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GRANITE CONSTRUCTION 2093357633 06/24/02 01:09pm P. 006 Because the concentrations of copper and lead exceeded ten times the Soluble Threshold Limit Concentration (STLC) in the two composite samples, the following additional testing was requested on August 17, 2001: ® Soluble Threshold Limit Concentrations (STLCs) using distilled water extraction for Copper and Lead by EPA 6000/7000 Series Methods The soil samples were submitted to Sequoia to perform these analyses on a regular turnaround schedule,usually requiring ten to fifteen working days for completion The analytical results are summarized in the attached Tables 1, 2 and 3 of this report.Total metal results are summarized on Table 1 and soluble metals are summarized on Table 3. The remaining analytical results are summarized on Table 2. From the list of analyses listed above ten metals (total metals), diesel range hydrocarbons, and four semi-volatile organic compounds from the EPA 8270 analyses were detected. The analyte pH ranged from 7.89 to 7.96 units. No volatile fuel constituents or soluble metals were detected at or above laboratory reporting limits. 4.0 DISCUSSION OF FINDINGS The analytical results from the list of analyses listed in Section 3 were compared as applicable to the California Code of Regulations 22CCR§66261.24 and/or Industrial U.S. EPA Region IX Preliminary Remediation Goals(DRGs), dated November 1,2000. Industrial PBGs were selected for comparison based on potential use of the leased propoerty for industrial purposes. DRGs are contaminant concentrations in environmental media (i.e. soil, air, water), calculated by the U.S. 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 I 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 assuming 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. A summary and Kleinfelder's findings and conclusions are as follows: 20-1108-33.001/2011 R 1188 Page 3 of 7 C 2001,Kleinfelder,Inc. October 17,2001