ARCHIVED REPORTS XR0011879 - Laserfiche WebLink

Home Browse Search

:. ------ V w A S S O CIAT ES I N C . ...-fit extent is inferred. The extent of contamination to the north is defined by borings SB3 and SB5. E The extent of contamination to the west and the east are inferred. Dissolved petroleum hydrocarbons beneath the site appear to attenuate with distance from the central portion of the I� site as evidenced by analytical data summarized in Table 2. f 4 5.0 POTENTIAL RECEPTORS AND PATHWAYS 5_1 Potential Receptors At the request of the PHSIEHD, Smith Technology conducted a search of the Department of Water Resources (DWR) groundwater well construction logs to identify any groundwater wells -� located within one-half mile of the site. The search revealed thirteen wells located in the vicinity of the site. None of the thirteen wells are located close enough to the site to be considered potential receptors. Well logs for the on-site water supply well were not found in the DWR records. The on-site well is the closest potential receptor to the plume (within approximately 120 feet crossgradient of the plume). At the writing of this report, no data was able to be obtained F from the property owner, tenant or PHSIEHD concerning the well depth, screen interval or depth of seal. The potential receptors survey is detailed in Smith Technology Corporation's Additional Sod and Groundwater Report, Fayette Manufacturing Corporation, 7675 West Eleventh Street, Tracy, California, dated January 31, 1997. 5,2 Potential Pathways The site plan showing the facility and the utility lines under the site, as provided by the tenant, _. were examined for preferential pathways for the migration of contaminants. The building on site F- is constructed on a thick concrete pad, according to the property owner, and is located over a portion of the petroleum hydrocarbon plume. The pad would prevent any petroleum hydrocarbon rom migrating into the building. In addition, the open vapors located in soil under the building f areas of the site are overlain by asphalt which would be expected to impede vapor contamination pathways. Based on this information, there are no preferential pathways for the migration of contaminants. The preferential pathways were discussed in detail in Smith Technology Corporation's Additional Soil and Groundwater Report, Fayette Manufacturing Corporation, �.. , 7675 West Eleventh Street, Tracy, California, dated January 31, 1997. 6.0 DISCUSSION The following paragraphs summarize the results of the subsurface investigations performed at the project site. 1. The vadose zone, from 0 to approximately 8 feet bgs, consists of silty clay. The capillary fringe, from approximately 8 feet to 11 feet bgs, consists generally of silty to sandy clay. =' The soil beneath the capillary fringe, from approximately 11 feet to 25 feet bgs, consists generally of sand and silty clay. w:1951221reportslparcap.doc 6