Underground Construction - May 2018 - 27

3,900 feet of 16-inch diameter
ductile iron water pipe alongside
the major thoroughfare Estrella
Parkway, which adjoins areas
where residential subdivisions
will be built. The new line is
being installed at depths of up
to 16 feet deep. The crew is also
running a shallower trench parallel to the water line ditch for a
future electrical line.
Projects like the Estrella parkway come with unique
challenges, namely frequent
encounters with underground
rock formations. It's so common
in this area that underground
contractors often include "rock
clauses" in contracts that cover
potential additional labor costs
when facing unexpected granite
and other rock formations while
digging.

"We've done a lot of work in
the area, usually with excavators, and knew we would be digging in a mixture of granite and
dense blue granite," Sellers said.
"In those conditions, a person's
lucky if he or she can dig 200
feet in two weeks with excavators and hammers. It's a real
challenge and hard on equipment."
Sellers and Sons' site foreman
Baron Holly recognized this
challenge and the limitations it
would place on his crew's work
and equipment. His first step
toward a solution was to call
Vermeer Sales Southwest, Inc. to
inquire about a rock trencher.
"We've rented trenchers from
this Vermeer dealer in the past,
but this project was going to be
a lot more challenging because

it was entirely in rock," Holly
said. "The team at Vermeer Sales
Southwest did more than rent
a trencher to us; they pulled
samples of the rock we would be
digging in, sent it off to be analyzed, and then came back with
an equipment recommendation
to help maximize productivity."

Collaboration with
testing
The core samples were sent
from the Arizona jobsite to the
Vermeer Corporation rock lab
in Pella, Iowa, for extensive testing. Afterward, Sellers and Holly
were supplied with a rock lab
report that provided data on the
rock's hardness, abrasiveness
and how it may respond when
workers and machines encountered it.

With that information, the
dealer helped Sellers calculate
estimated production rates and
operating costs. The equipment
recommended was a Vermeer
T1155 Commander 3 trencher
with Kennametal RockRazor
TS19C "X" cutting teeth to perform in the rocky ground conditions.
Sellers and Sons quickly saw
results. Using the recommended equipment, they were able
to trench between 600 and 800
feet per day. With a 540-horsepower engine, the Vermeer trencher worked through both granite and blue granite formations
at an aggressive pace.
Alongside the 16-foot deep,
34-inch wide trench, the crew
dug an offset trench for the electrical conduit. Initially, Sellers

Just showing up on site isn't enough. We own, manage, and maintain a
large fleet of equipment with AEMP Certified Equipment Managers to avoid
slowdowns and increase overall productivity.

HORIZONTAL DIRECTIONAL DRILLING/DIRECT PIPE® SERVICES: River, road, and railroad crossings /
Shore approaches / Intersects / Installing steel, HDPE, and FPVC / Design/Build and EPC Services
Certified in Safety, Quality, and Environment: OHSAS 18001:2007, ISO 9001:2015 and ISO 14001:2004.
www.MearsHDD.net

UConOnline.com | MAY 2018

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Underground Construction - May 2018

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