City provides basics of Brandon water system

Get up-to-speed on the basics of Brandon’s water system before heading over to the citywide public meeting at 6 p.m. Oct. 10 at the Brandon Golf Course. Information was compiled by Stockwell Engineering and supplied to the public at the Sept. 25 city council meeting. 

Aquifers

The city currently draws water from two aquifers, the Big Sioux and the Split Rock Creek. 

The Big Sioux aquifer is shallow and is primarily recharged by the Big Sioux River. Prior to construction of the treatment facility, the city supplied nearly all of its water from the Big Sioux wells in Aspen Park. Well 1 is currently the only well still in use, supplying approximately 150 gallons per minute (GPM). The city has water rights to develop an additional 1,250 gpm capacity in this aquifer, and has explored for additional supplies within the aquifer, encountering several challenges. First, test wells were unable to provide sufficient capacity due to extensive clay, which restricts. Second, the aquifer is vulnerable to contamination from many sources including farm runoff, abandoned fuel tanks, and private irrigation wells.

The Split Rock Creek aquifer lies below the Big Sioux aquifer and are separated by a layer of shale, which prevents water from moving between the aquifers. Wells 3, 6 and 7 are drilled into this aquifer. Well 3 currently supplies approximately 700 gpm; well 6 supplies about 1,500 gpm; and well 7 will be able to supply 1,200 gpm. The city has water rights to develop an additional 700 gpm of capacity in this aquifer.

Studies indicate the city could construct a high-capacity well approximately one mile east of the Bethany campus. Conservative estimates indicate the Split Rock Creek aquifer has the capability to yield 5 million gallons per day. Currently, there is approximately 8 million gallons per day of water rights allocated to various users. This suggests the aquifer is near capacity, however, large users are required to report their usage and much of this water is not currently being used. The city should prioritize additional water supplies in the Big Sioux aquifer.

The Sioux Quartzite aquifer lies below the Split Rock Creek aquifer and consists of solid bedrock. It is possible to obtain water from large fractures within the rock, however, fractures are localized and typically low capacity. Exploring this aquifer is difficult to drill, expensive and unlikely to yield a significant source of water.

Well 3 is located east of Splitrock Boulevard near Pizza Ranch. The well feeds directly into the distribution system and is not filtered to remove iron and manganese which presents taste and color issues. The water is disinfected and considered safe to drink and is only used in emergency and high flow situations. The city has considered connecting well 3 to the treatment plant, however, the location and capacity of the well makes it difficult to justify the cost.

Well 7 and radium: In the 1990s, the city of Sioux Falls evaluated locations for hig-capacity wells within the Split Rock Creek aquifer. One prime location was the existing well 7. In October of 1995, the city of Sioux Falls constructed well 7 and performed a pumping test to determine capacity. During the pumping test, the well tested positive for radium and gross alpha radiation, so Sioux Falls never utilized well 7. This was likely due to the cost of installing miles of pipeline required to connect the well to their system. Sioux Falls later sold the well to the city of Brandon.

Several alternatives were considered by city leaders and engineers before well 7 was selected as a water supply. Ultimately, limited capacity, water quality issues and land acquisition issues led to well 7 as a water supply. Three prime locations for additional wells within the Split Rock Creek aquifer have been identified. The first location is the existing well 7. The second is near McHardy Park, where the well tested positive for gasoline, and the third location is approximately one mile east of the Bethany campus. The city attempted to purchase land east of the senior living facility but was unable to reach a purchase agreement.

The city purchased well 7 knowing treatment would be required for radium and gross alpha, as rising levels of both in well 6 indicates treatment is inevitable. Radium and gross alpha naturally occurs in rock deposits and is relatively common and concentration typically tends to drift over time.

Well 8: The 2012 water study recommended rehabilitating well 6 to restore capacity of the well. However, during design discussions, concerns were shared about an emergency water supply should well 6 fail. The supply from well 3 does not have enough emergency capacity to support Brandon’s ongoing population growth. A proposal has been made to drill well 8 to replace well 6, which would remain as an emergency supply if well 8 fails. Wells 8 and 6 cannot be operated at the same time because they are located too close together, which would cause interference.

Rural water: Two rural water systems - Lewis and Clark Rural Water System and Minnehaha Community Water Corporation - are capable of supplying water to the city of Brandon. Both present challenges, including legal agreements, pressure differences, pipeline capacity and water qualities.

Water from LCRWS has been allocated to communities that bought into the system. In 1993, the city of Brandon opted not to buy into the system. Due to Brandon’s explosive population growth in the 1990s, it is likely the city would not have purchased enough capacity to supply the current population. 

Today, water is available on a temporary basis, however, the city has no guaranteed right to that water for future use. As surrounding communities continue to grow and use their reserved supply, Brandon would lose access to this water. The city would also be responsible for any infrastructure to connect to this system and would eventually lose all investment in the infrastructure.

Water from MCWC is available and there are ongoing discussions on connecting into the water system. However, it does not appear MCWC can supply the anticipated 4-5 million gallons of water needed by 2037. Some combination of city water and MCWC is a possible alternative.