Tunnel Updates

CALIFORNIA

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. 2023 saw the completion of the 4th mile of tunneling. Tunnel mining is anticipated to be completed by mid to late-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.

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; Phil Kang, Resident Engineer/Construction Manager; Sewer Design Section: Anthony Howard, Section Head; Don Drorbaugh, Supervising Engineer; Yoonkee Min, Senior Engineer; Edgar Rocha, Engineering Associate; Cecilia Dominguez, Civil Engineer. Parsons – Danson Kelii, Project Manager. Delve Underground – John Stolz, Lead Tunnel Design Consultant. Mott MacDonald – Brendan Reilly, Lead Tunnel Consultant; Max Gleichman, Lead Tunnel Engineer. Dragados – Matt Kendall, Project Manager; Nicholas Karlin Deputy Project Manager; Tony Hupfauf, Project Engineer.

Los Angeles
D Line (Purple Line) Extension Transit Project
The Purple (D Line) Extension Project is a 9-mile long project being built by the Los Angeles County Metropolitan Transportation Authority (Metro) 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 was built by Skanska/Traylor/Shea JV under a $1.636 billion contract.

The $1.37 billion Section 2 project includes 2.6 miles of twin bore tunnel and two new stations and built by Tutor Perini/O&G.

Section 3 is a 2.6-mile extension 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.

On April 2, 2024, Metro announced that it has successfully completed all tunneling. This major construction milestone was accomplished safely in one of the densest and most geologically challenging urban corridors in the L.A. region and nation.

Contractors utilized the latest tunnel boring machine (TBM) technology to excavate approximately 40-60 ft per day to help complete tunneling for the project.

During its five years of tunneling, Metro faced and successfully overcame many technical challenges like gassy ground, tar sands and abandoned oil wells. Near the La Brea Tarpits, for example, Metro’s advanced TBMs made their way through tar sands, and used horizontal directional drillings to probe the earth so contractors could identify and remove potential objects before any TBM damage occurred. Metro also safely used the same methods to identify and avoid unmapped and abandoned oil wells underneath Beverly Hills High School.

Project opening dates for the segments are: Section 1 – 2025; Section 2 – 2026; and Section 3 – 2027.

Oakdale
Paulsell Lateral Tunnels 1 & 2
Drill Tech Drilling and Shoring, Inc.

This $3.3 million project for the Oakdale Irrigation District consists of enlarging existing 3-ft x 7-ft irrigation canal tunnels to ~10-ft x 10-ft. Tunnel 1 is ~750 lf and Tunnel 2 is ~330 lf.

Drill Tech crews are using AM-50/AM-150 roadheaders to mine soft claystone/sandstone. The excavation is supported with fiber reinforced shotcrete and WWF in sandy spots.

NTP was issued Oct. 2, 2024, with tunnel scope beginning November 2024. Estimated completion is February 2025. All excavation is complete with shotcreting underway at press time. The project was on schedule to wrap up two weeks early despite a slow start due to rain/access at portals.

Crews mined two tunnels at once and adhered to a tight schedule to meet outage requirements from OID. Environmental regulations required that no work be done during fog, rain events, and 24 hours after rain events.

Tunnel Designer – Provost & Pritchard Consulting Group; General Contractor – Drill Tech Drilling and Shoring, Inc.; Owner – Oakdale Irrigation District; Construction Manager – Provost & Pritchard Consulting Group.

Personnel: Tunnel Designer – Provost & Pritchard Consulting Group, Scott Lewis; General Contractor/Tunnel Contractor – Drill Tech Drilling and Shoring, Inc. Alex Folchi; Owner – Oakdale Irrigation District – Joe Kosakiewicz; Construction Manager – Provost & Pritchard Consulting Group, Jake Feriani.

San Jose
VTA’s BART Silicon Valley Phase II Project
Kiewit/Shea/Traylor
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. Boring is scheduled to begin in 2027, per VTA.

