Condition-Based Asset Management: Investigation, Assessment Of The Oakland Macomb Interceptor System

U-TECH
By John R. Kosnak, P.E., M. SAME and Harry R. Price, P.E., F. SAME | October 2012, Vol. 67 No. 10

PACP provides an objective system for the classification and documentation of observations during a CCTV inspection. Based on the research by the WRc, the PACP system provides a 1 to 5 rating for the defects, with 1 being the best and 5 indicating immediate action required. The PACP provides a computational methodology for establishing the average rating of a portion of a collection system and a four-digit Quick Code that lists the number of the two most severe ratings encountered using an alpha numeric code. PACP is subdivided into four areas; Structural Defect Coding, Operational and Maintenance, Construction Features Coding and Miscellaneous Features Coding. Each of these four areas is in turn divided into multiple subsections. For example, the Structural Coding is divided into cracks, fractures, broken, hole, deformed, collapse, joint, surface damage, buckling, lining failure, weld failure, point repair and brickwork. Certified users are provided with a complete reference manual and a key which lists codes by family and provides a page reference guide.

Inspection, evaluation
A series of Condition Inspection and Evaluations were performed on the Oakland Macomb Interceptor System in 2007 and 2008. Within the lower portions of the Oakland Macomb System, the CCTV was supplemented with surface seismic testing using the multi-channel analysis of surface waves (MASW) technique. In addition the CCTV in the lowest portion of the system was also supplemented with sonar testing to identify debris along the invert of the interceptor.

The reports for these inspections and recommendations for remedial measures were issued in January 2008 and August 2008. Based on these reports, a program was developed that addressed the defects with PACP grades of 4 or 5. The initial phase of this defect restoration program was to construct flow control gates to provide in-line storage such that restoration could be performed while portions of the interceptor were in a dewatered condition.