CANOD.pdfCity of Edmonds
Critical Area Notice of Decision
Applicant: / Property Owner:
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Critical Area File #: f�Ze l S-00 %S Permit Number: 19L.o z 01 S / 0 �
Site Location: _co i _ 'arel Number: os�3 [oao i 3q +-
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Project Description: .� ` /
❑ Conditional Waiver. No critical area report is required for the project described above.
1. 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.
❑ 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 23.40.1,60 and
the provisions of the City of Edmonds critical area regulations. See attached findings of
noncompliance.
ER -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).
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Reviewer
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Signatur
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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
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S °' 18 2015
"""NO OF.PANIMENT
0194' OF EDMONDS
M.S.C.E., M.B.A. Geotechnical / Civil Engineer
September 15, 2015
City of Edmonds
c/o Eugene Bolin
eugenebolin@gmail.com
Subject: Geotechnical Response
City of Edmonds Review Comments dated September 14, 2015
Bolin Property at 7330 172nd Street S.W.
This engineering report presents geotechnical responses to the City of Edmonds
review comments in a letter dated September 14, 2015.
REFERENCES:
Geotechnical report by D. Bruce, P.E. dated July 27, with August 3, 2015
addendum designs
* Large drawings of overall site plan with replacement wall alignment
and height indicated. Site Plan certified September 15, 2015.
Representative site photographs
BACKGROUND:
As stated in the July 27 and August 3, 2015 report and designs, the existing
timber wall that provided landscaping and erosion stabilization, had failed. This failure
was not due to any geologic hazard. This failure was not due to any excessive
drainage problems, nor any seismic or buffer issues.
This failure was entirely due to "historic mediocre" construction quality of the
timber walls. Please see July 27, 2015 report.
This engineer was contacted to provide practical geotechnical engineering
analysis and designs in order to verify that proper wall construction was achieved
between both adjoining residences (Bolin, at 7330 and Donaldson at 7312 172nd Street
S.W.) to replace the existing failing wall for erosion control purposes.
City of Edmonds, c/o Eugene Bolin
Re: 7330 172nd Street, Edmonds
September 15, 2015
Page 2
This engineer provided on-site inspections and design criteria for the
replacement wall, constructed to date. See photos of an excellent keystone block wall,
with appropriate drainage zone.
The respective homeowners desired to obtain a City of Edmonds permit, in
addition to this engineer's existing and ongoing services.
The City of Edmonds reviewed the submitted reports and designs to date, and
issued a plan review comment dated September 14, 2015.
This report responds to those comments.
CITY OF EDMONDS REVIEW COMMENTS — GEOTECHNICAL RESPONSES:
A. Scope of Work: Please clarify the scope of work and show that work.
Please review July 27 and August 3, 2015 geotechnical reports.
Short Version: The preexisting timber wall has failed. This scope of work is to
replace that failed timber wall with a much better geotechnically-engineered
keystone block wall, with geogrid matrix where required by the geotechnical
engineer.
This "scope of work" is necessary in order to maintain proper erosion control
between the agreeing property owners. See expanded site plan that clearly
indicates the wall alignment (that replaces a failed timber wall) as well as the height.
See engineering drawings to verify the cross-section and geotechnical components
of the wall.
B. Geotechnical Report..., "must address ECDC criteria for development in or near
geologic hazards,"
This replacement wall project does not involve any geologic hazards.
Nevertheless, this engineer will respond to the relevant sections of the ECDC
sections.
Report Requirements:
Preparation by qualified professional: I, Dennis M. Bruce, P.E., have been
performing geotechnical engineering in the Puget Sound area for over 40 years.
I have previously taught Civil Engineering and Geotechnical Engineering at the
University of Washington. My projects include the entire spectrum of small home
owner issues to multi-million dollar plat designs. I am fully qualified to perform
the geotechnical work for this minor erosion control wall replacement project.
