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SECTION 819
MICROTUNNELING AND PIPE-JACKED TUNNELS


819-1 DESCRIPTION: This Work consists of all materials, labor and equipment required to directly
install product pipelines typically 24 and larger, underground in a single pass using an appropriate
tunnel boring machine combined with pipe-jacking techniques.

This specification also covers Pilot Tube Microtunneling (PTMT). Pilot Tube Microtunneling shall be
defined as an alternate microtunneling system typically for sizes 6" through 27" inner diameter. This
system is a two or three stage system, which allows both trenchless guided installation of house
connection sewers as well as accurate direct jacking of smaller diameter pipelines without use of
casing.

819-1.1 Scope of Work:

a. Construction of tunnels by one-pass methods with or without man entry. The
construction methods involve jacking pipe following a hand-shield excavation or a
tunnel boring machine (TBM) or micro-tunnel boring machine (MTBM), with the pipe
serving as both the tunnel liner during construction and the sewer pipe after
completion of construction.

b. Construction of smaller diameter pipelines utilizing the Pilot Tube Microtunneling
process. The system shall utilize a two or three phase system.

c. The Contractor may select pipe materials as listed in the QPL for Microtunneling and
Pipe-Jacked Tunnels, or approved equal.

d. Ancillary work includes mix design requirements, testing, furnishing and production
of grout for:

1. Pressure grouting of bolted liner plates for shafts.
2. Pressure grouting of primary tunnel liner.
3. Pressure grouting of jacked-pipe.
4. Annular grouting uncased sewer pipe.
5. Grouting voids in ground resulting from caving, loss of ground, or settlement.
6. Grouting of manholes constructed in shafts.
7. Compaction grouting is not part of this specification.

e. Construction, maintenance, and backfilling of tunnel shafts.

819-1.2 Definition:

a. Jacked Pipe: A method for installing sewer pipe that serves as initial construction
lining and tunnel support, installed for stability and safety during construction, and as
the sewer pipe. The pipe is shoved forward, or jacked, as the tunnel is advanced.

b. Microtunneling: A method of installing pipe by jacking the pipe behind a
microtunnel boring machine which is connected to and shoved forward by the pipe
being installed, generally precluding man entry.

c. Pilot Tube Microtunneling (PTMT): Multi stage method of accurately installing a
product pipe to line and grade by use of a guided pilot tube and followed by upsizing
to install the product pipe. The system must use a guidance system to insure
accuracy, is remotely operated and does not require man entry to the tunnel for
normal operations. The guidance system, consisting of target, theodolite, camera,
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and monitor, can detect the deviation of the drilling profile, and gives the operator
continuous information about the location of the steering head.

d. Tunnel Boring Machine (TBM): Mechanized excavating equipment that is
steerable, guided and articulated, connected to and shoved forward by the pipe
being installed, with man entry.

e. Microtunnel Boring Machine (MTBM): Mechanized excavating equipment that is
remotely-controlled, steerable, guided and articulated, connected to and shoved
forward by the pipe being installed, usually precluding man entry.

f. Tunneling Methodology: A written description, together with supporting
documentation that defines Contractor's plans and procedures for the microtunneling
or pipe jacking operations.

g. Zone of Active Excavation: Area located within a radial distance about a surface
point immediately above the face of excavation equal to the depth to the bottom of
the excavation.

h. Critical Structure: Any building, structure, pipeline, utility, bridge, pier, or similar
construction partially or entirely located within a zone of active excavation.

i. Pressure Grouting: Filling a void behind a liner or pipe with grout under pressure
sufficient to ensure void is properly filled but without overstressing temporary or
permanent ground support, or causing ground heave to occur.

j. Back Grouting: Secondary pressure grouting to ensure that voids have been filled
between shaft liners and the surrounding ground.

k. Annular Grouting: Filling the annular space between the carrier pipe and the
ground, by pumping.

l. Ground Stabilization Grouting: The filling of voids, fissures, or under-
slab settlement due to caving or loss of ground by injecting grout under
gravity or pressure to fill the void.

819-1.3 Qualifications:

a. Tunneling and Microtunneling Contractors will have actively engaged in the
installation of pipe using tunneling and microtunneling for a minimum of three years,
during which time the Contractor will have completed at least 15,000 linear feet of
microtunneling installations.

b. Field supervisory personnel employed by the Tunneling or Microtunneling Contractor
will have at least two years experience in the performance of the work and tasks as
stated in the Contract Documents.

819-1.4 Submittals:

a. Qualifications: Submit documentation showing that the Contractor and personnel
meet the minimum required qualifications stated in Section 819-1.3. Include a list of
a minimum of three wastewater collection projects similar in scope and value to the
project specified in the contract documents. Information must include, but not be
limited to date and duration of work, location, pipe information (i.e. length, diameter,
depth of installation, pipe material, etc.), project owner information (i.e. name,
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address, telephone number, contact person), and the contents handled by the
pipeline (water, wastewater, etc.).

b. Materials:

1. Submit pipe material reference sheets and manufacturers certification of pipe
meeting or exceeding the required specifications.

2. Submit a description of materials, grout mix, equipment and operational
procedures to accomplish each grouting operation. The description may
include sketches as appropriate, indicating type and location of mixing
equipment, pumps, injection points, venting method, flowlines, pressure
measurement, volume measurement, grouting sequence, schedule, and
stage volumes.

i. Submit a grout mix design report, including:

A. Grout type and designation.
B. Grout mix constituents and proportions, including materials by weight
and volume.
C. Grout densities and viscosities, including wet density at point of
placement.
D. Initial set time of grout.
E. Bleeding, shrinkage/expansion.
F. Compressive strength.

ii. For cellular grout, also submit the following:

A. Foam concentrate supplier's certification of the dilution ratio for the
foam concentrate.
B. A description of the proposed cellular grout production procedures.

iii. Maintain and submit logs of grouting operations indicating pressure,
density, and volume for each grout placement.

c. Tunneling Methodology: A brief description of proposed tunnel methodology for
review. The description should be sufficient to convey the following:

1. Proposed method of tunnel construction and type of face support.

2. Manufacturer and type of tunneling equipment proposed. Describe type of
lighting and ventilation systems.

3. Number and duration of shifts planned to be worked each day.

4. Sequence of operations.

5. Locations of access shafts and work sites. Describe method of construction for
tunnel shafts.

6. Method of spoil transportation from the face, surface storage and disposal
location.

7. Capacity of jacking equipment and type of cushioning.

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8. Identify critical utility crossings and special precautions proposed.

