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�atll6 a i01.;oU'iiiY <br /> • EW"RONt 'AL HEALTH DIVISION <br /> jut E. Weber Ave.Third Floor <br /> P.O.Box 3881 Stockton46 A 95201-0388 <br /> 52 t_388 <br /> Phone: (209) <br /> �ved <br /> 13 Approved wkh changes: See Remarks <br /> []Disapproved: See Remarks <br /> Remarks <br /> Date Fay <br /> Approval of these plans exte cs only to that <br /> which is shown and ct_sctthec: terenn but <br /> does not authorize or a�Jprove ar`y aff;=ssian <br /> -- • or deviator of regwreme'nts of State raves or <br /> Local Ordinanc9s. <br /> ERI <br /> ENVIRONMENTAL RESOLUTIONS. INC. <br /> December 9, 1998 <br /> ERI 2-17903.W02 <br /> Mr.Robert Bout l <br /> Unocal DBG/AMG <br /> 2121 North California Boulevard.Suite 250 <br /> Walnut Creek.California 91596 <br /> Subject Addendum to Work Plan for Supplemental Environmental investigation at Former Unocal <br /> Service Station 5098.5606 Pacific Avenue,StoUaon,California. <br /> \fr.Bout: <br /> At the requm of Union Oil Coronary of California(Unocal).Environmental Resolutions,Inc.(ERI) <br /> Submitted a Work Plan entitled: Work Plan for Supplemental Eavinnunental Investigation ar Former <br /> Unocal Service Station 5098,dated: November 1'_. 1998 for the subject site. The San Joaquin Countv <br /> Public Health Services.Environmental Health Division(rhe County)provided comments to the Work <br /> Plan in a letter dated November 10. 1998 and requested an addendum be submitted by December 2. <br /> 1998. A copy of the Counr's itaer is provided in Attachment A. Pursuant to a written requm by <br /> ERI.the County granted an enension of the submittal date to December 9. 1998. The County's <br /> approval is provided in Amichmem B. 1 i' <br /> The following presents the information requested in the CoumvS comment letter. 11{Vy" <br /> Item 1-Well Construction Details <br /> As requested.'...Diagrams and specifications are to be included for the wells that detail the size. <br /> icngth,placement depths-intervals.and materials to be included in the construction of the well.- Well <br /> construction details for both me shallow and deep wells are provided in Attachment C. hi addition.as <br /> requested,the screen length of deep wells will be no greater man five feet and the screened interval of <br /> the deep monitoring wells shall be placed in the most permeable soil laver closest to the historical <br /> deepest depth to groundwater(i.e..approximately 60 feet below ground surface). To facilbate the <br /> recognition of permeable zones,borings drilled for deep well installation will be continuously cored <br /> beneath 40 feet. <br /> Item'_-Anallticl Analysis of Sad Samples from Groundwater Monitoring Well Borings <br /> As requested in the Counw's letter 'Soil samples collected from the monitoring well installations shall <br /> be additionally auivzed for the seven oxygenates listed in the enclosed PHS-EHD policy". Although <br /> Unocal has agreed to Petro=analyses for oxvgcmted compounds, it should be noted that Unocal has <br /> not used anv other oxygenated compounds other than methvi tertiary burvl ether(MTBE)in its gasoline <br /> in California. Soil sampling of borings for dthologic and potential laboratory analysis will be <br /> performed at 5-foot intervals from the surface to total depth of the deep wells for weds proposed as <br /> side-by side completion. For shallow wells only(i.e.,a deep well not proposed nurbv),soil Sampling <br /> 79 Di9ltal Drive,Suite 6,Novato,Glnomia 90999 915-382.9105 (FAX 915-782-1956) <br /> Lake Forest • NOMO •Seattle <br />