&EPA
United States
Environmental Protection
Agency
Water Technology Fact Sheet
Pipe Bursting
INTRODUCTION
Under the traditional dig-and-replace method of
sewer rehabilitation, a replacement or additional
parallel sewer line is constructed by digging
along the entire length of the existing pipeline,
removing the existing pipe, and replacing it with
new pipe. In contrast to the traditional method,
which requires unearthing and replacing the defi-
cient pipe, trenchless sewer rehabilitation
techniques do not require excavation of the exist-
ing piping. Instead, these methods use the
existing collection system piping as a conduit or
host for replacing or rehabilitating the system. In
general, trenchless technologies can be imple-
mented through existing openings to the sewer
system (such as the manholes) or through smaller
insertion pits, rather than through excavation
along the entire length of pipe. Because these
types of sewer replacement methods do not re-
quire extensive excavation, they provide a
method of correcting pipe deficiencies with less
disturbance, economic impact, and environmental
degradation, and they require less restoration than
the traditional dig-and-replace method.
A number of trenchless sewer reha-
bilitation techniques are available,
including pipe bursting, sliplining,
cured-in-place pipe, and modified
cross section lining. The focus of
this fact sheet is pipe bursting,
which, when referring to replacing
existing pipe with new pipe of the
same diameter, is also called in-line
expansion. From a practical and value
engineering standpoint, it is consid-
ered advisable to go to a larger pipe
size, at least the next larger size,
rather than maintain the existing size.
This approach allows some additional
pipe capacity in the case of increased
loading conditions over time.
GENERAL DESCRIPTION
Pipe bursting is a method by which the existing
pipe is opened and forced outward by a bursting
tool. A hydraulic or pneumatic expansion head
(part of the bursting tool) is pulled through the
existing pipeline, typically by using a cable and
winch. As the expansion head is pulled through
the existing pipe, it pushes that pipe radially out-
ward until it breaks apart, creating a space for the
new pipe. The bursting device also pulls the new
pipeline behind it, immediately filling the void
created by the old, burst pipe with the new pipe.
Pipe bursting can be used to replace existing pipe
with similarly sized or larger pipe (see the discus-
sion of size, shape, and orientation under the
"Applicability" section below).
Various types of expansion heads can be used on
the bursting tool to expand the existing pipeline.
They can be categorized as static or dynamic.
Static heads, which have no moving internal
parts, expand the existing pipe through only the
pulling action of the bursting tool. In contrast,
dynamic heads provide additional pneumatic or
hydraulic forces at the point of impact with the
TYPICAL AIR CRACKER ftPPLICflTION
Courtesy of U Mole Ltd.
Figure 1. Pneumatic Pipe Bursting
TYPICAL HYDRAULIC ROD PULLER APPLICATION
Courtesy of U Mole Ltd.
Figure 2. Hydraulic Pipe Bursting
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existing pipe. Pneumatic heads pulse internal air
pressure within the bursting tool, while hydraulic
heads expand and contract.
Courtesy of Earth Tool Company, LLC
Figure 3. Pipe bursting to up-size pipe in
Green Bay, Wisconsin.
Dynamic heads often are required to penetrate
difficult pipe materials and soils. However, be-
cause dynamic heads can cause movement of the
surrounding soils, resulting in ground heaving,
static heads are preferred where pipe and soil con-
ditions are not suitable for using dynamic heads.
APPLICABILITY
Like other trenchless techniques, pipe bursting is
particularly valuable in urban environments be-
cause it causes fewer construction impacts that
are disruptive to businesses, homeowners, and
automotive and pedestrian traffic.
Pipe bursting typically yields the largest increase
in hydraulic capacity of any of the trenchless
sewer rehabilitation methods because other
methods, such as lining the inside of the pipe,
decrease the existing pipe's inside diameter and
capacity. Therefore, pipe bursting might be
especially applicable to projects that require
maintaining or increasing the size of the current
pipe as well as replacing defective pipe.
Size, Shape, and Orientation of Pipe
Pipe bursting is most appropriate for pipes with
an inside diameter range of 100 mm to 600 mm
(4 in. to 24 in.), although pipes as small as 51 mm
(2 in.) inside diameter or as large as 1,220 mm
(48 in.) inside diameter have been replaced.
Theoretically, there is no limit on the size of pipe
that can be replaced, and successful installation
of a larger pipe depends only on cost-
effectiveness, local ground conditions (e.g., the
potential for ground movement), and the ability
to provide sufficient energy to break the old pipe
and pull new pipe.
