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10 May 1999 S AGE-NC Project No 95-0111 Page 4 of 6 31 STRATIGRAPHY Tan silty clay and utility backfill were encountered in the investigation area Sitty clay was distributed from the surface to 15 feet bsg in soil boring MW7 Silty clay was distributed from the surface to 10 feet bsg in soil boring MW8 and pea gravel was encountered from approximately 10 feet bsg to above 15 feet bsg The gravel was underlain by silty clay to the total depth of the soil boring at 15 feet bsg A stratigraphic cross section of the soil at the site is depicted in Figure 3 3 2 LABORATORY RESULTS OF SOIL SAMPLES TPH-g was detected in one of the six soil samples analyzed TPH-g was detected at a concentration of 5 7 milligrams per kilogram(mg/kg)in soil sample BMW7-10 Xylene was detected in the same soil sample at a concentration of 0 015 mg/kg Soil samples collected and analyzed from depths of five feet and ten feet bsg in the same boring had detectable TPH-d at concentrations of 16 mg/kg and 3 0 mg/kg, while the soil sample from a depth Iof 15 feet bsg had no detectable petroleum impact TPH-d was detected in the soil analyzed from boring B-VIW8 at a depth of ten feet bsg at a I concentration of 140 mg/kg, while TPH-d was not detected in the soil from a depth of 15 feet bsg in the same soil boring Oxygenated compounds were not detected in the soil samples analyzed Analytical results of soil samples are summarized in Tables 1 and 2 The laboratory report (MAI Laboratory ID 02111 through 02116), quality assurance and quality control (QA/QC)reports and chain-of-custody form are in Appendix C I 3 3 GROUND WATER FLOW DIRECTION AND GRADIENT I The relative ground water elevation in each well was calculated by subtracting the depth to ground I water from the surveyed relative casing elevations The depths to ground water and relative ground water elevations are tabulated in Table 3 All existing wells were surveyed relative to the casing of monitoring well MW-1,which had been assigned an arbitrary casing elevation of 20 feet The depth I to ground water ranged from 6 30 feet below the well casing (bwc) in MW-4 to 9 50 feet bwc in MW-1 The relative ground water elevation at the site ranged from 10 21 feet in MW-5 to 11 57 feet in MW- 6 The relative ground water elevation increased an average of 0 33 feet over the last quarter The inferred ground water flow direction at the site was towards the northeast, consistent with results ' Advanced GeoEnvironmental Inc. I