ARCHIVED REPORTS XR0003434 - Laserfiche WebLink

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Mr DarinL Rouse Exxon Company, U S A August 4, 1999 Page 4 During the construction of each well a surge block was used to surge the filter pack to remove fines ' within the annulus and eliminate any budged materials On June 1, 1999, each newly installed well was developed using a submersible pump and bailer The wells were purged until purge water was relatively sediment free and a minimum of six wetted casing volumes were removed ' Depth to ground water was measured in monitoring wells MW-I through MW-10 on June 4, 1999 The depth to water measurements and survey casing elevations were used to construct a ground water ' elevation contour map included as Figure 3 On June 4, 1999, ground water was flowing to the northeast with an average hydraulic gradient of 0 005 Ground water samples were collected from MW-9 and MW-10 on June 4, 1999, and submitted to Sequoia Analytical for analysis of BTEX and TPPH as gasoline using the previously described EPA Methods Ground water samples were additionally analyzed for fuel oxygenates tertiary amyl methyl ether, tertiary butyl alcohol, di-isopropyl ether, 1,2-dibromoethane (EDB), 1,2-dichloroethane, ethanol, ethyl tertiary butyl ether, methyl tertiary butyl ether, by EPA Method 8260B ' Ground Water Analytical Results Ground water samples collected from monitoring wells MW-9 and MW-10 were below the laboratory's reporting limits for BTEX and TPPH as gasoline Laboratory chemical analyses on ground water samples collected from MW-9 and MW-10 detected concentrations of MTBE at 4 0 micrograms per liter (pg/L) and 77 5 µg/L, respectively The ground water sample collected from MW-10 also contained 1,2-dichloroethane at a concentration 6 54 µg/L Cumulative analytical results for ground water Samples collected at the site are summarized in Table 2 A copy of the laboratory analytical report with chain-of-custody documentation for the June 4, 1999, sampling event is included as Enclosure E ' Soil Stockpile ' Soil generated from drilling activities was temporarily stockpiled on-site Soil samples were collected from the stockpile for chemical analysis to assess disposal options Following receipt of soil analytical results and acceptance by BFI Vasco Road Sanitary Landfill located in Livermore, California the soil stockpile was transported by Dillard Trucking, Inc of Byron, California under non-hazardous waste ' manifest Approximately 5 27 tons of soil were removed from the site on June 22, 1999 Copies of the waste manifest and soil removal completion letter are included in Enclosure F ' Schedule rhe newly installed wells MW-9 and MW-10 will be included in future quarterly ground water ' monitoring and sampling events