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.. LEMSHiLL•HEFKENNQFF,WC. Reference point (RP) elevations were established by licensed surveyors to within 0.01 foot at each of the monitoring wells. All groundwater level measurements and subsequent calculations are based on these RP's. 4.2 GROUNDWATER SAMPLING As mentioned in Section 3.1 Soil Sampling, grab wat::r samples were collected on September 5 and 6, 1990 from soil borings 581; SB4, and SB6 using either a bailer or a "hydropunch". On October 1, 1990, representative groundwater samples were collected from each of the monitoring wells 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 monitoring wells were sampled with a 3-inch diameter acrylic bailer. Several well volumes of water were removed prior to sampling, while field measurements of conductivity, pH, temperature, and visual observations were made to ensure the collection of stable, representative groundwater samples. Quantitative groundwater sampling field data sheets are included in Appendix E. All sampling equipment was cleaned with a trisodium phosphate TSP) and water solution before sampling each monitoring well to prevent potential cross- contamination. Water samples were collected in sterile sampling containers, 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 the.Jahoratory within 24 hours of collection under appropriate chain- of-custody procedures, and extracted prior to expiration of approved hrrjding times. .Chain-of-custody forms are presented in Appendix E. 4.3 SAMPLE ANALYSIS Groundwater samples were collected on September 5 and 6, 1990, from soil borings SBI using a hydropunch and SB4 and S86 using a Mailer. These samples were analyzed for benzene, toluene, ethylbenzene, and xyle.iP (B'IX&E), total petroieiim F ' hydrocarbons (TPH) as gasoline and diesel, and total dissolved solids (TDS). on October 1, 1990, one week after well development, groundwater samples were collected from the monitoring wells and analyzed for BTX&E, TPH as gasoline, TOS, ' and total coliform. The analytical methods referred to above conform to EPA Test Methods for Evalua,t',ng Solid, Waste: Physical/Chemical Methods (SU-846, 2nd Edition), Mgthads ' for Organic Ch gmical Analysis of Municipal and Industrial Wastewater, USEPA 600- . --- 14-057, applicable methodologies from Standard Methj1d for-the i:xaminatinn -of -- - _ -- Waier---and Wastewater, ,,16th Edition, and/or as specified in the Leaking Underground Fuel Tank Mrnual (LUFT), modified EPA SW-846 Method 8015.