Aquatic_Electric_Barrier_Design_Recommendations__100_Watermark.pdf

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Inland Navigation Design - Research Report

Finite Element Modeling of Aquatic Electrical Barriers: Voltage and Current Distributions Brandon Road Lock & Dam Interbasin Project: Electric Fish Deterrent Design Recommendations

Caylin A. Hartshorn and Benjamin E. Barrowes December 2022

Approved for public release; distribution is unlimited.

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Inland Navigation Design - Research Report ERDC/CRREL CAC-01-DF December 2022

Finite Element Modeling of Aquatic Electrical Barriers: Voltage and Current Distributions Brandon Road Lock & Dam Interbasin Project: Electric Fish Deterrent Design Recommendations

Caylin A. Hartshorn and Benjamin E. Barrowes Cold Regions Research Engineering Laboratory U.S. Army Engineer Research and Development Center 72 Lyme Road Hanover, NH 03755

100% Design Recommendations Report Approved for public release; distribution is unlimited.

Prepared for U.S. Army Corps of Engineers Washington, DC 20314-1000

Under B5IWLD03202104

Monitored by Rock Island District Rock Island, IL 61204-2004

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Abstract: Abstract: Invasive carp (black, grass, silver, and bighead) are na-tive to Asia. They were originally imported into the US during the 1970’s and 1980’s to help fish farmers manage water quality, fish parasites, and vegetation in their production ponds. Unfortunately, feral populations be-came established in the Mississippi River that have led to a decline in na-tive fish species. In an effort to prevent the upstream transfer of invasive carp from the Mississippi River Basin to the Great Lakes Basin through the Chicago Area Waterway System (CAWS), the US Army Corps of Engineers (USACE) operates a series of four pulsed DC electric dispersal barriers near Romeoville, IL in the Chicago Sanitary and Ship Canal (CSSC). To supple-ment the electric dispersal barriers in the CSSC, USACE was authorized to construct a series of aquatic nuisance species deterrents, including an electric deterrent, approximately 11 river miles downstream at Brandon Road Lock and Dam (BR) in the Des Plaines River at Joliet, IL. Throughout the BR electric deterrent design process, the dispersal barriers at CSSC have served as the prototype systems used in the development of the concepts. Addition-ally, USACE has worked with the U.S. Cold Regions Research Engineering Laboratory (CRREL) to develop a Finite Element numerical model (COM- SOL) that predicts voltage and electric current distributions for a given elec-trode and waterway geometry. In this report, we aim to briefly describe both present and past problems experienced at the CSSC electrical dispersal bar-riers, demonstrate how a numerical model can be used to understand these issues, and how these models were used to help guide the design of the BR electric barrier. Additionally, we discuss the methods used for determining safety limits and how the models are used to ensure voltage and current re-main within the determined thresholds for safety while optimizing the effi-cacy of the deterrent.

Disclaimer: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents.

DESTROY THIS REPORT WHEN NO LONGER NEEDED. DO NOT RETURN IT TO THE ORIGINATOR.

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Table of Contents Figures and Tables............................................................................................ v

Preface ........................................................................................................ viii

Acknowledgments ............................................................................................ ix

Unit Conversion Factors..................................................................................... x

1 Introduction

1.1 Project Overview

1.1.1 Electrostatics Review

1.1.2 Electric Fish Barrier Principles

1.1.3 Benefits of Finite Element Modeling

2 Previous CSSC Modeling

2.1 Assumptions Made Within the Model

2.2 Model Validation

2.3 Model Geometry

2.4 Effects of Electric Deterrent Efficacy when a Barge is Present

2.4.1 Electric Field Orientation Effects

2.4.2 Diminished Efficacy

3 Brandon Road 65% Design Recommendations

3.1 Approach Options

3.2 Electrode Orientation

3.2.1 Side Mounted Vertical Electrodes

3.2.2 Additional Orientations

3.3 Converting CSSC Parameters to BR

3.4 Channel Width

3.5 Electrodes

3.5.1 Number of Electrodes

3.5.2 Spacing

3.5.3 Shape

3.6 Electrically Grounding the Barge

3.7 Stray Electrical Current Analysis

3.7.1 Installation of a Non-Conductive Liner

3.7.2 Barge Tie Off Electrocution Current

3.8 Additional Recommendations

4 Brandon Road 95% Design Recommendations

4.1 High Fidelity Model Parameters

4.2 Approach Options

4.3 Channel Width

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4.4 Soil Conductivity Effects & Installation of a Non-Conductive Liner

4.5 High Fidelity 65% Design Analysis

4.6 Design Safety Considerations

4.6.1 65% Design Safety Considerations Analysis

4.6.2 Additional Cathode Downstream Analysis

4.6.3 Two Additional Cathodes Downstream Analysis

4.7 Stray Electrical Current Considerations

4.7.1 65% Design Analysis

4.7.2 Additional Cathode Downstream Analysis

4.7.3 Two Additional Cathodes Downstream Analysis

4.8 Comparison of the Three Designs

4.9 Electrodes

4.9.1 Number of Electrodes

4.9.2 Spacing

4.9.3 Shape

4.10 Additional Recommendations

4.11 Questions Still Outstanding

5 Brandon Road 100% Design Recommendations

References

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Figures and Tables

Figures

Figure 1. Electrical barrier near Romeoville, IL in the Chicago Sanitary and Ship Canal. 3 Figure 2. Voltage - physical representation Figure 3. Charges and the Electric Field Figure 4. Physical representation of the relationship between the electric field, electri-cal current density, and electrical current Figure 5. Block Diagram of Electric fish barrier circut Figure 6. Finite element model of an electric fish barrier Figure 7. Examples of equipment and electronics used to collect experimental data at

