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Californi., ,gional Water Quality Co .l Board <br /> Central Valley Region <br /> Robert Schneider, Chair <br /> Linda S. Adams Arnold <br /> Secretrtn or Sacramento Main Office Schwarzenegger <br /> Enrironntt,nta/ 11020 Sun Center Drive#200. Rancho Cordova_California 95670-6114 Govermn <br /> Protecnon Phone(916)464-3291 •FAX(916)464-4645 <br /> http//wvww.Nvaterboards.cagov/Centrthalley 2M NOY 27 . AM If: 11. <br /> 20 November 2006 SAN .10AUiijil COUNTY <br /> ENVIRONMENTAL <br /> HEALTH DEPARTMENT <br /> Mr. Jim Levy <br /> Manager, Site Remediation <br /> Union Pacific Railroad Company <br /> 9451 Atkinson Street, Suite 100 <br /> Roseville, CA 95747 <br /> REBOUND AND REMEDIATION EFFECTIVENESS EVALUATION ADDENDUM WORK <br /> PLAN AND ADDITIONAL PRODUCT REMOVAL PROPOSAL, UNION PACIFIC RAILROAD <br /> COMPANY, TRACY MAINTENANCE FACILITY, SAN JOAQUIN COUNTY <br /> California Regional Water Quality Control Board, Central Valley Region (Regional Water <br /> Board) staff has reviewed the Rebound and Effectiveness Evaluation Addendum Work Plan <br /> (Workplan) dated 3 January 2006 and Additional Product Removal Proposal (Proposal) dated <br /> 28 August 2006 for the Union Pacific Railroad Company's Tracy Maintenance Facility. The <br /> Workplan proposes a sampling effort to address a request from Regional Water Board staff to <br /> assess the current concentrations of residual volatile organic compounds (VOCs) at the site. <br /> The Proposal recommends the implementation of a remedial alternative to enhance removal <br /> of total extractable petroleum hydrocarbons (TEPH) from site groundwater. Regional Water <br /> Board staff comments on the two documents are provided below. <br /> Workplan Comments: <br /> 1 . The Workplan proposes to collect soil vapor samples in Summa canisters from 15 points, <br /> including DPEX-01 through —08, SVEX-01 though —03, VMP-01-9', VMP-02-9', <br /> VMP-03-9' and VMP-04-9'. These wells were sampled during the 2002 rebound <br /> evaluation and provide a good basis for assessing changes that have occurred in the <br /> residual soil vapor contamination since that time. Regional Water Board staff believe <br /> UPRR should also collect soil vapor samples from VMP-01-5', VMP-02-5', VMP-03-5', <br /> VMP-04-5', VMP-05-5' and VMP-05-9' These additional samples are needed because <br /> UPRR has not collected soil vapor samples from the source area for approximately <br /> 4 years and a comprehensive assessment is needed. Also, California Human Health <br /> Screening Levels (CHHSLs) and San Francisco Bay Regional Water Quality Control <br /> Board environmental screening levels (ESLs) for vapor intrusion into indoor air are based <br /> on a soil vapor depth of approximately 5 feet-, therefore, samples from the shallow VMP <br /> screens (5-feet below ground surface) are needed for direct comparison to CHHSLs for <br /> VOCs and ESLs for total petroleum hydrocarbons. <br /> California Environmental Protection Agency <br /> P, He(I c/ed Pape, <br />