9. Slurry injection system details.

d. Tunnel Shaft Schedule of Values: Cost per shaft by station, diameter, and depth.

e. Tunnel Shafts: Submit shaft construction drawings together with calculations. As a
minimum the submittal shall include:

1. Shaft dimensions, design criteria, and details for ground support system,
such as sheeting, shoring, bracing, and stabilization, protection of the
excavation, special requirements for shaft penetrations, tunnel "eye", starter
and back tunnels, and seal slabs. Allowable surcharge loads and any
restrictions on surcharge capacity, including live loads, shall be clearly shown on
the shaft construction drawings. Thrust blocks or other reactions required for
pipe jacking shall be shown, if applicable.

2. Location of shafts by station and limits of working sites.

3. Description of site security arrangements in conformance with Subsection
819-3.6.

4. Description of method of extending the shaft above the flood level in
compliance with Subsection 819-1.5.b.

5. Any geotechnical / boring undertaken by the Contractor for whatever purpose
connected to the Work.

6. Submit shaft temporary deck drawings and calculations in the event that a
shaft is not needed for immediate construction activity, in conformance with
Subsection 819-1.5.b.

7. Shaft design submittals by the Contractor shall be signed and sealed by a
Professional Engineer registered in the State of Louisiana.

f. Drawings and Calculations: Submit for record purposes, drawings, and
calculations for any tunnel support system designed by the Contractor. Drawings
shall be adequate for construction, and include installation details. For pipe jacking
and microtunneling show pipe and pipe joint detail. Documents must be signed and
sealed by a Professional Engineer registered in the State of Louisiana. Calculations
shall include clear statement of criteria used for the design as described in
Subsection 819-1.5. Engineers review of all drawings and calculations is for
information purposes and overall compliance.

g. Quality Control: Submit for review a brief description of quality control methods
including:

1. Method and frequency of survey control.

2. Example of tunnel daily log.

h. Geotechnical Investigation: When geotechnical investigations are conducted by
the Contractor, submit results in both hardcopy and electronic form to the Engineer
for record purposes.

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i. Monitoring Plans: The Contractor shall provide monitoring plans per Subsection
819-3.10 for assessing ground movement (settlement or heave) due to drilling
operations as follows:

1. Instrumentation Monitoring Plan: Submit for review, prior to construction, a
monitoring plan that includes a schedule of instrumentation design, layout of
instrumentation points, equipment installation details, manufacturer's catalog
literature, and monitoring report forms.

2. Surface Settlement Monitoring Plan. Submit a settlement monitoring plan for
review prior to construction. The plan shall identify the location of settlement
monitoring points, reference benchmarks, survey frequency and procedures,
and reporting formats.

j. Structures Assessment: Pre-construction and post-construction assessment
reports shall be provided for critical structures, namely those located within the zone
of active excavation from the proposed tunnel centerline. Photographs or a video of
any existing/pre-construction damage to structures in the vicinity of the sewer
alignment shall be included in the assessment reports.

k. The readings of all monitoring shall be submitted to the Engineer.

l. Daily Reports: The shift log as defined in Subsection 819-3.5, Pipe-jacked
Tunneling Data, shall be maintained by the Contractor, and must be made available
to the Engineer on request.

m. Traffic Control Plan: If traffic maintenance is required as part of the Work, a Traffic
Control Plan will be submitted to DPW. The plan shall include an outline of the permit
acquisition procedure for lane closure, methods for proper signing and barricades,
which complies with local requirements and the MUTCD, and site Contractor
telephone numbers for emergencies.

819-1.5 Design Criteria:

a. Pipe:

1. Contractor is responsible for selection of the appropriate pipe and pipe joints to
carry the thrust of any jacking forces or other construction loads in
combination with overburden, earth and hydrostatic loads. Design of any pipe
indicated on the Contract Documents considers in-place loads only and does not
take into account any construction loads. The criteria for longitudinal loading
(jacking forces) on the pipe and joints shall be determined by the
contractor, based on the selected method of construction.

2. The jacked pipe shall be designed to withstand the thrust from the MTBM,
TBM, PTMT or shield and pipe advance without damage or distortion. The
propulsion jacks shall be configured so that the thrust is uniformly distributed
and will not damage or distort the pipe.

3. Take into account loads from handling and storing.

4. The criteria to be used at railroad crossings shall be as specified by the
AREA Manual for Railway Engineering and as otherwise specified by the
Railroad Agency having jurisdiction. In the design, account for additive
loadings due to multiple tracks.

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5. The criteria to be used for truck loading shall be HS-20 vehicle loading
distributions in accordance with AASHTO and as otherwise specified by the
LADOTD.

6. Provide pipes of diameter shown on the Contract Documents. Substitution of
pipe with larger diameter to suit MTBM, TBM, or PTMT equipment availability will
only be permitted if the Contractor can demonstrate to the Engineers
satisfaction that design flows and velocities can be achieved.

7. All tunneled pipes 36-inches in diameter or larger shall have grout injection
ports built into the pipe at the 12 oclock position for pumping slurry during the
pipe installation and for grouting the annular space once the tunneling is
complete.

b. Tunnel Shafts:

1. Shaft design must include allowance for contractors equipment and stored
material and spoil stockpile as appropriate. Design must also allow for HS-20
highway loading if located in the vicinity of a paved area.

