United States
Environmental Protection
Agency
Water Engineering Research
Laboratory
Cincinnati OH 45268
_
"x
Research and Development
EPA/600/S2-85/131 Jan. 1986
SERA Project Summary
Demonstration of Service
Lateral Testing and
Rehabilitation Techniques
C. H. Steketee
New equipment and techniques were
used to repair service lateral piping in
two sanitary sewer basins in Salem,
Oregon. The object was to reduce
infiltration and inflow (I/I) significantly.
The project included identifying, testing,
inspecting, and repairing the faulty
piping.
The importance of repairing service
laterals was well demonstrated. If these
are faulty, particularly near the sewer
main, repairing mains and manholes
will do little to reduce peak l/l's. No
single repair method was best for all
service lateral installations.
This Project Summary was developed
by EPA's Water Engineering Research
Laboratory, Cincinnati. OH. to an-
nounce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
Studies were conducted from 1981
through mid-1984 to determine how
municipal sanitary sewers in Salem,
Oregon, could be repaired to reduce
infiltration and inflow (I/I). For many
years, Salem's sewer system has col-
lected large amounts of I/I during wet
weather. These wet weather flows in-
termittently exceed the hydraulic capac-
ities of the sewage collection and treat-
ment systems, causing raw sewage
bypasses into storm drainage systems,
receiving streams, and occasionally onto
city streets. Previous city efforts to correct
these situations generally have not re-
sulted in large demonstrable I/I reduc-
tions.
In late 1981, the city decided to repair
the sewers in two small sewer basins and
to measure the results carefully. Flows
from the basins were monitored during
the wet weather months before, during,
and after repair work was done. Two
sewer basins with large volumes of I/I
were selected—the Skyline and the
Missouri basins. Both drain to manholes
where flows can be readily measured.
The Skyline basin was chosen because
most sewers there are constructed of
rubber-ring-jointed concrete pipe similar
to much Salem piping built since 1960.
The Missouri basin was chosen because
sewers there are built of concrete-mortar-
jointed pipe similar to most sewer piping
installed in Salem from 1940 to 1960.
For both basins, the project included
identifying, testing, inspecting, and re-
pairing faulty service lateral piping. These
efforts required the use of new equipment
and the development of new techniques.
Annual precipitation in Salem averages
40 in., 70 percent of which falls between
November 1 and April 1. The topography
of both sewer basins is low to moderately
sloping. Red clay-loam soils of low per-
meability predominate. Winter rains
result in groundwater levels near the
ground surface. Since the percolation of
precipitation into the deep soil strata is
slow, most mid-winter precipitation runs
off.
Both sewer repair projects were under-
taken as cooperative ventures of the City
of Salem, Westech Engineering, Inc., and
Gelco Grouting Service. The City of Salem
crews performed mainline TV inspections,
smoke stesting, mainline grouting work,
and manhole repair work. Westech Engi-
neering, Inc., organized and guided both
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projects, collected data, and prepared the
reports. Gelco crews tested, inspected,
and repaired service lateral piping.
The Skyline Basin
Sewer Repairs
The Skyline basin is a 67-unit sub-
division served by 2,584 ft of rubber-ring-
jointed concrete pipe installed between
1964 and 1966, and 745 ft of PVC pipe
constructed in the late 1970's. Almost all
concrete sewer pipe had been previously
tested and chemically grouted by city
grouting crews; yet peak I/I flows meas-
ured 560,000 gpd during a storm in
January 1982 at 3:00 a.m., when very
little domestic sewage was contributed.
When the sewers were eventually re-
paired, they still contributed 411,000 gpd.
Various investigations of pipe condi-
tions were made. During the fall of 1 981,
flow monitoring and recording equipment
was installed in the downstream man-
hole, and it has been maintained there
during the wet weather months ever
since. All sewer mains were TV-inspect-
ed, and each main joint was air tested.
Only 1 5 faulty main joints were discover-
ed. The sewers were smoke tested, but
only one service lateral leak was found.
