The Project includes an initial study and preliminary design phase scheduled for completion in 2015. This phase includes field investigation and surveying, closed circuit television (CCTV) inspection, and sewer smoke testing. Subsequent phases include design and construction of sewer improvements within the Project Area.
Much of the Project Area was originally developed with combined storm and sanitary sewer systems. Combined sewers were common until the early 20th century and were typically sized to carry three to five times the average dry weather flow. The combined sewers route the combined stormwater and sewage to the wastewater treatment facility most of the time. During large storm events, the volume of stormwater can exceed the capacity of the collection system and wastewater treatment facilities. Combined Sewer Overflow (CSO) structures have been installed in the combined collection system so that excess flow could be diverted to a stream or river to prevent sewer backups into homes or streets. The combined sewer flows for the majority of the Project Area are conveyed to the CSO structure located at 22nd Street and High Street. The remaining combined sewer flows, mostly north of Cottage Grove Avenue, are conveyed to the trunk gravity sewer at 15th Street and University Avenue.
The City of Des Moines has developed a Long Term Control Plan (LTCP) to meet the requirements from the Iowa Department of Natural Resources to eliminate CSOs and remove stormwater flows from the sanitary sewers. The Near West Side Sewer Separation Project is part of the LTCP.
This project will include construction of storm and sanitary sewer systems to reduce combined sewers in the Project Area. The City of Des Moines has included approximately $14.5 Million in their Capital Improvement Program (CIP) for improvements associated with this Project.
- Reduction of flow to the Wastewater Reclamation Facility
- Improvements in stormwater collection and conveyance
- Reduction of surface flooding, sewer backups and combined sewer overflows