Our firm designs groundwater control and waterproofing systems for a variety of underground applications, including airport, pedestrian, transportation and utility tunnels; and occupied underground spaces.
Airport Mined Tunnel Waterproofing
A new ramp was built directly over an existing underground Light Rail Transit (LRT) station and twin subway tunnels. The ramp configuration required designing the relocation of the LRT ventilation tunnel and shaft. Water control included grout injection into bedrock joins and installation of waterproofing membranes in the tunnel perimeter before concrete tunnel liner placement.
This photo shows the condition before water control measures.
Groundwater Control & Waterproofing
Existing Utility Tunnel Water Control
Amidst a busy University, a 100-year-old steam tunnel needed extensive rehabilitation, which included a waterproofing system and a structural tunnel load transfer slab. The water infiltration into the tunnel was causing spalled concrete walls, corroded pipe supports, and heaved concrete floors.
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The design included a thermoplastic/bentonite composite waterproofing membrane on the roof and walls.
The use of 3D finite element analysis was critical to this project to design a transfer slab supported on micropiles.
Airport Cut and Cover Tunnel Waterproofing
CNA designed the waterproofing system or four cut and cover tunnels that were constructed into the groundwater table. Over 500,000 square feet was installed on four tunnels used for vehicle movement on the airfield.
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CNA also performed quality assurance and field observations during construction.
Pedestrian Tunnel Waterproofing
As a prime consultant for this critical tunnel connection at the State Capitol, CNA's technical leadership was needed to manage the team for a wide range of design elements, including architecture and civil geotechnical, structural, mechanical, electrical engineering. The work included risk-assessment and resolving utility conflict issues.
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This cut and cover tunnel was designed with center divider wall to separate pedestrian traffic and deliveries. The tunnel was designed for a 25-ft span and only 2 ft of cover and needed to withstand simultaneous truck and LRT train loads. The tunnel is completely encased in a waterproofing membrane with integral back up drains.