Excavation at hydro project site now includes blasting
Oct 28, 2015
Excavation for the powerhouse and tailrace at the Red Rock Hydroelectric Project (RRHP) site at the Lake Red Rock Dam has now reached bedrock, which means that explosives will be needed to remove the final layers of bedrock before the powerhouse foundation can be set.
Excavation using explosives starts with holes being drilled into the bedrock. Explosives are then placed in the holes and ignited causing the rock to crack and splinter. Crews can then break up and haul the rock away from the site. The first blast occurred at 12:35 p.m., Wednesday and went very well, according to Ray Wahle, Power Supply and Operations director at Missouri River Energy Services (MRES). “We plan to excavate in this manner over a two-month period,” Wahle said. “The powerhouse, where electricity from the project will be generated, will be located at that spot.”
In all, about 32,300 cubic yards of rock will be removed by blasting. That is enough to cover a football field with 15 feet of rock.
Although the blasting is confined to a small area 100-feet below the road, this activity requires that Highway T-15 across the dam will be closed for short durations to ensure the safety of the public and workers. The road closures will occur between the hours of 8 a.m., and 8 p.m., Monday through Friday, and will be less than an hour in length. Variable Message Boards will be posted along T-15 on both the Pella and Knoxville sides of the dam to inform drivers of the closures. The blasting activity and road closures are expected to continue until late December, and a separate press release will be issued once that portion of the work is completed.
MRES, which supplies wholesale electricity and energy services to 60 communities, including Pella, in the states of Iowa, Minnesota, North Dakota, and South Dakota, is building RRHP. When the project is completed in 2018, it will be the second largest hydropower facility in Iowa and will be capable of supplying enough electricity to meet the needs of 18,000 homes.
“We regret that these road closures will cause inconveniences to people in the area, particularly those who use T-15,” said MRES Director of Member Services and Communications Joni Livingston. “But the safety of the public and of the workers at the project site remains our primary concern.”