A Wingecarribee Shire Council project to replace old and damaged sewer mains has seen a massive reduction in wastewater discharged into local waterways.
More than 180 million litres of wastewater per year is expected to be reduced from the Bowral catchment area as a result of a $1.65 million joint renewal project with WaterNSW.
Council’s Water Asset Coordinator, Stace Lewer explained the significance of the completed project.
“Back in 2013 Council put forward a proposal to WaterNSW (then Sydney Catchment Authority) for funding to renew 5.4 kilometers of old sewer mains around the Bowral area,” he said.
“The project consisted of renewing and replacing older sewer pipes which weren’t performing at their best anymore,” Mr Lewer said. “By fixing these pipes we anticipated that we would prevent more than 137 million litres of water from infiltrating our Bowral sewerage network.”
Infiltration is where water enters sewer pipes through cracks, breaks and other defects. These cracks and breaks may occur as a result of ground movement, faulty joints or even tree roots in search of water.
By keeping infiltration flow at a low level it reduces pressure on the sewerage network and wastewater treatment plants. High infiltration flows are particularly evident in times of high rainfall.
However data collected both prior and after the completion of the project suggest the actual amount of infiltration reduced as a result of the project was 184.5 million litres per year.
“This is a significant reduction of water entering our sewerage network,” Mr Lewer said. “And this reduction has resulted in multiple benefits.”
Other anticipated benefits include a significant reduction in CO2 emissions and nutrient load to the environment.
“Based on the success of this project we hope other grant opportunities become available to further improve the delivery of wastewater services across the Shire,” Mr Lewer added.
The $1.65 million project was delivered in conjunction with a $750,000 grant funded by WaterNSW. This grant is part of the NSW State Government’s Healthy Catchments Strategy Priority Pollutants Program.
Other Council initiatives implemented to reduce infiltration include sewer hydraulic modelling, carrying out regular inspections of manholes, conducting smoke testing to look for visible signs of defects and using CCTV cameras to physically travel and film the condition of underground pipes.
The Bowral catchment area consists of 103 kilometres of gravity sewer main, 15 Sewer Pumping Stations, 2,911 manholes and 4,265 sewer connections.