NEORSD Utilizes a Service Agreement Approach for Rehabilitation of Large Diameter Sewers
The Northeast Ohio Regional Sewer District recently completed a comprehensive interceptor inspection and condition assessment program to identify structural and operational problems within its collection system and to develop a plan for needed rehabilitation. The program provided an
accurate inventory of District-owned pipes and manhole structures; location data to be used in GIS mapping; noted accessible and buried manholes; located numerous defects; and laid the foundation for a sustainable management program for its in-ground assets.
The ultimate goal of the evaluation
and assessment program was to identify rehabilitation projects throughout the District's service area. These projects were divided into four primary rehabilitation levels:
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Structural Rehabilitation (lining or replacement)
The NEORSD interceptor system consists primarily of large diameter pipes, many constructed of bricks, many
egg-shaped pipes, and some over 100 years old. The inspection of the pipes revealed numerous isolated defects such as fractures, missing bricks, displaced bricks, infiltration, or holes in the large pipes. Through the condition assessment process, many of the pipes were given recommendations
for stabilization efforts to prevent or slow the further deterioration of a defect that may lead to failure. The spot repair decision was based on the observed need for rehabilitation and the cost/benefit analysis of full lining or replacement versus the spot repair.
Once a spot repair
was decided upon, the challenge was to develop contract documents to support the spot repairs that would provide for numerous types of rehabilitation efforts and also account for the likelihood that the conditions within the pipes have changed since the initial inspection. To meet the challenge,
the design team surveyed numerous sewer agencies to learn what others have done in regards to spot repairs, capitalized on the extensive amount of data collected during the inspection project and other District planning projects, and prepared a service agreement contract structure that would
provide the needed flexibility for this work. This paper will discuss the decision process for selecting spot repairs in lieu of lining or replacement, the background data received from polled agencies, and the preparation of the design documents and lessons learned for the on-going NEORSD
sewer rehabilitation program.
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