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Technical Sessions that Enlighten


The 2020 NAT Conference is proud to present technical sessions hosted by some of the leading innovators and technology from around the world. To learn more about available sessions, please view the complete list below.

Monday, June 25, 2018 | 9:30 AM

Technology Track - Project Controls

Chair: M. Younis, Subsurface & Tunnel Engineering LLC, Frederick, MD

Co-Chair: B. Catalano, Bessac, El Granada, CA

5D BIM applied to Cost Estimating, Scheduling and Project Control in Underground Projects
G. Venturini and F. Maltese; SWS Engineering, Toronto, Ontario, Canada and G. Teetes; Schnabel Engineering, Dallas, TX

Building Information Modeling (BIM) is a progressive delivery method that integrates multiple project sources into a 3D model toolbox. The construction schedule becomes the 4th dimension (4D) with the cost component becoming the 5th dimension (5D). 5D BIM allows the project lifecycle, from concept to construction, to be harnessed and shared in a common environment. The toolbox generates multi parameter models that permit to manage several strategic project data. BIM precision is related to the level of development (LOD), which increases with each single project life phase (from preliminary to detail and construction design). This paper provides useful case studies of BIM applied to cost estimating, scheduling and project control in underground projects.

Analysis of Concrete Lined Tunnels Crossing Active Faults
S. Lange, H. B. Mason, M. H. Scott, and S. A. Ashford; Oregon State University, Corvallis, OR

It is known that earthquakes with magnitudes greater than M6.0 can cause significant damage to tunnels. In particular, large strains due to fault offsets lead to severe damage in the tunnel lining, (e.g., concrete spalling), which can lead to potential closure and disruptions to the transportation network. Examining the response of the soil-structure interaction between tunnels and active fault zones, where damaging earthquake ruptures with significant offsets are possible, is critical to ensure resilient design and safe operation. Preliminary results of a calibrated 2D model of a circular reinforced concrete lined tunnel crossing an active fault show earthquake magnitude, fault geology, and structural properties of the tunnel are influential parameters. These results imply that novel tunnel design strategies are necessary.

Atmospheric Cutting Tools Replacement in EPB TBM “Bertha� Innovative Approach for Face Pressure Tunneling
J.L. Magro; Dragados, Madrid, Spain, R. Piquera; Dragados USA, Virginia Beach, VA and J. Garnero, Dragados, Seattle, WA

“Bertha�, the 17.48 m diameter world-record EPB TBM manufactured by Hitachi Zosen completed the excavation of the challenging SR99 Bored Tunnel under downtown Seattle in early April 2017 and the ability to replace cutting tools at atmospheric pressure from within cutterhead spokes while maintaining full face pressure was key to such accomplishment. This paper discusses the design, implementation and performance of this innovative system in this project and explores its promising role in upcoming face pressure tunnels, especially in those with challenging ground conditions and beneath sensitive areas such as crowded downtowns and under water.

Logistics and Performance of a Large Diameter Crossover TBM for the Akron Ohio Canal Interceptor Tunnel
P. Salazar; Robbins, Solon, OH and C. Maxon; Kenny-Obayashi JV,

The Ohio Canal Interceptor Tunnel (OCIT) below the city of Akron is utilizing the first large diameter Dual Mode, “Crossover� type TBM in the United States. The 30.4 ft diameter machine is excavating in variable conditions including soft ground and shale rock. Due to the unique conditions, the TBM has been designed with features including a flexible cutterhead design and abrasion-resistant plating on the cutterhead and screw conveyor. As part of a predictive maintenance plan, measurements for the screw conveyor’s exposed features will be taken along the drive to report on the wear rate of these components in shale. This paper will concentrate on the logistics and process of the TBM launch, and component wear and performance at the jobsite in variable ground conditions.

Job Site Security Risk Management Beyond Gates, Guards and Guns
E. Jacobs; MSAG

Economics and safety are driving technology into tunnel project monitoring and tunnel control systems at an accelerating pace. GPS, SCADA systems, Industrial Control Systems (ICS), security systems, traffic signaling systems, operational control and monitoring systems connected via wires and wirelessly are critical to successful and safe tunnel projects and operations. While this rapid technology infusion facilitates significant efficiencies, provides enormous amounts of data and enhances safety, it also adds new challenges. Today, there are new safety and economic risks on the job site created by cyber security vulnerabilities associated with the proliferation and integration of technology. The hazards and risks created must be addressed and understood. This paper presents the scope of the challenges faced, identifies examples of cyber security vulnerabilities on the job site during construction as well as once operational and in service. Concluding discussions will address and discuss remediation/mitigation strategies and best practices.

Design Track - Resiliency

Chair: D. Dobson, Barnard, Bozeman, MT

Co-chair: M. Brethel, Cowi, Sterling, VA

In-situ Fire Test for the Design of Passive Protection for the Lafontaine Tunnel
J. Habimana; Hatch, Montreal, Quebec, Canada, J. Bienefelt; Efectis, Amsterdam, Netherlands and R. Showbary; Efectis, Amsterdam, Netherlands

The Ministère des Transports, de la Mobilité durable et de l'Électrification des Transports (Quebec Ministry of Transportation) is planning to undertake major safety upgrade and rehabilitation work on the Louis - H. La Fontaine Tunnel to prolong its lifespan and to comply with current codes, standards and best practices in fire life safety as well as emergency egress in case of a major fire event. The tunnel, which is approximately 1 mile long, is one of the main links between Montreal and the City of the Longueuil and is heavily trafficked by cars and trucks as it serves the nearby Port of Montreal. The paper focuses on in-situ fire tests that were carried out in the tunnel in summer 2016 and on how the results of the tests were incorporated into the requirement for the design of the passive protection to maintain its structural integrity during a major fire event in the tunnel.

Preliminary Assessment – Rehabilitation and Expansion of the Central City Tunnel System in Minneapolis, MN
G. Sanders; CDM Smith, Kansas City, MO, M. Gilbert and M. Khwaja; CMD Smith, Boston, MA, and B. Lueck; CDM Smith, Minneapolis, MN

The tunnels of the Central City Tunnel System in downtown Minneapolis, MN, were, primarily, excavated between 1935 and 1940. The City’s growth and increased paved areas are channeling additional flows to the, now, undersized system, resulting in unintended system pressurization and extensive maintenance. This paper focuses on the technical aspects of the preliminary design, and the design challenges faced to enhance and expand the tunnel system capacity. One of the key decisions addressed during the preliminary design is the choice between expanding the existing tunnel cross section or constructing new tunnels parallel to the existing storm main tunnels. Preliminary engineering effort focusing on an integrated hydraulic modelling and tunnel design/construction approach are presented. Project geology is also captured, emphasizing the unique features of St. Peter Sandstone, highlighting the challenges it creates for design and construction.

Recent Passive Fire Protection Strategies for the US Highway Tunnels
W. Chen; Jacobs Engineering, Boston, MA

Tunnel structure fire protection strategy for the US highway tunnel is inconsistent. The National Fire Protection Association 502 (NFPA-502) technical committee provided its first tunnel structure fire protection clause in 2004. Since then, it has made several updates for this clause. The trend of these updates is to replace prescriptive requirements with performance based requirements. This paper reviews these requirements in chronological order; and examines the use of the requirements in three US highway tunnels constructed in the last decade. From the literature review and the case studies, this paper explains why the tunnel structural fire protection strategy for the US highway tunnels is inconsistent, provides recommended practice, and offers suggested revisions for NFPA-502’s consideration.

The Use of Numerical Analysis in Rehabilitation of Baltimore Howard Street Tunnel
S. Rashidi; AECOM, Piscataway, NJ, V. Nasri; AECOM, New York, NY, R. Humbert; AECOM and M. Hoey, CSX

This paper discusses the use of numerical modeling for optimization of tunnel rehabilitation scheme to improve the clearance of the Howard Street Tunnel in Baltimore, MD. With a total length of approximately 8,700 feet, the Howard Street Tunnel consists of three sections: concrete box section, original cut-and-cover section, and original mined section. The Howard Street Tunnel currently has a minimum vertical clearance of 19’-4� but a vertical clearance of 21’-0� should be achieved by lowering the track profile and/or structural modifications. Finite element modeling was used to determine the maximum allowable depth of cut in the brick arch at the cut-and-cover and mined sections of the tunnel. The results of these analyses allowed the designers to formulate a cost-effective solution which minimized the risk of compromising the structural integrity of the tunnel.

Evaluation of a Segmental Tunnel Lining Response to a Strike Slip Fault Rupture
A. Del Amo; Aldea Services, Markham, Ontario, Canada, K. Braun; L-7 Services, Golden, CO, R. Goodfellow; Aldea Services, Frederick, MD, M. Awad; Aldea Services, Springfield, VA and B. Yang, Aldea Services, Columbus, OH

Several underground projects in seismic areas are currently dealing with active fault crossings, in such locations the tunnel lining performance is a key element for the project’s success. This paper describes various special tunnel lining systems that could be designed to accommodate the imposed displacements on the tunnels due to the risk of a strike slip fault rupture when moderate movements are anticipated. It also emphasizes the lining response in oblique crossings compared to perpendicular crossings. Numerical analyses included advanced three-dimensional numerical models and special structural details. Finally, it provides recommendations to improve the tunnel performance during a fault movement.

Planning Track -Risk Management Challenges & Solutions

Chair: S. Lotti, Frontier Kemper, New Hyde Park, NY

Co-chair: R. Capka, Sound Transit, Seattle, WA

CEVP-RIAAT Process - Application of an Integrated Cost and Schedule Analysis
P. Sander; RiskConsult, Innsbruck, Austria, J. Reilly; John Reilly International, Framingham, MA and M. Entacher, RiskConsult, Innsbruck, Austria

Key processes necessary to identify and manage risks on complex tunneling projects have been developed over the last 20 years in order to implement risk-based approaches for better cost and schedule estimation. Cost and schedule, however, were mostly treated separately instead of integrating them in one model. This integration is highly relevant as schedule delays are very often the root cause for severe cost overruns. This paper presents a fully-integrated probabilistic cost and schedule model. The application is based on combination of two practice-proven approaches - the Cost Estimation and Validation Process CEVP® (Reilly et. al. 2004/Washington State Department of Transportation) and the RIAAT (Risk Administration and Analysis Tool), creating a powerful tool for management of complex risk environments.

Freezing of Glacial Soils for Cross Passage Construction in North America and Europe – A Comparison
U. Gwildis; CDM Smith, Bellevue, Washington, H. Hass; CDM Smith, Bochum, Germany and M. Schultz and M. Khwaja; CDM Smith, Boston, Massachusetts

Ground freezing is a temporary ground improvement method used for underground excavations such as cross passages between subway tubes. The versatility of the method – freeze pipes can be installed at varying angles from the ground surface and from within the tunnels – allows its use under restricting conditions when other methods are not feasible. Design and execution approaches vary widely. This paper compares two recent cross passage construction projects in glacial geology – the Northgate Link light rail extension in Seattle and the Slowacki Tunnel in Gdansk – and draws comparisons from the application of ground freezing technology in North America and Europe.

Unique Design and Construction Challenges for Near-Surface Large-Span Transit Station Caverns in Rock
C. Stone and E. Wang; HNTB Corporation, New York, NY

Continued growing demand for convenient access to prime locations in dense urban centers focuses the need for new transit station caverns within infrastructure and ground conditions presenting unique construction challenges. Paper highlights key principles and considerations for design of near-surface large-span mined caverns in rock, including entrances and shafts. Evaluation and mitigation strategies for the protection of adjacent and overlying infrastructure are shared. Practical examples from the authors’ past experiences on Ohio River Bridges, Number 7 Subway Line Extension, Trans-Hudson Express Tunnel, East Side Access and Second Avenue Subway in New York are presented, and representative completed station caverns.

Bergen Point WWTP Outfall Tunnel Shafts- Risk Mitigated Design for Excavation Support
M. Khwaja; CDM Smith, Waban MA, M. Schultz; CDM Smith, Boston, MA and J. Donovan, Suffolk County Department of Public Works, Yaphank, NY

Responsibility for shaft construction method selection generally lies with the contractor. Project specific logistics and site challenges for the Bergen Point WWTP tunnel shafts, and the need to mitigate risk to project cost and schedule, necessitated detailed evaluation during design for excavation support options for launching and receiving shafts. The contract documents were left somewhat flexible for the receiving shaft, but the contract documents are prescriptive for the launching shaft. A brief description on the decision-making process leading to contract document preparation is provided along with the design considerations for both shafts is presented. A detailed review of hydrogeologic conditions and ground freezing design parameter requirements and tests is presented and the approach used in risk mitigation and finalizing the contract documents is discussed.

Bart Silicon Valley (BSV) Phase II, Tunneling Methodology – Comparative Analysis Independent Risk Assessment
S. Saki; Aldea Services, Frederick, MD, J. Brady; Aldea Services, Decatur, GA, R. Goodfellow; Aldea Services, Frederick, MD, A. Del Amo; Aldea Services, Markham, Ontario, Canada, A. Moergeli; Moergeli Consulting, LLC, Los Angeles, CA and K. Davey; Santa Clara Valley Transportation Authority, Milpitas, CA

A risk analysis approach can be used to compare the viability of two competing tunneling options even at different levels of design maturity. This paper describes the process used to provide the Santa Clara Valley Transportation Authority (VTA) with a comprehensive decision-making basis using comparative risk profiles for two tunneling alternatives; a single large diameter tunnel versus two smaller twin tunnels for extending BART service into downtown San Jose. Quantification of construction risk impacts were assessed in terms of cost and time for comparing the subsurface construction cost and duration of the two options. The analysis also compared the differences in O&M costs for the first 30 years of operation.

Case Histories Track - Sewer/Water I

Chair: B. DiFiore, Mott MacDonald, Chicago, IL

Co-chair: B. Harris, Drill Tech, Livermore, CA

A Case Study of Risk Mitigation Measures on the West End Trunk Line Microtunnel
A. Prieto; Mott MacDonald, New York, NY, R. Ball; Mott MacDonald, Cleveland, OH, J. Marie; Mott MacDonald and G. DeBalko; Pennsylvania American Water

Risk mitigation measures adopted in the design and construction of a 1,050-linear foot microtunnel segment (59-inch casing pipe, 30-inch carrier pipe) of the overall 16,200 linear foot West End Trunk Line Project proved successful. As subsurface conditions created challenges during the microtunnel boring machine’s (MTBM) mining process, the design and construction management approaches were implemented and validated. The paper discusses how the challenges were overcome, including the MTBM becoming wedged within the excavation, very slow periods of excavation advance rate and unexpectedly high thrust loads as compared to the calculated values.

