Marshalltown, Iowa

Water Treatment Plant

  • Client Marshalltown Water Works
  • Type Water
  • Services Facility Plan, Design, Construction
  • Construction Cost $6.9 million
  • Project Manager Lance J. Aldrich, P.E., BCEE


A founding partner of FOX Engineering, Dave Fox was responsible for the 1977 design and construction of the original 10 million-gallon-day (MGD) water treatment plant in Marshalltown. In 1997 water demands were increasing rapidly; production at the lime softening plant was approaching capacity, and many components needed to be replaced or upgraded.

Major improvements in 1997 included rehabilitated solids contact clarifiers, filters with new media and air wash systems, and new aerators, high service pumps, and SCADA system. A project in 1999 took the plant from 10 to 12 MGD, providing additional needed capacity for a growing community. The project included much needed repair and replacement of key equipment in the 20-year-old plant.

The facility is now 39 years old and new demands for capacity are extensive. A $750 million Alliant Energy generating station began construction in 2015 and significantly increased the demand for water. Age and condition of equipment are additional factors in the utility’s decision to make changes.


FOX performed preliminary engineering, including concept plans and cost estimates. Alternatives developed for the utility board included expansion of the existing plant as well as construction of a new satellite treatment plant in a more strategic location. Work included water distribution modeling of the water system to estimate the impact on tower operation and system pressure.

New High Service Pumps

New slaker and contact basin

Construction is complete for the new 2 million-gallon ground storage reservoir with booster station, repair of a 1 million-gallon reservoir, rehabilitation of the softening contact clarifiers, new lime slakers, and a new 1.5 MW standby emergency generator. The project included rehabilitation of two existing high service pumps and a new control system.


The reservoir is designed so that it can serve as a chlorine contact tank and clearwell for a future plant relocation to that site. The booster station would then serve as a high service pump station. Redundancy and future needs are accounted for.

Looking North from the treatment plant to the new reservoir

As Alliant Energy finalized design of the new generating station, their water demands came into better focus with lower peak water demands than originally proposed.

By improving the reliability of the existing facility and increasing storage, the Water Works will be able to meet the demands of future economic development, their existing customers, and the new generating station.