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<br />0ct-31-2002 11 :32am From- <br /> <br />T-S99 P.004/00B F-972 <br /> <br />Mr. Jim Norfleet, P.E. <br />Mr. Jack Byers, P.E. <br />Page 3 <br /> <br />July 11, 2002 <br /> <br />holes were drilled by Geotechnical Engineering Group, Inc, in November 2000 and <br />copies of the logs are attached. The test holes drilled by Geotechnical Engineering <br />Group indicates that the existing dam embankment consists of gravels and oobbles <br />with some boulders, sandy, silty to clayey material. Rock cores varIed from 2 Inches <br />to 11 Inches. Test hole No.3 on the downstream embankment encountered pieces of <br />wood and organic material 5 to 15 feet below the ground surface. Test hole No.4 <br />encountered primarily gravels and cobbles with less fines than the other test holes. <br />Subsequent exploratory excavation indioates that there may be a void In this area. <br /> <br />Percolation tests were conducted in the test holes. The rates measured in TH-2, TH-3, <br />and TH-5 are generally consistent with a silty sand material. The percolation rate in <br />TH-1 was relatively fast. This could be attributed to hIgh permeability in the <br />embankment or the abutment/foundation material which was penetrated by the boring. <br />Water disappeared in TH-4 as rapidly as it was added. TH.4 also penetrated the <br />abutment/foundation material and is In the area where a void has been identified. <br /> <br />Portions of the downstream .embankment were excavated in October 2001 to remove ./ <br />unsuitable material and investigate seepage areas. The above referenced void area was <br />identified, but could not be further excavated due to its location under the existing <br />road. Portions of the excavated area were backfilled to proyide adequate support for <br />the existing road platform. This temporary fill will be removed. <br /> <br />The downstream embankment Is proposed to be excavated beginning at the toe of the <br />undisturbed slope extending at a 1 to 1 slope. The excavated material will be <br />evaluated for suitability as embankment material. The depression located on the <br />upstream embankment will likewise be excavatect and evaluated. The excavated area <br />will be shaped to allow for benching for new compacted embankment material. The <br />area around TH.4 near the service spillway pipe will be excavated and investigated to <br />determine If the embankment material is suitable and to determine the extent of the <br />void area. <br /> <br />New Embankment <br /> <br />./ <br /> <br />The dam embankment will be enlarged to have a crest width of approximately 44 feet. <br />This will include 14 feet for the "damN and 30 feet for the roadway. The embankment <br />material Is proposed to come from on51te soils within the reservoir and from the nearby <br />Baron Reservoir. Several test pits have been excavated on the northwest end of the <br />reservoir. The test pits indicate that suitable material Is 'available. However, the <br />organic material at the lake bottom must be removed and screening for rocks 6 Inch <br />and larger may be required. The embankment cross section will consists of a 18 Inch <br />, deep graded filter blanket overlain by the embankment. The drainage filter includes a <br />drainage blanket and chimney drain extending up the abutment slope and provides for <br />controlled collection and conveyance of seepage water within the dam. A toe drain will <br />be installed to provide for controlled discharge of the seepage water. The toe drain will <br />consist of a perforated pipe surrounded by a graded gravel envelope. <br /> <br />...----....-.------. <br /> <br />l~gIRESDURCE <br />