ARCHIVED REPORTS XR0000120 - Laserfiche WebLink

Home Browse Search

r PSC considers that the risk of petroleum hydrocarbons from this site affecting surface water bodies is unlikely Site data indicates that the plume of petroleum hydrocarbon impact is confined within the site's property boundary The distance to the nearest surface water body ' (900 feet) and its hydraulically upgradient location relative to the site makes it improbable that it would be impacted The onsite groundwater ingestion pathway is not complete because of the depth to groundwater and because Earthgram's utilizes a public water supply PSC considers that the offsite risk to water wells in the ' area is limited, based on groundwater modeling applied to the hydrocarbon plume While the plume of impacted groundwater may be confined within property boundaries, a groundwater fate and transport ' model was necessary to confirm that offsite well receptors would not be at risk The model is further discussed in Section 5 of this RACR ' The ingestion exposure pathway would also include the potential to ingest or eat impacted soil PSC considers the risk to the soil ingestion pathway as limited because a great mass of impacted soil was excavated at the time of the UST removals Further discussion of soil ingestion by potential receptors is summarized in Section 4 3 4.2.2 Inhalation Pathway An appraisal of the inhalation pathway includes the risk that petroleum hydrocarbons from soil and groundwater would volatilize and impact buildings (indoor air) and human health Factors to consider in assessing this pathway would include vaporization potential of the contaminants, surface cover, and extent and magnitude of impact Gasoline compounds by nature are typically volatile and readily ' transfer to a vapor phase However, PSC considers that the inhalation pathway is incomplete at this site due to the mass of soil that was excavated and the operation of the soil vapor extraction system ' Furthermore, the clayey nature of the subsurface, the site's pavement, and the slab-on-grade construction of the facility building serve as a barrier against organic vapors reaching the surface There have been no reports of petroleum vapors within the site building from Earthgrain's personnel Migration of vaporized contaminants into enclosed spaces, such as utility trenches and lines, is considered limited because the maximum depth of site utilities (sewer, water, electrical) is about three feet A 16 ' Remedial Action Completion Report The Earthgrains Company Facility 2651 South Airport Way Stockton,California ' Prepared For THE L'AAI HCRAINS COMPANY Prepared b) Philip Services Corp 11\ENV\62400132\121382CG\Stockton\Stockton\RemedialComplettonRepondm April 14 2003