PCCP Inspection Truthing and Educational Demonstration
Reclamation's inventory of prestressed concrete cylinder pipe (PCCP) has been in service for 25-60 years as very large diameter, 8 to 20 feet, main and transmission pipelines. Two recent failures of Reclamation-built PCCP spurred the need to survey the history of Reclamation PCCP, update and input our inventory into a GIS format, and push for inspection of all PCCP that is owned by Reclamation. This effort has identified and prioritized 46 installations across all Regions except GP and totaling approximately 93 miles of pipe.
Reclamation's Policy Office Asset Management Division has recently submitted a purchase request to fund up to $2.3 million for electromagnetic (EM) inspection of PCCP in FY18. These inspections will likely begin in fall 2018 and have been scheduled to prioritize structures that have never been inspected for wire breaks with EM technology. In the meantime, several water and irrigation districts have taken proactive steps to inspect their pipe. One such EM inspection took place in January 2018 on the Ak-Chin Link Pipeline outside of Phoenix, AZ. This pipeline was built in 1981 and spans approximately 8.5 miles with 84" and 78" diameter PCCP. The EM inspection contractor found 22% of the pipes surveyed had EM signals indicating broken prestressing wires. Eight sections were designated for immediate repair or replacement as they exceeded the yield limit of the pipe. The Ak-Chin Indian Community operates the pipe and will be implementing these recommendations in FY19. Reclamation TSC has corresponded with the Phoenix Area Office and is exploring an agreement with Ak-Chin Indian Community to preserve a section of the distressed pipe and bring it to Denver to use as a ground truthing tool for the EM inspection and as a teaching demonstration. In the case that the Ak-Chin Link section is not available, several other inspections are slated for FY18 through the Policy Office program mentioned earlier and these may also yield suitable pipe s
Need and Benefit
Reclamation currently has approximately 46 installations of PCCP totaling 93 miles, affecting all Regions except GP.
In light of recent failures, Reclamation is taking proactive measures, in the form of $2.3million in FY18 with more
investment anticipated in FY19 and FY20, to assess the condition of its inventory of PCCP through EM inspection and
plan scenarios for projected repairs and replacements. This effort could greatly reduce occurrences of unexpected
failures and save Reclamation millions of dollars. To complement this effort, Reclamation needs to increase the
knowledge base of its staff to understand tests performed during an inspection and interpretation of the results.
This research will employ laboratory ground truthing to give Reclamation a level of confidence with which to treat the
results from upcoming EM field inspections. The permanent installation of a PCCP in the Denver labs will also provide
a tool to develop and maintain Reclamation staff capabilities in visual and sounding inspection of PCCP and
interpretation of EM field inspection results.
EM inspections of Reclamation's inventory of PCCP will begin in fall 2018 and are anticipated to continue for 2-5
years. This research will take advantage of an upcoming replacement to secure a stick of distressed pipe. If this
research is not funded, this opportunity may be lost, and it will deny Reclamation staff a valuable educational tool, as
well as the first-person knowledge in ground truthing EM results with which they can critically review upcoming
contractor-generated inspection reports.
Contact the Principal Investigator for information about partners.
Bureau of Reclamation Review
The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.
PCCP Inspection Truthing and Education Demonstration (final, PDF, 7.9MB)
By Matthew Jermyn
Report completed on September 30, 2022