CANOD.pdfCity of Edmonds
Critical Area Notice of Decision,
Applicant:
Property Owner:
Critical Area File
'2, o ( 2-
Permit Number:
Site Location:
Parcel Number:
o 1030c"C
Project Description:
❑ Conditional Waiver. No critical area report is required for the project described above.
I There will be no alteration of a Critical Area or its required buffer.
2. The proposal is an allowed activity pursuant to ECDC 23,40.220, 23.50.220, and/or
23.80.040.
3. The proposal is exempt pursuant to ECDC 23.40.230.
Fj Erosion Hazard. Project is within erosion hazard area. Applicant must prepare an erosion and
sediment control plan in compliance with ECDC 18.30.
Critical Area Report Required The proposed project is within a critical area and/or a critical area
buffer and a critical area report is required. A critical area report has been submitted and evaluated
for compliance with the following criteria pursuant to ECDC 23.40.160:
1 The proposal minimizes the impact on critical areas in accordance with ECDC 23,40,120,
Mitigation sequencing;
2, The proposal does not pose an unreasonable threat to the public health, safety, or welfare
on or off the development proposal site;
3. The proposal is consistent with the general purposes of this title and the public interest;
4. Any alterations permitted to the critical area are mitigated in accordance with ECDC
23.40.110, Mitigation requirements.
5. The proposal protects the critical area functions and values consistent with the best
available science and results in no net loss of critical functions and values; and
6. The proposal is consistent with other applicable regulations and standards,
❑ Unfavorable Critical Area Decision, The proposed project is not exempt or does not adequately
mitigate its impacts on critical areas and/or does not comply with the criteria in ECDC 23,40.160 and
the provisions of the City of Edmonds critical area regulations. See attached findings of
noncompliance.
68- Favorable Critical Area Decision. The proposed project as described above and as shown on the
attached site plan meets or is exempt from the criteria in ECDC 23.40.160, Review Criteria, and
complies with the applicable provisions of the City of Edmonds critical area regulations. Any
subsequent changes to the proposal shall void this decision pending re -review of the proposal.
❑ Conditions. Critical Area specific condition(s) have been applied to the permit number referenced
above. See referenced permit number for specific condition(s).
Reviewer
Signature d
Date
Appeals: Any decision to approve, condition, or deny a development proposal or other activity based on the
requirements of critical area regulations may be appealed according to, and as part of, the appeal procedure, if any,
for the permit or approval involved.
Revised 12/16/2010
24'„W
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Existing 6' Fence
Existing Hous
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Property Owner: Michael Lawyer
Property Address: 8001 184th St. SW, Edmonds, WA 98026
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May 17, 2012
HWA Project No. 2012-000-21 Task 8
Mike Lawyer
8001 184th Street SW
Edmonds, Washington 98026
Subject: GEOTECHNICAL ASSESSMENT REPORT
Fence & Deck Construction
8001 184th St SW
Edinonds, Washington
Dear Mr. Lawyer;
This report addresses the applicable requirements of the ECDC with regard to the construction of
a new fence and expansion of your existing deck, both along the eastern side of your property
located at 8001 180' St SW (See Figure 1). Communications from the City of Edmonds indicate
that the proposed fence and deck expansion will be constructed within the minimum required
setback from a Landslide Hazard Area, and within an Erosion Hazard Area. The purpose of this
report is to assess whether the proposed fence and deck construction will impact local slope
stability and the potential for site erosion consistent with the requirements of the ECDC. Our
work included a site reconnaissance, limited subsurface exploration, ECDC code review, and
writing this report.
PROJECT DESCRIPTION
Currently, an elevated wooden deck is attached to the northern side of the residential structure.
The deck is approximately 10 feet wide and extends along the house to the west away from the
steep slope, as shown on Figure 2. From our meeting and discussion new construction will
consist of-
* Extending the deck approximately 5 to 6 feet to the east by way of adding a staircase to
the current ground surface.
® Constructing a fence that goes east from the northern point of the existing fence to the top
of the existing rockery at the northern end then parallels the rockery to the south and
turns west at the southern end of the house to connect with the southeast corner of the
house.
