HomeMy WebLinkAboutGEO2020-00048 BLD2020-00786 - BLD Engineering / Geo-tech Reports - 7/20/2020 G
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RECEIVED
JUL 2 3 2020
615 W. Alder Street
Geotechnical Report
Tupper Single Family Residence
374 East Pointes Drive East, Shelton
Parcel No. 12119-50-00155
Mason County, Washington
July 20, 2020
Project#2096
Prepared For:
Jolene Tupper
6585 River Road
Aberdeen, Washington 98520
Prepared By:
Envirotech Engineering
PO Box 984
Belfair, Washington 98528
Phone: 360-275-9374
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,IQMASON COUNTY Submittal Checklist
COMMUNITY SERVICES Geotechnical Report
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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 Jolene Tupper Parcel# 1 21 1 9-50-001 55
Site Address 374 East Pointes Drive East
(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) 9 Page 1 of 37
(7) (a) Appropriate restrictions on placement of drainage features,
Located on page(s) 17
(b) Appropriate restrictions on placement of septic drain fields,
Located on page(s) 18
(c) Appropriate restrictions on placement of compacted fills and footings,
Located on page(s) 15
(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) 16
(8) Recommendations for the preparation of a detailed clearing and grading plan which specifically identifies
vegetation to be removed,a schedule for vegetation removal and replanting,and the method of vegetation
removal.
Located on page(s) 17
(9) Recommendations for the preparation of a detailed temporary erosion control plan which identifies the specific
mitigating measures to be implemented during construction to protect the slope from erosion, landslides and
harmful construction methods.
Located on page(s) 10
(10) An analysis of both on-site and off-site impacts of the proposed development.
Located on page(s) 12
(11) Specifications of final development conditions such as,vegetative management,drainage,erosion control,and
buffer widths.
Located on page(s) 17
(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
cLypE sp Report,dated July 20,2020,and entitled Tupper Single
c�oF WASH q��2 Family Residence, meets all the requirements of the Mason
a County Resource Ordinance,Geologically Hazardous Areas
Section, is complete and true,that the assessment
43043 a cv� demonstrates conclusively that the risks posed by the landslide
D.o FCIS
Fss�o%ALE�G` hazard can be mitigated through the included geotechnical
7/20/2020 design recommendations,and that all hazards are mitigated in
Disclaimer:Mason County does not such a manner as to prevent harm to property and public
certify the quality of the work done in health and safety.
this Geotechnical Report.
Page 2 of 2
TABLE OF CONTENTS
1.0 INTRODUCTION................................................................................................................................. 1
1.1 PROJECT INFORMATION.................................................................................................................... 1
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
2.4 SLOPE AND EROSION OBSERVATIONS...............................................................................................4
3.0 SUBSURFACE INVESTIGATION.....................................................................................................5
3.1 FIELD METHODS,SAMPLING AND FIELD TESTING...........................................................................5
3.2 GENERAL GEOLOGIC CONDITIONS...................................................................................................5
3.3 SPECIFIC SUBSURFACE CONDITIONS.................................................................................................6
3.3.1 Groundwater............................................................................................................................... 7
4.0 ENGINEERING ANALYSES AND CONCLUSIONS......................................................................8
4.1 SLOPE STABILITY...............................................................................................................................8
4.1.1 Slope Stability Analysis..............................................................................................................9
4.2 EROSION............................................................................................................................................10
4.2.1 Shoreline Recession..................................................................................................................10
4.3 SEISMIC CONSIDERATIONS AND LIQUEFACTION..............................................................................11
4.3.1 Liquefaction..............................................................................................................................I f
4.4 LANDSLIDE,EROSION AND SEISMIC HAZARDS CONCLUSIONS........................................................11
4.5 LATERAL EARTH PRESSURES...........................................................................................................11
4.6 ON-SITE AND OFF-SITE IMPACTS.....................................................................................................12
5.1 BUILDING FOUNDATION RECOMMENDATIONS.................................................................................13
5.1.1 Bearing Capacity.......................................................................................................................13
5.1.2 Settlement..................................................................................................................................14
5.1.3 Concrete Slabs-on-Grade..........................................................................................................14
5.2 EARTHWORK CONSTRUCTION RECOMMENDATIONS.......................................................................14
5.2.1 Excavation.................................................................................................................................14
5.2.2 Placement and Compaction of Native Soils and Engineered Fill...........................................15
5.2.3 Retaining Wall Backfill.............................................................................................................16
5.2.4 Wet Weather Considerations....................................................................................................16
5.2.5 Building Pads............................................................................................................................16
5.3 BUILDING AND FOOTING SETBACKS.................................................................................................16
5.4 SURFACE AND SUBSURFACE DRAINAGE...........................................................................................17
5.5 VEGETATION BUFFER AND CONSIDERATIONS.................................................................................17
5.6 TEMPORARY AND PERMANENT EROSION CONTROL.......................................................................18
5.7 SEPTIC DRAINFIELDS........................................................................................................................18
5.8 STRUCTURAL MITIGATION...............................................................................................................18
6.0 CLOSURE.............................................................................................................................................19
Appendix A-Site Plan
Appendix B-Soil Information
Appendix C-Slope Stability
Appendix D—Erosion Control
1.0 INTRODUCTION
Envirotech Engineering (Envirotech) has completed a geotechnical investigation for a planned
single family residence located at 374 East Pointes Drive East, identified as parcel number
12119-50-00155, Mason County, Washington. See the vicinity map on the following page for a
general depiction of the site location.
