HomeMy WebLinkAboutGeoTech Report for BLD2011-00595 - BLD Engineering / Geo-tech Reports - 7/28/2011 16 1 ,A 0 11 - 0()'615105
RECEIVED
AUG 0 2 2011
426 W. CEDAR ST.
Geotechnical Report
for
Sharer Single Family Residential Property
16991 E. State Route 3, Allyn
Parcel No. 12230-77-00060
Mason County, Washington
July 28, 2011
Project#1178
Prepared For:
Jean Sharer
16950 E. State Route 3 cze F�WAS ST9T
Allyn, Washington 98524 "�T
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Prepared By:
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Envirotech Engineering °�k% 4STOL ��St7
PO Box 984 sS��NAO-
Belfair, Washington 98528
Phone: 360-275-9374
Fax: 360-275-4789
TABLE OF CONTENTS
1.0 INTRODUCTION..................................................................................................................................1
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
2.2.1 Upslope Geomorphology and Water Bodies...............................................................................3
2.3 SURFACE DRAINAGE...........................................................................................................................3
2.4 SLOPE AND EROSION OBSERVATIONS................................................................................................3
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..................................................................................................5
3.3.1 Groundwater...............................................................................................................................7
3.4 SOILS TESTING....................................................................................................................................7
4.0 ENGINEERING ANALYSES AND CONCLUSIONS.......................................................................8
4.1 SLOPE STABILITY................................................................................................................................8
4.1.1 Slope Stability Analysis...............................................................................................................9
4.1.2 Slope Stability Assessment........................................................................................................10
4.1.3 Septic Drainfield Impact to Critical Slopes..............................................................................10
4.2 EROSION............................................................................................................................................10
4.3 SEISMIC CONSIDERATIONS AND LIQUEFACTION.............................................................................11
4.3.1 Liquefaction..............................................................................................................................11
4.4 LATERAL EARTH PRESSURES...........................................................................................................1 1
4.5 ON-SITE AND OFF-SITE IMPACTS.....................................................................................................1 1
5.0 ENGINEERING RECOMMENDATIONS.......................................................................................12
5.1 BUILDING FOUNDATION RECOMMENDATIONS................................................................................12
5.1.1 Bearing Capacity.......................................................................................................................12
5.1.2 Settlement..................................................................................................................................13
5.2 EARTHWORK CONSTRUCTION RECOMMENDATIONS......................................................................13
5.2.1 Ezcavation.................................................................................................................................13
5.2.2 Placement and Compaction of Native Soils and Engineered Fill...........................................13
5.2.3 Retaining Wall Backflll............................................................................................................14
5.2.4 Wet Weather Considerations....................................................................................................14
5.3 BUILDING AND FOOTING SETBACKS.................................................................................................15
5.4 SURFACE AND SUBSURFACE DRAINAGE...........................................................................................15
5.5 VEGETATION BUFFER AND CONSIDERATIONS.................................................................................15
5.6 TEMPORARY AND PERMANENT EROSION CONTROL.......................................................................16
6.0 CLOSURE............................................................................................................................................17
Appendix A-Site Plan
Appendix B-Soil Information(Soil Profile;Soil Logs;Well Reports)
Appendix C-Slope Stability Input&Output
Appendix D—Erosion Control
1.0 INTRODUCTION
Envirotech Engineering (Envirotech) has completed a geotechnical investigation for a single
family residential property located at 16991 State Route 3, identified as parcel number 12230-77-
00060, Allyn, Mason County, Washington. See the vicinity map on the following page for a
general depiction of the site location.
The geotechnical investigation was conducted at the request of the property owner, Jean Sharer,
in support of the proposed development as detailed below. The proposed development, as
provided herein,and the surrounding area is identified in this report as the Project.
An initial geotechnical evaluation of the Project was conducted by Envirotech on July 18,2011.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 Project was provided by the proponent of the property during the
geotechnical investigation.The planned development consists of a I-story single family residence
and other ancillary features typical of this type of development. Driveways and an on-site septic
system are existing due to the previous development. Foundation construction is expected to
consist of continuous strip runners or pads typical of manufactured homes.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:
Envirotech Engineering Sharer Geotechnical Report
PO Box 984 page 1 16991 E State Route 3
Belfair,Washington 98528 Parcel 12230-77-00060
Pb. 360-275-9374 Mason County,Washington
Fax:360-275-4789 July 28,2011
• 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 Project;
• Collect bulk samples 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 Sharer Geotechnical Report
PO Box 984 page 2 16991 E State Route 3
Belfair,Washington 98528 Parcel 12230-77-00060
Ph. 360-275-9374 Mason County,Washington
Fax:360-275-4789 July 28,2011
2.0 SURFACE CONDITIONS
Information pertaining to the existing surface conditions for the Project was gathered on July 18,
2011 by Michael Staten, geotechnical engineer 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
The property is accessed from State Route 3, an existing paved highway. The Project is currently
previously developed land that has been demolished and cleared. The access road extends near
the east property line, and Sherwood Creek/ Mill Pond borders the property to the west. Beyond
the property, rural residential development exists. Vegetation on and near the Project consists
primarily of secondary growth firs, cedars, 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%, are located about 30 feet to the west of
the planned development. The critical slope is variable,and averages 67%with a vertical relief of
approximately 80 feet.
2.2.1 Upslope Geomorphology and Water Bodies
Ascending grades are virtually non-existent as the proposed house is situated on a ridge.
There are no apparent water bodies or wetlands located upslope from the planned
development that would significantly influence the Project.
2.3 Surface Drainage
Stormwater runoff originating on the property appears to primarily sheet flow, and channel. Some
scour is apparent and has been reported by the proponent of the property.
2.4 Slope and Erosion Observations
The slope grades near the Project signal a potential landslide or erosion hazard area. Some
indicators that may suggest past slope movements include:
Envirotech Engineering Sharer Geotechnical Report
PO Box 984 page 3 16991 E State Route 3
Belfair, Washington 98528 Parcel 12230-77-00060
Ph. 360-275-9374 Mason County, Washington
Fax: 360-275-4789 July 28,2011
• 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.
Other than sloughing of fill,these slope instability indicators or other significant mass wasting on
the property or within the general vicinity of the Project were not observed or discovered during
research. Indications of past landslides, current unstable slopes, deep-seated slope problems, or
surficial slope failures were not observed during the site visit.
