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Monitoring Well Installation and VET Report and IRAP—Former Unocal Station#0187,Stockton CA
<br /> December 22 2000
<br /> and 0 0453 ppm at 91, 111 5, and 116 5 feet bgs, respectively), U-23 (0 0628 ppm at 81 feet bgs), and
<br /> UV-3 (0 0105 ppm at 26 feet bgs)
<br /> Groundwater Analytical Results
<br /> MtBE was not detected in any well except for well U-22, where it was detected at a concentration of 3 06
<br /> ppb by EPA Method 8260B TPHg or benzene were not detected in wells U-1, U-2, U-4 through U-9,
<br /> U-11, U-14 through U-18, U-22, U-24, or U-25, and TPHg were not detected in wells U-20 or U-23
<br /> Petroleum hydrocarbons in the C6-C12 range (identified as TPHg) were detected in wells U-3 (12,300
<br /> ppb), U-10 (383 ppb), U-12 (861 ppb), U-13 (5,120 ppb), U-19 (3,210 ppb), U-21 (2,530 ppb), NP-1-22
<br /> (16,700 ppb), NP-1-65 (3 8,490 ppb), NP-1-111 (2 10 ppb), NP-2-22 (431 ppb), NP-2-60 (13,300 ppb),
<br /> and NP-2-116 (211 ppb) Benzene was detected in wells U-3 (515 ppb), U-10 (57 9 ppb), U-12 (99 9
<br /> ppb), U-13 (1,560 ppb), U-19 (810 ppb), U-20 (0 782 ppb), U-21 (706 ppb), U-23 (0 557 ppb), NP-1-22
<br /> (1,010 ppb), NP-1-65 (1,660 ppb), NP-1-111 (11 8 ppb), NP-2-22 (4 2 ppb), NP-2-60 (4,350 ppb), and
<br /> NP-2-116(24 5 ppb) DIPE was detected in well U-12 at a concentration of 3 58 ppb
<br /> WASTE DISPOSAL
<br /> Soil cuttings generated during drilling activities were placed on and covered with plastic sheeting at the
<br /> subject site and disposal confirmation sample SP-1(A-D) was collected (Table 1) Approximately 32
<br /> yards of soil cuttings remain at the site, but have been approved for disposal at Forward Landfill in
<br /> Manteca,California
<br /> VAPOR EXTRACTION PILOT TEST
<br /> GR personnel performed a five-day vapor extraction (VE) pilot test at the site from November 27 to
<br /> December 1, 2000 The VE system operated for a total of 40 hours and soil vapors were extracted from
<br /> wells UV-1, UV-2 and UV-3 The purpose of the VE pilot test was to evaluate the feasibility of the VE
<br /> technology and collect needed site specific data for the design of a VE system if deemed necessary The VE
<br /> pilot test also provided GR with data to determine the area with the highest residual hydrocarbons in the soil
<br /> and if there was enough hydrocarbon mass to warrant the installation of a VE system
<br /> Soil Vapor Extraction Test E ut ment
<br /> A trailer mounted, propane powered internal combustion (1C) engine was used for the soil vapor extraction
<br /> pilot test The vapor extraction test was performed in accordance with the San Joaquin Valley Air Pollution
<br /> Control District(SJVAPCD) source testing guidelines The SJVAPCD Notice of Consent Letter for a soil
<br /> vapor extraction pilot test is presented in Appendix B
<br /> An organic vapor monitor (OVM) was initially used to monitor the hydrocarbon concentrations in the
<br /> extracted soil vapor during the VE pilot test Laboratory confirmation samples were collected in Tedlar bags
<br /> and submitted to Sequoia Analytical Laboratories(ELAP#1274) Vacuum observation wells, measuring the
<br /> response to the vapor extraction,were monitored with magnehelic gauges and the data recorded manually
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