High Capacity Hoisting At Rondout West Branch Tunnel Project
D. Brennan; Kiewit Infrastructure, Lancaster, PA and D. Brennan; Kiewit Infrastructure, Marietta, GA

New York City Department of Environmental Protection (NYCDEP) is currently completing the repair of an existing water tunnel feed to the City of New York. The repair involves the construction of a by-pass to the existing tunnel. The depth of the new work and the type of equipment and materials required that the construction team revisit the traditional approach to shaft servicing. This paper will discuss the hoisting systems used at Shaft 5B Rondout West Branch Bypass Tunnel project near the City of Newburgh, New York. The shaft hoisting equipment was designed to handle the initial drill and shoot and the tunnel boring machine muck removal as well as the supply of all construction equipment including concrete segments and 40 foot sections of steel interliner pipe. Personnel were also transported from the surface to the foot of shaft located approximately 900 feet below. The hoisting equipment consisted of a total of 14 separate hoists and winches with a total of over 3,800 horsepower. The main muck and supply hoist consists of a double drum, variable frequency drive unit running at 1,100 feet per minute with a line pull of 62,210 pounds.

Boring Hard, Abrasive Gneiss with a Main Beam TBM at the Atlanta Water Supply Program
T. Fuerst; Robbins, Solon, OH and D. Del Nero; Stantec, Atlanta, GA

Atlanta, Georgia’s water supply program is a priority project involving a 5.0-mile long tunnel connecting up with the Chattahoochee River, which will establish an emergency water supply for the city. A 12.5 ft diameter Main Beam TBM is boring the area’s deepest tunnel through hard, abrasive Gneiss rock at rates of up to 100 ft per day. This paper will examine the project specifics and design, as well as the performance of the TBM. It will then draw conclusions as to the optimal TBM design for excavation in the area’s exceedingly hard geology based on this project and past projects in the area.

World’s Largest Tunnel Gates and Reservoir Connection Go Online as part of Chicago’s Tunnel and Reservoir Plan (TARP)
M. Sanchez and F. Oksuz; Black & Veatch, Chicago, IL, M. Padilla and D. Schiemann; U.S. Army Corps of Engineers, Chicago District, Chicago, IL, P. Jensen and C. Scalise; Metropolitan Water Reclamation District of Greater Chicago, Chicago, IL and M. Trotter; Kiewit Infrastructure Company, Omaha, NE

Chicago’s Tunnel and Reservoir Plan (TARP) is a nearly $4.0 billion and over 30-year long program and arguably the largest and longest combined sewer tunnel and reservoir system in the world. The McCook Main Tunnel construction and gates installation is now complete for connection of the McCook Reservoir to the existing TARP Mainstream tunnel system. This paper describes the overall project and the final stages of commissioning including installation and operation of world’s largest underground roller (or wheel) gates for flow control within the bifurcated tunnel sections that operate under 92 meters (300 feet) of water pressure.

Establishing Access Into Chicago’s Main Stream Tunnel Under Live CSO Flow
L. Dubaj, Omaha, NE

The McCook Reservoir Main Tunnel System Project includes a 1600’ long, 33’ diameter tunnel connecting the McCook Reservoir to the existing Mainstream Tunnel (MST) which is part of Chicago Metropolitan Water Reclamation District’s (MWRD) Tunnel and Reservoir Plan (TARP). This paper focuses on establishing access between the two tunnels during live CSO flows in order to complete construction. Establishing access to the live tie in included the installation of a temporary access platform, installation of temporary bulkheads at the upstream and downstream ends of the MST along with the assembly and finally installation of a 36� HDPE pipe that would allow up to 42 million gallons of CSO water to flow to the nearby water treatment plant while allowing to safety perform the tunnel tie-in.

Monday, June 25, 2018 | 1:30 PM

Technology Track - Innovation

Chair: B. Downing, Golder Associates, Vancouver, BC, Canada

Co-Chair: P. Headland, Aldea Services, Frederick, MD

A Preliminary Investigation for Characterization and Modeling of Structurally Controlled Underground Limestone Mines by Integrating Laser Scanning with Discrete Element Modeling
J. Monsalve, J. Baggett, R. Bishop and N. Ripepi; Virginia Polytechnic Institute and State University, Blacksburg, VA

Stability of large opening underground excavations in jointed rock masses primarily depends on the distribution and properties of the geological discontinuities. Conventional methods for structural mapping may not be optimal for rock mass characterization. Laser scanning is a technology that rapidly sends out laser pulses in order to measure the position of certain objects by generating a massive point cloud with millimeter precision. This paper reviews the application of laser scanning along with discrete element method (DEM) modelling, to produce a more realistic response of the rock mass behavior during excavation compared to analytical approaches. Additionally, a methodology to evaluate the stability in a structurally controlled underground limestone mine with these two technologies is proposed.

Study of the Correlation between RMR and TBM Downtimes
O. Frough and J. Rostami; Colorado School of Mines, Golden, CO and R. Torabi; Shahrood University of Technology, Shahroud, Iran

In Mechanized tunneling, machine performance is very sensitive to ground conditions and can be substantially impacted by variations in rock type, strength, jointing, and rock mass classes. Adverse ground conditions have a great impact on TBM downtimes and can considerably reduce the machine utilization. In this paper, the influence of rock mass properties on machine downtimes were examined. Data from three long mechanized tunnels recently completed by D.B. TBM was used to evaluate the relation between engineering geology information and daily machine utilization and downtime. Various regression equations were developed to offer empirical models for estimation of machine utilization and RMR. Results showed that the relationship between RMR and rock mass related downtimes can reach correlation coefficient (R2) of 0.62.

Cross Passage Construction: Mechanized Solutions and Fields of Application
G. Lang; Herrenknecht AG, Allmannsweier, Germa

With the growing world population and the rising transport volume, intelligent underground tunnel solutions become a necessity. At the same time, safety is becoming an increasingly important aspect in planning of these infrastructures. One of the measures in discussion is the construction of cross passages, mostly between parallel tunnels. In general, these tunnels are very short but their construction can be highly demanding, especially in poor ground conditions, and can have a big impact on the overall program. Various concepts have been worked out in relation to tunnel size, geology and hydrology. Cross passages in water-bearing ground with high water pressure are a special challenge. In the past, this could often only be realized with the help of ground freezing methods or with extensive grouting and consolidation measures. Mechanized approaches have been completed successfully in the past driven by the new increased demand, TBMs for cross passages are now discussed more often as a real alternative to save time and cost.

Communications, Tracking, Vehicle Telemetry and Proximity Solutions
G. Perez Manfredini; MST Global, Golden, CO

As with TBM and other tunneling machines, communication technologies have evolved significantly over the last few years. With today’s digital technologies, safety is enhanced by means of personnel tracking and location, electronic access control, vehicle proximity detection, video transmission, gas monitoring, and most importantly the people connection. Any person underground can now be connected to the world, get internet, and send an immediate emergency alarm wherever they are underground via mobile phones Digital technology increases productivity in tunnel projects. Thanks to Wi-Fi platforms, applications like ventilation on demand, vehicle tracking, TBM data transfer (excavation parameters), cutterhead interventions, geotechnical information and so on, can assist with project management, reduce construction costs, and achieve improved quality and production rates. In tunnels with a diameter of less than 5 meters, where TBMs tend to be longer, the Leaky-Wi-Fi technology lays as the best technical solution to overcome the challenge of propagating the Wi-Fi signal through the TBM.In the present day, there is no reason why someone should be in a tunnel without full access to modern means of communication. Everyone has the right to be connected, monitored, and protected, especially when working in an underground environment.

Underground Communication Innovations
J. Jarrett, E. Hansen, S. Harrison; Innovative Wireless Technologies, Lynchburg, VA

Tunnels are rugged environments with large moving equipment, explosives and hazards including water, dust and gas. To date, there are few underground communication and tracking systems available for tunnel projects that support OSHA (Occupational Safety and Health Administration) compliance. After the 2006 Sago Mine disaster, research and development was performed to improve communication systems for the underground environment. Today, over 250 US mines utilize these new technologies to improve productivity, reduce costs and enhance safety. This paper explores these new technologies and provides guidance for planners through the process of selecting a tunnel communication solution. It reviews the key requirements and constraints for consideration and provides an overview of various communication and networking technologies and discusses their strengths and weaknesses.

SCMAGLEV Project – Fast and Innovative Mode of Transportation in the Northeast Corridor
V. Gall, S. Pyakurel and N. Syrtariotis; Gall Zeidler Consultants, Ashburn, VA, C. Crawford and L. Sfintescu; Louis Berger, Morrison, NJ and D. Henley; Northeast Maglev, Washington, DC

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. The system operates using an electromagnetic levitation system developed and deployed in Japan that achieves an operating speed of 500km/h (311 mph). SCMAGLEV is a technically challenging but innovative project that will shorten travel times between Washington D.C. and Baltimore to 15 minutes, and eventually cover Washington to New York City in an hour. The project will enhance mobility along the Northeast Corridor (NEC) and spur development and economic growth in the region. This paper provides an overview of the SCMAGLEV project and discusses construction of the tunnel and elevated sections.

Design Track - Sequential Excavation Methods

Chair: B. Dean, Frontier Kemper, Evansville, IN

Co-chair: M. Leong, McMillen Jacobs, San Francisco, CA

Design and Construction Challenges in Urban Settings for the NATM Tunnels Line 2 of the RIYADH Metro
S. Pyakurel; Gall Zeidler Consultants, Ashburn, VA, K. Zeidler and A. Gerstgrasser; Gall Zeidler Consultants, Croydon Surrey, UK and I. Thompson; Bechtel

The Riyadh Metro Project entails the construction of six new lines. ArRiyadh Development Authority, the executive arm of the High Commission for the Development of Arriyadh contracted BACS consortium to design and build Lines 1 and 2; Gall Zeidler Consultants designed mined tunnels which are sections of the tunnels for the Lines 1 and 2 including emergency egress shafts and connection adits. This paper describes design and construction of Line 2 mined tunnels in an urban settings including challenges encountered during excavation in close proximity to the building foundations, piers and methods to control inflow of groundwater in ground conditions varying from disturbed brecciated to fresh intact limestone.

Downtown Bellevue Tunnel- Analysis and Design of SEM Optimization
C. Brodbaek and D. Penrice; Mott MacDonald, Pleasanton, CA, J. Coibion; Guy F. Atkinson Construction, Renton, WA and C. Frederick; Sound Transit; Bellevue, WA

The Downtown Bellevue Tunnel (DBT) is part of Sound Transit’s $3.7 billion light rail extension connecting Seattle with the cities of Bellevue and Redmond. In December of 2015 Atkinson Construction was awarded the DBT construction contract, which includes a 1,985 foot long, 38 foot wide Sequentially Excavated (SEM) tunnel. As part of a subsequent construction schedule reduction effort, in areas with favorable ground conditions Atkinson proposed that the excavation of the SEM tunnel be revised from six to three headings. To validate the optimized excavation sequence, three-dimensional numerical modeling was required to demonstrate its safety and reliability. This paper describes the numerical modeling—addressing initial liner design, ground deformations and three-dimensional excavation stability—and compares analysis results with construction field measurements and observations.

Elasto-Plastic Design of Fiber Reinforced Concrete Tunnel Linings
A. Nitschke, WSP USA, Washington, DC

The most advantageous property of Fiber Reinforced Concrete (FRC) is its toughness, changing the failure mode of concrete from brittle to elasto-plastic. In the plastic stage, the FRC tunnel lining effectively softens, which allows load re-distribution within the structure and consequentially increasing its ultimate load-bearing-capacity. However, to take full structural and economic advantage of this effect, the lining design’s focus should shift from a “strength� perspective to a “deformation� perspective respectively from a design concept based on “cross-section�-failure to design concept based on “system�-failure. The paper discusses the load bearing behavior of FRC in tunnel linings under combined moment-normalforce loading. Based on the findings, options for elasto-plastic failure-mode design of FRC tunnel linings, plastic hinges, and the paradigm shift that is required to take full structural and economic advantages of FRC for tunnel linings.

Ground-Liner Interaction during Seattle Northgate Link Cross-Passage Construction
T. Epel, M. Mooney and M. Gutierrez; Colorado School of Mines, Golden, CO, K. Braun; L-7 Services LLC, Golden, CO, M. DiPonio, Jay Dee Contractors, Inc., Livermore, MI and N. Long, Jay Dee Contractors, Inc., Seattle, WA

This paper presents the results and analysis of field measurements to characterize ground-liner interaction and the development of thrust force and bending moment in segments adjacent to openings during cross passage construction. The instrumentation and data collection of segment strain measurements during cross passage construction made possible by embedded wireless sensors enables a complete picture of thrust-moment evolution and ground-liner interaction. The results show how different excavation and construction activates load the cross passage opening and the contribution of different supporting elements.

Design and Construction of the Downtown Bellevue Tunnel
M. Wongkaew; The Boring Company, Hawthorne, CA, M. Murray; Mott MacDonald, Bellevue, WA, J. Coibion; Guy F. Atkinson Construction, Renton, WA, C. Frederick; Sound Transit, Bellevue, WA and M. Leong; McMillen Jacobs Associates, San Francisco, CA

Construction of Sound Transit’s East Link light rail tunnel using the Sequential Excavation Method (SEM) is well underway in downtown Bellevue, Washington. This paper describes the design and construction to date of the 2,000-foot long, 38-foot wide soft ground tunnel including refinements adopted in a collaborative team environment. These include the change from a six-heading to a three-heading excavation sequence, reduction of prescribed pre-support and face support, and changes in shotcrete supply and equipment. Productivity analyses are provided to illustrate these benefits. The paper also discusses the instrumentation program and the testing program to practically confirm shotcrete early strengths in the field.

The Influence of Material Models for the Effective Design of the Primary Lining
M. BakoÅ¡, J. Ortuta and P. PaloÄ?ko; Amberg Engineering Slovakia, Bratislava, Slovakia

The finite element method made a significant impact of static assessment of tunnel primary lining. The Mohr – Coulomb model is a widely used model. However, this model is not economically optimal. Designer can use other material models which are more suitable for rock environment resulting in more economical design. Tunnel Soroška is designed as 4.2 km long road tunnel in karst rock. One tunnel tube for both directions will be built in the first phase. The construction had an interesting result during the calculation of primary lining. The article presents a summary of geotechnical inputs for the efficient selection of the material models and a method of optimizing the calculation that takes the economic and environmental aspects of the design work into account.

Shallow Cover SEM Tunneling for the Purple Line Project
D. Watson, P. Lloyd and R. Villarreal; Mott MacDonald, New York, NY and R. Taylor; Traylor Brothers, Alexandria, VA

The Plymouth Tunnel is part of the 16.2-mile, 21-station, east-west, Light Rail Transit (LRT) Purple Line Project undertaken by the Maryland Transit Administration (MTA). With an overall length of 1220-feet, the tunnel comprises only a short section of the line. The tunnel follows a relatively shallow vertical alignment with a maximum depth of cover above the tunnel crown of approximately 40-feet, and to a minimum of approximately 15-feet at the portals. The overburden material consists of soils, disintegrated and decomposed highly weathered rock traversing under a residential area. The groundwater table is located above the tunnel crown along most of the tunnel alignment. The ground surface topography above the tunnel alignment forms a hill like promontory that drains the groundwater towards two creeks to the north and south of the alignment. This paper will discuss present the ground conditions, the design approach and constructability considerations for the tunnel.

Planning Track - Project Delivery -Water & Wastewater

Chair: M. Burnson, DSI Underground, Louisville, KY

Co-chair: N. Nuttbrock, Brierley, Houston, TX

DigIndy Tunnel System Pleasant Run Deep Tunnel Optimization
O. Hawbaker; Citizens Energy Group, Indianapolis, IN, M. Lewis and L. Gentile; Black Veatch, Indianapolis, IN

The Pleasant Run Deep Tunnel is a 39,000-foot long component of the 28-mile long DigIndy deep rock tunnel system, the cornerstone of Citizens Energy Group’s Long Term Control Plan (LTCP). Final planning optimized the conceptual design to achieve CSO capture objectives while eliminating expensive components and saving millions of dollars. After the elimination of several drop shafts originally planned, the final design included relocating drop shaft locations. The relocations were due to outreach with city stakeholders and included intermediate shaft relocation due to new major developments at the site. The relocations required the design team to revisit the optimization of the of the tunnel alignment to maintain minimized adit and consolidation sewer lengths.

Planning, Design and Construction of CSO Pumping Stations Structures
G. Hughes; JCK Underground Inc., Gibsonia, PA, R. Castro; JCK Underground Inc., Winchester, MA, C. Ray, M. Wone and R. Bizzarri; DC Water, Washington, DC and J. Cassidy; Greeley and Hansen, LLC

During the early stages of many Combined Sewer Overflow (CSO) tunnel programs, Owners are required to make critical decisions related to the configuration of underground structures to house dewatering pump systems. Key considerations may include siting, sequence of work, schedule, operational capacity, design criteria, constructability and contract packaging. Several of these items were addressed when building a 250 million gallons per day (MGD) pumping station within a 132-foot diameter by 175-foot deep shaft for DC Water’s DC Clean Rivers Project. This paper discusses the planning of underground structures for pumping stations in general terms and provides examples from the DCCR Project to demonstrate how active, flexible program management was used to overcome challenges and achieve a successful project execution.

Emerging Demand for Subsea Tunnels in Chile
V. Figueroa and N. Zegpi; SKAVA Consulting S.A, Santiago, Chile

Chile has an economy that strongly depends on natural resources, mainly mining and agriculture. Water is a strategic asset for the latter. Considering the water strategic economic value and that due to drought, aquifer and reservoir depletion, water supply reliability has become a permanent problem in the country’s most productive regions. The mining sector alone has planned for at least 19 projects using seawater in their processes. Considering the geological and tectonic context of Chilean coastline, these projects face significant difficulties. That is why subsea tunnels for intakes and outfalls are part of the solution to this challenge. This paper describes Chilean water context and design and constructability approaches for three different cases.

Implementing Major CSO Solutions via Deep Rock Tunneling -Louisville Ohio River Tunnel (ORT)
J. Steflik; Black & Veatch, Louisville, KY, J. Mathis and G. Powell; Louisville and Jefferson County Metropolitan Sewer District, Louisville, KY, A. Westermann; Black Veatch, Louisville, KY, D. Ginn; Black & Veatch, Indianapolis, IN and T. Wanless, Black & Veatch, Overland Park, KS

Louisville and Jefferson County Metropolitan Sewer District (MSD) will complete their Long Term Control Plan, part of an $850 million 20-year Integrated Overflow Abatement Plan (IOAP) by December 2020 to reduce combined sewer overflows (CSOs). Originally scoped as three separate CSO basin projects, the Ohio River Tunnel (ORT) was developed in response to challenges encountered throughout design and now involves construction of a deep rock tunnel with a capacity of approximately 37 million gallons. This paper discusses the challenges involved in completing the design of the ORT Tunnel and Shafts contract package on an accelerated 8-month schedule. The design phase for the basins was originally planned for approximately two years, but was compressed due to evolving design requirements for three CSO storage basins. The schedule will allow adequate construction time to meet MSD’s consent decree deadline. Key project elements include a 2.5-mile long, 20-foot finished diameter deep rock tunnel, four drop structures to convey consolidation flows to the tunnel, downstream pump station shaft, and adits connecting drop shafts to the tunnel in downtown Louisville.

Narragansett Bay Commission Phase III CSO Abatement Program – Pawtucket Tunnel
T. Moline; MWH Constructors, Providence, RI, C.Feeney; Stantec, Providence, RI and K. Kelly; Narragansett Bay Commission, Providence, RI

The Narragansett Bay Commission (NBC) operates collection and treatment facilities in two service areas in Rhode Island. In 1992, NBC began a three-phase Combined Sewer Overflow (CSO) Abatement Program to reduce untreated CSO discharges to Narragansett Bay. Phases I and II of the Program included construction of a 16,500-ft, 26-ft diameter rock storage tunnel and cavern pump station. Phase III will include construction of a second deep, rock storage tunnel (13,000-ft, 28-ft diameter), drop shafts, and a cavern pump station. This paper presents planning and optimization of Phase III construction utilizing data and case studies from Phases I and II construction.

Ship Canal Water Quality Project: Meeting Federal Requirements
S. Goff and G. Davidson; McMillen Jacobs Associates, Seattle, WA and D. Menes; Seattle Public Utilities, Seattle, WA

The Ship Canal Water Quality Project will control combined sewer overflows (CSOs) from seven basins in Seattle, WA. Both the City of Seattle and King County have federal EPA Consent Decrees with which this project must comply by 2025. Following an extensive options evaluation, the preferred option selected jointly by both agencies was to build a tunnel to convey and store excess flows from their associated basins. Design of the project’s tunnel and pump station elements commenced in 2015. This paper presents the development of the Storage Tunnel design to date, some of the challenges encountered during the design phase, an overview of the coordination between the various design-bid-build contracts and the current project status and schedule.

The Coxwell Bypass Tunnel, Cleaning up Toronto’s Waterfront
D. Cressman, O. Cantina, and D. Day; Black & Veatch, Toronto, Ontario, Canada and S. Fraser, R. Mayberry, and C. Kaars Sijpesteijn; City of Toronto, Toronto, Ontario, Canada

The City of Toronto is currently undertaking the detailed design of the Coxwell Bypass Tunnel (CBT); tendering for construction was initiated in 2017. The CBT represents the first stage of the Don River and Central Waterfront (DR&CW) Project, a long-term project designed to reduce combined sewer overflows (CSOs) and clean up the Inner Harbour of Lake Ontario, the Don River, and Taylor-Massey Creek. This paper outlines the scope of the CBT and provides context to its purpose in the larger $2 billion DR&CW Project. The CBT involves the excavation of 10.5 kilometers of 7.3 meter diameter tunnel through shale rock of the Georgian Bay Formation, five storage shafts, and 11 connection shafts along the alignment of the CBT. An overview of the CBT design and procurement strategy implemented is provided, as well as the risk-based analysis and decision-making process used to specify a shielded rock tunnel boring machine (TBM) with a precast tunnel lining (PCTL) system.

Case Histories Track - Transportation 1

Chair: C. Wilson, Black & Veatch Corp, Columbus, OH

Co-Chair: E. Feigl, Dr Sauer and Partners Corp, Herndon, VA

After the Tunnel Drive, Finishing the Highway to Replace SR 99 Below Seattle
G. Hauser; Dragados USA, Seattle, WA, S. Everett; Washington State Department of Transportation, Seattle, WA and J. Clare; Mott MacDonald, Seattle, WA

The Alaskan Way Viaduct Replacement, Bored Tunnel Project included a 9,270 LF tunnel and construction of a four lane, double decked highway to carry traffic below the City of Seattle Washington. Despite a major two year delay, tunnel mining with the world’s largest earth pressure balance TBM was completed on April 4, 2017 with virtually no impact to surface structures and utilities. This paper will describe major events of tunnel mining leading up to the successful hole through and a description of the work sequence to complete the tunnel interior structures including mechanical, electrical, plumbing, fire and life safety, the communication and support systems to allow service in 2019.

Cross Passage Freezing from the Ground Surface
A. McCain and B. Cook; SoilFreeze, Inc, Woodinville, WA, N. Long; Jay Dee Contractors, Inc., Seattle, WA and L. Applegate, Woodinville, WA

Ground freezing techniques were used to successfully excavate cross-passages that were part of the Sound Transit Northgate Link Extension in Seattle, Washington. In order to keep the tunnels unobstructed during mining operations and minimize in-tunnel freezing equipment, the decision was made to freeze the cross passages from the ground surface. Freezing from the ground surface to support excavation for tunnel cross passages had not occurred in the United States prior to this project. This paper presents the approach taken to navigate the project challenges overcome by freezing from the ground surface to provide stable and watertight shoring for the project.

Lessons Learned in Dry Ground Excavation Using an EPBM
D. Girard; J. F. Shea Construction, Inc., Walnut, CA and R. Chen; J. F. Shea Construction, Inc., Indianapolis, IN

Earth pressure balance (EPB) sensors are mounted in the excavation chamber of an EPB tunnel boring machine (EPBM) to monitor face support pressure. From this location, these sensors do not accurately portray the actual earth pressure in front of the cutterhead when exposed to relatively dry ground conditions. Mining and ground settlement monitoring data show that contact force can be used as an alternative parameter for maintaining sufficient face support pressure in granular soils above the water table. Avoiding unnecessarily high EPB pressures can improve the advance rate and minimize cutterhead wear, improving operational efficiency. Some lessons learned from the Crenshaw project and some suggestions for future projects are presented.

Phase 1 - Second Avenue Subway Project, New York: Light at the End of the Tunnel: Delivering a Mega Project On Schedule while Maintaining Budget
M. Trabold; AECOM, Merrick, NY, R. Giffen; Arup, New York, NY and A. Parikh, AECOM; Freehold, NJ

Phase 1 of the Second Avenue Subway is a $4.5 billion project which opened on schedule for revenue service on January 1, 2017. To complete the project on schedule while maintaining the budget was only achieved by utilizing different strategies with all parties working together to make it happen – owner, designer, construction manager, and contractors. This paper will discuss the design, planning, and then execution of completing such a complex mega project on schedule while maintaining budget. It will cover strategies that were used by the owner, designer and contractors to improve coordination amongst team members, which streamlined review processes, and removed obstacles to complete the project.

North Hollywood Station West Entrance – A Successful Connection of Metro Red Line Subway and Orange Bus Line
T. Vu; VN Tunnel and Underground Inc., Los Angeles, CA, M. Joshi; Los Angeles Metro, Los Angeles, CA, A. Gonzalez; Skanska Civil West, Los Angeles, CA and R. Silos; AECOM, Los Angeles, CA

The North Hollywood Station is currently the final stop of the Los Angeles Metro’s Red Line Heavy Rail subway. Metro’s Orange Line Bus Rapid Transit (BRT) Terminal is located on west side of Lankershim Boulevard across from the North Hollywood Station. Typically, there is a very high volume of patrons transferring from Orange Line Bus to Red Line Train going to Union Station in the mornings and vice versa in the afternoon. The heavy pedestrian traffic crossing Lankershim Boulevard to connect these two lines created a safety hazard for the patrons as well as traffic congestion for the vehicles in the north-south directions. The North Hollywood Station West Entrance was designed to address the above safety and congestion issues by providing a direct underground connection from the station concourse level to the ground surface via a stairway, single escalator, and two elevators. This new 150 feet long, 50 feet wide, and 40 feet deep underground entrance, constructed using cut-and-cover method, also houses ancillary equipment rooms to serve its operation. This paper will discuss in detail the design and construction challenges of this design-build project including: design optimization, deep excavation in a narrow footprint, tight budget and schedule, and connection to the existing structure and system.

Risk Management in Early Subaqueous Transit Tunneling
V. Tirolo; STV Inc., Brooklyn, NY

The management of risk on tunnel projects today is a formal matrix driven process initiated by the insurance industry We assume today when developing a risk matrix most of the risks can be identified. We have this confidence because of the high level of communications within the tunnel industry. However, even today i, we may be unaware of some potential risks. Consider subaqueous tunneling in middle to late 19th and early 20th Century. Few subaqueous tunnels had been built, experience was very limited, and there were no tunneling organizations or conferences. How did tunnel engineers of that era assess risk with little or no case history information? How did they entice government and private interests into funding such high risk enterprises? We will explore three areas where these early practitioners were able to build confidence of both business and government in these high risks enterprises. The experience and management of risk on subaqueous tunnels that began in the 1860s resulted in a boom for the industry that continues today.

