finally arrives, turf managers begin their agronomic practices that will
prepare turfgrass for the grueling summer schedule. Pre-emergent applications,
aerification, and fertilization mean another right of spring: the irrigation
leak. Months of no or limited activity coupled with the changes in soil
temperature reveal the weaknesses within the system that we have become so
familiar with. While digging up these leaks, ringing our hands in anticipation
of the cold water soon to numb our fingertips, the thought inevitably enters
our heads: “There must be a better way.” Well, to that I would like to reply
with “there is!”
A not so
new strategy to remove these leaks from your spring playbook is available in
the form of HDPE pipe. Used for decades in the petroleum industry for its leak
resistance, HDPE is now becoming more popular in irrigation applications.
of you were anticipating what I might share that could take away your acrimony
for irrigation, the mention of HDPE has probably just as quickly turned a few
of you off. “What is HDPE?” “Why would I switch to HDPE?” and “how much does it
cost compared to PVC?” are common questions once I start discussing HDPE
high density polyethylene, is a thermoplast plastic that is safe for the
environment, limits product waste, and can be installed and maintained through
what is known as “fusion” or a more traditional coupling method.
surprised to find out how few of us understand the variety of dangers that PVC
poses on us and the world around us. PVC, or poly-vinyl chloride, is a pipe
that uses dioxin in its creation. Dioxin is a known carcinogen and has been
linked to numerous health issues like birth defects, neurological disorders,
and a variety of cancers. Just breathing the fumes of PVC is extremely toxic.
Burning PVC pipe exposes you to dioxin and chloride. While this may seem
trivial to you now, will you feel that way in 20 or 30 years?
HDPE releases no noxious gases either during its creation or during its use and
potential degradation. When HDPE is burned it simply returns to carbon, a basic
element that surrounds us all in our daily lives. Resistance to degradation,
resistance to leaks, and environmental safety are all reasons why HDPE has been
a staple in petroleum and more recently in municipal infrastructure as a
potable water delivery source.
The use of
HDPE is also better for the environment as very little pipe is wasted during
installation. HDPE has no bells, no male or female ends. Each pipe is fused
together to make a monolithic single piece of pipe. When cut, no matter the
length, HDPE can be reconnected through fusion. This means that every inch of
HDPE is usable. We can also create our own directional fittings. The need to
order specific-sized tees, reducers and bushings is nearly nonexistent.
installing PVC, we use pipe connected by glue or gasket. Both connections use a
bell on the end of the pipe and a lubricant or solvent to assist with the
connection. We “bump” the pipe together, male end to female end, and hope our
precautionary preparation will reveal no leaks after pressurizing.
many of you may not know is that PVC has an “allowable leakage rate” from its
very first day in use. You read that correctly. When studying PVC you’ll learn
that it is not expected to be 100% leak free like HDPE. The connection points
for PVC, be it glue or gasket, are expected to exhibit minimal leakage. This
becomes more of an issue because as PVC gets older it becomes more brittle. PVC
also “de-rates” with use. What that means is that as water moves through the
pipe via the starting and stopping of the pump station, isolation through
valves, and the on-and-off sprinkler usage, PVC loses its sustainability.
accounting principles allow us to depreciate an irrigation system. The life
expectancy of pressurized PVC is roughly 15 years according to the Golf Course
Builders Association of America. By comparison, we do not have such an
allocated life expectancy for HDPE pipe. The monolithic fusion process of HDPE
removes the couplings, creates one singular monolithic pipe, and removes pipe
de-rating from the equation entirely. Most irrigation designers who are
familiar with HDPE will say that it should last 40 or more years, doubling the
life expectancy of PVC. In fact, those HDPE life expectations may be
conservative. Doug Zak, director of sales for CMF Global, a large HDPE
producer, states, “AquaFuse HDPE is rated to well over 100 years. While PVC was
an amazing advancement in irrigation years ago, the attention given to water
conservation and the fact that many sports turf complexes purchase water or use
effluent water is enough to initiate more interest in HDPE.”
