FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

20 October 1998 AGE-NC Project No. 98-0459 Page 6 of 7 station, and the general ground water flow direction in the area of the subject property,the impact to the subject property may have originated from the adjacent Exxon/Shell site: • However,the lack of detection of TBA in sample SP2,taken closer to the Exxon/Shell site does not directly support this possibility. It should be noted that the distribution of contaminants in the subsurface is controlled by preferential flow paths,which are not well understood for the subject property. • 8.1 ppb TBA detected in the ground water sample SPI exceeds the State of California maximum contaminate level (MCL) set at 0.5 ppb. • Low to moderate concentrations of dichlorodifluormethane, a refrigerant or aerosol propellant,were detected in soil-vapor from the area of the former structures on the subject property. This suggests a release from the cooling and/or refrigeration systems formerly on the subject property. This compound was detected at a maximum concentration of 110 ppb in the vapor samples analyzed for chlorinated compounds. • This chlorinated compound,dichlorodifluormethane, is not regulated in a soil-vapor phase. 7.0. RECOMMENDATIONS Based on present site conditions, AGE recommends: • A more extensive subsurface investigation will be necessary to determine the lateral extent of the impacted ground water on the subject property. • Based on the inference of an off-site origin of the TBA impact in the ground water beneath the subject property,any additional subsurface investigation related to this compound should be performed by the responsible party,the operator/owner of the Exxon/Shell station. 8.0. LIMITATIONS Our professional 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 upon analytical results provided by an independent laboratory. Evaluations of the geologic/hydrogeologic conditions at the subject property for the purpose of this investigation were made from a limited number of available data points (i.e. soil vapor, ground water samples) and subsurface conditions may vary away from these data points.No other warranty, expressed or implied, is made as to the professional recommendations contained in this report.