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Technical Sessions that Enlighten


The NAT Conference is proud to present technical sessions hosted by some of the leading innovators and technology from around the world.

Monday, June 8, 2020 | 9:30 AM

Technology Track - Ground Support

Room 1

Chair: Jeramy Decker, Kiewit, Papillion, NE

Co-Chair: Jay Arabshahi, Metro Water District of Southern California, Los Angeles, CA

10:15 AM

10:20 AM
Union Square Market Street Station

David Abrahams1 , Kenneth Johnson2 , Jane Wang3

1WSP, NEW YORK, New York , 2WSP, San Francisco, California , 3SFMTA, San Francisco, California

The Union Square Market Street Station was constructed using top-down, cut and cover excavation methods utilizing 150 foot battered drilled shafts as permanent ground support, rendering it one of the most unique subway station configurations in the world.. San Francisco’s Central Subway Project is a 1.7-mile-long subway extension with three underground stations. Its temporary and permanent ground support, compensation grouting activities, excavation dewatering, and existing conditions will be presented. Entrances at the historic Union Square and a second entrance that integrates with an existing BART station will also be described.

10:40 AM
Innovative High Durability Non-Steel Fibers Reinforced Segments

Paz Navarro1 , Maria N. Sanchez2 , Elena Martín3 , Ignacio Segura4 , Janill de la Cruz5 , Albert De la Fuente6

1gGravity Engineering, Madrid, Madrid , 2gGravity Engineering- Material Division, Madrid, Madrid , 3DRAGADOS, Madrid, Madrid , 4Universidad Politécnica de Cataluña, Barcelona, Barcelona , 5Universidad Politécnica de Cataluña, Barcelona, Barcelona , 6Universidad Politécnica de Cataluña, Barcelona, Barcelona

SFRC precast segmental rings are the usual lining for TBM tunnels. DRAGADOS- gGRAVITY Engineering- UPC wanted to go one step forward and have studied the non- steel fiber reinforced concrete (NSFRC) segments behavior in a Research and Development project (DURADOV) during 5 years. Durability, sustainability, structural and fire behavior for different type of fibers (polyolefin, carbon, basalt, glass) have been analyzed obtaining very positive results. This work opens the door to this innovative solution for these structural elements and other further applications, especially with challenging durability requirements.

11:00 AM
Jacked Pre-cast Caisson Shaft Construction Methologies

John Elliott1 , Ben Ablett2

1Golder, Doncaster, South Yorkshire , 2Golder, Doncaster, South Yorkshire

New market adoption of jacked pre-cast caisson shaft construction methodologies. An overview of the jacked caisson methodology and its’ application to varying ground conditions; the ability to deliver water-tight, rationalized structures through soft rock, non-cohesive and cohesive ground. Paired with under-pinned, under-reamed and corbeled segments, sprayed concrete linings and concreting under-water, this is a safe, versatile, quick construction methodology that can be designed for near surface infrastructure up to 70m deep. Pre-cast caisson methodology can also minimize the need for wet process applications on site and assist in reducing site waste streams due to its’ predominantly pre-cast system components.

Design Track - Overcoming Design Challenges

Room 2

Chair: Saeed Tabrizi, Frontier-Kemper Constructors LLC, Sylmar, CA

Co-Chair: Shawna, Mott MacDonald, Von Stockhausen, Pleasanton, CA

10:15 AM

10:20 AM
Design Case History of the Surface Water Supply Project, Segment C, in Houston, Texas

Nancy Nuttbrock1 , Alan Hutson2 , Melinda Silva3

1Brierley Associates Corporation, Houston, Texas , 2Freese and Nichols, Inc., Houston, Texas , 3Dannenbaum Engineering Corporation, Houston, Texas

Surface water will be supplied from Lake Houston through the City of Houston’s Northeast Water Purification Plant, approximately 39 miles of pipeline, and two pump stations. The project is separated into three segments, A, B and C, for design purposes. Segment C consists of approximately 17.5 miles of 84-inch and 66-inch diameter water line with sixteen trenchless crossings consisting of nineteen individual tunnels within the Lissie Formation. A case history will explain the subsurface conditions, design approach, site challenges, anticipated shaft and tunnel construction methods, and the need for compatibility between the specifications, drawings and Geotechnical Baseline Report.

10:40 AM
The Three Rivers Protection & Overflow Reduction Tunnel (3RPORT) – Design Challenges of the Launching of Pressurized Slurry TBM

Roberto Schuerch1 , Roberto Schuerch2 , Giuseppe Moranda3 , Ludovica Pizzarotti4 , Emidio Tamburri5

1Pini Swiss Engineers, Zurich, ZH , 2Pini Swiss Engineers, Zurich, Zurich , 3Pini Swiss Engineers, Zurich, ZH , 4Salini Impregilo Lane, Fort Wayne, Indiana , 5Salini Impregilo Lane, Fort Wayne, Indiana

Depending on the hydro-geological conditions and the overall project constraints, a tunnel boring machine (TBM) may be launched under high support pressure. The “pressurized” launching of a TBM represents a major design challenge particularly when the TBM is launched from a starter tunnel. The present paper focuses on the launching of the slurry TBM, named “MamaJo”, of the 3RPORT tunnel. The tunnel is part of the Long-Term Control Plan of the City of Fort Wayne (Indiana, USA) having the main goal to reduce the discharge of untreated Combined Sewer Overflows (CSOs and improve water quality in Fort Wayne’s CSO-impacted streams. The tunnel will have a length of about 7.5 km, an internal diameter of 4.87 m and will be excavated at a maximum depth of 60 m. Carbonate rocks are expected over the entire alignment. Due to the high rockmass permeability and high in-situ hydrostatic pressure at the tunnel elevation, the launching of the TBM has been designed taking into account a support pressure up to 6 bar. The paper presents the main geotechnical hazards for all launching stages as well as their impact on the design solutions. Finally, it summarizes the lesson-learned after the successful launch of the slurry TBM on April 2019. Particular attention is paid on the design of the launching chamber (incl. concrete plug) as well on the selection of the required TBM parameters.

11:00 AM
Nose Hill Water Supply Tunnel Design

Dan Ifrim1 , Shawn Pillai2 , Anwar Majid3 , David Lagore4

1Hatch, Mississauga, Ontario , 2AECOM, Calgary, Alberta , 3AECOM, Calgary, Alberta , 4City of Calgary, Calgary, Alberta

The City of Calgary is constructing the Nose Hill Water Supply Tunnel as part of the North Calgary Water Servicing Project. The new water supply line (feedermain) is required to service future developments and to ensure sustainability of the water supply system in the north Calgary. The City has engaged AECOM as the project consultant, to complete the design of the new water feedermain from Spy Hill West Reservoir to Beddington Reservoir. A portion of the preferred alignment traverses Nose Hill Park from the southwest to the northeast and will be constructed using tunneling technology. Remaining sections will be constructed, using open-cut methods, along with trenchless crossings of major roadways. The paper discusses the aspects and challenges of the tunnel design in variable ground conditions.

Planning Track - Tunnel Diversity

Room 3

Chair Rene Fippin, McMillen Jacobs Associates, San Francisco, CA

Co-Chair: Hamed Nejad, Michels, Secaucus, NJ

10:15 AM

10:20 AM
Recent Experience with Bond Market Investors on P3 Projects with Large Tunnels

David Mast1 , Thomas DiPonio2 , Mina Shinouda3 , Jason Edberg4 , Amanda Foote5 , Karun Malhotra6

1AECOM, Cleveland, Ohio , 2Jay Dee Contractors, Inc., Livonia, Michigan , 3Jay Dee Contractors, Inc., Livonia, Michigan , 4NTH Consultants, Ltd., Northville, Michigan , 5AECOM, Newburgh, Indiana , 6AECOM Capital, New York, New York

The Michigan Department of Transportation (MDOT) I-75 Modernization Project (Segment 3) in Detroit and Oakland County will be accomplished under a 30-year Private-Public Partnership (P3) with a contract value of over US$1 billion. Oakland Corridor Partners (OCP) was awarded the 30-year P3 Design-Build-Finance-Maintain project. In addition to highway road and bridge replacements, OCP will construct a nearly 4-mile long, 14.5-foot ID storage tunnel to eliminate pump stations and reduce road flooding. OCP assisted MDOT with securing financing, including bond ratings. The paper will share unique experience of winning and financing a P3 project with a large tunnel component.

10:40 AM
Aged Tunnel Rehabilitation Options: Using Geotechnical Techniques to Assess Site Conditions and Provide Modeling Inputs: A Case Study from Detroit

David Sackett1 , Russell Lutch2 , Jon (Ike) Isaacson3

1Brierley Associates Corp, Norfolk, Virginia , 2Brierley Associates Corporation, East Syracuse, New York , 3Brierley Associates Corporation, Milwaukee, Wisconsin

Main components of Detroit’s raw water tunnel infrastructure were constructed in the 1920s to 1950s. Approaching a century of continuous operation, underwater inspections revealed cracking of tunnel cast-in-place concrete liners and the potential risk of failure, requiring portions to be rehabilitated. The tunnels were installed within low-strength clays with dense “hardpan” at or near the invert. To assess the role of geologic conditions on the condition of the tunnels, a varied, multi-phased geotechnical program was performed. Techniques employed included sample borings, environmental screening, insitu testing, instrumentation and laboratory testing to explore possible relationships between the tunnel conditions and surrounding soils.

11:00 AM
Owner Flexibility and Contractor Experience Lead to Project Success

David Mast1 , Richard Depew2 , Alison Schreiber3 , Chris Lynagh4 , Tom Szaraz5 , Amanda Foote6

1AECOM, Cleveland, Ohio , 2Northeast Ohio Regional Sewer District, Cleveland, Ohio , 3Northeast Ohio Regional Sewer District, Cleveland, Ohio , 4McNally International Inc., Westlake, Ohio , 5McNally International, Inc., Westlake, Ohio , 6AECOM, Newburgh, Indiana

The Dugway South Relief and Consolidation Sewer was substantially completed in September 2018 for the Northeast Ohio Regional Sewer District. McNally Tunneling Corporation utilized a variety of tunneling and construction methods to accomplish this critical CSO control measure system. They utilized bid document flexibility to choose efficient construction methods, including use of a single TBM for soft ground and shale rock mining. McNally proposed several improvements based on the capabilities of their equipment and their own experience. This paper will discuss the challenges, solutions, and effectiveness of the design and construction methods utilized to complete the project.

