BLD20030749 CRA REVIEW'—'T 4
October 20, 2000
Kleinfelder Proposal No:
60-2100-02
Mr. Dan Zemanek
Sunrise Development, Ir�c.
249 View Street
Mountain Vxew, California 94041
Subject:
Dear Dan:
Critical Area Review
d
Proposed Assisted Care Living Facility
Southwest Corner Edmonds Way & 1Q2"d Place West
Edmonds. Washin¢ton
Edmon s, Washington
INTRODUCTION
This letter presents the results of Kleinfelder, ]nc.'s (Kleinfelder's) critical areas study for the
referenced project. This study was performed in general accordance with City of Edmonds,
Critical Areas Ordinance, Chapter 20.15B. Kleinfelder previously performed a geotechnical
engineering study for this site. The results of our study are presented in our August 15, 2000
geotechnical report.
PROJECT DESCRIPTION
The proposed development will consist of a 3-story assisted care living facility. The first floor
level will be approximately 27,670 square feet in plan. A 12-foot—wide terrace will be located
on the western side of the proposed building. One level of underground parking is also planned.
The proposed building will be located on the east half of the site as shown in Figure 2.
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60-Z I 0002l6010R 152.doc
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K L E ! N F f � D E R 24Q5 14Qth Avenue, NE, Suite Al Q1, Bellevue, WA 98005 (425) 562-4200 (425) 5b2-4201 fax
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SITE DESCRIPTION
The site is located in the southwest
Washington as shown in Figure 1.
occupied by two residential homes.
corner of Edmonds Way and
1 �2nd
Place West
in Edmonds,
The property is just over one acre in size and is Curren
The developed portion of the site is relatively level.
t1y
The site slopes up to the south just west of the level portion of the property. Based on an August
15, 2000 preliminary topographic map that was prepared by Lovell-Sauerland &Associates, Inc.,
the slope has a maximum inclination of 1-1/2H:1V (up to r
Figure 2.
An adjacent residential devel
�cess roe
of the slope. An ac
slope. A 2- to 5-foo
rockery is located on the north side of the access road.
oughly 60 percen
t} as shown in
opment consisting of three single family houses is located at the top
ad to the residential development is located approximately on the
t high rockery
condition (i.e., no bulging or missing rocks}.
is located on the south side of the access road and a 1-foot
Both rockeries appeared to be in good
Vegetation at the site contains a dense covering of conifer and deciduous trees.
consists of ferns and berry brambles.
During several site visits, we made the following observations:
• No evidence of slope instability (such as slope movemen
leaning trees, hisioric landslidesi
�.
Ground cover
t, soil sloughing,
Groundwater seepage was not visible nor was there evidence of historic
groundwater seepage
No streams are present on the propeny
No evidence of alluvial surficial deposits
SCOPE OF SERVICES
The purpose of this study was to evaluate the potential for geologic hazards that maybe present
at the site. Kleinfelder's geologic hazard is focused to address the City of Edmonds, Critical
... • i rr
Areas Ordinance, Chapter 20.15B. Specifically, we evaluated site specific issues such as buffers,
and steep slope hazard areas and seismic
erosion hazard areas, landslide hazard areas
areas.
60-2 I0402/fi0 t OR152.doc
Copyright 20�0 Kleinfelder, Inc.
K L � I N � � L D � R 2405 � 40th Avenue, NE, Suite A101, 6el�evue, WA 98�05 (425} 562-4200 (425? 562-4201 tax
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SUBSURFACE CONDITIONS
J As part of our geotechnical engineering study, we advanced two soil borings designated GB-1
and GB-2. We also excavated three test pits (designated TP-1 through TP-4) at the base of the
existing hillside as part of this critical areas study. Boring and test pit locations are shown in
Figure 2. Based on the conditions encountered, we characterized the soils and developed the
general strati�aphic profile described below:
•v_J
FiII: Fill material consisting of silty sand was encountered in TP-4 which is
located in the north portion of the site. Some refuse material was encouniered
.� in the fill: Fill was encountered from the ground surface to a depth of about 4
feet.
Glacial Advance Outwash: Glacial Advance Ouiwash was encountered at
�.� each exploration. The test pits and borings were terminated xn this unit This
layer consists of medium dense to very dense sand. The tesi pits were left
open for several hours to monitor for signs of caving. No caving was
observed in the hest pits. The outwash sand has moderate strength,. low to
moderate compressibility, and low moisture sensitivity.
4 Groundwater was not encountered in our borings or test pits.
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More detailed descriptions of subsurface conditions encountered at individual exploration
-- locations are presented on the boring and test pit logs, which are presented in Attachment B.
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GEOLOGIC HAZARD AREAS
Geologic Hazard Ciassificatxon
Potential geologic hazards erosion, landslide, steep slope, and seismic} at the site were classified
in accordance with Section 20. � 5B.�60 "C�assaf cation" of the Critical Areas ordinance. The
specific geologic hazards aye classified below.
