Fish_Barrier_Letter_Report _Man_Overboard_(2006-02-15).pdf

ERDC/CERL February 2006

ENGINEERING ANALYSIS OF THE CHICAGO SANITARY AND SHIP CANAL

ELECTRIC FISH BARRIER: ELECTRICAL EFFECTS ON PERSONNEL IN THE

WATER

Vincent Hock, Michael McInerney, Tarek Abdallah, Paul Nielsen, Thomas Lilly, Charles Shea, and Tad Britt

US Army Engineer Research and Development Center Construction Engineering Research Laboratory

PO Box 9005 Champaign, IL 61826-9005

ERDC/CERL Letter Report February 2006

ENGINEERING ANALYSIS OF THE CHICAGO SANITARY AND SHIP CANAL

ELECTRIC FISH BARRIER: ELECTRICAL EFFECTS ON ON PERSONNEL IN THE

WATER

BACKGROUND

The US Army Corps of Engineers Chicago District is operating a temporary electric field-based fish barrier in the Chicago Sanitary and Ship Canal, Romeoville, Illinois. The barrier was constructed by Smith-Root Inc, sole licensees of the U.S. patent (Smith 1988), to prevent the encroachment of invasive species, such as the Asian Carp (Rasmussen 2001) into the Great Lakes. The barrier had been in operation for a little more than two years when, in May 2004, an electrical discharge-related incident in the vicinity of the barrier was reported. This incident involved tow assembly operations over or very near the barrier. During preliminary discussions between ERDC-CERL, the Coast Guard, and the Chicago District, it was emphasized that it is crucial to prove this type of barrier is safe for barge and boat operation.

The barrier consists of two electrode arrays (uninsulated metal conductors) perpendicular to the water flow and near the bottom of the canal. A high voltage pulse applied between the electrodes creates an electric field in the water. Fish receive progressively higher voltage shocks as they approach and attempt to cross the electric field generated by the barrier, so they turn away from it. At the time of testing, the electrode arrays were configured to pulse simultaneously with a 4 ms (millisecond) pulse width, five times a second, with opposite polarities. The pulse width of 4 ms and ‘off’ duration of 196 ms results in a 2% duty cycle.

ERDC-CERL is grateful for the assistance of Illinois Marine Towing and Garvey Marine, who provided barges, towboats, and crews for the barge measurement exercises; and the assistance of the Chicago District, who provided the Boston Whaler and pilot for the field mapping exercises. Individual acknowledgements are listed the Acknowledgements section of this report.

OBJECTIVE

ERDC-CERL proposed to support the Chicago District by conducting electric field measurements to determine the magnitude of electrical potential buildup for various barge and hull configurations passing over the barrier. Separate measurements would be made to map the electric field downstream, within, and upstream from the barrier. The objective of these tests was to determine:

• The physical extent of the electric field generated by the fish barrier.

• The amount of polarization or voltage buildup on a boat or barge as the boat or barge passes over the barrier. These measurements were intended to identify and quantify any voltage buildups during normal barging operations.

• The possible potential or voltage differences within a barge tow and between a barge tow and earth ground in different configurations inside and outside the fish barrier perimeter. These measurements were intended to determine if the potential exists for static electrical discharge between barges and boats.

• The voltages that a person in the water might be exposed to. These measurements consisted of a detailed barrier field measurement and a number of measurements with a “dummy” in the water over the barrier.

APPROACH

In order to address these objectives, ERDC-CERL, in conjunction with representatives of the Chicago District and the U.S. Coast Guard, developed the following tasks.

1. Map the electric field resulting from operation of the barrier (first objective).

2. Measure voltage potentials between the components of a tow passing through the barrier, for three typical tow configurations (third objective).

3. Measure voltage potentials between a tow passing a moored barge while in the barrier (third objective).

4. Measure voltage potentials between a tow and a moored barge, while the tow is approaching the moored barge over the barrier (third objective).

5. Measure voltage potentials between a tow and the barrier system ground while the tow is traversing the barrier (third objective).

6. Measure the voltage potentials between electrically isolated stationary barges while one is parked over the barrier (task added by Project Leader during testing).

7. Measure and quantify of the degree of barge and tow electrical potential buildup on the hull while traversing the barrier (second objective).

8. Measure the electrical continuity between the engine drive shaft and engine block of a typical towboat (task added by Coast Guard during testing).

