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� u Mr Sam Savig Page 4 of 6 3.0 RESULTS 3.1 Subsurface Conditions Soil in the vicinity of well MW1, completed at the northeast corner of the property, consisted of clayey sand from the ground surface to a depth of approximately 6-9 feet bgs, which was underlain by well graded sand from approximately 6-9 feet bgs to approximately 25 5 feet bgs The interval from 25 5 feet bgs to 26 feet bgs (the maximum depth explored) consisted of silty sand Slight to moderate petroleum hydrocarbon odors and soil discoloration were noted in soil samples collected at depths of 10 and 15 feet bgs from boring MW I No odors or discoloration were noted in samples collected from 20 and 25 feet bgs, however PID readings from boring MW1 generally diminished with depth, ranging from 912 parts per million (ppm) at a depth of 10 feet bgs to 12 ppm at a depth of 25 feet bgs Soil in the vicinity of well MW2, located approximately 37 feet west of MWI, consisted of alternating layers of silty sand (encountered at 5, 15, and 25 feet bgs) and silty clay (encountered at 10 and 20 feet bgs) No petroleum odors were noted in any samples collected from boring MW2 PID readings ranged from zero to 2 ppm Soil in the vicinity of well N W3, located directly through the former UST excavation, consisted of pea gravel fill to a depth of approximately 10 feet bgs, which was underlain by silty clay from . approximately 10 feet bgs and well graded sand from approximately 10 feet bgs to 22-24 feet bgs The bottom sample (24 5-26 feet bgs) was silty clay No petroleum odors were noted in any samples collected from boring MW3 PID readings ranged from zero to 7 ppm Groundwater was first found at depths ranging from approximately 8 feet bgs in boring MW l to 12 feet bgs in borings MW2 and MW3 Boring logs and well construction details are included in Appendix C To determine the groundwater elevation, the static depth to groundwater was measured in each well and subtracted from the surveyed wellhead elevation The potentiometric surface ranged from approximately 38 11 to 38 13 feet above mean sea level (MSL) Based upon these data, groundwater flows in a north northeasterly direction with a very flat hydraulic gradient of approximately 0 0008 ft/ft (approximately 4 feet per mile) Groundwater elevations are summarized in Table 1 A potentiometric surface map generated using the November 27, 2001 well monitoring data is depicted on Figure 4 The groundwater velocity was estimated from the lithology of the aquifer material and from literature estimates of hydraulic conductivity Based upon the boring logs, the aquifer material consists of sand, silty sand, and clay The aquifer material was assigned a hydraulic conductivity of 100 gpd1W and an effective porosity of 30%, which are in the mid-range of values for sand found in the literature Utilizing the calculated groundwater gradient of 0 0008 ft/ft, the calculated interstitial flow velocity at the site is approximately 0 04 feet per day or 15-20 feet per year A review of the field monitoring parameters on the well purge logs indicate that EC in groundwater beneath the site ranged from approximately 1,720 to • 1,930 umhos, which corresponds to a total dissolved solids (TDS) value exceeding 1,000 parts per million (ppm) GIData1GROUNDZE\THORPE15ouza\Repotts\WELLRPT doc