Manholes Rehabilitation: Sometimes Misunderstood, Yet Key Infrastructure Solution

First In A Three-Part Series
By Gerhard “Gerry” P. Muenchmeyer, P.E. NASSCO Technical Director | September 2011, Vol. 66 No. 9

Manhole assessment
With all the challenges facing collection systems, it is not surprising that many manholes have significant defects that need to be identified using standard coding. After coding the defects and evaluating conditions, the manhole may require rehabilitation to extend its life expectancy. The first step toward rehabilitation is to conduct a comprehensive assessment and determine the overall condition of the manhole by identifying what defects, if any, need to be rehabilitated. Based on the standard Pipeline Assessment Certification Program (PACP), NASSCO created the Manhole Assessment Certification Program (MACP) which now includes two levels of inspection for condition assessment.

A Level 1 inspection allows utility owners to identify basic assessment information to evaluate the general condition of a manhole and to gather enough information to determine if a comprehensive Level 2 inspection is required or appropriate. A Level 1 inspection can typically be completed without the use of any special equipment or manned entry into a manhole.
A Level 2 inspection allows the utility owner to gather detailed information to fully document all existing defects, determine the condition of a manhole and to provide specific information to recommend or specify corrective actions.

Manhole components
Unlike the main pipeline portion of the collection system, a typical manhole consists of many different components, each requiring condition assessment and identification of defects that affect the function of the overall manhole structure. These typically include:

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