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Aerial Photo from Mason County Website
Envirotech Engineering Sharer Geotechnical Report
PO Box 984 page 4 16991 E State Route 3
Belfair,Washington 98528 Parcel 12230-77-00060
Ph. 360-275-9374 Mason County,Washington
Fax:360-275-4789 July 28,2011
3.0 SUBSURFACE INVESTIGATION
Information on subsurface conditions pertaining to the Project was primarily gathered on July 18,
2011 by Michael Staten, geotechnical engineer with Envirotech. Specific 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 water well report(s).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/cut slopes of up to 4 feet below the existing 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.
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 medium
dense soils in the upper 36 inches,and very dense soils from 36 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 Quatemary 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.
Based on knowledge of the area, the geological unit, Q0, is the parent material, and usually
described as "unsorted, unstratified, highly compacted mixture of clay, silt, sand, gravel, and
boulders deposited by glacial ice of the Puget lobe; gray; may contain interbedded stratified silt,
and gravel; sand-size fraction is very angular and contains abundant polycrystalline quartz,which
distinguishes this unit from alpine till; cobbles and boulders are commonly striated and (or)
faceted; although unweathered almost everywhere, may contain cobbles or small boulders of
deeply weathered granitic rock."
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 Sharer Geotechnical Report
PO Box 984 page 5 16991 E State Route 3
Belfair,Washington 98528 Parcel 12230-77-00060
Ph. 360-275-9374 Mason County,Washington
Fax:360-275-4789 July 28,2011
1
The Project is composed of native soils with indications of fill. It is apparent that foundations will
not be located in fill. For engineering purposes, these native soils consist of distinguishable
layers,as presented below.
Soils within the upper 3 feet of natural ground were observed to be moist, brown silty sand with
gravel(SM).
Soils below the upper 3 feet layer were observed to be mostly light brown and grey, dense low
moisture, silty sand with gravel (SM). These soils are 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 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 Alderwood Gravelly Sandy
Loam, Ab, with 5% - 15% slopes. This description is only in locations where development is
expected to occur. The soil designations are depicted in the aerial photograph below.
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Soil Survey From USDA Natural Resources Conservation Service
Envirotech Engineering Sharer Geotechnical Report
PO Box 984 page 6 16991 E State Route 3
Belfair,Washington 98528 Parcel 12230-77-00060
Ph. 360-275-9374 Mason County,Washington
Fax: 360-275-4789 July 28,2011
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. Perched
groundwater at shallow depths was not observed on-site, nor indicated on the well
reports. Some groundwater may flow above the hardpan during the wet season.
3.4 Soils Testing
The soil samples obtained at the Project site during the field investigation were preserved and
transported for possible laboratory testing. Visual classification of soils was performed in the
field at all observed soil profiles. Visual classifications were performed in accordance with the
American Standards for Testing and Materials(ASTM D2488).
The general results from the visual classification are presented above in the Subsurface
Conditions Section. Specifically, soils within the upper 4 feet in one testing location consisted of
approximately 20% gravel, 60% sand-sized soils, and 20% fines with low plasticity. Minor
variations observed during the visual classification of particle size content (i.e. gravel, sand,
fines), or isolated pockets within the soil stratification were insignificant in relation to the overall
engineering properties of the soil.
Envirotech Engineering Sharer Geotechnical Report
PO Box 984 page 7 16991 E State Route 3
Belfair, Washington 98528 Parcel 12230-77-00060
Ph. 360-275-9374 Mason County, Washington
Fax: 360-2754789 July 28,2011
4.0 ENGINEERING ANALYSES AND CONCLUSIONS
The following sections present engineering analyses and conclusions with relation to the existing
conditions and proposed improvements of the Project. This section includes slope stability,
erosion, seismic considerations, lateral earth pressures, 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, excessive and/or repeated surficial slope
movements, if not repaired, may represent a threat to the structural integrity of the slope. If this
situation does arise, the slope shall be inspected by a geotechnical 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 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. This
delineation is primarily dependent upon slopes and convergence. Secondly, lithology and
precipitation are modeled within this delineation. In summary, this designation is based on
mapping without field observations or knowledge of the specific site geology or soils. A
Resource Map from the DNR Forest Practices Application Review System is provided below:
Envirotech Engineering Sharer Geotechnical Report
PO Box 984 page 8 16991 E State Route 3
Belfair,Washington 98528 Parcel 12230-77-00060
Ph. 360-275-9374 Mason County,Washington
Fax:360-2754789 July 28,2011
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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 6 feet soil depth
Soil unit weight: 130 pcf
Angle of internal friction: 32 degrees
Cohesion: 50 psf
Soils below 6 feet in depth
Soil unit weight: 140 pcf
Envirotech Engineering Sharer Geotechnical Report
PO Box 984 page 9 16991 E State Route 3
Belfair,Washington 98528 Parcel 12230-77-00060
Ph. 360-275-9374 Mason County,Washington
Fax:360-2754789 July 28,2011
Angle of internal friction: 40 degrees
grees
Cohesion: 400 psf
Based on the slope stability analysis, a minimum factor of safety was determined to be
1.4 relative to static slope failures, and 1.0 with relation to seismic conditions. These
factor of safeties were primarily limited to the face of the slope, and 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 1.6 and 1.2, respectively. See the slope stability information in
Appendix C for a depiction of input parameters and example of outputs.
4.1.2 Slope Stability Assessment
DNR did not indicate previous landslide activity on the slopes downslope from the
Project. Based on the existing surface conditions with respect to the proposed
development, results of the aforesaid slope stability analysis, it is our opinion that the
proposed development should occur in accordance with this geotechnical report.
4.1.3 Septic Drainfield Impact to Critical Slopes
The approximate location of the existing septic drainfield is presented on the Site Plan in
Appendix A of this report. Based on the septic drainfield location with relation to the
existing and proposed topography,the drainfields are not expected to adversely influence
the structures near the critical slopes. This is also based on compliance with all
recommendations in this report.
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 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
Envirotech Engineering Sharer Geotechnical Report
PO Box 984 page 10 16991 E State Route 3
Belfair,Washington 98528 Parcel 12230-77-00060
Ph. 360-275-9374 Mason County,Washington
Fax: 360-2754789 July 28,2011
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.
4.3 Seismic Considerations and Liquefaction
Soils immediately below the expected foundation depth for this Project are generally Type D,
corresponding to the International Building Code(IBC)soil profiles. Soils below a depth of 5 feet
from the existing ground surface may be considered Type C. 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.
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 south of this Project.
This information is based on the USGS Quaternary Fault and Fold Database for the United States.
43.1 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 Lateral Earth Pressures
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. Significant retaining structures are
not anticipated for this Project. If retaining walls are later planned for this Project, prescriptive
requirements from the County should be adhered to. For retaining structures with a height
exceeding County prescriptive requirements,additional design parameters must be accounted for
in the retaining wall analysis, and recommendations should only be provided by a qualified
engineer after the type of backfill is acquired, inclination of backfill slope is estimated, and the
final wall height is determined.
