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Mr Chuck Carmel October 14 1993 Page 3 r� is composed of a vacuum compressor pump followed by a King-Buck-Hasstech catalytic oxidizer that has a design treatment flow rate of 100 cubic, feet per minute (ctm) of soil vapor The system is operated under Permit to Operate No N-1081-1-0 issued by San Joaquin Valley Unified Air Pollution Control District Operating Conditions This Quarter. In March 1993 the groundwater system was "pulsed" in attempt to remove hydrocarbon concentrations from the capillary zone Specitieally the system was turned on for a week. then off for a week However pulsing did not increase influent concentrations above detectable levels and therefore. the system was shut down on April 19. 1993 The SVETS operated continuously at 100 ctm during this quarter Vapor', were extracted from all eight vapor wells until May 1993 at which time wells VE-1 VE-2 and VE-3 were turned ott Vapors were extracted from the remaining five wells for the rest of the quarter Results and Discussion During operation of the GWETS in the second quarter of 1993 a total of 37,226 gallons has been extracted and treated The total amount of BTEX and TPH in the extracted groundwater is shown in Table 4 The current and historical concentrations of BTEX and TPH in the extracted soil vapor are shown in Table 5 The total amount of BTEX and TPH in the extracted soil vapor is also shown in Table 5 Influent concentrations appear to be steadily declining, indicating that the hydrocarbons are being successfully remediated The decision not to extract from wells VE-1, VE-2, and VE-5 was based on an evaluation of the following • Analytical data from samples collected March 12, 1993, from each vapor extraction well while it was operating Samples were collected by isolating each well at the treatment system manifold The analytical data are shown in Table 6 along with similar data collected during the original vapor extraction test in 1990 This data shows that wells VE-1, VE-2, and VE-5 were contributing insignificant concentrations of hydrocarbon constituents and not providing effective remediation • Wells VE-1 and VE-2 are not located in areas with known soil contamination and, therefore, influent concentrations from these wells were expected to decrease over time • Well VE-5 is located within the operational radius of influence (OROI) of other wells which continue to operate Figure 2 shows the area thought to be influenced by operating VE-3, VE-4 VE-6 VE-7, and VE-8 at an average flow rate of 20 cfm (20 (-fm is based on the assumption that the total flow rate of 100 ctm is distributed equally between these wells) The OROI shown on Figure 2 is ten feet This is based on Use or disclosure of data contcuned on this sheer is subject to the restriction spectfted at the beginning of this document 7846\REP0RT5\,1AY93QTR RPT Brown and Caldwell