City of Edmonds, c/o Eugene Bolin
Re: 7330 172nd Street, Edmonds
September 15, 2015
Page 3
1) None of the project area involves a critical area or hazard. Slopes
involved in the replacement wall project do exceed 40%, however, the
geotechnical investigation has verified dense, native subgrade soils with no
potential for liquefaction or slides.
Without the replacement wall, excessive erosional sloughing will result.
Hence, the replacement wall is geotechnically necessary.
2) There are no geologic hazard areas within 200 feet of this replacement wall
area.
Hazards Assessment:
1) Site and construction plans, show:
a) The type and extent of geologic hazard areas: None.
b) Proposed development: Yes. This project includes constructing a
replacement wall to provide necessary erosional stabilization.
c) Topography: See Site Plan.
d) Clearing limits: No significant additional clearing limits will be required.
Obviously, the area of the sloughing and leaning timber wall must be
properly excavated and prepared for the new stabilizing wall.
2) Geologic Characteristic:
a) Description of Subsurface Soils: The subsurface soils consist of dense
glacially consolidated till, which provide a bearing capacity of 4,000 p.s.f.
These subsurface soils are geotechnicall,y approved for the replacement
wall.
b) Field Investigations: This engineer provided on-site investigations during
the excavation and preparation of the wall constructed to -date.
3) Analysis of Proposal: There are no hazards to analyze. The existing slope
between the properties does require an erosion stabilization wall. Previous
timber wall is failing. This engineer proposes to replace the failed timber wall
with a proper keystone block stabilization wall, suWect to this engineer's
designs and on-site inspections.
City of Edmonds, c/o Eugene Bolin
Re: 7330 172nd Street, Edmonds
September 15, 2015
Page 4
4) Mil nimum Buffer and Building Setback. There are no requirements for buffer
or setback. See Site Plan. This engineer approves of the location, alignment
and height of the replacement wall, sect to on-site inspections by this
engineer. Inspection reports and a final certified report upon successful
completion will be provided to the City of Edmonds.
D. Incorporation of Previous Stud This engineer did provide additional
investigation and work on the site for the previous owner. This engineer did
prepare a report in 2006 for the previous owner (Sylvester).
This engineer did provide on-site geotechnical inspections in conjunction with the
Sylvester addition project.
This engineer is extremely familiar with all subsurface conditions, slopes and
drainage mitigations that are a normal, inherent aspect of a proper replacement
wall.
E. Mitigation of Long -Term Impacts: The purpose of the replacement wall is to
mitigate long-term impacts. Those long-term impacts include erosional sloughing
without the replacement wall. Q.E.D.
F. TITO 0 Is
This engineer declares that:
1) This replacement wall project will not increase the threat of the geologic
hazard (there is none) to adjacent properties beyond the pre -development
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.
4) Are certified as safe and designed under anticipated conditions by a qualified
engineer or geologist, licensed in the State of Washington.
This engineer certifies and declares that:
1) This development (replacement wall) will not increase surface water
discharge or sedimentation to adjacent properties beyond pre -development
conditions.
2) This development (replacement wall) will not decrease slope stability on
adjacent properties.
City of Edmonds, c/o Eugene Bolin
Re: 7330 172nd Street, Edmonds
September 15, 2015
Page 5
3) Such alterations (replacement wall) will not adversely impact other critical
areas.
Desion Standards: This engineer declares:
1) The proposed development shall not decrease the factor of safety for
landslide occurrence below the limits of 1.5 for static conditions, and 1.2 for
dynamic conditions.
2) The structures and improvements shall be clustered to avoid geologically
hazardous areas and other critical areas: This site conditions no
geological hazardous areas. Nevertheless, the replacement wall could be
bureaucratically considered to be "clustered" along the alignment shown.
3) Structures and improvements shall minimize alterations to the natural
contour of the slope: This replacement wall is specifically designed to
minimize alterations to the natural slope. Without the wall, the natural
contour of the slope will erode down into Mr. Bolin's driveway.
