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-- 6.4 SUBSURFACE SOIL CONDITIONS The site is underlain by Holocene dune sand and alluvium consisting of interbedded sands, 'r silts and clays. The upper 15 feet consist primarily of sand and interbedded silts and clays generally occur below this depth. LA 6.5 GROUNDWATER CONDITIONS V Groundwater was measured at 15.75 to 16.73 feet bgs in the onsite monitoring wells MW-1, MW-2 and MW-3. The measured groundwater gradient flows southwest at 0.00547 ft/ft which is generally consistent with the known regional gradient direction. Discussions with agencies indicate regional groundwater flow is northwest, but generally westward. 6.6 ANALYTICAL TEST RESULTS +� 6.6.1 PID Field Readings Volatile organic vapor readings were not detected by an Hnu PID in the subsoil samples '-' obtained from the exploratory borings at the time of drilling, nor were odors or other hydrocarbons noted during drilling. The PID readings are noted on the boring logs attached as Appendix B. 6.6.2 Soil Samples a.. The laboratory test results indicated non-detectable concentrations of TPH, BTEX, and MTBE in the composite soil samples. Soil test results are summarized in Table 1 and the �. analytical laboratory report is included in Appendix C. 6.6.3 Groundwater Samples �G The groundwater sample obtained from well MW-2 showsncentrations of 1.6 ug/L (ppb) benzene, 15 ppb ethylbenzene, 1.3 ppb xylenes and 0.330 mg/I, (ppm) TPH. The other ar groundwater samples (MW-1, MW-3 and hydropunch S13-1) show non-detectable levels of TPH and BTEX. All groundwater samples analyzed show non-detectable concentrations of MTBE. The groundwater samples MW-2 and MW-3 show non-detectable concentrations of �^ volatile organic compounds by method 8260. The MW-2 sample showing non-detectable concentrations by 8260 and detectable concentrations by methods 8015-8020 is not consistent. Groundwater test results are summarized in Table 2 and the analytical laboratory report is included in Appendix C. JN 40007-097-01 nD^^ dec-96\ammteca.aa 6-2 G& W44 , f� 1� y� .