|
The City of Stevens Point serves a population of 25,000. In 2005, the City adopted a comprehensive land use plan that doubled its sewer service area and extended sewer service to a large, unsewered area to the east.
The City faced several challenges in developing a plan to serve the extended area since projected flows from this area exceeded the capacity of the existing lift station. The City also owned an abandoned water main that it hoped to reuse for this project.
To alleviate the issues with the lift station, Donohue designed a new lift station on the same site as the existing station, which, in addition to providing the capacity to serve the east side of the city, also provided needed redundancy. Concurrently, the City was having another consultant design upgrades to the existing station. Foreseeing problems with two contractors on one small site, Donohue offered to coordinate bid documents with the other consultant. The City was able to award a construction contract to one contractor for both projects, which presented significant cost savings.
After conducting research, the City determined the water main could be converted to a force main by re-lining the main with a vinyl ester resin system with woven glass fiber tube. This material is suitable for wastewater, satisfies pressure requirements, minimizes “shrink”, and allows the City to self-perform repairs in the future. Donohue proceeded with the design of the liner and water main conversion. Ground Penetrating Radar (GPR) and sewer televising were used to determine the condition, location, and elevation of existing water main.
GPR identified two problem areas – one pipe segment was located within a cemetery and another was located within a busy railroad right-of-way. Provisions were added to the construction documents to line the pipe without allowing any equipment or excavations inside the cemetery. The segment within the railroad right-of-way was abandoned and a new segment was constructed using horizontal directional drilling.
Between the innovative reuse of the existing water main and the construction and contract coordination with the lift station, the City was able to realize substantial savings over traditional design and construction methods. These solutions were also considerably “greener” and minimized construction-related disruptions for residents.
|
