IIA_Safety_Testing_Summary_1Dec08.pdf

Summary of Safety Studies Completed at Chicago Sanitary and Ship Canal Dispersal Barrier IIA

Prepared By:

U.S. Army Corps of Engineers, Chicago District 111 North Canal Street, Chicago, Illinois 60606

December 1, 2008

Summary of Safety Studies Completed at Chicago Sanitary and Ship Canal

Dispersal Barrier IIA

INTRODUCTION

The US Army Corps of Engineers (USACE) has maintained a continuous barrier to aquatic nuisance species in the Chicago Sanitary and Ship Canal (CSSC) since the installation of the

Demonstration Electric Dispersal Barrier (Barrier I) in 2002. Construction of a permanent barrier (Barrier II) was initiated in 2004. Barrier II is being constructed in two halves, known as

Barrier IIA and Barrier IIB. Each half can be operated independently, but the ultimate goal is to operate both at the same time. Barrier IIA has been constructed and safety studies completed at it are the subject of this report. Design revisions for Barrier IIB are currently underway with final construction planned to begin in the summer of 2009. Figure 1 shows the relative locations of

Barrier I and Barrier II. Figure 2 shows Barrier IIA and nearby features.

Barrier I operates with a maximum in-water electric field strength of 1 volt/inch (V/in). This voltage level has been shown to be effective in repelling large fish. However, research completed after Barrier I was constructed indicates that smaller fish that are only several inches long may require in-water electric field strengths of up to 3 to 4 V/in to be repelled by an electric barrier. Therefore, Barrier II is designed to operate at maximum in-water field strengths up to 4

V/in. The majority of the tests completed to date for Barrier IIA have been done with IIA operating at the 1 V/in level. Additional testing at higher voltages will be completed in the future.

There are two safety concerns related to operation of the barriers: the potential of the electrified water to generate sparking within or between barges or other vessels and the potential risks that the electrified water poses to people who contact it. USACE and the U.S. Coast Guard have coordinated to complete a series of tests to address these concerns.

This document summarizes the testing and results of all safety studies relevant to operation of

Barrier IIA at a maximum field strength of 1 V/in. More detailed information on the studies is available in the previously published reports cited in the References section of this document.

BARRIER I TESTING

In January and March of 2005 testing was completed with various barge configurations to determine the potential for sparking within and between vessels due to the operation of Barrier I

(Reference 1). The results indicated that sparking could occur within barge tows that are connected with soft lines, between unconnected barges, or between barges and metal structures on land. Based on this testing, a Regulated Navigation Area (RNA) was established in the vicinity of the barriers (Ref. 2). Barrier IIA was under construction at this time and the extent of the RNA was defined to include the location of Barrier II as well as Barrier I. Testing was also completed in to evaluate human health risks associated with contacting the electrified water (Ref.

3).

Results of the Barrier I tests that are also relevant to Barrier IIA are discussed further below.

There are additional Barrier I tests that are not discussed in this document, but are included in

References 1 and 3.

REGULATED NAVIGATION AREA

On January 26, 2005 a RNA on the CSSC in the vicinity of the barriers was published as a temporary final rule. The RNA became permanent on January 1, 2006 (Ref. 2). The RNA is defined as all waters of the CSSC between the north side of the Romeo Road Bridge (Mile

Marker 296.1) and the south side of the aerial pipeline (Mile Marker 296.7). This area is shown in Figure 3. The regulations for the RNA are:

• All vessels are prohibited from loitering in the RNA.

• Vessels may enter the RNA for the sole purpose of transiting to the other side, and must maintain headway throughout the transit.

• All personnel on open decks must wear a Coast Guard approved Type I personal flotation device while in the RNA.

• Vessels may not moor or lay up on the right or left descending banks of the RNA.

• Towboats may not make or break tows in the RNA.

• Vessels may not pass (meet or overtake) in the RNA and must make a SECURITE call when approaching the barrier to announce intentions and work out passing arrangements on either side.

• Commercial tows transiting the RNA must be made up with wire rope to insure electrical connectivity between all segments of the tow.

The safety testing described below confirms that safety risks will be greatly reduced if transiting vessels adhere to the requirements of the RNA.

BARRIER IIA TESTING

This section provides an overview and timeline of the testing completed at Barrier IIA. The results of the tests and their implications for operation of Barrier IIA are discussed in more detail in the following sections.

Construction of Barrier IIA was completed in the spring of 2006. Testing was then begun to define the extent and magnitude of the electric field generated by Barrier IIA, evaluate the potential of Barrier IIA to create sparking between metal hulls, and evaluate the potential physiologic effects a person in the electrified water would experience. Initial measurements in

April 2006 of the strength and extent of the electric field generated by Barrier IIA showed that the field extended beyond the southern end of the RNA. This generated concerns that the field would negatively impact operations in a fleeting area located approximately 150 feet south of the

RNA. Tests were completed in which a barge tow was bumped into a barge moored in the fleeting area (Figure 4). Sparking did occur between the contacting barges. Therefore, physical and operational changes were evaluated to reduce the electric field beyond the RNA (Ref. 4).

