Underground Construction - October 2022 - 22

CIPP Emission Studies Update
By Lynn Osborn, NASSCO Technical Advisory Council Member, LEO Consulting
It has been over five years since NASSCO began
the program of evaluating cured-in-place pipe (CIPP)
air emissions of volatile organic compounds (VOCs)
and the effect on worker and public safety. Through
an industry workgroup consisting of several highly
respected industry organizations, NASSCO
commissioned three third-party studies beginning
with Phase 1 in late 2017. Phase 1 was awarded to
the Center for Underground Infrastructure, Research
and Education (CUIRE) at the University of TexasArlington
and was led by Dr. Mohammad Najafi. The
objectives of Phase 1 were a literature review of
past CIPP emission studies and a scope of work for
Phase 2, field studies.
Phase 2 was awarded to the Trenchless Technology
Center (TTC) at Louisiana Tech in the summer of
2018 and was led by Dr. Elizabeth Matthews. The
study consisted of emissions testing at nine different
air inversion, steam cure CIPP jobsites. The nine
installations differed in sewer diameter, sewer
length, climate and geographical location. Although
the testing detected several VOCs, styrene was the
only compound of interest found at concentrations
that had the potential to pose health risks, and two
primary locations on CIPP sites were of particular
concern: 1) emission locations, particularly the
exhaust discharge; and 2) the wet-out tube storage
unit. TTC made recommendations to mitigate safety
concerns near the exhaust discharge. However, a
detailed investigation of the wet-out tube storage
unit was not within the scope of the Phase 2 study,
and TTC recommended that suitable personal
protective equipment (PPE) be worn by workers
unloading wet-out tubes. Additionally, TTC
recommended further investigations in and near the
storage unit to better define safety protocols. Copies
of both the Phase 1 and Phase 2 reports are
available on nassco.org/safety/styrenesafety.
Phase
3 work, also at the TTC, began in the
summer of 2021 and is being led by Dr. Shaurav
Alam. The overall objective of Phase 3 is to quantify
possible health hazards to workers in the vicinity of
and inside the wet-out tube storage unit and to
develop safety protocols to mitigate any risks to
worker safety. Phase 3 was broken into three
stages:
* Stage 1 -Thermoplastic coating breakthrough
* Stage 2 - Storage unit simulation in a chest
freezer
* Stage 3 - Field work in active wet-out tube
storage units
In Stage 1 several different thermoplastic tube
coatings were tested for the rate of styrene
breakthrough. When a wet-out tube is placed inside
an empty storage unit for shipment to the jobsite,
the styrene level inside the storage unit is typically
low. However, as time passes, the styrene level
increases. This happens because styrene from the
thermoset resin inside the wet-out tube permeates
through the coating on the outside of the tube.
Several different thermoplastic materials are
currently being used for tube coatings, and in Stage
1 seven different types of coatings were blind
tested. A special two-chamber vial was developed,
and resin was added to the lower chamber.
https://www.nassco.org/safety/styrene-safety/ https://www.nassco.org/safety/styrene-safety/
Underground Construction - October 2022

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