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. Bechtel Infrastructure Corp. was selected to provide construction management services.

The station platforms will be housed within the bored tunnel at the Diridon, Downtown San José and 28th Street/Little Portugal stations.

Preliminary work is underway. Negotiations are continuing including evaluating cost-savings opportunities. According to VTA, the tunnel contractor is expected to be mobilized in early 2026.

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

Shaver Lake
Helms Liner Repair Project
Drill Tech Drilling and Shoring, Inc.
This was a $2.86 million project for Pacific Gas & Electric (PG&E) that includes:
– Contact Grouting 150 lf of steel lined 11- to 15-ft diameter penstock and 50 lf of 15-ft diameter concrete lined penstock directly upstream of large underground powerhouse (Helms).
Concrete liner repairs ~ 50 cubic yards excavated by hand/chipping gun and mucked by hand through 30-in. diameter flange.
– Arcylic resin stitch grouting 300 lf of 0.5-in. diameter leaking cracks.
– Setup, maintain and demobilize all underground safety and utilities (power, water, air, lighting, leakage water collection/pumping, etc.) for ~800 lf of tunnel for four different subcontractors during outage.

NTP was issued July 1, 2024, with tunnel scope beginning in September 2024. The job is 100% complete with demobilization in mid-January. The project was completed during scheduled outage with multiple scopes growing in nature from bid time.

Special/unique features of the job included:
-Very remote project location, ~2 hours by car from nearest town and ~7,500 ft elevation.
-Tight schedule to meet outage requirements from PG&E
-Tight access through 30-in. flange to get to majority of work

Tunnel Designer – Delve Underground; General Contractor – Drill Tech Drilling and Shoring, Inc.; Owner – PG&E; Construction Manager – PG&E.

Personnel: Tunnel Designer – Delve Underground, Shawn Spreng; General Contractor/Tunnel Contractor – Drill Tech Drilling and Shoring, Inc. Alex Folchi; Owner – PG&E – Rex Avila; Construction Manager – PG&E, Ryan Rabbon.

DISTRICT OF COLUMBIA

Washington
Potomac River Tunnel
CBNA/Halmar
The $819 million contract is the largest ever awarded by DC Water. The 5.5-mile-long tunnel will control combined sewer overflows 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 began with a ceremonial groundbreaking on May 21. Completion is expected 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.

INDIANA

Indianapolis
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.

All tunnel, shaft, adit, and deaeration chambers are 100% complete, and the Fall Creek Tunnel is now available for additional storage of CSO overflows from the four DigIndy Tunnel segments that have been previously commissioned. Surface connections to CSO outfalls along the Fall Creek Tunnel alignment 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: Eric Haacke.; Inspection PM: Sam Cain, P.E. (AECOM); Owner: Citizens Energy Group – Manager, DigIndy Capital Program: Mike Miller, P.E.; Tunnel Construction Supervisor: John Morgan.

Indianapolis
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.

All tunnel, shaft, adit, and deaeration chambers are 100% complete, and the Pleasant Run Tunnel will be available for additional storage of CSO overflows from the four DigIndy Tunnel segments that have been previously commissioned. Surface connections to CSO outfalls along the Pleasant Run Tunnel alignment are ongoing. Based on the terms of a federal consent decree, the Pleasant Run Tunnel must be operational by the end of 2025.

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

MARYLAND

Baltimore
Frederick Douglass Tunnel
Kiewit/Shea JV
On April 3, 2024, Amtrak announced that it has awarded a “Delivery Partner” contract to ADVANCE – a joint venture between major infrastructure firms AECOM and Jacobs. The joint venture’s work will include design oversight, construction management, contract management and other administrative support, among other tasks, on this $6 billion to improve rail traffic through downtown Baltimore. The new tunnel replaces Civil War era tunnels that limited capacity and served as a bottleneck on the heavily travelled Northeast Corridor between New York and Washington, D.C.

