REVIEWED PLN RESUB2 BLD2023-1391+GEO REPORT+7.17.2024_4.43.56_PM+4385057------- - - - - - -
Reviewed by
City of Edmonds ;
Planning Division ; CRITICAL AREAS REPORT
GEOLOGICALLY HAZARDOUS AREAS
MATHAY-BALLINGER PARK IMPROVEMENTS
ZGA Project No. 2814.00
3 June 2024
Prepared for:
City of Edmonds
Prepared by:
Z*ipperGeo
Geoprofessional Consultants
ZipperGeo
Geoprofessional Consultants
ZGA Project No. 2814.00
3 June 2024
City of Edmonds
Parks, Recreation, and Human Services
700 Main Street
Edmonds, Washington 98020
Attention: Mr. Kyle Woods, Planner & Capital Projects Manager
Subject: Critical Areas Report
Geologically Hazardous Areas
Mathay-Ballinger Park Improvements
24105 78th Place West
Edmonds, Washington
City Permit No. BLD2023-1391
Dear Mr. Woods:
In accordance with your request and written authorization, Zipper Geo Associates, LLC (ZGA) has
completed this Critical Areas Report on behalf of the City of Edmonds (the City) for the above -referenced
project. This report has been prepared in general accordance with Chapter 23.40.090 of the Edmonds
Community Development Code (ECDC), our proposal number P24153, dated 29 April 2024, and our
Professional Services Agreement with the City, dated 1 May 2024. This evaluation was limited to
Geologically Hazardous Areas as defined in ECDC 23.80.020.
We appreciate the opportunity to be of service to you on this project. If you have questions concerning this
report, or if we may be of further service, please contact the undersigned.
Respectfully Submitted,
Zipper Geo Associates, LLC
ogw
Signed 6/3/24
355
v JEFFREY S. TINKLEPAUGH
Jeffrey S. Tinklepaugh, LG, LEG
Senior Engineering Geologist
James P. Georgis, LG, LEG
Principal Engineering Geologist
19019 36th Ave West, Suite E I Lynnwood, WA 98036 1 Phone: 425.582.9928 1 zippergeo.com
ZipperGeo
Geoprofessional Consultants
TABLE OF CONTENTS
Page
INTRODUCTION........................................................................................................................................ 1
Purpose...................................................................................................................................................1
SiteLocation............................................................................................................................................1
ProjectUnderstanding.............................................................................................................................1
PreviousInvestigations by Others............................................................................................................2
PHYSICAL SETTING................................................................................................................................. 2
SurfaceConditions...................................................................................................................................2
GeologicSetting.......................................................................................................................................3
SubsurfaceConditions.............................................................................................................................3
GroundwaterConditions.........................................................................................................................3
GEOLOGICALLY HAZARDOUS AREAS.................................................................................................. 4
ErosionHazard Areas...............................................................................................................................4
LandslideHazard Areas............................................................................................................................5
SeismicHazard Areas...............................................................................................................................6
MitigationSequencing.............................................................................................................................7
CONCLUSIONS AND RECOMMENDATIONS.......................................................................................... 9
RELIANCE AND LIMITATIONS................................................................................................................. 9
REFERENCES........................................................................................................................................... 9
Appendix A — Figures
Figure 1: Vicinity Map
Figure 2: Site and Exploration Plan
Appendix B — Landau Associates Soil Classification Procedures, Test Pit Logs, and Grain Size Testing
Results
19019 36th Ave West, Suite E I Lynnwood, WA 98036 1 Phone: 425.582.9928 1 zippergeo.com
CRITICAL AREAS REPORT
GEOLOGICALLY HAZARDOUS AREAS
MATHAY-BALLINGER PARK IMPROVEMENTS
24105 78T" PLACE WEST
EDMONDS, WASHINGTON
3 June 2024
INTRODUCTION
Purpose
This report has been prepared by Zipper Geo Associates, LLC (ZGA) on behalf of the City of Edmonds (the
City) in support of planned improvements to Mathay-Ballinger Park. This report has been prepared in
general accordance with Chapter 23.40.090 of the Edmonds Community Development Code (ECDC), our
proposal number P24153, dated 29 April 2024, and our Professional Services Agreement with the City,
dated 1 May 2024. Our scope of services was limited to an evaluation of the presence/absence of
Geologically Hazardous Areas as defined in ECDC 23.80 within the project area and recommendations for
mitigating measures to reduce impacts to such critical areas, if necessary.
Site Location
Mathay-Bal linger Park is located at 24105 78th Place West, in Edmonds, Snohomish County, Washington
(the Site). The Site is adjoined to the north and west by the Old Everett Traction Co. Right of Way and to
the south and east by residential properties. The Site is accessed from the south from 78th Place West.
The Site is located just over 1,000 feet to the west of Lake Ballinger. The location of the Site is depicted
on Figure 1, Vicinity Map.
Project Understanding
ZGA was provided with a set of preliminary civil drawings for the Mathay-Ballinger Park Site
Improvements, prepared by CG Engineering, revision dated 10 April 2024. From a review of these plans,
we understand that the proposed site improvement will include:
• Asphalt resurfacing of the existing parking area at the north end of 78th Place West;
• Construction of new asphalt surfaces for additional parking spaces, walking paths, and
maintenance access roads connecting 78th Place West to an existing asphalt -paved trail (the
Interurban Trail) located to the north of the Site within the Old Seattle -Everett Traction Co. Right
of Way;
• Construction of a new single -stall restroom near the 78th Place West parking area;
• Construction of new concrete pads for benches, picnic tables, and a new play area;
• Minor regrading and fill placement; and
• Utility improvements including new stormwater infiltration galleries and associated catch basins
and below ground piping.
