United States
Environmental Protection
Agency
C1"
_.. _..
Research and Development
EPA-600/S2-83-064 Sept. 1983
&EPA Project Summary
Demonstration of Sewer
Relining by the Insituform
Process, Northbrook, Illinois
F. T. Driver and M. R. Olson
A full-scale study was undertaken of
the Insituform process for lining sewer
pipes to seal leaks and thereby prevent
the infiltration of groundwater through
leaky joints, cracks, and breaks. Such
infiltration can add significantly to the
amount of flow to sewage treatment
plants.
The study was done at the village of
Northbrook, Illinois, with two consec-
utive, 12-in.-diameter (31-cm) vitrified
clay pipe sanitary sewer segments that
were badly cracked. One was 150 ft (46
m) long, and the other was 432 ft (132
m) long.
Before the pipes were lined, average
groundwater infiltration was 19,500
gpd (74 mVday); after lining it was 100
gpd (0.4 mVday). The rate of exfiltration
was 3,800 gpd (14 mVday) before
lining and 270 gpd (1.0 mVday)
afterward. The Manning coefficient
after lining was 0.008 to 0.009. These
values are comparable to other plastic
such as PVC. Measurements of the
physical properties of the lining material
were also similar to those of PVC. A
realistic cost estimate cannot be ob-
tained directly from Northbrook because
this installation was a demonstration
project that limited the total length to
be lined and increased installation time
and cost for sewage bypass. But based
on cost data developed from previous
installations, the cost for Northbrook
would be $55/ft ($166/m).
This Project Summary was developed
by EPA's Municipal Research Labora-
tory, Cincinnati. OH. to announce key
findings of the research project that is
fully documen ted in a separate report of
the same title (see Project Report
ordering information at back).
Introduction
The infiltration of groundwater into
sanitary sewers through leaky joints and
cracks and breaks in sewer lines can add
significantly to the amount of flow to
sewage treatment plants, especially
during periods of elevated groundwater
levels caused by wet weather. Also,
during wet weather an inflow of water
into sanitary sewers can occur from roof
leaders and other types of drains. As a
result of infiltration and inflow (I/I),
treatment plants are overloaded and
operate less effectively.
Infiltration would be measurably
reduced with a rehabilitation technique of
reasonable cost that could seal all
unwanted openings in the pipe wall.
Such a method was conceived in England
more than a decade ago, but it has only
recently been introduced to the United
States, known commercially as "Insitu-
form,"* this method has a good potential
for completely sealing all leaks. Since
most installations can be made through
existing manholes, installation time,
traffic upsets, and surface disturbances
are reduced considerably.
To assess the effectiveness of Insitu-
form, a full-scale evaluation was under-
taken at the Village of Northbrook, Illinois.
Insituform Concept
The concept of the Insituform process
involves the use of a long tube or bag of
"Mention of trade names or commercial products
does not constitute endorsement or recommenda-
tion for use
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partially polymerized thermosetting resin
impregnated on a felt backing and closed
at one end This tube is inverted into the
pipe to be lined by filling it with cold
water. The felt tube has a thin film of
polyurethane on what is initially the
outside. Upon inversion of the tube into
the pipe, the polyurethane film forms the
pipe surface, which is very smooth. This
film also provides a leak-proof barrier to
the water being used for inversion. Aftf
inversion, hot water is pumped into tr
tube to cure the liner by completing
polymerization. The important installation
steps are outlined in Figure 1. After
The lining material is threaded
down the inversion bag
The end of the lining material is
opened up. turned inside out, and
clamped onto the steel 1/4 bend.
Manhole
ane
)
t
"NyJ
i^-
1 •
)
-X
')
1
Wood Bracing
Stainless
Steel Clamps
Pipe to be lined-
Water is pumped into the inversion
bag, and as the water pressure builds
up, the lining material starts to
turn inside out into the pipe to be
lined.
W
A 1
•^ J|
^1
As the end of the lining material
disappears into the inversion bag,
layflat hose is attached to its end.
This hose is pulled right through
the pipe, and is used to circulate
hot water
Layflat Hose
Water
«4r-
- 1
/
When the lining is fully cured, the
downstream end of the bag is
pierced to allow the hot,
circulating water to drain.
