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f Mr Kyle Christie May 15, 1995 Page 3 Description. The remediation system at ARCO Facility 434 consists of a soil vapor extraction and treatment system (SUETS) A ground water extraction and treatment system (GWETS) which was formerly in use at the site, was shut down on April 19, 1993, due to nondetectable concentrations of hydrocarbons in the groundwater The GAC vessels have been removed for use at another ARCO facility, and the effluent piping from the GWETS to the industrial sewer was disconnected The connection point to the industrial sewer was capped to prevent any accidental releases Because the GWETS operation has been terminated, Industrial Waste Discharge Permit No 151, that allowed discharge of the treated groundwater to the City of Lodi industrial sewer, has been suspended The SVETS consists of eight soil vapor extraction wells (VE-1 through VE-8) and a soil vapor treatment system The soil vapor treatment system is composed of a vacuum compressor pump connected to a King-Buck-Hasstech catalytic oxidizer with a design treatment flow rate of 100 cubic feet per minute (cfm) of vapor The system is operated under Perrrut-to-Operate No N-1081-1-0 issued by San Joaquin Valley Unified Air Pollution Control District (SJVUAPCD). In addition. a slip stream of soil vapor is treated by a biofilter system consisting of a humidifier and a contact chamber Operating Conditions This Quarter. The SVETS operated 85 percent of the time at an average flow rate of 58 cfm during this quarter. The system was down for 25 days due to high levels of water in the system influent. Vapors were extracted from wells VE-3, VE-4, • and VE-f. Vapor samples were collected from each of the individual wells during the fust quarter of 1995 The soil vapor laboratory reports and chain-of-custody documentation are included in Exhibit B. The current, historical, and total concentrations of BTEX and TPH-G in the extracted soil vapor are shown in Table 4 Table 5 summarizes the status of the soil vapor extraction wells and analytical results from the individual wells Figure 3 represents the inferred vacuum across the site as provided by measurements taken on February 6, 1995 The line of "influence" (determined as 0 1 inches of water, vacuum) is approximated by interpolating from vacuum readings taken at each well, and adjusting for depth to the well screen. Influent concentrations of TPH-G and benzene are steadily declining, which indicates the hydrocarbons beneath the site are being successfully remediated. During the first quarter of 1995, 275 pounds (41 gallons) of TPH-G were removed This represents an average removal rate of two pounds per day No measurable benzene was removed during the first quarter Recommendations Brown and Caldwell has proposed that the biofilter system be permitted to remediate the remaining low soil vapor concentrations at the site Due to the decline in soil vapor influent concentrations to the catalytic oxidizer and the lack of groundwater contamination at the site the catalytic oxidizer will be removed On November 7, 1994, Authority-to-Construct Permit No N-1081-1-1 for the biofilter system was issued by SJVUAPCD Full-time, independent Use or disclosure of data contained on this sheet is subject to the resirtaton specified at the beginning of this document 206".EP0RTS'\I ST95QTR$Pr