Heavy rainfall, combined with saturated ground conditions, resulted in the City of Sweet Home overflowing diluted raw sewage into Ames Creek, the city reported Wednesday, Dec. 10.
The creek flows into the South Santiam River just east of Pleasant Valley Road.
When the ground becomes saturated, groundwater enters the sanitary sewer system through
cracks and holes in the pipes, in addition to footing drains, and other sources of extraneous water from private property. When this occurs, the ability of the sewer system to transport sewage to the wastewater treatment plant is exceeded and the system becomes surcharged, the city said in a statement.
When these conditions become severe enough, the level within the WWTP’s influent pump station surcharges, then overflows to Ames Creek.
The influent pump station structure overflowed plant capacity at approximately 2:50 p.m. on Dec. 9, and concluded at 10:40 p.m. that evening, the city reported.
Signs were posted warning people to avoid contact with the water in Ames Creek and South
Santiam River due to potentially higher levels of bacteria. The city said signs would be removed
when the overflow concludes and bacteria levels are determined to be normal.