Shallow SEM Tunneling under Major Roadways and through Active Landslides in Edmonton Glacial Tills
J. Kuyt, M. El Khattab and E. Almog; Arup, New York, NY, K. Sullivan; Bechtel, Edmonton, Alberta, Canada and I. Cisyk; EllisDon, Edmonton, Alberta, Canada

The Edmonton Valley Line LRT is a $1.8bn(CAD) 13km light rail project connecting downtown Edmonton to Mill Woods. The scheme includes a 450m section of twin bore 7m diameter mined tunnels between the downtown surface stations and the signature bridge crossing over the North Saskatchewan River and valley. This paper addresses the technical project challenges, including shallow excavation underneath Jasper Ave with 3m cover, management of face stability and groundwater inflows from intra-till sand lenses, and accommodating active landslide movements on Grierson Hill. Challenges were addressed through use of advanced soil structure interaction numerical modeling, spiles and canopy pipes for pre-support in glacial tills, and instrumentation and monitoring response plans to address changing ground conditions with contingency support measures.

Tuesday, June 26, 2018 | 8:30 AM

Technology Track - TBM Technology 1

Chair: J. Criss, Kenny Construction

Co-chair: T. Moon, HNTB

Downtime Data Collection, Analysis and Utilization on Blacklick Creek Sanitary Interceptor Sewer Tunneling Project in Columbus, OH
A. Kerr and M. Ross; Michels Corporation, Columbus, OH

Budgetary and schedule related success in tunneling projects are often directly related to maximizing Tunnel Boring Machine (TBM) availability. This can be accomplished by increasing the amount of time spent on tunneling production, while utilizing resources to avoid known causes of downtime. It is very likely to encounter unforeseen conditions in tunneling, therefore preventable factors should be controlled as much as possible to maximize performance. The examination of opportunities to reduce downtime creates a potential for significant cost savings applicable to other tunneling operations. This paper will discuss the downtime analysis performed on the 3.7 meters (12 feet) diameter Herrenknecht Earth Pressure Balance (EPB) TBM used for the excavation of the Blacklick Creek Sanitary Interceptor Sewer Project in Columbus, OH.

EPB TBM Performance Prediction on the University Link U230 Project
M. Mooney, H. Yu, S. Mokhtari, X. Zhang and X. Zhou; Colorado School of Mines, Golden, CO, E. Alavi and L. Smiley; Jay Dee Contractors, Inc., Livonia, MI and W. Hodder; Jay Dee Contractors, Seattle, WA

There has been significant effort over more than 20 years to predict advance or penetration rates of hard rock TBMs, but very little effort (and no publications) on advance rates of soft ground pressurized face EPB or slurry TBMs. This is due to the complexity that the pressurized excavation chamber and screw conveyor or slurry transport material discharge creates. This paper tackles EPB TBM performance prediction by considering the process of soft ground excavation and by learning from real project data, specifically using the Seattle University Link U230 tunnel project data.

Interpretation of EPB TBM Graphical Data
K. Rafie; Stantec, Toronto, Ontario, Canada

Tunnel construction using a tunnel boring machine (TBM) involves a highly complex operation. Such processes generate large amounts of data that can be used for monitoring, reporting and analysis. Major TBM manufacturers have developed software systems to support tunnel contractors and their site teams in both data management and analysis. These programs are mostly web-based and have many advantages. Data acquisition cannot prevent breakdowns from occurring but can facilitate forensic investigations to quickly determine the root cause of a breakdown and provide basis for implementing corrective actions. This paper analyzes these data acquisition tools and presents case studies, primarily involving earth pressure balance (EPB) TBMs, to illustrate how the formation of critical interpretations can be made from user-defined charts and diagrams to diagnose issues and optimize TBM operational parameters.

TBM Procurement – Owner’s Dilemma
D. Ifrim and D. Zoldy; Hatch Corporation, Kleinburg, Ontario, Canada

Tunnelling is a unique and challenging industry. This paper will discuss the importance in understanding technological innovations in the current TBM manufacturing market and provides suggestions for procurement options in design-bid-build and design-build project delivery approaches. The objective of the paper is to open a discussion within the industry with the goal of invoking forwarding thinking to improve Tunnel Boring Machine (TBM) specification language in contract documents.

TBM Tool Wear Analysis for Cutterhead Configuration and Resource Planning in Glacial Geology
U. Gwildis; CDM Smith, Bellevue, Washington, K. Mosavat; The Robbins Company, Kent, Washington, J. Aguilar; CDM Smith, Burnaby, British Columbia, Canada

The abrasive nature of glacial geology generally results in Tunnel Boring Machine (TBM) cutting tool inspection and replacement needs that may require hyperbaric interventions and are a cost and risk factor. Correlation analysis of geotechnical conditions, TBM operational parameters, and tool wear measurements is a proven way to gain insight into the wear system behavior. This paper presents findings from various TBM drives in the Seattle and Vancouver, B.C. metropolitan areas on the performance of disc cutters and ripper-type tools in glacial and inter-glacial deposits. The authors provide recommendations for cutterhead configurations, tool management strategies, and the use of monitoring technology.

The EPB Chamber Air Bubble: What Causes It?
Y. Wu, A. Nazem and M. Mooney; Colorado School of Mines. Golden, CO

Contractors persistently deal with an air bubble in the chamber during EPB tunneling; however, the cause of this is unclear. This paper addresses this problem through a series of unique mixing tests coupled with the study of foam-soil interaction at the bubble and soil grain level. Testing reveals that foam is very stable when properly mixed with soil. Soil water content and foam injection ratio play important roles in influencing bubble migration from conditioned soil. The foam-soil mixing test results suggest that the shearing action of mixing tools creates a pathway for bubble migration. These results suggest that soil conditioning parameters, excavated soil properties, and pressure conditions in the EPB chamber should be all considered in design to eliminate the air bubble in the EPB TBM chamber.

Design Track - Rock Tunneling

Chair: D. Willis, The Robbins Co, Kent, WA

Co-Chair: C. Scalise, MWRD Chicago, Chicago, IL

Design and Construction of South Hartford Conveyance and Storage Tunnel
V. Nasri; AECOM, New York, NY, J. Sullivan; AECOM, Hartford, CT, V. Prestia; Kenny Construction Company, Hartford, CT and A. Perham; Metropolitan District Commission, Hartford, CT

The South Hartford Conveyance and Storage Tunnel (SHCST) is a major component of the Hartford Metropolitan District’s Clean Water Project (CWP). This tunnel will capture and store Combined Sewer Overflows (CSO) from the southern portion of Hartford, CT and Sanitary Sewer Overflows (SSO) from West Hartford and Newington, CT. The project components include a deep rock tunnel 21,800 feet in length with a 21’-1� excavated diameter, several miles of consolidation sewers, multiple hydraulic drop shafts with deaeration chambers and a 27 MGD tunnel dewatering pump station. AECOM and Black & Veatch JV led the design and Kenny and Obayashi JV is currently building the tunnel. This paper discusses the major aspects of the design and construction of the SHCST.

Approach to Characterizing BIM Rocks for Tunnel Design Using As-Built Tunnel Data
S. Von Stockhausen and D. Young; Mott MacDonald, Pleasanton, CA, C. Slack; GEI Consultants and H. Desai; Santa Clara Valley Water District, Santa Clara, CA

Characterization of block in matrix (BIM) rock is challenging due to strength differences of up to two orders of magnitude between blocks and matrix. The Franciscan Complex is a classic BIM rock widespread throughout Northern California. Several tunnels are planned to be constructed in this material by the Santa Clara Valley Water District and others over the next five years. This paper describes a geotechnical characterization process involving laboratory testing, back-analysis using the convergence-confinement method, and as-built tunnel records for a tunnel that encountered squeezing conditions to develop geotechnical design parameters for one of these new tunnels. The likelihood, extent and distance from the face for squeezing behavior in matrix dominated ground is explored in this paper.

High In situ Stress and Its Effects in Tunnel Design: An Update Based on Recent Project Experience from WestConnex M4 East & New M5 Tunnels, Sydney, Australia
D. Tepavac and P. Mok; McMillen Jacobs Associates, Sydney, Australia, D. Oliveira; Jacobs Engineering Group, Sydney, Australia, H. Asche; Aurecon Group, Neutral Bay, Australia and S. Simmonds; CPB Samsung John Holland Joint Venture, Burwood, Australia

The WestConnex project is part of an integrated transport plan for Sydney. It includes three underground multilane tunnels: M4 East, New M5, and M4-M5 Link. Each of these tunnels is a project of its own. This paper focuses on two of the three tunnel projects (M4 East and New M5). The results of design analyses as well as tunnel support solutions that have been developed to address the anticipated adverse effects of high in situ stress in these two projects are presented. Relevant data were obtained from ongoing tunnel excavations and construction monitoring program of both projects. The developed tunnel support solution and corresponding available construction data are compared.

Design and Construction Considerations for Atwater Water Intake and Conveyance Tunnel in Montreal
J. Habimana and Benoit Rioux; Hatch, Montreal, Quebec, Canada and S. Dusablon CRT, Montreal, Quebec, Canada

The City of Montreal plans to secure the existing water intake of the Atwater Treatment Plant by permanently isolating the section of the channel adjacent to nearby highway that is at risk from contamination and spills and constructing a new intake upstream. The new intake will be linked to the existing intake by a 877m (0.5 mile) long 6m (20 ft) diameter 30m (100 ft) deep tunnel, two 6m (20 ft) diameter vertical shafts, and an cut and cover connecting structure to the existing valve chamber. The geology consists of shale that is known to be fissile and slaking and is being excavated by drill-and-blast. The paper provides design considerations of this siphon tunnel as well as construction updates.

Final Design of the River Des Peres Tunnel in St. Louis P. Pride; Metropolitan St. Louis Sewer District, St. Louis, MO, M. Robison; Hazen and Sawyer, Atlanta, GA, and J. Bergenthal; Jacobs Engineering, St. Louis, MO and W. Klecan; Jacobs Engineering, Atlanta, GA

The $585 million Lower and Middle River Des Peres (LMRDP) CSO Storage Tunnel is the largest component of Metropolitan St. Louis Sewer District’s (MSD) consent decree-driven, multibillion dollar, 23 year, Project Clear. Final design of the 8.5 mile long, 30-ft diameter tunnel, which will be excavated through limestone and dolomite at depths in excess of 200 feet, was completed in 2017. This CSO conveyance and storage project has 34 intake structures, five construction shafts, two long connecting tunnels and excavation of a large, cavern-style pump station. This paper describes the planned construction, including requirements for initial support for shafts, tunnel and cavern, and initial support of excavation for a large intake structure.

Successful Implementation of “SEM - Single Shell Lining Concept� for the Emergency Tunnel at the Brenner Base Tunnel Project – Theory and Praxis of an Innovative Shotcrete Model
T. Marcher; SKAVA Consulting ZT GmbH, Innsbruck, Austria and C. Kaiser; STRABAG AG, Innsbruck, Austria

The Brenner Base Tunnel is a railway tunnel between Austria and Italy through the Alps with a length of 64 km. The construction lot Tulfes-Pfons was awarded to the Strabag/Salini-Impregilo consortium in 2014. The construction lot includes 38 km of tunnel excavation work and consists of several structures such as the 9 km long Tulfes emergency tunnel. Such a service (non-public) tunnel does not necessarily require a tunnel lining system with two shells, but under certain boundary conditions can be achieved by a single shell lining approach. The required conditions and limitations for the single lining approach are reflected and a proposal for structural verification is provided. For verification approach a novel constitutive model for the shotcrete design is used.

Planning Track - Geotechnical, Environmental & Sustainability

Chair: B. Duncan, SAK Consulting, St. Louis, MO

Co-Chair: Z. Skovajsova, COWI, Florham Park, NJ

Assessing Resilience Impacts from Integrated Above- and Below-ground Urban Infrastructure
P. Nelson, Colorado School of Mines, Golden, CO

This paper discusses an appropriate framework and metrics for infrastructure analysis that can include complex systems representations for all sectors – physical, social and environmental. In order to make better decisions concerning the use of underground space, particularly in urban environments, the functions and operations of the human and physical infrastructure systems must be understood in an integrated framework with common and meaningful metrics and representations. Considering the importance of economics, sustainability and vulnerability to extreme events, decision makers need an understanding of the valuation for underground space as a resource in order to consider life-cycle engineering and trade-offs and pros and cons of above- and below-ground infrastructure investments.

Design, Construction, and Risk Management Strategies for Shallow Tunnels in Urban Settings
K. Bhattarai; SA Healy, Henderson, Nevada

Shallow tunnels possess serious design and construction challenges especially in urban areas. These challenges are further amplified when crossing under live railroad tracks, major road or highways, foundations of existing high-rise buildings, critical utilities, major commercial districts, and so on. The construction risks include excessive settlements of structures and utilities or even sink-hole formations leading to potential disputes and litigations, a significant increase in construction cost and schedule delays. This paper presents risk management strategies during contracting, design, and construction phases for shallow tunnels excavated using various tunneling methods.

Small Diameter TBM Tunneling: Risk Management Approach to Face Geological Uncertainties
G. Gaspari and A. Lavagno; Geodata Engineering S.p.A., Toronto, Ontario, Canada

The increasing urbanization and consequent demand for underground services is booming the world trenchless industry, from developing countries to the most advanced economies, and North America isn’t the exception. However, the particular variability of the geology must face the hazard of uncertain ground conditions as micro-tunnels, pipe jacking and small diameter TBMs drill through the alignment. It is the case of alternate shale rock formations and glacial tills layered under the major cities of Southern Canada Provinces and Northern United States. Recent case histories and experiences involved Geodata in developing a Risk Management approach specifically tailored for small diameter tunneling. The choice of mechanized tunneling technology is itself already a mitigation measure, as TBMs can effectively face hydrogeological-geotechnical unexpected conditions, but not enough: a number of mitigation measures have been tailored in order to improve the excavation process reliability.

Rehabilitation of Tunnels: An Owner’s Perspective
D. Tsztoo, A. Yu and T. Redhorse, San Francisco Public Utilities Commission, San Francisco, CA

In today’s tunneling industry, an Owner must consider program objectives and capital resources in their evaluation of tunnel rehabilitation versus new tunnel alternatives. Despite recent innovations to improve cost and efficiency for new tunnel construction, there are other considerations in the Owner’s decision making process. This paper will explore why a tunnel rehabilitation project can be the favorable option resulting in a lower budget, shorter design and construction timeline, reduced pre-construction efforts, less environmental and community impacts, and increased construction/operational flexibilities—now and for the future.

Sewer Tunnel Beneath Meramec River to Fulfill Regional St. Louis Treatment Plan and Environmental Vision
E. Litton; WSP USA, St. Louis, MO, M. Stephani; WSP USA, Chicago, IL and J. Lung; Metropolitan St. Louis Sewer District, St. Louis, MO

Phase II of the Lower Meramec River System Improvements Project, also known as the Lower Meramec Tunnel (LMT), consists of a 6.8-mile-long, 12-foot excavated diameter, 78 to 286-foot-deep sanitary sewer tunnel. The LMT is part of Metropolitan St. Louis Sewer District’s (MSD) Project Clear; a program planned to span 23 years to improve water quality throughout MSD’s service area. The tunnel’s main objective is to intercept flows and to take offline the interim Fenton Wastewater Treatment Facility (WWTF). This paper presents project details, geologic conditions, hydrogeologic challenges, initial support, final lining and the project’s bidding timeline. Other topics include: incorporating lessons from Phase I (Baumgartner Tunnel), risk mitigation, unique chert characterization and considerations to address flooding within the project area.

Sustainable Infrastructure Tunneling: Construction Materials Considerations from the Early Project Stage
F. Pellegrini, B. Daly, A. Enescu, and N. Swetchine; LafargeHolcim, Zurich, Switzerland

While tunnels offer substantial environmental and social benefits during their use phase their construction can have a heavy impact on the environment. Beyond geotechnical, hydrogeological, tunnel-boring mechanical and other considerations, smart handling of enormous material streams is a major concern. Proper materials management—inbound and outbound—is key to optimizing resource efficiency and sustainability. Planning for best-handling practices and optimal reuse of excavation materials reduces the amount of waste to be dumped, improves environmental performance and reduces costs and risks during tunneling and landfilling. A prerequisite to implement such a sustainable materials-management plan is to integrate construction material science throughout the initial project stages. Evaluation of viable solution strategies must be part of the prefeasibility studies and each design phase.

Project Plans for the California Waterfix Tunnel
J. Bednarski, J. Arabshahi and S. Valles; Metropolitan Water District of Southern California, Los Angeles, CA and S. Pirabarooban; California Department of Water Resources, Sacramento, CA

This paper describes the proposed California WaterFix tunnels project in the Northern California Delta region from the context of the recently completed environmental (EIR/EIS) process for the project. The conceptual engineering effort led to development of a project that will include more than 70 miles of large diameter tunnels. The new system ensures water supply reliability while minimizing environmental impacts to the surrounding Delta area. The project’s main twin-bore 40-foot ID tunnels will utilize a single-pass precast concrete segmental liner. Preliminary design of the project components is planned to commence in 2018. Current implementation plans will be discussed in the paper. The overall budget for the tunnels, pump plant, river intakes and appurtenant facilities is $14.9 billion in 2014 dollars.

Case Histories Track - Sewer/Water 2

Chair: J. Kantola, JCK Underground, Sierra Madre, CA

Co-Chair: J. Prada, Stantec, South Burlington, VT

Indianapolis Deep Rock Tunnel Connector and Pump Station Start Up
J. Morgan; Citizens Energy Group, Indianapolis, IN and A. Varas, AECOM Technical Services, Indianapolis, IN

The intent of this paper/presentation is to provide a review of the design, construction, startup challenges faced with constructing the Deep Rock Tunnel Connector (DRTC) and the DRTC Pump Station (DRTC PS). The 15.5 km (9.6 mi) TBM excavated DRTC is a 5.5 m (18’) diameter concrete lined tunnel with an overall CSO storage volume of 340,000 cubic meters (90 MG). The DRTC PS, constructed 85 m (260 ft) below ground surface in a rock cavern 30.5 m (100 ft) long by 18.3 m (60 ft) wide and 24.4 m (80 ft) high, has a firm pumping capacity of 340 MLD (90 mgd). Both projects were constructed under separate contracts and are now in service. An important aspect of the paper is this was the first rock tunnel for Indianapolis. As such, the tunnel industry was not familiar with Indianapolis. Nor was Indianapolis accustomed to risk sharing on projects as is done in the tunnel industry. Many of the factors noted in this case history are not new to the tunneling industry. However, as an Owner not familiar with the industry as a whole we learned how to better partner. The end result is a successful project.

South Coast Water District’s Wastewater Tunnel Rehabilitation Project, Complexity Coupled with Environmental Sensitivity
S. Tzobery; Parsons, Laguna Beach, CA, R. McDonald; Drill Tech Drilling and Shoring, K. Kilby; Parsons T. Vohra; Parsons and R. Shintaku; South Coast Water District

Located beneath multimillion-dollar homes along the Laguna Beach cliff, the construction of the 10,4740-ft long sewer tunnel rehabilitation project poses unique geotechnical, environmental, and public relations challenges. The 60-year-old sewer tunnel has severely deteriorated over the years and could result damages to the active sewer pipeline. The new shaft and access tunnel are located on an extremely constrained site in a high-traffic tourist area, thus adding complexity to construction. This paper presents the construction approaches implemented in the first phase of the project and how the team addresses the unique community-sensitive requirements.

Norris Cut Force Main Replacement Tunnel, Miami, Florida
R. Dill; AECOM, Chelmsford, Massachusetts, R. Williams; AECOM, Miami, Florida, L. Li; MDWASD, Miami, Florida and E. Ramos; Nicholson Construction, Miami, Florida
The Miami-Dade Water and Sewer Department utilized a design-build delivery approach for a replacement sewage force main under Norris Cut through very challenging coralline limestone geology. This case study will discuss alternatives considered for the replacement, how a preferred method was selected, and how various risks were addressed in the design and construction. Ultimately the mile-long tunnel was mined using a custom-built, 10-foot diameter hybrid (slurry and EPB) tunnel boring machine. The tunnel was lined with pre-cast concrete segments for initial support and 60-inch fiberglass-reinforced mortar carrier pipe was grouted inside the tunnel for the force main replacement.

Operations and Maintenance of Waller Creek Flood Control Tunnel
J. Beachy and R. Swaminathan; City of Austin, Watershed Protection Department, Austin, TX

This paper will discuss the operations and maintenance of the Waller Creek Tunnel, the City of Austin’s largest flood control project. Located in downtown Austin, the mile-long, concrete lined 26.5’ (avg. dia), 70-foot deep inverted siphon began accepting flood waters in May 2015. The next twelve months were the wettest in Austin’s history, with the city receiving 59 inches of precipitation. Limited access to the tunnel is confined to the Outlet located on Lady Bird Lake, attraction to visitors of Austin. In February 2017, the tunnel was dewatered for sediment and debris removal. Key elements of this project included evacuating millions of gallons of water, removing over 3200 tons of sediment from a 40-ft deep shaft using combination vacuum/compressor trucks, and inspecting the condition.

Prefabricated Tunnel Pipe Liners - A Modern Day Approach to Efficient Installation
J. Schneider and B. Kelley; Kelley Engineered Equipment, LLC, Omaha, NE

Many modern tunnels require the installation of prefabricated tunnel pipe liners after the excavation and initial ground support are complete to yield the long design life that clients require. Since excavation cost increases significantly with tunnel diameter, owners and designers naturally want to minimize the tunnel diameter for the required final liner size. This often leads to limited annular space between the excavation diameter and the final liner, which requires the use of specialized equipment to carry and position the liner pipe in its final location. Outlined in this paper are various methods and examples of equipment that can be utilized for installation of prefabricated tunnel liner pipe.

Pre-Excavation Grouting at the Hemphill Site-Atlanta WSP Tunnel Atlanta, Georgia
A. Bedell, K.Horton and D. Del Nero; Stantec Consulting, Atlanta, GA and B. Jones; City of Atlanta Department of Watershed Management, Atlanta, GA

The City of Atlanta’s Water Supply Program Tunnel Project, comprises a 24,000ft long, 13ft diameter, hard rock tunnel. A complex aspect of the project involves connecting five blind bore shafts to the tunnel in a location close to current drinking water reservoirs. During the supplemental geotechnical investigation following initial contract award, results from additional borehole geophysics were reviewed. Unfavorably oriented fracture sets forced a change in the original pre-excavation grouting program designed for that site. Real-time grout monitoring and geophysical data were compared to provide assurance that the program as designed correlates with the in-situ ground conditions. Following grouting, results were modeled, and all grouting data was reviewed to determine if grouting was complete.

Hard Rock Tunnel Design Improvements Over 42 kilometers Spanning Multiple Projects
A. Noronha and M. Bradford, Black & Veatch, Indianapolis, IN

Over the past eight years, the Black & Veatch tunnel design team has designed five hard rock tunnels for three cities within Indiana and Kentucky. This paper discusses a few design enhancements over the course of these 42 kilometers of tunnels in Indianapolis, Indiana; Fort Wayne, Indiana; and Louisville, Kentucky. Design improvements include optimizing tunnel slope relative to its length and depth, reducing drop shaft surface footprint by combining drop and vent shafts into one shaft, incorporating drop shafts within larger Tunnel Boring Machine (TBM) shafts, and refining the design of the bifurcation junctions of two full size tunnels excavated by a TBM.

Tuesday, June 26, 2018 | 1:30 PM

Technology Track - TBM Technology 2

Chair: A. McClelland, Kiewit

Co-chair: D. Mast, AECOM, Cleveland, OH

Digitization in Mechanized Tunnelling Technology
K. BÄPPLER, Herrenknecht AG, Germany

A major step in the digital enhancement of products and services in mechanized tunnelling technology is to optimize the advance processes as far as possible. New and enhanced developments such as highly complex and powerful information systems, sensitive sensor systems and imaging techniques are particularly relevant for the users of TBM technology. They are key for the highest level of operational safety with measurable and verifiable progress. The multitude of processes and data, in consideration of digital processes and tools, offer certain advantages including tactical and strategic options during tunnel advance. Machine performance and associated systems can be optimized at any time and precise real-time insights can be gained into the interaction of the machines with their geological or topographical environment. This paper focuses on digitization in mechanized tunnelling technology and in particular on the interaction between machine, cutting tools and prevailing geology and thus the real-time networking of products and processes.

Incorporating Geological & Geotechnical Spatial Variability into TBM and Ground Settlement Risk Assessment
J. Grasmick, M. Mooney and W. Trainor-Guitton, Colorado School of Mines, Golden, CO

This paper describes a geostatistical approach for assessing the spatial variability and uncertainty in geology and geotechnical parameters from site investigations for urban tunneling in soft ground. Geostatistical analysis conveys important spatial trends that would otherwise be missed in classical statistical analysis (e.g. mean, standard deviation, range). To assess the levels of uncertainty in geology/geotechnical parameters, sequential indicator and Gaussian simulations were performed using site investigation data from a real tunneling project. The implications of measured uncertainty on tunnel boring machine performance risk are discussed. Furthermore, the paper demonstrates how results from sequential geostatistical analysis can be extended to assessing the risk for exceeding allowable ground deformation limits.

Interpretation of Tunneling Induced Ground Movement
M. Adib; AZTEC Engineering Group, Glendora, CA, M. Crow; Los Angeles Metropolitan Transportation Authority, Los Angeles, CA, A. Marr; Geocomp Corporation, Acton, MA and S. Oginski; J.F. Shea Co., Inc., Inglewood, CA

An 8.5-mile-long light rail project in Los Angeles included twin 1-mile long tunnels,21.5 feet in diameter. An Earth Pressure Balance (EPB) Tunnel Boring Machine (TBM) was used for excavating the tunnel in the Late-Pleistocene Alluvial Soils. An automated system was implemented for near-continuous measurement of tunneling induced ground movements from 53 No., Multi-Position Borehole Extensometer (MPBXs). Optical survey was performed to measure ground surface movements. This paper presents the subsurface conditions, the geotechnical instrumentation system, the measured ground movement along the first bored tunnel, and the interpretation of the movement as related to the performance of the EPB TBM and type of subsurface conditions along the alignment.

Pre-Conditioning of Hard Rocks As Means Of Increasing The Performance Of Disc Cutters For Tunneling And Shaft Construction
P. Hartlieb, Montanuniversitaet Leoben, Leoben, Austria and J. Rostami, Colorado School of Mines, Golden, CO

Excavation of very hard intact rock by various mechanized systems is challenging and requires high cutting forces. This refers to tunneling through rock that is in excess of 200-300 MPa, which has also been considered difficult tunneling conditions by the ITA Workgroup 14 that is specialized in mechanical excavation. There are innovative concepts to improve the cuttability of hard and abrasive rocks by using pre-conditioning systems for introducing micro-fractures in the rock. This includes high-power microwave irradiation which leads to weakening of the rock by introducing micro fractures in the medium. The initial results of treating rock surface with a 24 kW microwave shows initiation of some micro-crack network and the preliminary results will be discussed in this paper. The findings will be linked to possible improvements of tunnel/shaft boring machines (TBM, SBM) performance, especially with respect to possibility of deploying a hybrid system to aid the center and gage cutters by pre-damaging the rock.

The Karlsruhe Monster - Highly Flexible Steel Formwork, operated under Hyperbaric Conditions - Design and Application of a High-tech Formwork in a Tapered Tunnel Section
R. Antretter; BeMo Tunnelling GmbH, Innsbruck, Austria

Connecting two stations of the new Light rail scheme in the heart of Karlsruhe, Germany the Kaiser-Friedrich-Tunnel had to be excavated and finally lined under compressed air conditions. An extreme widening of the tunnel on the last 40 meters made the inner lining works special with regard to both the selection and erection of the formwork as well as the construction of the lining. The nearly 200 ton formwork was erected and operated inside the pressurized tunnel, all works were performed in a 24/7 operation at up to 1.15 bar (17 psi) air pressure. The paper describes the challenges faced in connection with these unusual conditions.

Instrumentation Design Framework for Large Diameter Tunneling Projects
A. Dean, J. Pearson and M. Wong; Stantec, Walnut Creek, CA

Large diameter tunneling projects are often located in developed and sensitive environments. As such, instrumentation layout, selection, monitoring and interpretation are essential to evaluate disturbance caused by tunnel construction. At the same time, there is limited modern guidance available in the industry relative to instrumentation design methodologies. This paper provides a framework of key principles and considerations relative to design of instrumentation programs for large diameter tunneling projects. Instrumentation discussed includes monitoring of ground and structure movements, groundwater levels, and construction induced vibrations.

