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CLEAR' TER G R. 0 U 'P" 1 N C, 2.3 Groundwater Gau in , Sam lin and Analysis g g Sampling The monitoring. wells were gauged and sampled'on February',28, 1995'. Prior to sampling, all wells were "purged of a "mi imum of ten "well" volumes of.. groundwater.- Well "purging information •is' presented on the Gauge. Data/Purge Calculations and Purge Data forms in Appendix 0. 'Following recovery'of water levels to at least 80°k/o of:their static levels, groundwater samples were collected 'from the` monitoring wells using dedicated polyethylene '. bailers. Samples were.labeled;;documented on a chain-of-custody form, .and;placed in a cooler for .transport to PACE,, Inc:, a state-certified . 1.laboratory located in Petaluma, California. The ground`,water.samples were analyzed for TPHg and TPHd by EPA Method 8015-:(modified) arid'"BTEX by EPA Method 8020"(modified). 3.0 ,RESULTS AND"DISCUSSION 3.1, Site Stratigraphy ; .. Sediments encountered_ during drilling consisted. primarily of silty sand in the' upper half of the borings and poorly graded,sands with or without interbedded silt in the lower half. -Minor gravel was also noted throughout the borings. Complete soil sample descriptions are presented on the Soil Boring Log "and Well-. Construction Diagrams irCAppendix"Cr 3.2 Results of Soil Sample Analysis No TPHg, TPHd or BTEX was detected in concentrations exceeding the method detection limits in soil samples,collected from blorings MW-1, MW-2 and MW-3. A summaryof soil sample,analytical results is presented•on Table 1. A.copy.of the laboratory"report and "chain-of-custody.form are attached'in Appendix E. � 3.3 Groundwater Gradient On February 28, "1995, the depth to groundwater in each of the wells ranged from, 20.74 to .21:91 feet below top of casing. .Groundwater"flow,was determined to be to the southwest at an' approximate gradient of'0.1% (0.001ft/ft). Depth to water measurements and wellhead elevation data ere used to calculate, groundwater l elevation:contours (Figure 3): 3.4 Results of"Groundwater Sample Analysis" Separate-phase petroleum was not detected in "'any of the monitoring wells: "Neither TPHg nor BTEX were detected.in groundwater-samples collected from monitoring wells"MW-1, MW-2 and MW-3. TPHd was detected at concentrations of.150, 330 and, 100 parts per billion (ppb), respectively. A'summary of. groundwater elevations and . { " anal tical results is: resented on Table"2.'.Hydrocarbo'n concentrations"are displayed y . p D-104 SWI 3 May.1, 1995.