HomeMy WebLinkAboutGEO2021-00006 - GEO Geological Review - 9/8/2020 Ga ZoZI -6000(0
RECEIVED
PLANNING JAN
2 0 2021
615 W. Alder Street
Geotechnical Report
Kenncuy Single Family Residence
151 NE Admiral Drive, Belfair
Parnal Nn 17ZZ(1_Cd_�l(1(11 Z
Mason County, Washington
September 8, 2020
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Prepared For:
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Prepared By:
Fnvirnta�h Fnainaarina
PO Box 984
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MASON COUNTY -
COMMUNITY SERVICES Geotechnical Report
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Instructions:
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Resource Ordinance. If an item is found not applicable,the report should explain the basis for the conclusion.
1808.7.1 of the International Building Code Section for Foundations on or adjacent to slopes.
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Site Address 151 NE Admiral Drive
(�) (a) A aiscussion of general geologic conditions in the vicinity of the proposea aeveiopment.
Located on page(s) 5
(b) A discussion of specific soil types,
(c) A discussion of ground water conditions,
Located on page(s)- ---7
Located on page(s) 3
(e) A discussion of the location of upland waterbodies and wetlands,
(f) A discussion of history of landslide activity in the vicinity, as available in the referenced maps and
records.
Located on oaae(s) 8
(2) A site plan which identifies the important development and geologic features.
Located on Map(s) Site Plan—Appendix A_
Located on Map(s) Site Plan and Soil Logs(Appendix B)
...L.....I.....L...11 L....:1..1:.....•....:1 /..... L....L.n:.F.... .....F s....\ .... .. ......1....:..... ..F.1..... ..
Located on Map(s) Site Plan
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Located on Map(s) Soil Profile(Appendix B)
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Bishop's Method of Circles.The minimum static safety factor is 1.5,the minimum seismic safety
factor is 1.1,and the quasi-static analysis coefficients should be a value of 0.15.
(7) (a) Appropriate restrictions on placement of drainage features,
Located on page(s) 17
•r.
Located on page(s) 18
(c) Appropriate restrictions on placement of compacted fills and footings.
15
(d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other slopes.
Located on page(s) 17
Located on page(s) 16
(8) Recommendations for the preparation of a detailed clearing and grading plan which specifically identifies
removal. v J
Located on page(s) 17
mitigating measures to be implemented during construction to protect the slope from erosion, landslides and
harmful construction methods.
10
(10) An analysis of both on-site and off-site impacts of the proposed development.
Located on page(s) 11
buffer widths.
Located on page(s) 17- 18
Located on page(s) 18
(13) A site map drawn to scale showing the property boundaries,scale,north arrow,and the location.2^drat:rs
Located on Map(s) Site Plan
with specialized knowledge of geotechnicaUgeologiCal rr c -'- "' ==' =^:==J in
the Cjato of W achinntnn wish¢nne iol tennt.A-4-^of the.I— I e nefitinno I alcn a r..tifie that the.reantrvahninal
PAL CLYDF Sr Report,dated September 8,2020,and entitled Kennedy
Single Family Residence, meets all the regLdramantc of the
y Mason County Hesource Ordinance,Geologically Hazardous
Areas Section,is complete and true,that the assessment
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FSS��tiALENG` hazard can be mitigated through the included geotechnical
9/8/2020 design recommendations,and that all hazards are mitigated in
Disclaimer:Mason County does not such a manner as to prevent harm to property and public
certify the quality of the work done in health and safety.
this Geotechnical Report.
Page 2 of 2
TABLE OF CONTENTS
1.0 INTRODUCTION.........«......«..............».........................«..................................................................1
1.1 PROJECT INFORMATION.................................................................................................................... 1
12 PURPOSE OF INVESTIGATION AND SCOPE OF WORK........................................................................ 1
2.0 SURFACE CONDITIONS.».................................................................................................................3
2.1 GENERAL OBSERVATIONS..................................................................................................................3
2.2 TOPOGRAPHY.....................................................................................................................................3
2.2.1 Upslope Geomorphology............................................................................................................3
2.3 SURFACE DRAINAGE..........................................................................................................................3
7.3.1 171n,a1 nn,a Wnfam ediaS................................................................................................. ?
2.4 SLOPE AND EROSION OBSERVATIONS...............................................................................................4
3.0 SUBSURFACE INVESTIGATION....................................»..............................................................5
3.1 FIELD METHODS.SAMPLING AND FIELD TESTING...........................................................................5
3.2 GENERAL GEOLOGIC CONDITIONS...................................................................................................5
3.3 SPECIFIC SUBSURFACE CONDITIONS.................................................................................................7
3.3.1 Groundwater............................................................................................................................... 7
4.0 ENGINEERING ANALYSES AND CONCLUSIONS...»«»«»..».................«.............................«...8
4.1 SLOPE STABILITY...............................................................................................................................8
4.1.1 Slope Stability Analysis..............................................................................................................9
a2- ERLksmm ........................................................•....................----------....................................................10
4.3 SEISMIC CONSIDERA VIONTS.A..wm i•ter�.� ..............................................................................10
4.3.1 Liquefaction..............................................................................................................................11
4.4 LANDSLIDE,EROSION AND SEISMIC HAZARDS CONCLUSIONS........................................................11
4.5 iL-,TE.P.:.• ERTH M- .wItEseC...........................................................................................................11
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5.1 BUILDING FOUNDATION RECOMAIENDATIONS.................................................................................13
5.1.1 Bearing Capacity.......................................................................................................................13
5.1.2 Ss!kinmem-f..................................................................................................................................14
5.1.3 C^ ni_t_ _ _.. _ _.- .. ...... .... --..........14
5.2 EARTHwoRK CONSTRUCTION RECommENDATIONS.......................................................................14
5.2.1 Excavation.................................................................................................................................14
PLawe-ment and Compac&n nr Nativp SoM and Engineered Fill::,.,.-- , 15
..........................16
5.2.4 Wet Weather Considerations....................................................................................................16
5.2.5 Building Pads............................................................................................................................16
5.3 BoILDLNG 4-NLiFooT1;GS::DY-r.................................................................................................16
— - - ............................................------............ 17
5.5 VEGETATION BUFFER AND CONSIDERATIONS.................................................................................17
5.6 ironARY AND PERMANENT EROSION CONTROL .............................18
..........................................
5.7 Ci;"i •V R P,'FIELDS.................... - -- - -
_ _.._..__ 1_
------------
6.0 CLOSURE».«........»..»...»..........»...................................................»...................................................19
Appendix A-Site Plan
Appendix C-Slope Stability
Appendix P—Erosion Control
1.0 INTRODUCTION
Envirotech Engineering (Envirotech) has completed a geotechnical investigation for a planned
single family residence located at 151 NE Admiral Drive, identified as parcel number 12330-54-
00013. Mason County. Washington. See the vicinity map on the following page for a general
depiction of the site location.
An initial geotechnical evaluation of the project was conducted by Envirotech on August 18,
2020. It was determined that slopes in excess of 40% with a vertical relief of at least 10 feet were
present within 300 feet of the planned development. Based on this site characteristic, the
proposed development will require a gcotechnical report pursuant to Landslide Hazard Areas of
Mason County Resource Ordinance (MCRO) 17.01.100. During the site visit by Envirotech,
surface and subsurface conditions were assessed. After completion of the field work and
applicable project research, Envirotech prepared this geotechnical report which, at a minimum,
conforms to the applicable MCRO.
As presented herein,this report includes information pertaining to the project in this Introduction
Section; observations of the property and surrounding terrain in the Surface Conditions Section;
ueid methods and soil descriptions in the Subsurface investigation Section; supporting
documentation with relation to slope stability, erosion, seismic considerations, and lateral earth
pressures in the Engineering Analyses and Conclusions Section; and, recommendations for
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vegetation in the Engineering Recommendations Section.
1A Project Information
Information pertaining to the planned development of the project was provided by the proponent
of the property.The planned development consists of a I-or 2-story single family residence,new
on-site septic system, and other ancillary features typical of this type of development.
Approximate building footprint and other proposed features with relation to existing site
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wr'iuiuulla arc.rffuJualAAf On On,JlU..Niap prrivfu\.0 in AptK.uulA A of uns l poiftl.
1.2 Purpose of Investigation and Scope of Work
The purpose of this geotechnical investigation is to assess geological hazards, and evaluate the
project in order to provide geotechnical recommendations that should be implemented during
development. The investigation included characterizing the general proicct surface and
subsurface conditions, and evaluating the suitability of the soils to support the planned site
activities.
