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Regional Connector Transit Corridor Project Excavation By TBM EXCAVATION BY TUNNEL BORING MACHINE 31 71 19 - 1 SECTION 31 71 19 EXCAVATION BY TUNNEL BORING MACHINE PART 1 - GENERAL 1.1 DESCRIPTION A. The Work specified in this Section consists of excavating Tunnel Boring Machine (TBM) driven tunnels in material as described in the Contract Documents; and constructing interfaces with cut- and-cover structures. B. Definitions: 1. Slurry TBM - A TBM with a pressure bulkhead located behind the face to form a plenum under pressure. Bentonite slurry or other liquid medium is introduced into the plenum chamber under controlled pressure to stabilize the face and to be mixed with material excavated by the rotary cutterwheel. The resultant slurry, with cuttings, is removed by pumping. 2. Earth Pressure Balance (EPB) TBM - A TBM with a pressure bulkhead located behind the face to form a plenum under pressure. Liquids and conditioners are injected into the plenum to be mixed with material excavated by rotary cutterwheel. The mix is extracted by means of a screw mechanism in an operation integrated with the TBM advance. 3. Tunnel Boring Machine (TBM) – General terminology referring to either a Slurry TBM or an EPB TBM and refers to the total system of tunnel boring equipment and auxiliary and support equipment comprising the TBM, backup gear and all equipment and materials affixed thereto. C. The Work includes: 1. Providing TBM(s) capable of excavating and supporting the tunnel in accordance with the requirements given in the Contract Documents. a. Design (in association with the TBM manufacturer) TBM(s) and all backup equipment and systems to operate under the earth and groundwater pressures and gaseous condition in all ground conditions as indicated in the Geotechnical Baseline Report (GBR) and to be compatible with the segmental tunnel lining to be installed. b. Meet all applicable standards for the tunnel classification for gas. 2. Furnishing and installing the initial permanent tunnel support consisting of bolted and gasketed precast concrete segments as specified in Sections 31 74 16, Precast Concrete Segmental Tunnel Lining. The concrete segments are called herein the “lining” or “liner.” 3. Furnishing and placing backfill grout behind precast concrete lining to fill the annular space between lining extrados and excavated surface in accordance with Section 31 73 00, Tunnel Grouting. C0980 ISSUED FOR SOLICITATION: 01/07/13 ADDENDUM 1: 02/25/13

EXCAVATION BY TUNNEL BORING MACHINE … · Excavation By TBM EXCAVATION BY TUNNEL BORING MACHINE 31 71 19 - 1 SECTION 31 71 19 EXCAVATION BY TUNNEL BORING MACHINE . PART 1 - GENERAL

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Regional Connector Transit Corridor Project

Excavation By TBM EXCAVATION BY TUNNEL BORING MACHINE

31 71 19 - 1

SECTION 31 71 19

EXCAVATION BY TUNNEL BORING MACHINE

PART 1 - GENERAL

1.1 DESCRIPTION

A. The Work specified in this Section consists of excavating Tunnel Boring Machine (TBM) driven tunnels in material as described in the Contract Documents; and constructing interfaces with cut-and-cover structures.

B. Definitions:

1. Slurry TBM - A TBM with a pressure bulkhead located behind the face to form a plenum under pressure. Bentonite slurry or other liquid medium is introduced into the plenum chamber under controlled pressure to stabilize the face and to be mixed with material excavated by the rotary cutterwheel. The resultant slurry, with cuttings, is removed by pumping.

2. Earth Pressure Balance (EPB) TBM - A TBM with a pressure bulkhead located behind the face to form a plenum under pressure. Liquids and conditioners are injected into the plenum to be mixed with material excavated by rotary cutterwheel. The mix is extracted by means of a screw mechanism in an operation integrated with the TBM advance.

3. Tunnel Boring Machine (TBM) – General terminology referring to either a Slurry TBM or an EPB TBM and refers to the total system of tunnel boring equipment and auxiliary and support equipment comprising the TBM, backup gear and all equipment and materials affixed thereto.

C. The Work includes:

1. Providing TBM(s) capable of excavating and supporting the tunnel in accordance with the requirements given in the Contract Documents.

a. Design (in association with the TBM manufacturer) TBM(s) and all backup equipment and systems to operate under the earth and groundwater pressures and gaseous condition in all ground conditions as indicated in the Geotechnical Baseline Report (GBR) and to be compatible with the segmental tunnel lining to be installed.

b. Meet all applicable standards for the tunnel classification for gas.

2. Furnishing and installing the initial permanent tunnel support consisting of bolted and gasketed precast concrete segments as specified in Sections 31 74 16, Precast Concrete Segmental Tunnel Lining. The concrete segments are called herein the “lining” or “liner.”

3. Furnishing and placing backfill grout behind precast concrete lining to fill the annular space between lining extrados and excavated surface in accordance with Section 31 73 00, Tunnel Grouting.

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4. Designing, furnishing and using slurries, conditioners, polymers, bentonite and/or other soil conditioning agents (all referred to herein as conditioners) required to maintain face stability (with positive face support), reduce wear, prevent accumulation of gas in excavation chamber, advance the heading, and transport spoils in these ground conditions with the equipment selected.

5. Designing and furnishing slurry treatment plant as required if a Slurry TBM is used.

6. Removing temporary bulkhead and support members and stabilizing ground at breakouts as required.

7. Installing and maintaining temporary drainage, lighting, power, water and ventilation in the excavations.

8. Drilling continuous probe holes ahead of each tunnel face as required by CAL/OSHA.

9. Furnishing, drilling for, and placing check grout, in accordance with Section 31 73 00, Tunnel Grouting, to verify ground conditions and stabilize disturbed ground, as required, above the tunnel crown.

10. Removing obstructions, objects or materials encountered during tunneling that unavoidably slow or stop the process of tunneling work. Refer to GBR for anticipated obstructions.

10.11. Arranging and providing a primary power system and a back-up power system comprising site-generated power at project sites. Capable of providing uninterrupted operation of essential tunnel support services such as ventilation, lighting, and pumping.

1.2 QUALITY CONTROL

A. Comply with Section 01 43 10, Project Quality Program Requirements – Design/Build.

B. Worksite Personnel

1. The Contractor’s Project Manager, Tunnel Superintendents, TBM master mechanics, Project engineers, tunnel engineers, and tunnel foremen shall have successfully completed at least one similar tunneling project using similar equipment. A similar project means a tunnel driven in soft rock and/or a tunnel driven in saturated alluvial soils, mixed face soils, at least 5,000 feet in length and 14 feet in diameter, driven using the type of TBM employed on this project.

2. All TBM operators and Contractor's master mechanic(s) shall be trained by the machine manufacturer before start-up of TBM.

3. TBM Operators: Use operators with prior experience on a similar project as defined above for the initial 1000 ft of tunnel drive in each tunnel.

4. Technical representative from the manufacturer: knowledgeable in the assembly, operation, maintenance and repair of TBM, and to be on site throughout the first 1000 ft of each tunnel drive and first 1000 ft of drive for each new operator. Train additional operators during the first drives.

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C. Certification

1. TBM drawings and calculations prepared and certified by a professional engineer registered in California with a minimum prior experience in responsible design of two TBMs of the type to be used in the Work.

2. Manufacturer certification that TBM, as assembled, meets performance requirement and is ready for operation, and that operators are qualified to operate TBMs and backup systems.

3. Certification of main bearing seals design: employ an independent reviewer who has been in responsible charge of at least five similar designs to review main bearing seal design for compatibility with expected tunneling conditions.

D. TBM “fit-up” and demonstration tests: conduct at factory in presence of Metro before shipping to Worksite and onsite before launch of machine for each tunnel drive.

E. Develop and implement Contractor's Plan of Operation to meet HOLD POINTS as follows. In all

cases, contact with building owners, occupants, or any public or private entity will be by Metro.

1. Prior to tunneling under private property:

a. Notification to owners and tenants.

b. Plan in place for TBM operation and any supplemental measures to limit settlements to required levels.

c. Where used, ground improvement by grouting and installation of compensation grout pipes are complete.

d. Instrumentation for monitoring settlement and distortion of structures and ground in place, calibrated, and read in accordance with Section 31 09 13 Geotechnical Instrumentation and Monitoring.

e. Demonstration of TBM functions to control ground movements as specified in Part 3.

2. Prior to tunneling under LA County 2nd Street Storm Drain and 3rd /Flower Street Chilled Water Pipes

a. Notification to the owner.

b. Plan in place for TBM operation and any supplemental measures to limit settlements to required levels.

c. Where used, ground improvement by grouting and installation of compensation grout pipes are complete.

d. Instrumentation for monitoring settlement and distortion of structures and ground in place, calibrated, and read in accordance with Section 31 09 13 Geotechnical Instrumentation and Monitoring.

e. Demonstration of TBM functions to control ground movements as specified in Part 3.

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3. Prior to tunneling under Red Line tunnels:

a. Notification to Metro.

b. Plan in place for TBM operation and any supplemental measures to limit settlements to required levels.

c. Where used, ground improvement by grouting and installation of compensation grout pipes are complete.

d. Instrumentation for monitoring settlement and distortion of structures and ground in place, calibrated, and read in accordance with Section 31 09 13 Geotechnical Instrumentation and Monitoring.

e. Demonstration of TBM functions to control ground movements as specified in Part 3.

4. Prior to Tunneling in zone of influence of sanitary sewers and storm sewerdrains:

a. Notification to City of Los Angeles Bureau of Engineering.

b. Review of CCTV inspections of Sewers.

c. Verify emergency equipment and materials are on hand and Spill Response Plan (City of Los Angeles Standard Specification for Construction related Spill Prevention and Response Requirements per Special Provisions) has been approved by Metro and City of Los Angeles.

d. Plan in place for TBM operation and any supplemental measures to limit settlements to required levels.

e. Instrumentation for monitoring settlement and distortion of structures and ground in place, calibrated, and read in accordance with Section 31 09 13 Geotechnical Instrumentation and Monitoring.

1.3 REFERENCE STANDARDS

A. ASTM International (formerly American Society for Testing and Materials).

B. California Department of Industrial Relations: Division of Occupational Safety and Health (DOSH) – Cal/OSHA 1. California Code of Regulations (CCR): Title 9, Industrial Relations

B. California Division of Occupational Safety and Health - California Code of Regulations:

1. Title 8. Industrial Relations, Division 1. Department of Industrial Relations, Chapter 4. Division of Industrial Safety, Subchapter 5. Electrical Safety Orders

2. Title 8. Industrial Relations, Division 1. Department of Industrial Relations, Chapter 4. Division of Industrial Safety, Subchapter 20. Tunnel Safety Orders

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C. US Department of Labor:

1. -Occupational Safety and Health Administration, 29 CFR 1926 Safety and Health Regulation for Construction

1.2. Mine Safety and Health Administration, 30 CFR 36 Approval Requirements for Permissible mobile Diesel-powered Transportation Equipment.

1.4 SUBMITTALS

A. Make submittals in accordance with Section 01 33 00, Submittal Procedures. A.B. Rebuilt TBM: If Contractor proposes to use rebuilt TBM(s), submit the following information.

1. Features of each proposed TBM, with a technical description, including manufacturer and year originally built, and general arrangement drawings of TBM and backup equipment, including but not limited to the cutters, cutterhead and overcut, conditioner injection systems, integrated support pressure control system, compressed air lock, thrust and steering systems, drive system, muck system, main bearing and tail seals and grease injection system, bentonite injection and pressure monitoring systems on shield body, guidance system, probe hole drilling system, tunnel liner description, backfill grouting system, check grouting system, ventilation system, segment erector, segments, muck transport system, gas monitoring system, and slurry treatment facility if applicable.

2. Sufficient detail such that Metro can evaluate each proposed (rebuilt) TBM against these specifications.

3. Complete descriptions of the changes and/or modifications to the features that will be made during the rebuilding process so that the rebuilt machine(s) will be in compliance with the specifications and performance prescribed herein.

a. Clearly identify the components by name, type, and use that will be rebuilt, reconditioned, replaced, or used as-is in the rebuilt TBM,

b. Certification, with the original manufacturer, that any reconditioned, new or used component supplied with the re-built TBM is fully capable of meeting the criteria for successful completion of the tunnel drives for this project.

c. History of all previous use of TBM including names of projects, description of projects, lengths of tunnel drives, ground conditions, ground support system, and settlement records. Provide names of references and current phone numbers for each of the above projects. Demonstrate successful performance of TBM with respect to ground control and settlement. Include equipment outage history for proposed rebuilt TBM identifying by name, type, and use any element of the TBM that was refurbished or reconditioned during its previous tunnel drive(s).

4. Approval of rebuilt TBM(s) does not relieve Contractor from its responsibility for completing tunneling work in accordance with these specifications. Contractor shall be fully responsible for any delays related to reconditioning, delivery, maintenance, repair, or performance of re-built tunneling equipment.

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B.C. Contractor Personnel Qualifications and Experience:

1. Resumes or documentation of applicable experience required for worksite personnel identified in Article 1.2, Quality Control requirements, above. Provide statements affirming each personnel's sole commitment to this project, if not submitted with Contractor’s proposalBid qualification documents. An example form to be used with submittals is contained in Appendix A.

D. Construction schedule, including:

1. Schedule for the design, manufacturing (and/or rebuilding), shop erection and testing, dismantling, and shipment to Worksite of TBM and all backup equipment and systems.

2. Assembly time, start-up time, and on-site training period planned to reach routine tunneling progress rates for execution of the Work.

3. Estimated average daily advance for tunnel excavation, in feet/day, for key increments of the tunnel, from start TBM to finish TBM excavation. Include details of resources to be utilized (personnel, locomotives, muck cars, etc.) and hours and shifts to be worked to achieve these rates.

4. Estimated average liner erection rate in minutes per ring.

E. TBM Tunneling Initial Work Plan:

1. General Arrangement Drawings for all TBM(s) from TBM manufacturer showing complete technical descriptions and details of TBM and backup equipment layout including detailed scale drawings with sufficient vertical and horizontal sections at tunnel axis and cross sections to clearly identify the different components of the TBM. Show the features of each TBM including but not limited to:

a. Cutters cutterhead, and overcut

b. Integrated support pressure control system

c. Conditioning system

d. Thrust, articulation, and steering systems

e. Drive system

f. Mucking system

g. Main bearing and tail seals and grease injection system

h. Bentonite injection and pressure monitoring systems on shield body

i. Backfill grouting system

j. Check grouting system

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k. Guidance system

l. Probe hole drilling system

m. Rock crusher for slurry TBM

n. Compressed air locks

o. Gas monitoring system

p. Fire suppression system

q. Schematic electrical system

r. Ventilation system

s. Segment erector and interface of TBM with the segmental lining

t. Slurry pumping and piping system, and treatment facility if applicable

2. List and description of TBM spare part.

3. Written certification from TBM manufacturer of full and complete design coordination between TBM manufacturer, backup equipment manufacturer and lining manufacturer. Include a written certification by the contractor and manufacturers affirming the compatibility of TBM and backup equipment with lining systems, segment erector, and continuous backfill injection system.

4. Description of work related to inspection or removal of boulders or obstructions, maintenance or repair requiring access to TBM face using compressed air, and other supplemental ground stabilization methods as required.

5. Details of spoils removal system from TBM through tunnels and cut-and-cover excavations to surface work area.

6. Documentation and certification of main bearing and seal design conditions, calculations, and design life for the TBM to be furnished, along with qualifications of independent seal design reviewer.

7. Description of methods for replacement of cutterhead main bearing, cutterhead seal(s), and cutters from within tunnel.

8. Program for fire prevention and mitigation.

9. Working Drawings for tunnel interfaces with cut-and-cover excavation.

10. Means and methods for drilling probe holes and for checking for hazardous and explosive gases.

11. Proposed method of calculating and monitoring the face pressure required to maintain face stability and the means and methods for changing the pressure as function of tunnel depth, ground water level, surface settlement, and geologic materials.

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F. Detailed Work Plan:

1. Work Plan (method statement) covering the intended machine parameters to achieve required pressure at the tunnel face for expected ground conditions described in the Contract Documents including, boulder excavation, cutterhead rotation speed and torque, thrust, screw conveyor rotation speed and torque, discharge rate, rate of advance, muck conditioning materials and mix quantities, and volumetric and pressure control of screw conveyor, slurry return line, or other discharge system.

2. Planned face pressures to be maintained for each reach and soil type, along with supporting calculations. Indicate tolerable limits for fluctuations in face pressure including target, minimum, and maximum face pressures.

3. Procedures for checking for and preventing accumulation of gas in excavation chamber at all times, and for venting gas and refilling excavation chamber.

4. Project-specific work plan to continuously use TBM performance monitoring data by the TBM operator and the Contractor’s tunnel supervision to construct the tunnel. Describe how TBM performance monitoring system to be used to assist in TBM tunnel construction.

5. Work Plan covering the start-up of TBM and the launch of TBM into ground through cut-and-cover structure, including:

a. Means for testing and verifying the efficacy of ground treatment, including basis for contractor-responsible design parameters.

b. Details of the seals to be used at the structure walls and other measures to be taken to minimize loss of ground and to provide groundwater control while the TBM advances sufficiently to complete the installation of several liner rings.

c. Method of preparing for breaking into cut-and-cover structures. Integrate with plan for prior performance of ground treatment, as required at cut-and-cover structures, and removing bulkhead.

d. Details for tunnel and cut-and-cover structure interfaces.

6. For slurry TBM:

a. Details of slurry treatment plant, treatment plant operations, disposal of slurry, and plant capabilities relative to anticipated ground conditions, and

b. Quality control testing program for slurry including a description of required tests and range of values considered acceptable for ground conditions anticipated for each tested parameter.

c. Processing rate of the slurry treatment plant for major grain-size material classifications.

7. For EPB TBM:

a. Types of conditioners to be used

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b. Mixing methods of conditioners

c. Proposed muck to conditioner ratios

d. Description of site conditions in which conditioners will be used

e. Logic to be used in determining when, which, and how much of conditioners to add

f. Quality control program for conditioners including description of quality control tests to be used in the field indicating the range of values considered acceptable for ground conditions anticipated

g. Ventilation plan to control, remove, and dilute gas introduced by off-gassing from excavated muck exposed in the tunnel.

8. Detailed description of proposed TBM guidance system including how guidance system interfaces with conventional laser, how the control is brought underground, how it is used by the TBM operator to monitor machine performance, how it interfaces with specified TBM operational systems and lining ring placement and grouting sequence to minimize deviations from the theoretical tunnel alignment, how it will be used to correct misalignment, and format of data to be provided to Metro.

9. Detailed description of the backfill grout mix, method, and procedure proposed, demonstrating that grouting provides the required strength, deformation and set time characteristics while driving the tunnel. Include a description of the grouting system to demonstrate the capability of complete, immediate, and uniform filling of the annular tail void as the TBM advances, and how grout set time is designed to ensure consistency with the planned rates of advance of the TBM. Include method of measuring grout volumes and pressures. Include logic used to determine grout composition and pressures as a function of tunnel depth, rate of advance, ground, and groundwater conditions.

10. Detailed description of the check grout mix, method, and procedure. Include method of measuring grout volumes and pressures. Include logic used to determine grout composition and pressures as a function of tunnel depth, ground, and groundwater conditions.

11. Proposed segment joints, geometry, seals, compression packing if used, gaskets, gasket materials or other items required by the selected means, methods, procedures, or equipment to successfully retain and complete the grouting operations.

12. Procedure for monitoring and maintaining pressure in conditioned soil (EPBM) or slurry (slurry TBM) behind cutterhead. Procedure for injecting and monitoring volume and pressure of bentonite injected in overcut annulus space outside the shield.

13. Details of the TBM and backup system, gas detection system, its equipment interlocks, alarms, set points, and operating logic network diagram. Include description of calibration data for gas detection instruments to be provided and procedures for operation.

14. Details of special precautions and the inspection procedures to be taken when stopping the machine for repair, weekends, holidays, and other scheduled stoppages to ensure that face stability is maintained and hazardous/explosive gases are not accumulated in excavation

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chamber during the shutdown. Include contingency measures to be implemented if problems in ground, groundwater, or gas control develop or power to TBM is lost.

15. Means and methods of verifying hazardous/explosive gases are purged before any personnel are allowed to enter excavation chamber.

16. Methods of correcting tunnel alignment if the specified driving tolerance is exceeded.

17. Methods of measuring each lining ring and of correcting lining ring for non-planarity and/or non-circularity that may cause segment or gasket damage or leakage if not detected and corrected. Include corrective measures to be taken should specified tolerances be exceeded.

18. Details of the mechanisms of the thrust jacks to prevent any eccentric or excessive loads to the segments or gaskets creating a potential for damage, and intended corrective measures to be taken if jack misalignment or liner or gasket damage should occur.

19. Overall operational procedures for the TBM including on-site assembly testing before start-up, supervisory staff organization and site responsibilities for each position.

