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GROUND WATER INVESTIGATION WORK PLAN BULK TERMINALS SITE, PORT OF STOCKTON, STOCKTON, CALIFORNIA bulk terminals site in addition to the current stockpiles to the north (Figure 3). Coal was stockpiled prior to 1991 in the area now occupied by Bay Sulfur; aerial photos indicate this coal was not present in 1982, but had been stockpiled by 1989. Petroleum coke was stockpiled from approximately 1989 to 2001 in the southeastern area of the site formerly leased by Koch-Carbon. 2.1.3 Historical Operations — Copper Concentrate From 1988 to approximately 1994, Metropolitan loaded copper concentrate onto vessels at the bulk terminals site. Although copper concentrate was not normally stored at the site, a rail transfer area near the center of the site (Figure 3) represents a potential source for elevated copper in shallow soils. 2.2 PREVIOUS SOIL AND GROUNDWATER INVESTIGATION Dames and Moore prepared a Phase I Preliminary Site Investigation (1991a) and a Baseline Investigation Report (1991b) for Metropolitan Stevedore in the southern portion of the bulk terminals site. As part of the 1991 Baseline Investigation, Dames and Moore sampled seven hand-augered soil borings and installed four ground water monitor wells (MW-1 through MW- 4; Figure 4). In 2003, TRE Consulting, of Stockton, California, resampled the ground water monitor wells and prepared a sampling and analysis report of results (TRE, 2003). Significant findings from these investigations are summarized below: 2.2.1 Soil sampling results - 1991 Soluble copper and lead (California Waste Extraction Test) were reported in 1991 in soil samples from 0.5 feet below ground surface (bgs) in the former copper concentrate transfer area and along the conveyor system easement in the northern portion of the site (Figure 4). Soluble copper was reported at 638 mg/L from soil (extract) in boring B-3, 568 mg/L at boring B-5, 247 mg/L at boring B-4 and 571 mg/L at boring B-6). Soluble lead was reported at 11.1 mg/L in soil (extract) from boring B-5 at 0.5 feet bgs. Soluble lead was undetected in all other samples. Total Recoverable Petroleum Hydrocarbons (TRPH; EPA Method 418.1) were reported in 1991 in 11 of 14 soil samples collected from the Metropolitan Stevedore and the conveyor system easement (borings B-3, B-4, B-5, B-6, B-7, MW-1, and MW-4; Figure 4). Reported concentrations ranged from 29 mg/kg at MW-1 to 190 mg/kg at B-4. In 1991, elemental sulfur (EPA Method 6010) and sulfates (EPA Method 300) were reported at concentrations of 737 mg/kg and 9,400 mg/kg, respectively, in soil samples from 0.5 feet bgs at MW-1. Sulfur and sulfate concentrations appeared to be highest in surficial soils in 1991. July 2005 Page 4 Environmental Risk Services Corp.