An initial geotechnical evaluation of the project was conducted by Envirotech on July 13,2020. It
was determined that slopes in excess of 40% with a vertical relief of at least 10 feet were present
within 300 feet of the planned development. Based on this site characteristic, the proposed
development will require a geotechnical report pursuant to Landslide Hazard Areas of Mason
County Resource Ordinance (MCRO) 17.01.100. During the site visit by Envirotech, surface and
subsurface conditions were assessed. After completion of the field work and applicable project
research, Envirotech prepared this geotechnical report which, at a minimum, conforms to the
applicable MCRO.
As presented herein, this report includes information pertaining to the project in this Introduction
Section; observations of the property and surrounding terrain in the Surface Conditions Section;
field methods and soil descriptions in the Subsurface Investigation Section; supporting
documentation with relation to slope stability, erosion, seismic considerations, and lateral earth
pressures in the Engineering Analyses and Conclusions Section; and, recommendations for
foundation, settlement, earthwork construction, retaining walls, erosion control, drainage, and
vegetation in the Engineering Recommendations Section.
1.1 Project Information
Information pertaining to the planned development of the project was provided by the proponent
of the property. The planned development consists of a 1-or 2-story single family residence,new
on-site septic system, and other ancillary features typical of this type of development.
Approximate building footprint and other proposed features with relation to existing site
conditions are illustrated on the Site Map provided in Appendix A of this report.
1.2 Purpose of Investigation and Scope of Work
The purpose of this geotechnical investigation is to assess geological hazards, and evaluate the
project in order to provide geotechnical recommendations that should be implemented during
development. The investigation included characterizing the general project surface and
subsurface conditions, and evaluating the suitability of the soils to support the planned site
activities.
In order to fulfill the purpose of investigation, the geotechnical program completed for the
proposed improvements of the project include:
• Review project information provided by the project owner and/ or owner's
representative;
• Conduct a site visit to document the site conditions that may influence the construction
and performance of the proposed improvements of the project;
• Define general subsurface conditions of the site by observing subsoils within test pits
Envirotech Engineering Geotechnical Report
PO Box 984 page 1 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
and/ or cut banks, review geological maps for the general area, research published
references concerning slope stability, and review water well reports from existing wells
near the project;
• Collect bulk samples,as applicable, at various depths and locations;
• Perform soils testing to determine selected index and/or engineering properties of the site
soils;
• Complete an engineering analysis supported by the planned site alterations, and the
surface and subsurface conditions that were identified by the field investigation, soil
testing, and applicable project research;and,
• Establish conclusions based on findings, and make recommendations for foundations,
drainage, slope stability, erosion control, earthwork construction requirements, and other
considerations.
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Vicinity Map from Mason County Website
Envirotech Engineering Geotechnical Report
PO Box 984 page 2 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
2.0 SURFACE CONDITIONS
Information pertaining to the existing surface conditions for the project was gathered on July 13,
2020 by a representative with Envirotech. During the site visit, the type of geotechnical
investigation was assessed, site features were documented that may influence construction, and
site features were examined that may be influenced by construction. This Surface Conditions
Section provides information on general observations, vegetation, topography, drainage and
observed slope/ erosion conditions for the project and surrounding areas that may impact the
project.
