Evaluation of Environmental Dredging for the Buffalo River

1
Evaluation of Environmental Dredging for the
Buffalo River

• Joseph F. Atkinson
• Great Lakes Program
• University at Buffalo
• October 8, 2004

2
Overview

• Whats the problem?
• Motivation/goals
• Recent data
• Current modeling
• ECOMSED
• Particle tracking
• Critical shear
• Continuing work

3
Setting
4
Buffalo River Area of Concern (AOC)
5
Physical characteristics

• gt 400 mi2 watershed
• Rural residential, agricultural, forest
• Lower river ? 6.5 miles long
• Meanders
• Periodically dredged (24, navigation)
• Stratified (reverse flows)
• Flows vary, 30 lt Q lt 10,000 cfs
• Mostly settling basin for solids

6
The problem(s).

• Previous industrial activity
• Low dissolved oxygen (summer)
• Contaminated sediments
• Previous industrial activity
• Upstream loading
• Hazardous waste sites
• CSO loadings

7
Previous work

• Remedial Action Plan (RAP)
• Coordinated through DEC/FBNR
• Data collected
• Remediation alternatives examined
• EPA Analysis and Remediation of Contaminated
  Sediments (ARCS) program
• Sediment modeling, coring samples in early to mid
  1990s
• Present work continuing those analyses

8
Sediment modeling history
9
Contaminated sediment inventory(ARCS)

• Focused on hot spots
• Resulted in dredging around Buffalo Color
  peninsula

10
Motivation(Remedial Action Committee)

• Restore beneficial uses
• (de-list as AOC)
• Habitat restoration
• Address sediment issues
• Environmental dredging
• Develop tool for evaluation of possible remedial
  action approaches
• Public-friendly

11
Present work
Sampling
(Buffalo News, 10/23/03)
12
Potential habitat restoration sites
13
Sampling procedures
14
(No Transcript)
15
PCBs in sediment cores
1
16
Sediment modeling

• Couple hydrodynamic, sediment transport and
  particle tracking models
• Compute changes in bed elevation
• Evaluate loading from upstream sources (quality
  and quantity)
• Effect of remediation options
• Natural redistribution and armoring
• Predict response to possible dredging actions

17
Current modeling

• ECOMSED
• 3-D, sigma layer, hydrodynamic and sediment
  transport
• Model selection criteria
• Study Objectives, budget and time constraints
• Technical Support
• Availability of data or the ability to obtain
  data
• Computing requirements
• Lateral and vertical flow profiles
• Linked with graphical output (SDA)
• Particle tracking

Turbidity
18
Sediment erosion (critical shear)
19
Buffalo River (current) tc ? 0.2 0.4
Pa Gailani et al. tc ? 0.1 gt 5 Pa
20
(No Transcript)
21
(No Transcript)
22
Long-term runs

• Multi-year (5-10 year runs) options
• Just do it
• Event and inter-event approach (Gailani et al.)
• Average conditions between events
• Particle tracking

23
Particle tracking

• Random walk algorithm, with settling
• Conservative, passive particles, no particle
  interactions
• Different particle size classes
• Resuspension same as traditional model
• Track newly entering and resuspended particles

24
Random Walk Algorithm

• For a particle in 2-D (vertical includes
  settling),
• Deterministic component Random component
• Deterministic component real velocity pseudo
  velocity
• - velocities obtained from ECOM output
• - iterative procedure used

25
Model verification (1-D)

• Relationship between diffusivity and step size
• Normalized concentration profile, D 10
  m2/sec, u 0.1 m/sec

26
Other

• Each particle represents a finite mass
• Allows evaluation of transport pathways
• Shows source areas
• Preliminary results show that most of the time,
  particles from upstream deposit shortly after
  upstream limit of dredging

27
Recommendations/further work

• Particle interactions
• Loading as a function of time (event)
• Lateral sloughing
• Further evaluation of
• Critical shear and erosion model
• Particle tracking
• Visualization package