2. The shaft shall be designed to withstand full hydrostatic head without failure.

3. Shaft located within the 100-year floodplain shall be designed with a water
retaining liner extending 2 feet above the 100-year flood elevation. It is
acceptable if liner is stored at the site for immediate installation in lieu of its
being installed at the shaft, provided that the shaft liner extends at least 2 feet
above existing ground elevation.

4. Shaft cover, if used in lieu of shaft perimeter security fencing, shall be
designed for a minimum 25 pounds per square foot distributed load plus a
300-pound point load.

5. Steel plate deck, if such is required, shall be designed for HS-20 loading.

819-2 PRODUCTS:

819-2.1 Sewer Pipe:

a. Contractor shall be responsible for selecting appropriate pipes and pipe joints to
safely carry the loads imposed during construction, including jacking forces. The
Contractor shall select approved pipe materials from the QPL and conforming with
the following Sections:

1. Vitrified Clay Pipe 1016-1.5
2. Fiberglass Reinforced Polymer (FRP) 1016-1.6
3. Polymer Concrete Pipe 1016-1.7

b. Use pipe that is round with a smooth, even outer surface, and has joints that allow
for easy connections between pipes. Pipe ends shall be designed so that jacking
loads are evenly distributed around the entire pipe joint and such that point loads will
not occur when the pipe is installed. Pipe used for pipe jacking shall be capable of
withstanding all forces that will be imposed by the process of installation, as well as
the final in-place loading conditions. Protect the driving ends of the pipe and joints
against damage.

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819-2.2 Slurry:

a. Slurry will be a mixture of water and bentonite clay. The fluid will be inert. The fluid
should remain in the tunnel to ensure the stability of the tunnel, reduce drag on the
jacked pipe, and provide backfill within the annulus of the pipe and tunnel.

b. Disposal of excess slurry and spoils will be the responsibility of the Contractor who
must comply with all relevant regulations, right-of-way, workspace, and permit
agreements. Excess slurry and spoils will be disposed at an approved location. The
Contractor is responsible for transporting all excess slurry and spoils to the disposal
site and paying any disposal costs. Excess slurry and spoils will be transported in a
manner that prevents accidental spillage onto roadways. Excess slurry and spoils
will not be discharged into sanitary or storm drain systems, ditches or waterways.

c. Mobile spoils removal equipment capable of quickly removing spoils from the
Microtunneling machine face will be present during drilling operations to fulfill the
requirements of item b. above.

d. The Contractor will be responsible for making provisions for a clean water supply for
the mixing of the slurry.

819-2.3 Grouting Materials: Prepare mixes that satisfy the required application. Materials used in
grout mix shall meet the following standards:

a. Cementitious Material:

1. Portland Cement: ASTM C 150, Type II, unless the use of Type III is authorized
by the Engineer; or ASTM C 595, Type IP. For concrete in contact with sewage
use Type II cement.

2. When aggregates are potentially reactive with alkalis in cement, use cement not
exceeding 0.6 percent alkali content in the form of Na
2
O + 0.658K
2
0.

b. Water: Clean, free from harmful amounts of oils, acids, alkalis, or other deleterious
substances, and meeting requirements of ASTM C 94.

c. Fine Aggregate: ASTM C 33. Determine the potential reactivity of fine aggregate in
accordance with the Appendix to ASTM C 33.

d. Fluidifier: Use a fluidifier meeting ASTM C 937 that holds the solid constituents of the
grout in colloidal suspension and is compatible with the cement and water used in the
grouting operations.

e. Admixtures:

1. Use admixtures meeting ASTM C 494 and ASTM C 1017 as required, to improve
pumpability, to control time of set, to hold sand in suspension and to reduce
segregation and bleeding.

2. For cellular grout, do not use foam or admixtures that promote steel corrosion.

3. Ensure that admixtures used in a mix are compatible. Provide written
confirmation from the admixture manufacturers of their compatibility.

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f. Water Reducers: ASTM C 494, Type A.

1. Water Reducing Retarders: ASTM 494, Type D.

2. High Range Water Reducers (Superplasticizers): ASTM C 494, Types F and G.

g. Prohibited Admixtures: Admixtures containing calcium chloride, thiocyanate, or
materials that contribute free chloride ions in excess of 0.1 percent by weight of
cement.

h. Grout Type Applications.

1. Grout for pressure grouting and back grouting: Sand-cement mortar mix.

2. Grout for annular grouting: Low density (cellular) grout or sand-cement mortar
mix.

3. Ground stabilization: Sand cement mortar mix.

i. Do not include toxic or poisonous substances in the grout mix or otherwise inject
such substances underground.

j. Provide grout that meets the following minimum requirements:

1. Minimum 28-day unconfined compressive strength: 1000 psi for sand- cement
mortar grout; 300 psi for cellular grout.

2. Determine strength by ASTM C 942.

819-3 GENERAL EXECUTION:

819-3.1 Construction Operations Criteria:

a. Use methods for microtunneling and pipe-jacked tunneling operations that will
minimize ground settlement. Select a method which will control flow of water and
prevent loss of soil into the tunnel and provide stability of the face under anticipated
conditions.

b. The Pilot Tube Microtunneling system shall utilize a two or three phase system as
described below:

1. Three Pass System

i. Phase 1 A rigid steel pilot tube in approximately one-meter lengths shall
be installed through the ground from the drive shaft to the receiver
shaft by earth displacement with the jacking frame. The alignment of
the pilot tube shall be established with a theodolite mounted at the
rear of the drive shaft and accurately set to the desired line and
grade. The theodolite shall view a lighted target in the lead or steering
pilot tube. A camera shall be fitted to the theodolite and shall transmit
the image of the crosshair and the target onto a monitor screen to be
viewed in the drive shaft by the operator. As the operator advances the
pilot tube through the earth the center of the target will drift from the
crosshair as a result of the biased or slanted leading tip of the pilot tube.
The operator shall rotate the pilot tube as required to orient the slanted
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steering tip toward the crosshair and continue to advance the pilot tube
until it reaches the receiver shaft.

