23605 101ST AVE W.PDF87
23605 101 ST AVE W
Dennis M. Bruce, P.E.
M-S.C.E., M.B.A. Geotechnical /Civil Engineer
November 10, 2012 -
City of Edmonds
C/o Randy Burke
23605 101 `4 Ave. W.
Edmonds, WA 98020
Subject, Geotechnical Evaluation — Stabilization"Wall Critdfla
Burke Property at 23605 101't Ave W. 11 1
City of Edmonds Plan Check No. 2012-0570
This engineering report presents the results of a geotechnical evaluation of the
Burke property at the above address. This evaluation was required due to City of
Edmonds plan review comments dated July 27, 2012 regarding slope stability, and. the
I I
existing and proposed stabilLm ton wall project.
REFERENCES:
0 Property survey and site plan furnished by owner
0 Previous wall designs by Jason Engineering dated May 14, 2012
0 City of Edmonds 6 0-mment letter dated July 27, 2012
0 Site photographs 4y,,;D. Bruce', P.E.
BACKGROU66:
,I'
Thd'overall Burke property is trapezoidal in shape (at the e "d a cul-de-sac).
See'site plan. Mr. Burke has placed eco-blo6ks in a stabilizing wall manner for portions
of his property. See photographs.
I
Tfiis engineer understands �h'afdu'r'ing attempts to continue placing, the eco-block
walls along the northern property line, the City of Edmonds performed on -site
inspections and issued a "Stop Work Order" and req&sted additiona'U soils information.
This report provides the results of this engineer's evaluation, conclusions and
design recommendations for the proposed continuation of the stabilization wall.
RESUB
NOV 16 2012
BUILDING DEPAR�-_MENIT
CITY OF EDMONDS
SOILS - FOUIVDA77ONS - SrrE DEVELOPME14T - WSPEC770N - DRAINAGE * DESIGAI & PERMIT e LEGAL
P.O. Box 55502 - Shoreline, WA 98155 - (206) 546-9217 - FM (206Y646-8442
STREET FILE
City of Edmonds
Re: Burke Property at 23605 — 101-9Ave W.
November 10, 2012
Page 2
EVALUATION:
In order to augment the existing site geotechnical information, two (2) soil test
holes were dug under this engineer's observation on October 12, 2012. Additionally,
the majority of the site is in an "excavated" condition, easily allowing for evaluation of
the native subgrade soils.
Both test holes revealed similar subgrade conditions, namely-
0" to 4. 0' Dense native sands and gravel
No groundwater was observed in either of the two test holes. No evidence of
groundwater seepage or erosional rutting was observed on the excavated north
property line face.
The subgrade soils are considered dense stable outwash.
EXISTING SLOPE CUT:
See photographs.
The rear (northerly) property line has been partially excavated. The excavation is
currently geotechnically stable as is, (with protective plastic covering). However, this
engineer strongly recommends a more permanent, property designed and installed, and
legally permitted through City of Edmonds, stabilization wall.
This engineer agrees with City of Edmonds July 27, 2012 memo requiring
geotechnical inspections during placement of the wall.
CONCLUSIONS I RECOMMENDATIONS:
Based on the findings of this investigation, and experience with similar sites in
the area, the Burke property is geotechnically approved for the proposed continuation
stabilization wall, subject to the following:
0 Legal permit and approval obtained from City of Edmonds.
Geotechnicai inspections for the placement of the eco-biock stablilzatio-In w-U-11.
* Allowable bearing pressure: 3,000 p.s.f.
City of Edmonds
Re: Burke Property at 23605 — 101sAve W.
November 10, 2012
Page 3
9 Equivalent fluid pressure of 30 p.c.f. is recommended.
* Use friction factor of 0.55 and passive pressure of 350 p.c.f.
Geotechnical inspections by this engineer prior to any eco-block placement.
Note: Periodic inspections during construction of eco-block wall to verify the
following: Base block embedment, block batter, linkage, drainage zone and
overall "blending in" with the existing slope and topography.
EXCAVATION AND SLOPES:
At the time of this investigation and report, the site has been "generally"
excavated to approximate eight foot (8.0') depths. See photographs.
As the attached eco-block wall designs require, the maximum height of
wall will be ten feet (10. 0').
It is essential that the eco-block wall contain a batter of 1 H:6V (on -site
inspections to verify).