In order to fulfill the purpose of investigation, the geotechnical program completed for the
proposed improvements of the project include:
• Review project information provided by the project owner and/ or owner's
representative;
• Conduct a site visit to document the site conditions that may influence the construction
and performance of the proposed improvements of the project;
• Define general subsurface conditions of the site by observing subsoils within test pits
Envirotech Engineering Geotechnical Report
PO Box 984 page 1 Parcel 12330-54-00013
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
and/ or cut banks, review geological maps for the general area, research published
references concerning slope stability, and review water well reports from existing wells
the fraj:,ct;
• Collect bulk samples,as applicable,at various depths and locations;
• Perform soils testing to determine selected index and/or engineering properties of the site
soils;
• Complete an engineering analysis supported by the planned site alterations, and the
surface and subsurface conditions that were identified by the field investigation, soil
testing,and applicable project research;and,
• Establish conclusions based on findings, and make recommendations for foundations,
drainage, slope stability, erosion control, earthwork construction requirements, and other
considerations.
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Envirotech Engineering Geotechnical Report
PO Box 984 page 2 Parcel 12330-54-00013
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
2.0 SURFACE CONDITIONS
Information pertaining to the existing surface conditions for the project was gathered on August
18, 2020 by a representative with Envirotech. During the site visit, the type of geotechnical
investigation was assessed, site features were documented that may influence construction, and
site features were examined that may be influenced by construction. This Surface Conditions
Section provides information on general observations, vegetation, topography, drainage and
observed slope/ erosion conditions for the project and surrounding areas that may impact the
project.
2.1 General Observations
Currently, the property is vacant with an existing driveway. Vegetation on and near the project
consists primarily of secondary growth firs and other trees and shrubbery common to this area of
the Pacific Northwest. An aerial photo of the project and immediate vicinity is provided on the
following page.
2.2 Topography
The topographic information provided in this section was extrapolated from a public lidar source,
and incorporated observations and field measurements. Where necessary, slope verification
included measuring slope lengths and inclinations with a cloth tape and inclinometer. See the Site
Plan in Appendix A in this report for an illustration of general topography with respect to the
planned development.
Critical descending slopes, with grades exceeding 40% appear to be within 300 feet of the
planned development. The maximum critical slope is approximately 73% with a vertical relief of
about 60 feet.
Ascending grades are generally located to the west of the planned development. These slopes are
relatively minor within 300 feet of the project,with no apparent slope grades of more than 25%.
2.2.1 Upslope Geomorphology
The upland area of the property and beyond is generally situated on a hillside of glacial
origin.
23 Surface Drainage
Runoff originating upslope of the development is mostly diverted away from the property by
accommodating topography. Excessive scour, erosion or other indications of past drainage
problems were not observed within the immediate vicinity of the planned development.
23.1 Upslope Water Bodies
There are no apparent water bodies or wetlands located upslope from the planned
development that would significantly influence the project.
Envirotech Engineering Geotechnical Report
PO Box 984 page 3 Parcel 12330-54-00013
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
2.4 Slope and Erosion Observations
The slope gradients near the project signal a potential landslide or erosion hazard area. Some
indicators that may suggest past slope movements include:
• Outwash of sediments near the bottom of the slope,
• Fissures, tension cracks, hummocky ground or stepped land masses on the face or top of
the slope,and parallel to the slope,
• Fine,saturated subsurface soils,
• Old landslide debris,
• Significant bowing or leaning trees,or,
• Slope sloughing or calving.
A large-scale landslide was discovered downslope and to the east of the planned development
within a distance of 300 ft. The depth was approximately 15 feet, and the width was over 300
feet.
N
Aerial Photo from Mason County Website
Envirotech Engineering Geotechnical Report
PO Box 984 page 4 Parcel 12330-54-00013
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
3.0 SUBSURFACE INVESTIGATION
Information on subsurface conditions pertaining to the project was primarily gathered on August
18,2020 by a representative with Envirotech.Applicable information on field methods,sampling,
field testing, general geologic conditions, specific subsurface conditions, and results from soil
testing are presented in this section of the report. Appendix B of this report includes pertinent
information on subsurface conditions for the project, such as subsoil cross-section(s), test pit
log(s), and applicable water well report(s). Water well reports were utilized to estimate ground
water levels, and if sufficient,were used in identifying subsoil types. Applicable test pit locations
are depicted on the Site Plan provided in the appendix of this report.
3.1 Field Methods,Sampling and Field Testing
Information on subsurface conditions for the project was accomplished by examining soils within
r nearby banks extending to depths of u to 7 feet below the natural ground
test its and/ o p
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surface. Information on subsurface conditions also included reviewing geological maps
representing the general vicinity of the project, and water well reports originating from nearby
properties.
Soil samples were not obtained from this project. Envirotech measured the relative density of the
near-surface in-situ soils by gauging the resistance of hand tools. Within testing locations, field
testing results generally indicated loose to medium dense soils in the upper 48 inches, and very
dense soils from 48 inches to the depth of terminous.
3.2 General Geologic Conditions
In general, soils at the project are composed of materials from glacial advances. The geologic
conditions as presented in the "Geologic Map of Washington," compiled by J. Eric Schuster,
2002 indicates Quaternary sediments, Qg. Quaternary sediments are generally unconsolidated
deposits,and dominantly deposited from glacial drift,including alluvium deposits.This project is
located within the Puget Lowland. Typically, "lower tertiary sedimentary rocks unconformably
overlie the Crescent Formation."as revealed in the Geologic Map. Initial sedimentary rocks were
formed from shales, sandstones and coal deposits from rivers. During the Quaternary period, the
Puget Lowland was covered by numerous ice sheets,with the most recent being the Fraser glacier
with a peak of approximately 14,000 years ago. Upon the glacial retreat, the landscape was
formed by glacial erosion glacial drift deposits.
The "Geologic Map of the Belfair 7.5-minute Quadrangle, Mason, Kitsap and Pierce Counties,
Washington"by Michael Polenz, Katelin Alldritt,Nicholas J. Heheman, Isablle Y. Sarikhan,and
Robert L.Logan,July 2009,provides the following caption(s)for the project area:
Envirotech Engineering Geotechnical Report
PO Box 984 page 5 Parcel 12330-544M13
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
\•ashon glacial ice-contact deposits--Saud,gavel,lodgment till,and
flow till;minor silt and clay beds;tan to gay;variably sorted;loose to
compact massive to well stratified;locally includes over-steepened beds
that typically reflect sub-ice flow,but their dip may,along with
small-scale shears,also have developed as collapse features or due to
glaciotectonic and tectonic deformation;formed in the presence of
meltwater alongside ice,generally toward the end of the glaciation-and is
thus commonly accompanied by stagnant-ice features,such as kettles and
less-orderly hummocky topography.eskers(also separately mapped as
subunit Qge),and subglacial or subaenal outwash channels.Deposits and
morphologies that support conceptual association with both ice and
meltwater are common in the map area and suggest that where unit Qgw is
mapped in the presence of fluted topography,it is commonly only a few
feet thick and locally could have been mapped as undifferentiated dnft
(unit W.Elsewhere,the unit may be over 100 ft thick.Unit Qgw also
includes poorly consolidated till commonly accompanied by underlying,
angular sand and noted as"sub-glacially reworked till"by Laprade(2003)
(see Geologic Setting),especially in fluted areas that lack dead-ice
features.See unit Qgo and Fig.4 for discussion of similarities between
units Qgw and Qgo(and its subunits Qgos,Qgol;and Qgol).A
discrepancy between this map and the Vaughn quadrangle to the south
resulted where Logan and Walsh(2007)mapped undifferentiated
Quaternary deposits(unit Qu)because they lacked field exposures and
geomorphic signs of the dead-ice deposits that are apparent north of the
boundary.Dead-ice topography north of the boundary also reveals a sandy
deposit mapped as unit Qgos by Logan and Walsh(2007)to be a facies
within unit Qgic.Locally divided into:
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Envirotech Engineering Geotechnical Report
PO Box 984 page 6 Parcel 12330-54-00013
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
3.3 Specific Subsurface Conditions
The following subsurface conditions are estimated descriptions of the project subgrade utilizing
information from the depth of penetration at all testing, sampling, observed and investigated
locations. Soils for this project were primarily described utilizing the Unified Soil Classification
System(USCS)and the Soil Conservation Service(SCS)descriptions.
