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Comprehensive Site Assessment and Remediation

Former Fueling Facility, Oceanside, CA

Client:  City of Oceanside Public Works Department

TGI has provided environmental site characterization, risk assessment, remedial action assessment and remediation services for a UST release that occurred at the site in the past.  The Site was previously a fueling facility for the City of Oceanside and is situated near the Pacific Ocean and the San Luis Rey River.
TGI performed a phased environmental site assessment at the Site between late 1999 and 2002.  The scope of initial assessment included drilling and sampling of exploratory borings, field screening and laboratory testing of soil and groundwater samples for the presence of petroleum hydrocarbon compounds and preliminary assessment of the geologic, hydrologic and hydrogeologic setting of the site.  After soil and groundwater contamination was identified. subsequent phases of investigation were performed to assess the horizontal and vertical extent of contaminated soil and groundwater, evaluate the geologic and hydrogeologic characteristics of the Site, and assess potential migration pathways for the contamination associated with past releases at the Site in order to evaluate the need for and technical approach to corrective action.  Monitoring/recovery wells have been to depths of up to 120 feet, soil and groundwater sampling and aquifer testing.  All work has been performed with oversight by the County of San Diego Department of Environmental Health, Site Assessment and Mitigation Program.

Gasoline-range petroleum hydrocarbon compounds were detected in the soil from a depth of approximately 15 to 110 feet below ground surface, phase-separated gasoline was discovered floating on the groundwater surface at a depth of approximately 108 feet below the ground surface and the groundwater contains dissolved petroleum hydrocarbon compounds.  Dissolved concentrations of more than 200,000 ug/l of volatile fuel hydrocarbons and 10,000 ug/l of benzene were detected.   The water bearing zone is a relatively granular (sandstone) layer within dense, fractured formational rock. 
TGI prepared a corrective action plan which identified enhanced vapor recovery as the approporiate remedial action for the site, designed a vapor recovery, air sparging and carbon treatment system, obtained an APCD permit for operation of the system and installed the system using existing and new wells. 
TGI operated the system for the City beginning in 2003.  The remediation system was successful in recovering more than 20,000 gallons of gasoline from the subsurface and reducing dissolved phase concentrations in the groundwater by 98%.  TGI performed post-remediation monitoring of 10 wells at the Site through and completed final closure of the Site in April 2013.  


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