Case Histories Track - Conventional Tunneling

Room 4

Chair: Paul Hetu, HNTB, San Jose, CA

Co-Chair: Steve Lotti, Frontier Kemper, New Hyde Park, NY

10:15 AM

10:20 AM
Anticipated vs Actual Behavior of Shallow SEM Tunnel Under a Residential Area – Construction Impacts and Contractor/Designer Solutions

Rafael Villarreal1 , David Watson2 , Philip Lloyd3 , Zhibo Chen4

1Mott MacDonald, Rahway, New Jersey , 2Mott MacDonald, New York, New York , 3Mott MacDonald, New York, New York , 4Mott MacDonald, New York, New York

The Plymouth Tunnel, part of Light Rail Transit Purple Line Project for the Maryland Transit Administration is a short but critical section of the Purple Line 1220-feet in length, with a shallow vertical alignment about half a tunnel diameter to a tunnel diameter beneath a residential area. For design and construction, a tunnel either in soil or rock would generally provide more predictable consistent conditions, however challenging mixed ground conditions were anticipated from below or within the tunnel horizon to surface. The ground ranged from soils, decomposed rock to fresh very strong schist. Even though extensive geotechnical investigations were conducted and a robust instrumentation and monitoring program was deployed, significant challenges were encountered during construction from the East C &C and Retained Cut to the top heading and bench during SEM tunneling. As well as discussing the anticipated versus actual conditions encountered and their impacts, this paper presents the Contractor and Designer approach, interaction and innovative solutions developed during construction overcome these challenges.

10:40 AM
SEM huge cavern stations beat cut an cover in Crosslinx Megaproject

Alejandro Sanz1 , Paz Navarro2 , Francisco Soto3 , Juan Azofra4

1gGravity Engineering, Madrid, Madrid , 2gGravity Engineering, Madrid, Madrid , 3Dragados Canada, Toronto, Ontario , 4Dragados Canada, Toronto, Ontario

The Eglinton Crosstown Light Rail Transit Project (5.4 BCAD$) in Toronto includes the construction of three SEM huge mined caverns and twelve cut and cover stations to be built in a tight 6-year schedule. This paper describes the innovative solutions implemented during the design and construction stages to overcome significant schedule and technical challenges expected in any urban Project. Temporary support details as shotcrete with no need of steel arches or girders, a combined lining design approach and optimized sequencing with innovative strategies to enable mining and final lining activities overlaps are some of the key aspects described.

11:00 AM
Performance-Based Classification of Fiber Reinforced Concrete for Tunnel Linings based on Model Code 2010

Axel Nitschke1

1WSP USA, Washington, District of Columbia

The utilization of fiber-reinforced concrete (FRC) either as shotcrete or as cast-in-place concrete in tunnel linings is constantly increasing. In parallel, the number of fiber types available on the market is growing. Generally, fibers with different materials, lengths, diameters, geometries, etc. are available and perform differently. Historically, fibers are specified by volume-percentage or weight-per-volume in the mix. However, it is also generally recognized that this is not the ideal approach and a performance-based approach is much more constructive, especially for tunnel linings. FIB Model Code 2010, a progressive and comprehensive pre-standard, that is widely used for FRC structural design internationally and in the US, provides a performance-based classification system. The major structural benefit of FRC in tunnel linings is in the improvement of the post-cracking behavior, specifically, an elasto-plastic or strain-hardening bearing behavior is desired. Next to the material properties, the post-cracking behavior is influenced by the combination of moment and thrust force in the lining.

Monday, June 8, 2020 | 1:30 PM

Technology Track - TBM Technology

Room 1

Chair: James Mueller, NYC DEP

Co-Chair: Jennifer Sketchley, McMillen Jacobs Associates, San Francisco, CA

1:30 PM

1:35 PM
EPBM Pro-Active Tracking and Progressive Optimization

Elisa Comis1 , Daniele Nebbia2 , Colin Lavassar3

1McMillen Jacobs, Mayfield heights, Ohio , 2Lane - Salini/Impregilo, Washington, District of Columbia , 3McMillen Jacobs Associates, Washington, District of Columbia

Current Earth Pressure Balance TBMs (EPBM) are equipped with a multitude of sensors that continuously record operational data. These data feeds can produce an almost overwhelming amount of information, especially when combined with results of geotechnical instrumentation programs that monitor soil and groundwater response to tunneling. Owners, designers and contractors benefit from pro-active analyses and visualization of these data sets though as this enables operational changes to be made in a timely manner to optimize TBM performance. Furthermore, a progressive response is often necessary to efficiently overcome problems that result from a combination of root causes, especially during TBM launch and the infamous “Learning Curve”. This paper focuses on the lessons learned regarding TBM data analysis and visualization during construction of the Anacostia River Tunnel and how these have been applied to the North East Boundary Tunnel, in Washington DC.

1:55 PM
Project Clear: Efficient Hard Rock Tunneling using Refurbished TBMs below St. Louis, Missouri

Desiree Willis1

1The Robbins Company, Solon, Ohio

The Metropolitan St. Louis Water District’s Project Clear is a 28-year program targeting water quality and wastewater capacity throughout St. Louis, MO. The program involves multiple tunnels, including Deer Creek, a 6.3 km long tunnel bored with the largest TBM ever used in the St. Louis area (6.5 m in diameter). Another tunnel, Jefferson Barracks, uses TBM components that have bored over 40 km of tunnel since 1981. This paper will analyze the performance of the TBMs in limestone and shale, and draw conclusions as to the ability of refurbished TBMs to bore on multiple projects over many years.

2:15 PM
Small Diameter Tunneling: Limitations and Machine Concepts

Peter Schmaeh1, Marcus Lübbers1

1Herrenknecht AG, Schwanau-Allmannsweier, Baden-Wurttemberg

Small diameter tunnels are considered for a large variety of applications from water and gravity tunnels for sewage to tunnels for cable and telecommunication lines. Furthermore, challenging crossings of water and traffic ways represent an increasing niche market for small TBMs, including pipeline installations. Especially in the pipeline industry, the tunnel diameter is not defined by the application itself but by the applicable tunnelling method. This creates a demand for small tunnels, even on long distances and difficult ground conditions. Safety aspects in mechanized tunnelling are becoming increasingly important. Latest safety regulations have tightened requirements regarding machine diameter and accessibility with considerable impact on personal access and logistics. As a result, larger diameters will come more into focus or unmanned procedures like pipe jacking will take over a share of the smaller diameters of up to four meters. At the same time, TBM technology is continuously advancing. Nowadays, TBMs can be designed for more flexible use, for example as combined technologies for changing ground conditions or with further features to increase versatility and project safety. This paper discusses the limitations given by small diameters and confined space and will summarize the state-of-the-art technology for small diameter segment lining and large diameter pipe jacking MTBMs. It will point out the main factors to choose the best-suited tunnelling technology and machine concept for a specific project according to the geological and hydrological conditions. Furthermore, it will give an outlook about possibilities for unmanned operations to avoid or minimize involved personnel.

2:35 PM
Using Predictive Modeling for TBM Process Control

Jacob Grasmick1 , Angus Maxwell1

1Maxwell Geosystems, Golden, Colorado

Tunneling process control is the feedback between the observed behavior of the TBM with predictions and observations. In this paper, examples of using predictive models to improve the feedback analysis and allow the engineer to readily undertake forecasts related to productivity and ground behavior are presented. These predictive models, which can be developed for TBM parameters (e.g., face pressure) and ground behavior (e.g., volume loss), are updated/improved as the TBM progresses through the ground and the relationship between geotechnical conditions and TBM performance becomes better understood. This feedback ensures tunneling is achieved safely and effectively, while maximizing productivity and minimizing risks.

2:55 PM
TBM Hardening and Anti-wear Mechanisms against Ground Abrasion

Donald Del Nero1

1Hatch, Clarkesville, Georgia

Soil and rock abrasion can have substantial impacts on TBM productivity and downtime events. The impacts of abrasion must be considered holistically for all TBM types and their individual components; from cutters to the muck scoops, from the plenum to the screw, and from the slurry pumps to the slurry plant. Productivity and downtime events from abrasion often point to metallurgical deficiencies. The paper will therefore highlight metallurgical aspects of abrasion resistance, common TBM wear patterns, customized anti-wear hardening mechanisms, custom steel alloys on the market and on what projects they have been implemented.

Design Track - Tunnel & Shaft Linings

Room 2

Chair: Paul Headland, Aldea Services LLC, Frederick, MD

Co-chair: Ritika Kundu, COWI North America, Florham Park, NJ

1:30 PM

1:35 PM
Design, Manufacturing, Construction and Durability of Precast Tunnel Segments According to New ACI 533.2R Guide

Mehdi Bakhshi1 , Verya Nasri2

1AECOM, New York, New York , 2AECOM, New York, New York

After success of ACI 544.7R as the first guide in the world on the fiber-reinforced concrete segments, American Concrete Institute (ACI) is aiming to publish its first comprehensive guide (ACI 533.2R) on general aspects of tunnel segments beyond the structural design. This paper presents main features of the guide including the most recent developments on all aspects of design, manufacturing, construction and the durability. In addition to the knowledge and common practice in the North America, ACI 533.2R brings together the knowledge and the experience gained on projects in Asia and Europe, and available national and international reports and recommendations. Beyond limit state design (ULS or SLS) during production, transportation, construction and final service stages, details of segmental ring geometry and systems, concrete strength, curing, and reinforcement detailing are discussed. Gaskets, connection devices, tolerances, dimensional control, and repair of defects are described. Durability and degradation mechanisms of tunnel linings and their mitigation methods are presented.

1:55 PM
Cross-Passage Openings in TBM Tunnels with Shear Keys

Cetin Sahin1 , Nicola Della Valle2 , Mert Gunduz3

1TunnelConsult, Sant Cugat del Vallés, Barcelona , 2TunnelConsult, Sant Cugat del Vallés, Barcelona , 3TunnelConsult, Umraniye, Istanbul

Twin tube transportation tunnels require the construction of connecting passages in order to link both tubes in case of an emergency. The construction of cross-passages involves partially demolishing of minimum two rings in each tube. Thus, in order to maintain the stability of the segmental lining ring and safely transfer acting loads from the opened ring to the adjacent ones, reinforced concrete shear keys are installed as temporary shear elements. As described in sample projects, shear keys are a proven smart and innovative solution to provide the required stability by avoiding the installation of steel support frames inside the tunnels.

2:15 PM
Analysis of Large Side Openings in Deep Shafts Under Different Ground Improvement Conditions

Sobhan Bhattacharya1 , Mohamed Gamal1

1Brierley Associates, DENVER, Colorado

The study investigates the complicated state of stress around the breakout-opening of an underground shaft by performing 3D finite element analysis and its impact on shaft design and reinforcement required around such openings. It discusses the impact of implementing different ground-improvement techniques (soil-freeze, jet-grout) and corresponding interface conditions. The results show that the difference between linear and non-linear interfaces is insignificant; and on many occasions the thrust-moment combinations are more critical for the no-interface case. It is observed that the use of complex non-linear interfaces has minor effects (10%-15% variation compared to no-interface model) on the state of stresses/forces.

