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i Soil samples were collected every 5 feet or at obvious changes in lithology using a split spoon sampler containing three, 2-inch diameter by 6-inch long brass sample tubes. Soil samples were collected from the sampler in brass tubes and sealed with teflon tape and plastic end-caps. The soil !~ samples were labeled with the appropriate borehole information, time and date of collection, and placed on ice for subsequent transport to and analysis at Excelchem Environmental labs located in Roseville, California. Chain-of-custody procedures were followed at all times. Selected soil samples were analyzed using TPHg and benzene,toluene, ethylbenzene, and total xylenes (BTEX), using modified EPA Method 8015, and EPA Method 8020 respectively. 1 3.4 Groundwater Monitor Well Installation Six groundwater monitor wells (MW-5, MW-6, MW-7, MW-8, MW-9, and MW-10) were constructed at the site. A relatively large amount of screen was used to construct each well because historical data from quarterly monitoring indicated a wide seasonal fluctuation of the water table elevation. Each monitor well was constructed of 2-inch diameter, 0.020-inch machine slot, Schedule 40 polyvinylchloride(PVC)well screen, installed from the bottom of the borehole (100 feet bgs) to approximately 65 feet bgs. Two-inch diameter blank PVC casing completed the well from the top of the screened interval to within 112-foot of surface grade. A filter pack consisting of 43 Monterey sand was placed in the annular space from the bottom of the boring to approximately 2-feet above the screened interval. A sanitary seal consisting of 2-feet of hydrated bentonite chips was placed on top of the filter pack,the remaining annulus was grouted with Portland cement to within 1 foot of ground surface. The groundwater monitor wells were completed at ground surface with an 8-inch diameter water tight traffic-rated street box set in concrete, and locked,using a water tight well cap. 3.5 Groundwater Monitor Well Development and Surveying After installation, the monitor wells were checked for floating liquid hydrocarbon by lowering a clean teflon bailer down the well and collecting a sample at the groundwater interface. No floating !=_ liquid hydrocarbon was obtained in any of the newly installed monitor wells. Monitor wells MW-5, MW-6, MW-7, and MW-8, were developed by using a mechanical bailer to alternately surge the j screened portion of the well bore and purge the sediment laden water. Monitor wells MW-9 and MW-10 were hand developed by using a PVC bailer. Development continued until five to ten well volumes of groundwater were removed, and/or the water produced was relatively sediment free. The top of casing of each completed groundwater monitor well was then surveyed to an arbitrary datum (100 feet)to within the nearest 0.01 foot,and accurately located on a site map by Morrow Surveying, Inc. of West Sacramento, California, a licensed professional survey company. Monitor well survey elevations are presented in Table 1. A photocopy of the Morrow Surveying blueprint depicting well locations and elevations is contained in Appendix B. 3.6 Groundwater Monitoring and Sampling Depth to groundwater was obtained from the newly installed and existing groundwater monitor wells -, at the site using a water level indicator graduated to 0.01 foot. The depth to groundwater _ measurement was converted to a groundwater elevation for each well and used to construct a potentiometric surface map (Figure 4), and calculate the local groundwater flow direction and hydraulic gradient. The groundwater potentiometric surface elevation averaged approximately 75.26 Job No.)0710-001-01SECOR LOCKEFORD.rNV 0c1ober9,1995 i_