HomeMy WebLinkAboutGEO2018-00037 GEO-Tech Review - BLD Engineering / Geo-tech Reports - 4/5/2016 SUN
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PLANNING
Gcotechnical Report
for
Spaterna Single Family Residence
XXX Great Bend Road
Parcel No. 32232-32-90142
Mason County, Washington
ton
April 5, 2016
Project#1643
Prepared For:
Al Spaterna CLYpE S
PO Box 4167 �`� C,4"A1f; �9��2
Bremerton, Washington 98312
Prepared By:
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Envirotech Engineering
PO Box 984 �oNA`.ti
Belfair, Washington 98528
Phone: 360-275-9374
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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
2.2.1 Upslope Geomorphology.............................................................................................................................3
2.3 SURFACE DRAINAGE.............................................................................................................................................3
2.3.1 Upslope Water Bodies..................................................................................................................................3
2A 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 LANDSLIDE HAZARDS...........................................................................................................................................8
4.1.1 Slope Stability Analysis.............................................................................................................................11
4.2 EROSION..............................................................................................................................................................11
4.3 SEISMIC CONSIDERATIONS AND LIQUEFACTION.................................................................................................11
4.3.1 Liquefaction...............................................................................................................................................11
4A LANDSLIDE,EROSION AND SEISMIC HAZARDS CONCLUSIONS...........................................................................12
4.5 LATERAL EARTH PRESSURES..............................................................................................................................12
4.6 ON-SITE AND OFF-SITE IMPACTS.......................................................................................................................12
5.0 ENGINEERING RECOMMENDATIONS.........................................................................................................13
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
5.2.2 Placement and Compaction of Native Soils and Engineered Fill............................................................15
5.13 Retaining Wall Backfill.............................................................................................................................16
5.2.4 Wet Weather Considerations.....................................................................................................................16
5.2.5 Building Pads.............................................................................................................................................16
5.3 SURFACE AND SUBSURFACE DRAINAGE..............................................................................................................16
5.4 VEGETATION BUFFER AND CONSIDERATIONS....................................................................................................17
5.5 TEMPORARY AND PERMANENT EROSION CONTROL...........................................................................................17
5.6 SEPTIC DRAINFIELDS..........................................................................................................................................18
5.7 STRUCTURAL MITIGATION.................................................................................................................................18
6.0 CLOSURE..............................................................................................................................................................19
Appendix A-Site Plan
Appendix B-Soil Information
Appendix C—Erosion Control
Appendix D—Drainage Details
APPENDIX A
SITE PLAN
1.0 INTRODUCTION
Envirotech Engineering (Envirotech) has completed a geotechnical investigation for a planned
single family residence located at XXX Great Bend Drive, identified as parcel number 32232-32-
90142, Union, Mason County, Washington. See the vicinity snap on the following page for a
general depiction of the site location.
The geotechnical investigation was conducted at the request of the proponent of the property,Al
Spaterna, in support of the proposed development as detailed below. The proposed development,
as provided herein, and the surrounding area that may influence the development, is identified
throughout this report as the Project.
An initial geological/ geotechnical evaluation of the Project was conducted by Envirotech with
the property owner or owner's representative on March 15, 2016. It was determined that natural
slopes between 15% and 40% were present within 300 feet of the Project. Due to the site
requiring drainage mitigation and earthwork recommendaitons, a geotechnical report was
prepared pursuant to landslide hazard areas of the Mason County Resource Ordinance(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 during the geotechnical investigation. Other Project information was obtained by
Envirotech. Except for a driveway and building pad, the site is undeveloped. 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;
Envirotech Engineering XXX Great Bend Road
PO Box 984 Page I Parcel 32232-32-90142
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5.2016
• 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 XXX Great Bend Road
PO Box 984 page 2 Parcel 32232-32-90142
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5,2016
2.0 SURFACE CONDITIONS
Information pertaining to the existing surface conditions for the Project was gathered on March
15, 2016 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
The property is accessed from Great Bend Drive, an existing paved roadway. The Project is
currently vacant and partially developed land as previously mentioned. The access road extends
near the north property line, and rural residential development borders the property to the south.
Beyond the property, rural residential development exists. Vegetation on and near the Project
consists primarily of secondary growth firs, maples, 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. Descending slopes exceeding 15% are located on and beyond the property.