It was determined that placing electrically conductive material in the canal between Barrier IIA and the southern end of the RNA would reduce the electric field extent. In May 2006 a grounding system consisting of interconnected steel blast mats was constructed on the canal bottom between Barrier IIA and the Romeo Road Bridge. Figure 5 is a photograph showing a blast mat. With the blast mat system in place, additional testing was completed in May and June

2006. This additional testing involved measuring the extent and strength of the electric field while varying barrier operating parameters and the way the blast mats were grounded. These measurements identified several operating configurations that were most successful at reducing the spread of the electric field beyond the RNA (Ref. 4).

In February 2007 additional tests were completed to determine if the grounding system had reduced sparking potential in the fleeting area and, if so, to identify an optimal operational configuration for Barrier IIA. The "bumping" test shown in Figure 4 was repeated for several operating configurations and no sparking was observed. Other tests were done that simulated the making up of a tow in the fleeting area. No sparking attributable to operation of Barrier IIA was observed during the simulated fleeting operations (Ref. 5).

After a review of the February 2007 test results, the operating configuration shown in Figure 6, identified as the "I Normal" configuration during testing in 2006 and 2007, was determined to be the optimal configuration for operation of Barrier IIA (Ref. 5). Operating IIA at 1 V/in in this configuration did not produce any sparking in the fleeting area tests of February 2007. Testing was also done for this configuration at 2 V/in, one of the limited times when testing has been done above 1 V/in, and no sparking occurred for any of the tests at the 2 V/in level either.

System constraints made it impossible to operate IIA at levels higher than 2 V/in at that time.

The February 2007 testing showed that operations outside the RNA would not have an increased risk of sparking with Barrier IIA operated at up to 2 V/in. However, there were still concerns about longer tows that could be partially within the RNA and partially outside of the RNA during transit over Barrier IIA. Specifically, would sparking occur if a tow long enough to simultaneously span the active electrodes of Barrier IIA and the fleeting area south of the RNA collided with moored barges in the fleeting area? It was also still necessary to examine the electrical effects on a long tow transiting the RNA when both Barrier IIA and Barrier I are operational. The additional concern would be that exposure to two different electric fields at opposite ends of the tow could lead to increased voltage potential differences within the tow.

Additional testing to evaluate these long tow scenarios was completed in April 2008 (Ref. 6).

USACE contracted with the U.S. Navy Experimental Diving Unit (NEDU) to analyze the data obtained from Barrier IIA field strength data collected in April 2006 and evaluate the potential physiologic effects that are likely to occur if a person were immersed near the energized Barrier

IIA. NEDU published the results of their evaluation in June 2008 (Ref. 7).

EXTENDED TRIAL OPERATION OF BARRIER IIA

Barrier IIA was continuously operated at a maximum in-water field strength of 1 V/in for approximately seven weeks from 3 September2008 to 24 October 2008. This was done to insure continuous protection against invasive species while maintenance was completed at Barrier I. It also served as an extended trial run of IIA. Previously all startup and safety testing at Barrier IIA had been done with the barrier turned on for only a few hours at a time and with the canal closed to through traffic while the barrier was in operation. During the trial run, traffic was allowed to pass over Barrier IIA. A bow boat assist was provided to all tows transiting the RNA that included one or more red flag barges. No safety incidents or safety concerns were reported to

USACE or the Coast Guard during this operation of Barrier IIA.

EVALUATION OF SPARKING POTENTIAL

Studies have been done to evaluate whether the electrified water created by Barrier IIA increases the possibility of sparking occuring:

• Within a single vessel

• When metal objects contact the deck or on-board structures/equipment

• Between the engine drive shaft and engine block

• Between a vessel and a grounded on-land object

• Between the components of a barge tow

• When one barrier is operating

• When Barrier I and Barrier IIA are both operating

• Between barges during fleeting operations outside the RNA

• Between two unconnected vessels or tows

• When both are within the RNA

• When one is partially within the RNA and one is not

All Barrier I testing was completed with the barrier operating at a maximum in-water field strength of 1 V/in. Unless otherwise noted, all Barrier IIA testing was completed with the barrier operating in the configuration shown in Figure 6 and at a maximum in-water field strength of 1

V/in. The Coast Guard closed the canal to through-traffic during all testing. All barges used in testing were fully loaded to achieve maximum hull exposure underwater. For tests that involved bumping barges together to look for sparking, background tests were done in which the test was completed with the barrier turned off. No sparking was observed for any background tests.

Sparking can occur when there is a large electrical potential difference between objects. So to minimize the chance of sparking, vessel hulls should be at nearly equal potentials.

