Fritschen-Stewart Rockery Waiver.pdff�c.1890
CITY OF EDMONDS GARY HAAKENSO
MAYOR
121 5TH AVENUE NORTH • EDMONDS, WA 98020 • (425) 771-0220 • FAX (425) 771-0221
Website: www.ci.edmonds.wa.us
DEVELOPMENT SERVICES DEPARTMENT
Planning • Building • Engineering
July 31, 2009
David Fritschen and Deborah Stewart
19925 13th Drive SE
Bothell, WA 98012
RE: Request for waiver per ECDC 19.10.070 for a rockery
16319 75th Place West, Edmonds
Permit Application #BLD20090376 & STF20090020
Dear Mr. Fritschen and Ms. Stewart,
The City is in receipt of your request for waiver to allow installation of a rockery as part
of development of your property 16319 75th Place W, which is currently under review by
the City. The site is located in the Earth Subsidence Landslide Hazard Area which is
regulated under ECDC Chapter 19.10. Rockeries are specifically prohibited in the Earth
Subsidence Landslide Hazard Area as set forth in ECDC 19.10.0701) unless a waiver is
first obtained per ECDC 19.10.070E.
Your request for waiver was sent for peer review by our geotechnical consultant, Landau
Associates, as permitted in ECDC 19.10.070.E. It is their opinion that the Geotechnical
Engineer or Record has adequately demonstrated that the proposed rockery will have no
reasonable likelihood of triggering or otherwise contributing to any landslide hazard or
earth subsidence risk, as specified in that section of the code. The rockery must be
installed per the approved construction plans to be issued with BLD20090376, including
special inspections by the Geotechnical Engineer of Record. It is your responsibility as
property owners to insure the rockery is maintained properly. A copy of their Technical
Memorandum dated July 28, 2009 is attached for your information.
Based on this information., it is my determination that the request for waiver for the
proposed rockery is approved.
Sincerely,
zt-
Ann Bullis, CBO
Building Official
Incorporated August 11, 1890
Sister City - Hekinan, Japan
LANDAU
ASSOCIATES
TECHNICALMEMORANDUM EWMNMENTAi I GEOTECHNICAL j NNURAL RESOURCES
TO: Ann Bullis, Building Official
City of Edmonds, Development Services Department
121 5`h Avenue North
Edmonds, Washington 98020
FROM: Dennis R. Stettler, P. E.
DATE: July 28, 2009
RE: GEOTECHNICAL PEER REVIEW OF ROCKERY WAIVER REQUEST
PROPOSED SINGLE FAMILY RESIDENCE
16319 75m PLACE WEST
EDMONDS, WASHINGTON
Rr=CEJV�!477-
Jkjj_ 2 D 2009
This technical memorandum provides the results of a geotechnical peer review provided on a
request for a waiver related to rockery construction for a proposed single family residence at 16319 75`h
Place West in Edmonds, Washington. Our services were completed in accordance with Task Order No.
09-11 of our On -Call Agreement for Geotechnical and Environmental Services between Landau
Associates and the City of Edmonds (City).
The project is located within the City's designated Earth Subsidence and Landslide Hazard Area,
and as such falls under the specific requirements of Edmonds Community Development Code (ECDC)
provisions 'related to development in landslide hazard areas as contained in ECDC 19.10 and ECDC
23.80. Landau Associates previously provided a geotechnical peer review of the plains and project
documents and the results of our review are contained in our March 28, 2007 and September 12, 2007
technical memoranda. We understand that the property ownership has since changed and the new owners
intend to construct a single family residence that conforms to the plans previously reviewed in 2007.
:However, ECDC 19.10 was revised and updated in 2007. As a part of those revisions, certain types of
construction were prohibited because of the potentially adverse effects of such construction on slope
stability within the Earth Subsidence and Landslide Hazard Area. One of the types of construction that
was prohibited was rockeries. The plans submitted and reviewed in 2007 included a rockery wall along a
portion of the north side of the property and along portions of the south and east sides of the property.
The rockery is considered prohibited construction in accordance with ECDC 19.10.070.D. Section
ECDC 19.10.070.E indicates that the prohibitions "shall apply unless the property owner requests a
waiver based upon the written analysis of a geotechnical engineer which clearly establishes. that the
proposed improvement will have no reasonable likelihood of triggering or otherwise contributing to any
landslide hazard or earth subsidence risk either on the site or in the neighboring earth subsidence of
landslide hazard area."
