Client
Confidential
Location
Bellevue, Western Australia
Key Services
Groundwater Remediation, Bioremediation
Outcome
The owner of a former waste control site in Bellevue, Western Australia, was pursuing the remediation of groundwater contamination.
Geosyntec was engaged to design, implement, monitor, and validate an enhanced in situ bioremediation (EISB) remedy at an off-site remediation area (OSRA). The objective of the project was to design and implement an effective remediation program to permanently reduce concentrations of contaminants, primarily trichloroethene (TCE), to the appropriate risk-based criteria (at a minimum) in a cost-effective, sustainable, and timely manner consistent with the expectations of the community and relevant stakeholders.
Our practitioners provided professional services to complete an additional site delineation program to understand the extent of the area requiring treatment and to refine the EISB design. We then performed laboratory bench-scale testing to assess the potential for EISB to effectively treat the target contaminants, identified appropriate validation metrics for the remedy, and developed a Remediation Action Plan for review and approval by the accredited contaminated sites Auditor. We also implemented the EISB remedy within the OSRA. Preliminary work for the EISB remedy included installing additional monitoring wells within the two treatment areas of the OSRA, collecting baseline soil samples, and collecting baseline groundwater samples from the newly installed and existing validation monitoring wells. Approximately 320,000 litres of electron donor (emulsified vegetable oil) and 80 litres of a commercially available dechlorinating bacterial (bioaugmentation) culture (KB-1® Plus) were injected into the subsurface within the two treatment areas to promote in situ biodegradation of the contaminants in groundwater in these areas.
Following the EISB injection, biannual groundwater sampling of the validation monitoring wells began and continued for roughly 2.5 years. EISB performance was assessed by monitoring groundwater parameters, including volatile organic compounds, total organic carbon, dissolved hydrocarbon gases, volatile fatty acids, microbial population and geochemical data.
Geosyntec obtained Auditor approval, meeting the overall project objectives. Changes in groundwater geochemistry and microbial population provided evidence that biologically active and reducing zones had been established in the treatment areas, and TCE decreased to concentrations that were below the remediation criteria at all the validation monitoring wells. By the end of the performance monitoring program, the remediation criteria or an equivalent metric had been achieved for both treatment areas and the OSRA was considered remediated and validated.
