A 20-inch city sewer line near the Mount Roberts tramway on South Franklin Street broke late Tuesday morning, and traffic on the street was reduced to one lane until repairs were completed Tuesday night.
A wastewater utility crew worked until 10:30 p.m. to replace a section of steel pipe with an 8-foot length of PVC piping.
Saltwater intrusion and electrolysis caused by nearby power lines brought about the corrosion that led to the pipe's failure, according to wastewater utility senior operator Tony Stoinich.
This is the second such break in the line in two-and-a-half years, said wastewater utility manager Andrew Bronson.
The other break occurred last year in front of city hall.
``The problem is that much of downtown is fill made up of crushed rock from mining,'' Bronson said. ``And so, seawater easily flows back into the area.''
Damaged pipe sections are replaced with rustproof PVC, he said, but replacing the entire steel main -- which runs about 2.5 miles from Centennial Hall to the Juneau-Douglas treatment plant -- would be a very expensive proposition.
``Another way is to reline the entire existing pipe with PVC, but that would also be very expensive,'' Bronson said.
Bronson estimated the pipe to be 20 to 25 years old.
``Construction standards then were different from today's,'' he said. ``We would not use steel pipe today.''
There were no reports of damage to local businesses or residences.