Update: Water Treatment Plant Improvements – Washington, Iowa

Originally constructed in 1924, this plant underwent its last major expansion and upgrade in 1992 with the installation of Electrodialysis Reversal (EDR) treatment systems. The EDR began to present the city with many operational and maintenance issues. Due to age, it had become very difficult to find replacement parts and the finished water quality had been significantly reduced. Additionally, the 1924 building which housed the city’s high service pumps and chemical feed systems had several structural issues that made rehabilitation cost-prohibitive.

New reverse osmosis skids

View of the new RO skids looking west. In view are the high-pressure feed pumps and cartridge filter housings.

In 2013, FOX completed a Facility Plan to evaluate various options for improvements to the City’s water supply, treatment, storage, and distribution system. The report recommended, among other things, replacement of the aging EDR systems with Reverse Osmosis (RO) membrane treatment. It also recommended demolition of the 1924 building and construction of an addition to the 1992 treatment building to house the new RO treatment systems, high service pumps, and chemical storage and feed systems.

In 2015, an on-site pilot study was conducted to confirm that RO treatment was a viable treatment alternative. The pilot also provided the data necessary to design the full-scale RO treatment system.

Bag filter housings which are located upstream of the RO units

The FOX team began design of the improvements in 2016. The new RO treatment plant was designed to meet the city’s anticipated water demands over the next 20 years, with a peak day capacity of 1.52 MGD, to serve a population of approximately 8,275 people.

FOX worked closely with city staff to develop a design that allowed phasing of the construction activities so that existing treatment systems remained in service until the new treatment systems were operational.

Construction of the improvements began in August 2017 and the new RO treatment systems went online in late June 2018. Improvements to the treatment plant site and renovations to the existing laboratory, office, and garage spaces will continue through spring 2019. Check back for the final results!

New high-pressure pumps

These things take time!

2011 Water distribution system is modeled

2013 Facility Plan is developed for supply, treatment, storage, distribution

2015 On-site pilot study confirms RO treatment is viable

2016 Design begins for new WTP

2017 Construction begins

2018 (June) New RO systems go online

2019 Expected completion for final renovations of building and site


FOX Engineering is an environmental engineering firm based in Ames, Iowa. We specialize in water and wastewater solutions for our diverse municipal and industrial clients. Our work varies in size and scope and can be found throughout the Midwest and beyond.