The project is currently composed of native soils without indications of fill. Within test pit
locations, soils within the upper 2 feet of natural ground were generally observed to be moist,
brown silty sand with gravel (SM). Soils below the upper 2 feet layer were observed to be poorly
graded sand with gravel and a trace of silt(SP)to a depth of 5 feet.
The relative densities of the soil within selected test pits are provided above in Section 3.1.
Expanded and specific subsurface descriptions, other than what is provided in this section, are
provided in the soil logs located in Appendix B of this report.
According to the "Soil Survey of Mason County," by the United States Department of
Agriculture, Soil Conservation Service, the site soils are described as Everett Gravelly Loamy
Sand, E,, with 5% - 15% slopes. The soil designations are depicted in the aerial photograph
below, and descriptions are provided in Appendix B of this report.
A
Soil Survey From USDA Natural Resources Conservation Service
3.3.1 Groundwater
From the water well report(s)and knowledge of the general area,permanent groundwater
is at least 150 feet directly below the property at the building pad location. Surface
seepage or perched groundwater at shallow depths was not observed on-site, nor
indicated on the well reports.
Envirotech Engineering Geotechnical Report
PO Box 984 page 7 Parcel 12330-54-00013
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
4.0 ENGINEERING ANALYSES AND CONCLUSIONS
The following section includes slope stability, erosion, seismic considerations, and impacts to
both on-site and off-site properties.
4.1 Slope Stability
Landslides are natural geologic processes, and structures near slopes possess an inherent risk of
adverse settlement, sliding or structural damage due to these processes. Geotechnical engineering
cannot eliminate these risks for any site with sloping grades because gravity is constantly
inducing strain on the sloping soil mass. Excessive wet weather and/ or earthquakes will
exacerbate these strains. Geotechnical engineering considers excessive wet weather and `design'
earthquakes in order to provide an acceptable factor of safety for developing on or near sloping
terrain with relation to current engineering protocol. These factors of safeties are based on
engineering standards such as defining engineering properties of the soil, topography, water
conditions, seismic acceleration and surcharges. Surface sloughing or other types of surficial
slope movements usually do not affect the deep-seated structural capability of the slope.
However, repeated surficial slope movements, if not repaired, may present a threat to the
structural integrity of the slope.If any slope movement arises,the slope should be inspected by an
engineer.Subsequently,maintenance may be required in order to prevent the possibility of further
surficial or deep seated slope movements that may be damaging to life and property.
According to the Coastal Zone Atlas of Mason County, Washington, the project is within and
near terrain labeled `Stable' and `Intermediate' regarding potential landslide activity.
Descriptions of these mapping units may be found in the aforesaid Atlas. A Stability Map from
the Coastal Zone Atlas for the general area of this project is provided below:
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intermediate
Moddied
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i 4V Unstable(old slide)
Unstable(recent slide)
Map from Washington State Department of Ecology Website
Envirotech Engineering Geotechnical Report
PO Box 984 page 8 Parcel 12330-54-00013
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
According to the Resource Map from the Washington State Department of Natural Resources
(DNR), the project is not within terrain labeled `highly unstable' relating to soils. DNR labeled
portions of this project as medium and high slope instability with relation to slopes. A Resource
Map from the DNR Forest Practices Application Review System is provided below:
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Soils-Highly Erodible Soils
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i Westside Slope Stability Model(FIR)
Ii Moderate Slope Instability
. High Slope Instability
300tt =
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Resource Map from Washington State Department of Natural Resources Website
4.1.1 Slope Stability Analysis
The Simplified Bishop Method, utilizing `STABLE' software, was used to analyze the
static stability of the site slopes. Seismic conditions were estimated utilizing worst case
scenario values from the static analysis,a quasi-static analysis coefficient of at least 0.15,
and applying the applicable values to STABLE software. Various radii's and center
points of the circle were automatically selected, and produced factor of safeties in a
graphical and tabular format. Worst case scenario values were used in the slope stability
analysis in regards to topography, surcharges, water content, internal friction and
cohesion of the site soils. STABLE software has been repeatedly checked with manual
calculations, and consistently proved to be a very conservative program. The following
soil properties were used in the analysis, and are based on observed conditions, known
geology,and/or published parameters:
Upper 2 feet soil depth
Soil unit weight: 132 pcf
Angle of internal friction: 30 degrees
Cohesion: 200 psf
Envirotech Engineering Geotechnical Report
PO Box 984 page 9 Parcel 12330-54-00013
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
Soils below 2 feet in depth
Soil unit weight: 100 pcf
Angle of internal friction: 33 degrees
Cohesion: 0 psf
Based on the slope stability analysis, unacceptable factors of safety could be present on
and near the critical slope,but do not reflect conditions where development is expected to
occur. For this project, at the location of the proposed development, minimum factor of
safeties for static and dynamic conditions were estimated to be at least 1.5 and 1.1,
respectively. See the slope stabilityinformation in Appendix C for a depi
ction of
ors of safe away from the project.
minimum fact
safety Y P J
4.2 Erosion
Based on the USCS description of the project soils, the surface soils are considered moderately
erodible. According to the Resource Map from the Washington State DNR, as provided above,
the project is not within terrain labeled `highly erodible.' This project is not within an erosion
hazard area as defined by the MCRO. Erosion hazard areas are those with USDA SCS
designations of River Wash (Ra), Coastal Beaches (Cg), Alderwood Gravelly Sandy Loam on
slopes 15% or greater (Ac and Ad), Cloquallum Silt Loam on slopes 15% or greater (Cd),
Harstine Gravelly Sandy Loam on slopes 15% or greater (Hb), and Kitsap Silt Loam on slopes
15%or greater(Kc).
It is our opinion that minor erosion control recommendations provided in this report is sufficient
for the development of this project, and additional engineered erosion control plans are not
required. Temporary and permanent erosion control measures are required for site development.
Extents of temporary erosion control will mostly depend on the timeliness of construction,
moisture content of the soil,and amount of rainfall during construction. Soil erosion typical to the
existing site conditions and planned disturbance of the project include wind-borne silts during dry
weather, and sediment transport during prolonged wet weather. Sediment transport could be from
stormwater runoff or tracking off-site with construction equipment.
The Temporary and Permanent Erosion Control Section (Section 5.6) of this report consist of
specific erosion controls to be implemented. Additional erosion control information and
specifications may be found in the latest addition of the "Stormwater Management Manual for
Western Washington," prepared by the Washington State Department of Ecology Water Quality
Program.
43 Seismic Considerations and Liquefaction
There are no known faults beneath this project. The nearest Class `A' or Class `B' fault to this
property is the Tacoma Fault Zone, which is approximately 2 miles to the south of this project.
This information is based on the USGS Quaternary Fault and Fold Database for the United States.
Potential landslides due to seismic hazards have been considered, and are addressed in the Slope
Stability Analysis Section provided earlier in this report.
Envirotech Engineering Geotechnical Report
PO Box 984 page 10 Parcel 12330-54-00013
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
Soils immediately below the expected foundation depth for this project are generally Type D,
corresponding to the International Building Code (IBC) soil profiles. According to the IBC, the
regional seismic zone is 3 for this project. The estimated peak ground acceleration ranges from
0.50g to 0.60g.This estimation is based on the United States Geological Survey(USGS)National
Seismic Hazard project in which there is an estimated 2% probability of exceedance within the
next 50 years.
4.3.1 Liquefaction
The potential for liquefaction is believed to be low for this project.This is based,in part,
on the subsurface conditions such as soil characteristics and the lack of a permanent
shallow water table. Subgrade characteristics that particularly contribute to problems
caused from liquefaction include submerged, confined,poorly-graded granular soils (i.e.
gravel,sand,silt).Although gravel-and silt-sized soil particles could be problematic,fine
and medium grained sands are typically subjected to these types of seismic hazards. No
significant saturated sand stratifications are anticipated to be within the upper 50 feet of
the subsoil for this project.
4.4 Landslide,Erosion and Seismic Hazards Conclusions
DNR did not indicate historic landslide activity near the project. Mapped slope conditions, as
delineated by the Departments of Ecology and/ or Natural Resources, were considered in our
slope stability assessment. Based on the proximity and severity of mapped delineations with
respect to the proposed development, results of the aforesaid slope stability analysis, observed
surface conditions, and other pertinent information, it is our opinion that the proposed
development may occur in accordance with the recommendations in this geotechnical report.
