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10 <br /> ENVIRONMENTAL HEALTH DEPARTMENT <br /> SAN JOAQUIN COUNTY <br /> Unit supervisors <br /> Donna K.Heran,R.E.H.S. <br /> 304 East Weber Avenue, Third Floor <br /> • ,,f ,j; Car] Borthan,R.E.E L5. <br /> sdike Huggins, R.EM.S.,8.17.1. <br /> •` :• Al Olsen,R.E.H.S. Stockton, California 95202-270$ Douglas W. Wilson,lt.l:•I I.S. <br /> Program Manager Telephone: (209) 468-3420 Margarel Lagorio, R.E.H.S. <br /> Q�rFOR Laurie A.Cotulla,R.E.H.S. <br /> Fax: (209) 464-{)l38 Robert McClcllon,R.E.H.S. <br /> Progrom Manager Mark Barcellos.R.E.H.S. <br /> 'JAN 2 1 ry 1" <br /> CARL NAVARRA <br /> 475 BLEWETT ROAD <br /> TRACY CA 95376 <br /> RE: Navarra Property SITE CODE: 1392 <br /> 7500 Eleventh Street <br /> Tracy CA 95376 <br /> San Joaquin County Environmental Health Department (EHD) has received and reviewed <br /> Groundwater-Quality Monitoring Report (QMR), dated December 2004, and Report on <br /> Extended Plume Definition (the Report), dated 20 October 2004, both prepared by your <br /> consultant The San Joaquin Company, Inc. (TSJCI). In addition, EHD and Mr. James <br /> Barton of the Central Valley Regional Water Quality Control Board (CVRWQCB) met with <br /> Dr. Dai Watkins and Mr. Bernie Dietz of TSJCI on 18 January 2005 to review the site <br /> te, As the meeting was held at the <br /> status and plan futureconsultant by corrective <br /> letter dated for the 15 December request of your mber 2004, EHD assumes you were <br /> aware of it taking place and chose not to attend. <br /> The Report included discussions of the historical use of the site, the site investigation and <br /> findings to date with maps showing the site and surrounding area, a plume map, and <br /> cross sections showing the hydrogeological framework. Installation and development of <br /> groundwater monitoring wells MW-13 through MW-19 and free-product monitoring wells <br /> MWFP-1 through MWFP-5 were described, along with the initial sampling results for those <br /> wells. The Report also included the analytical results for samples collected from six water <br /> supply wells in the vicinity. In the Report and QMR, TSJCI concluded: <br /> • The extent of the previously modeled plume of impacted groundwater was <br /> confirmed by the data obtained from the new wells; <br /> • Contaminant transport is significantly influenced by the presence of silt, sand and <br /> gravel in the subsurface compared to the lower permeability clayey soils toward <br /> the east and west; <br /> Groundwater in lower sand units (aquifer) has been protected from contaminants <br /> • by the overlying clay units (aquitards); <br /> • Free-product is not present in any of the wells; <br /> The water supply vVells on the subject site and on nearby properties have not been <br /> impacted by fuel component contaminants. <br /> The plume of impacted groundwater is stable and the northern, down-gradient limit <br /> is receding southward; and <br /> Contaminant concentrations within the plume are oscillating around a downward <br /> trend. <br />