9. Fine resolution mapping of the electric field resulting from operation of the barrier (fourth objective).

10. Measure the vertical (head to toe) voltages that a person in the water over the barrier might be exposed to (fourth objective).

11. Measure the potential difference between the upper electrode (water surface) and the fence (system ground) while over the barrier (fourth objective).

12. Measure the potential difference between the upper electrode (water surface) and the towboat while over the barrier.

13. Measure the touch potentials and touch currents of a person touching the canal wall over the barrier (task added by Coast Guard after March testing).

The experiments were conducted in three periods, between 5 and 7 January 2005, between 2 and 3 March 2005, and on 15 September 2005. Environmental data are listed in Table 1.

The January tow measurements were made with the aid of the “Albert C” owned by Illinois Marine Towing. This boat was not available for the March measurements and the “Joe Avery” owned by Garvey Marine was used for parallel barge configuration measurements. Experiments were conducted along various routes in the canal (i.e. east bank, center, west bank, upstream, downstream) in order to completely survey the influence of the fish barrier. Barges were fully loaded to maximize hull exposure in the water. The September measurements were assisted by the Corps of Engineers Chicago District’s “whaler.”

The magnitude (absolute value) of the measured value is significant for this analysis. Except for task 7, the sign (positive or negative) of the measurement is unimportant. For these experiments, the sign was determined arbitrarily, based solely upon which lead was connected to the common (reference) terminal of the instrument. Instrument connections were selected for expediency and convenience, not for physical reasons. Instrumentation is described in more detail in Annex 1.

Tasks 1 through 8 are reported in ERDC/CERL Letter Report LR-05-2, “ENGINEERING ANALYSIS OF

THE CHICAGO SANITARY AND SHIP CANAL ELECTRIC FISH BARRIER: ELECTRICAL

EFFECTS ON BARGES AND TOW VESSELS,” May 2005.

Task 9 – Fine resolution mapping of the electric field, Experimental Approach

In order to obtain worst case results for the personnel safety (“man overboard”) experiments; it was proposed to conduct the measurements in the highest field region of the fish barrier. Because the electric field measurements performed for Task 1, “Map the electric field resulting from operation of the barrier,” traded voltage sensitivity for spatial resolution, these measurement results were not adequate for accurately identifying the location of the maximum field strength. Since the electrode horizontal spacing for the Task 1 measurements was about 17 feet, the spatial location of a sharply peaked field gradient with a horizontal dimension of less than this (e.g., directly over the barrier) can not be resolved accurately with that data. Additional factors included the instrumentation data rate, settling time, multiplexing rate and boat speed contributed to the inadequacy of these measurements. Due to these factors and the advantage of examining actual empirical data, additional fine resolution electric field measurements directly over the barrier were necessary prior to the man overboard tests.

The system (Figure 1) for these measurements was a floating ring with two sensors (Ag-AgCl half cells) attached at opposite sides of the ring and located approximately 15-inches apart horizontally. A single wire from each sensor was routed to the instrumentation on shore. The ring was manually towed over the barrier along the east bank. This was accomplished using two ropes attached to the ring at opposing sides. The open circuit voltage between the sensors was recorded using a Tektronix TDS 5104 Digital Phospher Oscilloscope and an Agilent 34970 Digital Multiplexer. The sensors were electrically connected to the recording instrumentation with a Tektronix P5200 high voltage differential probe. (The differential probe was necessary with the oscilloscope to avoid grounding issues associated with single ended inputs.)

The GPS data was gathered by visual sighting from the bank with the range finder option on the GPA instrumentation.

Testing from the previous field mapping (Task 1) showed that the field strength is uniform across the canal. Therefore for this experiment it was necessary to measure only the field strength near the east bank.

Results

Data from one of the four runs across the barrier is plotted in FIGURE 2. Two locations of high field strength were identified and markers were placed on the fence at these locations.

These locations correspond exactly to the centers of the two electrode arrays and both peak at about 10 volts. Since the maximum fields appeared to be approximately equal, the center of the lower (southern) array was chosen for the location to conduct the man overboard tests because of its experimental efficiency.

Task 10 - Measure the vertical (head to toe) voltages that a person in the water over the barrier might be exposed to.

