Water Quality Upgrades Bring Big Benefits to Brandon and the Big Sioux River
Residents of Brandon, South Dakota can expect to see improved water quality in their homes and the Big Sioux River thanks to two water improvement projects implemented by the City of Brandon. In August, we received a comprehensive tour of the new Water Treatment Plant Expansion from Donovan Carpenter, Public Works Foreman, and Tami Jansma, City Engineer. Tami also joined us at Big Sioux Recreation Area to give an overview of the newly constructed Big Sioux Drainage Structure Repair Project. Read on to learn more about both of these noteworthy undertakings.
Water Treatment Plant Expansion Project
Approximately seven years ago, the City of Brandon initiated a feasibility study to assess water usage and projected development growth until 2070. Based on the study's results, the City hired AE2S, an engineering firm, to design and oversee the Water Treatment Plant Expansion Project. The project had two primary purposes: 1) Double the size of the water treatment plant to increase maximum treatment capacity from 2,000 gallons per minute to 4,000 gallons per minute and 2) Install a reverse osmosis (RO) treatment system to reduce water hardness from 400 mg/L to 200 mg/L, a range similar to water from the City of Sioux Falls and the Minnehaha Community Water Corporation.
The current expansion project began in 2022 and is scheduled for completion in 2026. Along with adding on to the existing plant, the project will also include updates to the old system. The water treatment plant, located in Aspen Park, was originally constructed in 1999. It is strategically located near underground wells in the Split Rock Creek Aquifer and the Big Sioux Aquifer. All of Brandon's water is pulled from underground wells, primarily from the Split Rock Creek Aquifer. Unlike other towns in the region, Brandon is not connected to the Lewis and Clark Regional Water System, a decision that was made by the Brandon City Council in 1993. Therefore, the City must pull and treat all of the water needed for the cities of Brandon and Corson. At this time, there are no plans to build a wastewater treatment plant in Brandon, and all of the city's wastewater will continue to be sent to the City of Sioux Falls Water Reclamation Facility.
The amount of water pulled per day in Brandon varies based on the season. During the winter, approximately 700,000 gallons of water are pulled per day. This number increases drastically during the summer to between 1.6 million and 1.7 million gallons per day, largely due to residents and businesses watering their lawns. A few years ago, before water restrictions were enforced, the city experienced a peak daily water usage of 2.8 million gallons.
As the City of Brandon continues to grow and use more water, it is necessary to expand the treatment facility to accommodate the projected growth trends. In total, the Water Treatment Plant Expansion Project cost approximately $25,000,000. Of that, about $8,000,000 was paid for through funds from the American Rescue Plan Act (ARPA), which entirely funded the reverse osmosis portion of the project. The additional $17,000,000 is financed through a 30-year bond and funded by a monthly surcharge on water users' utility bills.
RO Treatment System
The new state-of-the-art reverse osmosis treatment system is one of only a few in this region. RO treatment removes dissolved minerals and contaminants in the water that cannot be removed through regular water filtration systems. For years, one of the main complaints from Brandon residents was the hardness of the water, as it was about twice as hard as the water in Sioux Falls. Consequently, many residents installed their own water softeners or in-home RO systems to combat this issue. The City addressed the community's complaints and ensured that the treatment plant expansion included a method to reduce water hardness. Once all of the final tweaks have been made, the new large-scale RO system should decrease the city's water hardness by half. Not only will Brandon residents see a reduction in calcium buildup on appliances and fixtures, but they will also see a decrease in the costs associated with installing or operating in-home water softeners and RO systems.
Although RO systems are great at reducing water hardness, the resulting demineralized, low-alkalinity water can be very corrosive to metal pipes. As a result, the final product sent to Brandon residents and businesses will be a mix of 50% RO-treated water and 50% conventionally treated water. All untreated water entering the plant will undergo the original filter treatment process, which has been in place since 1999. Approximately 50% of the conventionally treated water will then be sent for additional treatment in the RO system. The other 50% will meet back up with the treated RO water in a pipe, where chlorine and fluorides are added back in before the water exits the building.
