DISCOVER | DEVELOP | DELIVER DISCOVER | DEVELOP | DELIVER 1 File Name SUSTAINABLE SEDIMENT MANAGEMENT AND DREDGING SEMINAR 6-8 MARCH 2019 SAUSALITO, CA Environmental Work Windows as a Management Practice Burton Suedel
DISCOVER | DEVELOP | DELIVERDISCOVER | DEVELOP | DELIVER1File Name
SUSTAINABLE SEDIMENT MANAGEMENT AND DREDGING SEMINAR6-8 MARCH 2019SAUSALITO, CA
Environmental Work Windows as a Management PracticeBurton Suedel
US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
Chemical• Metals, PAHs, etc.
Biological• Harmful Algal Blooms
Physical• Turbidity
Environmental Stressors
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US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
What is an Environmental Window (EW)?
EWs are time periods within which dredging is allowed Typically established using a biological metric (e.g. fish migration,
egg laying, larval development, etc.) Setting of EWs is controversial Data Gap: Lack of effects-based exposure data for suspended
sediments on species used to set EW EWs are the most frequently cited concern in the dredging program EWs impact dredging schedules and are costly
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US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
Effects of Suspended Sediments and Sedimentation
On SAV
On FishMigration
On corals
On Fish Spawning
On T&E Species
US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
Dredge Plume Spatial/Temporal ScalesInitial
Mixing Zone Near-Field Far-Field
sec
100s of meters 1,000s of meters
FLOW“Trace” Plume
Dredge
Time
Distance from dredge
minutes hoursmeters
US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
Other Sources of Resuspension
Tug Plume
Plume Generated
by Bow Thruster
US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
Applying Risk Assessment Paradigm to Manage Risk
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Exposure Assessment
Measuresof Effect
ProblemFormulation
RiskCharacterization
RiskManagement
Economic Analysis,Socio-Political,
Engineering Feasibility
Risk Assessment Paradigm
US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
Apra Harbor Case StudyProblem Formulation
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Identify receptors (coral) Identify/map coral density/diversity Identify sources of exposure
• Dredging as source of released sediment• Background suspended solids are near zero
and there are no outfalls or other land-based sediment sources to Apra Harbor
Identify exposure mechanisms• Total sedimentation from dredging project• Maximum sedimentation rate over any 24 hour
period• Light attenuation (represented by suspended
solids time history)
US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
Quantifying Exposure
• Quantify exposure from each risk pathway for each species in areas of concern
• Characterize risks to coral in Apra Harbor from 18 month dredging operation
• Quantify exposure:• Simulate sediment transport
and sedimentation over coral habitat – 100 scenarios modeled to bracket potential exposure
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Peak 24-hr TSS over coral
Total sedimentation for dredge cycle
US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
Combining Exposure and Effects to Characterize Risk
1. Estimate effects via literature review of risk to coral from sediment
2. Green/Yellow/Red light indicator created for coral species using exposure and effects estimates Green – minimal damage Yellow – some damage,
recovery expected Red – Significant die-off
3. Exposure thresholds mapped from sediment transport and sedimentation model
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3) Estimated coral effects for one scenario
2) Coral thresholds identified
1) Coral thresholds evaluated from literature
US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
Fish Larvae and Egg Exposure System (FLEES)
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US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
12
FISH LARVAE AND EGG EXPOSURE SYSTEM (FLEES)Developed to expose early life history stages of fish, shellfish, and other species to specified concentrations
and durations of suspended sediment or sedimentation in a controlled laboratory environment.
SUSPENDED SEDIMENTCapability
01FLEES allows for the design of experiments that simulate resuspension of sediment as a result of dredging operations or other factors such as vessel traffic, freshets, or storms.
SEDIMENTATIONCapability
02FLEES can be quickly retrofitted to accommodate the design of experiments that simulate sedimentation.
US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
13
AND
SUSPENDED SEDIMENT WORST CASE SCENARIO
WHY FLEES WORKS
A data acquisition device and LabVIEW software is used to integrate turbidity sensors with solenoid valves to build a computer application that both continuously monitors and records turbidity in each aquarium while introducing sediment from the slurry tank to maintain specific NTUs.
Individuals contained for a prolonged periods, with no escape from exposure to field-collected sediment of varying concentrations.
US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
EW Case study: Corals in Honolulu Harbor, HI
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Problem Concerns about suspended sediment and
sedimentation effects on corals are restricting dredging operations Exposure and effects-based data needed to
characterize and manage riskObjective Essayons dredging in HH to estimate exposure Investigate performance of corals exposed to
varying suspended sediment concentrations using FLEES Coordinate with HI coral experts
US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
Methods
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Effects Study• Exposure parameters - monitoring• Exposure regime to mimic dredging
operation• Concentrations (NTU & TSS)• Coral species/type and life stages• Short- and long-term effects• Endpoints (lethal and sublethal)• Source of corals• Source of test water and sediment• NMFS coordination
US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
Results indicate that detailed, site-specific knowledge of the dredge project, sediment type, and species life history can inform risk-based decision making regarding dredging effects on sensitive habitats
Exposure and effects-based data can reduce uncertainty in assessing risk associated with perturbations due to dredging
Combination of exposure and effects data can be effectively used to assess risk to species occupying sensitive habitats
Structured science-based approach can effectively assess risk to sensitive habitats for appropriately managing risk to these species
Summary
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US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
Environmental Windows Case Studies
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US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
The window applicable to Oakland Harbor dredging in the programmatic LTMS Biological Opinion is based on presence of salmonids, but given that the harbor is not connected to any tributaries and where it is situated in the Bay, it is reasonable to assume that salmon are not likely present SPN could consider pursuing a standalone Biological Opinion for
Oakland harbor to seek a dredging window that is less restrictive POC: Stephen Willis
Dredging Window Case Study #1 (SPN)
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US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
Under current programmatic LTMS EFH consultation eelgrass surveys are required to satisfy indirect effects of dredging and light monitoring for direct effects of dredging when within 250m of eelgrass beds Multiple surveys have been performed both in-bay and coastal.
Reports indicate that no net-loss of eelgrass occurred due to dredging and that there is no appreciable difference in light availability to eelgrass beds when dredging is occurring within 250m of the beds SPN is planning on coordinating with NMFS to remove at least the
light monitoring provision POC: Chris Eng
Dredging Window Case Study #2 (SPN)
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US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
Success Story Elimination of monitoring requirement for Caulerpa and grunion POC: Jim Fields
Dredging Window Case Study #3 (SPL)
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US Army Corps of Engineers • Engineer Research and Development Center
Sustainable Sediment Management and Dredging Seminar
6-8 March 2019 Sausalito, CAUNCLASSIFIED // FOR OFFICIAL USE ONLY
Discussion Points
What is the main basis for restricting dredging operations in your district?
What are ways in which we can overcome those restrictions?