20. Compressed air work:

a. Details of the TBM air lock or compressed air chamber, its locking and bulkhead designs, the sealing arrangement, the life support requirements, and the mechanism supporting the lock inside the tunnel. Include a detailed description of procedures for operating the airlock, effecting compression/decompression, operating details, gas monitoring, and emergency work plan.

b. Details of medical lock for decompression of workers following entry into the pressure chamber of the TBM under compressed air. Medical lock shall meet all requirements as defined by OSHA Regulations Standards – 29 CFR, 1926.803 Subpart S for working under compressed air, California Division of Occupational Safety and Health - Title 8, Chapter 4. Division of Industrial Safety Subchapter 20. Tunnel Safety Orders, and as specified in Section 01 57 23, Environmental Management of Excavated Materials.

21. Methods for monitoring the volume and weight of material excavated and removed from the face.

22. Action Plan for tunneling and control of settlement: Describe in detail plan(s) for corrective measures to be implemented should the settlement action or maximum levels be reached.

23. Means and methods for controlling groundwater inflows, and type and extent of ground treatment.

24. Calibration methods for pressure cells in excavation chamber.

25. Product data, description of injection system, means and methods for seal grease.

G. Certifications prior to start of tunneling, and as required during operations:

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1. TBM Manufacturer: Written certification that all operators and master mechanics have completed training on similar equipment and at manufacturer’s plant for this project's equipment and are qualified and ready for machine operation.

2. Calibration certificates for gas detection system, pressure cells in excavation chamber, TBM guidance system, thrust jacks, and annular backfill grout pressure gauges. Provide these certificates every 30 days during which TBM tunneling is taking place.

3. For individuals authorized to perform gas testing.

H. Continuous monitoring data of TBM performance for the duration of bored tunnel excavation:

1. Real-time data of machine functions via integrated system that provides remote access through internet or intranet to data and data reductions stored.

2. Continuous time plots of:

a. Face pressures (individual measurement and average)

b. Overcut annulus pressures outside the shield (individual measurement and average)

c. Volume and weight of material excavated and removed from the face

d. Extensometer and vibrating wire piezometer readings at the nearest locations to the tunnel face.

I. Within one working day of occurrence, except where otherwise specified:

1. Daily reports for each manned shift, including periods when the TBM is not excavating. Include manning requirements, start and end station of the TBM, muck car counts (as applicable to EPB TBM excavation), lining ring data, description of delays of individual or cumulative duration greater than 15 minutes, water inflow, incidence of ground loss, deviations from work plan, or other unusual events.

2. Cutter and muck system component change record, including time and date of replacement, cutter or component position or number, and reason for change(s).

3. For each erected ring, an individual record of all relevant construction information, including:

a. Station numbers.

b. Time shove started and finished.

c. Time lining erection started and finished.

d. History of face pressure throughout shove.

e. Instantaneous advance rate of shield during shove.

f. Orientation of lining ring (position of key).

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g. Grout pressures and quantities.

h. Complete record of measurements, with records of grouting for each ring daily.

i. Delays during shoving or lining erection.

j. Problems encountered such as water seeps.

k. Damages to lining segments or gaskets during erection or after start of shoving for the next ring; correction of such damage or replacement of damaged liner or gasket; changes to means or methods to prevent recurrence.

l. Soil classificationdescriptions.

4. Records of deformation and/or damage for each lining element including repairs effected, water inflows, etc.

5. Air quality reports - Records of air and gas monitoring. Test and monitoring reports as required (for oxygen level and for dust, toxic and hazardous gases, and other atmospheric impurities in the working environment) by CAL/OSHA, the City of Los Angeles, Federal Agencies and Metro.

6. Results of strength tests for the injected tail void grout.

7. For slurry TBM, results of quality control tests including volume and density of the slurry.

8. Quality control tests for conditioners. Test minimum of twice each shift (four hours apart)

9. Notify Metro immediately upon detecting slurry or muck spills.

J. At least 30 days prior to start of tunneling, schedule an Action Level Plan workshop to inform and train project staff of requirements when settlement indicators show that Action Levels have been reached. Participants are specified in Part 3 of this specification. Coordinate this workshop with other requirements specified in Section 31 09 13, Geotechnical Instrumentation and Monitoring.

K. As-built survey of the tunnel bore within 30 days of completion of each tunnel drive.

L. Immediate notification to Metro of any tunnel misalignments or lining non-planarity and proposed corrective action.

M. Ten days before beginning any non-emergency remedial measures, such as minor leak sealing,

submit a plan for approval by Metro; and do not begin implementation of work until such plan has been approved in full by Metro.

1.5 WORKSITE CONDITIONS

A. The underground work has been classified as potentially gassy by the State of California, Department of Industrial Relations, Division of Occupational Safety and Health Administration (CAL/OSHA). Provisions of the Tunnel Safety Orders and Compressed Air Safety Orders of the State of California shall apply together with other applicable State and Federal Laws and Regulations. Upon completion of tunnel excavation, and, if conditions warrant such action, the

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Contractor may apply to CAL/OSHA for reclassification of tunnels.

B. Regardless of the classification of the tunnel, any electrical equipment and services shall be approved and permissible in accordance with California Code of Regulations, Title 8, Electrical Safety Orders for hazardous (classified) locations, and any mobile diesel powered equipment shall be approved and permissible in accordance with Mine Safety and Health Administration Title 30. Code of Federal Regulations, Part 36. Approval Requirements for Permissible mobile Diesel-powered Transportation Equipment.

N.C. Regardless of the classification of the tunnel, smoking and smoking materials are prohibited at any time underground.

O.D. Contractor shall be solely responsible for compliance with CAL/OSHA underground classification, developing construction equipment, means, methods and procedures that fully recognize and resolve the impacts of hazardous gases as anticipated as described in GBR and their reactive compounds and by-products on equipment, the work environment, and the public. These impacts include, but shall not be interpreted to be limited to, corrosion, explosive and hazardous gas, and malodorous discharges.

P.E. Subsurface conditions as described in the Contract Documents.

PART 2 - PRODUCTS

2.1 GROUT

A. As specified in Section 31 73 00, Tunnel Grouting, and herein.

2.2 PRECAST CONCRETE SEGMENTS

A. As specified in Section 31 74 16, Precast Concrete Segmental Tunnel Lining.

2.3 TUNNEL BORING MACHINES

A. General

1. Using Earth Pressure Balance (EPB) TBM or Slurry TBM is a Contract requirement. Provide a pressurized ground support to the face and around shield body and pressurized grouting through the tail seal with the pressure maintained until the annular grout has set. Fill the annulus of around the body of the TBM with a pressurized slurry material or remolded soil prior to injection of pressurized annular grout through tail shield ducts.

2. Perform the work using a new or reconditioned/rebuilt TBM(s) including trailing gear. Reconditioned/rebuilt TBM(s) are permitted subject to meeting the requirements of these specifications.

3. Provide TBM(s) and back-up equipment to operate in all conditions indicated in the Contract Documents, and as amplified herein.

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4. Design TBM and backup equipment to negotiate minimum curves in the alignment and meet the specified alignment tolerances.

