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CIVIL & ENVIRONMENTAL

US Navy - SWDIV
Remedial Design and Remedial Action Implementation

Project Background
ERRG was awarded this firm, fixed-price EMAC contract to perform a remedial design (RD) for trichloroethylene (TCE)-contaminated groundwater at the Tustin Former Marine Corps Air Station. The base contract is over 80% complete, and ERRGwas awarded two additional modifications: the first modification expanded the scope of the remedial design to include TCE-contaminated soils, and the second modification added implementation of the remedial design/remedial action (RD/RA design/build), for both soils and groundwater. The remedial alternative selected for the project was "hydraulic containment with soil hot spot removal."

ERRGs initial strategy in winning the competitive bid for the project was to utilize the already-proposed remedial design for the site (from the Feasibility Study), perform a value engineering analyses to identify any needed modifications, and then adjust final design parameters based on site-specific hydrogeologic testing and local geology/hydrogeology. The approach ensured that design work was not repeated, and that Navy funding could be used in the most efficient manner.

The original scope of work included only generation of a RD for groundwater at one base Operable Unit; however, the scope of work was expanded to include not only the RD, but also the RD/RA for groundwater, and for soils at an adjacent Operable Unit.

As part of the project, the ERRG team also performed a pre-RD hydrogeolgic field investigation (well installations and step-drawdown testing), to evaluate site-specific hetereogeneity, a challenge to the RD. Subsurface conditions at the site included three interconnected water bearing zones, clay lenses, and other features which posed challenges to designing a groundwater treatment system. The field investigation was able to glean valuable site information which led to the recommendation not to perform additional modeling.

As part of the project, the ERRG team recommended certain design features to the Navy, which allowed for remote monitoring and control of the site treatment system through a web page. The design required use of special hardware, and construction techniques, but still complied with the budget established for the project. Engineering analyses also generated various other options for reducing long term O&M funds, and took into consideration some of the political constraints which faced the project (e.g. nearby sites were already transferred to non-Navy parties, and so treatment system components were limited to certain geographical areas).