2.1 General Observations
Currently, the property is vacant. 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% appear to be within 300 feet of the
planned development.The maximum critical slope is approximately 92% to nearly vertical with a
vertical relief of about 35 feet.
Ascending grades are generally located to the west of the planned development. These slopes are
relatively minor within 300 feet of the project,with no apparent slope grades of at least 15%.
2.2.1 Upslope Geomorphology
The upland area of the property and beyond is generally situated on a hillside of glacial
origin.
2.3 Surface Drainage
Runoff originating upslope of the development is mostly diverted away from the property by
accommodating topography. Excessive scour, erosion or other indications of past drainage
problems were not observed within the immediate vicinity of the planned development.
2.3.1 Upslope Water Bodies
There are no apparent water bodies or wetlands located upslope from the planned
development that would significantly influence the project.
Envirotech Engineering Geotechnical Report
PO Box 984 page 3 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
2.4 Slope and Erosion Observations
The slope gradients near the project signal a potential landslide or erosion hazard area. Some
indicators that may suggest past slope movements include:
• Outwash of sediments near the bottom of the slope,
• Fissures, tension cracks, hummocky ground or stepped land masses on the face or top of
the slope,and parallel to the slope,
• Fine, saturated subsurface soils,
• Old landslide debris,
• Significant bowing or leaning trees,or,
• Slope sloughing or calving.
Bowing trees were observed on the top of the shoreline slope. The base of the slope has been
undercut by wave action. Seepage and sloughing were also noted during the site visit on the
subject property, with a recent shallow landslide (bluff peel-off) located about 300 feet to the
north of the property. Indications of deep-seated slope problems were not observed during the site
visit.
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Aerial Photo from Mason County Website
Envirotech Engineering Geotechnical Report
PO Box 984 page 4 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
3.0 SUBSURFACE INVESTIGATION
Information on subsurface conditions pertaining to the project was primarily gathered on July 13,
2020 by a representative with Envirotech. Applicable information on field methods, sampling,
field testing, general geologic conditions, specific subsurface conditions, and results from soil
testing are presented in this section of the report. Appendix B of this report includes pertinent
information on subsurface conditions for the project, such as subsoil cross-section(s), test pit
log(s), and applicable water well report(s). Water well reports were utilized to estimate ground
water levels, and if sufficient, were used in identifying subsoil types. Applicable test pit locations
are depicted on the Site Plan provided in the appendix of this report.
3.1 Field Methods,Sampling and Field Testing
Information on subsurface conditions for the project was accomplished by examining soils within
test pits and/ or nearby banks extending to depths of up to 10 feet below the natural ground
surface. Information on subsurface conditions also included reviewing geological maps
representing the general vicinity of the project, and water well reports originating from nearby
properties.
Soil samples were not obtained from this project. Envirotech measured the relative density of the
near-surface in-situ soils by gauging the resistance of hand tools. Within testing locations, field
testing results generally indicated loose to medium dense soils in the upper 48 inches, and very
dense soils from 48 inches to the depth of terminus.
3.2 General Geologic Conditions
In general, soils at the project are composed of materials from glacial advances. The geologic
conditions as presented in the "Geologic Map of Washington," compiled by J. Eric Schuster,
2002 indicates Quaternary sediments, Qg. Quaternary sediments are generally unconsolidated
deposits, and dominantly deposited from glacial drift, including alluvium deposits. This project is
located within the Puget Lowland. Typically, "lower tertiary sedimentary rocks unconformably
overlie the Crescent Formation."as revealed in the Geologic Map. Initial sedimentary rocks were
formed from shales, sandstones and coal deposits from rivers. During the Quaternary period, the
Puget Lowland was covered by numerous ice sheets,with the most recent being the Fraser glacier
with a peak of approximately 14,000 years ago. Upon the glacial retreat, the landscape was
formed by glacial erosion glacial drift deposits.
The "Geologic Map of the Vaughn 7.5-minute Quadrangle, Pierce and Mason Counties,
Washington"by Robert L. Logan and Timothy J. Walsh, December 2007,provides the following
caption(s)for the project area:
Envirotech Engineering Geotechnical Report
PO Box 984 page 5 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
Beach deposits—MA sand.and Vm-ei deposited in thr mtertulal zone.ct residual
pebble-cobble gm el and isobsed boulders on a wave-cut platform.
