Emergency action plans are only effective if people at risk from a dam failure have adequate time for evacuation. A tabletop exercise often can reveal shortcomings in an EAP, without the time and cost involved in a functional or full-scale exercise.
By Paul J. Shannon
One goal of the Federal Energy Regulatory Commission (FERC) is to ensure all dams under its jurisdiction have workable and effective emergency action plans (EAPs). In order for an EAP to be effective, the following two things must occur before anyone is affected by a dam failure:
– The dam owner verifies there is an emergency and notifies emergency management agencies; and
– People at risk are warned and are able to evacuate the inundation zone.
These two items can be difficult to accomplish, particularly since there often are residences, businesses, campgrounds, and recreation areas located directly downstream of dams.
Functional and full-scale exercises, where a simulated emergency allows participants to act out their roles in a timed and stressful environment, reveal if there is enough time to get people out of harm’s way. However, these exercises can cost tens of thousands of dollars when factoring in staff time, facility costs, and communication equipment. By comparison, tabletop exercises are much easier to design and conduct. The largest costs typically come from renting a room big enough for all participants and providing lunch. However, tabletop exercises often do not address the timing of emergency responses or if there are adequate resources.
For a tabletop exercise to truly reveal if an EAP is effective, particular attention must be paid to listing the detailed actions of each participant and the realistic time each action would take. This process can be done whenever there is a concern regarding whether people can be warned and evacuated in time.
What’s involved in a tabletop exercise
A tabletop exercise includes representatives of the dam owner and emergency management personnel who would be called upon during an emergency. The exercise is run by a facilitator, typically a representative of the dam owner or a consultant. The facilitator begins the exercise by describing a simulated event. All participants then discuss the actions they would take during the emergency. The facilitator can have participants discuss the detailed steps they would take and how long they believe each step would take. The closer that an area of development – such as a campground – is to the dam, the more detail is needed to determine if there is enough time to warn people.
The difficulty with this process is that participants often are not realistic with their time estimates. For example, in the case of a remotely operated dam, an owner may say it takes the company’s designated responder ten minutes to drive to the facility. This estimate reflects the best drive time under ideal conditions (e.g., on a sunny day, no red traffic lights, and exceeding the speed limit). On a typical day, the trip may take 15 minutes door-to-door. At night, in the rain, or with icy conditions, the trip may take twice the original estimate. That additional ten minutes could mean the difference between a successful and an unsuccessful response to the emergency. The facilitator of the tabletop exercise needs to question participants thoroughly to arrive at the most accurate time estimates.
Once total response time is established, it can be compared to information from inundation maps. The amount of time that elapses from the assumed failure of the dam to when affected people are out of harm’s way should be less than the time it takes flows from the failure to arrive at an area of concern. If not, the EAP must be enhanced to ensure people are evacuated in time.
How a tabletop exercise works
The following example describes the process involved in a tabletop exercise.
Background for the exercise
A dam that impounds water for a hydroelectric facility is located in a rural area.
An operator is stationed at the project from 8 a.m. to 4:30 p.m. on weekdays and visits for about 30 minutes on Saturdays and Sundays. The generating units are automated, and instruments continually monitor upstream and downstream water levels. During off-duty hours, an autodialer system notifies the operator if any instrument reading indicates a problem. The operator lives about 15 minutes from the dam.
Riverside campgrounds located directly downstream of dams often need enhanced warning and evacuation measures to ensure the safety of campers in case of dam failure.
The closest area to be affected by failure of the dam is a privately-owned campground about 1.2 miles downstream. There are about 75 campsites, with about 30 sites within 100 horizontal feet of the river bank. A superintendent lives adjacent to the campground, within a five-minute walk to the campsites. Data from inundation maps indicates the flood wave would arrive at this location about 26 minutes after dam failure. Time to peak water level would be about one hour and 15 minutes. The maximum incremental rise of water at this site would be 6.5 feet. The only other effects of dam failure would be to 12 riverside homes in a small city 13 miles downstream. The flood wave would arrive here six hours and 20 minutes after dam failure.
Table 1: Original Tabletop Exercise Timeline for Emergency Action Plan (Items in yellow are not initially known by participants.)
During previous discussions, the emergency management agency indicated it would take ten to 15 minutes for a local deputy to arrive at the campground to evacuate residents. A timely evacuation seemed possible because emergency responders would have about 30 minutes after the dam fails to get people to higher ground. In addition, the EAP for this dam contains the name and phone number of the campground superintendent. The emergency management agency was confident the riverside homes in the small city would be evacuated before the flood wave arrived.