2:35 PM
Montreal Express Link (REM) Airport Tunnel - Design of Segmental Tunnel Lining

Mehdi Bakhshi1 , Verya Nasri2

1AECOM, New York, New York , 2AECOM, New York, New York

A new 3.6 km long bored tunnel will be built below Montréal international airport airstrips as part of the Réseau Express Métropolitain (REM) which soon will be the fourth largest electric and fully-automated light-rail transit network in the world. This 7m-diameter tunnel will be excavated by a hybrid TBM that progresses through saturated soft ground and competent rock and will be supported by fiber-reinforced concrete (FRC) segmental lining. Segmental ring geometry and system are presented including a new dowel system in North America for the circumferential joints and an innovative tunnel sealing gaskets. This paper, in addition, discusses design procedures and results of analyses on governing load cases of segments from the time of demolding all the way through the final service stage. Advanced analysis results are presented including results of three-dimensional (3D) nonlinear finite element analyses on TBM thrust jack forces and 3D TBM excavation simulation with staged construction. Structural demands are compared with the nominal capacity of FRC segments which for the first time is derived as a result of an extensive statistical analysis program on 100s of standard beam tests performed in the segment precast plant.

2:55 PM
Behavior of Large Diameter Segmental Lining

Ashley Wilson1, Mike Mooney1

1Colorado School of Mines, Golden, Colorado

Large diameter segmental lining systems are increasingly being planned for in highway and transit tunnels in North America (e.g., Seattle, LA, Virginia, Toronto, San Jose). Many behavioral and design assumptions from the more common 20-25 ft transit tunnels are applied to large diameter tunnels, however, with little supporting evidence. This paper addresses, through analysis and extensive review of full scale tests conducted globally, a number of critical aspects that are quite different for large diameter lining, including segment joint rotational stiffness, slenderness ratio, and whole ring behavior with 10-12 joints compared to the 5-6 of most liners to date.

Planning Track - Contracting Strategies

Room 3

Chair: Dan Peterson, Schiavone

Co-chair: Aswathy Sivaram, Black & Veatch

1:30 PM

1:35 PM
Design-Build Procurement of the Hampton Roads Bridge-Tunnel Expansion

James Utterback1

1Virginia Department of Transportation, Hampton, Virginia

The $3.86 billion Hampton Roads Bridge-Tunnel Expansion project in southeastern Virginia developed rapidly from concept selection in December 2016 to contract award in April 2019. During this time, the Virginia Department of Transportation evaluated whether to structure the procurement as a privately-financed P3 or publicly-financed design-build; engaged regional stakeholders and the tunneling community to choose between immersed-tube and bored-tunnel construction alternatives; identified and retired cost-driving risks during procurement; and continuously refined the project scope, which ultimately entailed a 1.5 mile (2.4 km) four-lane tunnel crossing, 2.5 miles (4 km) of marine bridges, and 5 miles (8 km) of highway widening.

1:55 PM
CM/GC Delivery Method for Federally-Procured Projects: A Case Study on the Independent Cost Estimating Process

Douglas Pelletier1 , Jeff Wallace2 , Andy Thompson3

1Fermi National Accelerator Laboratory, Batavia, Illinois , 2Mott MacDonald, Chicago, Illinois , 3Mott MacDonald, New York, New York

The Construction Manager/General Contractor (CM/GC) delivery method is intended to benefit the design process, value engineering, risk mitigation, and schedule optimization while promoting construction and design innovation. This delivery method is particularly suited for complex projects that require significant consideration of contractor means and methods. Fermilab’s Far Site Conventional Facilities proceeded with a CM/GC delivery method to account for the unique conditions of excavating over 300,000 CY of rock in tunnels and caverns that will be constructed approximately 5000’ deep in the repurposed Homestake Mine in Lead, SD. The experiences of the CM/GC are presented.

2:15 PM
Getting Metro Owners the Best Value from Their Major Underground Projects

Ron Drake1 , Bill Hansmire2

1COWI North America, Arroyo Grande, California , 2WSP, Los Angeles, California

This paper discusses the merits of a design-bid-build alternative to design-build for Metro owners to achieve best value from their urban transit projects. The paper demonstrates how conventional design-bid-build can better address the risks for changed conditions, utility relocations, environmental mitigation, permitting, and coordination with governmental agencies and third parties that is difficult to delegate to design-build contractors. The paper provides suggestions and recommendations for consideration by owners to select a delivery method to effectively manage risk sharing, financial motives, design innovation, quality control, and cost and schedule control to achieve best value from their urban transit projects.

2:35 PM
Tunnel Cost Estimating – Sharing our Experience

Dan Ifrim1 , Andre Solecki1, Gary Kramer1 , Nina Dinescu1, Majid Eslami1

1Hatch, Mississauga, Ontario

Tunneling is a high risk and challenging industry. Construction methodology decisions are based on cost and social impact. A happy medium decision requires accurate cost estimating in order to determine the Capital Cost for the project. This paper discusses use of construction cost estimating tools and their applicability and accuracy for tunneling works estimating along with specific estimating tolls strictly used for tunneling cost estimates. Further the paper details the importance of estimator experience and ability to differentiate between costing different tunneling methodologies and our unique tunnel estimating approach together with past projects analysis and estimating accuracy. The objective of the paper is to draw attention over the importance of estimating tool customization, the importance of obtaining third parties cost estimates and understanding local market conditions, in order to achieve a close level of accuracy.

2:55 PM
Progressive Design Build in Silicon Valley

Nik Sokol1 , Mike Jaeger2 , Jack Sucilsky3

1Arup, Oakland, California , 2Tanner Pacific, San Carlos, California ,3Barnard Construction, Redwood City, California

The Silicon Valley Clean Water Gravity Pipeline (SVCW) is among the first tunnel projects to be procured using Progressive Design Build (PDB). Selected to provide cost certainty after the 60% design level and to allow greater coordination of the design with operations and maintenance, PBD also facilitates collaborative working between owner, contractor and designer. The flexibility of PDB procurement has allowed early milestones to be achieved during Stage 1, prior the Stage 2 contract, including ordering the TBM and 100% design of the precast concrete segmental lining and TBM launch shaft. Successes and challenges of the PDB process are discussed.

Case Histories Track - Tunnel Boring Machines

Room 4

Chair: Ian Danielson, Kiewit. Alexandria, VA

Co-Chairs: Joe O'Carroll, Mott MacDonald, San Diego, CA

1:30 PM

1:35 PM
Innovative Tunneling Technics in Singapore

Bernard Catalano1 , Estelle Clayes2

1Bessac Inc, Canonsburg, Pennsylvania , 2Bessac, St Jory, Haute-Garonne

The joint venture Penta Ocean / Bachy Solentanche, in partnership with BESSAC for tunneling works, have been allotted the T219 subway construction lot for an amount of 330 M€. The major works include the construction of: the new large subway station - with surrounding diaphragm walls, creating 210 m long, 40 m wide and 35 m deep- 2 parallel 830 m long tunnels with an ID of 5.80 m. The abrasive geology was decomposed granite and fractured granite with boulders. The tunnels were excavated by a slurry TBM. When the TBM reached the wall of the next allotted station at the end of the first drive, the machine was dismantled from inside the tunnel and retrofit into a new shell for the second tunnel. The TBM launch was completed with very low ground cover (1 meter below live large sewer), without ground reinforcement, in a very sensitive urban context. The project team develops high density technology to overcome the face stability risks. The scope of works also includes the construction of a pedestrian access (15 m x 9 m section, 50 meters long), located under a boulevard, which could not be interrupted. This underpass was constructed under the umbrella of a pipe roof previously built by jacking 18 concurrent steel pipes Ø 1270 mm, 41 m long, with micro tunneling method. Another additional challenge was the inability to retrieve the MTBM at the end of each drive from a shaft, which lead Bessac to use a fully retractable machine.

1:55 PM
Mechanized Excavation in Shale Formation. Performances Comparison between the Main Beam TBM Tunnels, the Single Shield TBM Tunnel and the Roadheader Tunnels at the Doan Valley Project.

Martino Scialpi1 , Karrie Buxton2 , Brian Negrea3

1Kiewit Infrastructure Co., Chagrin Falls, Ohio , 2NEORSD, Cleveland, Ohio , 3McNally Tunneling Corporation, Cleveland, Ohio

The Doan Valley Project in Cleveland, OH is part of the broader Project Clean Lake, a 25-year program that will help control combined sewer overflows (CSOs) and reduce the pollution in Lake Erie by 4 billion gallons per year. Within the same geological formation, three tunnels have been approached with different mechanized excavation technologies, different ground support systems and different final lining: the two 12’ dia. conveyance tunnels bored by an open gripper TBM, supported by ribs and lagging, then lined with reinforced concrete pipes (RCP); the 21’ dia. main storage tunnel bored and built by a single shield hard rock TBM with precast concrete segmental lining; the starter and tail tunnels’ horseshoe sections mined by a Roadheader, supported by rockbolts-wiremesh-shotcrete, then lined with cast-in-place concrete. In this paper mobilization/demobilization aspects, learning curves, performances achieved by each construction methodology are analyzed and compared in terms of safety during the operations, quality of the final product, cost and time effectiveness.

2:15 PM
The Dallas Mill Creek Drainage Relief Tunnel - Changing TBM Cutterhead Diameters in Mid-tunnel

Paul Smith1 , Milton Brooks2 , Quang Tran3 , Eudomar Silva4

1Black & Veatch Corporation, Richardson, Texas , 2City of Dallas Water Utilities, Dallas, Texas , 3Southland Holdings, LLC, Roanoke, Texas , 4Black & Vetach Corporations, Dallas, Texas

The Dallas Mill Creek / Peaks Branch / State Thomas (MCPBST) Drainage Relief Tunnel was designed to alleviate years of severe flooding in impacted neighborhoods and businesses east of downtown Dallas. The 8.04 km (5 miles) tunnel will change diameters from 11.45 m (37.58 ft) to 9.88 m (32.42 ft) and will be 30.5 m to 54.9 m (100 to 180 ft) deep in Austin Chalk. This paper will discuss the challenges of delivery, assembly and launching a Mega-TBM that will change cutterhead diameters in mid-tunnel and discuss the logistics of handling high volumes of muck within an urban setting.

2:35 PM
Completing Mexico City’s Mixed Ground Mega Tunnel: Emisor Oriente

Roberto Gonzalez1

1Robbins Mexico, Mexico D.F., Distrito Federal

On May 23, 2019, the last of six 8.93 m diameter EPBs completed excavation at Mexico City’s Tύnel Emisor Oriente (TEO), a feat marking the completion of ten years and 62.1 km of tunneling. The TEO is a critically-designated plan to stem severe flooding while boosting wastewater capacity, and is the country’s largest infrastructure project. The six EPB TBMs excavated some of the most complex geology on earth, ranging from abrasive volcanic rock to watery clays. This paper will cover the incredible challenges and solutions used to overcome what may be the toughest conditions ever bored by EPBs.

2:55 PM
Multiple use of TBMs for Singapore’s ground breaking conveyance system of Deep Tunnel Sewerage System Phase 2

Patrick Billian1

1Herrenknecht AG, Schwanau, Baden-Wurttemberg

Singapore is regarded worldwide as a prime example of a future metropolis of global importance. Over the years, Singapore made good progress in tapping underground spaces, from utility to metro lines and roads, to meet the many and growing needs of urban environment. The next major milestone in subterranean development is the construction of the 50km long Deep Tunnel Sewage System Phase 2, which is an island-wide network of tunnels running across the southern and western areas of Singapore. The paper focuses on the groundbreaking new gravity-fed deep tunnels that will all be excavated by TBMs.