Average slope grades are approximately 22%with a vertical relief of approximately 46 feet.
2.2.1 Upslope Geomorphology
Ascending grades are generally located to the northwest of the planned development.
This slope is relatively minor within 300 feet of the Project, with no apparent slope
grades of at least 15%.The upland area of the property is situated on a hillside and crest.
Landforms are primarily of glacial origin with centuries of weathering overburden.
Additional geomorphology that is pertinent to both upslope and downslope areas are
provided in the Subsurface Investigation Section of this report.
2.3 Surface Drainage
Runoff originating upslope of the development is mostly diverted away from the property by
accommodating topography. However, moderate runoff enters the property that could affect the
building envelope.
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 XXX Great Bend Road
PO Box 984 page 3 Parcel 32232-32-90142
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5,2016
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:
• 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.
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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Envirotech Engineering XXX Great Bend Road
PO Box 984 page 4 Parcel 32232-32-90142
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5,2016
APPENDIX B
SOIL INFORMATION
3.0 SUBSURFACE INVESTIGATION
Information on subsurface conditions pertaining to the Project was primarily gathered on March
16, 2016 by a representative 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 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 extending to depths of up to 5 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.
Soil samples were not obtained from this project. Envirotech measured the relative density of the
near-surface in-situ soils by gauging the resistance of hand tools. Within testing locations, field
testing results generally indicated loose to medium dense soils in the upper 60 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, QB. 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 Skokomish Valley and Union 7.5-minute Quadrangles,Mason County,
Washington" by Michael Polenz, Jessica L. Czajkowski, Gabriel Legorreta Paulin, Trevor A.
Conteras, Brendon A. Miller, Maria E. Martin, Timothy J. Walsh, Robert L. Logan, Robert J.
Carson, Chris N. Johnson, Rian H. Skov, Shannon A. Mahan, and Cody R. Cohan, June 2010,
provides the following caption(s)for the project area:
Vashon lodgment till—Unsorted,unstratitied mix of clay,silt,sand,gravel,and sparse boulders;
c�9t typically supported by a sandy matrix;mostly gray;compact,resembling concrete.
Envirotech Engineering XXX Great Bend Road
PO Box 984 page 5 Parcel 32232-32-90142
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5,2016
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3.3 Specific Subsurface Conditions
The following subsurface conditions are estimated descriptions of the Project subgrade utilizing
information from the depth of penetration at all testing, sampling, observed and investigated
locations. Soils for this project were primarily described utilizing the Unified Soil Classification
System(USCS)and the Soil Conservation Service(SCS)descriptions.
The Project is currently composed of native soils without indications of borrowed fill. However,
native fill soils were observed on the downslope side of the building pad. Within test pit
locations, soils within the upper 5 feet of natural ground were observed to be moist, brown silty
sand with gravel (SM). 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 Alderwood Gravelly Sandy
Loam, Ac, with 15% - 30% slopes. The soil designations are depicted in the aerial photograph
below,and descriptions are provided in Appendix B of this report.
Envirotech Engineering XXX Great Bend Road
PO Box 984 page 6 Parcel 32232-32-90142
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5,2016
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APPENDIX C
EROSION CONTROL
4.0 ENGINEERING ANALYSES AND CONCLUSIONS
The following sections present engineering assessments and conclusions concerning the Project.
These conclusions have been made available based on the planned construction activities as
outlined in the Introduction Section of this report; general observations of drainage and
topography as summarized in the Surface Conditions Section; and, soil conditions that were
identified by the field investigation and soils testing as outlined in the Subsurface Investigation
Section. Conclusions for the Project that is provided herein, includes pertinent information for
landslide,erosion and seismic hazards.
4.1 Landslide Hazards
For the planned development, as provided in the Introduction Section of this report, it is
Envirotech's opinion that the proposed development is not subjected to or cause adverse impacts
to a landslide hazard area or its associated buffer or setback as defined in the MCRO. This
conclusion is based on the contents provided in this report.
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. 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.
Maintenance of the slope should be completed if the situation does arise in order to prevent the
possibility of further surficial or deep seated slope movements that may be damaging to life or
property.