USACE is confident that the results of the sparking potential tests are independent of weather conditions. The measurements collected indicate that the voltage potential differences generated between metal objects in the vicinity of the barrier are not great enough to initiate the breakdown of air due to a high voltage. Therefore, arcing does not occur between two objects that are close, but not touching. The sparking observed in the sparking potential tests only occurred after two barges touched and then separated. This type of sparking is analogous to striking an arc in electric welding or the contacts of an electrical switch opening. Two metal objects at different electric potentials are brought together. The differing potentials result in an electric current flow between the objects. When the objects are separated the current continues to flow, ionizing and heating the air between the objects. When the distance becomes too great for the electric potential to maintain the arc, the current is limited by the circuit resistance or power supply, or the electric potential is removed, current flow stops. In the case of barges, localized heating results in melting of steel and tiny metal particles are emitted from the barge. This is the observed sparking. This sparking is independent of the weather conditions because it is initiated by the two objects touching and separating, and the process of ionizing air via this mechanism is independent of temperature and humidity. The heat and temperature generated by this sparking process is much greater than the temperatures on the canal and will rapidly evaporate any moisture in the air.

Sparking Potential Within a Single Vessel

In January 2005 experiments were completed to determine if a barrier electric field would lead to increased possibility of sparking on board a vessel. A towboat was positioned over Barrier I and

USACE and the Coast Guard moved throughout the boat touching a handheld metal rod to metal equipment and fixtures. No sparking was observed. This confirmed that the electricity is distributed only on the outside of the boat hull as predicted by electrical law (the Faraday Cage

Effect).

In March 2005 an additional experiment was done to measure electrical continuity between the engine drive shaft and engine block of a typical towboat. While a towboat was stationary over

Barrier I, the electrical resistance between the engine drive shaft and engine block was measured.

The electrical resistance between the drive shaft and block was 0.2 ohm. This indicated that the engine block, transmission, and drive shaft are electrically continuous. Therefore, sparking between the drive shaft and engine block is unlikely.

These experiments did not need to be repeated at Barrier IIA because the results will hold true for any electrical field in the canal water. The results demonstrate that the electrical field generated by Barrier IIA will not lead to an increased risk of sparking on board a vessel transiting the barrier.

Sparking Potential Between a Vessel and a Grounded On-Land Object

Testing was completed in January 2005 to measure the voltage difference between a vessel above Barrier I and the earth ground adjacent to the canal. One test lead was connected to a barge on a tow transiting over the barrier and a second test lead was connected to the grounded fence around the Barrier I complex. The tow configuration used is shown in Figure 7; voltage V3 was measured. The peak voltage difference between the barge and earth ground exceeded 80 volts. Thus, if a vessel or tow were to attempt to moor to a grounded conductive structure on land, such as a metallic bollard, cleat, or fence, using wire rope there is a significant risk of sparking.

This test did not need to be repeated at Barrier IIA because the result will be the similar for any electric field in the water of the same strength (1 V/in). The potential for sparking during mooring will be eliminated if the no mooring requirement of the RNA is obeyed. Also, USACE has removed all mooring structures, including cleats, bollards, and capstans, that were within the

RNA due to previous land uses.

Sparking Potential Between the Components of a Barge Tow

When One Barrier Is Operating

In January 2005 tests were done to measure the voltage potential difference between the components of a tow with two barges in series while it passes over Barrier I. Separate tests were done with the barges connected by soft lines and wire rope. The instrumented barge configuration used for both is shown in Figure 7; voltages V1 and V2 were measured.

With the barges connected by soft lines, the maximum voltage difference between the two barges approached 250 volts as the tow moved over the barrier. This level of voltage potential difference creates a significant risk of sparking. No sparking was observed during transit.

However, while making a tow with soft lines for the experiments, sparking between barges was observed. One barge was moored slightly downstream of Barrier I while the other barge and towboat were over the barrier. Sparking was created when a metal tool used for connecting the barges was used to bridge the barges. As the tool was scraped across one of the barge surfaces, sparks were created. Sparks were also observed when the hull corners of the roped barges made contact. This confirms that sparking is a definite possibility between barges connected with soft lines.

With the barges connected by wire rope, the maximum voltage difference between the two barges was less than 0.1 volt. The maximum voltage difference between the towboat and Barge

2 , a worst case measurement for potential difference within the tow, was less than 0.15 volt.

These low potential differences indicate sparking is extremely unlikely within a tow where the barges are in series and connected by wire rope. No sparking was observed during testing. Note that the maximum voltage potential difference for the barges connected with wire rope was more than three orders of magnitude less than the maximum voltage potential difference measured for the barges connected with soft lines.

In March 2005 similar testing was done at Barrier I for a tow where the barges were in parallel.

This configuration is shown in Figure 8; voltages V1 and V2 were measured. These tests were only done with wire rope connections. The maximum observed voltage potential difference was approximately 3 volts. No sparking was observed. Although the maximum potential difference was higher than for the series configuration with wire rope, it is still low enough to make sparking unlikely. Also note that the maximum potential difference is still nearly two orders of magnitude less than the maximum potential difference measured for the series configuration with soft lines.

