SITE INFORMATION AND CORRESPONDENCE

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Roberts Petroleum Services Facility July 11, 1990 Project No. 1628G y Page 2 a An Exceltech geologist togged the boring with soil descriptions classfied according to the Unified Soil Classification System and Munsell Soil Color Charts. Before drilling Y i� bean at the site, all g drilling and sampling equipment was steam cleaned to reduce the potential for cross-contamination. During drilling and between soil sampling intervals, the soil��samplker was scrubbed and washed with trisodium phosphate solution and rinsed with potable water. a Soil samples were collected at approximately 5-foot depth intervals through the hollow-stem auger to minimize cross contamination and sampling of slough. A modified California split-spoon ; 3 sampler, equipped with three internal brass liners, each 6 inches long and 2 inches in diameter, was used to collect and retain the samples. The sampler was advanced 18 inches into the relatively undisturbed soils ahead of the auger by driving it with a 140-1pound rig-operated hammer. After recovery from the borehole, the sampler was broken do w}n into its component parts. The lowermost sample liner from each set of samples collected above thel`water table was preserved for ' laboratory analysis. 1 { The ends of the liner were covered with aluminum foil and plastic caps. It was then labeled with a unique sample number and pertinent sample information,placed in a plastic "Ziploc" bag, entered onto a chain-of-custody form, and packed in a chilled ice chest. The soil in the remaining liners was visually characterized and checked for petroleum vapors`. Hydrocarbon soil vapor concentrations were measured in the field with an OVM 580A photoionzation detector. Soil cuttings generated from the drilling of the exploratory boring were placed on plastic sheeting, covered, and left on-site pending the laboratory analytical results. Details of the subsurface conditions encountered are shown on the boring log included inp Appendix A. Appendix B includes Exceltech protocol for soil sampling. Groundwater Monitoring Well Construction { �. Upon completion, the exploratory borehole was converted to a groundwater monitoring well (MW- 8). Four-inch-diameter, Schedule 40 PVC blank and factory-slotted casings with flush-threaded couplings were set through the augers. No solvents or!I cements were used during well construction. An Exceltech geologist determined the placement of the screened interval in the field. The well was installed to monitor the uppermost water-bearing zone. a After the PVC well casingwas installed, No. 3 sand was oared down the annular space between P P F the augers and the well casing to make the desired sand pack.! The augers were pulled out of the E ground a few feet at a time during sanding. Sand filled the annular space to approximately 2 feet above the top of the screened interval. Approximately 1-1/2 feet of bentonite pellets was placed on r top of the sand and hydrated. A cement grout seal was then placed in the annulus up to the ground surface. A vault box, set in concrete around the wellhead, completed the well installation. Appendix A contains construction details of the well. Well Development After I� M e construction, the well was developed to improve the hydraulic c�onductivity between the well and the natural formation. The development was conducted by;�a surge-and-purge method on April 25 and 26, 1990. A surge block was used to surge the water in and out of the screen and sand pack.