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Patricia Bonnifield Page 3 October 20, 2003 surface soil results were also compared to 2002 Residential and Industrial Preliminary Remediation Goals (PRGs).2 PRGs are risk-based concentrations that are intended to assist individuals in initial screening -level evaluations of environmental concentrations of chemicals. Generally, if a site concentration of a chemical is below its PRG, the chemical is not considered to pose a potential health threat. The pre -excavation samples taken by SJCEHD showed that the used sandblast grit contains levels of copper that would result in this material being classified as a Non-RCRA hazardous waste. The results for the sandblast debris/soil mixture (sample SBD on Table 2) indicate that the excavated soil does not need to be managed as neither a characteristic RCRA (federal) nor a Non-RCRA (California) hazardous waste. Disposal of this material may be allowable in a Class III landfill if the levels of metals are consistent with the individual landfill's waste acceptance criteria. Among the 17 metals for which the three confirmation soil samples were analyzed, arsenic, cadmium, copper, molybdenum, and silver occurred at a concentration above the general soil level (based on the California data set) in one or more samples. We believe that these metals are not derived from sand blasting activities, because the concentration of these same metals in the sandblast debris sample (SBD) are substantially lower then California data set. Therefore, the site concentrations of arsenic, cadmium, copper, molybdenum, and silver are naturally occurring. Entire Buckley Cove area including Ladd's Marina was created by man- made fills in the 1940's from a variety of sources. Fill from river dredging and imported soil from the greater Stockton area was used to create the landmass on both sides of Buckley Cove Way. As such it would not be considered unique for some of the metals to exceed the levels observed in the California data set. The PRGs were used to assess the potential health significance of the chemical residuals in the soil. Except for arsenic, the concentrations of all the metals were at least 5 -fold below both the applicable residential and industrial PRGs. The concentration of arsenic in the site soil is greater than both the residential and industrial PRGs. However, the natural levels of arsenic in California soils also are above the PRGs. As noted above, the concentrations of arsenic at the site are very close to the range that is typically seen in California soil. Thus, the risks associated with the arsenic in the soil are consistent with ambient health risks. The potential for impacted soil to reach a surface water was considered by evaluating the topography of the site. The sandblast area is located approximately 100 feet away from the closest surface water body. Although topographically higher than the surface water, the area immediately adjacent to the sandblast area slopes inward toward the sandblast compound. z U.S. Environmental Protection Agency, Region 9. 2002. Preliminary Remediation Goals. Available on the Internet at http://www.epa. og v/region09/waste/sfund/prg/index.htm CAWINDOWS\Temporary Internet Files\Content.IE5\UTCIOUZE\Ladd's Investigation Report[1].doc