SIOUX FALLS, S.D. (KELO) — Less than six months after June flooding destroyed waste water force mains in the city of Vermillion, the mains have been replaced.
The first two force mains were damaged and a third followed later. The city was forced to discharge raw wastewater into the Vermillion River at a rate of about 1.2 million gallons a day from June 27 through July 12, the city’s public works director Shane Griese said in July.
Before the permanent fix, a temporary suspension bridge was installed to support a temporary main over the river. It was finished on July 13.
The permanent project cost came in about $12,600 under budget to total about $832,223, according to material in the November city council meeting.
The bulk of the work is done underground, under the river.
Griese said contractors bore under the river to about 30 feet. “The design called for plus or minus five feet,” Griese said of the 30-foot target.
RP Construction was the general contractor on the project. Ellingson did the horizontal drilling needed for the project.
“It’s a little bit specialized,” Griese said of the horizontal drilling. “There are a lot of contractors that do horizontal drilling but usually not with this big of pipe.”
The project used two 12-inch and one 10-inch pipe. That’s the interior diameter. When the exterior of the pipe is included, the 12-inch pipes are 14 to 16 inches and the 10-inch pipe is 10 to 12 inches.
Crews make an initial bore under the river which is widened to allow for the force main to be installed, Griese said.
“They pull the (force main) pipe through the hole under the river,” Griese said.
The force main project was completed before the Nov. 1 deadline.
“We ran into some really good weather,” Griese said. The general contractor originally had an Oct. 4 date for intermediate completion but after discussion, the city waived that deadline, he said.
RP Construction said if the intermediate deadline was waived, it would complete the project ahead of schedule, Griese said.
“The work was progressing really well,” Griese said. The project was substantially completed on Oct. 11.
“Everything was operational by Oct. 11,” Griese said. “It is running excellent, how it is supposed to.”
The temporary bridge and pipe are gone.
“You can’t really tell we did anything there,” Griese said of the project.
Some seeding of grass along the river and other items are still left to finish.
