SD1 Continuous Sewer Assessment and Rehabilitation Program - 5 Years Later

Authors:

  • Sean Fitzgerald - Hazen and Sawyer
  • Rich McGillis - Sanitation District No. 1 of Northern Kentucky

In 2008, Sanitation District No. 1 of Northern Kentucky (the District), which serves over 250,000 people in Campbell, Kenton, and Boone Counties, developed and implemented an aggressive Continuous Sewer Assessment and Rehabilitation Program (CSAP). The program was developed a part of the CMOM Program required as part of a Consent Decree with USEPA Region 4 and the Kentucky Division of Water (KDOW) to address CSOs and SSOs in the sewer system.

In addition to being a CMOM requirement, the program serves as a best practice for SD1 and wastewater utilities to optimize their operations in the most effective manner to help achieve the highest level of service to its customers. The goal of the program was to move SD1 into a more proactive mode of sewer assessment and rehabilitation and help to reduce preventable sewer spills. The program has provided a much better picture of the overall condition of the collection system which is over 75 years old in many parts of the District. SD1 took over all of the sewer systems from individual cities in 1996. Many of these sewers had never been inspected or properly maintained.

Since SD1 was at the 5-year mark since the inception of CSAP, it was time to assess how the program was doing and to utilize the data gathered so far to develop a refined Asset Renewal rate projection for the next 20 years. This paper will present the results of the program so far as well as the results of an Asset Renewal Rate Study which utilized condition data from the previous 5 years to project Asset Renewal needs for the next 20 years. The projected needs utilized condition data which was converted to a remaining useful life (RUL) for each pipe. The RUL for pipes that do not currently have condition data were projected by forecasting condition by pipe material based on the distribution of RUL for pipes of the same material that have been inspected. Two renewal rate scenarios were assessed and compared to the “rule-of-thumb” 1% per year rate. The result is a defensible knowledge based projection of funding needed to maintain the condition of the collection system at a specified overall condition.

The paper will also present how the program has significantly reduced preventable overflows, improved workflow, and has allowed SD1 to move to a proactive mode in the management of its collection system and to provide a higher level of customer service to its customers. The result has been reduced overflows while cleaning fewer pipes and a dramatic reduction in the unit price for sewer rehabilitation.

Nevertheless, as with any program, periodic reviews are needed and refinements should be implemented to address lessons learned and provide improvements to the program. SD1’s CSAP is no exception. We will present some lessons learned and program refinements that will be implemented to further strengthen the CSAP as it moves into the future and is a permanent part of SD1’s Operations.

For more information, please contact the author at sfitzgerald@hazenandsawyer.com.

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