The chiller system that cools Metro's busy Farragut North and Dupont Circle stations is in shambles, and fixing it will require digging up more than the length of a football field of Connecticut Avenue.

The problem lies beneath bustling Connecticut Avenue, right around the intersection with K Street in Northwest. Large pipes that carry water to cool the Metro stations are rotted out and leaking in multiple locations. The pipes are approximately 6-to-8 feet below the surface. Like the road above them, the pipes have dealt with a lot of wear and tear.

"We've experienced catastrophic failures of the supply lines to the cooling tower underneath Connecticut Avenue," said Paul Kram, acting head of Plant Maintenance for Metro.

The leaks were so bad the cooling system has been turned off.

"These are big lines," Kram said. "They are 16 inches, they are 40 years old and they run for about 400 feet in each direction under Connecticut Avenue."

The fix will not be easy. At some point before spring, 400 feet of Connecticut Avenue will have to be dug up to get to the pipes. The pipes will then be replaced. The hope is that the system can be fixed by the start of next year's "hot" season.

For riders, no chiller system means they have to sweat it out on hot days. In the summer, the transit agency tries to keep temperatures about 6 or 8 degrees cooler inside stations than the outside temperature.

Inside the Farragut North station Wednesday, a digital thermometer put out a reading of 90.3 degrees. Inside Dupont Circle, it was 89.1 degrees.

"I mean it's hot, I'm sweating right now," said rider Malik Moore.

"It's not only that it's 90 degrees in here and humid, but it's also that I have been waiting more than 10 minutes for a train on the Red Line," said Eric Hershberg, his suit jacket draped across his knee. "If I were infirm or elderly, this would not only be uncomfortable but hazardous. It's not acceptable."

Others say the heat is nothing like some other transit systems such as New York's subway system.

"It just makes you tougher," said rider Emma Smith with a smile, in town from New York.

Kram makes the point that in Boston, subway stations are never cooled and regularly top 100 degrees during a heatwave.

"But that is a northeastern city," Kram concedes.

Metro said it is putting together a detailed plan to fix the chiller system now. It will require coordination from a number of city agencies. No timetable or price has been set for the repair.