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By Jacob Mathis, Mark Bradford, Alston Noronha, R. M. True

In June 2022, Louisville MSD completed a 6.5-km (4.0-mi), 6.1-m (20-ft.) diameter CSO conveyance and storage tunnel system located along the Ohio River in downtown Louisville, Kentucky. For large diameter shaft and tunnel construction, drill-and-blast operations among other methodologies were used in close proximity to federal, commercial, and residential properties with no impact to stakeholder infrastructure. s one of the rst maor tunneling proects in Louisvilles metropolitan area, this paper explores Black & Veatchs rigorous geotechnical instrumentation monitoring program that provided uality assurance for local stakeholders and afrmed innovative tunneling solutions can be successfully executed in an urban setting.

Jun 23, 2024

By Elisa Comis, David Chastka, Miriam Piemontese, Maria Chastka

The Lower Olentangy Tunnel (LOT) Project involves the construction of a 17,000 ft (5,200 m) long, 12 ft (3.65 m) internal diameter Combined Sewer Overflow (CSO) tunnel. The tunnel is excavated by using an Earth Pressure Balance (EPB) machine designed to cope with soft ground, weak rocks and water pressure. The project is located in the city of Columbus, Ohio and the main geotechnical hazards are related to the heterogenous soils and the low overburden in an urban environment. This paper focuses on the performance of the EPB first drive and the comparison between the design assumptions and the actual TBM performance during construction.

Jun 23, 2024

By Taeyong Lee, Cole Bales, Matt Fowler, John Horne

Mitchell Point Tunnel near Hood River, Oregon is one of the more unique segments of the Historic Columbia River Highway and State Trail being constructed through the Columbia River Gorge. This 650-foot bike/pedestrian tunnel set to open in 2024 is being delivered by FHWA in partnership with Oregon DOT, Oregon State Parks, and the U.S. Forest Service. Primarily driven using drill & blast excavation methods through basalt, the shotcrete and dowel-supported tunnel features masonry portals and ve window adits that provide illumination and views of the river similar to the original highway tunnel of many vistas built in 1915 that was removed in 1966 to make way for Interstate 84. This paper summarizes the planning, design, and construction.

Jun 23, 2024

By Bernd Hagenah, Eric C. Wang

New tunnels of significant alignment lengths such as mountain tunnels, base tunnels, as well as beneath urban centers pose unique environmental challenges. This paper highlights key environmental considerations for planning, design, construction, and operations by sharing lessons-learned from the authors' extensive project experience on these types of tunnels. Discussion of unique constraints include limited right-of- way, ventilation and emergency egress during the construction phase and revenue service, safety and security, and protection of existing structures. Practical approaches and applied innovative state-of-the-art solutions addressing distinct sustainability challenges and unique requirements are shared from US and international project examples.

Jun 23, 2024

By Nick Tessitore, Ryan Marsters, Alex Warren, Dylan Fawaz

The West Gates Deicing Industrial Waste Pond Expansion project at Denver International Airport seeks to expand utilities to accommodate additional terminal gates. The project includes six tunnel crossings beneath taxiways and runways with lengths ranging from 239 to 2,025 linear feet. Excavation methods include shielded tunnel boring machines and steerable auger boring. Designed initial support includes liner plate, steel ribs and lagging, steel casing, and Fiberglass Reinforced Pipe and ranges in size from 24" to 132". This paper will discuss challenges associated with the overall layout and design of the project, including contingencies to protect critical infrastructure. In addition, a construction update is provided.

Jun 23, 2024

By Tom Michaud, Rob Albinger, Ian Turner, Michael Rispin

Data transmission, communication, tracking, and the connection of equipment such as gas detectors, cameras, and collision avoidance systems in today's tunnel industry are critical pieces of the constructor's infrastructure. Reliability, flexibility, redundancy, and cost-effectiveness are key in selecting and implementing inte- grated systems. Both wired and wireless components are used to deliver custom solutions and can involve interconnectivity between backbones. Systems integration is important as industry adopts proven technologies from other industries. Case stud- ies are given showing how tailor-made approaches deliver needed functionality, with varying degrees of com- plexity, in various classifications of environment, in order to meet a project need.

Jun 23, 2024

By Francesco Chiappalone, Marco Invernizzi, Franco Gasperin, Brad Yoder, Fabrizio Fara

The Ship Canal Water Quality Project includes a 2.7-mile, 18-ft and 10-in internal-diameter tunnel that extends from Ballard to Wallingford, two popular neighborhoods in the West of Seattle. During the TBM Main drive a 12' × 12' boulder with variable strength up to 47,000psi was encountered resulting on signicant damages to the Cutter ead. The rst part of this paper describes the design and construction of an underground recess in front of the TBM to create a safe working environment for the TBM repairs. The second part describes an injection campaign performed to seal an unforeseen water inow appeared during the excavation of the 11 Avenue Diversion Structure.

