Tag Archives: cliffs

Straw matting below reinforced cliffs explained

The in basket: I was curious about the beige fabric that was laid at the base of the cliffs the state just reinforced on Highway 3 between Gorst and Bremerton, and in the nearby ditches. It didn’t look like the typical erosion ccntrol material I’ve seen elsewhere. So I asked about it.

The out basket: Project Engineer Jerry Moore says it’s called “straw mulch matting” and it is for erosion control.  lts purpose “is to temporarily

protect the soil from pounding rain that would disturb the soil surface and cause erosion,” he said. “The matting helps keep the water clean before it flows into the bay.

“The matting is a temporary measure that is placed until the grass starts to grow,” he said. “In time, the matting decomposes into mulch which will aid the

grass growth.”

What prompted Windy Point rock work?

The in basket: I got the impression somewhere that the rock work on Highway 3 at Windy Point between Bremerton and Gorst that may create long backups this year isn’t so much prompted by worsening of the conditions on the cliff as by the evolving state slope stabilization program and the Windy Point area gradually working its way to the top of the list of needed projects.

I asked the state if I was right.

The out basket: Lisa Copeland of the Olympic Region of state highways says there have been rock falls there. “(We receive) “regular reports from the maintenance team about rock falling in the area, most of it is contained to the ditch,” she said. “The most recent, significant event occurred in 2006, when 10-20 cubic yards of debris came down the cliffs. A similar event occurred during the Nisqually earthquake in 2001.

“This project falls under WSDOT’s Unstable Slope Management Program which prioritizes the need for statewide unstable slope improvements.”

“According to Gabriel Taylor, WSDOT engineering geologist, the scale is based on 11 factors, each one ranging from 3 to 81,” Lisa said. “They are all combined for the rating. As a result, the low end and high end are ridiculously unrealistic numbers and most slopes rate between 200 and 500. The slopes on this project rate 450.

“The slopes are rated not just on rock fall history,” she said, “but on risk to the traveling public, which is accounted for by (average daily traffic) as well as other factors.(It’s 71,000 (trips per day) in the Windy Point vicinity).”