Laserfiche WebLink
California gional Water Quality Cop1'•pl Board <br /> - Central Valley RegionFn <br /> Karl E. Lungiry. Sri). P.E, Chair <br /> Arnold <br /> 1 May 2007 RECEIVED <br /> MAY 0 3 2V <br /> Mr. A.K. Jain BY' GEOCCIN <br /> Slate of California, Department of General Services <br /> ]0] 3rd Street, Suite 4-430 <br /> West Sacramento, CA 95605 <br /> WORKPLAN REVIEW, FORMER VINTAGE CAR WASH, 601 EAST MINER AVENUE, <br /> STOCKTON, SAN JOAQUIN COUNTY <br /> I reviewed the Soil Vapor Survey and Risk Assessment Workplan (Wongelan) received <br /> 30 April 2007, submitted by Geocon Consultants, Inc. (Geocon) on behalf of the <br /> California Department of General Services, Real Estate Services Division (DGS) for the Slate <br /> Controllers Office - Bureau of Unclaimed property (SCO). The Wokplan includes Figure 3, <br /> which provides the thirty proposed soil gas survey locations and a partial list of gre maximum <br /> groundwater monitoring well analytical results for sampling conducted on 28 March 2007. The <br /> 28 March 2007 monitoring repon has not been released as of the date of this letter, so the <br /> following table is incomplete for all constituents. Comparing the March 2007 groundwater <br /> results with the last sampling event in September 2005 in the following table, <br /> On anarn 11 laem n:e a Ten -oc <br /> 99 005 2.200 a 1.600e 320 ayL 9,B�W 90 ugT 20 uyL .3 ugh <br /> I8 uyL 15 <br /> r}200] ve e5.000 04 a m , a r z mo-vo re <br /> - wxpmcam asps z - w.uM Korea, roan moor a+Mrs <br /> s m ee that groundwater concentrations of all constituents reported have not changed <br /> significantly between the two events, with all gasoline constituents noted remaining well above <br /> water quality objectives. <br /> The Wokplan proposes thirty (30) direct-push soil gas sampling points (25 onsite and 5 <br /> ofisite, see attached Figure 3) to characterize potential threats from vapor intrusion to adjacent <br /> residences and businesses. The Workman also slates that two soil borings will be used to <br /> collect soil samples for physical properties (soil bulk density, grain density, soil moisture <br /> content, grain s¢e, and total porosity). The Workplan states that the soil vapor data will be <br /> used to perform a preliminary screening evaluation for vapor intrusion using the Department of <br /> Toxic Substances Control (DTSC) guidance, Interim Final Guidance for the Evaluation and <br /> Mitigation of Subsudae Vapor Intrusion to Indoor Air Cr February 2005). <br /> California Environmental Protection ASemry <br /> 0 rrcrc ePnow <br />