Minimizing failures to PVC water mains

The city of Calgary, Canada, is notable both for the depth of its commitment to PVC as a material for water & sewer mains, and the low failure rate it has experienced them. The break rate in the early 1990s, ~0.2 failures/year/100km, was roughly one-quarter of the average for 10 other Canadian cities1, and less than 1% of the break rate for poly-wrapped ductile iron pipe in the same environment. The paper offers a hypothesis that this success stems from a tradition of extraordinarily careful and conservative installation methods and specifications that evolved in Calgary during a period when well-protected metallic pipe was installed with great care, just before PVC became an AWWA-specified material type. Some details of these specifications and the rigorous inspection procedures that enforce them are offered.