According to the Coastal Zone Atlas of Mason County, Washington, the Project is within and
near terrain labeled 'Stable' and 'Intermediate' regarding potential landslide activity. Stable
slopes are generally not prone to landslides due to small grades and accommodating geology.
Historically, intermediate terrains have no known landslides. A site specific analyses and
conclusions concerning the slopes are presented herein. A Stability Map from the Coastal Zone
Atlas for the general area of this Project may be found below.
Envirotech Engineering XXX Great Bend Road
PO Box 984 page 8 Parcel 32232-32-90142
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5,2016
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According to the Resource Map from the Washington State Department of Natural Resources
(DNR), the Project is 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 XXX Great Bend Road
PO Box 984 page 9 Parcel 32232-32-90142
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5,2016
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Envirotech Engineering XXX Great Bend Road
Apr PO Box 984 page 10 Parcel 32232-32-90142
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5,2016
4.1.1 Slope Stability Analysis
A slope stability analysis was not performed for this project. This is due to the existing
natural slopes with grades less than 40%.
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 within terrain labeled `highly erodible.' This Project is 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.
4.3 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 5 miles to the northwest of this
Project. This information is based on the USGS Quaternary Fault and Fold Database for the
United States.
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
Envirotech Engineering XXX Great Bend Road
PO Box 984 page 11 Parcel 32232-32-90142
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5,2016
caused from liquefaction include submerged, confined, poorly graded granular soils (i.e.
gravel,sand, silt). Although gravel-and silt-sized soil particles could be problematic,fine
and medium grained sands are typically subjected to these types of seismic hazards. No
significant saturated sand stratifications are anticipated to be within the upper 50 feet of
the subsoil for this Project.
4.4 Landslide,Erosion and Seismic Hazards Conclusions
DNR did not indicate historic landslide activity near the Project. Mapped slope conditions, as
delineated by the Departments of Ecology and/ or Natural Resources, were considered in our
slope stability assessment. Based on the proximity and severity of mapped delineations with
respect to the proposed development, results of the aforesaid slope stability analysis, observed
surface conditions, and other pertinent information, it is our opinion that the proposed
development may occur in accordance with the recommendations in this geotechnical report.
4.5 Lateral Earth Pressures
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.
4.6 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.
OF Envirotech Engineering XXX Great Bend Rind
PO Box 984 page 12 Parcel 32232 32 90
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5,201.6
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. 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 12 inches shall be placed at a minimum of 12 inches below the existing
ground surface, and/ or 12 inches below bottom of existing onsite fill 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 XXX Great Bend Road
PO Box 984 page 13 Parcel 32232-32-90142
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5,2016
5.1.2 Settlement
Total and differential settlement that a structure will undergo depends primarily on the
subsurface conditions, type of structure, amount and duration of pressure exerted by the
structure, reduction of pore water pressure, and in some instances,the infiltration of free
moisture. Based on the expected native soil conditions, anticipated development, and
construction abides by the recommendations in this report, the assumed foundation
system may undergo a maximum of 1.0 inch total settlement, and a maximum differential
settlement of 0.75 inch.
5.1.3 Concrete Slabs-on-Grade
Interior slabs, if utilized, should be supported on a minimum of 4 inches of compacted
coarse, granular material (Retained on U.S. Sieve #10 or greater) that is placed over
undisturbed, competent native subgrade or engineered fill per the Earthwork
Recommendations Section below.
The recommendations for interior concrete slabs-on-grade as presented herein are only
relevant for the geotechnical application of this Project. Although beyond the scope of
this report, concrete slabs should also be designed for structural integrity and
environmental reliability. This includes vapor barriers or moisture control for mitigating
excessive moisture in the building.
5.2 Earthwork Construction Recommendations
Founding material for building foundations shall consist of undisturbed native soils to the
specified foundation depths. Compacted engineered fill, or selective re-compacted native soils
may be used to the extents provided in this Earthwork Construction Recommendations Section.
The following recommendations include excavations, subgrade preparation, type of fill, and
placement of fill for building foundations.
