Underground Construction - November 2017 - 44

REHABTECHNOLOGY
By Larry Kiest, Jr.

CIPP Lateral Sewer Rehabilitation:
Does It Perform As Expected?

Editor's Note: This is the fourth installment of an occasional series of articles
discussing long-term performance needs, capabilities and requirements of various rehabilitation technologies.

A major challenge faced by nearly every utility is how to address its aging
underground infrastructure. Sewer pipes are failing from coast to coast
as America finds itself on a fast track to replace or renew sewer collection
systems. A major driving force is the mandate set forth by state and federal regulators that require utility owners to renew their systems so they
are watertight.
Today, if a utility uses State Revolving Loan Funds (SRF) to pay for
its sewer rehabilitation project, the design must be justified based on
life-cycle cost analysis. This requirement is imposed by legislation passed
by the U.S. Congress in 2014 known as the Water Resource Reform and
Development ACT (WRRDA). Even without the requirement for such an
analysis, a responsible utility should perform one to ensure the best value
for the rate payer's investment. The days of ground water infiltrating and
overloading pipes, pumps and wastewater treatment plants at public expense is now a priority to correct.
Today, more and more engineers have experienced the limitations and
capabilities of cured-in-place pipe (CIPP) and understand the need for
water tightness, as well as the need for long-lasting performance. CIPP is
the most sought-after trenchless technology. However, case studies have
shown that CIPP rehabilitation of sewer mains allows continued leakage,
as groundwater tracks behind the liner and reenters the sewer at service
connections.
Likewise, service lateral pipes have deteriorated and must be renewed
and sealed. Studies have shown that up to 70 percent of extraneous water
can be derived from defective lateral pipes. In order for a rehabilitated
system to be watertight, a holistic approach must be used, which includes
addressing the main pipe, manholes and similar structures, service lateral
pipes and cleanouts.
When materials and methods designed to rehabilitate and seal up a
system by adherence to established engineering industry standards are
commissioned, many utility owners are experiencing "good as new results" on their projects. In other words, they are receiving performance
comparable to new pipe construction.
The most difficult challenge utility owners must overcome is the sales
pitch for low-cost, short-lived solutions by many providers and contractors alike. The notion of CIPP bonding to fats, oils and grease (FOG) in
a wet sewer pipe for 50 years has led to millions of dollars going down
the drain. The industry has responded by developing more appropriate
and stringent specifications and industry standards for CIPP requiring high-quality construction materials, including CIPP gasket seals, to
achieve "as good as new" results.

Industry standards
The primary objectives for renewing a sewer collection system should include both renewed structural integrity and to provide a long-term watertight seal. To be effective and meet those objectives, one must first understand the technology and apply the correct industry standards. Those who

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have been involved
with pipeline rehabilitation are familiar
with the ASTM F1216
standard, the granddaddy of standards for
the CIPP industry. But
being familiar with a
standard doesn't necessarily mean one truly
understands what the
standard entails.
ASTM F1216-16,
"Standard Practice
for Rehabilitation of
Existing Pipelines and
Conduits by the Inversion and Curing of
a Resin-Impregnated
Tube," has guided the
CIPP industry since it
was published in 1989.
The F1216 standard is
a practice for installing
CIPP in mainline pipes
that have easy access
from manholes located at each end of the
sewer pipe. The F1216 Mainline CIPP with
Leaking Lateral
standard makes no
Connection
mention of robotically
positioning a lateral
Failed Top
connection liner from
Hat Lateral
within the main pipe,
Connection
and makes no mention
of providing a longterm seal utilizing a
pipe gasket.
Too often, there is
confusion as technology providers and contractors alike make the
statement "my lateral
liner meets F1216."
What people really
should be saying is, "My lateral liner meets the non-mandatory design of
F1216 found in appendix X1."
Did you know that F1216 section 8.2 actually includes an allowable
leakage rate? The F1216 standard allows for 400 gallons of leakage per
day, per mile for an 8-inch pipe. That equates to 146,000 gallons of leakage per year, per mile while maintaining compliance to the standard.
There is so much in-depth information relating to CIPP that to really unUnderground Construction November 2017

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Underground Construction - November 2017

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