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iMonitoring Well Installation and VET Report,and[RAP--Former Unocal Station#0187,Stockton CA December 22 2000 During the pilot test the influent to the IC engine was sampled The highest influent petroleum concentrations were from well UV-1 Hydrocarbon concentrations of as high as 6,500 parts per million by volume (ppmv) of TPHg, 11 ppmv of benzene were found Much lower influent concentrations were reported from wells UV-2 and UV-3 No detectable concentrations of MtBE were reported in any influent samples Extraction rates for UV-1 were between 9 and 38 pounds TPHg per day at varying test conditions The extraction rates for UV-2 and UV-3 were between 0 and 2 pounds TPHg per day Complete sample and extraction rate data are provided in Table 4 Summary of Vapor Extraction Test The VE test was performed for a total of 40 hours An IC engine was used to extract vapors from wells UV-1, UV-2 and UV-3 System flow rates ranged from 9 to 23 scfm Based on the data from the VE pilot test, it appears that the maximum radius of influence from any vapor extraction well is less than 20 feet at test conditions Air samples were collected from the influent and effluent vapor streams Petroleum hydrocarbon concentrations in the influent vapor stream ranged from 19 to 6,500 ppmv of TPHg and 0 to 15 ppmv of benzene No detectable concentrations of MtBE were reported The only well where significant concentrations of petroleum hydrocarbons were removed was UV-1 This well was used in three of the five days of the test The extraction rate decreased over the three days of the test Based on the VE monitoring data, less than 25 pounds of TPHg were removed during this pilot test OZONE MICROSPARGE SYSTEM Sparge wells SP-lA, SP-113, SP-2A, SP-213, SP-3A, SP-3B, SP-4A and SP-4B were connected to an ozone microsparge system System operation began on December 13, 2000 The system will be evaluated based on sample results from wells NP-1 and NP-2 These nested piezometers are screened in each of the three zones Initially samples will be collected weekly and analyzed for TPHg by EPA method 8015, and BTEX and MtBE by EPA method 8020 Dissolved oxygen will also be measured using field test equipment As sample results are evaluated, sampling frequency might be modified CONCLUSIONS Based on data and observations from all field investigations performed at the site to date, we draw the following conclusions 1 The lack of a significant difference in groundwater elevations between wells screened in the A Zone (20 to 35 feet bgs), the B Zone (65 to 75 feet bgs) and the C Zone (screened from 110 to 120 feet bgs) suggests these zones are all part of the same hydrogeologic unit, and there is hydrostatic communication between the uppermost and the deepest depths explored This investigation did not encounter any fine-grained units that appear to act as a confining layer for groundwater Likewise, all of the fine-grained units encountered below first-encountered water 24004208-1 9