On most any day, people are out playing
soccer on the fields of Waterloo, Ontario. Soccer is a serious
business that cannot be disrupted by something as mundane as replacing
sewer pipes. With that in mind, Harry Cosford of Swiss Hill Landscaping
took on the job of installing new sewer lines beside a city soccer
field. While installing the underground pipes, he had to avoid
delaying the games.
 The
job consisted of replacing 400 feet of four-inch sewer piping
along the western end of the field. The site included the soccer
field, underground water lines that could not be disturbed,
and bad soil conditions. The ground had been filled in with
imported soils that contained rocks and concrete.
Boring beats trenching. The traditional
trench-and-replace method could not meet Cosford's goals. He
chose the same trenchless technique that the city of Waterloo
was already using to replace underground pipes--using a piercing
tool for lateral connection bores to replace sewer lines. The
work had so impressed Cosford that he knew it was the only way
to do the job.
Although piercing tools were introduced
in Europe more than 30 years ago, the tools had not been used
often to install the type of gravity sewers Waterloo needed.
The Grundomat Tool by TT Technologies, however, was up to the
task at the soccer field.
Despite less than ideal conditions,
the Grundomat tool bored through on the correct trajectory and
exited on target each time. The 5 3/4-inch tool created three
bores, one at 100 feet and two at 150 feet. They were completed
in two days. The speed was about 1.5 feet per minute, so the
total boring time amounted to less than five hours. Traditional
trenching would have taken several days.
Head design pushes job forward. The
Grundomat boring machine, with its reciprocating stepped-cone
head, hit the target. Unlike the cone-shaped heads on most piercing
tools, the Grundomat pneumatic piercing tool provides fast and
accurate horizontal boring in a variety of soil conditions,
according to the manufacturer.
Smooth operators. Piercing tools
perform underground horizontal bores with little or no surface
disturbance. They can be launched directly into a slope, such
as a railway bed or a highway bed, and exit on the other side
of the rails or road, leaving traffic flow uninterrupted. The
procedure is cheaper than trenching because it requires less
crew and equipment. There's no resurfacing or repair of the
rail or road, either. In applications such as the soccer field
job, small entrance and exit pits are prepared to launch and
retrieve the tool.
Piercing tools are being used to
install or repair sewer and water lines, cable, and electrical
conduits. The tools are available in many sizes to fit most
applications. The Grundomat tool alone comes in 10 sizes. The
tool can create a bore with the pipe inserted later, or the
pipe or conduit can be pulled in behind the tool with a pipe
pulling adaptor. Pipe pushing adaptors are available for installing
the pipe after the bore has been made.
The high cost of trenching, laying
pipe, and then resurfacing areas is convincing owners and contractors
that horizontal boring is often a better option. Contractors
who have invested in piercing tools have found that they pay
for themselves after just a few jobs.
"Using a Grundomat tool was a cheaper
alternative compared to the open trench method," Cosford says.
"Plus I didn't want to rip up the playing field."
Constructor, March 1995,
Page 30
|