/ ll3 2 3M I!) P.lQ score
The lot is located on the northwest corner of the intersection of 80th Ave W and W
184t" St SW (Figure 1). Residential lots border the north and west side c eth r � '�"��"��1' `�� .A a 0
TIL 125�7'/,IJHDO
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May 17, 2012
HWA Project No. 2012-000-21 Task 8
property. A steep slope area is located along the eastern property line. The ground surface
slopes eastward down toward 80th Avenue West at about 65% grade, but is locally steepened
where an existing terraced rockery exists , as shown in Figure 2, Site and Exploration Plan , as
well as Figure 3, Cross Sections A -A' and B -B'. The top of the slope is at about El. 332 feet
which is about 14 feet above the toe of the slope along 80th Ave W (El. 318 feet). There are
currently no visible signs of previous slope instability, or evidence of slope creep that might be
inferred from trees with bent trunks. Slope vegetation consists mainly of ivy with several large
coniferous trees. No slope vegetation that is typically indicative of seepage or very moist
conditions was noted. Three rockeries extend along the south and east side of the property
ranging in height from 2 to 6 feet tall creating a terraced hill slope as shown in Figure 3. No
apparent evidence of instability of the rockery was observed and only minor loss of material
from between the rocks was visible during the site visit.
The soil conditions at the location of the proposed deck expansion and new fence location were
explored by means of two hand auger borings, one 6 feet east of the house at the extend of the
proposed deck expansion and one at the top of the existing rockery. It should be noted that the
soil and ground water conditions described are only for the specific dates and locations reported
and, therefore, are not necessarily representative of other locations and times. It is anticipated
that water conditions will vary depending on seasonal precipitation, local subsurface conditions
and other factors.
SUBSURFACE CONDITIONS
According to the geologic map by Minard, J.P (1983), "Geologic Map of the Edmonds East and
Part of the Edmonds West Quadrangles ", the slope consists of advance outwash comprising
mostly clean, pebbly, sand with fine-grained sand and silt common in the lower part of the unit.
Glacial till is mapped at the western end of the property but was not encountered in our
explorations. Undisturbed advance outwash is typically dense to very dense. Slopes in glacial
outwash, typically slough to the angle of repose of the sand of around 300 to 330. When slope
instability occurs in glacial outwash, it is mainly confined to loose surficial layers, but deep-
seated slides can occur near the contact with less permeable glacial silts and clay near the base of
the deposit. Soil conditions are shown in Figures 5 and 6 along with a legend to terms used on
the hand borings in Figure 4.
CONCLUSIONS
Critical Areas
Construction of the fence and deck are considered an alteration within an erosion and landslide
hazard buffer area by the ECDC. In accordance with ECDC Section 23.80.060, alterations of
geologically hazardous areas or associated buffers may only occur for activities that.
1. Will not increase the threat of the geological hazard to adjacent properties beyond
Geotechnical Assessment Report 2 HWA GeoSciences Inc.
May 17, 2012
HWA Project No. 2012-000-21 Task 8
predevelopment conditions;
2. Will not adversely impact other critical areas;
3. Are designed so that the hazard to the project is eliminated or mitigated to a level equal to
or less than predevelopment conditions; and
4. Are certified as safe as designed and under anticipated conditions by a qualified engineer
or geologist, licensed in the state of Washington.
In addition, in accordance with ECDC Section 23.80.070.A.2, alterations of an erosion hazard or
landslide hazard area and/or buffer may only occur for activities for which a hazards analysis is
submitted and certifies that:
a. The development will not increase surface water discharge or sedimentation to
adjacent properties beyond predevelopment conditions;
b. The development will not decrease slope stability on adjacent properties; and
c. Such alterations will not adversely impact other critical areas;
The geologic map and our explorations indicate that the project area is underlain by advance
outwash. These soils consist of dense, granular, well drained, sand that are typically not subject
to global or deep rotational failure. In addition, the present site development plans do not
include any modification of the steep slope portion of the property and will not impair local
stability to any significant degree. Based on our understanding of the proposed work, as stated in
the previous project understanding section, it is our opinion that extending the deck up to 6 feet
east and constructing the fence will have any adverse effects on the existing slope on the east
side of your property as long as the following conditions are met during construction:.
® All of the new deck foundations should be founded on dense native soils consisting of
gray to grayish brown well graded sand with gravel anticipated at a minimum of
approximately 2.5 feet deep at the location of the deck. The actual depth to unweathered
native outwash may vary and footing lengths be adjusted accordingly.