ii. Phase 2 An enlargement casing with an outside diameter up to 1
larger than the product pipe shall be rigidly connected to the final pilot tube
and advanced into the earth behind the pilot tube. An auger shall be
used inside the enlargement casing to remove the material being
excavated. The auger shall be contained inside the limits of the
enlargement casing as it progresses along the proposed alignment. A train
of temporary steel casings with an outside diameter very similar to the
enlargement casing and used to move the enlargement casing from the
drive shaft to the receiver shaft. The enlargement casing will cut a bore
hole from the drive shaft to the receiver shaft and the temporary casings
will case the hole as it is cut. Each temporary casing shall be fitted
with an internal auger to transport the excavated material to the drive shaft
where it shall be removed from the shaft and disposed of at an approved
location. The pilot tubes shall be recovered in the receiver shaft as the
temporary casings are installed.

iii. Phase 3 The product pipe shall then be installed directly behind the final
temporary casing pipe with the jacking frame. The casing pipes and
augers shall be recovered in the receiver shaft as the product pipe is
installed.

2. Two Pass System

i. Phase 1 The pilot tube shall be installed in the same manner
described Phase 1 of the Three Pass System.

ii. Phase 2 The enlargement casing shall be installed in the same
manner described in Phase 2 of the Three-Phase System. Each product
pipe shall be fitted with an internal protective-casing pipe to house the
auger and prevent damage to the product pipe. The product pipe shall
be installed directly behind the enlargement casing with the internal casing
rigidly connected to the auger chamber of the enlargement casing. The
internal casing shall be manufactured such that the excavated material
does not leak excessively into the product pipe. The internal casing shall
be fitted with a protective shoe to protect the product pipe from damage
and to support the casing and auger at the centerline of the pipe. The
product pipe shall be advanced along the proposed alignment with the
jacking frame thus progressing the enlargement casing from the drive
shaft to the receiver shaft with the pilot tubes being recovered in the
receiver shaft. The excavated material shall be funneled into and
conveyed through the internal casing to the drive shaft where it
shall be removed from the shaft and disposed of at an approved
location. Upon reaching the receiver shaft the enlargement casing shall
be removed and the internal casings and augers retracted and recovered at
the drive shaft.

c. Conduct tunneling operations in accordance with applicable safety rules and
regulations, OSHA standards and Contractor's safety plan. Use methods, which
include due regard for safety of workmen, adjacent structures, utilities, and the
public.

d. Maintain clean working conditions on the project site.

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e. For tunneling under railroad embankments, highways, or streets, perform the
installation so as to avoid interference with the operation of the railroads, highways,
or streets, except as approved by the owner of the facility.

819-3.2 Location of Tunnel Shafts:

a. The number of tunnel shafts shall be kept to a minimum and shall be typically sited at
proposed manhole locations.

b. When shaft sites are indicated on the Contract Documents, the Contractor may alter
locations of shaft sites as needed for construction operations. Relocation shall be
subject to the Engineers approval.

c. Locate shafts and associated work areas to avoid blocking driveways and cross
streets, and to minimize disruption to business and commercial interests. Avoid
shaft locations near areas identified as residential or potentially contaminated.

d. Locate shafts and associated work areas to avoid any major utility relocations. Any
required utility relocations for shaft construction shall be coordinated by Contractor
with the utility owner.

e. The Contractor shall verify all existing utilities, pipelines, and structures in the project
area, and take all precautions and measures to protect them during the installation,
subsequent tunneling and backfilling of the shafts after completion of sanitary sewer
installations. Relocation of City-Parish-owned utilities for the construction of
temporary shafts are considered incidental to shaft construction and shall be
included in the Tunnel Shaft unit price.

f. Plan shaft locations to minimize interference with storm drainage channels, ditches,
water mains, sanitary sewers, storm water sewers or culverts, which, if damaged,
could result in ground washout or flooding of shafts and tunnels.

819-3.3 Ground Water Control: Provide ground water control measures in conformance with
Section 801, when necessary to perform the Work.

819-3.4 Equipment:

a. Full directional guidance of a shield, TBM, or MTBM is a prerequisite of this method
of construction.

b. The Contractor shall be responsible for selection of tunneling equipment which,
based on past experience, has proven to be satisfactory for excavation of the soils to
be encountered.

c. The Contractor shall employ tunneling equipment that will be capable of handling the
various anticipated ground conditions and is capable of minimizing loss of soil ahead
of and around the machine and shall provide satisfactory support of the excavated
face.

d. The TBM used for pipe-jacking shall conform to the shape of the tunnel with a
uniform perimeter that is free of projections that could produce over- excavation or
voids. An appropriately sized overcutting head may be provided to facilitate steering.
In addition it shall:

1. Be capable of full face closure.

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2. Be equipped with appropriate seals to prevent loss of bentonite lubricant.

3. Be capable of correcting roll by reverse drive or fins.

4. Be designed to handle adverse ground conditions including ground water
inflow.

5. Be equipped with visual display to show the operator actual position of TBM
relative to design reference.

e. If a hand shield is used for pipe-jacked tunneling (with or without attached
mechanized excavating equipment), the shield must be capable of handling the
various anticipated ground conditions. In addition, the shield shall:

1. Conform to the shape of the tunnel with a uniform perimeter that is free of
projections that could produce over-excavation or voids. An appropriately-
sized overcutting head may be provided to facilitate steering.

2. Be designed to allow the face of the tunnel to be closed by use of gates or
breasting boards without loss of ground.

f. In the case of MTBM, use a spoil transportation system which:

1. Either balances the soil and ground water pressures by the use of a slurry or
earth pressure balance system; system shall be capable of adjustments
required to maintain face stability for the particular soil condition and shall
monitor and continuously balance the soil and ground water pressure to
prevent loss of slurry or uncontrolled soil and ground water inflow, or, in the
case of a slurry spoil transportation system:

i. Provides pressure at the excavation face by use of the slurry pumps,
pressure control valves, and a flow meter.

ii. Includes a slurry bypass unit in the system to allow the direction of flow
to be changed and isolated, as necessary.

iii. Includes a separation process designed to provide adequate
separation of the spoil from the slurry so that slurry with sediment
content within the limits required for successful tunneling can be returned
to the cutting face for reuse. Appropriately contain spoil at the site prior to
disposal.

iv. Uses the type of separation process suited to the size of tunnel being
constructed, the soil type being excavated, and the workspace available at
each work area for operating the plant.

v. Allows the composition of the slurry to be monitored to maintain the slurry
weight and viscosity limits required.