4.5 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 is based on the expected site development,
existing topography, land cover,and the recommendations presented in this report.
Envirotech Engineering Sharer Geotechnical Report
PO Box 984 page 11 16991 E State Route 3
Belfair,Washington 98528 Parcel 12230-77-00060
Ph. 360-275-9374 Mason County,Washington
Fax:360-275-4789 July 28,2011
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-
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.
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. 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. These bearing capacity requirements also apply to isolated footings,
except the width should be increased to 24 inches for both round and square foundations.
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 Sharer Geotechnical Report
PO Box 984 page 12 16991 E State Route 3
Belfair,Washington 98528 Parcel 12230-77-00060
Ph. 360-275-9374 Mason County,Washington
Fax:360-275-4789 July 28,2011
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.
5.2 Earthwork Construction Recommendations
Founding material for building foundations shall consist of undisturbed native soils. 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,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. It is suggested
that foundation excavations are inspected by a geotechnical engineer or qualified
professional in order to assess the bearing material prior to the placement of structural
footings.
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 foot for each foot of compacted or re-compacted fill beneath the foundation. See the
illustration below.
Envirotech Engineering Sharer Geotechnical Report
PO Box 984 page 13 16991 E State Route 3
Belfair,Washington 98528 Parcel 12230-77-00060
Ph. 360-275-9374 Mason County,Washington
Fax:360-275-4789 July 28,2011
&FOOTING
COMPACTED
NATIVE SOILS
OR ENGINEEREDFILL
I I-I 11
-i I '
UNDISTURBED SUBGRADE
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. Engineered
fill 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
Partical Size Distribution of Engineered Fill
Compaction shall be achieved in compacted lifts not to exceed 6 inches and 12 inches for
native soils and engineered fill, respectively. Each lift should be uniformly compacted to
at least 90% 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.
5.2.3 Retaining Wall Backf ill
As previously mentioned, significant retaining structures are not anticipated for this
Project. However, if used, native soils may be used as retaining wall backfill for this
Project. Backfill may also consist of engineered fill or borrow materials approved by a
geotechnical engineer. Placement, compaction and extents of retaining wall backfill
should also be specified by a geotechnical engineer or qualified professional.
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
Envirotech Engineering Sharer Geotechnical Report
PO Box 984 page 14 16991 E State Route 3
Belfair,Washington 98528 Parcel 12230-77-00060
Ph. 360-275-9374 Mason County,Washington
Fax:360-275-4789 July 28,2011
notified, and these soils should be completely removed and replaced with compacted
engineered fill or suitable native material as presented in this section.
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 25 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
FACE
I I—i I —I 1 '
�— 25 FT MIN --- l FOOTING
The required setbacks may be reduced, if necessary. The setback may be decreased by extending
the foundation an additional 2 feet in depth below the ground surface for every 5 feet of setback
reduction. However, the building should not be located any closer than 10 feet from the top of
steep slope. Other mitigation techniques may be utilized in order to reduce the required setback,
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. 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.
From a geotechnical perspective, footing drains are optional for the single family residence. If
footings are established at depths greater than 2 feet below final grade, then perimeter footing
drains are recommended. Roof drains are recommended for this Project,and should be directed to
permanent stormwater facilities away from structures. The stormwater may have an outlet to the
east of the development on the moderate slopes as shown on the Site Plan in Appendix A of this
report. Alternatively, the runoff may be tightlined beyond the toe of the steep slope to the west of
the development.
5.5 Vegetation Buffer and Considerations
Vegetation is an excellent measure to minimize surficial slope movements and erosion on slope
faces and exposed surfaces. By removing trees, the root strength is decreased over time, thereby
lowering the `apparent' cohesion of the soil. Transpiration is decreased, which results in
additional groundwater, increased pore water pressure and less cohesion/ friction of the soil
Envirotech Engineering Sharer Geotechnical Report
PO Box 984 page 15 16991 E State Route 3
Belfair, Washington 98528 Parcel 12230-77-00060
Ph. 360-275-9374 Mason County, Washington
Fax: 360-275-4789 July 28,2011
particles. Stormwater runoff also increases, and, fewer plants will create less absorption of the
force from raindrops,thereby creating the potential for erosion hazards.
Vegetation shall not be removed from the face of the steep 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. If necessary, erosion control measures during construction may include
stockpiling cleared vegetation, silt fencing, intercepting swales, berms, straw bales, plastic cover
or other standard controls. If necessary, 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 Map in
Appendix A depicts the recommended locations for erosion control facilities to be installed, if
necessary.
Permanent erosion control may also be 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. The following Surface and Subsurface Drainage Section may
have additional recommendations with relation to permanent erosion for surface drainage
features.
Envirotech Engineering Sharer Geotechnical Report
PO Box 984 page 16 16991 E State Route 3
Belfair, Washington 98528 Parcel 12230-77-00060
Ph. 360-275-9374 Mason County,Washington
Fax: 360-275-4789 July 28,2011
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. Therefore, it is recommended that a
qualified engineer performs a site inspection during the earthwork construction if subsurface
conditions found on-site are not as presented in this report.
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 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,
Ennvvirote�c-h, ngineering
X
Michael Staten,P.E.
