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. Monitoring Well Installation Report - Former Chevron Service Station #9-5775 June 2 1999 • Upon completing soil sample collection, boring SB -1 was backfilled with neat cement with 5 % bentonite from the total depth of the boring to the ground surface A groundwater monitoring well was constructed in each of well borings using 20 feet of two-inch diameter, 0 020 -inch machine -slotted Schedule 40 PVC screen Lonestar #3 graded sand was placed in each well across the entire screen interval and extended approximately 2 feet above the top of the screen Each well was then sealed with 2 feet of hydrated bentonite chips followed by neat cement Well construction details are presented on the boring logs in Appendix D Drill cuttings were placed on and covered with plastic sheeting and stored on-site pending disposal After completion of drilling, four samples for disposal characterization were collected from the drill cuttings and submitted to the laboratory for composlting and analysis as sample SP (A -D) On February 12, 1999 the drill cuttings were removed from the site and transported to the BFI Landfill in Livermore by Integrated Wastestream Management (IWM) 4.2 Well Development and Sampling On February 3, 1999, groundwater monitoring wells MW -1 through MW -4 were developed by GR personnel using a vented surge block and hand -balling Depth to water was measured in the wells prior to development Groundwater samples were collected from the wells upon completion of well development Water purged during well development and sampling was transported to McKittrtck Waste Management by IWM Groundwater monitoring data are presented in Table 2, and copies of the GR Well Development and Sampling Field Data Sheets are included in Appendix E 4 3 Wellhead Survey On March 7, 1999, wells MW -1 through MW4 were surveyed relative to mean sea level by Virgil Chavez, a California licensed land surveyor (#6323) Horizontal coordinates were obtained at the same time A copy of the survey report is included in Appendix F, and the survey data is summarized in Table 2 4.4 Laboratory Analysts Soil and groundwater samples were analyzed by Sequoia Analytical in Walnut Creek, California (FLAP #1271) Selected soil samples collected from the borings and groundwater samples were analyzed for TPHg, benzene, toluene, ethylbenzene and xylenes (BTEX), and MtBE by Environmental Protection Agency (EPA) Methods 8015/8020 Groundwater samples, the soil samples collected at the bottom from each boring and two soil samples with the highest MtBE concentrations as indicated by the results of EPA Method 8020 were also analyzed for oxygenate compounds (MtBE, Ethanol, t -Butanol, Di -isopropyl ether [DIPS], ethyl tertiary butyl ether [EtBE] and tertiary amyl methyl ether [tAME]) by EPA Method 8260 In addition, soil samples collected from boring SB -1 at 30, 33, 43 and 54 feet bgs and from boring MW -4 at 11, 16, 20 5, 45 and 53 5 feet bgs were analyzed for bulk density and porosity by method RP -40 and 34WS 04-2 4