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2015-03-10 Dredging Presentation by Randall.Pdf C DS R. E. Randall Bauer Professor of Dredging Engineering Director, Center for Dredging Studies Ocean Engineering/Department of Civil Engineering Texas A&M University C DS OVERVIEW Dredging Equipment Dredge Production Dredged Material Placement Open water Confined (Upland) Beneficial use Environmental Laws Summary Presentation for Lone Star Harbor Safety Committee 2 C DS DREDGING EQUIPMENT DREDGE MECHANICAL HYDRAULIC Dipper Bucket Ladder Hopper Sidecasting Pipeline Agitation Clamshell Dragline Backhoe Bucket-Ladder Plain Suction Cutterhead Bucket Wheel Dustpan Presentation for Lone Star Harbor Safety Committee 3 C DS HOPPER DREDGE Presentation for Lone Star Harbor Safety Committee 4 C DS HOPPER DREDGE (GLDD LIBERTY ISLAND & MURDEN SPLIT HULL HOPPER DREDGE) Presentation for Lone Star Harbor Safety Committee 5 C DS MECHANICAL CLAMSHELL DREDGE Presentation for Lone Star Harbor Safety Committee 6 C DS PIPELINE DREDGES AND SLURRY TRANSPORT Typical pipeline diameters range from 15 to 92 cm (6 to 36 in) Pipes are commonly constructed with steel or a composite material such as high density polyethylene Pipelines may be submerged, floating, or placed on the shore. Floating pipelines may be supported by pontoons or flotation material. Length of the pipelines varies from short distances such as several hundred feet to several miles. Presentation for Lone Star Harbor Safety Committee 7 C DS CUTTER SUCTION DREDGE & CUTTERS Presentation for Lone Star Harbor Safety Committee 8 C DS ADVANCING WITH FIXED α α SPUDS Presentation for Lone Star Harbor Safety Committee 9 C DS BOOSTER PUMP, UNLOADER, SPIDER BARGE Presentation for Lone Star Harbor Safety Committee 10 C DS PRODUCTION EQUATION CU YD/HR = GPM x AVE % SOLIDS x 0.297 CU YD/HR = D^2 x V x (SG-1) x 0.661 Example: 20 in (0.508 m) dredge, V=15.12 ft/s(14,805 GPM), SG=1.25 (Cv=0.2273 or 22.73 % solids by volume) P=GPM(Cv)(0.297)=14805(0.2273)(0.297)=999 cu yd/hr P=D2(V)(SG-1)(0.661)=202(15.12)(1.25-1)(0.661)=999 cu yd/hr Presentation for Lone Star Harbor Safety Committee 11 C DS DREDGED MATERIAL PLACEMENT OPTIONS Open Water Placement Confined Disposal Facility (CDF) Beneficial Use Presentation for Lone Star Harbor Safety Committee 12 C DS OPEN WATER PLACEMENT Presentation for Lone Star Harbor Safety Committee 13 C DS CONCEPTIAL CONFINED PLACEMENT FACILITY Presentation for Lone Star Harbor Safety Committee 14 C 50 YEAR PLAN FOR BENEFICIAL USE OF DREDGE MATERIAL DS (PORT OF HOUSTON, COURTESY OF D. CASEBEER) Presentation for Lone Star Harbor Safety Committee 15 C DS ATKINSON MARSH Presentation for Lone Star Harbor Safety Committee 16 C DS SEASONAL RESTRICTIONS ON DREDGING (DREDGING WINDOWS) The dredging window refers is that period during which dredging activity is permitted Windows are placed on the dredging to protect a biological resource from impact of the dredging activity Dredging windows Provide protection to the resources Complicates scheduling of funding, contracting and conduct of work Increases the costs due to constrained time period Increases operational hazards if windows coincides with adverse weather Causes inefficient use of the dredge fleet Presentation for Lone Star Harbor Safety Committee 17 C DS GULF INTRACOASTAL WATERWAY IN TEXAS Presentation for Lone Star Harbor Safety Committee 18 C DS DREDGING COSTS Actual Dredging Costs (1993‐2013) Average Dredging Cost/Cubic Yard $1.60 $7.50 $1.50 $7.00 $1.40 $6.50 $6.00 $1.30 $5.50 $1.20 ($/CY) $5.00 $1.10 $4.50 $1.00 Dollars) $4.00 $0.90 Cost $3.50 $0.80 $3.00 $0.70 $2.50 $0.60 $2.00 $1.50 (Billion $0.50 $1.00 $0.40 Average $0.50 $0.30 $0.00 Cost $0.20 $0.10 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 $0.00 Fiscal Year 2011 2013 2012 1993 2001 2010 1995 1997 1994 1998 1996 1999 2003 2005 2002 2007 2004 2000 2008 2006 2009 Fiscal Year http://www.navigationdatacenter.us/dredge/dredge.htm Presentation for Lone Star Harbor Safety Committee 19 C DS SUMMARY Dredging is used to maintain and deepen ship channels, GIWW, ports & harbors, other waterways. Dredging equipment includes: cutter suction, hopper, & mechanical dredges, barges, pumps, instrumentation. Dredged material is placed in open water, confined (upland) placement areas, and used beneficially. Dredging is used for the environmental clean up of rivers, lakes, bays, and oceans. Environmental laws regulate dredging activities Dredging windows protect certain marine life Total US dredging costs $1.1 billion and average cost/cubic yard was $5.81 Texas GIWW requires ~ 11 million cubic yards of dredging Presentation for Lone Star Harbor Safety Committee 20 C DS QUESTIONS Presentation for Lone Star Harbor Safety Committee 21.
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