Department of Transportation reports show that the bluff east of Aberdeen has seen eight slides since 1994 with the latest one in January, and a department official said it gets monitored every day.
The bluff, which has been historically unstable, has led some locals to grow wary of its stability, with westbound communters of Highway 12 paying careful attention as they drive by.
The most recent slide, which came on the heels of heavy rainfall on Jan. 5, closed all four lanes of the highway until crews cleared the debris later that evening. After clearing the highway, the DOT left the remaining clean-up to the city, which presides over that area.
Aberdeen Public Works Director Malcolm Bowie said no additional work was planned to address the area.
The bluff saw its worst slide in December 1996, nearly 1,600 feet west of the welcome sign, and resulted in the closure of all four lanes for several days.
Mitigation following the 1996 slide, according to Marc Fish, the department’s assistant chief engineering geologist, included the Jersey barrier that now sits along that stretch of highway, widening the ditch beneath the slope and applying Shotcrete, a cement sprayed on the side of the slope. Geologists also installed the horizontal drains that can still be seen jutting out from the face of the bluff to address the water pressure that helped cause the slide in 1996.
“We’ve not had a failure of any significance or a rock issue of any significance since that time,” Fish said. “Some rocks have come down off the slope, but we have a very large and deep ditch at the base of the slope – a catchment area – that is to catch those types of rocks.”
Other recent slides happened in March 2014 and January 2010. Two slides happened in 1994, one in April and again in December. Though the bluff has seen slides of various significance through the past two decades and has resulted in temporary highway closures, DOT and city officials said it remains a priority.
The department’s Unstable Slopes Management Program keeps a database of more than 3,300 unstable slopes throughout the state and ranks them based on their level of risk. Two of the bluff’s slopes are included in the database.
Monitoring slopes throughout the state is done via maintenance offices in each region. Randy Moody, the department’s maintenance superintendent for Grays Harbor County, said slopes are informally checked by crews during their drives to and from work sites.
“We know where our problems exist, we’ve been dealing with these areas for many years,” Moody said, adding that the bluff near Highway 12 is on a route often frequented by maintenance personnel. “It gets checked, I can say, every day of the week. It basically has not moved on us in many, many years.”
Despite its history of slides, the bluff should not be an area of concern for drivers along the stretch of highway, officials said.
“Our maintenance crews that work out of the Aberdeen area are very familiar with this stretch of highway and they’re very familiar with this bluff area,” said Claudia Bingham Baker, a DOT spokeswoman. “So what we can do to assure the public that it is safe for them is to assure them that we watch this area on a regular basis.”
Kyle Mittan, 360-537-3932, kmittan@thedailyworld.com. Twitter: @KyleMittan
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