water and wastewater tunnels - mott mac

Water and wastewater tunnelsDesigning sustainable, environmentally friendly solutions

Water I Water and wastewater tunnels

Underground solutions for water and wastewater systems

Today, that infrastructure is challenged by aging structures, increased demand, and competing budget priorities. Water and wastewater systems must cope with new regulations, new contaminants, and increasingly scarce resources.

Tunnels and underground structures are a critical part of that challenge. In the fast-changing world of underground construction, you need advisors who can think laterally and search out the connections that others fail to make.

Mott MacDonald understands and meets this challenge. Our global network of experts never stop asking, “What if?”

We constantly stretch our thinking, imagining elegant solutions for the most complex underground challenges. Yet in our drive for progress we never lose sight of the human impact of our actions.

Mott MacDonald I Water and wastewater tunnels

In the 20th century, municipalities across the US and Canada dedicated themselves to building critical water and wastewater infrastructure. Their success was a major achievement in the history of public health, saving lives and improving the quality of life for millions of people.


Water tunnels North America’s water supply and distribution system is in a constant state of upgrade and expansion. Critical lifelines must remain operational while work continues. Some are located in difficult environments, from pristine mountain areas to active geological faults.

ProjectStanley Park Water Supply Tunnel

LocationVancouver, British Columbia

Client Metro Vancouver

ExpertiseSite investigation, design, cost estimating, risk management, procurement support, construction engineering

Protecting a natural treasure by driving deeper

OpportunityMetro Vancouver and member municipalities work together to supply clean, safe drinking water to more than 2.3 million people in the region. To meet future demand, Metro Vancouver will construct the Stanley Park Water Supply Tunnel, bringing potable water from the Capilano Reservoir on the north shore to downtown Vancouver.

The one-mile (1.4-kilometer) tunnel will pass beneath Stanley Park, a National Historic Site with a variety of trees, animals, and over 200 bird species. Preserving this urban oasis is a top priority.

SolutionMott MacDonald has supported the project since 2016, when we completed an alignment study that considered the technical, environmental, social, and archaeological challenges. In 2018, our multidisciplinary team was brought on to advance the project through design, including completion of site investigation works, construction cost estimating, and risk management.

We have worked closely with Metro Vancouver, regulatory authorities, First Nations, and key stakeholders. To help these groups visualize the project elements, we developed 3D models and virtual reality walkthroughs to bring this important project to life.

OutcomeThe project is progressing through design, with construction expected to begin in 2021 through 2027. When complete, the new tunnel will meet current seismic standards, help ensure the continued reliable delivery of clean, safe drinking water to the region, and increase the capacity of the existing system for the region’s growing population.


ProjectNew York Harbor Water Siphon

LocationNew York, New York

Client New York Economic Development Corporation

ExpertiseDesign

The tunnel is the first of its kind to be built under New York Harbor in decades.

OpportunityThe Port of New York and New Jersey is the third largest port in the US, handling almost 40% of the East Coast shipping trade. But the widening of the Panama Canal has made possible a new generation of megaships, which New York’s Anchorage Channel cannot accommodate. Dredging the channel could compromise two water mains (known as siphons) built in 1917 and 1925 to deliver water to Staten Island.

SolutionAs part of a joint venture, Mott MacDonald evaluated alternatives for replacing the existing siphons with one new and deeper steel siphon. Mott MacDonald designed a siphon 6 feet (1.8 meters) in diameter inside a tunnel 12 feet (3.6 meters) in diameter, along with a new chlorination station on Staten Island able to treat 150 million gallons (568 million liters) of water per day.

OutcomeConstruction of the New York Harbor Water Siphon, the first new tunnel under New York Harbor in many decades, was interrupted by flooding from Superstorm Sandy. Tunneling was completed in 2014, providing a reliable new source of drinking water and opening New York City to new trade opportunities. The project represented the first use of a pressurized face tunneling machine for a subaqueous crossing in New York City.

Water for Staten Island and bigger cargo ships for New York Harbor


A “race against time” to ensure the Bay Area’s water supply

OpportunityIn the late 1920s and early 1930s, miners used drill-and-blast techniques to construct the original 3.5-mile (5.6-kilometer) Irvington Tunnel between Sunol and Fremont, California. For years, the tunnel supplied 85% of San Francisco’s water — but critical elements were vulnerable to seismic activity.

ProjectNew Irvington Tunnel

LocationSan Francisco, California

Client San Francisco Public Utilities Commission

ExpertiseConstruction management

The New Irvington Tunnel carries drinking water to 2.6 million customers, providing much needed redundancy in this seismic region.


