SciDev was approached to Design and construct a Temporary Water Treatment Plant (TWP) to treat contaminated groundwater of up to 200mg/L TSS (Total Suspended Solids) at a continuous treatment flow rate of 4lps (litres per second). Testing and commissioning were done in accordance the Dewatering management plan, Enviro consultant findings, Randwick Council development application consent and Council discharge permit.
Construction of Stage 2 Building basement was expected to encounter contaminated groundwater issues comprising of chlorinated solvents (Tetrachloroethene (PCE), Trichloroethylene (TCE), chloroform, 1,2- Dichloroethane (DCE), Total Recoverable Hydrocarbons (TRH), BTEX. These higher metals concentrations are measured above ANZG Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZG, 2018) as per an assessment conducted by an environmental consultant.
Dewatering activities were required to lower groundwater levels to allow basement construction activities to occur, therefore requiring pumped water to undergo treatment to below Council agreed discharge criteria, to allow for subsequent disposal to stormwater.
The area of the basement is approximately 5,485m2 and an initial groundwater thickness of up to 2m is expected during the dewatering phase. Once this ‘slug’ of water has been dewatered, there will be an ongoing requirement to maintain groundwater levels beneath basement construction depth to allow for works to progress. A WTP was required for groundwater pumped from within this basement footprint and captured stormwater within the site.
Summary
Treat contaminated groundwater with total suspended solidsof up to 200mg/L in accordance with AUS/NZ Guidelines.
3-stage process including pre-treatment – consolidation, pH correction, coagulation, and flocculation, clarification through a Lamella Plate Separator and filtration via staged physical, cation ion exchange (CIX).
This is the only PFAS water treatment plant of this scale, in Australia that currently treats to beneath the 99th percentile level of ecological protection under the Australian and New Zealand Environment and Conservation Guidelines (ANZECC) for discharge to the environment.
The plant’s construction and commissioning were completed in 14 days ahead of the contractual agreement.
The water treatment plant is required to operate 24/7 and process 4L/second.