4.5 Lateral Earth Pressures
Retaining walls may be utilized for this project. The lateral earth pressures exerted through the
backfill of a retaining wall are dependent upon several factors including height of retained soil
behind the wall, type of soil that is retained, degree of backfill compaction, slope of backfill,
surcharges,hydrostatic pressures,earthquake pressures,and the direction and distance that the top
of the wall moves. A structural or geotechnical professional should design retaining walls based
on specific conditions.
Soil parameters for the structural design of retaining walls may be estimated as 134 pounds per
cubic foot (pcf) and 118 pcf for engineered fill and native soils, respectively. The angle of
internal friction may be estimated as 36 degrees and 32 degrees for engineered fill and native
soils,respectively.These soil parameters are based on soil type and placement conforming to the
Earthwork Construction Recommendations Section in this report.
4.6 On-Site and Off-Site Impacts
From a geotechnical position, it is Envirotech's opinion that the subject property and adjacent
properties to the proposed development should not be significantly impacted if all
recommendations in this report are followed. This opinion is based on the expected site
development, existing topography, existing nearby development, land cover, and adhering to the
Envirotech Engineering Geotechnical Report
PO Box 984 page 11 Parcel 12330-54-00013
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
recommendations presented in this report. Future development or land disturbing activities on
neighboring properties or properties beyond adjacent parcels that are upslope and/or downslope
from the subject property could cause problems to the subject property. For this reason, future
development or land disturbance near the subject property should be evaluated by a geotechnical
engineer.
Envirotech Engineering Geotechnical Report
PO Box 984 page 12 Parcel 12330-54-00013
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
5.0 ENGINEERING RECOADIENDATIONS
The following sections present engineering recommendations for the proposed improvements of
the project. These recommendations have been made available based on the planned
improvements as outlined in the Introduction Section of this report; general observations
including drainage and topography as recapitulated in the Surface Conditions Section; soil/
geologic conditions that were identified from the geotechnical investigation that is summarized in
the Subsurface Investigation Section; and, project research, analyses and conclusions as
determined in the Engineering Analysis and Conclusions Section. Recommendations for the
project that is provided herein,includes pertinent information for building foundations,earthwork
construction, building and/or footing setbacks, drainage, vegetation considerations, and erosion
control.
5.1 Building Foundation Recommendations
Recommendations provided in this section account for the site development of a typical one- or
two-story, single family residential structure. The recommended allowable bearing capacities and
settlements as presented below, consider the probable type of construction as well as the field
investigation results by implementing practical engineering judgment within published
engineering standards. Evaluations include classifying site soils based on observed field
conditions and soil testing for this project. After deriving conservative relative densities, unit
weights and angles of internal friction of the in-situ soils, the Terzhagi ultimate bearing capacity
equation was utilized for determining foundation width and depth. Foundation parameters
provided herein account for typical structural pressures due to the planned type of development.
A structural analysis is beyond the scope of a geotechnical report, and a structural engineer may
be required to design specific foundations and other structural elements based on the soil
investigation. Stepped foundations are acceptable, if warranted for this project. Continuous,
isolated, or stepped foundations shall be horizontally level between the bottom of the foundation
and the top of the bearing strata.The frost penetration depth is not expected to extend beyond 12
inches below the ground surface for this project under normal circumstances and anticipated
design features.
5.1.1 Bearing Capacity
Existing in-situ soils for this project indicates that the structure can be established on
shallow, continuous or isolated footings. Foundations shall be established on relatively
undisturbed native soil that is competent and unyielding. Alternatively, foundations may
be constructed on selective re-compacted native soil or compacted engineered fill as
described in the Earthwork Construction Recommendations Section of this report.
For a bearing capacity requirement of no more than 1500 psf, a minimum continuous
footing width of 15 inches shall be placed at a minimum of 12 inches below the existing
ground surface atop unyielding soils. For a columnar load of no more than 3 tons, a
circular or square isolated foundation diameter or width shall be at least 24 inches.
Foundation recommendations are made available based on adherence to the remaining
recommendations that are provided in this report. Alterations to the aforementioned
foundation recommendations may be completed upon a site inspection by a geotechnical
engineer after the foundation excavation is completed.
Envirotech Engineering Geotechnical Report
PO Box 984 page 13 Parcel 12330-54-00013
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
5.1.2 Settlement
Total and differential settlement that a structure will undergo depends primarily on the
subsurface conditions, type of structure, amount and duration of pressure exerted by the
structure,reduction of pore water pressure, and in some instances,the infiltration of free
moisture. Based on the expected native soil conditions, anticipated development, and
construction abides by the recommendations in this report, the assumed foundation
system may undergo a maximum of 1.0 inch total settlement, and a maximum differential
settlement of 0.75 inch.
5.1.3 Concrete Slabs-on-Grade
Interior slabs, if utilized, should be supported on a minimum of 4 inches of compacted
coarse, granular material (Retained on U.S. Sieve #10 or greater) that is placed over
undisturbed, competent native subgrade or engineered fill per the Earthwork
Recommendations Section below.
The recommendations for interior concrete slabs-on-grade as presented herein are only
relevant for the geotechnical application of this project. Although beyond the scope of
this report, concrete slabs should also be designed for structural integrity and
environmental reliability. This includes vapor barriers or moisture control for mitigating
excessive moisture in the building.
5.2 Earthwork Construction Recommendations
Founding material for building foundations shall consist of undisturbed native soils to the
specified foundation depths. Compacted engineered fill, or selective re-compacted native soils
may be used to the extents provided in this Earthwork Construction Recommendations Section.
The following recommendations include excavations, subgrade preparation, type of fill, and
placement of fill for building foundations.
5.2.1 Excavation
Excavation is recommended to remove any excessive organic content or other deleterious
material, if present, beneath foundations and to achieve appropriate foundation depth.
Additional sub-excavation will be required for this project if the soils below the required
foundation depth are loose, saturated, not as described in this report, or otherwise
incompetent due to inappropriate land disturbing, or excessive water trapped within
foundation excavations prior to foundation construction.All soils below the bottom of the
excavation shall be competent, and relatively undisturbed or properly compacted fill. If
these soils are disturbed or deemed incompetent, re-compaction of these soils below the
anticipated footing depth is necessary. Excavations shall be completely dewatered,
compacted, and suitable before placement of additional native soil, engineered fill or
structural concrete.
Envirotech Engineering Geotechnical Report
PO Box 984 page 14 Parcel 12330-54-00013
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
5.2.2 Placement and Compaction of Native Soils and Engineered Fill
For engineered fill or disturbed native soils that will be utilized as fill material directly
beneath foundations, observation and/ or geotechnical testing is required prior to
foundation construction. The following placement and compaction requirements are
necessary.
For disturbed native soils or engineered fill beneath foundations, limits of compacted or
re-compacted fill shall extend laterally from the bottom edge of the foundation at a rate of
one horizontal foot for each foot of compacted or re-compacted fill depth beneath the
foundation.See the illustration below.
FOOTING
COMPACTED
NATIVE S❑ILS
OR ENGINEERED 1
FILL
TTL— ISTURBED SUBERAW
Both engineered fill and native soils used as compacted fill should be free of roots and
other organics, rocks over 6 inches in size, or any other deleterious matter. Because of
moisture sensitivity, importing and compacting engineered fill may be more economical
than compacting disturbed native soils. Engineered fill shall include having the soils
retained on the No. 4 sieve crushed (angular), and should consist of the following
gradation:
U.S. Standard Sieve %Finer(by weight)
6" 100
3" 60— 100
No.4 20—60
No.200 0-8
Table 1
Particle Size Distribution of Engineered Fill
Compaction shall be achieved in compacted lifts not to exceed 6 inches for both native
soils and engineered fill,respectively.Each lift should be uniformly compacted to at least
95% of the modified Proctor maximum dry density (ASTM D 1557) and within 3% of
optimum moisture content. Each lift surface should be adequately maintained during
construction in order to achieve acceptable compaction and inter-lift bonding.
Temporary earth cuts and temporary fill slopes exceeding 4 feet in height should be
limited to a slope of 2:1 (horizontal:vertical). Utility trenches or other confined
excavations exceeding 4 feet should conform to OSHA safety regulations. Permanent cut
and fill slopes shall be limited to a slope of 2:1, unless otherwise approved by an
engineer.