CSSC

Figure 8. Electrical conductivity values at CSSC obtained during testing. (a) Values of canal water over time. (b) Values of soil as a function of electrode spacing Figure 9. Electrode width − Plan set vs simulation. (a) Physical layout of wide and nar-row array showing 8 separate electrodes. (b) Electrical plan set showing all 8 electrodes are wired in parallel. (c) Electrodes used within the simulation Figure 10. Model results vs experimental data. Both sets of data were collected down the canal center at a depth of 2 ft. (a) Modeled results. (b) Experimental data Figure 11. Model geometry for CSSC Figure 12. Electric field when there is no barge. (a)-(b) Plan view showing the cut for (c)-(d) respectively Figure 13. Electric field when a barge is present. (a)-(b) Plan view showing the cut for (c)-(d) respectively Figure 14. Plan view of the electric field at the water surface. (a) When there is no barge.

(b) When a barge is present Figure 15. Field effects due to a barge. (a) Location of 4 line plots spanning the gap be-tween the sidewall and barge. (b) Electric field strength for these line plots Figure 16. Field effects due to a barge. (a) Location of 4 line plots in a tight group mid-way between the sidewall and barge. (b) Electric field strength for these line plots Figure 17. Short channel downstream approach option Figure 18. Bottom mounted horizontal electrodes vs side mounted vertical electrodes.

(a) Transparent view of the model so electrodes can be seen. (b) Plan view of results.

(c) Cut view of the vertical electrodes with a barge within the canal Figure 19. Two additional electrode orientations studied Figure 20. Effects of non-electrically grounded parasitics. (a) Plan view of CSSC model.

(b) Electrical field strength values for CSSC model. (c) Plan view of a simplified geom-etry model. (d) Electrical field strength values for simplified geometry model Figure 21. Depth Changes from CSSC to BR model. (a) Cut view showing dimensions of CSSC model.(b) Cut view showing dimensions of BR model Figure 22. Effects of depth change. (a) Electrical field strength values for simplified model at 26 ft depth. (b) Electrical field strength values for simplified model at 15 ft depth.

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Figure 23. Effects of additional grounded parasitics (cathodes). (a) Plan view of sim-plified model. (b) Electrical field strength values for simplified model. (c) Plan view of model with addional cathodes. (d) Electrical field strength values for model with ad-ditional cathodes Figure 24. Effects of channel width. (a) 110 ft wide channel. (b) 160 ft wide channel.

Figure 25. Physical layout of recommended electrodes Figure 26 Figure 27. Effects of barge moving closer to sidewall with bottom mounted electrodes.

Plan view of barge moving closer to the sidewall Figure 28. Effects of barge moving closer to sidewall with U-Shaped electrodes. Plan view of barge moving closer to the sidewall Figure 29. Geometry of U-Shaped electrode. (a) View of model with two electrodes. (b) Cut view of model with one electrode Figure 30. Grounded barge. (a) Plan view, grounded barge and U-shaped electrodes.

(b) Cut view, between electrodes. (c) Line plots, surface of the water between barge and sidewall Figure 31. Stray electrical currents in the soil. (a) Plan view showing the geometry of line plots. Data was collected at 25 ft., 60 ft., and 95 ft. off the wall. (b) Electrical cur-rent values when no barge is present. (c) Electrical current values when a barge is present. 33 Figure 32. Effects of soil conductivity on stray electrical currents. Three plan (birds eye) views of the model ran with three different values for soil conductivity Figure 33. Tie off electrocution current model. (a) Distance view showing all compo-nents of model. (b) Zoomed in figure of white box shown in part a. Wire rope is con-nected to barge (orange) and human (green) standing on concrete Figure 34. Past, current, and recommended electrode construction material. (a) Section of past bundled steel cables. (b) Section of current solid steel bar. (c) Recommended modular steel plate Figure 35. High fidelity model created for the 95% design. (a) Distance view of entire model with incorporated elevation data received from Rock Island District. (b) Zoomed in view showing different components of the model Figure 36. High fidelity model results of 65% design. (a) Plan (birds eye) view of the of design. Water above the liner (black) and electrodes has been removed for viewing.

(b) Plan (birds eye) view of electric field strength at the surface of the water Figure 37. High fidelity model line plot results of 65% design. (a) Plan (birds eye) show-ing the location of the surface line plot within the channel. (b) Electric field strength values for line plot at the surface. Upstream is to the right, with downstream to the left.

Figure 38. Safety zone threshold values. (a) Graphical representation of safety zones for a single DC pulse. (b) Electrical current values for a single DC pulse and the correspond-ing physiological effects. (c) Reduced electrical current and electrical current density val-ues for pulsed DC. The corresponding physiological effects for each zone remain the same.