V ashore dtl—Cnstranfied to moderately suattfied,compact umsosted aucnme of clay ult.san&
and p-d deposited&-*by glanat we.gran to tan_Heath eseryssfiere m sharp contact with
mdedymg um b,does not drain well as peimeabdm and poroun are low:sand and finer grams
im matt x are say angular,pebble-to boulder-um lasts are commonly striated and faceted.
basing angular and(or)rounded edges:boulders are generally disseminated and relatnely rare:
may contain mtetbeds of sand and graset.The surface of thu we is chmactenzed by streamlmed
drumlins,striations and flutes that ace generally hundreds to thousands of feet bag-Angular to
subrormded glacial erratic boulders.consutmg mostly of phw=or metamorphic rock.are
common but disseminated an the surface of this unit.Unit may be capped by a few Feet of
unsorted and mmed Wan.sand and gravel ar by omit 090s.-"ashore bill locally a.,x,older
sediments.Sommg angular umconfarmcbes.Drag Ni ing and horizontal shea img may occur at
the base of Cue till or iaternall}between tayas of tilt,especially is thick deposits.unit Ogt
ranges m dwJmess ftm 0 to at least 50 S_
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Geological Map Department of Natural Resources Washington State
3.3 Specific Subsurface Conditions
The following subsurface conditions are estimated descriptions of the project subgrade utilizing
information from the depth of penetration at all testing, sampling, observed and investigated
locations. Soils for this project were primarily described utilizing the Unified Soil Classification
System(USCS)and the Soil Conservation Service(SCS)descriptions.
Envirotech Engineering Geotechnical Report
PO Box 984 page 6 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
The project is currently composed of native soils without indications of fill. Within test pit
locations, soils within the upper 3 feet of natural ground were generally observed to be moist,
brown silty sand with gravel (SM). Soils below the upper 3 feet layer to a depth of 7 feet were
observed to be mostly grey, low moisture, silty sand with gravel (SM), locally known as hardpan.
Clay hardpan was observed near the base of the slope.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 Sinclair shotty loam, S.,
with 5% - 15% slopes. The soil designations are depicted in the aerial photograph below, and
descriptions are provided in Appendix B of this report.
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Soil Survey From USDA Natural Resources Conservation Service
3.3.1 Groundwater
From the water well report(s) and knowledge of the general area, permanent groundwater
is at least 50 feet directly below the property at the building pad location. Surface seepage
or perched groundwater at shallow depths was not observed on-site, nor indicated on the
well reports.
Envirotech Engineering Geotechnical Report
PO Box 984 page 7 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
4.0 ENGINEERING ANALYSES AND CONCLUSIONS
The following section includes slope stability, erosion, seismic considerations, and impacts to
both on-site and off-site properties.
4.1 Slope Stability
Landslides are natural geologic processes, and structures near slopes possess an inherent risk of
adverse settlement, sliding or structural damage due to these processes. Geotechnical engineering
cannot eliminate these risks for any site with sloping grades because gravity is constantly
inducing strain on the sloping soil mass. Excessive wet weather and/ or earthquakes will
exacerbate these strains. Geotechnical engineering considers excessive wet weather and `design'
earthquakes in order to provide an acceptable factor of safety for developing on or near sloping
terrain with relation to current engineering protocol. These factors of safeties are based on
engineering standards such as defining engineering properties of the soil, topography, water
conditions, seismic acceleration and surcharges. Surface sloughing or other types of surficial
slope movements usually do not affect the deep-seated structural capability of the slope.
However, repeated surficial slope movements, if not repaired, may present a threat to the
structural integrity of the slope.If any slope movement arises,the slope should be inspected by an
engineer. Subsequently,maintenance may be required in order to prevent the possibility of further
surficial or deep seated slope movements that may be damaging to life and property.
According to the Coastal Zone Atlas of Mason County, Washington, the project is within and
near terrain labeled `Stable' and `Unstable' regarding potential landslide activity. Descriptions of
these mapping units may be found in the aforesaid Atlas. A Stability Map from the Coastal Zone
Atlas for the general area of this project is provided below:
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Envirotech Engineering Geotechnical Report
PO Box 984 page 8 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
According to the Resource Map from the Washington State Department of Natural Resources
(DNR), the project is not within terrain labeled `highly unstable' relating to soils. DNR labeled
portions of this project as medium slope instability with relation to slopes. A Resource Map from
the DNR Forest Practices Application Review System is provided below:
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Highly Unstable
m Highly Erodible
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Slops Stability-West
® ® Moderate Scope Instability
1:2.� High Slope Instability
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Resource Map from Washington State Department of Natural Resources Website
4.1.1 Slope Stability Analysis
The Simplified Bishop Method, utilizing `STABLE' software, was used to analyze the
static stability of the site slopes. Seismic conditions were estimated utilizing worst case
scenario values from the static analysis, a quasi-static analysis coefficient of at least 0.15,
and applying the applicable values to STABLE software. Various radii's and center
points of the circle were automatically selected, and produced factor of safeties in a
graphical and tabular format. Worst case scenario values were used in the slope stability
analysis in regards to topography, surcharges, water content, internal friction and
cohesion of the site soils. STABLE software has been repeatedly checked with manual
calculations, and consistently proved to be a very conservative program. The following
soil properties were used in the analysis, and are based on observed conditions, known
geology, and/or published parameters:
Upper 3 feet soil depth
Soil unit weight: 132 pcf
Angle of internal friction: 30 degrees
Cohesion: 200 psf
Envirotech Engineering Geotechnical Report
PO Box 984 page 9 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
Soils below 3 feet in depth
Soil unit weight: 140 pcf
Angle of internal friction: 40 degrees
Cohesion: 400 psf
Based on the slope stability analysis, unacceptable factors of safety could be present on
and near the critical slope,but do not reflect conditions where development is expected to
occur. For this project, at the location of the proposed development, minimum factor of
safeties for static and dynamic conditions were estimated to be at least 1.5 and 1.1,
respectively. See the slope stability information in Appendix C for a depiction of
minimum factors of safety away from the project.
4.2 Erosion
Based on the USCS description of the project soils, the surface soils are considered moderately
erodible. According to the Resource Map from the Washington State DNR, as provided above,
the project is not within terrain labeled `highly erodible.' This project is not within an erosion
hazard area as defined by the MCRO. Erosion hazard areas are those with USDA SCS
designations of River Wash (Ra), Coastal Beaches (Cg), Alderwood Gravelly Sandy Loam on
slopes 15% or greater (Ac and Ad), Cloquallum Silt Loam on slopes 15% or greater (Cd),
Harstine Gravelly Sandy Loam on slopes 15% or greater (Hb), and Kitsap Silt Loam on slopes
15%or greater(Kc).
It is our opinion that minor erosion control recommendations provided in this report is sufficient
for the development of this project, and additional engineered erosion control plans are not
required. Temporary and permanent erosion control measures are required for site development.
Extents of temporary erosion control will mostly depend on the timeliness of construction,
moisture content of the soil,and amount of rainfall during construction. Soil erosion typical to the
existing site conditions and planned disturbance of the project include wind-borne silts during dry
weather, and sediment transport during prolonged wet weather. Sediment transport could be from
stormwater runoff or tracking off-site with construction equipment.
The Temporary and Permanent Erosion Control Section (Section 5.6) of this report consist of
specific erosion controls to be implemented. Additional erosion control information and
specifications may be found in the latest addition of the "Stormwater Management Manual for
Western Washington," prepared by the Washington State Department of Ecology Water Quality
Program.
4.2.1 Shoreline Recession
Due to the close proximity of a shoreline,an evaluation of the shoreline recession rate for
this project was completed. This was accomplished by interviewing property owners
within the vicinity of the project, and/ or carefully reviewing and comparing historical
aerial photographs of the project. Historical aerial photograph sources may be found in
the 1951 aerial for the Soil Survey of Mason County, aerials from the Washington State
Department of Ecology,and from the Washington State Department of Natural Resources
Envirotech Engineering Geotechnical Report
PO Box 984 page 10 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
website. Based on available information,we conclude that the past shoreline recession for
this project is less than 10 feet in 50 years.
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, which is approximately 5 miles to the north of this project.
This information is based on the USGS Quaternary Fault and Fold Database for the United States.
Potential landslides due to seismic hazards have been considered, and are addressed in the Slope
Stability Analysis Section provided earlier in this report.
Soils immediately below the expected foundation depth for this project are generally Type D,
corresponding to the International Building Code (IBC) soil profiles. According to the IBC, the
regional seismic zone is 3 for this project. The estimated peak ground acceleration ranges from
0.50g to 0.60g.This estimation is based on the United States Geological Survey(USGS)National
Seismic Hazard project in which there is an estimated 2% probability of exceedance within the
next 50 years.