Across the board, this project is a net benefit for the City of Brandon and the Big Sioux River Watershed. By implementing a city-wide RO system, there will be a reduced need for in-home water softeners, which consume high amounts of salt. Once salt has dissolved in water, it is challenging to remove and, therefore, is not removed at most municipal wastewater treatment plants. Unfortunately, this means that the salt from in-home water softeners is ending up in the Big Sioux River. Over time, chlorides turn freshwater saltier, harming aquatic ecosystems.
Additionally, in-home RO systems waste a significant amount of water, with a finished product of 25% RO water to 75% wastewater. The city's new RO system is significantly more efficient, with a finished product of 75% RO water to 25% wastewater. And best of all for the city, it means that Brandon can continue to grow and know that water is readily available. "Hopefully, it's a peace of mind that we do have water and we will have water and we can have continued growth," noted Tami Jansma, City Engineer.
Collapsed control structure on the Valley of the Giants Trail
Big Sioux Drainage Structure Repair Project
For the past several years, hikers on the Valley of the Giants Trail at Big Sioux Recreation Area have had to take an alternative route due to streambank erosion that destroyed a portion of the trail. The City of Brandon and South Dakota Game, Fish and Parks set out to fix that. For almost 50 years, a 540-foot-long black plastic pipe flowed underground from the nearby Parkview Boulevard neighborhood to the Big Sioux River, passing through the park along the way. Following a large flooding event in 2019, the pipe and concrete control structure collapsed, causing the flood waters to wash out a section of the trail. The quick and easy solution would have been to replace the plastic pipe with a concrete pipe and continue sending stormwater directly to the river. Tami Jansma, the Brandon City Engineer, wouldn't settle for that. The environmental impacts of sending dirty stormwater to the river needed to be considered.
After encountering almost two years' worth of permitting red tape, the City was finally approved to proceed. South Dakota Game, Fish and Parks helped to advocate for the proposal at the state level, as it would take place on state-owned land. Without their support, Jansma believes it is unlikely the project would have come to fruition. IDG Structural Engineering was hired to design and complete the $1,000,000 project, which was fully funded through general fund and sales tax dollars.
To begin, engineers studied aerial maps and determined that the original pipe did not follow the natural drainage channel. It was essential to Jansma that this issue be remedied in the master plan. When water follows a natural channel, it can slow down and soak into the soil, thereby reducing erosion, recharging groundwater resources, and filtering out contaminants before flowing into another waterbody.
On-the-ground work began at the neighborhood entrance to the park with the installation of a stormwater pipe and control structure, similar to a manhole. This structure acts as a capture basin, collecting all the garbage and sediment from the street during rain events. Every time the city receives over a quarter inch of rain, the Brandon Public Works Department is responsible for cleaning out the basin. "It is amazing how much garbage is in it. It's so nice that we're keeping all of that out of the river now," Jansma said.
New water control structure
After flowing through the control structure, the pipe continues for a short distance underground before emptying into the first of three rock-bottomed ponds, where water can begin to infiltrate into the soil. The first two ponds feature a water control structure that regulates the water level, forcing it to rise to a certain point before allowing it to flow to the next pond. These structures ensure that the water has time to slow down and infiltrate before moving on. The third pond leads to the natural flow path, where the now cleaner water empties into a small stream in the park next to the Big Sioux River.
The Big Sioux Drainage Structure Repair Project was completed in the fall of 2024. In addition to constructing a new drainage structure, the original plastic pipe was removed, and the Valley of the Giants Trail was restored. So far, there have been no issues with erosion, despite heavy rainfall events in 2025. A mix of native prairie species was planted over the new drainage area, allowing it to blend seamlessly into the natural environment. The next time you are hiking at Big Sioux Recreation Area, make sure to check out this unique stormwater improvement project!