Envirotech Engineering Geotechnical Report
PO Box 984 page 15 Parcel 12330-54-00013
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
51.3 Retaining Wall Backfill
Native soils may be used as retaining wall backfill for this project if the total wall height
is 4 feet or less and the recommendations below are followed. Native soils for retaining
walls exceeding 4 feet in height must be approved by the local authority or evaluated by
an engineer.Backfill may consist of engineered fill,as presented in this report,or borrow
material approved by a geotechnical engineer. Compaction of these materials shall be
achieved in compacted lifts of about 12 inches. Each lift should be uniformly compacted
to at least 85%, and no more than 90% of the modified Proctor maximum dry density
(ASTM D 1557).If pavement or building loads are planned to be located within retaining
wall backfill, then 90% compaction is required. In addition, heavy construction
equipment should be at a distance of at least V2 the wall height. Over-compaction and
limiting heavy construction equipment should be prevented to minimize the risk of excess
lateral earth pressure on the retaining structure. Envirotech recommends that retaining
wall backfill is compacted with light equipment such as a hand-held power tamper. If
clean,coarse gravel soils are utilized as engineered fill,and surcharges will not influence
the retaining wall, compaction may be achieved by reasonably densifying granular soils
with construction equipment.
5.2.4 Wet Weather Considerations
Due to the types of subsurface soils, additional provisions may be required during
prolonged wet weather. Every precaution should be made in order to prevent free
moisture from saturating the soils within excavations. If the bottom of excavations used
for footing placement changes from a moist and dense/hard characteristic as presented in
this report to muck or soft, saturated conditions, then these soils become unsuitable for
foundation bearing material. If this situation occurs, a geotechnical engineer should be
notified, and these soils should be completely removed and replaced with compacted
engineered fill or suitable native material as presented in this section.
5.2.5 Building Pads
Building pads for this project, if utilized, shall be constructed per the fill placement and
compaction recommendations as presented above. Both engineered fill and native soils
may be used for building pads. Building pad slopes shall be no steeper than 2:1 for both
compacted engineered fill and re-compacted native soils used as fill. Building pad fill
shall be"keyed"into the existing subgrade to a depth of at least 2 feet below the existing
ground surface. The term "keyed," as used here, implies that the interface between the
building pad and subgrade is horizontally level. Alternatively, building pads may be
keyed into the subgrade to the above specified depth,and stepped. Stepped fill should be
keyed into the subgrade at a minimum width of 10 feet. All footings shall be located at
least 5 feet away from the top of the engineered fill slope.
5.3 Building and Footing Setbacks
Provided that assumptions relating to construction occur and recommendations are followed as
presented in this report, the factor of safety for slope stability is sufficient for a 50 feet footing
Envirotech Engineering Geotechnical Report
PO Box 984 page 16 Parcel 12330-54-00013
Betfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
setback from the face of the nearby descending slopes exceeding 40%. See the figure below and
the Site Plan in Appendix A for an illustration of the setbacks.
STRUCTURE
TOP OF
SLOPE SLOPE
FACE
i ILI—I I '
SETBACK FOOTING
From the illustration above, structures may be located closer to the top of slope by extending the
foundation deep enough to maintain the recommended setback.In addition, the required setback
may be reduced by mitigation, and subsequently would require additional geotechnical studies.
Decks and septic drainfields may encroach the setbacks up to the vegetated buffer provided in
this report.
5.4 Surface and Subsurface Dr
ainage
Positive drainage should be provided in the final design for all planned residential buildings.
Drainage shall include sloping the ground surface, driveways and sidewalks away from the
project structures. All constructed surface and subsurface drains should be adequately maintained
during the life of the structure. If drainage problems occur during or after construction,additional
engineered water mitigation will be required immediately. This may include a combination of
swales,berms,drain pipes,infiltration facilities,or outlet protection in order to divert water away
from the structures to an appropriate protected discharge area. Leakage of water pipes, both
drainage and supply lines,shall be prevented at all times.
If impervious thresholds are exceeded per the prevailing agency code, then engineered
stormwater management plans are required for this project. The drainage engineer must
coordinate with a geotechnical engineer for input with relation to slope stability prior to
submitting drainage plans. If stormwater management plans are not required for this project,then
the following recommendations should be followed.
For this project, we recommend that infiltration is avoided in order to maintain slope stability,
and that roof downspout dispersion on splash blocks are employed. Recommended drainage
details are provided in Appendix E of this report.
5.5 Vegetation Buffer and Considerations
For this project, we believe that a detailed clearing and grading plan is not warranted unless the
prevailing agency thresholds are exceeded, and basic vegetation management practices should be
adhered to.
Vegetation Buffer—Vegetation shall not be removed from the face of the critical slope or within
a distance of 10 feet beyond the top of the slope. However, any tree deemed hazardous to life or
Envirotech Engineering Geotechnical Report
PO Box 984 page 17 Parcel 12330-54-00013
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
property shall be removed. If tree removal is necessary, then stumps and roots shall remain in
place, and the underbrush and soil shall remain undisturbed as much as possible. Any disturbed
soil shall be graded and re-compacted in order to restore the terrain similar to preexisting
conditions and drainage patterns.See the Site Plan in Appendix A of this report for a depiction of
the vegetation buffer.
5.6 Temporary and Permanent Erosion Control
Erosion control during construction should include minimizing the removal of vegetation to the
least extent possible. Erosion control measures during construction may include stockpiling
cleared vegetation, silt fencing, intercepting swales, berms, straw bales, plastic cover or other
standard controls. Although other controls may be used, if adequate, silt fencing is presented in
this report as the first choice for temporary erosion control.Any erosion control should be located
down-slope and beyond the limits of construction and clearing of vegetation where surface water
is expected to flow. If the loss of sediments appears to be greater than expected, or erosion
control measures are not functioning as needed, additional measures must be implemented
immediately. See Appendix D for sketches and general notes regarding selected erosion control
measures. The Site Plan in Appendix A depicts the recommended locations for erosion control
facilities to be installed as necessary.
Permanent erosion control is necessary if substantial vegetation has not been established within
disturbed areas upon completion of the project.Temporary erosion control should remain in place
until permanent erosion control has been established. Permanent erosion control may include
promoting the growth of vegetation within the exposed areas by mulching, seeding or an
equivalent measure. Selected recommendations for permanent erosion control are provided in
Appendix D. Additional erosion control measures that should be performed include routine
maintenance and replacement, when necessary, of permanent erosion control, vegetation,
drainage structures and/or features.
5.7 Septic Drainfields
Septic drainfields were considered in our geotechnical evaluation.This includes septic drainfields
with relation to the observed soil conditions, expected vegetation removal, and existing and
proposed topography. Based on the aforesaid parameters, the septic drainfields are not expected
to adversely influence critical slopes.This is also based on compliance with all recommendations
in this report.
5.8 Structural Mitigation
With respect to landslide alleviation or slope improvements, structural mitigation is not necessary
for this project. This determination is based on the anticipated improvements of the project,
engineering conclusions,and compliance with all recommendations provided in this report.
Envirotech Engineering Geotechnical Report
PO Box 984 page 18 Parcel 12330-54-00013
Belfair.Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
6.0 CLOSURE
Based on the project information provided by the owner, the proposed development, and site
conditions as presented in this report, it is Envirotech's opinion that additional geotechnical
studies are not required to further evaluate this project.
Due to the inherent natural variations of the soil stratification and the nature of the geotechnical
subsurface exploration, there is always a possibility that soil conditions encountered during
construction are different than those described in this report. It is not recommended that a
qualified engineer performs a site inspection during earthwork construction unless fill soils will
influence the impending foundation.However,if native,undisturbed subsurface conditions found
on-site are not as presented in this report,then a geotechnical engineer should be consulted.
This report presents geotechnical design guidelines, and is intended only for the owner, or
owners' representative, and location of project described herein.This report should not be used to
dictate construction procedures or relieve the contractor of his responsibility.
Any and all content of this geotechnical report is only valid in conjunction with the compliance of
all recommendations provided in this report. Semantics throughout this report such as `shall,'
`should' and `recommended' imply that the correlating design and/or specifications must be
adhered to in order to potentially protect life and/ or property. Semantics such as `suggested' or
`optional' refer that the associated design or specification may or may not be performed, but is
performance. The recommendations provided in this report are valid for the
provided for optimal pe p
proposed development at the issuance date of this report. Changes to the site other than the
expected development, changes to neighboring properties, changes to ordinances or regulatory
codes, or broadening of accepted geotechnical standards may affect the long-term conclusions
and recommendations of this report.
