Washington, IA

Water Treatment Plant Improvements

  • Client City of Washington
  • Type Water
  • Services Facility Plan, Treatment Design
  • Construction Cost $4,943,000
  • Project Manager Steve Troyer, PE, BCEE
  • Project Engineer Matthew Hawes, PE


The city’s existing water treatment facility, which underwent its last major expansion in 1992, utilized an electrodialysis reversal (EDR) treatment process.  Portions of the facility that housed the city’s high service pump dated back to 1924. While the EDR systems provided the city with many years of reliable service, aging equipment and lack of available replacement parts provided the city with many operational and maintenance challenges.  Additionally, the 1924-era building had significant structural issues which made rehabilitating that portion of the facility cost prohibitive.

FOX Engineering was retained in 2012 to conduct a facility plan for the entire water system – including supply, treatment, storage, and distribution – to identify and prioritize improvements necessary to maintain a reliable supply of water at the desired water quality. The report identified, among other things, that the existing EDR systems be replaced with new Reverse Osmosis (RO) membrane treatment.

In 2015, an on-site pilot study was conducted to confirm that RO treatment was a viable treatment alternative and to obtain data necessary to design the full-scale RO treatment system. In 2016, the team led by FOX began design.  A major challenge in implementing upgrades to the existing plant was maintaining operation of the treatment and pumping facilities while constructing and implementing the improvements.


To ensure that the city was able to operate its existing treatment and pumping facilities during construction of the improvements, 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 and chemical feed systems were fully operational. To accomplish this, the design included a building addition to the 1992 building to house the new RO treatment systems, chemical feed systems and high service pumps. Temporary measures were utilized during construction to allow the new treatment facilities to operate while the old treatment facilities in the 1992 and 1924 buildings were demolished. After the new facilities were operational, the 1992 treatment building was rehabilitated to include renovated laboratory and office spaces, garage and storage space while the 1924 building was demolished.

RO Treatment System Skids

RO Low Service Boost Pumps


The city received construction bids in June 2017 with the low bid of $4.943 million from Tricon Construction Group of Cedar Rapids, Iowa. Construction began in August 2017 and the new RO systems went into full operation in June 2018.  The project was substantially completed in February 2019 with final completion occurring in June 2019.  The water treatment plant improvements have allowed the city to provide its customers with a higher quality of water than was achievable with the old EDR systems. The new RO treatment plant is designed to meet a peak day capacity of 1.52 MGD, for a population of approximately 8,275 people, and is expected to reliably meet the city’s anticipated water demands over the next 20 years.

High Service pumps