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Critical Areas Report
Geologically Hazardous Areas
Mathay-Bal linger Park Improvements
3 June 2024
ZipperGeo
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These improvements are generally depicted in Figure 2, Site and Exploration Plan.
Previous Investigations by Others
Our scope of services did not include a subsurface investigation. For the purposes of this report, we have
utilized geologic information from readily available, published resources, our field observations from a
site reconnaissance, and Site -specific subsurface data previously collected by Landau Associates. The
results of Landau Associates previous geotechnical investigations are summarized in the following
document:
• Summary of Geotechnical Engineering Services, Moth ay -Ballinger Park Project, Edmonds,
Washington, prepared by Landau Associates, dated 27 December 2023.
According to this report, on May 24, 2023, Landau Associates advanced four test pits (TP-1 through TP-4)
and completed one small-scale pilot infiltration test (PIT; PIT-1) at the Site, in the approximate locations
indicated on Figure 2, Site and Exploration Plan. Test pits were advanced to depths of approximately 9 to
10 % feet below ground surface (bgs). PIT-1 was completed at a depth of approximately 3 feet bgs and
was then extended to a depth of approximately 10 % feet bgs. Four soil samples (one from each test pit
and from PIT-1) were submitted for grain size distribution and moisture content analysis. Landau
Associates recorded their subsurface observations in test pit logs, which are enclosed in Appendix B. The
results of moisture content analyses are presented on the boring logs. The results of grain size analyses
are presented on a separate plot (Landau Figure 9), which is also enclosed in Appendix B.
PHYSICAL SETTING
Surface Conditions
According to a survey by Pacific Coast Surveys, the park area is generally level with an overall gentle slope
to the south and a total vertical relief of approximately 6 feet from elevation 328 feet above sea level (asl)
near the north end of the park area to 322 feet asl near the parking area to the south. The Site includes
portions of a steeper slope that adjoins the park to the north with a total vertical relief of approximately
6 to 10 feet with an asphalt -paved or gravel -surfaced trail located along the top of the slope. Slopes
generally do not exceed 15% within the park area except for in limited, localized areas (15% represents a
threshold slope within the ECDC for Erosion Hazard Areas). Slopes along the northern portion of the site,
adjoining the trail, generally do exceed 15%, and in the westerly half of the Site often exceed 40% (40%
represents a threshold slope within the ECDC for Landslide Hazard Areas).
We conducted a reconnaissance of the Site on 8 May 2024. The majority of the park area is surfaced with
grass. An asphalt parking area is located at the south end of the Site at the terminus of 781" Place
Southwest. An asphalt sport court is located to the east of the parking area. A wood chip surfaced play
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Geologically Hazardous Areas
Mathay-Bal linger Park Improvements
3 June 2024
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area is centrally located within the park. Numerous mature trees are scattered throughout the park. A
gravel access road is located at the north end of the park extending up the slope and connecting to the
paved portion of the Interurban Trail. Dense undergrowth consisting mainly of blackberries is located at
the northeasterly end of the park and along the slope below the trail. We did not observe visible evidence
of surface water, groundwater seepage, active erosion, or landsliding during our visit.
According to the Natural Resources Conservation Service (NRCS) Web Soil Survey database', shallow soils
at the Site belong to the Alderwood Series. Alderwood soils are generally described by the NRCS as
gravelly, sandy loam derived from glacial drift deposits. Alderwood soils are recognized by the ECDC as
prone to erosion when slopes exceed the 15% threshold.
Geologic Setting
Surficial geologic conditions for the Site are depicted on the Geologic Map of the Edmonds East and Part
of the Edmonds West Quadrangles, Washington (Minard,1983). The surficial geology of the Site is mapped
as Vashon Till (Qvt), which is generally classified as a poorly sorted (well graded), non -stratified mixture
of clay, silt, sand, pebbles, and cobbles with occasional boulders. Unweathered Vashon Till typically
exhibits an overall high density and low permeability, although layers or lenses of coarse grained sediment
may occur within the unit. Also mapped in the vicinity of the site is the Vashon Recessional Outwash (Qvr)
geologic unit, which is generally classified as stratified sand and gravel with minor silt and clay layers.
Vashon Recessional Outwash typically exhibits a low to medium density and high permeability, although
layers or lenses of fine-grained sediment may occur within the unit.
Subsurface Conditions
During test pit explorations, Landau Associates observed geologic conditions beneath the Site to depths
of up to 10 % feet. According to their report and boring logs, subsurface conditions at the Site generally
consist of 3 to 4 inches of topsoil over loose to medium dense or medium stiff, damp to moist, gray to
light brown, sand with varying amounts of silt, gravel and cobbles to silt with varying amounts of sand,
gravel, and cobbles. Landau Associates interpreted that these conditions were representative of the
Vashon Recessional Outwash geologic unit described by Minard. All test pits were terminated within the
Vashon Recessional Outwash unit.
