HomeMy WebLinkAboutGEO2019-00091 BLD2019-01290 - BLD Engineering / Geo-tech Reports - 5/31/2019 ZoIR -,61a90 RECEIVED
AUG 2 7 2019
615 W. Alder Street
Geotechnical Report
Funk Single Family Residence
460 E Stretch Island Rd S, Grapeview
Parcel No. 12108-42-00050
Mason County, Washington
May 31, 2019
Project#1999
Prepared For:
Patty Funk
PO Box 693
Grapeview, Washington 98546
Prepared By:
Envirotech Engineering
PO Box 984
Belfair, Washington 98528
Phone: 360-275-9374
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5/3l/19
MASON COUNTY ;ubmitfal Checklisl
COMMUNITY SERVICES Geotechnical Report
Instructions:
This checklist must be submitted with a Geotechnical Report and completed, signed, and stamped by the licensed
professional($)who prepared the Geotechnical Report for review by Mason County pursuant to the Mason County
Resource Ordinance. If an item is found not applicable, the report should explain the basis for the conclusion.
Note: Unless specifically documented, this report does not provide compliance to the International Residential Code
Sections R403.1.7 for foundations on or adjacent to slopes, Section R403.1.8 for expansive soils or section 1808.7 1
of the International Building Code Section for Foundations on or adjacent to slopes.
Applicant/Owner Patricia Funk Parcel# 12108-42-00050
Site Address 460 E Stretch Island Rd S Grapeview ---
(1) (a) A discussion of general geologic conditions in the vicinity of the proposed development,
Located on page(s) 5
(b) A discussion of specific soil types,
Located on page(s) 5-6
(c) A discussion of ground water conditions,
Located on page(s) 7
(d) A discussion of the upslope geomorphology,
Located on page(s) 3
(e) A discussion of the location of upland waterbodies and wetlands,
Located on page(s) 3
(f) A discussion of history of landslide activity in the vicinity, as available in the referenced maps and
records.
Located on page(s) 11
(2) A site plan which identifies the important development and geologic features.
Located on Map(s) Site Plan—Appendix A
(3) Locations and logs of exploratory holes or probes.
Located on Map(s) Site Plan and Soil Logs (Appendix B)
(4) The area of the proposed development,the boundaries of the hazard, and associated buffers and
setbacks shall be delineated(top, both sides, and toe)on a geologic map of the site.
Located on Map(s) Site Plan
(5) A minimum of one cross section at a scale which adequately depicts the subsurface profile, and
which incorporates the details of proposed grade changes.
Located on Map(s) Soil Profile(Appendix B)
(6) A description and results of slope stability analyses performed for both static and seismic loading
conditions. Analysis should examine worst case failures. The analysis should include the Simplified
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.
Located on page(s) 9 Page 1 of 40
4
(7) (a) Appropriate restrictions on placement of drainage features,
Located on page(s) 17
(b) Appropriate restrictions on placement of septic drain fields,
Located on page(s) 18
(c) Appropriate restrictions on placement of compacted fills and footings,
Located on page(s) 14-15
(d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other slopes.
Located on page(s) 16-17
(e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of other slopes.
Located on page(s) 16-17
(8) Recommendations for the preparation of a detailed clearing and grading plan which specifically identifies
vegetation to be removed, a schedule for vegetation removal and replanting, and the method of vegetation
removal.
Located on page(s) 17 _
(9) Recommendations for the preparation of a detailed temporary erosion control plan which identifies the specific
mitigating measures to be implemented during construction to protect the slope from erosion, landslides and
harmful construction methods.
Located on page(s) 10
(10) An analysis of both on-site and off-site impacts of the proposed development.
Located on page(s) 12
(11) Specifications of final development conditions such as, vegetative management, drainage, erosion control, and
buffer widths.
Located on page(s) 17- 18
(12) Recommendations for the preparation of structural mitigation or details of other proposed mitigation.
Located on page(s) 18
(13) A site map drawn to scale showing the property boundaries, scale, north arrow, and the location and nature
of existing and proposed development on the site.
Located on Map(s) Site Plan
I, Michael Staten, hereby certify under penalty of perjury that I am a civil engineer licensed in the State of Washington
with specialized knowledge of geotechnical/geological engineering or a geologist or engineering geologist licensed in
the State of Washington with special knowledge of the local conditions. I also certify that the Geotechnical
CLY 9T Report, dated May 31, 2019, and entitled Funk Single Family
'V��^����1. '>>� Residence, meets all the requirements of the Mason County
Resource Ordinance, Geologically Hazardous Areas Section,
is complete and true, that the assessment demonstrates
43045 conclusively that the risks posed by the landslide hazard can
\ALF�` be mitigated through the included geotechnical design
j )9 recommendations, and that all hazards are mitigated in such a
Disclaimer: Mason County does not manner as to prevent harm to property and public health and
certify the quality of the work done in safety.
this Geotechnical Report.