Geotechnical Engineer
Envirotech Engineering Sharer Geotechnical Report
PO Box 984 page 17 16991 E State Route 3
Belfair,Washington 98528 Parcel 12230-77-00060
Ph. 360-275-9374 Mason County,Washington
Fax:360-2754789 July 28,2011
APPENDIX A
SITE PLAN
APPROXIMATE TOP OF 40%+ SLOPES v � ODo .A'o
AND VEGETATION BUFFER. SEE REPORT SCALE, I INCH = 100 FEET
A
0 25 50 100
APPROXIMATE TOE OF
40%+ SLOPE
ROOF DRAINAGE
SHALL NOT BE iM /
DIRECTED TO WEST
SLOPE UNLESS
TIGHTLINED BEYOND
TOE
V
XISTING DRIVEWAY
v
EXISTING DRAINFIELD
ROPOSED HOUSE
ANY EROSION CONTROL TO BE DIRECT ALL ROOF DRAINAGE
DOWNSLOPE OF CONSTRUCTION TO LOCATION EAST OF HOU E
AREAS PER REPORT ON MODERATE SLOPES UNL SS
OTHERWISE ALLOWED IN
REPORT. ^�
25FT BUILDING SETBACK FROM TOP 1¢
OF SLOPES EXCEEDING 407
S ROPERTY LINE
SOILS MEDIUM DENSE SILTY SAND CSM
OVERLYING VERY DENSE GLACIAL TILL
PROJECT/ OWNER/ LOCATION,
SINGLE FAMILY RESIDENCE
NOTES- GE❑TECHNICAL REPORT
1. ALTERNATIVES FOR REDUCING BUILDING SETBACKS OR VEGETATION
BUFFERS MAY BE PROVIDED IN THE GEOTECHNICAL REPORT. SHARER
2. CONTOURS WERE NOT PREPARED BY A LICENSED LAND SURVEYOR. PARCEL 12230-77-00060
CONTOURS WERE EXTRAPOLATED FROM A PUBLIC LIDAR SOURCE, AND MASON COUNTY, WASHINGTON
INCORPORATED FIELD MEASUREMENTS AS EXPLAINED IN THE GEOTECHNICAL
REPORT, LEGEND ENGINEER,
3, BOUNDARIES WERE NOT PREPARED BY A LICENSED SURVEYOR. LOCATION ENVIROTECH ENGINEERING
OF PROPERTY LINES AND SITE FEATURES, SUCH AS TOP OF SLOPES, WATER PO BOX 984
FEATURES, ETC_ WITH RELATION TO THE PROPERTY LINES MUST BE � SLOPE INDICATOR BELFAIR, WASHINGTON 98528
VERIFIED BY THE OWNER. RECOMMENDATIONS IN THIS REPORT PROVIDE EXISTING CONTOUR 360-275-9374
SETBACKS, DEPTHS, ETC., WITH RELATION TO GEOLOGIC FEATURES, NOT
PROPERTY LINES. TPIO TEST PIT
SITE PLAN
APPENDIX B
SOIL INFORMATION
VERTICAL AND HEIRIIDNTAL SCALE-
I INCH . 40 FEET
0 0
PROPOSED HOUSE
FILL
MEDIUM DENSE
OVERBURDEN (GM)
DRAINFIELD
O.
DENSE GLACIAL TILL 22i+
SECTION A-A
PROJECT/ OWNER/ LOCATION,
SINGLE FAMILY RESIDENCE
GE❑TECHNICAL REPORT
SHARER
PARCEL 12230-77-00060
MASON COUNTY, WASHINGTON
NOTES-
ENGINEER,
1) MINOR GRADE CHANGES REQUIRED IN ORDER TO ACHIEVE ENVIROTECH ENGINEERING
POSITIVE DRAINAGE PO BOX 984
2) THE SOIL PROFILE IS 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 LOG(S), AND/OR EXPERIENCE IN THE GENERAL AREA. S❑IL PROFILE
TEST PIT LOG
TEST PIT NUMBER TP-1
PROJECT: SFR Geotechnical Report DATE OF LOG: 7/18/2011
PROJECT NO: 1178 LOGGED BY: MCS
CLIENT: Sharer EXCAVATOR: N/A
LOCATION: Parcel 12230-77-00060 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 ... ... .... . . . .......... ... ...... .
SM Brown, moist, loose to medium dense
SILTY SAND with GRAVEL. Gravel is
_ primarily well-graded and subangular.
Sand is mostly medium. Low plasticity.
2
3 Hard Pan
Excavation terminated at approximately
3.0 feet
4
5
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:Alderwood gravelly sandy loam,5 to 15 percent slopes—
Mason County,Washington
Mason County, Washington
Ab—Alderwood gravelly sandy loam, 5 to 15 percent slopes
Map Unit Setting
Elevation. 50 to 800 feet
Mean annual precipitation: 25 to 60 inches
Mean annual air temperature:48 to 52 degrees F
Frost-free period: 180 to 220 days
Map Unit Composition
Alderwood and similar soils: 100 percent
Description of Alderwood
Setting
Landform: Moraines
Parent material: Basal till with a component of volcanic ash
Properties and qualities
Slope: 5 to 15 percent
Depth to restrictive feature: 24 to 32 inches to dense material
Drainage class: Moderately well drained
Capacity of the most limiting layer to transmit water(Ksat):Very low
to moderately low (0.00 to 0.06 in/hr)
Depth to water table:About 18 to 36 inches
Frequency of flooding: None
Frequency of ponding: None
Available water capacity:Very low (about 2.5 inches)
Interpretive groups
Land capability(nonirrigated):4s
Typical profile
0 to 10 inches. Gravelly sandy loam
10 to 28 inches: Very gravelly sandy loam
28 to 60 inches: Gravelly sandy loam
Data Source Information
Soil Survey Area: Mason County, Washington
N I Survey Area Data: Version 6, Sep 22, 2009
Natural Resources Web Soil Survey 7/28/2011
Conservation Service National Cooperative Soil Survey Page 1 of 1
File Original and First Copy with Application No.
Department of tcology WATER WELL REPORT
Second Copy—Owner's Copy
Third Copy—Drinces copy STATE Or WAAMMOTON Permit No.
(1) OWNER: Name......A ol....... .
(2) LOCATION OF WELL County tW4.
_n...........................................................- !rft,1113� S.L.30 T.U N., R/eW.M.
Bearing and distance from section or subdivision corner
(3) PROPOSED USE: Domestic W-*"Industrial. [3 Municipal 0 (10) WELL LOG:
Irrigation [) Test Well 0 Other o rormation:Describe by color,character•jmzr of material and structure,and
show thickness of aqus era and the kind and nature of the materwl in each
X sereftin penetrated. =h at least one entry for each change of formation.
(4) TYPE OF WORK.- Owner's number of well
(if than one).... .. . ................... MATZRIAL TO
Now"oil r112 .,,,,d; OW [] Bored C1
Deepened 0 Cable 00""Drive. 0
Reconditioned El Rotary 0 Jetted E3
I Imor e
(5) DIMENSIONS: Diameter of well
Drilied...... 11<0......ft- Depth at completed ell.,
(6) CONSTRUCTION DETAIL:
Casing installed: ro...... Dism. from to ...Yce ft.
Threaded 0 .................. Diam. from ................ ft. to ................ ft.
Welded W1.. ................. Dism. from ft. to ............_ ft.
Perforations: Yea 0 No�
a Type of perforator used_..............._... .. ..............................................
SIZE of perforations ............................. an. by .- in.
. ............... perforations from ...... . ........... ft.to ....................... ft.
.......... perforations from ............... ft. to --__-------------- ft.
...................... perforations from ft.to ....................... ft.
Screens: Yes 2101"No E3
b(anufa N .............................
