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No Further Action Required Request Report <br /> Tracy Byron Road-Tracy,California December 1,2011 <br /> 4. CONCLUSIONS AND RECOMMENDATIONS <br /> SAIC identified the presence,and delineated the extent,of TPH in soil and groundwater near the <br /> former OVP and TAOC pipelines during past site investigations. At least 30 years have elapsed <br /> since the pipeline systems were decommissioned,and the plume size has stabilized and may now <br /> be shrinking as natural attenuation continues to degrade TPH in soil and groundwater. 1 <br /> Consistent with SWRCB Resolution No. 92-49,Section M.A through C, SAIC evaluated 1 <br /> alternative cleanup technologies and found that all technologies other than natural attenuation <br /> would be ineffective, infeasible,and costly given the nature of the crude oil in soil and <br /> groundwater. COPCs at the Site will naturally attenuate over time to below WQOs. There are <br /> no current or anticipated future uses of the shallow groundwater due naturally occurring high <br /> TDS concentrations, likely low yield,and the availability of alternative water supplies. The <br /> HHSE demonstrated that COPCs do not pose a threat to potential residents. It is unlikely that <br /> sensitive receptors near the Site have been significantly affected by on-site soil and groundwater. <br /> CEMC requests that the Central Valley RWQCB issue an NFAR letter for this low-risk site for <br /> these reasons. <br /> This report contains the technical data and rationale necessary to support a decision by the 1 <br /> Central Valley RWQCB to issue an NFAR letter for the Site. SAIC prepared this report taking <br /> into consideration the documentation outlined in Appendix A of the Tri-Regional <br /> Recommendations. CEMC requests that the Central Valley RWQCB issue an NFAR letter for <br /> this low-risk site for the reasons provided in this report and summarized in this section. <br /> & REFERENCES <br /> Cal/EPA, 1999. Preliminary Endangerment Assessment Guidance Manual, Department of Toxic <br /> Substances Control. June. <br /> DFG, 2010. California Natural Diversity Database. March. <br /> DWR, 2003 updates Bulletin 118. California's Groundwater-Bulletin 118 Update 2003. <br /> October. <br /> 2006. Lines of Equal Elevation of Water in Wells,Unconfined Aquifer, San Joaquin <br /> Valley. Spring. <br /> EPA,2008. Regional Screening Levels for Contaminants at Super <br /> und Sites, September 12, <br /> 2008. http://www.eva.goy/repionO9/suDerfimd/rsl/index.html. September. <br /> RWQCB (Central Valley Region), 2004. Appendix A—Reports Tri-Regional Board Staff <br /> Recommendations for Preliminary Investigation and Evaluation of Underground Tank <br /> Sites. April. <br /> (Central Valley Region), 2008- The Water Quality Control Plan (Basin Plan)for the <br /> Sacramento River Basin and the San Joaquin River Basin,4th ed. February. <br /> (Central Valley Region), 2011. Review—Human Health Screening Evaluation, Tracy <br /> Byron Road Property, Tracy,San Joaquin County, CA. August. <br /> RWQCB(San Francisco Bay Region),2008. Screening for Environmental Concerns at Sites <br /> with Contaminated Soil and Groundwater(Interim Final). May. <br /> 10 <br /> SAIE <br /> 1 <br />