April 23rd, 2012
I-15 CORE’S “OLD FAITHFUL”Uncategorized, by Catherine Higgins.
By Aaron Mentzer, I-15 CORE Social Media Manager
Drivers on I-15 in Springville may have noticed a large fountain of water gushing into the air like a geyser west of the freeway in early March.
All of the water flowing into Hobble Creek — approximately 20,000 gallons per minute — was pumped through five 12-inch-diameter pipes a few hundred feet downstream while I-15 CORE construction crews installed a new box culvert to allow the creek to pass under I-15.
“The existing culvert was just too small to handle the quantity of water in the creek,” said Ray Stillwell, Environmental Compliance Manager for I-15 CORE contractor Provo River Constructors (PRC). “It was almost always full, with no additional capacity to deal with runoff or heavy rainfall. The new culvert is much wider and includes two additional overflow culverts adjacent to the main box to accommodate higher-than-normal flows.”
Rerouting a creek or canal is common in construction, but this was not a typical case. Hobble Creek is a key spawning site for the endangered June sucker, which is only found in Utah Lake and its tributaries. Farther downstream, the creek
channel had recently been reconstructed by the Utah Transit Authority, in cooperation with the Utah Department of Natural Resources (UDNR) and Bio-West, to create the Hobble Creek Wetland Mitigation Site. PRC needed to divert the creek in a way that (a) followed the existing channel as much as possible; (b) prevented erosion and sedimentation within the wetland mitigation site downstream; and (c) preserved the June sucker’s spawning habitat.
To solve this problem, the CORE team developed a creative solution. They installed five pumps in the creek with 12-inch outlet pipes to route Hobble Creek around the new box culvert and into the existing channel. Ninety-degree elbows were attached at the end of the five pipes so the high-pressure flow of water exiting the pipes would be directed upward, minimizing erosion and sediment generation.
During design and construction of the new channel, PRC coordinated with UDNR and Bio-West, and the resulting design limited wetland impacts to a much smaller area. “Working with these other agencies, we were able to re-build the channel in a way that minimizes impacts and maintains or enhances the spawning areas for the June Sucker,” Stillwell said.
Workers installed carefully selected, native rock at different locations in the channel as well as in the box culvert itself to restore the habitat in the new creek bed. With the channel reconstruction and rock placement completed, workers removed the temporary upstream dam, and water began flowing through the new culvert last month.
“This new culvert is a great example of the cooperation and innovation taking place throughout the I-15 CORE project,” said Mike Brehm, I-15 CORE Environmental Manager. “Parties from several agencies worked together to construct this culvert in a way that actually benefits the environment.”