5.2.1 Excavation
Excavation is recommended to remove any excessive organic content, fill or other
deleterious material, if present, beneath foundations and to achieve appropriate
foundation depth. Additional sub-excavation will be required for this Project if the soils
below the required foundation depth are loose, saturated, not as described in this report,
or otherwise incompetent due to inappropriate land disturbing,or excessive water trapped
within foundation excavations prior to foundation construction. All soils below the
bottom of the excavation shall be competent, and relatively undisturbed or properly
compacted fill. If these soils are disturbed or deemed incompetent, re-compaction of
these soils below the anticipated footing depth is necessary. Excavations shall be
completely dewatered, compacted, and suitable before placement of additional native
soil,engineered fill or structural concrete.
Envirotech Engineering XXX Great Bend Road
PO Box 984 page 14 Parcel 32232-32-90142
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5,2016
5.2.2 Placement and Compaction of Native Soils and Engineered Fill
For engineered fill or disturbed native soils that will be utilized as fill material directly
beneath foundations, observation and/ or geotechnical testing is required prior to
foundation construction. The following placement and compaction requirements are
necessary.
For disturbed native soils or engineered fill beneath foundations, limits of compacted or
re-compacted fill shall extend laterally from the bottom edge of the foundation at a rate of
one horizontal foot for each foot of or compacted re-compacted fill depth beneath the
r r r
foundation. See the illustration below.
FOOTING
COMPACTED
NATIVE SOILS
OR ENGINEERED t
FILL t
UNDISTURBED SUBGRA])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
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 for both 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. Permanent cut
and fill slopes shall be limited to a slope of 2:1, unless otherwise approved by an
engineer.
Envirotech Engineering XXX Great Bend Road
PO Box 984 page 15 Parcel 32232-32-90142
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5,2016.
APPENDIX D
DRAINAGE DETAILS
5.2.3 Retaining Wall Backfill
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
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 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 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 Mason County 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.
Envirotech Engineering XXX Great Bend Road
PO Box 984 page 16 Parcel 32232-32-90142
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5,2016
' Both footing perimeter drains and roof drains are required for this Project. Subsurface water
intercepted in the footing perimeter drains, and stormwater collected from roof drains shall be
separately tight-lined to the recommended outlet. Roof and foundation drains may share a
tightline if an above ground drainage outlet is allowable and a backflow preventer is installed
within the pipe system in order to prevent roof water from entering the foundation area.
For this project, we recommend that roof dispersion is located to the northwest of the proposed
house,conforming to the Mason County Small Parcel Stormwater Plan.
Subsurface interceptor drains should be located upslope of the proposed structures to mitigate
subsurface water. This may be accomplished by either one of two options. If upslope foundations
are bearing atop very dense hardpan encountered at approximately 5 feet below the ground
surface, then standard footing perimeter drains are sufficient, and should extend to a depth of 6
inches into the hardpan.If the upslope house foundation is bearing near the existing native ground
surface, then an interceptor drain should be constructed 5 to 10 feet upslope from the residence,
and extend at least 6 inches into the underlying hardpan. In addition, we recommend that the
subsurface drain is extended at least 10 feet beyond the building footprint on the upslope side.
For mitigating surface runoff, positive grading from the house per code is sufficient. Additional
grading should be assured so that runoff is directed around the house and beyond. Vegetated flow
paths or riprap may be needed to control erosion from the runoff.
5.4 Building Setbacks and Vegetation Buffer
For this project, we believe that a detailed clearing and grading plan is not warranted unless
Mason County thresholds are exceeded, and basic vegetation management practices should be
adhered to.
It is our opinion that building setbacks or vegetation buffers are not required for this project.This
is based on the planned development following the recommendations provided in this report, and
the property being located outside the influence of potential natural landslides.
5.5 Temporary and Permanent Erosion Control
Erosion control during construction should include minimizing the removal of vegetation to the
least extent possible. Erosion control measures during construction may include stockpiling
cleared vegetation, silt fencing, intercepting swales, berms, straw bales, plastic cover or other
standard controls. Although other controls may be used, if adequate, silt fencing is presented in
this report as the first choice for temporary erosion control. Any erosion control should be located
down-slope and beyond the limits'of construction and clearing of vegetation where surface water
is expected to flow. If the loss of sediments appears to be greater than expected, or erosion
control measures are not functioning as needed, additional measures must be implemented
immediately. See Appendix D for sketches and general notes regarding selected erosion control
measures. The Site 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
Envirotech Engineering XXX Great Bend Road
PO Box 984 page 17 Parcel 32232-32-90142
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5,2016
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.
