Growth Built engaged NPE to provide a complete dewatering and groundwater treatment solution to facilitate the construction of an 11-storey mixed-use building overlaying a four-level basement car park in Shell Cove, NSW. The water treatment system needed to successfully remove high levels of iron, manganese, and other dissolved metals from the groundwater to non-detectable/ultra-low levels to achieve compliance requirements with Shellharbour City Council, Water NSW and NSW-EPA before discharge. Additionally, the water had a high total hardness. Treated water is discharged into the local stormwater network, which drains into the Shell Cove Marina, a receptor with high ecological, aesthetic and economic value. Fe and Mn oxidise upon exposure to air and form insoluble coloured metal oxides. The high dissolved iron and manganese levels resulted in solid deposits within pipes that led to blockages and unwanted staining. In addition, Fe and Mn can be bioaccumulated and, in high concentrations, can cause damage to aquatic organisms.

NPE deployed its pumping, dewatering, and groundwater treatment capabilities. A combination of pH-targeted precipitation and catalytic oxidation media was utilised to remove iron and manganese. The complete treatment train included retention tanks, chemical dosing units (to effect pH correction, coagulant, and flocculant addition), clarifier units, catalytic oxidation media filters, sludge thickening tanks and discharge water quality monitoring probes. Telemetry and remote monitoring capabilities were huge components of the treatment train, enabling timed human intervention to institute corrective measures to ensure compliant treated water discharge.

The current water treatment setup has successfully treated the results, indicating that iron, manganese, and other metals are being removed to levels below the detection limit.