|While recently working on the small generator bearings at our dam, the dam’s plant supervisor noticed that a hardened area on the shaft of that generator was missing a piece of the protective coating. As a result, this small generator – which helps regulate daily lake levels – is now out of commission.
The repair, the first of its kind for our dam, cannot be made in place or with the lake at its normal level. The generator has to be completely disassembled. The shaft and runner will have to be removed and the shaft sent out for repair.
This information is to make citizens and property owners aware that the Town of Lake Lure will draw down the lake as much as eight feet, and possibly more, in order to address this serious repair need.
The issue was discussed at length by the Lake Lure Lake Advisory Board, the Lake Lure Marine Commission and the Lake lure Town Council during each board’s September meeting.
The draw dawn will begin Dec. 1 and not begin to be refilled before March 1st. The goal is to complete the repair within this time frame. However, several circumstances could extend the draw dawn beyond March 1st.
Of the two generators at the dam, the smaller generator is the unit used on a daily basis to fine tune lake levels. With it completely out of commission, residents and visitors will begin to see some noticeable fluctuations in the lake level between now and Dec. 1st.
The small generator uses approximately three times less water than the larger generator and allows greater flexibility in managing those levels. Thus the reason why the repair needs to be addressed sooner than later.
The repair process is not without its risks. In order to complete it, plant staff must enter the penstock for an extended period of time. The penstock is the intake structure that controls water flow and delivers it to the hydro turbines. It is a pipe approximately ten feet in diameter that gets smaller as it reaches the turbines. It is a dark, confined and foul-smelling space in which to work.
Individuals working in the penstock, and the resulting void left by the shaft and runner, presents the potential for a catastrophic accident. That is because the staff is relying on only one valve to keep the lake from flooding the penstock.
Such an episode would kill anyone in it, damage the power house and the only other generator. In order to eliminate these risks, Town Council, Lake Operations and the Marine Commission made the decision to lower the lake.
The town currently has the lake on an every three years draw down schedule. This is to maintain the dredging program and give property owners an opportunity to work on their docks, boathouses and shoreline stabilization projects.
Prior to this incident with the small generator, the lake would not have been scheduled for its next significant draw down until 2017.
The Marine Commission, in its decision to draw down the lake this year, also voted to stay on the current schedule and lower it again in 2017 so that residents and property owners can move ahead accordingly with existing plans to complete work on docks, boathouses and shoreline stabilization projects.
Reprinted by permission from the Town Newsletter, Valerie Hoffman, Editor.