4) Structures and improvements shall be located to preserve the most critical
portion of the site as natural landforms and vegetation. This replacement
wall provides proper erosion control allowing for maintenance of the
vegetation on the slope face.
5) Proposed development shall not result in greater risk or a need for
increased buffers on neighbor's property. This replacement wall does not
result in a greater risk.
6) The use of retaining walls that allow for the maintenance of the existing
natural slope is preferred over graded artificial slopes. This engineer
agrees. The entire purpose of this replacement wall is to allow proper
maintenance of the existing slope area.
7) Development shall be designed to minimize impervious lot coverage.
Agreed.
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This replacement wall is designed in order to maximize the vegetation on the
slope face.
Seasonal Restriction:
It is essential that the City of Edmonds promptly issues a permit in order for the
necessary stabilization wall work to resume.
This engineer will provide on-site inspections and advise owner and contractor
if any work must be temporarily ceased during periods of heavy rains.
Because this engineer will provide on-site inspections, no seasonal restriction
for the remainder of the wall work is necessary.
City of Edmonds, c/o Eugene Bolin
Re: 7330 172nd Street, Edmonds
September 15, 2015
Page 6
m
1=110=_ _
On-site sewage disposals: Not applicable to this simple replacement wall
project.
Section 23.40.090 Critical Areas Reports:
a) Preparation by a qualified professional: Yes.
b) Independent review of critical area reports: Not necessary. This is a
simple replacement wall project.
c) Best available science: Yes.
d) Minimum report contents:
1) This engineer understands that Mr. Bolin and Ms. Donaldson have both
submitted project applications for the City of Edmonds. Thus, it seems a
simple matter for the City of Edmonds to grant both of the adjoining and
agreeable homeowners to "get on with it".
2) A) Site Plan: Yes, numerous copies furnished.
B) Description of storm water management: The storm water
management is inherent in the keystone block with the drainage zone and
a natural "weeping effect" to disburse any ground water behind the wall.
C) Dates, names and qualifications of persons preparing report: Yes.
D) Identification and Characterization of all critical areas: None.
Wetlands: None. Water bodies: None. Shorelines: None. Buffers
adjacent to the proposed project area: None required.
+�
'Description of efforts made to apply mifigationsgggencing This is a
replacement wall.
0 (6) This engineer cannot understand the syntax or grammar of this sentence.
TREE ISSUE — GEOTECHNICAL STABILITY:
Currently, a tree exists at the southeastern portion of the Bolin property (which is
adjacent the southwestern portion of the Donaldson property).
The proposed wall replacement project will necessitate the removal of this tree.
City of Edmonds, c/o Eugene Bolin
Re: 7330 172nd Street, Edmonds
September 15, 2015
Page 7
This engineer has determined that the tree roots are a contributing factor in the
failing of the timber wall (previously discussed).
Additionally, the soil adjacent and under the tree has been severely undermined
by the burrowing activity of "mountain beavers".
It is geotechnically required that this tree be removed. Removal of this tree will
not adversely impact the overall slope stability.
Removal of this tree in conjunction with the replacement keystone block wall will
improve overall slope stability.
This engineer understands that adjacent property owners will re -vegetate and
plant landscaping, shrubbery and groundcover to assist in long-term erosion control.
SUMMARY:
o This project is a simple replacement wall for the failing timber wall.
Proper geotechnical engineering report has been done with proper design
sketches.
This engineer has provided on-site inspections and certifies that the wall
constructed to date is geotechnically stable.
• This report responds to the City of Edmonds requirements for the ECDC.
It is essential that the City of Edmonds promptly issue a permit so that the
necessary stabilization work may resume.
This engineer must continue to provide on-site inspections and will provide
periodic reports and a final report to the City of Edmonds.
If there are any questions, do not hesitate to call.