Jun 23, 2024

By Botond Beno, Dave Watson, Danny Read

The Hampton Roads Bridge-Tunnel (HRBT) Expansion widens the existing I-64 four-lane bridge-tunnel corridor to eight lanes through construction of two parallel tunnels, interstate widening, and bridge expansions. The design-build contract was awarded to Hampton Roads Connector Partners with HDR and Mott MacDonald retained as lead designers in a Design Joint Venture. This paper will highlight some of the e challenges related to the design of the twin bored tunnels from spaceproong, tunnel enabling wors, segmental lining design and durability considerations.

Jun 23, 2024

By Roger Escoda Estelrich, Joan Carles Casado Ortega, Mitchell Gerdau, Jose Raul Martinez, Jeb Pittsinger, Frank Perrone

The existing Chesapeake Bay Bridge-Tunnel complex is being expanded to include the Parallel Thimble Shoal Tunnel. This will be a subaqueous bored crossing between two islands constructed for the original 1960s immersed-tube tunnel. Jet grouting was employed by the Chesapeake Tunnel Joint Venture (CTJV) to provide watertight base plugs, launch and retrieval blocks for the tunnel boring machine (TBM), a TBM canopy to limit ground movement, and a retaining wall to enable off-island excavation: all within hydraulically placed sands. This paper will review the design and construction challenges, including soil permeability and recharge, grout communication, installed grout strengths, and remediation requirements.

Jun 23, 2024

By Gary Peach, Khalid Saif Al-Khayareen, Vigil Fernandez, Furqan Hameed

The Musaimeer pump station and outfall project (MPSO) is in Doha Qatar. This technical paper will discuss and explain the three major stages of geotechnical investigation employed. Stage one the tender geotechnical data and how this was used to design the TBM and identify various areas of risk. Stage two was the selection of supplementary geotechnical investigation methodologies. Stage three was the geotechnical investigation by specialist equipment installed on the TBM and providing further data on a real time basis as the TBM was advancing. Analysis of all the data will be provided along with the lessons learned.

Jun 23, 2024

By Amanda Powers, Brian Glynn, Robert Sauceda, Daniel Huffines, Mike Garbeth

This paper will review the evaluation performed for the Cottonwood & Hackberry Creek Wastewater Interceptor Improvements Project to replace two separate aging and undersized interceptor sewers by either open cut construction or trenchless construction methods. A case study will be discussed for the utilization of microtunneling to avoid a deep open cut excavation within a landscaped roadway median to construct nearly a mile of new 60-inch interceptor sewer in an urban area adjacent to an environmentally sensitive riverine area, while minimizing the permitting and environmental impacts of construction, and minimizing the impacts to residents and vehicular trafc and restoration reuirements.

Jun 23, 2024

By S. Klein, M. McLeod, S. Gambino, K. Johnson, E. O’Hara

The Mokelumne Aqueducts Resiliency Project (MARP) involves construction of a 16.5-mile tunnel across the Sacramento-San Joaquin Delta (Delta) to replace the existing surface aqueduct pipelines with more resilient conveyance. The tunnel will be bored in Pleistocene-age alluvium at elevations between 100 to 10 feet below mean sea level. At this depth ground conditions are signicantly stiffer and denser than surcial soils and will mitigate potential seismic harards related to liquefaction ground shaking and cooding that could arise from potentially damaged levees. The heterogeneous soil deposits at tunnel depth consist of interbedded layers of stiff to very stiff clay and silt, and dense to very dense clean sand and silty sand.

Jun 23, 2024

By James Carroll, Lance Heyer

This paper describes the shaft design and construction for a 72-inch microtunnel under 14 active railroad tracks in Avondale, Louisiana. Initial shaft design for a deeper tunnel alignment considered secant piles with a jet grout plug. Final design for a shallower tunnel alignment included contractor input with support consisting of braced sheet piles with a jet grout plug. The authors further elaborate on jet grout implementation in very soft organic clay soils and the practical limitations of jet grouting. This paper emphasizes how all project participants worked together to utilize value engineering and alternative delivery on a unique tunneling project with a focus on temporary shaft support.

Jun 23, 2024

By Gunjan R. Bhattarai, K. Bhattarai

Applications of machine learning and robotics in the tunneling industry are still nascent. Research and development are ongoing in TBM guidance; prediction of TBM cutter wear and tunneling induced ground deformations; and robotic arms for segment installation, inspection, cleaning, and maintenance of TBM cutting tools. This paper presents a case study of geological profile reconstruction using multimodal machine learning. The results from this study can aid the development and application of multimodal AI technologies to generate data reports and geological profiles in real time, taking voice recordings, photos, or videos obtained directly from the field as inputs.

