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Third Quarter 2000 Site Update - Former Chevron #9-5775 (CAO #5-00-704) October 12, 2000 Valley Unified Air Pollution Control District Authority To Construct permit #N-4343-1-0 Locations of the vapor extraction wells are shown on Figure 2 A VES schematic is shown in figure 4 Carbon Change Out Due to detection of 20 2 parts per million (ppm) of methyl tert-butyl ether (MtBE) in the sample collected July 26, 2000, from Midpoint 1 (between the first and the second carbon vessels), GR contracted with US Filter/Westates to change out the carbon in the first carbon vessel US Filter/Westates changed this carbon on Monday, August, 7, 2000 The GWS was sampled again on August 3, 2000, prior to carbon change out Results of this second sample set were not received from the laboratory prior to carbon change out Petroleum hydrocarbons were not detected in the second sample from Midpoint I The GWS was not shut down during carbon change out Summary of GWS Operation The GWS was started on July 3, 2000 Tap water was used to wet the carbon in the vessels prior to system startup, so initial GWS samples were not collected until July 6, 2000, to allow the tap water to discharge During the quarter samples were collected from the influent port, midpoint 1 (between the first and second carbon vessels), midpoint 2 (between the second and third carbon vessels) and effluent sample ports on a weekly basis between July 6 and September 27, 2000 A total of 14 sampling events were performed During these sampling events, detectable influent concentrations of Total Petroleum Hydrocarbons as gasoline (TPHg) fluctuated from 1,290 to 52,000 parts per billion (ppb), benzene concentrations fluctuated from <50 to 7,300 ppb, and methyl tert-butyl ether (MtBE) concentrations fluctuated from 46,000 to 390,000 ppb Samples were analyzed by Sequoia Analytical (FLAP #1271,1624 and I2360) and KiffAnalytical LLC (ELAP #2236) Analytical data are summarized in Table I During the period from July 6 to September 27, 2000, the GWS treated and discharged a total 11,100 gallons over a penod of 83 days Calculated discharge rates during the third quarter 2000 ranged from 0 05 to 0 24 gallons per minute As of September 27, 2000, the system has extracted approximately 167 pounds (lb) of TPHg, 0 099 lb of benzene and 21 1 lb of MtBE GWS operational data are summarized in Table 2 Initial samples collected from theMidPointl, MidPomt2 and Effluent sample ports on July 6, 2000, contained low concentrations of petroleum hydrocarbons These samples were collected before enough time for all the tap water placed in the system to wet the carbon prior to startup would have discharged Confirming samples were collected on July 10, then the system flushed with approximately 1,400 gallons of tap water that was discharged to a holding tank, and a second sample collected Based on the results of this sampling the system was placed back in operation on July 11 The system did not pump groundwater for approximately 24 hours A flow meter was installed on the discharge line from the pump in well EX -1 on July 25, 2000 The well did not pump for approximately one half hour dunng installation As discussed above, a low concentration of MtBE was detected in MidPomt I sample collected July 26, 2000 A subsequent sample collected August 3, 2000, did not contain detectable concentrations of petroleum 346408 07 2