Tunnel Stabilization and Sewer Pipeline Replacement
Approved by the South Coast Water District Board of Directors in 2010 and the City of Laguna Beach in late 2013, the Tunnel Stabilization & Sewer Pipeline Replacement Project (Tunnel Project) is a 100-year solution to protect the environment, local economies and neighboring communities. The project comprises two key components:
- Tunnel Stabilization: The District will enlarge the size of the tunnel from an average of 6 to 9 ft. This will ensure safer working conditions and greater access for future pipeline maintenance and repair. Permanent shotcrete lining and steel supports will be installed at several locations where required, replacing rotten timber supports and removal of loose rock that currently exist.
- Pipeline Replacement: The District will install a new 24-in. pipeline throughout the tunnel. The current pipeline – also 24 in. in diameter – will be encased in concrete, but preserved for redundancy and emergency use.
The cost to repair the tunnel is estimated at approximately $90 million and will be funded through low-interest state loans, grants and the District’s general fund. Shortlisted tunnel contractors announcement was anticipated for 2014-2015 with request for bids expected in 2015 and NTP in 2015-2016.
The North East Interceptor Sewer (NEIS) Phase 2A
The North East Interceptor Sewer (NEIS) Phase 2A project is currently the northern extension of the NEIS Phase 1 project. The project will construct approximately 3.03 miles of 8-ft diameter sewer in tunnel and associated structures. The sewer will be constructed from the Division St. Shaft site, near the intersection of San Fernando Road and Cazador Street and terminate at the northern overflow parking lot for the Pony and Train Rides in Griffith Park, just north of the I-5 Griffith Park On/Off Ramps (I-5 Shaft Site) east of Crystal Springs Drive. In addition, this project will also construct approximately 0.76 miles of 7-ft diameter sewer in tunnel and associated structures. This 7-ft diameter sewer has been called the NOS Extension. The sewer traverses from the I-5 shaft site to the Recreation and Parks Central Yard, which is south of LA Glendale Water Reclamation plant (LAGWRP) and connects to the existing North Outfall Sewer (NOS) near Baywood Street.
The expected construction duration is from July 29, 2015 to Jan. 12, 2019. The estimated construction cost is $162,686,700.
Clearwater Program Effluent Outfall Tunnel
The Clearwater Program Joint Water Pollution Control Plant (JWPCP) Effluent Outfall Tunnel is part of an extensive planning 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 replace the existing 8- and 12-ft tunnels with a new 37,000-lf, 18-ft ID 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. The geotechnical exploration should be completed by March 2015. Project advertising and bidding is anticipated to occur in early 2016.
Delta Habitat Conservation and Conveyance Program
The Delta Habitat Conservation and Conveyance Program (DHCCP) is a comprehensive effort to improve the environmental sustainability of California’s Sacramento-San Joaquin Delta region, and ensure the reliability of water deliveries throughout the state. Key components of the program include a series of water conveyance tunnels that will allow for transport of up to 9,000 cfs of water directly from the Sacramento River to the major export pumping plants in the south end of the Delta. The components of this program will replace the current water diversion activities which rely on a series of improved channels and canals to move the water southward in the Delta. The program consists of three river intake structures, three major pumping plants, approximately 10 miles of 20-ft and 29-ft ID tunnels, and approximately 60 miles of 40-ft ID main conveyance tunnels. The main conveyance tunnels will be configured in a parallel twin bore arrangement, with tunnel invert depth of averaging approximately 150 ft below ground surface. In addition to launching and receiving shafts, a series of ventilation/access shafts will be constructed along each tunnel reach. Current conceptual engineering efforts are supporting the environmental impact documents which are being circulated for public comment as part of the EIR/EIS process. Tunnel design is anticipated to commence in early 2016, with the first tunnel contracts being advertised for construction bids in late-2017 to early-2018. Subsequent tunnel construction packages will be advertised on approximate 6-month intervals following the first contract award. Approximately five to six tunnel construction contracts will be awarded under this program. It is currently anticipated the facilities will be operational by 2028.
The Metropolitan District Commission (MDC) of Hartford, Connecticut, is initiating the first of two large CSO tunnel projects with the pre-qualification of tunnel contractors for the South Hartford tunnel. A pre-qualification RFQ is expected to be released prior to the end of 2014 with construction bidding scheduled for September 2015. Interested Contractors may register with the MDC’s ebid system at www.ebidexchange.com/mdc to receive notifications and access RFQ documents. A non-mandatory pre-submittal meeting will be held with interested contractors shortly after the release of the RFQ. The second tunnel, known as the North Tunnel Extension, is being initiated with a Basis of Design Report in early 2015 with construction bidding planned for 2018.
