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STRUCTURAL CAPABILITIES OF NO-DIG MANHOLE REHABILITATION (WE&RF Report INFR1R12)
Citation:
Najafi, M. AND V. Sever. STRUCTURAL CAPABILITIES OF NO-DIG MANHOLE REHABILITATION (WE&RF Report INFR1R12). Water Environment & Reuse Foundation, Alexandria, VA, 2016.
Impact/Purpose:
• Creates awareness on the condition and importance of the sanitary sewer manholes. • Describes the effects of a manhole failure with respect to utility infrastructure asset management as well as environmental, social, and economic consequences. • Provides insight on the available manhole rehabilitation techniques to help wastewater community understand the capabilities of them. • Provides cost information and tools to rehabilitate a manhole in the most cost efficient manner. • Guides the wastewater (and stormwater) utilities and their consulting engineers with making decisions on material and method selection. • Establishes sound wastewater rehabilitation programs, thereby reducing sanitary sewer overflows (SSOs) and their effects on the environment.
Description:
Failure of a manhole may have catastrophic consequences such as a sinkhole. At a minimum, wastewater flow will be blocked and flow upstream of the manhole will backup, causing a sanitary sewer overflow (SSO). Accordingly, the structural condition of a manhole is an important performance indicator and risk of failure should be minimized. Mechanical strength of manhole rehabilitation materials vary substantially and little is known about their ability to withstand the dead and live loads exerted on the manhole. As such, this project investigates the structural capabilities of commonly used manhole rehabilitation materials and methods via literature review, and case study compilation, lab tests on mechanical strength, and computational modeling. A classification for manhole rehabilitation techniques is provided based on their structural capabilities (i.e., fully, semi-, or non-structural). The results of this project suggest that any type of manhole rehabilitation material can be applied as fully structural; nevertheless, it may be difficult to achieve the thickness required to qualify as fully structural for the spray-applied, cured-in-place type liners. A user-friendly, preliminary decision support tool is in progress and will be provided when complete as a practical tool to help choose structural class and construction methods appropriate for a manhole considered for rehabilitation.
