Optimization Evaluation of Yermo Groundwater (Operable Unit 1) and Technical Support, Marine Corps Logistics Base (MCLB) Barstow, CA.

This task order was to perform an optimization evaluation of the Operable Unit 1 (OU 1), Yermo Groundwater; pilot testing and reporting at OU 1 and CERCLA Area of Concern (CAOC) 16; and a base wide programmatic review of installation restoration sites. Additionally, GCE conducted an SVE data gap investigation at Yermo Annex CAOC 16 and performed an emerging contaminant (PFAS) site investigation at the Nebo Main Base and Yermo Annex.

GCE reviewed the data from existing site investigations performed at Operable Unit (OU) 1, Yermo Groundwater, as well as Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) Area of Concern (CAOC) 16 as it relates to contaminated soil. This evaluation ultimately aided in optimization of treatment systems to reduce the time necessary to achieve remedial goals for the contaminants of concern (COCs). The optimization evaluation was conducted in accordance with the NAVFAC Guidance for Optimizing Remedial Action Operation.

Pilot Testing and Reporting at OU 1/CAOC 16

Based on the evaluation and recommendations presented in Optimization Evaluation, GCE conducted a pilot test of recommended optimization techniques at OU 1/CAOC 16. GCE conducted a combined small-scale soil vapor extraction (SVE) optimization study and limited in situ chemical oxidation (ISCO) testing, at Yermo Annex – OU 1 in the vicinity of Building 573.

Basewide Installation Restoration Program Desktop Review, Site Management Plan Production, and Underground Storage Tank Program Review

GCE conducted a complete review of the Installation Restoration Program (IRP) for MCLB Barstow. This included a review of all sites discussed under OUs 1 through 7. The documentation associated with this effort was presented in a Site Management Plan (SMP). For those sites closed with land use controls (LUCs) and those sites that remained open and required remedial action, GCE prepared a summary of the “next steps.” The SMP included a copy of any relevant LUC inspection checklists/forms.

Emerging Contaminant Investigation for Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS), Nebo Main Base and Yermo Annex

PFAS were detected in shallow groundwater at the Nebo Main Base and Yermo Annex above the U.S. Environmental Protection Agency’s (US EPA) lifetime health advisory levels for PFAS. As a result of these detections, an emerging contaminant investigation was performed to delineate the vertical and horizontal extent of elevated PFAS contamination, determine the source area(s) for both soil and groundwater (if possible), identify potential receptors, and recommended response actions. Only two PFAS were the focus of the investigation: perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). A recommended step included evaluating any available site or local data on other PFASs that may assist in understanding the potential risks associated with PFOA and PFOS, and whether these additional PFAS should be included or excluded from future data collection efforts.