Questar Gas and our contractor, Northern
Pipeline (NPL) of Phoenix, AZ, are committed to completing this
project safely and on schedule while minimizing as much as possible
any inconvenience to local businesses and residents. To accomplish
this, some work may be performed at night and on weekends. This
will reduce impacts on morning and evening commutes. We will adhere
to all county noise-reduction ordinances.
NPL has more than 40 years experience in 39 states building pipelines
in urban settings.
For pipe buried beneath streets or highways, construction may
require intermittent closures of one or more lanes of traffic.
Driveways also may be occasionally blocked by excavation work,
otherwise they will be plated to maintain access during business
hours and at night and on weekends.
Before construction starts in front of any home or business,
a representative will contact the owner or resident to discuss
options for maintaining driveway access. Signs notifying the public
that businesses remain open during construction are available.
To finish construction on schedule and as quickly as possible,
the project is divided into sections, or "spreads."
This allows multiple crews to work simultaneously at different
locations. Work zones can range from a single intersection to
several blocks long. At any one location the amount of time to
cut pavement, install new pipe and replace asphalt can range from
several days to several weeks.
The public can do its part to ensure construction proceeds safely
and on time by finding alternative routes, driving carefully in
construction zones and keeping children away from construction
Questar Gas works closely with city and state transportation
officials to ensure safety and minimize inconvenience to drivers
and pedestrians. However, for public safety it may be necessary
to temporarily close streets and sidewalks or restrict vehicle
and pedestrian traffic. As mentioned, driveways may occasionally
be blocked by excavation work. We will make every effort to keep
these inconveniences as brief as possible. Your patience is appreciated.
If you have questions or concerns, do not hesitate to contact
Following are brief descriptions of the steps involved in pipeline
removal and construction:
Locate buried utilities - The area below city streets
can be a maze of underground utilities. To avoid damaging these
facilities, a procedure known as potholing is used prior to trenching
to identify the exact vertical and horizontal location of existing
infrastructure, including the pipeline to be replaced..
Move existing utilities - Before trenching (see next step),
all water and natural gas service lines that cross the existing
pipe will be moved to a lower depth. This will minimize the risk
of interrupting water- or gas-service to individual homes or businesses
once actual construction begins.
Dig trench - After the pipe has been located and purged
of gas and service lines in the trench zone moved, the pavement
above the existing pipe is cut and removed. Then equipment is
brought in to dig the trench. The depth of the natural gas pipeline
trench will be determined by the location of the existing pipe
and other utilities. As the trench is dug, the soil is loaded
into trucks and hauled away for disposal in a designated landfill.
Remove old pipe - Sections of pipe to be removed are cut
into lengths, lifted from the trench, loaded onto trucks and hauled
away for proper disposal.
Deliver and "string" new pipe - New pipe is
manufactured and inspected to ensure it meets industry and federal
safety standards. Pipe sections are then delivered by truck to
the construction site where they are placed end-to-end (or "strung")
on skids adjacent to the trench. If necessary, a hydraulic machine
bends pipe sections to fit around obstacles or conform to the
direction of the trench.
Weld new pipe together and coat - Welding crews join the
sections of pipe together into a continuous length. Each welded
joint is visually inspected, x-rayed and then coated for protection.
Lower pipe into trench - Using one or more tractors, crews
lift and then carefully lower the welded sections of pipe into
the trench. Final welds are made to "tie-in" any unconnected
Backfill trench - Under streets, in place of the removed
soil, a mixture known as "flowable fill" is used to
backfill the trench. In other areas, the original soil is replaced.
Pressure test new pipe - After it's buried and before
it's put into service, the entire length of new pipe is hydrostatically
tested to ensure the integrity of the system. This is done by
filling the pipe with water, pressurizing the system above its
maximum operating conditions and holding the pressure for a specified
time. The pipe is drained, cleaned and dried before put into service.
Clean-up and restore ROW - The final step is to repair
the surface over the trench. If necessary, fences or sod may also
Directional bore - At some busy intersections, most water
crossings and under I-15, instead of trenching, crews will install
pipe by boring horizontally underneath the road, stream or canal.
The boring machine drills a hole from one side of the road or
stream. Pipe is strung on the other side and then pulled back