Independent firm highlights land movement optionsA preliminary report by the Portland firm Landslide Technology suggests that to stop the current earth movement in the Uppertown area, the hill cut be filled back in.
Commissioned by the city of Astoria to figure out how to stop or slow the movement by the winter, Landslide Technology determined that the best way to do that would be to replace the base of a hill near Lief Erikson Drive and 31st Street that had been excavated for a commercial development.
"In our opinion, the most practical stabilization measure that can be undertaken before the commencement of the winter rains is to backfill the development excavation at the toe of the slope," said the report, written by engineers Michael R. Meyer and D Andrew Vessely, who is a vice president of Landslide Technology.
The firm predicted that if no change is made before the winter when heavy rains will saturate the ground, "rising groundwater levels will further destabilize the area and will likely increase the rate of movement."
Currently, the hill is held by a 15-foot-tall retaining wall. The report found that the wall is likely only supporting the slope of the hill formed after the excavation and that the hill cut had actually removed support for a "much larger and deeper, pre-existing landslide terrain."
At the start of the report, it notes Astoria is built upon a terrain with a history of "creeping ground" and slow earth movement.
While homeowners have blamed the hill cut for the movement - and one has produced two engineering reports commissioned by his insurance company backing those claims - this report is the first independent analysis that indirectly blames the excavation for the earth movement.
The excavation and retaining wall were done by Jim Wilkins Construction Co., on property owned by Skip Hauke. Neither Hauke nor Wilkins have publicly commented on the matter at the request of their insurance companies.
But Astoria City Manager Dan Bartlett said he hoped that they and other parties involved in the earth movement would have some response to the findings of the report at the city council meeting tonight.
He said Hauke and others received the report Friday.
"The ball is in their court and we're hoping someone is going to pick it up and run with it," Bartlett said.
Already six homeowners have left their houses because of the movement. The report said that it appeared the earth had moved about six inches during the summer.
The firm was able to make its conclusions and recommendations based on data gathered from inclinometers and other devices placed in borings at the scene.
Essentially the engineers are recommending that sand dredge be used to fill in the excavation to "pre-development topography" at the base of the hill.
The report also said that some movement would continue after the hill had been filled in because the ground had been stretched to some degree.