EISB Remedy Implementation and Performance Assessment
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Project Objective

The owner of a former waste control site (WCS) located in Bellevue, Western Australia was pursuing the remediation of the site from groundwater contaminants of concern (COC).

Geosyntec’s Scope of Services

Geosyntec Consultants Pty. Ltd. (Geosyntec) was engaged to design, implement, monitor and validate an enhanced in-situ bioremediation (EISB) remedy in the off-site remediation area (OSRA) of the WCS. The overall objective of the project was to design and implement an effective remediation program that permanently reduces the concentrations of the COCs, primarily trichloroethene (TCE) to the appropriate risk-based criteria (at a minimum) in a cost-effective, sustainable and timely manner consistent with the expectation of community and relevant stakeholders.

The project consisted of professional services to i) complete an additional site delineation program to determine the extent of area requiring treatment and to refine the EISB design, ii) perform laboratory bench-scale testing to assess the potential for EISB to effectively treat the target COCs in the OSRA, iii) identify appropriate validation metrics for the remedy and develop a Remediation Action Plan (RAP) for review and approval by the accredited contaminated sites Auditor, and iv) implement the EISB remedy within the OSRA at the site. Preliminary work for the EISB remedy included installation of additional monitoring wells within the two treatment areas (i.e., primary and secondary treatment areas) of the OSRA, collection of baseline soil samples, and collection of baseline groundwater samples from the newly installed and existing validation monitoring wells. Approximately 320,000 liters (L) of electron donor (emulsified vegetable oil) and 80 L 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 COCs in groundwater in these areas.

Following the EISB injection activities, bi-annual groundwater sampling of the validation monitoring wells began and continued for a period of roughly 2.5 years. EISB performance was assessed by monitoring a suite of groundwater parameters including volatile organic compounds, total organic carbon, dissolved hydrocarbon gases, volatile fatty acids, microbial population, and geochemical data.

Notable Accomplishments

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 of the validation monitoring wells. By the end of the performance monitoring program, the remediation criteria or equivalent metric had been achieved for both treatment areas and the OSRA was considered remediated and validated.

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Project Summary

  • Location: Perth, Western Australia
  • Client: Confidential Client
  • Project Practice Areas: Water & Wastewater
  • Type of Facility: Perth – Western Australia
  • Services Provided: Site delineation, EISB bench-scale testing, Remediation Action Plan development, EISB remedy implementation and performance assessment
  • Type of Work: EISB
  • Governing Regulation: State and local