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E,lc (L�/ N <br /> Ci LEEDSHILL - HEe;���ENHOFF, INC. Linee(N � • L#4... 41r CC1I <br /> 9j 1275 Market Street <br /> j W San Francisco, California 94103 <br /> (415)626.2070 <br /> March 1, 1988 <br /> Mr. Robert L. Niblack <br /> Engineering Geologist TH <br /> California Regional Water Quality Control Board <br /> rvSP� NEpt <br /> V1Ei��� IGES, <br /> Central Valley Region EN SERV <br /> 3443 Routier Road <br /> Sacramento, CA 95827 <br /> Re: Lincoln Properties, Lit./Groundwater <br /> File No. 52640-13360 <br /> Dear Mr. Niblack: <br /> Responsive to concerns as expressed in your February 23, 1988 letter, Leeds- <br /> hill-Herkenhoff, Inc. (LH), proposes to modify the previously submitted <br /> technical approach for obtaining geological data at Lincoln Village Center, <br /> Stockton. As discussed in our February 23, 1988 phone discussion, in lieu <br /> of a combination of continuously coring two boreholes and mud-rotary drill- <br /> ing at the other sites, LH will conduct the hydrogeologic investigation of <br /> the unsaturated zone using hollow-stem augering techniques. The hydrogeo- <br /> logic characteristics at the three (3) or four (4) monitoring well locations <br /> will be established by continuously logging cutting samples produced during <br /> hollow stem augering and the collection of modified California split spoon <br /> samples at lithologic changes as determined and directed by the on-site LH <br /> engineering geologist or civil engineer to provide better geologic data. <br /> With respect to the actual groundwater monitoring well installations, LH <br /> still proposes to construct these wells using direct mud-rotary techniques. <br /> The concerns with ". . .locating the first water-bearing zone and proper <br /> placement of the screened interval . . ." should no longer be a concern with <br /> the initial hollow stem auger drilling. <br /> As agreed in our February 23, 1988 phone discussion, we would like to re- <br /> ceive written concurrence that the amended geologic investigation is accept- <br /> able to you, and that additional borings to characterize the geology at the <br /> site will not be required. The Technical Report, including results from <br /> this investigation will be available approximately four months after LH <br /> receives RWQCG approval to proceed. <br /> Please call if you have any questions. �O F�OFESS.rpN, <br /> ,. <br /> Very truly yours, 4�eypS. IV, !F, 71 <br /> � <br /> Gerry S. Nakano ` JAo.29524 <br /> �P � <br /> cc: Mr. Wil Smith P. <br /> Ms. 'Jeanne Zolezzi t <br /> ALBUQUERQUE • SANTA FE • PHOENIX SAN DIEGO • SAN FRANCISCO <br />