Streamline - Fall 2017 - 27

Ground movement. Earthquakes
and ground movement can cause connection failure, beam or shear breaks
and cracks along the length of a pipe.
A region's geographic phenomena can
greatly determine how much the ground
moves. Some regions regularly experience ground movement, whereas others
are relatively stable.
With its location on the San Andreas
Fault, California experiences dramatic
earthquakes, causing the ground to move
suddenly and with great force. It's no
surprise that a high level of restraint
is used on water and sewer pipes in
many areas along the West Coast.
Although other parts of the country
located on major fault lines can incur
less dramatic ground movement, such
movement can still stress water and
wastewater pipelines.
The New Madrid fault line is particularly noteworthy, as it can affect more
than 15 million people in Alabama,
Arkansas, Illinois, Indiana, Kentucky,
Mississippi, Missouri and Tennessee.
The Ramapo Fault runs about 70 miles
through New Jersey, New York and
Pennsylvania. Ground movement caused
by this fault has stressed piping systems
even without full-blown earthquakes.
In addition, scientists have warned of
earthquake risk from hydraulic fracturing operations.
Ground movement can also be caused
by seasonal weather changes, especially
during winter and spring. The ground
freezes in the winter and ice melts in
the ground during the spring; both
cause major ground shifts. Ground
movement is also correlated to extreme
weather changes.
Other ground stresses. Pipe also can
be affected by the ground in a variety
of other ways. The amount of ledge or
rock in the ground can negatively affect
piping. If a high level of ledge is in the
ground, even slight movements caused
by traffic or weather can cause piping
to break. Conversely, swampy areas
with ground that is moist and spongy

moves easily and can also stress pipes.
There's also a long list of other environments that lead to pipes uncoupling,
including tidal areas, bridge crossings
and pipes running under water. For
these circumstances, it's best to consult with engineers on how to evaluate
the risks associated with a distribution
system's environment.
Techniques for restraining pipe

Several techniques are available to
restrain pipes. Each method has distinct advantages and disadvantages with
regard to cost, time and labor.
Rodding. Until relatively recently,
rodding was the most commonly used
technique for restraining pipes. It's
effective and used in underground and
aboveground installations. Thrust rods
are usually all-thread rods with washers and bolts that dog-ear into connections for restraint. Some installers even
use rodding for flanged connections.
The main drawback of rodding is cost,
as material costs are high. The time to
install these rods is also a concern.
Thrust blocks. Thrust blocks are
engineered concrete blocks placed at
either end of a line of pipes or beside a
joint to prevent pipes from pulling out.
Whereas rodding strings pipes together
so they stay connected, thrust blocks
provide a solid mooring at the end or a
bend in a pipeline to prevent movement.
Although thrust blocks are typically
made of concrete, it's not uncommon
to find makeshift versions made from
steel posts, pressure-treated wood posts,
or bags of ready-made concrete.
The materials used to make thrust
blocks are inexpensive, but it takes time
to construct the blocks, pour the concrete and wait for it to cure. The water
supply must be turned off to ensure the
concrete cures properly before connecting the pipe. Although money is
saved on materials, additional costs are
incurred in terms of the time it takes
for the job to be completed. In addition,
there isn't always enough space for thrust

blocks-for example, where utility lines
are in close proximity.
Another way concrete is used to
restrain pipes is by pouring concrete
on the connection itself. This can be
effective, but repairing the connection
in the future can be tricky. At minimum,
a pipe must be surrounded by plastic
before the concrete is poured on it. If the
plastic cover isn't applied, the entire pipe
and connection will need to be cut out
and replaced when repairs are required.
Mechanical restraint devices and
sleeves. Mechanical restraints and
sleeves involve connecting a sleeve using
multiple lugs. Several mechanical products like this are on the market, and it's
a great way to join pipe. However, it's a
time-consuming process. The larger the
mechanical restraint device, the more
bolts there are to tighten. The technique
is particularly effective for large-diameter pipes that need significant reinforcement to stay connected.
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27


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Table of Contents for the Digital Edition of Streamline - Fall 2017

From the President: Accomplishment
From the Executive Director: Time Flies…
VRWA Said “Goodbye” to Board Member and Friend Roy Markham
Basic Management Skills
Lessons from Louisiana
Planning for the Future
The 2017 Virginia Water Resources Progress Report
The Benefits of Pipe Marking for Water and Wastewater Facilities
Water and Environmental Programs
Recipe for Sustainably Managing Utilities
When and How to Use Piping Restraints
NRWA Recap
Throwing My Loop: Cowboy Up…
VRWA Member Corner
eLearning Benefits
Membership Application
Benefits for VRWA Members
Board of Directors
VRWA Committees
Index to Advertisers/Ad.com
Streamline - Fall 2017 - Intro
Streamline - Fall 2017 - cover1
Streamline - Fall 2017 - cover2
Streamline - Fall 2017 - 3
Streamline - Fall 2017 - 4
Streamline - Fall 2017 - 5
Streamline - Fall 2017 - 6
Streamline - Fall 2017 - From the President: Accomplishment
Streamline - Fall 2017 - 8
Streamline - Fall 2017 - From the Executive Director: Time Flies…
Streamline - Fall 2017 - 10
Streamline - Fall 2017 - VRWA Said “Goodbye” to Board Member and Friend Roy Markham
Streamline - Fall 2017 - 12
Streamline - Fall 2017 - Basic Management Skills
Streamline - Fall 2017 - 14
Streamline - Fall 2017 - Lessons from Louisiana
Streamline - Fall 2017 - 16
Streamline - Fall 2017 - 17
Streamline - Fall 2017 - 18
Streamline - Fall 2017 - Planning for the Future
Streamline - Fall 2017 - The 2017 Virginia Water Resources Progress Report
Streamline - Fall 2017 - The Benefits of Pipe Marking for Water and Wastewater Facilities
Streamline - Fall 2017 - 22
Streamline - Fall 2017 - 23
Streamline - Fall 2017 - Water and Environmental Programs
Streamline - Fall 2017 - Recipe for Sustainably Managing Utilities
Streamline - Fall 2017 - When and How to Use Piping Restraints
Streamline - Fall 2017 - 27
Streamline - Fall 2017 - 28
Streamline - Fall 2017 - 29
Streamline - Fall 2017 - 30
Streamline - Fall 2017 - NRWA Recap
Streamline - Fall 2017 - 32
Streamline - Fall 2017 - Throwing My Loop: Cowboy Up…
Streamline - Fall 2017 - 34
Streamline - Fall 2017 - VRWA Member Corner
Streamline - Fall 2017 - 36
Streamline - Fall 2017 - eLearning Benefits
Streamline - Fall 2017 - Membership Application
Streamline - Fall 2017 - Benefits for VRWA Members
Streamline - Fall 2017 - 40
Streamline - Fall 2017 - VRWA Committees
Streamline - Fall 2017 - Index to Advertisers/Ad.com
Streamline - Fall 2017 - cover3
Streamline - Fall 2017 - cover4
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