SolutionMott MacDonald served as lead construction manager for the New Irvington Tunnel, which parallels the original alignment. The tunnel was excavated using roadheader and drill-and-blast methods rather than tunnel boring machines to provide more access and options while crossing the many faults and shears. The risks of using tunnel boring machines were deemed too high.

OutcomeCompleted in 2015, the New Irvington Tunnel carries drinking water to 2.6 million customers in San Francisco, San Mateo, Santa Clara, and Alameda Counties. The old tunnel has been drained, inspected, and repaired without disrupting service to residents.


Watering the Big Apple

Opportunity Completed in 1916, the Catskill Aqueduct is an engineering marvel, supplying one of the world’s great cities with 581 million gallons (2.2 billion liters) of water a day. Keeping it in good repair is a vital priority.

Solution As part of a New York City Department of Environmental Protection repair and rehabilitation project, Mott MacDonald is applying the latest digital technology to the last 12-mile (20-kilometer) stretch of the aqueduct, known as the Lower Catskill Aqueduct.

We used light detection and ranging (LiDAR) to map the Lower Catskill Aqueduct corridor from the air. We then partnered with Esri, the supplier of geographic information system software, and Autodesk, which provides software solutions for Building Information Modeling (BIM), to combine BIM and geographic information systems (GIS) data in new ways.

All the information gathered on the aqueduct was brought together to build an accurate 3D model using Autodesk InfraWorks, software that enables designers and civil engineers to plan and design infrastructure projects in the context of the real world.Our hybrid digital reality model enabled us to locate the exact position of surface leaks, spalls, cracks, and other defects. We trained computers to identify, tabulate, and quantify each defect, helping to prioritize needed repairs.

OutcomeOur digital approach minimized the need for shutting down the aqueduct, improving the health and safety of engineers by reducing the time needed for work inside the tunnel. Our approach was estimated to reduce the number days for field investigation from 63 to 19 and the number of shutdowns for inspection work by 80%. This helps safeguard the health and safety of engineers by reducing the time needed for work inside the tunnel.

Our approach to field data collection, information management, and BIM resulted in the work being completed ahead of schedule and under budget in the first two years of the project.

By integrating digital workflows in a geographic context, we’re helping to reduce costs and to restore the 100-year-old engineering marvel to a state of good repair and long-term operational reliability — fit for another century.

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ProjectDesign services for the reconstruction of Lower Catskill Aqueduct

LocationNew York State

Client New York City Department of Environmental Protection

ExpertiseCondition assessment, detailed design, facility planning, design services during construction

Top: The Catskill Aqueduct stretches 92 miles (148 kilometers) from the Ashokan Reservoir to New York City.

Bottom: Accurate 3D models gave stakeholders unprecedented insight into the project

Mott MacDonald’s innovative and award-winning design reduced risk, time, and cost while increasing quality and safety.Wastewater tunnels

In many older cities, combined sewers handle sanitary as well as wet-weather flows. These systems may experience overflows during heavy rainfall. One solution is the creation of large storage tunnels that can temporarily store overflows, keeping polluted runoff out of waterways.

OpportunityThe seven large storage tunnels of Project Clean Lake will reduce pollution in Lake Erie by four billion gallons per year.

The construction of the tunnels faced many challenges, including shale rock that slakes or disintegrates when exposed to moisture.

SolutionMott MacDonald was selected to design four of the seven tunnels.

On the Euclid Creek Tunnel, we collaborated successfully with the contractor, machine supplier, grouting specialists, and owner. Our design enabled one-pass construction, reducing scores of underground risks while increasing quality and safety.

ProjectProject Clean Lake: Euclid Creek, Dugway, and Westerly CSO Tunnels

LocationCleveland, Ohio

Client Northeast Ohio Regional Sewer District

ExpertiseTunnel and shaft design, construction management

Outcome On the Euclid Creek Tunnel, our use of concrete segments reinforced with steel fiber cut four months from the construction schedule and saved the client considerable expense.

The innovative and highly successful use of rapid-gel two-part grout in the Euclid Creek Tunnel earned Mott MacDonald and our client several national and international awards. The method has been used on all of the client’s later tunnels.

Cleaner water in Cleveland

The Lee Tunnel in East London helps protect the waters of the River Lee.

ProjectThames Tideway Tunnel

LocationLondon, UK

Client Tideway

ExpertiseDesign

Opportunity The Thames River is one of the most iconic water bodies in the world. However, release of sewage into the Thames detracts from its natural beauty and threatens public health. This project aims to dramatically reduce the discharges in the river. The Thames Tideway Tunnel is the biggest infrastructure project ever undertaken by the British water industry. It will include about 16 miles (26 kilometers) of tunnels constructed beneath London.

