2026 WATER & WASTEWATER AWARDS

Water and Wastewater Grand Place Award  (1st Place in Category)Firm: HR Green, Inc

Client/Owner :Des Moines Metropolitan Reclamation Authority
Project: WRA Birdland Pump Station Improvements

The City of Des Moines previously owned and operated the old Birdland Pump Station (BPS) constructed in 1964, which is located adjacent to the Des Moines River and serves a combined sewer system. The BPS did not have the capacity to handle peak combined sewer flows, resulting in sewer overflows during wet weather. Elimination of this combined sewer overflow required an increase in pumping and conveyance capacity exceeding that of the existing BPS. The WRA agreed to construct a new BPS to handle peak flows while eliminating the overflow per a DNR Consent Decree.

HR Green was retained by the WRA to provide engineering services (design, bidding, and construction phases) for the project improvements. HR Green started with the conceptual design of several improvement alternatives, including reusing the existing BPS vs. constructing a completely new pump station. To establish design flow rates during wet weather, HR Green established a hydraulic model that was calibrated based on existing flow meter data and rainfall data. Additionally, HR Green worked with a subconsultant to provide a condition assessment of the existing 24-inch cast iron force main that serves the existing BPS. The condition assessment was completed using a highly sensitive acoustical tool that traveled through the pipeline collecting information to identify leaks and air pockets which are obvious areas of potential concern.

The alternative of reusing the existing BPS was ruled out due to the inadequate size of the wet well and dry well. The selected alternative included replacement of the existing BPS with a new facility. Screens were included to remove large debris from the influent flow stream that could potentially damage the pumps. The mechanical bar screens discharge into a roll-off dumpster located at grade for access. Post-screening, the wastewater flows into a common channel before being routed into individual pump wet wells compliant with the Hydraulic Institute Confined Wet Well design. The pump arrangement includes four  pumps overall, two normal duty (70 hp), and two wet weather duty (420 hp) pumps that provide a total capacity of 25 mgd. Due to the extreme peaking factors, the normal duty pumps convey flow into a new 18-inch force main while the wet weather pumps convey flow into the existing 24-inch force main. The project included extensive site improvements to protect the new pump station from river flooding. The pump station aesthetics was captured with input from local residents to match the neighborhood architecture and includes odor control to commercial and residential properties. For facility longevity, a surge analysis was conducted to protect the piping system from transient pressures conditions, with the recommended design incorporating surge relief valves and strategically located combination air valves. To maintain compliance, the design included a comprehensive construction sequence to minimize disruption to surrounding residents, allow the existing pump station to operate throughout construction, and maintain feasibility of construction on a very limited site footprint adjacent to the river. The project involved extensive permitting coordination with the Iowa DNR, US Army Corps of Engineers,
and City of Des Moines.

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