Often, the reasons for choosing one type of pipe over
another are not black and white. In one case recently in rural Oklahoma, the
reason was blue.
Contractors and utility officials in Water District #10 in
Delaware County, Okla., had always used PVC pipe for their water systems, in
part because it was available in blue for easy identification in the ground.
When a manufacturing members of the Plastics Pipe Institute developed a solid
blue high-density polyethylene (HDPE) pipe for potable water applications, the
battle between HDPE pipe and PVC pipe was on. In the end, HDPE was selected for
this particular application.
"We looked at both HDPE pipe and PVC pipe and decided
that the best choice for the district for the long-term was the
polyethylene," said Tim McCrary of Crafton, Tull & Associates Inc, an
Although the availability of the product in blue got HDPE in
the game, the color of the pipe doesn't help pay back the district's loan--the
selling of the water does.
Water officials in Oklahoma discovered that the less water
that leaked from the pipes, the more efficiently they could sell it, which in
turn helps pay back the loan faster.
"Environmental concerns were among the criteria we used
to pick the pipe material," McCrary said. "When your only revenue
stream is your water, you have to protect that as much as possible. There's
been a big crackdown here on the issue of water loss. We concluded that the
HDPE pipe gives us the best chance at protecting this valuable source."
Heat is on
Unlike PVC, polyethylene pipe, in both solid blue and
traditional black with the blue stripe, provides a leak-free system through its
joining process--heat fusion--that produces strong, totally sealed connections.
Further, polyethylene is a dielectric material and is
frequently used as an insulating material for electrical conductors. Because it
is a non-conductor, polyethylene is simply not subject to corrosion.
"Municipalities with traditional piping systems all
have a minimum allowable 'unused water' percentage that they tolerate,"
said Rich Gottwald, executive director of the Plastics Pipe Institute. "In
many municipalities, this water loss can reach 30% to 50%, or more.
"However, many municipalities are now using HDPE pipe
to construct a leak-free and corrosion-resistant water distribution system to
deliver water to their residents--and are avoiding the problems and costs
associated with leaky systems," added Gottwald.
The other criteria the Oklahoma Water District used to evaluate
PVC and HDPE pipe included cost; operational issue and performance;
regulations; future development of the area; and public and environmental
HDPE scored equal to or better than PVC for this application
in each of those categories, according to the engineers.
The cost factor was tied into the long-term performance.
Engineers conducted a study that projected leaks, breaks, and pipe/joint
failure over a 15-year period and calculated potential lost water. Again, HDPE
pipe was predicted to save more money over that period of time.
Another factor in the decision was the success contractors
in the area had with polyethylene natural gas lines. Polyethylene pipe is used
for more than 90% of the fuel as distribution piping in the U.S. because of its
reliability, leak-free performance and resistance to corrosion.
"We've always encouraged water officials to learn more
about HDPE pipe and its ability to provide the durable performance they
want," said Gottwald. "After all, if polyethylene pipe is trusted by
the fuel gas industry to be leak-free, what's stopping the water
With a plethora of new construction projects in Delaware
County, the sewer lines also will be a major part of the area's development.
"When it's time for the sewer pipes to go in, we'll be
on the lookout for the HDPE pipe," McCrary said.
HDPE pipe helps Oklahoma Water District protect against water loss