Similar tests to quantify maximum voltage potential differences over Barrier IIA have not been completed because the results from Barrier I will also apply at Barrier IIA. However, during other tests done over Barrier IIA sparking was generated by dragging a wire rope connected to a towboat over an adjacent barge that was connected to the towboat by soft lines. No sparking was observed between components of a tow at Barrier IIA when the components were connected by wire rope.

These tests show that sparking within a tow is extremely unlikely if each component of the tow remains electrically connected to all neighboring components of the tow. Electrical connectivity could occur in a tow connected by soft lines if the metal hulls remain in continuous contact with one another. However, if the soft lines are loose enough to allow the hulls to separate and come back together again, sparking between the hulls is a significant possibility. Connecting a tow with wire rope is much safer as it insures continuous electrical connectivity within the tow.

Thus, the RNA requirement that tows be made up with wire rope makes sparking within a tow extremely unlikely.

These tests also demonstrate the importance of the RNA requirement prohibiting the making or breaking of tows within the RNA. Obviously during making or breaking of tows there are times when the tow components are not electrically connected to one another and, therefore, the risk of sparking could be high.

When Barrier I and Barrier IIA are both operating

Testing was completed in April 2008 to determine if operation of both Barrier I and Barrier IIA at the same time increased the potential for sparking to occur between the components of a tow.

The additional concern when a second barrier is operating would be that exposure to two different electric fields at opposite ends of the tow could lead to increased voltage potential differences within the tow. The longer the tow, the more likely it is to be exposed to electricity from both barriers simultaneously. Therefore, the tests were done for the longest tow that is used on this segment of the CSSC, a tow five barges long. The tow configuration used in testing is shown in Figure 9. All parts of the tow were made up with wire rope.

Four test runs were completed alternating between upstream and downstream travel. During each test run the entire tow traveled from south of the Romeo Road Bridge to north of the aerial pipeline or vice versa. After the first run, which was upstream, a bow boat was added to the front barge of the tow. The total length of the tow without the bow boat was 1,083 feet. The total length of the tow with the bow boat was 1,150 feet.

The maximum voltage potential differences between the barges ranged from 3.5 to 5 volts. The maximum voltage potential difference between the towboat and the barge next to it was approximately 9 volts. The maximum potential difference between towboat and barge is greater than between barges because the towboat has rubber bumpers that the barge is pulled up against.

This makes the wire ropes the sole electrical connection between the two. In addition to the wire ropes, there is metal-to-metal hull contact between adjacent barges.

The maximum voltage potential difference between barges in the long tow test is similar to the maximum voltage potential difference for the parallel barge configuration testing at Barrier I.

The maximum voltage potential difference between the towboat and adjacent barge is higher than for the parallel barge configuration testing at Barrier I, but still on the same order of magnitude. The maximum potential differences for the long tow with both barriers operating are still far below the maximum potential differences for a tow made up with soft lines transiting

Barrier I. Therefore, for a long tow in transit with both barriers operating, sparking is still unlikely if the tow made up with wire rope.

Sparking Potential Between Barges During Fleeting Operations Outside the RNA

As discussed earlier, when Barrier IIA was first activated and tested it was discovered that the electric field spread beyond the RNA at a level that led to sparking in the fleeting area south of the Romeo Road Bridge. After the blast mat grounding system was constructed and optimized, testing was completed in February 2007 to confirm that operation of Barrier IIA would not lead to increased sparking potential in the fleeting area.

Four barge/tow scenarios were evaluated for sparking potential testing in the fleeting area:

connecting barges in series (Figure 10), connecting barges in parallel (Figure 11), inserting a single barge into a tow (Figure 12), and an angled tow configuration (Figure 4). The first three scenarios simulated various ways of making a tow. The angled tow configuration simulated a potential collision where a down-bound tow loses control and moves into the fleeting area. The angled tow test is the test for which sparking was observed in April 2006, which led to the need for the grounding system.

Barrier IIA was operated in three different configurations for each of the four barge/tow scenarios. The results discussed in this section are for the configuration shown in Figure 6, which is the configuration which USACE plans to use for future operation. The other configurations were determined to be less desirable and will not be used again.

For each barge/tow scenario, the moving tow was placed in close proximity to the moored barge that it was to contact. The tow then slowly made contact with the moored barge and slowly moved away. These contacts are called "bumps" in this report. At least two bumps were completed for each scenario. In addition, bumps were completed for each barge/tow scenario with the barrier off to obtain a "background" comparison. During the making and breaking of contact, Corps, Coast Guard, and tow company personnel were positioned to look for sparking between barges. Voltage potential differences between all barges were measured throughout this process.

For each scenario, the sparking potential tests were first done with the barrier operating at a maximum in-water voltage gradient of approximately 1 volt/inch. If no sparking was observed, an attempt was made to increase the barrier operating voltage to attempt to determine the level at which sparking began. However, due to high water conductivity and barrier equipment limitations, it wasn’t possible on the testing days to operate Barrier IIA at levels higher than approximately 2 volts/inch.