The announcement followed soon after Amtrak awarded a CMAR contract to build the new Frederick Douglass Tunnel in February to Kiewit/Shea Joint Venture. In fall 2023, Amtrak awarded demolition contracts and a CMAR contract for the Program’s “Southern Approach,” which includes a new ADA-accessible West Baltimore MARC Station, replacing multiple bridges, and constructing tracks and other railroad infrastructure.

The Frederick Douglass Tunnel project includes two new high-capacity tunnel tubes, approximately 2 miles in length, designed for electrified Amtrak and MARC passenger trains.

Ellicott City
Extended North Tunnel
Kiewit-Traylor
The Extended North Tunnel, will be about 5,000 ft long, 18 ft in diameter and run up to 100 ft underground, just north of Main Street in Ellicott City, Maryland. The tunnel will carry 26,000 gallons of stormwater per second away from streets and foundations of Ellicott City and the West End and directly into the Patapsco River. The Extended North Tunnel is one of seven flood mitigation projects in the EC Safe and Sound Plan as a result of recent catastrophic flooding in the area.

In April 2022, Howard County announced that it had reached an agreement with Kiewit-Traylor to serve as constructor manager-at-risk for the project. In May 2022, the EPA announced a $75 million Water Infrastructure Finance and Innovation Act (WIFIA) loan to the owner, Howard County, Maryland, to support the Ellicott City Safe and Sound Plan projects.

In June 2024, Howard County held a ceremonial groundbreaking event for the project. Shaft sinking commenced in December 2024. Project completion is expected in 2027.

As a separate contract as part of the same program, Kiewit is installing 10-ft jacked tunnels under CSX railroad lines.

MISSOURI

St. Louis
Lower Meramec Tunnel (11746)
Affholder
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 was mined utilizing a TBM entirely within limestone, shale and dolomite rock with two required construction shafts and six drop structures. The project is approximately 79 % 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 completed mining the 35,903 ft long tunnel on October 18, 2024 . The contractor has also hand mined the six drop shaft adits. The carrier pipe is scheduled to start installation in February 2025. Final completion is anticipated by Nov. 20, 2025.

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 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.

The Tunnel Designer is WSP as a subconsultant to HDR Engineering, Inc. The Construction Manager for the project is Black & Veatch. Major Subcontractors – Bates Construction, Williams Tunneling, J&J Boring; Hayward Baker; TBM Manufacturer – Robbins.

Personnel: Metropolitan St. Louis Sewer District – Design Project Manager: Jerry Jung; Construction Project Manager: Ray Scherrer. Tunnel Design Engineer: Everett Litton, WSP. Construction Manager: Clay Haynes, Black & Veatch: SAK – Project Manager: Jim Buckley. Project Engineer: Patrick Niemuth. Tunnel Division Safety Manager: Jack Lynch. Safety Manager: Matt Muscarella. Project Superintendent: Christopher Gunter.

OHIO

Akron
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.

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 lf of precast-concrete-segmental-lined rock tunnel with a finished inside diameter of 16.5 ft, 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 also includes the 2,200-ft, 10-ft ID long Rack 32 ancillary tunnel. The EPB TBM was lowered in November 2024 for that portion of the project. The TBM for the main tunnel drive completed its Factory Acceptance Test in Germany in September 2024 and is being prepared for launch. Project completion is scheduled for 2027.

Cleveland
Shoreline Tunnel and Consolidation Project
McNally/Kiewit SST JV
This is part of the Northeast Ohio Regional Sewer District’s Project Clean Lake CSO program. The Shoreline Tunnel and Consolidation Project is a $201 million project that involves 14,100 ft of 23-ft ID soft ground tunnel using a 26-ft OD Herrenknecht EPB. NTP was issued in 2021. Mining was completed in May 2024. Final completion is expected this year.

