Following on from the successful construction and commissioning of the Coppabella Water Treatment Plant Aurizon Holdings Limited engaged Dowdens Pumping & Water Treatment [Mackay & Brisbane Branches] to deliver a much needed Sewage Treatment Plant (STP) Upgrade at their Coppabella Township, located on the Goonyella Rail Corridor (the world's largest metallurgical coal rail system) - 159 kilometres South West of Mackay, QLD. The Coppabella STP Upgrade project entailed the addition of an Ultra-Filtration (UF) 'Polishing' Plant onto the existing STP. Dowdens new UF 'Polishing' Plant can produce up to 180 kL/day of treated Class A effluent.
The township of Coppabella was primarily designed and built to service the junction of two railway lines (one from Goonyella Coal Mine and one from Saraji Coal Mine) and to provide accommodation to the regions coal mine workers in work depots. The town is wholly owned and operated by Aurizon Holdings Limited and contains: stations, residences, single-quarters, work depots, hotel, a shop, swimming pool, football oval, caravan park, school, ambulance, fire brigade, the recently completed Dowdens whole-of-town Water Treatment Plant and of course the upgraded Sewage Treatment Plant which is now capable of producing 180kL of treated Class A effluent per day for above ground irrigation applications. The local Coppabella Golf Course is one area where this treated effluent is used for irrigation.
After successfully completing various projects for Aurizon Holdings Limited, Dowdens won the tender to provide the process design together with equipment supply, civil construction, installation, commissioning and training for the STP plant operators. The construction phase of the project began with extensive civil works being undertaken to raise the ground level for the new STP components. The pre-existing STP has historically been subject to flooding during heavy rainfall events due to the sites proximity to the local creek. Upon surveying the sites substrate a water table was discovered 1m below ground level.
Working with local Civil Engineers Cardno a substantial foundation was designed / laid to ensure the new buildings, plant components and 4,000 tonne water tank would be stable and remain above the flood plain even during heavy rainfall. Once foundations were laid Dowdens began construction of the 400,000L lined stainless steel water tank, new building to properly house the STP process equipment, an operators office, laboratory facilities and a back-up generator used to power the entire STP in the event of power loss.
After extensive effluent testing and thorough examination of the existing STP process a UF 'Polishing' Plant was designed by Dowdens inhouse Water Treatment Engineering Dept. capable of processing up to 180kL of partially treated sewage effluent per day. The partially treated sewage effluent was rated as Class C and needed to be treated to an acceptable level (Class A) to then be used for above ground irrigation. This treatment process consists of three stages of filtration and sterilisation, including UF. This three-stage process runs as follows:
When the treated effluent arrives in the 400kL stainless steel tank a recirculation system pumps it through a chlorine analyser and back to the treated effluent tank. The chlorine analyser then controls the residual free chlorine level in the treated water and will start / stop a chemical dosing pump as required to maintain the pre-set residual free chlorine level.
Each of the GMF, UF and ACF processes are periodically backwashed and cleaned, with residual waste being fed to a nearby buffer dam where chlorine is allowed to dissipate. Based on the level in the buffer dam and the level in the treated effluent tank, the water may then be returned to the pump station at the front of the STP for reprocessing.
With a history of successful installations over the past 20 years throughout the Queensland Mining Sector Dowdens Pumping & Water Treatment have the ability to expertly design / manufacture / install and commission specialised pumping and water treatment solutions that are built primarily in-house & onsite to client's specific unique requirements. The Coppabella STP Upgrade project is yet another example of Dowdens unparallelled capability to deliver specialised long-term engineered fluid handling solutions from project inception through to final commissioning / handover.