Tuesday, June 9, 2020 | 8:30 AM

Technology Track - Innovative Solutions

Room 1

Chair: Dave Dorfman, Walsh, Warwick, NY

Co-chair: Everett Litton, WSP, Saint Louis, MO

8:30 AM

8:35 AM
Altered Tunnel Start due to Significant Surface Erosion in the Portal Area – A Creative Approach at Tunnel Herrschaftsbuck in Germany

Norbert Fuegenschuh1 , Roland Arnold2

1Beton- und Monierbau USA, Inc., Vienna, Virginia , 2BeMo Tunnelling, Austria, Innsbruck, Tyrol

Tunnel Herrschaftsbuck is a 480 m (1,575 ft) long double tube NATM highway tunnel project in Germany`s black forrest area. After the contract for the bid-build project was awarded, detailed survey showed that deep soil erosion had significantly altered the surface features at the West portal. Start of excavation as intended was therefore no longer an option. To resolve the problem the contractor proposed a method called the "Carinthian Cut & Cover Method", basically a combination of Cut & Cover and NATM-tunneling - a viable and economical solution under the given circumstances. The paper describes the methods used to survey the present situation, the development of the technical solution and the execution of the construction works on this challenging project.

8:55 AM
Deep Shaft Sinking Through Limestone, Mudstone, and Halite

Seth Pollak1 , Geoff Capes2 , Ted Mahoney3

1Arup, New York, New York , 2BHP, Roxby Downs, South Australia , 3BHP, Muswellbrook, New South Wales

The Jansen Project is a new potash mine development being undertaken by BHP in Saskatchewan, Canada. The project consists of a pair of shafts which have been sunk to a depth of approximately 1 km. Unlike previous shafts within the province, Jansen was sunk using new technology in the form of Herrenknect’s Shaft Boring Roadheader (SBR) machine. The shaft liner is being constructed via a two-pass method; with the final liner to be constructed from the bottom up. Shaft stability in the sinking condition is ensured through a combination of artificial ground freezing and primary ground support. The focus of this paper is the area of the shaft at a depth of 700 m to 900m composed of limestone, mudstone, and halite. This paper covers the characterization, primary ground support design and construction observations made within these zones.

9:15 AM
An Introduction to Low-Density Cellular Concrete and Advanced Engineered Foam Technologies

Nico Sutmoller1

1Aerix Industries, Timberville, Virginia

An introduction to Low-Density Cellular Concrete and advanced foam technologies. Beginning with a brief history of the technology, this presentation reviews the basics of cellular concrete (as defined by ACI523). The audience will be exposed to exciting applications, highlighting the Kaneohe Kailua Tunnel gravity sewer line in Hawaii where the grout was pumped for 2.84 miles. The presentation will also highlight some other global projects and how they relate to real world geotechnical challenges with emerging foam technologies. Attendees will learn the definition, and properties of low-density cellular concrete, mix design requirements, and QA/QC testing procedures. The learning objectives will be: 1. Discuss the history, definition, and properties of cellular concrete 2. Review mix design requirements and testing procedures 3. Explore typical applications and highlight some case studies 4. Review some emerging technologies, and how traditional cellular concrete technology is advancing to meet challenging project parameters

9:35 AM
Boring a Tunnel Under a Train Station Using Ground Freezing

Marc Bouffier1 , Louis Delmas2 , Benjamin Lecomte3 , Laurent Buissart4 , Christian GILBERT5

1VINCI CONSTRUCTION GRANDS PROJETS, Rueil-Malmaison, Hauts-de-Seine , 2SYSTRA, Paris, Paris , 3VINCI Construction Grands Projets, Rueil-Malmaison, Hauts-de-Seine , 4spie batignolles, Neuilly-sur-Seine, Hauts-de-Seine , 5SYSTRA, Paris, Paris

A mixed brine-nitrogen artificial ground freezing method was used for the extension of Paris Metro Line 14. The project consisted in the excavation of a 26m-long rectangular tunnel, carried out from two vertical shafts, with 122 freezing pipes. The tunnel intercepts three piles carrying an active commuter train station. The hydro-geotechnical context required the use of ground freezing as temporary support. The tunnel was divided in 6 sections, supported by heavy steel ribs and fiber shotcrete. During the works, several developments, such as the lifting of the station, water flows in the open frozen body shape and the thermal exchanges with the outside, added another level of complexity to the ground freezing handling.

9:55 AM
Long-Distance Annulus Tunnel Backfilling with Limited Grouting Access

Margaret Ganse1 , Ingrid Sandberg, PE2 , Steven E. La Vallee3 , Keith Lemaster4 , Randy Parks, PE5 , Michael Lehrburger, PE6

1Shannon & Wilson, Inc., Denver, Colorado , 2Shannon & Wilson, Inc., Denver, Colorado , 3Cematrix Cellular Concrete Solutions, Bristol, Illinois , 4Garney Construction Corporation, Littleton, Colorado , 5Dewberry Engineering, Denver, Colorado , 6Burns & McDonnell, Centennial, Colorado

The 7,614-foot-long Colsman Tunnel is owned and operated by the Southgate Sanitation District (District). The District and their Owners Advisor Burns & McDonnell retained the design-build team of Garney Construction, Dewberry Engineering, and Shannon & Wilson to rehabilitate the aging tunnel by sliplining it with a 48-inch diameter HDPE pipe during live flow conditions. Global Underground performed the sliplining using horizontal directional drilling, and Cematrix Cellular Concrete Solutions performed annulus grouting. Approximately 7,400 cubic yards of low density cellular concrete was placed. This presentation focuses on steps taken to mitigate the challenges associated with grouting long distances with limited access.

10:15 AM
Small Diameter Hydro Tunneling: A Powerful Solution for Renewable Energy

Sindre Log1 , Rune Skjevdal2

1The Robbins Company, Solon, Ohio , 2Norsk Grønnkraft (NGK) Utbygging AS, Oslo, Norway

Small hydroelectric projects, with installed capacity up to 10 MW, are a relatively untapped but potentially game-changing source of renewable energy in North America. In Norway, hydro projects are pioneering the use of small diameter TBMs in hard rock. Compared with drill and blast, TBMs offer increased production rates and reduction in cross section, among other benefits. The uniquely designed machines are engineered to take on steep gradients, up to a 45-degree angle in some cases. This paper will discuss the specialized TBMs at several projects in Norway, and the potential to use this technology in North American small hydro.

Design Track - Risk Management Through Effective Design

Room 2

Chair: Max Eden, JF Shea

Co-Chair: Nicholas Duchemin, CBNA: Civil & Building North America - Bouygues TP, Miami, FL

8:30 AM

8:35 AM
Setting Face Pressures for Settlement Control During EPB and Slurry Tunneling

Storer Boone1 , Nick Shirlaw2 , Stephen Barrett3

1Golder Associates Ltd., London, Ontario , 2Golder Associates Ltd (Hong Kong), Wanchai, Hong Kong Island , 3Golder Associates Pty. Ltd., Richmond, Victoria

Face pressures for control of EPB or slurry tunnel boring machines must be selected to avoid surface heave, large ground losses, maximize productivity and comply with ever more stringent surface settlement or volume loss criteria. Engineers commonly use simple empirical methods relating the ground surface settlement trough unit volume to tunnel unit volume, even for high risk projects, without considering root causes of volume loss at tunnel level. This paper summarizes methods for setting target face pressures for settlement control, reasons for and consequences of inadequate target pressures, identifies needs for future research and illustrates these issues with several case histories.

8:55 AM
Challenges to Urban Excavation through Chalk Formation

Eric Wang1 , Changsoo (Kevin) Moon2 , Charles Stone3

1HNTB Corporation, New York, New York , 2HNTB Corporation, New York, New York , 3HNTB Corporation, New York, New York

Although chalk limestone is generally viewed as a favorable medium for tunneling, its engineering properties can present unique challenges to be considered in design and construction. Specifically, selection of excavation methods and support systems for tunnels beneath congested urban centers should account for the ground behavior of underground construction in chalk. Challenges presented by specific engineering properties and the associated construction requirements are discussed including potential geo-hazards such as low uniaxial compressive strength, methane gas, solution cavities, faults, slickensides and principal stress ratio. Case histories are shared providing lessons-learned on two continents regarding overcoming these challenges.

9:15 AM
Everything is Deeper in Texas SAWS - Tunneling in the Navarro Claystone

Daniel Maine1 , Gail Hamrick-Pigg2 , Jeff Farnsworth3 , Kevin Mandeville4 , Melody Clay5

1Brierley Associates, Austin, Texas , 2San Antonio Water System, San Antonio, Texas , 3Kimley-Horn and Associates, Inc., San Antonio, Texas , 4Brierley Associates, Austin, Texas , 5Brierley Associates, Denver, Colorado

Aging infrastructure and increasing demand on sewer systems in San Antonio, TX is driving utilities to be bigger, deeper, and along more challenging alignments. Design for the replacement of a 54-inch sewer line through Lackland Air Force Base with a 104-inch sewer, via tunneling is underway. This 28,000-foot tunnel with eight shafts will be excavated through the challenging Navarro Formation Claystone. Challenges in designing this tunnel and how case histories of tunneling in this and similar formations helped develop the final design are discussed.

9:35 AM
Hard Rock Tunnel Rehabilitation: A Smaller Demonstration Project Informs Design of Complete Tunnel Rehabilitation Project

Rachel Martin1 , Kushwant Chohan2 , Glenn Boyce3 , David Tsztoo4

1McMillen Jacobs Associates, Walnut Creek, California , 2McMillen Jacobs Associates, Walnut Creek, California , 3McMillen Jacobs Associates, Walnut Creek, California , 4San Francisco Public Utilities Commission, San Francisco, California

San Francisco Public Utility Commission is currently designing a $140 million rehabilitation and repair project for the Mountain Tunnel, scheduled to begin construction in 2020. A $5.9 million interim repair contract was undertaken in 2018/2019 to perform portions of work and provide a demonstration of the project elements. The interim repairs, performed during a 60-day tunnel shutdown, included repairs to sections of tunnel liner, contact grouting, invert smoothing/paving, and construction water treatment. This paper discusses lessons learned from the design and construction of the interim contract and how these elements will be implemented in the larger Mountain Tunnel Improvements Project.