Groundwater Conditions
Landau Associates reported that they did not observe groundwater within their field explorations. We
expect that shallow groundwater beneath the Site generally flows towards Lake Ballinger (to the east) at
a higher elevation than that of the water level within the lake. According to the City, the water level within
' https://websoilsurveV.nres.usda.gov/app/WebSoilSurveV.aspx
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Geologically Hazardous Areas
Mathay-Bal linger Park Improvements
3 June 2024
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Lake Ballinger is typically below 280 feet2 asl except in flood conditions. 280 feet in elevation is
approximately 40 feet below the lowest elevation at the Site. Therefore, the exact depth to groundwater
below the Site is unknown but is expected to be greater than 10%feet and less than 40 feet. Groundwater
levels should be expected to vary throughout the year depending on site use, precipitation rates, and local
geologic conditions, with the highest groundwater levels generally occurring during late winter and early
spring.
GEOLOGICALLY HAZARDOUS AREAS
ECDC 23.80.050(B) requires that a Critical Areas Report address geologically hazardous areas that are
within the project area and all geologically hazardous areas within 200 feet of the project area or that
have the potential to be affected by the proposal. Figure 2, Site and Exploration Plan, depicts the
approximate extent of geologically hazardous areas identified by this assessment within the scope of the
project's survey, provided by Pacific Coast Surveys. In addition to these areas, we reviewed portions of
the King County West 2021 LiDAR digital elevation model, reviewed geologic hazard inventories from the
Washington Geologic Information Portal (WGIP), and performed a site reconnaissance to assess the
potential presence of geologically hazardous areas beyond the survey area. Our extended review did not
identify geologically hazardous areas beyond the project survey bounds shown in Figure 2 that may
adversely affect or be adversely affected by the proposed park improvements.
Erosion Hazard Areas
Erosion Hazard Areas are defined in ECDC 23.80.020(A) as those areas identified by the U.S. Department
of Agriculture's Natural Resources Conservation Service as having a "moderate to severe," "severe," or
"very severe" rill and inter -rill erosion hazard. Erosion hazard areas are also those areas impacted by
shoreland and/or stream bank erosion. Within the city of Edmonds erosion hazard areas include:
1. Those areas of the city of Edmonds containing soils that may experience severe to very severe
erosion hazard. This group of soils includes, but is not limited to, the following when they occur
on slopes of 15 percent or greater:
a. Alderwood soils (15 to 25 percent slopes);
b. Alderwood/Everett series (25 to 70 percent slopes);
c. Everett series (15 to 25 percent slopes);
2. Coastal and stream erosion areas which are subject to the impacts from lateral erosion related to
moving water such as stream channel migration and shoreline retreat;
https://www.edmondswa.gov/government/departments/public works and utilities/stormwater utility system/1
ake ballinger water level
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Mathay-Bal linger Park Improvements
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3. Any area with slopes of 15 percent or greater and impermeable soils interbedded with granular
soils and springs or ground water seepage; and
4. Areas with significant visible evidence of ground water seepage, and which also include existing
landslide deposits regardless of slope.
Alderwood soils occur on the Site on slopes of 15% or greater. These areas therefore qualify as Erosion
Hazard Areas. The approximate extent of Erosion Hazard Areas at the Site is depicted in Figure 2, Site and
Exploration Plan. Planned Site improvements overlap with mapped Erosion Hazard Areas in the northern
portion of the Site, where the access road will approach the existing paved asphalt trail, and in one other
localized area to the south of the existing play area. Adverse effects of construction will be mitigated by
implementingthe temporary erosion control measures outlined in Sheets C2.1 and C2.2 of the preliminary
civil plan set. Permanent stormwater systems will be designed in accordance with the Stormwater
Management Manual for Western Washington (Washington State Department of Ecology, 2019) and
generally appear sufficient for the scope of site regrading and new impermeable surfaces. Permanent
erosion control will be accomplished by revegetation of affected areas with appropriate ground cover or
installation of erosion resistant surfacing. It is our opinion that conditions do not warrant a minimum
setback from identified erosion hazard areas.
Landslide Hazard Areas
Landslide Hazard Areas are defined in ECDC 23.80.020(B) as areas potentially subject to landslides based
on a combination of geologic, topographic, and hydrologic factors. They include areas susceptible because
of any combination of soil, slope (gradient), slope aspect, structure, hydrology, or other factors. Within
the city of Edmonds potential landslide hazard areas include:
1. Areas of ancient or historic failures in Edmonds which include all areas within the earth subsidence
and landslide hazard area as identified in the 1979 report of Robert Lowe Associates and amended
by the 1985 report of GeoEngineers, Inc., and further discussed in the 2007 report by Landau
Associates;
2. Coastal areas mapped as class u (unstable), uos (unstable old slides), and urs (unstable recent
slides) in the Department of Ecology Washington coastal atlas;
3. Areas designated as quaternary slumps, earthflows, mudflows, or landslides on maps published
by the United States Geological Survey or Washington State Department of Natural Resources;
4. Any slope of 40 percent or steeper that exceeds a vertical height of 10 feet over a 25-foot
horizontal run. Except for rockeries that have been engineered and approved by the engineer as
having been built according to the engineered design, all other modified slopes (including slopes
where there are breaks in slopes) meeting overall average steepness and height criteria should
be considered potential landslide hazard areas);
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3 June 2024
5. Any slope with all three of the following characteristics:
a. Slopes steeper than 15 percent;
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b. Hillsides intersecting geologic contacts with a relatively permeable sediment overlying a
relatively impermeable sediment; and
c. Springs or ground water seepage;
