By Scott Robertson
The Tennessee Valley Authority held a series of meetings July 30 to announce its plan to address seepage issues at Boone Dam. After meeting with elected officials and the media, John McCormick, TVA vice president of Safety, River Management and Environment told a crowd of just over 300 at a public information session in Johnson City, “We have benchmarked this project. We have looked at many dams that have gone through this kind of repair, and the benchmark for this type of operation is about five to seven years to perform.” After a few seconds of catcalls from disappointed attendees, McCormick continued, “It’s also going to cost in the neighborhood of between $200-300 million to install, but I will tell you, this is a permanent repair for this reservoir. This is doing it right.”
Many residents and businesspeople whose properties abut the lake have been adversely affected by TVA’s decision to lower the lake level to take pressure off the earthen portion of the dam.
TVA has been studying the extent of, and potential solutions for the seepage problem since it was discovered in the earthen portion of the dam last October. Investigation of a sinkhole at that time led to the discovery of a series of underground geological pathways allowing water “piping” to cause internal erosion. If left uncorrected, McCormick said, the erosion could eventually lead to the failure of the dam.
McCormick outlined the steps that will be taken in completing the dam repairs.
“We looked at many, many options,” McCormick said. “We had to. We are required by law to look at many options. Our long-term fix is to insert a concrete cutoff wall in the earthen dam. That concrete wall will go in in three stages.
“Stage one will require us to drill multiple columns and multiple rows from the concrete structure all the way past the beach area,” McCormick said. “About 500 borings will have to be done. We will drill down into the epikarst and insert low-mobility grout. To help you see low-mobility grout in your mind, think of cold toothpaste.
“Stage two will also require us to put multiple borings into the earthen dam,” McCormick said. “In this case, there will be three across the entire length of the dam. This will go down 250 to 300 feet into bedrock. Again, the intent of drilling down and inserting this low mobility grout, which will harden under the surface of the earth, is to stop the water flow.
“The third and final stage is putting in this ‘concrete’ – and it’s not actually concrete, it’s a composite that acts like concrete – cut-off wall. This wall is going to go from the top of the crest down as far as 250 feet. It will be multiple feet thick. And again, it will run the entire length of the earthen dam.”
McCormick told the largely skeptical crowd that TVA has been working with private firms to analyze the problem before choosing the five-to-seven-year option. “We reached out to industry experts, some of the best in the world who have worked on other dams facing the same issue, to help us identify what the risks were and what some opportunities and options were to repair this dam.
“This option is a very robust option,” McCormick added. “We did intensive research, a comprehensive and thorough investigation. That has led us to this option being the best option to pursue.”
While preliminary work is already underway, said John Kammeyer, vice president of construction, an environmental study must be completed before work can begin in earnest. “There are only three companies in the world that can do this,” Kammeyer said. “We have been working with one of them. We will be putting the full job out to bid.”
Many attendees were unimpressed by TVA’s presentation. The first member of the general public to address the TVA panel, Scott West, said, “Five to seven years is unacceptable. Let’s put things in perspective. The Empire State Building in New York City was built in one year and 45 days. The Hoover Dam, the largest dam in this country, was built in five years. The San Francisco Bridge – four years. And you guys can’t fix a water leak in five to seven years.”
“We had other options,” McCormick said. “We could do it faster. But we would find ourselves in the very same position we are today again. (Doing it faster) is not a permanent, or even a long-term repair. This is a permanent repair that puts us in a position to deal with sinkholes that come up in the future without having to take that water level down.”
Kammeyer said the repairs will be complicated by the fact that there is limited workspace and at times, around 200 workers will be “on top of each other” to get the job done on time and under budget. “In 2016, when we bring in the major contractor, that group will be working 24 hours a day, seven days a week, either doing production work or maintenance on the equipment. Right now we’re doing the testing, we’re doing the set-up, we’re doing all that facilities work that you have to do in order to do a project while we wait for the NEPA review to be done. So we’re doing as much as we can. We’re doing the procurement side, we’re going out for bids next month on the base job, the engineering, the construction, get all those pieces in place so that when the evaluation’s finished, we’re ready to hit the start button.”
Several businesses already have been, and will continue to be adversely affected by the drawdown of the lake level. But the long repair time and large number of workers on site will likely create opportunities for other local businesses.
The owner of a lakeside apartment complex, Kevin Beckett, approached TVA officials at the public information session about the possibility of housing workers who will be effecting repairs on the dam in his units. “When the lake was up, (my apartments were) 100 percent full. I’m currently at 50 percent occupancy, and after the announcement today, I’m almost sure I’m going to lose more. So my question is not for a handout or help. What I would like to do is possibly…set up some kind of contractual agreement for housing for your workers. That will help me and you.”
Vish Patel, owner of The Boone Store, a gas station across Highway 75 from the Boone Dam turnoff, also sought a contract with TVA. In his case, it would be for provision of fuel for the trucks that will be delivering materials to the dam.
Kammeyer told Patel, “I’m sure we’ll be going local. The constructor that’s doing this work is international. We’ll be bringing them on next year. But there’ll be opportunity for a lot of local business growth, new business, so yes, absolutely.”