Pipe bursting has limitations. Difficulties can
arise from expansive soils, close proximity of
other service lines, a collapsed pipe along the
pipeline, and other causes.
Pipe-bursting operations create outward ground
displacements. These displacements tend to be
localized and dissipate rapidly away from the
bursting operation. The bursting operation also
can cause ground heave or settlement above or at
some distance from the pipe alignment. Critical
conditions for ground displacement occur when
the pipe to be burst is shallow and ground dis-
placements are primarily directed upward, when
much larger diameter pipes are used, and when
deteriorated existing utilities are present within
two to three diameters of the pipe being replaced.
In addition, typical pneumatic pipe bursting can
create quite noticeable ground vibrations on the
surface above the bursting operation.
The most favorable ground conditions for pipe
bursting are soils that can be moderately com-
pacted. Less favorable ground conditions involve
densely compacted soils and backfills and soils
below the water table. Each of these soil condi-
tions tends to increase both the force required for
the bursting operation and the zone of influence
of the ground movements.
Although the most common replacement scenario
is a size-for-size replacement, replacement with a
pipe of larger diameter can be accomplished us-
ing the appropriate pipe-bursting method. The
amount of up-sizing possible depends on the
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compactness of the trench backfill and the native
soil. Larger up-sizings also require more energy
to power the bursting tool. Finally, larger up-
sizings cause more ground movement because the
bursting head must burst through not only the
existing pipe but also the surrounding backfill
and soil to allow the larger-diameter pipe to be
inserted. Thus, these factors must also be consid-
ered when determining the feasibility of a large
up-sizing of existing pipe.
Length of Pipe
Pipe bursting is most appropriate for a maximum
installation length (for one run of pipe) of 230 m
(750 ft). However, straight pulls of over 300 m
(1,000 ft) have been performed. In 1997 a 475-m
(1,550-ft) pull was used for replacing a 25-cm
(10-in.) cast iron pipe with a 25-cm (10 in.)
HDPE pipe in Stockbridge, Massachusetts. In
Portland, Oregon, a 400-m (1,300-ft) pull was
used to replace a 45-cm (18-in.)-inside-diameter
sewer with a 50-cm (20-in.)-outside-diameter
pipe (North American Society for Trenchless
Technology 1999).
One factor that limits the installation length is
friction. The higher the friction, the more difficult
it is to pull the new pipe through the burst sec-
tions, so more power is required. Another
limiting factor is the area available for laying out
the new pipe in sections near the insertion point
(a process referred to as "pipe lay-down"). The
amount of space available determines the maxi-
mum length of the pipe sections and thus the
length of the run of pipe that can be installed.
Although the traditional method of pipe bursting
is well established and widely used, a number of
innovative pipe-bursting techniques are also be-
ing employed to replace existing piping systems.
Several of these new processes are discussed
below.
Expandit Pipe Bursting
The Expandit system (Perco Engineering Ser-
vices) is a pipe-bursting method that uses existing
manholes or small excavations to insert the pipe-
bursting tool and the new pipe. As such, it does
not require the excavation of launch/insertion pits
or recovery pits. It is a true "manhole-to-
manhole" approach. First, the two manholes are
prepared by removing the benching and the two
pipe entry points. The Expandit head is then low-
ered into the launch manhole, while a winch is
positioned above the reception manhole. The
head is hydraulically expanded and contracted in
place, bursting the existing pipe. The head is then
jacked forward using segmental pipe (Perco's
short "Snapit" pipe), which is machined to suit
the size of the manholes. The winch is used to
maintain the straight-line stability of the head and
to ensure that it stays in the center of the existing
pipe. Upon reaching the reception manhole, the
head is disconnected and pulled out of the receiv-
ing manhole, and the benching in the two
manholes is reinstalled. The Expandit process
allows the diameter of the new pipe to be in-
creased by up to 100 percent relative to the
replaced pipe, and the new pipe can be clay, con-
crete, or high-density polyethylene (HDPE).
Replacement pipe cannot be made from polyvinyl
chloride (PVC) because PVC cannot support the
jacking loads placed on the pipe.
