREATMENT SOLUTIONS

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LAKELANDS GOLFVIEW ESTATE RETIREMENT VILLAGE - NUTRIENT AND IRRIGATION MANAGEMENT PLAN

AQUASOL

82-86 BERINGARRA AVE, MALAGA, PERTH WA 6090

TEL: 08 9248 7533 FAX: 08 9209 3975

[email protected]

mailto:[email protected]�

Aquasol Pty Ltd

1/26/2017 LAKELANDS GOLFVIEW ESTATE RETIREMENT VILLAGE - NUTRIENT AND IRRIGATION MANAGEMENT PLAN

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Content

1. Introduction

2. Project Setting

2.1 LOCATION & TOPOGRAPHY

2.2 SURFACE GEOLOGY

2.3 PHOSPHORUS RETENTION INDEX

2.4 ACID SULPHATE SOILS

3. Rainfall & Evaporation

4. Water Resources

4.1 SURFACE WATER

4.2 GROUNDWATER

4.2.1 Separation to nearest Public Drinking Water Source Areas (PDWSA)

5. Proposed Land Use and Nutrient Application

5.1 NUTRIENT APPLICATION

5.2 NUTRIENT REMOVAL

6. Site Management

6.1 IRRIGATION SCHEME

6.2 WATER TREATMENT

6.3 IRRIGATION MANAGEMENT

7. Protection of Natural Water Resources

8. Monitoring and Reporting

9. Contingency Plans

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1.- Introduction This report describes the proposed sewage infrastructure to service a new retirement village located at Clubhouse Ln, Gnangara WA 6077. Development comprises a total number of 290 residential dwellings. Wastewater management for each lot will be via each lot connecting to a WWTP. Sewer will be collected from the units and plumbed to a package WWPS, which will pump waste water to the WWTP. From there, treated water will be sent to a storage tank (as needed basis) at Golf Course compound for irrigation. Figure 1: Proposal Map

Possible irrigation area: WWTP location: Wetland: Storage tank: This Nutrient and Irrigation Management Plan (NIMP) has been prepared by Aquasol Pty Ltd on behalf of Handel Property Group, project managers, in support of a RWQMP application for the proposed onsite Waste Water Treatment Plant and Irrigation Scheme. The proposed wastewater treatment scheme will effectively provide sewage services to this new development, and treat water to a quality suitable for irrigation.

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Table 1: Process Details

Development Info

No of Lots

290

No of EP/lot 3

L/day-EP 150

Max Effluent [L/day] 130,000

This NIMP demonstrates that the proposal has considered relevant environmental factors in its development and that appropriate design and ongoing management has been established to ensure water and nutrient application will not result in leaching to the surrounding environment. The NIMP also provides a description of the site and its surrounds, describes and interprets monitoring data, and provides a description of the proposed wastewater treatment and irrigation scheme. Management strategies and future monitoring programs are then provided to ensure environmental requirements and safeguards are met. This NIMP has been prepared in accordance with the principles, objectives, and key criteria of the Department of Water’s Water Quality Protection Note 33 Nutrient and Irrigation Management Plans (June 2010) and Water Quality Information Sheet 4 Nutrient and Irrigation Management Plan Checklist (August 2010) publications. Table 2: Administrative Details Proponent David Lee – Developer representative

Applicant Francisca Haro – Aquasol representative

Site Location Clubhouse Ln, Gnangara WA 6077

Construction Timeframe Commencement : Immediately after approvals granted from DER, DoH and ERA Duration : 12-16 weeks

Project Duration Duration : Ongoing

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2. Project Setting 2.1 Location & Topography The entire golf course site comprises an area of approximately 90[ha], and the proposed development site, an area of approximately 10 [ha] located to the north and east of Clubhouse Lane at Lakelands Country Club. Golf course encompasses a wide range of environmental conditions include a diverse range of plant and animal communities. While the golf course has to operate as a golf course and not a nature reserve, it still has a duty of care to manage these areas in a responsible and sustainable manner. The subject golf course area contains two separate areas densely vegetated with bulrushes and other vegetation typical of swamps, and vegetation comprising grass with sparse trees and shrubs.

