December 2017 Tamar Estuary
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- Bu səhifədəki naviqasiya:
- Project Cost ($ million)
- Total 74.6
Tamar Estuary River Health Action Plan 37 To this end, it is proposed that a first step in considering regulatory change is for the Department of Primary Industries, Parks and Environment to prepare a discussion paper on the potential options, costs and benefits of changed regulatory arrangements for the combined system. The paper should be developed by the end of the first quarter of 2018 and should seek stakeholder views on the options presented. Other policy improvements are also worth considering, including requirements for consideration of water sensitive urban design (WSUD), particularly for new buildings, major developments or new subdivisions. In order to ensure the success of the implementation of any improved WSUD policy, education and training must be developed for the general community, planners, regulators and construction industry. Compliance monitoring of the installation and operation of WSUD devices is also considered critical for success. This is largely an issue for planning authorities in the catchment. 5.8
Recommendations The working group ranked the priority projects outlined at section 5.5 primarily according to the effectiveness of the option in reducing the sewage loading ultimately received by the Estuary. Figure 9. Costs and benefits of hard infrastructure combined system projects From Figure 9, it is clear that three projects provide above average return of investment, those are: 1.
2.
The New Combined Rising Main; and 3.
The offline storage located at New Margaret Street Pump Station. Quantifying the benefits of these first three projects cumulatively, it is estimated that the reduction in sewage discharged to the Estuary from the combined system would be 53 per cent for an estimated $41.4 million investment.
Tamar Estuary River Health Action Plan 38 This is not to say that the other projects are not of value, but there are diminishing returns to investment. Figure 10 displays the cumulative reductions in sewage discharged to the Estuary based on the following proposed packages of works: 1.
2.
1 + The New Combined Rising Main; 3.
2 + The offline storage located at New Margaret Street Pump Station; 4.
3 + The South Launceston Diversion in conjunction with the offline storage proposed to service the Esplanade; and 5.
4 + The offline storage located at Forster Street Pump Station; However, all of these priority project are recommended to be progressed. To put the proposed mitigation options in perspective, Figure 10 also displays separation as a stand-alone option.
Full separation of the system has an estimated cost of $435 million and assumes that this would decrease combined system overflows to the Estuary by 100 per cent. It is clear the proposed mitigation projects provide significant value for money (approximately a 70 per cent reduction in combined system sewage load for an estimated $74.6 million total investment).
Tamar Estuary River Health Action Plan 39
Esplanade storage 6.7 Forster St storage 8.4 New Margaret St storage 10.0 South Launceston Diversion 18.1 West Launceston Diversion 4.6 New combined rising main 26.8 Total 74.6 Table 3. Proposed hard infrastructure projects and costs It should be noted that the Estimates for the LSIP works (West Launceston and South Launceston Diversions) have been provided by TasWater directly. These estimates have been undertaken on the preliminary design of the pipelines and pump stations for the transfer systems and include allowances for design, approvals and construction. The construction cost estimates have been calculated by John Holland within a +/- 20 per cent limit of accuracy. Estimates for non-LSIP options have been prepared based on conceptual designs, using similar construction rates used for LSIP. Estimates include an allowance of 20 per cent (of construction cost) for engineering/approvals, and 30 per cent construction contingency. Recommended changes to the regulatory, policy and operational environment of the combined system should also be considered by relevant authorities. The recommended discussion paper on the current regulatory arrangements for the combined system is scheduled for release within three months, while planning authorities would be encouraged to consider policy and operational changes as soon as possible.
Tamar Estuary River Health Action Plan 40 6.
Expected outcomes of investments and actions proposed 6.1
Investments at all Catchment Action budgets are shown to be very cost effective at reducing pollutant concentrations in Tamar Estuary Zone 1, particularly for enterococci (see Figure 7). There is clear evidence of decreasing returns to scale of investment against this goal with 30 to 55 per cent of the potential decrease in concentration achieved with the first 1.7 per cent of investment ($2 million option). Even with decreasing returns to scale of investment, the $10 million investment option still represents a very cost effective option for reducing in Tamar Estuary Zone 1 concentrations with over 45 per cent of potential sediment reduction, roughly 60 per cent of potential nutrient reduction and over 80 per cent of enterococci reductions achieved for only 8.5 per cent of the $117 million, fully funded investment cost. As was the case with loads, decreases in sediment concentrations in Zone 1 are likely to be significantly underestimated by the modelling. This means that significant decreases in sediments exported to Tamar Estuary Zone 1 can be expected with these investments.
6.2
Impact of Combined System investment recommendations As indicated in section 5.6, the six priority projects recommended in relation to the combined system will lead to more combined system flows going to Ti Tree Bend treatment plant and in turn reduced pathogen loads in Zone Yüklə 1,91 Mb. Dostları ilə paylaş:
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