9:55 AM
Addressing Project Challenges and Integrating Construction Method Flexibility for the Rand Park Stormwater Diversion Tunnel, Keokuk, Iowa

Mahmood Khwaja1 , Michael Schultz2 , Michael Odrowski3 , Gregory Sanders4 , David Schechinger5 , Mark Bousselot6

1CDM Smith, Waban, Massachusetts , 2CDM Smith, Boston, Massachusetts , 3CDM Smith, Kansas City, Missouri , 4CDM Smith, Kansas City, Missouri , 5Veenstra & Kimm, Inc., Coralville, Iowa , 6City of Keokuk, Keokuk, Iowa

At an average invert depth of 85 feet, the Rand Park stormwater diversion tunnel is 2,920 feet long and has a 10-foot internal diameter. While the tunnel horizon is, primarily, within the regional Warsaw Shale, there are limited extent of mixed-face conditions in proximity of the junction structure at Fulton Street. With an appreciable distribution of geodes, the Warsaw Shale is interbedded with limestone. The project is on an accelerated design schedule and faces challenges, including: developing bid documents featuring flexibility on construction approach while maintaining control on project cost and schedule; addressing significant slope stability issues within the project limits; baselining complex subsurface conditions; and, meeting an anticipated short construction period. The paper presents the detailed design and bid document development approach that focuses on these project challenges.

10:15 AM
Supporting Post-bid Change in Segment Design and Machine Launching Philosophies for the Bergen Point Outfall Tunnel, Suffolk County, NY

Mahmood Khwaja1 , Keith Kelly2 , Michael Schultz3 , Janice McGovern4

1CDM Smith, Waban, Massachusetts , 2CDM Smith, Woodbury, New York , 3CDM Smith, Boston, Massachusetts , 4Suffolk County, Yaphank, New York

At more than 14,000 feet in length, the Bergen Point WWTP outfall tunnel was bid with a traditionally reinforced segmental lining, and with the boring machine to be launched from a shaft and starter tunnel, both using ground freezing to support respective excavations. During construction, the contractor modified the segment design to use fibre reinforced concrete; submitted a substitution to modify the machine launching approach, such that the first 400 feet will be tunneled using a method traditionally reserved for micro-tunneling, thus accommodating the installation of the trailing gear without the need for a starter tunnel. This paper provides a brief on the shift in, and the post-bid criteria development for, the segment design approach and the unique method for launching the slurry machine; evaluates the benefits and challenges related to these significant modifications to the original design; and, a quantitative study of the difference between traditionally reinforced and fibre reinforced concrete for the project-specific segment design.

Planning Track - Transportation

Room 3

Chair: Foteini Vasilikou, Arup, Blacksburg, VA

Co-Chair: Sebastien Gaugris, Vinci Construction. Montreal, Quebec, Canada

8:30 AM

8:35 AM
Highway Connection through Ouachita Mountains - Arkansas Tunnel Studies

Eric Wang1 , Heiner Sander2 , Michael Fugett3

1HNTB Corporation, New York, New York , 2HNTB Corporation, New York, New York , 3Arkansas State Highway and Transportation Department, Little Rock, Arkansas

Bypassing and lessening traffic impact on very historic Hot Springs, the Arkansas State Highway and Transportation Department (AHTD) initiated a high-level tunnel feasibility study for proposed east – west arterial highway under Hot Springs National Park. Supporting AHTD’s due diligence comparison of open-cut versus tunnel option, study addressed feasibility, constructability, and conceptual cost and schedule estimates for new tunnel through elevated ridge terrain featuring very hard Arkansas Novaculite formation. Site survey and local geologic data informed development of practical sequential excavation method (SEM) tunneling approach to address sensitive environmental conditions. Tunnel envelope optimization efforts helped meet AHTD minimum operational and NFPA 502 safety requirements.

8:55 AM
Large Single Bore Tunnel for VTA’s BART to Silicon Valley Phase II Extension

Anthony Bauer1 , Gordon Clark2 , Ronak Naik3

1HNTB, Long Beach, California , 2HNTB, Los Angeles, California , 3Santa Clara Valley Transportation Authority, San Jose, California

Santa Clara Valley Transportation Authority (VTA) is currently planning Phase 2 of the extension of the Bay Area Rapid Transit (BART) system into Silicon Valley, through downtown San Jose, California. A single bore tunnel configuration has been selected to allow two tracks and a center platform station to be located completely within the TBM tunnel lining. The resulting 5-mile long tunnel proposed for the project will have a nominal 54 ft outside diameter, passing through the dense downtown San Jose area and will include 3 underground stations. This paper summarizes the tunnel & station configurations, ventilation, Fire Life Safety, and constructability aspects of the project and discusses upcoming work.

9:15 AM
SCMAGLEV – Innovative Mass Transit in the Northeast Corridor (NEC)

Vojtech Gall1 , Timothy O'Brien2 , Nikolaos Syrtariotis3 , Cosema (Connie) Crawford4 , David Henley5

1Gall Zeidler Consultants, Ashburn, Virginia , 2Gall Zeidler Consultants, Ashburn, Virginia , 3Gall Zeidler Consultants, Ashburn, Virginia , 4WSP, Washington, District of Columbia , 5Baltimore Washington Rapid Rail, Baltimore, Maryland

The Northeast Corridor Superconducting Maglev Project (SCMAGLEV) entails construction of a high-speed train system between Washington, D.C. and New York City, with the first leg between Washington and Baltimore, MD. This innovative project will shorten travel times between Washington D.C. and Baltimore to 15 minutes, and connect to New York City in under an hour. In October 2019, the draft EIS will be issued for comment with a Final EIS/ROD by Summer 2020. This paper provides an update on the project and discusses the preferred alignment alternative, preliminary staging and launching of the TBMs for construction, and preliminary station design.

9:35 AM
Safety Challenges in Long Rail Tunnels

Bernd Hagenah1 , Sean Cassady2 , Hans-Peter Vetsch3 , Jason Yunglong Liu4

1HNTB Corporation, New York, New York , 2HNTB CORPORATION, Bellevue, Washington , 3Vetsch Rail Consulting, Bützberg, Bern , 4HNTB CORPORATION, Bellevue, Washington

Planning and operation of rail and transit tunnels and facilities require implementation of high standards to ensure health and safety of passengers and agency staff. Long tunnels pose a special challenge in emergency situations since it is unlikely that rescue forces could be engaged within a short reaction time required. Therefore, planning of tunnel facilities, associated equipment and procedures must actively support inherent simplicity of operations in the event of an incident. Best qualities of proper emergency planning reduce decision-making errors during emergency response scenarios while providing effective hazard mitigation for passengers, operating crew and first responders. This paper discusses best industry practices in managing the incident response for long rail and transit tunnels and points to lessons learned.

9:55 AM
Revisting Whittier Tunnel 20 Years After Conversion to Dual Rail/Highway Service

David Jurich1 , Paul Gabryszak2 , Matt Tanaka3 , Carl Hall4

1Mott MacDonald, Lakewood, Colorado , 2Mott MacDonald, Buffalo, New York , 3Alaska Department of Transportation & Public Facilities, Anchorage, Alaska , 4PND Engineers, Inc., Anchorage, Alaska

In 2001 the 13,300-foot long Anton Anderson Memorial Tunnel opened for dual highway and rail traffic. The conversion from rail earned the longest roadway tunnel in North America an ASCE Opal Award for engineering excellence and has transformed the economy of Whittier. As the tunnel approaches the successful end of its original 20-year design life, the Alaska DOT and the Alaska Railroad Corporation seek to extend the service life of the tunnel. This paper will describe investigations, designs, and construction enhancements to ground support and drainage systems, portal structures damaged by avalanches, emergency generator capacity, invert panels, and traffic signage.

10:15 AM
Proposed New Tunnels for Sound Transit’s LINK Light Rail Expansion

Anthony Pooley1 , Dirk Bakker1

1Sound Transit, Seattle, Washington

The Sound Transit 3 (ST3) program will add 62 miles of new light rail to the Seattle-Tacoma area, completing a 116-mile system by 2040. Two key projects will connect the neighborhoods of West Seattle to Downtown Seattle by 2030, and Ballard to Downtown Seattle by 2035. These projects will include the construction of a major new downtown tunnel, for which various configurations are being considered. For the West Seattle and Ballard sections, both elevated and tunnel options are under consideration. This paper describes the evaluation process leading to the choice of tunnel or elevated options, and selection of tunnel types. The technical challenges associated with the proposed tunnels are also outlined.

Case Histories Track - Shafts & Rehab

Room 4

Chair: Steve Price, Walsh, Little Falls, NJ

Co-Chair: Amanda Kerr, Michels, Brownsville, WI

8:30 AM

8:35 AM
Innovative SOE Solutions for Shaft Construction: Getting to Depth with Diaphragm Walls at Westerly Storage Tunnel

Jewels Stover1 , Lisa Smiley2 , Ryan Sullivan3

1Nicholson Construction, Canonsburg, Pennsylvania , 2Jay Dee Obayashi JV, Cleveland, Ohio , 3Northeast Ohio Regional Sewer District, Cleveland, Ohio

The Westerly Storage Tunnel (WST) Project is part of Project Clean Lake, the Northeast Ohio Regional Sewer District's program designed to reduce pollution in Lake Erie by 4 billion gallons over the next 25 years. When completed in 2020, WST will be nearly 2 miles of 25-ft diameter tunnel installed 200-250 ft below ground. The storage tunnel will manage higher flow volumes, reducing stormwater influx in the combined sewer system and reducing overflow occurrences. The project required three deep shafts to access the tunnel, one each at the launch and retrieval sites for the TBM and a third for a vent shaft. Support of excavation for the access shafts was constructed utilizing unreinforced diaphragm walls. This innovative, value-engineered alternate significantly reduced risks associated with traditional secant piles combined with a rib and liner plate system. Implementation of the diaphragm wall technology resulted in a water tight, continuous shaft keyed into rock. This case study and presentation will examine the design, methodology, installation approach, and challenges unique to each deep shaft.

8:55 AM
Pre-Excavation Activities for the Long Baseline Neutrino Facility Far Site

Seth Pollak1 , Jon Hurt2 , Ben Seling3 , Josh Willhite4 , David Vardiman5 , Syd DeVries6

1Arup, New York, New York , 2Arup, New York, New York , 3Kiewit, Omaha, Nebraska , 4Fermi Research Allicance, LLC, Lead, South Dakota , 5Sanford Underground Research Facility, Lead, South Dakota , 6Fermi Research Alliance, LLC, Lead, South Dakota

The Long Baseline Neutrino Facility Far Site at the Sanford Underground Research Facility in Lead, South Dakota will house four large detector tanks located deep underground. Construction of the supporting infrastructure required for this project is already underway including installation of a grizzly and rehab of existing mine drifts and ore passes for conveyance of waste rock. This paper will discuss the design and construction of these pre-excavation works, and the overall project schedule as it closes in on commencement of mass excavation activities.

