McCarthy Building Companies Inc. based in St. Louis, Mo., is the contractor for the $215 million upgrade of the Sioux Falls Regional Water plant.
(McCarthy Building Companies Inc. photo)
As the first major expansion at the South Dakota facility in more than 40 years, a $215 million upgrade of the Sioux Falls Regional Water plant will significantly increase the plant's ability to treat wastewater safely and effectively. When complete, the plant is expected to see a 50 percent increase in treatment capacity, from 21 million gal. per day (gpd) to 30 million gpd.
"This is a huge deal," said Mark Perry, wastewater superintendent, city of Sioux Falls Public Works. "The project will rehabilitate the current facility, while expanding the plant.
"The city of Sioux Falls and surrounding area has experienced rapid population growth over the past two decades. The Sioux Falls Regional Water Reclamation Plant is critical infrastructure, and we need to ensure it is well-positioned to meet the needs of our growing community for decades to come."
An official groundbreaking took place in early May 2022, but the expansion has been a long time in the making.
"As our team likes to say, this project takes a marathon mentality. After years of preparation, the launch of this project intersected with the COVID-19 pandemic, which wreaked havoc in many ways, from the way our internal and external project teams communicated to supply chain issues and cost escalation. In the end, and to this day, it took determination and perseverance from our team to keep this project moving forward."
Perry explained the improvements involve five main areas of impact, including headworks, aeration basins, chlorine contact basins, solids handling and electrical system improvements.
"The improvements will increase the plant's hydraulic ability from 21 mgd to 30 mgd flow. The peak flow during wet weather will be increased to a capacity of 60 mgd. The solids loading treatment capacity will also be increased from 51,200 pounds per day to 66,700 pounds per day removal.
"All this translates into increasing the plant capacity for regional service of approximately 295,000 people in the future, compared with a little more than 215,000 people today. The wastewater will be treated to the same quality level as in the past, but the facility will now be set up to convert to increased nutrient removal limits in the future, which will further increase the quality of the water discharged into the Big Sioux River."
Perry said the community has been supportive of the project.
"Any time a municipality is taking on a construction project, particularly with this price tag, it's important that we are communicative and transparent. Overall, people understand the importance and necessity of this work."
He added, "This project wouldn't be possible without the countless hours and immense talent dedicated to it by our public works team, teams from across the city of Sioux Falls and our many contractors. Our core values are safety, teamwork, character and respect. I see each one of those values embodied in our team members as they've taken on this colossal project.
"On behalf of our team, we all feel this work is incredibly rewarding. The long days and any hurdles we face with this project will all be worth it to know we are creating something for our community that will outlive many of us. It's rewarding in that sense to be part of something bigger than yourself."
According to Dave Moran, project director, McCarthy Building Companies Inc. based in St. Louis, Mo., a number of tasks have already been finished.
"To date, we have completed the excavations for the new headworks building; A-Basin expansion; the four new final clarifiers; CCB expansion; and portions of the new switchgear building. Concrete has been placed at the lower level of headworks; portions of the slabs and walls have been placed; and A-basins and portions of the final clarifiers have been placed."
Crews are currently working on the structural concrete at headworks; concrete for A-Basins 7 through 9; mechanical and structural work in A-Basin 6; yard piping for the influent and effluent of the A-Basins; underslab piping at the final clarifiers; structural concrete at CCB and demolition at the thickening building.
"We are still very early in the project, so many significant activities remain," said Moran. "Through 2023, we will focus on yard piping, structural concrete and A-Basin 1-6. In 2024, the focus will be process piping, mechanical installation and general building trades."
Moran noted one of the major issues on the project involves the upgrades of existing aeration basins, due to the structural and mechanical upgrades required.
"Out of the six existing basins, only one can be taken out of service at a time while flow into and out of the remaining basins must be maintained."
Keeping everyone out of harm's way is also a top concern.
"The safety of the plant staff, along with craft working on the project, is our highest priority. Working in the existing facility poses several challenges, including live electrical, live process lines and potentially dangerous gasses."
Rehabilitating the existing plant involves a great deal of planning.
"Due to improvements taking place across several different parts across the existing plant, several provisions must be made to facilitate flow around construction activities, which we refer to as Maintenance of Plant Operations [MOPOs]. While the job site has more than 40 MOPOs, some of the critical ones include temporary piping and structures to bypass the splitter structure/A-Basin Influent, the A-Basin effluent manhole and bypassing the CCB."
Long overdue for an upgrade, the structure is in definite need of the repairs now being made.
"Overall, the plant staff has done a fantastic job maintaining the facility in the areas they can access," said Moran. "We are still determining much of the plant condition, because it cannot be determined until basins are drained or demolition has been complete."
Mass grading and structure excavation has already taken place for the bulk of the site, as well as foundation underdrain, plant drain and force main relocations. Roughly 220,000 cubic yards of dirt will be moved between excavation and backfill.
Equipment being used on the project ranges from skid steers to large excavators, including a Cat 352.
On several of the excavators and dozers, GPS machine controls are used to facilitate the speed and accuracy of mass grading operations. A 65-ton rough-terrain and 90-ton rough-terrain crane are currently on site, along with two tower cranes.
As for the effect of weather on construction, said Moran, "It has been an unseasonably cold and wet winter, which has impacted much of the concrete and underground work. The team has done a great job managing these challenges and continues to maintain the overall project schedule."
The project is currently on track to be completed by 2025. Despite the many tasks that lie ahead, Moran is pleased to play a role in such an important undertaking.
"It's extremely rewarding to be part of the team to increase the plant flow for today's needs, along with creating solutions for future expansion. With several of our craft and staff members living in the Sioux Falls area, having a highly functioning treatment plant is important for all of us." CEG
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