Vermeer Air Impactor
The Air Impactor (Vermeer Manufacturing,
Pella, Iowa) has been used in a number of inno-
vative pipe-bursting projects. It combines an air-
powered bursting tool with the pulling power of a
horizontal directional drill, reducing setup time,
excavation, and surface disruption compared to
traditional pipe bursting. The surface launch ca-
pability of the horizontal directional drill reduces
or eliminates the need for launch and exit pits
because the bursting head is attached to the drill
rod at the surface and is retrieved through a man-
hole. Thus, like the Expandit pipe-bursting
system described above, it can be used from
manhole to manhole.
Other advantages of the Air Impactor/horizontal
direction drill combination compared to tradi-
tional pipe-bursting methods are reduced setup
time and smaller crew size, which can signifi-
cantly reduce costs relative to traditional pipe
bursting. The stronger pulling power of the drill
versus that of a winch is also an advantage, espe-
cially with the drill's ability to back out of the
pipe if it gets stuck.
One limitation of the Air Impactor/horizontal di-
rectional drill method is that rods need to be
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removed from the drill string at periodic intervals,
making it a start-and-stop process. In addition, the
drill can be difficult to set up on paved surfaces.
Trenchless Lateral Replacement (TRIG Tools)
TRIG Tools, in Alameda, California, developed a
pipe-bursting machine with the purpose of replac-
ing private building/residential sewer connections,
or laterals. The TRIG tool uses a steel cable to
pull a static head and new HDPE pipe through
the old pipe. The unique aspect of this method is
that it can burst through small-diameter (10 cm to
15 cm [4 in. to 6 in.]) pipe and pull the new pipe
through multiple bends. (The technology has
been used on up to three 45-degree bends in one
pull.) This can be achieved because of the small,
0.3-m (l-ft)-long static head, which can be ma-
neuvered through bends in the old pipe, and
because of the pulling action of the TRIG hydrau-
lic puller, which can apply up to 60,000 pounds
of force on the steel cable. Trenchless lateral re-
placement can be used to replace pipe of any
material except ductile iron. The replacement
pipe is always HDPE because of its flexibility
and durability.
Dual-Process Rehabilitation
The DPR method (Renaissance Integrated Solu-
tions of New York) combines pipe bursting with
the simultaneous installation of a separate conduit
system for carrying fiber-optic cable lines. An
HDPE-fabricated pipe with up to eight conduits
around its exterior is used to replace the existing
pipe. The separation of the conduits from the
interior of the pipe prevents exposure of the fiber
conduit to wastewater or other corrosive ele-
ments, allows for easy access to the fiber for
service and repair, and allows for routine clean-
ing of clogged sewer lines.
The major advantage of the DPR method is that
two common infrastructure upgrade goals
replacement of damaged pipeline and installation
of conduits for a local fiber-optic network that
can connect every building within a densely
populated downtown areaare accomplished
simultaneously. Other advantages include:
Long-term cost and short-term time savings
from the simultaneous installation of sewer
and communications infrastructure
Potential income from telecommunication
companies that lease the conduits
The presence of a local fiber-optic network as
an economic incentive for attracting busi-
nesses and other development to the area
DPR is best suited for nonresidential areas that are
densely populated with business and for institu-
tional, private, and government locations. Such
environments are most likely to create a high de-
mand for the fiber-optic system, which can help
defray its extra costs. The initial cost investment is
higher than that of sewer rehabilitation alone be-
cause two systems are being installed at one time
(new sewer lines and new fiber conduit manholes,
access boxes, etc.). Logistical concerns (such as
who designs and builds, owns and operates, and
services and repairs such a system) must be evalu-
ated to ensure that the system functions efficiently
once it is installed.
IMPLEMENTATION
The general steps for pipe bursting are as follows:
Obtain as much history as possible about the
pipe's construction and repair. Use closed-
circuit TV to view the pipe.
Install the bypass.
If necessary, construct access pits.
Disconnect services.
Cut or remove possible impediments (e.g.,
ductile iron repair couplings, steel repair cou-
plings, valves, thick concrete encasement).
Burst the old pipe (a typical rate is 30 m [100
ft] per hour) and pull the new pipe.
Pressure-test the pipe.
Tie the pipe into the existing system.
Reconnect services and remove the bypass.
During the pipe-bursting process, the rehabili-
tated pipe segment must be taken out of service
by blocking flows or rerouting them around the
rehabilitation area. After the pipe bursting has
been completed, the laterals are reconnected.
Ground-penetrating radar might need to be used
to locate any underground utilities that are not
documented on existing maps or plans.
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Unforeseen conditions, such as abandoned un-
derground utilities that are not shown in utility
records, can increase construction time as well as
the risk to the client or contractor. To avoid these
potential problems, pipe bursting or any trench-
less rehabilitation projects should be coordinated
with utility work by other agencies.
