COMPLIANCE INFO - Laserfiche WebLink

Home Browse Search

`„u vte a a s e: presented in Appendix E through G. The QA/QC parameters for the samples were within acceptable limits and suggest that the data is useful for its intended purpose. 4.0 CONCLUSIONS & RECOMMENDATIONS The following conclusions and recommendations were based on the observations and data obtained during this LSI of the subject property: • The geophysical survey performed by NORCAL did not identify suspect features and/or buried metallic anomalies that are indicative of filling/service station equipment or USTs in the areas investigated. • No physical evidence of soil contamination was noted in the soil borings during this LSI with the exception of deep (approx 30 feet bgs)elevated PID readings in BV-2, with petroleum hydrocarbon odors in BV-3 and BV-4 that appear to be representative of subsurface groundwater conditions and capillary fringe soils. Concentrations of VOCs and TPH were not detected in the analyzed soil samples. No further action or investigation of soil at the subject property appears warranted at this time. • Detected concentrations of TPH-g in grab-groundwater samples do not appear to be significant. Gasoline range TPH compounds were only reported in grab-groundwater samples collected along the south subject property boundary. Elevated concentrations of TPH-d and TPH-mo range compounds appear to indicate one or more sources, especially since the most significant TPH-d concentrations in groundwater had patterns for Stoddard solvent and kerosene, which indicates various sources. Stoddard solvent and kerosene were commonly used as cleaning or degreasing compounds at automotive repair and other industrial facilities in the past. Stoddard solvent was also commonly used as a dry cleaning solvent in the past. TPH-mo concentrations in grab-groundwater samples were detected at somewhat higher concentrations than the TPH-d concentrations in the same analyzed sample. TPH in grab-groundwater samples was found to be elevated in the vicinity of the former on-site filling/service station but not in the upgradient sample BV-5. The low concentrations of TPH-g along with TPH-d results with non-standard patterns reported by the laboratory likely indicate aged releases from one or more sources that could have originated from on site and or off site. • Additional site characterization may be requested by SJCEHD to determine the source(s) of the TPH concentrations found in groundwater at the subject property and to confirm the reported concentrations. • The groundwater beneath the subject property is impacted with PCE and other degradation breakdown VOCs that appear to be associated with the upgradient dry cleaner facility located to the southwest. The highest concentrations of PCE in groundwater were detected along the south subject property boundary with much lower concentrations reported in grab-groundwater samples collected farther east and north on the subject property, indicating the more distal portion of the PCE plume is to the east and that the source area is upgradient to the west or southwest. Typical degradation products for PCE were also found in all of the analyzed grab-groundwater samples, including TCE, cis-1,2-DCE, and 1,2-DCA. Although the concentrations of these chlorinated compounds in groundwater were reported at concentrations that exceed an established MCL; no further action or investigation appears warranted because these detected compounds appear to be associated with an off-site release most likely the adjacent dry cleaning facility to the southwest. • In addition, reported concentrations of PCE in the analyzed soil vapor samples appear to indicate an upgradient and off site source. PCE concentrations were reported at much higher concentrations in the deeper(15 foot vapor samples)of the two vapor samples 9 Project Number 99008-008321.03