6. Any area potentially unstable as a result of rapid stream incision or stream bank erosion;
7. Any area located on an alluvial fan, presently subject to, or potentially subject to,
inundation by debris flow or deposition of stream -transported sediments; and
6. Any slopes that have been modified by past development activity that still meet the slope criteria.
The Site is not associated with nor in the vicinity of mapped landslide hazards per the Washington Geologic
Information Portal (WGIP) landslide hazard inventory3. However, portions of the slope at the
northwestern margin of the Site exceed 40% slope with a vertical height of over 10 feet and a horizontal
run of at least 25 feet. These areas therefore qualify as Landslide Hazard Areas. The approximate extent
of Landslide Hazard Areas at the Site is depicted in Figure 2, Site and Exploration Plan. Planned Site
improvements are located downslope from Landslide Hazard Areas where they will not impart a surcharge
load and are setback far enough from the toe of the slope that they are unlikely to reduce the lateral
support of said slope. The risk that construction of the proposed Site improvements will have an adverse
effect on the stability of nearby Landslide Hazard Areas is low. Additionally, proposed Site improvements
do not include continuously occupied structures within the likely runout area of a landslide originating
from the Landslide Hazard Areas identified in the vicinity. It is our opinion that conditions do not warrant
a minimum setback from identified landslide hazard areas. In our opinion, no mitigation appears
necessary.
Seismic Hazard Areas
Seismic Hazard Areas are defined in ECDC 23.80.020(C) as areas subject to severe risk of damage as a
result of earthquake -induced ground shaking, slope failure, settlement, soil liquefaction, lateral spreading,
or surface faulting. These areas are designated as having a "high" and "moderate to high" risk of
liquefaction as mapped on the Liquefaction Susceptibility Map of Snohomish County by the Washington
State Department of Natural Resources or areas located within landslide hazard areas.
3 Washington Geological Survey, 2023, Washington State Landslide Inventory Database-GIS data, June 2023:
Washington Geological Survey Digital Data Series 29, version 1.1.
https://fortress.wa.gov/dnr/geologydata/publications/data download/ger portal landslide database.zip
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Critical Areas Report
Geologically Hazardous Areas
Mathay-Bal linger Park Improvements
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The Site is not located within an area designated as having a "high" or "moderate to high" risk of
liquefaction. However, per ECDC 23.80.020(C), portions of the Site do qualify as Landslide Hazard Areas
and therefore also qualify as Seismic Hazard Areas. The approximate extent of Seismic Hazard areas at the
Site is depicted in Figure 2, Site and Exploration Plan. Planned Site improvements do not overlap with
mapped Seismic Hazard Areas and the risk that construction of the proposed Site improvements will have
an adverse effect on the stability of nearby Seismic Hazard Areas is low. In our opinion, no mitigation
appears necessary.
Mitigation Sequencing
Per ECDC 23.40.120(A), applicants shall demonstrate that all reasonable efforts have been examined with
the intent to avoid and minimize impacts to critical areas. Geologically hazardous areas in the vicinity of
the proposed park improvements include erosion hazard areas, landslide hazard areas, and seismic hazard
areas. The extents of these critical areas are depicted on Figure 2, Site and Exploration Plan. Per ECDC
23.40.120(B), when an alteration to a critical area is proposed, such alteration shall be avoided, minimized,
or compensated for in the following sequential order of preference:
1. Avoiding the impact altogether by not taking a certain action or parts of an action;
— The proposed site improvements avoid geologically hazardous areas to the extent
practicable. Site improvements overlap with limited portions of erosion hazard areas near
the existing park area and on the slope leading up to the Interurban Trail to the north.
2. Minimizing impacts by limiting the degree or magnitude of the action and its implementation by
using appropriate technology or by taking affirmative steps, such as project redesign, relocation,
or timing, to avoid or reduce impacts;
— The proposed site improvements will utilize existing grades to the extent practicable and
will cross the northerly erosion hazard area at a nearly perpendicular angle to minimize
the amount of disturbance.
— Project plans avoid surcharge loads or other modifications to the landslide/seismic hazard
areas.
3. Rectifying the impact to wetlands, frequently flooded areas, and fish and wildlife habitat
conservation areas by repairing, rehabilitating, or restoring the affected environment to the
historical conditions or the conditions existing at the time of the initiation of the project;
— The site is an active city park and it is our understanding that no wetlands, frequently
flooded areas, and fish and wildlife habitat conservation areas are present.
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Geologically Hazardous Areas
Mathay-Bal linger Park Improvements
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— Permanent grades will be configured according to Sheet C3.1, Grading and Drainage Plan
of Mathay-Bal linger Park Site Improvements (plans), prepared by CG Engineering, dated
10 April 2024
4. Minimizing or eliminating the hazard by restoring or stabilizing the hazard area through
engineering or other methods;
— Project plans include appropriate stormwater control measures
— Project plans include permanent erosion control measures in the form of revegetation of
affected areas with appropriate ground cover or installation of erosion resistant surfacing.
— Project plans include temporary erosion control measures during construction.
