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Mr Kyle Christie December 11, 1995 Page 3 complete laboratory report for the sampling event is presented in Exhibit A Figure 2 presents TPH-G and BTEX concentrations for this sampling event. The hydrocarbons detected in MW-1 are most likely due to the product line failure which occurred in the second quarter 1995 The hydrocarbon concentrations detected in BHD-1 are thought to be attributed to the Chevron station across the street from the ARCO site Chevron's well MW-1 is located approximately 30 feet to the north of well BHD-1 and near Chevron's former underground storage tank location Samples from Chevron's MW-1 have generally contained sirnilar TPH-G and BTEX concentrations to those in BHD-1 Fecal coliform was not detected in the sample from well MW-3 Therefore, fecal coliform analyses will not be conducted on samples from this or any of the other wells during future sampling events Status of Site Remediation This section provides a description of the remediation system and discusses the operation of the remediation system for the third quarter 1995 Description The remediation system at ARCO Facility 2133 consists of a groundwater • extraction system (GWES) and a soil vapor extraction and treatment/air spargmg (SVET/AS) system The GWES consists of one groundwater extraction well (R) fitted with a submersible pump, with a designed pumping capacity of 15 gallons per minute (gpm). The extracted groundwater is discharged to the City of Stockton sanitary sewer under City of Stockton Wastewater Discharge Permit The permit expires December 31, 1997 The extracted groundwater does not require treatment prior to discharge (as per the requirements of the wastewater discharge permit) The system is sampled monthly to ensure that discharge is within permitted limits The GWES has operated nearly continuously since June 1991 Prior to this time, a free product recovery system operated at the site from 1984 to 1985 After the free product was recovered, the system was modified for use as a GWES and operated periodically from 1986 to 1991 Additional modifications were made to improve the system in 1991 The SVET/AS system consists of 14 soil vapor extraction wells (V-1 through V-12, MW-2 and E-6) and nine air sparging wells (S-1 through S-9) The soil vapor extraction wells are connected to an Airex Katox 100 catalytic oxidizer unit Construction of the SVET/AS system was completed during the last quarter of 1994 and the system was brought on line in January of 1995 The system operates under Authonty-to-Construct (air) permit number N-78-3-0 issued by the San Joaquin Valley Unified Air Pollution Control District on August 1, 1994, and expiring October 1, 1995 Vapor extracted from the site is treated by the catalytic oxidizer unit which must either meet a minimum VOC destruction efficiency of 95 percent, or must not exceed a total VOC emission rate of 2 pounds in any one day Monthly Use or disclosure of data continued on this sheet is subject to the restriction specified at the beginning of this document 2060VtEP0RT5\3RD95QTR DOC