A Municipal Water Utility had a project involving construction of a 6.6-mile long water transmission main. The transmission main was to be constructed inside a continuous tunnel using 84-in. diameter Prestressed Concrete Cylinder Pipe (PCCP). Project specifications required that the PCCP be fabricated in accordance with ANSI/AWWA C301, and stated that inspection and testing by the Owner during manufacture of the pipe will be performed by representatives of the Owner. However, fabrication of the PCCP commenced prior to notice being given to the Owner’s representative, which resulted in 208 individual pipe sections (~12% of pipe produced for project) that lacked an adequate basis for acceptance.
CTLGroup was retained by the Owner’s representative to perform post-fabrication evaluation of the 208 pipe sections that had not been inspected during fabrication. CTLGroup’s scope of work included 1) review of all available relevant documentation related to fabrication of the subject pipe and destructive evaluation of nine representative pipe sections taken from the lot of 208. Destructive evaluation consisted of removing the mortar coating and prestressing wire from each pipe, documenting key fabrication details, and obtaining component material samples for subsequent laboratory evaluation. Upon completing this work, CTLGroup provided the Owner with a report documenting findings and conclusions from the evaluation work.