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Nov 08

Supplemental Overflow Control Plan

Posted on November 8, 2022 at 10:31 AM by Rachel Douglas

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Supplemental Overflow Control Plan

Springfield Environmental Services recently completed an annual report of its Supplemental Overflow Control Plan (SOCP) activities for fiscal year 2022. The report contains information on the overall structure of the program and the work completed between July 1, 2021, and June 30, 2022. This information is required to be provided annually to the Missouri Department of Natural Resources, however, we think it is also a great tool to help educate Springfield rate payers on the progress being made to improve their sanitary sewer infrastructure and community.  

The primary goals of the SOCP, on which the City of Springfield is scheduled to invest $300 million over a 15-year period, are to eliminate both wet-weather sanitary sewer overflows from the sewer collection system and prohibited bypasses from the City’s two wastewater treatment plants. Overflows and bypasses can occur when the capacity of the sanitary sewer system or treatment plant is exceeded during rain events when large volumes of water enter the system. This occurs through improper connections, like gutter downspouts or basement sump pumps, which are termed “inflow” sources as well as seepage from groundwater pressures through cracks or other deficiencies in the system piping or manholes, which are termed “infiltration” sources. Together, these inflow and infiltration (also known as I&I) sources can, during major rain events, contribute more than three times the volume of normal dry weather wastewater flows. This can temporarily overwhelm the system and require that pressure is relieved through overflows, typically occurring at manholes, where a mixture of I&I and wastewater escape until the rain event subsides.  

A few highlights from the 2022 SOCP report:

  • City of Springfield 2022 SOCP Annual Status ReportThe highlight of SOCP activity in fiscal year 2022 was the investment of $8.02 million in collection system renewal projects. These projects help correct leaks in sanitary sewer system pipes (of which the city has 1,200 miles) and manholes (which number more than 29,000) by a variety of rehabilitation techniques including pipe lining, pipe replacement or repair, and lining of manholes. These improvements help tighten up our community’s aging sewer system and help reduce overflows into neighborhoods and backups into homes and businesses while overall extending the life of the infrastructure and making the system more efficient.
  • $1.89 million was invested in treatment plant renewal projects that include expanding a wastewater holding facility at the Southwest Wastewater Treatment Plant to increase storage capacity for large wet weather events and general rehabilitation work on the testing laboratory and primary treatment components of the Southwest Plant. Long-range planning studies were also begun for both the Northwest and Southwest Wastewater Treatment Plants to assess near-term rehabilitation needs at each facility and plan for long-term facility improvements to support the projected growth of the Springfield area.  
  • A total of $780,000 was invested in the City’s Private Sewer Repair Program to reduce I&I from private sources, such as homes and businesses, that are connected to the collection system. This program strategy seeks to help property owners become aware of deficiencies in their plumbing that are contributing inflow to the public sewer system. Identified problems are then repaired at no cost to the property owner. Reducing I&I from private sources helps lower peak flows during wet weather events and collectively contributes to reducing overflow events.  
  • The remaining $3 million was invested in various other program strategies, including projects to increase flow capacity at certain bottlenecks in the collection system, the monitoring of system flows, a study to optimize sewer cleaning efforts, and other programs to help improve water quality.

In the first two years of the SOCP, the City has invested a total of $39.32 million, which is very close to a straight-line average necessary to meet the overall investment goal by 2035. View a copy of the full 2022 SOCP annual report and view past annual reports at  The City of Springfield continues to make progress towards the overall goals of the Plan and has seen significant reduction of I&I in sewer basins where program work has been completed.  

Ron Petering Portrait

Written By:

Ron Petering

Assistant Director 
Environmental Services
[email protected]
755 N. Franklin Avenue, Springfield, MO 65802