5.6 Septic Drainfields
The approximate location of the 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 critical slopes. This is also
based on compliance with all recommendations in this report.
5.7 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.
t
Envirotech Engineering XXX Great Bend Road
PO Box 984 page 18 Parcel 32232-32-90142
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5,2016
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
i 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
Robert McNearny,E.I.T. Michael Staten,P.E.
Staff Engineer Geotechnical Engineer
Envirotech Engineering XXX Great Bend Road
PO Box 984 page 19 Parcel 32232-32-90142
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 April 5.2016
NOTES'
1. EROSION CONTROL MAY BE REQUIRED FOR THIS SITE, GENERAL LOCATIONS
ARE DEPICTED, AND ALTERNATIVES MAY BE UTILIZED AS EXPLAINED IN THE SCALE: 1'=8 0'
GEOTECHNICAL REPORT.
2. CONTOURS WERE NOT PREPARED BY A LICENSED LAND SURVEYOR.
CONTOURS WERE EXTRAPOLATED FROM A PUBLIC LIDAR SOURCE, AND 0 20 40 g 0
INCORPORATED FIELD MEASUREMENTS AS EXPLAINED IN THE GEOTECHNICAL
REPORT.
3. BOUNDARIES WERE NOT PREPARED BY A LICENSED SURVEYOR. LOCATIONS
OF SITE FEATURES THAT ARE SHOWN HERE, SUCH AS TOP OF SLOPES, TOE �80
OF SLOPES, WATER FEATURES, ETC.., WITH RELATION TO THE PROPERTY
LINES MUST BE VERIFIED BY THE OWNER. RECOMMENDATIONS IN THE
GEOTECHNICAL REPORT PROVIDE SETBACKS, BUFFERS, DEPTHS, ETC.. WITH
RELATION TO GEOLOGIC FEATURES, NOT PROPERTY LINES, THESE GEOLOGIC
FEATURES MAY BE LOCATED ON THE SUBJECT PROPERTY OR NEIGHBORING 1 7 3± PROPERTY
PROPERTIES. 1�1�0 1300
LINE
�-I
300± \\
TOE OF SLOPE
STABILIZED C❑NSTRUCTI❑N T SILT FENCE
ENTRANCE, SEE DETAI ^� T P 2 SEE DETAILS.
PROPOSED SEPTIC
�o 0 o DRAINFILED
0
0).1
N
PROPOSI REA FOR
0,R❑❑F R N❑F ISPER PROPOSED STRUCTURE
0
ADDITI❑NAL DRAINAGE
443± MITIGATION UPSLOPE OF
STRUCTURE PER REPORT.
ALSO, SEE DETAILS.
NOTE, ILDING SETBACKS OR PROJECT/ OWNER/ LOCATION,
VEGETAT ON BUFFERS NOT SINGLE FAMILY RESIDENCE
EXISTING DRIVEWAY REC❑MMENDED PER REPORT GE❑TECHNICAL REPORT
SPATERNA
XXX GREAT BEND ROAD
VEGETATE ALL DENUDED AREAS LEGEND PARCEL 32232-32-90142
PER EROSION CONTROL R❑L MASON COUNTY WASHINGTON
TEMPORARY ENGINEER,
EROSION CONTROL ENVIR13TECH ENGINEERING
PO BOX 984
SLOPE INDICATOR BELFAIR, WASHINGTON 98528
rg� EXISTING CONTOUR 360-275-9374
TP TEST PIT SITE PLAN
GEOTEXTILE ABOVE
NATIVE COVER DRAIN R❑CK
6. 1/2' - 1 1/2'
e .
WASHED DRAIN ROCK
PROPOSED
FOUNDATION
` F❑UNDATI❑N
12' MIN
4-INCH PVC PERFORATED PIPE (CLASS 200 OR
BETTER)
43
20'
FOOTING DIRECTLY
ON HARDPAN
FO❑TING PERIMETER DRAIN DETAILS
N.T.S.
NOTESi
1) OUTLET PIPES SHOULD SLOPE 2%.