Cleveland
Southerly Tunnel and Consolidation
McNally Tunneling Corp.
Another component of Project Clean Lake, the Southerly Tunnel is a $328 million project involving 18,060 ft of 23-ft ID tunnel using a TBM: 26-ft OD refurbished Herrenknecht EPB. NTP was issued in April 2024. Completion is scheduled for 2028. With this project, six of the seven projects involving large tunnels are completed or are in construction.

Columbus
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 ft. 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.

NEW YORK

Mount Pleasant
Kensico-Eastview Connection
Frontier-Kemper Constructors
In fall 2024Frontier-Kemper Constructors was awarded a contract valued at approximately $1.1 billion by the New York City Department of Environmental Protection for the Kensico-Eastview Connection Tunnel Project.

The scope of work entails the construction of a new deep rock tunnel between the Kensico Reservoir and the Catskill/Delaware Ultraviolet (CDUV) Light Disinfection Facility, both in Westchester County, New York. The new tunnel will provide an additional means of conveying water between the Kensico Reservoir and the CDUV Facility, enhancing operational resiliency and redundancy for New York City’s water supply system.

The new tunnel will run approximately 500 ft below ground and extend approximately 2 miles. The finished tunnel will be 27 ft in diameter. Included in the project are two large shafts to accommodate TBM launch and retrieval. NTP was expected in early 2025 with substantial completion expected in 2030.

RHODE ISLAND

Pawtucket/East Providence
Pawtucket Tunnel
CB3A
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 Pawtucket Tunnel is 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.

Tunneling was started in September 2022 and was completed in February 2024. Final project completion was expected by 2028.

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.

VIRGINIA

Alexandria
RiverRenew Tunnel
Traylor-Shea
The RiverRenew Tunnel System Project includes a 2.2-mile-long, 12-ft-wide tunnel, shafts, and other sewer infrastructure that will help prevent about 180 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 was completed in March 2024. The project also includes the Hoofs Run Interceptor, which is also complete. Project completion is expected in 2026.

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

Loudoun County
Milestone Reservoir and Pump Station
Drill Tech Drilling & Shoring
Drill Tech Drilling & Shoring, Inc. has been awarded this unique $42.2 million project that will ultimately allow Loudoun Water to temporarily store 1 billion gallons of raw water in an abandoned rock quarry prior to treatment.

Under contract with Clark Construction Group, LLC, Drill Tech will excavate and support a large diameter shaft and three separate intake tunnels utilizing drill and blast methods. Excavation of two of the three intake tunnels will start from within the shaft and will terminate into the abandoned quarry. The third tunnel will be excavated from a ledge within the quarry.

The Pump Station Shaft has been excavated and supported down to Tunnel A (El. 136). Now that Tunnel A excavation and support work is complete, Drill Tech personnel will resume Pump Station Shaft excavation down to Tunnel B (El. 65). Once shaft excavation reaches this elevation, Tunnel B excavation will begin.
Drill Tech personnel have also completed excavation of Tunnel C starting within the abandoned quarry.

Drill and blast methods were used to excavate this tunnel to the Pump Station Shaft design invert. A shotcrete lining, concrete invert, and 36 in. steel pipe will soon be placed within Tunnel C.
Raise bore excavation work was expected to begin in February 2025 from within Tunnel C to the ground surface adjacent to the Pump Station Shaft. After completion, a 42 in. steel pipe will be grouted within the raise bore excavation.

Special/unique features of the job include dewatering and treatment of over 200 million gallons of water from the abandoned quarry; scaling and rock fall support installed within the quarry above the three tunnel portals; and blasting near sensitive areas including the Washington & Old Dominion Trail.
The project is approximately 30% complete. NTP was issued March 20, 2024. Completion is estimated for January 2026

Tunnel & Shaft Designer: Arcadis; Construction Manager at Risk: Clark Construction Group, LLC; Major Subcontractors: Balter Company (geotechnical instrumentation and monitoring).

