ES Council gets alarming Black Bass Dam report

EUREKA SPRINGS -- Black Bass Lake is a scenic delight with great hiking trails and kayaking opportunities right in the heart of Eureka Springs. It also sits above a pumping station that supplies drinking water and fire protection to about 70 percent of the town. But if you look at the face of the dam, there are rocks missing with a resulting jumble of mish-mash that makes it look improbable that the dam could still be standing.

And it doesn't just look bad. The City Council heard reports Monday night the dam has deteriorated alarmingly in the past four years, and particularly in recent months with heavy rainfall causing significant erosion of the quasi-cementitious fill material that holds the rock face in place.

At risk are not only any people in the flood plain and low-water crossings if the dam were to breach and fail, but the city's water supply system. Mayor Dani Joy said the pumping station would be wiped out if the dam, originally built back in 1894, comes tumbling down.

Historic, and expensive

Joy said there has been a lot of erosion because of the rain. FEMA is planning to visit this week to look at the dam to consider stabilization funding.

"It is a huge project," Joy said. "The proposal is for over $100,000."

"It is an historic dam," said Alderperson Butch Berry. "For people familiar with the dam who have seen deterioration, it is pretty amazing -- I don't want to say frightening -- to see how much has deteriorated in the past two years. There are stones completely missing, stones that have fallen down. While the engineers were there, some stones were falling. The whole face of the dam is at risk.

"It is a serious concern if, as noted, when it fails -- and it is going to fail -- it will wipe out the pump station that supplies the west side of city. We have a letter from Carroll-Boone Water District that indicates that if the pump station fails, we won't be completely without water; however, there will be low water pressure which could affect fire fighting and a lot of the motels."

5-ft. draw-down underway

Public Works Director Duane Allen said the city recently put in pipes to siphon the lake down five feet to relieve the pressure behind the dam. At his recommendation, the council approved allocating $90,000 to begin emergency repairs on the spillway and other areas of the dam that are showing the most erosion. That expenditure will be paid for with FEMA funds that have already been approved.

The city hopes to obtain more FEMA funding in the future to address repairs to the front and the back of the dam.

The council heard from dam engineer Richard Dee Purkeypile, P.E., a Eureka resident who works for TRC, Austin, Texas. Purkeypile has been donating his services to inspect the dam and provide recommendations.

"It is in bad shape and we should do something about it," Purkeypile said. "We have reduced external pressure on it so there is less liability. But the fill material is deteriorating each time it rains. More of the buttresses and walls will fail. We've been looking at it for at least four years and it has been deteriorating significantly."

As recommended, a cut-limestone wing wall will be used to prevent the spillway channel from overtopping and discharging along the downstream toe of the dam. The end of the concrete spillway discharge chute will be extended and tied into the native limestone bedrock using reinforced concrete that is dowelled into the existing concrete walls and chute floor.

As for replacing the missing stones in the front face of the wall, the council heard that would be extremely dangerous due to the unsupported nature of the upper portion of the dam, especially the walkway along the top of the dam.

1915 addition leakiest

Purkeypile said nearly 100 percent of the seepage has been stopped with the draw-down of water. He said the top eight to ten feet added in 1915 are in the worst shape, possibly due to using inferior materials and workmanship.

The question is how to fix the problem at a price the city can afford. Mass stabilization with rocks and mortar has been considered. But some people don't want to lose the original cut-stone dam look.

"It could be one of the last hand-cut stone dams in the country," said Rae Hahn, a former alderwoman. "It is a historic structure, they are coming down."

Hahn said she would provide the council with an engineering report done earlier on the dam that she said came out of a year of hard work looking at the issue. Hahn said putting something in front of the dam may not solve the problem. But she said because of the tremendous job the Parks and Recreation Department has done building trails in the area, and the lake's historic character and scenic beauty, fixing Black Bass dam should be a priority.

Purkeypile said it is possible that FEMA money could be used to clean up the face of the dam, pressure grout it and seal it up. He said the city doesn't "have to be married to the initial mass stabilization concept" and instead could consider addressing stability by stepping back and considering other options to stabilize the dam. The original dam had a stepped spillway that was faced with cut limestone rock.

"That would lend itself to the historical look of what was there in 1894," he said. The final look of the repaired dam will ultimately depend on the availability of funding for the repairs.

Other business

In other business, action on the city's sidewalk ordinance was tabled after a motion to make replacing limestone sidewalk with limestone an option rather than a requirement failed on a vote of two to two, with Berry and Alderperson James DeVito voting for limestone and Joyce Zeller and Mickey Schneider voting to allow people the option of using concrete. "I'm afraid you are putting homeowners between rock and hard place by insisting they use something dangerous," Zeller said.

DeVito disagreed, and said limestone is not inherently dangerous and can be finished to any surface you want.

DeVito said limestone costs $15 per square foot while concrete is $10 per square foot, and that for an average lot (1,600 square feet of sidewalk), the cost would be $800 more for limestone.

Schneider had different numbers stating it would cost $67 per square yard for concrete and $135 for limestone. Schneider was concerned about the affordability of repairs.

Proponents of limestone sidewalks have said it is important to retain the historical appearance of the town.

During public comment, Enid Swartz didn't express an opinion about what kind of materials to use to repair sidewalks. But she wants it done quickly. Her husband was knocked out after falling on an uneven sidewalk Sept. 6 on Main Street, had an overnight stay in the hospital and bills totaling more than $6,246.

"Thank God we can afford health insurance," Swartz said. "But what about other people who fall in Eureka? We must repair our dangerous and uneven sidewalks. We call ourselves a welcoming tourist Mecca. But $6,000 in medical bills is a big tourist turnoff."

Board appointments

In board appointments, council approved appointing David Graupner to the Planning Commission. Enid Swartz was appointed to the Hospital Commission. Joanne Graupner was nominated by the mayor for a position on the Parks and Recreation Commission. One position is still open on the Historic District Commission.

Mayor Joy announced that Smith Communications has filed a lawsuit over the city's denial of a cell tower on Planer Hill.