Water and Pollution Control Department

Construction & Project Updates

Water Treatment Plant Expansion Project
(Last Updated: April 9, 2008)

PROJECT BACKGROUND

The Ames Water Treatment Plant (WTP) is a conventional lime-softening facility. Source water for the plant comes from 22 alluvial wells located in four well fields. The plant has a rated capacity of 12 million gallons per day (mgd). The utility has annual revenues of approximately $6.7 million.

The Ames water utility was formed in 1891. The existing water treatment plant was constructed in 1927 as a 2 mgd iron removal facility. In 1931, lime softening was added, and the plant capacity was increased to 3 mgd. Treatment capacity was doubled with a plant expansion in 1962. In 1971, the capacity was again increased, this time to 9 mgd with the addition of four new filters. In 1988, the plant was expanded yet again, going to the current 12 mgd with the construction of a new settling basin and rehabilitation of the existing filters. The WTP currently maintains three ground storage reservoirs (7.75 mg), three elevated storage tanks (4 mg), and a booster pump station. In addition, the WTP controls a booster pump station and an elevated tank for a local industry.

A number of treatment units at the WTP are showing signs of deterioration. Many have undergone structural rehabilitations in the past 30 years, and major repairs or outright replacements are necessary in order to maintain the WTP’s existing capacity. The plant has limited redundancy for several treatment units; as a result, the replacement of some components while keeping the plant operational may be problematic.

During the summer of 2007, a new single-day peak demand record was set at 10.22 mgd, and a new peak three-day average was set at 9.81 mgd. The peak three-day average is 82 percent of the plant’s 12 mgd rated capacity. Using the rate of growth of the peak three-day average over the past five years and extrapolating forward, it is conceivable that the plant capacity could be reached as soon as 2012.

As a result of the growing summer peaks, the utility initiated a sustained water conservation program in 2007. The focus of the first year’s efforts was to simply raise public awareness about the way water is being used and to promote conservation by appealing to the community’s social consciousness. The City  its water rate structure from a flat rate to a seasonal inclined-block structure. Options for mandatory conservation, such as alternate-day watering, will also be presented to the Ames City Council for consideration.

While conservation has numerous benefits and will continue to be a priority for the Ames water utility, the trends of summer peak usage suggest that planning for additional capacity needs to begin immediately. Due to the age and condition of the existing facility, a comprehensive assessment of the existing infrastructure is also necessary.  The Infrastructure and Capacity Needs Assessment is the initial concept development phase for an anticipated Water Treatment Plant rehabilitation, replacement, and/or expansion. This first phase will determine the overall direction for the future of the Water Treatment Plant. Subsequent phases will implement the conclusions reached in this Needs Assessment phase.
 

CURRENT STATUS

On April 9, 2008, an open Request for Statements of Interest was released.  Any firm who believes they have the necessary expertise and experience is invited to submit a Statement of Interest.  Statements are due by 4:00 pm CDT on May 2, 2008.
 

PROJECT TIMELINE