In no case should excavation slopes be greater than the limits specified in local,
state and national government safety regulations. Temporary cuts up to a height of
four (4) feet deep in unsaturated soils may be vertical. For temporary cuts having a
height greater than four (4) feet, the cut should have an inclination no steeper than 1:1
(Horizontal:Vertical) from the top of the slope to the bottom of the excavation. Under
specific recommendations by the geotechnical engineer, excavation cuts may be
modified for site conditions. All permanent cuts into native soils should be inclined no
steeper than 2:1 (H:V). Fill slopes should not exceed 2H:lV. It is important to note that
sands do cave suddenly, and without warning. The contractors should be made aware
of this potential hazard.
Water should not be allowed to flow uncontrolled over the top of any temporary
or permanent slope. All permanently exposed slopes should be seeded with an
appropriate species of vegetation to reduce erosion and improve stability of the surficial
layer of soil.
DRAINAGE CONSIDERATONS:
Footing drains are recommended at the base of all eco-block walls. These
drains should be surrounded by at least six (6) inches of one -inch -minus washed rock
City of Edmonds
Re: Burke Property at 23605 — 101`4 Ave W.
November 10, 2012
Page 4
wrapped in non -woven geotextile fitter fabric (Mirafi 140N, Supac 4NP, or similar
material). At the highest point, the perforated pipe invert should be at least as low as
the bottom of the lowest eco-block and it should be sloped for drainage.
No groundwater was observed in either of the two test holes during the fieldwork.
Seepage into the planned excavation is possible, and likely if excavation occurs during
winter months, and if encountered should be drained away from the site by use of
drainage ditches, perforated pipe, French drains, or by pumping from sumps
interconnected by shallow connector trenches at the bottom of the excavation.
The excavation of the site should be graded so that surface water is directed off
the site and away from the tops of slopes. Water should not be allowed to stand in any
area where foundations, slabs, or pavements are to be constructed. Any exposed
slopes to be covered with plastic to minimize erosion. Final site grading in areas
adjacent to buildings should be sloped at least two percent (2%) away from the building,
except where the area adjacent to the building is paved.
Geotechnical inspections to verify that all slopes are stable and all surface water
flow complies with City of Edmonds requirements.
GENERAL EARTHWORK AND STRUCTURAL FILL:
The proposed eco-block wall alignment should be stripped and cleared of all
surface vegetation, all organic matter, and other deleterious material. The stripped or
removed materials should not be mixed with any materials to be used as structural fill.
NOTE: Please comply with City of Edmonds clearing limits as required on
approved plans.
Structural fill is defined as any fill placed under the building, behind permanent
retaining or foundation walls, or in other areas where the underlying soils needs to
support loads. This engineer should observe site conditions during and after excavation
prior to placement of any structural fill.
All structural fill should be placed in horizontal lifts with a moisture content at or
near the optimum moisture content. The optimum moisture content is that moisture
content which results in the greatest compacted dry density. The moisture content of fill
50:11S :- - --- - :-- --4--4& --A & —1---k. M—+-11 A A.."�— +k= fiffirwi tanrl r-r%mmae-tirwn
I Ib vq:�[ Y 111 Ipul um It c3l Ou I I luw. u=
process.
The allowable thickness of the fill lift will depend on the material type, compaction
equipment, and the number of passes made to compact the lift. In no case should the
City of Edmonds
Re: Burke Property at 23605 — 1OV4 Ave W.
November 10, 2012
Page 5
lifts exceed twelve (12) inches in loose thickness. The following table presents
recommended relative compaction for structural fill:
Location of Fill Placement
Beneath footings, slabs or walkways
Behind retaining walls
Beneath pavements
Minimum Relative
Compaction
95%
90%
95% for upper 12 inches of
Sub -grade, 90% below that level
Where: Minimum relative compaction is the ratio, expressed in percentages, of
the compacted dry density to the maximum dry density, as determined in
accordance with ASTM Test Designation D-1 557-78 (Modified Proctor).
Use of On -Site Soils
If grading activities take place during wet weather, or when the sandy on -site
soils are wet, site preparation costs may be higher because of delays due to rains and
the potential need to import granular fill. The on-sfte soils are generally sandy and thus
are not highly moisture sensitive.. Grading operations will be difficult when the moisture
content of these soils greatly exceeds the optimum moisture content.
Moisture sensitive soils will also be susceptible to excessive softening and
.pumping" from construction equipment traffic when the moisture content is greater than
the optimum moisture content.
Ideally, structural fill, which is to be placed in wet weather, should consist of a
granular soil having no more than five (5) percent sift or clay particles. The percentage
of particles passing the No. 200 sieve should be measured from that portion of the soil
passing the three -quarter -inch sieve.
