Rehabilitation of Wastewater Collection and Water Distribution ...

For other lining systems, the suitability of the liner material and the installation process for a particular
application must be determined by broadly applicable testing standards for the materials used and/or
proprietary testing carried out by the manufacturer for the pipe lining system. Depending on the materials
and the application, this combination may result in a very clear and consistent QA/QC approach or it may
leave gaps in the QA/QC coverage for particular applications.
QC procedures for the various technologies discussed herein are typically given to the installation
contractor by the system manufacturer. To further reinforce a system’s commitment to having a quality
installation, the manufacturers will develop an ASTM installation standard for their system. Appendix E
provides examples of the current extent of coverage of industry-wide standards for rehabilitation systems.
QA is the responsibility of the system owner or the designated project engineer. Whether utilizing
prescriptive or performance specifications, it is important that this communication with the installer
convey what QA testing will be performed, and then the contract documents need to follow through on
this testing. Too often, trenchless technologies have specifications for reasonable assurance testing, but
those overseeing the project do not perform the testing. Samples of the finished installation need to be
taken to confirm that the minimum mechanical properties have been achieved or have gone unaltered. Fit
and finish should be evaluated in light of the prior condition of the host pipe and the system being
installed. It is generally preferable that the relationship with the testing laboratory providing the results of
the testing resides between the owner and the laboratory; not the contractor and the laboratory.
Current QA testing has its drawbacks. Most CIPP projects require restrained samples to be taken from
cured liners where the liner is inflated in a pipe sleeve of like diameter either at an intermediate manhole
or the receiving end manhole so that the approximate thickness of the liner during installation after the
rigors of its placement can be captured to provide determination of the as-built mechanical properties of
the newly installed CIPP. These samples must be properly taken to provide an accurate representation of
what is in the ground. They must rest horizontally, with a sufficient heat sink, to simulate the ground
during the curing process. The restrained samples are taken in manholes or other access locations and
thus the heat loss and/or moderation provided by the host pipe and pipe embedment materials must be
replicated by placing a “soil envelope” on the sample tube. Often this is not achievable due to the size
and shape of the receiving manhole. Currently there is a change before the ASTM F17.67 sub-committee
to add ultrasonic thickness testing as an alternative to using the thicknesses derived from the restrained
sample. A method of non-destructive determination of the finished mechanical properties also is lacking.
Ultra-wideband pulsed radar systems, ultrasonic measurements, and before-and-after laser profiling are
potential methods to provide definitive finished thickness information. However, none of these methods
is fully developed for in-pipe liner thickness measurements.
Water-tightness is another issue confronting trenchless rehabilitation technologies. CIPP, which is seen
as a monolithic structure, from time to time has “leaks through the wall.” Joints in just installed
thermoplastic panel systems have leaks, especially when machine installed in non man-entry size piping.
One question that should be resolved is how leakage testing should be carried out and what level of
leakage is acceptable, both from a life-cycle view of the installation and an inflow and infiltration (I&I)
perspective. Some recent inspection systems (e.g., the FELL electro-scan system) provide an effective
means of finding and quantifying leaks and, perhaps more importantly, potential leaks that are not
currently active – but only in nonconductive pipe systems.
As the governing patents expire on many aspects of rehabilitation technologies, more companies are
encouraged to enter the marketplace and compete with the established technology providers. This
provides increased competition – leading in general to lower prices – but it also may provide an incentive
to cut corners on QC as part of the price competition. Also, new entrants into the rehabilitation
marketplace may not have as well developed technical “know how” (staff education level and
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