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Phase 11 Additional Subsurface Investigation Tracy Corners Shopping Center 3225 North Tracy Boulevard Tracy,California 95376 Partner Project Number 14-129814.3 January 27,2015 Page 12 Phase 1, Quality Cleaners had a projected tenant term from April 1992 to September 2007 at the subject property. A dry cleaner checklist completed by A/E indicated that one floor drain was present in a room adjacent to the dry cleaning machine and was connected to the sewer system. In addition, the dry cleaning machine was manufactured in 1991. Partner noted during the Phase I investigation completed in December 2014, that according to an interview with the property manager,this site has operated as a dry cleaning facility since 1992. Although the current closed-loop dry cleaning machine (installed in 2007) uses a hydrocarbon-based solvent (DF- 2000 Aliphatic Hydrocarbon Fluid) for dry cleaning purposes, the prior tenant used a closed-loop dry cleaning machine (operational from 1992 to 2007) that used chlorinated solvents, particularly PCE, during the dry cleaning process. Chlorinated solvents (a.k.a. chlorinated volatile organic compounds [CVOCs]) are highly mobile chemicals that can easily accumulate in soil. These solvents, even when properly stored and handled, can readily migrate into the subsurface as a result of small releases associated with on-site operations. During Partner's Phase I investigation in December 2014, two 55-gallon steel drums (one containing new DF-2000 Aliphatic Hydrocarbon Fluid and one containing dry cleaning process waste sludge) were observed adjacent to the dry cleaning machine. Steel secondary containment was noted around the dry cleaning machine. In addition, no significant staining or cracking was observed in the area around the dry cleaning unit or around the hazardous waste storage area. According to the most recent waste manifest on-site, Technichem, a licensed transporter of hazardous waste, collects the waste sludge. According to the property manager, a prior subsurface investigation performed in 1999 indicated that soil beneath the dry cleaning tenant space had not been impacted by chlorinated solvents. However, based on the length of time between the prior subsurface investigation and the change from the PCE-based dry cleaning machine to the hydrocarbon-based dry cleaning machine (approximately eight years), the former use of chlorinated solvents represented a recognized environmental condition (REC). Partner completed a Phase II Report on December 19, 2014 for the Quality Cleaners unit in the Tracy Corners Shopping Center to investigate the potential impact of PCE and related CVOCs in sub-slab soil gas as a consequence a potential release or releases from the dry cleaning facility. The scope of the Phase II Investigation included the installation of four sub-slab soil gas points and the collection and analysis of four soil gas samples and one duplicate soil gas sample for PCE, trichloroethene (TCE), cis-1,2- dichloroethene(DCE),trans-1,2-DCE, and vinyl chloride. PCE was detected in each of the four soil gas samples and the one duplicate soil gas sample collected. Soil gas concentrations were converted into theoretical indoor air concentrations using the Department of Toxic Substances Control (DTSC) recommended attenuation factor. Applying the applicable DTSC foundation attenuation factor of 0.05 resulted in a calculated theoretical indoor air concentration of 165 micrograms per cubic meter(pg/m3) of PCE and 17.5 pg/m3 of TCE. The conversion resulted in indoor air concentrations above the DTSC recommended value for PCE of 2.08 pg/m3 at each of the four locations and above the EPA Regional Screening Level (RSL)for TCE of 3.0 pg/main one location (SG3). PARTNER