Page 2 of 2
TABLE OF CONTENTS
1.0 INTRODUCTION.................................................................................................................................I
1.1 PROJECT INFORMATION..................................................................................................................... 1
1.2 PURPOSE OF INVESTIGATION AND SCOPE OF WORK......................................................................... 1
2.0 SURFACE CONDITIONS....................................................................................................................3
2.1 GENERAL OBSERVATIONS..................................................................................................................3
2.2 TOPOGRAPHY......................................................................................................................................3
2.Z.1 Upslope Geomorphology............................................................................................................3
2.3 SURFACE DRAINAGE...........................................................................................................................3
2.3.1 Upslope Water Bodies.................................................................................................................3
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.................................................................................................6
3.3.1 Groundwater............................................................................................................................... 7
4.0 ENGINEERING ANALYSES AND CONCLUSIONS.......................................................................8
4.1 SLOPE STABILITY...............................................................................................................................8
4.1.1 Slope Stability Analysis..............................................................................................................9
4.2 EROSION............................................................................................................................................10
4.2.1 Shoreline Recession.................................................................................................................. 10
4.3 SEISMIC CONSIDERATIONS AND LIQUEFACTION.............................................................................11
4.3.1 Liquefaction.............................................................................................................................. 11
4.4 LANDSLIDE,EROSION AND SEISMIC HAZARDS CONCLUSIONS....................................................... 11
4.5 LATERAL EARTH PRESSURES........................................................................................................... 11
4.6 ON-SITE AND OFF-SITE IMPACTS....................................................................................................12
5.1 BUILDING FOUNDATION RECOMMENDATIONS................................................................................13
5.1.1 Bearing Capacity...................................................................................................................... 13
5.1.2 Settlement................................................................................................................................. 14
5.1.3 Concrete Slabs-on-Grade......................................................................................................... 14
5.2 EARTHWORK CONSTRUCTION RECOMMENDATIONS...................................................................... 14
5.2.1 Excavation................................................................................................................................ 14
5.Z.2 Placement and Compaction of Native Soils and Engineered Fill........................................... 14
5.2.3 Retaining Wall Backfill............................................................................................................ 15
5.2.4 Wet Weather Considerations....................................................................................................16
5.2.5 Building Pads........................................................................................................................... 16
5.3 BUILDING AND FOOTING SETBACKS................................................................................................ 16
5.4 SURFACE AND SUBSURFACE DRAINAGE........................................................................................... 17
5.5 VEGETATION BUFFER AND CONSIDERATIONS................................................................................. 17
5.6 TEMPORARY AND PERMANENT EROSION CONTROL....................................................................... 17
5.7 SEPTIC DRAINFIELDS........................................................................................................................ 18
5.8 STRUCTURAL MITIGATION............................................................................................................... 18
6.0 CLOSURE............................................................................................................................................19
Appendix A-Site Plan
Appendix B -Soil Information
Appendix C-Slope Stability
Appendix D—Erosion Control
Appendix E—Drainage Details
1.0 INTRODUCTION
Envirotech Engineering (Envirotech) has completed a geotechnical investigation for a planned
single family residence located at 460 E Stretch Island Rd S, identified as parcel number
12108-42-00050, 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 May 22, 2019. 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 geotechnical 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;
field 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
foundation, settlement, earthwork construction, retaining walls, erosion control, drainage, and
vegetation in the Engineering Recommendations Section.
1.1 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 1- 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 conditions are illustrated
on the Site Map provided in Appendix A of this report.
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 project 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 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 near the
Envirotech Engineering Geotechnical Report
PO Box 984 page 1 Parcel 12108-42-00050
Belfair, Washington 98528 Mason County, Washington
Ph. 360-275-9374 May 31,2019
project;
• 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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Vicinity Map from Mason County Website
Envirotech Engineering Geotechnical Report
PO Box 984 page 2 Parcel 12108-42-00050
Belfair, Washington 98528 Mason County, Washington
Ph. 360-275-9374 May 31,2019
2.0 SURFACE CONDITIONS
Information pertaining to the existing surface conditions for the project was gathered on May 22,
2019 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. However,most of the property is cleared with lawn. 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 113%with a vertical relief of about 70
feet.
Ascending grades are generally located to the south and east of the planned development. These
slopes are relatively minor within 300 feet of the project,with no apparent slope grades of at least
15%.
2.2.1 Upslope Geomorphology
The upland area of the property and beyond is generally situated on a hillside of glacial origin.
2.3 Surface Drainage
Runoff originating upslope of the development is mostly diverted away from the property by
accommodating topography. Indications of past drainage problems were observed along the north
side of the property.
2.3.1 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 12108-42-00050
Belfair, Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 31,2019
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.
Indications of deep-seated slope problems were not observed during the site visit. A small scale
shallow landslide was noted on the critical slope. In addition,shoreline erosion is prominent.
