Underground Construction - December 2017 - 12

Unique Undergrounding Program
and time consuming to repair, frequently requiring additional crews
to hand-carry poles, wires and
climb poles while bucket trucks
and auger trucks are parked on the
roadway because they cannot gain
access to where the repairs need to
be made.
"These labor intensive repairs
can sometimes take days and pull
resources from other restoration
efforts," Bradshaw said. "Eliminating these difficult-to-repair
locations will lead to a significantly
more efficient restoration.
"We believe that a program
aimed at burying only the most
outage-prone tap lines will cost
less than three percent of the 'underground everything' estimate
from 2005."

Targeting areas
To select which overhead tap lines
to convert, Bradshaw said Dominion uses a data-driven process that
begins with a review of 10 years of
outage data for each tap line. Data
is used to develop an events-permile metric to ensure selection of
a group of tap lines that have the
greatest impact for the lowest cost.
"We take this data and then
perform a site review to ensure
that the tap lines are, indeed, good
candidates for conversion to underground," said Bradshaw.
Horizontal directional drilling
(HDD) is used almost exclusively.
"Directional drilling minimizes
impact to our customers' properties," Bradshaw said. "This installation method, as opposed to open
trenching, has been key to customer acceptance and willingness to
install underground lines in their
area. These projects serve established properties where customers
have installed sheds or built fences
and planted gardens. The ability to
safely install facilities using trenchless technology allows for minimal
impact on established properties."
Construction is being performed by five contractors assigned to seven geographic areas
throughout the Virginia service

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Cost always has been the
primary roadblock for
undergrounding - it costs
more to bury power cable
than to suspend it from
poles. However, considering
repeated replacements
in storm-prone areas,
along with other factors,
many power companies
are considering ways to
go underground in areas
with older, established
infrastructure.
territory.
"Each contractor," said Bradshaw, "provides design, right-ofway and construction services.
While they are installing new
underground facilities, they are
also securing easements and completing designs for future work.
They build their own backlog and
in many ways are responsible for
their own success. We have been
very pleased with our contracted
partners. They also have a high
regard for the customer experience
associated with the program."
Bradshaw said that as expected,
converted tap lines have seen significant improvement in reliability, going from an annual average
outage duration of 372 minutes
prior to underground conversion,
to less than two minutes after conversion.
"As conversions continue," he
said, "we believe we will have a
slight decrease in the number of
customers impacted while having
a significant reduction in the number of work repair locations, so we
expect our traditional restoration

Undergrounding Impact On
Storm Restoration
As a result of the underground conversions, the reduction in work
repairs following storms reduces outage times for almost all customers, said Alan Bradshaw, Dominion Energy director of electric
distribution-underground.
Storm restoration usually includes four overlapping stages:
* Response to downed wires (public safety).
* Restoration of critical infrastructure and main feeders.
* Restoration of tap lines.
* Restoration of individual transformers and services.
"Certainly, the back end of the restoration is shortened because
of the undergrounding of tap lines, but the biggest bang for the
buck comes from being able to move resources to the actual job of
restoration and repair sooner," Bradshaw said. "By undergrounding overhead lines, there are fewer downed wire calls to respond to
at the front end of the restoration.
"Resources that would have spent time ensuring downed wires
are de-energized can now move to restoring main feeders and,
therefore, large blocks of customers sooner.
"Perhaps the biggest impact comes from the fact that we are
converting lines all across our system. After a storm, there will be
differing levels of impact and damage across the system. Those
areas that are less impacted will have even less repairs to make as
a result of the underground conversions. The resources that were
working in these less-impacted areas can now be reallocated sooner to the areas that were more heavily impacted, leading to large
blocks of customers being restored faster. Even at this early stage,
we are seeing evidence that the total length of restoration following large storm events is decreasing."
curve will look different as we complete the program."

Satisfied customers
Post construction surveys show
that Dominion customers are
"very" satisfied with the underground program, scoring more
than 4.5 out of 5.
"We make it a priority," Bradshaw explained, "to communicate
regularly with customers impacted
when securing easements for new
underground facilities and to review construction schedules, safety and landscaping once a project
is complete.
"We use a variety of communication mediums including letters,
postcards, telephone calls and door
hangers. We have also created a
portfolio of reference pieces on
topics such as easements, meter

base conversions and how directional boring mitigates impact to
tree roots."
On larger projects, Dominion
hosts community informational
meetings to review proposed layouts and discuss project schedules.
"We have had an overwhelmingly positive response to easement
requests, which is critical to the
completion of any project," said
Bradshaw. "We recognized early on
that respecting personal property
was important to our customers,
so we make a commitment to leave
private properties at least as good
as we found them.
"Because we rely so heavily on
vendors to help us with the program, we are very conscientious
about sharing feedback with our
contractors and hold them to the
same standards we hold our own
employees."
Underground Construction December 2017

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Underground Construction - December 2017

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