SITE INFORMATION AND CORRESPONDENCE

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4 ,- -� lo. FilioslDobler Annexation and development Project t. TRACY Environmental Impact Report pipelines exist in the UPRR right-of-way. These include the'Kinder-Morgan pipeline and the Chevron Bay Area Pipeline(BAPL). Other pipelines may also exist in the vicinity. Siteinvestigations have been undertaken by Chevron of properties along the historical pipelines (which included portions_ of the Project site). Crude oil affected soil, later attributed to'the OVP/TAOC leaks, were identified. Soil and Groundwater Investigations (Geomatrix,.March 1999), Site Closure Requests and Soil 1. Management Plans (Geomatrix, August 1999, Geoinatrix December 1999,'Geomatrix, September 2001).have been prepared for the Project site (APNs 209-27-025 and -030). Based on these reports,'very limited petroleum hydrocarbon-affected soil was encountered at four to 15 feet below ground surface (bgs). Detected constituents (pyrene and'chrysene) were below their respective residential preliminary rernediation goals (PRGs).established by the-U.S.,Environmental_Protection_Agency-(EPA),-indicating, that the presence of.these constituents in soil at the site do not pose an unacceptable risk to future onsite' residents .. Also, the concentrations of detected benzene,:toluene, ethylbenzene, xylenes and polycyclic 't aromatic hydrocarbons (PAHs) were below their respective PRGs, also indicating that the presence of ! these constituents in soil at the site, including the potential fort additivity due to multiple constituents, do not pose .an unacceptable risk to the health of future onsite residents. There were no detections of dissolved petroleum constituents in groundwater. According to letters issued by the.Depariment of Toxic Substance Control (DISC), Regional Water :.: . . mental Health Department EHD ,Quality Control Board (RW CB) and the San Joaquin CountEnviron no further.investigation is required for this site due to pipeline impacted soils. It is noted that any changes in the precentor proposed use of the site may require further site characterization and mitigation activity. Per an interview conducted on August 10,2010,with Mr.Michael Infuriia of EHD, the Soil Management Plans previously prepared.for the Project site do not consider vapor intrusion. Due to the known level of past contamination at.the Project site, Mr. Infurna advised that the site characterization and extent of contamination at the Project site be updated.for present day conditions. Mr. Infuma also recommended i further vapor intrusion considerations,as it applies to onsite contaminated soils and was not considered as part of past investigations. Although there is a.known presence of hazardous materials contamination in.onsite soils along the southern portions of the Project site,these detected concentrations do not pose an unacceptable risk to the health of future onsite residents, as detennined u1 1999. However, recent changes to the regulatory framework, as applicable to the Project, currently require further investigations to potential onsite.vapor intrusion that may result from onsite contaminated soils.. Thus,these historic spills associated with offsite petroleum pipelines have resulted in soil contamination at the Project site and may have resulted in a potential vapor intrusion condition at the Project site. } � ' Per additional investigations documented in a report dated�Jivary 2 09, a known third-party diesel spi11 on APN 209-27-014 (immediately adjacent to the OVP) may have contributed to contamination at this site• The diesel spill occurredwhen a big-rig traveling dense fog West Grant Line Road crossed West Byron Road and crashed on APN 209-27-014 in March 2008. A purported 140 gallons of diesel leaked from the ruptured fuel tank onto surface soil. To address the diesel spill, 130 cubic yards of affected soil were reportedly excavated by a third party to approximately 10 to 12-feet bgs. Groundwater was encountered at the bottom of the excavation, but a grab groundwater sample was not collected prior to backfill. : Although approximately 130 cubic yards of affected soil were reportedly excavated to approximately 10 to 12 feet .bgs; the adjoining up-gradient offsite property to the south reported k Draft•June 2019 4.10-3 Hazards and Hazardous Materials IM. ..