Precision Tunneling at Its Finest – Denver International Airport

What started as an ambitious plan to mitigate environmental hazards from airplane de-icing fluid turned into a textbook case of innovation, collaboration, and resilience. Welcome to the story of Denver International Airport’s underground engineering masterpiece.

A CRITICAL CHALLENGE

At the heart of this project was a pressing environmental goal: to stop airplane de-icing fluid from contaminating local waters. The solution? A state-of-the-art drainage tunnel system built directly beneath one of the world’s busiest airports.

But executing this plan required overcoming challenges rarely seen in traditional construction—working below active runways, contending with complex soils, and ensuring full FAA compliance without disrupting airport operations.

THE RIGHT TOOL FOR THE JOB

To dig beneath DIA, the team used “Maverick,” a manned 132-inch diameter Single Shield Tunnel Boring Machine (TBM). Instead of buying new equipment, Southland modified an existing TBM—cutting costs and boosting efficiency.

Precision open-face tunneling tackled everything from cohesive sandstone to sand-like non-cohesive soils that risked tunnel stability. It was a real-world test of adaptability and expertise.

ENGINEERING AROUND THE CLOCK

From winter freeze to FAA red tape, this project threw everything at the team. Some major milestones included:

• Weekly coordination with subcontractors and FAA

• Tunneling only when de-icing pads were closed

• Redesigning equipment to fit tight specs

• Overcoming staffing challenges due to strict background checks

Every tunnel ring, every pipe segment, and every gate valve was placed with zero margin for error.

SUSTAINABILITY IN ACTION

This project was about more than just digging a tunnel—it was about building smarter:

• Recycled water and waste management systems

• Repurposed runway edge lights for tunnel monitoring

• Strategic design to reduce environmental impact

The result? An Envision Gold rating for sustainable construction—one of the highest honors in green infrastructure.

LESSONS FROM BELOW

Building a tunnel under a functioning airport is like threading a needle—with jet engines roaring overhead. The team had to:

• Manage dewatering to prevent contaminated runoff

• Camouflage monitoring systems to avoid disrupting runway operations

• Adapt to unexpected conditions like swelling clay and loose sand

Through it all, safety and precision remained the top priority.

PROJECT HIGHLIGHTS

• TBM Maverick: 132-inch diameter

• 4,400 linear feet of 72″ & 90″ FRP pipe

• 4 pond cells totaling 21.6 million gallons of capacity

• 1-million-gallon DIW storage tank

• Pump Station with 4 pumps

• Constructed under active taxiways, a runway, and a de-icing pad

A BLUEPRINT FOR THE FUTURE

The West Gates DIW Pond Expansion isn’t just a feat of underground engineering—it’s a case study in modern collaboration and creative problem-solving. From innovative tunneling to environmental stewardship, this project sets a new benchmark for what’s possible beneath our feet.

Next time you’re flying through Denver, just remember: some of the most remarkable infrastructure is the part you never see.