2. In the case of a cased auger earth pressure balance system, the system shall be
capable of adjustments required to maintain face stability for the particular soil
condition to be encountered. Monitor and continuously balance the soil and
ground water pressure to prevent loss of soil or uncontrolled ground water
inflow.

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i. In a cased auger spoil transportation system; manage the pressure at the
excavation face by controlling the volume of spoil removal with respect
to the advance rate. Monitor the speed of rotation of the auger flight,
and the addition of water.

3. Provide an MTBM which includes a remote control system with the following
features:

i. Allows for operation of the system without the need for personnel to enter
the tunnel. Has a display available to the operator, at a remote operation
console, showing the position of the shield in relation to a design
reference together with other information such as face pressure, roll,
pitch, steering attitude, valve positions, thrust force, and cutter head torque;
rate of advance and installed length.

ii. Integrates the system of excavation and removal of spoil and its
simultaneous replacement by pipe. As each pipe section is jacked
forward, the control system shall synchronize all of the operational
functions of the system.

4. Provide an MTBM that includes an active direction control system with the
following features:

i. Controls line and grade by a guidance system that relates the actual
position of the MTBM to a design reference (e.g., by a laser beam
transmitted from the jacking shaft along the pipe to a target mounted in the
shield).

ii. Provides active steering information that shall be monitored and transmitted
to the operating console.

iii. Provides positioning and operation information to the operator on the
control console.

5. Use generator which is suitably insulated for noise reduction in residential or
commercial areas. Use of generator must be in accordance with City/Parish
noise ordinance.

g. In the case of PTMT the following are minimum major components required:

1. Line and Grade Control System The control system shall include but not be
limited to a theodolite, lighted target, camera, and monitor screen. The
equipment must be capable of installing the pipe to the desired line and grade
with a tolerance described in Section 819-3.9

2. Jacking Frame The jacking frame shall possess adequate strength to
advance the pilot tube, the enlargement casing and the string of product pipe
from the drive shaft to the receiver shaft. The jacking force shall be easily
regulated down to the safe working load rating of the pipe. The frame shall
develop a uniform distribution of jacking forces on the end of the pipe. The
auger motor shall possess adequate torque to steer the pilot tube and
adequate torque and speed to effectively auger the excavated material from the
face of the bore to the drive shaft.

3. Pilot Tube The pilot tubes shall be constructed of steel in rigid but short
sections to accommodate the small drive and receiver shafts. The tubes shall
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rigidly connect to each other, the steering tip and the enlargement casing
and have a clear inside diameter large enough to adequately view the lighted
target. The tubes shall withstand the torque encountered in the steering
process.

4. Enlargement Casing The enlargement casing shall be constructed of steel to a
diameter just larger than the product pipe and have a leading connection
compatible with the pilot tube. The leading face of the casing shall possess
several large openings for the soil to enter as it advances along the proposed
alignment. An internal auger chamber shall funnel the excavated material into
the temporary full diameter casings of the Three-Phase Process or into the
internal auger casings of the Two-Phase Process. Structural members shall
connect the leading edge of the casing to the pilot tube connections.

5. Soil Transportation System The soil transportation system shall consist of an
auger train operating inside the full diameter temporary steel casings of the
Three-Phase System and an internal casing and auger train operating inside
the product pipe. The internal casings of the Two-Phase Process shall be
manufactured to minimize leakage of the excavated material into the product
pipe.

6. Soil Removal A soil removal system shall be provided to safely remove the
excavated material from the drive shaft to the surface.

7. Hydraulic Power Unit The hydraulic power unit shall rest on the surface and be
connected to the jacking frame by hoses. The unit shall meet all applicable noise
standards.

8. Lubrication System A lubrication system shall be employed to minimize pipe
friction to insure that pipe can be installed from the drive shaft to the receiver
shaft within the safe working load rating of the pipe. The system may also be
required to minimize the torque required to transport the excavated material
to the drive shaft.

h. Provide a pipe jacking system with the following features:

1. Has the main jacks mounted in a jacking frame located in the starting shaft.

2. Has a jacking frame which successively pushes a string of connected pipes
following the tunneling excavation equipment towards a receiving shaft.

3. Has sufficient jacking capacity to push the tunneling excavation equipment and
the string of pipe through the ground. Incorporate intermediate jacking stations,
if required.

4. Develops a uniform distribution of jacking forces on the end of the pipe by use
of spreader rings and packing, measured by operating gauges.

5. Provides and maintains a pipe lubrication system at all times to lower the
friction developed on the surface of the pipe during jacking.

i. Use thrust reactions for pipe jacking that are adequate to support the jacking
pressure developed by the main jacking system. Special care shall be taken when
setting the pipe guide rails in the jacking shaft to ensure correctness of the
alignment, grade, and stability.

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j. Provide equipment to maintain proper air quality of manned tunnel operations during
construction in accordance with OSHA requirements.

k. Enclose lighting fixtures in watertight enclosures with suitable guards. Provide
separate circuits for lighting, and other equipment.

l. Electrical systems shall conform to requirements of National Electrical Code NFPA
70.

819-3.5 Pipe-Jacked Tunneling Data:

a. Maintain shift logs of construction events and observations. The Engineer shall have
access to the Contractor's logs with regard to the following information:

1. Location of boring machine face or shield by station and progress of tunnel
drive during shift.

2. Hours worked per shift on tunneling operations.

3. Completed field forms for checking line and grade of the tunneling operation,
showing achieved tolerance relative to design alignment. Steering control logs
will generally be acceptable.