— Clearing and grading will be conducted during the dry season (roughly May 1 to October
1 per ECDC 23.80.070(A)(6)).
5. Reducing or eliminating the impact or hazard over time by preservation and maintenance
operations during the life of the action;
— Site improvements will be maintained in general accordance with City of Edmond Park
Department Standards of Practice.
6. Compensating for the impact to wetlands, frequently flooded areas, and fish and wildlife habitat
conservation areas by replacing, enhancing, or providing substitute resources or environments;
and/or
— Not applicable.
7. Monitoring the hazard or other required mitigation and taking remedial action when necessary.
— Geotechnical construction monitoring will occur on an on -call basis during construction.
These visits will include observations by a Certified Erosion & Sediment Control Lead
(CESCL)-certified individual.
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Critical Areas Report
Geologically Hazardous Areas ZipperGeo
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Cd010141ILIM[QLIPT_1►11111X4101LTA IAi140101_A1111[001.1
Portions of the Site and its vicinity qualify as Geologically Hazardous Areas per ECDC 23.80. These areas
are depicted in Figure 2, Site and Exploration Plan.
Based on our conceptual geologic model of the Site and our review of the preliminary civil plan set, it is
our professional opinion that the risk that construction of the planned Site improvements will have an
adverse effect on the stability of nearby Geologically Hazardous Areas is low. It is our opinion that
conditions do not warrant a minimum setback from identified landslide or erosion hazard areas.
Mitigating measures will include temporary erosion control during construction as outlined in Sheets C2.1
and C2.2 of the preliminary civil plan set. Based on our review, the proposed temporary erosion control
measures appear sufficient. No further mitigation appears warranted in our opinion.
RELIANCE AND LIMITATIONS
This report is an instrument of service and has been prepared for the exclusive use of the City of Edmonds
in accordance with generally accepted engineering geology practice for specific application to this project
and site location. Our scope of services did not include a subsurface investigation. We assume that
information provided by others is accurate and complete. No warranty, express or implied, is made.
Technical Memorandum, Summary of Geotechnical Engineering Services, Mathay-Ballinger Park Project,
Edmonds, Washington, prepared by Landau Associates, dated 27 December 2023.
Critical Areas Determination, prepared by the City of Edmonds, dated 30 August 2024.
DLD2023-1391, 24105 78th Place West, Fill/Grade — Mathay Ballinger Park, prepared by the City of
Edmonds, dated 17 November 2023.
City of Edmonds Community Development Code, revision dated 5 March 2024.
Mathay-Bal linger Park Site Improvements (plans), prepared by CG Engineering, dated 10 April 2024.
Geologic Map of the Edmonds East and Part of the Edmonds West Quadrangles, Washington, 1:24,000
scale, US Geological Survey Miscellaneous Field Studies Map MF-1541, prepared by Minard, J.P., dated
1983.
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Critical Areas Report
Geologically Hazardous Areas
Mathay-Bal linger Park Improvements
3 June 2024
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Appendix A
Figures
Page 1 10
53
r
a -1�s L r
1.6
it
�,
-.. -,&:
APPROXIMATE PROJECT AREA 0
'' ► ice+ �� _ �� -s
REFERENCE: 2022 AERIAL PHOTOGRAPH, ACQUIRED FROM SNOHOMISH COUNTY
ONLINE PROPERTY INFORMATION PORTAL.
CB RIM=339.44 - 10' / 30' M / 0EC 1 % M
IE 12" RCP(SE)=336.39 / l / / /F 34' - - - �2? �/ 25' f� 0�� 28"
x / /t.
B 26•
CB RIM=337.76 26• /12' F s• j /
IE 12" RCI=335.86 / / / / I F F / M /// JDECI �
IE �12' RCI (S 335.7s I ^ / / / _ // ! �• / / / 7) I
CB RIM= 36.71 _ L _ / / 8 6• 14'x2
l \ 'M /
IE 12" P(NW)=328.88 /F / 1/
IE ,11/' CPP SW=328.88
E /
//// ///I M,/ //
CB RIM=327.80 / / j / 4' /'f F II 26" I 91100000804
IE 12' CPP(NE)_324.68 '
60 0 30 60 IE 12' PVC(SW)=324.68 + / // S� F
28'
SCALE IN FEET*, n /j// ' I /.: �// / \ / \M ��F----------1
T P-4 / / / / \ / F F YF� 4 F
/ 5 AR ` ' ' 26•
SHED P j / // BIKE / / / 95,481 SF /X F
SHED
/ Y " 2704310040280Q/
SHED //'/ // / F 10,
CB RIM=326.19 / I
IE 12' C(NE =323.39 r0 • /i P(jS�/// / /
IE 12" RCP(5;=323.39 �.% 1L"r / / / // F / / /
/ � I
0049
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26
/ .'•.
