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SURFRIDER NORTHERN BEACHES NEWSLETTER - July 2000

SEWAGE OVERFLOWS DURING RAIN PERIODS

Sewage mains are laid underground, usually following natural gradients until they level out at sea level. Often, they are laid in creeks or gullies, excavated below the creek bed, carrying sewage from more elevated suburbs down to the streets at lower levels.

During periods of rain, water seeps into the mains through joints (the pipes are only butted together) and causes cracks or breaks in the pipes. The volume of leakage into the pipes is often so great that the pipes become full of diluted sewage and cannot carry the volume. To avoid the sewage "backing up" in the pipes, overflow outlets have been designed and built into the system and the diluted sewage overflows into creeks, gutters storm water canals, lagoons, beaches and surf.

This is the reason why the public are advised not to surf for 3 days after heavy rain - to give the overflows time to flow away, degrade and their content of bacteria, viruses etc. to decompose.

What a pathetic system - might have seemed OK in the 19th century but it is completely unacceptable in the 21st!!

However, there is no easy solution …..

Can the old (and not so old) sewerage lines be lined internally so they don't leak?

Not practical or possible yet.

Can the overflows be collected and stored so they don't end up in lagoons and surf? (Lagoons at Manly, Curl Curl, De Why and Narrabeen are great collectors of sewage overflows. Elsewhere it gets to the surf via storm water pipes.)

Well, yes they can, and that is what is being done with the North Side Sewage Storage Tunnel, being excavated from North Head Sewage Treatment Works to near Clontarf at Middle Harbour. The Tunnel will collect and store overflows (commonly called "wet weather flows") and then release these to the Sewage Treatment works at a rate the Treatment Works can process. At times of prolonged heavy rain the capacity of the Tunnel will be exceeded and the diluted sewage will pass untreated to the ocean outfalls (so you will still be surfing with "shit").

Many readers would have learned of the Northside Sewage Storage Tunnel through reports in The Manly Daily. There are numerous controversies and problems and a budget overrun from $300 million to $450 million.

How many sewage storage tunnels would be needed to keep sewage overflows out of Manly, Curl Curl, Dee Why and Narrabeen lagoons and out of gutters and storm water pipes which discharge directly to beach and surf?

Sewage from almost all of Sydney, from the far western suburbs, beyond Parramatta, Blacktown etc., drains eastwards to the three major outlets - North Head, Bondi and Malabar and with Sydney's population increasing faster than any other capital city, the problems will only get worse.

There is no easy fix and we will discuss some possibilities in our next Newsletter.

WARRIEWOOD SEWAGE TREATMENT WORKS

I commenced campaigning to improve the performance of this operation in the late 1980's and after I formed the Northern Beaches Branch of Surfrider in 1992, Rex Campbell and more recently Paul Maddock have campaigned long and hard and, at last, successfully.

As local surfers and beach users well know, the plant malfunctioned periodically, resulting in the release of untreated or partially treated sewage, especially at times of rain, directly into the surf at the cliff face outlet at Warriewood.

Dependent of wind, swell and currents, it was carried north to Warriewood and Mona Vale, or south to Turrimetta and North Narrabeen.

Rex has written to Sydney Water (Operators of the Plant), met with staff, and called public meetings in an effort to force improvements. Over the years, the number of malfunctions and bypasses have been reduced, and in 1999, Sydney Water announced it would:

1. Construct a large retention pond to hold wet weather flows (which were previously released untreated) and after the rain event had concluded, to release through the plant.

   The capacity of the pond is not adequate to hold flows after prolonged periods of wet weather, but it is a big improvement.

   The retention pond is scheduled to be operating before year end 2000.

2. UV purification: An ultra violet "sterilisation" unit is being installed to irradiate treated effluent and reduce the concentration of viruses and bacteria released into the surf. Under normal conditions the effluent should meet national health guidelines for recreational water (that is, it should be clean enough to swim in, before it enters the ocean).

   This process is also scheduled to be operating in 2000. We look forward to seeing how well it works.

SEWAGE OVERFLOWS INTO NARRABEEN LAGOON AND NORTH NARRABEEN SURF BREAK

During a meeting I attended with Sydney Water about 1992, Sydney Water(then the Metropolitan Water and Sewage Board) showed a map of all the sewage overflows in the Sydney Basin. There are many hundreds.

As I recall there were 7 or 8 overflows directly into Narrabeen Lagoon and another 7 or 8 into the creeks which feed the Lagoon.

During 2000/2001 Surfrider plans to investigate:

1. The exact location of the overflow points
2. How often and to what extent they operate
3. The quality of the Lagoon water (during wet weather when the sewage overflows would operate) at the Lagoon entrance where it enters the surf
4. The quality of the water in the surf break

Currently Beach Watch, as part of their program, sample the surf at all Sydney Beaches from Cronulla to Palm Beach [ ] days per week. Samples are usually taken from the lifeguard flag areas, which is appropriate for the general public, but not necessarily appropriate for boardriders who often surf well away from the flags.

At North Narrabeen, boardriders surf in the Lagoon outflow at run out tides.

Other Breaks.

Similar situations also need investigating at most other Northern Beaches Surf Breaks such as Queenscliff, Curl Curl, Dee Why, Long Reef where there are Lagoon entrances, and at other breaks adjoining storm water outlets.

SEWAGE OVERFLOWS AT "THE BOWER" AND "WINKI POP"

Surfers might have thought that with the commissioning of the offshore sewage outlets some years ago, that pollution at The Bower and Winki Pop had been overcome (at least to some degree).

Not so!

Two sewage overflows continue to operate at times of wet weather flows (rain periods). A sewage line runs from the Manly - Queenscliff area to the sewage pumping station at Shelley Beach (near Le Kiosk restaurant). The pumping station normally pumps sewage up to the North Head Treatment Works and then to the offshore outlets (about 2km offshore).

At times of heavy rain, storm water leaks into the sewage lines, which cannot handle the increased volume and overflow is released at two points:

1. through a pipe running underneath the headland and discharging directly into a cliff face outfall at Winki Pop; and
2. by an overflow near Shelley Beach at the small swimming pool beside the walkway.

Peter Barr has been a member of a community/Sydney Water committee working on the problem for some time, and has recently been joined by Brendan Donohoe our Northern Beaches President.

Short term solutions are: