Clearwater Program Effluent Outfall Tunnel
The Clearwater Program’s Joint Water Pollution Control Plant (JWPCP) Effluent Outfall Tunnel Project is part of an extensive effort by the Sanitation Districts of Los Angeles County to analyze the needs of its Joint Outfall System to the year 2050. The Effluent Outfall Tunnel is envisioned to enhance the existing 8- and 12-ft tunnels with a new 37,000-lf, 18-ft ID post-tensioned concrete segmented lined tunnel. All tunneling work will be done from a single shaft located at the Districts’ JWPCP located in the City of Carson. Structures located at the start and end of the tunnel will connect to the existing Ocean Outfall System facilities.
Bids were submitted in October with final award scheduled for Dec. 12, 2018. Dragados USA submitted a bid of $630,500,000, just under FCC Southland Mole JV’s bid of $630,860,959. Other bids included Lane Obayashi JV ($653,000,000), Skanska Kenny JV ($655,997,000) and Frontier-Kemper Michels JV ($665,700,000). The contract was officially awarded on Jan. 23, 2019.
Construction was anticipated to start Q1 2019.
BART Silicon Valley Extension
On June 4 the Federal Transit Administration issued a Record of Decision for the $4.7 billion, 6-mile BART Silicon Valley Phase II Extension into downtown San Jose. Five miles of the extension are planned to be underground, constructed by a single, large-bore TBM on the order of 45-ft in diameter. The extension includes four stations (three underground). The overall project is a 16-mile extension of the Bay Area Rapid Transit system in the San Francisco Bay area. Cost estimates are in the range of $5 billion. Project construction is planned to start by 2021 with passenger service by 2026. A joint venture of HNTB and WSP agreed to a four-year, $88.3 million program management contract with the owner, Santa Clara Valley Transportation Authority (VTA).
DISTRICT OF COLUMBIA
Potomac River Tunnel Project
The Potomac River Tunnel is a component of DC Water’s long-term control plan (LTCP), also known as the DC Clean Rivers Project. The Consent Decree establishes schedules for construction of the Potomac River Tunnel and other CSO control facilities under the DC Clean Rivers Project, including a 2025 deadline to implement the project in its entirety. The Potomac River Tunnel will be located approximately 100 ft below ground. CSOs captured by the Potomac River Tunnel would be conveyed to the Blue Plains Advanced Wastewater Treatment Plant.
The B&P Tunnel is a planned replacement of the existing B&P Tunnel, which is an integral portion of Amtrak’s Northeast Corridor. The new tunnel would replace the low speed, two-track brick arch tunnel, built in the 1870s with four, new single bore, high speed tunnels. The estimated construction cost is $5 billion, with a construction duration of a decade. The project is on Amtrak’s priority list, along with four other mega-projects – thus awaiting funding.
The FRA and MDOT issued the Final Environmental Impact Statement (FEIS) in November 2016 and the Record of Decision (ROD) was released March 2017.
Hudson Tunnel Project/Gateway
The Hudson Tunnel Project is a new two-track heavy rail tunnel along the Northeast Corridor from the Bergen Palisades in New Jersey to Manhattan that will directly serve Penn Station New York. It consists of three major elements: the Hudson Yards right-of-way preservation project, the Hudson Tunnel, and the rehabilitation and modernization of the existing North River tunnel.
A joint venture of WSP, AECOM and STV has been awarded the design contract. The tunnel portion of the contract, estimated at $13 billion, is envisioned to be a design-build contract including the Palisades Tunnel and Hudson Tunnel. Uncertainties regarding funding is impacting the schedule. The FTA in March rated the Hudson Tunnel a “medium-low,” making it ineligible to receive federal Capital Improvement Grants.
The Hudson Tunnel Project is part of the Northeast Corridor Gateway Program, a series of strategic rail infrastructure investments designed to improve current service and create new capacity. The Port Authority of New York and New Jersey (PANYNJ) currently serves as the project sponsor, but the project is a joint undertaking that also includes Amtrak and New Jersey Transit (NJ TRANSIT).
The existing North River Tunnel, opened in 1910, is owned by Amtrak. NJ TRANSIT and Amtrak operate approximately 450 trains each weekday through the tunnel that carry over 200,000 daily passenger trips. The North River Tunnel presents reliability challenges due to damage from Superstorm Sandy in 2012, as well as the overall age the tunnel and the intensity of its current use. Significant delays to a large number of trains occur when problems arise.
The Narragansett Bay Commission (NBC) has begun conceptual design of the third and final phase of its Combined Sewer Overflow Program. Phase III includes the Pawtucket Tunnel, NBC’s second CSO storage tunnel. NBC completed the Providence Tunnel, a 16,500-ft long, 26-ft diameter CSO storage tunnel, in 2008 during Phase I of its CSO program.
The Pawtucket Tunnel will be approximately 13,000 ft long, 28 ft in diameter and located in bedrock about 200 ft below the ground surface. The contract to construct the Pawtucket Tunnel will include the launch and recovery shafts (which will become permanent access shafts), two to three drop shafts with connecting adits at existing outfall locations, and an underground shaft- or cavern-style tunnel pump station.
