FEBRUARY 3, 2015
PORTLAND, OREGON
The Portland Water District had 21 ruptures last month,
twice the norm, while also accelerating replacement of its aging lines.
February’s historic cold drove frost deep into the soil
where the Portland Water District’s water mains are buried, wreaking havoc on
the utility’s aging infrastructure.
“The frost went down into the ground almost 4½ feet,” said
Chris Crovo, director of asset management and planning for the water district.
Most of the district’s water mains are 5 to 5½ feet deep, though sometimes
shallower because of ledge, Crovo said.
“That frost moves the pipe and some of that pipe is old,
cast iron and brittle. It doesn’t hold up very well, and it cracks and leaks,”
he said.
In the latest break, district crews replaced a section of
cast iron pipe after a main ruptured Monday on Stroudwater Street in Westbrook.
The district had 21 water main breaks in February, twice the
normal number for a winter month and the most in any February since 2004, said
district spokeswoman Michelle Clements. January had a more typical eight to 10
breaks, she said.
The water mains haven’t been the only casualties of the
frigid weather. The deep snow and heavy ice also have taken a toll on natural
gas and propane equipment.
Last week, the Portland Fire Department responded to a
business on Marginal Way after its natural gas line was ruptured by a snow
plow. The Portland Museum of Art and the Children’s Museum & Theatre of
Maine had to be evacuated after a falling icicle punctured a gas line.
In Cape Elizabeth on Monday, a propane line at 146 Scott
Dyer Road was severed by a buildup of ice and snow, sending the gas into the
home and resulting in an explosion and fire, the State Fire Marshal’s Office
said. Also Monday, a business at 470 Riverside Street in Portland filled with
gas after a service line broke under a deep pile of snow.
Since Jan. 1, the Portland Fire Department has responded to
21 gas leaks, two more than in the same period last year, said spokesman Tim
Nangle.
CERTAIN PIPES MORE VULNERABLE
The water distribution system has had a more difficult time
with the weather.
That’s because about 460 miles of the district’s 1,000 miles
of pipe are cast iron and range from 100 to 140 years old, with some dating to
1870, Crovo said.
The cast iron is being replaced with newer, ductile iron
pipe, which flexes and doesn’t crack as easily.
The water mains are vulnerable because they are buried
beneath the street, where plow crews have scraped away any insulating snow.
The service lines running to customers’ homes are less prone
to breaking because the thick snow cover serves as insulation. Some service
lines have frozen, but that has typically been because the pipe is closer to
the surface or is near a stormwater collection system pipe that allows cold air
close to the service pipe.
The sewer system is not susceptible because those pipes are
warmer and the system is more modern.
The water line problems are not unique to Portland. Lewiston
Public Works Director David Jones told WCSH6-TV that his city is seeing more
water main breaks, and cold weather is to blame.
A water line break in Lewiston closed part of Ferry Road for
several hours Monday.
MANY STEPS IN REPAIRING PIPES
Water leaks can be difficult to find because the water
doesn’t always bubble to the surface above where the leak is located. The frost
can form a barrier and force the leaking water to migrate to another spot
before it works its way to the surface. Sometimes the district has to drill
test holes to locate a leak. That leaves the water running, which causes icing
on the roads.
Once a leak is located, each water line repair requires
extensive excavation, often disrupting traffic as roads are closed or narrowed.
Workers use a jackhammer tip mounted on an excavator to break through the frost
layer, Crovo said.
“It’s like going through ledge,” he said.
Once the pipe is excavated, the broken section is examined.
If it has a radial crack, it is patched with a “Band-Aid.” If it has a lateral
crack, a section of old pipe must be cut away and replaced with a new one. That
was the case Monday in Westbrook, where 3 to 4 feet of cast iron pipe had to be
cut away and replaced.
When the repair is finished, the hole is filled with gravel,
and even that is complicated by the weather. The gravel needs to be dry and not
frozen into large chunks. Crews then place an asphalt patch over the gravel,
waiting till the warmer months to repave it properly.
MORE SPENDING, SPRING BREAKS NEXT
Portland’s water district is gradually replacing its oldest
pipes.
The district spent $6 million on replacing pipes last year,
budgeted $6.5 million for this year and is asking for a 3.8 percent revenue
increase so it can increase the replacement fund to $7 million annually, said
Clements, the water district spokeswoman. In 2011, the district was spending
just $2.5 million annually on pipe replacement.
The district tries to anticipate problem areas and make them
a priority, Crovo said.
“If we get multiple leaks on a road, it tells us that pipe
has met its useful life,” he said.
Crovo said that although it seems like Greater Portland has
had more than its share of water main breaks this winter, the American
Waterworks Association’s benchmark is 25 to 30 breaks a year for every 100
miles of pipe. The water district averages about 10 per year for each hundred
miles of pipe, Crovo said.
February’s deep freeze also could create problems this
spring, he said.
“Frost receding is also not good for water pipes,” Crovo
said. “Probably the last two weeks of March we’ll see another rash of breaks.”
However, the infrastructure that most people will be paying
attention to at that point will be the roads.
“They’re going to have a banner year for potholes,” he said.