Type Model No....._-- 7 DISM. from ...1.4 ft, to ........
Diem. ................ Slot size ................ from .............. it to............... ft
Gravel packed: Yes 0 No R00000Size of gravel; ............................
Gravel placed from ..............................._ft.to... ............................ft. r
Surface seal: Yes a- No 0 To Jbirt de V d th? ft.Material used in seal.... ... .. ......................
Did any strata contain unusable water? Yes 0 No Iro
Type of water?.................................Depth of strata......_._............._..... 19M
Method of sealing strata Off....-_. .............................................. .........
U1 L-0
(7) PUMP:• manuraturer's Naro*..........................................................
L
Type: ................................................................... .. HP.........................
(8) WATER LEVELS.- Land-surface elevation
above mean see level.... ..........................ft
Static level ............. 7.1 71, ft. below top of well Date.....1
Artesian pressure .. .. . ................lbs. per square inch Daft ........................
Artesian water Is controlled by........._._....... ) *
(9) WELL TESTS: Drawdown to amount water level Is
loweredYlow static level Work st&rt&d..z2jFLx—WX CoZleted...
Was a pump test made? Yes 0 No Vr'lf yes.by whom?...._ ... ... ..
Yield: gal./min. with ft. drawdown after hra. WELL DRILLER'S STATEK&i .Z' '2
This well was drilled under my jurisdiction and this report is
• true to the beat of my knoWledge &ad--be1J*f.
Recovery data (time taken as zero when pump turned off) (water level
L measured from well top to water level) NAME.. . . .......
Time Water Level Time Water level Time Water Level .....4 jee-i
(Person. Arm, or corporation) (Type or i1t)
.....................................I.................................... ...................................... e 13 4:0,4, 7t...4
Addrm....e ... . .. ......... Jr. .......
. ........ ..... .. ....................... ......................................................
....................................I.................... ..............................................
Dateof t ....... ................... . .............. Iffigned]....... .. ..........................(well .................. ... ..... .......
.......her.
Bailer test 7c_gal./min.with' ra
Artesian flow......................... . ..................4I.Pm. Date.-.._...-_-_--------------------_...--.__.-----
Temperature of water................ Was a chemical analysis made? Yes 0 No LAcense No.......e;'T?5. Date.-I<!... 1941
(USE ADDITIONAL 15111CIErS IT NECESSARY)
APPENDIX C
SLOPE STABILITY
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Onto le: Dynamic Bishop
STABLE Version 9.03.00u
Bishop
TITLE
Dynamic
UNITS (Metric/Imperial) = I
GEOMETRY DEFINITION
POINTS
NO. X Y
1 0.000 0.000
2 50.000 0.000
3 213.000 -90.000
4 263.000 -90.000
5 0.000 -5.000
6 50.000 -5.000
7 213.000 -95.000
8 263.000 -95.000
9 26.300 0.000
10 37.370 0.000
11 48.450 0.000
12 59.520 -5.260
13 70.590 -11.370
14 81.670 -17.490
15 92.740 -23.600
16 103.820 -29.710
17 114.890 -35.830
18 125.960 -41.940
19 137.040 -48.060
20 148.110 -54.170
21 159.180 -60.290
22 170.260 -66.400
23 181.330 -72.510
24 192.410 -78.630
25 203.480 -84.740
26 214.550 -90.000
27 225.630 -90.000
28 236.700 -90.000
LINES
Lo X Hi X SOIL
1 2 1
2 3 1
3 4 1
5 6 2
6 7 2
7 8 2
*Y**Y*****Y**YY*YY*YYY**YY**Y*Y*YY**Y**Y**##*Y*****YY*YY**
SOILS
SOIL NAME LINETYPE-PEN COHESION FRICTION UNIT WT.
rvew user
Project Sharer
Datafile: Dynamic Bishop
1 Soil-1 CONTINUOUS-BLACK 50.00 32.0 130.000
2 Soil_2 CONTINUOUS-BLUE 400.00 40.0 140.000
PORE PRESSURE SPECIFICATION
SOIL PIE20 RU EXCESS
Y/N/P Value Value
1 N 0.000 0.000
2' N 0.000 0.000
PIEZOMETRIC SURFACE
POINT
POINT PORE PRESSURES
POINT PRESSURE
++++««xxxx»+xxx««x««x«+x«x+++«+«++»x++x++x+xxx+«xxxxxx«»xx
SLIP DIRECTION (+/- X) _ +
SLIP-CIRCLES
AUTOMATIC
Circle Centre Grid Extremities
210.400
«x«x»+++xx«xx«+
x +
26.300 * * 236.700
+ +
0.000
X spacing -- no. of cols (max 10)= 10
Y spacing -- no. of rows (max 20)= 20
Grid 1 Circles through point 9
Grid 2 Circles through point 10
Grid 3 Circles through point 11
Grid 4 Circles through point 12
Grid 5 Circles through point 13
Grid 6 Circles through point 14
Grid 7 Circles through point 15
Grid 8 Circles through point 16
Grid 9 Circles through point 17
Grid 10 Circles through point 18
Grid 11 Circles through point 19
Grid 12 Circles through point 20
Grid 13 Circles through point 21
Grid 14 Circles through point 22
APPENDIX D
EROSION CONTROL
GEOTEXTILE FABRIC GEOTEXTILE FABRIC
BET
WRAP AROUND TRENCH 2'x2' WOOD POST AND WIRE MESH
TO AT LEAST ENTIRE OR EQUIVALENT OR BETTER
BOTTOM OF TRENCH 2 6 FT MAX. O.C. 0.5 FT
BEFORE PLACING GRAVEL 2'x2'x5' WOOD POST OR I�-- 6 FT
12' DEEP, 8' WIDE TRENCH EQUIVALENT OR BETTER EXISTING
FILLED WITH 3/4' TO 1 1/2', GROUND SURFACE
WASHED GRAVEL 2 T
DIRECTION OF — 2.5 FT 12' DEEP, 8' WIDE
WATER FLOW GROUND SURFACE TRENCH FILLED WITH 1 T
12' 3/4' TO 1 1/2' t 2.5 FT
T 2.5 FT WASHED GRAVEL g• BOTTOM EXTENTS OF—."7
GEOTEXTILE FABRIC SILT FENCE - DETAIL
SILT FENCE - CROSS SECTION N.T.S.
N.T.S. HAY OR STRAW MATTING
ENERAL NOTES- 1. STRAW SHALL BE AIR DRIED, AND FREE FROM WEED SEEDS AND
COARSE MATERIAL.
