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Phase D Subsurface Investigation Tracy Comers Shopping Center 3225 North Tracy Boulevard Tracy,California 95376 Partner Project Number P14-129814.2 December 19,2014 Page 12 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 completed a Phase I report on December 9, 2014. During Partner's on-site investigation, Partner noted the presence of a dry-cleaning tenant known as Quality Cleaners. 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 closed-loop dry-cleaning machine (operational from 1992 to 2007), used chlorinated solvents, particularly PCE, during the dry-cleaning process. Chlorinated solvents (a.k.a. CVCCs) 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 onsite operations. Partner observed two 55-gallon steel drums (one containing new DF-2000 Aliphatic Hydrocarbon Fluid and one containing dry-cleaning process waste sludge) 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 represents a recognized environmental condition. Geology and Hydrogeology Based on a review of the United States Geological Survey (USGS) Union Island, California Quadrangle topographic map, the subject property is situated at an elevation approximately 22 feet above mean sea level, and the local topography is sloping gently to the southwest. Please see Figure 2 for a topographic map of the site vicinity. The subject property is situated within the Sacramento Valley plain of the Great Valley physiographic province of the State of California. The uppermost geologic formation underlying the soils at the subject property is the Pleistocene Age San Joaquin formation. The San Joaquin formation comprises the underlying stratigraphy and consists mostly of clay loam deposited in stream channel, point bar, and fluvial environments. The thickness of the San Joaquin formation is estimated to be over 80 inches. Based on borings advanced during this investigation,the underlying subsurface consists predominantly of silty sands. The scope for this project only included sub-slab probes to a depth of 5 inches; therefore, boring logs were not completed for this investigation. PARTNER