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Aerial Photo from Mason County Website
Envirotech Engineering Geotechnical Report
PO Box 984 page 4 Parcel 12108-42-00050
Belfair, Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 31,2019
3.0 SUBSURFACE INVESTIGATION
Information on subsurface conditions pertaining to the project was primarily gathered on May 22,
2019 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
test pits and/or nearby banks extending to depths of up to 5 feet below the natural ground 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 dense soils to the depth of terminus.
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 Vaughn 7.5-minute Quadrangle, Pierce and Mason Counties,
Washington' by Robert L. Logan and Timothy J. Walsh, December 2007, provides the following
caption(s)for the project area:
Envirotech Engineering Geotechnical Report
PO Box 984 page 5 Parcel 1210842-00050
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 31,2019
j Qgt� Vashon till—Unstratified to moderately stratified,compact,unsorted mixture of clay,silt,sand,
and gravel deposited directly by glacial ice;gray to tan;nearly everywhere in sharp contact with
underlying units;does not drain well as permeability and porosity are low;sand and finer grains
in matrix are very angular;pebble-to boulder-size clasts are commonly striated and faceted,
having angular and(or)rounded edges;boulders are generally disseminated and relatively rare.
may contain interbeds of sand and gravel.The surface of this unit is characterized by streamlined
drumlins,striations,and flutes that arc generally hundreds to thousands of feet long.Angular to
subrounded glacial erratic boulders,consisting mostly of plutonic or metamorphic rock,arc
common but disseminated on the suriace of this unit. Unit may be capped by a few feet of
unsorted and stained ablation sand and gravel or by unit Ogos.Vashon till locally crosscuts older
sediments,forming angular unconformities.Drag folding and horizontal shearing may occur at
the base of the till or internally between layers of till,especially in thick deposits.Unit Qgt
ranges in thickness from 0 to at least 50 ft.
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Geological Map Department of Natural Resources Washington State
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.
Envirotech Engineering Geotechnical Report
PO Box 984 page 6 Parcel 1210842-00050
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 31,2019
The project is currently composed of native soils without indications of fill. Within test pit
locations, soils within the upper 5 feet of natural ground were generally observed to be dry poorly
graded sand(SP).Soils below the upper 5 feet layer were observed to be mostly grey,low moisture,
silty sand with gravel(SM), locally known as hardpan. The hardpan may extend to depths greater
than 50 feet. This is based on nearby well reports, site geology, and/or knowledge of the general
area.
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 Harstine Gravelly Ashy Sandy Loam,H.j
with 6% - 15%slopes,and Sinclair Shotty Loam, So,with 5%- 15% slopes.The soil designations
are depicted in the aerial photograph below, and descriptions are provided in Appendix B of this
report.
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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
50 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 12108-42-00050
Belfair, Washington 98528 Mason County, Washington
Ph. 360-275-9374 May 31,2019
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`Unstable' 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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Map from Washington State Department of Ecology Website
Envirotech Engineering Geotechnical Report
PO Box 984 page 8 Parcel 12108-42-00050
Belfair,Washington 98528 Mason County, Washington
Ph. 360-275-9374 May 31,2019
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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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 5 feet soil depth
Soil unit weight: 100 pcf
Angle of internal friction: 34 degrees
Cohesion: 0 psf
Envirotech Engineering Geotechnical Report
PO Box 984 page 9 Parcel 12108-42-00050
Belfair, Washington 98528 Mason County, Washington
Ph. 360-275-9374 May 31,2019
Soils below 5 feet in depth
Soil unit weight: 140 pcf
Angle of internal friction: 40 degrees
Cohesion: 400 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 stability
information in Appendix C for a depiction of minimum factors of safety away from the project.
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.
4.2.1 Shoreline Recession
Due to the close proximity of a shoreline, an evaluation of the shoreline recession rate for this
project was completed.This was accomplished by interviewing property owners within the vicinity
of the project, and/ or carefully reviewing and comparing historical aerial photographs of the
project.Historical aerial photograph sources may be found in the 1951 aerial for the Soil Survey of
Mason County, aerials from the Washington State Department of Ecology, and from the
Washington State Department of Natural Resources website. Based on available information, we
conclude that the past shoreline recession for this project is less than 5 feet in 50 years.
Envirotech Engineering Geotechnical Report
PO Box 984 page 10 Parcel 12108-42-00050
Belfair,Washington 98528 Mason County, Washington
Ph. 360-275-9374 May 31,2019
4.3 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, in which is approximately 2 miles to the north 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.
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 indicated 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,
Envirotech Engineering Geotechnical Report
PO Box 984 page I 1 Parcel 12108-42-00050
Belfain Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 31,2019
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
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 12108-42-00050
Belfair, Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 31,2019
5.0 ENGINEERING RECOMMENDATIONS
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 1210842-00050
Belfair, Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 31,2019
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 ofthis 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.
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.