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/ DEC � +
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/ TP-1 PIT-1 // axt OFFFENCE 0.3(N) \
\
j/// , / / / �' M �3 HmH
F 9' 14' DEC DEC / CB RW=319.82 \
/7� P� Y�� ? OT 1 . IE 2' PWM=319.42 \
20'/ BACK) 00J4100100 NEW 20'x30' SLAB FOR PICNIC AREA \
0049110
/ 26 �(��/ / cl 00491100000803 \
/42 /F / j` 014" 695 nI
�i / / /� NEW RESTROOM I \
j / / / / F Q FFE: 322.0 I r \
m
• 5'SETBACK C36"
�329.05 / r RUCTURE SET�� I CO RIM=320.27
/ 14' I I �- J �-- could Nor OPEN
C M .6' / N as Os'02' E 135.78'(C) 1135.88'(P)EXISTING
U. / / 7'-1 0.8, CB -r LANDSCAPING I I
F .:': E 12" RCPSj 3I f72 IE 4' PIC(N)� 319.32 TO REMAIN LOT 4
E 12' PYC S)=318.70 IE 4' DIP(NW=319.32 I I
Al 22 j l l 12' E 4' 1884 IE 12" DIP(W=319.32 I
M / F g17f' / I I WARNER ADDITION
6 I LOT 2 I VOL. 15, PG. 76
N CB RIM=319.44 LAKE &ILLINGER I I I
CB RIM=319.89 I IE 12' M(N)=317.79 HOMESM ADD. I L
0.8' GPM I IE 12 RCP(S)=3/7.04 VOL 14, PG. 99
7.
�- �-31`n
IE 12' RCP((S94
318.I �, �--------
- - - - - - - - -
I I I
REFERENCE: SHEET C1.1, PRELIMINARY SITE PLAN, CG ENGINEERING, APRIL 10, 2024.
FIGURE 2, SITE AND EXPLORATION PLAN, LANDAU ASSOCIATES, SUMMARY OF GEOTECHNICAL ENGINEERING SERVICES, DECEMBER 27, 2023.
LEGEND
TP-1 APPROXIMATE LOCATION AND ID
OF TEST PIT (LANDAU, 2023)
SPIT-1 APPROXIMATE LOCATION AND ID
OF PILOT INFILTRATION TEST
(LANDAU, 2023)
EROSION HAZARD AREA PER
ECDC 23.80.020(A)
r LANDSLIDE/SEISMIC HAZARD
L - - J AREA PER ECDC 23.80.020(B/C)
THIS FIGURE IS MEANT TO BE VIEWED IN COLOR.
GRAYSCALE REPRODUCTION MAY LEAD TO INCORRECT
INTERPRETATION.
Critical Areas Report
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3 June 2024
Appendix 6
Landau Associates
Soil Classification Procedures,
Test Pit Logs, and
Grain Size Testing Results
Page 1 11
MAJOR
DIVISIONS
Soil Classification System
uscs
GRAPHIC LETTER
SYMBOL SYMBOL"'
TYPICAL
DESCRIPTIONS tz"3>
GRAVEL AND
CLEAN GRAVEL
p:�.. j.:p:
GW
Well -graded gravel; gravel/sand mixture(s); little or no fines
0 @ w
GRAVELLY SOIL
(Little or no fines)
Poorly graded gravel; gravel/sand mixture(s); little or no fines
o: o. Q ,p ,o .
GP
0 @�
(More than
Silty gravel; gravel/sand/siltmixture(s)
GRAVEL WITH FINES
GM
w E'w
coarse fraction retained
(Appreciable amount of
Qo N
on No. 4 sieve)
fines)
GC
Clayey gravel; gravelfsand/clay mixture(s)
0 LO z°
SAND AND
CLEAN SAND
$W
Well -graded sand; gravelly sand; little or no fines
ui m c
U) t r
SANDY SOIL
(Little or no fines)
Poorly graded sand; gravelly sand; little or no fines
SP
Q oo
O0
(More than 50%of
fraction
Silty sand; sand/siltmixture(s)
SAND WITH FINES
SM
coarse passed
(Appreciable amount of
$C
through No. 4 sieve)
fines)
Clayey sand; sand/clay mixture(s)
ML
Inorganic silt and very fine sand; rock flour; silty or clayey fine
p r
SILT AND CLAY
sand or clayey silt withlow plasticity
CL
U) o - N
Inorganic clay of low to medium plasticity; gravelly clay; sandy
ov'v
m
(Liquid limit less than 50)
clay; silty clay; lean clay
OL
Z @ w o
Organic silt; organic, silty clay of low plasticity
MH
Inorganic silt; micaceous or diatomaceous fine sand; elastic silt
a N
o'er
SILT AND CLAY
uJ �,z°
CH
Inorganic clay of high plasticity; fat clay
Z E
LL
(Liquid limit greater than 50)
Organic clay of medium to high plasticity; organic silt
OH
HIGHLY ORGANIC SOIL
PT
Peat; humus; swamp soil with high organic content
GRAPHIC LETTER
OTHER MATERIALS SYMBOL SYMBOL TYPICAL DESCRIPTIONS
PAVEMENT
• :.
AC Or PC
Asphalt concrete pavement or Portland cement pavement
ROCK
RK
Rock (See Rock Classification)
WOOD
WD
Wood, lumber, wood chips
DEBRIS
O O O
DB
Construction debris, garbage
Notes: 1. USCS letter symbols correspond to symbols used by the Unified Soil Classification System and ASTM classification methods. Dual letter symbols
(e.g., SP-SM for sand or gravel) indicate soil with an estimated 5-15% fines. Multiple letter symbols (e.g., MUCL) indicate borderline or multiple soil
classifications.
