Soil erosion caused damaged sewer pipe, 10 ft. sinkhole on Broadway Avenue

A broken City of Portland sewer pipe that left Smith Memorial Student Union temporarily closed Wednesday was initiated by soil erosion, which caused a concrete stormline pipe to fall on the sewer pipe earlier this week.

The soil erosion underneath the street on Southwest Broadway near SMSU occurred after an influx of water washed away the soil, causing a stormline pipe to fall on and break the city sewer line on Monday, said Cheryl Kuck of the Portland Department of Transportation.

The soil, a sandy loam, caused a 10-foot sinkhole underneath the street, Kuck said.

“The water eroded an area that created a cavity underneath the street,” Kuck said. “So it’s not a fault with the stormline, or with the sewer pipe, as it was with this hole.”

PSU Facilities employee Richard Koontz was one of the first on campus made aware of the situation, after receiving several reports of toilets not functioning in SMSU.

“I called the City of Portland around 11 a.m. on Monday to report the problem,” Koontz said. “They came [Wednesday] to dig up Broadway to get to the pipe.”

The sewer pipe, which ran under Southwest Broadway and connected many PSU buildings to Portland’s sewer system, was built in 1882, Kuck said.

“We have a lot of over 100-year-old pipes in the sewer system,” she said.

While SMSU reopened yesterday after the building’s water services were shut off and the ground and basement floors were closed all day Wednesday, Broadway will remain partially closed until Wednesday, Kuck said.

City workers still have to replace the broken sewer pipe, fill the cavity and stabilize the manhole and street before the job is completed, she said.

“This isn’t finished yet,” she said. “We’ll be out of there sometime Wednesday, probably.”

Kuck also said that the City of Portland is going to further investigate the source of the water that washed away the soil, which is still unknown.

The sinkhole will be filled with the materials that will keep another incidents such as this one from happening-a mixture of soil, gravel and a kind of diggable concrete, Kuck said.

SEWER PIPE TIMELINE

MONDAY, OCT. 20PSU facilities employee notices a problem with the sewer system in Smith Memorial Student Union after receiving several complaints about non-functioning toilets- Sewage begins to backup in the basement of SMSU, causing damage to the carpets in the IT hallway.- Problem reported to the City of Portland in the late morning.- Water shut off in SMSU.- Outside company Dow Columbia called in for basement cleanup in SMSU.

WEDNESDAY, OCT. 22– Construction crews from City of Portland start digging up Southwest Broadway, find broken sewer pipe at the bottom of 10-foot sinkhole–construction causes lane closures on street.- SMSU closes first floor, basement, bathrooms and food services, and shuts off water service.- Dow Columbia again called for basement cleanup of SMSU.- Workers continue pumping water and sewage from adjacent manholes, dumping them in other manholes away from the sinkhole.

THURSDAY, OCT. 23– Initial investigation of sinkhole by the City of Portland find the sinkhole was caused by soil erosion underneath Broadway due to an influx of water from an unknown source; washed-away soil caused concrete storm pipe to fall on older sewer pipe, breaking it and causing sinkhole.

The City of Portland is expected to continue their work until next Wednesday, replacing the broken pipe, filling in the sinkhole and securing the manhole and street.