US Army Corps of Engineers BUILDING STRONG®

The Particle Tracking Model: Determination of constituent fate in complex hydrodynamic and wave environments Speaker: Joseph Gailani Research Hydraulic Engineer

Research Group:

Tahirih Lackey, Zeki Demirbilek, Sung-Chan Kim, David King, and Pearce Cheng

Engineer Research and Development Center

October 25, 2012

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Total Suspended Solids (TSS) concentration light attenuation fish and larval migrations

contaminants sediment deposition

egg burial seagrass smothering

Issues: Effects of Sediment on Habitat (Exposure)

Areas in green depict seagrass

Data collection in center of the channel pathway

Dredging operation near sensitive sea- grass region (Panama City, Florida)

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Particle Tracking Model

Input Requirements

Grid/Bathymetry Data Hydrodynamic and/or

Wave Data ADH ADCIRC EFDC CH3D

Native Sediment Data User Defined Source

Data ► Dredging ► Placement ► CSOs

Time-dependent Particle Positions

P(t,X,Y,Z)

PTM/Surface-water Modeling System (SMS) Data Analysis Tools

Deposition Concentration Dose Exposure Accumulation Pathways Turbidity

PTM is a Lagrangian particle tracker that models transport processes (advection, diffusion, deposition, etc) for representative parcels to determine constituent (sediment, contaminants, biologicals, etc) fate.

PTM

PTM Dredge Source Description

User defines sources generated from: ► Dredge source models ► FATE models ► Known release rates

Sources From: ► Dredging operations ► Placement operations ► ODMDS erosion ► Overflow

Source strengths vary temporally and spatially (incl. vertically)

Each particle represents a defined mass of constituent and includes constituent behavior

PTM is currently linked to FATE models used by USACE Districts

Source terms are extremely important to accurate modeling. This is currently the focus of ongoing research.

Barge Placement Pipeline Placement

PTM/SMS Interface

The interface for PTM is found in the Surface Water Modeling System (SMS). The interface has been designed to be user-friendly and ultimately allow users to create mesh, hydrodynamics, source information for input, run PTM, and visualize and analyze output data.

Visualize Model Results:

• Particle Positions • Particle Pathways • Particle Count • Accumulation (mm) • Rate of Accumulation (mm/hr) • Deposition (mm) • Exposure (kg / m3) * hr • Concentration (kg / m3) • Dosage (kg / m3) * hr • Turbidity

(PTM/SMS Interface showing data at Apra Harbor)

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New PTM Capabilities

New features: High Performance Computing compiling platform Parallel processing Accepts hydrodynamic input as: 2D, 3D sigma, and now 3D z-grid Optimized time step option based on courant number Enhance particle location scheme to faster tracking

New capabilities have been added to PTM to allow users to track a larger number of particles, faster. These changes allow users to simulate more alternatives and bracket parameters which may have a known range but no definite value. Ultimately this leads to a better understanding of the constituent transport in the system and provides better support for decision making.

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PTM Project Examples ► CSO outflow sediment, constituents, and debris

(multiple sites) ► Sediment transport from dredges and dredged

material placement (multiple sites) ► Contaminant transport from dredges and dredged

material placement (multiple sites) ► Larval fish transport at Seabrook ► Egg transport in Newark Bay ► Water borne particulates on the Gulf Coast ► In general used for exposure estimates for risk

assessment in habitat

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Case Study: Predicting Coral Exposure Due to Dredging in Apra Harbor, Guam

The U.S. Navy is studying alternatives for the construction of a deep water wharf at Apra Harbor, Guam to provide a berthing site for nuclear powered aircraft carriers (CVN).

Development of a site would involve dredging at the wharf location and additional dredging to provide a turning basin and access fairway (dredge depth = 16 m) .

This work studies the exposure due to dredging at two of the considered sites: Polaris Point and Ship Repair Facility.

Apra Harbor, Guam

Objective: Model dredging alternatives and determine exposure to adjacent coral reefs. Then work with coral reef experts to help determine risk.

Problem : These sites are adjacent to large, diverse coral reefs, and there are concerns about the impacts of dredging.

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Navigation Footprint: Polaris Point

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Navigation Footprint: Ship Repair Facility

Dredging Protocols

•Clamshell Resuspension Sources: Impact Ascent/Descent Slewing

•Chiseling Resuspension Sources: Major Release at bottom

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Modeling Scenarios Case Production

Rate (yd3/day) Dredge Time

for Polaris Point (months)

% Loss Silt Curtain Efficiency

1 1800 12 2 90%

2 1800 12 1 100%

3 1110 18 2 90%

4 1110 18 1 100%

5 1800 12 1 90%

6 1800 12 2 100%

7 1110 18 1 90%

8 1110 18 2 100%

Cases 1 and 4 bracket the original maximum and minimum results and will be the focus of this presentation

Sedimentation Case 1: 1800 cyd - 2% loss - 90% effective silt curtain

(Deposition in g/cm2)

•The largest values are shown near Polaris Point and the Ship Repair Facility. •The majority of the sediment settles and accumulates within the dredging footprint.

Data Analysis Tables

(Outside of Dredging Footprint)

Case

Total Accumulation

Area (m2) greater than 0.5 g/cm2

Polaris Point Ship Repair Facility

1 78,400 96,000

4 56,000 70,400

Case

Maximum Deposition Rate Area (m2) greater than 0.01

g/cm2/day

Polaris Point Ship Repair Facility

1 252,800 313,600 4 148,800 187,200

Case

Maximum Concentration

Area (m2) greater than 0.01 kg/m3

Polaris Point Ship Repair Facility

1 161,600 118,400

4 44,800 4,800

Shown is the quantity of area outside of the dredging footprint for which the parameter (accumulation, maximum deposition rate, maximum concentration) is greater than the specified level.

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Summary, Conclusions and Future Work The transport of resuspended sediment due to dredging in Apra

Harbor has been simulated and analyzes is ongoing. Scenarios were developed to bracket the range of exposure

estimates using conservative assumptions. For total accumulation and deposition rate, preliminary analysis

shows that Ship Repair Facility results appear slightly higher. For both alternatives, maximum suspended sediment concentration

values are low (instantaneously < 0.02kg/m3). These maximum values occur only immediately at the site being dredged and then quickly dissipate.

Next step – coordinating with our team of coral reef biologists to interpret results.

Comparison of results with monitoring data if the project goes forward.

FAQ How can I get PTM?

► PTM is available free of charge to USACE employees. POC: Tahirih.C.Lackey@erdc.usace.army.mil

References: http://el.erdc.usace.army.mil/dots/doer/ptm.html

Do I have to use SMS to use PTM? ► PTM does work outside of SMS, however the data analysis tools

that create deposition, concentration, etc are a part of SMS. Also, source creation is much easier utilizing SMS.

How long does it take for the model to run? ► That depends primarily on the number of particles created, the

length of the simulation, and the speed of your machine. For a two week simulation with 50,000 particles on the average PC, should take less than a day to run.

How can I learn to use the model? ► Personal PTM workshops are available upon request. ► Additional Information: http://www.xmswiki.com/xms/SMS:PTM