The fence should be constructed with a 2 foot set back from the back of the highest rock
of the rockery in order to prevent disturbance of the soils immediately behind the
rockery.
In our opinion the most significant risk posed by development in this portion of the site is likely
a temporary increased potential for erosion during construction. This potential hazard will need
to be mitigated by post construction regrading and replacement of the grass surface covering, or
with replacement of native plants sufficient to prevent soil erosion. We believe that the
construction of the fence and the deck will not adversely affect the adjacent slope or any adjacent
Geotechnical Assessment Report 3 HWA GeoSciences Inc.
May 17, 2012
HWA Project No. 2012-000-21 Task 8
critical areas assuming the following conditions are taken during construction.
Best Management Practices (BMP'S) including limiting activity during wet weather, and
proper disposal or recompaction of surface soils materials that has been disturbed during
construction must be followed.
If these steps are followed then we conclude that the proposed improvements will not impair
local stability to any significant degree and should be permitted as allowed under the provisions
specified in ECDC Sections 23.80.060 and 23.80.070.A.2
CONDITIONS AND LIMITATIONS
We have prepared this letter report for use by Mike Lawyer and his designated agents for use in
permitting the construction of a new fence and deck expansion along the eastern side of his
existing single family residence. Experience has shown that soil and ground water conditions
can vary significantly over small distances. Inconsistent conditions can occur between
explorations and may not be detected by a geotechnical study of this nature. If, during future site
operations, subsurface conditions are encountered which vary appreciably from those described
herein, HWA should be notified for review of the recommendations of this letter report, and
revision of such if necessary.
The scope of work did not include environmental assessments or evaluations regarding the
presence or absence of wetlands or hazardous substances in the soil, surface water, or ground
water at this site. HWA does not practice or consult in the field of safety engineering, and
construction safety considerations are the responsibility of the Contractor or property owner.
®-®
Geotechnical Assessment Report 4 HWA GeoSciences Inc.
May 17, 2012
HWA Project No. 2012-000-21 Task 8
We appreciate the opportunity to be of service. If you have any questions or concerns, please do
not hesitate to contact us.
Sincerely,
HWA GE®SCIENCEs INC.
Daniel Coltrane, L.G.
Geologist
AttwbmPnts-
Steven E. Greene, L.G., L.E.G.
Senior Engineering Geologist
Figure 1
Site Vicinity snap
Figure 2
Site and Exploration Plan
Figure 3
Cross section A -A' and B -B'
Figure 4
Legend of Terms and Symbols Used on Exploration Logs
Figure 5
Log of Handhole HH -1
Figure 6
Log of Handhole HH -2
Geotechnical Assessment Report 5 HWA GeoSciences Inc.
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RELATIVE DENSITY OR CONSISTENCY VERSUS SPT N -VALUE
COHESIONLESS SOILS
COHESIVE SOILS
Boulders
Gravel and
Cobbles
3 in to 12 in
GW
Approximate
Density
N (blows/ft)
Approximate
Consistency
N (blows/ft)
Undrained Shear
Grained
Gravelly Soils
Relative Density(%)
No. 10 (2.0 mm) to No. 40 (0.42 mm)
Fine sand
Strength (psf)
Very Loose
0 to 4
0 - 15
Very Soft
0 to 2
<250
Loose
4 to 10
15 - 35
Soft
2 to 4
250 - 500
Medium Dense
10 to 30
35 - 65
Medium Stiff
4 to 8
500 - 1000
Dense
30 to 50
65 - 85
Stiff
8 to 15
1000 - 2000
Very Dense
over 50
65 - 100
Very Stiff
15 to 30
2000 - 4000
Sand and
Clean Sand
Hard
Iover 30
>4000
USCS SOIL CLASSIFICATION SYSTEM
MAJOR DIVISIONS
GROUP DESCRIPTIONS
Boulders
Gravel and
Cobbles
3 in to 12 in
GW
Well -graded GRAVEL
Coarse
3 in to 3/4 in
Clean Gravel
a
Sand
No. 4 (4.5 mm) to No. 200 (0.074 mm)
Grained
Gravelly Soils
(little or no fines)
No. 10 (2.0 mm) to No. 40 (0.42 mm)
Fine sand
No. 40 (0.42 mm) to No. 200 (0.074 mm)
Silt and Clay
Smaller than No. 200 (0.074mm)
MR
o Q
GP
Poorly -graded GRAVEL
Soils
More than
Approx. Compressive Strength (tsf)
SG
Specific Gravity
TC
50% of Coarse
Gravel with
o
GM
Silty GRAVEL
UC
Fraction Retained
Fines (appreciable
on No. 4 Sieve
amount of fines)
GC
Clayey GRAVEL
Sand and
Clean Sand
SW
Well -graded SAND
Sandy Soils
(little or no fines)
More than
SP
Poorly -graded SAND
50% Retained
50% or More
on No.
