Dartford Tunnel East – London, England

The tunnel, which carries traffic on the M25 London Orbital Motorway under the Thames River started leaking in a number of places. Total water make was 350 liters per minute. After several unsuccessful attempts by others to adequately seal the water, Sovereign mobilized in September 1989 to perform a trial sealing exercise on the worst 100 meter section. Within 6 shifts, the total water make in the tunnel was reduced to an acceptable rate of 125 liters per minute. An August 1992 inspection certified that no further leaks had developed in the 100 meter SCEM66 trial area.

Gwithian Outfall Shaft, Penzance – Cornwall, England

The new Penzance/St. Ives Sewerage Scheme in Cornwall required the sinking of a 6.1-meter diameter shaft to a depth of 60 meters on the shore at Gwithian, to provide access to a 2.1 km long outfall tunnel to be driven out beneath St. Ives Bay. Initial ground support through the upper water-bearing sands, gravels and fractured killas (metamorphosed sedimentary rock marginal to igneous intrusions) was by precast concrete sections.

High water inflows were encountered while sinking through the water-bearing strata. Despite attempts to control water through backwall grouting with cement, the water make increased to over 1560 liters per minute at the base of the water-bearing interval at 35 meters depth. Due to the high inflow rate, cement grouting, even with use of bridging materials, was unsuccessful.

SCEMm66 was modified to yield the desired coagulation characteristics in the fast-flowing, saline water. After injection through the segmental lining over a 9 shift period, the water inflow was reduced from 1560 liters per minute to 114 liters per minute.

Aldersgate Car Park – London, England

A one-meter thick, 30-meter long diaphragm wall build during construction of the car park started leaking. The leaks we very slight and ranged from “a drip a minute” to “beads of water on damp concrete”. Benefitting from its colloidal particle size, SCEM66 was used to successful seal the leaks.

Resort Hotel, Brighton Beach – Sydney, Australia

The Resort Hotel, Brighton Beach was designed to provide 10 stories of 5 star hotel and office accommodations overlooking Botany Bay.

2019 MBTA Boston
Downtown Crossing, China Town, State Street, Haymarket Station

HIghlights

• Leak remediation with NOH2O® in historically protected surroundings
• Minimal impact to the traveling public
• Permanent leak remediation in areas with high foot traffic

Project Overview
Boston’s MBTA Wayfinding Improvement and Station Rehabilitation program called for leak remediation at several underground subway stations below and neighboring with historical buildings and structures. Downtown Crossing, China Town, State Street and Haymarket Station have several entrances as well as below grade passage- and stairways that connect the Orange, Red, Blue and Green subway lines. Water leaks have have resulted in partial closures of these during and after rain events.

Strategy
Sovereign conducted individual site and historical research which resulted in a multi-phased plan to stop water infiltration into areas which were preselected by the MBTA, and where the public has the most access to.

Results
All pre selected areas were treated with NOH2O®, which created an impermeable water barrier along the outer structure and at interfaces with existing structures as well as selected areas where single point injections to ensure that the clients expectations were exceeded.

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2018 MTA Bridges and Tunnels - Hugh Carey – Brooklyn Battery Tunnel

HIghlights

• Sealed ~70 leaking tunnel joints in 6 months
• Use of patented injectable bolts to deliver NOH2O® through cast iron tunnel liner joints
• Exceeded client specified dryness criteria

Project Overview
The Brooklyn–Battery Tunnel (officially the Hugh L. Carey Tunnel) is a toll tunnel in New York City that connects Red Hook in Brooklyn with Battery Park in Manhattan. It was placed into service in 1950. The tunnel consists of twin tubes that each carry two traffic lanes under the mouth of the East River. With a length of 9,117 feet, the Brooklyn–Battery Tunnel is the longest continuous underwater vehicular tunnel in North America.

The Tunnel has elements of cast-in-place liner as well as cast iron segments with an inner cast-in-place concrete protective lining. NOH2O® was delivered through the cast-in-place liner via drilled holes to the surrounding rock. Leaks from ~ 70 cast iron segment joints were sealed by replacing standard bolts from the cast iron segments with patented injectable bolts. Through these bolts NOH2O® was injected and sealed the segment joints. In addition, the NOH2O® injected through the bolts sealed adjacent leaks at other segment joints.

Strategy
Sovereign engineered, manufactured and tested injectable replacement bolts connecting the flanges of the tunnels’ cast iron segments to be used as injection ports for NOH2O®.

Results
The application of injectable replacement bolts was the first use of this type of water sealing method for a multi-lane vehicle tunnel. This method has proven to be very successful for the rehabilitation of cast iron lined tunnels throughout the New York area.

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2017-19 MTA - New York City Transit – Enhanced Station Initiative

Highlights

• NYCT Subway Station rehabilitation program utilizing NOH2O® as primary waterproofing.
• Design-Build project delivery with 10-year performance warranty
• Night and weekend work shifts to make room for other trades
• NOH2O® was selected over 6 other types of leak mitigation

Project Overview
NYCT’s Enhanced Station Initiative (ESI) Program covers the modernization of 19 stations, some of which have been in operation for more than a century. The stations feature renewed finishes, necessary structural repairs and waterproofing.

Strategy
Sovereign, as part of design-build teams, identified water leak areas, reviewed existing structural conditions, engineered and implemented leak remediation at 12 subway stations. Specific areas included entry/exit stairways, large mezzanine levels as well as walls and ceilings of train platforms.

Results
The application of NOH2O® sealing off water leakage to from critical communication infrastructure ensures that the traveling public receives live travel time information and reliable WiFi and cell phone service.

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2016 MTA New York City Transit – 34th Street - Hudson Yards Station

Highlights

• NOH2O® is permanent leak remediation
• Performance is warrantied
• Minimal impact to station operations - zero impact to revenue service
• Previous grout attempts, by others, failed

Project Overview
NYCT’s 34th Street -Hudson Yards Subway Station, which opened to the public in September 2015 was plagued with water infiltration very shortly after its opening. The extent of this impacted the operation of escalators as well as slippery walking surfaces and damage to the architectural finish out. In 2016 Sovereign was tasked to engineer a solution and apply NOH2O® to mitiagate this impact to the station’s operation and unsighly condition.

Strategy
Sovereign developed a two Phase approach/plan. Phase 1 treated areas accessible and visible to the public and Phase 2 addressed the non-public concourse areas and a ventilation shaft.

Results
Phase 1 was completed in 6 weeks; working 12 hour night shifts reduced impact to the public as the Station remained in service throughout the work. Phase 2 was completed in 8 weeks, with varying day/night shifts.

The initially planned duration of the leak remediation work (6 months) was performed in 3 months.

34th Street – Hudson Yards Station is free of unwanted water infiltration.

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2016 NYCT - 2nd Avenue Subway – 63rd Street LIne

HIghlights

• ~54,000 SF of tunnel and crossover treated in 6 months
• Productivity: 250 SF per man-hour
• Schedule savings for track and systems work

Project Overview
The 2nd Avenue Subway extension includes the G3/G4 Tunnels which were constructed in the 1980s. They connects trains from the 7th Avenue line to the 2nd Avenue Subway extension. Structural rehabilitation and leak remediation are required to ensure the design life of the existing structures can meet that of the newly constructed extension.

Curtain grouting 1,850 LF of the G3 Track and 900 LF of the G4 Track with NOH2O® was selected to prevent groundwater inflow so new installations are not damaged. All work in these areas was performed from work train flat cars in the tunnel sections and scaffolds in the crossover areas.

Strategy
Sovereign generated a curtain grouting phasing plan which utilized an optimized work train set-up and scaffolding as well as a modified Jetleg drill with carbide bits to increase the drilling rates and guard against equipment failure from active water inflow.

