Why Material Selection Matters
Water and WastewaterAnd why there is more to pipe than just purchase price
The Tri-County Water Authority (TCWA) was formed in 1991 as a not-for-profit water utility serving portions of Jackson, Cass and Bates counties, Missouri. When the system was first established, about half of the pipe installed were ductile iron and half were plastic PVC. Today, the authority’s 120 miles of pipe are approximately 75% ductile iron and 25% plastic PVC.
During its more than 25 years of service, TCWA has seen more than 250 main breaks. Most of those involved plastic PVC pipe and only three involved ductile iron pipe. TCWA General Manager John Overstreet said, “While the expenses vary depending on the location and the size of the pipe, the repair/replacement costs associated with each of these events can easily exceed $5,000.”
For a portion of a 32-mile pipeline installation in 2015, TCWA chose AMERICAN’s zinc-coated ductile iron pipe with V-Bio ® enhanced polyethylene encasement. During the pipeline’s design, the TCWA analyzed many factors including material and installation costs as well as life expectancy and pumping costs. The decision was clear: Ductile iron pipe with a protective V-Bio enhanced encasement provided a far better life-cycle cost and benefit.
A portion of the pipeline involved a transmission main in an area with highly corrosive soils, and the TCWA used corrosion monitoring equipment in the area to monitor its investment. With three years of data now available, the transmission main’s survival against corrosion calculates to several hundred years.
“For water utilities with corrosive soils, AMERICAN’s zinc-coated ductile iron pipe with V-Bio enhanced polyethylene encasement provides protection that wasn’t available before. This combination of zinc-coated and V-Bio wrapped ductile iron pipe has proven to protect ductile iron pipe in aggressive environments around the world,” said AMERICAN Senior Sales Engineer Tyler Bolen. “Now when a water main needs to be extended or another section of plastic PVC pipe requires replacement, TCWA’s primary material of choice is zinc-coated and V-Bio wrapped ductile iron pipe.”