The services described in this report were prepared under the responsible charge of Michael
Staten, a professional engineer with Envirotech. Michael Staten has appropriate education and
experience in the field of geotechnical engineering in order to assess landslide hazards,
earthquake hazards,and general soil mechanics.
Please contact Michael Staten at 360-275-9374 if you have any questions, comments, or require
additional information.
Sincerely,
Envirotech Engineering
Jessica Smith,M.S. Michael Staten,P.E.
Staff Geologist Geotechnical Engineer
Envirotech Engineering Geotechnical Report
PO Box 984 page 19 Parcel 12330-54-00013
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 8,2020
APPENDIX A
SITE PLAN
SCALE. 1 INCH a 100 FEET
l00
�0 FT CONSTRUCTION
SETBACK FROM TOP
OF CRITICAL SLOPE IADVALNr
10 FY VEGETATION REMOVAL
BUFF/ER FROM TOP ff
CRITICAL SLOPE
� v
V
1 > 4 -f A .w
A-1 a
TP 6 % I10
M TB►v
41D:
PROPERTY LINE
OUTLINE Or•�••�
PRM=I/OWNER/ LOCATION-
L L009MN C04TIR NAT BE REQUIRED FOR THIS SITE,GENERAL LOCATIONS SINGLE FAMILY RESIDENCE
Awe DEPICTED,NO ALTE"TIVES KAY BE UTILIZED AS EXPLAINED IN THE GEOTECHNICAL REPORT
DEOTECHNIINAL REf w-
G CWTOk *VE1E NUT PREPARED BY A LICENSED LAND SURVEYOR. fOD�E717
CMMUS VM 0MtAPOLATEj FROM A PUBLIC LIDAR SOURCE, AND 10 1E AWRAL DRIVE
DICOIPOIMTED FM"BEMILIRO ITS AS EXPLAINED IN THE C£ATECHNICAL LEGEND PABl1.EL 1030-5/-00013
BQM'TL TY WA
3 BdRmAIM WEBF MOT PREPARED BY A LICENSED SURVEYOR. LOCATIONS TEMPORARY EI40EE1B
OF SITE F AIUM THAT ARE SNOWN HERE, SUCH AS TOP OF SLOPES, TOE ++ -EROSION CONTR0. ENVE1QTE(H ENGINEERING
OF 7LOOPEf,WATETN FFATUIRM ETC- WITH RELATION TO THE PROPERTY 904
LI ES MAY IE%-Cor=SIT THE OWNER. RECOMMENDATIONS IN THE - SLOPE INDICATOR � ASHINGTON 98328
GE¢TECHKM&IEPW PIOVIOE SETBACKS, BUFFERS. DEPTHS. ETC. WITH 74
RELATION TO GCOILOW FFATUES, NOT PROPERTY LINES.THESE GEOLOGIC 80 EXISTING CONTOUR
��SN r NEL=ATCO OR THE SUBJECT PROPERTY OR NEIGHBORING TPIj@ TEST PIT SITE PLAN
APPENDIX B
SOIL INFORMATION
VERTICAL MI 1a1SDNTAL SCALE-
SCALE, 1 INCH 60 FEET
PROPOSED
HOUSE
MEDIUM DENSE SILTY SAND
WITH GRAVEL (SM)
14;1*
2
3�t
21it 3/= EXISTING GRAnf
1y�r
1
POORLY GRADED SAND (SP)
SECTION A-A
PALKCT/ OWNER/ LOCATION,
SUWjLE FAMILY RESIDENCE
GEOTECHNICAL REPORT
BD Mt3Y
PAKEL UtM-54-00013
%0M COINTY, WASHINGTON
NOTES
ENMNEElB
U MINOR GRADE CHANGES REQUIRED IN ORDER TO ACHIEVE EfA UMECH ENGINEERING
POSITIVE DRAINAGE MO$CAI no
2) THE SOIL PRCf'ILE IS ACCURATE FOR THE DEPTH 13F SE9EL OL WS INGTON 98528
THE OBSERVED TEST PITS AT THE SPECIFIED LOCATIONS.
LOVER DEPTHS ARE BASED ON SITE GEOLOGY,
WELL LOG., AND/OR EXPERIENCE IN THE GENERAL AREA S❑IL PROFILE
TEST PIT LOG
TEST PIT NUMBER TP-1
PROJECT: Kennedy Geotechnical Report DATE OF LOG: 8/18/2020
PROJECT NO: 20139 LOGGED BY: MCS
CLIENT: Kyle Kennedy EXCAVATOR: N/A
LOCATION: 151 NE Admiral Drive DRILL RIG: None
Mason County,Washington ELEVATION: N/A
INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: WA
STANDARD PENETRATION TEST
SOIL STRATA
DEPTH SAMPLERS USCS DESCRIPTION LL PI CURVE
AND TEST DATA DEPTH N 10 30 50
0 SM Medium Wows,mist,medium dense
SILTY SAND with GRAVEL.Gravel is
prmar y vmN-graded and subrounded.
t Sand is mostly medium.No plasticity.
z
SP Poorly graded SAND with GRAVEL and
traces of SILT.No plasticity.
3
4
5
6 -
7
Excavation terminated at approximately 7
feet
8
9
10
No Groundwater Encountered ENVIROTECH ENGINEERING
Tars n*mwbw Pertains only to ft bang and should nor be Geotechnlcal Engineenng
rnbMrekd as berg Nxkdw of ft entire so
Map Und Description Everett gravelly loamy sand.5 to 15 percent slopes—Mason County.
Washington
Mason County, Washington
Ee—Everett gravelly loamy sand, 5 to 15 percent slopes
Map Unit Setting
National map unit symbol 2hk7
Elevation 50 to 500 feet
A4ean annual precipitation 55 to 90 inches
Mean annual air temperature 48 to 50 degrees F
Frost-free period 160 to 180 days
Farmland classification Farmland of statewide importance
Map Unit Composition
Everett and similar soils 100 percent
Estimates are based on observations,descriptions,and transacts of
the nhapunit
Description of Everett
Setting
Lanclform Terraces
Parent material Glacial outwash
Typical profile
H I-0 to 7 inches gravelly ashy loamy sand
H2-7 to 21 inches extremely gravelly sand
H3-21 to 60 inches very gravelly sand
Properties and qualities
Slope 5 to 15 percent
Depth to restrictive feature:More than 80 inches
Drainage class Somewhat excessively drained
Capacity of the most limiting layer to transmit water(Ksat) High to
very high(5 95 to 19 98 infhr)
Depth to water table More than 80 inches
Frequency of flooding None
Frequency of ponding None
Available water capacity Very low(about 2 5 inches)
Interpretive groups
Land capability classification(irngated) None specified
Land capability classification(nonirrigated) 4s
Hydrologic Soil Group A
Forage suitability group Droughty Soils(0002XN402WA)
Other vegetative classification Droughty Soils(G002XN402WA)
Hydric soil rating No
Data Source Information
Soil Survey Area Reason County,Washington
Survey Area Data Version 16,Jun 4,2020
"U,% Natural Resources Web Sal Survey 9,712020
iOW Conservation Service National Cooperatrve Sal Survey Page I of I
FM_ �""" WATER WELL REPORT °'„ ,o"-lw7 tad
TAed COW 00aft M copy-0.mft Cow STATE OF WASHINGtON �
Wabsr Psnnfl No
M ONKM Name ROD-nnat _ Addraa p0im wA Mll�S
(3)LOCATM OF VIEW Otter MASON _NE-iM_jam( tM Sac_IL T._n KA lU wM
Ib)$TAT ADDRESS OF WELL nww adswo rra�a�etaRrwt�tr RD
TAX PARCEL NO. t2&112nft Q - --------.