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tennis M. Bruce, P.E.
geotechnical / Civil Engineer
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Geotechnical / Civil Engineer
Eugene Bolin
Jennifer Donaldson
7330 172nd St. S.W. ( and 7312 172nd St. S.W.)
July 7, 2 15
.ibinr. ry 1
This engineering report presents the results of a geotechnical evaluation of the properties
( above ) in relation to the failed timber walls on the slope above the easement zone . See
survey map. The adjacent properties have a common interest in proper slope stability.
Additionally, the lower property (Bolin) needs dependable access for the driveway. See
photos.
References: - Photo sheets
-Geotechnical evaluation and inspection reports by D. Bruce, P.E. in 2006 for the 7312
172nd St. S.W. property ( then owner : Sylvester)
Background: This engineer performed geotechnical evaluation, recommendations, and follow
up inspections for the 2006 addition project for 7312. At that time —a design for replacing the
failing timber walls (on the slope) was made. No modifications or efforts to replace those
walls were undertaken until July, 2015. Current work includes: Retaining this engineer to
evaluate slope stability for BOTH properties, make recommendation ( following up the 2006
designs), and daily site inspections of the work.
Evaluation: The lower timber wall had failed. The upper wall is in "mediocre" condition.
Both walls should be replaced. The optimum replacement configuration involves a single
Keystone block wall (established within the easement zone ) that is based in dense native soil
per this engineer's inspections) and compacted structural fill. The upper portions of the wall
will require a geogrid element of approximately 5.5 ft. width. This engineer to provide design
sketches —and, more importantly, work with the owner on a daily basis to verify conditions
and performance.
SOILS - FOUNDATIONS - SITE DEVELOPMENT 9 INSPECTION * DRAINAGE * DESIGN& PERMIT 9 LEGAL
P.O. Box 55502 - Shoreline, WA 98155 - (206) 546-9217
Both property owners have entrusted this engineer to look out for both interests and the
overall stability of the slope. Both owners are in agreement with the recommendation herein —
subject to proper performance and Final Engineering Certification.
Inspections: Due to the failing conditions and the essential requirement to complete all slope
work prior to the fall rains —Mr. Bolin began work to "clean up" the failed timber wall and
evaluate the slope. This engineer inspected all work performed to date and verifies the
excellent quality of wall work and the stability of the slope. Ins actions continue*
Rear wall issues: See photo sheet. The rear ( southerly) portion of the driveway contains a
more significant slope and obvious failed timber walls. Replacement is required.
This wall replacement MAY be incorporated into a larger overall new garage project. This
engineer requires wall replacement (whether the garage project comes to be).
Previous foundation work on the adjacent ( upslope ) patio addition project in 2006
( inspected by this engineer) verified stable conditions on the Donaldson property.
Summary:
-The pre-existing timber walls need replacement in 2006. The lower wall has failed.
-The slope is stable, subject to a new stabilizing wall being properly installed.
-The current work on the Keystone block wall is geotechnically approved, subject to continued
inspections and design modification, as required by this engineer.
-Recommend that the City of Edmonds issue a permit for this necessary replacement work,
subject to continued inspections by D. Bruce, P.E.
t
Dennis M. Bruce, P.E.
Geotechnical / Civil Engineer
7330 172"d St. S.W. Failed timber wall (onto Bolin drive)
Stable slope on 7312 property ( Donaldson ).
2006 patio addition supported on deep pier foundations.
Stable slope ( on Donaldson prop.) Bolin garage at right.
Setting stable Keystone blocks ( former failed timber wall)
Note stable soil cut, former gravel drainage zone. Good.
7330 172nd St. S.W. viewing northerly.
Lower failed timber wall being replaced per Geotech. Engr
Donaldson residence in background. Wall failed. Base blocks well set on compacted crushed rock.
A proper stabilizing wall is required.
Drainage zone, block linkage, batter properly done.
Geotech. inspections verified slope stability during work
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