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Local Representation Advisory Committee Leichhardt

2 August 2016

 

Item No:         LL0816 Item 7

Subject:         No Sewerage Outlets for Sydney Harbour  

File Ref:         16/6014/85504.16         

Prepared By: Richard Jarvis – Manager Parks and Assets, Leichhardt

Authorised By: Peter Gainsford - Director, Major Projects and Engineering  

SUMMARY

During heavy rainfall events stormwater enters the sewerage networks producing flows in the sewerage networks that exceed the capacity of the sewer pipe networks.  Surcharge flows from the sewerage network occur when the network fails to convey all the sewage flow during storm events, commonly occurring as discharges of excess flows from manholes and connections to the sewers.  These discharges can affect connected premises, roadways, and stormwater drainage networks, which also eventually convey the excess sewage flows to Sydney Harbour.

 

The Sydney Coastal Councils Group and Sydney Water share a vision to facilitate a collaborative approach to Integrated Water Management and enhance Sydney’s urban water, sewerage and stormwater network to optimise environmental, social and economic outcomes. Recently a Memorandum of Understanding (MOU) has been developed in consultation with various sections of Sydney Water.  The MOU is intended to establish a framework for the parties to work collaboratively to advance Integrated Water Management and build on the history that the parties share.

 

 

RECOMMENDATION

 

THAT LRAC note the following recommendation:

 

That Council adopt a policy position of opposing the direct discharge of sewerage to stormwater networks or the harbor, and actively support the Sydney Coastal Councils Group and the Parramatta River Catchment Group in their efforts to influence Sydney Water’s policy and practices.

 

 

 

 

BACKGROUND

Leichhardt Council at its meeting of 22 March 2016 (C142/16 NO SEWERAGE OUTLETS FOR SYDNEY HARBOUR) resolved that Council:

1.         Adopt a position opposing any further sewerage outlets in Sydney Harbour.

2.         Write to neighbouring councils including the City of Canada Bay informing them of our position and inviting them to join a campaign against these outlets.

3.         Write to Sydney Water and the relevant State Government Ministers informing them of this position and calling on them to develop alternate solutions.

4.         Receive a report at the May Ordinary Council Meeting on the impact of existing and proposed sewerage outlets in Sydney Harbour. 

5.         Consult the Sydney Coastal Council group on this matter.

 

Council wrote to neighbouring Councils, Sydney Water and Ministers on this matter.  This report details the factors which result in the construction of sewerage outlets into Sydney Harbour, and the current activity of Council’s representative organisations in addressing the issue in order to influence change.

 

During heavy rainfall events stormwater enters the sewerage networks producing flows in the sewerage networks that exceed the capacity of the sewer pipe networks, resulting in surcharges from the networks, commonly at low points adjacent to creeks and waterways.

 

Typical stormwater discharges conveyed by the stormwater networks during storm events also pollute Sydney Harbour and its tributaries.  Councils are improving the water quality of stormwater discharges through the provision and operation of water quality improvement devices.

 

Surcharge flows from the sewerage network occur when the network fails to convey all the sewage flow during storm events, commonly occurring as discharges of excess flows from manholes and connections to the sewers.  These discharges can affect connected premises, roadways, and stormwater drainage networks, which also eventually convey the excess sewage flows to Sydney Harbour.

 

Sewerage outlets to Sydney Harbour and its tributaries are installed by Sydney Water to convey excess sewage flows during surcharge events, such as heavy rainfall storms, from locations of surcharges in the sewerage network, to waterways. Storm flows in sewers dilute the sewerage, and where the storm surcharge flows are diverted to the harbour, they are further diluted at the discharge location. There are also existing surcharge relief connections into the stormwater drainage networks.

 

Hence, during storms or system failures the excess sewage flows now enter Sydney Harbour by various routes, some of which expose the public to diluted raw sewage.  The direct connections installed by Sydney Water reduce the possibility of contact by the public with undiluted sewage flows.

 

The industry’s typical alternative to discharging sewage surcharge flows into channels and waterways is to divert the excess flows to a storage tank, which is pumped back into the network after the storm event has abated.  This solution requires the construction of storage tanks with pumps at the sewerage network low points, which are commonly immediately adjacent to creeks and waterways.  The storage capacity provided may also be exceeded in major events, resulting in smaller volume surcharges to channels and waterways.