4. Maximum pipe jacking pressures per drive.

5. Location, elevation and brief soil descriptions of soil strata.

6. Ground water control operations and piezometric levels.

7. Observation of any lost ground or other ground movement.

8. Any unusual conditions or events.

9. Reasons for operational shutdown in the event a drive is halted.

819-3.6 Tunnel Shaft Construction:

a. Ground support systems shall be in accordance with the following:

1. Liner elements, bracing and shoring structural members shall be installed at the
locations and in the method sequence and tolerances defined on shaft
construction drawings as the excavation progresses.

2. The bracing and shoring shall be in contact with the liner to provide full
support as shown in shaft construction drawings. Any modifications to liner,
bracing and shoring shall be evaluated, checked and approved by
Contractor's Professional Engineer, and submitted to the Engineer.

3. A seal slab shall be installed as soon as final depth and stable bottom
conditions have been reached and accepted by the Engineer. The seal slab
shall be capable of withstanding the full piezometric pressure, either by
pressure relief using under drains, or in the case of more permeable ground
condition, by the use of a structural reinforced slab. In either case, the seal
slab shall be constructed in accordance with the design provided by the
Contractors Professional Engineer.
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4. The entire shaft shall be designed and constructed to appropriate factors of
safety against yield, deformation, or instability as determined by Contractor's
Professional Engineer, and shall withstand a full hydrostatic head without
failure.

5. Special framing, bracing or shoring required around tunnel "eyes" or other
penetrations shall be in-place according to shaft construction drawings before the
liner or any bracing or shoring at the penetration is cut or removed.

6. Conduct annular space grouting in accordance with Subsection 819-3.8.

b. Install suitable thrust or reaction blocks as required for pipe jacking equipment.

c. Provide drainage from shafts while work is in progress and until adjacent pipe joints
have been sealed and the shaft is backfilled. Conform to the requirements with
Section 801.

d. Divert surface water runoff and discharge from dewatering system away from the
shaft. Protect the shafts from infiltration or flooding.

e. Each surface work site is to be surrounded by a security fence, which shall be secure
at any time the site is unattended by Contractors personnel.

f. In addition to the above, the shaft, when not in use shall be protected by a second
security fence at the perimeter of the shaft, or alternatively by a cover designed in
accordance with Subsection 819-1.6.b.

g. A shaft which is constructed more than 60 days in advance of its intended use shall
be covered by a steel plate deck designed by the Contractors Professional
Engineer, and the surface restored to permit full traffic flow during the time the shaft
is not in use. All other Contractors material including portable concrete traffic
barriers, traffic control system, fencing and other materials and equipment must be
removed from the site and reinstalled at the time the shaft is re-opened for use.

h. Backfill and compaction of the shaft shall be provided in accordance with Section
801. Grouting of manhole or structure annular space in accordance with Subsection
819-3.8, will be permitted in cases where insufficient workspace exists.

i. Remove the shaft liner above the level of 8 feet below ground surface, unless
otherwise indicated on the Contract Documents. Maintain sufficient ground support
to meet excavation safety requirements while removing the shaft structure.

j. A flowable fill material may be used by the Contractor for backfill of Tunnel Shafts.
Flowable fill shall be in accordance with Section 911.

819-3.7 Excavation and Jacking of Pipe:

a. Tunnel Excavation:

1. Keep tunnel excavation within the servitudes and rights-of-way indicated on the
Contract Documents and to the lines and grades designated on the
Contract Documents.

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2. Perform tunneling operations in a manner that will minimize the movement of the
ground in front of and surrounding the tunnel. Prevent damage to structures and
utilities above and in the vicinity of the tunneling operations.

3. Open-face excavations:

i. Keep the face breasted or otherwise supported and prevent falls,
excessive raveling, or erosion. Maintain standby face supports for
immediate use when needed.

ii. During shut-down periods, support the face of the excavation by positive
means; no support shall rely solely on hydraulic pressure.

4. Closed-face excavation:

i. Carefully control volume of spoil removed. Advance rate and excavation
rate to be compatible to avoid over excavation or loss of ground.

ii. When cutting head is withdrawn or is open for any purpose, keep
excavated face supported and stabilized.

5. Excavated diameter should be a minimum size to permit pipe installation by
jacking with allowance for bentonite injection into the annular space.

6. Whenever there is a condition encountered which could endanger the tunnel
excavation or adjacent structures, operate without intermission including 24-
hour working, weekends and holidays, until the condition no longer exists.

7. The Contractor shall be responsible for damage due to settlement from any
construction-induced activities. Replacement of all damaged areas shall be the
responsibility of the Contractor at no additional cost to the Owner.

b. Pipe Jacking:

i. Cushion pipe joints as necessary to transmit the jacking forces
without damage to the pipe or pipe joints.

ii. Maintain an envelope of bentonite slurry around the exterior of the
pipe during the jacking and excavation operation to reduce the exterior
friction and possibility of the pipe seizing in place.

iii. If the pipe seizes up in place and the Contractor elects to construct
a recovery access shaft, approval must be obtained from the
Engineer. Coordinate traffic control measures and utility adjustments as
necessary prior to commencing work.

iv. In the event a section of pipe is damaged during the jacking operation, or
joint failure occurs, as evidenced by inspection, visible ground water
inflow or other observations, the Contractor shall submit for approval his
methods for repair or replacement of the pipe. Any pipe damaged or
misaligned shall be removed and replaced by the Contractor at no
additional cost to the Owner.

v. Overcutting shall be remedied by grouting along the entire length of
the installation.

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vi. All tunneled pipes 36-inches in diameter or larger shall have grout
injection ports built into the pipe at the 12 oclock position for pumping slurry
during the pipe installation and for grouting the annular space once the
tunneling is complete.

819-3.8 Grouting:

819-3.8.1 Preparation:

a. Notify the Engineer at least 24 hours in advance of grouting operations.

b. Select and operate grouting equipment to avoid damage to new or existing
underground utilities and structures.

c. In selection of grouting placement consider pipe flotation, length of pipe, length of
tunnel, depth from surface, and type of sewer pipe, type of pipe blocking and
bulkheading, grout volume and length of pipe to be grouted between bulkheads.

d. The Contractor is to ensure there is no water in the annular space between the
carrier pipe and the tunnel liner prior to pumping the cellular grout into the annular
space.

e. Operate any dewatering systems until the grouting operations are complete.