of Coarse
Sand with
SM
Silty SAND
200 Sieve
Fines (appreciable
Fraction Passing
Size
amount of fines)
SC
Clayey SAND
No. 4 Sieve
ML
SILT
Fine
Silt
Liquid Limit
Grained
and
CL
Lean CLAY
Soils
Less than 50%
Clay
_
—
OL
Organic SILT/Organic CLAY
MH
Elastic SILT
Silt
50% or More
Liquid Limit
Passing
and
50% or More
CH
Fat CLAY
Clay
No. 200 Sieve
Size
OH
Organic SILT/Organic CLAY
Highly Organic Soils
PT
PEAT
COMPONENT DEFINITIONS
COMPONENT
SIZE RANGE
Boulders
Larger than 12 in
Cobbles
3 in to 12 in
Gravel
3 in to No 4 (4.5mm)
Coarse gravel
3 in to 3/4 in
Fine gravel
3/4 in to No 4 (4.5mm)
Sand
No. 4 (4.5 mm) to No. 200 (0.074 mm)
Coarse sand
No. 4 (4.5 mm) to No. 10 (2.0 mm)
Medium sand
No. 10 (2.0 mm) to No. 40 (0.42 mm)
Fine sand
No. 40 (0.42 mm) to No. 200 (0.074 mm)
Silt and Clay
Smaller than No. 200 (0.074mm)
GROUNDWATER SYMBOLS
SZ Groundwater Level (measured at
time of drilling)
Groundwater Level (measured in well or
open hole after water level stabilized)
COMPONENT PROPORTIONS
PROPORTION RANGE
TEST SYMBOLS
%F
Percent Fines
AL
Atterberg Limits: PL = Plastic Limit
IShelby
LL = Liquid Limit
CBR
California Bearing Ratio
CN
Consolidation
DD
Dry Density (pcf)
DS
Direct Shear
GS
Grain Size Distribution
K
Permeability
MD
Moisture/Density Relationship (Proctor)
MR
Resilient Modulus
PID
Photoionization Device Reading
PP
Pocket Penetrometer
Approx. Compressive Strength (tsf)
SG
Specific Gravity
TC
Triaxial Compression
TV
Torvane
Approx. Shear Strength (tsf)
UC
Unconfined Compression
GROUNDWATER SYMBOLS
SZ Groundwater Level (measured at
time of drilling)
Groundwater Level (measured in well or
open hole after water level stabilized)
COMPONENT PROPORTIONS
PROPORTION RANGE
SAMPLE TYPE SYMBOLS
®2.0"
OD Split Spoon (SPT)
5-12%
(140 lb, hammer with 30 in. drop)
IShelby
Tube
30-50%
3-1/4" OD Split Spoon with Brass Rings
OSmall
Bag Sample
Large Bag (Bulk) Sample
®
Core Run
Non-standard Penetration Test
(3.0" OD split spoon)
GROUNDWATER SYMBOLS
SZ Groundwater Level (measured at
time of drilling)
Groundwater Level (measured in well or
open hole after water level stabilized)
COMPONENT PROPORTIONS
PROPORTION RANGE
DESCRIPTIVE TERMS
< 5%
Clean
5-12%
Slightly (Clayey, Silty, Sandy)
12-30%
Clayey, Silty, Sandy, Gravelly
30-50%
Very (Clayey, Silty, Sandy, Gravelly)
Components are arranged in order of increasing quantities.
NOTES: Soil classifications presented on exploration logs are based on visual and laboratory observation.
