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Hydraulic dredge
Pipeline to geotubes
Photo from: Little Lake Cleanup Team
2
Sediment processing facility
Water treatment plant
Geotubes (separates dredge water from mud)
Truck disposal route
From: Little Lake Cleanup Team
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• Water drains by gravity
• Less labor/equipment
• “Decouples” dredging & dewatering
• Less potential air release
Separating dredge water using “geotubes”
Extra slide
4
Dewatering - geotextile tubes
GravelWater collection pipe
Liners
TubesBerm
From: Little Lake Cleanup Team
Extra slide
5From: Little Lake Cleanup Team
Filling geotubes
Extra slide
6
Solids captured & water drains out
Extra slide
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Stacked geotubes
Geotubes need a lot of space
8From: WDNR webpage
Water treatment
• Air flotation• Sand/gravel filters• Carbon filters
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Landfill disposal*
Loading
* Engineered for contaminant containment
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1. Commitment to goals
2. Flexibility
3. Cooperation
4. Coordination & communication
Good effort
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Why are we doing all this anyway?(time to fish recovery)
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<1 <1 <1 <1
0
10
20
30
40
50
60
Cleanup LevelsNo Action 5 ppm 1 ppm 0.5 ppm 0.25 ppm 0.125 ppm
<
Yea
rs
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Project Objectives
• Clean water
• Edible fish
• Ecological improvements
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Lake Winnebago
From: DEA, 2003
Capping: possible dredging supplement
1. Post-capping water depth 3-feet+
2. Not in navigation channel
3. Avoid pipelines, utilities, etc.
4. PCBs less than 50 ppm
Possible capping
Sand cap
Sediment
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1. Stirring up (resuspension)
2. Leftover contamination (“residuals”)
3. Habitat effects
4. Disposal
DredgingIssues
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16
Dredging critics*Resuspension
Extra slide*Not U.S. EPA view
*
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Contaminant losses during dredgingHudson River White Paper Resuspension of PCBs During Dredging
• 5 Projects
• 388 observations
Average loss: mechanical dredge 0.3%
Average loss: hydraulic dredge 0.1%
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DredgingSurface water monitoring
Wat
er c
lari
ty(t
urb
idity
)
Background levels
dredging
dredging
dredging
dredging
dredging
10/24
/05
10/23
/05
10/25
/05
10/26
/05
10/27
/05
10/28
/05
dredging
DaysFrom: OU 1 Environmental Data Memorandum, November 2, 2004
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Contamination left behind(dredging “failures”)
Critics view: “…no contaminant concentration reduction.”
Reasons:
1. Shallow bedrock
2. Debris (e.g., rock and wood)
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Shallow bedrock: “leftovers” are hard to remove
River
Residual sediment
Bedrock
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Wood debrisManistique River, MI
22
Rock debrisGrasse River, NY
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Concentrations after dredging
94AVERAGE99PCBsLake Jarnsjon, Sweden92CadmiumMarathon Battery, NY97PCBsNew Bedford, MA97PCBsCumberland Bay, NY99PCBsGM Massena, NY79PCBsGrasse River, NY
Average % ReductionContaminantProject
From: Hudson River Responsiveness Summary White Paper (312663),Post-Dredging PCB Residuals
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05
101520253035404550
Fox River dredging projectConcentration reduction
Average PCB concentrations (ppm)
Pre-dredging Post-dredging
96% reduction*
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2
*For all sediments
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March 1999 (after excavation)
Habitat disruption - Bryant Mill Pond
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August 1999 (4-months after excavation)
Habitat recoveryBryant Mill Pond
U.S. EPA and WDNR, 2002, Record of Decision, Operable Unit 1 and Operable Unit 2, Lower Fox River and Green Bay, White Paper 8 – Habitat and Ecological Considerations as a Remedy Component for the Lower Fox River
27Groundwater
Liner system
Capping system
Native clay soil
Disposal: engineered landfill
Waste
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Treatment - sediment melting (vitrification)
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Melting versus landfill disposal(Fox River upstream)
$21 million$48 millionCosts (upstream project)
Proven effective
Successful small scale test
Technology development
No (landfill space used)
Yes (beneficial re-use)
Treatment
Landfill disposal
Melting(i.e., vitrification)
Preferred
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Capping
Sand cap
Contaminated sediment
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Dredging versus Capping
Remains in river
Landfill
Permanent change
Altered/disrupted (eventual recovery)
Habitat
Contained*Mostly removedContaminant disposition
No releasesSmall releaseShort-term releases
CappingDredging
Preferred *Assumes long-term stability
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Dredging versus Capping
ModerateHighCost
Less noise, traffic, odors, etc.
Some noise, traffic, odors, etc.
More monitoring & institutional
controls
Limited followupmonitoring
DecreasedIncreasedWater depth
Monitoring & maintenance
Smaller “footprint”Larger “footprint”Construction impacts
CappingDredging
Preferred
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Capping• Best in quiet waters
• Typically for low toxicity contamination
Photo courtesy of Bean Environmental, LLC.
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Cleanup options summary
• “One size does not fit all”
• Unique site conditions should be considered
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Economic benefits of cleanup
• Increase in property values (e.g., Waukegan Harbor: $53,000 increase per house following cleanup*)
• Cleanup-related jobs & business
• Health benefits
* Braden, J.B., et al, 2004, Contaminant Cleanup in the Waukegan Harbor Area of Concern: Homeowner Attitudes and Economic Benefits, Journal of Great Lakes Research.
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Economic benefits of cleanup(continued)
• Recreation improvements & tourism (e.g., removal of fish advisories)
• Lower navigation dredging costs and/or increased commercial use
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Economic benefits to communities from cleanups
$ 1 million
$ 4.2 million
$ 14 million
$ 4.6 million
$ 7 million
$ 2 million
$ 13.2 million
$ 142 million
$ 70 million
Annual income
$ 32.5 million
$ 22 million
$ 6 million
Annual income
No.No.
8001200RaymarkInd., CT ($80 million)
4300700Industri-Plex, MA ($60 million)
2500235Ft. Devens, MA
AnnualState taxes
Propertyvalue
increase
Permanent jobs
Short-term jobsSuperfund
project & cleanup costs
From: EPA, Superfund: The Road to Recovery Extra slide
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Economic benefits to communities from cleanups
Park fees
$ 0.6 million
$ 0.1 million
$ 67 million
$ 0.03 million
$ 0.4 million
---
$ 1.9 million
$ 0.5 million
Annual income
$ 2.1 million
$ 3.7 million
$1.2 million
Annual income
No.No.
---90ChismanCreek, VA
113145Denver Radium, CO ($130 million)
2042Old Works, MT
Annual State taxes
Propertyvalue
increase
Permanent jobs
Short-term jobsSuperfund
project & cleanup costs
Extra slideFrom: EPA, Superfund: The Road to Recovery
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Big river sites cleanups
2.7 million$ 460 millionHudson, NY
?$ 600 million (?)Housatonic, MA
1.0 million?Kalamazoo, MI
Fox River, WI 7.2 million$ 400 million
Contaminated sediment
(cubic yards) Cleanup costsSite
40Photo from Ann Schell
More information:http://www.epa.gov/region5/sites/foxriverhttp://www.dnr.state.wi.us/org/water/wm/foxriver/index.htmlhttp://www.littlelakecleanup.com/pages/1/index.htm
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