Figure 39. Reduced DC safety zones shown over top a plan (birds eye) view of the 65% design. Each safety zone is color coded as described in the the figure. The total length of DC-3 and DC-4 is approximately 900 ft Figure 40. Additional cathode downstream design. (a) Plan (birds eye) view of the of design. (b) Plan (birds eye) view of electric field strength at the surface of the water (c) Electric field strength line plot at the surface Figure 41. Reduced DC safety zones shown over top a plan (birds eye) view of the ad-ditional cathode downstream design

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Figure 42. Two additional cathode downstream design. (a) Plan (birds eye) view of the of design. (b) Plan (birds eye) view of electric field strength at the surface of the wa-ter (c) Electric field strength values for line plot at the surface Figure 43. Reduced DC safety zones shown over top a plan (birds eye) view of the ad-ditional cathode downstream design Figure 44. Stray currents 70 ft. off channel wall, 65% model. (a) Plan view with line plot. (b) Cut view of the line plot through the entire half space Figure 45. Stray currents 70 ft. off channel wall, additional cathode downstream model.

(a) Plan view with line plot. (b) Cut view of the line plot through the entire half space. 54 Figure 46. Stray electric currents 70 ft. off channel wall for two additional cathodes down-stream model. (a) Plan view with line plot. (b) Cut view of the line plot through the entire half space of the model Figure 47. Comparison of electric field strength at the surface for all three designs. (a) Plan view of the graphical layout for the different designs. (b) Line plot data of the elec-tric field strength Figure 48. Reduced DC safety zones for all three designs. (a) 65% design. (b) One ad-ditional downstream cathode design. (c) Two additional downstream cathode design Figure 49. Numerical tables comparing all three designs. (a) Size of the DC safety zones.

(b) Maximum stray electric current density 70 ft. off channel wall Figure 50. Number of electrodes, anode, and cathode arrangement for both modified de-signs. (a) One cathode downstream design. (b) Two cathode downstream design Figure 51. Spacing of electrodes for both modified designs. (a) One cathode downstream design. (b) Two cathode downstream design Figure 52. Shape of electrodes for both modified designs. (a) One cathode downstream design. (b) Two cathode downstream design

Tables

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Preface

This report is split into five main chapters. The first chapter shortly dis-cuss the project overview and motivation for the Brandon Road Interbasin Project (BRIP). Additionally we will examine electric fish barrier princi-ples, a review of electrostatic, and the benefits of finite element modeling.

In the second chapter we aim to briefly describe both present and past is-sues experienced at the electrical barrier that is presently built and operat-ing at the Chicago Sanitary and Ship Canal (CSSC). This chapter will be supplemented by model validation process and assumptions made. In the third chapter we look to demonstrate how a numerical model was used to help guide the design of the Brandon Road electric barrier to a 65% level. In the fourth chapter we discuss how the principles from chapter 3 were built upon. We will examine a new high fidelity model that was created and how it helped guide the design to a 95% level. This chapter will be supplemented by analysis of the high fidelity model results and safety concerns which cul-minated in slight design differences between the 65% and 95% recommen-dations. Finally, in the fifth and final chapter we aim to wrap up any out-standing design considerations that were missing from the 95% recommenda-tions.

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Acknowledgments

The authors of this report would like to thank every individual that has participated in the Brandon Road Interbasin Project thus far. Designing, building, and operating an aquatic electrical barrier is a non-trivial task that requires addressing a multitude of different engineering considerations.

Many engineers, scientist, and professionals across ERDC, Rock Island, and Chicago District have provided essential ideas, opinions, and knowledge that have made this report possible. The authors would like to particularly thank Kirk Sunderman, Joseph Schulenberg, and Kent Rockow for their partici-pation and involvement. Their leadership, experience, and ability to work through engineering problems has been especially vital.

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Unit Conversion Factors

Multiply By To Obtain degrees (angle) 0.01745329 radians feet 0.3048 meters inches 0.0254 meters miles (nautical) 1,852 meters miles (U.S. statute) 1,609.347 meters pounds (mass) 0.45359237 kilograms

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1 Introduction

1.1 Project Overview

Invasive carp (black, grass, silver, and bighead) are native to Asia. They were originally imported into the US during the 1970’s and 1980’s to help fish farmers manage water quality, fish parasites, and vegetation in their pro-duction ponds. They held promise as a new product to sell as food and as a valuable non-chemical replacement for the pesticides to be used in lakes, reservoirs, and water treatment facilities. Unfortunately, feral populations became established in the Mississippi River that have led to a decline in na-tive fish species. They grow quickly and after the first six months of life are too large for natural predators to eat. Two of the invasive carp species, the silver and the bighead carp, are filter feeders that consume 20-40% of their body weight per day, causing strain on any ecosystem they are a part of.

They are notorious for out competing other fish for both food and space [1].

