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i 3.3 Monitoring Well Development and Surveying The four momtonng wells were developed on January 4, 1999 by pumping and surging with an airlift pump The well development equipment was disassembled and washed in a laboratory grade detergent solution and nnsed with clean potable water pnor to use in each well Development water was stored on-site in 55-gallon drums The momtonng well top-of-casmg (TOC) elevations were surveyed relative to an arbitrary benchmark(chiseled square set at southeast corner of residence; assumed elevation of 100 00 feet) on February 19, 1999 by Quartaroli &Associates 3.4 Initial Monitoring Well Sampling The initial momtonng event was conducted on January 8, 1999 After depth sounding and visual observation, each momtonng well was purged, allowed to recover, and sampled The wells were purged of a minimum of four casing volumes of water Temperature, pH, and conductivity were measured after removal of each approximate casing-volume of water Purge water was stored on site in 55-gallon dnims Samples were obtained using disposable bailers, decanted into appropriate sample containers and stored m an ice chest containing blue ice The domestic well was purged for 10 minutes from a spigot at the top of the well, then a sample was obtained from the spigot Five groundwater samples (one from each monitoring well and one from the domestic well)were transported under Chain-of-Custody documentation to BSK Analytical Laboratones for analysis of TPHg and BTEX using EPA Method 8015/8020 (Modified) and for fuel oxygenates using EPA Method 8260 Due to expiration of the holding time pnor to BTEX analysis, the momtonng wells and domestic well were resampled on February 5, 1999 The sampling protocols described above were followed Groundwater samples from the second sampling event were submitted for analysis of TPHg, BTEX, and MTBE using EPA Method 8015/8020 (Modified) Water Sample Logs are presented in Appendix B Analytical results for groundwater samples are summarized in Table 2 Groundwater elevation data is presented in Table 3 Laboratory Analytical Reports, QA/QC Data, and Chain-of-Custody Documentation are presented in Appendix C ' 4.0 FINDINGS 4.1 Soil Soils encountered beneath the Site generally compnse mterbedded layers of sandy silt and silty sand The silt layers tend to grade downward into coarser-grained silty sand or sand in approximately 10-foot to 30-foot sequences A layer of fine- to medium-grained, dense sand is consistently encountered at approximately 40 feet bgs, with decreasing thickness to the west In borings MW-1 and B-2, the sand layer was present at about 34-57 feet bgs In borings MW-2 and intenm Report-07400178-May 1999 4