Water table will drop 1m after all

Gosford Council has admitted that water table levels will drop by up to one metre due to its groundwater extraction plans.

The statement in a "fact sheet" comes less than a month after the council claimed that the water table on the Peninsula would not drop with ground water extraction.

Council's manager of asset management Ms Pam McCann told Peninsula News on July 21: "There will not be an overall dropping of the water table."

The statement was made before the development application for the associated water treatment plant went before Council on July 29.

She was responding at the time to claims by the Central Coast branch of the Australian Conservation Foundation that groundwater extraction was "likely to have a substantial effect on water table levels, with consequent effects on bush reserves on the Peninsula".

The fact sheet issued last week stated: "The Woy Woy borefield will extract a maximum of one metre off the top of the groundwater mound, which represents about four per cent of the aquifer's estimated total capacity.

"By limiting the amount of water that's extracted, the longevity and overall sustainability of the aquifer will be protected.

"It will also prevent the ingress of saltwater into the aquifer.

"The Woy Woy borefield is expected to provide an average 3.8 mega litres of drinking water per day or 1387 mega litres per annum after treatment which is enough to supply around 7000 households based on 2006 usage levels."

There are about 16,000 households on the Peninsula.

"One of the main advantages of the Woy Woy borefield is its close proximity to end-users which means distribution of the resulting drinking water will not only be much easier but also more cost-effective compared to other options.

"The quality of the extracted groundwater from the Woy Woy borefield, during extensive monitoring over the past 20 months across five test bores, has proved to be reasonable both in terms of raw water quality and expected yield over time.

"The amount of water that can be extracted from the Woy Woy-Umina aquifer each year will be decided by the NSW Department of Natural Resources (DNR) which controls all groundwater resources in the State.

"Once the necessary water treatment plant at Woy Woy and underground pipe distribution network in Woy Woy and Umina have been installed and commissioned, it's expected the DNR will grant Gosford Council a 12-month Test Pumping Licence.

"This license will require Gosford Council to provide extensive daily, weekly and monthly monitoring data about ongoing water levels, impact on flora and fauna as well as geological factors and rainfall.

"The DNR will use this data to decide how much water can be extracted from the aquifer each year in the medium to long-term.

"Through this extensive monitoring, Gosford Council and the DNR can make sure that if the aquifer comes under stress or the water levels drop, the amount of water being extracted can either be reduced or, if necessary, stopped altogether until the aquifer has been naturally recharged through rainfall.

"A total of 6.5 kilometres of pipeline also needs to be installed to pump the raw groundwater from the bore holes to the water treatment plant.

"This pipeline network will run from the 14 production bores to the Woy Woy Works Depot on Ocean Beach Rd.

"These pipes will be installed underground, in road reserves and other lands owned by Gosford Council.

"In addition, 13 street kiosks will cover the above ground pipe work that's needed for each bore hole.

"The majority of these kiosks will be located in existing parks and reserves to minimise the impact on local residents.

"These kiosks look very much like the street cabinets used to enclose electrical transformers.

"Adjacent to each bore head kiosk will be a switch cabinet assembly similar to those used at most sewage pump stations.

"This pipeline installation program will take approximately six months, commencing in October.

"The Woy Woy Groundwater Project is expected to begin delivering drinking water to Peninsular residents by April.

"On certain days some residents will get mostly treated groundwater and at other times they will received a combination of water from the Somersby and Woy Woy water treatment plants.

"Some residents may never receive treated groundwater, especially if they live in the south of the Peninsula where they'll always receive water from the Somersby water treatment plant."

The fact sheet and other information about the Woy Woy groundwater project are available from Council's website and council offices.

Fact sheet, August 17 Pam McCann, Gosford Council