Experimental Approach

The measurement apparatus for these measurements consisted of a second tethered flotation ring that was fitted with two reference electrodes attached in a vertical orientation (Figure 3). One electrode was attached to the ring and hung just below the waterline. The second was suspended 6-feet directly below the upper electrode and was “anchored” with a concrete block (approximately 18 lb.). This electrode assembly was used to measure the voltage difference that a 6-foot tall human treading water (vertical orientation) would be likely to encounter. For this series of tests the towboat was located over the barrier about 50 feet from the eastern shore of the canal. Two nylon ropes were attached to the ring. The end of one rope was on the tow and the other was on the bank. The ropes were used to pull the ring between the bank and the tow. The GPS receiver was waterproofed and attached to the flotation ring. Location data was continually collected by the ARMS system during these runs and retrieved after completion of the suite of measurements. This experiment was repeated three times.

Results

Figure 4 and Figure 5 show two of the three runs as the ring was drawn both toward the bank and toward the towboat. This is the open-circuit voltage between the 6-foot spaced vertical electrodes. The variability of the peak values is attributed to the path of the float ring occasionally deviating from the region of the greatest electric field due to wind and water current. The distance of the ring from the center of the lower array is plotted on the figures. Note that the largest amplitudes occur when the ring is over the array (i.e., the ring distance from the center of array is zero). The highest field strength recorded was nearly 50 volts.

Discussion

Although the effects of an electric current inside the human body have been studied and documented and most dangers evaluated [3], the analysis of the effects of induced fish barrier currents on the human body is complicated because, in this instance, the body is totally immersed in water and that the voltage is a low duty cycle pulse which contains much less energy than a steady state dc voltage or an equivalent ac voltage.

The simplest model for determining electric current through the body is determined by dividing the total body resistance by the applied voltage. While the bodies' internal resistance remains the same whether in air or water, the skin resistance does not, and generally decreases with increasing moisture content. This model neglects external effects.

Task 11 - Measure the potential difference between the upper electrode (water surface) and the fence (system ground) while over the barrier.

Experimental Approach

The highest voltage to which a person in the water could be exposed would be the voltage between a location in the water directly over a barrier electrode array and earth ground of the system electronics.

This is an unlikely occurrence, since the earth ground is not available at the water surface. (Ground is about six-feet up a steep bank.) However, this measurement was performed as a worst case possibility, should a rescue attempt be made using a metal ladder, cable or chain.

Touch potential is a term used to describe the voltage difference between a person and another object.

This measurement simulated the touch potential between a person in the water and the system/earth ground. Measurements were made of the voltage difference between the upper ring electrode (Figure 3) and the barrier’s grounding system as the flotation ring was drawn toward the bank. For ease of measurement the fence surrounding the equipment building was used. These tests were conducted in a manner similar to Experiment 10. The towboat was located over the barrier about 50 feet from the eastern shore of the canal. Two nylon ropes were attached to opposite sides of the float ring. The end of one was run to the towboat and the other was taken to the bank. The ropes were used to pull the ring between the bank and the towboat. This experiment was repeated four times.

Results

FIGURE 6, Figure 7, Figure 8, and Figure 9 show the results of one of these measurements. As the ring approaches the bank, the open circuit voltage between the electrode and the fence is nearly 90 volts.

Recall that this is a worst case measurement. Because this voltage is between the electrode and system ground (fence), the actual voltage that a person could experience would be smaller. First, the person could not actually touch the fence, it is at least 6-feet above the water line, and second the fence has a very low resistance path to the system ground. It is not known how much lower that potential would be.

Task 12 - Measure the potential difference between the upper electrode (water surface) and the towboat while over the barrier.

Experimental Approach

To ascertain the touch potential experienced by a person in the water swimming to the towboat, measurements were made of the voltage difference between the upper ring electrode (Figure 3) and the towboat as the flotation ring was drawn toward the towboat. This potential was measured by measuring the voltage difference between the upper electrode and towboat. This measurement gives the touch potential between a person and the tow while over the barrier, simulating a person attempting to re-board a vessel from the water.

These tests were conducted in a manner similar to Experiments 10 and 11. The towboat was located over the barrier about 50 feet from the eastern bank of the canal. Two nylon ropes were attached to the float ring. The end of one was on the tow and the other was on the bank. The ropes were used to pull the ring between the towboat and the bank. This experiment was repeated twice.