Flows were measured at each manhole at
night between 12:01 and 6:00 a.m. during
storm periods to determine the amount of
I/I contributed by each section of sewer
main. I/I contributed by leaking manholes
was also measured. The I/I entering
mams and manholes was found to be
small. Most service laterals were con-
structed of 4-in., rubber-ring-jointed,
concrete pipe.
Property owner permission was ob-
tained to install service lateral cleanouts
adjacent to each house where leaking
service laterals had been identified. Ex-
cavations were made by hand, and ABS
plastic service cleanouts were installed.
Next, plugs were inserted through the
cleanouts, and a mainline packer normally
used for mainline grouting work was
centered over each service tee so that
each service lateral could be air-tested.
Of the 31 tested, 28 failed. Hydrostatic
water tests were performed on each
lateral at the same time. In all but one
case, the hydrostatic test and the air test
results were identical.
Next, the 28 faulty service laterals were
TV-inspected by rodding a 1.5-in.-diam-
eter TV camera down the service piping
from the recently installed cleanouts.
These inspections revealed service piping
that was generally in good structural
condition. Few visible leaks or broken
pipes were discovered. These inspections
raised suspicions that many service lat-
erals were leaking at their connections to
the sewer main. Thus the downstream
3-or 4-ft section of each faulty service
lateral was isolated and air tested. Nine-
teen leaked. Because those faults were
immediately adjacent to the main, they
were considered to be major I/I contrib-
utors.
Repairs were subsequently made to the
Skyline sewer system. Leaking manholes
and joints in sewer mains were sealed by
chemical grouting. Faulty service laterals
were repaired with a variety of tech-
niques, most of which involved chemical
grouting. A new innovation, developed by
Westech/Gelco and nicknamed "the
snake," was used to repair most faulty
service laterals. This equipment consisted
of a flexible rubber cylinder that had a
pneumatically operated apparatus to pro-
pel the unitthrough service lateral piping.
The equipment was used to systematically
isolate 7-ft sections of service lateral
pipe, to perform air tests on the isolated
piping, and to seal leaks using chemical
grouting.
After the initial repairs were completed,
peak I/I volumes of 150,000 gpd were
measured—a 63-percent reduction from
the original 411,000 gpd. In two sections
of sewer main, only mains and manholes
were repaired, not service laterals. This
step was taken to see how repairing
adjacent sewers affected the I/I collected
by these two sewer sections. Although
overall flows were greatly reduced, the I/I
collected by these two sewers increased
by 208 percent in one section and de-
creased by 43 percent in the other.
Eventually, most of the remaining faults
were repaired. Peak I/I flows from the
repaired basin were reduced by approxi-
mately 92 percent.
Because initially the mains and man-
holes were relatively watertight in the
Skyline basin, more than 90 percent of
the peak I/I flow was attributed to the
service laterals. TV inspections of sewer
mains during high groundwater condi-
tions revealed most faulty service laterals.
The most significant service lateral faults
were those immediately adjacent to the
main, where sheared tees or leaking
joints probably resulted from inadequate
compaction of bedding materials beneath
the service tee and service piping. During
high groundwater conditions, some of
these faults contributed more than 50
gpm I/I.
The cost of repairs to the Skyline sewer
basin totaled about $70,000, not includ-
ing the cost of flow monitoring, investi-
gations for scientific purposes, report
writing, and other similar tasks. Numer-
ous difficulties were encountered in
testing, inspecting, and repairing service
lateral piping, but most of these have
since been overcome.
The Missouri Basin Sewer
Repairs
In the Missouri basin, 220 homes are
served by 13,345 ft of concrete-mortar-
jointed sewer mains installed in 1955
and 1956. Although investigations into
the condition of the Missouri basin sewers
began in the fall of 1981, repairs to this
sewer system did not begin until 1983.
The results of the work done in the
Skyline basin had come to the attention of
the U.S. Environmental Protection Agency
(EPA) officials, who were interested in
further developing and evaluating tech-
niques and equipment for locating, test-
ing, inspecting, and repairing faulty
service laterals. EPA entered into a
cooperative agreement with the City of
Salem, offering financial aid for sewer
repair work in the Missouri basin. A
variety of techniques and equipment for
service lateral work were to be used and
evaluated as part of the Missouri basin
repair program.