As populations expanded, so did efforts to control their movements between the Mississippi River Basin and the Great Lakes Basin. The Great Lakes fishing industry is of great importance to both the Canadian and United States economies, with an estimated value of over $7 billion a year [2]. Thoug-ghts on the exact negative economic impact invasive Carp would effect this industry vary. However, it is agreed that if invasive carp become well estab-lished within the Great Lakes Basin (GLB) there will be a heavy toll on jobs, businesses, and communities [2]. In an effort to prevent the upstream transfer of invasive carp from the Mississippi River Basin to the Great Lakes Basin through the Chicago Area Waterway System (CAWS), the US Army Corps of Engineers (USACE) operates a series of four pulsed DC electric dispersal barriers near Romeoville, IL in the Chicago Sanitary and Ship Canal (CSSC). Part of the barrier and it’s location are shown in Figure 1. A demonstration dispersal barrier (Barrier I) has been operating since 2002. A more permanent dispersal barrier was constructed in two segments, Barriers IIA and IIB, which began full-time operation in 2009 and 2011, respectively.

The most powerful barrier, Permanent Barrier I, became fully operational in 2022.

Additional deterrents have been authorized for the CAWS to address vul-nerabilities in the current system. To supplement the electric dispersal bar-

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riers in the CSSC near Romeoville, USACE was authorized by to construct aquatic nuisance species deterrents approximately 11 river miles downstream at Brandon Road Lock and Dam (BR) in the Des Plaines River at Joliet, IL.

The BR dispersal barriers will become a front line of defense in the CAWS for protecting the Great Lakes from aquatic invasive species, backed up and supported by the electric dispersal barriers already in place.

In 2014 USACE evaluated potential options and technologies to further pre-vent the upstream Interbasin transfer of Aquatic Nuisance Species (ANS) [3]. This report identified a recommended plan that was signed and sent to congress in 2019. The authorized plan identified Brandon Road Lock and Dam as the best control point on the Illinois Waterway to place a gantlet of deterrents to prevent movement of aquatic nuisance species from advanc-ing upstream to the Great Lakes. Acoustic, electric, bubble deflection, au-tomated barge clearing, and flushing lock make up the gantlet of authorized deterrents. An engineered channel and boat ramps are included within the authorized plan and serve as key structural components of the project. For detailed documentation of the process and deterrents selected for BRIP, re-fer to the authorized feasibly study[4]. Authorization for Pre-Construction Engineering and Design (PED) for the Brandon Road Interbasin Project (BRIP) was signed in December 2020. The analysis within this report was completed in an effort to guide the PED for BRIP [5].

USACE Chicago District, has over 20 years experience testing the efficacy, minimizing the risk, and researching best practices for operating an electric dispersal barrier. Throughout the BRIP electric deterrent design process, the dispersal barriers at CSSC have served as the prototype systems used in the development of the concepts. For a detailed account of this information and the work done refer to the Dispersal Barrier Efficacy Study reports [6, 7] and the references therein.

1.1.1 Electrostatics Review

The system currently built and operating at CSSC consist of arrays of elec-trodes driven by repetitive (4–5 Hz) high-voltage DC (direct current) pulses [8].

This pulsed repetition frequency is so low, and thus slow, that it can be an-alyzed via electrostatics. That is, electric charges are at rest and electric fields do not change with time. Within this report there are four main quan-tities discussed − voltage, electric field, electrical current density, and elec-trical current.

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(a)

(b)

Figure 1. Electrical barrier near Romeoville, IL in the Chicago Sanitary and Ship Canal

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Figure 2. Voltage - physical representation.

Electrons gain potential energy when they move away from positive charge and toward negative charge. They lose potential energy as they flow through a finite conducting medium. This potential energy difference is measured in voltage (V ). Voltages are a mathematical scalar and are referenced to each other. This concept is illustrated in Figure 2.

Atoms consist of electrical charges − electrons (negatively charged), neu-trons (no charge) and protons (positively charged). Each isolated charge is surrounded by an electric field in space. For positive charges the electric field points away from the charge. For negative charges the electric field points toward the charge. The electric field from each isolated charge creates a force between them. Where like charges repel and opposite charges attract.

This phenomenon is shown graphically in Figure 3. The electric field at an arbitrary location is the force a test charge would experience at that loca-tion. Mathematically the electric field is defined as the voltage gradient, is thus a vector measured in V olts/meter, and written as:

E = −∇V (V olts/meter) (1)

If electric charges are moving, then this flow of charges is known as electric current and is measured in Amps (A). Electrical current, I , must flow through a finite area, such as the cross section of a conducting wire. Thus, it is not a value at at a specific point in space. Electric current density, J , is a point function, and defined as the amount of current flowing through a unit area. Thus, it is measured in Amps/meter2. The electrical current

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Figure 3. Charges and the Electric Field

Figure 4. Physical representation of the relationship between the electric field, electrical current density, and electrical current.

can be calculated by summing up the electrical current density over the area charges are flowing. Mathematically this is written as:

I =

J dS⃗ (2)

J A (Amps) (3)

When electrical currents are in a medium with finite conductivity, σ, electric current density can be related to the electric field by the following equation:

J = σ

E (Amps/meter2) (4)

These relationships are illustrated in Figure 4.