5. Diameter of excavated tunnel: as required to produce minimal over-excavation and least necessary clearance. Take into account horizontal and vertical alignment to be negotiated.

6. Provide TBM designed to maintain face stability and minimize water/gas inflow and surface settlements at all times under all conditions indicated for each reach during both excavation and periods of TBM shutdown.

B. Electrical System

1. Primary power distribution system capable of limiting high-voltage fluctuations when starting up or shutting down the TBM.

2. Emergency standby generator capable of automatically coming on-line in the event of a power failure to operate ventilation, lighting, pumping, communications and other safety support systems without interruption.

3. Power interrupt system that automatically shuts down power to the TBM and trailing equipment upon detection of an air quality event exceeding the regulation limits, while maintaining power to essential services such as ventilation, emergency lighting, dewatering pumps, and safety support systems.

B.C. Excavating Tools and Cutterhead

1. Design TBM to be capable of handling boulders of the maximum size indicated in the Contract Documents including provision for installation of disc cutters on the cutterhead, which in combination with the size of opening in the cutterhead limits the size of cut boulders entering the excavation chamber. In the case of the slurry TBM, this will be the size that can be dealt with by the rock crusher. In the case of an EPB TBM this will be the size that can be passed by the screw conveyor.

2. After completion of the first drive of each TBM, replace all cutting tools before starting the next drive, and repair any other damage to cutterhead, mucking system, or other components before the TBM restarts.

3. Design TBM(s) to have interchangeable disc cutters and ripper teeth. Disc cutters shall be capable of cutting and removing hard materials, including boulders and hard layers as described in the Contract Documents. Design disc cutter seals and bearings to perform in the full range of conditions indicated. Maintain a complete set of disc cutters, including spares as recommended by the manufacturer on site at all times.

4. Design the TBM for maximum abrasion resistance and durability based on anticipated conditions. Design cutting tools for maximum life. Design the TBM to be capable of replacing cutters, cutterhead seals, and drag teeth from behind the cutterhead.

5. Provide a remote reading wear indicator system to indicate when cutting tools require replacement.

6. Provide adjustable gauge cutters.

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7. Provide cutterhead with flood-doors that can be closed mechanically and remotely from the TBM operator's console. When flood-doors are fully open, the maximum opening width shall limit the passage of boulders as specified above.

8. Equip TBM with a minimum six pressure cells evenly distributed through invert, springline, and crown to monitor pressure in plenum chamber and in overcut annulus space outside of shield and behind cutterhead.

9. Equip TBM to monitor gas concentration and pressure and prevent accumulation of hazardous and explosive gases in plenum chamber, and to vent or replace air/gas mixture by bentonite injection in plenum chamber.

10. For access to the tunnel face and pressure chamber behind the cutterhead, fit TBM with compressed air lock(s) and associated compressed air equipment designed for the maximum hydrostatic pressure to which the tunnel is exposed but not less than two bar (30 psi) air pressure.

a. Separate lock for tools and equipment.

b. Feed-throughs into plenum independent of air lock(s) for electrical power, water supply, fire suppression system, high-and-low-pressure air, welding and any other service lines required.

c. Capable of purging the plenum of hazardous gases before entry.

C.D. Soil Conditioners

1. Capable of stabilizing face under all conditions described in the Contract Documents

2. Provide TBM with conditioner injection system to condition the muck as required, and to prevent excavated material from adhering to and clogging the cutterhead chamber, muck passages, or other parts of the TBM.

3. Compatible with selected equipment.

4. Minimizing accumulation of air/gas in plenum chamber.

5. Non-hazardous, biodegradable, not to endanger existing groundwater and compatible with ground conditions described in GBR.

D.E. Thrust System and Steering

1. Design TBM to provide forward propulsion by thrust cylinders that react against the installed segmental liner without damaging the liner.

2. Equip the thrust cylinders with full or partial jacking ring(s), shoes, or pads to distribute the jacking forces to the liner without damaging the liner. Design the thrust cylinder shoes to be consistent with segment and segment joint design while capable of individual and synchronized thrust cylinder actuation while limiting the maximum force that each thrust cylinder may exert so that liners are not damaged. Thrust cylinders shall resist displacements when idle.

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3. Articulate the shield, subject to the following:

a. Design and locate an articulation joint (or joints) as required, to assist constructing the tunnel to the theoretical alignment indicated and within the specified tunnel alignment tolerances.

b. Equip the articulation joint with a seal replaceable from within the skin to prevent the entry of slurry, grout, fines, or other foreign material. Provide a means for cleaning the articulation joint from inside the TBM to maintain its full range of articulation.

E.F. Drive System

1. Provide TBM having sufficient drive motor power so the machine is not torque limited while operating in earth pressure balance mode or slurry mode for any ground materials or conditions described in the Contract Documents.

2. Provide capacity to start cutterhead with not less than 1.5 times rated full load torque.

3. The design life of the main bearing shall be not less than 10,000 hours with a sealing system providing protection for the same period.

4. Design TBM to allow replacement of the main bearing from within the tunnel.

5. Design TBM drive system that operates the cutterhead equally in either direction of rotation.

F.G. Excavated Material Mucking System

1. Fit and operate EPB TBM with a screw conveyor to remove excavated material from the cutterhead chamber. Design the screw conveyor for operation in abrasive soil and for efficient replacement from within the tunnel. Belt conveyor feeding from the cutterhead chamber will not be acceptable.

2. Design the EPB screw conveyor to maintain the required face pressure within the cutterhead chamber and the entrance to the screw conveyor. Reduce pressure to atmospheric at the screw exit by control of the screw conveyor. Design the EPB TBM to be capable of controlling face pressure to within +/- two psi of the desired pressure at all times.

3. Design the EPB screw conveyor to be capable of being closed and sealed against earth pressure at each end. The front of screw conveyor shall be located at the base of the excavation chamber and shall project into chamber when operating. Design the screw to be capable of being withdrawn in order to close front bulkhead door for maintenance.

4. Calibrate pressure cells (EPB or slurry TBM) as recommended by supplier or as needed to assure accuracy of pressure measurements.

5. Design the slurry TBM to work under all conditions described in the Contract Documents. This includes the complete slurry system required to stabilize the face and drive the tunnel. Design the slurry TBM to be capable of controlling the face pressure to within +/- two psi of the desired pressure.

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6. Design slurry treatment plant to accommodate the types and quantities of geologic materials anticipated and to remove the solids from suspension at a sufficiently fast rate so that slurry treatment does not limit the TBM advance rate. Replace or recondition slurry as needed with fresh slurry when the slurry properties are unsatisfactory.

7. Equip Slurry TBMs for measurement of flow, density, and other relevant parameters in both the inbound and outbound slurry lines.

8. Equip EPB TBM with two weight scales integrated into the discharge conveyor.

9. Equip EPB TBM with gas monitoring system to monitor gas concentrations at the screw conveyer discharge door.

10. Equip TBM with state of the art weight/volume monitoring devices for excavated material linked to the TBM data management system to provide determination and reporting of the excavated weight/volume on a real time basis.