���
An erosion hazard is defined as areas
on hazard. The group of soils includes, but is not limited to, the following when they occur
opes of 15 percent or greater:
erosi
on s�
containing soils that may experience severe to very severe
1. Alderwood Soils (15 to 25 percent slopes);
2. Alderwood/Everett Series (25 to 70 percent slopes);
3. Everett Series (15 to 25 percent slopes).
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Copyright 2000 Kleinfelder, Inc.
K L E I N F � L D E R 2405 14�th Avenue, NE, Suite A101, 6ellevue, WA 98005 (425� 56�-4Z00 (425) 562-4201 fax
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The Soil Survey of Snohomish County Washington maps that were prepared by the Unite
Department of Agriculture indicates that the near surface soil in the western portion of the
States
site is
designated as an Alderwood/Everett Gravelly sandy loam (25 to 70 percent slopes). The near
surface soil on the eastern portion of the site classify as an Everett gravelly sandy loam (0 to 8
percent slopes). Therefore, the western portion of the site classifies as an erosion hazard. As
previously stated
Landslide
we did not
observe obvious signs of erosion on the
hillside during our site
According to the Critical Areas ordinance one of the following five criteria must be met in order
to be considered a landslide hazazd. The criteria are:
1. Slopes with inclinations of 15 percent or greater and impermeable soil such as
granular soils and springs or groundwater
silt�and clay interbedded with
seepage.
2. Areas with significant visible evidence of groundwater seepage and includes
existing landslide deposits regazdless of slope.
3. Areas which have shown movement during the Holocene epoch (from 10,000
years ago to present) or which is underlain by mass wastage debris of that
epoch.
4. Potentially unstable areas resulting from rapid stream incision or stream bank
erosion:
5. Areas located on an alluvial fan, presently subject to, or potentially subject to
debris flow ordeposition ofstream-transported sediments.
Based on c
that the sit
r site visits, subsurface explora#ions, and general knowledge of the area, we judge
e does not classify as a Iandsiide hazard as specified in the Critical Area
Basis for our judgement is presented below:.
1. As shown on Figure 2, the slope inclinations along portions of the site exceed
15 percent. However, the subsurface investigation performed for the
geatechnical engineering study did not identify the presence of impermeable
soil, such as silt and clay, on the site.
2. No evidence of springs or groundwater seepage was observed ar noted at the
site.
3. We did not observe historic movement attributed to the Holocene epoch.
4. There are no streams on the site to create unstable areas.
—� 5. The site is not located on an alluvial fan and is not presently or potentially
subject to debris flow or deposition ofstream-transported sediments.
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Copyright 2440 Kleinfelder, Cnc.
K L E i N F E L D E R 2405 3 40th Avenue, NE, Suite A101, Bellevue, WA 980�5 (425) 562-420D (425) 5b2-4201 fax
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There Fs a nossibility that some colluvium is
colluvium
sloughing
localized.
is relatively tivn
approximately 1 t
present along the slope. It is likely that the
0 2 feet thick). There is a potential for some
to occur within the colluvium. Howeve
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r, we believe thai the sloughing should be
Therefore, we believe that the site does not classify as a landslide hazard area.
Stee Slo e Hazard
A steep slope hazard area is classified as any ground that rises at an inclination of 40 percent or
more.
As shown in Figure 2, portions of fihe site have slope inclinations that exceed 40 percent.
Therefore, these portions of the site as shown on Figure 2 are classified as a steep slope hazard.
Seismic Hazard
A seismic hazard area
is classif ed as those areas subs ect �o severe risk of earthquake damage as
a result of seismically induced landslides, earth adjustments, sett�ernent, or liquefaction.
The geotechnical engineering study encountered medium dense to dense glacial advance
outwash deposits to the maximum depth explored of 21.5 feet below the lower portion of the site.
Groundwater was not encountered t� the ma�cimum depth explored.
The Seattle area is subject to ground shaking resulting from seismic events. However, given the
density of the glacial advance outwash soil encountered at the site, the depth of the water table,
and the lack of groundwater seeps at the site, we believe that the site is not subject to landslides,
earth adjustments, settlement, or liquefaction during a seismic event.
Streams
There are no
s�rearns that pass
i
through the property.
Develoz�ment Standards — Geolo�ically Hazardous Areas
As discussed above, the western portion of the site classifies as an erosion hazard area and a
steer slope hazard area and as specified in the Critical Areas ordinance. However, based anon
our evaluation, the site does not classify as a landslide hazard o
Figure 2, a porti
. As shown in
on of the proposed development will be constructed within the erosion and steep
r a seismic hazard
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Copyright 2000 Kleinfelder, Inc.
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sl
ope hazard areas. Therefore, a variance will Likely be required for erosion and steep slope
hazard areas. This �s discussed in more detail below.
