ARCHIVED REPORTS_XR0011440 - Laserfiche WebLink

Home Browse Search

27 September 1999 AGE-NC Project No. 97-0327 Page 8 of 9 • Laboratory and field data suggest that TPH-g and TPH-d impacted ground water is present in the area of P-8. • The State of California drinking water standards, adopted under the Safe Drinking Water Act, have established maximum contaminant levels (MCLs) for benzene, toluene, ethylbenzene and xylenes at 1 µg/l, 150 µg/l, 700 4g11 and 1,750 4g11; respectively. Concentrations of dissolved benzene and toluene detected in the grab ground water samples collected from P-8 were above selected MCLs. • The State of California Department of Health Services has adopted a concentration of 13 µg11 as an action level (ALs) for MTBE in March 1999, and has adopted a concentration of 5µg/1 as a secondary maximum contaminant level (MCL) in January 1999. Concentrations of dissolved MTBE detected in the grab ground water samples collected from P-8 were above both the AL and MCL. • The horizontal and vertical extent of petroleum hydrocarbon-impacted soil has not been fully delineated north and east of P-8. • The horizontal and vertical extent of petroleum hydrocarbon-impacted ground water has not been fully delineated in any direction. 6.0. RECOMMENDATIONS iBased upon data collected from the site, AGE recommends: • Additional investigation to deten-nine the lateral and vertical extent of hydrocarbon-impacted ' soil and ground water at the site. Further assessment is warranted north and east from the known petroleum hydrocarbon-impacted area. • Installation of ground water monitoring wells to provide repeatable ground water sampling locations, determine site-specific ground water flow direction and gradient, and to document petroleum hydrocarbon concentration trends. ' A search for all potential ground water receptors within a 2,000-foot radius of the site.. 7.0. LIMITATIONS Ourp rofessional services were performed using that degree of care and skill ordinarily exercised by environmental consultants practicing in this or similar localities. The findings were based mainly ' upon analytical results provided by an independent laboratory. Evaluations of the geologic/ Advanced GcAnvironmental,Inc.