Solution In 2016, Mott MacDonald was chosen to design the eastern section of the project, including a 3.4-mile (5.5-kilometer) section of the main tunnel and a 2.9-mile (4.7-kilometer) connecting tunnel for combined rainwater and wastewater — both of which will serve the east of London.


Successful wastewater and stormwater tunnel engineering requires a broad combination of skills: hydraulics, geotechnics, hydrogeology, tunnel design, odor control, corrosion control, and more.

Britain’s biggest wastewater project

OutcomeThe project is designed to make London’s wastewater system ready for the 22nd century, preventing millions of tons of pollution from reaching the Thames each year. Cleaning this valuable water resource will protect the health of millions, while boosting recreational use and civic pride in this beautiful waterway.

Mott MacDonald earlier provided detailed design for three shafts that make up part of the £635 million Lee Tunnel in East London, another Tideway project that prevents wastewater from being discharged into the River Lee.

OutcomeWhen the relief sewers and related hydraulic improvements are completed, the average annual CSO volume will be reduced by 37%, to 285 million gallons. The maximum number of outfall activations will decrease from 42 to 31 per year as measured at the downstream outfall, meeting the mandated water quality goal of the Bronx River’s long-term control plan, and helping protect the waters in and around New York.

OpportunityThe Bronx River, which flows through the Bronx Zoo and the New York Botanical Garden, is the only freshwater river in New York City.

In 2007, local communities agreed to stop dumping sewage into the river, but water quality was still affected by combined sewer overflows (CSOs), averaging 455 million gallons (1.7 billion liters) per year. Protecting this imporant New York City water resource from sewage was a critical goal of this ambitious project.

SolutionThe New York City Department of Environmental Protection planned to construct relief sewers at two outfalls, which would capture and convey overflows to a wastewater treatment plant, using an existing pipeline.

Mott MacDonald was retained as a key subconsultant to plan and design two new relief sewers with an interior diameter of 60 inches (1.5 meters) and 72 inches (1.8 meters). Constructing the sewers will require multiple microtunneling drives totaling about 5,000 feet (1,524 meters) in length. The drives will pass through varying rock and soft-ground geology, under major transportation corridors and parks, and through densely populated communities.

Our responsibilities include geotechnical engineering, underground construction design, structural engineering, and site/civil drainage support.

Reducing Bronx River pollution with microtunneling


ProjectBronx River CSO Abatement

LocationNew York, New York

Client New York City Department of Environmental Protection

ExpertiseGeotechnical engineering and final design

A challenge on the Pacific coast

ProjectLaguna Beach Sewer Tunnel upgrade

LocationLaguna Beach, California

Client South Coast Water District

ExpertisePlanning, alternatives analysis, tunnel inspection, tunnel and pipeline design, cost estimating, risk assessment, construction management, rehabilitation

Top: Tunnel was enlarged using a roadheader, and supported with steel sets and shotcrete.

Bottom: The rehabilitated Laguna Beach Sewer Tunnel will provide 100 years of service.

OpportunityMore than 10,000 feet (3,100 meters) long, the Laguna Beach Sewer Tunnel was constructed inside the ocean-facing cliffs in South Laguna, California, in 1954. It contains a sewer pipeline 24 inches (0.6 meters) in diameter that is critical to the South Coast Water District (SCWD) sewer conveyance system.

Sections of the sewer were in disrepair, threatening the viability of this important infrastructure. In addition, the limited access to this cliffside sewer required creative thinking and innovative solutions. A break in the line would cause spillage of over a million gallons per day and into the ocean.

SolutionMott MacDonald was retained to perform an end-to-end evaluation of the tunnel. One section of the tunnel required emergency repair. Contractor access to the beach was limited to a very steep set of public stairs, so all construction equipment and material were transported to the beach site using workboats capable of beach landings.

Mott MacDonald prepared bid-ready design documents and provided construction management services for the emergency repairs. Once these were complete, Mott MacDonald assisted SCWD with planning, alternatives analysis, permitting, and detailed design for the rehabilitation of the entire tunnel and the replacement of the pipeline.

OutcomeThe rehabilitation projects in the fourth and final phase of construction, scheduled for completion in 2022. The improved facility will provide 100 years of reliable service to the community, excavated materials are being used by SCWD for other benefits, and the existing pipeline will remain for future use as a backup pipe. This will keep the adjacent beach and ocean as a beautiful resource for future generations.


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water and wastewater tunnels - mott mac

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