Ames Water Treatment Plant

Looking west at the new Ames water treatment plant


The city of Ames began municipal water service to its residents in 1891; the first treatment efforts followed in 1924. Treatment processes evolved from simple iron removal to more sophisticated lime softening and disinfection, always with a focus on providing the best quality water possible to its customers.

The most recent plant expansion occurred in 1988. By 2008, city officials had become increasingly concerned about the aging infrastructure, some of which had been in service since the 1920s, and the utility’s ability to continue providing the necessary services and quality of water expected by its growing customer base. Seasonal water demands threatened to exceed treatment capacity, and increasingly stringent Federal and State drinking water regulations required expanded resource commitments to ensure compliance.

A view of the old plant (top left) and new plant location (bottom right).


Needs Assessment and Concept Development Phase

In 2008, city staff selected FOX Engineering to assist in developing and implementing a long-term solution to improve its water treatment facilities. To begin, FOX assembled a team of water plant experts – engineers, architects, and operations specialists – from within its own Iowa-based firm, and HDR Engineering of Omaha and Barr Engineering of Minneapolis.

After 10 months of concentrated evaluation and analysis, the FOX team completed its initial Water Treatment Plant Infrastructure and Capacity Needs Assessment, which comprised the conceptual development phase of the rehabilitation, replacement, and expansion of the water treatment facilities.

Aerators in action

Aerators and lime silos on west side of plant

That effort examined future treatment capacity based on city and consultant expectations for growth in residential, commercial, and industrial water demands. Limitations due to the physical conditions and capacity of the existing plant were carefully investigated and the feasibility of a rehabilitated and expanded water plant was evaluated along with development of a completely new treatment facility at a nearby site. Planning efforts included consideration of various proven and innovative technologies, such as lime softening vs. membrane softening.

Lime slaking system

During the conceptual development phase, the FOX team assisted city staff in seeking involvement from its concept advisory team – a group assembled to obtain operations, maintenance, management, and customer/citizen perspectives. Through a series of regularly scheduled meetings and workshops, the FOX team formulated, communicated, and refined the conceptual design for the treatment facilities.

The initial needs assessment enabled the FOX team to recommend, and city officials to select, a plan for constructing a completely new 15-mgd lime-softening water treatment facility to be located on a new, nearby site.

View across the three solids contact basins used for softening

The selected concept would achieve additional cost-efficiencies through optimal use of existing water source, storage, pumping, and residual management facilities with useful remaining life and value. The new facilities could be expected to provide upgraded efficiency and performance for the project’s 20-year planning period and the necessary infrastructure to serve the city for many decades beyond.

Staff and engineers discuss the softening process

Pre-Design Phase

With concept selected, planning and design proceeded through a 20-month-long pre-design phase that built upon the conceptual design framework and more firmly established engineering aspects ranging from treatment process and hydraulic design details, to building space utilization and floor plan layouts, to site planning considerations.

This effort examined the various permits and approval procedures involved in securing the many federal, state, and local agency authorizations. Monthly meetings and special workshops were conducted with city staff to define and articulate FOX team recommendations and client preferences across a wide range of specifics for the facilities design including process technologies, equipment selection, construction materials, building systems, control systems, and site development.

Throughout and following the pre-design phase, the city was involved in negotiations for acquisition of the 43-acre future treatment plant site, which was owned by the federal government.

The pipe gallery between solids contact units and the filters

Design Phase

Following a value engineering review of the Pre-design documents, the design phase of the project commenced in October 2012 and was completed in May 2014, with the FOX design team finalizing and submitting to the city all final design documents, including engineering drawings, construction specifications, and construction contract documents. The comprehensive, multi-discipline design encompassed all architectural, structural, mechanical, civil, process, and electrical engineering aspects of the new facilities.

Filter in operation

During the design phase, the FOX team collaborated with city staff to give special attention to decision-making that would help contain construction cost budgets while achieving maximum functional value of the facilities. Such efforts were helpful for city management and elected officials as they responsibly controlled capital expenditures for the $70 million total project.

During design, the FOX team met regularly with city staff to communicate project progress and solicit input regarding design choices. Obtaining their input was critical in developing a facility that would meet multiple stakeholder expectations.

A view from above the high service pumps

Balancing competing internal needs against potential costs and the need to contain customers’ water rates is always a demanding effort and this project was no exception. A special objective was to achieve LEED (Leadership in Energy & Environmental Design) certification of the facility, which qualified the project for $6.5 million in forgivable loans through the State Revolving Loan Fund.

Construction Phase

The city received construction bids in August 2014. The low bid for construction of the treatment plant was $52.5 million, submitted by Knutson Construction. The low bid for underground piping to connect the new water plant site was $3.2 million, submitted by S. M. Hentges & Sons. Groundbreaking ceremonies were held October 16, 2014; construction activities commenced in November, and were underway for the next 36 months.


Water Plant Commissioning/Start-Up

The new lime softening facility is made up of numerous processes – non-mechanical aeration, solids contact softening/clarification, recarbonation, dual-media filtration, disinfection, high-service pumping, and lime residuals management. Chemical systems include: lime feed using batch-style, continuous-loop slakers, carbonic acid generation with pressure-adsorption carbon dioxide systems, simplified granular fluoride mixing and dosing, phosphate stabilizer application, and liquid flocculent (polymer) use.

Lance Aldrich and Lyle Hammes in the control room

The new treatment plant is located on a 43-acre site previously used by the USDA in its research programs.  The proximity of the new site to the existing treatment facilities will allow integration of existing high-service pumping, finished water storage, and lime sludge facilities into the new design to achieve additional cost efficiencies.

The plant was subjected to a series of commissioning tests during June and July 2017, to prove system performance and fine tune operations and controls. The facilities were placed into full-time service on July 27, 2017. The success of the project was capped with a public open house in August 2017 that drew more than 1,500 residents to view their new facilities and to learn firsthand of the city’s efforts in assuring them quality water into the future.

And, it’s water!!

“The way it was designed, when you walk through, you realize this is not a throwaway facility. This is not a building that’s designed to be here for twenty years, and then get ripped down and replaced by something else. This is going to be the home of drinking water treatment for the city of Ames for, I would hazard a guess, a hundred years. This is really going to be a landmark piece of infrastructure for the Ames community.”

John Dunn, P.E., MBA

Director, Water & Pollution Control for the City of Ames

Plant entrance from 13th Street

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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.