Figure 2: Location

2.2 Surface Geology Published geological maps for the area depict the flat northern portion of the site as being underlain by peaty clay with variable sand content and of lacustrine origin. The surrounding more elevated potions of the site are depicted as being underlain by Bassendean Sand. Below these upper soil layers, the deeper geological formation is reported to comprise Poison Hill Greensand, which is expected to occur some 50m below existing ground levels. Based on the known history of the site and surrounding land levels, some superficial depths of fill could be anticipated due to previous agricultural activities.

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2.3 Phosphorus Retention Index The soil’s ability to retain phosphorus can be described by its PRI (Phosphorus Retention Index), which is related to the quantity of iron and aluminium oxides in the soil matrix. Soils in Western Australia have naturally low concentrations of nitrogen and phosphorus. Phosphorus in the soils may be incorporated into organic matter, bound to metals such as iron, aluminium or calcium, or dissolved in water. Dissolved phosphorus is readily available for plant growth. Organic phosphorus is ‘readily’ released as biological material decays. Inorganic phosphorus however provides a long-term resource as it can be released from the binding material in response to waterlogging, oxygen and pH changes. Gerritse (2002) noted that PRI can sometimes be of secondary importance because even at low PRI values P is rapidly bound in the topsoil for most soil types. Where P is bound to topsoil, water erosion effectively becomes the main mechanism of export. It should be noted that P movement through the landscape is influenced by many factors, and it can move either dissolved in water or attached to soil particles. In addition to soil and landform, it should be noted that many other factors such as catchment size, drainage density, proximity to drains, rainfall/runoff, climate and vegetation also affect phosphorus movement. The iron concentration of irrigation water is also a factor and can improve soil PRI with time. 2.4Acid Sulphate Soils (ASS) Acid Sulphate Soil (ASS) is the common name given to naturally occurring soil and sediment containing iron sulphides. These naturally occurring iron sulphides are generally found in a layer of waterlogged soil or sediment, and are benign in their natural state. When disturbed and exposed to air, however, they oxidise and produce sulphuric acid, iron precipitates, and concentrations of dissolved heavy metals such as aluminium, iron and arsenic. Release of acid and metals as a result of the disturbance of ASS can cause significant harm to the environment and infrastructure. The Perth Metropolitan Acid Sulphate Soils (ASS) Risk Map shows that the site is located in an area of “High Risk” of ASS occurring within 3m of natural surface. However, it has been advised by developer’s consultant, that in terms of the disposal of treated water - (P)ASS is irrelevant. Risk area is not being exposed, and is located remotely from the irrigation zone (adjacent to the wetland to north). In saying that, they will have an ASSMP for the sewer retic and pump station in parallel to be prepared by Emerge Associates.

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3. Rainfall & Evaporation

The annual and monthly rainfall distribution for the site is shown in Table 3 below. Based on the Bureau of Meteorology, the rainfall summary for the past 10 years at nearest station Wanneroo (009263) is detailed below, having the majority of this rainfall falling between May and September each year. Table 3: Gnangara - Average Monthly Rainfall Period J F M A M J J A S O N D Rainfall (mm) 13.6 11.7 19.6 44.0 92.5 126.9 131.7 117.2 98.9 28.7 29.9 17.6 As shown in table 4 below, evaporation is considerably higher than rainfall at an average of approximately 160 mm/year. Table 4: Average Monthly Evaporation Period J F M A M J J A S O N D Evaporation (mm)

280 250 200 130 90 70 60 85 110 160 260 260

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4. Water Resources 4.1 Surface Water There are no natural watercourses considered likely to be affected by the wastewater treatment and irrigation scheme. There are no wetlands, watercourses or water dependent ecosystems on the site. Existing wetland is located to the east of the site approximately 1.0 km away. The Perth Groundwater Atlas suggests groundwater levels seasonally vary from approximately RL 44m AHD to RL46m AHD. Historical aerial photos of the site indicate that in 1974, the site became flooded to a level of approximately 46m AHD. This is inferred to be consistent with the maximum level for the site as shown on the Groundwater Atlas. The historical groundwater monitoring data indicates that the regional peak groundwater level has reduced by about 1.0m over the past 40 years. Figure 3: Site plan and Underground Water Contour

In red: WWTP Location In yellow: Wetland location In blue: irrigation area

Underground Water Contour (46.2m max recorded groundwater level)

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4.2 Groundwater 4.2.1 Separation to nearest Public Drinking Water Source Areas (PDWSA). For land planning and development purposes within any PDWSA, three protection areas (P1, P2 and P3) have been defined based on present land use, tenure, and the vulnerability of the water body to harm. These areas are each managed in a different way to provide effective protection of water resource quality. Figure 4: DWSPA