No sparking was observed for any of the bumps with Barrier IIA operating in the configuration shown in Figure 6 at 1 V/in or 2 V/in. In particular, the lack of sparking in the angled tow tests, compared to the fact that sparking had occurred in that test earlier, shows that the blast mat grounding system is effective in reducing the electric field outside the RNA. The absence of sparking while making tows shows that Barrier IIA can be operated at up to 2 V/in without creating safety concerns for operations to make or break tows in the fleeting area.

Sparking Potential Between Two Unconnected Vessels or Tows

When Both are Within the RNA

In January 2005 tests were also done to determine the possibility of sparking between unconnected barges moving in the vicinity of one another over Barrier I. In the first test one barge was moored approximately 40 feet downstream from Barrier I. Electrical potential measurements were made between the fixed barge and a moving barge while a tow passed over the barrier. This testing configuration is shown in Figure 13. The maximum measured voltage potential difference was over 300 volts. As discussed earlier, this potential difference is not high enough to lead to sparking if the barges do not contact one another. However, if elements from separate tows were to scrape against one another in the barrier region, the possibility of sparking is substantial.

In the second test of unconnected barges in January 2005, one barge was moored approximately

40 feet downstream from Barrier I and a tow was maneuvered toward the moored barges until head-to-head contact was made. This testing configuration is shown in Figure 14. The voltage potential difference between the two barges decreased with decreasing distance, but not to zero.

Instead, as the distance decreased to the point where they were virtually touching, the potential difference remained in excess of 40 volts. This represents a worst-case condition that almost assures sparking. Indeed, sparking was clearly visible between the barges in the field tests.

Similar tests to quantify maximum voltage potential differences over Barrier IIA have not been completed because it is obvious that collisions or allisions over Barrier IIA would also have a high risk of generating sparking. These tests clearly show the importance of the RNA requirements prohibiting passing and making or breaking of tows within the RNA.

When One is Partially Within the RNA and One is Not

Clearly the potential for sparking is significant when unconnected tows or vessels make contact over or in close proximity to either of the barriers. Tows which are long enough to have one end over a barrier while the other end is outside the RNA create another concern. If the tow is configured with wire rope as required, the electrical connectivity will lead to an electric charge on the barge at the head of the tow, even though that barge is no longer be within the RNA.

Then there may be some risk of sparking if the head of the tow collides or allides with another vessel or tow, such as barges in the fleeting area south of Romeo Road Bridge or a tow waiting for its turn to pass through the RNA.

This risk could be eliminated by redefining the RNA. An ideal RNA would be long enough that the longest tow possible in the area would still be entirely within the RNA until no part of it was over a barrier. However, this is not practically possible because of the location of fleeting areas that predate the barrier system.

Sparking potential for a tow partially within the RNA is the most difficult of the sparking potential scenarios to define. There are an infinite number of possibilities for collisions or allisions, depending on the size and position of the tow partially within the RNA, the size and position of the vessel or tow outside the RNA, and the point of contact and angle of contact between them. It is also difficult to define the worst-case scenarios that would lead to the greatest voltage potentials at the head of the tow.

In April 2008 USACE tested a scenario that has a high likelihood of occurring: a downbound tow colliding with the northeast corner of a barge moored at the northern end of the fleeting area.

This scenario is illustrated in Figure15. The position of the moving tow was varied to see if the location between the sidewalls of the canal made a difference in the results. Thirteen test runs were completed with varying positions of the moving tow. During each test run, the barges were bumped together a minimum of three times. Eleven test runs were done with the entire tow made up with wire rope. Two test runs were completed with the towboat connected to the barge by soft lines, while the two barges were still connected with wire rope.

Sparking was not observed during any of the test runs when the tow was made up entirely with wire rope. The tests runs in which the towboat was connected to the adjacent barge with soft lines did produce sparking. This result is likely because the tow was no longer a continuous electrical conductor; there was now an electrical break between the towboat and second barge, and this break was located between the two south electrode arrays. When the towboat and second barge were electrically connected, together they spanned both of the south electrode arrays, providing a low resistance and direct path for the current to flow between the two arrays.

When the towboat was isolated from the second barge, there was no longer this low resistance electrical path between the arrays, and the electrical current preferred to travel through the tow barges to the fleeting area, providing the extra current needed to initiate sparking. This again shows that the use of wire rope reduces the risk of sparking

USACE and the Coast Guard previously discussed constructing a protection cell or cells at the northern end of the fleeting area to eliminate the possibility of barge-to-barge collisions such as those tested in April 2008. However, representatives of the navigation industry stated that a protection cell system would make it more difficult to navigate through the area while not entirely solving the problem because collisions or allisions could still occur farther south in the fleeting area. A protection system that entirely encloses the fleeting area, rather than just protecting the northern end, would be impractical as it would severely restrict the ability to make or break tows in the area. Therefore, planning for a protection cell system was discontinued.

