1. Toronto crews have
“concrete” solution for
repairing underground pipes
Last season, Enbridge Gas Distribution performed ongoing mainte- the savings in paving costs – a huge benefit to utility companies
nance on hundreds of gas pipes beneath Toronto’s streets with vir- looking for ways to reduce maintenance and repair costs to help
tually no disruption to traffic or local business. keep their rates down.”
How did its crews accomplish this? Keyhole technology is also environmentally-friendly. There’s no need
for temporary patching, repaving of the roadway or disposal of
Instead of breaking the pavement with jackhammers and backhoes
debris created during excavation. Instead, crews can reuse portions
to gain access to underground pipelines, crews used an innovative
of roadway materials that once became construction waste.
and extremely cost-effective new family of technologies and tools –
“keyhole” coring and pavement reinstatement. The process allows “In addition, the process is win-win for us and for the municipality,”
crews to do repair or maintenance work on underground pipes or says Kathy O’Neill, an Inspector for the Keyhole program at
other buried equipment from the road surface – safely, efficiently, Enbridge. “Not only is the precise circular cut 80% smaller than a
and without the need for more costly and disruptive excavation conventional rectangular road-cut, it is almost invisible after the
methods. Enbridge Gas Distribution developed Keyhole technology repair, which makes it aesthetically pleasing to the municipality that
as a pilot program more than a decade ago. The company has test- owns the road. The high-strength, waterproof bond and circular
ed it on hundreds of excavations, through a wide range of severe shape of the cores also mean no more corner stress cracks in the
climatic conditions – without a single failure. road and no groundwater leaks that penetrate the subsurface and
can cause potholes.”
“A heavy-duty truck-mounted rig cuts an 18" (0.5 metre) diameter
core out of the pavement,” explains Bill Elliott, Enbridge Gas The company used this technology to complete more than 300
Distribution’s Toronto-based Field Manager of Maintenance. “This cores and reinstatements in Toronto during 2003, and plans to do
coring unit is purpose-built to cut through any paved surface – 1,500 more in 2004. A growing number of other jurisdictions have
including reinforced concrete – in less than 15 minutes.” accepted the coring process as a permanent pavement reinstate-
ment method.
The crew then removes and sets aside the core, “vacuum exca-
vates” the underground pipes and equipment, and repairs leaks or “It’s the most exciting and productive maintenance innovation that
do other maintenance from the surface, using special long-handled I’ve come across in my more than 25 years with the company,” con-
tools. “Once the repair has been completed,” says the Gas cludes Scott McClelland, Enbridge Gas Distribution’s Operations
Technology Institute’s Keyhole technology Project Coordinator Manager for the Toronto region. “Based on our experience so far,
Dennis Jarnecke, “the hole is back-filled, and the core bonded back Keyhole coring is rapidly becoming a welcome addition to the tools
into place with a special compound. The roadway or sidewalk is we use in our construction and maintenance operations.”
then as good as new.”
For more information on the Keyhole program at
Actually, it’s better than new. Tests conducted by reputable inde- Enbridge Gas Distribution, please contact:
pendent research organizations (including the National Research
Council, the US Army Corps of Engineers, Golder Associates and Gord Reynolds
the University of Illinois at Urbana-Champaign confirm that the Manager
strength of the bond compound is five times greater than the man-
Keyhole Technology
dated load-bearing standard set by the city of Toronto. Within 30
minutes, it can support the combined weight of six transit buses.
Enbridge Gas Distribution
This process can add years to the life of the roadway, compared to Telephone: 416-461-0408
traditional methods.
Fax: 416-461-5944
“It’s amazing,” Elliott said. “After only half an hour, we can re-open Mobile: 416-732-2200
the site to pedestrian and vehicle traffic. We can promptly move on e-mail: gord.reynolds@enbridge.com
to the next site instead of having to monitor a temporary paving
www.enbridge.com/keyhole
repair until it is complete. And the process literally pays for itself from
JULY 04 05-0702