9:15 AM
Laguna Beach Rehab Tunnel - Solutions for Unique Tunnel Rehabilitation Challenges

Scott Zlystra1, Trenton Cohen2 , Joe Sinacoci3 , Marc Serna4

1Parsons, Laguna Beach, California , 2Mott MacDonald, Los Angeles, California , 3South Coast Water District, Laguna Beach, California , 4South Coast Water District, Laguna Beach, California

A 60-year-old deteriorating sewer tunnel located beneath coastal cliffs and landslide slumps in Laguna Beach, California, is in need of rehabilitation and sewer pipe replacement. Since construction, the environmentally sensitive project area has grown with multimillion-dollar homes and heavy tourist activity that, along with incomplete historical records, add unique geotechnical, environmental and public relations challenges to the unique rehabilitation process. This paper presents the improved methods used for stabilizing and rehabilitating the existing sewer tunnel, and discusses the experiments and tools developed and employed by the project team for addressing variable and unexpected conditions, increasing productivity and shortening construction duration.

9:35 AM
Rehabilitation of Teck Coal Conveyor Tunnel in Elkview Mine, British Columbia

Irwan Halim1

1AECOM, Chelmsford, Massachusetts

The tunnel conveys raw coal to the processing plant, and needs to be rehabilitated to accommodate future mining nearby. This paper will describe the rehabilitation design approach and construction progress. Due to significant variation of the in-situ conditions along the tunnel, numerous design adjustments were required. Many challenges were encountered due to the difficult working environment inside the tunnel. This paper will describe the construction issues, solutions, progress and field adjustments that were needed during installation of lattice girders, CIP concrete, shotcrete, backfill grouting, and contact grouting for the rehabilitated tunnel, including lessons learned for similar rehabilitation of existing tunnels.

9:55 AM
Digging a Shaft in Free Phase Oil and Hydrocarbons, Reality vs. Fantasy

Ehsan Alavi1 , Sanjeer Yogendran2 , John Teahen3 , Abdul-Ghani Mekkaoui4

1Jay Dee Contractors, Inc., Livonia, Michigan , 2C&M McNally Tunnel Constructors, Burlington, Ontario , 3C&M McNally Tunnel Constructors, Burlington, Ontario , 4JayDee Contractors, Inc., Livonia, Michigan

The Don River & Central Waterfront Coxwell Sanitary Bypass Tunnel Project in Toronto will extend approximately 10.5 km from Ashbridges Bay Treatment Plant west under Lake Shore Boulevard, north under Bayview Avenue and east through the Don River park area to the Coxwell Ravine Park. This project includes the installation of five intake shafts connected by 10.4km of 6.3m internal diameter tunnel and eleven drop shafts and vent shafts, connected to the tunnel by a series of adits. During the excavation of one of five intake shafts (20m in diameter and 52m deep), significant volumes of free phase oil and hydrocarbons were encountered. This paper discusses the original design, shaft excavation methodology and the significant modifications that were made in order to successfully excavate the shaft in such harsh environment.

10:15 AM
Modern Mining: Engineered Tunneling Approach for Mine Access Tunnels

Timothy O'Brien1 , Nikolaos Syrtariotis2 , Vojtech Gall3 , Kyle Wooton4

1Gall Zeidler Consultants, Ashburn, Virginia , 2Gall Zeidler Consultants, Ashburn, Virginia , 3Gall Zeidler Consultants, Ashburn, Virginia , 4Frontier-Kemper Constructors, Evansville, Indiana

The recently completed Luck Stone Inter-Quarry tunnel in Leesburg, VA utilized an engineered tunneling approach employing the Sequential Excavation Method for an access tunnel connecting a newly opened pit to existing quarry and processing facilities. Such an approach is becoming more common place in the mining industry, with an engineered approach providing extended lifespans over 50 years and allowing risk management for critical mining infrastructure tunnels. Also discussed are additional examples of such an approach in new and existing tunnels of the Bingham Canyon Mine in Utah, and access/long-term production tunnels at the Soto Norte Gold Mine, Colombia.

Tuesday, June 9, 2020 | 1:30 PM

Technology Track - Design Innovations

Room 1

Chair: Bill Dean, Frontier Kemper, Evansville, IN

Co-chair: Zhenqi Cai, Mott MacDonald, New York, NY

1:30 PM

1:35 PM
Unreinforced Slurry Walls as Shaft Temporary Supporting System

Pooyan Asadollahi1

1Parsons, Washington, Maryland

Slurry walls, also known as diaphragm walls, are commonly used as temporary and/or permanent support of excavation for construction of shafts in soft ground. Through case histories, this paper demonstrates economical benefits of disregarding long-term structural contribution of the slurry walls particularly in sever environmental condition. In addition, for temporary slurry wall shaft systems, possibility of using steel fiber, synthetic fiber or additives in lieu of temperature/shrinkage reinforcement is discussed with detailed analysis. Finally, the paper will be concluded by introducing unreinforced slurry wall shaft system using newly developed/patented concrete additives.

1:55 PM
Probabilistic Modeling of Geological Transitions along a Tunnel Alignment

Rajat Gangrade1 , Mike Mooney1 , Whitney Trainor-Guitton1

1Colorado School of Mines, Golden, Colorado

Transitions between geological/geotechnical soil units will have a critical impact on the operation and performance of a tunnel boring machine (TBM). However, with typical geotechnical site-investigation campaigns on tunneling projects, there exists a considerable uncertainty in the depth and thickness of a soil layer of interest. This paper presents a case study on the probabilistic modeling of the interpreted transitions between soil units using geostatistical techniques. The assessment aids in developing a comprehensive geological model for tunneling risk assessment, minimizing claims due to unforeseen geological conditions and improve decision-making within tunneling projects.

2:15 PM
Designing and Implementing Risk Mitigation for Existing Critical Utilities by Means of Excavation Sequencing

Gregory Rogoff1 , Karrie Buxton2 , Josh Suffel3 , Brad Murray4

1McMillen Jacobs Associates, Mayfeild Heights, Ohio , 2Northeast Ohio Regional Sewer District, Cleveland, Ohio , 3McNalley Internation Inc., Westlake, Ohio , 4McMillen Jacobs Associates, Mayfield Heights, Ohio

Aged and vulnerable utilities, including water mains 12 to 30-inches in diameter, were required to be left undisturbed near the excavation and construction of a sewer diversion structure (DVS) and consolidation sewer (CS) as part of the Northeast Ohio Regional Sewer District’s Doan Valley Storage Tunnel Project. Minimal clearances were available between existing utilities and the DVS excavation, which necessitated a coordinated work sequence to maintain flows in the existing brick Doan Valley Interceptor and complete a deeper tunneled tie-in between the DVS and the CS. Acoustic sensors were used to monitor the effects of construction on the water mains.

2:35 PM
Reaching New Depths: Innovations in Technological Site Characterization Tools for Integrated Tunnel Design

Erin Sibley1 , Amanda Wachenfeld2

1Mott MacDonald, Chicago, Illinois , 2Mott MacDonald, Westwood, Massachusetts

Traditional methods for capturing and analyzing site characterization data for tunnel projects, such as hand-written field logs and CAD-based subsurface profiles, have remained relatively disconnected from the overall ground model and tunnel structural design. However, recent innovations in digital automation and data collection offer the opportunity for more holistic design, allowing detailed information to be carried through the exploration stage to subsequent project phases. This paper presents state-of-the-art tools for design development, such as a cloud-based field report application, digital data planning and management tools, and 3D geologic modeling software, and how they are utilized for seamless, integrated tunnel design.

2:55 PM
Advancements in Durable Segments for Utility Tunnels

Ralf Winterberg1

1BarChip Inc., Tokyo, Okayama

The Blacksnake Creek Stormwater Separation Project will convey stormwater directly to the Missouri River. This will reduce water quantity in the existing sewer during storms and the quantity of combined stormwater and wastewater overflowing to the river. Currently, a 2.75 m ID and 2 km long segmental tunnel is under construction as part of the Separation Project. This project is an America’s First, using segments solely reinforced with macro synthetic fibre (MSF). This paper addresses the solutions to the technical challenges of the project, the design of the segments and the benefits associated with the use of MSF.

Design Track - Resiliency

Room 2

Chair: Andre Solecki, Hatch, Mississauga, Ontario, Canada

Co-chair: Franz Wilhelmstoetter, Dr. Sauer, Herndon, VA

1:30 PM

1:35 PM
LED Lighting for Hazardous and Gassyocation

Brian Astl1 , Jacob Hunter2

1Lind Equipment, Markham, Ontario , 2Jennmar, Matthew, North Carolina

This paper looks at the new advances in LED lighting as it pertains to tunneling in areas determined to be potential gassy / hazardous locations. LED construction lighting uses less electricity, creates less heat, and can be used in more versatile ways than traditional bulb based lighting. This technology is now being applied to hazardous location and tunneling applications that will save time and money while keeping workers safe.

1:55 PM
Tunnel Rehabilitation and Structural Modifications

Peter Torres1 , Ravi Jain2 , Daniel Garcia3

1WSP, New York, New York , 2WSP, Forest Hills, New York , 3WSP, New York, New York

The rehabilitation of transportation tunnel structures is comprised of concrete or steel repair, strengthening, leak remediation and cognizance of systems within. The results of visual surveys, non-destructive testing and geophysical investigations are amalgamated to understand the original design practices during the era in which the structures were constructed and develop designs that meet the project requirements while maintaining the structural integrity. Recent advances in structural analysis modeling, waterproofing and remediation allow for economic prescribing of repairs. Key challenges discussed include developing load transfer systems, performing rehabilitation while maintaining service along with electrical, mechanical and communication components.

2:15 PM
New Aspects in Tunnel Ventilation

Petr Pospisil1

1IP Engineering, Muenchenstein, Switzerland

For tunnel fire life safety, the crucial questions are where people are situated, where to escape, and how the smoke spreads. Designing or even operating a tunnel ventilation system to achieve the critical velocity must be questioned, since most fatalities in tunnel fires have died due to quick spread of toxic smoke, caused by the inappropriate operation of tunnel ventilation. Instead, the longitudinal airflow must be controlled. Engineering know-how and experience, high redundancy of critical elements, quality control in all stages of implementation and thorough testing in site under different conditions are key issues to achieve reliable operational safety.

2:35 PM
Investment and Operation Cost Savings with Innovative Fire Life Safety Systems Design

Hubert Heis1 , Reinhard Gertl2 , Hans Haring3

1ILF Consulting Engineers Austria GmbH, Rum, Tirol , 2ILF Consulting Engineers Austria GmbH, Rum, Tirol, 3ILF Consulting Engineers Austria GmbH, Rum, Tirol

The paper considers project examples where cost savings have been achieved by developing different concepts for Fire Life Safety equipment. In several case studies it will be demonstrated that due to an alternative approach during the design phase significant reduction in the cost of equipment and in some cases even construction costs could be minimized. The impact of optimized design to operation and maintenance cost will also be part of the investigation. Due to a well thought out ventilation concept intermediate vent shafts could be avoided or the intermediate ceiling was eliminated. Other examples point out how cabling cost or operation and maintenance cost can be reduced for tunnel lighting.

