ARCHIVED REPORTS_ROY'S AUTO - HISTORICAL (2)

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Prior to the ROW acquisition, Kaldveer Associates (Kaldveer) performed a soil quality investigation for CalTrans on the eastern portion of the site shown on Figure 2. Based on the results of the DHS and Kaldveer sampling, the Superior Court ordered the owners of the property to conduct a soil investigation. 4_0 Hydrogeological Setting The site is located in the east central portion of Stockton, at the southwest corner of Miner Avenue and State Highway 99, in a mixed light industrial and residential area. The elevation of the site is approximately 26 feet above sea level. The ground surface in this area generally slopes gently to the west at about 5 feet per mile. The nearest surface water bodies are ephemeral and include the Stockton Diverting Canal, located a little less than one mile to the northeast, and Mormon Slough, located about 6,000 feet to the south. Based on published data, the current depth to groundwater beneath the site is estimated to be approximately 65 feet. Historical high groundwater (Spring 1986) is estimated to have been about 50 feet below grade. Groundwater flow in the site vicinity is expected to be generally easterly towards a large pumping depression on the east side of Stockton. As described by Kaldveer, the surface soil at the site consists of dark brown to black, organic rich clay from the surface to a depth of approximately 2-3 feet. Underlying this unit is a brown silty clay/clayey silt to a depth of approximately 7-8 feet. Beneath the brown clay, a red-orange silt is present to 10 feet, the maximum depth explored. Based on the boring advanced by hollow stem auger (HSA) by Ground Zero in February 1997, the uppermost three feet of soil at the site generally consisted of dark brown to black organic rich clay. Underlying this unit, brown silty clays and silts were found to a depth of 41 feet, the maximum depth explored. Groundwater was not encountered, however streaks of saturated clay were observed between the depths of 20 and 28.5 feet. The saturated streaks in this boring are attributed to the proximity of a septic system seepage pit. 5.0 Investigation by Kaldveer In June 1991,Kaldveer drilled 33 exploratory soil borings in the ROW acquisition area to depths of 10 feet below ground surface (bgs). Soil borings were located in a grid-like pattern, but some were moved to locations of apparent staining. Three near-surface soil samples collected by hand, and a total of 66 soil samples collected from the borings at depths of 1 and 4.5 feet bgs were submitted to a CalTrans-approved laboratory. Selected samples were analyzed for total recoverable petroleum hydrocarbons (TRPH), total petroleum hydrocarbons as gasoline and rays\torts\summary 2