Envirotech Engineering Geotechnical Report
PO Box 984 page 14 Parcel 12108-42-00050
Belfair, Washington 98528 Mason County, Washington
Ph. 360-275-9374 May 31,2019
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 SOILS
OR ENGINEERED t
FILL
1
II UN STURBED SUBGiA E
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
Y 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.
5.2.3 Retaining Wall Backfdl
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
Envirotech Engineering Geotechnical Report
PO Box 984 page 15 Parcel 12108-42-00050
Belfair, Washington 98528 Mason County, Washington
Ph. 360-275-9374 May 31,2019
located within retaining wall backfill, then 90% compaction is required. In addition, heavy
construction equipment should be at a distance of at least ''/z 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 75 feet footing
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
DACE _
I I—I
SETBACK --�-I FOOTING
Envirotech Engineering Geotechnical Report
PO Box 984 page 16 Parcel 12108-42-00050
Belfair,Washington 98528 Mason County, Washington
Ph. 360-275-9374 May 31,2019
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.
5.4 Surface and Subsurface Drainage
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. In addition, drainage outlets must
be outside of the building setbacks as provided in this report. 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
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
Envirotech Engineering Geotechnical Report
PO Box 984 page 17 Parcel 12108-42-00050
Belfair,Washington 98528 Mason County, Washington
Ph. 360-275-9374 May 31,2019
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 Drainflelds
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 12108-42-00050
Belfain Washington 98528 Mason County, Washington
Ph. 360-275-9374 May 31,2019
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
provided for optimal performance. The recommendations provided in this report are valid for the
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
yW
Jessica Legarza, M.S. Michael Staten, P.E.
Staff Geologist Geotechnical Engineer
Envirotech Engineering Geotechnical Report
PO Box 984 page 19 Parcel 12108-42-00050
Belfair. Washington 98528 Mason County, Washington
Ph. 360-275-9374 May 31,2019
APPENDIX A
SITE PLAN
SCALE, 1 INCH 150 FEET
TOP OF SLOPE
EXCEEDING 40%
TOE OF SLOPE
EXCEEDING 40%
XIST(NG DRIVEWAY
4 /E REPOSED
�o DRAINFIELD AREA
TP1
I i y
' � O
CASE iNLCT 4 / H
o � y
PROPOSED SINGLE PROPERTY LINE
FAMILY RESIDENCE
75 FT CONSTRUCTION
10 FT VEGCTATION SETBACK FROM TOP OF
SETBACK FROM TOP CRITICAL SLOPE
ff CRITICAL SLOPE
NOTES, PROJECT/OWNER/ LOCATION,
1.EROSION CONTROL MAY BE REGUIRED FOR THIS SITE.GENERAL LOCATIONS SINGLE FAMILY RESIDENCE
ARE DEPICTED.AND ALTERNATIVES MAY BE UTILIZED AS EXPLAINED IN THE GEOTECHNICAL REPORT
GE07ECHNICAL REPORT,
2 CONTOURS WERE NOT PREPARED BY A LICENSED LAND SURVEYOR. FUNK
CONTOURS WERE EXTRAPOLATED FROM A PUBLIC LIDAR SOURCE. AND 460 E STRETCH ISLAND WAY S
INCORPORATED FIELD MEASUREMENTS AS EXPLAINED 1N THE GEOTECHNICAL LEGEND PARCEL 12109-42-00050
REPORT. MASON COUNTY, WASHINGTON
3�BOUNDARIES WERE NOT PREPARED BY A LICENSED SURVEYOR.LOCATIONS TEMPORARY ENGINEER
-
Or SITE FEATURES THAT ARE SHOWN HERE, SUCH AS 1OP OF SLOPES, TOE {EROSION CONTROL ENGIROTECH ENGINEERING
OF SLOOPES. WATER FEATURES. ETC.., WITH RELATION TO THE PROPERTY PO BOX ECH
LINES MUST BE VERIFIED BY THE OWNER. RECOMMENDATIONS IN THE SLOPE INDICATOR PELFAIR, VASHINGTON 98528
GEOTECHNICAL REPORT PROVIDE SETBACKS, BUFFERS, DEPTHS,ETC.. WITH DELFAI5-9374
RELATION TO GEOLOGIC FEATURES, NOT PROPERTY LINES THESE GEOLOGIC --Be— CXtSTING CONTRIR
FEATURES MAY BE LOCATED ON THE SUBJECT PROPERTY OR NEIGHBORING SITE PLAN
PROPERTIES. TPI TEST PIT
APPENDIX B
SOIL INFORMATION
VERTICAL MD HAI20NTAL SCALE,
I UCH= 40 MT
SOILSI POORLY GRADED SAND
OVER DENSE GLACIAL TILL
PROPOSED HOUSE
MEDIUM DENSE TO DENSE
POORLY GRADED SAND (SP)
EXISTING GRADE
x�
1
GLACIAL TILL OR
ADVANCE OUTWASH
CASE INLETQ
SECTION A-A
PROJECT/ OWNER/ LOCATIW,
SINGLE FAMILY RESIDENCE
GE❑TECHNICAL REPORT
FUNK
PARCEL 12108-42-00050
MASON CDJNTY, WASHINGTON
NOTES.