The use of "some" on -site soils for fill material may be acceptable if the upper
organic materials are segregated and moisture contents are monitored by engineering
inspection.
As stated, the on -site soils are excellent for support of the proposed wall, backfill
material and drainage.
City of Edmonds
Re: Burke Property at 23605 — 101" Ave W.
November 10, 2012
Page 6
DRAINAGE CONTROLS:
No drainage problems were evident with the existing site and slope cuts.
The proper completion of the eco-block wall (subject to geotechnical
inspections), will improve overall site stability and proper surface water control.
SLOPE STABIUTY:
This engineer's on -site evaluation has determined that continuation of the eco-
block wall is necessary to provide long-term slope stability, thus providing additional
support and stability for the northerly adjacent property.
Currently, the excavated cuts are stable (as protected with existing plastic
covering). The proper installation of the proposed eco-block wall will provide long-term
protection and stabilization.
INSPECTIONS:
The recommendations of this report are only valid when key geotechnical
aspects are inspected by this engineer during construction:
0 Soil cuts
• Base eco-block sub -grade verification
• Eco-block wall inspections (as discussed in this report)
• Any fill placement
• Subsurface drainage installation
• Temporary and permanent erosion control measures
SUMMARY:
The proposed eco-block stabilization wall for the Burke property is
geotechnically approved when constructed in accordance with the recommendations
herein, compliance with City of Edmonds approved plans and requirements, and key
geotechnical inspections during c9ristruction.
CLOSURE:
The findings and recommendations of this report were prepared in accordance
with generally accepted professional engineering principles and practice. No other
warranty, either express or implied, is made. The conclusions are based on the results
City of Edmonds
Re: Burke Property at 23605 -7 101 st Ave W.
November 10, 2012
Page 7
of the field exploration and interpolation of subsurface conditions between explored
k>cations. If conditions are encountered during construction that appear to be different
than those described in this report, this engineer should be notified to observe the
situation and review and verify or modify the recommendations.
If there are any questions, do not hesitate to call.
DMB-vIb
cc: Randy Burke
M PC I M ViA
"F-JOHT
(S- -S Locia-
Dennis M. Bruce, P.E.
Geotechnical / Civil Engineer
-F LO e K
13 AS 15 e
r10*4-
006 T
L.- 7,Jr
CITY OF EDMONDS
1215 1h Avenue North, Edmonds WA 98020
Phone: 425.771.0220 * Fax: 425.771.0221 * Web: www.edmondswa.gov
DEVELOPMENT SERVICES DEPARTMENT - PLANNING DIVISION
-(J7C. IS91J
Critical Areas Reconnaissance RePort Update
um er-
"N
ticd :-A' b
... .... ...
Determination Study Required
'Site.L&j�� ve;-S
Tax Account Number 00446700001000
Prop�qy..---,
Applicant Some
s 616- /1 "'H ous;�Areas.�-!�I
A Ge* y azard
reos.�Pre
r c'
11.:�.d fid
-hazdrdA�eds,�-.,I .... ..
an si e
THIS PARCEL WAS PREVIOUSLY IDENTIFIED AS AWAIVER-' IN
2002. HOWEVERY THE CRITICAL AREAS CODE UPDATE OF
2005 REQUIRES REASSESSMENT OF THE ORIGINAL
DETERMINATION.
Site Description
During review and inspection of the subject site, it was found that the site may contain (or be adjacent to) critical
areas, including Geologically Hazardous Areas (Erosion and/ or Landslide Hazard Areas), pursuant to Chapters
23.40 and 23.80 of the Edmonds Community Development Code (ECDC). Geologically hazardous areas include
areas susceptible to erosion, land sliding, earthquake, or other geological events. They pose a threat to the health
and safety of citizens *when incompatible development is sited in areas of significant hazard. Such incompatible
development may not only place itself at risk, but also may increase the hazard to ' surrounding development and.
use. C ited sections of the Edmonds Community Development Code can be found on the City of Edmonds website
at www.edmondswa.gov.
The associated LiDAR map indicates that the southern half of the parcel is basically level but slopes quickly up to
the Old Woodway High School site with grades in excess of 50%. Soils on the property are identified primarily as
Everett Gravelly sand loam (0 — 8% slope) with a small section of Alderwood Urban land complex (2% - 8% slope)
near the northeast corner of the parcel. As a result, the slopes in excess of 15% are classified as a potential erosion
hazards and the portion that exceeds 40% is a potential landslide hazard area.
