Tetra Tech, a principal partner in the joint venture Tech2 Solutions (T2S), working as part of a joint venture (SES-TECH), provided broad-based environmental remediation services to the Naval Facilities Engineering Command Southwest (NAVFAC SW) under a $30M Fixed-price Remedial Action Contract (FRAC). Site remediation scope under the FRAC, included project management, engineering, construction, procurement, program support and administration on 62 subprojects within 8 western U.S. states. We managed an integrated program with multiple individual area remediation projects; performed soil and groundwater investigations and remediation; decontaminated and demolished facilities; implemented comprehensive surface water monitoring and storm water controls; and removed unexploded ordinance.
This contract highlights an example of our experience and past performance in remediation of a hexavalent chromium (Cr+6) plume at the Naval Air Station North Island (NAS NI) Operable Unit 20 (OU20). On this $2.45M time-critical subproject we performed groundwater monitoring, remedial site investigation including contaminant plume modeling, remedial system design, bench and pilot scale treatability studies and remedial action implementation for a 55-acre trichlorethylene (TCE) groundwater plume inclusive of a 7-acre Cr+6 plume.
NAS NI is an active military base on the northern end of the Silver Strand Peninsula, separating San Diego Bay from the Pacific Ocean. The base has supported naval air and fleet operations since the 1920s. The western portion of the base is occupied by NAS NI and the eastern portion by Navy Base Coronado. Historical fleet maintenance activities have impacted soil and groundwater in multiple stacked aquifers with Cr+6 and TCE. These contaminants of concern were migrating beneath operating facilities towards San Diego Bay.
The NAS NI OU20 project was a comingled Cr+6/VOC groundwater plume (55-acre TCE plume/7-acre Cr+6 plume), located beneath multiple operational and sensitive facilities. It was considered a CERCLA time-critical remedial action (TCRA) because of migration towards sensitive off-site receptors. We performed a groundwater investigation to define the evolving extent of contamination. Following groundwater monitoring, we performed bench testing of proposed remedies and pilot field testing of biological reduction to determine applicability and optimize the remedial system design. Following treatability confirmation, we implemented the full-scale field remediation.