EVALUATION OF RISKS POSED BY HUMAN IMMERSION IN THE ELECTRIFIED

WATER

USACE collected data on in-water electric field strengths and wall contact potentials at Barrier

IIA in April 2006. USACE then contracted NEDU to analyze the data to determine the potential physiological effects likely to occur if a person were immersed in the CSSC in the vicinity of an energized barrier. The most likely sources of such an immersion would be an individual falling into the water from a barge, towboat, or recreational boat or from the land at the canal’s edge.

The discussion below on risk posed by immersion is taken from NEDU’s June 2008 report (Ref.

7).

Risk Posed by Immersion

The analysis of the effect of the Barrier IIA electric field on humans immersed in the CSSC is complex. While many studies of the effects of electrical shocks to animals and humans are published, almost all investigate bodies in air, not immersed in water, and with single current burst shocks from alternating current. The CSSC dispersal barriers generate rapid pulses of direct current. In addition, the situation at the barrier includes many continuously changing environmental and physiological variables.

NEDU’s approach was to identify and characterize the worst-case conditions and to apply several different analytical techniques to estimate body currents. Several safety standards and codes then were extrapolated to evaluate the potential harmful effects of these body currents.

The goal was to bound the problem and to estimate the order of magnitude of risk for serious physiological effects

Key information on the significant cumulative effect of repetitive short-duration DC shocks on the heart - information not available until the May 2007 revision of the IEC Technical

Specification on the effect of electric current on humans and livestock - greatly increased the expected probability of ventricular fibrillation (cessation of heartbeat). Barrier IIA was designed to operate at 4 or 5 pulses per second, with each pulse 4 milliseconds long. The IEC Technical

Specification (Ref. 8) reports that pulses of current that are separated by less than the period of a normal heartbeat can have cumulative effects that lead to ventricular fibrillation even though the effect of each individual pulse would not alone lead to ventricular fibrillation. The threshold for ventricular fibrillation applicable to a second pulse within the period between heartbeats can be as low as 65% of the threshold current for a single pulse. Each succeeding pulse reduces the threshold current by another ~35%, until a minimum threshold of ≤10% of the single pulse threshold is reached. Since a person immersed in the CSSC at Barrier IIA will experience 4 or 5 pulses per second , the value of the threshold current for inducing ventricular fibrillation is ≤10% of the threshold current for a single pulse.

Comparing voltage gradients measured within the CSSC at Barrier IIA while the barrier is operating at 4 or 5 pulses per second with a pulse width of 4 milliseconds and a maximum in-water field strength of 1 V/in to electric shock safety standards and to other scientific studies indicates that currents in a person immersed in the water could be life threatening. At a minimum, the shock effects could render an immersed person unable to maintain personal flotation or to assist in their own rescue. In the worst case, ventricular fibrillation could be induced. The probability of ventricular fibrillation being induced is greater than 50% and the risk of strong muscular contractions and difficulty breathing is even higher. These physiologic effects could result in death in a relatively short time. The most severe risk would be death from ventricular fibrillation or from asphyxia (due to either paralysis of the chest muscles or inability to remain afloat). Once removed from the electric field, if breathing cessation is less than about three minutes and ventricular fibrillation is not required, individuals may require pulmonary resuscitation to survive the exposure, but normally they can recover with no long-term physiological effects. When removed from the electric field, an individual suffering fibrillation does not spontaneously recover; emergency medical treatment including defibrillation must be administered within a few minutes of initiation of fibrillation or death will result. i

NEDU’s evaluation indicates that the electric current densities induced in the CSSC by Barrier

IIA operating at 4 or 5 pulses per second with a pulse width of 4 milliseconds and a maximum in-water field strength of 1 V/in pose a significant risk to immersed humans over a canal length of approximately 260 feet. Based on the reported range of flow rates in the CSSC, the transit time through 260 feet of a person drifting with the current could range from 2 to 15 minutes, with a mean of approximately 5.4 minutes. Thus, unless they are quickly removed from the water, an immersed person could spend a significant amount of time in a potentially harmful electric field.

Additional Risk Posed by Contact With Structures

The discussion immediately above assumes the immersed person is floating, swimming, or treading water without contacting anything other than the water. Once an immersed person touches or otherwise contacts a structure, such as a canal wall or a boat, the current induced in their body may change. This could change the risks to which the person is exposed. Therefore, it is also necessary to evaluate the physiologic effects of an immersed person contacting a physical structure, since during a rescue attempt the victim at some time will be in contact with the water and the canal wall, another structure, or a boat. NEDU used the same approach used to evaluate risk from immersion to evaluate contact voltage potentials measured by USACE for several scenarios.

A test was completed at Barrier I in January 2005 to determine the voltage potential difference between a reference electrode floating in the water above the barrier and the system ground for the barrier. This situation represents a worst-case possibility that would occur if the rescue of an immersed person was being attempted using a metal ladder, cable, or chain electrically connected to a ground. In such a situation, the current flow induced in the person has a greater than 50% probability of inducing ventricular fibrillation (Ref. 7).

