Sean C. Morgan
An extraordinarily large rainstorm caused a series of landslides along Highway 20 east of Cascadia and overloaded the city’s wastewater treatment plant over the weekend.
Some parts of Oregon received more than 6 inches of rain, including 8 inches recorded at Mapleton. At Foster Dam, the U.S. Army Corps of Engineers recorded 2.72 inches Saturday and Sunday.
On Sunday, a landslide closed Highway 20 at milepost 44, just east of Cascadia, about 17 miles east of Sweet Home.
The slide deposited 150 cubic yards of mud, rock and debris on the highway as well as 12 to 14 large trees, said Rick Little, Oregon Department of Transportation spokesman. The slide resulted in the extended closure of the highway, with detours to Highway 22 and highway 126 to access Santiam Pass and Central Oregon.
ODOT crews worked overnight to maintain one lane of travel for emergency vehicles only, and they cleared the roadway Monday afternoon.
“Yesterday morning, we got the call on the bigger slide,” said Kendal Weeks, ODOT transportation maintenance manager. “We punched a hole through it, and we found a lot more.”
Workers found about a dozen smaller slides, he said. Several culverts were clogged, forcing water carrying 4- to 6-inch rocks across the highway.
The main slide was about 15 feet deep, he said. A slide about five miles east, near milepost 49, was about 4 feet deep. That slide was mostly mud, about the consistency of cement.
“I’ve lived up here going on four years, and Sweet Home my whole life,” said Joe Mott, who lived east of the main slide. “This is like my playground from when I was a kid.”
He said the water in the river almost reached the road, and it did reach a cabin on the shore across the street from his house.
He saw water running across the highway at the culverts, and the rainfall collapsed the cistern at his house.
Errol and Bobbie Shervey, who also live east of the slide, said the water drained across the highway and their front yard, washing out their drainage system.
They had 6 inches of water coursing over their front yard, and they could see the water nearly reach Gordon Road across the river from their house.
“It was really frightening,” said Bobbie Shervey. “Usually you can see every pebble in the water, every fish.”
By Monday around noon, the water was subsiding although it was still brown and opaque.
The couple began building their home there in 2006 after visiting the area for 20 years. During the February 1996 flood, Char LaFollette, who owned and operated the Mountain House with her husband, took pictures of the river where Highway 20 cross the South Santiam.
The photo showed the water nearly reaching the bottom of the bridge, Bobbie Shervey said. Even then it didn’t flood their property, and they felt relatively safe.
The Sherveys were surprised to see the runoff across their front yard.
“It carved a nice-sized channel where it wanted to go,” Bobbie Shervey said.
Errol Shervey left for town Sunday to get a Sunday paper but wasn’t able to make it when he found the main slide, he said.
They watched tremendous amounts of debris float down the river, they said.
That debris was visible in a muddy Foster Reservoir Monday.
“The most traumatic thing: We watched a mamma mink jump in the water dragging something,” Bobbie Shervey said. Although she doubts it had baby mink, she thinks it may have had its nest below the waterline.
In Sweet Home, the Wastewater Treatment Plant began overflowing at approximately 11:45 a.m., according to the Oregon Department of Environmental Quality. The plant is located just east of the Pleasant Valley Bridge along the South Santiam River.
The overflow was the result of heavy rains and high groundwater entering the sewer collection system, according to the DEQ. It stopped overflowing at about 9:45 p.m.
Downstream users were notified, and warning signs were placed as required.
Anyone with questions may contact the Sweet Home Public Works Director at 367-6243 or the plant at 367-4846.
Previously, the last time that the plant bypassed untreated wastewater was in March.
The city is in the process of repairing and replacing deteriorated sewer pipes throughout the city to reduce the amount of storm water and groundwater that enters the sewer system.
The storm was the result of a strong jet stream over the Pacific Northwest bringing in a couple of disturbances packed with moisture-laden, sub-tropical air producing heavy rainfall, according to the National Weather Service.
The heavy rainfall combined with snow melt runoff to flood several rivers and streams in Northwest Oregon and Southwest Washington and cause several landslides and debris flows.
Corvallis recorded 1.54 inches of rain over the weekend. Salem and Eugene had 1.34 and 1.1 inches respectively.
The Weather Service is predicting partly sunny and partly cloudy weather until this weekend when there will be a chance of rain. Highs will be in the high 40s and lows in the high 30s.