The investigations of the Missouri
sewers paralleled the Skyline investiga-
tions. Beginning in the fall of 1981, flow
monitoring and recording equipment was
installed in a manhole at the downstream
end of the sewer basin, where it has since
been maintained during the wet weather
months. Smoke tests were conducted
and revealed seven leaking service later-
als and several apparent interconnections
with storm drainage piping. All sewer
mains were inspected, revealing 33 leak-
ing service laterals, 129 visibly leaking
main joints, 26 holes in main pipes, 101
broken pipes, and 46 root intrusions.
Night-time wet weather flow measure-
ments were made to determine the
amount of I/I entering each section of
sewer pipe.
Major system repairs began in October
1983 and were completed by May 1984.
City crews chemically grouted sewer
mains, repaired faulty manholes, dug up
and replaced broken pipes, and made
other repairs where excavation and back-
fill were required. Gelco Grouting Service
crews tested, inspected, and repaired
service lateral pipes. Night-time flow
measurements had revealed that some
sections of sewer pipe contributed very
little I/I. Consequently, little or no repair
work was performed on those sewers. Of
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the 68 sections of sewer mam, 47 were
chemically grouted.
Likewise, service laterals were tested
and repaired in selected areas only.
Eighty-six service laterals were tested,
and most were repaired. Every service
lateral connection at the main failed an
air test and was sealed. Numerous dead
tees and abandoned service laterals were
sealed off.
Where service lateral work was to be
done, permission from property owners
was obtained to install cleanouts and to
make repairs to private service laterals.
Work on private service lateral pipes was
done at city expense because of the
experimental nature of the project. Access
to service laterals was gained in one of
these ways:
1. By installing a cleanout, usually
adjacent to the house.
2. By excavating and sectioning the
service lateral pipe, usually near
the property line.
3. By using the Cues Lateral Sealing
System* from within the sewer
main.
Service lateral inspections was made
using a 1.5-in.-diameter TV camera rod-
ded through the pipe. Most service later-
als were air-tested using a double-ball air
test unit developed for the project. Service
lateral repair methods included chemical
grouting using the Cues Lateral Sealing
System or the Westech/Gelco snake,
installation of polyethylene liners, instal-
lation of Insituform liners, and replace-
ment. Many service lateral pipes in the
Missouri basin were in very poor condition
and could not be repaired by chemical
grouting.
Sewer repairs in the Missouri basin
reduced peak I/I flows from 1.6 million
gpd to approximately 386,000 gpd at a
cost of about $375,000.
Findings and Conclusions
The Skyline and Missouri projects
revealed a great deal about effective
repair of sewer systems. Some lessons
and conclusions are listed as follows:
1. Sewer repairs should be done by
sewer basin to reduce I/I. During
wet weather, stormwater and
groundwater gravitate into and
collect in the backfilled sewer
trenches. The granular bedding
•Mention of trade names or commercial products
does not constitute endorsement or recommenda-
tion for use
materials and pipe zone materials
usually allow this water to move
freely along the sewer trenches
outside the sewer pipe. Even a few
sewer faults can allow large
amounts of this trench water to
enter the sewers. This trench water
can and often does flow into service
lateral faults several feet from the
main. Because the water moves
easily along the old sewer trenches,
repairing only the obvious leaks
usually causes the level of the
trench water to rise somewhat,
thereby causing it to migrate into
other sewer system faults.
2. The importance of repairing service
laterals was well demonstrated. If
these are faulty, particularly near
the sewer main, repairing mains
and manholes alone will do little to
reduce peak I/I.
3. Sewer repair needs to be a compre-
hensive program. Flows from the
basin selected for repair need to be
measured during wet weather be-
fore, during, and after repairs are
made so that the effectiveness of
the repair program can be deter-
mined. The repair of all faults
initially identified is not usually
sufficient to greatly reduce I/I flows.
Usually a few major undetected
faults are discovered after initial
repairs are made. When these faults
are prepared, I/I flows are dramati-
cally reduced.
4. Rubber-ring-jointed piping systems
are usually easier and less expen-
sive to repair than older mortar joint
systems where more extensive
repairs are necessary. Because of
the granular backfills, some newer
sewer systems contribute more I/I
per foot of sewer main than do the
older, more delapidated sewer sys-
tems.