ADVANTAGES AND DISADVANTAGES
All trenchless rehabilitation methods, including
pipe bursting, have many advantages relative to
open-trench sewer replacement technologies.
First and foremost, trenchless rehabilitation
methods require substantially less construction
work than do traditional dig-and-replace meth-
ods. Underground utility construction can cause
disruptions to people living or working in areas
near the construction zone. Because trenchless
sewer rehabilitation has the potential to reduce
surface disturbance relative to traditional dig-
and-replace methods, it can reduce the number of
traffic and pedestrian detours, minimize tree re-
moval, decrease construction noise, and reduce air
emissions from construction equipment. However,
the benefits of trenchless sewer rehabilitation are
not limited to urban areas. In wetland areas and
areas with established vegetation, construction
influences can be especially harmful to plants and
aquatic habitat, and trenchless methods can re-
duce those potential impacts. In some instances,
pipe bursting might be the only way to replace
sewers in wetlands and trenchless technologies
the only practical way to install sewer systems
initially.
In addition to these benefits, reducing the amount
of underground construction labor and the surface
area of the construction zone confines work
zones to a limited number of access points. This
reduces the area where safety concerns must be
identified and secured.
Pipe bursting also has a significant number of
advantages relative to other trenchless sewer re-
habilitation methods. These advantages include:
Pipes of a wide range of diameters (5-cm to
120-cm [2-in. to 48-in.] inside diameter of ex-
isting pipe) can be burst.
A pull length of more than 300 m (1,000 ft)
can be used.
Most types of existing pipe materials (other
than HPDE) can be burst. (Some ductile iron
and reinforced concrete can be very difficult
to burst.)
The condition of the existing pipe does not
affect the ability to perform pipe bursting, as
long as the pulling cable can be inserted into
the existing pipe.
Pipe bursting allows up-sizing of pipes.
Pipe bursting also has a number of disadvantages,
including:
Existing flows in the pipe must be bypassed
or diverted.
An insertion pit must be dug to insert the
pipe-bursting apparatus into the pipe unless
an innovative pipe-bursting method using
manholes as access points is used.
The method is not recommended for pipe in
soils that are not compressible (e.g., rocky or
sandy soils).
The method might not be suitable for some
pipe materials (e.g., HDPE, ductile iron pipe,
reinforced concrete).
Impediments inside the old pipe have to be
removed.
Replacement pipe can stretch as it is being
pulled and then retract afterward, leaving
gaps between the pipe and the manhole where
it was inserted.
Occasionally, the burst pipe fragments might
be pushed into the manhole, filling it with de-
bris, or the manhole itself might be pushed
out of alignment while the replacement pipe
is being pulled into the manhole.
Ground heave can occur with shallow pipes.
The percussive action from dynamic bursting
heads can cause significant ground move-
ment, which could damage nearby surface or
underground structures.
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Pipe bursting is not favorable under the following
conditions:
Obstructions along the pipe. Obstructions
increase friction or might block the path of
the expansion head and replacement pipe.
Metallic point repairs that reinforce pipe with
ductile material. Ductile material is difficult
to burst.
Existence of adjacent pipes or utility lines. The
existence of other underground utilities might
require that the pipe-bursting operation not de-
viate in any direction from the existing pipe so
as not to damage the other utility lines.
Soil below the groundwater table. Bursting in
saturated soil can cause the water pressure to
rise around the bursting head, and groundwa-
ter can have a buoyant effect on the bursting
operation by flowing toward open insertion/
reception pits.
PERFORMANCE
Traditional Pipe Bursting
King County, Washington, used pipe bursting in
several pilot projects as part of its Regional Infil-
tration and Inflow (I/I) Control Program. This
program, initiated in 1999, includes a 6-year,
$41 million I/I control study that was kicked off
in 2000. The study includes efforts to identify
sources of I/I, test the effectiveness of various I/I
control technologies, examine the costs and bene-
fits of various I/I control technologies, and
prepare a regional plan for reducing I/I in local
agencies' collection systems. Technologies tested
under the pilot program have included rehabilitat-
ing pipes with cured-in-place materials and
replacing pipes with open-trench and pipe-
bursting methods. Most of the existing system
consisted of concrete, although several newer
sections of PVC pipe that were defective or im-
properly installed have also been rehabilitated.
