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_ � r. � ; �, � : � , r� �.. : _. � `!, �' � �� <br />,__�: �.�.. ... .. . . . . ,. <br />ul' ��;iriations in hydraulic conducti��ity across thc sitc. Slug tcsting was performed at �vclls B-9, <br />13-Id, and B-17. Wcll II-l8 ���as not tested duc to its poor recovery ratc and thc presence of <br />strong gasolinc odors in thc �vcll. <br />Slug tests were perfornred on July 1, 2002, by a Shannon fi�Vilson hydrogeologist. Multipl:. <br />tests ���cre performed at cach well to assess thc reproducibility of the groundwater level response <br />in thc wcll. A rotal of three falling hcad and thrcc rising head tcsts each were complctcd at wells <br />B-�, B-14, and I3-17. Appcndix D provides slug testing procedures and method��logy and a <br />summary of slug tcsting results. Thc rangc of hydraulic conductivity valucs est:mated for thc <br />testcd soils (using thc gcomctric mcans from the Bou�ver and Ricc and the Cooper methods) is <br />fi'om :ibout I? x IO'to �1.3 x 10'' ccntimctcrs per scconds (cm/s). <br />7.0 GI'sOP1�lYSICrU, SURYEI' <br />Because contamination is present at boring B-18 and contamin:mt concenu'atirnis in sail at this <br />locntion indicate pro�itnity to a source, :� gcophysical sur��ey was conducted in accessible <br />portions of thc cxisting plaza in thc vicinity of boring B-1 S to look for buricd objccts, such as an <br />imdcrgroimd storagc tank (UST) or piping. Scvcral "lincs" ���crc cvaluated around thc north�vcst <br />comcr of thc existing Administration 13uilding (nc;v thc formcr pump island), as �vcll as :� <br />50-foot-squarc arca centcrcd on boring I3-IS. �yithin thc 50-foot-squaro arc:i.:� ;�rid of lincs <br />���crc cvaluatcd on an approximalc 1-mctcr spacing in cach dircction. <br />'Ilu survc�� consistcd of ground pencu����ing radar (GPR) tcchniqucs and ���as per(ormcd hy an <br />c�pericnccd local gcophysical company, GcoRccon, undcr subcontract to Shannon �\1'ilson. <br />'l�hc gcophysiail sur��cy rcport is includcd in Appendix 1=. GPIZ is a mcthod that provides a <br />continuous, high resolution cross-section depicting vurialions in the cleclncal properties of thc <br />shallow subsurfacc. Thc systcm operatcs by continuousl�� �adiating a S00-megahcrtz (MEIz) <br />radar frequency pulse into the grounJ from a trarsducer as it is moved along a traverse. Since <br />most of thc matcrials arc transpurcnt to thc 500 ,\41-Iz radar frequcncy pulsc, only a portion of Ihc <br />radar sional is reflected back to the surfacc. However, ���hcn the signal encounters a metal object, <br />all of thc incident cnergy is reflectcd. The resulting rccords can providc inCormation regarding <br />stratification, the thickness and cxtent of fill matcrial, thc location of buried oUjccts, and changes <br />in matcri:il conditions such as saturation. Significant amoimts of fill matcriaVdebris and somc <br />:oil t����c� i;in inhihit thc ��crl�,rmnncc �,I the ��coph�si�al rquipmcnt. <br />i i-r.,�,.a,o� r, i,, �, ud � I- I-09G�3�1-00� <br />