Jun 23, 2024

By Jennifer King, Julius Strid, Steve Brandon

The Upper Hidden Basin Diversion (UHBD) tunnel was driven approximately 1.2 miles by the drill-and-blast method primarily through massive granite bedrock geology for the Kodiak Electric Association, Inc. (KEA) in Kodiak, Alaska. The tunnel was driven from both portals with a constant 11-ft straight-leg horseshoe cross-section. The design and construction of the tunnel was driven by logistics and weather conditions due to its remote location and the rugged terrain of the project setting. This paper will discuss the successful completion of a challenging project over a ve-year period from preliminary planning through the design and construction phases.

Jun 23, 2024

By Francesco Chiappalone, Franco Gasperin, Fabrizio Fara

This document describes the challenging task of mining through tiebacks using a 21'-8" diameter Tunnel Boring Machine (TBM) as part of the Ship Canal Water Quality Project. The mining operation involves navigating through 17 tie-backs that are evenly spaced at 8-foot intervals, with many intersecting the full face of the cutterhead. Detailed analysis and review of TBM parameters specific to this area have been conducted to ensure operational efficiency and safety. Hyperbaric interventions have been planned and coordinated, encompassing pre-mining preparations, continuous monitoring and adjustments during the mining process, as well as post-mining measures. The document highlights the complexity and importance of strategic planning and execution to successfully overcome the tie-back intersections during the mining operation.

Jun 23, 2024

By James Corcoran, Richard McLane, Joseph DeMello, Eric Carlson, Hans van de Vrugt

The Los Angeles County Transportation Authority’s Purple Line Extension Phase 1 is a $3.12 billion (USD) design-build, underground heavy rail project, connecting an existing station at Wilshire Boulevard and Western Avenue and extending west 3.92 miles under Wilshire Boulevard and terminating approximately 550 feet west of Wilshire/La Cienega Station. The project alignment runs through the heart of the world famous La Brea Tar Pits and one of the world’s largest urban oil elds. This paper presents a case history of the planning, design, and construction efforts to achieve successful construction of the bored tunnels through Reach 3 of the alignment. Further, this paper outlines the proactive partnership between the owner, Los Angeles County Metro (Metro), the Design Builder, Skanska-Traylor-Shea oint enture (STS), and Southwest Geophysics who provided the geophysical services. Specically, the project included background review of historic site data (e.g., oil eld maps, building foundation plans, historic aerial photographs, etc.), geophysical demonstration testing to ascertain the capability of borehole magnetics to detect oil wells, directional drilling of thousands of feet of horizontal and vertical boreholes, collection of high resolution magnetic gradiometer data along vertically and horizontally cased boreholes as well as the collection of surface magnetometer data, discovery (“ground truthing”) of detected geophysical anomalies, and abatement of potential obstructions within the tunnel alignment.

Jun 23, 2024

By Carlos Álvarez, Sergio Sánchez, Michael Mains, Giuseppe Gaspari

Extensive record of tunnels excavated with SEM (sequential excavation method) in swelling grounds exists in literature: global experiences include successful tunnelling both through clayey and rock masses with time dependant deformation. However, TBM (tunnel boring machine) use in swelling conditions with high water pressures (EPB, earth pressure balance, machines or slurry shields) is much less documented, considering the lower expected impact due to the limited stress relief and operations under saturated conditions. This paper summarizes a number of studies conducted as part of the risk assessment and detailed design of a large diameter TBM tunnel in variable and challenging geological conditions. The tunnel alignment is driven through mixed face conditions including swelling soils and clayey soft rocks, prone to intense time-dependent deformations. The paper also describes the approach adopted for the design of pre-cast segmental lining subject to both swelling actions and high seismic loads, due to the regional active tectonic faults. The design of this lining included a detailed parametric study performed to handle the existing uncertainties related with ground characterization, potential deconnement and complex geological congurations.

Jun 23, 2024

By Jon Ike Isaacson, Michael Miller, Jarek Trela

Despite reef structures being relatively common in carbonate rocks around the world, tunneling experience in reefs is extremely rare. Impacts and risks associated with reef tunneling through these geologic features were also relatively unknown. A new reef was encountered during construction of the Lower Pogues Run Tunnel in Indianapolis, exposed over 5,000 linear feet along the alignment, resulting in adverse impacts on construction. Analysis of investigation data and construction from this encounter provide insight into the identification and characterization of reefs along tunnel alignments as well as the potential impacts on construction for future tunneling within reef structures.

Jun 23, 2024

By Tim M. Benson, Adam L. Lamanna, Carolina Martinez-Gutierrez, Mark J. Stephani

The Lower Concourse C Extension (LCE) 108-in Storm Sewer consists of a 2,797-foot long, 27 to 55-foot deep, 108-in I.D. storm sewer tunnel. Situated beneath active taxiways and a terminal apron at Hare International Airport (D), the tunnel diverts ows from existing storm sewers located within the footprint of a future satellite concourse. The project was delivered via Construction Manager at Risk (CMAR) as part of Chicago Department of Aviation’s (CDA) ongoing O’Hare 21 Capital Program. This paper presents project details, multiple stakeholder coordination, subsurface risks and challenges, TBM performance, and impacts to existing infrastructure.

Jun 23, 2024