ARCHIVED REPORTS_XR0011440 - Laserfiche WebLink

Home Browse Search

n: . 27 September 1999 AGE-NC Project No. 97-0327 Page 7 of 9 5.0. SUMMARY AND CONCLUSIONS Based on review of a regional ground water elevation map published by the SJCFCD, the prevailing ground water flow direction in eastern Stockton is generally toward the northeast. Based upon data collected on 21 June 1999, AGE concludes the following: • First encounteredground water is approximately 52'/2 feet bsg; first observed saturated soil was identified at 55 feet bsg. • General lithology beneath the site is depicted in cross sectional view on Figures 3 and consists of brown, dry to saturated, fine sandy silt encountered from 15 feet bsg to depths of approximately 55 feet bsg. • Faint to intense petroleum hydrocarbon odor and vapor were noted in soil and grab ground water samples collected from probing P-8. • The approximate horizontal and vertical extent of petroleum-impacted soil-is depicted on Figure 4 based on laboratory data and field evidence noted on boring logs (i.e. vapor detection, petroleum odor). • TPH-g was detected in the 40-foot soil sample collected from boring P-8 at a concentration of 340 mg/kg. TPH-d was detected in the 40-foot soil sample collected From P-8 at a concentration of 37 mg/kg. The estimated extent of adsorbed TPH is depicted in cross sectional view A -A 'in Figure 4. • The laboratory reported that unmodified or weakly modified diesel is significant in the 40- foot soil sample collected from P-8. • BTEX compounds were detected in the 40-foot soil samples collected from the P-6 and P-8 at concentrations ranging as high as 20 mg/kg. • MTBE was detected in the 40-foot soil sample collected from P-8 at a concentration of 0.019 mg/kg. • TPH-g and TPH-d were detected in the ground water sample collected from P-8 at a concentration of 1,900 micrograms per liter(µg11); however, the laboratory reported that the diesel chromatograni for the sample did not have typical diesel characteristics. BTEX compounds were detected in the ground water sample at concentrations ranging as high as 310 ug/l; dissolved benzene was detected at a concentration of 230 µg11. • Dissolved MTBE was detected at a concentration of 51 µg11 utilizing EPA Method 8020 and • confirmed ata concentration of 52 µg11 utilizing EPA Method 8260. Advanced GeoEnvironmental,Inc.