Portions of sewer system overflow
Heavy rains too much for sites on Cardinal Drive
Crews working through the night New Year's Day were unable to contain the leaks from a beleaguered city sewer system as heavy rain ushered in 2009.
An estimated 60,000 gallons of untreated sewage overflowed from sewers onto Cardinal Drive and into Blue Heron Canal between 11 p.m. Jan. 1 and 7 a.m. Jan. 2. Much of the sewage ended up in Oswego Lake, either by passing through the canal or flowing to the lake via storm drains from Cardinal Drive.
Lake Oswego's sewers have overflowed in heavy rain since 1996. Rain in excess of more than two inches a day tends to infiltrate the system and causes its interceptor sewer - a pipeline running through Oswego Lake on pilings - to back-up.
The 20,000-foot line was built in 1963 and carries sewage from a series of smaller pipes, or trunk lines, to a wastewater treatment facility on the Willamette River.
The interceptor is now undersized for its service area, serving approximately 800 acres more than originally intended. Plans to replace it have been in the works since 1999 and construction is expected to begin in 2010.
The National Weather Service reported that 3.04 inches of rain and snow fell at the Portland International Airport in the 24-hour period between 4 a.m. Jan. 1 and 4 a.m. Jan. 2.
As it did, rainwater filled the Lake Oswego Interceptor Sewer to capacity and forced crews to fight sewage as it bubbled from manholes on Cardinal Drive and in the Blue Heron Canal for more than 24 hours.
'The rain has just been horrible,' reported Wayne Benson, utility superintendent in Lake Oswego's Maintenance Department.
'We did our very best not to get anything into the lake. That's the deal we made with the (Department of Environmental Quality) but unfortunately sometimes we just can't keep up with what's coming out,' he said.
DEQ has repeatedly fined Lake Oswego for sewage overflows because the release of untreated sewage into a water body violates the federal Clean Water Act.
The agency is unlikely to fine Lake Oswego for this latest violation because the city is on-track to replace the interceptor, according to Lyle Christensen, an environmental specialist with the department.
'As long as they are on schedule we probably are not going to take additional enforcement action and fine them additionally,' he said. 'The overflow is just another reason why they need to be moving forward.'
Benson said a warning system now alerts city crews as the sewers appear near overflowing. Crews received that warning by 2:50 p.m. on Jan. 1, he said, and quickly placed sandbags around a critical manhole on Cardinal Drive.
They worked through the night to vacuum sewage from a 1,000-gallon containment area into nearby trucks. The sewage was then driven across town to manholes on the other side of Oswego Lake less impacted by rainfall. The east side of the city's sewer system is unaffected by the undersized pipe in Oswego Lake and the back-up problems it causes.
Benson said as many as five trucks at a time shuttled sewage across the city throughout the day and night.
'But by about 11 p.m. it was coming out of the manhole so fast we couldn't contain it anymore,' he said.
Untreated sewage is a health hazard and carries pollutants and disease-causing organisms.
Benson said homeowners in the area have been alerted to the overflows through the city's emergency notification system. Five homeowners were unable to use their water because of the problems, he said.
He cautioned swimmers to stay out of Oswego Lake and Blue Heron Canal for a few days while higher levels of bacteria would be present in the water.
Repairs to the city's sewer system will begin this month in the canal area. Benson said those repairs would relieve some sewer overflow problems but that overflows would still be likely in wet weather before the interceptor sewer is replaced in 2010.
Unfortunately, as of press time Wednesday, the forecast for the metro area and Northern Willamette Valley was for periods of heavy rain through late Friday with a flood watch in effect during that period.
The sewage overflow is the first of its kind this winter. The city saw significant sewer overflows in wet weather 1996, 1998, 2001, 2006 and 2007.