Sunday, April 20, 2014
PORTLAND - Water district officials say that a "considerable amount" of its water mains are beyond their useful life, meaning leaks and breaks like the one on Dec. 19 that spewed thousands of gallons of water onto Bayside streets could happen again.
This section of 100-year-old water main ruptured Dec. 19 on Somerset Street.
Courtesy of Portland Water District
Crews work to repair a water main break on Dartmouth Street in Portland on Dec. 20.
Staff File Photo/Gabe Souza
Officials say they don't expect to see more catastrophic breaks like that one, which spilled 20,000 gallons of water per minute for 45 minutes near Somerset and York streets. That water main break caused significant flooding, damaged private and public property, and triggered a 24-hour boil-water order for the entire peninsula.
"The biggest event that could have happened, I think, happened," said Christopher Crovo, executive director of asset management and planning for the Portland Water District. "It was a very unusual break."
The Somerset Street break, however, highlighted the state's aging water delivery systems and the lack of funding to keep that system in good repair.
The Portland Water District provides water from Sebago Lake to about 190,000 people in 11 communities, from Raymond to Cape Elizabeth, including Portland and South Portland, through a 975-mile network of pipes, ranging in age from 1870 to 2012.
Two transmission lines -- dating from 1912 and 1939 -- supply water to the district's 11 communities. The redundant capacity would allow the district to maintain water service if one of the pipes fails, Crovo said.
About 10 percent -- or nearly 100 miles -- of the district's water mains are more than 100 years old, which is considered beyond the pipes' useful life. But it's not the oldest pipes that are breaking at the highest rate.
Crovo said pipes from the late 1800s are made of thick cast iron that could probably last 200 years. But pipes laid between the 1920s and the 1930s are seeing the most failures. Crovo said the scarcity of metal during the two world wars and lower levels of craftsmanship are largely to blame.
About 87 miles of pipe was laid during that period, according to district records.
While breaks could become more common as the system continues to age, Crovo says they won't be as severe as the one on Somerset Street, given the size of the pipes involved and their locations. He noted Somerset Street's low-lying location.
Only 100 miles of the pipe system owned by the Portland Water District are 20 inches wide or larger. Those pipes typically run along major roadways in Gorham, Westbrook, Portland, South Portland and Falmouth.
The rest are smaller mains with fewer connections to businesses and residences. They do not cause as much damage when they fail and take less time and money to fix.
The 20-inch Somerset Street main, which dates back to 1912, was large because it used to carry water from a 2-million gallon reservoir on Munjoy Hill. That reservoir was taken out of service in 2003.
A portion of the Somerset Street main -- from Franklin Street to Elm Street -- was replaced with 16-inch pipe in 2003.
Crovo said the district had been planning to replace the rest of the 20-inch main next year, when a major development project is expected to move forward in Bayside.
Meanwhile, district officials say that factors besides age play a major role in causing water main breaks, such as road construction and weather.
If there is a stretch of cold weather, but not a lot of snow to insulate the ground, frost can cause pipes to break even though they lie 51/2 feet below the ground, Crovo said.
Annually, the district replaces about 3.5 miles of pipe that's 75 years or older, at a cost of $3 million. That's short of Maine Public Drinking Water's annual target rate that recommends replacing at least 1 percent of a system's water mains.
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