Aspen crews use smoke to find rainwater leaks in sewer lines

Aspen’s sewer system is drowning in rainwater. Not sewage. Rain.

That is the hard truth hiding in the pipes beneath the valley floor. The Aspen Consolidated Sanitation District is currently pumping vegetable oil-based smoke through the lines to find the leaks. They are chasing faulty connections and broken lines. The goal is simple: stop the flood.

Starting Monday, crews from TREKK Design began the work. They have already tested around 14,000 feet of sanitary lines. The results in the Aspen Airport Business Center area were stark. They found roughly 30 leaks. That is one leak for every 500 feet of pipe.

The smoke itself is harmless. It is non-toxic, similar to what theaters use on stage. Vernon Schrock, an office technician at TREKK Design Group, calls it "steam." It is odorless. It leaves no residue. If it fills a building, opening a window clears it in minutes. Health complaints are rare. The real issue is what happens when that smoke hits a leak.

It reveals a massive inefficiency in how Aspen treats its water. Faulty connections allow rainwater to pour into the sewage system. This swells the volume at the treatment facility. Average flow sits at about 2 million gallons per day. During a storm, that number jumps to 12 million gallons.

Five times the volume. All from roofs.

"The roof drains typically come from your taller buildings," Schrock explained. "Two to three story buildings where they didn’t have anywhere when they built those for the water to drain off the roof and go somewhere. So they hooked it into the sanitary sewer lines."

Why does this happen? Age. Old construction. Past plumbing codes allowed rooftop drainage to flow directly into the sewage system. The code changed. But many building owners and contractors still don’t know their systems are connected. They aren't breaking the law; they are just operating on outdated infrastructure.

Hamilton Tharp, the district’s collection system superintendent, notes that identifying these faults is critical. It stabilizes treatment levels. It prevents the system from being overwhelmed.

The district is tackling this in phases. The first segment tested lines in Aspen proper back in 2024. This phase targets the Aspen Airport Business Center, Cemetery Lane, Red Butte, and the Aspen Golf Club.

Once crews find a leak, they photograph it. They log it onto a GIS map. The data stays with the district. They will notify owners. They will patch the leaks.

This is a multi-year project. It is not a quick fix. But without it, the treatment plant keeps drowning in rainwater that never needed treatment in the first place.

The smoke is just the diagnostic tool. The bill for the repair is the real story. And it will be paid by the people who own those old, improperly plumbed buildings.