Allowed Activities & Exempt Proposals
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 Plannerfor more information.
General Report 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
classifie's and delineates the critical areas and waiting until you have a specific development proposal to complete
the study. You may also choose submit the entire study with your specific development application. Please review
the minimum report requirements for all types of Critical Areas which are listed in ECDC 23.40.09O.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 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.
Erosion Hazard Areas
Erosion Hazard areas include Alderwood and Everett series soils on slopes of 15 percent or greater, among others.
Landslide Hazard Areas are further defined in ECDC 23.80.020.A. In addition to the general requirements for
Critical Areas reports referenced above, specific Critical Area report requirements for Erosion Hazard Areas (which
are one of the Geologically Hazardous Areas) are provided in ECDC 23.80.050.
Note that Stable Erosion Hazard Areas may have limited report requirements at the director's discretion. At a
minimum an erosion and sediment control plan prepared in compliance with the requirements in ECDC Chapter
1&30 shall be required.
Development is restricted within an Erosion Hazard Area and must meet additional criteria. For erosion hazard
areas with suitable slope stability, an erosion and sediment control plan prepared in compliance ECDC 18.30 will be
considered to meet the Critical Areas "Study Required" determination. The determination of "suitable slope
stability"� will be made by both the Planning and Engineering divisions of the City of Edmonds. In areas where the
slope stability is not suitable, projects within Erosion Hazard Areas will require a report by a licensed deotechnical
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�.�0.090.13. Development standards are given in ECDC 23.80.060 and 23.80.070.
Page 12
Landslide Hazard. Areas
Development is restricted within a Landslide Hazard Area and its buffer. Projects that will intrude into these areas
I
will require a report*by a licensed Geote.chnical Engineer. Geologically hazardous areas include areas susceptible
to erosion, land sliding, earthquake, or other geological events. They pose a threat to the health and safety of
citizens when incompatible development is sited in areas of significant hazard. Such incompatible development
may not only place itself at risk, but also may increase the hazard to surrounding development and use.
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 ECDC
23.80.060. 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. 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.
Determination: Study Required
This review applies to the entire subject parcel, Depending on the location and project proposed relative to the
identified critical areas, certain studies and reports may be required. Please contact the Planning Division at
425.771.0220 if and when you have a specific development proposal for this site in order to discuss the various
permits that will be required.
Mike Clugston, Associate Planner
Name, Title
Signat
July 19, 2012
Date
Page 13
CA File No. C)a 01
Critical Areas Checkli*st
Sife Info mmation (soils/ topography/ hydrolo y/vegetation)
gy
1. Site Address/ Location: - .2 Z (5
2. Property Tax Account Number: Oto�)
3. Approximate Site Size (acres or square feet):
4. Is this site currently developed? _)�Yes; no.
If yes; how is site developed? iloot
5. D the general site topography. Check all that apply.
Flat: less.than 5-feet elevation change over entire site.
Rolling: slopes on site,gen'er�lly less than 15% (a vertical rise of 10-feet over a horizontal
distance of 66-feet).
Hilly: slopes present on site of more t�an 15 % and less than. 30 % a vertical rise, of 10-feet
over a horizontal distance of 33 to 66-feet).
Steep: grades of greater than 30% present on site (a vertical rise of 10-feet over a horizontal
distance of less than 33-feet).
Other (please describe):
6. Site contains areas of year-round standing water: ovo Approx. Depth:.
7. Site contains areas of seasonal standing water: Approx. Depth:
What season(s) ofthe year?
8. Site is M' -the floodway k)e9floodplain of a water course.
9. Site= arek or an area where water flows �qrbss the grounds surface? Flows are year-round?
Flows are seasonal? (What time of year?
10. Site is primarily: forested 0 0 meadow Q 0 shrubs k.) 0 mixed
urban landscaped (lawnshrubs etc) LIP C
11. ,'Obvious wetland is present on site:
C - S .!nap _�d,
s"
4.'..".--,Critie91- e", bory 6r:CA,-diap',indi&
Site. widiih de�ik . hait�de"'SUbsid66e-J"
Revii§wCidt
MT-11-
2� 74;!
c
jL,
AnONI'',r�.
K% AN
;e2
Z�
Critical Areas Checklist.doc/3.19.2001
City of Edmonds
Development ServicesDepartment,
Planning Division
Phone: 425.771.0220
Fax: 425.77.1.0221
The Critical Areas Checklist contained on this form is to
be filled out by any person preparing a Development
Permit Application for the City of Edmonds prior to
his/her submittal of the application to the City.