biggest hurdle many sports turf managers face when discussing HDPE is the
fusion process I mentioned before. While you may hate digging up leaky PVC and
speculating what type of repair coupling to use, the fact that you have
familiarity with it instills confidence that you are able to service and repair
“What if I
have a leak?” is a legitimate question that every turf manager should ask. The
answer is that fusion isn’t as complicated as perceived. To simplify fusion, it
is simply a connection process that uses heat and pressure to connect HDPE
pipe. While several fusion methods exist, the theory behind them all is that
simple. Butt fusion is used in connecting pipe that has been butted up to each
other end to end. A second fusion type, saddle fusion, is used primarily when
changing pipe direction or pipe size. Saddle fusion does just as the name
implicates, where a fitting will ride on top of the HDPE pipe like a saddle,
and be fused to the pipe. Socket fusion offers a type of fusion where a coupler
can be heated and pressed into the HDPE pipe. Most socket fusion is done on
smaller diameter pipe.
style of fusion is electrofusion. Electrofusion also uses a coupler that allows
the HDPE pipe to be slid into it, then uses electrical contacts to heat the
coupler and pipe into the same seamless monolithic pipe just as the other
styles of fusion offer. Electrofusion is the simplest and removes the
experience level that can be so crucial to proper fusion. While it is the most
expensive, it is also the safety net that turf managers can rely on to fix that
critical leak when unforeseen circumstances, like drainage work, compromises
the pipe. The electrofusion device takes the guesswork out of how long to heat
or what pressure to use when pressing the HDPE pipe together.
irrigation or coupling new irrigation can also be done with special compression
type fittings available in many different brands and types, among them are
fittings from a manufacturer named Philmac. Using these compression fittings
can serve as a huge safety net for the turf manager who wants complete control
over repair and installation without implementing some form of fusion. A
Philmac compression fitting tightens down on each end of the pipe, biting or
gripping into the HDPE and providing a leak free connection. The only drawback
to the Philmac fitting is that it doesn’t come in larger sizes; a 3-inch
Philmac fitting is the largest I am familiar with. What is not commonly known
is that other “knock-on” or joint restraining couplers can also be used on
HDPE. The outside diameter of HDPE and PVC are the same, allowing turf managers
to use traditional gasketed couplings to be used, even if it’s only temporary
until some form of fusion is completed.
coupling decision you make, know that HDPE pipe comes in sticks no shorter than
40 feet. That already reduces fail points by at least half as rigid PVC pipe
comes in sticks no longer than 20 feet. I have used 2-inch HDPE in 500-foot
rolls on numerous occasions. This means that no or limited connection points
will even be necessary. Imagine the ease of installation on a sports turf field
where the majority of pipe is 3 inches or less. With the traditional pipe
layout found in most football or baseball fields, HDPE quickly becomes a viable
how much you may like something, the ultimate question we must all prepare for
is “What does it cost?” The answer is not as much as you think. In the past,
the cost difference was a factor. But with increased demand for HDPE, the
attention given to PVC and its associated health concerns, and a better
understanding of what true “apples to apples” comparisons are between HDPE and
PVC pressure ratings, we see the cost difference is shrinking considerably.
“HDPE resins are now about the same as PVC resins pound for pound,” says Zak.
comparing the installed price difference between an all-fused HDPE system
(pipe, fittings and valves) you have to keep in mind that 90 plus percent of
HDPE systems are joined above ground, not in an open trench. This usually
speeds up installation times and allows for full and complete inspection of the
fusions long before it’s rolled into a trench. Fused HDPE pipe can be fully
pressurized one hour after completion, as opposed to waiting 24 hours on a
glued PVC joint.
offers expandability. Hybrid systems using PVC mainlines and HDPE laterals have
been a common design strategy over the last few years. This allows turf
managers who are concerned with fusion as an installation or repair strategy to
maintain control over their systems with traditional coupling devices for both
PVC and HDPE. This could make renovations cheaper by keeping existing mainlines
and marrying new HDPE laterals to the system as a temporary or permanent strategy
depending on your properties wants and needs. So, when you get the irrigation
repair blues remember, there may be a way to avoid it or at least minimize it.
That is, unless you really like to dig holes each spring.
Wilkinson is a Professor, Golf and Sports Turf Management, at Horry Georgetown
Technical College, Myrtle Beach, SC.