Soil descriptions are presented in the following general order: MOISTURE CONTENT
Density/consistency, color, modifier (if any) GROUP NAME, additions to group name (if any), moisture DRY Absence of moisture, dusty,
content. Proportion, gradation, and angularity of constituents, additional comments, dry to the touch.
(GEOLOGIC INTERPRETATION) MOIST Damp but no visible water.
Please refer to the discussion in the report text as well as the exploration logs for a more WET Visible free water, usually
complete description of subsurface conditions. soil is below water table.
Geotechnical Assessment Report LEGEND OF TERMS AND
Lawyer Residence SYMBOLS USED ON
HMGEOSCUNCESINC 8001 184th St SW EXPLORATION LOGS
Edmonds WA
PROJECT NO.: 2012-000-TO08 FIGURE: 4
LEGEND 2012-000-T008.GPJ 5/17/12
DRILLING COMPANY: HWA Geosciences Inc. DATE STARTED: 5/8/2012
DRILLING METHOD: Hand Bucket Auger DATE COMPLETED: 5/8/2012
SAMPLING METHOD: None LOGGED BY: D. Coltrane
LOCATION: See Figure 2
o S U) DESCRIPTION
W
U
0
[TOPSOIL]
Z
W
~
2 -inch thick dark brown silty SAND topsoil with grass at
surface.
°
SW
[WEATHERED ADVANCE OUTWASH]
z
Z
O c
H
Loose to medium dense, light olive gray to brown, slightly silty
J J
��Q
Q'
gravelly fine to coarse SAND, moist.
°
;°
n
Z o
- ADVANCE OUTWASH
— — — — — — —
-----— — — — — — — —
SWT
W
v¢i v¢i
0- .n
Dense to very dense, olive gray to gray, gravelly fine to
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coarse SAND, moist. Trace silt.
Hand hole was terminated at 2.5 feet below ground surface.
No ground water seepage was observed during the
exploration.
5 -
NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
0 20 40 60 80
Water Content (%)
Plastic Limit Liquid Limit
Natural Water Content
Geotechnical Assessment Report HANDHOLE
BOA Lawyer Residence HH -1
S ®, S �, 8001 184th St SW PAGE: 1 of 1
HMGEOj�J Edmonds, WA
PROJECT NO.: 2012-000-TO08 FIGURE: 5
HANDHOL-DSM 2012-000-T008.GPJ 5/17/12
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NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
0 20 40 60 80
Water Content (%)
Plastic Limit Liquid Limit
Natural Water Content
Geotechnical Assessment Report HANDHOLE
BOA Lawyer Residence HH -1
S ®, S �, 8001 184th St SW PAGE: 1 of 1
HMGEOj�J Edmonds, WA
PROJECT NO.: 2012-000-TO08 FIGURE: 5
HANDHOL-DSM 2012-000-T008.GPJ 5/17/12
DRILLING COMPANY: HWA Geosciences Inc.
DATE STARTED: 5/8/2012
DRILLING METHOD: Hand Bucket Auger
DATE COMPLETED: 5/8/2012
SAMPLING METHOD:
LOGGED BY: D. Coltrane
LOCATION: See Figure 2
of
W
W
U
U
D
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I— Z
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Q Q
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CL s
N
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0
X. SW [WEATHERED ADVANCE OUTWASH]
Loose to medium dense, olive brown, slightly silty gravelly fine
to coarse SAND, moist.
Becomes medium dense.
e' SW [ADVANCE OUTWASH]
Dense to very dense, gray, gravelly fine to coarse SAND,
moist. Trace silt.
Hand hole was terminated at 1.8 feet below ground surface.
No ground water seepage was observed during the
exploration.
5
0 20 40 60 80 100
Water Content (%)
Plastic Limit Liquid Limit
NOTE:
This log of subsurface conditions applies only at the specified location and on the
date indicated
Natural Water Content
and therefore may not necessarily be indicative of other times and/or locations.
Geotechnical Assessment Report HANDHOLE
awnLawyer Residence HH -2
HMIGEOS ®'j� C 8001 184th St SW PAGE: 1 of 1
Edmonds, WA
PROJECT NO.: 2012-000-TO08 FIGURE: 6
HANDHOL-DSM 2012-000-T008.GPJ 5/17/12