2:55 PM
Rock Burst Due to High In Situ Horizontal Stress Adjacent to Tunnel and Shaft

William Zietlow1 , Anna Crockford1

1Brierley Associates, Denver, Colorado

The Maline Creek CSO Storage Facility in St. Louis, Missouri, was designed to collect and store CSO in a deep limestone cavern. The St. Louis area is known to have high horizontal stresses. Due to the orientation of the tunnel relative to the stress field, the shaft and tunnel excavations caused stress concentrations which effectively quadrupled in the crown near the shaft. The stress concentrations exceeded the strength of the rock resulting in a rock burst event, causing a large offset in the tunnel crown near the tunnel-shaft intersection. The overstress conditions were observed declining with distance from the shaft.

Planning Track - Risk Management

Room 3

Chair: Mark Ramsey, Mott MacDonald

Co-chair: Matt Paulisich, Dragados

1:30 PM

1:35 PM
Risk Mitigation Strategy for the Big Walnut Sewer Extension Tunnel in Columbus, Ohio

Irwan Halim1

1AECOM, Chelmsford, Massachusetts

This project will expand sanitary sewer service within the City of Columbus. It consists of 2.5 mile long, 72-inch finished diameter pipe to be grouted inside 10-foot diameter tunnel excavation in shale. This paper describes the multi-faceted geotechnical exploration during tunnel alignment study to minimize the ground condition risks. The tunnel will cross immediately below a buried valley with minimum cover of poor and highly weathered rock with potential soil-like inclusion. The risk mitigation strategy to cross the valley will be discussed to include contingencies and cost allowances. Design provisions to prevent impact on adjacent groundwater resources will be described.

1:55 PM
Estimating Project Contingency Reserves – Now What?

Joe OCarroll1 , Keith Ward2 , Erika Moonin3

1Mott MacDonald, San Diego, California , 2City of Seattle Public Utilities, Seattle, Washington , 3Southern Nevada Water Authority, Las Vegas, Nevada

In underground construction risk and uncertainty is prevalent from the very outset of a project. A risk and uncertainty analysis is useful to help convey confidence in delivering a project within an available budget. But once the analysis is performed, what should a Project Owner do with the information and data available and how does it shape the outcome or even viability of a project? This paper looks back at projects from a “what, if anything, could have been done better” and looks forward as to “how should the analysis inform delivery methods and contingency reserves once bids are received”.

2:15 PM
Tunneling In A Dense Urban Environment – The Edgewood Avenue Near Surface Collector Project

Gregory Sanders1 , Mahmood Khwaja2 , Michael Schultz3

1CDM Smith, Kansas City, Missouri , 2CDM Smith, Boston, Massachusetts , 3CDM Smith, Boston, Massachusetts

The Milwaukee Metropolitan Sewerage District (MMSD) is designing a new near surface collector extension sewer to improve the Shorewood/Milwaukee combined sewer service area system hydraulics. The project includes the design and construction of a 66-inch conveyance pipe to be constructed parallel to, and in close proximity of, an existing 78-inch pipe. This paper presents the local geology and subsurface conditions, as well as discusses the major project challenges and risks including construction in proximity to existing sewer system and utilities, dense urban environment, and coordination with multiple stakeholders. Project is in the preliminary design phase; expected to be advertised for bid in mid-2020.

2:35 PM
Reliability, Availability, Maintainability, Safety (RAMS) analysis for complex tunnel construction systems – applications and benefits

Philip Sander1 , John Reilly2 , James J. Brady3 , Markus Spiegl4

1Bundeswehr University Munich, Neubiberg, Bavaria , 2John Reilly International, FRAMINGHAM, Massachusetts , 3Aldea Services Inc., Decatur, Georgia , 4RiskConsult, Innsbruck, Tyrol

Mechanical tunneling is characterized by significant uncertainty and complex systems. These apply to the entire supply chain related to the operation and maintenance of TBMs. If the reliability and availability of these systems is not secured, delays and increased costs can, and do, occur. RAMS (Reliability, Availability, Maintainability, Safety) is a process for early identification and planning for such failures by evaluation all the components of a system using Fault Tree Analysis. This paper explains the benefits of the application of probabilistic RAMS analysis in tunneling using the example of a TBM supply train from the Brenner Base Tunnel project.

2:55 PM
Second Narrows Water Supply Tunnel – Planning through Construction Procurement

Gregg Davidson1 , Frank Huber2 , Andrew McGlenn3

1McMillen Jacobs Associates, Seattle, Washington , 2Metro Vancouver, Burnaby, British Columbia , 3McMillen Jacobs Associates, Seattle, Washington

The Second Narrows Water Supply Tunnel will ensure system reliability in the event of a major earthquake and increase the Greater Vancouver Water District’s capacity to meet the long term needs of a growing population. The tunnel will be 1100m long and 6.5m in diameter, constructed under Burrard Inlet between North Vancouver and Burnaby in British Columbia. It will be excavated through mixed ground conditions under high groundwater pressure, using a slurry TBM, between a 60m deep shaft in soil and a 110m deep shaft in rock. The completed tunnel will accommodate three large diameter water mains which will be installed as part of the tunnel contract. This paper presents the project from planning, through design and into construction procurement, describing some of the unique challenges encountered.

Case Histories Track - Planning and Overcoming Challenges

Room 4

Chair: Oliver Robert, Bessac

Co-chair: John McCluskey, NYC DEP, New York, NY

1:30 PM

1:35 PM
Startup and Operation of Deep Rock Tunnel Connector and Pump Station

Alexander Varas1 , John Morgan2

1AECOM, Zionsville, Indiana , 2Citizens Energy Group, Indianapolis, Indiana

The Deep Rock Connector Tunnel (DRTC) and Pump Station (PS) were placed into service on December, 2017 and March, 2018, respectively. The tunneling contractor (JF Shea JV) was responsible for the construction of the tunnel, three CSO diversion structures, and a common Launch/PS Screen and Grit shaft. The pump station contractor (Renda Southland JV) was responsible for constructing a pump station within an underground cavern excavated in rock. This presentation will discuss how the work and scheduling challenges were overcome in order to have the facilities in operation by the mandated Consent Decree in service dates.

1:55 PM
Lake Mead Intakes Nos. 1, 2 and 3: Fifty Years in the Making

Erika Moonin1

1Southern Nevada Water Authority, Boulder City, Nevada

When the Southern Nevada Water Authority’s Low Lake Level Pumping Station is complete in 2020, it will be the crowning jewel in a 50-year effort to successfully tap Southern Nevada’s allotment of Colorado River water from Lake Mead. The Lake Mead Intake No. 3 projects began in 1969 and include three intakes, tunnels, forebays, miles of large-diameter transmission pipe, and soon three pumping stations, all constructed in challenging ground conditions. These projects were constructed in a race against time to accommodate a growing community and to stay ahead of potential debilitating operational challenges due to a persistent, long-term regional drought.

2:15 PM
Design and Construction Considerations for Long Distance Small Diameter Tunnels

Jim Buckley1 , Konner Horton2 , Adam Bedell3 , Don Del Nero4

1Guy F. Atkinson Construction, Decatur, Georgia , 2Guy F. Atkinson Construction, Atlanta, Georgia , 3Stantec, Atlanta, Georgia , 4Stantec, Clarkesville, Georgia

During project development and design, water tunnel alignment and sizing are often driven by hydraulic or storage requirements. The Atlanta Water Supply Project involves 5 miles of 12.5 feet excavated diameter, 10 feet finished diameter tunnel 250 to 450 ft below ground surface excavated with a main beam hard rock TBM. This paper will focus on the challenges encountered due to the length and diameter from a contractor’s point of view, focusing on the mining, lining, and grouting operations. Recommendations presented suggest a small increase in tunnel diameter could result in larger savings during construction.

2:35 PM
Semmering Base Tunnel - A Challenge in Tunneling

Erich Neugebauer1 , Michael Proprenter1

1iC consulenten ZT GmbH, Salzburg, Vienna, Austria

With a total length of 17 miles the Semmering Base Tunnel in Austria is one of the outstanding tunneling projects currently under construction in Europe. At this stage a considerable length of the twin tube railway tunnels including cross passages, an underground emergency and ventilation station, deep shafts and large caverns have been built by means of SEM and TBM method. Major fault zones and an extensive water inflow create highly challenging conditions for the tunneling works. The presentation provides a comprehensive and detailed insight into the construction works which started in 2014 and last till 2026.

2:55 PM
Construction of the Albany Park Stormwater Diversion Tunnel

Sotirios Vardakos1 , Mark Stephani2

1WSP, NEW YORK, New York , 2WSP, CHICAGO, Illinois

The Albany Park neighborhood in Chicago, IL has historically experienced significant flooding impacting hundreds of homes along the North Branch of the Chicago River. To reduce impacts from flooding, the City constructed a 5835 ft long, 18 ft diameter diversion tunnel that can relieve excess flows during flood events. This paper presents the challenges encountered during tunnel construction and the methodologies implemented for successful completion of the project. Sequential excavation method (SEM) for construction of the assembly chamber, TBM performance, the encounter of a fracture zone, and the instrumentation and monitoring programs are described in the paper.

Wednesday, June 10, 2020 | 8:30 AM

Technology Track - Digital Technology

Room 1

Chair: Claire Maddox, Kiewit

Co-chair: Ike Isaacson, Brierley Associates, River Hills, WI

8:30 AM

8:35 AM
EPB TBM Automation: What's Possible?

Mike Mooney1

1Colorado School of Mines, Golden, Colorado

Self-driving cars and automated drilling suggests that tunneling is headed towards significant automation. How do we get there? This paper examines EPB TBM automation, including (1) the various subsystems and how these can be automated (e.g., ring assembly, cutterhead cruise control, soil conditioning); (2) the challenges in automating the excavation process, i.e., delivering the appropriate suite of operator controlled inputs to maintain productivity, alignment and negligible ground deformation? (3) The power of artificial intelligence in enabling automation; (4) the level of TBM performance improvement possible through automation; (5) and the implications on risk, including risk ownership.

8:55 AM
Innovative Tools to Control Project Risks

Bernard CATALANO1 , Bernard THERON2

1Bessac Inc, Canonsburg, Pennsylvania , 2BESSAC, St Jory, Haute-Garonne

Four new complete new subway lines are under construction mobilizing 21 TBMs. Those years of no exposure to underground works for a generation of personnel has resulted in safety and performance challenges to this gigantic project. TBM operations call for specific skills not available in other sections of our construction industry. Segmental ring erection and hyperbaric works for cutter head maintenance are two crucial activities of soft ground TBM tunneling. The development of innovation, such as training tools and managing tools, has emerged as essential in order to support excavation operations for its 4 TBMs operated by Bessac and its partner.

9:15 AM
BIM implementation in the Design of Underground Structures for the Réseau Express Métropolitain (REM) project in Canada

Theodora Vovou1 , KiSeok Jeon1 , Verya Nasr13

1AECOM, New York, New York

Building Information Modeling (BIM) application in the design of underground structures is an increasing trend in the tunneling industry. The purpose of this paper is to present advanced analysis methodologies that were applied to develop a multidisciplinary BIM system for the design of underground stations and the representation of an existing tunnel for the Réseau Express Métropolitain (REM) project in Montréal, Canada. Advantages of processing laser scanning technology, such as LiDAR and GPR data, to improve the design process and automate drawing production, as well as challenges associated with the process of integrating existing tunnel structures in the BIM model, are discussed. Lessons learned from this megaproject provide useful information for the implementation of BIM in future tunneling projects.