2. Soil descriptions are based on the general approach presented in the Standard Practice for Description and Identification of Soils (Visual -Manual
Procedure), outlined in ASTM D 2488. Where laboratory index testing has been conducted, soil classifications are based on the Standard Test
Method for Classification of Soils for Engineering Purposes, as outlined in ASTM D 2487.
3. Soil description terminology is based on visual estimates (in the absence of laboratory test data) of the percentages of each soil type and is defined
as follows:
Primary Constituent: > 50% - "GRAVEL," "SAND," "SILT," "CLAY," etc.
Secondary Constituents: > 30% and < 50% -'very gravelly," 'very sandy," 'very silty," etc.
> 15% and < 30% - "gravelly," "sandy," "silty," etc.
Additional Constituents: > 5% and <_ 15% - "with gravel," "with sand," "with silt," etc.
< 5% - "with trace gravel," "with trace sand," "with trace silt," etc., or not noted.
4. Soil density or consistency descriptions are based on judgement using a combination of sampler penetration blow counts, drilling or excavating
conditions, field tests, and laboratory tests, as appropriate.
Drilling and Sampling Key
SAMPLER TYPE & METHOD SAMPLE NUMBER & INTERVAL
Field and Lab Test Data
Code
WOR
Description
Weight of Rod
Graphic Code Description Sample Identification Number
®
a
3.25-in OD, 2.42-in ID Split Spoon
WOH
Weight of Hammer
®
b
2.00-in OD, 1.50-in ID Split Spoon
Sampler Graphic (variable)
PP = 1.0
Pocket Penetrometer, tsf
m
c
Thin -Wall Sampler (aka Shelby Tube)
TV = 0.5
Torvane, tsf
®
d
Grab Sample
Recovery Depth Interval
PID = 100
Photoionization Detector VOC screening, ppm
0
e
Single -Tube Core Barrel
W = 10
to
Moisture Content,
El
f
Double -Tube Core Barrel
1 1� Sample Depth Interval
D = 120
Dry Density,
®
g
2.50-in OD, 2.00-in ID WSDOT
Jpcf
®
h
3.00-in OD, 2.37-in ID Mod. Calif.
Portion of Sample Retained
-200 = 60
Material smaller than No. 200 sieve, %
®
i
Other - See text if applicable
for Archive or Analysis
GS
Grain Size - See separate figure for data
1
300-lb Hammer, 30-inch Drop
Groundwater
AL
Atterberg Limits - See separate figure for data
2
140-lb Hammer, 30-inch Drop
UU
Triaxial Unconsolidated Undrained (UU) Strength
3
Direct Push
V Approximate water level at time of
Cu
Triaxial Consolidated Undrained (CU) Strength
4
Vibrocore
- drilling (ATD)
Consol
1-D Consolidation Test
5
Other - See text if applicable
Approximate water level at time after
Perm
Permeability Test
6
Piston Extraction
- drilling/excavation/well
CA
Chemical Analysis
I
LANDAU Mathay-Ballinger Park Soil Classification Figure
Edmonds, Washington System and Key 3
A S S O C I A T E S
z
s
a
0
14
PIT-1
SAMPLE DATA
SOIL PROFILE
�
Excavation Method: Tracked Excavator
o z ca
a
cn
9
E
Ground Elevation (ft): Not Measured
.m -am
Q
o
U)
Excavated By: NW Excavating and Trucking, Inc.
w
in
a
12
65
Logged By: SC
rn 0s
c�
SP-
Brown, fine to coarse, SAND with gravel, silt,
SM
and root organics (loose, damp)
SM
(TOPSOIL)
Light brown, silty SAND with gravel and root
S-1 =
d
W = 30
organics (loose, damp)
(RECESSIONAL OUTWASH)
S-2 =
d
WGS 1
ML
-T
Brown -gray, SILT with gravel, trace cobbles,
and mottling (medium stiff, damp)
Infiltration test depth
S-3 = I d
S-4 JW I d I FFFFS-M Gray, silty, very gravelly, SAND with cobbles
(medium dense, damp)
Test Pit Completed 05/24/23
Total Depth of Test Pit = 10.5 ft.
GROUNDWATER
Groundwater Not Observed
Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate.
q 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols.
N
7
n
Figure
LALANDAU Mathay-Ballinger Park Log of Test Pit PIT-1
Edmonds, Washington 9 4
A S S O C I A T E S
z
s
a
0
12
TP-1
SAMPLE DATA
SOIL PROFILE
GROUNDWATER
�
Excavation Method: Tracked Excavator
o z ca
a
cn
9
E
Ground Elevation (ft): Not Measured
.m -am
Q
o
U)
Excavated By: NW Excavating and Trucking, Inc.
w
in
a
12
65
Logged By: SC
rn 0s
c�
SP-
Brown, fine to coarse, SAND with gravel, silt,
SM f
and root organics (loose, damp)
SM
(TOPSOIL)
Brown, silty SAND with gravel, and root
organics (loose, damp)
(RECESSIONAL OUTWASH)
S-1 =
d
W = 21
ML
Browmgray, SILT with gravel, trace cobbles,
Groundwater Not Observed
and mottling (medium stiff, damp)
S-2 = d W = 10
GS
S-3 = d
S-4 = d
Test Pit Completed 05/24/23
Total Depth of Test Pit = 9.5 ft.
---------------------
Light brown, gravelly, very silty, SAND with
cobbles (medium dense, damp)
-grades to gray, silty, and very gravelly
Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate.