4.3.1 Liquefaction
The potential for liquefaction is believed to be low for this project. This is based, in part,
on the subsurface conditions such as soil characteristics and the lack of a permanent
shallow water table. Subgrade characteristics that particularly contribute to problems
caused from liquefaction include submerged, confined, poorly-graded granular soils (i.e.
gravel, sand, silt).Although gravel-and silt-sized soil particles could be problematic,fine
and medium grained sands are typically subjected to these types of seismic hazards. No
significant saturated sand stratifications are anticipated to be within the upper 50 feet of
the subsoil for this project.
4.4 Landslide,Erosion and Seismic Hazards Conclusions
DNR did not indicate historic landslide activity near the project. Mapped slope conditions, as
delineated by the Departments of Ecology and/ or Natural Resources, were considered in our
slope stability assessment. Based on the proximity and severity of mapped delineations with
respect to the proposed development, results of the aforesaid slope stability analysis, observed
surface conditions, and other pertinent information, it is our opinion that the proposed
development may occur in accordance with the recommendations in this geotechnical report.
4.5 Lateral Earth Pressures
Retaining walls may be utilized for this project. The lateral earth pressures exerted through the
backfill of a retaining wall are dependent upon several factors including height of retained soil
behind the wall, type of soil that is retained, degree of backfill compaction, slope of backfill,
surcharges,hydrostatic pressures,earthquake pressures,and the direction and distance that the top
of the wall moves. A structural or geotechnical professional should design retaining walls based
on specific conditions.
Envirotech Engineering Geotechnical Report
PO Box 984 page 11 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
Soil parameters for the structural design of retaining walls may be estimated as 134 pounds per
cubic foot (pcf) and 118 pcf for engineered fill and native soils, respectively. The angle of
internal friction may be estimated as 36 degrees and 32 degrees for engineered fill and native
soils, respectively. These soil parameters are based on soil type and placement conforming to the
Earthwork Construction Recommendations Section in this report.
4.6 On-Site and Off-Site Impacts
From a geotechnical position, it is Envirotech's opinion that the subject property and adjacent
properties to the proposed development should not be significantly impacted if all
recommendations in this report are followed. This opinion is based on the expected site
development, existing topography, existing nearby development, land cover, and adhering to the
recommendations presented in this report. Future development or land disturbing activities on
neighboring properties or properties beyond adjacent parcels that are upslope and/or downslope
from the subject property could cause problems to the subject property. For this reason, future
development or land disturbance near the subject property should be evaluated by a geotechnical
engineer.
Envirotech Engineering Geotechnical Report
PO Box 984 page 12 Parcel 1 2 1 1 9-50-00 1 55
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
5.0 ENGINEERING RECOMMENDATIONS
The following sections present engineering recommendations for the proposed improvements of
the project. These recommendations have been made available based on the planned
improvements as outlined in the Introduction Section of this report; general observations
including drainage and topography as recapitulated in the Surface Conditions Section; soil/
geologic conditions that were identified from the geotechnical investigation that is summarized in
the Subsurface Investigation Section; and, project research, analyses and conclusions as
determined in the Engineering Analysis and Conclusions Section. Recommendations for the
project that is provided herein,includes pertinent information for building foundations,earthwork
construction, building and/ or footing setbacks, drainage, vegetation considerations, and erosion
control.
5.1 Building Foundation Recommendations
Recommendations provided in this section account for the site development of a typical one- or
two-story, single family residential structure. The recommended allowable bearing capacities and
settlements as presented below, consider the probable type of construction as well as the field
investigation results by implementing practical engineering judgment within published
engineering standards. Evaluations include classifying site soils based on observed field
conditions and soil testing for this project. After deriving conservative relative densities, unit
weights and angles of internal friction of the in-situ soils, the Terzhagi ultimate bearing capacity
equation was utilized for determining foundation width and depth. Foundation parameters
provided herein account for typical structural pressures due to the planned type of development.
A structural analysis is beyond the scope of a geotechnical report, and a structural engineer may
be required to design specific foundations and other structural elements based on the soil
investigation. Stepped foundations are acceptable, if warranted for this project. Continuous,
isolated, or stepped foundations shall be horizontally level between the bottom of the foundation
and the top of the bearing strata.The frost penetration depth is not expected to extend beyond 12
inches below the ground surface for this project under normal circumstances and anticipated
design features.
