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Site Background Information - Fernando's Place AGE-NC Project No. 00-0769 Page 6 of 7 benzene (SVE5-25), 0.018 mg/kg toluene (SVE5-20), and 0.036 mg/kg ethylbenzene and 0.044 mg/kg total xylenes from SVE4-25. TAME was detected in soil samples collected from SVE4-25, SVE5-20, and SVE5-25 at concentrations as high as 0.046 mg/kg (SVE5- 25), and 1,2-DCAwas detected in soil sample SVE5-25 at a concentration of 0.024 mg/kg. While, three soil samples from boring EW-1 were analyzed for the fuel additives; no contaminants of concern were detected. SITE CONCEPTUAL MODEL v1.0. The lateral and vertical extent of dissolved hydrocarbons and the fuel additive 1,2-DCA are not defined. The lateral extent of dissolved hydrocarbons exceeds the limits of the investigation to date and the likely extends east of EI dorado Street and north of the site beyond a distance of 350 feet. Higher concentrations of dissolved hydrocarbons and the fuel additive 1,2-DCA are focused near the former UST#3 area and lesser at former UST #1/#2 area. GROUND WATER DEPTH AND GRADIENT Based on quarterly ground water monitoring events conducted by AGE, depth to ground water at the property is approximately 20 feet to 30 feet below surface grade (bsg). The prevailing ground water flow direction is generally northeast, although flow directions may vary locally and seasonally. Depth to first encountered ground water at the property during the last quarter was measured to be approximately 27 feet bsg. HYDROGEOLOGIC UNITS Based on cross sections A-A'and 8-8', AGE informally identified five hydrologic flow units, located between first encountered ground water and 199 feet bsg, as having significant intervals of apparently porous, coarser-grained soil separated by intervals of finer-grained, less permeable soil. Hydrogeologic Unit 1 (HU-1)was subdivided into three sub-units(HU- 1 Upper Zone, HU-1 Middle Zone, and HU-1 Lower Zone) that may not have significant barriers to vertical migration of contaminants. Generally, HU-1 Upper Zone was identified at depths between 25 feet (first encountered ground water) and 51 feet bsg; HU-1 Middle Zone was identified at depths between 48 feet and 75 feet bsg; HU-1 Lower Zone was identified at depths between 60 feet and 90 feet bsg. Hydrogeologic Unit 2 (HU-2) was identified at depths between 112 feet and 125 feet bsg and consists primarily of a continuous layer of sand. Hydrogeologic Unit 3 (HU-3) was identified at depths between 140 feet and 160 feet bsg and consists primarily of a continuous layer of sand. Hydrogeologic Unit 4 (HU-4) was identified at depths between 160 feet and 175 feet bsg Advanced GenEnvirontnental,Inc.