The purpose of the Checklist is to enable City staff to
determine whether any potential Critical Areas are", or
may be, present. on the subject property. The information
needed to complete the Checklist should be -easily.
available from observations of the site or data available at
City Hall (Critical areas inventories, maps,� or soil
surveys).
Date Received:
City Receipt#: V& W
Critical, Areas File M A �Riiiip V;22='..-Z00L-W9
Critical, Areas Checklist Fee: $45.00
Date Mailed to, Applica'nt: —0
A property owner, or his/her authorized representative,
must filf out the checklist, sign and date it, and submit it
to the City. The City will review the checklist, make a
precursory site visit, and make a determination of the
subsequent steps necessary to complete a development
permit ' lication.
PIPP
Please submit a vicinity map; along with the signed copy
of this form to assist City staff in finding and locating the
specific piece of property described on this form. In
addition, the applicant shall include other pertinent
information (e.g. site plan, topography map, etc.) or
studies in conjunction with this Checklist to assistant staff
in completing their preliminary assessment of the site.
The undersigned applicant, and histher/its heirs, and ass�gns, in consideration on the processing of the application agree,
to release, indemnify, defend and hold the City of Edmonds'harmless from any and all damages, including reasonabl(
attorney's fees, arising from any action or infraction' based in whole or part upon false, misleading, inaccurate oi
incomplete information furnished by the applicant, his/her/its agents o . r employees.
By my signature, I certify that the information and exhil;it� herewith submitted are true and correct to the best of m3
knowledge and that I am authorized to file ppli f of the owner as listed below.
7itio,,n o ,PtYie b al
/\O
J.4
r.lm 111A
DATE
SIGNATURE OF APPLICANVAGENT
Property Owner's Aut horization
By my signature, I certify that I have authorized the bove Applicant/Agent to apply for the subject land use application,
and grant my permission for the ublic officia an the staff of the City of Edmonds to enter the subject property for the
purposes of inspection and pol g a ndau appliciaiion.
SIGNATURE OF OWNER DATE 2—
PLEASE PRINT CLEARLY
7er/A plicant:
— A /0 TJ
Name
— 2=3
71e Address
City State Zip
Telephone: 2 V(0 - _�;-q,2 - 6
Email address (optional):
Critical Areas Checklist.doc/3.19.2001
Applicant Representative:
T 11,�
City S.tatte Zip
Telephone:
Email Address (optional): R E C E I V E D
I '
MAY - 2 2002
PERMIT COUN-NER
I'S (
CA C�Q,
V,
t I
S-
.7
Gi L
X/11 $1
ri
—T-
-7 4, C>q
S-Irf� -INVMT701?41� W&
0 Soil cuts
0 Base eco-block sub -grade verification
0 Eco-block wall inspections (as discussed in this report)
0 Any fill placement
0 Sub�surface drainage installation'
e 'Temporary and permanent erosion control measures
prwidz Wedk-tv AAd 64.1
wAlAaw Luwaw-
7 !
P
ON -Qlrkr,
ir
in thja permit appwal, pr0CM sball H
as I allowing or permittft the
11 �
of aay cuunnk "istin MCPk
tted buil= AM*=
g of unpe m.
I I ide tke scopt Of tbc
site condit:bn whicii -.s onts'
ro= r. 1SV
't application, re9wrdless of whz-*`ff Swh
saucture or -,)rkdluOR is Shown On the
Ian drawing. Sjc!-; beilding, Viucft= V*
con ttn= be the --m*cx `1 a 9QP',:Lue
f n�zt actior
City of Edmondg Building Department
MTA t A 13, 111
W,
Al;
ERICONTRACTOR IS RESPONSIBLE
EROSION CONTROL AND DRAINAG
ENGINE RING D
"AS I
APPROVED 3Y PLANNING
Aur/M— (-4�1
d--±— u�
&D 7f) 1z o 5 7 0
ZonelZ �- e' Comer Flag <
Setbacks
-RMuired
Actual
Front
--7.5-+
Sides
7 5'
Rear
7. S-
-T r
Other
-� �S-
-7,5--�-
Heigbt
19-
10 -
Ki 11 n
JUL 13 2012
DE-VEUjFME`i,t.�',r SERVICE
GI -Pt OF EMOKIDS
------.K^-N-D-Y T � 13UKKE
-ta-6�0- !�T E�p MaNPS, # W A
PLOT -PLAN.. STREET FILE
ION
21