Erosion Hazard
Within the erosion hazard area, an approved erosion control plan will
have to be prepared in
accordance to Chapter 1830 ECDC. The plan will have to be approved by the City of Edmonds
- prior to site development. Cle
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r disruption of the soils within an erosion hazard area
should be kept to the minimum necessary to provide reasonable use of the site.
Stee�a Slope Hazard
wring and/o
Because the western portion of the site classifies as a steep slope hazard area, the �ri�ica� Areas
r zone and building setback. Typically, buff
setback distances aze 50 feet and 15 feet, respectively. According
ordinance, the buffer zone and building setback distance requiremen
eliminated if the city grants an exemption or exception pursuant to ECDC 20.15B.040. A
variance can be granted pursuant to ECDE 20.15B.170(A).
e
Ordinance will require a buff
er zone and building
to the Critical Areas
�s can be reduced or
In order to construct the proposed assisted care living facility, an earth retention (shoring) system
will have to be constructed.
dier pile and
site will, for
Seattle area include s
western portion of the
The north end of the earth retention
located on the building itself.
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Two types of earth retention systems that are commonly used in the
tiebacks, or soil nailing. The earth retention system in the
the most part, be located at the we
system on the western side of the p
stern side of the terrace.
roposed building will be
Given the subsurface information obtained from the borings and the recent backhoe test pits, we
judge that both types of systems are viable �al�ernatives for this site. The earth retention system
_ along the steep hazard area (western side of the site} will have to be designed for lateral loads
be induced by the steep slope. Including this type of lateral Loads in an earth retention
esi�n is common and has been successfully constructed in the past.
that will
system c
60-210002/b0 [ OR1 S2.doc
Copyright 20Q0 Kleinfelder, Inc.
K L E I N F E L D E R 24�5 i 40th Avenue, NE, Suite A101, Bellevue, WA 98005 t42S) 562-420U {�25i Sb2-42D1 fax
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CONCLUSION
Based on the information contained herein, the western portion of the site classifies as a steep
sisted care living facility is currently located within
slope hazazd area. Given that the proposed a
the steep slope hazard area, an exemption or
Edmonds.
exception will have to be requested from the City of
Further, an earth retention system will have to be installed in order to conshuct the underground
portion of the facility. In our opuuon, a soldier pile and tieback, or a soil nail earth retention
system can be designed such that the step slope portion of the site is supported with adequate
factors of safety against failure. Because the earth retention system has yet to be desired, a
slope stability analysis has not been performed since all the input parameters are not know at this
time. A slope stability analysis should be performed concurrently with the earth retention system
design.
Therefore, we believe that constructing the proposed building should have little to no impact on
increasing the steep slope hazard or erosion hazard over those for the existing site conditions,
LIMITATIONS
The recommendations contained in this report are based on the subsurface conditions presented
in our Augusfi I Soh geotechnical report and our understanding of the proposed development. The
subsurface data used in the preparation of this report was obtained from the two borings and four
backhoe test pits tha# were performed far .our August 15th geatechnical report and this
investigation. It is possible that variations in the soil and groundwater conditions could exist
befiween the points explored. The nature ,and extent of variations may not be evident until
construction occurs. If any conditions are encountered at this site, which are different from those
described in this report, our firm should be immediately natif ed so that we may make any
necessary revisions to recommendations contained in thus report. In addifiion, if the scope or
location of the planned construc#ion changes from that described in this report, our fum should
also be notified.
This report was prepared in accordance with the generally accepted standard of practice at the
time the report was written. No warranty, express or implied, is made.
It is the Client's responsibility to see that all parties to the project including the designer,
contractor, subcontractors, etc. are made aware of this report in its entirety. The use of
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Copyright 200U Kleinfelder, Inc.
..:.� K L E 1 N F E L D E R 2405 14�th Avenue, N�, Suite A101, BeElevue, WA 98005 (425} 552-�2�0 (425) S&2-�201 fax
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information contained in this report for bidding purposes should be done at the Contractor's
option and risk.
CLOSURE
We appreciate the opportunity to be of service on this project.
Should you have any questions
regarding this report or wish to discuss additional services, please do no
undersigned at (425) 562-4200.
Sincerely,
KLEINF'ELDER, INC.
James M. Schmidt, P.E.
��er, Geotechni
,�
William CB Gates, Ph.D., P.E.
Washington Area Manager
cal Engineering
Attachments:
A: Figure 1
Figure 2
B: Boring Logs GB-1
Test Pit Logs TP-1
through GB-2
through TP-4
C: Authorization to Use
cc: Mr. Jay Janette; Mithun
t hesitate to contact the
EXPIRES SI3�I LOO/
so-x i oaox�so i oR � s2.ao�
Copyright 2000 K]einfelder, Inc.
K L E E N F E � D E R 24�5 140th Avenue, NE, Suite A10i, Bellevue, WA 98005 (425) 5b2-4200 (42S) 562-4�01 fax
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