819-3.8.2 Equipment:

a. Batch and mix grout in equipment of sufficient size and capacity to provide the
necessary quality and quantity of grout for each placement stage.

b. Use equipment for grouting of a type and size generally used for the work, capable of
mixing grout to a homogeneous consistency, and providing means of accurately
measuring grout component quantities and accurately measuring
pumping pressures. Use pressure grout equipment, which delivers
grout to the injection point at a steady pressure.

819-3.8.3 Pressure Grouting for Jacked or Pulled Pipe:

a. For jacked pipe 60 inches in diameter or greater, pressure grout the annulus
after installation, displacing the bentonite lubrication. Jacked or pulled pipes less
than 60- inch diameter may be left ungrouted unless the excavated diameter
exceeds the external pipe diameter by more than one inch.

b. Inject grout through grout holes in the sewer pipe. Drilling holes from the surface
or through the carrier pipe walls is not allowed. Perform grouting by injecting it at
the pipe invert with bentonite displacement occurring through a high point tap or
vent.

c. Control ground water as necessary to permit completion of grouting without
separation of the grout materials.

d. Limit pressures to prevent damage or distortion to the pipe or to keep flexible
pipe within acceptable tolerances.

e. Pump grout until material discharging is similar in consistency to that at point of
injection.

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819-3.8.4 Pressure Grouting for Shaft Liner:

a. If required, perform grouting operations to fill voids outside of the shaft liner.

b. For nonexpendable primary liners installed by hand mining or in shafts, grout once
every 4 feet or more frequently if conditions dictate.

c. Control grout pressures so that shaft liner is not overstressed, and ground heave is
avoided.

d. For liner requiring grout, perform back grouting once each shift, or more often if
required to ensure that all voids are filled.

819-3.8.5 Ground Stabilization Grouting:

a. Completely fill voids outside the limits of excavation caused by caving or collapse of
ground. Fill with gravity or pressure injected sand-cement grout as necessary to fill
the void.

b. Take care in grouting operations to prevent damage to adjacent utilities or public or
private property. Grout at a pressure that will not distort or imperil any portion of the
work or existing installations or structures.

c. Verify that the void has been filled by volumetric comparisons and visual inspection.
In the case of settlement under existing slabs, take cores as directed by the
Engineer, at no additional cost to the Owner, to demonstrate that the void has been
filled.

819-3.8.6 Field Quality Control:

a. Pressure Grouting for Shaft Liners. For each shaft, make one set of four
compressive test specimens for each 30-foot depth and one set for any remaining
portion less than a 30-foot increment.

b. Pressure Grouting for Jacked Pipe. Make one set of four compressive test
specimens for every 400 feet of jacked pipe pressure grouting.

c. Pressure Grouting for Pulled Pipe. Make one set of four compressive test
specimens for every 400 feet of pulled pipe pressure grouting.

d. Ground Stabilization Grouting. Make one set of four compressive test specimens for
every location where ground stabilization grouting is performed.

819-3.9 Control of Line and Grade:

a. Construction Control:

1. Contractor shall check baselines and control points at the beginning of the
Work and report any errors or discrepancies to the Engineer.

2. Use the baselines and control points indicated on the Contract Documents to
establish and maintain construction control points, reference lines and grades for
locating tunnel, sewer pipe, and structures. These control points are given to
assist the Contractor and if deemed necessary the Contractor should
establish additional control points or benchmarks in order to perform the work
accurately.
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3. Establish construction control points sufficiently far from the work so as not to be
affected by ground movement caused by pipe-jacked tunneling
operations.

b. Bench Mark Movement. The Contractor shall ensure that if settlement of the ground
surface occurs during construction which affects the accuracy of the temporary
benchmarks the Contractor shall detect and report such movement and reestablish
temporary bench marks.
c. Line and Grade.

1. Check and record the survey control for the tunnel against an above-ground
undisturbed reference at least once for each 250 feet of tunnel constructed.

2. Record the exact position of the MTBM, TBM, PTMT or shield after each
shove to ensure the alignment is within specified tolerances. Make immediate
correction to alignment before allowable tolerances are exceeded.

3. When excavation is off line or grade, make alignment corrections to avoid
reverse grades in gravity sewers. A belly in the tunnel which will hold water is not
acceptable and shall be replaced at no additional cost to the Owner.

i. The sewer pipe shall not vary more than plus or minus one inch (1) in
elevation or plus or minus six inches (6) horizontally from the
established line and grade (as shown on the Contract Documents) at any
point between manholes, including the receiving end. The installed
pipe shall not hold water.

ii. Pipe installed outside tolerances and subsequently abandoned shall first
be fully grouted.

819-3.10 Monitoring:

a. Instrumentation Monitoring. Instrumentation specified shall be accessible at all times
to the Engineer. Readings shall be submitted promptly to the Engineer.

1. Install and maintain an instrumentation system to monitor and detect movement
of the ground surface and adjacent structures. Establish vertical control points
at a distance from the construction areas that avoids disturbance due to ground
settlement.

2. Installation of the instrumentation shall not preclude the Engineer, through an
independent contractor or consultant, from installing instrumentation in, on,
near, or adjacent to the construction work. Access shall be provided to the
work for such independent installations.

3. Instruments shall be installed in accordance with the Contract Documents and
the manufacturers recommendations.

4. Monitoring locations given on the Contract Documents are not inclusive and are
given to assist the Contractor. Additional locations may need to be
established by the Contractor. The Contractor is responsible for all
construction induced ground movement and the monitoring thereof.