Design Track - Challenging Design Issues

Chair: P. Chou, Parsons, Boston, MA

Co-chair: H. Nejad, Michels, Secaucus, NJ

Design and Monitoring of an Effective Deep Excavation Cut-off
E. Sekulski, J. Leech, M. Chendorain; Arup, San Francisco, CA, J. Yao; LA Metro, Los Angeles, CA, Mark Ramsey; HNTB, Los Angeles, CA

Exposition Station is a 70 ft-deep cut-and-cover structure and a TBM launch portal for the Crenshaw/LAX Transit (light rail) Project. Ground conditions comprise sequences of clays and sands with two aquifers separated by an aquitard layer. Station excavations extend near or into the aquitard. A pressure-grouted base was initially considered necessary for a groundwater cutoff. With additional investigation and analysis, the project team demonstrated adequate cutoff could be achieved by keying the CSM wall into the aquitard, providing considerable savings to the project. This paper presents the work and challenges to demonstrate and successfully implement the alternative solution, including additional subsurface investigations, multiple aquifer tests, analyses, and a monitoring and mitigation program.

A New Approach to Hydraulics in Baffle Drop Shafts to Address Dry and Wet Weather Flow in Combined Sewer Tunnels
M. Seluga; Northeast Ohio Regional Sewer District, Cleveland, OH, S. Glovick; Wade Trim, Pittsburgh, PA, B. Murray; McMillen Jacobs Associates, Mayfield Heights, OH and F. Vincent; Northeast Ohio Regional Sewer District, Cleveland, OH

Sewer authorities in the US are constructing tunnels to control Combined Sewer Overflow (CSO) to meet regulatory requirements. This paper focuses on the design solutions for drop structures that convey an extreme variation of flow. The Doan Valley Storage Tunnel in Cleveland Ohio conveys dry and wet weather flows with a series of dual purpose conveyance and CSO storage tunnels. Baffled drop structures with dry weather drop pipes were designed to address this uncommon flow variation. This paper summarizes the design approach including numerical and physical modeling, air entrainment, energy dissipation, and structural systems for these unique drop shafts.

Challenges of Design and Construction of Slurry Walls in a Congested Site
R. Jain; Parsons Brinckerhoff, New York, NY, M. Shinouda; Jay-Dee Contractors, Livonia, MI and A. Colasante; Treviicos, Charleston, MA

The First Street Tunnel (FST) is part of DC Water’s Clean Rivers Project constructed under a residential area in Washington DC. As a design-Build project, The FST project encompassed rapid design progression and fast-track delivery. Reinforced concrete slurry walls were utilized as the support of excavation for the TBM launching shaft. As the design evolved towards construction stage, additional geotechnical borings revealed differences from provided baseline data. Coupled with permitting considerations, the design needed to be optimized to maintain structural integrity without compromising economy and efficiency. Furthermore, the execution of slurry walls having a depth of 175-ft required a controlled excavation plan which included sophisticated excavation equipment, highly trained personnel and a quality control plan that aimed to ensure the shaft wall was installed to tight tolerances.

Support of Excavation Structural Challenges and Steel Design for the Crenshaw/LAX Transit Corridor Project
B. Hoffman, B. Yang and P. Leduc; Aldea Services, Frederick, MD

The Crenshaw/LAX Transit Corridor Project is an 8.5-mile extension of the Los Angeles Metro System. Three of the stations along the underground portion of the extension have been constructed using top-down construction methods. The stations were constructed below six lane major arterial streets through downtown Los Angeles and traffic had to be supported on a decking system above large open pits to maintain traffic flow. The size of the excavations and placement of pin piles within the station excavations created challenges and a need for innovative steel design to achieve the acceptable unbraced lengths (up to 118 feet full length, 60 feet unbraced length) of strut members and make installation feasible. This paper summarizes the solutions that were developed to overcome various design obstacles for the support of excavation systems.

Tunnel Ventilation Systems Harmonization for Optimization of Tunnel Construction
S. Cassady and D. Parker; HNTB Corporation, Bellevue, WA

The SR 99 Tunnel Ventilation System (TVS) manages pollutants, providing a safe and tenable environment for motorists in the tunnel during flowing traffic, stopped traffic, and congested traffic. The TVS also mitigates the effects of smoke and heat during a fire incident to facilitate evacuation of tunnel occupants and implementation of firefighting operations. Three subsystems key to the ability of the TVS are: the extraction ventilation system; the maintenance air ventilation system; and the jet fan ventilation system. The extraction ventilation system is made up of four centrifugal extraction fans in each of the two Tunnel Operations Buildings. The fans connect to a continuous extraction duct running along the east side of the tunnel. The fans pull smoke and pollutants out of the tunnel roadway through the extraction duct and exhaust it out of stacks on top of the buildings. All eight fans are available for smoke extraction. The maintenance air ventilation system is made up of one centrifugal fan and one backup fan in each of the two Tunnel Operations Buildings. These fans connect to a maintenance air duct running along the west side of the tunnel and a utilidor under the roadways. The maintenance air system pressurizes the egress passage, preventing smoke and pollutant infiltration from the roadways. The jet fan ventilation system consists of several jet fans mounted above and alongside the roadways near the tunnel portals. These fans manage the longitudinal airflow drawing fresh air into the roadway tunnel, and pushing smoke and heat out of the tunnel away from motorists. Design development of these three ventilation subsystems establish harmonized operation modes for managing the tunnel environment such that tunnel bore and approach cut and cover size was optimized.

Vibration Study on California High Speed Rail Tunnels based on Earthquake Data and Numerical Analysis
X. You; WSP USA, St Louis, MO and D. Anderson; WSP USA, Philadelphia, PA

The paper presents a vibration study for a planned California High Speed Rail (CHSR) tunnel. Proposed tunnel alignment alternatives cross properties near a limestone quarry. There is concern regarding the potential impact of the quarry’s blast vibration on the tunnel structure. As it is in an unpopulated area, seismograph monitoring data was unavailable. A numerical simulation was done to simulate quarry blasting impact on the proposed tunnel. Quarry blast events were identified among earthquake seismic data to calibrate the numerical results. The study results can help to identify setback distance to secure integrity of the proposed tunnel.

Tunnel Cross Passage Seismic Analysis Considering 3D Wave Propagation
Y. Shi, P. Chou, D. Lin; Parsons Corporation, Boston, MA

Cross passage is a rigid connecting structure between twin bored tunnels and serves as a vital means of egress in the event of an emergency. For its seismic analysis, strains induced from the propagation of seismic waves are important parameters as well as dynamic forces transferred from adjacent tunnels. Closed-form solutions based on plane formulations have been provided in classic literatures. However, the behavior of a rigid structure between two relatively flexible tunnels during a seismic event is rather complex, and closed-form solution cannot fully capture the 3D effects of the interacting structures. An expansion of the solutions to 3D space is therefore of significance for the cross passage design. This paper presents a detailed expansion and an application to a finite element model for a transit project in Southern California to show how design can be facilitated in modeling this complex behavior.

Planning Track - Project Delivery - Transit & Highways

Chair: C. Cimiotti, SA Healy, Pasadena, CA

Co-chair: E. Chavez, Impregilo

The Future of Transit Tunneling in Washington, D.C.
B. Zelenko, H. Cordes and W. Hansmire; WSP USA, Washington, DC

In post-World War II Washington, DC, political forces came together to establish the Washington Metro System. Tunneling and underground construction methods, which were greatly influenced by local geology, have significantly improved over the nearly 50 years since Metro started construction in 1969. Half of the original 103-mile system is underground. To meet current transit demands that have exceeded expectations and future projections, new transit lines, redundancy in the downtown core, and connectivity to high-speed rail into the growing city along Amtrak’s Northeast Corridor are being considered. Current tunneling methods (including DC Water’s tunnel program), emerging technologies, and alternative delivery methods (including Los Angeles Metro experience with design-build project delivery) are discussed relative to the future of transit tunneling in Washington, DC.

Subsurface Investigations, Design and Construction Considerations for the Montreal Transportation Agency Côte-Vertu Underground Storage and Maintenance Garage
G. Osellame, J. Habimana; Hatch, Montreal, Quebec

The Montreal Transportation Agency (Société de Transport de Montreal – STM) is currently constructing the Cote-Vertu underground storage and maintenance garage that will facilitate daily operations and offer parking spaces for the new Azur trains. The project comprises three parallel tunnels of 1200 ft length each, 25 ft width with a pillar with of 16.5 ft; a 2,000 ft long connecting tunnel to the existing tunnel which will have caverns that have spans as large as 62 ft with very shallow rock cover. The contract requires the use of a roadheader to excavate the garage to ensure the stability of the pillars. The project crosses near known major faults. The paper addresses the geotechnical investigation programs, the design considerations and the selection of construction methods as well as provide updates on ongoing construction activities that started in May 2017.

Windsor-Detroit Tunnel: Application of State-of-the-Practice Maintenance and Safety Standards
E. Wang and R. Manuelyan; HNTB Corporation, New York, NY and P. Mourad, City of Windsor; Windsor, Ontario, Canada

To improve prioritizing of facility cyclic maintenance and operations costs, the Windsor-Detroit Tunnel Corporation tasked HNTB Corporation with developing recommendations for implementation of best practices for tunnel systems condition assessment and subsequent planning for maintenance activities (monitoring, repair and replacement) for the Detroit-Windsor Tunnel facility. This bi-national facility circa 1930s features two-lane roadway tunnel alignment including: approach, shield-driven tunnel, and immersed tube sections, respectively; with associated portal and ventilation structures. The August 13, 2015 ruling, that made National Tunnel Inspection Standards (NTIS) part of the Code of Federal Regulations, provided opportunity to update facility’s existing inspection, maintenance and operation manual.

Consideration of Single Bore as Construction Option for VTA’s BART Silicon Valley Phase II Extension Project
S. Zlatanic; COWI, Florham Park, NJ and K. Davey, Valley Transportation Authority, San Jose, California

In 2009, Phase II Extension of Valley Transportation Authority’s (VTA) total 16-mile BART Silicon Valley Extension Program (BSV Phase II) had planned for nearly 5-mile-long twin-bore tunnel through downtown San Jose to the City of Santa Clara with 33 cross-passages, three cut-and-cover underground stations and one at-grade station. In 2014, as the project was being revived through VTA planning efforts and environmental reviews, to better address growing community concerns, VTA had undertaken evaluation of single bore construction option with emphasis on tunnel alignment, diameter, depth, station configuration, and tunnel and station ventilation and fire life safety aspects including emergency egress. If finally approved, the single bore concept will be used for the first time in the US to house both guideways and stacked station platforms within the tunnel.

The Scarborough Subway Extension (SSE) – Large Single Bore Transit Tunneling in Toronto
M. Geary; Hatch, Toronto, Ontario, Canada, T. Gregor; Hatch, Mississauga, Ontario, Canada and E. Poon; Toronto Transit Commission, Toronto, Ontario, Canada

Hatch is performing preliminary and detailed design for the Toronto Transit Commission’s (TTC) Scarborough Subway Extension (SSE), a 6 km long extension of the existing Line 2. SSE will be delivered by the Design-Bid-Build procurement method and is currently projected for tendering in late 2019. The running structure of the extension consists of a large single bore 10.7 m internal diameter tunnel housing twin subway tracks, mined by earth pressure balance (EPB) or slurry TBM. The large single bore tunnel solution represents a significant departure from the traditional TTC arrangement of twin tunnels for subway. This paper discusses the technical background, design and construction considerations, operational constraints and assessments undertaken that led to the selection of the single bore concept for Toronto’s next major subway expansion.

The Next Big Tunnel Under Downtown Seattle
G. Clark; HNTB Corporation, Seattle, WA and J. Gildner; Sound Transit, Seattle, WA

The Alternative Analysis and early engineering studies are underway to allow Sound Transit to define a new light rail line. The new system will reach from West Seattle to Ballard and is expected to be operational between 2030 and 2035. The 11.8-mile segment will include 14 stations. It is expected to have 3.4 miles of either twin bore or large single bore tunnel and include six underground stations, 7.5 miles of elevated guideway with six elevated stations, and 0.6 miles of at-grade track with two at-grade stations. Two major water crossings will also be required over the Duwamish River in the south and over or under Salmon Bay in the north.

Crossing the Chesapeake Bay 21st Century Style- The Parallel Thimble Shoal Bored Tunnel
E. Fernandez; DRAGADOS, Madrid, Spain, A. Sanz; DRAGADOS, J. Luis Magro; DRAGADOS, Seattle, WA and E. Alcanda; DRAGADOS-USA

The Chesapeake Bay Bridge Tunnel (CBBT) was constructed in the late 1950s and early 1960s, as a new fixed link at the entrance of the Chesapeake Bay. The bridge-tunnel complex incorporates two immersed tube tunnels under the Thimble Shoal and Chesapeake Channels to facilitate marine navigation. Originally conceived as an immersed tube, the Parallel Thimble Shoal Tunnel will be constructed as a bored tunnel to reduce traffic congestion on the existing facility. The paper presents the advantages of this sustainable approach through the use of pressurized face tunneling.

Case Histories Track - Transportation 2

Chair: M. Torsiello, WSP Parsons Brinckerhoff, Los Angeles, CA

Co-chair: P. Finn, Barnard, Bozeman, MT

Risk Mitigation through the use of In-Tunnel Ground Freezing for Seattle Light Rail Tunnel Cross Passage Construction
R. Capka; Sound Transit, Seattle, WA and N. Long; Jay Dee Contractors Inc., Seattle, WA

Effectively controlling groundwater is an essential pre-requisite to the excavation of soft ground tunnels using the Sequential Excavation Method (SEM). This paper evaluates the use of in-tunnel ground freezing, in lieu of more traditional dewatering methods, as the primary means of controlling challenging groundwater conditions for the construction of several cross passages along the 4.3 mile Northgate Link Extension light rail project in Seattle, WA for the Central Puget Sound Regional Transit Authority (Sound Transit). The paper will include a review of the risk-based decision making process used during construction to select in-tunnel ground freezing over dewatering to mitigate a differing site condition, and it will analyze the outcome of that decision by reviewing the successes and challenges associated with the tunnel construction.

