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i Mr Kyle Christie January 11, 1995 Page 3 been reported since sampling began in 1988 TPH-G and BTEX concentrations are generally higher in the sample from well E-6 than have previously been reported 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-f and near Chevron's former underground storage tank location Samples from Chevron's MW-1 have generally contained similar TPH-G and BTEX concentrations to those in BHD-1 The samples from off-site wells PR-1, PR-2, E-7, and BHD-2, and on-site well MW-1 did not contain detectable concentrations of hydrocarbons, indicating that off-site migration is being contained by the GWES 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 1994 Description The remediation system at ARCO Facility 2133 consists of a GWES The GWES consists of one groundwater extraction well with a designed pumping capacity of 15 gallons per minute The extracted groundwater does not require treatment prior to discharge to meet the requirements of the City of Stockton wastewater discharge permit issued for this site The system is sampled monthly to ensure the discharge is within permitted limits The analytical results are included in Exhibit B Groundwater is extracted from the well via a submersible pump Installation and start-up of a free product recovery system occurred in 1984 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, and it has been operated nearly continuously since June 1991 Operating Conditions This Quarter During the third quarter of 1994, the GWES operated approximately 60 percent of the time The system did not operate for most of September, during construction of the SVE/AS system BC shut the system off to protect workers from the danger of accidental electrocution resulting from disturbance of electrical lines during excavation During operation of the GWES in the third quarter of 1994, approximately 682,077 gallons were extracted and discharged During this quarter, the pumping rate of the extraction well was reduced to 8 gallons per minute {gpm) The total amount of BTEX and TPH-G in the extracted groundwater is shown in Table 4 The quantity of BTEX and TPH-G discharged to the sewer is well within the limits stated in the permit Use or disclosure of data contained on flits sheet is subject to the restriction specified at the Beginning of this docuinent t2671REP0RTs13RD94QTR RPT