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b. Surface Settlement Monitoring

1. Establish monitoring points on all critical structures.

2. Minimum monitoring points are indicated on the Contract Documents.

3. Record location of settlement monitoring points with respect to construction
baselines and elevations. Record elevations to an accuracy of 0.01 feet for
each monitoring point location. Monitoring points should be established at
locations and by methods that protect them from damage by construction
operations, tampering, or other external influences.

4. Ground surface elevations shall be recorded on the centerline ahead of the
tunneling operations at a minimum of 100-foot intervals or at least three
locations per tunnel drive. For sewers greater than 60-inch diameter, also
record similar data at approximately 20 feet each side of the centerline.
Settlement monitoring points must be clearly marked by studs or paint for ease
of locating.

5. Monitoring points to measure ground elevation are required at a distance of 0
feet, 10 feet and 20 feet from the perimeter of the shaft on each of four radial
lines, the radial lines being at 90 degrees to each other.

6. Railroads. Monitor ground settlement of track subbase at centerline of each
track.

7. Utilities and Pipelines. Monitor ground settlement directly above and 10 feet
before and after the utility or pipeline intersection.

c. Reading Frequency and Reporting. The Contractor shall submit to the Engineer,
records of readings from the various instruments and survey points.

1. Instrumentation monitoring results to be read at the frequency specified and
unless otherwise specified, shall be started prior to the zone of active
excavation reaching that point, and shall be continued until the zone of active
excavation has passed and until no further detectable movement occurs.

2. Surface settlement monitoring readings shall be taken:

i. Prior to the zone of active excavation reaching that point,

ii. When the tunnel face reaches the monitoring point (in plan), and

iii. When the zone of active excavation has passed and no further
movement is detected.

3. All monitoring readings shall be submitted promptly to the Engineer.

4. Immediately report to the Engineer any movement, cracking, or settlement
which is detected.

5. Following completion but prior to final acceptance, make a final survey of all
monitoring points.

819-4 DISPOSAL OF EXCESS MATERIAL: Remove spoil in accordance with Section 801.

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819-5 ACCEPTANCE TESTING: Acceptance testing and inspection is to be carried out by methods
described in Section 802.

819-6 SITE RESTORATION: All surfaces affected by the Work shall be restored to their
preconstruction conditions. Performance criteria for restoration work will be similar to those
employed in traditional open excavation work as described in Section 903.

819-7 POST CONSTRUCTION EVALUATION:

a. The Contractor shall provide a set of Field Record Drawings including both alignment
and profile to the Engineer. Drawings should be developed from actual field
readings. Raw data should be available for submission at any time upon request.
As part of the Field Record Drawing, the Contractor shall specify the tracking
equipment used, including method of confirmatory procedure used to ensure the
data was captured. Field Record Drawings having survey data shall be stamped by
a Professional Land Surveyor registered in the State of Louisiana.

b. All fittings, valves, manholes, connections, etc., including all critical structure
monitoring points as shown on Contract Documents, shall be located by GPS and
based on the Louisiana State Plane - South coordinate system as shown on Contract
Documents and shall be provided on the Field Record Drawings. No landmarks
shall be used. The record drawings shall be stamped by a Professional Land
Surveyor registered in the State of Louisiana.

819-8 MEASUREMENT:

a. Microtunneled Pipe: Measurement for the installation of microtunneled sewer pipe
shall be made horizontally, on a linear foot basis, for various sizes listed in the Bid
Form, as designated on the Contract Documents; and to the end of stubs or the
termination of the pipe; and to the inside face of pump station and treatment plant
works.

b. Tunnel Shaft: Measurement for tunnel shafts (includes entry and receiving pits and
any construction access shafts) utilized to facilitate construction of the proposed
sanitary sewer by tunneling (regardless of method) shall be on a lump sum basis, as
specified in the Contract Documents.

819-9 PAYMENT:

a. Microtunneled Pipe: Payment for this Item shall be full compensation for pipe and
fittings, sewer flow control, plugging and bypass, connections to existing pipe and
service lines when no separate payment is made under another Bid Item, jointing,
bedding, traffic control, testing, and clean-up in accordance with the Specifications;
and all else incidental thereto for which separate payment is not provided under any
other item in the Bid Form.

b. Tunnel Shaft:

1. Payment for this Item shall be made at the contract lump sum price, as
specified in the Contract Documents. This payment shall be full
compensation for labor, equipment, submittals, materials and supervision for the
construction and excavation of the proposed shafts (regardless of size, type
and number of shafts), complete in place, including traffic control, disposal
of excess materials, bedding, backfill and compaction, surface restoration
(including sawcutting, pavement removal and replacement) monitoring
(including associated instrumentation and premonitoring activity) as per
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specifications, protection of existing structures and utilities (gas, water, sanitary
sewer, power, telephone), utility adjustments, sheeting, shoring or bracing,
dewatering, grouting (if required), cleanup, ground support systems, post
construction evaluation; and all else incidental thereto for which separate payment
is not provided under any other item in the Bid Form.

2. The Contractor, prior to construction shall provide a schedule of values. On this
schedule of values, the Contractor shall itemize the cost by station, diameter
and depth for each tunnel shaft necessary to complete the work and any
additional shafts required for construction operations.

819-10 PAY ITEMS:

Pipe Inner Diameter (I.D.) Schedule
(as Shown on Drawings)

A = 4" Pipe N = 27" Pipe
B = 6" Pipe O = 30" Pipe
C = 8" Pipe P = 32" Pipe
D = 10" Pipe Q = 36" Pipe
E = 12" Pipe R = 42" Pipe
F = 14" Pipe S = 48" Pipe
G = 15" Pipe T = 54" Pipe
H = 16" Pipe U = 60" Pipe
I = 18" Pipe V = 64" Pipe
J = 20" Pipe W = 66 Pipe
K = 21" Pipe X = 72 Pipe
L = 24" Pipe Y = 76 Pipe
M = 26" Pipe Z = 80 Pipe

Item No. Description Units

819100_

819110_

8192000

_ _ Microtunneled Pipe

_ _ Pilot-Tube Microtunneled Pipe

Tunnel Shafts
Linear Feet
Linear Feet
Lump Sum