G.H. Seals

1. Provide main bearing seals designed for tunneling conditions and maximum pressure anticipated from the sum of all forces acting on the seals simultaneously and all machine operating characteristics related to the main bearings. Design the seals for the articulation joint, tail shield and probe ports for maximum hydrostatic and earth pressure.

2. Design shield tail seals to comprise a redundant system of wire brushes to seal against maximum hydrostatic and backfill grout pressure with due consideration of the liner segment design and the influence of liner grouting in seal design. Provide a minimum of three seals continuously fed with fibrous grease whenever the TBM advances.

3. Design tail seals other than the rear seal so as to be replaceable during a drive from within the tunnel.

H.I. Grouting:

1. Backfill Grouting: Provide a computer operated grouting system linked to TBM systems to calculate grout quantities and continuously adjust grout injection rate and pressure on the basis of the TBM advance rate and other data, and in accordance with requirements specified in Section 31 73 00, Tunnel Grouting. Provide an interlock system so that the TBM cannot be advanced if the grout system is not working.

2. Ground loss check grouting – Refer to Section 31 73 00, Tunnel Grouting.

I.J. Shield Gap Injection System

1. Equip the TBM with a bentonite shield gap injection system when operating in the pressurized mode capable of continuous injection under pressure through the shield to fill the shield gap created by the perimeter cutters overcutting the shield. The bentonite shall be capable of supporting the surrounding ground to counteract soil relaxation during shield penetration. Bentonite shall be continuously injected under pressure with the advance of the TBM.

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2. Equip the TBM with a lock out system to prohibit TBM advance unless Shield Gap Injection System is fully operational.

3. Provide an injected fluid consisting of a volume-stable, bentonite water mixture. Adjust mix consistency for compatibility with ground conditions, machine progress rates and planned or unplanned work stoppages. Continuously pump fluid mix as the TBM advances at sufficient pressure and volume to ensure:

a. Complete and total filling of the shield gap annular void.

b. Support of the surrounding ground; provide method of automatically controlling and measuring fluid volumes and pressures.

c. Provide for adequate supply of mix to fill all surrounding voids.

J.K. Segment Erector

1. Design the segment erector to be compatible with the machine and liner system to ensure safe and efficient segment installation.

2. Design the erector to be actuated in the axial, radial, and circumferential directions and in the three articulation angles corresponding to the six degrees of freedom. Design the erector to grip and erect the segments so that they are positioned accurately, so that segments are aligned within the required tolerances, gaskets are compressed, and no damage or distortion of the segments or gaskets occurs.

3. Provide special construction bars, framework, or other supports, as required during erection of segments.

4. Design the TBM segment erector so as to be able to retrieve segments for replacement if damage is incurred within the first 12 inches of shove.

K.L. Machine - Liner Interface

1. Maximum thrust pressure at any point and any time on the liner system shall not exceed 50% of segment 28 day compressive strength (or less if required by the segment manufacturer) unless otherwise submitted to and approved by the segment manufacturer and Metro.

2. Thrust pads shall not damage gaskets or segments.

3. Equip TBM to allow continuous, complete backfill grouting of the annulus between the concrete segments and excavated surface (tail void).

4. Design TBM to grout the tail void through the tail shield using pipes or channels designed by the TBM manufacturer and embedded within the tail shield. Uniformly space grout pipes embedded in the tail shield; add a redundant pipe at each location for use in the event that the first pipe becomes blocked. Provide means of clearing blocked pipes of grout. Grouting through grout holes in segments will not be accepted as the primary method of backfill grouting.

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5. Coordinate the shield tail seal and the liner system design, fabrication, and operation to ensure a competent seal.

6. Use inert tail seal grease, compatible with the liner system gaskets and materials, and that does not contaminate the surrounding ground or groundwater and does not cause long term deterioration of liner concrete, joint connector, gaskets, seals or joint packers.

L.M. Guidance System, Alignment Control, and TBM Performance Monitoring

1. Equip and operate TBM with a computerized guidance system capable of accurately steering, tracking and continuously recording tunnel machine location and permitting continuous control and setting of alignment and grade.

2. Design the guidance system to provide continuous location and position data in real time including comparison between design tunnel centerline and driven tunnel centerline. Display the real time comparison graphically to the machine operator at all times on an electronic display terminal. Data presented to include, for every segment ring interval along tunnel centerline, design centerline stationing values, as-driven coordinates and elevation values, horizontal and vertical offsets from design tunnel centerline to the driven tunnel centerline, horizontal and vertical attitude of TBM compared to theoretical and forecasted position of the TBM at a 15 ft distance in front of the face.

3. Capable of recording and storing data electronically for real time data access through internet or intranet available to Metro and later use. Capable of processing and generating, automatically by computer, separate plots of all parameters.

4. Design the guidance system to interface with individual controls for thrust jack pressures and extensions, cutterhead and shield articulation.

5. Data to be collected for each shove or stroke of the TBM includes the following:

a. Date, time and tunnel station at start of shove.

b. Drive motor current or hydraulic pressure continuously recorded for cutterhead.

c. Total thrust force of propel jacks.

d. Rotational speed, torque, and direction of the cutterhead.

e. Rotational speed and torque of screw conveyor for EPB TBM.

f. Pressure for each pressure cell in excavation chamber and screw conveyor continuously recorded.

g. Information from guidance system.

h. Mode of operation; tail grout volumes and pressures; tail seal grease volume.

i. Record type of soil being excavated; presence of boulders or other obstructions; volume of soil excavated.

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M.N. Other Features

1. Provide TBM with the capability to drill probe/grout holes through, and to grout ahead of the face in at least two positions and through the machine skin in at least six positions located equidistant around the circumference of the machine from locations ahead of the tailshield. Equip TBM with probe hole drilling capability such that at least one probe hole can be maintained a minimum of 50 feet ahead of each TBM cutterhead at all times at all locations. Design the probing and grouting ports so as to be fitted with suitable glands and valves to withstand the pressures envisaged.

2. Provide method to test for the presence of hazardous or explosive gas in accordance with CAL/OSHA requirements.

3. Provide TBM with all necessary equipment to comply with applicable provisions of the Tunnel Safety Orders of the State of California.

N.O. Rebuilt TBMs

1. All components and systems function equal to those of a new machine, except as indicated herein to be new.

2. The following components shall be new:

a. Cutters, picks, drag teeth, and cutting wheel

b. All seals listed in paragraph entitled “Seals.”

c. All hydraulic system seals, hoses, and control modules.

d. Electrical wiring, lockouts, and switches.

e. Main bearing(s)

3. Design and manufacture the jacking and propulsion system, the segment handling and erector system, and the segments to be fully compatible with each other.

4. Rebuilt machines shall have been used successfully for all completed tunnels by the machine in terms of ground control.

PART 3 - EXECUTION

3.1 PREPARATION

A. Settlement Indicators or Reference Points - Before starting tunneling operations, ensure subsurface settlement indicators (MPBX), settlement reference points, liquid tube monitoring systems or approved alternative monitoring systems, and building settlement reference points are installed and are functional in accordance with Section 31 09 13, Geotechnical Instrumentation and Section 31 79 00, Compensation Grouting.