5. Repairing sewer systems and effec-
tively reducing I/I is challenging,
difficult, and demanding. To do it
successfully requires both know-
how and persistence.
6. Quality control is extremely impor-
tant in repairing sewers. Many
repair difficulties encountered in
these two basins were caused by
repair efforts (particularly chemical
grouting work) that did not ade-
quately seal the pipe and manhole
faults.
7. Relatively little experience has been
gained in testing, inspecting, and
repairing service laterals. The fol-
lowing observations have been
made about service lateral work.
a. Locating faulty service laterals.
Smoke testing identified less
than 10 percent of the faulty
service laterals. TV inspection of
sewer mains located most leak-
ing service laterals when the
work was performed during per-
iods of high groundwater.
Approximately 40 to 50 percent
of the service laterals in the
Skyline system leaked. Locating
leaking service laterals by TV
inspection of mains in newer
rubber-ring-jointed piping sys-
tems appears to be reasonably
efficient. In older, mortar-jointed
sewer systems such as the
Missouri system, nearly all ser-
vice laterals leak. Thus the most
feasible approach to such a
system is to systematically air
test all service laterals or to
replace or repair all of them
without preliminary testing.
b. Access for testing, inspecting.
and repairing. Service lateral
cleanouts have several advan-
tages. The most important is that
access for testing, inspection,
and repairs is available as needed
over an extended period. Excava-
tion and sectioning of service
lateral piping usually affords the
best access for testing, inspec-
tion, and repairs, but the excava-
tion usually cannot be left open
for an extended period. Conse-
quently all testing and repair
must be completed with a few
days—often a difficult accom-
plishment. Access from within
the sewer main using the Cues
equipment requires no excava-
tion and no contact with or
consent from property owners.
However, only the few down-
stream feet of service lateral pipe
can be entered, tested, or re-
paired.
c. Inspection and testing methods.
The small-diameter TV camera
equipment provides a reasonably
good visual inspection of service
lateral pipes. Visual inspection is
usually necessary to determine
how repairs should be made.
Several methods were used for
leak testing service piping. The
hydrostatic test is somewhat
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slow. Air testing from the main
to the service lateral cleanout is
better, but it does not locate the
service leaks. The double-ball air
test unit provides rapid and ac-
curate testing if a cleanout or
excavation for access is available.
This method locates pipe leaks
but cannot test the connection to
the main. The Cues Lateral Seal-
ing System tests the connection
to the main but cannot test
farther than 6 or 8 ft upstream.
Repair methods. No single repair
method was best for all service
lateral installations. Each faulty
service pipe installation had to
be inspected, and pipe conditions,
configurations, depths, and sur-
face conditions were considered
before a repair method was
selected. In many cases, replac-
ing service piping was least
expensive and most desirable.
Where the existing pipe was
relatively straight, polyethylene
liners were competitive in price
with other repair methods and
caused little disruption of surface
facilities. The Westech/Gelco
snake was best used where
service piping was structurally
sound with only a few leaking
joints. Grouting these joints is
usually less expensive than other
repairs. The Cues Lateral Sealing
System is especially applicable
where sewer mains are deep or
inaccessible and wherethe serv-
ice lateral piping is structurally
sound. Insituform liners may in
time become an excellent method
for service lateral repairs, but
technical problems must be re-
solved before this method can be
widely used.
The full report was submitted in fulfill-
ment of Cooperative Agreement No. CS-
811117 by the City of Salem, OR, under
the sponsorship of the U.S. Environmental
Protection Agency.
C. H. Steketee is with Westech Engineering, Inc., Salem, OR 97302.
Richard Field was the EPA Project Officer (see below for present contact).
The complete report, entitled "Demonstration of Service Lateral Testing and
Rehabilitation Techniques," (Order No. PB 86-135 647/AS; Cost: $16.95,
subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
For further information. Carl A. Brunner can be contacted at:
Water Engineering Research Laboratory
U.S. Environmental Protection Agency
Cincinnati. OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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EPA/600/S2-85/131
0169064 WERL
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