130 2nd Avenue South • Edmonds, WA 98020 • (425) 778-0907 • fax (425) 778-6409 • www.landauinc.com
Landau Associates has reviewed a letter provided to us by the City from HWA Geosciences, Inc.
dated July 20, 2009 titled: Rockery Waiver Request, FritschenlStewart Property Development, 16319
75rh Place West, Edmonds, WA, City of Edmonds Plan Check No. 20090376. In our opinion, HWA
Geosciences has adequately addressed the technical issues required to satisfy the request for a waiver to
allow construction of the rockery wall consistent with the previously approved project plans.
This technical memorandum has been prepared for use by the City of Edmonds in evaluating the
adequacy of a rockery waiver request related to the proposed single family residence at 16319 75th Place
West in Edmonds, Washington. The focus of our review was the geotechnical aspects of the waiver
request and the purpose of our review was to assess the adequacy of the application documents for
compliance with ECDC 19.10 requirements for development within landslide hazard areas and
conformance with conventionally accepted geotechnical engineering practices. The geotechnical peer
review by Landau Associates does not lessen the requirements for the applicant's geotechnical
consultant and other design professionals to prepare an appropriate design for the site conditions.
We appreciate this opportunity to be of service to the City of Edmonds. Please contact us if you
have any questions or if we may be of further service.
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7128109 1\Edmdata\projects\07411385FileRoom\RlRockeryWaiverReview_tm.doc I-ANDAU AssoUATES
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A-GEOSCIENCES INC.
hnical & Pavement Engineering • Hydrogeology • Geoenvironmental • Inspection & Testing
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July 20, 2009copy
HWA Project No. 2003-174-21-1300
TO:
David Fritschen
and Deborah Stewart
19925 13th Dr S.E.
Bothell, WA 98012
Subject: ROCKERY WAIVER REQUEST
CC:
Ann Bullis and Pat Lawler
RECEIVED
JUL 2 3 2009
BUILDING DEPAR-rMEly
OTY of FDMONna
Edmonds Development Services
121 5th Avenue North
Edmonds, WA 98020
Fritschen/Stewart Property Development
1631975 th Place West, Edmonds, WA
City of Edmonds Plan Check No. 20090376
As part of the proposed site development, rock -faced retaining walls are proposed to facilitate
minor grade changes in the development area footprint, for the above -subject development. It is
understood that ECDC (Edmonds Community Development Code) Chapter 19. 10, Section 070,
prohibits rockeries in the North Edmonds Earth Subsidence Landslide Hazard Area (ESLHA).
In accordance with the provisions of ECDC 19.10.070(E), a waiver is requested.
The proposed site grading and development plans include rock -faced gravity retaining walls.
There are two such proposed walls for this project. The north wall is approximately 80 feet long,
it extends east/west, and it will retain 2 to 4 feet cut to facilitate the grade change from the
proposed driveway/yard Elevation 102 feet down to the landscaping area at existing and final
proposed Elevation 98 to 100 feet. The proposed south/east wall extends approximately 145 feet
along the south and east sides of the development footprint. It would will retain a cut into
existing grade surface to facilitate the driveway/yard grading at approximate Elevation 102 feet;
exposed height of this wall will vary from less 2 feet at the north and west ends, to a maximum
of about 6%2 feet behind (south of) the proposed garage.
These proposed rock -faced gravity walls have been called rockeries on the plans and in our
reports. However, these are not rockeries in the traditional sense. The trade group Associated
Rockery Contractors (ARC) describes traditional rockeries as, "a protective system which helps
to retard the weathering and erosion process acting on an exposed cut or fill soil face." In
contrast, the proposed rock -faced retaining walls are engineered gravity retaining structures.
These rock -faced retaining walls were designed by an HWA geotechnical engineer and
Washington State licensed civil engineer. Detailed design and construction requirements, and
our design and stability calculations, are presented in our report dated April 23, 2004, which was
previously submitted to the City of Edmonds. As discussed in that design 19730 - 64th Avenue w
report, the wall will be constructed in accordance with current City of Edmonds sane aoo
July 20, 2009
HWA Project No. 2003-174-21-1300
1) The wall will be constructed with a batter of 6V:1H (horizontal:vertical).