9:35 AM
Settlement Monitoring during Tunneling Using Continuous InSAR and Trend Detection Analysis

Giacomo Falorni1 , Marie-Josee Banwell1 , Sara Del Conte1

1TRE Altamira Inc., Vancourver, British Columbia

Satellite radar interferometry (InSAR) is employed for ground and structure deformation monitoring during all tunnelling project phases (design, construction, and operation) as a forensic analysis tool, with periodic updates of movement history. These mainly retrospective analyses provide a dense cloud of measurement points that integrate and complement the smaller networks of benchmarks used for the in situ, real-time deformation monitoring. However, significant advances to data processing algorithms and the adoption of cloud computing are now allowing measurements to be updated within hours of each new satellite image acquisition, which occurs every 6 to 12 days, depending on the satellite system employed. It is even possible to use several different satellite orbits to provide near-daily updates if required. The advent of constant updates introduces new problems associated with the management of big data sets and the highlighting of relevant information. Every update typically includes hundreds of thousands to millions of measurement points in urban environments, meaning that the timely identification of the points containing key information becomes fundamental. The development of a trend change detection tool, designed to rapidly sift through millions of points and flag only those where changes in ground deformation trends have occurred, including pre-set thresholds are approached or exceeded, addresses this issue by immediately attracting the attention of the stakeholder to those points that warrant further investigation. Applications of this approach including examples of the Trend Detection tool for urban tunneling projects will be presented, illustrating the integration of InSAR data into tunnel monitoring plans.

Design Track - Precast Concrete Tunnel Linings
Planning Track - Water/Wastewater

Room 3

Chair: Mike Wongkaew, HNTB

Co-chair: Ivan Hee, Skanska

8:30 AM

8:35 AM
Brushy Creek Regional Utility Authority Phase 2 Raw Water Delivery System Project

James Parkes1 , Aaron Archer2

1Schnabel Engineering, Baltimore, Maryland , 2Walker Partners, Austin, Texas

The Brushy Creek Regional Utility Authority (BCRUA) is a partnership of the cities of Cedar Park, Round Rock, and Leander, Texas. The Phase 2 Raw Water Delivery System is a new deep water intake and conveyance system at Lake Travis. The estimated $160M project includes two lake taps with multilevel screens; a 9,000 LF gravity intake tunnel with a minimum 8-ft internal finished diameter concrete liner; an underground suction chamber with 6 well shafts; a 30-ft diameter, 300-ft deep construction access shaft; a 2,600 LF transmission tunnel with an 84-inch welded steel final liner; an exit shaft approximately 155 feet deep at the end of the transmission tunnel; a 145 MGD pump station with 10 pumps; and a maintenance building for chemical feed systems to the intake shafts. The majority of the underground work will be in limestone of the Glen Rose formation. Final design is underway with anticipated bid date of June 2021 and construction start date of January 2022. Major project elements, design developments, constraints, procurement methods, and project schedule are presented herein.

8:55 AM
Determining the Feasibility of Tunneling for Flood Mitigation after Hurricane Harvey

Brian Gettinger1 , Scott Elmer2 , Michael Joye3 , Don Wotring4 , Patrick Beecher5 , Hector Olmos6

1Freese and Nichols, Houston, Texas , 2Harris County Flood Control District, Houston, Texas , 3Parsons, Philadelphia, Pennsylvania , 4Brierley Associates, Cambridge, Massachusetts , 5Terracon, Houston, Texas, 6Freese and Nichols, Houston, Texas

Up to 60 inches of rain fell during Hurricane Harvey leading to widespread flooding, $125 billion in damages and 65 deaths. Existing flood mitigation infrastructure is struggling to handle increasingly frequent large storms events and increasing population. Large diameter, deep inverted siphon tunnels have been proposed as a solution to improve system conveyance capacity; however, few large diameter tunnels have been built in Houston due to perceived challenges with soft clay and sandy soils, high groundwater, and faulting. This paper discusses the outcome of a feasibility study including insights on geotechnical conditions, applicability of tunneling, conceptual cost estimate, and hydraulic capacity for the potential very large diameter and long inverted siphon tunnel(s).

9:15 AM
Allegheny County Sanitary Authority - Tunnel System Preliminary Planning

Mike Lichte1 , Daniel Dobbels2 , Kim Kennedy3 , Tim O'Rourke4

1Allegheny County Sanitary Authority, Pittsburgh, Pennsylvania , 2McMillen Jacobs Associates, Burilington, Minnesota , 3Allegheny County Sanitary Authority, Pittsburgh, Pennsylvania , 4Wade Trim, Cleveland, Ohio

ALCOSAN’s planned improvements to better manage wet weather responses include a network of storage tunnels, green infrastructure and WWTP expansion to meet a federal mandate. A Preliminary Planning (PP) Project began in 2017 to optimize the tunnel system and complete preliminary engineering studies. The PP project will be completed in November 2020 with final design anticipated to begin in 2021. The tunnel system consists of approximately 15 miles of 14 to 16 ft diameter tunnels, approximately 20 drop shafts and 5 miles of near surface consolidation sewers. This paper will review preliminary planning and design aspects and anticipated construction sequencing.

9:35 AM
Assembly and Launch of the Coxwell Bypass TBM, Assessment of Complete vs. Partial TBM Assembly

William Hodder1 , Brian Hesano2 , Ehsan Alavi3 , Paul Cott4

1Jay Dee Contractors Inc, Toronto, Ontario , 2JayDee Contractors, Inc., Livonia, Michigan , 3JayDee Contractors, Inc., Toronto, Ontario , 4Jay Dee Canada ULC, Toronto, Ontario

The Don River & Central Waterfront Coxwell Sanitary Bypass Tunnel Project in Toronto will extend approximately 10.5 km from Ashbridges Bay Treatment Plant west under Lake Shore Boulevard, north under Bayview Avenue and east through the Don River park area to the Coxwell Ravine Park. The tunnel will be mined by using a shielded tunnel boring machine capable of operating in EPB mode and lined by using a precast concrete segmental tunnel linear with an internal diameter of 6,300 mm and external diameter of 6,900 mm. North Tunnel Constructors LLC, a joint venture of Jay Dee Canada, Michels Canada and C&M McNally Tunnel Constructors, decided to extend the length of the starter tunnel to about 115m to be able to fully assemble the tunnel boring machine inside the starter tunnel. In this paper, the rationale behind this decision in addition to the assembly process have been discussed. Furthermore, 3D modeling is being utilized as a tool to efficiently describe the assembly process and address potential conflicts prior to start of TBM assembly.

Case Histories Track - Microtunneling and Hand Mixing

Room 4

Chair: John Arciszewski, Southland Construction, Middleburgh, NY

Co-chair: Anna Crockford, Brierley Associates

8:30 AM

8:35 AM
Sur de Texas-Tuxpan Project. World Record Microtunneling Drive with an Underwater Recovery.

Marc Marti Cardona1, Hector Trigal2

1TERRATEST, Madrid, Community of Madrid , 2TERRATEST, Madrid, Madrid

The Sur de Texas-Tuxpan gas pipeline is an offshore natural gas pipeline between Brownsville, Texas, and Veracruz, Mexico. The $3.1 billion project is being developed by the Federal Electricity Commission (CFE) of Mexico and is the country’s first subsea pipeline. A key component of the Sur de Texas-Tuxpan project was the Altamira Landfall. This piece of work included a world record 7,360-ft microtunneling drive of 10.5-ft OD pipe from the shore under the Gulf of Mexico with an underwater recovery of the MTBM. The drive also involved two vertical curves. The main challenge presented by the installation of the pipeline was the crossing of environmentally sensitive areas, such as, mangrove areas and coral barriers. For the crossing of these areas, the use of trenchless technology was chosen instead of other conventional techniques, such as installation in open trench which causes greater impact and affectation. TERRATEST Group not only completed the tunnel at Altamira Landfall but built the launching shaft, the ramp to allow the bundle installation and conducted other civil works such as foundations for the gantry cranes and auxiliary equipment. This paper discusses how many of the challenging aspects of the $55 million USD project were successfully overcome. Some of these challenges included tunnel completion having a very low skin friction (0.4 kN/m2) and an average jacking force of (0.65 T/m), installation of two 42-inch gas transmission pipelines and one 24-in. water line bundle and “wet” retrieval of both the TBM and Push-Module from the seabed.

8:55 AM
A Tale of Two Tunnels: The Cooksville Creek Trunk Sanitary Sewer

Alex Burnett1 , Marc Gelinas2 , Grace Krasowski3

1Hatch, Oakville, Ontario , 2Hatch, Oakville, Ontario , 3The Regional Municipality of Peel, Brampton, Ontario

The Cooksville Creek trunk sanitary sewer (CCTSS) is a 1200mmØ sanitary sewer that services the City of Mississauga in Ontario, Canada. Constructed in two phases, the CCTSS was installed via two-pass conventional TBM methods in 2010 and was installed via single-pass microtunnelling methods in 2019. As the consulting and design engineer for both phases, Hatch has a comprehensive knowledge of the project and will compare the methods of installation, including production, impact to the urban environment, and project cost. The paper will provide conclusions regarding advantages and disadvantages of both tunneling methods, and recommendations where each method may be preferred.

9:15 AM
How Do You Eat an Elephant? Hand Mining in the 21st Century

John Elliott1 , Edward Gillard2

1Golder, Doncaster, South Yorkshire, 2Golder, Doncaster, South Yorkshire

How do you eat an elephant? …one small bite at a time! Golder describe the complex works methodologies and innovative design solutions developed to introduce step-free access to one of London’s oldest, busiest inter-modal stations in what appears to be an inverted safety-critical game of Jenga. Lift shafts were constructed through overground rail platforms, between the now-exposed underground platform tunnels while the station remained in full operation, the complex 3D geometries only made feasible by the adopted methodology. By adapting and modifying the legacy assets they were safeguarded, while providing greater capacity, connectivity, accessibility and an improved passenger experience.

Tunnel Demand Forecast Plenary Session

Wednesday, June 10, 2020 | 10:15 AM - Noon
Session Chair: Jonathan Klug
Vice President, David R. Klug & Associates

The Tunnel Demand Forecast session will have presentations from various owners and engineers regarding upcoming projects throughout the US and Canada. An overall update and summary of North American tunnel projects will also be given. Some of the projects and programs to be discussed will include:

  • MWRA Metropolitan Tunnel Program, Boston, Mass.
  • DART D2 Subway, Dallas, Texas
  • Sound Transit, Seattle, Washington
  • Superconducting MAGLEV Project, Baltimore/Washington D.C.
  • Canadian Upcoming Projects Update

Each presentation will last approx. 20 minutes with limited question and answer period to follow. Presentation list is subject to change based on speaker availability.