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' • 24 May 2001 ' AGE-NC Project No 96-0254 Page 3 of 4 31 STRATIGRAPHY ' Based on the findings from the CPT soil borings, cross section A-A' was constructed to depict general lithology beneath the site(Figure 3) Generally,the subsurface of the site from 1 foot bsg to approximately 70 feet bsg, was comprised mainly of silt, sandy silt, clayey silt, silty clay and clay Poorly graded sand, gravelly sand and silty sand layers were encountered from surface grade to approximately 1 foot bsg,36 feet to 40 feet(Sand Zone A)and 61 feet to 65 feet bsg (Sand Zone B) CPT computer-generated boring logs are included in Appendix A ' The deeper sand zones, Informally designated Sand Zone A and B are inferred to be the primary lateral migration paths of the dissolved contaminants The lateral continuity of the two sand zones in three dimensions is unknown ' 3 2 LABORATORY RESULTS OF "GRAB"GROUND WATER SAMPLES A total of four"grab"ground water samples were collected from CPT-1 and CPT-2 and submitted ' • for laboratory analysis for the above mentioned constituents TPH-g, TPH-d and BTEX compounds, detected only in the water sample collected from the ' upgradient Sand Zone B in CPT-2 (61 to 65 feet bsg), were present at concentrations of 110 micrograms per liter (Ecg1l) TPH-g, 85 µg/1 TPH-d, 2 4 µg/1 benzene, 3 3 µg/1 toluene, 1 3 µg/1 I ethylbenzene and 5 9µg/1 total xylenes Laboratory analysis of grab ground water samples collected from CPT-1 at depths of 26 feet to 30 feet, Sand Zone A (37 feet to 41 feet) and Sand Zone B (61 feet to 65 feet bsg)did not report any of the analytes at or above laboratory reporting limits ' Fuel oxygenated compound were not detected in the ground water samples The laboratory reports (MAI Lab 1 D 62602 through 62605) and chain-of-custody forms are presented in Appendix B Analytical results of the CPT "grab"ground water samples are summarized in Table 1 ' 4.0. SUMMARY AND CONCLUSIONS Based upon data collected on 13 March 2001,AGE concludes the following • Generally, the subsurface of the site from 1 foot bsg to approximately 70 feet bsg, was comprised mainly of silt, sandy silt, clayey silt, silty clay and clay Poorly graded sand, ' gravelly sand and silty sand layers were encountered from surface grade to approximately 1 • foot bsg, 36 feet to 40 feet (Sand Zone A) and 61 feet to 65 feet bsg (Sand Zone B) f Advanced GmEnwmamentnl,Inc