Tunnel Updates – February 2024

Three times per year, TBM: Tunnel Business Magazine recaps the status of major tunneling projects underway in the United States and Canada. Below is the Tunnel Update that appeared in the February 2024 issue of the print edition.


Carson/Los Angeles/Rancho Palos Verdes

Joint Water Pollution Control Plant Effluent Outfall Tunnel
Dragados USA

NTP for this $630 million project for the Los Angeles County Sanitation Districts was issued April 8, 2019 with 1,953 working days to complete the work and an estimated completion date of mid-2027.

The Joint Water Pollution Control Plant Effluent Outfall Tunnel project will serve the sanitation needs of approximately 5 million people in 73 cities and unincorporated areas of Los Angeles County. The project is part of the Sanitation Districts’ Clearwater Program, which evaluates infrastructure and facilities needs through the year 2050 and makes recommendations on how to maintain a reliable and cost-effective wastewater management system.

As part of the implementation of the Clearwater Program, the Sanitation Districts is constructing a tunnel approximately 7 miles long and 21.5 feet in excavated diameter (18 feet in internal diameter) to convey disinfected, secondary-treated effluent from the Sanitation Districts’ Joint Water Pollution Control Plant (JWPCP) located in the City of Carson, California to an existing ocean discharge system at Royal Palms Beach in San Pedro in the City of Los Angeles. The tunnel will provide better seismic resiliency, provide additional capacity for population growth and storm events, and will provide redundancy for the two (2) existing tunnels that were constructed in 1937 and 1958, which have not been inspected in nearly 60 years. The tunnel begins at the JWPCP Shaft Site (entry shaft) and ends at Royal Palms Beach (exit shaft). The tunnel alignment varies in depth from approximately 50-feet to 450-feet below the ground surface. The entire tunnel alignment will be below the groundwater table with pressures ranging from 1 to 9 bar. As part of the scope, a 14-ft diameter cast-in-place concrete connection will be constructed to convey the treated effluent from an existing force main to the proposed JWPCP Shaft. Other notable project features include an approximately 60-foot diameter and 113-foot deep drop shaft, a junction structure and two valve structures at the JWPCP and a manifold structure at Royal Palms Beach.

Tunneling will go through two very distinct ground conditions. The first half of the tunnel will be through soft ground with depths up to 110 feet. The second half of the tunnel will be through hard rock with depths up to 450 feet where the tunnel will be subjected to intense ground squeezing conditions due to the overburden pressure.

The tunnel lining consists of bolted and gasketed precast concrete segments. Tunneling traverses splays of the Palos Verdes Fault Zone where 16-foot diameter steel liner will be used within the 18-foot diameter concrete segments to accommodate displacement from seismic events at two locations. When in operation, the tunnel will be under hydrostatic pressure. In the first half of the alignment, internal pressure will exceed the external pressure and post-tensioning of the concrete segmental liner will be necessary. To offset the “hoop stress” developed from internal pressure, a post-tensioning system consisting of internal steel tendons along the circumference of the concrete liner was specified. This post tensioning design is unique and has only been used a few times in the world, but never before in North America. In the second half of the alignment, the hard rock around the tunnel will offset the internal pressure, and post-tensioning will not be required.

Work at the JWPCP Shaft Site started in the summer of 2019. Construction of the access shaft slurry wall excavation support system was completed in December 2019. Excavation of the shaft in dry and wet conditions, which was followed by shaft tremie slab construction and dewatering, was completed August 2020. Open cut construction of the 14-foot diameter cast-in-place concrete Connection A from the proposed Junction Structure No. 1 to the JWPCP Shaft was substantially completed in October 2020. Jet grouting activities for the tail tunnel, starter tunnel, and three safe havens were completed in May 2021. Excavation of the starter and tail tunnels was completed in May 2021. The Contractor is using a Herrenknecht slurry TBM, which arrived onsite in late 2020. Fabrication of test precast concrete segments at the Traylor Bros., Inc. Littlerock, California facility began in April 2021. Tunnel machine launch began in the Fall of 2021, with production mining beginning in early-2022. Tunnel mining is anticipated to be completed by early-2025. Multiple hyperbaric interventions for TBM cutterhead inspection and maintenance have been successfully completed to date. Three planned maintenance stops at Safe Havens 1, 2 and 3 were also completed. Approximately 20,500-feet or 56% of the tunnel lining has been installed to date.

Lead Design Consultant: Parsons; Tunnel Design Consultant: Delve Underground; Tunnel Consultant: Mott MacDonald/BabEng; Listed Major Subcontractors for Dragados – Excavation and Structures: W.A. Rasic Construction Company, Inc.; Jet Grouting and Support of Excavation: Malcolm Drilling Company, Inc.

Personnel: Los Angeles County Sanitation Districts – Construction Management Section: Matthew Palma, Section Head; Russell Vakharia, Resident Engineer/Construction Manager; Sewer Design Section: Anthony Howard, Section Head; Oscar Morales, Supervising Engineer; Yoonkee Min, Senior Engineer. Parsons – Danson Kelii, Project Manager. Delve Underground – John Stolz, Lead Tunnel Design Consultant. Mott MacDonald – Brendan Reilly, Lead Tunnel Consultant; Chris Peiler, Lead Tunnel Engineer. Dragados – Matt Kendall, Project Manager; Nicholas Karlin Deputy Project Manager; Tony Hupfauf, Project Engineer.


Mountain Tunnel Improvements Project
Mountain Tunnel Constructors Inc.

The scope of the work for SF PUC includes: existing tunnel interior repair and modification work within the 19 mile tunnel length which includes; concrete lining repairs, contact grouting, pressure grouting, approximately 5,000 linear feet of new concrete invert paving, demolition of existing bulkheads and installation of new bulkheads, bulkhead improvements and debris removal. Construction of new tunnel improvements which includes a new Flow Control Facility (FCF) which is comprised of a 55 foot diameter, 150-foot deep new shaft, bypass tunnels and connections with the existing tunnel; the construction of new portal, 1075 ft long adit, tie-in of the adit to the existing tunnel, construction of a new access shaft with a new connecting adit, new siphon extension of about 300 feet with an inclined shaft connecting to the existing tunnel and installation of approximately 1,500 feet of steel pipe lining. Other work within the project limits includes construction of permanent spoil fill sites, installation of a water filtration system during the tunnel shutdowns and water treatment plant for construction water discharge, road/slope stabilization for the adit access roads, various types of retaining walls, a micro pile supported concrete deck, environmental permit compliance and other site improvements and restoration.

The 150-foot-deep and 55-foot internal diameter FCF shaft will be constructed primarily in a schist formation. The FCF bypass tunnels, which are horseshoe shape with varying dimensions, will also be constructed in schist. The 1,075-foot-long horseshoe shape adit will be constructed in both diorite and schist. The 100-foot-deep and 17-foot internal diameter access shaft and bypass tunnel siphon extensions will be constructed in diorite. It is expected that drill and blast will be the construction method for all underground construction.

The project is approximately 50% complete. Work continues in the Priest Adit to prepare for the upcoming final lining installation with the waterproofing membrane installation completed. The FCF shaft final lining was completed. Work continues on the many tunnel access road improvements along the project corridor. Outage No. 3 began in early December and in-tunnel work began including repairing the existing concrete lining and contact grouting behind the lining.

The objectives of the Mountain Tunnel Improvements are to rehabilitate the tunnel and to make improvements to extend the useful life of this asset for the next 100 years. This $139 million project will require five winter season tunnel outages of 60 to 100-day durations each to complete the in-tunnel repairs and other work inside the tunnel and to construct the tie-in connections between the existing tunnel and the new improvements.

Lead Design Consultant is Delve, SFPUC Construction Management Bureau is the construction manager, construction management and construction inspection provided by AECOM; Major coordination with Hetch Hetchy Water and Power, Ted Allen; Major Mountain Tunnel Constructors, Inc. subcontractors include Kroner Environmental, Schrader Mechanical, Cody Builders Supply, Sinclair, Carpi and Mach8Bio. Coordination and Partnering with the United States Forest Service.

Personnel: SFPUC – Regional Project Manager: Randy Anderson; Project Engineer: Joseph Buitrago; Acting Regional Construction Manager: Lucas Hoffman; Resident Engineer: Fredrick “Paco” Larsen; Public Outreach: Jonathan Streeter; Delve – Project Manager: Troy Page; Design Project Manager: Renee Fippin, Principal: Tunnel Engineer: Glenn Boyce, Principal; AECOM – Contract Manager: Steven Tidwell, Vice President; Lead Inspectors: Kevin Bolle, Mark Loving, James Brown. Ron Smith and Jon Wolfe; Safety Manager: Rick Cavil, Environmental Compliance Manager: Tony Jones; Mountain Tunnel Constructors Inc. – Project Manager: Jim Stevens; Construction Manager: Gabe McClain; Project Superintendent, Tyrone Wright.

Los Angeles

D Line (Purple Line) Extension Transit Project

The Purple (D Line) Extension Project is a 9-mile long project that consists of three Sections.
Section 1 is a 3.92-mile long subway alignment with three stations being constructed under Wilshire Boulevard in gassy ground and tar sands with prehistoric fossil deposits. It is being built by Skanska/Traylor/Shea JV under a $1.636 billion contract. Section 1 passed 88% completion as of October 2023.

The $1.37 billion Section 2 project includes 2.6 miles of twin bore tunnel and two new stations and is being built by Tutor Perini/O&G. Section 2 passed 61% completion as of October 2023.
Section 3 is a 2.6-mile extension being built by Frontier-Kemper/Tutor Perini JV under a $410 million contract for tunnel construction. Tutor Perini/O&G Joint Venture was awarded the Section 3 stations contract, which is valued at $1.4 billion and includes the construction of two new stations. Section 3 passed 50% completion as of October 2023.

According to Metro, Section 1 is forecast to open in 2025, followed by Section 2 in 2026, and Section 3 in 2027.

San Jose

VTA’s BART Silicon Valley Phase II Project

The Bay Area Rapid Transit (BART) Silicon Valley Phase II Extension (BSVII) Project is the second phase of VTA’s BART Silicon Valley Program to expand BART service into Santa Clara County. It is the largest single public infrastructure project ever constructed in Santa Clara County. The BSVII Project will extend the BART System from north San José through downtown San José to Santa Clara and is estimated to carry 54,600 passengers each weekday to destinations throughout the Bay Area by 2040. Completion of the project will finally “ring the bay” with frequent rail service.

The scope of the BSVII Project includes 5 miles of tunnel, 53.2-ft outside diameter and 48-ft inside diameter, and three underground stations. A fourth station, Santa Clara Station, and the Newhall Yard and Maintenance Facility are located at-grade at the west end of the BSVII extension in Santa Clara.
In November 2023, VTA announced that the TBM has been ordered from Herrenknecht. The $76 million TBM for the project will be the third largest TBM ever built. The largest TBM, Tuen Mun-Chek Lap Kok in Hong Kong, was 57-ft, 10-in., and the SR 99 TBM in Seattle was 57-ft, 3-in. TBM manufacturing is expected to take about 18 months.

The project will be constructed within a variety of alluvial deposits that extend from the ground surface to depths of 300 ft. The deposits consist of non-sequential, laterally variable, interbedded, and discontinuous fine-grained and coarse-grained soils. Fine-grained soils include silts and clays and coarse-grained soils include sands and gravels.

The tunnel alignment will vary in depth from approximately at grade to 160-ft below the ground surface. The entire tunnel alignment will be below the groundwater table with pressures ranging from 1 up to 4.5 bar.

Kiewit/Shea/Traylor joint venture was awarded the Stage 1 Pre Construction Services contract to complete an innovations phase, programming services, engineering design services, open book cost estimating, and schedule development. The majority of these efforts are to be complete by June 2024.

The station platforms will be housed within the bored tunnel at the Diridon, Downtown San José and 28th Street/Little Portugal stations. The majority of these stations are located along West Santa Clara Street. This approach also requires a series of adits to connect off-street surface access structures to the station platforms. The large diameter single bore approach standardizes station construction at all three stations along the CP2 alignment, eliminating the need for a long and deep open-cut, shored excavation along with minimizing utility relocation, support and local business interruptions.

The ventilation system proposed consists of a single point extraction system that relies on dampers and emergency ventilation stacks (EVS) spaced approximately 900 ft on center to remove smoke from the trainway in the event of a fire. The use of a precast concrete interior track slab supported by columns extending down to the tunnel invert instead of a track slab cast on structural fill within the tunnel, opened the invert area below the trainways to be used as a continuous ventilation plenum along the entire tunnel alignment. This continuous ventilation plenum allows for optimization of the fan locations and increases redundancy of the system.

The interior build out in envisioned as precast track slab within the bored tunnel. This method proposes the use of an alternate precast track-support structure inside the bored tunnel, in lieu of a cast-in-place track slab on structural fill. This proposal, which employs a bridge-type structure to support BART trains, employs a multi-pronged approach to address the needs of emergency ventilation, seismic resistance, TBM service, access, and egress for construction materials in a manner that had not been previously contemplated. The use of precast elements allow for more efficient construction of elements off-site in a less constrictive environment that can then be transported to and assembled within the tunnel. Placement of precast elements in the tunnel will accelerate the overall construction process and reduce the amount of work needed to be completed in the tunnel (including logistics).

Project Parties: Kiewit Engineering Group – KIE, leads and manages design; Tunnel Designer: Arup; A joint venture of HNTB and WSP are providing program management services for the project and a Mott MacDonald/PGH Wong Engineering Inc. joint venture are providing General Engineering Services. Shannon & Wilson is the Geotechnical Engineer Consultant

Personnel: Project Director: Mike Colpack; Deputy Project Director: Kari Larsen; Project Construction Manager: Dave Hazen; Underground Construction Manager: Christof Metzger; Tunnel Interior Build Out Manager: Shemek Oginski; TBM Manager: Dick McLane, Pre-Construction Manager: William Searles; Estimating Manager: Tony O’Donnell; Design Director: Eric Halvorson; Deputy Design Manager: Kimball Olsen; Lead Tunnel Engineer, Commercial Manager: Brett Campbell.



West Gates DIW Pond Expansion
Southland Contracting Inc.

This unique project addresses Denver International Airport’s (DEN) most significant environmental risk, the discharge of aircraft deicing fluid to receiving waters. Southland Contracting (SCI) is constructing critically needed DIW infrastructure to allow the airport and their airline partners to continue operating during winter weather in compliance with environmental regulations. The new construction will provide volume for the current DIW storage deficit, and the ongoing 39-gate Concourse Expansion Program. Additionally, this project provides for future Deice Pads Delta Sierra (DS) West, DS East Deice Pads Delta (D), and apron expansion DIW runoff and collection storage.

The overall purpose of this roughly $70 million project is to replace the existing DIW Pond 002. The tunnel scope of work consists of six bores totaling 5,179 lf. Each drive varies by length and diameter to accommodate the active runway, taxiways, and maintenance roads they cross.

Additional scopes of work include:

  • Four (4) 5.4-million-gallon pond cells (total of 21.6 MG of storage) located on the West Airfield
  • 4,400 lf of 72-in. & 90-in. FRP pipe to interconnect between existing Pond 002 and proposed Pond 002R
  • Diversion structures with gate valves
  • Pump Station with 4 pumps
  • 1-million-gallon DIW storage tank
  • 14-in. DIW force main to move collected DIW waters to the WADS Ponds or Lift Station No. 1 sanitary sewer system
  • Control facilities, along with needed infrastructure

Southland Contracting launched beneath Taxiway Whiskey Alpha (WA) / Bravo 4 (B4) in April 2023. A manned 60-in diameter, Single Shield Tunnel Boring Machine (TBM) is excavating the 1,465 lf run for two-pass installation. This tunnel is supported by a combination of steel casing and liner plate. This 60-in. excavation was completed in fall of 2023, and all carrier pipe has been installed and grouted.

While the WA/B4 tunnel was under construction, SCI’s second tunnel crew began setup and excavation for a 43-ft deep launch shaft in May 2023. The 38-ft diameter launch shaft is supported by steel rib and wood lagging for a single-pass installation. This 550 lf drive, northwest of Taxiway Charlie November (CN), was excavated using a manned 96-in. diameter Single Shield TBM. The single-pass installation will be completed with direct jacked FRP pipe. A 45-ft diameter common reception shaft was installed and supported with steel beam and wood lagging. The common reception shaft will connect waste flow from the 550 lf, single-pass installation, to the downstream 2,051 lf drive crossing beneath Runway 16 Lima / 34 Romeo (16L/34R). The 550-LF excavation was completed in November 2023.

Maverick was mobilized to Runway 16L/34R for a two-pass 2,051 lf drive. Maverick is a manned 132-in. diameter, Single Shield TBM. The 132-in. diameter tunnel will carry a 72-in. DIW drain line, two 32-in. DIW High Concentrate drain lines, 8-in. Glycol Supply line, two 14-in. conveyance pipes, electrical and communication lines. This excavation will be supported with steel ribs and channel lagging. The 45-ft diameter common reception shaft depth will be 50-ft deep. Given the shallow depth at the launch location, trench boxes will be used for the launch pit. TBM tunnel excavation commenced in January 2024.
The three remaining bores have been subcontracted to a local firm, Underground Infrastructure Technology (UIT). These bores range from 30 in. to 48 in. diameter and total 1,113 lf. UIT has completed 2 of the 3 bores, and the final bore is ongoing as of January 2024.

The bid value of the Project was $73,124,905. Estimated date of completion is Q3 2024/
Status of Project:

  • Contract Execution: November 30, 2022
  • Notice to Proceed: March 1, 2023
  • Estimated Completion: Q3 2024
  • 100% completed – 60 in. TBM excavation under Taxiway WA/B4
  • 100% completed – 90 in. TBM excavation single pass
  • 10% completed – 132 in. TBM excavation under Runway 16L/34R
  • Completed excavation of 4 of 4 pond cells
  • Special/unique Features of the Job:
  • Tunneling beneath active Runway, Taxiways, and maintenance roads.
  • Solve Denver International Airport’s greatest environmental hazard.
  • Build critical infrastructure to facilitate airport expansion.

Owner: City & County of Denver | Denver International Airport; Lead Designer: Burns & McDonnel Inc.; Tunnel Designer:Lithos Engineering Inc.; TBM Manufacturer:Southland Contracting Inc.; Contractor: Southland Contracting Inc.; Subcontractor: Underground Infrastructure Technology LLC. (UIT); Contractor Design Engineer:Kilduff Underground Engineering Inc.

Personnel: Area Manager: Nick Jencopale; Area Manager: Mike Froelich; Project Manager: Maxwell Pauley; General Superintendent: Jamie Willcott; Tunnel Superintendent: Genaro Ramos.



South Hartford Conveyance and Storage Tunnel
Kenny/Obayashi IV, JV

Kenny/Obayashi received NTP on this $279.4 million project for the Hartford Metropolitan District (MDC) on Aug. 1, 2016. The scope of works includes a 4 -mile long tunnel, 21-ft OD and 200 ft deep, along with a 74-ft diameter by 240-ft deep pump station shaft; a 39-ft diameter by 205-ft deep TBM launch shaft; a 32-ft diameter by 216-ft deep retrieval shaft and eight vortex drop shafts.

The tunnel geology includes red siltstone with basalt encountered at fault zones during TBM excavation. After TBM extraction, an Odor Control Building will be constructed at the Retrieval Shaft Site. MDC announced on Jan. 6, 2022, that the TBM reached the arrival shaft. A Herrenknecht Single Shield Rock TBM was used to mine through siltstone, sandstone, and shale of the Portland and East Berlin Formations and the Hampden and Holyoke Basalts. The tunnel alignment was complicated by the presence of numerous faults.

The project is in its final stages with final signoff soon.



Potomac River Tunnel
CBNA/Halmar JV

The DC Water Board of Directors approved a design-build contract for construction of the Potomac River Tunnel (PRT), the Authority announced on Oct. 6. The $819 million contract is the largest ever awarded by the Authority. The 5.5-mile-long tunnel will control combined sewer overflows (CSOs) to the Potomac River, improving water quality in this critical natural resource. This work is part of the larger Clean Rivers Project, a $2.99 billion program to improve the water quality of the Anacostia and Potomac rivers and Rock Creek by increasing the capacity of the sewer system.

A joint venture of CBNA and Halmar was selected based on its lowest price proposal and second highest technical score, therefore providing the best value.

The 18-ft diameter tunnel will run deep underground beneath the Georgetown waterfront, along the edge of the National Mall and East Potomac Park, past Hains Point and connect by gravity to the existing Anacostia River Tunnel. Construction will require two tunnel boring machines. Starting from West Potomac Park, one machine will mine south through mostly soft ground, and another machine will head north to bore through rock.

Work on the project is expected to begin in 2024 with completion in early 2030, in accordance with the schedule stipulated in the Consent Decree DC Water signed in 2005 with the U.S. Environmental Protection Agency, the Department of Justice, and the District of Columbia. Once the PRT is operational, it will reduce combined sewer overflows (CSOs) to the Potomac River by 93 percent in an average year of rainfall.


Fort Wayne

Three Rivers Protection and Overflow Reduction Tunnel Project (3RPORT)
Salini Impregilo Lane JV

The $188 million Design-Bid-Build project for Fort Wayne City Utilities consists of approximately 24,500 lf of tunnel, 200 to 240 ft deep, excavated by a Herrenknecht slurry TBM, segmentally lined with a 16-ft finished inside diameter. There are three large diameter shafts, ranging from 29 to 69 ft diameter supported through the overburden with a slurry wall, with drill-and-blast excavation through rock. There are 13 small diameter drop and vent shafts, ranging from 2 to 8 ft, excavated by blind-bore drilling, and lined with ductile iron and centrifugally cast fiberglass reinforced polymer mortar pipe. Approximately 720 lf of adits will be driven using drill-and-blast method to connect the TBM tunnel to the drop and vent shafts. The TBM tunnel and adits will be excavated primarily through limestone of the Wabash Formation with anticipated high groundwater inflow in the range of 5,000 gpm to 10,000 gpm at 6.5 bar pressure.
TBM excavation was completed in 2022. The project has reached substantial completion. Final completion was expected early this year.

Tunnel Designer: Black & Veatch; Construction Manager: Jacobs; Major Subcontractors: CSI Tunnel Systems, Keller – North America, Hardman Construction, Bunn Inc., F.A. Wilhelm Construction, Service Electric. TBM Manufacturer: Herrenknecht.

Personnel: Owner / City of Fort Wayne: Mike Kiester (Manager, City Utilities Engineering); Tunnel Designer / Black & Veatch: Leo Gentile (Senior Project Manager), Matthew Pierce (Project Manager); Construction Manager / Jacobs: Todd Webster (Construction Contract Manager); Contractor / Salini Impregilo Lane JV: Daniele Nebbia (Vice President of Tunneling Operations), Carlos Lang (Project Director), Lance Waddell (Project Manager).


City of Huntington, LTCP Projects 7 & 8 Northside Interceptor Sewer
Turn – Key Tunneling Inc. (TKT)

Huntington, IN

LTCP Projects 7 & 8 consisted of the construction of approximately 8,100 linear feet of 36- to 72-in. diameter interceptor sewer pipe, plus connecting sewers. This project also encompassed various components such as approximately 13,000 cubic yards of rock excavation, a 72-in. jack and bore under the Norfolk Southern Railroad, water main replacement, new sidewalks and curbs, full roadway reconstruction, fiber optic installation, and the construction of new CSO structures equipped with meters.

Turn – Key Tunneling Inc. (TKT), subcontracted by Atlas Excavating Inc., played a pivotal role in the successful completion of this project. TKT was entrusted with the construction of the 150-ft tunnel using 90-in. liner plate tunneling technology beneath the existing Norfolk Southern Railroad to accommodate a 66-in. diameter carrier pipe. Despite encountering unforeseen challenges during the execution phase, TKT demonstrated remarkable adaptability and problem-solving skills.

During the initial stages of the tunneling process, TKT encountered rock conditions that were significantly harder than anticipated based on the geotechnical report. To overcome this challenge, TKT proposed and executed a strategic modification to the construction approach by employing a 60-in. SBU bore within the shield, allowing for faster rock removal and facilitating the breaking of the rock formation. While some casing had to remain in place due to railroad restrictions, TKT effectively navigated these constraints and continued with the tunneling process, resorting to a drill and split method where necessary.

Despite the initial setbacks, TKT persevered and gradually gained momentum, ultimately achieving significant progress towards the latter stages of the tunnel. Despite the rock conditions exceeding the originally estimated unconfined compressive strength (UCS), TKT’s commitment to excellence and dedication to the project ensured the work was completed within the agreed upon timeline and under budget. Most importantly, TKT maintained a strong focus on safety throughout the project duration, resulting in zero accidents or near misses.

The $1.5 million project was completed between September and November 2023.

Personnel: Chris Leonard – Senior Project Manager; Gary Ison – Superintendent.


Fall Creek Tunnel
Shea-Kiewit JV

The Fall Creek Tunnel is a 20,244-ft, 20-ft, 2-in diameter bored tunnel with an 18-ft finished concrete lining (approximately 250 ft deep). There are ten CSO connecting structures/deaeration chambers and adits. The work is for Citizens Energy Group’s DigIndy project, which is a CSO reduction program including six deep rock tunnels totaling over 28 miles.

Mining commenced in September 2019 and was completed on April 1, 2020. The Fall Creek Tunnel has nine adits totaling over 5,200 feet and adit and deaeration chamber excavation is 100% complete. Adit excavation is complete and chamber build out is complete. All drop and vent shaft excavation and lining is complete. Tunnel concrete lining operations and the retrieval shaft concrete lining is 100% complete. Surface connections are ongoing. Based on the terms of a federal consent decree, the Fall Creek Tunnel must be operational by the end of 2025.

Personnel – Construction PM: Christian Heinz, P.E.; Inspection PM: Sam Cain, P.E. (AECOM); Owner: Citizens Energy Group – Manager, DigIndy Capital Program: Mike Miller, P.E.; Tunnel Construction Supervisor: John Morgan.


Pleasant Run Tunnel
Shea-Kiewit JV

The Pleasant Run Tunnel is a 41,472-ft, 20-ft, 2-in diameter bored tunnel with an 18-ft finished concrete lining (approximately 250 ft deep). There are eight CSO connecting structures/deaeration chambers and adits. The work is for Citizens Energy Group’s DigIndy project, which is a CSO reduction program including six deep rock tunnels totaling over 28 miles.

Mining commenced in May 2021 and was completed in August 2022. Drop shaft and vent shaft excavation and lining is ongoing. Adit and deaeration chamber excavation is complete, and crews have commenced lining and buildout. Tunnel concrete lining operations commenced in late April 2023 are approximately 50% complete. Surface connections are ongoing. Based on the terms of a federal consent decree, the Pleasant Run Tunnel must be operational by the end of 2025.

Key Project Personnel – Construction PM: Christian Heinz, P.E.; Inspection PM: Sam Cain, P.E. (AECOM); Owner: Citizens Energy Group – Manager, DigIndy Capital Program: Mike Miller, P.E.; Tunnel Construction Supervisor: John Morgan.



Hogan Smyrna Village Sanitary Sewers
Turn – Key Tunneling Inc. (TKT)

Louisville, KY

A new $30 million multi-family complex is under construction on the south side of Louisville under the guidance of two local developers. Hogan Real Estate and Will Realty broke ground on Smyrna Village, a 192-Unit apartment complex located at 8912 Smyrna Village Parkway in August 2023. The original project schedule calls for the construction to be completed in time to open in October (2024).

A crucial part of the sitework package that general contractor Trademark Excavating Company LLC (TEC) was contracted to perform included a 349 lf trenchless section for an 8-in. diameter gravity sewer beneath Smyrna Parkway and an on-ramp to Gene Snyder Expressway. Turn – Key Tunneling Inc. (TKT) was subcontracted by Trademark Excavating to perform this trenchless crossing. TKT elected to go with a 30-in. diameter Auger Bore, utilizing Small Boring Unit (SBU) technology to install a proposed 30-in. steel casing. The crossing was anticipated to be in hard rock for the entirety of the crossing. Once completed, the 30-in. casing would house an 8-in. SDR35 sewer pipe, that would service the new complex.

TKT started this jack and bore with a 30-in. SBU head but experienced significant issues with controlling the alignment. Variations in the rock strata and different hardness of the rock proved too much to overcome with the 30-in. head. TKT elected to remove the 30-in. casing, fill the excavated hole with concrete and upsized the line to a 42-in. casing utilizing a 42-in. SBU head. This provided TKT with better control and gave more room for error on such a lengthy run. The change in diameter proved to be a worthy solution to the alignment issue and the crossing was completed with the 42-in. casing in the same alignment as the previously started 30-in.

Once the 42-in. casing reached the receiving pit, an 8-in. SDR 35 carrier pipe was threaded through the casing and the annular space between the two grouted with a non-shrink grout. The pipe was finally tested by camera and showed it was all good from this change. The project was completed between August and December 2023.

Trademark Excavating was happy TKT came to them with solutions to the problems from their expertise in trenchless excavation and completed a difficult project as a group effort to deliver a quality product to the Owner.

Personnel – Chris Leonard – Senior Project Manager; Gary Ison – Superintendent; Bobby Howard – Foreman.


St. Louis

Jefferson Barracks Tunnel
Affholder (SAK Construction)

The $63.3 million project for the Metropolitan St. Louis Sewer District includes approximately 17,800 lf of TBM bored tunnel, and installation of a 7-ft diameter fiberglass reinforced polymer mortar carrier pipe and fiber optic conduits in the tunnel. The tunnel is located adjacent to the Mississippi River, extending southwardly from the Lemay Wastewater Treatment Plant, and is intended to replace an aging system of pump stations, force mains and shallow sewers that convey wastewater to the treatment plant.

The project is about 95 percent complete. Excavation of the tunnel and construction of the seven intake structures along the tunnel alignment are complete. The tunnel was excavated through limestone bedrock at depths ranging from 140 to 215 ft below the ground surface. Construction was by a main beam TBM launched from an 88-ft diameter shaft which will serve as a pump station to be constructed under a separate contract. A pre-excavation grouting program was conducted at the launch shaft to minimize inflow from any karstic features that could have been encountered during shaft excavation. The TBM was removed via the finished 18-ft diameter, concrete lined shaft at the upstream terminus of the tunnel. Fourteen bored shafts for drop pipes, vent pipes, and fiber optic conduits were also drilled along the tunnel alignment from the surface to the tunnel depth and passed through karstic zones above the tunnel alignment. Installation of the carrier pipe has been completed except for a 20-foot closure piece at the intermediate shaft. Placement of cellular concrete backfill for the carrier pipe started in August 2023 and is about 70 percent complete. Backfilling the intermediate shaft will be the last work required before Substantial Completion and is anticipated in mid-March 2024 with Final Completion scheduled in April 2024.

Tunnel Designer: Jacobs Engineering Group; Construction Manager: Shannon & Wilson; Major Construction Subcontractors: Case Foundation (shafts), ACT (pre-excavation grouting), Williams Tunneling (tunnel construction and carrier pipe installation), Goodwin Brothers Construction (intake construction); TBM Refurbishment: Robbins.

Personnel: Patricia Pride, Project Manager, Metropolitan St. Louis Sewer District; Kent Kotthoff, CM Program Manager, Metropolitan St. Louis Sewer District; Ray Scherrer, Division Inspector, Metropolitan St. Louis Sewer District; William Haag, Design Project Manager, Jacobs Engineering Group; Andrew Bursey, Lead Tunnel Designer, Jacobs Engineering Group; Tom Abkemeier, CM Project Manager, Shannon & Wilson, Inc.; David Donovan, Resident Project Representative, Shannon & Wilson, Inc.; Dan Swidrak, Project Manager, SAK Construction; Jack Bragg, Project Superintendent, SAK Construction; Jack Lynch, Tunnel Division Safety Manager, SAK Construction.

St. Louis

Lower Meramec Tunnel (11746)
Affholder (SAK Construction)

This is a $174 million project for the Metropolitan St. Louis Sewer District (MSD) comprising 35,903 ft (6.8 miles) of 11-ft excavated diameter, 8-ft inside diameter, 78 to 286 ft deep sanitary sewer tunnel which is expected to be mined utilizing a TBM entirely within limestone, shale and dolomite rock with two required construction shafts and six drop structures. The project is approximately 47% complete.

The Contractor has completed drilling the drop and vent shafts, installed secant piles at the termination TBM retrieval shaft and completed excavation of the termination shaft, tail tunnel, starter tunnel, and the adit to the Fenton dropshaft. The Contractor completed installation of the upper portion of the concrete lining at the starter shaft. The TBM was assembled and passed on site testing in April 2023. The TBM has mined approximately 19,000 ft to date, which is 54% of the 36,015 ft long tunnel. The contractor has also hand mined two of the five drop shaft adits. The TBM is expected to hole through in July 2024, and carrier pipe is scheduled to be installed starting November 2024.

This project is an extension of the previously constructed Baumgartner Tunnel Project which was 20,200 ft long with an excavated 12.5-ft diameter. Bedrock conditions anticipated to be encountered consist of the Warsaw Formation and the Burlington-Keokuk Limestone. The Warsaw Formation is composed primarily of limestone and shale with small amounts of chert whereas the Burlington-Keokuk Limestone includes limestone and abrasive chert which, in places, composes up to 40% to 60% of the rock mass.

Tunnel Designer is WSP as a subconsultant to HDR Engineering Inc. The Construction Manager for the project is Black & Veatch.

Personnel: Metropolitan St. Louis Sewer District – Design Project Manager: Jerry Jung; Construction Project Manager: Ray Scherrer. Tunnel Design Engineer: Everett Litton, WSP. Construction Manager: John Deeken, Black & Veatch. SAK – Project Manager; Jim Buckley. Project Engineer; Patrick Niemuth. Tunnel Division Safety Manager; Jack Lynch. Safety Manager; Matt Muscarella. General Project Supt.; Shayne Peck. Project Superintendent; Steffan Peck.



Northside Interceptor Tunnel
Granite Construction

Granite has been awarded an approximately $215 million contract by the City of Akron (OH) to construct the Northside Interceptor Tunnel Project (NSIT) to aid in preventing combined sewer overflows from entering the Cuyahoga River during typical storms. Project funding will come from the Ohio Environmental Protection Agency’s Water Pollution Control Loan Fund (WPCLF) and is expected to be included in Granite’s third-quarter CAP.

The NSIT, a crucial component of the U.S. Environmental Protection Agency’s mandated Consent Decree, is set to revolutionize the city’s sewer infrastructure and significantly reduce combined sewer overflows (CSOs). The project’s primary structure, a 16.5-ft internal diameter tunnel located along the Cuyahoga River, will play a pivotal role in addressing CSOs by collecting overflows at four locations and storing them. This storage capacity—more than 10 million gallons—will curb the environmental impacts of CSOs, safeguarding the health of local waterways.

The project encompasses various components that will ensure its efficacy and success. Key elements include 6,660 linear feet of precast-concrete-segmental-lined rock tunnel with a finished inside diameter of 16.5 feet, designed to accommodate both dry and wet-weather sewage flow, as well as store combined sewage. The project also features an array of control structures, flow drop shafts, connecting sewers, and overflow structures, all carefully integrated to optimize the system’s performance.

The project was set to begin in fall 2023 and is expected to be completed in July 2027.


Shoreline Tunnel and Consolidation Project
McNally/Kiewit SST JV

This is a $201 million project for the Northeast Ohio Regional Sewer District as part of its Project Clean Lake CSO program. It consists of 14,100 ft of 23-ft ID soft ground tunnel using a 26-ft OD Herrenknecht EPB. NTP was issued in 2021. Expected completion date is 2025.

It is approximately 100 ft deep running parallel to Lake Erie’s shoreline in Cleveland. The Shoreline Tunnel System will reduce CSO by an estimated 350 million gallons annually from 12 permitted CSO locations that are direct tributaries to Lake Erie. The project consists of the main tunnel as well as a 70-ft of 78-in. diameter dewatering sewer, 50-ft of 84-in. diameter consolidation sewer, three shafts, numerous near-surface structures, and repairs to existing sewers and regulators. All 3 shafts have been excavated and the TBM has been launched.

Unique features of this job include 6-ft precast tunnel liner rings and EPBM in soft ground, starting in glacial till, until eventually transitioning to sandy lenses with 75% of drive in clays.
Delve Underground is the tunnel designer.


Lower Olentangy Tunnel
Granite Construction

The LOT main tunnel will require construction of approximately 17,000 ft of 12-ft diameter tunnel at an average depth of 50 feet. This portion will be mined with a Herrenknecht tunnel boring machine and constructed of precast concrete segments. There are three main shafts (large manholes and other structures to provide access and tunnel controls) along LOT at Tuttle Park north of Lane Avenue, at Gowdy Field near Third Avenue & Olentangy River Road, and at Vine Street.

A 90-in. diameter microtunnel will also be constructed to relieve the OSIS near Second Avenue. The microtunnel will begin at the 2nd Avenue and Perry Street intersection and flow west into LOT at the Gowdy Field Shaft.

A 36-in. relief sewer will also be constructed to relieve a DSR in Third Avenue into LOT. This DSR is on the Kinnear Subtrunk Sewer which serves the Fifth by Northwest Blueprint area.

The LOT project was bid during the Summer of 2020. Construction began in early 2021 and is expected to be completed in September 2026.

Crews completed 1-mile long South run in November 2023. The TBM was relocated to launch shaft and assembled for re-launch of the 2.5-mile long North run January 2024. Mining is projected to be complete by December 2024.



Upper Little Sugar Creek Trunk Sewer Improvements
Bradshaw Construction Corporation

Bradshaw Construction Corporation has started construction on one pass sanitary sewer tunnels in Charlotte. The 2,272-ft by 72-in. reinforced concrete pipe tunnel will be installed behind a Herrenknecht AVN-1800 MTBM along curved alignments. Subsurface conditions consist of partially weathered rock and alluvial deposits. Construction began November 2021 and has completed the 2,272 ft for the project. The second tunnel on the project has been redesigned to incorporate a 10-ft x 10-ft horseshoe drill and blast to mitigate exposure to hard granitic rock. The project members include Charlotte Water (Owner), Kimley & Horn (Engineer) Sanders Utility Construction Co., Inc. (General Contractor) and Bradshaw Construction performing as tunneling subcontractor.

Project Information: Matthew Webb – Project Manager; mwebb@bradshawcc.com.


West Neuse Interceptor Improvements
Bradshaw Construction Corporation

Bradshaw Construction Corporation has started construction on two pass sanitary sewer tunnels in Raleigh. The 580-ft by 87.5-in. steel casing to allow for the installation of proposed 66-in. sanitary sewer will be installed behind a Herrenknecht AVN-1800 MTBM. The first 380 ft out of 580 ft has been installed. Subsurface conditions consist of granitic rock. Construction began March 2023. The project members include Raleigh Water (Owner), Black & Veatch (Engineer) JF Wilkerson Contracting Co. Inc. (General Contractor) and Bradshaw Construction performing as tunneling subcontractor.

Project Information: Matthew Webb – Project Manager; mwebb@bradshawcc.com.


Pawtucket/East Providence

Pawtucket Tunnel

Rhode Island-pawtucket-aerial
Pawtucket, RI

The Narragansett Bay Commission is building the third and final phase of its Combined Sewer Overflow Program. Phase III includes the Pawtucket Tunnel, NBC’s second CSO storage tunnel.

The $245 million Pawtucket Tunnel will be approximately 11,600 ft long, 30 ft in diameter and located in bedrock about 200 ft below the ground surface. The project includes the launch and recovery shafts (which will become permanent access shafts), four drop shafts with connecting adits at existing outfall locations, and an underground shaft- or cavern-style tunnel pump station.

The launch shaft and tunnel pump station will be located at NBC’s Bucklin Point Wastewater Treatment Facility in East Providence. The alignment will be parallel to the Seekonk River and Blackstone River, and end near the border of Pawtucket and Central Falls, Rhode Island. An 8,800-ft long, 10-ft diameter conveyance tunnel, which will connect to the Pawtucket Tunnel, is planned to begin after the Pawtucket Tunnel is completed.

The design-build contractor consists of a joint venture of CBNA and Barletta (CBNA-Barletta JV); also known as CB3A. The prime designer is AECOM. GEI Consultants is assisting AECOM with geotechnical engineering and field support. Design subconsultants include Gall Zeidler Consultants, Mueser Rutledge Consulting Engineers and BETA Group. The program/construction manager for Phase III is Stantec and its teaming partner Pare Corporation. Herrenknecht is supplying the hybrid TBM.
Tunneling was started in September 2022. Final project completion was expected by 2027.



Saluda River Force Main Extension
Bradshaw Construction Corporation

Bradshaw Construction Corporation has started construction on a two-pass sanitary sewer tunnel in Columbia. The 330-ft by 74.5-in. tunnel to allow for the installation of proposed 48-in. sanitary sewer will be installed behind a Robbins Rockhead Double Shielded Tunnel Boring Machine. Construction of a 26-ft liner plate launch shaft has commenced. Subsurface conditions consist of granitic rock. Construction began January, 2024. The project members include City of Columbia (Owner), Stantec (Engineer) McClam & Associates, Inc. (General Contractor) and Bradshaw Construction performing as tunneling subcontractor.

Project Information: Matthew Webb – Project Manager; mwebb@bradshawcc.com.



Mill Creek/Peaks Branch/State Thomas Drainage Relief Tunnel Project
Southland Mole Joint Venture

This $212 million project for the City of Dallas is scheduled for final completion in March 2026. Tunneling has been completed. Key elements of the project include:

  • 26,385 lf of tunnel
  • 32-ft, 6-in. excavated diameter (30-ft finished diameter)
  • 8 Intake Shafts (ranging from 120-vf to 200-vf depth)
  • 6 lateral tunnels excavated by Roadheader or excavators/breakers
  • Austin Chalk
  • Main Beam TBM
  • Dewatering Station

The current status is as follows:

  • Completed excavation of 8EA shafts ranging from 22 ft to 35 ft diameter and 110 ft to 190 ft deep. Total of 8EA Shafts on project (5 Intake Shafts, 1 Outfall Shaft, 1 Dewatering Station Shaft, and 1 Access Shaft).
  • Completed excavation of 6EA lateral tunnels, with the final lateral tunnel near completion. Ranging from 12.5 ft to 25 ft diameter and 50 ft to 500 ft in length.
  • Completed mining with 32-ft, 6-in. diameter TBM July 2022.
  • 26,000LF of tunnel excavation completed with Main Beam TBM (10,000 lf at 37-ft, 7-in. and 16,000 lf at 32-ft, 6-in.).
  • Completed demobilizing TBM from tunnel.
  • Mobilized formwork and equipment for cast-in-place tunnel concrete lining operation.
  • Placement of cast-in-place concrete lining operation of 30-ft ID tunnel in progress.
  • CIP Lining ongoing at multiple lateral and shaft locations.

Special/unique features of the job include:

  • Two TBM bored diameters, 37-ft, 7-in. and 32-ft, 6-in.
  • 15-in. thick cast-in-place final concrete liner
  • 6 working sites within city environment
  • Tunneling under city infrastructure (including State Highways, Light Rail Tunnels/Surface Tracks, Rail Roads)

Owner: City of Dallas; Lead Designer: HALFF; Tunnel Designer: COWI; CM: Black and Veatch; TBM Manufacturer: The Robbins Company; Contractor: Southland Mole JV (Southland Contracting & Mole Constructors); Subcontractor: Oscar Renda Contracting Inc.; Contractor Design Engineer: Aldea Services.

Personnel: SMJV Area Manager: Nick Jencopale; SMJV Senior Project Manager: Quang D. Tran, P.E.; SMJV Project Manager: Jose Ortiz, P.E.; SMJV Surface PM: Caesar Ramirez; SMJV Safety Manager: Stephen Jones; SMJV Senior Project Engineers: Matt Jackson/Jason Lipp; SMJV General Superintendent: Jose Jimenez/Mike Clingon; SMJV Project Engineers: Liany Marino.



RiverRenew Tunnel

The RiverRenew Tunnel System Project includes a 2-mile-long, 12-ft-wide tunnel, shafts, and other sewer infrastructure that will help prevent about 130 million gallons of sewage from polluting the Potomac River, Hunting Creek, and Hooffs Run each year. Traylor-Shea was awarded a $454.4 million contract to complete the final design and construct the Tunnel System Project. The Traylor-Shea design-build team consists of Traylor Bros, Inc., and J.F. Shea Co., a joint venture, with support from Jacobs Engineering and Kokosing Construction Co.

The Herrenknecht tunnel boring machine (TBM) began mining on Nov. 1, 2022, and reached the first of two outfall sites in June 2023. Boring of the Waterfront Tunnel is expected to continue through February 2024. The project also includes the Hoofs Run Interceptor, that will be excavating using a Herrenknecht 76-in. MTBM.

Project completion is expected by July 2025.

Designer: Jacobs Engineering; Construction Manager: Brown & Caldwell, JCK Underground, EPC; Major Subcontractors: Kokosing Industrial, Keller North America; TBM Manufacturer: Herrenknecht AG.

Front Royal

Parallel Waterline For The Route 522 North Corridor
Bradshaw Construction Corporation

Bradshaw Construction Corporation recently began construction for a tunnel installation on the Parallel Waterline for the Route 522 North Corridor project in Front Royal, VA. Bradshaw is currently installing a 552-ft, 60-in. steel casing tunnel underneath the Shenandoah River out of 55-ft deep liner plate shafts installed by the General Contractor. 18-in. DIP waterline will be installed by the General Contractor after the tunnel is completed. Ground conditions consist of massive limestone up to 20ksi with the potential for karst features. The project members included the City of Front Royal (Owner), CHA Consulting Inc. (Engineer), Snyder Environmental, Inc. (GC), and Bradshaw Construction Corporation working as the tunneling subcontractor.

Project Information: Jordan Bradshaw – Project Manager; Jordan.bradshaw@bradshawcc.com.

Newport News

46th Street Diversion Sewer
Bradshaw Construction Corporation

Bradshaw Construction Corporation recently completed two tunnels on the 46th Street Diversion Sewer Rehabilitation/Replacement project in Newport News. The two tunnels totaled approximately 400 lf of 43-in. steel casing. The drives were launched out of a common liner plate launch shaft installed by the General Contractor’s subcontractor at the intersection of 33rd Street and West Avenue. Ground conditions included poorly graded sand for the drive along West Avenue and fat clay for the drive along 33rd Street. Key project members included Hampton Roads Sanitation District (HRSD) (Owner), Ramboll Americas Engineering Solutions Inc. (Engineer), Tidewater Utility Construction, Inc. (General Contractor), and Bradshaw Construction Corporation as the tunneling subcontractor.

Project Information: Jordan Bradshaw – Project Manager; Jordan.bradshaw@bradshawcc.com.


Hampton Roads Bridge-Tunnel
Hampton Roads Connector Partners

With a budget of more than $3.8 billion, the Hampton Roads Bridge-Tunnel (HRBT) Expansion project for the Virginia Department of Transportation is the largest highway construction project in the state’s history. The project involves widening the current four-lane segments along nearly 10 miles of the I-64 corridor in Norfolk and Hampton, with new twin tunnels across the harbor. The expansion will increase capacity, ease major congestion and enhance travel time reliability.

The new tunnels will be bored with a 46-ft diameter variable-density Herrenknecht TBM, 50 ft deeper than the existing tunnels. The project represents only the fourth TBM-bored highway tunnel in the United States (Port of Miami Tunnel, Seattle SR 99 Tunnel and the Parallel Thimble Shoal Tunnel in Virginia are the others), and the second largest TBM used in the country (behind SR 99).

In addition to new tunnel construction, the project involves replacing/building bridge structures (five bridges to be replaced, 23 to be widened), replacing marine trestles and widening of the roadway from two to three lanes in each direction.

In early 2019, VDOT entered into a P3 design-build contract with Hampton Roads Connector Partners to build the project. Hampton Roads Connector Partners includes Dragados USA (lead contractor) and HDR and Mott MacDonald (lead designers). Also on the joint venture team are Flatiron Constructors, Vinci Construction and Dodin Campenon Bernard.

The TBM had mined nearly 1,700 ft as of the end of September. Project completion was expected in 2025.


Parallel Thimble Shoal Tunnel
Dragados USA/Schiavone Construction

The $756 million project entails the construction of a 5,700-ft bored tunnel connecting two southbound trestles of the existing Chesapeake Bay Bridge and Tunnel, a 17.6-mile structure connecting the Norfolk/Virginia Beach areas to Virginia’s eastern shore which first opened to traffic on April 15, 1964. When complete, the new tunnel will carry two lanes of traffic southbound and the existing tunnel will carry two lanes of traffic northbound.

On Feb. 21, 2023, the 43.5-ft diameter TBM began its initial excavation at the tunnel’s headwall, marking the official start of tunneling for the Parallel Thimble Shoal Channel Tunnel. WAVY reported that tunneling was stopped due to encountering an anchor while mining. Tunneling was expected to resume in early 2024, with project completion forecast for May 2027.



Ship Canal Water Quality project
LANE Construction

The $255 million Ship Canal Water Quality Project (SCWQP) Storage Tunnel Contract for Seattle Public Utilities (SPU) is comprised of 13,939 lf of 18-ft, 10-in. ID segmentally lined tunnel using a 21.5-ft diameter pressurized face tunnel boring machine (TBM) with tunnel depths ranging from 35 to 85 ft to top of tunnel, and a conveyance pipe casing under the Ship Canal installed via a curved microtunnel drive, 646 lf and 94-in. diameter.

There are five shaft sites: one slurry wall shaft at the West Shaft site in Ballard (tunnel launch site); three secant pile shafts at the Fremont site, Queen Anne site, and East Shaft site in Wallingford (tunnel exit shaft); and one drilled shaft using a steel casing at the East Ballard site. Anticipated ground conditions along the tunnel alignment consist of a highly variable mix of glacially over-consolidated soils.

When completed, the tunnel will capture and temporarily store more than 29 million gallons of untreated stormwater and sewage until the treatment plant is ready for it. The tunnel will improve water quality regionally by keeping more than 75 million gallons of polluted stormwater (from rain) and sewage each year from flowing into the Lake Washington Ship Canal, Salmon Bay, and Lake Union.

The project is a joint effort between two agencies: Seattle Public Utilities (Lead) and King County Wastewater Treatment Division. Both Agencies are under Consent Decree with the US EPA and DOJ, and the Washington State Department of Ecology. The Storage Tunnel is the second of four projects in the SCWQP. There are two subsequent projects to connect the new storage facility to the local sewer systems to complete the SCWQP.

Tunnel mining was completed in July. The 21.5-ft diameter TBM completed 13,947 ft of the tunnel drive that began in the Ballard neighborhood and traveled eastward along the north side of the Ship Canal to the Wallingford neighborhood. The 10-ft diameter MTBM also completed its journey from Fremont southward under the Ship Canal toward the Queen Anne neighborhood in March 2023. Crews then installed conveyance pipe and below grade vaults at four sites along the tunnel route.

Work on the tunnel project will continue through 2024. The overall SCWQP facility is expected to be put into service in 2027.

The Herrenknecht EPB TBM performed well through very variable ground conditions with minimal surface settlement, including passing directly underneath the footings of the approach span to Ballard Bridge.
Lane successfully introduced the use of a pressurized launch bell into the USA and the TBM overcame two significant challenges – drilling through a very large boulder, and passing through 19 de-tensioned cable tiebacks. Production statistics include 96.5 ft in one day, 390 ft in a week and 1,291 ft in a month.

Tunnel Designer: Delve Underground (formerly McMillen Jacobs Associates); Construction Manager: Jacobs Engineering; TBM Manufacturer: Herrenknecht. Major Subcontractors: Shaft Construction Malcolm Drilling Co.; Microtunneling – Northwest Boring Co. Inc.; Mechanical and Concrete Structures – Prospect Construction Inc.; Electrical – Chau Electric; Trucking – Grady Excavating Inc.; Segments: CSI.

Personnel: Owner (SPU): Keith Ward: SCWQP Executive; Cynthia Blazina: SCWQP Construction Manager; Stephanie Secord: SCWQP Project Manager; Roger Mitchell: SCWQP Supervising Resident Engineer. Lane Construction: Daniele Nebbia: Vice President of Tunneling Operations; Project Director: Fabrizio Fara; Project Manager: John Arciszewski; Technical Manager: Francesco Chiappalone.




Stage 2 LRT Project – Confederation Line East and West Extension Project
East-West Connectors (EWC)

The Stage 2 Confederation Line East and West Extension Project is a $2.57 billion (CAD) design-build-finance project for the City of Ottawa being built by East-West Connectors (EWC), a joint venture comprised of Kiewit, Eurovia and VINCI (KEV).

The Stage 2 O-Train East and West extensions are a signature project in Canada’s national capital, funded by three levels of government. There is a strong focus on ensuring that the project is delivered with minimal impact to the community. This requires close, on-going engagement with stakeholders and the public, as building a large infrastructure project in an urban environment is disruptive. The West extension includes two cut-and-cover tunnels:

  • The 3-km Parkway Tunnel will travel between Kichi Zìbì and Lincoln Fields stations traveling underneath the Kichi Zìbì Mīkan (formerly Sir John A. Macdonald Parkway), Richmond Road, and Byron Linear Park.
  • The 270-m Connaught Tunnel will link south of Lincoln Fields Station with Queensview Station by traveling underneath Connaught Avenue and connecting with the Pinecrest trench.

In October 2023, excavation on all cut and cover tunnels was completed. Construction of the Parkway Tunnel began in 2020 and, at the end of 2023, it was 85% complete. Construction of the Connaught Tunnel began in 2021 and, at the end of 2023, it was 80% complete. The structural work for both tunnels is expected to be fully completed at the end of 2024. The Parkway Tunnel will travel through federal lands and a City of Ottawa park (Byron Linear Park) to preserve recreational opportunities and community linkages. When construction is complete on the Parkway Tunnel, Byron Linear Park will be enhanced to include more trees, less pavement, more public art, and additional plaza space for local events. The Connaught tunnel will travel beneath Connaught Avenue.

To optimize the building sequence, the structures team is utilizing three Everest Traveler formwork systems to pour the three walls of the tunnel and roof together on the Parkway Tunnel. This is a hydraulic system that allows the team to pour 250 cubic metres of concrete every 10 days. The Everest needs to be modified at certain points due to the alignment of the cut and cover tunnel.

The structures team is also using two Peri Travelling Formwork systems, which perform the same functions as the Everest Traveller but in less uniform spaces pouring the walls and roof separately.

Design engineering services for the Stage 2 Confederation Line East and West Extension Project are being provided by WSP Canada and Hatch Ltd.

Personnel: Alex Saltarelli, Project Director, East-West Connectors GP.


Stage 2 LRT Project – O-Train South Extension Project

Ottawa - Cut and Cover_Richmond Road_November 2023
Ottawa, ON

Dow’s Lake Tunnel has been rehabilitated as part of the Stage 2 O-Train South Extension. The tunnel was originally opened in 1967 as part of the Prescott Line of the Canadian Pacific Rail corridor and was an ambitious project for its time. Local city transit service operator, OC Transpo took possession of the tunnel as part of its pilot light rail project in 2001. One aim of the O-Train South Extension Project, beginning in 2019, was the rehabilitation of Dow’s Lake Tunnel, now more than 50 years old.

The height of the tunnel is approximately 6.7 m from the top of the rail. The width of the tunnel is approximately 5.1 m, and the length of the tunnel is approximately 750 m. The tunnel was built underneath Dow’s Lake, an artificial lake created to regulate water levels in the Rideau Canal. One of the main challenges in the rehabilitation of the tunnel was the impact of years of water infiltration and stress on the concrete structure. Thorough concrete inspections were undertaken, and crack injections were performed on deficient areas. The tunnel structure was reinforced with a series of 23 concrete boxes and 22 expansion joints. Corrections, improvements, and additions were made to the standpipe system and the pumphouse building in charge of its operation.

In addition, new elements were added during the course of the O-Train South Extension to comply with modern safety and fire standards. The most notable of these is the new Tunnel Ventilation System (TVS), a now standard safety component to ensure passenger safety in the unlikely event of a fire inside a tunnel. The Dow’s Lake Tunnel TVS has been installed and tested, comprising a system of 18 powerful jet fans. Egress routes from the tunnel have been made safer by means of concrete trough systems that also house communication wiring throughout the tunnel. Stairs have been added to the North and South portals to the tunnel as evacuation routes. Finally, to bring the tunnel fully into the 21st century, cellular wiring has been added to ensure no one loses signal, a further safety feature in case of emergency.
In January 2024, the O-Train South Extension is nearing completion and so is the rehabilitation of Dow’s Lake Tunnel. Rigorous testing and commissioning of all systems, including those in the tunnel, is well underway to support the eventual launch of revenue service.


Ashbridges Bay Treatment Plant Outfall
Southland | Astaldi Joint Venture

Key components of this $300 million project for the City of Toronto include:

  • 16 m diameter shaft. 85 m deep
  • 3.5 km of 8 m diameter TBM excavated tunnel
  • 7 m ID Precast Concrete segmental lining
  • 50 of 1 m diameter risers from tunnel (marine work)
  • CIP Structure at top of shaft
  • Ground expected: Georgian Bay shale
  • The project is over 90 percent complete. Construction activities and milestones include:
  • Shaft excavation complete
  • 8-m diameter segmental tunnel complete
  • Offshore Risers installations complete
  • Riser connections in tunnel complete
  • CIP starter tunnel complete
  • Shaft concrete lining underway
  • Effluent Conduit Structure underway

Consultant & Designer: Hatch with Jacob & Baird; Major Subcontractors: Johnson Bros. Corp. (Off-shore work including Riser installation).

Personnel: Contractor: Southland | Astaldi JV; Project Director (Joe Savage); Project Manager (Pouya Mirhashemian); Deputy Project Manager (Ben Okundia); Deputy Project Manager (Christian Zenck); General Superintendent (Curtis Bahten); Underground Superintendent (Jeff Reagan).

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