Work in the South Hartford tunnel contract will include construction of an 18-ft finished (lined) diameter tunnel 21,800 ft in length in deep rock, launch shaft, retrieval shaft, pump station excavation shaft, eight drop shafts, adits, six de-aeration chambers and odor control at potential release points. The launch shaft is to be excavated at 38 ft diameter, the retrieval shaft at 33 ft diameter, and the pump station shaft at 74 ft diameter. The drop shaft diameters vary from 42 to 72 in. The estimated construction duration is 54 months.
At this time, the liner will be at the option of the contractor and may be either a cast-in-place liner or a pre-cast liner. This is subject to change as the design is finalized. The contract documents will include a geotechnical data report, a geotechnical baseline report and dispute resolution board participation. Escrowed bid documents will also be required.
The completion of the overall South Hartford project will also include three additional construction contracts for the fit out of the tunnel pump station along with two consolidation conduit contracts to convey flows from current overflow locations to the drop shafts. The consolidation contracts will be bid in 2016 and the tunnel pump station fit out in 2017.
Both the South Hartford tunnel and the North Tunnel Extension are required components of a Federal Consent Decree and a State Consent Order. The tunnels are major components of the MDC’s Clean Water Project and will complement the Hartford water pollution control plant’s expansion to treat wet weather flows up to 200 mgd.
Local voters have already authorized funding for the Hartford plant expansion, the design and construction of the South Hartford Tunnel and the Basis of Design Report on the North Tunnel Extension. Supplemental funding is anticipated from the Connecticut Department of Energy and Environmental Protection (DEEP) for all of these projects. With the funding comes the requirement of 6% minority business enterprise and 5% women business enterprise participation.
The North Tunnel Extension will be similar in size and length as the South Tunnel. Final diameter, length and route will be determined in the Basis of Design Report to be concluded in early 2016.
DISTRICT OF COLUMBIA
Northeast Boundary Tunnel
The Northeast Boundary Tunnel (NEBT) project is a major component of DC Water’s long-term control plan to meet court-ordered combined sewer overflow (CSO) control objectives, water quality standards, and provide flood relief. The NEBT would provide the last increment of CSO storage capacity for the Anacostia River required by the Consent Decree and would also serve to mitigate the occurrence of sewer flooding and basement backups in the Northeast Boundary drainage area.
Major characteristics of the NEBT include: Installation of 27,000-ft long, 23-ft diameter reinforced concrete tunnel; tunnel depths of 50-160 ft below the ground surface using a TBM; diversion facilities sited near chronic flood areas to relieve the existing sewer system and divert flows to the tunnel during storm events; and ventilation control facilities constructed to regulate air flow in the tunnel system.
Total construction cost of the NEBT project is estimated at more than $500 million. Construction of the tunnel and supporting infrastructure would begin in 2017 and is scheduled to be completed in 2022. When completed, the Anacostia River Projects, which include the NEBT, are expected to reduce the annual volume of CSOs to the Anacostia River by 98 percent, and number of overflows from 82 to 2 in an average year of rainfall.
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. A draft EIS is estimated to be released to public/agencies is spring 2015.
Three Rivers Protection and Overflow Reduction Tunnel
The $150 million Ft. Wayne CSO tunnel project, known as Ft. Wayne Three Rivers Protection and Overflow Reduction Tunnel (3R-PORT), is part of an EPA-mandated program to reduce combined sewer overflows into area waterways. The tunnel project includes 5 miles of 12-ft ID tunnel, 2 miles of 24- to 108-in. consolidation sewers, and 13 drop shafts. The tunnel will be constructed at an average depth of 150 ft with construction shafts expected to be up to 40 ft in diameter.
Additionally, the program includes the Foster Park Relief Sewer, an upstream extension of the tunnel that involves the construction of 2 miles of 48- to 84-in. sewer, and a 20 mgd dewatering pump station. Consultants include Black & Veatch, Arcadis and CH2M Hill.
Pleasant Run Deep Tunnel
The Pleasant Run Deep Tunnel (PRDT) will be an 18-ft ID tunnel nearly 33,000 ft in length and approximately 250 ft deep. The PRDT is anticipated to be constructed in limestone and dolomite using a main beam TBM. The tunnel alignment will have two 35-ft finished diameter shafts, one tunnel working shaft and one TBM retrieval shaft. Eight drop shaft vortex structures will be required to drop flows into the tunnel. Solicitation for construction is anticipated to occur in 2020.
Lower Pogues Run Tunnel
The Lower Pogues Run Tunnel (LPgRT) will be an 18-ft finished diameter tunnel approximately 10,000 ft in length and approximately 250 ft deep. The LPgRT is anticipated to be constructed in limestone, dolomitic limestone and dolomite using a main beam TBM. The project will use trenchless technology and open cut methods to install 20- to 50-ft deep consolidation sewers, which are anticipated to be up to 8 ft in diameter. Three drop shafts will be required to convey flow into the tunnel from six combined sewer overflows that currently discharge into Lower Pogues Run. Solicitation for construction is anticipated to occur in 2016.