SHOULD THE TEMPORARY EROSION AND SEDIMENT CONTROL MEASURES SHOWN ON 2, APPLY AT APPROXIMATELY 75 TO 100 POUNDS PER 1000 SQUARE
HESE PLANS PROVE TO BE INADEQUATE DURING CONSTRUCTION, THE CONTRACTOR FEET OF GROUND,
HALL INSTALL ADDITIONAL EROSION AND SEDIMENT CONTROL FACILITIES. 3. MINIMUM THICKNESS SHALL BE 2 INCHES.
ALL EROSION AND SEDIMENT CONTROL FACILITIES AND DEVICES SHALL BE 4. HAY OR STRAW IS SUBJECT TO BLOWING. KEEP MOIST OR TIED
NSPECTED DAILY AND IMMEDIATELY MAINTAINED, IF NECESSARY, DOWN.
ALL EROSION AND SEDIMENT CONTROL FACILITIES AND DEVICES SHALL BE LEFT IN
LACE UNTIL THE UPSLOPE AREAS HAVE BEEN PERMANENTLY STABILIZED. PERMANENT EROSION CONTROL NOTES-
EMPORARY EROSION CONTROL NOTES+ SEEDING FOR RAW SLOPES
OR ALL AREAS WHICH HAVE BEEN STRIPPED OF VEGETATION OR EXPERIENCED LAND 1. BEFORE SEEDING, INSTALL NEEDED SURFACE RUNOFF CONTROL
ISTURBING ACTIVITIES, AND WHERE NO FURTHER WORK IS ANTICIPATED FOR A MEASURES SUCH AS GRADIENT TERRACES, INTERCEPTOR DIKES,
ERIOD EXCEEDING THE LISTED CRITERIA BELOW, ALL DISTURBED AREAS MUST BE SWALES, LEVEL SPREADERS AND SEDIMENT BASINS.
MMEDIATELY STABILIZED WITH MULCHING, GRASS PLANTING OR OTHER APPROVED 2. THE SEED BED SHALL BE FIRM WITH FAIRLY FINE SURFACE,
R❑SION CONTROL TREATMENT APPLICABLE TO THE TIME OF YEAR. GRASS SEEDING FOLLOWING SURFACE ROUGHENING. PERFORM ALL OPERATIONS ACCROS
LONE WILL ONLY BE ACCEPTABLE DURING THE MONTHS OF APRIL THROUGH OR PERPENDICULAR TO THE SLOPE.
EPTEMBER. HOWEVER, SEEDING MAY PROCEED WHENEVER IT IS IN THE INTEREST OF 3. SEEDING RECOMMENDATIONS, AS SHOWN BELOW, AND SHOULD BE
HE OWNER/CONTRACTOR, BUT MUST ALSO BE AUGMENTED WITH MULCHING, NETTING APPLIED AT THE RATE OF 120 POUNDS PER ACRE.
R OTHER APPROVED TREATMENT. 4. SEED BEDS PLANTED BETWEEN MAY 1 AND OCTOBER 31 WILL
REQUIRE IRRIGATION AND OTHER MAINTENANCE AS NECESSARY TO
RY SEASON (MAY 1 THRU SEPTEMBER 30) -- THE CLEARING OF LAND, INCLUDING THE FOSTER AND PROTECT THE ROOT STRUCTURE.
EMOVAL OF EXISTING VEGETATION OR OTHER GROUND COVER, MUST BE LIMITED TO 5. SEED BEDS PLANTED BETWEEN NOVEMBER 1 AND APRIL 30,
NLY AS MUCH LAND AS CAN RECEIVE APPROPRIATE PROTECTIVE COVER OR BE ARMORING OF THE SEED BED WILL BE NECESSARY, (e.g.,
THERWISE STABILIZED, AFTER HAVING BEEN CLEARED OR OTHERWISE DISTURBED , GEOTEXTILES, JUTE MAT, CLEAR PLASTIC COVERING).
Y NO LATER THAN SEPTEMBER 30 OF A GIVEN YEAR, UNLESS IMMEDIATE 6. FERTILIZERS ARE TO BE USED ACCORDING TO SUPPLIERS'
TABILIZATION IS SPECIFIED IN THE EROSION AND SEDIMENT CONTROL PLAN, ALL RECOMMENDATIONS. AMOUNTS SHOULD BE MINIMIZED, ESPECIALLY
REAS CLEARED OR OTHERWISE DISTURBED MUST BE APPROPRIATELY STABILIZED ADJACENT TO WATER BODIES AND WETLANDS.
HROUGH THE USE OF MULCHING, NETTING, PLASTIC SHEETING, EROSION BLANKETS,
REE DRAINING MATERIAL, ETC., BY SEPTEMBER 30 OR SOONER PER THE APPROVED USE THE FOLLOWING RECOMMENDED SEED MIXTURE FOR EROSION
LAN OF ACTION. UNLESS OTHERWISE APPROVED BY THE COUNTY, SEEDING, CONTROL, OR A COUNTY APPROVED ALTERNATE SEED MIXTURE,
ERTILIZING AND MULCHING OF CLEARED OR OTHERWISE DISTURBED AREAS SHALL BE
ERFORME➢ DURING THE FOLLOWING PERIODS- MARCH 1 TO MAY 15, AND AUGUST 15 TO PROPORTIONS PURITY GERMINATIO
CTOBER 1. SEEDING AFTER OCTOBER 1 WILL BE DONE WHEN PHYSICAL COMPLETION NAME BY WEIGHT(%) (%) (%)
F THE PROJECT IS IMMINENT AND THE ENVIROMENTAL CONDITIONS ARE CONDUCIVE
❑ SATISFACTORY GROWTH. IN THE EVENT THAT PERANENT STABILIZATION IS NOT REDTOP (AGROSTIS ALBA) 10 92 90
OSSIBLE, AN ALTERNATIVE METHOD OF GROUND COVER, SUCH AS MULCHING, NETTING, ANNUAL RYE (LOLIUM MULTIFLORUM) 40 98 90
LASTIC SHEETING, EROSION BLANKETS, ETC., MUST BE INSTALLED BY NO LATER THAN CHEWING FESUE 40 97 80
EPTEMBER 30. (FESTUCA RUBRA COMMUTATA)
(JAMESTOWN, BANNER, SHADOW, KOKET)
N THE EVENT THAT CONSTRUCTION ACTIVITIES OR OTHER SITE DEVELOPMENT WHITE DUTCH CLOVER 10 96 90
CTIVITIES ARE DISCONTINUED FOR AT LEAST 4 CONSECUTIVE DAYS, THE (TRIFOLIUM REPENS)
WNER/CONTRACTOR SHALL BE RESPONSIBLE FOR THE INSPECTION OF ALL EROSION
ND SEDIMENT CONTROL FACILITIES IMMEDIATELY AFTER STORM EVENTS, AND AT MULCHING
EAST ONCE EVERY WEEK. THE OWNER/ CONTRACTOR SHALL BE RESPONSIBLE FOR
HE MAINTENANCE AND REPAIR OF ALL EROSION AN SEDIMENT CONTROL FACILITIES. 1. MATERIALS USED FOR MULCHING ARE RECOMMENDED TO BE WOOD
FIBER CELLULOSE, AND SHOULD BE APPLIED AT A RATE OF 1000
ET SEASON (OCTOBER 1 THRU APRIL 30) -- ON SITES WHERE UNINTERUPTED POUNDS PER ACRE.
