CRA-2010-0019 erosion-landslide.pdfCITY OF •
CRITICAL AREAS RECONNAISSANCE REPORT
Site Location: 23005 107th
Place W Tax Acct. Number: 00476000001800
Determination: Study Required Determination #: CRA -2010-0019
Applicant: Scott Curtis Owner: Sheila Ringdahl
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During review and inspection of the subject site, it was found that the site contains and/or is
adjacent to critical areas, including Geologically Hazardous Areas, pursuant to Chapters 23.40 and
23.80 of the Edmonds Community Development Code (ECDC).
The western half of the subject parcel is fairly level. The eastern half slopes gradually downward
to the east until the slope reaches a short steeper section. According to the City's LIDAR data, the
grades in the eastern section of the parcel range from 15% to greater than 45% near the eastern
parcel boundary. The portions of the site with slopes less than 40% are considered erosion
hazards and that portion of slope near the eastern property boundary which is in excess of 40% is
considered to be a landslide hazard.
This report applies to the entire subject parcel. Depending on the location and type of project
proposed relative to the identified critical areas, additional studies may be required.
Certain activities are allowed in or near critical area buffers as specified in ECDC 23.40.220.
Similarly, certain development proposals may be exempt from Critical Areas Requirements (ECDC
23.40.230). If you have any questions about whether your proposed development qualifies as an
allowed or exempt activity, please contact a Planner for more information.
GENERAL CRITICAL AREA STUDY REQUIREMENTS
Critical Areas Reports identify, classify, and delineate any areas on or adjacent to the subject
property that may qualify as critical areas. They also assess these areas and identify any potential
impacts resulting from your specific development proposal. If a specific development proposal
results in an alteration to a critical area, the critical areas report will also contain a mitigation plan.
You have the option of completing the portion of the study that classifies and delineates the critical
areas and waiting until you have a specific development proposal to complete the study. You may
also choose to submit the entire study with your specific development application.
• Please review the minimum report requirements for all types of Critical Areas that are listed
in ECDC 23.40.090.D. There are additional report requirements for different types of
critical areas (see below).
• Note that it is important for the report to be prepared by a qualified professional as defined
in the ordinance. There are options on how to complete a critical areas study, and there is
an approved list of consultants that you may choose from. You may contact the Planning
Division for more information.
• General Mitigation Requirements for all Critical Areas are discussed in ECDC 23.40.110
through 23.40.140.
STUDY REQUIREMENT — EROSION HAZARD AREA
It appears that this property contains or is adjacent to an Erosion Hazard Area. Erosion Hazard
Areas include:
• Those areas with Alderwood and Everett series soils on slopes of 15 percent or greater.
• Any area with slopes of 15 percent or greater and impermeable soils interbedded with
granular soils and springs or ground water seepage.
• Areas with significant visible evidence of ground water seepage, and which also include
existing landslide deposits regardless of slope.
DEVELOPMENT PROPOSALS ASSOCIATED WITH EROSION HAZARD AREAS
Development within an Erosion Hazard Area must meet additional criteria.
• For erosion hazard areas with suitable slope stability, the only critical area study needed is
an erosion and sediment control plan prepared in compliance with the requirements set
forth in Chapter 18.30 ECDC as part of the construction documents. This option is at the
director's discretion, per Edmonds Community Development Code section 20.80.050.G.
• In areas where the slope stability is not suitable, projects within Erosion Hazard Areas will
require a report by a licensed Geotechnical Engineer or other qualified professional. Note
that it is important for the report to be prepared by a qualified professional as defined in the
ordinance.
• Report requirements are given in ECDC 23.80.050, and more generally in ECDC
23.40.090. D.
• Development standards are given in ECDC 23.80.060 and 23.80.070.
STUDY REQUIREMENT — LANDSLIDE HAZARD AREA
It appears that this property contains or is adjacent to a Landslide Hazard Area.
• A Landslide Hazard Area is any area with a slope of forty percent (40%) or steeper and
with a vertical relief of ten (10) or more feet (except areas composed of consolidated
bedrock).
• Landslide Hazard Areas are further defined and illustrated in ECDC 23.80.020.8.
• In addition to the general requirements for Critical Areas reports referenced above, specific
Critical Area report requirements for Landslide Hazard Areas are provided in ECDC
23.80,050.
DEVELOPMENT PROPOSALS ASSOCIATED WITH LANDSLIDE HAZARD AREAS
Development is restricted within a Landslide Hazard Area and its buffer.
• Projects that will intrude into these areas will require a report by a licensed Geotechnical
Engineer.
• The criteria that are applied depend on the amount that the buffer is reduced.
• The buffer can be reduced to a minimum of ten (10) feet (with an additional 15' building
setback per ECDC 23.40.280) if a report is prepared that meets the standards listed in
ECDC 23.80.050. The alteration must also meet the requirements listed in ECDC
23.80.060.
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• In addition, proposals to reduce the buffer to less than ten (10) feet must comply with the
design standards listed in ECDC 23.80.070.A.3.
If you have any questions about this determination, please contact a Planner for more information.
Michael Clugst
Name
Signature
3, 2010
Date
NOTE: Cited sections of the Edmonds Community Development Code (ECDC) can be found on
the City of Edmonds website at www.ci.edmonds.wa.us.