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•CHNICAL MEMORANDUM• <br /> From: Scott E. Gable R.G. To: Interested Parties Copies: File <br /> Company: Kvaemer Davy <br /> Location: San Francisco <br /> Reference: J:\7043\wp\otherWn021997.001 <br /> Subject: Permit for Destruction of Monitoring Well MW-470A Date: February 19, 1997 <br /> DDRW-Sharpe UST Site No. 34 <br /> This Technical Memorandum is presented as an addendum to an Application for Permit to destroy a <br /> monitoring well. This Technical Memorandum describes the purpose for, and techniques to be used in, <br /> destruction of a groundwater monitoring well designated MW-470A. <br /> Underground storage tank(UST)site No. 34 at Defense Distribution Region West(DDRW) Sharpe may be <br /> closed following successful removal of petroleum contaminated soil and verification sampling. Excavations <br /> limits are expected to encompass the well head and near surface reaches of MW470A as shown on the <br /> attached Site Plan(Figure 1) and Geologic Cross Section D-D'(Figure 2). This monitoring well will be <br /> destroyed prior to excavating UST site No. 34. The well will be destroyed in a manner consistent with <br /> requirements of the San Joaquin County Public Health Services -Environmental Health Division Site <br /> Mitigation Program Guidelines for Work Plans and Report Submittal, dated June, 1993 and California <br /> Department of Water Resources (DWR) Bulletin 74-90 Part III. <br /> Monitoring well MW-470A is a 2-inch diameter PVC well screen in an 8-inch diameter borehole completed to <br /> 36-feet below ground surface(bgs). The well will be destroyed by drilling over the casing with hollow stem <br /> augers (4'/z-inch inside diameter by 81/2-inch outside diameter)and pressure grouting the remaining borehole <br /> with a neat cement mixture consisting of one sack of Portland Type MI cement(3%bentonite)to 10 gallons of <br /> water. A side discharge tremie pipe will be used to place the neat cement which will be delivered using a <br /> grout pump. The borehole will be backfilled only to 15-feet below ground surface, coincident with the planned <br /> depth of excavation at UST Site No. 34. (see Figure 2). <br /> r.v043MKOTeeRMUMOC <br />