Combined Sewer Overflows
INTRODUCTION
The City of Ottumwa has a combined storm and sanitary sewer system. Storm runoff and household sewage are collected and transported through the same pipe. When the system was constructed years ago, this is how sewer systems were commonly built.
When the system is overloaded, such as during a heavy rain, the sewer (both sanitary and stormwater) overflows directly into the Des Moines River. These discharges are called Combined Sewer Overflows (CSOs). The combined sewers also cause raw sewage to "backup" in basements. The City has recorded over 500 basement backups in the last 10 years.
The system does not meet current environmental regulatory standards and the City of Ottumwa is now required by the Iowa Department of Natural Resources to develop a sewer separation plan. The Iowa Department of Natural Resources (IDNR) has prohibited sewer extensions in the past and future restrictions threaten Ottumwa's growth and development.
In addition, reducing the number of CSOs will help reduce pollution occurring in the Des Moines River, as well as at our outdoor water park, "The Beach Ottumwa."
Finally, addressing the CSO problem will greatly reduce the incidence of raw sewage backups in resident's basements.
(The Iowa Department of Natural Resources regularly issues news releases about overflows and wastewater discharges around the state. Click here for DNR News.)
Combined Sewer Overflow at the Ottumwa Park Lagoon.
OTTUMWA'S SOLUTION
An initial study phase to investigate the sewer system to find deficiencies and aid in the design of a future separation project was completed in 2003.
The City Council has retained the services of Veenstra and Kimm, Inc., of West Des Moines, Iowa as a consulting engineering firm to design the first phase of the South Ottumwa Sewer Separation.
The City intends to proceed with separating the worst part of the system located south of the Des Moines River. This will eliminate four of nine CSOs and 65% of household sewer backup locations.
For more information about Combined Sewer Overflows, check out these links: