Awards: ACEC Iowa Special Projects Grand Place Award; ACEC Iowa Engineering Excellence Grand Conceptor Award; ACEC National Recognition Award
To accommodate rapid urbanization in the early 1900s, the historic Bee Branch Creek was enclosed in a 20-foot-wide stone storm sewer. However, as the area continued to expand, capacity deficiencies developed in this sewer, resulting in severe flooding of more than 1,100 residential and commercial properties within the city. In 2008, the City of Dubuque opted to remove the storm sewer and restore the Bee Branch Creek to an open channel. Our team was selected to design these improvements and prepare final plans and specifications. After updating the hydrologic and hydraulic models, a naturalized channel configuration and riparian area was developed to integrate with a variety of adjacent land uses.
Key elements of the $100 million construction project include more than 400,000 CY of excavation to create 4,500 LF of open channel waterway and dredging of a 25-acre detention basin. The majority of this material was used to fill an adjacent surplus detention area, thus creating a 6-acre redevelopment parcel and contributing to a $7.5 million reduction in project costs. Structural elements include four vehicle bridges and three overlook structures. A trenchless culvert crossing including six 8-foot diameter steel pipes, will be constructed through the Canadian Pacific Railway yard to maximize flow through the system.
The new open channel accommodates a spring-fed base flow that will be capable of supporting a healthy stream ecosystem. In order to preserve the health of this system, a number of sustainable water quality improvements were incorporated, including the installation of 2,500 LF of pervious roadway, 50 pervious parking stalls, four hydrodynamic stormwater separators, and five bioinfiltration basins. To preserve the history of the Bee Branch Channel, portions of the existing stone storm sewer were salvaged and reused to construct channel bank areas and other adjacent features.
The channel corridor provides linear community space that encompasses an extension of the regional Heritage Trail, a pedestrian bridge, information/educational kiosks, an amphitheater, orchard, benches, lighting, and more than 1,000 new trees.Back to Project Gallery