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Ames Water Treatment Plant – Construction

Seasonal water demands threatened to exceed the City’s treatment capacity, and it was becoming more difficult to maintain the aging facilities, some of which had been in service since the 1920s. In addition, increasingly stringent Federal and State drinking water regulations required expanded resource commitments to ensure compliance.

(Left to right) FOX engineers, Lance Aldrich, P.E., BCEE; and John Washington, P.E., construction manager

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. 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.

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.

The new site contained abandoned buildings, concrete slabs, and utilities – some of which were buried and unknown prior to starting construction. The site included many existing features such as mature trees and natural areas which were, as practical, incorporated into the design and preserved. Building elevation was a major concern relative to the existing infrastructure and treatment facilities remaining in service. The Skunk River separated the new facility from the existing facility; connecting the two facilities required directional drilling under the river for two 24-inch raw water mains, two 24-inch finished water mains, two 6-inch lime sludge force mains, and a large conduit containing several inner-conduits for fiber optic communication.

Building construction started with a deep excavation followed by massive concrete and rebar foundation. The general contractor utilized a tower crane sitting on its own massive foundation to quickly and efficiently distribute materials, formwork, and tools to the building. Cast in place (CIP) reinforced concrete walls were poured on top of the foundation. CIP reinforced concrete decks were poured on top of the walls. Various concrete tanks including solids contact basins, a recarbonation basin, filter cells, a backwash recovery basin, and clearwells were integrated in the CIP concrete walls and decks. Precast concrete wall panels and a precast concrete “double tee” roof completed the structural components of the new facility.

Making sure one phase of work was completed correctly before covering it with another phase of work was crucial to making sure the project stayed on track and didn’t require significant rework.

The water treatment plant includes numerous pieces of equipment such as pumps, blowers, lime equipment, aerators, and solids contact units to name a few; most requiring electrical connections, electrical gear, and controls to function. The various tanks and equipment also require interconnecting piping. Because its size restricted normal entry to the building, some of the piping and equipment had to be installed prior to the roof being put in place.

The main building contains the water treatment plant, but also houses administration spaces including engineering offices and library, staff training areas, locker rooms, maintenance areas and public education spaces.

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.

1,500 tons of rebar

17,000 cubic yards of concrete

Pipe: > 20,000 lineal feet

Electrical wire > 850,000 lineal feet.

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.

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.