** Source: Perth Ground Water Atlas

P1 areas are defined and managed to ensure there is no degradation of the water resource in these areas. This is the highest level of protection for the water source and normally will apply to land owned by the State, and that is characterized by low-intensity and low-risk land use, such as forestry. Protection of the public water supply outweighs virtually all other considerations in respect to the use of this land. P1 source protection areas are managed in accordance with the principle of risk avoidance. P2 areas are defined to ensure that there is no increased risk of pollution to the water source. P2 areas are declared over land where low-risk development already exists. Protection of public water supply sources is a high priority in these areas. P2 areas are managed in accordance with the principle of risk minimisation and so conditional development is allowed. P3 areas are defined to manage the risk of pollution to the water source. These areas are declared over land where public water supply sources must coexist with other land uses such as residential, commercial and light industrial development. Protection of P3 areas is achieved through management measures defined via management guidelines or site-specific conditions that limit the contamination risk to water resources from the land use or activity. If however the water source becomes significantly contaminated, then water supplied from P3 areas may need to be treated or an alternative water source found. Lakelands Golfview Estate Waste Water Treatment is not located within any Public Drinking Water Source Area.

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5. Proposed Land Use and Nutrient Application 5.1 Nutrient Application The proposed WWTP will provide treated water of a quality suitable for surface irrigation in private open areas within adjacent golf course. After treatment, nutrient concentrations for the water prior to irrigation will be reduced to: • TN: 10 mg/L • TP: 1 mg/L This will be achieved as: Table 5: Nutrient Details Total Max Effluent [L/day] 130,000 Area available for irrigation [Ha] 10 Expected effluent concentration (after treatment)

N [mg/L] 10 P[mg/L] 1

Maximum allowed ** [Kg N/yr/Ha] 180 [Kg P/yr/Ha] 20 Area required for irrigation [Ha] 2.37 [Ha] 2.64 **From soil type B (nutrient application) - table 6 below These application rates are well within the Department of Health’s maximum loads for inorganic nitrogen (180 kg/ha/yr) and reactive phosphorus (20 kg/ha/yr) to control eutrophication for sites with soil type B (mixture is of gravel/loam/sandy, table 6 below). Figure 5 shows the extent of the private open space to be irrigated by treated wastewater. The total viable irrigation area on the site is approximately 20 ha, well over minimum area needed at Plan’s maximum load capacity. Figure 5: Irrigation area

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Table 6: Max Nutrient Guidelines

Source: Department of Water, irrigation with nutrient-rich wastewater, Water Quality Protection Note WQPN 22 5.2 Nutrient Removal

- Nitrogen Removal Nitrogen in waste water will be removed to an expected concentration by ‘Simultaneous Nitrification-Denitrification’ process, which is the conversion of the ammonium ion to nitrogen gas. For this, 2 separate aerators will be installed in Tank 2 and 3. Aerators will work independently to provide required Aerobic/Anaerobic conditions. Aerobic / Nitrification phase

NH4 + O2 NO2 + 2H+ + H2O (Ammonium ion to Nitrite) NO2 + O2 NO3 (Nitrite to Nitrate) Anaerobic / Denitrification phase

NO3 NO2 NO N2O N2 (gas) By having independent aeration systems, Nitrogen reduction will increase. Tank 2, fully aerated, will boost nitrification conversion, plus additional intermittent aeration in tank 3. Denitrification conversion will then be carried out in tank 3 when aerator is OFF, and in the following water tanks of the treatment train (anoxic conditions).

http://en.wikipedia.org/wiki/Ammonium_ion�

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- Phosphorous Removal Waste water will be dosed with Aquasol’s Floc M2600 (Poly Aluminium Chloride), widely used in waste water treatment to settle large particles and precipitating phosphates (AlPO4). Basic reaction detailed below: 3 AlCl3OH + 3NaPO4 3ALPO4(s) The dosage of PAC is a function of the phosphorous removal required. The efficiency of coagulation falls as the concentration of phosphorous decreases. In practice, an 80-90% removal rate is achieved at dosage rates between 60 to 150 mg/L. As an internal practice, dosage will be established on bench-scale tests and by full-scale tests using a portable spectrophotometer, however, based on previous experience, PAC dosage is expected to be at approximately 80 mg/L. Aluminium in PAC (floc) will be dosed at a minimum rate to control P and suspended solids only. By having always surplus of P and SS in water, will indicate that all PAC fully reacted, and expected concentration in the irrigation stream will be cero.