ENGINEER
ll MINOR GRADE CHANGES REQUIRED IN ORDER TO ACHIEVE ENVIROTECH ENGINEERING
POSITIVE DRAINAGE PO BOX 984
2) THE SOIL PROFILE 1S ACCURATE FOR THE DEPTH OF BELFAIR, WASHINGTON 98528
THE OBSERVED TEST PITS AT THE SPECIFIED LOCATIONS. 360-275-9374
LOWER DEPTHS ARE BASED ON SITE GEOLOGY,
WELL LDG(S), AND/OR EXPERIENCE IN THE GENERAL AREA. SOIL PROFILE
TEST PIT LOG
TEST PIT NUMBER TP-1
PROJECT: Funk Geotechnical Report DATE OF LOG: 5/22/2019
PROJECT NO: 1999 LOGGED BY: MCS
CLIENT: Patty Funk EXCAVATOR: N/A
LOCATION: Parcel 12108-42-00050 DRILL RIG: None
Mason County, Washington ELEVATION: N/A
INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: N/A
SOIL STRATA, STANDARD PENETRATION TEST
DEPTH SAMPLERS USCS DESCRIPTION LL PI CURVE
AND TEST DATA
DEPTH N 10 30 50
0
SP Brown, moist, loose to medium dense
POORLY GRADED SAND. Low
plasticity.
1
2
3
4
Light brown, dense
5
Excavation terminated at approximately
5.0 feet
6
7
8
9
10
No Groundwater Encountered ENVIROTECH ENGINEERING
This information pertains only to this boring and should not be Geotechnical Engineering
interpreted as being indicitive of the entire site
Map Unit Description-Harstine gravelly ashy sandy loam.6 to 15 percent slopes—Mason
County.Washington
Mason County, Washington
Ha—Harstine gravelly ashy sandy loam, 6 to 15 percent
slopes
Map Unit Setting
National map unit symbol: 21tvj
Elevation: 200 to 390 feet
Mean annual precipitation: 30 to 55 inches
A4ean annual air temperature: 48 to 52 degrees F
Frost-free period. 180 to 200 days
Farmland classification: Prime farmland if irrigated
Map Unit Composition
Harstine and similar soils: 85 percent
Minor components: 15 percent
Estimates are based on observations, descriptions.and transects of
the mapunit.
Description of Harstine
Setting
Landform: Ridges
Landform position(two-dimensional). Footslope
Landform position(three-dimensional) Nose slope
Down-slope shape: Linear
Across-slope shape: Convex
Parent material: Sandy glacial drift • ith an influence of volcanic
ash over dense glaciomarine deposits
Typical profile
Oi-0 to 0 inches: slightly decomposed plant material
Oe-0 to 1 inches: moderately decomposed plant material
&0 - 1 to 6 inches: gravelly ashy sandy loam
Bw2-6 to 14 inches: gravelly ashy sandy loam
Btv3-14 to 22 inches: gravelly ashy sandy loam
Bw4-22 to 32 inches: gravelly ashy sandy loam
2Cd i-32 to 38 inches: gravelly loamy sand
2Cd2-38 to 61 inches: gravelly loamy sand
Properties and qualities
Slope. 6 to 15 percent
Depth to restrictive feature: 20 to 39 inches to densic material
Natural drainage class: tvtoderately,::ell drained
Capacity of the most limiting layer to transmit tvater(Ksat). Very
lo%::(0.00 to 0.00 in:hr)
Depth to water table. About 24 to 37 inches
Frequency of flooding: None
Frequency of ponding: None
Available water storage in profile. Lo..(about 4.2 inches)
ksnx Natural Resources Web Soil Survey 5!272019
Conservation Service National Cooperative Soil Survey Page I of 3
Map Unit Description Harstine gravely ashy sandy loam 6 to 15 percent slopes---Mason
County.Washington
Interpretive groups
Land capability classification(irrigated): None specified
Land capability classification(nonirrigated). 4s
Hydrologic Soil Group: C
Forage suitability group: Limited Depth Soils(G002XN302WAi
Hydric soil rating: No
Minor Components
Indianola
Percent of map unit. 5 percent
Landform: Eskers.kames.terraces
Landform position(three-dimensional): Riser
Down-slope shape: Linear
Across-slope shape: Linear
Hydric soil rating. No
Norma
Percent of map unit: 3 percent
Landform: Depressions.drainage.vays
Landform position(three-dimensional): Dip
Down-slope shape: Concave.linear
Across-slope shape. Concave
Hydric soil rating. Yes