(3)PROPOSED USE: 1] Bert a C11-WI Qmulldpr (10)WELL LOG or DECOWASSIONIN(I PROCEDILM OEfCRlIWIk
is& C Test wee ❑Other m TriononOM aradw.araar.rs a nAdwr *.*,Mere ar rind-0
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Dorn from_ too-_ R BROyyj)CEMEMM SAND GRAVEL AND C
prlaaraae OYM w►b BROWN CEMENTED CLAY AND f3RAYE1
71
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waft Iwr 2d0 R brow top or wee Dab yaSM& WELL CON9TRUCT)ON CERTIFICATION:
NOMM Praalka ea Ow square v)CP Date Icandmom NW r woepw respwwbtkty for corrardon of ara word,so Ita
Arbwrtwaltris by cooflW uft,dwasnirgMwN on lconSruCbrarlQarI bA I I ISO
CUMa��— MO M Ybarllae reported above are true to my best knomedge and b"
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A&W gelAnln*a seem atat a our_ Ira Eodogy rs an Equal opportunity and AtBmma6ra Action empbyer. For
Arft M bw q.dm. Da*4MSCR14 special accommodation needs,contact the Waller Resources Program at
Tempomweahrew waaadtwNwartryaanwdaz QYa®tore (360)407-6600 The Too number is(360)407-60%.
APPENDIX C
SLOPE STABILITY
1 . O 0
1 . 1 O
1 . 2 0
1 . 3 O
1 . 4 0
1 . 5 0
1 . 60
1 70
80
1 . 0
�2 . 0
O . 729
Proj act Kanrxady Report
D a t a f 1 1 a D y n a m i c A n a l y s i s
Analysis _ Bishop
erw�a.c.-xooz rz �u.oai.e.. zea
1 . O 0
1 . 1 0
1 . 2 0
1 . 30
1 . 4 0
1 . 50
1 _ 6 0
L 7 0
_ 80
l . 0 0
_ 097
Praj E+ct Kaririedy Report
L�atafila Static Analysis
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APPENDIX D
EROSION CONTROL
GEOTEXTILE FABRIC
WRAP AROUND TRENCH
TO AT LEAST ENTIRE
BOTTOM OF TRENC4TRENCH
BEFORE PLACING 2'x2'x5' WDOD POST OR
12' DEEP, 8' WIDEQUIVALENT OR BETTER
FILLED WITH 3/4WASHED GRAVEL za�rIliRECTION OF EXISTINGWATER FLOVGRERJND SURFACE
vrtJ-
SILT FENCE - CROSS SECTION
N.T.S.
2'x2' WOOD POST (TYP) GEOTEXTILE FABRIC
OR EQUIVALENT OR BETTER AND WIRE MESH
2 6 FT MAX. O.C.
G R-� r �A R
EXISTING rl
r -L
GROUND SURFACE
e
la- DEEP, 8• WIIIE
1 rr
TRENCH lLJLED WITH as Fr
WASHED GRAVEL OR VE TI
BOTTOM EXTENTS OF
GEOTEXTILE FABRIC SILT FENCE - DETAIL
N.T.S.
PROVIDE FULL WIDTH
3/4 IN TO 1 1/ N�C FT r INGRESS/EGRESS
CRUSHED GRAVEL
PLACED AT 6 IN
MINIMUM DEPTH
WELL-DRAINED
SOILS
-0.02 IN/MIN FULL LEWTH
R=25 FT MIN
access konn
STABILIZED CONSTRUCTION ENTRANCE
N.T.S.
S+W%NEHT EMISSION:AHTIWL 90TE9
LSN
SHF.Dm FEW RCv SLOPES
33QL2 THE TEWOMI T MEOW ACID KETI NIENT fUITQDL WAliAM-MU"ON
Man PHO+tE TD E BbmauliTY"ON.L ONATNLR,TDN.THE GOITAmmm L JEFIM SEA,Iio'TALL HWU SWIF1 E IILMT CURTWL
M4ALL ABII EONAL MOM 00 SE]OIENT CONT111]L FAt7_IT11M IEAOIINEs ELM E COMMIT T[ORMi.11TENOEFTElt IMM
ALL.EAODDf AIO SIMINIT COITIR FA Xm A!I IEVICEM SHALL BE SVIALM LEVEL WILAWM AO BMW IMOOL
YMMLY NO WINATELY WATAIDEI,7 IECESURY. OS TIE mm 10 SHILL ME rw WITH►ARlLT F11C SUFACJE.
ALL[ROi>si Nab SEEEp(DIT=TML►AC3RBES AO[EVLZ.9 ZHALL E LEFT N FO!"31116 SIIIFACE MID93 i.FEI[F1111 ALL OPEMATat AMIOSI
tD1TR THE L7MS M AAE-AS HAVE NIX PE NOWDITLY STAIO.REi Q rCPvNINICUEAR TO IHIE.SLOPE.
Z SRO IEEMVMTU44 NM*1010 MOW.ANNE SHIELD BE
t lmCM1L TE11E1H IFPLtI AT THEE TMTE Or 1113►I M PER AM
HAVE
4>®1Fa RJBDO L'TIIEED HEAT i MO QTiJIi i VD.L
ALL ATEAI VHITF�I Am YNE E MO i� 1m IQ AIRCTrATERm YM at m A FUITIOI 00 IWTXCT IHE UW XMICI G At 1 TO
FaLEO0B6 THE Lx=0uMm Q1V,ALL IMHD=n AmiaII WEST= S SINS>O!1 LMM BETWEEN OIVIE111111t I ON WILL.31%
T 1iAiL12151 WITH MIAOB OW RIINYIO DR np ARIE1p0 OF flE WO>E'2 VIIl.>E/ElZ.'iSART.Ogg•
tOMTftd THE►11L"IT NPLlf ll[TO THE TOE OF Tt/Yt cw 90211MFLES,.ACE MAT.GEAR MASTIC COVE M@ik
V]LL OIL!BE ACIIPTMU 0"6 THE HlO TW DE APRIL THINOM i.FERTL3Z RY ARE TO BE LIED ACCEIMM TO SIMPLIEW
muvvvER, BEXIOW HRY mi ED*)HEWED 17 1S IN TFE IkjwKFr Or 111=9111OATa1L MATS%NmLI BE 1lOtCl.ED.may'V
NIrER/COITTACTTR.BOUT UST ALTO BE AJOIE)M WITH HALO LNG,EETTIG ADJACENT TI VATBR 70IpES as VCTLA06.
OiHQt A"PROVCI TWATPEBIT.
USE THE E'OJ.WIE JFOO[Bil[D go DDMrJ1E r'1Bt BIB!
1 SEASOPI(MAY I THRU SEPTEMBER XD— TW CLEARING OF LAND.IKLUU45 THE CONTROL ON A MOM APPROVEC ALTERVAATE SEED MIXTURE
VAL DE rxislImG vC(BTATWW OR WHIV?GROUND COVER,RUST BE LIMITED TO
Y AS MJCH LAND AS CAN RECEIVE APPROPRIATE PROTECTIVE COVER OR E PROPDRTIIBLS PURITY GERNINA
STABIUME, AFTER MAVDNG BEEN CLEAREI OR OTHERWISE DISTURED . NAME BY vLtGNTCID (ICI c4)
Y HD LATER THAN SEPTEMBER 30 IF A GIVEN YEAR,UNLESS IMMEDIATE
aBILIZATIEN IS SPECIFIED IN THE EROSION AND SEDD(E%T Ca4TRL PLAN. ALL REDTOP(AGROSTIS AL W :D 92 9J
CLEARED OR OTHERWISE DIS7MBED MUST BE APPROPRIATELY STABILIZED ANNUAL RYE(LLLIIN MLTFLORUM) 40 98 90
THE USE OF MULCHING, NETTING,PLASTIC SHEETING,EREIS04 BLANKETS. CHEWING FESRE 40 97 DO
DRAINING MATERIAL ETC.. BY SEPTEMBER 30 OR SOONER PER THE APPROVED (FESTUCA RUBRA COMMUTATA)
OF ACTIN. UNLESS CnHERWtSE APPROVED BY THE COUNTY, SEEDING, (JAMESTOWN.BAKER.SHADOW, KOcET)
TIUZING AND MULCHING DE CLEARED 13R OTHERWISE DIST(URIE B AREAS SWILL BE WHITE DUTCH CLOVER 10 96 90
NED DURING THE FOLLOWING PERIODS,MARCH 1 TO MAY 15,AND AUGUST 15 TO (TRIFLIUM REPENS)
TODER
L SEEDING AFTER OCTOBER 1 WILL BE DOE WHEN PHYSICAL COPLET33N
THE PROJECT IS DGNI ENT AND THE ENVDRU ENTAL CONDITIONS ARE CONDUCIVE MULCHING
SATISFACTORY GROWTH. IN THE EVENT THAT PERAN£HT STABISZATBON LS HOT
SIRE,AN ALTERNATIVE METHOD OF GROUND COVER, SUCH AS MULCHONC,NETTING,L MATERIALS USED rtR MULCHING ARE RECOMMENDED TO BE WOOD
TIC SHEETING,EROSION BLANKETS,ETC.,MUST E INSTALLED BY NO LATER THAN FIBER CELLULOSE,AND SHOULD BE APPLIED AT A RATE 13F LOW
ER 30. POUNDS ER ACRE.
