North Liberty: A Rapidly Growing City Takes Steps to Improve Its Water System and Plan for the Future

Phase I, Division I – Treatment Plant Improvements

North Liberty’s plant was constructed in the late 1970s and expanded in 2001. Due to significantly higher than anticipated population growth, water demands quickly reached the capacity of the existing facility.

To meet current and future demands, expansion of the water treatment plant was necessary; however, due to its location in a residential neighborhood, space for expanding the current plant was limited.  Additionally, the City needed a solution that would allow them to easily expand their treatment plant in the future to accommodate their fast-growing population.

Nanofiltration membranes being prepared for installation in the membrane pressure vessels

In 2013, FOX Engineering completed a Facility Plan that evaluated various options for expanding or replacing the plant. The report concluded that building a new membrane filtration plant at a new location was the most cost-effective solution.

The report also recommended constructing the new plant in phases so that excess treatment capacity was not constructed all at one time thus minimizing the financial impact on existing users.

In 2014, an on-site pilot study was conducted to confirm that nanofiltration membranes were a viable treatment alternative and to determine design requirements for the full-scale system. In 2015, the design team, led by FOX Engineering, began design of the Phase I Water System Improvements which included design of the new nanofiltration plant, new water supply wells, raw water mains and a ground storage tank. The Phase I Water Treatment Plant was designed to meet demands over the next 10 years, with a peak day capacity of 3.0 MGD, to serve a population of approximately 28,940 people.

Nanofiltration equipment installed

Throughout the design process, the need for easy expansion to accommodate the City’s population growth was always kept in mind. The three nanofiltration skids were specifically designed to allow the capacity of the skids to be easily expanded in the future and space was allocated in the building for the addition of two future NF skids.  Space was also allocated for an additional high service pump and chemical storage was also provided.

The result? North Liberty is capable of doubling its water treatment capacity to 6.0 MGD without the need to increase the building footprint.

The new Nanofiltration Water Treatment Plant, which is a part of the approximately $20 million Phase I Water System Improvements, went online in late May 2018.

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.