 

Achieving the necessary investigations, land acquisitions, design and construction of storage tanks and pumping systems requires considerable lead time, during which the exposure of the public and property to raw sewage may be unacceptable.  For that interim period, the direct conveyance of sewage overflows to the harbour is a possible risk reduction strategy, preferable to overland flows.

 

 

FINANCIAL IMPLICATIONS

There are no financial Implications for Council.

 

 

 

OTHER STAFF COMMENTS

Council is a member of the Parramatta River Catchment Group (PRCG) which is working toward the objective of making the Parramatta River swimmable.  Sydney Water is also a member, and is participating in progress toward that objective.  After recent publicity on sewage surcharge connections to the harbour, PRCG published a press release on the topic which included the following:

 

“In regards to wet weather overflows

-           The wastewater system is designed to transport more than what is needed for dry weather – around four times more. However, during periods of heavy rainfall, stormwater can enter the system through illegal stormwater connections, maintenance holes, or cracked or damaged wastewater pipes. This causes the system to reach capacity and overflow. During wet weather, the quality of an overflow resembles urban stormwater runoff, comprised of a mix of about 80% stormwater and about 20% wastewater.

-           Rather than wastewater overflowing into homes, backyards and other infrastructure, overflows points have been built into the system to direct this excess flow in a controlled way to areas least likely to damage property or cause a risk to public health such as stormwater channels or local waterways.”

 

Inner West Council has also sought advice from the Sydney Coastal Councils Group (SCCG), of which Council is a member.  Sydney Coastal Councils Group has been addressing the discharge of sewage to the harbour and ocean since its inception, and recently prepared a Literature Review and Draft Issues Paper - Sewage overflows management in the Sydney Region - December 2015. 

 

The Draft Issues Paper has identified the following areas as key issues for consideration in determining future options to reduce and mitigate sewage overflows:

• Community and stakeholder perspectives

• Integrated urban water management including Water Sensitive Urban Design

• Addressing illegal connections and faults in the private sewer network

• Issues regarding the current management of stormwater, including the relative contributions to waterway pollution of stormwater and sewage overflows

• Sydney Water’s risk based approach to sewage overflow management which is proposed to replace frequency targets in Environment Protection Licences

• Transparency, communication and engagement between stakeholders

 

Recently a Memorandum of Understanding (MOU) has been developed in consultation with various sections of Sydney Water.  The MOU is intended to establish a framework for the parties to work collaboratively to advance Integrated Water Management and build on the history that the parties share.  A copy of the Literature Review, Issues Paper, and MOU is provided as an attachment.

 

SCCG and Sydney Water share a vision to facilitate a collaborative approach to Integrated Water Management and enhance Sydney’s urban water, sewerage and stormwater network to optimise environmental, social and economic outcomes. The MOU sets out a framework to advance this vision.

 

The MOU is comprised of the Schedule which describes the proposed key outcomes for the participating parties (Key Outcomes) and the Priority Activities to be undertaken by the parties to facilitate achieving the objectives.  The Key Outcomes are those actions which have been agreed to be focused on over a five year period from 2016 – 2021.  “Priority Activities” are to be progressed (as far as possible) within a twelve month period.  It is anticipated that the scope of the MOU will evolve as the relationship matures.

 

 

 

PUBLIC CONSULTATION

No public consultation has been initiated.

 

 

 

CONCLUSION

It is recommended that Council adopt a policy position of opposing the direct discharge of sewerage to stormwater networks or the harbor, and actively support the Sydney Coastal Councils Group and the Parramatta River Catchment Group in their efforts to influence Sydney Water’s policy and practices. Such a policy is a responsible and constructive approach to this matter.

 

This approach recognises the impacts on the community and their needs for immediate relief from wastewater overflowing into homes, backyards and other infrastructure, through the use of overflows points which have been built into the system to direct this excess flow in a controlled way to areas least likely to damage property or cause a risk to public health such as stormwater channels or local waterways.  The approach also seeks to curtail the discharge of untreated sewage into our waterways.

 

 

 

 

ATTACHMENTS

Nil.