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- TAL SEA
<br /> �EPART E T
<br /> ENVIRONME ('JUIN COUNTY _unit Su�ervfsors
<br /> SAN `+ _ Carl B01
<br /> u,N R.L 1
<br /> R.E:H.S. Mike Huggins,R E•H.S=>
<br /> y � LSorina { Hem, 3(}4 East Weber Avenue,Third Floor Douglas W,Wilson,R:> .x.s.
<br /> q: :director Stockton, California 952,}2-270 ' rlatgaretLagorio,lt.> . I.s
<br /> " 468-3420
<br /> Al Olsen,R,E.H.S. R E.li.S,
<br /> ,. . '1`e��ph421e: (���} R�bertMcCtell�n,
<br /> Program Manager 464-0138
<br /> . �,..t Fax: ( Mark Bareellos,
<br /> 'a�` :Laurie A.Cotuila,It.E:HS: 2Q9}
<br /> Program Manager
<br /> AUG 0 9 2004
<br /> ,30E TOSTE JR
<br /> JT STORAGE
<br /> 2480 TOSTE ROAD
<br /> TRACY CA 95376
<br /> RE: Curtiss Pontiac-Cadillac
<br /> SITE:GQ17E: 1.877
<br /> 2450 Toste React
<br /> Tracy CA 9537£
<br /> Sart Joaquin County Environmental Health Department (SJCIEH©) has reviewed
<br /> "Excavation and Sampling Report-Former Gasoline UST" (Report) stated
<br /> January 9, 2004, along with the updated figures and tables dated June 23, 2004,
<br /> submitted on your behalf by Advanced G eoEnvi ron mental, Inc. (AGE), and has the
<br /> following comments.
<br /> Site remediation by aver-excavation of contaminated soil was conducted at your site
<br /> during May 2003. The Report presents the details of the over-excavation,and the
<br /> destruction and reinstallation of monitoring wells MW-1 A, MW-'113, MW-4 and MW-7.
<br /> Approximately 1,400 cubic yards of petroleum hydrocarbon contaminated sail was
<br /> removed during the remediation, The Report estimates that approximately 306 gallons
<br /> of total petroleum hydrocarbons as gasoline,or 83% of the calculated soil contaminant
<br /> mass at this site,was removed during the over-excavation.
<br /> The report recommends implementing the monitoring previsions of the approved
<br /> Remedial Action Plan (RAP), which proposed monitored statural attenuation as the most
<br /> feasible remediation alternative for the groundwater contamination remaining at this site.
<br /> Routine quarterly groundwater monitoring'-and sampling is to continue at the site;and
<br /> should include measurement or analysis of the following natural attenuation parameters:
<br /> dissolved oxygen, methane, ferrous iron; sulfate; nitrate, dissolved manganese,
<br /> alkalinity, hardness, pH, temperature, conductivity and redox potential. In addition,the
<br /> Wisconsin Department of Natural Resources guidance document, "Guidance Can Natural
<br /> Attenuation For Petroleum Releases", dated March 2003,which can be found on the
<br /> Federal EPA website, recommends determining the hydraulic conductivity for the
<br /> primary contaminant flow Maths (PCFP), horizontal and vertical gradient, effective
<br /> porosity of the PCFP's, bulk density of aquifer solids, organic carbon/water partitioning
<br /> coefficient(K,)for each contaminant, the organic carbon content(f0c)for the aquifer
<br /> along the PCFP's, location and horizontal and vertical dimensions of the contaminant
<br /> source area,and estimates of contaminant mass in the source area including the mass
<br /> in soil in both the vadose zone (Ms) and in the saturated zone (Msz) material and
<br /> dissolved phase (Mgw).
<br />
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