Mechanical fit out of the tunnel pump station will be performed under a separate contract. Construction of diversion structures, gate and screening structures and consolidation conduits at existing outfall locations will be performed under separate contracts as well.
The launch shaft and tunnel pump station will be located at NBC’s Bucklin Point Wastewater Treatment Facility in East Providence, Rhode Island. 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 program/construction manager for Phase III is Stantec and its teaming partner Pare Corporation. Construction of the Pawtucket Tunnel is anticipated to begin in late 2020 or early 2021.
Dallas Area Rapid Transit (DART) is well underway with planning and preliminary design of the D2 Subway, which will provide a second light rail alignment through downtown Dallas. Preliminary engineering/project development work is expected to be completed by 202 so that the project can advance to the design-build phase. The targeted opening date is 2024.
Thirty-four borings have been completed since 2016, providing data on conditions up to 120 ft below grade. These borings have revealed the rock types of Austin Chalk (limestone) and Barnett Shale (shale). Upon completion of soil and rock testing, additional evaluations will be performed to help DART determine the most appropriate method(s) to construct the tunnel, stations, and station access portals.
The project budget was $1.3 billion as of October 2016. The project includes 1.3 miles of alignment below grade (2 miles total) and three underground stations (four total).
Flood Control Tunnels
The Harris County Flood Control District is set to receive a federal grant of $320,000 to study the feasibility of building deep tunnels to divert storm water to the Houston Ship Channel, the Houston Chronicle reported on Feb. 20. The four-month study would determine whether the tunnels would be practical and cost-effective in the district’s flood-protection strategy. The district got a $2.5 billion flood bond approved last summer.
Early discussions have the tunnels at least 20 ft diameter and 150 ft deep moving water from upstream bayous to the ship channel, in some cases a distance of 30 miles.
The San Antonio Water System (SAWS), a public utility owned by the City of San Antonio, Texas, is in the process of selecting a consultant for its W-6 Upper Segment: Hwy 90 to SW Military Drive Sewer Main Project.
The estimated $150 million project involves approximately 27,000 lf of 10-ft diameter tunnel to host the new 90-in. FRP gravity sewer pipe. The project also includes installation of about 2,300 lf of 60-in. gravity sewer pipe via open cut. The tunnel depth will vary along the alignment with depths of up to 130 ft. The project includes five launching/receiving shafts with additional smaller access shafts. Geotechnical data is being gathered as design proceeds.
This project is part of SAWS’ compliance with the EPA Consent Decree. The depth and extent of tunneling is beyond that of past sewer projects at SAWS. SAWS invites capable tunnel contractors local, national, and international to submit proposals when the project is advertised in spring of 2020.
The goal is to complete 100% Contract Documents by February 2020, so SAWS can advertise in March 2020. The objective is to award the construction contract in June 2020. Estimated construction duration is a maximum of 36 months.
A joint plan prepared by Alexandria Renew Enterprises (AlexRenew) and the City of Alexandria outlining an approach to remediate a portion of Alexandria’s sewer system built in the late 1800s was been accepted by the Virginia Department of Environmental Quality (DEQ), AlexRenew announced on July 2, 2018. The plan outlines the construction of infrastructure improvements to remediate four outfalls in Alexandria that currently discharge a mixture of rainwater and sewage into Alexandria’s rivers and streams during rain events.
The plan’s infrastructure includes construction of a deep tunnel system, approximately 2 miles long, and new sewer infrastructure to connect the tunnels to the existing sewer system. The plan also includes upgrades to AlexRenew’s Water Resource Recovery Facility to pump and treat wastewater collected in the tunnels. Once completed, the new tunnel system will connect to the existing outfalls to prevent millions of gallons of sewage mixed with rainwater from reaching rivers and streams. Instead of polluting waterways, the sewage and rainwater mixture will be captured by the tunnel system and conveyed to AlexRenew’s Water Resource Recovery Facility to be transformed into clean water and returned to the Potomac River. When the plan is complete, it is estimated to reduce the occurrence of discharges from approximately 60 to less than four times per year, on average. The significant reduction in the frequency and volume of these discharges will achieve cleaner, healthier waterways by reducing the amount of bacteria, trash, and other pollutants that currently impact Hooffs Run, Hunting Creek, and the Potomac River.
AlexRenew, in a partnership with the City of Alexandria, will lead the planning, design, and implementation of the plan to remediate the outfalls by 2025. Additionally, in an effort to minimize impacts to the community, the plan proposes that the AlexRenew facility serve as the main construction point for the proposed tunnel system. AlexRenew will be conducting an extensive outreach program to ensure that the community and regulatory stakeholders are kept informed as the design for the tunnel system kicks off and is developed.
Ship Canal Water Quality Project
Seattle Public Utilities is planning to build a tunnel jointly with King County to reduce the amount of combined sewer overflows into local waterways. Bidding is underway with bids due by May, 22, 2019. The project includes a 2.7-mile long storage tunnel with a diameter of 18 ft, 10 in. excavated by pressurized face TBM 30 to 90 ft below grade. The engineer’s estimate is $219 million. Work also installation of a 646 ft long, 94-in. ID conveyance tunnel under the Lake Washington Ship Canal using a microtunneling machine (MTBM).