20100310131248096.pdf�_'___Krazari& ASSOC I ATE S, INC.
GEOTECHNICAL ENGINEERING e ENVIRONMENTAL ENGINEERING
CONSTRUCTION TESTING & INSPECTION
July 26, 2006 KA Project No. 092-06128
Mr. Dwight Steele
Steele Home Service
2342488 1h Ave W
Edmonds, Washington 98026
RE: Limited Slope Evaluation
Proposed Addition
Drake Residences �._... ,
E 6Fe 9 t� Place West
' � 6 4 9 i a G k�"� 4; R /,,I H R' i r"
6"13 95'�Ias�hmgtrlrl qq p+„� I F
�de li Y OM�';;;
Dear Mr. Nelson:
In accordance with your request and authorization, a geologist from our firm conducted a limited slope
assessment for the referenced site on July 12, 2006. We have prepared this letter, to address the
applicable elements of the Edmonds Municipal Code — Natural Resources — Chapter 23.80 — Geologically
Hazardous Areas.
The property is currently pending an application for a small addition of approximately 140 square feet,
and a newly designed roof. The property is located at 22613 95`h Place West in Edmonds, Washington.
The site is currently developed and the property is well vegetated with a typical suburban lawn and
landscaping. The majority of the proposed site is level. A slope break, which we understand is near the
southern lot line, breaks sharply to a slope of approximately 40 to 50 percent in magnitude which
terminates in a level area approximately 30 feet below. The slope is well vegetated with salal,
rhododendrons and large conifers. There is an abundance of forest duff on the ground.
Based on a review of the Geologic Map of the Edmonds East and part of the Edmonds West Quadrangles,
Washington (Geologic Map), it appears that the property is located in an area that is on a broad expanse
of Vashon Drift Glacial Till. This unit is a non -sorted mixture of gravels, sand and silt, which has been
over consolidated by sub glacial pressures.
The Natural Resources Conservation Service lists the soils in this area as Alderwood-Urban land complex
which is a soil developed on glacial tills, and has been altered by urban development. The soil has an
extreme erosion potential, due to the quantity of silt and fine sand that can be found in it.
During our reconnaissance of the site, we investigated the shallow slope soils by excavating shallow hand
auger borings in the adjacent lawn, and on the slope near the mid point in two locations. A hand auger
was used at locations near the top of slope, as well, to identify the soils. The conditions encountered in
the shallow hand auger borings corresponded well to the mapped glacial till: a medium dense to dense
silty sand with gravel, light grayish brown. The slope has a limited quantity of fill around the top.
Offices Serving The Western United States
19501 — 144"' Avenue NE # F-300 9 Woodinville, Washington 98072 e (425) 485-5519 9 Fax (425) 485-6837
KA Project No. 092-06128
July 26, 2006
Page No. 2 of 3
No tension cracks, active sloughs or water seepage that could be attributed to slope instability was seen.
All the conifers on the site are standing straight and tall indicating that this site has not significantly
moved in recent history.
We found no evidence of a landslide hazard, and recognize that the soils present a limited erosion hazard.
It is our opinion, based on our site observations and knowledge of the proposed construction, that
subsurface exploration and detailed slope stability analyses are not required. It is also our opinion that
detailed survey work and geotechnical analyses for the site slope conditions are not warranted.
It is our opinion that the addition may be located as proposed, provided adequate measures are taken to
minimize erosion during construction, and in terms of the maintenance of the steep slope after
construction. A list of Best Management Plans for erosion control are listed below:
• Phase the soil, foundation, utility, and other work, requiring excavation or the disturbance of the site
soils, to take place during the dry season (generally May through September). Grading activities can
be undertaken during the wet season (generally October through April), but it should also be known
that this may increase the overall cost of the project.
• All site work should be completed and stabilized as quickly as possible. Temporary stabilization can
include plastic, mulch, or an acrylic such as Envirotac. Permanent stabilization can include building
construction, paving, sodding, or hydroseed, provided the area is maintained so the grass can grow.
• Additional perimeter erosion and sediment control features may be required to reduce the possibility
of sediment entering the surface water. This may include additional silt fences, construction of a
perimeter berm, ditches with check dams, or ponds to allow the debris to settle out.
• Any runoff generated by the project should be directed to a stabilized area away from the slope.
Concentrated flows of water should not be directed onto the slope for any reason.
Y All roof and footing drains should be tightlined to the storm drain system.
To prevent erosion after the project, the homeowner should limit the removal of native vegetation in the
area on and adjacent to the slope, although we understand that the slope is part of the adjacent property.
Vegetation should not be removed from slope areas without protection of exposed soils, and immediately
re-establishing permanent erosion control on the site. Water flow on the slope should be limited, no roof,
footing, or yard drains should be directed toward or onto the slope.
Based on our limited soil study, an allowable soil bearing pressure of 2,500 pounds per square foot (psf)
can be used when placing footings on undisturbed native soils at a depth of 18 inches or greater.
The geotechnical information presented herein is based upon professional interpretation utilizing standard
engineering practices and a degree of conservatism deemed proper for this project. It is not warranted
that such information and interpretation cannot be superseded by future geotechnical developments. We
emphasize that this report is valid for this project as outlined above, and should not be used for any other
site. Our report is prepared for the exclusive use of our client. No other party may rely on the product of
our services unless we agree in advance to such reliance in writing.
Krazan & Associates, Inc.
Office. -Serving, The, We -fern United ShfP.0
KA Project No. 092-06128
July 26, 2006
Page No. 3 of 3
We hope that this letter provides the information required at this time. If you have any questions, or if we
may be of further assistance, please do not hesitate to contact our office at (425) 485-5519.
Respectfully submitted,
KRAZAN & ASSOCIATES, IN r.
obert A. Blomquist, LG
Project Geologist
i'e Caraway, P.E.
Geotechnical Division Manager
Krazan & Associates, Inc.
Offices Serving The Western United States