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' 12 January 2005 . AGE-NC Project No 97-0326 ' Page 5of11 ' 2 2 2 Collection and Analysis of Ground Water Samples Water samples were collected from each purged well using a pre-cleaned inertia pump after allowing ' the wells to achieve a minimum 80% recovery of the pre-purge water volume Each water sample was transferred into three 40-milliliter(ml)volatile organic analysis (VOA) vials containing 0 5 ml 18%hydrochloric acid as a sample preservative After collection,the samples were properly labeled, ' placed in a chilled container and transported under chain-of-custody to CTEL, a DHS-certified analytical laboratory, for analysis The samples were analyzed for • TPH-g in accordance with EPA Method 8015M, and ' 0 BTEX, MTBE, DIPE, ETBE, TAME, TBA, ethanol, methanol, 1,2-DCA and EDB in accordance with EPA Method 8260B 1 ' 3.0. FINDINGS The soil stratigraphy, ground water elevation, flow direction, and gradient were determined from field data, the contaminant impact to soil and ground water was quantified by the laboratory analytical data 31 STRATIGRAPHY ' Based on descriptions of soil samples collected from the soil borings, supplemented with soil composition data acquired from previous soil borings and cone penetrometer test (CPT) investigations, cross section A-A' was constructed depicting general lithology beneath the site ' (Figure 4) The sediments above 70 feet below surface grade (bsg) tend to be fine-grained soil With the exception of an approximately 3- to 5-foot gravel pad beneath the dispenser area, surface soil to a depth of approximately 10 feet bsg consists of a black, highly plastic clay Below 10 feet bsg, the sediments consist predominantly of alternating clayey silts, silty clays and clays, clay soil appears ' to increase eastward Laterally-discontinuous sand lenses of less than 60 feet in width were observed at depths of between 15 and 25 feet bsg and between 30 and 40 feet bsg beneath the site(Figure 4) ' Below 70 feet bsg is a cyclical sequence of laterally-continuous sand layers alternating with finer- grained sediments The laterally-continuous sand layers occur at an approximately 30-foot interval The uppermost sand, beginning at approximately 70 feet bsg, appears to be the most variable in terms of thickness,ranging from approximately 15 feet on-site to 5 feet off-site towards the east and • west The middle sand layer, at between 110 and 120 feet bsg, is approximately 12-foot thick west Advanced GeoEnvironmental,Inc 1