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r 1 <br /> I { <br /> ENVIRO l ENTAL HEALTH')EPARTMENT <br /> >oP.. <br /> j! SAN JOAQUIN COUNTYy Donna K. Heran, R.E.H.S. Unit Supervisors <br /> Director 304 East Weber Avenue,Third Floor Carl Borgman,R.E.H.S. <br /> .. Laurie A. Cotulla, R.E.H.S. Stockton,California 95202-2708 Mike Huggins, R.E.H.S., R.D.I. <br /> Program Manager Telephone: 209 468-3420 Douglas W. Wilson,R.E.H.S. <br /> a<i F40 1? { ) Margaret Lagorio,R.R.H.S. <br /> Fax: (209)464-0138 Robert McClellon, R.E.H.S. <br /> Website: www.sjgov.org/ehd/ Jeff Carruesco, R.E.H.S. <br /> CARL NAVARRA JUN 2 7 2006 <br /> 475 BLEWETT ROAD <br /> TRACY CA 95376 <br /> RE: Navarra Property Site Code: 1392 <br /> 7500 Eleventh Street <br /> Tracy CA 95376 <br /> At the request of your consultant, The San Joaquin Company, Inc. (TSJCI), a meeting was held <br /> at the office of the San Joaquin County Environmental Health Department (EHD) in Stockton, <br /> California on 16 June 2006 to discuss the current status of your site and additional assessment, <br /> monitoring and remediation requirements. Attending the' meeting were Ms. Margaret Lagorio <br /> and Mr. Nuel Henderson representing the EHD, and Mr. Dai Watkins and Mr. Bernie Dietz of <br /> TSJCI representing you. Prior to the meeting, EHD reviewed Evaluation of Natural Attenuation <br /> of Petroleum Hydrocarbons in Groundwater(ENA), dated March 2006, prepared by TSJCI. <br /> The EHD concurred with TSJCI that the plume of impacted groundwater has been adequately <br /> assessed at this time and no additional assessment activities are currently required. Additional <br /> assessment may be required in the future if new information or interpretations indicate plume <br /> instability or currently unrecognized areas of concern. <br /> TSJCI has demonstrated in ENA the likely operation of natural attenuation of the impacted <br /> groundwater plume, estimating a current contaminant destruction rate of approximately <br /> pound per day and an estimated return to natural background conditions in the source area of <br /> various gasoline fuel components in approximately 8 to 16 years. TSJCI could not make an <br /> estimate of the time required for the plume to return to background conditions in the area of <br /> MW-7, on the north side of Eleventh Street, due to the presence of free product up-gradient to <br /> and in the MW-7 area. TSJCI recommended selection of monitored natural attenuation (MNA) <br /> as the selected remediation technology for the site. Also in ENA and recent quarterly monitoring <br /> reports, TSJCI presented a statistical analysis of the groundwater monitoring data to show that <br /> biennial monitoring of the peripheral monitoring wells and annual monitoring of the core wells in <br /> the dissolved plume would be adequate to properly monitor the plume. TSJCI also <br /> recommended cessation of monitoring of the local water supply wells and destruction of the <br /> unimpacted deeper groundwater monitoring wells. These points were discussed at the meeting. <br /> During the 16 June meeting, EHD expressed concern regarding the length of time required for <br /> MNA to attain background conditions in the source area and the unknown amount of time <br /> required for the MW-7 area. The EHD believes, and TSJCI seemed to agree, that active <br /> remediation on the north side of Eleventh Street, where most of the contamination is either <br /> present or migrating toward, would accelerate the return to background conditions and would <br /> hasten ultimate site closure. This may be important to you as the EHD has been informed by the <br />