Challenge. Provide technical expertise to help protect public health and the municipal water supply from a petroleum hydrocarbon plume that has migrated beneath Qualcomm Stadium.

Solution. INTERA is providing advice regarding additional investigation activities and the effectiveness of a groundwater extraction and treatment system to address petroleum hydrocarbon contamination. Our support includes reviewing all of the responsible party’s reports and work plans and providing comments and recommendations to the City and to the San Diego Regional Water Quality Control Board. INTERA’s findings indicate that the contamination plume continues to migrate toward the San Diego River and is not being fully captured by the extraction well network, and that some petroleum contamination may still be trapped in the finer-grained sediment layers within the aquifer. INTERA is also assisting the City in developing plans to inject treated water (from the groundwater extraction system) back into the aquifer as a means of aquifer storage and future recovery and use. INTERA developed a hydrogeologic conceptual model of the potential aquifer storage based on an analysis of the site geomorphology and an evaluation of numerous borings and well logs. We provided oversight for a field investigation to confirm the location, thickness, and hydrogeologic parameters of the storage zone that included installation of three groundwater monitoring wells. These wells were constructed using specialized, Continuous Multi-level Tubing (CMT) technology that allows monitoring of up to seven discrete intervals within a single borehole. Results of INTERA’s aquifer characterization work are being used by the City of San Diego for further planning on the reuse of the alluvial aquifer as a municipal water supply.