y�S MU BE APPLJED IM ALL AREAS WITH EXPOSED SLOPES
1{E LMMI 701 COMMILLTIBN AALT].VITIM M 00ER SITE IIEVELEPNM ONZATI"a TEEN m
MBE 2tlCMaT4 EL FOR AT LEAST 4 COMCJTIVE OATS.THE i ORLMM SHOED E WEED I9l3ATELT AFTER BEEDINE DE A
TO SDBRLL BE REIPOMIMILC FOR THE DWWIM ff ALL 1011OSSOI AEA{VM H CADS E SEEM IECAJiE OF THE HEVAC L ALL
SE NET CON 11O. FALTLIM D/KEAIELY AFTER DITI1Ni EWLRr1.AM AT AEVM j13LOpDO RAM SHILL WE COVEXIED r HDVEMJrR L
O=EVERY WEER.TIE 01 ww Ip1T1irc7m SHALL E RE]PRMI[i8 FOR
HHA10k MMM AM WA1R W ALL EStDI AN SE MOM CO(TILL FACL.HES Turom w 6
SEASON mCTmOt t TMI U AAFOM �.M 90—IDE SITES 1AfSE LOUVrFSQ7"TE7S. ' �E�IN=PAO.ECT OBE To HSItY
�CTIOH[ACTIVITY M AH CLEAARSNG OF LAIM DELUXIM THE
As ABHC i NIMD AR�►�g 00 OEM OR aft YTANII-WS1 COVER, ` HOO11�71 8 WTF&M 3}OULD r PLJILED ON slJi>'EE LZ E ILL EML J
EVQ(i A ma.AR SWOM IS L�1E0 ADW III FSMUM AND SEM4ENT F 'AND SOEL= OG ON$STOP SILLY Q-W( 111A E
[>rr-311E A ImERVE7t H SILT
L Et IF MBOO.it AIL M L LOAMIK(LO11(,SNiDT LOOK
ILO tOPIP &MOT CLAY LOAM.COAT THE
QF/1 ON AOTNRJ[1 AWJ4�I�ZCEIVyEE AP'PN24MTE PPIOTW 7VE 4 n&n SHALL E M Xm TD THE 1ZDESBATE 0L4T10IGTBOH
ON 1E OT1OVlE IITAiOLOEL BE K lIL1Sb1L It7T11T.R..NIRT6 'iA1.A FOw 70 ftOl DI71 ITTEJI'OT3 ILTH DC BON.BLPf
EROImT O.AIMM FIE[ MILTEOAL ETC.VMW 0 OTS A►RI SlTH H pEppImT TIRRT Mgnn t a THE P SHALL AE l34 P ALL
EOI CLEAM Q ClIFEIVOE]OWL11010 IF NOT Hai ACTIVELT VOIEI. �m CONTROL S71I>rTJRES SILL>E N PI1tCL ONE]17RE
T FTEIC'DRG,SEDIMENT TRAPS,SEDUIENT PONDS,ETC..WILL DOT E VIEWED AS
TE COVER IN AND 13F THENSELVES.IN THE EVENT THAT ANY LAND AREA NOT
ACTIVELY WORKED REMAINS UNPROTECTED OR HAS NOT KEN APPROPRIATELY
ARRIZED 5 DAYS AFTER HAVING BEEN CLEARED,AL CONSTRUCTION ACTIVITY ON
SITE,EXCEPT FOR APPROVED EROSION AND SEDIMENT CONTROL ACTIVITY,SHALL
DIATELY CEASE UNTIL SUCH A TIME AS AFOREMENTIDEO LAND AREA HAS BEEN
PROPRIATELY PROTECTED OR STABILIZED.
STOCKPBE MANAGEMENT
STQCKPD.E SMALL lE STARR*=(VITA PLASTIC COVERING OR OTHER APPROVED DEVICE) DAILY D TJEEN NCIVEMKR 1 AND MARCH
3LN ANY SEASON,SEDIMENT LEA*"rROM STOCK PEES MUST BE PREVEMTEL
3.TOPS[BL SHALL NOT BE PLACED WHILE N A FROZEN OR MUDDY CONDITION.MEIN THE SUDGRACE IS rxCESSIvELY VET.OR WHEN
CONDITIONS EXIST THAT MAY OOiJRW1SE BE IETRIIENTAL TO PROPER GRADING OR PPO°DSED SODDING DR SEEDING.
.ikW; L?GTADL0IEB QMmicI ON THE ARZMB TO BE 704ME LB TIA.L BE KWTADED A^*.[G¢i'.M THE ArY60WED M.AIC.
islllEtT31311 EBITMAME
I AICMAL SHALL E 4 IOC TO w DIOR QL AW1 SPALLE(4 TO NL BiC H FIX PESO:EtITIAL SV ME FARO.Y LOTS}AND HAY BE
VLIH 1 IM>♦1 TO S IIOH MM(STATE-TAVPM SPFLIFICATI[t4t:. SELTIDt{N-M.)
THE NOOK PINY SMALL BE AT LEAST M DOES THICK AM 20 FEET LOW 4W FEET FOR SITE& WITH LM T" L MUM OF
DISTURBED SOLT.WIDTH SMALL E FLU WIDTH OF THE VEHICLE INGRESS An EGRESS AREA.SAALLER PADS MAY BE APPROVED
FOR SDNGI E-FAMILY RESIDENTIAL AND SMALL CD0ERCIAL SITES.
3.ADDITIONAL ROCK SHALL E ADDED PERIODICALLY TO MAINTAIN PROPER FUNCTION [F THE PAD,
4.IF THE PAD DUDES NOT ADEQUATELY REMOVE THE HUD FROM THE VEHICLE WHEELS,THE WHEELS SMALL BE HOSED Er BEFORE
11E VEIBCLF ENTERS A PAVED STREET.THE WASHING SHALL E DOE ON AN AREA COVERED WITH CRUSTED ROCK AND WASH
WATER STALL DRAM TO A SEDIMENT RETENTION FACILITY OR THROUGH A SILT FENCE.
LLT FORCE
GEUTfRD.E FILTER FABRIC TYPE SMALL E I"SPECIrEC IN THE'STORDWATER Di4NAGE ENT MANUAL
THE PUM:r SLTAM BA=M: OR APPLIFARE CONTY STANDARDS
.GEUTEXTO.E FELYM►AMM SMALL E PLRCHA30 IN A CT/TMIDUS ROM.CUT TO THE LENGTH OF
SAMOCK TO AVOID USE OF JOINTS,IF JOINTS ARE NECESSARY,FILTER FABR(-- SHALL E SPLSSD
DIY AT A SUPPORT POST WITH A MPO"6-INCH OVC9LAP AND SECUPEIY FASTENED AT
ENO TO TIE POST.
STANDgRII ILTE1t rABR¢MOLL BE FASTENED NOSING Y STAPLES OR TIE WIRES(HOC PASS)P 4 IN
RNM SHALL BE SEWED AND PLACED AT DEFT MS INDICATED IN THE DETAILS ON THIS SHEET. AND
S`ECLOELY ONTO THE FBOA(O.
WINE MESH SHALL E eX2'XL4 GAUGE HR EQlUIVLENT.THE WILE MESH MAY E ELIMINATED IF
TRA-STRENGTH FILTER FABRIC oONffLAMENT,AND CLOSER POST SPACING IS USED,
.A TRENCH SHALL E rXCAVATED ACCORDING TO THE DUALS ON INNS SHEET ALONG THE LURE ff THE
TS AND UPSIJPE FROM THE SILT FENCE
.SO_T rENCES SHAM E LOCATED DOVNSLOPE FROM THE CLEARING L.D41TS OF THE PROJECT.
APPENDIX D
DRAINAGE DETAILS
HOUSE
ROOF DOWNSPOUT
SERVES UP TO
700 SF OF ROOF
SO FT MIN
VEGETATED
FLOW PATH
DOWNSPOUT
EXTENSION
ROOF DOWNSPOUT AND SPLASH BLOCK DETAILS
N.T.S.
II I
II