The ends of the lining material are
cut off 2 in. beyond the end of
the pipe. The pipe is air -tested using an
expanding stopper developed for the purpose.
The section of pipe that was removed is
trimmed to the correct length and joined
into the pipe using a resin, felt, and glass-
fiber bandage.
Pierce in Downstream
Manhole
'l
I f*
Downstream M.H
/
0
Figure 1. Steps in lining with Insituform.
2
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installation, the end of the tube is cut off
with a power saw, and the wall of the
manhole near the pipe is finished with a
sand-resin mixture. Reconnection of
service laterals is carried out with a rotary
cutter .For pipes that are too small to
enter, a remote-controlled television
camera-cutter combination has been
developed.
Installation at Northbrook
At Northbrook, two consecutive 12-in.-
diameter (31-cm) vitrified clay pipe
segments were lined Segment lengths
were 150 ft (46 m) and 432 ft (132 m).
Manholes we re located at the entrance to
the first segment, between the two
segments, and at the outlet of the second
segment. Two 6-in. (15-cm) service
laterals entered the first pipe segment
The sewer was a sanitary sewer installed
in 1962 and had many offsets and radial
and longitudinal cracks. Some sections
were deteriorated to the point of not being
circular
Before lining, the sewer segments
were cleaned well, since any remaining
debris would not be forced out during
inversion but would increase the rough-
ness of the lining, reduce flow capacity,
and reduce strength. Very sharp protru-
sions could break the liner and interfere
with curing.
The felt tube was built up from two 3-
mm layers of densely needled polyester
fiber. (Thickness can be increased by
adding 3-mm layers). Impregnation was
conducted at the site by filling the liners
with the appropriate amounts of a
catalyzed, thermosetting, isophthalic-
acid-based resin and passing the liner
through a system of conveyers and rollers
to wet a II of the felt thoroughly. Inversion
was carried out using a 19.7-ft (6-m)
static head. The two pipe segments could
have been lined with one length of liner
and one inversion, but two were used on
successive days to accommodate a large
number of interested observers.
The desired curing temperature for the
chosen resin was approximately 180° F
(82° C). The curing cycles for the two
segments are listed in Table 1. Consider-
able time was required to heat the water
to curing temperature. Cooling was
purposely slowed to an hour or more to
prevent rapid contraction, which might
cause separation of the liner from the
pipe. Small thermocouples placed be-
tween the original pipe wall and the liner
at both ends of the lengths being lined
were used to determine whether curing
temperature was being reached through
the total thickness of the liner. The
Table 1 . Resin Curing Cycles
Temperature Range
PC)
Curing Time
(hr)
Upper pipe segment:
55-160
160-185
185
185-100
13-71
71-85
85
85-38
0.75
0.5
2
1
Total
4.25
Lower pipe segment'
55-160
160-185
185
185-10O
13-71
71-85
85
85-38
Total
1.25
0.75
2
1.5
5.5
conditions listed in Table 1 would be
typical of most installations.
Results
The success of the lining process was
tested by observing both the infiltration
into the upstream pipe segment and the
exfiltration from the downstream segment
just before and after lining. The infiltration
test was carried out by plugging the
upstream manhold and measuring flow
over a weir at the downstream end of the
pipe segment. Groundwater levels were
approximately 14 in. (35 cm) above the
crown at the outlet. The average value of
infiltration was 19,500 gpd (74 mVday)
before lining and 100 gpd (0.4 mVday)
afterward. The small amount of inflow
after lining is believed to have resulted
from leakage at the upstream manhole,
since television inspection of the pipe
showed no breaks in the lining.
The exfiltration test was carried out by
plugging the line just above the manhole
at the upstream end of the pipe and the
line just below the downstream manhole.
The pipe segment was then flooded to 3 ft
(91 cm) above the crown at the upper
manhole The rate of fall of the water was
measured. Before lining, the rate of
exfiltration was 3,800 gpd (14 mVday),
and after lining it was 270 gpd (1.0
mVday). The small amount of exfiltration
after lining is believed to have occurred in
the manholes.
