COMPLIANCE INFO - Laserfiche WebLink

Home Browse Search

kn K L E I N F E L D E R 4 DISCUSSION AND RECOMMENDATIONS 4.1 HYDROCARBON SURFACE STAIN AREAS During the preliminary soil sampling investigation conducted in June 1988. TPH concentrations were detected in shallow soil samples collected at HS-1, HS-2, and HS-4. The highest concentration were detected at areas HS-1 and HS-4. The TPH concentration at HS-1 dropped from 5,600 mg/kg at 1.5 feet to below laboratory detection limits at 4.5 feet. At HS-4, the TPH concentration dropped from 1,100 mg/kg at 1.5 feet to 270 mg/kg at 5 feet. During the November 1988, second phase investigation, soil samples were collected from the center of the three hydrocarbon stained areas. TPH was only detected at 60 mg/kg in the soil from the center of HS-1 at a depth of 5 feet. TPH and BTEX concentrations were below laboratory detection limits in the three water samples collected from the wells installed through the HS area central borings. Radial borings were advanced around the central borings at HS-1 and HS-4 to assess the lateral presence of contamination. TPH concentrations in the radial boring samples were below laboratory detection limits except for 27 mg/kg in the soil sample collected from HS- 4, B-3 at a depth of 5 feet. The significant decrease in TPH concentrations in the unsaturated soil and the lack of TPH or BTEX constituents in the ground water samples indicate that the surface hydrocarbon stains at HS-1, HS-2, and HS-4 have not had an adverse impact on shallow ground water. Kleinfelder does not recommend additional soil or ground water assessment in these areas. Prior to initiating construction or development activities at the site, Kleinfelder recommends the hydrocarbon-stained soil at HS-1 and HS-4 be excavated and properly disposed of at an appropriate landfill. HS-1 and HS-4 had TPH concentrations over 1,000 mg/kg in the shallow soil samples, and therefore the soil would be considered a hazardous waste. A preliminary estimate of the soil requiring excavation is approximately 50 to 75 cubic yards from each of the two HS areas. Additionally, the ground water monitoring wells should be properly abandoned according to SJLHD requirements. 161-89-107 11