TBM Passing under Existing Subway Tunnels in Los Angeles, California
J. Choi; WSP USA, Los Angeles, CA, M. Crow and G. Baker; LA Metro, Los Angeles, CA, R. Drake; EPC Consultants, Inc., Los Angeles, CA, P. Jolly; Arcadis, Los Angeles, CA and C. Bragard; Traylor Bros., Inc., Los Angeles, CA

The development of a comprehensive underground subway system in Los Angeles is proceeding after the construction of the first tunnels by LA County Metro in the 1990’s. Expansion of the subway system has posed challenges with respect to interference with existing subway tunnels and transit operations. Most recently, Metro’s Regional Connector Transit Corridor (RCTC) twin bored tunnels required passing under Metro’s existing Red/Purple Line tunnels with about 5-ft of clearance. The structural integrity, safety and revenue operation of the existing subway line had to be maintained during construction of the undercrossing. This paper summarizes site conditions, monitoring program, contingency plan, execution and outcomes of the successful crossing under Metro’s Red/Purple Line with an EPBM.

What Comes Down Must Go Up – Dewatering Induced Ground Movement on the SR-99 Bored Tunnel Project, Seattle, WA, USA
J. Clare; Mott MacDonald, Seattle, WA

The Alaskan Way Viaduct Replacement Program was a $3.1 billion program to replace an aging viaduct in Seattle, Washington, USA. The bored tunnel project was a $1.3 billion design-build project that included a 2.8 km long, 17.4 m diameter road tunnel. Construction of a 24.3 m diameter, 36.5 m deep access shaft for TBM repairs relied on dewatering to depressurize a confined aquifer below the shaft base. Early design predictions estimated that settlement would be limited to the immediate vicinity of the shaft. Actual depressurization lead to unexpected widespread settlement which included numerous historic buildings and aging city infrastructure. Extensive monitoring relied on traditional and remote instrumentation of private and public facilities which proved useful to record ground movement.

Widening of a Road Tunnel without Interruption in Service
M. Invernizzi; Alpi Engineering LLC in Association with Rocksoil Spa, Austin, TX, C. Bonomi; CB Geotechnica, Milano, Italy and P. Asadollahi; Parsons Corporation, Washington, DC

Considering the growth in urban population, widening transportation tunnels is essential to ease traffic flow in congested routes. While changing the route or halting traffic may not be feasible, the only practical option would be to maintain the tunnels in service during the widening construction activities. This paper describes a practical example of a tunnel widening technique adopted in Nazzano Tunnel, a 2-lane tunnel in Rome, Italy, to which an additional lane was added. The planning and design of this project required particular sensitivity to the contractual obligations related to traffic and work deadlines to minimized risk exposure. The construction technique including the precut steel shell, ground improvement resins and segments as well as the different construction stages and productivity are presented.

The Crenshaw Corridor- Cross Passages: Design vs Construction
L. Piek; Arup. Los Angeles, CA, H. Mann; Arup, J. Kuyt; Arup, Jamaica, NY and P. Finn; JF Shea, Bozeman, MT

The Crenshaw/LAX Light Rail Transit Corridor Project included twin bore tunnels constructed by EPBM with cross passages between them for emergency egress and for locating MEP and communications equipment. Prior to commencement of the tunnel bores jet grouting was used to treat the Late-Pleistocene Alluvial Soils at the five cross passage locations. The initially specified design requirements for ground treatment versus the final jet grouting results indicated the treated ground was significantly better than specified, meaning a dramatic reduction in the structural support of the tunnel opening and cross passage shotcrete support was viable. After redesigning the cross passage support in close collaboration, the design and construction teams utilized additional subsurface investigations and an observational approach to allow construction to proceed safely, leading to further efficiencies in executing the works. The initial design approach is discussed, as well as the steps leading to the finished support. Additional details regarding the finishing works is also covered.

Humboldt Bay Power Plant Decommissioning Shaft – A Case Study in Cutter Soil Mix (CSM) Wall Construction
Z. Varley; WSP, Los Angeles, CA

The Humboldt Bay Power Plant (HBPP) Decommissioning Project includes the removal of underground facilities previously used for nuclear power generation. Groundwater control and support of excavation are critical elements for controlling demolition and excavation activities during decommissioning. This paper presents the original design concept, as well as the contractor-initiated design modification for shaft construction of a Cutter Soil Mix (CSM) deep shoring system and cutoff wall. The 110-foot diameter, 174-foot deep CSM shoring and cutoff wall allowed for the excavation and decommissioning of the reactor caisson structure beneath the Refuel Building adjacent to Humboldt Bay on the Pacific Ocean.

SEM Tunneling of City Trunk Line across Tujunga Wash
W. Roth, S. Nesarajah, and B,Su; AECOM, Los Angeles, CA, P. Lau and R. Purasinghe; Los Angeles Department of Water & Power, Los Angeles, CA and W. Pichler; Dr. Sauer & Partners, Herndon, VA

Tujunga Wash channel runs diagonally under a street intersection on a bridge. For a 60-in trunk line crossing the channel, a ~10-ft diameter, 250-ft long SEM tunnel was designed “snaking� between driven concrete piles supporting the bridge abutments. The bridge had been constructed in 1948 with a sewer siphon five feet below the channel floor. Ground conditions consist of silty sands and, except during wet season, the groundwater table is generally below tunnel invert. To assess the impact of tunneling-induced ground movements on bridge abutments and sewer, nonlinear soil-structure interaction analysis was performed with FLAC3D. The results indicated negligible settlement of bridge abutments and sewer. Tunnel construction was completed in 2016 with settlements lower than predicted. Tunnel construction was completed in 2016 with settlements lower than predicted.

Wednesday, June 27, 2018 | 8:30 AM

Technology Track - Fresh Approach

Chair: L. Gilbert, Atkinson, Austin, TX

Co-chair: S. Pollak, Arup, Houston, TX

Hands-on Training and Technology Transfer in Tunneling
M. Lazcano, J. Merello and N. Zegpi; SKAVA Consulting S.A., Santiago, Chile

This paper describes three projects in which tunneling performance was improved significantly through Training and Technology Transfer. The projects included are the Andina Phase I project, which through modified equipment technology and construction methods, productivity more than doubled; the Cheves Hydropower project where training and mentoring the supervision team, improved the Owners’ contractual control and enabled schedule recovery from a six month delay; and Ventilation Adits at El Teniente mine where through training of operators and workers on the Norwegian Tunneling Method productivity was increased by 80%. Experience has shown that leadership, having the correct methodology, planning and empathy, are key to succeeding with Training and Technology Transfer processes.

High Precision Pilot Hole Drilling Utilizing Real-Time Optical Guidance and Verification Techniques
A. Reel and S. Alziati; Shaft Drillers International, Mt. Morris, PA

Precision is the technological edge that engineers strive for as design tolerance become increasingly more stringent. The use of multiple pass drilling technologies using smaller diameter pilot holes as the initial pass to control and mitigate potential alignment deviation has long been recognized as a fundamental component of controlled drilling in deep foundations for civil, mining, and geotechnical construction. For those projects which require strict adherence to a specified alignment and have a narrow allowable deviation, the ability to accurately control the direction and inclination of the pilot hole is of paramount importance. It is the path of the pilot hole that ultimately dictates the final hole alignment.

Innovative Concrete for Aggressive Ground in Qatar
F. Bernardeau and J. Stypulkowski, CDM Smith, Doha, Qatar

The Abu Hamour Tunnel is 9.5km long with 3.7m internal diameter (ID) storm water tunnel, located in a hot humid environment with high concentrations of chlorides and sulphates which are present in the ground and groundwater, as well as in the storm water and construction dewatering water that will flow through the tunnel. Most of the construction sites in Doha use dewatering as means of keeping the excavation dry. The original conceptual design achieved a 100-years design life and 50 years maintenance-free performance of the concrete for the tunnel by applying HDPE liner on the intrados and epoxy coating on the extrados. Abu Hamour (Musaimeer) Surface & Ground Water Drainage Tunnel – Phase I (ASHO) in Doha, Qatar proposed an alternative lining utilizing, amongst other things, steel fiber reinforcement and special concrete mix consisting of a triple blend concrete suitable for harsh ground and groundwater conditions. The compliance assessment focused on concrete durability, structural integrity of elements, and cost effectiveness considering the whole life cycle costs.

In-depth Inspection of a Century Old San Francisco Water Tunnel
R. Fippin; McMillen Jacobs Associates, Walnut Creek, CA, J. Sketchley; McMillen Jacobs Associates, San Francisco, CA, T. Redhorse and D. Tsztoo; San Francisco Public Utilities Commission; San Francisco, CA,

The 92-year-old, 18.9-mile-long (30.4 km) Mountain Tunnel is part of the San Francisco Public Utilities Commission Hetch Hetchy Water conveyance system. Only six years after commissioning, defects were observed in the concrete lining, which have grown over time to expose the rock behind. This paper presents the 2017 inspection of this water tunnel and data collected to perform an assessment of its integrity. The inspection’s extensive data collection program contained a visual inspection, geologic mapping, concrete and rock coring, small-diameter drilled holes, GPR, LiDAR, and inflow measurements. The information obtained formed the basis for the condition assessment, which evaluated the tunnel’s integrity and feasibility of its rehabilitation.

Spider Pile Steel Segment Shaft
J. Mulvoy and A. King; DSI Underground, Louisville, KY

This paper will explore and detail the adaptability of steel segments in the economically challenging environment of large diameter and deep shaft construction utilizing existing slurry wall techniques. The increasing flexibility in fabrication of steel products provides a renewed opportunity to use rolled steel products in shaft construction. Machining and fabrication techniques now provide for application of water tight gaskets capable of meeting most shaft hydrostatic load conditions. Furthermore, the cutting of plates and bending technology has now provided for a much higher level of accuracy in segment fit up and final assembly. The adaptation of existing bolting technology now provides for connected steel assemblies with lower installation costs.

Teck BRE Raw Coal Conveyor Tunnel Rehabilitation
I. Halim; AECOM, Boston, Massachusetts, D. Forrester; AECOM, Sydney, Nova Scotia, N. Oettle; AECOM, San Jose, California and B. Wong; Teck Resources, Sparwood, British Columbia

Continued operation of Elkview Mine involves open pit extraction of coal reserves under Baldy Ridge in Southeast British Columbia, Canada. An existing tunnel crossing under Baldy Ridge is the only means of raw coal conveyance to the process plant, so it must be preserved and remain operational to support future mining. This paper describes the rehabilitation of the tunnel that was deemed necessary to support close proximity mining activities. A thorough geotechnical investigation and test blasting programs were conducted to support the design of remedial measures for the tunnel. Static and dynamic numerical models were developed to evaluate the impacts on the tunnel from the proposed future mining and eventual backfill over the tunnel with waste rock. The rehabilitation was designed to be constructed without disruption to the continuously operating coal conveyor that runs through the existing tunnel.

Design Track - Precast Concrete Tunnel Linings

Chair: A. Solecki, Hatch, Mississauga, Ontario, Canada

Co-Chair: J. McCluskey, NYCDEP, Corona, NY

Design of the San Francisco Public Utilities Commission’s Channel Tunnel
M. Deutscher; Jacobs Engineering, Boston, MA, S. Sadek; Jacobs Engineering Group, Attleboro, MA and M. Wong; San Francisco Public Utilities Commission, San Francisco, CA

The San Francisco Public Utilities Commission’s (SFPUC’s) Central Bayside System Improvement Project (CBSIP) includes the proposed 24 foot internal diameter, approximately 1.7 mile long Channel Tunnel (CHTL) for gravity conveyance and storage of wet and dry weather flows. The tunnel profile is approximately 110 to 150 feet below ground surface, located primarily within the Franciscan Complex. The shafts at either end of the tunnel require slurry diaphragm walls to achieve excavated diameters and depths of up to approximately 130 feet and 180 feet, respectively. This paper presents the design progress to date, including a discussion of tunnel design challenges in complex geologic conditions and the design process of a large diameter slurry wall shaft in an active seismic zone.

Designing a Bored Tunnel for the Unthinkable – A Marine Vessel Collison Assessment
D. Watson, C.Pound, C. Eberle, B. Beno; Mott MacDonald, New York, NY

Bored tunnels are generally constructed underground to avoid surface features, whether manmade or naturally occurring. Designing a bored tunnel to avoid potential marine vessel collisions can be viewed as somewhat exceptional. The design of the Parallel Thimble Shoal Tunnel was one such case where engineers needed to find innovative, yet code compliant, design solutions for this unusual scenario. A codified probabilistic approach, intended to assess the vessel impact on bridges, in conjunction with empirical vessel collision test data, was used to calculate the vessel collision force. The integrity of the precast concrete segmental tunnel liner was then assessed using complex ground structure finite element modelling. The results of the analyses were compared against the owner’s serviceability design state criteria and successfully verified.

Designing Reinforcement for Precast Concrete Tunnel Lining Segments
J. Susetyo, M. Dutton and T. Gregor; Hatch Corporation, Mississauga, Ontario, Canada and M. Mongeau; Numesh inc., Montreal, Quebec, Canada

The paper outlines the factors that need to be considered by designers to make appropriate choice for reinforcement in precast concrete tunnel lining for various project applications. The choices considered in the paper are traditional grade 60 rebar cages, the state-of-the-art grade 80 welded wire reinforcement (WWR), and steel fiber reinforcement. The discussed factors will include consideration for ground condition (including seismic and hydrostatic conditions), long-term safety and serviceability requirements, and the type of application (such as sewer or transit tunnels). The benefits and disadvantages of each option are addressed, and relative costs of the solutions are compared through a case study analysis.

Evolution and Challenges of Segmental Liner Design and Construction for SR 99 Tunnel
Y. Jiang, G. Clark and J. Wu; HNTB Corporation, Seattle, WA

The breakthrough of the SR 99 Tunnel Boring Machine (named “Bertha�) on April 4, 2017, in Seattle, USA, signifies the completion of tunnel lining construction for one of the world’s largest bored tunnels. The 57.5-foot diameter, 9,300-foot-long-tunnel under Seattle reached depths of 215 feet in an active seismic region. This paper focuses on the evolution of the SR 99 tunnel one-pass liner and interior structures from conceptual through final designs, including incorporating evolving requirements in roadway alignment, traffic flow, fire life safety, seismic safety, constructability, impact of interior structures, and other geo-structural challenges.

