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Updated ASCE Manhole Guidelines Focus On Issues, Rehab Methods
- Safety information has been updated and expanded to include a section about procedures to take before entering a manhole, after entry, rescue procedures and a detailed check list for confined space entry with a safety flow chart;
- Guidance for inspection procedures has been expanded, including mapping and numbering, data recording and suggestions for photographic records;
- Expanded I&I quantification provides alternative methods to estimate I&I from manhole defects;
- Information on rehabilitation methods covers the latest technologies and a manhole rehabilitation option decision matrix;
- Estimates of typical rehabilitation costs and life cycle costs for rehabilitation components are included;
- Guidelines for construction inspection includes coatings and linings; and
- The revised manual contains updated color photographs of typical manhole defects and methods of rehabilitation.
A presentation explaining the revised manual was presented last month at the 2010 UCT (Underground Construction Technology International Conference & Exposition) in Tampa and copies of the manual can be ordered on the ASCE web site (www.asce.org) or purchased from outlets that carry ASCE publications. Completion of the manual required about five years of work by many dedicated professionals (see attached sidebar).
Nelson says as of 2007, the estimated number of manholes in the United States was 20 million – significant assets to communities and the primary means of access for sewer collection systems in order to perform maintenance.
"Evaluating and estimating the life of these structures is of considerable importance in the financial planning of agencies particularly in respect to depreciation allowances and rates of return on investment," he says. "Actually estimating the economic life – the age when a manhole becomes more cost effective to replace than to rehabilitate – is a function that must be recognized on a local basis. Therefore, one of the goals of this manual is to provide an inspection and condition grading protocol that provides logical follow up steps which can be taken to maintain and improve upon the health of these structures."
Evolutionary improvements in material for constructing and repairing manholes also make the new guidelines timely.