Advisory: Heavy rains last night lead to a stormwater and sewage overflow in NW Portland
Sanitary Sewage Release Advisory
(this is not a combined sewer overflow [CSO] advisory)
(September 18, 2019) - Heavy rains last night overwhelmed a portion of the City’s sewer system at the 2700 block of NW Westover Road, leading to a mix of stormwater and sewage overflowing to the street from at least two manholes. In addition, the heavy rains led to a number of basement backups in nearby homes.
The mix is estimated to be about 90 percent stormwater and 10 percent sewage. Crews responded around 9:30 p.m. and cleaned out the main sewer line as a precautionary measure in case of blockage but did not find any. The overflow stopped around 10:15 p.m.
The overflow to the street mixed with additional rain that fell overnight, further diluting and dispersing it. Warning signs were posted on the 2700 block of Westover only. Environmental Services does not advise any additional precautions.
The City of Portland Bureau of Environmental Services treats an average of 70 million gallons of wastewater each day and manages a system of 2,500 miles of pipes, 2,000 green street planters and additional grey and green infrastructure. While not common, exceptionally heavy rains can exceed the capacity of combined stormwater and sewer pipes, leading to discharges. Sewer overflows are usually preventable and are caused most often when pipes become blocked with grease, tree roots and debris.
The Bureau of Environmental Services provides city residents with programs to protect water quality and public health, including wastewater collection and treatment, sewer construction and maintenance, stormwater management, and stream and watershed restoration.