Laserfiche WebLink
Section 4 <br /> Results <br /> Local Geology <br /> A north-south cross section of the area studied during soil boring instillation is shown <br /> on Figure 4-1. Boring logs are attached as Appendix D. The upper 60 feet of soil <br /> be:teath the former gasoline Most oaf theesel sample ntly of <br /> tanklocati <br /> o be cons mpose of about 50 <br /> silty fine sand and sandy <br /> percent to 70 percent silt and clay and 30 percent to 50 percent very fine sand. Lenses <br /> of clay.y silt and fine sand also occur in the study area. Blew counts recorded during <br /> drilling indicate that the soil consistency ranges from film o very still teat is pre- <br /> dominantly stiff. No groundwater was encountered in any of the borchcIcs drilled at <br /> the East Miner location. <br /> Local Hydrogeology <br /> n. Fre- <br /> No groundwater monitoring1wells investigation (t1�ealled at Dcl Monne Dison e) indicate East Miner eith1 steal- <br /> _ liminary data from a nearby <br /> low groundwater is flowing northerly at a gradient of 0.002 (CH2M HILL, November <br /> 1991, in preparation). <br /> Ground-Penetrating Radar Survey Results <br /> rad <br /> r (GPR) survey <br /> r The subsurface anomalies detected by she ground-penetrating ub.unlace anomalies or electromagnetic reflec� <br /> shown on Figure 4-2. Although some <br /> tions were encountered, Norcal"did not identi y �y ref e ilies p iotterns ch dent rich are <br /> of <br /> underground storage tanks" (Appcndix B). <br /> characteristic of buried pipelines. <br /> ast <br /> es <br /> Figures ca and 4-4 ma esti om underground storagenative field data nt•tanks are typicallydmotrehdisttiinct <br /> Miner location. Anomalies <br /> than those observed at the East Miner location. For comparison, Figure 4-5 shows a <br /> typical GPR anomaly of a 1,000-gallon underground tank. <br /> the <br /> ly ob- <br /> During the GPR survey�5 fou6r 51S-inch-diameter bol* <br /> -inch square footings hoies.o Thet footings are14 fret <br /> served. Each footing h <br /> apart from each other ectednd five feet from diesel tank, Thess'ellding 3 ; the two footings are in the two footings m Y have been used testi p- <br /> vicinity as the suspp <br /> port an aboveground storage tank similar in size to the suspected 50(1-gallon these <br /> tank. <br /> 4-1 <br /> 5103If,t)5VdP,cxu.;t <br />