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Equation 4 is analogous to ohm’s law. Equation 1 shows us how the elec-tric field is related to voltage. Equation 3 shows us how electrical current is related to electrical current density. Thus:

J = σ

E ⇐⇒ I = σ V (where σ =

R ) (5)

1.1.2 Electric Fish Barrier Principles

Electrofishing is a not a new concept, with designs and implementations dat-ing back to the 1950’s. As the name suggests, the original idea was using the electric fields to lower the physical effort required and increase the efficacy of commercial fishing [9]. Although fishing is not objective for the electric bar-riers currently operating at CSSC and being designed for the BRIP, many of the same concepts are used. Figure 5 shows a high level block diagram of how the electrical circuit operates.

Figure 5. Block Diagram of Electric fish barrier circut.

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When pulsed DC is used, a processed called electrotaxis often occurs. Elec-trotaxis refers to the phenomenon that fish tend to swim involuntarily to-wards the high field strength region, the anode. As they swim closer to the anode they are eventually stunned. This involuntary swimming is compara-ble to normal swimming. However, the movements are much more forceful and intense [9].

This process is much less efficient and effective in water with high conduc-tivity, such as saltwater. The electrical power required to effectively work is increased drastically [6]. It can be shown that the volume of water that can effectively shock a fish is:

U = Pρ

E2η (6)

Where P = Generator Power, ρ = Water Resistivity, E = Electric Field, and η = Pulse duty cycle. Water conductivity, both seawater and fresh waster can be quite variable [9]. However, seawater is typically 2 to 3 orders of magnitude higher in conductivity than freshwater [10]. Therefore, from Equation 6 we can see that for all other things equal, freshwater can have an effective volume of 100− 1000 times larger.

Pulsed DC is considered the state of the art method. This is because pulsed DC is cheaper than pure DC and more effective than AC. For peak voltages that are equal, pulsed DC induces a larger electrotaxic effect than pure DC.

This results in saving money on energy consumption. Additionally, AC does not typically induce electrotaxis, but electronarcosis[9]. This is somewhat ef-fective on larger fish because they respond to much lower electric field (cur-rent) values. However, it is not nearly as effective on smaller fish[9]. Differ-ent fish don’t just respond to different electric field values differently. They responded differently to pulse shapes, rates, and duty cycles. This means, there is no consensus on the best choice for these characteristics. Instead, it relies heavily on the practical conditions and experimental studies for a given scenario[9].

1.1.3 Benefits of Finite Element Modeling

There are several benefits to developing a finite element model, similar to that shown in Figure 6, during the PED. Setting up a model indeed creates an added expense at the beginning of a project. However, the cost savings down the road as well as the added benefit to the design are incredibly valu-

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Figure 6. Finite element model of an electric fish barrier.

able. One of the largest benefits to developing a model during the design phase is the ease and speed at which changes can be made. That is, once a model is built up, making drastic fundamental changes to the design can be implemented and discussed. Consequently, allowing for the design to maxi-mize efficacy and safety.

Collecting experimental data is a burdensome task. Acquiring data from an electric fish barrier is a non-trivial and requires individuals with specific ex-pertise. The coordination and travel required to ensure that qualified in-dividuals are available to collect the data is time-consuming and therefore expensive. Additionally, the electronics and equipment needed are often very specialized. Again, this makes for an added cost. Being able to reduce the number of times that experimental data is collected, even by just by a few, is a large advantage. Photos with pictures of experimental equipment used at CSSC are shown in figure 7. Another added benefit to developing a model is the ability to verify experimental results against theoretical results. When there is large agreement between these results the design team is given con-fidence that the safety measures and efficacy of the barrier will function as designed.

(a) (b) (c)

Figure 7. Examples of equipment and electronics used to collect experimental data at

CSSC.

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2 Previous CSSC Modeling

2.1 Assumptions Made Within the Model

Several assumptions were made over the course of this study. Some of these assumptions were only used during modeling for CSSC, and some of them were again used for the developed model of Brandon Road Lock and Dam.

The conductivity of the water within the canal can be quite variable over the course of time. This is due in large part because of the salt used on the roads during the winter. Substantial portions of the salt run off the roads and into the river system. As can be seen in figure 8a, the conductivity has a wide range . For much of this study a weighted average value for the con-ductivity of the water has been used as a bulk parameter, 0.1 S/m (with an electrical permittivity of ϵr = 80). As discussed earlier, the efficacy of an electric fish barrier is greatly diminished when the conductivity of the wa-ter increases from that of freshwater. However, this decrease in efficacy is largely offset by the fact that invasive carp are significantly less active dur-ing the winter. That is, they do not have the motivation seen during the warmer months to move upstream. This phenomenon has been characterized in many reports by CSSC. So, it might seem prudent to develop a model, and thus design around the worst case scenario, the highest water conduc-tivity seen. However, this does not match the best approach that has been proven over the past 20 years by CSSC. The threat of invasive carp moving upstream is near non-existent during the winter months. For this reason, the design team agreed the best approach was to develop a model and thus de-sign a barrier around electrical conductivity values of the canal water during the period that is the greatest threat.

Another assumption that was used during the modeling of CSSC is the elec-trical conductivity of the soil. Again, a weighted average value was used within the model as a bulk parameter, 0.004 S/m (with an electrical per-mittivity of ϵr = 8). In reality the electrical conductivity of the soil changes as a function of both space and time. A closer approximation would be to split up soil half space within the model into several smaller sections. Each section would then have a value of conductivity that was determined dur-ing testing. However, the effects of adding this much detail into the model would be minimal to the overall results. Especially when compared to the development time and processing power needed for this level of detail. A

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(a) (b)

Figure 8. Electrical conductivity values at CSSC obtained during testing. (a) Values of canal water over time. (b) Values of soil as a function of electrode spacing.

graph showing the electrical conductivity values found at CSSC during test-ing is shown in figure 8b.

Building and installing the electrodes used for the wide and narrow arrays is not an easy task. At CSSC, both the anode and the cathode consist of 8 distinct 5”x 5” square electrodes. For the wide array these electrodes are sep-arated by approximately 2 feet and for the narrower array these electrodes are separated by approximately 1 foot. For both the anode and the cathode these eight distinct electrodes are wired in parallel. That is, they are elec-trically connected together and held at the same electric potential. This can be seen from the CSSC design plans shown in Figure 9. However, for the de-veloped model one large electrode was used in place of 8 separate electrodes wired in parallel. As shown in Figure 9 , the one large electrode within the model was built equal in width to the eight separate electrodes. This was done and then effort to decrease computational time. The computational ef-fort needed for eight separate electrodes is exponentially higher than what is needed for one wide electrode. It is understood that near the electrode the modeled results will deviate from the fields that are physically present in the canal. However, the data we are most interested in is located near the sur-face to approximately 12 feet below the surface of the water. This is because the electric fields are strongest near the electrodes and diminish as they get further away. Therefore, the area with the lowest fields and thus of greatest concern is right at or near the surface of the water. As you will see in the next section the difference in field values between 8 separate electrodes and one large electrode is extremely minimal.

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(c)

Figure 9. Electrode width − Plan set vs simulation. (a) Physical layout of wide and narrow array showing 8 separate electrodes. (b) Electrical plan set showing all 8 electrodes are wired in parallel. (c) Electrodes used within the simulation.

2.2 Model Validation

To gain confidence in the concept model developed for Brandon Road In-terbasin Project, results were tested against experimental data collected at CSSC. The similarity of these results can be seen in figure 10. Where figure 10a is of the modeled results and figure 10b is from data obtained experi-mentally. Details about the experimental data can be found in [11]. From that report data was collected over various scenarios, such as location within the lock and depth. For this report we have provided model results from a run in [11], that stated “Data was collected from canal center at a depth of two feet.” In [11], peak values during this run for the wide array ranged from 0.85 to 2.53 V/in and 2.48 to 2.6 V/in for the narrow array. As you can see from figure 10a, the values given by the model for this scenario was

0.87 V/in for the wide array and 2.53 V/in for the narrow array. Both val-ues agreeing strongly with what was collected experimentally.

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(b)

Figure 10. Model results vs experimental data. Both sets of data were collected down the canal center at a depth of 2 ft. (a) Modeled results. (b) Experimental data.

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2.3 Model Geometry

This section is provided so that the geometry for the CSSC model can be seen. Figure 11 shows all of the relevant dimensions and values for this model.

Figure 11a is a plan (Birds Eye) view from above the canal. Figure 11b is a cut view of the canal showing the depth of different characteristics. Lastly, figure 11c shows the electric potential values for each electrode within the model.

(a)

(b)

(c)

Figure 11. Model geometry for CSSC.

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2.4 Effects of Electric Deterrent Efficacy when a Barge is Present

It is widely known that the presence of a barge, when near the CSSC electri-cal fish barrier arrays, alters the electric fields. In the past, experimentally, its been shown the presence of a barge has a substantial negative impact on the efficacy of these barriers [12, 6]. However, there has been little work on theoretical 3D modeling characterizing the electric and current density vec-tor fields in the presence of a barge. This section and the subsections within will use the developed CSSC model to analyze and discuss what happens to the electric field when a barge is present. Many of the lessons learned from this study heavily influenced the design at Brandon Road.

2.4.1 Electric Field Orientation Effects

When there is no barge the electric field within the canal looks like that as shown in figure 12. Figure 12a and 12b show a plan (Birds Eye) view of the cut for figure 12c and 12d respectively. The electric current aims to flow from the positive electrode (anode) to the negative electrode (cathode).

The electrons want to flow in the path of least resistance, this path is in a straight line between the positive and negative electrodes. However, elec-trons are of like charge and therefore also repel each other. That is, if a path becomes too congested, they will find a new path. This results in electrons flowing in all directions. Shown in figure 12c current is flowing from the an-ode to the cathode most strongly in a straight line, however, as this path be-comes congested the electrons begin fanning out wider towards the surface of the water. This phenomenon is also shown in figure 12d, where the strength of the electric field within the canal is a function of depth. That is, the field is strongest at the bottom of the channel when it is closest to the electrode and gradually decreases as it moves further away towards the surface of the water.

