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- ENVIROMEN <br /> TAI1 HEALTDEPARTMENT <br /> °u`N SAN JOAQUIN COUNTY <br /> Unit Supervisors <br /> c a b y Donna K. Heran, R.E.H.S. 304 East Weber Avenue,Third Floor Carl Borgman,R.E.H.S. <br /> :< Director <br /> N.� StOGkton,California 95202-270$ Mike Huggins, R.E.H.S.,R.D.I. <br /> Al Olsen, R.E.H.S. Douglas W. Wilson,R.E.H.S.' <br /> :.. P. Program Manager Telephone: (209)458-3420 Margaret Lagorio,R.E.H.S. if <br /> QCI FO�aI <br /> Laurie A. Cotulla, R.E.H.S. Fax: (209) 464-0138 Robert McCleElon, R.E.H.S. 1 <br /> Program Manager Jeff Carruesco, R.E.H.S. <br /> Website:www.sjgov.org/ehcV <br /> j <br /> DONALD SINCLAIREp ZQaJ <br /> SHIRLEY THOMPSON <br /> 3780 LYNNE ROAD <br /> TRACY CA 95376 <br /> RE: Sinclair Trucking SITE CODE: 1916 <br /> 3780 Linne Road <br /> Tracy CA 95376 <br /> San Joaquin County Environmental Health Department (SJC/EHD) has reviewed <br /> "Remedial Action Report"(Report) dated August 11, 2005, submitted on your behalf by <br /> Geological Technics Inc. (GTI) and has the following comments. <br /> The Report documents remedial activitiesthat were conducted at your site during <br /> February 2005. Approximately 400 cubic,'yards of soil contaminated with petroleum <br /> hydrocarbons were excavated and removed from the site. Soil samples for analysis <br /> were collected from the bottom and sidewalls of the excavation, and from the <br /> contaminated soil stockpile. One monitoring well had to be destroyed prior to the <br />` excavation, and was subsequently replaced. Routine quarterly groundwater monitoring <br /> and sampling has continued following the'remedial activities. <br /> The Report provides an estimate of contaminant mass remaining in the soil, stating that <br /> approximately 80% of the soil contamination was removed during the remedial activities. . <br /> However, not all available site data was used in the estimate calculation of remaining <br /> hydrocarbons. The original mass reported was calculated for the Initial Site Conceptual <br /> Model (SCM) dated June 18, 2003. Additional investigation has been conducted <br /> following that date which included the collection of more soil data that should have been <br /> incorporated into an updated mass calculation. The calculation of contaminant mass <br /> remaining after the remediation used only data from the excavation pit, ignoring earlier <br /> data available for areas outside the excavation area from soil that was not removed with <br /> the remediation. The SCM figures showing the sorbed mass distribution prior to <br /> excavation vary from the distribution shown in the Report. All available data must be <br /> honored for both the contaminant mass estimate and the modeled distribution of <br /> contamination, unless the data can be discarded for sound technical reasons. No <br /> technical justification for discounting earlier collected data was provided in the Report. <br /> As it is important to have a reliable estimate of the residual contaminant mass to <br /> evaluate the risk posed by contaminants left in place, SJC/EHD directs a recalculation of <br /> the contaminant mass at this site, both before and after the remediation activities, and <br /> that all available site data be used in the calculations. <br />