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B. Prepare action plans and conduct a workshop to inform and train project staff to ensure understanding of plans that delineate the actions to be taken when settlement indicators show that action levels or maximum levels are reached. Include key management and supervisory staff from the Contractor, specialty subcontractor(s), and Metro.

3.2 CONSTRUCTION

A. Tunneling

1. Perform tunnel construction for anticipated ground conditions to minimize ground movement and control water and water inflow and attendant soil transport, and to meet requirements herein for Allowable Settlement. Immediately notify the Metro representative on shift if deviations from the approved work plan occur. Follow up with written notification within 24 hours of occurrence and indicate what corrective measures were taken.

2. Distance Between Headings – If two TBMs are used, keep longitudinal distance between two adjacent tunnel faces being excavated concurrently at a minimum distance of 150 feet.

3. Tunnel using a minimum face pressure between 10 psi and at-rest earth pressure. Add any hydrostatic pressure as determined at the tunnel invert. Add any pressure necessary to meet requirements herein for face control or for Allowable Settlement.

4. Continuously backfill grout the tail void through the tail shield as the machine advances.

a. Adjust grout set-up times for compatibility with machine progress rates and planned or unplanned work stoppages.

b. As the segment ring is pushed from the shield, continuously pump grout at sufficient pressure and in sufficient volume to ensure complete and total filling of the annular void and support the surrounding ground.

5. As the TBM advances, continuously inject tail seal grease under pressure to minimize risk of groundwater or grout intrusion.

6. Maintain face supported during shutdowns.

7. Monitor gas concentrations and pressure in plenum chamber at all times. Vent or replace air/gas mixture presents in plenum chamber as necessary to ensure that gas concentration in plenum chamber is below explosive/hazardous level. Ensure air/gas mixture has been vented or replaced by bentonite injection before tunneling resumes at the end of any shutdown period.

8. Ensure cutterhead and mixing chamber/plenum is filled prior to restart of mining after any shutdown period or intervension.

9. Stop mining and secure the tunnel when the conditioning system, plenum bentonite injection system, shield gap injection system, grouting system or guidance system is not operating. Resume mining when these systems are operating reliably.

10. Allowable Settlement or Heave - Maximum ground settlement/heave and/or angular distortion to not exceed the limits shown in the tables below:

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a. Allowable Settlement/Heave for buildings, facilities, utilities, and other structures:

Action Level Maximum Level

Angular Distortion* 1/1000 1/750 Total Settlement/Heave (in.) 0.35 0.5

*Average settlement slope or slope between building walls or columns which ever less.

b. Allowable Settlement/Heave above each tunnel measured by MPBX

Location Action Level (in.) Maximum Level (in.)

3 ft. above tunnel 0.5 0.75

11. Action Levels for Allowable Settlement/Heave are levels at which tunneling is allowed yet corrective measures are required, including procedural modifications that permit tunneling to continue without exceeding the specified Maximum Level. Corrective measures include:

a. Adjusting face pressure, soil conditioning, overcut gap injection and pressure, annular grout quantities, grout mix, grout pressures, progress rates or other factors as identified in the submitted Action Plan for Tunneling and Control of Settlement.

b. Utilizing or modifying grouting and ground treatment methods to achieve control of settlement, to protect buildings and utilities, and to avoid liner deformations.

c. Meet with Metro to discuss overall tunneling operation and the effectiveness of adjustments made to the construction procedures, overall tunneling operation; and any ground improvement measures such as grouting either as required herein or undertaken at the initiative of the Contractor.

12. Maximum Levels for Allowable Settlement/Heave are levels at which no further settlement/heave will be acceptable. Settlements/heaves exceeding the Maximum Level specified herein require the immediate implementation of the following:

a. No further tunneling is allowed unless otherwise directed and corrective measures taken.

b. Inspection of affected facilities and structures and performance of acceptable corrective and restorative measures

c. Submit modified plan for additional corrective measures to assure no further settlement occurs

d. If geotechnical instrumentation indicates that ground movement is continuing and damage to structures or utilities is increasing or the risk of damage as determined by Metro is increasing, assure face stability to stop the ground movement and stop the damage to structures and utilities, and take measures to reduce risk of damage determined by Metro.

e. Where lost ground and incomplete grouting result in voids around the tunnel excavation,

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perform approved measures to fill voids.

f. Resume tunnel excavation only upon preventing further settlement/heave.

13. Perform check grouting in accordance with Section 31 73 00, Tunnel Grouting.

14. Whenever there is an emergency or stoppage of work, which is likely to endanger the excavation or adjacent structures, or where 24-hour-a-day working is required, maintain sufficient forces for 24 hours a day, including weekends and holidays, to perform any work required until emergency or hazardous conditions are resolved and eliminated, or the 24-hour-a-day section is completed.

15. Do not advance TBM at any time without filling and pressurizing excavation chamber. Maintain excavation chamber filled and pressurized when not advancing. During intervention when excavation chamber must be filled with air, ventilate and monitor chamber for gases at all time.

B. Tunneling Requirements for Specific Conditions

1. Japanese Village Plaza (JVP) Parking Structure and Other Structures

a. Perform pre- and post-construction survey and settlement analysis.

b. Install and monitor geotechnical instrumentations complying with Section 31 09 13, Geotechnical Instrumentation and Monitoring.

c. Demonstrate fully functioning TBM and backup equipment before starting tunneling under RC-451A. Conduct tunneling in association with geotechnical instrumentation and monitoring to meet settlement performance requirements specified in this Section and to protect utilities in the street during demonstration.

d. Evaluate settlements and performance of TBM in terms of lost ground and settlement control by pressure-face tunneling over at least 60 feet or entire of tunneling prior to tunneling under RC-451A. If evaluations indicate potential for damage, identify and conduct measures to be taken to ensure no damage when tunneling under private property.

e. Install compensation grout pipes for RC-451 and RC-451A in advance of tunneling under the properties as indicated in the drawings. Conduct compensation grouting as required complying with Section 31 79 00, Compensation Grouting.

f. Conduct permeation grouting for RC-449 and RC-450 in advance of tunneling under the properties as indicated in drawings and specified in Section 31 82 00, Permeation Grouting.

2. 2nd Street Storm Drain

a. Perform pre- and post-construction survey and settlement analysis.

b. Conduct permeation grouting around the storm drain in advance of tunneling under the structure as indicated in drawings and specified in Section 31 82 00, Permeation

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Grouting.

c. Install and monitor geotechnical instrumentations per Section 31 09 13, Geotechnical Instrumentation and Monitoring.

d. Evaluate settlements over previous 400 feet of tunneling or entire. If evaluations indicate potential for damage, identify and conduct measures to be taken to ensure no damage when tunneling under the structure.