Results

Figure 10 and Figure 11 show the results of these measurements. For this particular run, as the probe approaches the tow, the touch potential approaches about 30 volts.

Task 13 - Measure the touch potentials and touch currents of a person touching the canal wall over the barrier.

ERDC-CERL, at the request of the Chicago District Corps of Engineers, conducted specific touch potential and touch current measurements at the Chicago Ship and Sanitary Canal temporary fish barrier.

These measurements were made on 15 September 2005. Figure 12 illustrates experimental setup.

Touch potential is the open circuit voltage difference between a person and an object. Touch current is the current flowing through the person when in contact with an object. In this case, the experiment was designed to quantify the voltage and current induced by the fish barrier system on a system of sensors arranged to resemble a person in the water. The measurements for this study were conducted in the canal at the locations of the maximum electric field as determined by earlier CERL measurements (3 March 2005). The locations were over the barrier electrode arrays on the east wall of the canal and at the aluminum ladder at the boat launch. Additional analysis was performed to determine the source resistance seen by the sensor system. Once the source resistance is known, the current drawn by any load placed between the sensors on the experimental device can be computed.

Experimental Approach

An apparatus was constructed to simulate a human in the canal touching the canal wall. The “sled” is shown schematically in Figure 13 and in the photographs of Figure 14.

Three sensors (Ag-AgCl half cells) were mounted on a wooden structure. Sensors could be placed in either of two pairs of holes in the vertical part of the apparatus (high or low in Figure 13). These sensors represented the hands (left and right) of a person in the water contacting the canal wall. The locations of the two pairs of holes were intended to represent two contact heights on the wall as a person approached the wall, a lower one for when the person is still an arms distance away, and an upper one for when the person is at the wall. Another sensor was placed in the water approximately 2-4 feet from the canal wall (Figure 12). This sensor represented the human torso immersed in the water. It could be placed in two positions in the sled, a far and a near hole, the far position corresponding to the arms length distance from the wall and the near position corresponding to the at wall position (Figure 13). Water soaked sponges were placed over the “hands” to lower the electrode contact resistance with the wall. The moist sponge helped in two ways, the pliancy of the sponge provided more contact surface with the rough wall and the water lowered the resistance.

The voltage measurements (designated as V in Figure 12) were peak voltage measurements made with a Fluke 123 Scopemeter in the scope mode. The hand sensor was connected to the positive terminal of the meter and the torso sensor was connected to the negative / common terminal. Vs is the open circuit voltage (when Rx equals infinity) measurement. The touch currents and source resistance were computed from voltages measured across various resistors; 51, 120, 240 and 470 ohms.

Figure 15 is a representative waveform of a barrier pulse. The peak value of this waveform was read from the scope display and recorded. This 4-ms long pulse has a 5 Hz repetition rate (it repeats every 200 ms).

Refer to Figure 16 and Equations 1. The touch current, I, is computed using the measured voltage, Vx across the resistance Rx. I represents the current flowing through a body with internal resistance Rx. The computation of the touch current can be generalized for any body resistance, Rx, by computing the source resistance, Rs. Note that when Rx is equal to infinity (an open circuit) Vx is equal to Vsource.

( )sx source x x sourcex x source s sxsource xx xssource

RR

VI

R V

VR

R I

V R

RRIV

RIV

VRIV

(1)

The source resistance consists of the following individual system resistances:

1. Resistance of the path through the water from the barrier voltage source (electrodes) to the platform electrode (torso).

2. Contact resistance between the platform electrode and the water - this is very small. Half cells are low resistance devices when in contact with water or wet soil.

3. Contact resistance between the upper electrodes (hands) and the rock wall of the canal. Water soaked sponges were placed on these electrodes to reduce this value and simulate worst case conditions.

4. The return path to the voltage source through the rock, earth and water.

The largest components of the source resistance is likely to consist of the contact resistance to the canal wall (3) and the return path to the barrier drive system (4).

FIGURE 17 shows the sled and sensors while conducting measurements over the barrier electrode array.

Sponges were placed over the wall sensors and moistened to decrease surface contact resistance (touch resistance). Measurement locations were a compromise between high torso-to-fence potential measurements and wall roughness.

Results

Typical worst case results are reported in this summary. The largest voltages were measured directly above the barrier electrodes (corresponding with the maximum head-to-fence measurements of 3 March 2005) and at the boat launch.

