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Final Baseline Human Health Risk Assessment <br /> i <br /> San Joaquin Human Services Agency Building <br /> December 2001 <br /> • 1E-06 (one in a one million) established by EPA Region 9 and used by Cal EPA DTSC as well <br />' as the one in a hundred thousand (1E-05) significant risk level established by Proposition 65 <br />' under the Safe Drinking Water and Toxic Enforcement Act of 1986 Additionally, the hazard <br /> level (1 lE-3) is below the acceptable risk level of one (< 1) Detailed risk-based calculations <br />' using the site-specific input parameters are presented in Appendix A <br />' 4.0 CONCLUSIONS <br /> The evaluation of potential indoor air risks to occupational workers via the migration of benzene <br />' vapors from the groundwater beneath and adjacent to the San Joaquin Human Services Agency <br /> Building indicate acceptable risks using a combination of default and site-specific parameters <br />' These results are based on site-specific building data and a conservative exposure point <br /> concentration estimate for benzene <br />' <br /> 5.0 REFERENCES <br /> lie ASTM 1995 Standard Guide for Risk-Based Corrective Action Applied at Petroleum Release <br />' Sites ASTM Designation E 1739 — 95 <br /> California Environmental Protection Agency (CaIEPA) 1996 Department of Toxic Substances <br />' and Control 1992 Supplemental Guidance for Human Health Multimedia Rask Assessments of <br /> Hazardous Waste Sates and Permitted Facilities (Corrected and Reprinted) August 1996 <br />' California Department of Toxic Substances Control, 1994, Preliminary Endangerment <br /> Assessment Guidance Manual <br />' Environmental Quality Management, Inc (EQM) 2000 User's Guide For The Johnson and <br /> Ettinger (1991) Model for Subsurface Vapor Intrusion Into Buildings (Revised) December <br /> 2000 <br />' Groundwater Services Inc GSI 1997 Tier 1 and Tier 2 RBCA Spreadsheet System Version <br />' 1 01 <br /> Johnson, P C and Ettinger, R A 1991 Heuristic Model for Predicting the Intrusion Rate of <br /> Contaminant Vapors into Buildings Environmental Science and Technology, Vol 25, No 8, <br /> 1991 <br /> • <br /> I <br />' San Joaquin County GW Monitoring Report2(Appendix D)v 2 10 12/27/2001 <br />