Water & Wastewater

Water Treatment

Brookings obtains source water from a series of nine (9) groundwater wells located in two separate aquifers. The east wellfield has four (4) wells; the north wellfield has five (5). Both wellfields access groundwater from relatively shallow sand and gravel formations. BMU has a strong focus on protecting the drinking water source, also known as wellhead protection.

While Brookings has quality groundwater sources, the raw water pumped out of the ground still benefits from treatment to remove undesirable characteristics and improve water quality to the consumer. Specifically, BMU removes dissolved iron and manganese (which cause undesirable staining if not removed), and reduces the water hardness by approximately half the total hardness. Water treatment occurs at two different facilities, the East Water Plant, which can treat approximately 4 million gallons per day (MGD), and the North Water Plant, which can treat approximately 2.5 MGD. Both plants utilize lime softening as the primary treatment process.

The process of treating water is similar at both plants. The first step is aeration to remove hydrogen sulfide and to aid in the removal of iron and manganese. Following aeration, the water enters a contact basin where it is mixed with lime. The water chemistry reaction that occurs allows the minerals (including iron, manganese, and hardness) to settle to the bottom and be removed. The clarified water is removed from the surface of the basin and flows to gravity filters. The filters remove any remaining particles and provides final water clarification before delivery to the distribution system. In addition, chlorine is applied for disinfection and fluoride is added for tooth decay prevention, as required by the State.

Should you be interested in learning more about the water treatment process, BMU provides facility tours upon request; please contact us at 605-692-6325 for more information.

Water Distribution

Once treated, drinking water is stored either at reservoirs at the treatment plants or in elevated towers in the distribution system. Reservoirs at the treatments plants have a combined 4.5 million gallons (MG) of storage, and three elevated towers throughout the distribution system have a combined 1.75 MG of storage. The distribution system includes approximately 124 miles of water main, ranging in size from 1-inch to 20-inch. BMU also supplies water to the City of Aurora as well as two other smaller consecutive water systems both north and south of Brookings.

Wastewater Collection

Wastewater collection begins with water sent down the drain from homes and businesses throughout the community. Once an individual sewer service reaches the public (BMU) sewer main (typically in the adjacent street), it combines with wastewater flow from the community and continues downstream through a series of increasingly larger sewer pipes. Most of the wastewater flow is by gravity, flowing from higher elevation to lower elevation. In some areas, a lift station is required to allow flow to continue downstream.

The BMU wastewater collection system ranges in size from typical 8-inch diameter sewer mains up to 36-inch diameter sewer pipe at the lower end of the collection system. The collection system includes approximately 117 miles of sewer main. In addition, BMU operates five lift stations of various size and capacity throughout the collection system.

BMU maintains the wastewater collection system by periodically inspecting and cleaning the sewers when needed. The maintenance fleet includes a sewer inspection camera for remote visual inspection of the sewer, and two jetting and vacuuming trucks that allow cleaning of the sewer.

Wastewater Treatment

The Brookings wastewater treatment plant (WWTP) is located approximately 2 miles south of Brookings. The WWTP was originally constructed at this location in 1980, and went through a significant upgrade and expansion in 2013 to 2015. The WWTP has a firm hydraulic capacity (peak daily average) of 17 million gallons per day (MGD) and was sized based on the projected 2035 population predicted in a March 2012 Facility Plan document.

The WWTP is a mechanical treatment plant with the primary treatment provided by a biological activated sludge treatment process. This basically means organic material contained in the wastewater is treated (removed) by feeding it to microscopic organisms. The treatment process includes nitrification, which means ammonia is removed in the treatment process. In the future, the WWTP will be upgraded to include nutrient (nitrogen and phosphorus) removal.

Once at the WWTP, wastewater flows through a series of individual processes (unit processes), each with a different objective throughout the treatment process. The treatment process consists of two basic flow trains, 1) the liquid wastewater train which follows a drop of wastewater as it flow through the treatment process, and 2) the solids train follows partials removed from the wastewater to final disposal. A brief summary of the treatment processes are below:

All Incoming Flow

• Influent (incoming) flow measurement
• Pretreatment – Removal & disposal of inert material (rags, debris, sand, etc.)

Liquid Flow Train (Wastewater flowing through the process)

• Primary Treatment – Physical settling and partial removal of organic material
• Secondary Treatment – Aerobic biological breakdown of organic material
• Tertiary Treatment – Polishing and final removal of organic material
• Disinfection – Ultraviolet light disinfection to kill viruses & pathogens
• Re-areation - Ensures adequate dissolved oxygen required for aquatic life is present
• Discharge of treated wastewater effluent meeting NPDES permit limits to the Big Sioux River

Solid Flow Train (Solids removed from the process)

• Digestion – Anaerobic biological breakdown of solids collected throughout various processes
• Dewatering – Liquid removal from digested solids
• Beneficial Reuse – Nutrient land application of digested biosolids in accordance Biosolids Management Permit No. SDL023388

BMU operates a laboratory at the WWTP and tests daily for a number of permit-required treatment parameters to ensure permit compliance. BMU also partners with South Dakota State University (SDSU) Engineering Department to employ part-time Student Operators to assist with operation and laboratory work at the WWTP; this partnership provides an excellent opportunity for future engineers to obtain hands-on experience and reduces the number of full-time BMU staff required to operate the facility.

Should you be interested in learning more about the WWTP, BMU provides facility tours upon request; please contact us at 605-692-6325 for more information.

Industrial Pretreatment

Industries and businesses located or planning to locate in Brookings are required to comply with the local Sewer Use Rules and Regulations. The local pretreatment program was approved by the Environmental Protection Agency. If there are question about these regulations or you would like a copy of those regulations, please contact the Pretreatment Administrator at 605-693-3287.