The measured voltages and calculated source resistances values are listed in Table 2, Table 3, and Table 4.

The calculated short circuit current values (R x = 0) is the maximum current that can be supplied to the load by the system at the point the data is taken. The approximate value of current seen by a human or any other object in the barrier at this location can be determined by using the object’s resistance, R x, in the formulas of Equations 1.

Discussion

The values for short circuit current are relatively low and probably are not hazardous.

Boat Launch Measurements and Observations

Table 5, Table 6, and Table 7 present the tough potential and touch current measurements at the boat launch. Because an unusually high electric field was measured at the boat launch during the barrier field measurements for the “Man Overboard” investigation of 3 March 2005, further measurements at this location were warranted. The position of the sled at the ladder is shown in the pictures of FIGURE 18.

Table 5 lists the torso-to-wall touch potentials and currents. The aluminum ladder is in the raised or up position. The currents are twice as great as those measured over the arrays and are probably approaching dangerous values.

Measurements from torso to ladder with the aluminum ladder in the lowered or down position are listed in Table 6. When the ladder is down about 1 foot of it is in the water. These values are definitely dangerous.

Measurements from the steel gate to the aluminum ladder with the ladder in the lowered or down position are listed in Table 7. When the ladder is down about 1 foot of it is in the water. These values are large enough to be extremely hazardous.

FIGURE 2 is the field data taken on 3 March 2005 shown as a function of time. These measurements were taken with a sensing system consisting of two half cells mounted about 15” apart on outer circumference a life preserver ring. The data represents the voltage difference between the two electrodes as the sensor system was towed across the barrier. The route traveled by the sensor was along the east bank of the canal and extended from a point off the southwest corner of the fence surrounding the barrier array system to just north of the swinging gate (south of the boat launch location). The intent of these measurements was taken to determine and document the locations of maximum fields for the “Man Overboard” study. Note the low field values at the south west corner location (left side of plot) and the relatively high field values at the gate location (right side of plot. Both of these locations are approximately the same distance from the nearest electrode array. One would expect the fields to decay similarly on both sides of the barrier. If there were no interfering factors, the field magnitudes should drop off approximately equally on the north side and the south side of the barrier. It is likely that the field perturbation on the north (right) side is caused by an excess of current drawn from the barrier to an electrical ground associated with the boat launch (metal - either part of the hoist structure and/or reinforcement steel in the concrete base).

The effects observed with the ladder in the water associated with the touch potential measurements reinforce this conclusion.

Undesirable effects from the hoist at its present location include: shock hazard, distortion of the fish barrier fields and increased power loss associated with fish barrier operation.

For safety purposes, it is recommended that the ladder be replaced with one constructed of non-electrically conductive material (i.e. fiberglass). It is also recommended that no grounded metallic structures be installed in the barrier region where they can be reached from anyone in the water or from metal boats in the water.

CONCLUSIONS

A detailed field mapping of the barrier electrical field at the surface of the water was conducted. The highest voltage zones were identified and the peak voltage zone of the south set of electrodes was used for the “man overboard” measurements. These included voltages across a 6-foot vertical dimension with a voltage probe in the barrier region. This resulted in a value of nearly 50 volts being observed in the highest field strength region of the barrier. (It should be noted that all voltage values are pulse peak values and that the duty cycle is 0.02. The voltage is zero for 98% of the time.)

Voltage values representative of the electrical potential that would be produced across a simulated 6-foot human vertically immersed in the barrier region were measured. Nearly 50 volts open circuit was observed in the highest field strength region of the barrier. As the simulated person (representation) in the water was dawn toward the bank, the touch potential between the representation and the fence was nearly 90 volts, while as a representation approached the tow, the touch potential approached about 30 volts.

Analyzes of the effects of these voltages on the human body are ongoing. These analyzes are complicated because, in this instance, the body is totally immersed in water and the voltage is pulsed. Current safety standards for induced currents in humans assume the body is in air and either dc or ac voltages are applied.

RECOMMENDATIONS

For safety purposes, it is recommended that the ladder be replaced with one constructed of non-electrically conductive material (i.e. fiberglass). It is also recommended that no grounded metallic structures be installed in the barrier region where they can be reached from anyone in the water or from metal boats in the water.

REFERENCES

Hock, Vincent, et al, Engineering Analysis of the Chicago Sanitary and Ship Canal Electric Fish Barrier:

Electrical Effects on Barges and Tow Vessels, ERDC/CERL Letter Report LR-05-2, May 2005.

Rasmussen, J.L. 2001, The Cal-Sag and Chicago Sanitary and Ship Canal: A Perspective on the Spread and Control of Selected Aquatic Nuisance Fish Species, U.S. Fish and Wildlife Service, 4469 - 48th Avenue Court, Rock Island, IL 61201, 26 pp.

Smith; David V., Fish repelling apparatus using a plurality of series connected pulse generators to produce an optimized electric field, United States Patent 4,750,451 June 14, 1988.

ACKNOWLEDEMENTS

Chicago District Corps of Engineers Charles Shea, Project Manager Whaler (23 November 2005) Sinko Higgins Whaler (5 January 2005) Melvin McLaurin

Illinois Marine Towing, Lemont Illinois M/V Albert C towboat (6 – 7 January 2005) Capt Bill Russell Pilot Richard Robertson Crew David Jones

Garvey Marine Towing, Lemont Illinois Joe Avery towboat (3 March 2005) Captain James Janes Crew Manuel Santos and Matt Cupples

FIGURES

FIGURE 1. Field mapping system consisting of reference electrodes mounted on floating ring to map the electric field in detail directly over the barrier.

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FIGURE 2. The voltage difference between sensors 15-inches apart as they are drawn across the barrier (Agilent Data).

FIGURE 3. Diagram of electrode configuration ring for the “man overboard” experiments.

Voltage Difference between Vertical Half-Cells ring drawn from tow toward bank

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FIGURE 4. The voltage difference between the upper and lower reference electrodes as they are drawn from the tow toward the eastern bank of the canal.

Voltage Difference between Upper Half-Cell and Towboat ring drawn from bank toward towboat

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FIGURE 5. The voltage difference between the upper and lower reference electrodes as they are drawn from the bank toward the tow.

Voltage Difference between Upper Half-Cell and Fence

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FIGURE 6. Voltage difference between ring upper electrode and fence.

ring drawn from tow toward bank

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FIGURE 7. Voltage difference between ring upper electrode and fence.

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FIGURE 8. Voltage difference between ring upper electrode and fence.

ring drawn from tow toward bank

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FIGURE 9. Voltage difference between ring upper electrode and fence.

ring drawn from bank toward towboat

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FIGURE 10. Voltage difference between flotation ring upper electrode and towboat.

ring drawn from bank toward towboat

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FIGURE 11. Voltage difference between flotation ring upper electrode and towboat.

FIGURE 12. Touch potential and touch current measurements at the canal wall.

FIGURE 13. Diagram of the “sled” used to position the half-cell sensors for touch potential and touch current measurements.

FIGURE 14. Photographs showing the sensors mounted on the under and back sides of the sled.

FIGURE 15. Single 4 ms pulse waveform.

FIGURE 16. System electrical circuit diagram.

FIGURE 17. Photograph showing sled and electrodes in contact with canal wall for array measurements.

FIGURE 18. Photograph showing sled and electrodes in contact with canal wall for ladder measurements.

TABLES

TABLE 1. Environmental conditions during field testing.

Date Mean

Temperature (°F)

Maximum Temperature

(°F)

Average Humidity

Precipitation (in)

Wind Speed (mph)

Water Conductivity (ppm TDS) [µS/cm])

5 January 2005 30 32 92 .03 Snow 20 1,220 (780) 6 January 2005 22 30 89 .03 Snow 12 1,220 (780) 7 January 2005 19 28 89 .00 6 1,220 (780) 2 March 2005 20 28 65 .00 7 1,220 (780) 3 March 2005 26 37 67 .00 4 1,220 (780)

15 September 2005 63 69 45 .00 6 524 (335)

TABLE 2. Measurement at upper array (150 volts torso-to-fence).

Rload Voltage Current Rsource Ishort circuit (ohms) (volts) (milliamps) (ohms) (milliamps) Open 25.00 470 1.50 3.19 7,363 270 0.80 2.96 8,168 120 0.40 3.33 7,380 51 0.15 2.94 8,449

Average Rsource 7,840 3.20

TABLE 3. Measurement between arrays.