Running the exercise
A tabletop exercise is being performed for the hydropower project. A facilitator who represents the dam owner leads the exercise. After introductions, an orientation seminar is given to ensure that all participants understand the project, the potential effects, and procedures described in the EAP.
For this exercise, the operator is awakened at 3:30 a.m. by the autodialer indicating a low reservoir level. Based on this scenario, the facilitator asks the operator, dam safety manager, and emergency response personnel to describe their actions.
Table 2: Revised Timeline for Emergency Action Plan (Items in yellow are not initially known by participants.)
At this point, exercise participants do not know what caused the sensor to activate. At 3:15 a.m., the left embankment dam experienced a sinkhole at the crest. Water began to overflow the low area in the embankment, traveled down the slope onto natural ground, and entered the river about 0.25 mile downstream. Because the flows entered the river further downstream, the water level sensor in the tailrace adjacent to the dam was not immediately triggered. By 3:28 a.m., overtopping flows caused a complete breach of the embankment. At 3:30 a.m., the autodialer system called the operator.
The facilitator writes down all responses from the participants and gets estimates of time involved for each item. Table 1 on page 30 shows the responses. (Note: The items highlighted in yellow are not initially known by the participants.)
Discovering an inadequate EAP
The timeline developed as a result of the tabletop exercise reveals an ineffective EAP. There is not enough time to warn campers and evacuate the campsite. In fact, the first attempt to contact the campground would occur about 30 minutes after the first campsites were being inundated. Previous exercises never considered the time it would take for the operator to physically verify an emergency at the dam during non-work hours. Also, it would be nearly impossible for emergency responders to reach the campsite in time to perform evacuations, even with immediate notice.
Additional measures are needed for this EAP to work.
Discussing and revising the EAP
The dam owner and emergency response agencies reviewed the timeline and determined the following changes were needed:
- Shortening the time needed to verify failure if the dam is unmanned. The dam owner decided to install web cameras and lights focused on staff gages in the reservoir and tailrace. These cameras will be accessed via the Internet from the operator’s and dam safety manager’s homes to verify a dam failure and shorten response time by 20 minutes. Also, both the operator and dam safety manager will receive autodialer notices for water level alerts.
- Contacting the campground superintendent sooner. The EAP will be modified to instruct the operator to call the campground superintendent immediately upon discovering an emergency. Both the operator and dam safety manager will keep copies of the EAP in their homes. The emergency management agency will also try to contact the campground superintendent using a radio system.
- Educating campers that they may need to undertake emergency procedures. The emergency management agency and dam owner will prepare brochures to be given to campers when they check in. Brochures and evacuation maps also will be posted on camp site bulletin boards near rest rooms.
- Informing campers about their actions. Using the inundation maps, the campground manager, emergency management agency, and dam owner will determine nearby high ground where campers can stay until they are evacuated. The dam owner will finance installation of signs showing the evacuation route.
- Enrolling the campground superintendent to evacuate campers during emergencies. The emergency management agency and campground superintendent agree the superintendent will try to warn campers. The dam owner will give the superintendent a blow horn for warning campers. In case of downed phone lines, the dam owner will provide a radio system between the campground and the emergency management agency.
- Including the campground superintendent in drills and exercises. The dam owner will give the campground superintendent a copy of the EAP notification flow chart and include the superintendent in annual drills and exercises.
New results of the exercise
With the new measures in place, a second time line can be prepared to determine if the EAP is now effective. (See Table 2.)
A comparison of the two time lines shows the new measures would result in the campground superintendent being informed almost 50 minutes sooner than previously. This time savings is crucial for successfully evacuating campers. After implementation of the new measures, a functional or full-scale exercise can be performed to verify the assumed time estimates for the emergency procedures and ensure the EAP is effective.
Mr. Shannon may be reached at Federal Energy Regulatory Commission, 888 First Street N.E., Washington, DC 20426; (1) 202-502-8784; E-mail: paul. email@example.com.
The views expressed in this article do not necessarily represent the views of the Federal Energy Regulatory Commission or the U.S. government.
Paul Shannon, a civil engineer with the Federal Energy Regulatory Commission (FERC), is an instructor for FERC’s EAP Exercise Design Course and a member of FERC’s EAP Technical Resource Group. He has participated in many tabletop and functional exercises.