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ENVIRONMENTAL HEALTH DEPARTMENT <br /> 0SAN JOAQUIN COUNTY <br /> Unit Supervisors <br /> Zr' .y Donna K.Heran,R.E.H.S. <br /> a' Director 304 East Weber Avenue, Third Floor cart BorgmBorn, n,R.E.H.S. <br /> Al Olsen,R.E.H.S. SYOCICtOri, California 95202-2708 Mike Huggins,R.E.H.S,R.D.I. <br /> Douglas W.Wilson,R.E.H.S. <br /> • csq, o .NSP• Program Manager Telephone: (209)468-3420 Margaret Lagorio,R.E.H.S. <br /> F a Laurie A.Corolla,RE.H.S. <br /> Pro Fax: (209) 464-0138 Robert McClellory R.E.H. <br /> Program Manager 8 MMarBazcellos,R.E.H.S.. <br /> JAY MCILRATH apl Stµtl(�PD <br /> JC & M MCILRATH I <br /> PO BOX 326 11I �I�3 <br /> STOCKTON CA 95201 1 <br /> RE: JAMAR Service S Code: #1667 / <br /> 4075 Main Street <br /> Stockton CA 95212 ' <br /> WORK PLAN: "Additional Assessment Work Plan" <br /> DATED: October 2003 <br /> PREPARED BY: GHH Engineering,Inc. <br /> APPROVED: <br /> DISAPPROVED: <br /> ADDENDUM NEEDED: x Submit b4:. ember 21,2003 <br /> ADE UATE AND NECESSARY F, NTS OF THEW RK PLAN [H&S 25299.37,subd(c)(3)]: <br /> 1. Installation of monitoring w or investigation of the vertical and lateral extent of the groundwater contaminant <br /> plume,both onsite and down-gradient offsite. <br /> 2. Addition of the new wells to the quarterly groundwater monitoring and sampling program,with analyses conducted <br /> for TPHg,TPHd,BTEX,1,2-DCA,EDB and fuel oxygenate additives by EPA approved method 8260B. <br /> COMMENTS AND CONDITIONS: <br /> 1. Groundwater flow direction at this site has been consistently towards the southeast or south-southeast. The work <br /> plan states the offsite monitoring wells will be installed to evaluate the extent of impacted groundwater to the <br /> southeast,but the proposed locations of the offsite wells do not appear to be in this direction. Submit an addendum <br /> to the map locating adequate offsite wells to intercept the flow direction towards the southeast,as stated in the work <br /> plan,or provide technical justification for the locations shown on the current map. <br /> 2. The depths of the monitoring well clusters MW-6 and MW-7 do not intercept the sand noted in boring CPT-2 at 100- <br /> 110 feet bsg. The water sample collected at 100-104 feet bsg in boring CPT-2 reported 2,500 ppb MtBE. Additional <br /> monitoring wells must be installed to intercept this sand. Please include them in the addendum. <br /> 3. The target depth of the proposed deep,discretely screened onsite monitoring well must intercept an appropriate sand <br /> interval. The log for boring CPT-1 indicates a possible sand interval from 96.5-102 feet bsg;the log for boring B-1 <br /> indicates a sand interval from 100-110 feet bsg. This is the interval of interest;placing the screen at 95 feet bsg is <br /> likely to be too shallow. SJC/EHD believes that this boring should be set deeper than proposed,and continuously <br /> cored at target depth to ensure proper screen placement. Please include this in the addendum. <br /> 4. As previously directed,all wells associated with this site must be surveyed to an established benchmark,that is, <br /> relative to mean sea level. Per Senate Bill 2886,all survey data and laboratory analytical data must be submitted <br /> electronically to Georacker,the State Water Resources Control Board database. <br /> Lori Duncan,Senior REHS Nuel C.Henderson,Jr.,R.G. <br /> LOP/Site Mitigation Unit IV LOP/Site Mitigation Unit IV <br /> cc: James Barton,CVRWQCB <br /> Tom Ballard,GHH Engineering <br />