2) A foundation pad of compacted crushed rock, at least one foot thick and extending at
least one foot beyond the front and back of the base rock course, is necessary for
foundation stability.
3) An envelope of compacted, freely -draining crushed rock should extend behind the back
face of the rockery a horizontal distance of W2 (where H is the exposed wall height)
along the entire wall. The purpose of this crashed rock envelope is to increase sliding
and overturning stability of marginal existing site soils (slide debris) that will be retained.
The crushed rock will have less than 5% fines (silt and clay) content and will therefore be
freely draining to avoid buildup of hydrostatic pressure behind the wall backfill.
In short, the proposed rock -faced retaining walls include a significant mass/volume of compacted
crushed rock, which combined with the rockery fascia, will act as a gravity retaining structure.
These walls will retain the existing site soils in a similar way to a segmented pre -cast concrete
block retaining wall, which is apparently considered acceptable in the ESLHA.
In 2007, the current development proposal was submitted to the City of Edmonds for review and
permitting for then -current owner/applicant Andrew Shubin. The undersigned acted as the lead
design professional for the Shubin development proposal. The development and grading plans
for the current Fritschen/Stewart development are essentially the same as they were in 2007. In
2007, a geotechnical peer review was completed by Landau Associates. The geotechnical peer
review (GPR) memo by Landau, dated March 28, 2007, took no exceptions to our rack -faced
wall design.
It was shown in our original geotechnical report dated February 25, 2004, and our rockery
addendum design dated April 23, 2004, that the proposed site grading and rock wall construction
would have no reasonable likelihood of triggering or otherwise contributing to any landslide
hazard or earth subsidence risk, either on the subject site or any adjacent properties. Providing
that the rock -faced wall is constructed in accordance with our recommendations under periodic
inspection by HWA geotechnical engineers or our representatives, there will be no decrease in
the stability of the subject or adjacent sites. Moreover, the walls are constructed per our
recommendations under our observation, there will be no reasonable likelihood of triggering or
contributing to any landslide hazard or earth subsidence risk on the subject or adjacent
properties.
Finally, because the proposed development was reviewed and accepted by the City of Edmonds
and their designated GPR agency in 2007, it reasonable in our opinion that this same design
would be considered acceptable in 2009.
2003-174-21-300 Rockery Waiver Request 2 HWA GEOScmNCES INC.
July 20, 2009
HWA Project No. 2003-174-21-1300
We trust that the foregoing, along with our previously submitted geotechnical reports, are
adequate for the City to consider a rockery waiver under ECDC 19.10.070(E).- If you require
additional information or we may be of further service, please contact the undersigned at (425)
774-0106.
Sincerely,
HWA GwSap-Ncy-s INc.
X9
Erik O. Andersen, P.E.
Senior Geotechnical Engineer, Vice President
2003-174-21-300 Rockery Waiver Request 3 HWA GEOSCIENCES INC.
Stewart/Fritschen
19925 13th Drive SE
Bothell, WA
98012
David_ Fritschen@msn.com
chili pprs e,hotmaii_com
Phone: 206-271-9499 David
Phone: 206-941-6093 Deb
July 20, 2009
City of Edmonds
Building Division
Re: BLD20090376
16319 75th Place W Edmonds, WA
Attention: Pat Lawler
Plans Examiner
Plan Review Comments addressed:
RECEIVED
JUL 2 3 2009 .
SUILDENG DEPARTMENT
CITY OF EDMONDS
1. No response as indicated on the City of Edmonds letter dated July 8, 2009.
2. Stamped letter from Erik Anderson as requested.
3. Letter and details from Norm Navarro Engineering addressing shear walls.
5 Completed City of Edmonds special inspection forms with HWA GeoSciences Inc. being fired for all
special inspections_ (2 forms attached)
6 Completed City of Edmonds Energy and Ventilation forms_
Details and product data for the tempered glass railings.
8 We would like to go with option 8(a) Waiver possibility for the Rockeries. Attached please find a report
from Erik Anderson setting out his opinions regarding the Rockeries. ($500.00 deposit included)
Structural Comments addressed:
1. Addressed in Plan Review section
2. Letter and details from Norm Navarro Engineering
3. Letter and details from Norm Navarro Engineering
4. Letter and details from Carolyn Jewett CG Engineering
Please forward any other requests or comments to our lead design professional Erik Anderson.
Regards
Deborah Stewart/David Frits