Pipe bursting was tested in 5 of the 12 programs
(Auburn, Kirkland, Redmond, Ronald, and Sky-
way). Different pilot projects used pipe bursting
on mains, laterals, and side sewers (see Table 1).
The pilot projects used HOPE replacement pipe
and typically replaced 15-cm (6-in.) pipe with 15-
or 20-cm (6- or 8-in.) pipe for mains; laterals and
side sewers typically consisted of 10- and 15-cm
(4- and 6-in.) pipes that were replaced with pipes
of similar size.
Pulls were typically 60-100 m (200-300 ft) for
mains, 100 m (300 ft) for laterals, and 12 m (40
ft) for side sewers.
The Kirkland basin, which consisted of 4,900 m
(16,400 ft) of sewer main, experienced defects in
most of the collection system infrastructure, as
well as several inflow sources. Twenty-five per-
cent of the mains were rehabilitated using pipe
bursting, and the system experienced a 25 percent
reduction in I/I. In the Ronald basin, which con-
sisted of 3,990 m (13,100 ft) of sewer main, few
defects were found in the mains, so the pilot pro-
ject focused on the laterals and side sewers.
Approximately 72 percent of the laterals and side
sewers were replaced, and the system experi-
enced a 74 percent reduction in I/I.
Project
Table 1.
Summary of King County, Washington, Pipe Bursting Pilot Projects
System Component Rehabilitated
Main
Manhole
Lateral Side Sewer System Improved I/I Reduction (%)
Auburn j j
Kirkland j y
Ronald
Skyway y y
y y 11% of mains
y 25% of mains
y y 72% of laterals
and side sewers
y y 100% of system
Negligible
28
74
86
Source: Adapted from King County, Washington, 2004.
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In the Skyway pilot, 100 percent of the system
was rehabilitated (3,060 m [10,040 ft] of mains,
laterals, side sewers, and manholes), and the sys-
tem achieved an 86 percent reduction in I/I.
Although pipe bursting was conducted in the Au-
burn and Redmond areas, it was not a significant
part of the sewer rehabilitation in those areas.
The Fairfax County (Virginia) Department of
Public Works performed a pipe-bursting project
in 2002 in a wealthy, established subdivision.
Approximately 1,220 m (4,000 ft) of clay pipe,
which had been installed in the 1940s, was re-
placed. Closed-circuit TV inspection of the pipe
revealed that much of it had been completely
shattered and that raw sewage was leaking out of
the pipe into the soil. Dig-and-replace methods
were not feasible because of the residents' con-
cerns regarding the disturbances that would be
caused during construction. Pipe bursting was
chosen as a preferred alternative because no other
trenchless rehabilitation method was suitable for
the shattered pipe. The pipe needed to be up-
sized from a 15-cm (6-in.) diameter to the
County's minimum-requirement 20-cm (8-in.)
diameter. The project, which included significant
input from residents, took several years to plan
and complete and cost approximately $1 million.
Expandit Pipe Bursting
Perco Engineering Services used its patented Ex-
pandit pipe-bursting method for a major sewer
replacement project at the Royal Botanic Gardens
in Kew, England, where 160 m (525 ft) of 225-
mm (9-in.)-diameter pipe was installed as part of a
project to expand public facilities in the gardens.
For this project, it was essential that tree and other
plant root systems not be damaged, and the only
way to access the sewer lines was through existing
1.2-m by 1.0-m (4-ft by 3-ft) brick manholes. Fur-
thermore, the gardens are open to the public 363
days of the year, and the disruption to visitors and
local residents had to be minimal.
Air Impactor
Pipe bursting with a Vermeer Air Impactor, in
conjunction with a horizontal directional drill rig,
has been used at a number of locations. One such
location was Dalton, Georgia, where $1.2 million
was budgeted for replacement of 3,350 m (11,000
ft) of clay sanitary sewer line. Over a period of 6
months in 2001, approximately 1,000 m (3,300
ft) of sewer line was replaced using the Vermeer
Air Impactor method with HDPE pipe. The drill
rod was able to push through root intrusion in the
pipes, and the contractor was able to burst an
average of 1 m (3 ft) per minute.
COSTS
Factors influencing the cost of a pipe-bursting
project include:
Diameter and material of both the pipe to be
replaced and the replacement pipe
Length of pipe to be rehabilitated
Removal of the burst pipe fragments
Specific defects in the pipe (such as joint off-
sets, root intrusions, and severe cracking)
Depth of the pipe to be replaced and changes
in grade over the pipe's length
Locations of access manholes
Number of additional access points that need
to be excavated
Location of other utilities that have to be
avoided during construction
Provisions for flow bypass
Number of service connections that need to
be reinstated
Number of directional changes at access
manholes
Ground conditions
Tables 2 and 3 list the costs from the case studies
described above.