3. Red Line Tunnels

a. Perform pre- and post-construction survey and settlement analysis.

b. Install and monitor multi-points borehole extensometers on each side of Red Line tunnels as indicated in Project Definition Drawings and complying with Section 31 09 13, Geotechnical Instrumentation and Monitoring. Provide real time instrumentation and monitoring on/in Red Line tunnels without the interruption of train operation while tunnel faces are within 200 feet from the existing tunnels.

c. Evaluate settlements over previous 400 feet of tunneling. If evaluations indicate potential for damage, identify and conduct measures to be taken to ensure no damage when tunneling under the existing tunnels.

d. Drill probe holes from headings in advance of tunneling under Red Line tunnels to investigate the ground condition between Red Line and proposed tunnels. Conduct permeation grouting through probe holes complying with Section 31 82 00, Permeation Grouting, if found to be required to fill voids.

e. Conduct check grouting after tunneling under Red Line tunnels complying with Section 31 73 00, Tunnel Grouting.

4. Colburn School, 2nd Street Tunnel, Walt Disney Concert Hall, and Broad Museum

a. Perform pre- and post-construction survey, settlement analysis, vibration and noise study.

b. Install and monitor geotechnical instrumentation complying with Section 31 09 13, Geotechnical Instrumentation and Monitoring.

c. Install and monitor noise and vibration complying with Section 01 56 19, Construction Noise and Vibration Control.

d. Evaluate settlements, noise and vibration over previous 400 feet of tunneling. If evaluations indicate potential for damage or exceeding noise and vibration limits, identify and conduct measures to be taken to ensure no damage when tunneling under the referenced structures and to reduce construction noise and vibration.

5. 3rd/Flower Street Chilled Water Pipes and Utilities

a. Perform pre- and post-construction survey and settlement analysis.

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b. Evaluate settlements over previous 400 feet of tunneling or entire. If evaluations indicate potential for damage, identify and conduct measures to be taken to ensure no damage when tunneling under the structure.

c. Install compensation grout pipes for the pipes and utilities in advance of tunneling under the referenced structures as indicated in the drawings. Conduct compensation grouting as required complying with Section 31 79 00, Compensation Grouting.

d. Install and monitor geotechnical instrumentations complying with Section 31 09 13, Geotechnical Instrumentation and Monitoring.

6. 4th Street Bridge

a. Perform pre- and post-construction survey and settlement analysis.

b. Evaluate settlements over previous 400 feet of tunneling. If evaluations indicate potential for damage, identify and conduct measures to be taken to ensure no damage when tunneling under the structure.

c. Employ non-destructive investigation technique to locate piles of the bridge foundation.

d. Install and monitor geotechnical instrumentations complying with Section 31 09 13, Geotechnical Instrumentation and Monitoring.

C. Precast Concrete Segmental Tunnel Liner System - Refer to Section 31 74 16, Precast Concrete Segmental Tunnel Liners.

D. Repair and Restoration of adjacent facilities:

1. Repair settlement related property damage resulting from tunneling. Have on call for immediate response trades to repair damaged utilities, streets, sidewalks, and building elements.

2. Respond to requests for work from other agencies as directed by Metro. Such requests are anticipated to include street and sidewalk restoration, and traffic control.

3.3 CONSTRUCTION TOLERANCES

A. Allowable departure of the tunnel from the indicated line or grade: 8-inch diameter bulls-eye.

B. Departure from or return to established alignment: no greater than 3-inch per 100 feet.

C. Also refer to Section 31 74 16, Precast Concrete Tunnel Lining.

3.4 MONITORING AND CONTROL FOR SEGMENTAL LINING

A. Monitor the dimensions and deformations of the tunnel liner rings as specified herein, and in Section 31 09 13, Geotechnical Instrumentation and Monitoring and as required in Section 31 79 00, Compensation Grouting.

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B. If the convergence measurements indicate excessive movements are occurring, take corrective measures in accordance with submitted procedures. Consider ring deflection excessive if the horizontal diameter, measured between inside surfaces of the segments, changes more than one half inch from the diameter measured at the time of complete emergence from the TBM tail shield and completion of ring grouting. When compensation grouting is performed, coordinate with compensation grouting crews for taking readings and responses.

C. If excessive deformations are occurring, take additional readings on affected sections of the liners. Take readings daily, or more often if required, and take readings after each shove of the shield if the tail shield is within one diameter of the section exhibiting excessive deformation.

D. Replace segments seemobserved to suffer be damaged during the first 12 inches of shove.

3.5 WATER AND GAS INFLOW IN FINISHED TUNNEL

A. Water:

1. No water drip into tunnel allowed.

2. Maximum overall inflow - 0.1 gallons per minute per 1000 linear feet of tunnel.

3. Local inflow limit - 0.1 gallons per day per 10 square feet of tunnel lining area.

4. If, after the segmental lining has been installed, water inflow into tunnel exceeds specified limits above during construction and a period of one year after completion of Work, undertake remedial measures in accordance with Section 31 01 70, Sealing Leaks.

B. Gas:

1. Monitor the segmental liners for gas leakage as the tunnel progresses and upon completion of tunneling. Take measurements a minimum distance of one foot from tunnel lining, at top, bottom and springline positions around the circumference

2. Maximum gas concentration - 2.5 percent of the LEL methane or 2.5 ppm of hydrogen sulfide at a minimum air velocity of 60 feet/min in the tunnel.

3. If leaks are producing an environment with gas concentrations exceeding specified limits above during construction and a period of one year after completion of Work, remediate gas inflow in accordance with Section 31 01 70, Sealing Leaks.

3.6 DISPOSAL OF EXCAVATED MATERIAL

A. Remove all material excavated from the TBM driven tunnel through the Mangrove worksite launch pit. Do not remove material excavated for the tunnels through the 1st/Central Station.

B. As described in the GBR, when water is used as a component of the conditioner, the spoil will have high water content. Take measures to handle and dispose of the mixture of muck and water including: stockpiling muck at the mining sites to drain, addition of dry material, transporting from site using sealed trucks, washing down trucks before they leave the work site, and using intermediate, offsite stockpiling sites to drain or dry the muck to acceptable water

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contents before disposal. Make provisions for the handling and disposal of the drainage water from the muck.

3.7 TUNNEL CONNECTION AND TERMINATION

A. Leave in place survey points at the beginning and end of each tunnel and each tunnel/station interface.

B. If water or gas inflow does not meet the criteria specified for finished tunnel at crosspassage/tunnel or station/tunnel connection, remediate water or gas inflow in accordance with Section 31 01 70, Sealing Leaks

END OF SECTION

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APPENDIX A

PERSONNEL ASSIGNED TO PROJECT

Name: _______________________________________________ Project Position__________________________________ Years of Experience: Soft Ground Tunneling (Pressure face TBM) _____________________ Other (specify) ______________________________________________ Project Description and Nature of Work for Which Person was Responsible: ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ Description of Required Training completed as applicable: ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ (Use additional sheets as necessary to describe experience)

Name of Client for verification of above (Owner/Agency, Contractor, etc.): ____________________________________________________________________ Address: ____________________________________________________________ ____________________________________________________________ ____________________________________________________________ Contact Name: _____________________________ Telephone _______________ Owner’s Project or Contract No. ________________ Fax No. _______________ Commitment to Project (Duration proposed person to be assigned to the Project): ____________________

(TO BE FILLED OUT FOR EACH PROJECT PERSONNEL)

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