Bold brick pit drainage plan

MOST of an estimated 42 million litres (42 megalitres) of water in the Kirrawee brick pit is destined to be "put down the drain" when work starts on the $35 million development.

Millions of litres: Chris Ryan is the project director of  the South Village development planned for Kirrawee brick pit. Most of the water at the site (seen in background) will be pumped into stormwater drains. Picture: Lisa McMahon

Millions of litres: Chris Ryan is the project director of the South Village development planned for Kirrawee brick pit. Most of the water at the site (seen in background) will be pumped into stormwater drains. Picture: Lisa McMahon

Water supply: Flying foxes in bushland at Kareela.

Water supply: Flying foxes in bushland at Kareela.

Approval has been sought to pump the contents of the brick pit into nearby stormwater pipes, which discharge into the Georges and Hacking rivers.

Property company Payce, which is developing the urban renewal project, South Village, defended the plan.

"Other uses for the water have been ruled out due to a range of reasons, including the logistics and infrastructure required to transport the water," a spokesman said.

The proposed dewatering process is among revised plans submitted to the Planning Assessment Commission.

A consultant's report said the brick pit was about 215 metres long, 90 metres wide and up to six metres deep.

A 2006 survey estimated the water volume to be 42,717 cubic metres (42.7 million litres or 42.7 megalitres).

"Water quality presents no concerns in its present state and as such it is considered reasonable to allow discharge to the stormwater system provided controls are put in place and contingency plans are initiated in the event the present water quality changes," the report said.

The report said the existing stormwater drainage network was the most appropriate dewatering method and there was potential to discharge into two separate waterways.

Discharge points would be Dents Creek, which flows into the North-West Arm of Gymea Bay, and Oyster Gully, which feeds into Oyster Bay, on the Georges River.

The report said one pump operating at 25 litres a second from 7am to 5pm would move 900,000 litres a day. At that rate, the pit would be drained in 47 days by one pump or 24 days with two.

If discharge was permitted 24 hours a day, the operation could be completed by two pumps in 10 days.

The report said discharged water would meet approved guidelines and "adequate monitoring" would ensure a low risk to the surrounding environment was maintained.

Flying foxes to get pond for drinking 

PROVISIONS will be made for flying foxes from the nearby Kareela colony, which drink from the brick pit.

Protecting the flying foxes was ‘‘critical’’ in the dewatering plan, a biodiversity plan said.

Some of the brick pit water will be pumped into a temporary pond on site until a permanent water feature is created in a new public park.

The report said an 800-square-metre surface area of water was needed, in an elongated shape, ‘‘to accommodate the ‘skimming’ drinking behaviour of the grey-headed flying-fox’’.

South Village project director Chris Ryan said it remained to be seen whether the bats would continue to use the site after development.

‘‘Who knows?’’ he said. ‘‘The bats don’t live here, they drink here. There will be a facility for them if they ... keep coming.’’

What do you think of the drainage plan and temporary pond for bats at the brick pit?

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