Underground Construction - August 2018 - 32

CURRENTLY@

CUIRE

Center for Underground Infr

CUIRE Leads Research Team for Phase I
of NASSCO CIPP Study

A four-month study on the review of published literature pertaining to chemical emissions
of styrene-based resin used in
the cured-in-place pipe (CIPP)
process, found that existing
studies do not adequately capture worker exposures or levels
in the surrounding areas to
which workers or citizens may
be exposed.
The study was commissioned
by the National Association
of Sewer Service Companies
(NASSCO) after a 2017 report
suggested CIPP workers may be
at risk to chemical air emissions
exposure. The literature review
is the first element in NASSCO's effort to obtain factual
information about any risks to
workers.
The study started last December and completed April 6,
2018, by researchers at UTA/
CUIRE and the Institute for Underground Infrastructure (IKT)
in Germany. The team determined that spatial variation of
concentrations, and variations
in concentrations with different
meteorological conditions, are
not well-determined.
Most of the steam-cure studies captured temporal variation
in emissions by measuring concentrations before, during and
after curing. The studies were
less complete in capturing spatial variation in concentrations,
measuring styrene around the
termination manhole, or inside
the manhole or sewer pipe itself.
Maximum values at the out32

AUGUST 2018 | UConOnline.com

let point and inside the terminal manhole ranged from 20 to
1,070 ppm -- levels that exceed
some exposure limits. However, since workers and certainly
the public should not typically
enter or stand directly at the
termination manhole in the exhaust plume, this information
is not very helpful.
At the steam-cured sites,
additional field measurements
of styrene concentrations surrounding the terminal manhole
are needed. Only four of the
steam-cure studies measured
concentrations at least three
feet away from the terminal
manhole, versus in the manhole
itself or in the exhaust plume.
On one project, employees
walked the construction area
periodically, but spent most of
the time in their work trucks
due to the cold weather. Hence,
these measurements were likely
not typical of worker exposures.
Additional worker exposure
data should be collected to
capture variability in source
emission rate, meteorological
conditions, and the worker's
location with respect to the terminal manhole.
Atmospheric concentrations
of compounds are functions
of the source emission rate,
meteorological conditions, and
the receptor location. Since concentrations are expected to vary
as a function of distance from
the manhole, measuring at few
locations gives an incomplete
picture. In addition, concentra-

tions are expected to vary with
wind speed and direction, so
one day's measurements do not
capture levels under differing
meteorological conditions.
These earlier studies also do
not adequately capture variations in emission rates from
different kinds (different diameters, lengths, etc.) of pipes.

The overall results of the project
at UTA/CUIRE/IKT indicated
that the 21 papers reviewed
have questionable methodologies and, therefore, the results
presented are not conclusive.
The researchers recommended
additional sampling, and data
evaluation and analysis, as a
second phase of this study.

Update on Structural Design
Methodology for Spray
Applied Pipe Liners
To reduce emergency projects and impacts to the traveling public,
departments of transportation (DOTs) can use spray-applied pipe
linings (SAPLs) to renew deteriorated gravity stormwater conveyance
conduits and culverts, provided they are discovered prior to loss of
soil-structure interaction. An SAPL is a standalone application that
inhibits further deterioration and can structurally renew severely damaged culvert and drainage structures. The primary materials
used for SAPL generally fall into two broad categories of cementitious materials and polymers such as epoxies, and polyurethanes and
polyureas.
The primary objective of this two-year study is to develop design equations for structural renewal of gravity stormwater conveyance culverts with both cementitious and polymer materials.
Both circular and arch shapes with spans larger than 36 inches

Soil box testing for an arch-shape SAPL with three thicknesses of same material

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Underground Construction - August 2018

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