A barge is made out of steel, and is therefore many orders of magnitude more conductive than the surrounding water. This large block of high con-ductivity steel alters the characteristics of the electric field values within the canal as shown in Figure 13. Again, Figure 13a and 13b show a plan (Birds Eye) view of the cut for figure 13c and 13d respectively. Once more the elec-trons wish to take the path of least resistance. When a barge is present, there is a giant block of high conductivity steel near the electrodes. This creates a low resistance path between the anode and cathode. Resulting in a substantial amount of electrical current leaving the anode headed up (+z direction) towards the barge, moving across the barge, and back down to-wards the cathode (−z direction). This phenomenon is illustrated in Figure

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(c) (d)

Figure 12. Electric field when there is no barge. (a)-(b) Plan view showing the cut for (c)-(d) respectively.

13c. The change in electric field orientation raises two questions - (1) Do in-vasive carp react differently when the majority of the field is orientated in the positive and negative vertical direction opposed to the horizontal direc-tion? (2) When the field shifts to being orientated mostly vertical, the width of the array that is above the determined necessary threshold shrinks. Is it still wide enough to deter the invasive carp as designed? The design team presented these questions to the lead research biologist. The design team was assured that for the field strength values used at CSSC neither of these effects would have a large impact on the efficacy of the electric fish barrier.

That is, although invasive carp do react differently to different field orienta-tions the field the strength used at CSSC is high enough such that there is no impact. Additionally, the width of the array does impact a barriers abil-ity to deter invasive carp, but again, the field strength used at CSSC is high enough to limit the impact of this change.

The low resistance path created by the barge has two different effects - (1) directly above the anode and cathode and (2) between the anode and cath-ode. Figure 13d shows these two different effects. For the cut view directly over the anode and cathode, the electric current flows at an angle towards the barge opposed to being uniform across the width of the channel. This re-sults in a considerable drop in field strength near the side walls of the chan-nel. For the cut view between the anode and cathode, the electric current is using the barge as a bridge between them. Therefore, electrical current is running on the outer shell of the barge. This results in a substantial drop in field strength in the water in close proximity surrounding the barge. These two different effects combine with each other to create an area of concern within the fish barrier. That is, the barge creates a path that is under the necessary threshold to deter invasive carp.

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(c) (d)

Figure 13. Electric field when a barge is present. (a)-(b) Plan view showing the cut for (c)-(d) respectively.

2.4.2 Diminished Efficacy

As mentioned in the section above, without a barge present, because the electrodes span the width of the canal, the electric field is roughly uniform perpendicular to water flow as shown in figure 14a. That is, the electric field profile doesn’t change appreciably as a function of distance across the canal.

This same conclusion can be made from Figure 12d, a slice of the electric field across the canal. Without a barge present, the field is fairly uniform across the canal but changes strength as a function of depth.However, when a barge is present there is a path created below the determined necessary field strength threshold. Resulting in a preferred path for the fish. The pre-ferred path starts near the sidewalls, drifts in towards the barge, and finally drifts back out towards the sidewalls. This path is shown in figure 14b.

(a) (b)

Figure 14. Plan view of the electric field at the water surface. (a) When there is no barge.

(b) When a barge is present.

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Line plots at the surface of the water were used to analyze the diminished field strength due to a barge in more detail. Assuming a two-barge wide tow, there is roughly 90 feet of water, 45 feet on each side in the canal which is 160 feet wide. Initially, four line plots were placed spanning the 45 feet on one side between the sidewall and the barge. The location of these four line plots are shown in Figure 15a with their corresponding values shown in Figure 15b. From these figures you can see that near the shore (dark blue curve, Figure 15b), the electric field is largely unchanged because the conducting barge is far enough away that the electric current prefers to go through the water instead of all the way to the barge and back. At the other extreme near the barge (light blue curve, Figure 15b), the electric current turns into the barge and then back out of the barge at the cathode. Note, as discussed in the previous section, the electric field is still relatively strong, but its direction has changed. Thus the deterrent is still largely effective above the electrodes and near the shore. In both cases, the electric field re-mains at least 80% of its strength compared to when the barge is absent.

The worst case for the electric field strength above the electrodes is approxi-mately midway between the shore and the barge.

(a)

(b)

Figure 15. Field effects due to a barge. (a) Location of 4 line plots spanning the gap between the sidewall and barge. (b) Electric field strength for these line plots.

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Four new line plots were used in a tighter grouping around the midway point.

The location of these four line plots are shown in Figure 16a with their cor-responding values shown in Figure 16b. At this approximate midway point (red curve, Figure 16b), the electric field drops to around 1.4 V/in compared to its maximum of 2.53 V/in, a 45% reduction. Figure 13d presents this in-formation in a slice of the electric field across the canal both above the an-ode and at the midpoint between the two electrodes. It is true that right near the barge hull (at the midpoint between the electrodes), the electric field is very small because the current prefers the metallic barge to the less conducting freshwater. However, in order to get to that point near the hull, the fish must swim through the area of high electric current above the elec-trodes. This number of a 45% reduction then looks like the worst case re-duction of the field strength: near the water surface, just above the anode.

This reduction can be applied with more confidence now to future designs.

If BRIP can operate to produce a 6 V per inch electric field with no barge present, the expected worst case electric field with a two wide tow barge present would be around 3.3 V per inch.

(a)

(b)

Figure 16. Field effects due to a barge. (a) Location of 4 line plots in a tight group midway between the sidewall and barge. (b) Electric field strength for these line plots.

