Blasting to begin on North Fork reservoir improvement project
Crews working on the dam at Burnett Reservoir are expected to begin blasting rock next week as part of the two-year project begun this winter to shore up the dam’s defenses against extreme rainfall and seismic activity.
The blasting of bedrock is necessary to create an auxiliary spillway that will help the 62-year-old dam handle the kinds of downpours that flood the North Fork watershed every 200 years. The project also includes a series of eight “fuse gates” that will be tripped by the kinds of storm that happen every 50,000 years.
The sequentially tripped gates are designed to handle the volume of runoff that occurred during storms Ivan and Frances in 2004 and during the flood of 1916, the highwater mark of storms in Western North Carolina. All the water that runs off the mountains above Black Mountain pours into the 22,000-acre reservoir, also known as North Fork Reservoir. The reservoir and water treatment plant there provide 70 percent of Asheville’s drinking water.
The $30 million-$35 million project will triple the amount of water the reservoir can release every second.
The blasting shouldn’t cause too much of a commotion, Bill Hart, North Fork Water Treatment Plant supervisor, said last week.
“Our expectation is that people shouldn’t notice much of anything at all,” he said. The explosives will be deeply embedded in the bedrock and should be much less noticeable than the explosions at nearby Grove Stone & Sand, which often shake buildings at the water treatment plant, he said.
Blasting to create fractures in the bedrock, initially scheduled to begin March 26, was more likely to begin April 2 or 3, Hart said March 22. Blasting should be completed in two months and shouldn’t be detected much beyond the blasting site, he said. The explosions, to occur between 9:30 a.m.-3:30 p.m., will happen once or twice a day, followed by one to three days of excavation.
The project will raise the 130-foot-tall dam by four feet and make improvements to the principle spillway. It is meant to create seismic stability by buttressing the earthen 1,200-foot-long dam and reinforcing the 55-foot-tall, 600-foot-long saddle dam that protects a low-lying area of the reservoir. It will modify the raw water piping through the dam and to the water treatment plant. Contractor Phillips & Jordan is doing the work.