Dupont
Percent of map unit: 3 percent
Landform: Troughs,depressions
Landform position(three-dimensional). Dip
Down-slope shape: Linear.concave
Across-slope shape. Concave
Hydric soil rating: Yes
Neilton
Percent of map unit: 2 percent
Landform: Out.,ash terraces
Landform position(three-dimensional): Riser
Dotin-slope shape: Linear
Across-slope shape. Linear
Hydric soil rating: No
McKenna
Percent of map unit: 2 percent
Landform: Depressions,drainage::as
Landform position(three-dimensional): Dip
Down-slope shape: Concave.linear
Across-slope shape: Concave
I;r)% Natural Resources Web Sod Survey 5l271201y
of Conservation Service National Cooperative Sod Survey Page 2 of 3
Map Unit Description Harsune gravelly ashy sandy loam.6 to 15 percent slopes---Mason
County,Washington
Hydric soil rating. Yes
Data Source Information
Soil Survey Area: Mason County.Washington
Survey Area Data: Version 14.Sep 10,2018
i iR\ Natural Resources Web Soil Survey 5272019
+d" Conservation Service National Cooperative Sod Survey Page 3 of 3
Map Unit Description Sinclair shotty loam,5 to 15 percent slopes---Mason County
Washington
Mason County, Washington
So—Sinclair shotty loam, 5 to 15 percent slopes
Map Unit Setting
National map unit symbol: 2hn7
Elevation. 0 to 300 feet
44ean annual precipitation: 25 to 50 inches
Mean annual air temperature. 50 degrees F
Frost-free period. 200 days
Farmland classification, Farmland of state::ide importance
Map Unit Composition
Sinclair and similar soils. 100 percent
Estimates are based on observations.descriptions, and transects of
the mapunit
Description of Sinclair
Setting
Landfo.rm. Till plains
Typical profile
H1-0 to 11 inches: gravelly loam
H2-11 to 35 inches. very gravelly loam
H3-35 to 60 inches: gravelly sandy loam
Properties and qualities
Slope. 5 to 15 percent
Depth to restrictive feature. 28 to 42 inches to densic material
Natural drainage class: Moderately :.ell drained
Capacity of the most limiting layer to transmit water(Ksat). Very
lo:r to moderately lov. (0.00 to 0.06 in,hr)
Depth to water table: About 18 to 30 inches
Frequency of flooding: None
Frequency of ponding. None
Available water storage in profile: Lo:•. (about 3.7 inches)
Interpretive groups
Land capability classification(irrigated;: None specified
Land capability classification(nonirrigated): 4s
Hydrologic Soil Group: B
Forage suitability group: Limited Depth Soils(G002XN302WA)
Hydric soil rating: No
Data Source Information
Soil Survey Area: Mason County.Washington
Survey Area Data: Version 14, Sep 10.2018
1AM Natural Resources Web Soil Survey 5272019
'i Conservation Service National Cooperative Sod Survey Page 1 of 1
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❑Dewater hripoee ❑Test web ❑Oahe cry Grapeview comr 13
saL—
OF WORK: Owner number of well(if mvc than Ow) 1/t-1/1 EW M e-q
N-Weil ❑Recnemnoned Mel d_❑Dag El Bond ❑Drivca laleationl>.YL tetra See_R twn�}_ R-;i1 a o e
DetprnW Mable ❑Rnluy ❑Jebel I.al/Iv ly Deg Lid MtdSx ag� WWM
DUVWNSIONS: Dumetc o(-d inches.drilled_3QQ_h (9.1'r am
Depte of ozooe ed well 300 h REQUIRED) Lang Deg Long K=Sec
Tax Parcel No. 191 nf>_.49_nn1 do
CONSTRUCTION DETAILS
Casiallfr]Welded —6 Dian.from �W�7f
CONSTRUCTION OR DECO?,04SS10N PROCEDURE
:❑T, installed Diem.hornformation Describe by color. ,tier d ma�ral tad msmre,sad Ibc
kind and astare of the material is raeh sa dum penetrated,wi0 at last one
❑7Ltr�ded Diem from for ace change of information.ludieste all weer cocouatesed.
Perforations: ❑Yes ION. (LISE ADI)MONAL SHEL S IF NECESSARY.)
ype of perforolas... MATERIAL FROM TO
SIZE of perfs__m.by_____in,and nu.Of Pufs_from 1t so_n-
Seems:®Yes ❑No Q K-Pere Laatim 293
Manufaenads Nanac CX)Qk 7bpsoil
Iyyc f-.:..7.,,. Model No.