Results
The production rate of 250 SF per man-hour, including time required for mobilization and follow-up work provided a dry tunnel in a very short time span. This enabled the general contractor to advance track and systems work without delays.

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2015 MTA New York City Transit – South Ferry Terminal Station

Highlights

• First MTA/NYCT application of NOH2O® as a positive side, curtain grouting application
• NOH2O® forms a waterproofing membrane along the outer station and tunnel structures
• 4 months schedule improvement allowed early start of finishes work and systems installation
• NOH2O® was selected over 6 other types of leak mitigation

Project Overview
The South Ferry Terminal Complex was severely damaged by superstorm Sandy in 2012. As a result of the Station being entirely submerged in saltwater the entire Station underwent a total makeover. Prior to this event the Station enhancements had been completed in 2009, however water infiltration remained a problem. In 2015 Sovereign was tasked to engineer a solution and apply NOH2O® to mitiagate water infiltration and ensure a dry Station.

Strategy
Sovereign developed a two Phase approach/plan. Phase 1 treated the entire Station cut & cover box and Phase 2 the adjacent facility rooms and tunnels.

Results
Phase 1 was completed in 8 weeks. Phase 2 was completed in 12 weeks, with varying day/night shifts. The application of NOH2O® forming a membrane along the outside of the station and tunnel structures rendered them dry.

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2014 NYCT Montague Tube Rehabilitation

Highlights

• Selected sections of tunnel treated in 6 months
• Use of patented injectable bolts to deliver NOH2O® through cast iron tunnel liner joints
• Exceeded client specified dryness criteria

Project Overview
The Montague Tunnel, opened to service in 1920, is a New York City Subway tunnel the under the East River between Manhattan and Brooklyn. The R-Line uses the tunnel at all times, the N-Line uses it during late nights, and during rush hours, several W-Line trains per day in each direction use the tunnel.

The Tunnel is approximately 12,000 LF long, includes elements of cast-in-place liner as well as cast iron segments with an inner cast-in-place concrete protective lining. Leaks in the cast iron segments were addressed by replacing standard bolts from the cast iron segments with patented, stainless steel injectable bolts. These bolts were injected with NOH2O® to seal the segment joints. The NOH2O® injected through the bolts equally sealed adjacent leaks in the segment joints.

Strategy
Sovereign engineered, manufactured and tested injectable replacement bolts connecting the flanges of the tunnels cast iron segments.

Results
The application of injectable replacement bolts of this magnitude was the first use of this type of water sealing method for a NYCT owned and operated facility. This method has been utilized at several other similartype tunnels.

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2012 NYCT Steinway Tube – Duct Bench Rehabilitation

Highlights

• Innovative leak remediation with NOH2O® through cast iron tunnel liner
• Drilled and injected NOH2O®through patented bolts
• Work performed during regulary scheduled track outages
• No train service disruption during revenue service hours

Project Overview
The leak mitigation for Steinway Tube comprised of sealing leaks in the tunnel liner behind the existing electrical duct bench. The duct bench was demolished, and wet spots identified. In areas where the liner consisted of cast-in-place concrete, holes were drilled through the liner to inject NOH2O® behind the liner. Where the liner consisted of cast-iron segments, the concrete was chipped out to expose leaking bolts. The leaking bolts from the original construction were replaced with stainless steel patented bolts of the same diameter that allow injection of NOH2O® into the annulus around bolt hole and bolt. The NOH2O® injected through the bolts also sealed adjacent leaks in the segment joints.

Strategy
Sovereign provided a four-man grouting crew and material to seal a leak documented during the duct bank demolition. The leak was located at the transition between the Manhattan horseshoe and cast-iron sections and originated at the concrete-rock interface and behind a steel liner.

Results
Work was completed on February 7, 2015 in one 12-hour shift using 6 drilled holes, 550 liters of NOH2O®, 80 liters of Inhibitor and 140 liters of Actical 500. Finally, new concrete duct banks were cast.

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