SITE INFORMATION AND CORRESPONDENCE

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t+ k Project F11ioslDobler Annexation and Development p 1 i TRACY Environmental Impact Report Inc. prepared two soil management plans, in December and investigations, Geomatrix Consultants, August of 1999 for portions of the Project site as art of a previous development project proposed. _ According to letters issued by the DISC, RWQCB and the EHD, no further investigation was required a result of pipeline im acted soils. However, these agencies for these onsite properties, at that time, as p p p have noted that any .changes in the .present or proposed .use of the site_may.require. further site characterization and mitigation activity.: Per an interview conducted with Mr. tlMichael Infurna_of the.— EHD, the soil management plans previously,prepared for the Project site do not consider vapor intrusion impacts. Due to the known level of past contamination at the Project site, Mr..Infurna advised that the i. site characterization and extent of contamination at the Project site be updated for.pre sent day conditions. Mr. Infurna also recommended further vapor intrusion investigations for the Project site, as it applies to onsite contaminated soils. With implementation'of Mitigation Measures 4.10-1d, a qualified Site Characterization specialist would be required to conduct updated site characterization at the Project site prior to issuance of building permits, in consultation with Chevron and EHD, with regard to onsite contaminated soils associated with adjacent'pipeline leaks. Upon completion of site characterization activities, remedial activities, if necessary, would be recommended.in consultation with EHD. Also,prior to issuance of building permits, vapor intrusion investigations would be required to be conducted 'by a qualified Environmental I Professional, in consultation with the EHD (Mitigation Measure 4.10-1e). Should the Environmental Professional determine that proposed buildings could be impacted by vapor intrusion, the Environmental Professional, in consultation with EHD, would recommend specific design measures to be incorporated I into the buildings' design that would'reduce these indoor air,quality concentrations to below regulatory thresholds, as directed by EHD. With implementation of itigation Measures 4.10-1d and 4.10-1e, impacts to persons at the-Project site as a result of offsite pipeline leaks would be reduced to less than significant levels. E Based on the EHMCA, a known third-party diesel spill occurred'at ATN 209-27-014 (immediately E adjacent to the Project site) in March 2008.. 'The diesel spill occurred when a big-rig truck traveling in dense fog on West Grant Eine Road crossed West Byron Road and crashed. 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 werereportedly excavated to . approximately 10 to 12 -feet bgs, the adjoining up-gradient offsite property to the south reported concentrations in the groundwater as a result of this spill.-Thus, this offsite spill has potentially resulted in groundwater contamination to the Project area. .Wth implementation of Mitigation Measure 4.10-1e, vapor.intrusion investigations would be required to consider potential impacts as a result of contaminated groutidwater. Also, with implementation of Mitigation Measure 4.10-1f, construction worker safety ' would be 'minimized through implementation of a Worker Safety Plan that would outline specific measures that would be taken by personnel in the event that potentially contaminated groundwater is encountered. According to the 2005 UWMPt,Tracy provides water services to all of its residents within the City limits. Surface water has historically comprised between 50 to.60.percent of the City's total water supply. The City's two wholesale surface water supply suppliers are the U.S. Bureau of Reclamation (USBR) and the South San Joaquin Irrigation District(SSJID). Additional water comes from the Delta-Mendota Canal the Stanislaus River and the Tracy Groundwater Sub-basin. Itis anticipated.that potable water for the project would be provided by existing water infrastructure, which is owned by the City. Therefore, it is not ' 2005 City of Tracy Urban Water Management Plan,dated December 2005 Draft•June 2011 4.14-13 Hazards and Hazardous Materials