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Table 2.
Example Costs from Case Studies
Year
2001
2002
2003
2003
2003
2003
2003
2005
Method
Vermeer Air
Impactor
Traditional
Pipe
Bursting
Traditional
Pipe
Bursting
Traditional
Pipe
Bursting
Traditional
Pipe
Bursting
Traditional
Pipe
Bursting
Traditional
Pipe
Bursting
DPR
Location
Georgia
Virginia
Washington
(pilot project)
Washington
(pilot project)
Washington
(pilot project)
Washington
(pilot project)
Washington
(pilot project)
Louisiana
Length and
Material of Pipe
3,300-ft clay pipe
4,000-ft clay pipe
30,769ft
16,406ft
23,143ft
13,097ft
10,038ft
31,000-ft clay pipe
Estimated Cost
$1,200,000 (cost also includes
7,700 ft of trench-and-replace
work)
$1,000,000
$749,400
$1,190,400
$1,273,400
$1,531,400
$1,883,900
$5,300,000
Pipe Cost
per ft
NA*
$250
NA*
$73
NA*
$117
$188
$171
included significant amounts on non-pipe-bursting work.
Table 3.
Summary of Costs from Traditional Pipe Bursting: Washington State I/I Pilot Projects
Project
Auburn*
Kirkland
Redmond*
Ronald
Skyway
Design Cost
($)
$96,100
$154,700
$193,800
$145,000
$238,400
Construction Construction Management Cost
Cost ($) (Including Inspection) ($) Total Cost ($)
$384,700
$838,200
$840,100
$1,077,300
$1,395,200
$72,200
$57,600
$82,600
$176,300
$157,700
$749,400
$1,190,400
$1,273,400
$1,531,400
$1,883,900
*Project included significant non-pipe-bursting component.
REFERENCES
Other Related Fact Sheets:
Trenchless Sewer Rehabilitation
EPA 832-F-99-032
September 1999
Other EPA fact sheets can be found at
http://www.epa.gov/owm/mtb/mtbfact.htm
Earth Tech. 2004. Pilot Project Report, Regional
Infiltration and Inflow Control Program, King
County, Washington, 2004. October.
Hammer Head Mole. 2001 to 2002. Hammer-
Head News Bulletins (November 200I/July
2002). .
Khan, Ifty, Director, Wastewater Collection Divi-
sion. Fairfax County Department of Public
Works, 2005. Personal communication with
Parsons Corporation.
Moore, W. 2002. Vermeer Horizontal Drill In-
stalls New Sewers. Construction Equipment,
June 2002.
-------
North American Society for Trenchless Technol-
ogy. 1999. Water Pipeline Rehabilitation J»m
Method Fact Sheet. United States
Environmental Protection
Perco Engineering Services Limited. 2005. Sewer Agency
Replacement by Pipebursting: Case Histories.
,, ,, // , / .-,
Office of Water
P P ' September 2006
Renaissance Integrated Solutions. 2005. Dual
Process Rehabilitation Solution.
. Accessed
June 23, 2005.
Sawyer, T., T. Armistead, and W. Starrett. 2005.
Data Demand Sparks Race to Bring Fiber Op-
tics Home. Engineering News-Record.,
March?, 2005.
Simicevic, J., and R.L. Sterling. 2001. Guidelines
for Pipe Bursting. TTC Technical Report no.
2001.02. Prepared for U.S. Army Corps of
Engineers, Engineering Research and Devel-
opment Center.
TRIC Tools, Inc. 2006. Web site.
.
U Mole Ltd. 2006. Pipe Bursting Equipment.
.
United Kingdom Society for Trenchless Tech-
nology. 2005. Replacement Techniques.
http://www.ukstt.org.uk/tt_replacement.php.
Accessed July 12,2005.
ADDITIONAL INFORMATION
King County, Washington
Erica Herrin, Water Quality Planner II
Wastewater Treatment Division
201 South Jackson Street, Suite 505
Seattle, WA 98104
Fairfax County, Virginia
Ifty Khan, Director of Wastewater Collection
Department of Public Works and
Environmental Services
6000 Freds Oak Road
Burke, VA 22015
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