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L4 LEEDSHILL HERKENHOFF, INC Reference point (RP) elevations were established by licensed surveyors to within 0.01 foot for each of the newly installed monitoring wells and the three existing wells at this site for vertical gradient control . All groundwater level measurements and subsequent calculations are based on these RP's. Depth to groundwater measurements were taken several weeks after the monitoring wells were installed to determine the water surface elevation and direction of flow. This ' data is provided in Section 4.3 Groundwater Flow. 3.3 GROUNDWATER SAMPLING Representative groundwater samples were collected from all five monitorin wells on December 7, 1989 using established protocol as specified in the USGS "National Handbook of Recommended Methods for Water Data Acquisition," which provides guidelines for the collection of representative groundwater samples. The 4-inch diameter monitoring wells were sampled with a 3-inch diameter Teflon bailer ' The 2-inch diameter monitoring wells were sampled with a 1.3-inch diameter Teflon bailer. Several well volumes of water were removed prior to sampling, while field measurements of conductivity (SC) , pH, temperature, and visual observations were made to ensure the collection of stable, representative groundwater samples. Groundwater sampling field data sheets are presented in Appendix B. The water samples were collected in sterile 40 ml glass VOA sampling bottles, appropriately labeled and preserved according to standard EPA methods All samples were cooled to 4 degrees Celsius at the site and maintained at that temperature until received at Superior Analytical laboratory. Samples were received at the laboratory within 24 hours of collection under appropriate chain- of-custody procedures, and extracted prior to expiration of approved holding times Chain-of-custody forms are presented in Appendix B 3.4 DRUJ AND STOCKPILE SAMPLING ' Three representative soil samples were collected from the stockpiled soil on site. Also, one soil sample was obtained from each of the nine BCA drums remaining on site except for drum BC4, which contained water and was therefore not sampled. The soil stockpile is estimated to contain approximate) 55 cubic ds of sol Y yards 1 Samples were collected on November 9, 1989 from the north end, the south end and the center of the stockpile. A hand trowel was used to collect samples by digging 18 inches below the surface and filling a clean glass jar. Drum samples were collected with the hand trowel 18 inches below the surface from the center of each drum. The hand trowel was brushed and washed between samples in a Trisodium Phosphate (TSP) solution to prevent potential cross-contaminat:on Once collected, all samples were wrapped, carefully marked, and identified The samples were then preserved for analysis in accordance with EPA and California Department of Health Services (DOHS) protocol . Before transport to the