Lessons Learned from Failure of a Large Diameter Water Pipeline

Construction was near completion for a 28 mile long by 48 inch diameter pipeline when problems were discovered in the hydrostatic testing phase. Sections of pipeline would not hold test pressure and subsequent inspections revealed some pipe segments (joints) of the pipeline had collapsed. Additional internal inspections revealed much of the pipeline had excessive vertical deflection and failure of the mortar lining. The authors were hired to provide forensic engineering, pipeline remediation design, construction observation of the pipeline remediation, and construction contract administration. Forensic engineering revealed the primary cause of failure was inadequate compaction of the pipeline embedment material. Approximately 15 miles of the pipeline were completely removed and replaced with new pipe and 13 miles of pipeline were repaired. The pipeline remediation construction cost was approximately $20 million. Many other problems were discovered during the remediation construction and are discussed in the paper. This paper describes the highlights and lessons learned during the forensic engineering phase and pipeline remediation construction phase.