The City of Dubuque’s water system is comprised of nine pressure zones located within the Mississippi River Valley and adjacent bluffs. The northern section of Pressure Zone 2 has low pressure. Zone 2 serves customers located on a river bluff that varies significantly in elevation. As development has expanded to the north to higher elevations, pressures have decreased. A previous study recommended raising pressures by constructing a taller water tower located at the intersection of Roosevelt Street and Sky Blue Drive. The recommendation included installing 16 Pressure Reducing Valves (PRV) to protect infrastructure from high pressures.
As part of the project, the City requested a hydraulic model of their entire distribution system. The main purpose of the model was to verify the recommendations of previous reports before proceeding with the design of the Roosevelt Street Tower. IIW built a city-wide hydraulic model and ran scenarios based on recommendations from previous studies. Using the model, the IIW team was able to reduce the number of PRVs from 16 to 2.
After the modeling, IIW designed the water tower, distribution piping, and two pressure reducing valve stations. One challenge during design was locating the PRV stations. The areas where the PRV stations were to be located had narrow right-of-ways. Working closely with water operations and maintenance staff, IIW was able to locate one PRV station with the entrance outside of the roadway and the equipment removal hatch within the roadway. The other PRV was located in a piece of a gravel driveway owned by the City. The locations will provide easier and safer access for maintenance rather than being located in the middle of the road.
Another important part of this project has been community engagement since the new tower is being located in a developed residential area. IIW and City Water Staff held an open house for the public to keep them informed. A rendered 3D animation of the proposed tower provided citizens a preview of how the water tower will look once completed.
The project is currently in the bid phase and is on schedule to be completed by November 2020.