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Updated ASCE Manhole Guidelines Focus On Issues, Rehab Methods
Manholes are critical assets of the nation's underground wastewater infrastructure. Recently updated manhole inspection and rehabilitation guidelines are aimed at improving manhole structural integrity by identifying issues and the appropriate methods of repairing and rehabilitation so that timely maintenance prevents major problems.
Since 1997, the most comprehensive industry guideline for manhole inspections has been the Manual of Inspection and Rehabilitation Practices No. 92, published by the American Society of Civil Engineers (ASCE).
"It was the first manual of practice developed in the United States focusing exclusively on manhole inspection and rehabilitation," says Richard (Rick) Nelson, vice president and director, conveyance infrastructure technology, CH2M Hill. Nelson is the ASCE committee chairman and one of the primary authors of the first edition and a reviewer of the second edition of the manual which was developed by a committee lead by Joanne Hughes, RS Lining Systems.
Nelson says the manual addressed safety, manhole inspections procedures, quantification of inflow and infiltration (I&I), rehabilitation methods, cost effectiveness analysis of rehabilitation methods, and construction inspection and quality control.
"The authors of this first manual included many industry leaders from utilities, vendors and consultants," Nelson says. "The goal of the committee was to publish a manual of practice to help standardize the inspection of manholes and provide guidance on data evaluation, I&I quantification and rehabilitation methods. The manual included color photos of defects as an aid to the practitioner.”
Time for update
That manual has served the industry well. However, it was prepared between 1994 and its final approval and publication three years later, and technologies have changed significantly since then. Nelson provides this summary of key points in the revised guidelines: