A section of eroding bluff along NE Front Street in Coupeville that is threatening a sidewalk is believed to be stable for now but the situation will continue to be monitored closely, town officials say.
Bruce Blyton, a geotechnical engineer with Kirkland-based Associated Earth Sciences, Inc., examined the site last week and was able to make several determinations, according to Mayor Nancy Conard.
First, the bluff is unlikely to erode much further in the immediate future. That means both the sidewalk and the road are probably safe for the time being, though that part of the gravel path remains closed for public use.
“What you see right now is what you can expect for the next couple of weeks,” Conard said.
Also, the problem is likely tied to man-made fill that was used to address a long ago erosion problem, possibly in the early 1960s. Chunks of concrete and asphalt were mixed with light sandy soils and the combination has proven particularly vulnerable to scouring from tidal action.
“He said it’s really the fill that’s the underlying problem,” Conard said.
The fill is believed to have been used on up to 400 feet of waterfront though the area that’s visibly affected, both from the view on the street and the beach, is only about 60 feet across.
That part of the bank, located between NE Kinney and NE Gould streets, began sloughing off onto the beach earlier this month and the sidewalk in the area began to sag toward the beach. The process sped up rapidly last week, however.
“It went down even further with the heavy rain last night,” said Mary Young this past Tuesday, a Front Street resident of 14 years.
So much of the bank had fallen onto the beach that the section of gravel sidewalk is now noticeably lower than the surrounding area and large and deep cracks are visible along the path.
Town officials had been aware of the situation for more than a week. Cones and a barricade were erected but additional steps were taken Tuesday to combat the developing situation.
Road crews placed sandbags along the outside edge of the path in an attempt to limit further saturation from stormwater off the road. The geotechnical engineering firm was also hired.
There was some concern initially that a lane of traffic or the entire street would have to be closed to through traffic, but those fears were at least temporarily settled by the engineer’s findings.
According to Coupeville resident Ron Van Dyk, who has lived across the street in the historic Captain Joseph Clapp House since the early 1960s, erosion is nothing new on NE Front Street.
Shortly after he moved in, a large fir tree on the water side of the road toppled onto the beach after a “big blow.” When it fell, the tree’s root system took nearly two feet of roadway with it, he recalled.
“When I came out in the morning, I thought, ‘Something looks different,’” he said.
Also, NE Front Street used to run in front of the nearby Captain Thomas Coupe House — the oldest house in town — but was rerouted around the building because of erosion problems.
The house itself has had to be moved back twice over its long history for the same problem, according to Ebey’s Landing National Historical Reserve records.
Island County officials are reporting that they have cleared at least a dozen small landslides on Whidbey and Camano Island roads in recent weeks, and one larger slide south of Clinton at Possession Point destroyed one home and damaged another this past Wednesday.
“This whole county is slowly but surely washing away,” Van Dyk said.
The town’s hired geotechnical engineer is expected to conduct further tests, such as soil testing and physical survey of the property to determine the limit of the right-of-away. A report will be given to the Town Council at its next meeting, Feb. 12, but a long-term solution may not yet have been identified.
Conard said the cost for the engineer and later stabilization work remains unknown.