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3 Brandon Road 65% Design Recommendations

3.1 Approach Options

Figure 17. Short channel downstream approach option

Two main approach options were discussed during the Brandon Road Inter-basin Project − Electrical Deterrent Charrette: (1) The long channel down-stream approach and (2) the short channel downstream approach. All engi-neering design and cost considerations favored the short channel approach.

However, the long channel approach would allow for larger standoff distances from the electric barrier electrodes. At the time of the 65% design recom-mendation submittal the authors believed initial models demonstrated safe electrical current values could be achieved within the short channel approach option. However, it was agreed that the high fidelity model would need to agree with this analysis.

Design Recommendation: Short channel downstream approach option.

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3.2 Electrode Orientation

One of first tasks addressed was the physical geometric orientation of the electrodes. As seen in Chapter 1, CSSC used electrodes that were mounted to the bottom of the channel with a span equal to the canal width. How-ever, early on in the BRIP design process the question was raised whether this was the most efficient and effective design. Several different orientations were suggested, modeled, and studied.

3.2.1 Side Mounted Vertical Electrodes

Figure 18 demonstrates the results for bottom mounted horizontal elec-trodes vs side mounted vertical electrodes. A transparent view of the model is shown in Figure 18a so the electrodes can be seen. In Figure 18a and Fig-ure 18b the bottom mounted electrodes are located on the left hand side of the model with the side mounted electrodes on the right hand side. The ver-tical side wall mounted electrodes mimic a giant capacitor where the canal water serves as the dielectric material. A plan (birds eye) view from above the model of the results are shown in 18b. For this figure results are located at the surface of the water. For this study the horizontal electrodes were set to 2200 V with the vertical electrodes set to 4400 V. Although the hor-izontal electrodes were set to a higher initial voltage, the total power was approximately 24 kW, opposed to approximately 18 kW for the vertical elec-trodes. The vertical electrode orientation could have been studied more by bring the total power consumption closer together and then discussing engi-neering trade offs. However, a large discrepancy was quickly noticed. A cut view of Figure 18b is shown in Figure 18c. However, for this study a barge was placed within the canal. Barges are made mostly of steel and are thus many orders of magnitude higher in conductivity than the water. For a ver-tical arrangement of electrodes, the electrical current runs from one side of the canal to the other. When a barge is present, the electrical current uses it as a bridge to cross the canal. This leaves a huge gap underneath the barge and is not a feasible design.

3.2.2 Additional Orientations

Several more orientations were looked at, such as those shown in Figure 19.

However, similar to the vertical electrodes shown in Figure 18, the additional orientations modeled revealed points of concern. Either the field strength did not meet the threshold needed at the surface of the water or the presence of a barge created similar problems to those shown in 18c.

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(b)

(c)

Figure 18. Bottom mounted horizontal electrodes vs side mounted vertical electrodes. (a) Transparent view of the model so electrodes can be seen. (b) Plan view of results. (c) Cut view of the vertical electrodes with a barge within the canal.

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Figure 19. Two additional electrode orientations studied.

3.3 Converting CSSC Parameters to BR

As discussed in the previous chapter through previous work at CSSC we had built up confidence in our model. There are many differences between the barriers seen at CSSC and those that will be located at BR. In order to maintain confidence in the model parameters were changed one at a time to match BR. Within this section we will discuss three parameter changes – simplified geometry, channel (water) depth, and parasitic zeros. Many of the figures within this section compare data at the same location across different scenarios. All data plotted are line graphs that run the length of the chan-nel, at the surface of the water, for different distances off the canal wall. The four distances for which data is plotted is 23 ft. (blue), 29 ft. (green), 33 ft.

(red), and 38 ft. (turquoise) off the canal wall. The location of these lines can be seen in Figure 20a

a. Simplified Geometry: As discussed in the previous chapter CSSC placed non-electrically grounded parasitic between the barriers. At the time of their implementation it was believed the parasitic helped to minimize the stray electrical current within the channel. However, as can be seen in Figure 20, when the parasitic is not electrically grounded they add little value. A similar electric field within the channel can be achieved without them. Figure 20a is a plan view of the geometry, parasitics, elec-trodes, and line plots taken at CSSC with the corresponding electrical field strength values given in Figure 20b. A plan view of a simplified geometry, a single anode and cathode are shown in 20c with the cor-responding electrical field strength values given in Figure 20d. For this reason it is not recommended that BR use non-electrically grounded par-

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asitics. However, as will be discussed in later electrically grounded para-sitics do create many advantages, and will be recommended. In an effort to differentiate from the parasitics seen at CSSC the phrase “electrically grounded” parasitic, or simply cathode, will be used when discussing the design for BR.

b. Channel (Water) Depth: The average depth seen at CSSC is approxi-mately 26 ft, while the approximate average depth at BR is 15 ft. The model geometry was adjusted to accommodate this difference. Figure 21 shows all of the relevant dimensions that were altered. Figure 21a is a cut view of the model for CSSC and Figure 21b is a cut view of the model for BR.

(a) (b)

(c) (d)

Figure 20. Effects of non-electrically grounded parasitics. (a) Plan view of CSSC model.

(b) Electrical field strength values for CSSC model. (c) Plan view of a simplified geometry model.