An indirect measure of the effectiveness
of lining was an obvious increase in the
leakage into the adjacent manholes
through cracks in their walls. This
observation confirms the experience with
sewer grouting methods, in which
leakage appears after grouting at points
that did not formerly leak. The cause is
ascribed to a higher groundwater level
resulting from elimination of the most
significant leaks. Where the condition of
manholes is questionable, their rehabili-
tation should also be considered.
One of the advantages claimed for the
Insituform lining of sewers is the in-
creased smoothness, with regard to
carrying capacity. The Manning coeffi-
cient was 0.008 to 0.009 after lining.
These values are comparable with those
for other plastic pipe such as PVC.
Accurate values for the Manning coeffi-
cient were not obtainable before lining, so
a comparison of maximum water-carrying
capacities before and after lining was not
possible at Northbrook.
A number of physical properties of the
lining material used at Northbrook were
measured and compared with PVC (Table
2).
This comparison indicates that the two
materials are very similar in their physical
characterstics.
Insituform Costs
Approximate costs for relatively long
length installations of Insituform are
Table 2. Properties of Insituform Compared with PVC
Property Insituform
PVC
Tensile strength (psi)*
Modulus of elasticity (psij
Flexural strength (psi)
Compressive strength (psi)
Coefficient of thermal
expansion (cm/ cm °C)
5,420
475.000
9,320
15,000
5.96 x 10~5
7,200
400, OOO
1 1,000
9,000
52 x ;o~5
"To convert psi to kN/m}, multiply by 6.895
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shown in Table 3. These figures include
the fabrication and installation of the
liner and cutting of openings to service
laterals Additions for pipe cleaning and
inspection and for bypass pumping of
sewage must be made as shown in
footnote in Table 3. In addition, there are
other relatively small costs for setting up
of equipment (mobilization) and for traffic
control
A realistic cost estimate cannot be
obtained directly from Northbrook because
this installation was a demonstration
project that limited the total length to be
lined and increased installation time and
cost for sewage bypass. But an estimate
can be made for Northbrook based on
Table 3 information. For lining the two
pipe segments (with $1,500 estimated for
mobilization and traffic control), the cost
would be approximately $55/ft ($ 166/m).
This estimate assumes that other sewers
in the area would be lined at the same
time to take advantage of the large-order
prices in Table 3.
Table3.
Insituform Costs*
Sewer
(cm)
155
31
47
61
Diameter
(m.)
6
12
18
24
Liner Thickness
(mm)
3
6
6
12
6
12
9
15
Cost Per
Linear Foot
($)
33
39
47
55
57
66
74
86
Cost Per
Linear Meter
($)
108
128
154
180
187
217
243
282
* Add $1.900 per line for bypass pumping Add $1.90 for 6-to 15-in.pipe,and$2.50for15-to30-m.
pipe per foot for preliminary cleaning and inspection.
At Northbrook, the condition of the
pipes was too poor to consider specific
point repair and grouting. Where the pipe
is severely deteriorated grouting cannot
be used. Had grouting been practical, it
would have been a cheaper alternative.
Grouting is not as effective as Insituform,
and in a number of documented cases it
has been essentially ineffective. The cost
effectiveness of grouting in terms of
actual I/I reduction can therefore be very
low.
The full report was submitted in
fulfillment of Grant No. R-806322 by the
Village of Northbrook, Illinois, under the
sponsorship of the U.S. Environmental
Protection Agency.
F. T. Driver and M. R. Olson were with Driver. Olson and Degraff Associates,
Rockford. IL 61104. F. T. Driver is now with Insituform of North America,
Memphis, TN 33118; and Mr. Olson is with Thomas I. Simmons & Associates.
Rochelle. IL 61068.
Richard Field and Robert Turkeltaub are the EPA Project Officers (see below).
The complete report, entitled "Demonstration of Sewer Relining by the Insituform
Process, Northbrook, IL." (Order No. PB 83-245 878; Cost: $7 7.50, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
Richard Field can be contacted at:
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Edison, NJ 08837
ftUS GOVERNMENT PRINTING OFFICE 1983-659-017/7173
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