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Unocal Service Station #6981 February 1, 1995 the VES influent and effluent vapor stream samples are summarized in Table 2 The VES Operation and Emissions Data are summarized in Table 3 Copies of the Sequoia Analytical Laboratory reports and chain-of-custody forms are presented in Attachment D TPHg concentrations in influent vapor stream samples ranged from 4,100 to 5,220 milligrams per cubic meter (mg/m�) Benzene concentrations in these samples ranged from 57 to 164 mg/m3 TPHg concentrations in the effluent vapor stream samples collected during the quarter ranged from < 11.0 to 74 mg/m3 TPHg destruction efficiencies during this period were greater than 98.2%, and the TPHg emission rate did not exceed 1 55 pounds per day (lb/day) Effluent benzene concentrations during this same period ranged from <0 108 to 0 060 mg/m3, with destruction efficiencies greater than 99 8% The benzene emission rate did not exceed 0 004 lb/day DISCUSSION The VES was brought online September 22, 1994 As of the December 11, 1994, the VES had operated approximately 73 days, or 92% of the time All of the vapor extraction wells were open and used for extracting hydrocarbon-bearing vapors during this period The VES was in compliance with all SJVUAPCD permit requirements regarding TPHg emission rated and destruction efficiencies Through December 11, 1994, approximately 3,612 pounds of hydrocarbons (TPHg) have been extracted from beneath the site The shallow groundwater table beneath the site dropped approximately 1 foot in the fourth quarter of 1994 as compared to the third quarter of 1994 Wells with the highest concentrations of dissolved gasoline are located in the vicinity of the eastern most dispenser island The analytical data from the surrounding wells continues to indicate that the dissolved hydrocarbon plume beneath the site is delineated During the next quarter (first quarter 1995), the groundwater monitoring wells will continue to be monitored and sampled, and VES will be monitored every other week The data collected from these events will continue to be evaluated and will be reported in the First Quarter 1995 Status Report which will be submitted to the appropriate regulatory agencies by July 30, 1995 4855702-2 3 GeoStrategies Inc.