Underground Infrastructure - July 2023 - 22

Rehab Technology
The actions taken simulate the uncured liners in the refrigerated
transport truck prior to opening the doors at a construction site.
Field study
To perform the field study, researchers visited several liner
installations for the purpose of monitoring the uncured liner
transport truck. Modifications made to the refrigerated truck,
to have PIDs onboard in the cab, consisted of drilling holes in
the refrigerated area and running Teflon tubing to the PIDs
that were safely secured at the passenger seat.
At each installation site, measurements of styrene emission
were taken each time the doors opened to install a liner. Data
was measured at the back of the truck from the ground and
chest height at the middle and front of the chamber. Also noted
was each time the door opened to load and unload the trash left
over from the installation.
TABLE 1. Summation of maximum styrene concentrations
Coating
Material
PU (15 mil)
PP (17 mil)
PU (24 mil)
Breakthrough
Point Time
1 Day
2 Days
6 Days
Measured Max
Conc. (PPM)
396
305
362
Modeled Max
Conc. (PPM)
410
305
397
TABLE 2. Summarization of liner characteristics
Liner
Installation
Number
1
2
3
4
5
6
Coating
Material
PP
PP
PP
PP
PP
PP
Coating
Thickness
(mil)
17
17
17
17
17
17
Thickness
(mm)
6
6
6
6
6
6
% Resin by
Storage Volume
5.6
5.6
5.6
Date
Time
Liner Diameter
(in) / Wet Tube
Length (ft)
7.75/353
7.75/246
7.75/106
10/356
7.75/305
7.75/50
Estimsted
Resin
Weight (lbs)
962
671
289
1200
831
136
7/20/22
12:02 AM
12:03 AM
12:05 AM
12:10 AM
12:15 AM
12:21 AM
12:26 AM
12:35 AM
12:45 AM
12:55 AM
1:00 AM
1:22 AM
1:23 AM
Action
Opened Door (Installation)
Spot Check Reading 1
Spot Check Reading 2
Spot Check Reading 3
Spot Check Reading 4
Spot Check Reading 5
Spot Check Reading 6
Spot Check Reading 7
Spot Check Reading 8
Spot Check Reading 9
Spot Check Reading 10
Spot Check Reading 11
Spot Check Reading 12
Lab results
The results of the lab scale study show the concentration of the
measured styrene levels versus the amount of time. The three
liners that had readings taken were: 15-millimeter thick polyurethane
(PU), 17-millimeter thick polypropylene (PP), and
24-millimeter thick PU. Consistent styrene-to-volume ratios
were used for all three tests.
IMAGE 5 is an example of the styrene release over time and
TABLE 1 summarizes the overall lab study results.
As expected, the thinner, 15- and 17-millimeter, liners allowed
for a quicker breakthrough time, both being in the first
two days. However, the 24-millimeter did not see any breakthrough
until the sixth day of testing.
It should also be noted that the 24-millimeter liner never
saw a decrease in concentration, whereas the other liners saw
TABLE 3. Installation 2 and 3 details and readings
Spot Check
Concentration (PPM)
-
258
120
50
44
75
56
68
44
35
37
32
26
IMAGE 2. PIDs.
IMAGE 3. Example of an uncured liner.
22 JULY 2023 | UndergroundInfrastructure.com
IMAGE 4. Refrigerated truck used for wetted
out liner transportation.
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Underground Infrastructure - July 2023

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