Guide for Optimized Design of Tunnel Segmental Ring Geometry
M. Bakhshi and V. Nasri; AECOM, New York, NY

Size of segmental tunnel linings installed in the rear of the TBM shield is defined by the internal diameter, thickness, and length of the ring. This paper provides guidance to size tunnel inner section considering the internal space required during the service; segmental ring thickness according to different major parameters such as internal diameter; and length of the ring. Segmental ring systems are presented and ring segmentation and configurations are discussed. Segment systems from the perspective of individual segment geometry are presented. Governing load cases and load combinations that may impact the initially-assumed size of rings and segments are summarized. Based on provided advantages and disadvantages, best practice is recommended for an optimized design of tunnel segmental ring geometry.

Steel Fibre Reinforced Concrete (SFRC) for TBM Tunnel Segmental Lining – Case Histories in the Middle East
G. Castrogiovanni; COWI North America, Springfield, NJ, and G. Busacchi; COWI Qatar, Doha, Qatar and G. Mariani

The experience gained by COWI in some of the world’s landmark mechanized tunnelling projects in the Middle East with the use of Steel Fibre Reinforced Concrete (SFRC) lining in sewer, storm water, and metro tunnels is reviewed in comparison with traditionally reinforced solutions. The technical challenges offered by concrete mix design and its workability and mechanical properties testing, potential local damage during handling and installation of the tunnel lining, its corrosion and fire protection, and life service requirements in the encountered highly-concentrated chloride and sulphate environments are discussed together with considerations on the reduced projects’ carbon footprint.

Planning Track - Planning for Success: Risk Management & Contracting Strategies

Chair: A. Bursey, Jacobs Engineering, Atlanta, GA

Co-chair: N. Karlin, Skanska, Riverside, CA

The Risks Associated with TBM Procurement and the Next Steps Towards Industry Change
L. Home; The Robbins Company, Solon, OH and G. Brierley; Doctor Mole Incorporated, Denver, CO

Risk management in the world of TBM tunneling is, in itself, a risky business. The underground often presents obstacles and complex projects spanning miles of tunnel multiply those risks. However, there are ways to manage and reduce risk in our industry; i.e., by ensuring that thorough geotechnical studies are done and that contingency plans are in place. The TBM itself can be designed with risk reduction in mind, using tools that expand visualization of the ground around the machine and arm the contractor with ways to get through challenging ground conditions with minimal delays. This paper will explore risk in TBM tunneling from the viewpoints of the consultant, the contractor and the equipment manufacturer. It will also seek to make recommendations as to how risk can be better managed in today’s tunneling industry.

Alternative Delivery Drives Alternative Risk Allocation Methods
J. Reilly; John Reilly International, Farmingham, MA, R. Essex; Mott MacDonald, Tampa, FL and D. Hatem; Donovan Hatem LLP, Boston, MA

Project principals seek project outcomes which meet required development plans and budgets. Underground construction demands a focus on commercial and political requirements when unanticipated subsurface conditions impact project schedules, budgets, public perception, and public acceptance. Design-build (DB) and Public/Private Partnership (P3) delivery increase related complexity. This paper explores answers to the following questions:

  • Why select DB or P3s for subsurface projects?
  • Why is risk allocation important?
  • What is our risk allocation experience for DB/P3?
  • What are applicable international practices?
  • What “lessons learnedâ€? apply to DB and P3s?
  • Can a Geotechnical Baseline Report be adapted for DB and P3?
  • How can risk allocation be incorporated into contract documents?
  • What risk allocation guidelines can improve DB and P3?
  • The way forward?

Construction Cost Estimating Using Risk-Based Approach
M. Schultz; CDM Smith, Boston, MA and G. Sanders; CDM Smith Kansas City, MO

Owners, seeking to gain a better understanding of underground risks and the possible scheduling, and budget implications of those risks on the allocation of capital funds on projects are asking for a deeper understanding of the likelihood of major risk events happening. Advanced approaches to risk-based cost and schedule analysis provide more cost certainty in designer’s cost estimates and a means to quantify the risks associated with underground construction. Risk Registers are being used as a tool to help identify and estimate the probability of occurrence of certain risk events and to cost out the significant risks associated with tunneling work that carry over into construction. Taken one step further these potential “high impact� risk events are looked at in more detail to make more informed decisions on budgets and schedules. These tools can provide a more realistic understanding for the purposes of budgeting, reserving contingency funds, and making cash flow projections. This paper reviews the approaches being used and will provide project examples where risk-based cost estimates were prepared and how they were used. Applications to alternative delivery approaches (design-build, progressive design-build, etc.) are also briefly discussed.

Procurement of and Contracting for Underground Construction Projects in North America
G. Brierley; Doctor Mole Incorporated, Denver, CO and D. Corkum; McMillen Jacobs Associates; Oxon Hill, MD

Beginning around 1990 the construction industry began contemplating using the Design/Build method of project procurement for infrastructure projects. In general, this transition from Design/Bid/Build to Design/Build was driven initially by a desire to help reduce project schedule and claims and then by an effort to facilitate project financing via PPPs. However, major underground projects can be complicated and risky for Design/Build as a result of the significant interface that takes place between construction activities and ground conditions which literally impacts 100% of the project. This paper is intended to discuss many of the important planning, design, and construction variables that need to be evaluated when deciding to use either the DBB or DB methods of project procurement for a tunneling project.

Current Trends in Procurement Delivery of Major Tunnel Projects
S. Kramer; COWI North America, Kensington, MD

This paper explores the current trends in tunneling procurement and delivery being used across the United States. This includes a comparison between conventional and alternative delivery methods as they have been applied to tunnel projects in transportation and water/wastewater. The paper will illustrate methods such as design-build, progressive/modified design build, construction management at risk and public-private partnerships and how alternative delivery methods have been successfully used and challenges faced as they are applied to a wide range of tunnel projects across the U.S. The author will share personal experiences and the experiences of other individuals and firms using actual projects constructed.

Fort Wayne Utilities Three Rivers Protection and Overflow reduction Tunnel – Project Bidding Successes and Lessons Learned
T. Short and M. Gensic; Fort Wayne Utilities, Fort Wayne, IN, L. Gentile; Black & Veatch, Indianapolis, IN and D. Day; Black & Veatch, Columbus, OH

The $200 million Three Rivers Protection and Overflow Reduction Tunnel (3RPORT) is the primary element in the City of Fort Wayne’s Consent Decree program known as Fort Wayne Tunnel Works. 3RPORT is the largest project undertaken in city history. The 3RPORT project was successfully bid and awarded in 2017 and employed key strategies to complete the design and bid the project during a window between other major tunnel projects in the USA. Key strategies included early engagement, favorable bidding of contractors through information sharing, outreach, and one-on-one discussions. Other strategies included prequalification, accelerated design, closely monitoring tunnel construction activity, project lifecycle risk management; and actively coordinating design, program management, legal and specialty consultant teams.

Interlake Tunnel – A Future Design-build Project
R. Drake; EPC Consultants, Arroyo Grande, CA

The Interlake Tunnel is a planned water conveyance tunnel between two reservoirs in Monterey County, California to provide flood control and additional water supply for the “salad bowl� agriculture industry. The tunnel is under development by the Monterey County Water Resources Agency and will be two miles long with an inside finished diameter of 10-feet. The project will be constructed through the highly fractured Monterey shale formation. This paper describes the technical design and construction details of the tunnel and adjacent spillway modification project, and the project delivery plan and schedule.

Case Histories Track - Sewer/Water 3

Chair: R. Vincent, Northeast Ohio Regional Sewer District, Cleveland, OH

Co-chair: J. Parkes, Schnabel Engineering

Preparation for Tunneling, Blacklick Creek Sanitary Interceptor Sewer Project in Columbus, OH
E. Alavi; JayDee Contractors, Inc. Livonia, MI, E. Whitman; Michels Corporation, Columbus, OH, V. Wollet; H.R. Gray, Columbus, OH and M. Anderson; Black & Veatch Corporation, Columbus, OH

The City of Columbus Blacklick Creek Sanitary Interceptor Sewer Project (BCSIS), located in northeast Franklin County, Ohio, includes 6.9 km of sewer tunnel. This project also requires the excavation of two shafts at the launch point of the TBM run, 6 intermediate shafts, and two shafts at the receiving point of the TBM. A joint venture of Michels Corporation and JayDee Contractors, Inc. (Blacklick Constructors, LLC) is constructing this project. The tunnel is being excavated using a Herrenknecht EPB TBM. This paper summarizes the preparation work that has been done prior to the launch of the TBM. Additionally, several major issues arose at the beginning of the project which were resolved through collaborative partnership between the contractor and the Construction Management Team. Lessons learned throughout this process are discussed.

The Columbus OARS CSO Tunnel from Design through Construction – An Experience in Solution-Filled Karst
P. Smith; Black & Veatch, Columbus, Ohio, R. Pesina; City of Columbus Department of Public Utilities, Columbus, Ohio, J. Coffey; DLZ Corporation, Columbus, Ohio, M. Hall; H R Gray, Columbus, Ohio, and M. Anderson; Black & Veatch, Columbus, Ohio

The alignment of the 7.01 m (23 ft) diameter bored 7.1 km (23,300 ft) long Columbus OSIS Augmentation Relief Sewer (OARS) CSO Tunnel passes through solution-filled karst limestone and dolomite at depths up to 58.0 m (190 ft) and traverses north from the Jackson Pike Wastewater Treatment Plant (JPWWTP) to the downtown Columbus Arena District. This paper will discuss planning, final design and the use of innovative methods to overcome difficult geologic conditions encountered while excavating and constructing multiple large diameter shafts, the main tunnel, a connecting tunnel and adit connections in the karst limestone. The paper will also discuss project completion, project start-up and delivery of the CSO tunnel system to the City of Columbus.

Urban Hard Rock Tunneling & Blasting in Baltimore City
T. Brown and J. Bradshaw; Bradshaw Construction, Eldersburg, MD

Bradshaw Construction recently completed 2,500 feet of tunnel for a 36 inch sanitary sewer in downtown Baltimore City. Given the local geology consisting of very hard rock (up to 37,000 psi) with intermittent veins of highly decomposed rock, the contractor utilized a 72 inch Double Shielded TBM provided by the Robbins Company, upsized from the base 60 inch tunnel design, to provide a greater ability to mine the rock. Access shafts, up to 57 feet deep, were set in congested urban environments. This required extensive utility support during operations and coordination with local residents and businesses, particularly during blasting operations. Through the challenges, the interceptor went online as scheduled.

Various Deep Shaft Construction Techniques Used in Atlanta Water Supply Program
T. Jiang and W. Warburton; Stantec Consulting Services Inc., Alpharetta, GA, Y. Wu; Stantec Consulting Services Inc., Fenton, MO and B. Jones; City of Atlanta, Department of Watershed Management, Atlanta, GA

The City of Atlanta is converting an over-a-century-old quarry into a 2.4-billion-gallon raw water storage facility through its Water Supply Program, which consists of a deep hard rock tunnel and ten deep shafts with various diameters. The shafts function as pump station shaft, drop shaft, riser shaft, and construction shaft, respectively. Multiple techniques are utilized in the shaft construction, which include conventional drill and blast for the large diameter shafts, blind bore for five 420-foot-deep and 9.5-foot-diameter pump station shafts, and raise bore for a 330-foot-deep and 16.5-foot-diameter riser shaft. The blind bore and raise bore shafts are the largest ever to be built in the southeastern Piedmont geology.

South Hartford Conveyance and Storage Tunnel Project – Successful Use of Large Diameter Secant Piles for Shaft Support
A. Perham; The Metropolitan District, Hartford, CT, J. Sullivan; AECOM, Rocky Hill, CT, M. Brune; Case Foundation, Omaha, NE, D. Belknap; Black & Veatch and C. Haynes; Black & Veatch, Wentzville, MO

The South Hartford Conveyance and Storage Tunnel (SHCST) is a major component of the Hartford Metropolitan District’s Clean Water Project (CWP). The tunnel will capture and store Combined Sewer Overflows (CSO) from the southern portion of Hartford, CT and Sanitary Sewer Overflows (SSO) from West Hartford and Newington, CT. The project includes 21,800 ft of 18 ft final diameter tunnel, several miles of consolidation sewers, eight hydraulic drop structures and a 50 MGD tunnel dewatering pump station. Construction has started on the large diameter shafts which have used large diameter secant piles (59.1inch diameter) for initial support in the upper sections of the shafts. This paper describes the challenges and methods used to construct the secant pile walls.

An Innovative Approach with Granite Block- Mud Mountain Dam 9-Foot Tunnel Rearmoring Project
M. Brunk, J. Carroll and J. James; ILF Consultants, Inc., Traverse City, MI, Terry Gilliland; Garney Construction, Gig Harbor, WA and E. Engberg; United States Army Corps of Engineers

Mud Mountain Dam near the base of Mount Rainier includes two tunnels. One of the tunnels has required ongoing invert maintenance due to the passing of high sediment loads. The United States Army Corps of Engineers (USACE) awarded the design-build contract to rehabilitate the tunnel to Garney Construction teamed with ILF Consultants and Golder Associates. Though originally awarded the project for their mechanically anchored steel armor plating design, the team provided the USACE with a value engineering change proposal (VECP) of natural granite blocks. The granite block design provides an increased design life, lower cost, and shorter construction schedule, with construction beginning in July 2017. This paper discusses details and challenges of the VECP from design through initial construction.

Contractor and Engineer Collaborate on Shaft Design, Sewer Tunnel Stabilization Project
D. Jurich; Mott MacDonald, Lakewood, CO, B. Mainer; Drill Tech Drilling and Shoring, Antioch, CA, J. McDivitt; South Coast Water District, Laguna Beach, CA, Z. Horvath; Mott MacDonald, Pleasanton, CA and E. Friedman; Mott MacDonald, Lakewood, CO

After award of the Phase I contract for construction of a new access shaft and access tunnel to support rehabilitation of an aging sewer tunnel in Southern California, the contractor proposed a modification to the shaft design. The owner agreed, and the contractor and engineer collaborated during pre-mobilization to quickly develop a solution that met project performance requirements, better suited the contractor’s preferred means and methods, and achieved construction schedule. The re-designed solution integrated initial support with final lining, addressed difficult conditions at the overburden-rock interface, met the challenges of multi-phased construction, and improved sequencing of Phase I and future construction activities.