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` Mr Kyle Christie March 1, 1996 Page 3 • Samples from Chevron's MW-1 have generally contained similar TPH-G and BTEX concentrations to those in BHD-1 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 treatmentlair sparging (SUET/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 1986 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, 1996 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 System influent and effluent hydrocarbon concentrations are measured on a monthly basis using a photo-ionization detector (PID) to ensure that the conditions of the Authonty-to-Construct are met Operating Conditions This Quarter During the fourth quarter of 1995, the GWES operated 100 percent of the time at an average flow rate of 2 4 gpm, extracting and discharging a total of 326,645 gallons of groundwater The total amount of BTEX and TPH-G in the extracted groundwater is shown in Table 4 The analytical results are included in Exhibit B The quantity of BTEX and TPH-G discharged to the sewer is well within the limits stated in the permit The SVET system operated 93 percent of the time during the fourth quarter of 1995 The SVET system was not operating 7 percent of the time during the fourth quarter because of power outages The system is currently configured to extract vapor from wells V-2 and V-3 which are • Use or disclosure of data continued on this sheet is subject to the restriction specified at the beginning of this document 2060�REPORTYATHOQTR DOC