0 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols.
N
7
n
Figure
LALANDAU Mathay-Ballinger Park Log of Test Pit TP-1
Edmonds, Washington 9
A S S O C I A T E S
N
14
TP-2
SAMPLE DATA
SOIL PROFILE
Excavation Method: Tracked Excavator
z m
a
@
to
-0
�,
Ground Elevation (ft): Not Measured
Q
Q
o
r
U)
Excavated By: NW Excavating and Trucking, Inc.
m e
m
iv
CL
m
U)
Logged By: SC
w cn 05
cn
1--
(0
D
SP-
Brown, fine to coarse, SAND with gravel, silt,
SM
and root organics (loose, damp)
(TOPSOIL)
SM
Brown, silty SAND with trace gravel, root
organics, and mottling (loose, damp)
S-1 I
d
=
W 21
(RECESSIONAL OLITWASH)
S-2= d ML Brown -gray, SILT with gravel, trace cobbles,
and mottling (medium stiff, damp)
-----------------------
S-3 = d SM Gray, silty SAND with gravel and cobbles
(medium dense, moist)
S-4 = d GS4 -grades to very gravelly, with trace cobbles,
mottling, and medium dense to dense
Test Pit Completed 05/24/23
Total Depth of Test Pit = 9.0 ft.
GROUNDWATER
Groundwater Not Observed
Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate.
0 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols.
N
athay
7
r
Figure
LALANDAU M Edmonds,
Ballinger Park Log of Test Pit TP-2
Edmonds, Washington
A S S O C I A T E S
N
SAMPLE DATA
_ � m
E C-
z m �
0 o Z aD > E c E
m
w (n 05 in
S-1I d
S-2 I d
W = 24
GS
_' 10 S-3 T I d
a
Test Pit Completed 05/24/23
0
Total Depth of Test Pit = 10.3 ft.
0
0
12
TP-3
SOIL PROFILE
o
Tracked Excavator
Excavation Method:
E
(o
-0
>,
Ground Elevation (ft): Not Measured
r
(Un
Excavated By: NW Excavating and Trucking, Inc.
12
U)
Logged By: SC
(2
SP-
SM
Brown, fine to coarse, SAND with gravel, silt,
and root organics (loose, damp)
SM
(TOPSOIL)
Brown, silty SAND with gravel, organics, and
mottling (loose, damp)
(RECESSIONAL OUTWASH)
---------------------
Light gray, sandy SILT with mottling (medium
stiff, damp)
-grades to gray and moist
GROUNDWATER
Groundwater Not Observed
Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate.
0 2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols.
N
7
athay
r
Figure
LALANDAU M Edmonds,
Ballinger Park Log of Test Pit TP-3
Edmonds, Washington /
A S S O C I A T E S
N
TP-4
SAMPLE DATA
SOIL PROFILE
Excavation Method: Tracked Excavator
z m
a
@
to
-0
�,
Ground Elevation (ft): Not Measured
Q
Q
o
r
U)
Excavated By: NW Excavating and Trucking, Inc.
M c
m
iv
CL
m
U)
Logged By: SC
w cn 05
cn
1--
(0
D
SP-
Brown, fine to coarse, SAND with gravel, silt,
SM
and root organics (loose, damp)
SM
(TOPSOIL)
Light brown, silty SAND with gravel, tree roots,
and trace cobbles (loose, damp)
S-1I
d
=
W 16
(RECESSIONAL OUTWASH)
S-2I
d
ML
Brown -gray, SILT with gravel, trace cobbles,
and mottling (medium stiff, damp)
S-3 = d SM Gray, silty, very gravelly, SAND with trace
cobbles (medium dense, damp)
Test Pit Completed 05/24/23
Total Depth of Test Pit = 10.0 ft.
Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate.
2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols.
GROUNDWATER
Groundwater Not Observed
� Figure
LALANDAU M Edmonds,
Ballinger Park Log of Test Pit TP-4 Q
Edmonds, Washington v
A S S O C I A T E S
74217.01 6/23/23 P:\074\217.010\T\GINT\074217.010.011 MATHAY BALLINGER PARK.GPJ GRAIN SIZE FIGURE
100
U.S. Sieve Opening in Inches
6 4 3 2 1.5 1
1/2 3/8 3 j
U.S. Sieve Numbers
6 810 1416 20 30 40 5060 100 140 200
Hydrometer
90
80
70
L
m
a
60
c
ii
50
c
a
40
30
20
10
0
100 10 1 0.1 0.01 0.001
Grain Size in Millimeters
LANDAUEdmonds,
A S S O C I A T E S
MathaLAy-Bal linger Park
Washington
Grain Size Distribution
Figure
Q
J
Cobbles
Gravel
Sand
Silt or Clay
Coarse
Fine
Coarse
Medium
Fine
Symbol
Exploration
Number
Sample
Number
Depth
(ft)
Natural0
Moisture (/o)
Soil Description
Unified Soil
Classification
•
PIT-1
S-2
2.3
31
SILT
ML
m
TP-1
S-2
3.8
10
Gravelly, very silty, fine to coarse SAND
SM
A
TP-2
S-4
8.3
4
Silty, very gravelly, fine to coarse SAND
SM
*
TP-3
S-2
3.4
24
Sandy, SILT
ML