2) ROOF DRAINS SHOULD NOT TIE INTO FOUNDATI❑N DRAIN
SYSTEM.
3) QUARRY SPALL SHOULD BE PR❑VIDED AT THE DRAINAGE
OUTLET,
4) DRAINAGE OUTLETS SHALL BE LOCATED ABOVE ANY HIGH
WATER ELEVATION.
5) DRAINAGE SYSTEMS SHALL BE INSPECTED AT LEAST TWICE
PER YEAR, AND MAINTAINED, IF NECESSARY.
5' TO 10'
GROUND SURFACE
2%
PROPOSED FOUNDATION ,; SOIL NOTES
FILTER FABRIC :...HACKFILL '• -6' 1) PROPER SHORING AND SAFETY OF
ABOVE SIDE SLOPES DURING TRENCH
DRAIN ROCK EXCAVATION IS CONTRACTOR'S
RESPONSIBILITY.
2) SLOPES FOR INTERCEPTOR DRAIN
TRENCHES
SHALL BE BETWEEN 0.5% AND 2.0%.
3/4' - 1' 3) LOWER 1/4 OF DRAIN PIPE SHALL
BE UNPERFORATED.
CLEAN
CLE NROCK 4) FILTER FABRIC SHALL BE
DRANON-WOVEN GEOTEXTILE SPECIFICALLY DESIGNED TO IMPEDE
THE MIGRATION OF FINE SOILS.
4' HARDPAN SURFACE
1-14' MIN, PERFORATED PIPE
�{I 2 FT
INTERCEPTOR DRAIN DETAILS
N.T.S.
PROJECT/ OWNER/ LOCATION-
SINGLE FAMILY RESIDENT
GEOTECHNICAL REPORT
SPATERNA
GREAT BEND ROAD, UNION
MASON COUNTY, WASHINGTON
ENGINEER,
ENVIROTECH ENGINEERING
PO BOX 984
BELFAIR, WASHINGTON 98528
360-275-9374
DRAINAGE DETAILS
TEST PIT LOG
TEST PIT NUMBER TP-1
PROJECT: Spaterna Geotechnical Report DATE OF LOG: 3/15/2016
PROJECT NO: 1643 LOGGED BY: MCS
CLIENT: AL Spaterna EXCAVATOR: N/A
LOCATION: Parcel 32232-32-90142, DRILL RIG: None
Mason County, Washington ELEVATION: N/A
INITIAL DEPTH OF WATER: 32" 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 Reddish brown, very moist, loose to
medium dense SILTY SAND with
GRAVEL. Sand is mostly medium. Low
1 plasticity.
2
Groundwater encountered @ 32"
Brown, very moist, loose to medium
3 dense SILTY SAND with GRAVEL. Sand
is mostly medium. Low plasticity.
4
5
Excavation terminated at approximately
5.0 feet
6
7
8
9
10
ENVIROTECH ENGINEERING
This information pertains only to this boring and should not be Geotechnical Engineering
interpreted as being indicative of the entire site.
TEST PIT LOG
TEST PIT NUMBER TP-2
PROJECT: Spaterna Geotechnical Report DATE OF LOG: 3/15/2016
PROJECT NO: 1643 LOGGED BY: MCS
CLIENT: AL Spaterna EXCAVATOR: N/A
LOCATION: Parcel 32232-32-90142, DRILL RIG: None
Mason County, Washington ELEVATION: N/A
INITIAL DEPTH OF WATER: 25" 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 Reddish brown, very moist, loose to
medium dense SILTY SAND with
GRAVEL. Sand is mostly medium. Low
1 plasticity.
Groundwater encountered A 25"
2
SM Reddish brown,very moist, loose to
medium dense SILTY SAND with
GRAVEL. Sand is mostly medium. Low
3 plasticity.
4
5 "
Excavation terminated at approximately
5.0 feet
6
7
8
9
10
ENVIROTECH ENGINEERING
This information pertains only to this boring and should not be Geotechnical Engineering
interpreted as being indicative of the entire site.
VERTICAL AND HORIZONTAL SCALE.
I INCH 40 FEET
0
PR❑P❑SED
H❑USE
MEDIUM DENSE
❑VERBURDEN (GM)
1\
VERY DENSE GLACIAL
TILL
SECTION AzA
PROJECT/ OWNER/ LOCATION.