No additional nutrients via fertilisers will be applied to the irrigation area.

6. Site Management

6.1 Irrigation Scheme All waste water entering the treatment system comes from retirement village – 290 residential dwelling (max of 130Klt/d), no storm water expected to enter in the system. Table 7: Irrigation Scheme Summary Water Source & Supply Details

Source of Irrigation Water Wastewater Treatment Plant servicing 290 lots

System Storage Capacity Total : 130 kL/d

Irrigation Details

Max Irrigation Volume 130kL/day

Type of Irrigation Surface irrigation

Irrigation Schedule Table 10

Daily Irrigation Rate 5 L/day-m2 (table 8)

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6.2 Water Treatment The process incorporates Anaerobic and Aerobic Treatment along with Filtration and Disinfection to facilitate biological wastewater treatment to effluent standards for Biochemical Oxygen Demand (BOD5), Turbidity, Total Nitrogen (N), Total Phosphorous (P) and E-coli. The Anaerobic/Equalization Tank serves as an Anaerobic digester and as an Equalization tank buffering peak flows throughout the day. The tank is fitted with a level sensor for lowering the tank level prior to peak flow periods. From there, water is pumped into the Aeration Tank for secondary treatment. The Aeration Tank has been sized to accommodate the requisite volume required to treat the incoming organic (BOD5) load, and batch aeration system to control Nitrogen. Submersible aerator will supply a high volume of oxygen for the biological process and will facilitate recirculation of the wastewater undergoing treatment on the entire volume of the tank. From there, water will be transferred into the SBR Tank. The SBR will batch three to four times daily as required. Aeration is stopped for one hour to allow settling in the tank. Flocculent in tank will aid in the settling process. Once the tank has settled a pump will clear/pump water from the top of the tank into the Polish Tank. Finally, in Polish tank, water will be pumped through 5 x deep bed media filters fitted with automatic backwash valves that can be set to operate at a selected interval via the touch screen HMI. Backwash from the filters will be sent to the Sludge Tank. Sludge settled at the bottom of the tanks will be also sent to the Sludge Tank. Once the Sludge Tank is full, excess water will be sent back to the Anaerobic Tank for re-retreatment, and solids removed as needed basis to an approved disposal site. All alarms in the system will be recorded in the PLC, and activate a flashing light on the control box. All wiring will be completed to Australian standards. System control will be via Delta PLC & HMI.

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6.3 Irrigation Management The key objective of this irrigation management is to avoid surface runoff and excess nutrient leaching. The system has been designed to promote efficient and even water distribution. Even though irrigation area hasn’t been specified yet, and geotechnical report was conducted at the development area, it was anticipated (and advised by developer) that soil conditions remain similar in the entire golf course area, and that vast area available for irrigation will provide alternative location avoiding any possible hazard. If required, an additional geotechnical report could be conducted in the irrigation area when Golf Course representatives specify location of it. However is noted that no endanger vegetation is present on site, nor superficial water. Based on table 8, Design Irrigation Rate for a soil mixture of sand and loam is 5 Litres/m2-day. Table 8: Soil Irrigation Rates (DIR) Soil Type Litres/m2-day Sand and gravel 5

Sandy loams 5 Loams 4

Clay loams 3.5

Light clays 3

Medium to heavy clays 2

Total treated water volume will be irrigated in batch of 2 cycles a day to avoid any possible overload. Expected irrigation times will be later in the afternoon and early mornings (table 10). Table 9: Irrigation Loads - Maximum Capacity Total Volume 130,000L/d

Total Area Available for irrigation 10[ha] Total Area Needed for irrigation 2.65[ha] DIR 5 L/m2-d Area Needed - TP Discharge 2.37[ha] Area Needed - TN Discharge 2.64[ha] DIR Discharge Area 2.6[ha]

Table 10: Preliminary Irrigation Schedule Irrigation On Irrigation Off Irrigation On Irrigation Off 3am -6am 6am -8pm 8pm – 1am 1am -3am 3 hrs 14 hrs rest 5 hrs 2 hrs rest

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The following best practice initiatives and maintenance practices will be implemented as part of continual system evaluation in order to manage the irrigation system:

• Employee in charge to be correctly trained, and proper PEE to be used • Monitoring and recording of system flow rates using an automatic flow meter • Monthly system field checks to ensure problems are addressed in a timely manner (if any) • Management of pump stations to ensure adequate distribution of irrigation • Routine maintenance of the irrigation system for optimum performance • Inspection of the pumping station, and conduct pump/motor maintenance

7. Protection of Natural Water Resources

Safeguards for the protection of natural water resources are presented in Table 11, addressing key issues identified in DoW (2010a), and reflecting information and analysis presented in other Chapters of this NIMP. The risks to natural water resources are considered minor and manageable via ongoing operation, maintenance and monitoring programs. The monitoring program is discussed in detail in Chapter 8. Note, no contaminant fate and transport modelling has been undertaken as the required irrigation area is smaller than the 10 ha, requirement specified in DoW (2010a) to trigger the need of this modelling. Table 11: Natural Water Resource Safeguards Issue Safeguards

Nutrient Retention

• Nutrient application rates to be less than DoH specified application criteria rates to control eutrophication • Ongoing Operation & Maintenance Management to keep system running as required • Post Development Monitoring Program to confirm treatment achievement

Groundwater Table / Waterlogging

• Clearance to groundwater from natural surface complies with GSP • Average daily irrigation rate below specified - DIR of 5 L/m2-day • Ongoing Operation & Maintenance Management • Monitoring Program

Nutrient Wash into Waterways

• Water movement across the site is not expected to occur

Proximity to Sensitive Water Resources

• Wetland more than 1km from proposed irrigation area • Site located outside PDWSA

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8. Monitoring and Reporting

The proposed monitoring program is shown in Table 12. Post development monitoring will be carried out weekly during commissioning period and monthly thereafter. The quality of the effluent will be controlled and checked at sample points, and sent to NATA approved laboratories for analysis. Mandatory annual report will be produced and submitted to DoH, report can be also sent to DER/EPA if requested. Annual review outcomes will be used to provide continual improvement of the system if required. Table 12: monitoring program Parameter Expected results after

treatment (limits) Commissioning Monitoring Ongoing Monitoring

E.Coli <10cfu/100mL Weekly Monthly

Biochemical Oxygen Demand (BOD5)

< 20mg/L Weekly Monthly

Turbidity <5NTU Continuously online Continuously online

Disinfection

0.2 – 2 mg/L Continuously online Continuously online

pH 6.5 – 8.5 Continuously online Continuously online

Total Nitrogen (TN) <10 mg/L < 180 [Kg N/yr/Ha]

As requested As requested

Total Phosphorous (TP) < 1mg/L < 20 [Kg N/yr/Ha]

As requested As requested

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9. Contingency Plans

Proposed equipments for the WWTP will be controlled automatically by a Program Logic Controller system, which will warn by an alarm any possible malfunction. Buffer volume in tanks will be used as contingency capacity in case irrigation is not possible and water cannot be disposed (avoiding uncontrolled overflows).

Table 13: Proposed Alarm system Affected Component Alarm Message Corrective Actions

Inlet Screen Screen Failure Qualified staff to check screen malfunction,

advise Aquasol ASAP

Transfer Pumps Transfer Pumps Failure Qualified staff to check pump malfunction,

advise Aquasol ASAP for replacement if needed

Aerators Aerator Failure Advise Aquasol ASAP for replacement if needed

Chemical Injection Chemical low level Advise Aquasol ASAP for refill of chemicals

Chemical Pumps Chemical injection

failure

Advise Aquasol ASAP for replacement if needed

Media Filter Filter Blockage Advise Aquasol ASAP for replacement if needed

** Final alarm system to be confirmed after approval. In terms of the ongoing review of data collected during the monitoring program, the following process will be followed to determine if any contingency action is required:

• Review data and assess spatial extent of any concern. • Determine if due to the irrigation scheme or other factors. • Perform appropriate action as required. • Record and report any incident and action taken. • If necessary, inform and provide monitoring data to DER/EPA

Possible contingency actions which may be taken include:

• Identify and remove any point sources. • Review operational and maintenance practices. • Consider alterations to open space areas and vegetation including soil amendment. • Consider modifications to the wastewater treatment and irrigation system.

lakelands golfview estate retirement village - nutrient and … · 2017-03-22 · lakelands...

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