Diam S Slot Sire +tR_Emm295_h to---30&_ft
Dian SlaSut from hm ft Brown silt bcxJlsd sand d 1
Gro-FUter piliCk 1 ❑Ya ®No ❑Si=Of gmvWtaad
Materials placed froso 1L lo fC Brown s�1
so.faee Sal: Q Yes ❑No To wbat deplhl 16 It
Materials used in seal P-t-rvti to � Brown fine sand with some
in ss
Did any swau conta umabk water?❑ L
Yes No
Type of water^ Deph Of smh
Metbod of scaling sash o(f Sandy brown clay 117
PUMP: ManufamvdsName_ Ca11r1e:
Ty'Fe NJ'. Blue clay
WATER LEVELS: Load-surface elevation abo.e a=sea Level ft
Static Ievd AS h below top of well Due
Artesian preasare jbs.per square inch Due
Artesian water is cwnbotled by
(cap.valm etc.) Flee to medium brown sand
WEU TESTS: Drawdowo is amount water level is lowered below static leveL with water 'Inn
Was a pump test made?❑Yes U No If ya,by whom?
Yield_ya/min.svrih ft drawdown after Ern
Yield. eallmin.with R dnwdown after Est.
Y.dd:__0jaau.with. k dnwdown aftes Err /
Recovery data/none mien err rrro when fwmp turned ofJ)(watrr Ievet nresnrrd from
—U top to water fn•rl)
Time Water Level Time Water Level Time Water Level _ if
-- —— Lr_
ng-p,iminent Of Ecok a
Date of cast •<.{ r ES
Basler tes1_2G.jab min.with _ft drawdown after I Ilm
Airsest eat/mil.with stem se al IL for hrs.
Artesian Bow g P as Date Start Date 3/7?10T Compkfed D,m3(Z.9/02
Temperate:of water_Was a chemical analysis:node?❑Yes 0 Na
WELL CONSTRUCTION CERTIFICATION: I constructed end/or accept rcsponsibdity for construction Of INS well,and its eorrThance with all
Washington well construction standards.Materials used and the infornwion repooted above are true to my best lmowlddge,and belief.
®Driller❑Fligine:er❑Tnrnee N nt) [killing Covipany DayiS Drilling
Ikiller/Engincerfrrainee Sig= t"'- Address 390 NE Davis Farnt Rd_
Driller or Trainee License No. 1706 Q D Dip,Stale,zi Bel i r, wa 9857A
Contrtlaor'S DAVISDI110t7J4 March 02
1f trainee,bcemed diiller'a Registration No Data
S+K2 arsd IkYnx nr Feology .is au Equal Opponuoity Employ. ECY RSII.140(Rev ar01)
APPENDIX C
SLOPE STABILITY
1 _ 00
1 . 1O
1 . 2 0
1 . 30
1 40
1 50
1 _ 60
1 _ 7 0
W 1 . S O
1 _ 90
. U O
w
1 7 3
Project _ Funk Project
Oat-- agile _ Dynamic Analysis
Analysi _ Bi- hop
STABLE—=002 N= .. Lad
1 O O
1 10
1 20
1 . .3 O
1 . .40
1 . so
r•
-1 . 60
1 8 O
1 . 90
. 00
67 3
Pr: j � =t Funk Pr- j ccL
D A L A f i 1 S L A t i C A n A 1 I s i s
Anealyaia Si�2zop
APPENDIX D
EROSION CONTROL
GEOTEXTILE FABRIC
WRAP AROUND TRENCH
TO AT LEAST ENTIRE
BOTTOM OF TRENCH
BEFORE PLACING GRAVEL 2'x2'x5' WOOD POST OR
12' DEEP, 8' WIDE TRENCH f EQUIVALENT OR BETTER
FILLED WITH 3/4' TO 1 I/2'
WASHED GRAVEL OR VEGETAT N
1i
DIRECTION DF a,s IT EXISTING
it
WATER FLOW GROUND SURFACE
za IT
e•
SILT FENCE — CROSS SECTION
N.T.S.
2'x2' WOOD POST (TYP) GE❑TEXTILE FABRIC
OR EQUIVALENT OR BETTER AND WIRE MESH
@ 6 FT MAX, O.C.
EXISTING
GROUND SURFACE
2
12' DEEP, 8' WIDE
TRENCH FILLED WITH '�
3/4' TO 1 1/2' 25 IT
WASHED GRAVEL OR VEG TI
BOTTOM EXTENTS OF GEOTEXTILE FABRIC I SLT FENCE — DETAIL
N.T.S.
PROVIDE FULL WIDTH
3/4 IN TO 1 1/Z N20 FT INGRESS/EGRESS
CRUSHED GRAVEL
PLACED AT 6 IN
MINIMUM DEPTH
WELL-DRAINED
SOILS FULL�N�
-0.02 IN/MIN
R=25 FT MIN
ti —
ACCFSS Pmo
_STABILIZED CONSTRUCTION ENTRANCE
N.T.S.
