Presenter: Kylie Evans 9 October 2014

Transcription

1 Presenter: Kylie Evans 9 October 2014

2 Tamworth Sewerage Augmentation Scheme The Tamworth Sewerage Augmentation Scheme has two major components: Westdale Wastewater Treatment Plant Tamworth Effluent Reuse Farm The budget for these two components was approximately $80m

3 Westdale Wastewater Treatment Plant

4 Planning for the Augmentation Scheme commenced in At this time: Tamworth had two Wastewater Treatment Plants: one at Swan Street and one at Westdale Swan Street WWTP had a capacity of 18,000ep and Westdale WWTP had a capacity of 33,000ep Swan Street WWTP was an aging plant and encroachment by residential areas compromised its viability Westdale WWTP was overloaded

5 The WWTP Augmentation meant: An increase in capacity of Westdale WWTP from 33,000ep to 61,000ep Decommissioning Swan Street WWTP Building a Plant which could cater for population growth to 2025 Building a Plant which could cater for industrial growth to 2025

6 Plant Capacity Prior to shut down Swan St WWTP was treating close to 4 ML/day Prior to the Augmentation, Westdale WWTP was treating a little over 7.5ML/day At present, the augmented Westdale WWTP is treating approximately 11.7ML/day In 2025, Westdale WWTP will treat approx 14.8ML/day

7 Wet Weather Capacity The augmented Westdale WWTP can: Provide high level primary treatment (mechanical screening and degritting) for eight times Average Dry Weather Flow (ADWF); Provide adequate primary treatment (manual screening and degritting) of all flows, even bypass flows; Provide secondary treatment (biological processing) for nearly five times ADWF; Provide disinfection for all flows.

8 Licence Conditions Licence Limit for discharge to Anabranch Licence Limit for discharge to Farm Biological Oxygen Demand 20 mg/l 20 mg/l Suspended Solids 20 mg/l 20 mg/l Phosphorus 12 mg/l 12 mg/l Nitrogen 25 mg/l 30 mg/l Ammonia 12 mg/l 15 mg/l Coliforms 3000 cfu/100ml 1000 cfu/100ml ph Oil & Grease 10 mg/l 10 mg/l TDS 600 mg/l 600 mg/l

9 The NSW Office of Water (NOW) also plays a role in regulating wastewater. NOW uses the National Guidelines for Water Recycling to establish boundaries for the protection of human health. The Guidelines require a number of barriers to be in place to prevent people being exposed to disease-causing microorganisms. The Guidelines also require effective systems for monitoring and detecting when the process may not be optimal.

10 Procurement Options 1. Design and Separate Construction 2. Design and Construction 3. Alliance Can be quickest Innovation at all stages Contractor motivated to save money Less resources required by Principal As a result of these advantages, combined with the fact that Council had had difficulty with 1 and 2 previously, Council decided to go with an Alliance.

11 Treatment process components New Pump Station and Emergency Storage at the Swan St WWTP site Pretreatment for industrial waste stream with new screening & degritting and utilising existing Trickling Filters New elevated Inlet Works with mechanical screening and degritting for 8xADWF and odour control via two odour beds Biological treatment in 4 Intermittently Decanted Aeration Lagoons (4.6xADWF) New blower building with six high speed centrifugal blowers Disinfection Ponding for all flows with 25 days hydraulic retention time Effluent Transfer Pump Station and 7.5km rising main to the Effluent Reuse Farm 1500ML Effluent Storage Dam Two new sludge lagoons of 20ML capacity each Sludge storage and drying area New administration building with office, laboratory, meeting room and amenities Chemical delivery and storage area

12 Additional Works Since the completion of the Alliance Contract, Council has further developed the site with Demolition of old inlet works Demolition of the old amenities building Construction of an additional sludge lagoon of 20ML capacity Additional roadworks Installation of a septic waste delivery point New machinery shed/workshop Demolition of old Swan St WWTP structures Continuing process optimisation

13 EPA Licence Meeting the Targets Licence Limit for discharge to Farm Average Influent Quality after Industrial Pretreatment (since 1/10/2011) Average Results (since 1/10/2011) Biological Oxygen Demand 20 mg/l 253mg/L 4.3 mg/l Suspended Solids 20 mg/l 339 mg/l 14.7 mg/l Phosphorus 12 mg/l 12mg/L 2.5 mg/l Nitrogen 30 mg/l 57mg/L 6.0 mg/l Ammonia 15 mg/l 32mg/L 0.3 mg/l Coliforms 1000 cfu/100ml 16,460,000 cfu/100ml 73 cfu/100ml ph Oil & Grease 10 mg/l 29 mg/l <5 mg/l TDS 600 mg/l 569mg/L 513 mg/l

14 Section 60 Approval The Verification Report demonstrated: The IDALs are consistently achieving bacterial LRVs of 2.5. The maturation pond system is achieving bacterial LRVs between 1.3 and 4.2. Additional LRVs will be achieved through management measures at the Reuse Farm.

15 Tamworth 100% Effluent Reuse Farm

16 Why a Reuse Farm? The 100% Effluent Reuse Farm was motivated by: The spectre of significant Load Based Licensing Fees. Costs associated with treating the wastewater to Sensitive Waters criteria. Application of effluent to the Reuse Farm determined the technology that was needed at the WWTP. Concerns, at that time, over the Water Reforms and water availability. Recognition that the wastewater, which had originally been purchased by the City as surface water, was an asset of the City and an economic opportunity for the region.

17 Council purchased suitable land for the agricultural reuse of effluent at a distance of approximately 7-8km from the Westdale WWTP site.

18 The Farm The whole area of the Effluent Reuse Farm for now and in the future is 1500 hectares. At present there are 600 hectares under centre pivot irrigators. The residual area is dry-land farmed. The effluent that is expected to be supplied to the Farm ranges from 4250ML/year at present flow rates, up to 6000ML/year in 2025 A clause in the operating contract allows Council to redirect up to 20% of effluent for some other purpose at some time in the future

19 Procurement: The Effluent Reuse Farm Contract The Establishment and Management of the Effluent Reuse Farm was achieved under a single contract which included: The design of the Effluent Reuse Farm The construction of the Effluent Reuse Farm The operation of the Effluent Reuse Farm for 10 years.

20 The Farm Infrastructure The Farm infrastructure includes: 13 centre pivot irrigators A pump station with 5 pumps capable of pumping 53ML/day Pipework for two future centre pivot irrigators On-site roads Seven catchponds to collect run-off from the farm. Flow from these catchponds is measured Office and machinery shed Vegetated 20 metre wide buffer around the whole farm, comprising trees and shrubs

21 Constraints The crops grown on the Farm must be capable of using all of the water and nutrients supplied to the Farm. No cotton is to be grown. No crops for human consumption are to be grown. No bird attracting crops are to be grown. Fodder from the Farm may not be fed to pigs. Lactating cows, cattle under 12 months old and pigs may not graze on the Farm.

22 Monitoring Extensive monitoring and assessment of the environment is to be undertaken as part of the operation of the Reuse Farm. This includes: Effluent testing and analysis Groundwater testing and analysis Surface water testing and analysis Soil testing and analysis Run-off testing and analysis Atmospheric monitoring Additionally, there will be an assessment of the mass of nutrients which are released to the site and an assessment of the mass of nutrients removed with each crop. This will be reported to the EPA annually.

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