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KLEINFELDER i EPA, that can be used as screening tools to evaluate a site for potential human health risks. PRGs are calculated using standard assumptions and are specific for land use conditions (e.g. residential or industrial). The chemical concentrations calculated by the U.S. EPA typically correspond to a fixed level of risk (usually 10-6, or 1 in 1,000,000 cancer risk, or a non -cancer hazard quotient of 1) for soil, air, and water. The following exposure pathways were accounted for in the PRG calculation for soils assuring residential land use: • Ingestion • Inhalation of particulates • Inhalation of volatiles • Dermal (skin) absorption For the inhalation pathways, volatilization factors and particulate emission factors are used to estimate exposure due to emissions from soil to air. For the dermal absorption pathway, a 10% skin absorption factor was used to calculate the PRGs for the constituents of concern at the subject site. This factor assumes the dermal dose is equal to an adult's ingestion dose. The soil results were also compared to Title 22 Total Threshold Limit Concentration (TTLC) Regulated Level for classification of hazardous wastes per 22CCRk�66261.24.) Additionally the groundwater results were compared to Maximum Contaminant Levels (MCLs) also contained within Article 4 and 5.5 of Title 22. Based upon review of the reported iialytical results with the aforementioned regulated values and Preliminary Remedial Goals (PRGs), no reported levels of the requested analytes were found above the regulated levels and goals summarized in Table 1 (See Table 1 under the Tables Tab of this report). Based upon these comparisons it appears that the concentrations remaining in the confirmation samples from Disposal Sites B and C have not adversely impacted soil and groundwater in the areas investigated. 20-3978-03.W36/2019766 Page 16o1'20 © 1999. Kleinfelder. Inc. September 9. 1999