ANKENY WASTEWATER TREATMENT FACILITIES
Ankeny, Iowa
Veenstra & Kimm, Inc. has worked with the City of Ankeny since the late 1960s on issues related to its wastewater treatment facility. In 1974 as the City of Ankeny was about to embank on designing a new treatment plant the Iowa Department of Natural Resources required the City of Ankeny to participate in a regionalization study. That study was originally intended to connect the City of Ankeny to the regional treatment facility by the early 1980s.

In 1976 the City of Ankeny constructed an interim 1 mgd treatment facility. By the early 1980s it was determined the City of Ankeny would not connect to the regional treatment facility. As a result, Veenstra & Kimm, Inc. developed a four phased improvement program to expand the treatment plant from 1 mgd to a peak capacity of nearly 26 mgd. Between 1986 and 2001 Veenstra & Kimm, Inc. designed four projects to upgrade and renovate the treatment plant. The treatment plant improvements increased the treatment plant from a effective capacity of less than 5,000 persons to nearly 37,000 persons. Ironically, after the completion of the fourth project the alternatives of regionalization became cost-effective for the City of Ankeny and the treatment facility will be retired from service by 2011.

As the City expanded its treatment process through the 1980s and 1990s the plant utilized a two-stage process including fixed media filters and activated sludge. The plant was designed to operate either with the treatment processes in parallel as a single stage plant or in series as a two-stage plant. By the mid-1990s the City determined it appropriate to complete the fourth phase of the treatment process that significantly expanded the activated sludge process. With these improvements the fixed media first-stage treatment units were taken out of normal service and left in standby mode. The fourth improvement phase included an expansion of the influent pump station and other energy improvements throughout the plant. One of the major elements of the fourth phase involved the installation of a new electrical service and switchgear and new standby power unit.

The project posed significant challenges to maintain service during construction. Even though the project posed significant challenges the project was completed without a single change order related to the original project. The only change order was a request by the City of Ankeny to add the modification to an existing building to the project.