Another test was completed at Barrier I in March 2005 to determine the voltage potential difference between a reference electrode floating in the water and a towboat as the electrode was pulled toward the towboat. This was intended to simulate a person being pulled to the hull of the towboat. The maximum voltage potential difference between the electrode and hull occurred when the electrode was near the boat, indicating that a significant current could be generated in an immersed person upon contact with the boat. This current would have a 5 to 50% probability of inducing ventricular fibrillation (Ref. 7).

The two described tests completed at Barrier I were not repeated at Barrier IIA because the risks would obviously still be present at IIA. However, site-specific tests were done at Barrier IIA to measure the contact currents generated by contacting the canal walls at seven locations above and near the barrier. The measured contact currents with the walls of the canal near Barrier IIA are low enough that they should not cause any serious physiological health effects (Ref. 7).

Measurements of contact currents generated by contacting the canal walls at locations above and near Barrier I also were low enough that they should not cause serious health effects (Ref. 7).

The canal walls are composed of rock. The contacts in the 2005 tests were with an electrical grounding system and a metal hull. Thus, the risks associated with contact appear to vary depending on the electrical conductivity of the object being touched and the extent to which the touched object is grounded.

Mitigation of Risks

NEDU reports that for a pulse rate of 4 or 5 pulses per second the maximum in-water field strength at Barrier IIA would have to be approximately 0.08 V/in or less to remain below the threshold for ventricular fibrillation. This is less than 10% of the field strength (1 V/in) required to repel large-bodied fish. Therefore, the barrier field strength can not be reduced to a safer level without rendering the barrier ineffective.

NEDU also reports that a maximum in-water field strength of 1 V/in with a pulse rate of 1 pulse per second would pose a low risk of ventricular fibrillation, although it would still pose a significant risk of strong muscular contraction. A pulse rate of 4 to 5 pulses per second has been identified as effective at repelling fish. However, the effect of using a pulse rate of 1 pulse per second has not been fully evaluated. USACE is initiating research into whether a lower pulse rate, perhaps as low as 1 pulse per second would reliably repel fish. If the results are favorable, USACE would reduce the barrier pulse rates. In the meantime, it is necessary to continue to operate the barriers at the higher pulse rate that is proven effective.

Even if ventricular fibrillation would not be induced, there is a strong possibility of an immersed person suffering involuntary muscular contractions that would make it difficult to swim or tread water. Therefore, the RNA requirement to wear a Type I personal flotation device on open decks while in the RNA is necessary.

NEDU notes that no electric field can be judged absolutely safe for all people. Some electric shock fatalities occur each year from intense emotion such as fear or excitement, even when the electric current involved is known to be safe for most normal individuals. This may be a particular risk at the CSSC dispersal barriers, as a person who has unexpectedly fallen overboard may be in a panic even without the added sensation of electric shock.

The key to mitigating the risks of human immersion in the electrified water at Barrier IIA or

Barrier I is to keep people out of the water. Recognizing this, USACE and the Coast Guard began a pubic educational campaign in March 2008. The intent was to ensure that commercial and recreational boaters were aware of the location of the barriers and the potential risks of contacting the electrified water. A joint press announcement was released on 27 March 2008.

Flyers were developed and distributed to recreational boaters at marinas and boat launches throughout the Chicagoland area during the spring. Beginning in April, the flyers have been handed out to vessels passing through the Lockport Lock, which is approximately 5 miles downstream of Barrier IIA. USACE is committed to continuing this educational campaign, with a particular emphasis on reaching out to recreational boaters early in each boating season.

There are existing large signs at both ends of the RNA. These signs and their location are shown on Figure 16. USACE is working to erect four additional signs. The new signs will provide more information on the risks of human immersion in the water and precautions to be taken.

They will also provide an earlier warning to approaching vessels. Figure 17 shows the proposed location of the new signs. Figures 18 and 19 show the current draft of the proposed sign language and appearance. While the design for these signs is finalized and the necessary real estate is acquired, temporary signs have been placed at locations similar to the final sign locations. The temporary signs are solar-powered LED highway message centers, which flash several messages to alert vessels that they are approaching and entering the fish barrier area.

To further reduce the possibility of someone falling into the electrified water from shore, additional fencing will be erected. Figure 20 shows the location of existing and proposed fencing. USACE is currently awarding a contract to erect the new fences shown on Figure 20.

The east side of the canal is a particular concern because there is public access to the road near the canal on the east side. The roads on the west side of the canal are already behind fencing and a locked gate. To further limit access on the east side until the permanent fencing is erected, temporary fencing was installed in the locations shown on Figure 20.

USACE is also currently working on plans for egress ladders in the vicinity of the barriers. The concept plan is to install ladders to the north and south of each barrier (Barrier I, Barrier IIA, Barrier IIB) on both sides of the canal. The ladders will be placed in recesses constructed in the canal walls. The recesses will also include a platform around the ladder at an elevation near mean canal water levels. This platform will provide a location for a person to sit or stand if they are unable to climb up the ladder. Design details are still being evaluated, including the appropriate distance from the barriers to the ladder wells and how to install the ladders and platforms while minimizing contact current concerns. The objective is to construct ladders and platforms for Barrier IIA and Barrier I by the summer of 2009.