ONSTRUCTION ACTIVITY IS IN PROGRESS, THE CLEARING OF LAND, INCLUDING THE 2. MULCH SHOULD BE APPLIED IN ALL AREAS WITH EXPOSED SLOPES
EMOVAL OF EXISTING VEGETATION AND OTHER GROUND COVER, SHALL BE LIMITED GREATER THAN 2-1 (HORIZONTAL-VERTICAL).
0 AS MUCH LAND AREA AS CAN BE COVERED OR STABILIZED WITHIN 24 HOURS IN 3. MULCHING SHOULD BE USED IMMEDIATELY AFTER SEEDING OR IN
HE EVENT A MAJOR STORM IS PREDICTED AND/ OR EROSION AND SEDIMENT AREAS WHICH CANNOT BE SEEDED BECAUSE OF THE SEASON. ALL
RANSPORT OFF-SITE IS OBSERVED. AREAS REQUIRING MULCH SHALL BE COVERED BY NOVEMBER 1.
LL CLEARED OR DISTURBED AREAS SHALL RECEIVE APPROPRIATE PROTECTIVE
OVER OR BE OTHERWISE STABILIZED, SUCH AS MULCHING, NETTING, PLASTIC
MEETING, EROSION BLANKETS, FREE DRAINING MATERIAL, ETC., WITHIN 5 DAYS AFTER
AVING BEEN CLEARED OR OTHERWISE DISTURBED IF NOT BEING ACTIVELY WORKED.
ILT FENCING, SEDIMENT TRAPS, SEDIMENT PONDS, ETC., WILL NOT BE VIEWED AS
DEQUATE COVER IN AND OF THEMSELVES. IN THE EVENT THAT ANY LAND AREA NOT
EING ACTIVELY WORKED REMAINS UNPROTECTED OR HAS NOT BEEN APPROPRIATELY
TABILIZED 5 DAYS AFTER HAVING BEEN CLEARED, ALL CONSTRUCTION ACTIVITY ON
HE SITE, EXCEPT FOR APPROVED EROSION AND SEDIMENT CONTROL ACTIVITY, SHALL
MMEDIATELY CEASE UNTIL SUCH A TIME AS AFOREMENTIONED LAND AREA HAS BEEN
PPROPRIATELY PROTECTED OR STABILIZED.
ILT FENCE
PROJECT/ OWNER/ LOCATION
GEOTEXTILE FILTER FABRIC TYPE SHALL BE PER SPECIFIED IN THE 'STORMWATER MANAGEMENT MANUAL SINGLE FAMILY RESIDENCE
❑R THE PUGET SOUND BASIN,' OR APPLICABLE COUNTY STANDARDS
GEOTEXTILE FILTER FABRIC SHALL BE PURCHASED IN A CONTINUOUS ROLL CUT TO THE LENGTH OF GE❑TECHNICAL REPORT
ACH BARRIER TO AVOID USE OF JOINTS. IF JOINTS ARE NECESSARY, FILTER FABRIC SHALL BE SPLICED SHARER
OGETHER ONLY AT A SUPPORT POST WITH A MINIMUM 6-INCH OVERLAP AND SECURELY FASTENED AT PARCEL 12230-77-00060
OTH ENDS TO THE POST. MASON COUNTY, WASHINGT❑N
3. STANDARD FILTER FABRIC SHALL BE FASTENED USING V STAPLES OR TIE WIRES (HOG RINGS) 2 4 IN
PACING.
, POSTS SHALL BE SPACED AND PLACED AT DEPTHS INDICATED IN THE DETAILS ON THIS SHEET, AND ENGINEER,
RIVEN SECURELY INTO THE GROUND. ENVIROTECH ENGINEERING
WIRE MESH SHALL BE 2'X2'X14 GAUGE OR EQUIVILENT. THE WIRE MESH MAY BE ELIMINATED IF PO BOX 984
XTRA-STRENGTH FILTER FABRIC (MONOFILAMENT), AND CLOSER POST SPACING IS USED. BELFAIR, WASHINGTON 98528
A TRENCH SHALL BE EXCAVATED ACCORDING TO THE DETAILS ON THIS SHEET ALONG THE LINE OF THE 360-275-9374
❑STS AND UPSLOPE FROM THE SILT FENCE.
. SILT FENCES SHALL BE LOCATED DOWNSLOPE FROM THE CLEARING LIMITS OF THE PROJECT, EROSION CONTROL
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.
Applicant's Name: J
Permit# ('` 00s �arcel# ��v
Date(s) of the Document(s)reviewed: O 01-1
(1) (a)A discussion of general geologic conditions in the vicinity of the proposed development,
OK? V Comment:
(b) A d�ssion of specific soil types
OK? Comment:
(c) A dis ussion of ground.water conditions
OK? Comment: -
(d) A iscussion of the upslope geomorphology
OK? Comment:
(e) A dlispussion of the location of upland waterbodies and wetlands
OK? Comment:
(f) A discussion of history of landslide activity in the activity in the vicinity, as available in the
refe. ced maps and records
OK? Comment:
(2) A site pla which identifies the important dp--vpJopment and geologic features.
OK? Comment:
(3) Locations and logs of exploratory h I s or probes.
OK?U Comment:
(4) The area of the proposed development, the boundaries of the hazard, and associated buffers and
setbacl 'Ahall be delineated(t�sides, nd toe)on a geologic map of the site.
OK? I Comment: /
(5) A minimum of one cross section at a scdle which adequately depicts the subsurface profile, and
which incorporates the details of proposed grade changes.
OK?`L Comment:
(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 ss ety factor is 1.1. and the quasi-static analysis coeffients should be a value of 0.15.