SINGLE FAMILY RESIDENCE
GE❑TECHNICAL REP❑RT
SPATERNA
GREAT BEND DRIVE, UNION
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
d 002-4
G EO 101 t
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: S?AY E lz f%Permit#: LLB �1 - �����- Parcel#: RL3Z- �Z -90142_
Date(s)of the'Document(s) reviewed: i�Pr' S 701 G
1. (a) A discussion of general geologic conditions in the vicinity of the proposed development,
OK? _Comment:
(b) A discussion of specific soil types
OK? �_Comment:
(c) A discussion of ground water conditions
OK? _Comment:
(d) A discussion of the upslope geomorphology
OK? )o� —Comment:
(e) A discussion of the location of upland waterbodies and wetlands
OK? Comment:
(f) A discus ' n of history of landslide activity in the vicinity, as available in the referenced maps and records
OK? Comment:
2. A site plan that identifies the important development and geologic features.
K? Comment:
3. L cations and logs of exploratory hol or probes.
K? Comment: 71,
r r
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? Comment:
5. minimum of one cross section at a scale which adequately depicts the subsurface profile, and which
i orporates the details of proposed grade changes.
K? / 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 safety factor is 1.1 and the quasi-static
analysis coeffients should be a value of 0.15.
�OK?_ Comment: PfC A J f q d �/q
7. (a) Appropri estrictions on placement of drainage features
OK? Comment:
(b) Appropriate r strictions on plaT nt of septic drain fields
OK?_ Comment:
(c) Appropriate estrictions on placement of compacted fills and footings.
OK? _Comment:
Page 1 of 2 Form Effective June 2008
(d) Recom a ded buffers from the landslide hazard areas shoreline bluffs and the tops of other slopes.
OK? Comment:
(e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of other slopes.
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 vegetation
removal.
OK? Comment:
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? Comment:
10. An analysis of both on-site and off-site impacts of the proposed development.
r
OK?_�Comment:
11. Specifications of final development conditions such as, vegetative management, drainage, erosion control, and
buffer widths.
OK? Comment:
12. Recommendations for the preparation of structural mitigation or details of other proposed mitigation.
OK? Comment:
13. A site map drawn to scale showing the property boundaries, scale, north arrow, and the location and nature of
existin and proposed development on the site.
OK? Comment:
Are the Documents signed and stamped? Y By whom? Rc J��tPl►"'
License#: ��u� License type:��
FIRST REVIEW X Approved ❑ Need more info.
If not approved, what is the next action/recommendation for further action?
Reviewed by on Zso I 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 Geotechnical Report.
Page 2 of 2 Form Effective June 2008
RECr
�f_ I
AUG 0 8 2018
MASON COUNTY Submittal Checklist
) COMMUNITY SEIZ4MAIder Street
PFFBuilding,Nanning,Environmental Health,Community Health Geotechnical Report
Instructions:
This checklist must be submitted with a Geotechnical Report and completed, signed, and stamped by the licensed
professional(s) 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 Al Spaterna Parcel# 32232-32-90142
Site Address XXX Great Bend Road
(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) 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) 8
(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) 10
(7) (a) Appropriate restrictions on placement of drainage features,
Rev. February 2018
------------
r Located on page(s) 16
(b) Appropriate restrictions on placement of septic drain fields,
Located on page(s) 17
(c) Appropriate restrictions on placement of compacted fills and footings,
Located on page(s) 13 and 14
(d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other slopes.
Located on page(s) 17
(e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of other slopes.
Located on page(s) 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) 11
(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) 16-18
(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
Report, dated April 5, 2016, and entitled Spaterna Single
CLYp,s Family Residence, meets all the requirements of the
T
W,Syjy,, Mason County Resource Ordinance, Geologically
Hazardous Areas Section, is complete and true, that the
assessment demonstrates conclusively that the risks
posed by the landslide hazard can be mitigated through
SSIQNAL���i
8112119 the included geotechnical design recommendations, and
that all hazards are mitigated in such a manner as to
prevent harm to property and public health and safety.
Page 2 of 2
Disclaimer:Mason County does not certify the quality of the work done in this Geotechnical Report.