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l _ __ _ Site Background Information - Fernando's Place AGE-NC Project No. 00-0769 Page 3 of 4 The fuel additives DIPE, ETBE, MTBE, TAME, TBA, EDB and 1 ,2-DCA were not detected in the soil samples collected and analyzed from the three soil borings. Additional volatile organic compounds (VOCs) detected in the analyzed samples included isopropylbenzene, n-propylbenzene, 1 ,3 ,5-trimethylbenzene, 1 ,2,4-trimethylbenzene, p-isopropyl-toluene, and naphthalene. 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 uncross sectionsA-A ' andB-B ', AGE informally identified five hydrologic flowunits, located between first encountered ground water and 199 feet bag, 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 (fust 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 and consists of a locally contained layer of sand. Hydrogeologic Unit 5 (HU-5) was identified at depths between 190 feet and 199 feet bsg and consists of a locally contained layer of sand. I HYDROCARBON-IMPACTED SOIL AND GROUND WATER Based on the analytical results of soil samples collected during the August and September 2002 investigation and previous subsurface investigations, cross sections illustrating the inferred vertical and horizontal extent of hydrocarbon-impacted soil were constructed: hydrocarbon-impacted soil appears to be defined vertically, although the lateral extent of impacted soil is not defined at the site. The most impacted soil was encountered beneath the former UST locations, to depths as great as Advanced GeoEnvironmental, tnc.