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APPENDIX D
DRAINAGE DETAILS
HOUSE
ROOF DOWNSPOUT
SERVES UP TO
700 SF OF ROOF
50 FT MIN
VEGETATED
FLOW PATH
DOWNSPOUT
EXTENSION
R❑OF DOWNSPOUT AND SPLASH BL❑CK DETAILS
N.T,S
GEo 101q - 000"
Mason County Review Checklist
for a Geotechnical Report
Instructions:
This checklist is intended to assist Staff in the review of a Geotechnical Report. The Geotechnical Report is reviewed
for completeness with respect to the Resource Ordinance. If an item is found to be not applicable, the Report should
explain the basis for the conclusion. The Report is also reviewed for clarity and consistency. If the drawings,
discussion, or recommendations are not understandable, they should be clarified. If they do not appear internally
consistent or consistent with the application or observations on site, this needs to be corrected or explained. If
resolution is not achieved with the author, staff should refer the case to the Planning Manager or Director.
Foy- B Lo Zo t q -0 l 2 4 0
Applicant's Name: �N�
Permit#. 201q- ODGa) Parcel#: 12104 -Ll Z''0 00570
Date(s)of the Document(s) reviewed: 11"Z Z "l
1. (a) A discussion of general geologic conditions in the vicinity of the proposed development,
OK? Y S Comment:
(b) A discussion of specific soil types
OK? 65 Comment:
(c) A discussion of ground water conditions
OK? YO Comment:
(d) A discussion of the upslope geomorphology
OK? VeS _Comment: 2..Z.. k
(e) A discussion of the location of upland waterbodies and wetlands
OK? Njg�Comment: Z 1
(f) A discussion of history of landslide activity in the vicinity, as available in the referenced maps and records
OK? VE�Comment: CPnAL`/ NTH f6COMM6 r-V A4T10OV5 W 9EO TECH fiefX --r
2. A site plan that identifies the important development and geologic features.
OK? ES Comment: ' 7rENO'y A-
3. Locations and logs of exploratory holes or probes.
OK? Yf5 Comment: AeO,-N'OIX 'g
4. The area of the proposed development, the boundaries of the hazard, and associated buffers and setbacks shall
be delineated (top, both sides, and toe) on a geologic map of the site.
OK?-l`'-=Comment: 0IJ 51119- PC.+-y
5. A minimum of one cross section at a scale which adequately depicts the subsurface profile, and which
incorporates the details of proposed grade changes.
OK? I�tComment: Of") �r 60t1. WO Tf?-ufl
6. A description and results of slope stability analyses performed for both static and seismic loading conditions.
Analysis should examine worst case failures. The analysis should include the Simplified 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 coeffients should be a value of 0.15.
OK? ES Comment: IKW"M"h 'FQGTO~S
7. (a) Appropriate restrictions on placement of drainage features
OK? Yt% Comment: �.9 A4010 /N(`1 'Lr�luN
,5
(b) Appropriate restrictions on placement of septic drain fields
OK? I Comment: 7
(c) Appropriate restrictions on placement of compacted fills and footings.
OK? l Comment: 5.2.E
Page 1 of 2 Form Effective June 2008
(d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other slopes.
OK? VET Comment:
(e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of other slopes.
OK? F5 Comment: 75 fwiw� 6tT gAr_r- FM"` 5cye- FVC re-pwJo 1Y0 %
8. Recommendations for the preparation of a detailed clearing and grading plan which specifically identifies
vegetation to be removed, a schedule for vegetation removal and replanting, and the method of vegetation
removal.
OK? Comment: 20 Q f- NOr uJA40XC NTEl PCV- PErb<-T
9. Recommendations for the preparation of a detailed temporary erosion control plan which identifies the specific
mitigating measures to be implemented during construction to protect the slope from erosion, landslides and
harmful construction methods.
OK? E Comment: 5•(Q F fidS(OA/ Cn.JT"L-
10. An analysis of both on-site and off-site impacts of the proposed development.
OK?Comment: t r CO MM F 14 DA TiOAJj i--i A-000,+-t-
11. Specifications of final development conditions such as, vegetative management, drainage, erosion control, and
buffer widths.
OK? IE2 Comment: 53 - ON 5*11C_ 0L+J XPPVN n%Y
12. Recommendations for the preparation of structural mitigation or details of other proposed mitigation.
OK?&_') Comment: dOr /J V C-53 iE Rlu m^-r-
13. A site map drawn to scale showing the property 6oundaries, scale, north arrow, and the location and nature of
existing and proposed development on the site.
OK?-iVO ce_Comment: $t't� ?L+00
Are the Documents signed and stamped? ES By whom? I C FF 46L S*A-TEn/
License#: 43 0y5 License type: PE
FIRST REVIEW Approved ❑ Need more info.
If not approved, what is the next action/recommendation for further action?
Reviewed by on "2G "� Time spent in review:
SECOND REVIEW/ UPDATE ❑ Approved ❑ Need more info.
Reviewed by , on . Time spent in second review:
THIRD REVIEW/UPDATE ❑ Approved ❑ Need more info.
Reviewed by , on . Time spent in third review:
Disclaimer.' Mason County does not certify the quality of the work done in this Geotechnica/Report.
Page 2 of 2 Form Effective June 2008