OK?�_Comment:
(7) (a)Appropriate restrictions on placement of drainage features
OK? 11 Comment:
(b) Appro➢riate restrictions on placement of septic drain fields
OK? ,Comment:
(c) AppVriate restrictions on placement of compacted fills and footings
OK?_I Comment:
(d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other
slopes on the property.
Page 1 of 2 Form Effective June 2008
OK? `' Comment:
r (e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of
other lopes on the property.
OK? Comment:
(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 ve etation removal.
OK? mment:
(9) Recommen ations 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 fromerosion, landslides and harmful construction methods.
OK?_ Comment:
(10) An analysis of both on-site and off-site impacts of the proposed development.
OK? _Comment:
(11) Specifications of final development conditions such as, vegetative management, drainage,
erosion trol, and buffer widths.
OK? Ir Comment:
(12) Recommendations for the preparation of structural mitigation or details of other proposed
mitigatiUn
OK?_�_Comment:
(13) A site map drawn to scale showing the property boundaries, scale, north arrow, and the location
and nature f existing and prop se develop ent on the site.
OK?Comment: /
Are the Documents signed and stamped?
Type and #of License: w -�
If not approved, what is the next action/recommendation f r further action?
7�'T 14 r
cve .
Reviewed by , on
Time spent in review:
SECOND REVIEW/UPDATE:
Reviewed by , on
Time spent in second review:
THIRD REVIEW/ UPDATE:
Reviewed by , on
Time spent in third review:
Disclaimer: Mason County does not certify the quality of the work done in this Geological Assessment
Page 2 of 2 Form Effective June 2008
(8/12/2011) Genie McFarland -Sharer checklist pl.pdf Page 1
NIP-son County Department of Community Development
Submidaii-jeck- or a Geoischnical Report
Instructions:
This checkfist must be suL-mitted with a GeotecKnical Report and completec,signed,and stam.pa-d by the
licensed proffesslonal(s)who prepared the Geotechnical Report for review by Mason County pursuant to
wt the lasso,:,-aij-pty Resvirce Ordkance art Y Nan be r fxmd to appficabla the report should explain
the basis for the conclusion.
-77--OC'06'0
ApplicantlOwner .7�r Partug#
Site Address
(1) (a)A discussion of generalaebiogic conditions in the vicirilly of the proposed development,
3
Located on page(s)
(b) A discussion or,spamra types
Located on pagefs',
(c) A discussion of ground water conditions
7 Located an page(s)
(d) A discussion of the upslope geamorpholog
y
Located on page(s)
el A discussion of flie location of upland watertiodies and wetlands
Located on page(s)
() A d1sc=iion.jz hisrory of landslide activity in the activity in the ificinity,as available in the
referenced maps records
Localod or.page(s) 49
(2) A site plan whichidwfiffe5.the Impor6ritt development and geologic features.
Located m, Mapfsj' (Ar
(3) Locations and logs of expi ratoiry holes or probes
Svc On k-ij
M,a P (14a P
(4) The area of the proposed development,the boundaries of the hazard,and associated buffers and
sethecks§haff be delineated(top, th sides,and toe)on a'geologfe clap of the site.
L d on Map(s). 11
0,114
(5) Aminimurn of one cross section at a scale which adequately depicts the subsurface profile,and
%rhich incorporates the datalla of prop amde changes.
�-Oce�co map(s" 4
(6) —,,;p tion end reeafts of s Stability an at) j3arT3 tied lb r batf stafl and se-2 t-I mift.1 r.
conditions.Analysis shoWd exainLne worst cas--ftftres.The arial�sls should include the
Srnpllfied stshqp's M'athod 4 Ckctes--Dhe alkiftnum sbeac safety is f.5.the minimtm.
mismic safety factor is 1.1.mid the cruasi-staffo analysis caeffients should be a v--Iue of 0-15.
Lacaiedonpage(s) /0.. 49p, c--.::
(7) (s)Appropriate restrictions an placement of drainage features
Wcaisd on page(s) /(7
(b) =Aor! r;ata--str;cdons c—nplacement or septk-drain fields
Looted on, me(s) /0
(c) Apprcipnale restrictions an placerneni of compacted r-ills and footings
77
Located on Page(s) /
Page I of 2 Form Effeadve June 2008
Disclaimer:Mason County does nof certify the qua!fhr of the work done in this
(8/12/2011) Genie McFarland -Sharer checklist p2.pdf Page 1
(d) Recommended buffers from the landslide hazard areas shoreline bluffs and Me laps of oilier
siopas on this propaq-
Located on paga(s) /s
(e) Recommended setbacks fromthe landslide hazard areas shoreline bluffs and the tops of
otter siopes to ibe property.
Located on page(s) jh
(S) rtecommandations for the preparation of a detailed clearing and grading pia. xitici:3 sx iiii tsuy
identifies vegetation to be removed,a schedule for vegetation removal and replanting,and the
method of vegetation rem, al.
Located on pages, �L+
(9) Recommendations for the preparation of a detailed temporary erosion control plan which
identifies the speck mitigating measures to be implemented during construction to protect the
slope-,om arr sion,landslides and ham€ui construction methods.
Located on pages) 1J
NO) An analysis of both or,-siie and off-siie impacs of tide proposed development.
Located on pages) r j
(;i) Specifications of finai developn-£eni candiiions such as,vegetative management,drainage,
erosion contrai,and bufffr widths.
Located on page(s) l if
(12) Recommendations for the preparation of structural mitigation or details cf olther proposed
nafigaficn. f
Located on pages.
(13) R siie map drawn to scale showing tine property boundaries,scale,-north anw,and#'a iocation
and nature of existing and
ff--pro,{j{Sed development on the site.
i:.a`iC:QiL'�ZI on
hereby�under tssnaifid of
perjury that i am a ci,il eri ear iicersed in lire Seta of iniasningior:wish imowiedgt±of
9e0te0ha!CsVgeoiog or a gaokvist or a-.WC.--sag gec4agist
w itq r -uIle Sid` of
�ifSa�S. �6f [CSL£C i.v......j. � 33
Report,dated T,i? 2 d Z�f t ,and entitled /'t�i i"ef^
mwa, im mqu �it ol,
and tnm,'a at tie assessirtent
demonstrates conclusively that the risks posed by the landslide hazai-d can be mitigated L'wo the
.nrdt3ciiti gEDiF.w'Fs'77Eai EtG'Si}' i rer,.tR nn af -ark r2Cid i:�a^F�s cam Midi td;SiYfSSt a manner as
:_... �€3Q4S S
vv
Page 2 of 2 Form Effective dune 2008
Disc almen Masc^County aces not ce•tif,r'he qualtty of the war k hone In this Cade `j�af Ran _