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Condition-Based Asset Management: Investigation, Assessment Of The Oakland Macomb Interceptor System
The investigative techniques utilized included closed circuit television (both tractor mounted and raft mounted), sonar, laser measurement, surface geophysical investigation, geotechnical investigation and man entry inspections. In addition, both chemical and atmospheric testing was performed as a part of the inspections.
Closed circuit television (CCTV) is considered the standard for the evaluation of collection systems. In the Detroit area, the use of CCTV to evaluate sewers first appeared on a regular basis in the early 1980s. The initial cameras were rigidly fixed to a skid and sometimes the hardest part of the job was getting the pull line through the sewer to pull the camera. Defects were recorded by hand on paper forms and each operator recorded what they saw in their own words. As a result, if a sewer was televised at different times by different firms, the descriptions often varied greatly. Descriptions also varied widely between members of the same firm. Because of the variances in descriptions, it was difficult to monitor change from inspection to inspection.
The Water Resources Centre (WRc) in London recognized the need to standardize descriptions. The WRc first published their Manual of Sewer Condition Classification in 1980 but it was a number of years before it reached the Detroit area. By the mid-1990s with the advent of computerized recording systems, the WRc classifications were included in the dropdown menus. In 2002, the National Association of Sewer Service Companies, in conjunction with WRc, released their Pipeline Assessment Certification Program (PACP).