(ohms) (volts) (milliamps) (ohms) (milliamps) Open 25.00 470 0.60 1.34 19,113 270 0.30 1.17 22,230 120 0.15 1.31 19,880 51 Noise

Average Rsource 20,408 1.20

TABLE 4. Measurement at lower array (100 volts torso-to-fence).

(ohms) (volts) (milliamps) (ohms) (milliamps) Open 10.00 470 0.50 1.06 8,930 270 0.30 1.11 8,730 120 0.10 0.83 11,880 51 0.05 0.98 10,149

Average Rsource 9,922 1.00

TABLE 5. Canal wall touch measurements at aluminum ladder, ladder up (180 volts torso-to-fence).

(ohms) (volts) (milliamps) (ohms) (milliamps) Open 40.00 470 3.00 6.38 5,797 270 2.00 7.41 5,130 120 0.80 6.67 5,880 51 0.28 5.49 7,235

Average Rsource 6,010 6.70

TABLE 6. Torso to ladder measurements with the ladder down and bottom 1 foot in water.

(ohms) (volts) (milliamps) (ohms) (milliamps) Open 10.00 470 7.00 14.89 201 270 5.50 20.37 221 120 4.00 33.33 180 51 2.00 39.22 204

Average Rsource 202 49.50

TABLE 7. Gate to ladder measurements with the ladder down and bottom 1 foot in water.

(ohms) (volts) (milliamps) (ohms) (milliamps) Open 20.00 470 20.00 42.55 0 270 20.00 74.07 0 120 20.00 166.67 0 51 N/A

Average Rsource 0 ---

ANNEX 1 - INSTRUMENTATION

Various models of multimeters, digital storage oscilloscopes and data acquisition units were used to record the electrical measurements.

1) Agilent 34970A Multiplexing Data Acquisition System with up to 20 analog to digital DC voltage input channels.

2) Tektronix 5104 Digital Phosphor Oscilloscope

3) Fluke 105B Digital Scopemeter with 100 MHz Bandwidth

4) Fluke Model 865 Graphical Volt/Ohm meter

5) Fluke Model 123 Scopemeter

6) Hewlett Packard E2373A Volt/Ohm meter

7) Garmin N-17 GPS receivers with TDS Recon Hand-held computers

8) ARMS enhanced ike 300

The Agilent Data Acquisition System was used throughout the experiments to continuously measure and record the voltage differentials. The Agilent was chosen because of its multiple independent channel capabilities (up to six for these experiments) and its virtually limitless storage. (When used in conjunction with a personal computer (PC) data is immediately transferred to the PC for storage.) The disadvantage of using the Agilent was not being able to synchronize measurements with the fish barrier pulses. Since the instrument was free running there was no guarantee that every pulse or even that a complete pulse was captured. This is why the magnitudes of the peaks do not change monotonically.

Fortunately because of the high sample rate and long scan times, complete pulses were frequently obtained. When interpreting the Agilent data, the envelope (overall trend of the peak values) of the waveform should be considered.

The Flukes and the Tektronix were used as backups in case of failure of the Agilent and as a secondary confirmation of the measurement. The Agilent, Fluke 105B and Tektronix are direct reading and recording systems. The Fluke Model 865 is a direct reading and average recording instrument. Since the Fluke Model 865 collects and averages the measurements over a 1 second time period, it would average the single 4 ms “pulse peak” values with the “off” voltage values, resulting in an under recording of the peak values. Because the barrier pulses have a 2% duty cycle, the average value of the Fluke 865 must be scaled by factor of 50 (1/.02) to convert to peak value.

Throughout the project all moving electrical measurements were collected and referenced with geospatial coordinates to aid in mapping and determining the extent and nature of the electrical field. Two Global Positioning Systems (GPS) were used to record the data. These were typically placed on the bow and stern of the “Boston Whaler” as well as the barge configuration. GPS location was recorded at 0.2-ft to 20-ft intervals, depending on the measurement system, as the reference cell array passed over the electrodes of the electric fish barrier.

The GPS recorded its position every two or three seconds. Because the data acquisition instruments recorded voltages at millisecond intervals, in order to georeference the electrical data a linear interpolation of the GPS data was required. The electrical measurements were georeferenced by using the barrier array as a marker. Because the maximum electrical measurement values occur over the barrier, the time values of the measurement files were georeferenced by synchronizing the time of the maximum values with the time of the location of the barrier arrays in the GPS files.

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