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 HopperSidecastingPipelineAgitation
ClamshellDraglineBackhoeBucket-LadderPlain SuctionCutterheadBucket WheelDustpan
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)
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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
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ADVANCING
WITH FIXED α α SPUDS
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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
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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
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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
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