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' 10 May 2004 • AGE-NC Project No. 98-0520 tPage 4 of 6 The samples B5-20 and 135-30 were described as brown sandy clay and a gray clay (silty), with - ' porosities at between 46% and 47.71/o,low organic content (1.2 to 1.4%), and a specific gravity of 2.72. The geotechnical laboratory report(Cooper Testing Lab-ID #255-035) and chain-of-custody form are included in Appendix C. t4.2 ANALYTICAL RESULTS OF SOIL AND GROUND WATER SAMPLES A total of nine soil samples and four grab ground water samples were submitted to, CTEL for ' analysis listed in Section 3.2.No target analytes were detected at or above laboratory detection limits in the samples analyzed.Analytical results of soil samples are summarized in Tables 1 and 2.Copies of the laboratory report (CTEL. Project No. CT214-0401022) and chain-of-custody form are ' included in Appendix D. 5.0. SITE CONCEPTUAL MODEL Based on the data collected to date from soil borings and monitoring well installations, AGE has lie developed a site conceptual model for the release,migration and distribution of the contaminants in the subsurface as described below: ' The shallow stratigraphy is composed of an upper layer (Layer 1) of between 15 and 20 feet of yellowish to brownish green, generally unconsolidated, fine to medium sand, underlain by an ' approximately 15-foot thick clayey silt layer(Layer 2);northwards,Layer 2 appears to transition into a sandy silt or silty sand with clay, and beneath former USTs No. 1 and 2, a discontinuous lense of green to olive gray fine sand was identified near the top of Layer 2. The third layer (Layer 3), at ' below 35 feet bsg, appears to be an olive green to brown, unconsolidated coarse to pebbly sand;this layer was defined on.the basis of the four deepest soil borings (MW6, B 1,B5 and B6) located at the former USTs'No. 1 and 2 and.down gradient off-site to the north-west.(Figure 2). A geologic cross section is provided in Figure 3. Additional figures and tables can be found in the AGE-prepared ' Corrective Action Plan, dated 11 February 2003 (CAP). ' Since initiation of ground water monitoring in December 1999,ground water elevations have ranged from approximately 13 to 19 feet above mean sea level. The ground water table underlying the site is generally in the form of a trough-like depression, with the base of the trough plunging northwest ' a low gradient of less than 0.01 ft/ft. Releases of petroleum hydrocarbons occurred from the on-site USTs. Once released to the ' subsurface,the contaminants migrated through the sandy Layer 1 to a vertical depth of approximately .20 feet bsg, at which point the contaminants encountered the less permeable clayey silt of Layer 2.. 1 Advanced GeoEnvlronmental,Inc. t