Fall Creek/White River Tunnel System
The Fall Creek/White River Tunnel System (FCWRTS) is anticipated to be an 18-ft finished diameter tunnel approximately 48,000 ft in length. The FCWRTS consists of two segments; the Fall Creek Tunnel Segment, having a length of approximately 20,000 ft, and the White River Tunnel Segment, having a length of approximately 28,000 ft. The tunnel will be an average of 250 ft deep and is anticipated to be constructed in limestone and dolomite using a main beam TBM.
Deep tunnel access shafts are anticipated to be up to 35 ft finished diameter. Twenty drop shaft vortex structures will be required to convey flow into the tunnel from dozens of combined sewer overflows that currently discharge in Fall Creek and the White River. Solicitation for construction is anticipated to occur in 2016.
The proposed Red Line is a 14.1-mile, east-west transit line connecting the areas of Woodlawn, Edmondson Village, West Baltimore, downtown Baltimore, Harbor East, Fell’s Point, Canton and the Johns Hopkins Bayview Medical Center Campus. It includes 19 stations, five of which would be underground. The 14.1-mile long alignment includes two tunneled sections – Cooks Lane and Downtown tunnels – totaling 4.7 miles. NTP for the first major construction contracts is anticipated for 3rd quarter 2015 with the line operational in 2022.
Delaware Aqueduct By pass Project
The Delaware Aqueduct Bypass Project is being managed by the New York City Department of Environmental Protection to fix two leaks in the Delaware Aqueduct. The project involves building a 2.5-mile bypass tunnel roughly 600 ft under the Hudson River from Newburgh to Wappinger. The bypass tunnel will replace a portion of the existing Delaware Aqueduct that is leaking in Newburgh, N.Y. Once the bypass is finished, the leaking portion of the existing tunnel will be taken out of service. The project will also use grouting to address a series of smaller cracks in the aqueduct in Wawarsing, N.Y. The two cracked sections of the aqueduct are currently leaking roughly 15 to 35 million gallons each day, depending on the amount of flow in the aqueduct. The bypass tunnel project is split between two contracts. The first (known as BT-1) began in earnest last year. Through that contract, two 30-ft diameter shafts will be built on either side of the Hudson River to allow access to the subsurface. The shaft in Newburgh will be built to a depth of 900 ft and the shaft in Wappinger will be built to a depth of 700 ft. BT-1 is expected to be complete sometime in 2016. The second contract (known as BT-2) involves the use of a tunnel-boring machine to drill the 22-ft diameter bypass tunnel. That portion of the project was expected to begin in 2015. It also includes the connection of the bypass to structurally sound portions of the existing Delaware Aqueduct, and the grouting in Wawarsing. That project is expected to reach substantial completion sometime around 2021. The two contracts comprise roughly $1 billion.
The bypass tunnel is part of a larger suite of projects known as Water for the Future, which totals roughly $1.5 billion. These projects also include some structural upgrades to the Catskill Aqueduct, the rehabilitation of a system of groundwater wells in Queens, and a number of conservation projects that will help New York City conserve water. Web: www.nyc.gov/html/waterforthefuture/index.shtml
Dugway Storage Tunnel
This project includes the installation of a 24-ft diameter storage tunnel extending approximately 15,000 ft in length from its connection to the Euclid Creek Tunnel (ECT) at the Nine Mile Site to its terminus near Superior Avenue/ Lakeview Road. The Dugway Storage Tunnel (DST) will be constructed with a tunnel boring machine (TBM) in Chagrin Shale at depths approaching 200 ft below ground level. The DST will also include several consolidation sewers, diversion structures, and drop shafts to capture and store CSO from the DST service area. The diversion systems feeding the drop structures will be equipped with the inflow control gates to manage the dynamic flow within the ECT/DST tunnel system. Salini Impregilo signed a $153 million contract to build the project.
Doan Valley Storage Tunnel
This 17-ft diameter tunnel will extend 9,700 ft. RFP issue: fourth quarter, 2015; design award: first quarter, 2016; construction award: fourth quarter 2017. Estimated cost: $104.5 million.
Westerly Main CSO Storage Tunnel
The tunnel consists of 12,300 ft of 24-ft diameter tunnel. RFP issue: third quarter, 2016; design award: fourth quarter, 2016; construction award: second quarter 2020. Estimated cost: $180.3 million.
Combined Sewer Storage Tunnel
The City of Ottawa is in the process of designing its Combined Sewer Storage Tunnel (CSST), an estimated $195 million project to reduce overflows and improve water quality in the Ottawa River. The CSST will include two tunnels – the 4.4 km East-West Tunnel and the 2.2-km North-South Tunnel. The tunnel diameters are expected to by about 3 m. The design team includes Stantec, CH2M Hill, Golder Associates and Jacobs Associates. Tender award was expected by May 2015 with construction anticipated to last two to three years.