For over 10 years, Stratus personnel have been providing environmental consulting services as part of the City of Sacramento's On-Call Professional Services for Environmental Site Assessments, Remediation Services, Hazardous Materials Surveys, and Laboratory Analytical Services contract. Our work included the North Area Corporation Yard (NACY) which had soil and groundwater contamination, primarily diesel fuel, from a leaking underground storage tank (UST) system.

 

A remediation plan was prepared and approved by the Regional Water Quality Control Board (RWQCB) and included excavation and bioremediation of impacted soil; treatment and disposal of groundwater encountered during the excavation; destruction of 19 existing monitoring wells and the installation of 5 new monitoring wells; the installation of a horizontal well system within the excavation for future treatment if required; and the replacement of the treated soil into the excavation as backfill. Stratus personnel involvement included:

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• preparation of technical plans and specifications;

• participation in pre-bid and pre-construction meetings;

• review and response to contractor requests for information both during and after the bidding process;

• review of contractor submittals; preparation of plans for the destruction and installation of groundwater monitoring wells and implementation of the well destruction plan;

• contractor oversight during the excavation of 40,000 cubic yards of soil to include screening, sampling, and segregation of diesel impacted soil; and

• participation in project meetings; and the preparation of progress reports.

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Stratus personnel reviewed the remediation plan and groundwater monitoring program and identified cost saving changes. These included the use of a flame-ionization detector for real-time field screening of soil, rather than collection and off-site laboratory testing of samples. This allowed the contractor to maintain continuous excavation rather than having to stop and wait for results.

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Stratus staff recommended changes to the groundwater monitoring program to reduce the number of constituents analyzed and the number of wells sampled. The groundwater monitoring recommendations were approved by the RWQCB and implemented.

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Additionally, Stratus personnel collected site specific values and re-evaluated the remediation goal. The re-evaluation modeling determined that an increase in the goal from 83 milligrams per kilogram (mg/kg) to 1,000 mg/kg for diesel would be protective of groundwater. The recommended change in the remediation goal was approved by the RWQCB. To date the soil has been treated, the excavation has been backfilled, the monitoring wells have been destroyed, the site has been restored; and the project has received a “No Further Action” status.

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