CONCLUSIONS

There are inherent risks associated with the operation of the electrical dispersal barrier system in the Chicago Sanitary and Ship Canal. There is no way to reduce the electric field in the water to completely eliminate the potential for sparking between vessels or the health risks posed by human immersion without compromising the ability of the barriers to effectively stop the movement of invasive fish species. However, these risks can be greatly reduced if canal users obey the RNA and behave carefully near the barriers.

There is no risk at Barrier IIA, or at other electrical barriers, of increased sparking potential for on-board activities when a vessel is in the electrified water. There is a significant risk of sparking between vessels that make contact within the electric field and are not otherwise electrically connected to one another. There is also a significant risk of sparking if something conductive on a vessel within the electric field contacts a grounded object on land. However, these risks are minimized by complying with the RNA requirements prohibiting mooring, passing, and making or breaking tows and requiring transiting tows to be made up with wire rope.

The proximity of the fleeting area south of the Romeo Road Bridge to Barrier IIA creates additional concerns for sparking potential. However, the testing completed shows that Barrier

IIA can be operated without impact on the fleeting operations. Barrier IIA was operated at a maximum field strength up to 2 V/in without initiating sparking between barges during the making of a tow in the fleeting area. Also, a tow, properly made up with wire rope, spanning both the Barrier IIA electrodes and the fleeting area did not generate sparking when bumped into a barge in the fleeting area while Barrier IIA was in operation at a maximum field strength of 1

V/in. At the time of testing, Barrier IIA could not be operated at higher field strengths.

A test was also completed to evaluate the voltage potential differences that would develop within a long tow made up with wire rope if it transited the RNA with both Barrier IIA and Barrier I activated. The conclusion was that there is no significant additional risk of sparking within a tow transiting over both barriers operating versus the risk of transiting with only Barrier I operating.

The health risks of human immersion can obviously be avoided by avoiding human contact with the electrified water. It is not possible to control the behavior of all individuals, but it is possible to make every effort to ensure that canal users are aware of the location of the barriers, the risks they pose, and the importance of staying out of the water. To achieve this awareness, additional signs are being erected and a public outreach campaign will be a permanent ongoing feature of operation of the barrier system.

USACE believes that Barrier IIA can be operated at a maximum in-water field strength of 1 V/in with minimal risk, provided the RNA and the education campaign are continued. Before Barrier

IIA is operated at higher maximum in-water field strengths, additional testing at the higher field strengths is necessary to further evaluate sparking potential for long tows and operations within the fleeting area. Additional research will also be completed to evaluate if barrier effectiveness can be maintained while reducing the barrier pulse rate. If appropriate, barrier operating parameters will be altered in the future based on the results of these tests and research. However, the ongoing threat posed by potential migration of invasive fish species, including the Asian carp, makes it necessary to activate Barrier IIA now and operate it at as tested at a maximum field strength of 1 V/in.

REFERENCES

1. Engineering Analyses of the Chicago Sanitary and Ship Canal Electric Fish Barrier: Electrical

Effects on Barges and Tow Vessels. U.S. Army Corps of Engineers, Engineering Research and

Development Center Construction Engineering Laboratory. May 2005.

2. 33 CFR Part 165. Section 165.923 Regulated Navigation Area between mile markers 296.1 and 296.7 of the Chicago Sanitary and Ship Canal located near Romeoville, IL.

3. Engineering Analyses of the Chicago Sanitary and Ship Canal Electric Fish Barrier: Electrical

Effects on Personnel in the Waster. U.S. Army Corps of Engineers, Engineering Research and

Development Center Construction Engineering Laboratory. February 2006.

4. Dispersal Barrier IIA Electric Field Strength and Sparking Potential Testing. U.S. Army

Corps of Engineers, Chicago District and Engineering Research and Development Center

Construction Engineering Laboratory. 24 October 2006.

5. Dispersal Barrier IIA Sparking Potential and Electric Field Strength Testing to Determine the

Optimal Operating Configuration. U.S. Army Corps of Engineers, Chicago District and

Engineering Research and Development Center Construction Engineering Laboratory. 11 June

2007.

6. Demonstration Dispersal Barrier and Dispersal Barrier IIA Sparking Potential and Long Tow

Testing to Determine Safety Considerations. U.S. Army Corps of Engineers, Chicago District and Engineering Research and Development Center Construction Engineering Laboratory. 12

May 2008.

7. Evaluation of Risk That Electric Fish Barriers Pose to Human Immersion in the Chicago

Sanitary and Ship Canal. U.S Navy Experimental Diving Unit. June 2008.

8. Effects of Current on Human Beings and Livestock – Part 2: Special Aspects. International

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