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+�_ ` <br /> , r <br /> ENVIRONMENTAL HEALTH <br /> DEPARTMENT <br /> OPt.viN C <br /> SAN JOAQUIN COUNTY <br /> r. <br /> �: :?� Ronna K.Reran,R.E.H.S. Unit Supervisors <br /> {'` < Director 304 East Weber Avenue, Third Floor Carl Borgman,R.E.H.S. <br /> - <br /> Stockton, California 952022708 Mike <br /> Al Olsen,R.E.H.S. Huggins,R.E.H.S.,R.D.1. <br /> • •- — ram Pro Manager Douglas W.Wilson,R.E.H.S. <br /> atri oxia� g g g <br /> Laurie A.Cotulla,R.E.H.S. g Telephone: (209) 468-3420 Margaret La orio,R.E.H.S. <br /> Program Manager Fax: (209) 464-0138 Robert McClellon,R.E.H.S. <br /> Mark Barcellos;R.E.H.S. <br /> LORI SHIELDS <br /> DIESEL PERFORMANCE MAR 17 e uu% <br /> 2804 FREMONT STREET <br /> STOCKTON CA 95205 <br /> RE: Diesel Performance SITE CODE: 1120 <br /> 2804 Fremont Street <br /> Stockton CA 95205 <br /> San Joaquin County Environmental Health Department (SJCIEHD) has reviewed <br /> "Addendum to Site Conceptual Model and Corrective Action Plan" (Addendum) dated <br /> March 5, 2004, that was submitted on your behalf by ATC Associates, Inc. (ATC) and <br /> has the following comments. <br /> The Addendum was submitted to address specific requests made by SJCIEHD in <br /> correspondence dated February 17, 2004. The addendum includes a feasibility study, a <br /> calculation of contaminant mass remaining in soil at this site, a cross-sectional diagram <br /> and a rose diagram of historical groundwater flow direction. <br /> While there are a variety of methods and approaches to calculating the contaminant <br /> mass in soil, SJCIEHD does not agree with the equation used for the calculation for this <br /> site. Soil porosity is a factor of concern when calculating contaminant mass remaining in <br /> groundwater, but not in vadose zone soil. In addition, the cross-sectional diagram <br /> shows two disconnected masses of soil contamination. One soil sample collected at <br /> 30 feet below surface grade (bsg) in soil boring SB-3 was reported as non-detect for <br /> petroleum hydrocarbon constituents. However, this was the only soil sample collected in <br /> the former UST area from between 20-40 feet bsg that was ever submitted for analysis. <br /> The SJCIEHD inspector present at the drilling of boring SB-3 noted hydrocarbon odor in <br /> the 35-foot and 40-foot samples. The boring log for SB-3 has no comments on the <br /> condition of the samples form 31 feet bsg to 44 feet bsg. The summary of the report of <br /> findings (`Summary Report for Subsurface Investigation' dated October 20, 1997, <br /> submitted by SMITH Environmental Technologies Corporation) states "Although field <br /> observations and/or laboratory analysis did not identify petroleum hydrocarbons from <br /> 24 feet to 35 feet bsg in SB3, it is assumed petroleum affected soil at this site generally <br /> attenuates with depth." When monitoring well MW-1 was installed no samples from 20.5 <br /> to 40.5 feet bsg were submitted for analysis, but both the SJCIEHD inspectors field <br /> notes and the ATC boring log note slight to moderate product odor in soil samples <br /> collected at approximately 25, 30 and 35 feet bsg. SJCIEHD considers it unlikely that <br /> there are two disconnected areas of soil contamination at this site, and as such the <br /> estimate of contamination remaining in the soil proposed by ATC is probably low. <br />