First written contact with City of Shoreline, Uki Dele, Surface Water Utility & Environmental Services Manager 7/16/16
Hello Uki Dele,
I live on 1320 NW 175th Street, Shoreline. I left a couple of messages yesterday about a storm water culvert that I fear is destabilizing a steep grade on my property and setting the stage for a potential slide or catastrophic event.
My husband and I have lived at this property in Innis Arden since 2002. The north side of the property is a Coyote Reserve, a green space that has a greater than 30% grade. I have a copy of a report, “Slope Stability and Water Problems Associated with Soil and Vegetation of Innis Arden” (prepared by Adams and Harrison of the UW School of Forestry Soilslab) where they identify the storm water culvert on my property and recommend that the water be diverted to avoid a sink hole or a slide.
I’ve had this soils report since 2003 or so. I asked to see it years ago because I was concerned that the neighborhood would recommend lowering the canopy on this green space, and I assumed that degrading the vegetation could compromise the soil. Thankfully they have not made any moves to trim trees.
However over the last few years, I should have been more aware of the gully created by drainage in the culvert. The gully has widened significantly. It has been mountain beaver eating our raspberry plants that led to the discovery of the immensity of the culvert running under our property.
Here’s a little history. A few years back I noticed that the storm water drainage (we’re at the bottom of 175th on the north side) ran across my neighbor’s driveway and into my yard depositing mud in my yard and degrading my landscaping and the soil around our fence. The city came out and created a berm that moved the water into street drain that sits at the SE side of my property. After I remember looking at the storm water rushing into the reserve at the mouth of the culvert during a heavy rain and noted that it was just flowing into the dirt. I did not understand at the time the problems that would develop with that amount of water draining onto the slope. Since then I lost control of the vegetation and did not have a visual of the degradation of the slope that has taken place. But in the last few days I have removed vegetation (ivy, blackberries) and exposed the culvert. It appears that much soil has washed away, exposing tree roots and a deeper cavern than I remember.
I am very concerned that if this water is not diverted to the city storm water system, we are going to lose our hillside and our home could be threatened. The NE corner of our house is only 30′ away from the gully!
In the Adams and Harrison Slope Stability report, they identify this culvert.
…Storm culvert (CY_O-2) delivers large amounts of water into Coyote during rain storms… A gully is growing between the culvert and the bottom of the reserve as water is dumped into the reserve. This situation should be corrected. Otherwise an even larger gully will form and the large volume of water passing through the sand may create a hydrostatic head lower down causing a blow out and the subsequent transport of sand from the reserve to lower cliff (sink hole formation).” They mention that a blow out would be unlikely if the culvert is diverted and the canopy maintained.
My husband and I have been in communication of King County Wildlife Control and are working on trying to encourage the mountain beaver to move elsewhere. In the meantime, I would really appreciate meeting you and having you or someone else come out to see the culvert as soon as possible. I hope that the culvert can be diverted before the fall rains begin, and I can work to re-vegetate the area and re-stabilize what remains of the slope.
I’d be happy to get you a copy of the Slope Stability report.
Thank you for your time. I look forward to talking with you soon.
Teresa (and Julian) Catford
1320 NW 175th Street