Emergency Action Planning

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Lake Sherwood

Sylvan Lake EAP Case Study

The Dam Owner's Perspective

In Missouri, two events a few years ago caused many dam owners to consider what would happen if their dams were to fail. The first was the December 2005 catastrophic breach of the Taum Sauk Upper Reservoir dam about 90 miles south of St. Louis. The dam, part of a federally regulated power generation facility, released 1.5 billion gallons of water, devastating Johnson's Shut-Ins State Park. Because of the time of year the only persons present were a park ranger and his family, who suffered injuries. Their home was destroyed. The second incident was a 2011 statewide emergency response exercise timed for the 200th anniversary of the New Madrid earthquake. The scenario assumed a similar earthquake happened, with widespread destruction and dislocation, including the failure of several dams in eastern portions of the state near the Interstate 55 corridor. The exercise was conducted after Lake Sherwood Dam's EAP was completed, but New Madrid and the potential for another earthquake had been tugging on the minds of eastern Missouri dam owners for several years before the anniversary.

Group leader Glenn Lloyd
At the workshop Ed Varno, left, and George Schmidt, center, with Lake
Sherwood Estates, discussed their dam's EAP with Ryan Stack,
Missouri Department of Natural Resources dam safety engineer.

Ed Varno, Lake Sherwood Estates HOA manager, notes that it was mostly Taum Sauk that "got everyone thinking, and asking what might happen if our dam failed." Michael Daniels, Warren County Emergency Management Director, was also wondering.

"Mike was a key motivator in helping us get the EAP for Lake Sherwood done," Varno said. "He mentioned some of the benefits of having an EAP, and I agreed that we needed to do this. I do not expect anything catastrophic enough to take down our dam except an earthquake. That is the single biggest concern. We would lose everything.

"As we talked about it, I went down below the dam and saw the homes there and began to get a perspective and sense of the volume of water in our lake and where it could go. It seemed like the prudent thing would be to put some type of plan together, get some actions written down. Mike took the lead role at that point because he had developed similar plans for other emergency situations.

"Then DNR produced the new EAP format, which was a terrific template. They adapted it from national EAP forms that were very convoluted compared with what DNR developed. DNR's form was much more streamlined and made more sense. So when that format came out we changed what we were doing with our earlier legwork and put it into that format. When DNR did the inundation study we finally knew what could be possible if the dam failed. We saw how much water would come out if our dam breached, and where it would go. It helped us identify all the homeowners and businesses downstream.

"There are only 10 or 12 homes within a half mile below the dam. Farther down the land is more open and mostly agricultural. We were having a problem trying to determine how far the water would go until the study showed us. Identifying each individual located down there was a challenge, but Mike had access to information I didn't have. We were able to get homeowner names and send letters to them confirming addresses, phone numbers, and who else should be involved. We found that with an EAP it will be easier to notify DNR, emergency management, local police, state highway patrol, the fire department, and the others on the list to contact in case of a catastrophe. The most important aspect of all this is being able to notify people downstream as quickly as possible. Many of the homes are raised up, so we don't know for sure if they would be flooded, but initially the residents certainly would not be able to get out and go anywhere.

"As Mike and I began to talk about who could assist with various emergency and recovery matters, this became another stumbling block to work through. We had to identify who in the area has what sort of equipment and materials that we could need. That meant quarries if we need gravel or sand hauled in to reinforce or bolster the dam. We identified who had bull dozers, who had pumps. We might need a trucking company. Unless you begin to think through all these services and equipment you may need in an emergency, it never comes to mind except when something goes wrong. The EAP forces you into that mode of thought before an emergency – how do we do this, who else should be involved in this?

"We also would want to call on our private engineer, who is with Shannon & Wilson in St. Louis. They are very familiar with our dam and what the rock and soil strata are like around here, and they have records of work performed for us. In an emergency they can offer professional advice we don't have on site.

"It took us about a year to finalize the EAP, and one reason it took that long is that at first we really struggled with some of the more complicated federal EAP documents suited to much larger dams. We couldn't understand why some parts were necessary, and we wanted to do something different that would be easier to read. But as Mike noted, the EAP had to be something first responders were used to seeing and that FEMA would be expecting. When DNR came in with its template we were really thrilled to see it. It was a godsend. It's a format that is comprehensive but very understandable and not difficult to complete.

"At the time we started the EAP I don't believe anyone in Lake Sherwood Estates was very worried about the liability involved in owning a dam. But now that we have the EAP there is a sense in the community that they're glad someone thought about this and did it. An EAP is not hard to do. You just have to put some time into it and some resources. My advice to any dam owner is to go to your local emergency management director because this is what they do all the time. Work with the state dam safety engineers because they know the information they want in the EAP."

Varno also advises any dam owner to take interest in their dam, keep a close eye out for any conditions and changes due to vegetation or animal activity, and avoid getting complacent just because the dam has existed for decades without a problem.

"As managers of the dam we know how to maintain it, what is important, and we keep an eye on it so we don't have major vegetation growth on the back of the dam, and no animals digging holes. The residents also are more aware of potential dangers, and we may get a phone call from someone who saw a beaver or muskrat near the spillway. They know it might become an issue.

"We know that an earthen dam will leak forever, but we make sure they are only little leaks. We've had two different types of leaks. The upper ones go around the side of the dam and come out behind it, creating a small waterfall. When the lake drops 38 inches below normal pool, it stops. It's not a major issue, and if we can find it we will stop it, but it's not a critical leak.

"We also have had some deeper leaks, and we've done some dye testing over the years. We've had five rounds of grouting. The engineers tell us where they need to drill, and each time it has reduced the leakage. But it's never fully stopped it. The leakage always seems to creep back, and now we're at a point where we will do more grouting. The engineers are developing a plan for testing and probably for grouting in 2016.

"With the EAP completed the next step will be to test its assumptions with an exercise later this year. It's just a matter of finding the right time to do it. Mike and I have discussed the exercise as a way to find out if anything in the EAP needs to be updated or changed. We're glad to have our EAP, but we want to stay confident in it."