Underground Construction - July 2017 - 28

REHABTECHNOLOGY

Pipe Slitting

Brings Cost, Time, Life-Saving
Benefits To Airport

Pilots shout out "clear" to warn
anyone they might not be able
to see around their plane and
to stay away from the propeller.
While some pilots starting up their
planes at Frasca Field, a privately
owned, public-use airport located
at the northern edge of Urbana, IL,
might have seen men and equipment working the ground between
two hangars, they were all well
clear of flight line activities.
Unless the pilots had stopped
to ask, they could not know water
pipe spanning the breadth of the
paved surface was being replaced
right beneath their aircraft's
wheels. That's because the MidState Sewer Services crew was
using a technique called "pipe slitting." While widely used to replace
or decommission gas line services,
the technique is being successfully used by Mid-State to expand
the options it offers customers for
noninvasive, trenchless water service replacement.

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Mid-State's owner, Steve Johnson, had performed spot repairs
on this line in the past, so he was
familiar with its deteriorating
condition. He advised Tom Frasca, owner of Frasca Air Service,
the airfield's fixed-base operator (FBO), that it was time to
consider replacing the water line
completely.
"Otherwise," Johnson told Frasca, "you're at a point where you're
just going to find yourself making
these little 10-foot repairs more
and more often."

Best course of action
Replacing the line between the two
hangars was no problem, as it lay
in open ground. Johnson could
access the pipe with a simple narrow trench. However, a 340-foot
run of 1½-inch HDPE pipe feeding
the line from the FBO building
was problematic. Lying perpendicular to the hangars' shared
water pipe, it joined the pipe at a

tee fixture midway between the
hangars. Except for that short bit
of open ground at the tee, the pipe
ran below the airfield's tarmac, a
portion of the field's paved surface
where planes park and transition
between its hangars and runways.
The trench for the original installation can be seen in pilot photos
from the early 1960s. It was well
past its useful life.
Traditional open-cut replacement of the water supply line
with 1¼-inch CTS (copper tubing
size) HDPE would mean opening a 2-foot-wide trench across
the entire paved surface. While
it wouldn't shut down the airport completely, it would cause a
significant disruption to routine
activities for many days. Urbana's
municipal field, University of Illinois-Willard Airport, lies just on
the other side of the metropolitan
area from Frasca Field, is larger.
Private pilots and corporations
prefer Frasca for its lower traffic

Above: The HammerHead HG12 Auto
Boom winch easily managed the long
length of cable required for water line
replacement beneath the tarmac of
Frasca Field in Urbana, IL

volume. Trenchless replacement
was highly preferable for this job.
Even though his mid-Illinois
service area doesn't often require
trenchless techniques, Johnson
has a great deal of experience in
them. About 13 years ago he added
a Hammerhead PortaBurst PB30
to his equipment fleet to expand
capabilities.
"Every once in a while," Johnson said, "we would have to upgrade a line that ran under a road
or patio or foundation. It sure
comes in handy on jobs like that."
The portable 30-ton puller might
sit unused for a couple of months,
Johnson added, "but then I might
have a streak where I need it twice
a week for a while."
A few years ago, Johnson invested in gas line pipe slitting
Underground Construction July 2017

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Underground Construction - July 2017

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