United States
     Environmental Protection
Water Technology Fact Sheet
Pipe Bursting
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
        Courtesy of U Mole Ltd.
        Figure 2. Hydraulic Pipe Bursting

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.

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

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

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

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  area—are  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.

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.

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.

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

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,

•  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
•  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.

Pipe bursting is not favorable under the following

    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.


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.
                                           Table 1.
              Summary of King County, Washington, Pipe Bursting Pilot Projects
                        System Component Rehabilitated
Lateral     Side Sewer   System Improved    I/I Reduction (%)
Auburn j j
Kirkland j y
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
Source: Adapted from King County, Washington, 2004.

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.

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
•   Ground conditions

Tables 2 and 3 list the costs from the case studies
described above.

Table 2.
Example Costs from Case Studies







Vermeer Air



(pilot project)

(pilot project)

(pilot project)

(pilot project)

(pilot project)

Length and
Material of Pipe
3,300-ft clay pipe

4,000-ft clay pipe






31,000-ft clay pipe
Estimated Cost
$1,200,000 (cost also includes
7,700 ft of trench-and-replace






Pipe Cost
per ft







  included significant amounts on non-pipe-bursting work.
                                          Table 3.
     Summary of Costs from Traditional Pipe Bursting: Washington State I/I Pilot Projects
Design Cost
Construction Construction Management Cost
Cost ($) (Including Inspection) ($) Total Cost ($)
  *Project included significant non-pipe-bursting component.
Other Related Fact Sheets:

Trenchless Sewer Rehabilitation
EPA 832-F-99-032
September 1999

Other EPA fact sheets can be found at

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.
   Accessed July 12,2005.

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