Personnel: Drill Tech Drilling & Shoring, Inc. – Project Executive: Brent Duncan, PE; Project Manager: Kyle White & Alex Steadman; General Superintendent: Mike Belderrain; Site Superintendent: Travis Thomas; Project Engineer: Justin Bayer; Safety Manager: Gilbert Prather

Norfolk
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 completed mining of the first tunnel drive in April 2024. The TBM recorded a best day of 17 rings –more than 113 ft. The TBM was then turned around in the shaft to re-launch the southbound drive. Mining resumed in October 2024.

Norfolk
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. However, after mining 700 ft, the TBM was stopped after encountering an old, buried anchor in the seabed.

From June 2023 to early December 2023, CTJV developed a plan that included the construction of a safe haven into which the TBM could be driven to allow for a maintenance intervention. This plan involved performing ground improvements of the soil in and around the cutterhead. These improvements were completed by injecting foam grout to seal the area around the cutterhead and between the cutterhead and the safe haven located in front of the TBM. This was all done to prevent any potential cave-ins, or blow-outs, at the cutterhead. By grouting the ground in front of the TBM, CTJV was able to pressurize the excavation chamber and prevent water and sand from flowing into the excavation chamber.

Bulkheads at the front of the TBM, with air-lock chambers, allowed workers to gain access to the cutterhead for inspection, remove any remaining anchor debris and replace any damaged tools. All of this work was completed underground, under the seabed, in front of the TBM.

Upon removal of the anchor pieces, CTJV then performed a full inspection of the cutterhead. It was determined that 389 of the 442 tools on the cutterhead required replacement. A total of 48 wear plates were also replaced.

On April 8, 2024, CTJV began tunneling once again. Jan. 27, 2025, marked a major milestone as the TBM broke through to the receiving pit on Two Island at Thimble Shoal Channel. The TBM averaged about 50 ft per day after mining resumed.

Looking ahead, CTJV will begin to construct the roadway inside the tunnel, install the electrical/mechanical systems and construct the support buildings. Once complete, the new tunnel will carry two lanes of traffic southbound and the existing tunnel will carry two lanes of traffic northbound.

Current forecast for project completion is early 2028.

WASHINGTON

Shelton
RM18-1806 NAVFAC Repair Railroad Culverts
Drill Tech Mining & Tunneling, Inc.
Work is complete on the RM18-1806 Repair Railroad Culverts Project for NAVFAC Northwest. The project involves construction of two 20-ft wide by 15-ft tall fish passage culverts, 235 and 160 ft in length, beneath an active section of the Shelton-Bangor-Bremerton Rail Line with limited cover (30 and 50 ft). The goal of the project is to replace existing 48-in. culverts with fish passable structures and improve fish passage in the area without impacting rail operations.

Drill Tech Mining & Tunneling, Inc. (DTMT) was selected by Advanced Technology Construction as the design-build tunneling subcontractor with a contract value of approximately $11.5 million. Soft ground tunnel excavation was completed using mechanical methods, with ground conditions consisting of alluvium and glacial outwash type soils. Canopy tubes were installed for pre-excavation support and the tunnel support system consisted of liner plate with internal steel arches on 4-ft centers. The tunneling portion of the project included pre-excavation support (canopy tubes), tunnel excavation and support, contact grouting, tunnel shotcrete, and tunnel invert.

Tunnel Designer: FK Engineering Associates & Drill Tech Mining & Tunneling; General Contractor: Advanced Technology Construction.

Personnel: Tunnel Support Design Engineer: Joseph Alberts, PE; Pre-Excavation Support Design Engineer: Ryan Carroll, PE; General Contractor – Advanced Technology Construction; Project Manager – Chuck Allaire; Tunneling Subcontractor – Drill Tech Mining & Tunneling, Inc.: Project Manager – Ryan Carroll, PE; Superintendent – Mike Conner; Project Engineer – John Joyce.