ARCHIVED REPORTS XR0001910 - Laserfiche WebLink

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Cecchuu Cecchim, and G ovannom, Fueling Island 4.3 Ground Wateir Monntoiri ng On June 20, 1996, the ground water level was approximately 62 feet below the top of casing and within the screened interval of UST-5 No free product was observed on ground water in the well Table 2 tabulates water level depth measurements and water level elevation calculations for the wells Figure 3 illustrates ground water elevation data in map view The ground water flow direction beneath the site at the time of measurement appears to be generally to the west The calculated ground water gradient over the site was approximately 0 004 foot/foot Analytical results for wells UST-2 through UST-5 are listed in Table 3 - Analytical Results of Ground Water Samples The certified analytical reports are presented m Appendix C On June 20, 1996, ground water from UST-5 was reported to contain TPH-D at a concentration of 180 micrograms per liter (µg11) TPH-G was reported at 110 µg/l BTEX were reported as 8 8 µg11 for benzene, 17 µg11 for toluene, 3 4 µg11 for ethylbenzene, and 10 µg11 for total xylenes In ground water from UST-2, TPH-D was reported to have a concentration of 140 µg/l All other analytes were reported as non- adetect in momtormg wells UST-2 through UST-4 4.4 Dlscussnon The intent of the installation of UST-5 was to provide additional information regarding both the soil plume and ground water plume near the hydrocarbon source area. Tests of the fine-grained soil samples, collected during the drillmg of UST-5, indicate that a soil plume consisting of concentrations of TPH-D and TPH-G extends to a depth of about 45 feet where the hydrocarbon concentrations begin to rapidly decrease with depth Non- detect findings are reported at a depth of 62 feet bgs Concentrations of dissolved hydrocarbons were low in the ground water, and no free-floatmg product was observed 4.4.1 Soil The soils recovered from the exploratory boring for UST-5 consisted mainly of fine- grained silty materials Medium-grained sand was encountered between 19 and 23 feet bgs Thin-bedded sand layers were also observed between 64 feet and 69 feet bgs. F 16M4W\2QM96 RPT 6 F„Vironmental Science do&gweenng, Inc