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LANDAU
�+ MEMORANDUM
�{ p� iA ASSOCIATES
CAL, Itl EMORANDUM emmu.mumIf-00EQW'.1aI.Mbm
TO: Jeannine Graf; Building Official.
City of Edmonds: Development Services Department,.Building Division
FROM: Dennis R. Stettler, P.E.
DATE April. 11, 200s
RE: COMPLETENESS R,EvIEwFOR EARTH SUBSIDENCE AND LANDSLIDE HAzARD AREA
SUBMITTAL PACKAGE -- PLAN REVIEW NO..PRE200$00.0.4
JOHNSON `SFR —16117 74" PLACE WEST
EDMONDS, WASHINGTON
This technical .memorandurnprovides our assessment' of the completeness, of the: geotechnical
portions of .the; permit.submittal package submitted to the City ofEdmonds (City) for the proposed
referenced development within the. Earth Subsidence arid Landslide Hazard Area (ESLHA)of North
Edmonds. This completeness review was accomplished in accordance with Task Order No: '08-06 of
Landau :Associates' On -,Call :Geotechnical Engineering Services Agreement with. the City.
The completeness review is not -intended to be a thorough review of the permit submittal package.
Instead, it is intended to be a cursory review to .assess whether the submittal appears to ;contain the
necessary information :in order to complete a geotechnical peer review in 'accordance with Edmonds
Community Development Code: Chapter ECDC 19.10: As a guide in assessing the completeness of the
package, we referred to the:ESLHA Permit Submittal Checklist.
On. the basis.of our cursory review,,it appears that the submittal package contains a reasonably
comprehensive geotechnical report: and supporting documents appropriate to assess the planned
construction within the ESLHA. However, the City enacted updated requirements for development
within the North Edmonds; ESLHA in mid=20077. as contained in. ECDC.19.10; Any permit :submittals
after the effective date of -the updated ECDC 19.10 must fully address the ,specific. requirements contained
'within that, code. The geotechnical,. report was prepared in March 2007 and the geotechnical declaration
and risk statement was. prepared in November 2007.
Based on our cursory review, it appears.that the geotechnical documents, may -not fully address
the specific requirements; of the updated ECDC 19..10. For example, neither the applicant's March 2007
geotechnical:.report or the.November. 2007 geotechnical letter specifically -references' the :North Edmonds
Earth Subsidence: az d .landslide Hazard .area Summary :Report prepared by Landau Associates, or
specifically addresses the requirement for a_letter addressing the provisions of,ECDC 23.80 (see ECDC
19;10:030 for Minimum required,application submittals and'ECDC 19.1:0:030 H for specific geotechnical
requirements): The. existing.docunients appear to p Aially.address these specific 'requ remI nts..Howe.ver,.
130 2nd Avenue South , Edmonds; -WA 98020 • (.425) 7:78.0SQ7 • fax (4251:7:78-5409: www.lbndauinc.com
they may not fully address the specific requirements since it is not clear from our cursory review that the
geotechnical consultant followed the requirements of the updated ECDC 19.10 in the preparation of their
documents. Without conducting a more comprehensive geotechnical peer review of the geotechnical
documents, it is not possible to identify all of the geotechnical submittal requirements of the updated
ECDC 19.10 that may require further clarification or additional information beyond what has been
submitted (the more comprehensive geotechnical peer review is beyond the scope of this initial
completeness review).
We suggest that the geotechnical consultant review the requirements of the updated ECDC 19.10
and either prepare and submit an updated geotechnical report or a supplemental letter. The revised or
updated geotechnical documents should address the updated ECDC 19.10 requirements or supplement the
existing documents as appropriate with the necessary information. In particular, the geotechnical
engineer should make sure that their documents address all landslide hazards applicable to the site (see
the Landau Associates 2007 Summary Report), the onsite measures taken to correct or reduce the hazards,
as applicable, and the measures taken to mitigate potential impacts from the remaining hazards. We
expect that this additional submittal by the geotechnical consultant should facilitate the review and
approval process.
We note that the geotechnical report refers to the 2008 IBC. The City requires the use of the
2006 IBC and the report should be updated accordingly.
The Permit Submittal Checklist and ECDC 19.10.030 requires a vicinity map that ". . . shall
designate all known landslide masses, or debris flows or mud flows on or near the site ...". A vicinity
map is provided in the permit submittal package which states: "There are no landslides, debris flows or
mudflows within 100 ft of the property lines." In fact, the entire property and each side of the property
are located on top of a large landslide mass, as noted in the geotechnical report. This statement regarding
the existence of landslide masses on the vicinity map should be modified and resubmitted.
A State Environmental Policy Act (SEPA) Checklist was not provided in the materials provided
to us by the City for review. The plans indicate 1,060 cubic yards of grading. Grading in excess of 500
cubic yards requires State Environmental Review and a SEPA Checklist. If the City did not receive a
SEPA Checklist as a part of the permit submittal package, the applicant should prepare and submit a
SEPA Checklist.
Structural calculations were not provided in the materials provided to us by the City for review.
While the scope of our review will not include structural engineering, these calculations are required for
all temporary and permanent shoring, retaining walls, etc. and a review of these calculations to confirm
that the geotechnical parameters have been incorporated into the shoring and retaining wall design as
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appropriate. If the City has not received these structural calculations, they should be provided by the
applicant.
A rockery is shown on the civil plans. ECDC 19.10 generally prohibits rockeries and requires
engineered retaining walls.
It is not clear from our cursory review how retaining walls (for either shoring or permanent
conditions) on the property are addressed in the design. The civil plans refer to design by the
geotechnical engineer. The structural plans include hand -drawn sketches illustrating the general location
of temporary blocks for shoring and permanent retaining walls, but design details are not provided. The
geotechnical report appears to provide design parameters for retaining walls, but not a specific design or
construction plans. Construction of the residence will require significant cuts into existing landslide
debris. The issue of temporary cuts, temporary shoring, and permanent retaining walls needs to be further
addressed by the design team. Temporary shoring plans with supporting calculations are required by the
City.
Permit submittals for projects within the ESLHA require that various statements and declarations
be provided by the Applicant/Owner, Lead Design Professional, Structural Engineer, and Geotechnical
Engineer. A statement from the Geotechnical Engineer was included in the permit submittal package
(although this may need to be updated to be consistent with the updated ECDC 19.10 requirements as
noted above). The materials that we were provided by the City for our completeness review did not
contain the required statements and declarations of the Applicant/Owner, Lead Design Professional, and
Structural Engineer. If these statements and declarations have not been received by the City, these items
should be furnished by the applicant to complete the submittal package.
Our cursory review did not identify other missing items that are required under ECDC 19.10. Of
course, once the more detailed geotechnical peer review is underway, there may be specific items within
the submitted documents that need to be clarified or addressed in order to complete the geotechnical peer
review and recommend approval.
Please contact us if you have any questions regarding this completeness review and when you are
ready for us to commence our geotechnical peer review.
DRS/kes
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