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03 February 2004 <br /> AGE-NC Project No 98-0500104-1127 <br /> IPage 3 of 6 <br /> I3 1 GROUND WATER ELEVATION AND GRADIENT <br /> In the AGE-prepared Monitoring Well Installation Report, dated 08 October 2002, AGE identified <br /> four Informal hydrologic units(HU)on the basis of the physical characteristics of the soil developed <br /> from analysis of soil samples from well and CPT borings Shallow-screened (40 to 60 feet below <br /> surface grade[bsg])monitoring wells MW-1 through MW-17 were screened through first hydrologic <br /> unit (HU1), Intermediate-upper-screened (75 to 85 feet bsg) wells MW-18 through MW-21 were <br /> screened in second hydrologic unit (HU2), intermediate-lower-screened (90 to 105 feet bsg) wells <br /> MW-22 through MW-29 were screened in a third hydrologic unit(HU3) and fourth hydrologic unit <br /> (HU4), deeper-screen (125 to 135 feet bsg)wells MW-31 through MW-33 were screened in a fifth <br /> hydrologic unit(HU5) from 110 feet to 145 feet bsg and well MW-34 was screened in the sixth and <br /> lowest hydrologic unit (HU6) at 145 to 150 feet bsg <br /> From the depth to ground water measurements of the shallow-,Intermediate-and deep-screened wells <br /> collected on 29 December 2003,ground water elevations and gradients were calculated for the First <br /> and Third/Fourth hydrologic units <br /> • Depths to ground water for shallow-screen wells ranged between 51 40 and 53 03 feet below <br /> ithe tops of well casings Ground water elevations were calculated to be between 35 07 feet <br /> (MW-6)and 35 55 feet(MW-12)below mean sea level(msl) The general ground water flow <br /> direction was north-northeast,at the former UST location and generally north across the site <br /> at gradients of 0 001 feet/feet at the former UST and dispenser area, generally MW-1 <br /> (Figure 3) Ground water in the area of the former stoddard release appears to flow towards <br /> well MW-12, or northwest <br /> • Depths to ground water for intermediate-lower-screened wells ranged between 51 40 and <br /> 52 78 feet below the tops of well casings Ground water elevations were calculated to be <br /> between 35 18 feet and 35 70 feet below msl The inferred ground water flow direction was <br /> northeast at a gradient of 0 003 feet/feet (Figure 4) <br /> Ground water elevation at the site increased an average 3 feet between the July and December 2003 <br /> ground water monitoring events (Table 1) <br /> I <br /> 32 LABORATORY RESULTS OF GROUND WATER SAMPLES <br /> EA total of thirty-three groundwater samples collected from monitoring wells MW-I through MW-34 <br /> were submitted for laboratory analysis <br /> • TPH-g/TPH-ss were detected in ground water samples from wells MW-16 and MW-18 <br /> • associated with the stoddard release west of the building on the site <br /> Advanced GeoEnvironmentai,Inc <br />