Bootawa Dam Water Treatment Plant, Australia


The Bootawa Dam Water Treatment Plant (WTP) in Taree, New South Wales (NSW) was officially opened in November 2010. The facility was built next to the Bootawa Dam which is the main water storage facility for the Manning-Great Lakes region in NSW.

Construction of the plant was started in 2007 by the water utility company MidCoast Water. Total investment in the project was $82m. The WTP has a capacity to process 60m litres of water a day, with provision to expand to 75m litres in future.

Purpose of project

The new plant was built to address the long-term issues affecting the Manning Water Supply. The quality of water was being affected by elevated levels of iron and manganese. In addition, algae and dirty water was present in the catchment.

"The Bootawa dam features several structures which are used to pre-treat water."

Pre-treatment

The Bootawa dam features several structures which are used to pre-treat water. A floating mechanical de-stratifier located at the deepest part of the dam at 23m helps improve the quality of water.

The de-stratifier works by pulling surface water down and mixing the different layers of water. This action generates water which has a more even temperature thereby improving the overall quality.

Water is passed through an intake tower consisting of several screens, before it is piped to the treatment plant.

Treatment

Water received at the WTP passes through the filtration area consisting of filters made of polymer membranes. The fine straw-like fibres of the filters remove tiny impurities which are less than 0.2 microns in size. The membranes also remove micro-organisms such as cryptosporidium and giardia. Use of polymer membranes eliminates the need to add chemicals to water. The filters are backwashed every 30 minutes and the backwashed water is fed back into the plant for processing.

The filtered water is sent to the sealed ozone contact tank where it is mixed with ozone. This process removes any compounds produced by algal blooms. Presence of such compounds can cause taste or odour problems. Treating with ozone also helps in disinfecting the water.

The next step in the purification process includes passing the water through the biologically activated carbon (BAC) filter. The BAC filter consists of activated carbon which absorbs any final contaminants present in the water. It also removes residual taste or odour.

The final step in the treatment process is feeding the water into the chlorine contact tank. Chlorine is added to water in the tank to remove any remaining bacteria. Small traces of chlorine are left to ensure that water remains bacteria free until it reaches consumers.

The treated water is then sent to the treated water reservoir where small quantities of soda ash and fluoride are added. Soda ash is added for pH correction and fluoride is added for dental health.

Facilities

A raw water balance tank is part of the plant and gets water either directly from the Manning River or the Bootawa Dam.

"The treated water is distributed through MidCoast Water's pumping station 2B."

Water is piped to the WTP from the raw water balance tank which helps in ensuring flexibility of water supply.

A large inlet line, which can be operated automatically or manually, is used to pipe water.

The treated water is distributed through MidCoast Water's pumping station 2B. The pumping station consists of seven pumps to supply water across MidCoast Water's network.

From the pumping station, water is sent through the reticulation system which carries water to more than 30 reservoirs and then onto homes and businesses.

Technology

The plant has been designed to be fully automatic. It is monitored and run by advanced supervisory control and data acquisition (SCADA) technology.

Key players

The architects of the WTP were EJE Architecture. The engineering consultant was Worley Parsons.

The $49.5m construction contract was awarded to the Reed Group. It was responsible for the design, construction and commissioning of the plant. The company carried out various civil works at the site, including construction of reservoirs, tanks, treatment units, amenities, drainage and pumping stations.

Weir Minerals supplied a pump package for the plant. Thompsons, Kelly & Lewis supplied centrifugal pumps for the project.