5.1.1 Bearing Capacity
Existing in-situ soils for this project indicates that the structure can be established on
shallow, continuous or isolated footings. Foundations shall be established on relatively
undisturbed native soil that is competent and unyielding. Alternatively, foundations may
be constructed on selective re-compacted native soil or compacted engineered fill as
described in the Earthwork Construction Recommendations Section of this report.
For a bearing capacity requirement of no more than 1500 psf, a minimum continuous
footing width of 12 inches shall be placed at a minimum of 18 inches below the existing
ground surface atop unyielding soils. For a columnar load of no more than 3 tons, a
circular or square isolated foundation diameter or width shall be at least 24 inches.
Foundation recommendations are made available based on adherence to the remaining
recommendations that are provided in this report. Alterations to the aforementioned
foundation recommendations may be completed upon a site inspection by a geotechnical
engineer after the foundation excavation is completed.
Envirotech Engineering Geotechnical Report
PO Box 984 page 13 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
5.1.2 Settlement
Total and differential settlement that a structure will undergo depends primarily on the
subsurface conditions, type of structure, amount and duration of pressure exerted by the
structure, reduction of pore water pressure, and in some instances, the infiltration of free
moisture. Based on the expected native soil conditions, anticipated development, and
construction abides by the recommendations in this report, the assumed foundation
system may undergo a maximum of 1.0 inch total settlement, and a maximum differential
settlement of 0.75 inch.
5.1.3 Concrete Slabs-on-Grade
Interior slabs, if utilized, should be supported on a minimum of 4 inches of compacted
coarse, granular material (Retained on U.S. Sieve #10 or greater) that is placed over
undisturbed, competent native subgrade or engineered fill per the Earthwork
Recommendations Section below.
The recommendations for interior concrete slabs-on-grade as presented herein are only
relevant for the geotechnical application of this project. Although beyond the scope of
this report, concrete slabs should also be designed for structural integrity and
environmental reliability. This includes vapor barriers or moisture control for mitigating
excessive moisture in the building.
5.2 Earthwork Construction Recommendations
Founding material for building foundations shall consist of undisturbed native soils to the
specified foundation depths. Compacted engineered fill, or selective re-compacted native soils
may be used to the extents provided in this Earthwork Construction Recommendations Section.
The following recommendations include excavations, subgrade preparation, type of fill, and
placement of fill for building foundations.
5.2.1 Excavation
Excavation is recommended to remove any excessive organic content or other deleterious
material, if present, beneath foundations and to achieve appropriate foundation depth.
Additional sub-excavation will be required for this project if the soils below the required
foundation depth are loose, saturated, not as described in this report, or otherwise
incompetent due to inappropriate land disturbing, or excessive water trapped within
foundation excavations prior to foundation construction.All soils below the bottom of the
excavation shall be competent, and relatively undisturbed or properly compacted fill. If
these soils are disturbed or deemed incompetent, re-compaction of these soils below the
anticipated footing depth is necessary. Excavations shall be completely dewatered,
compacted, and suitable before placement of additional native soil, engineered fill or
structural concrete.
Envirotech Engineering Geotechnical Report
PO Box 984 page 14 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
5.2.2 Placement and Compaction of Native Soils and Engineered Fill
For engineered fill or disturbed native soils that will be utilized as fill material directly
beneath foundations, observation and/ or geotechnical testing is required prior to
foundation construction. The following placement and compaction requirements are
necessary.
For disturbed native soils or engineered fill beneath foundations, limits of compacted or
re-compacted fill shall extend laterally from the bottom edge of the foundation at a rate of
one horizontal foot for each foot of compacted or re-compacted fill depth beneath the
foundation. See the illustration below.
FOOTING
COMPACTED
NATIVE SOILS
OR ENGINEERED t
FILL
ISTURDED SllBERA
tX
Both engineered fill and native soils used as compacted fill should be free of roots and
other organics, rocks over 6 inches in size, or any other deleterious matter. Because of
moisture sensitivity, importing and compacting engineered fill may be more economical
than compacting disturbed native soils. Engineered fill shall include having the soils
retained on the No. 4 sieve crushed (angular), and should consist of the following
gradation:
U.S.Standard Sieve %Finer(by weight)
6" 100
3" 60— 100
No. 4 20—60
No. 200 0-8
Table 1
Particle Size Distribution of Engineered Fill
Compaction shall be achieved in compacted lifts not to exceed 6 inches for both native
soils and engineered fill,respectively. Each lift should be uniformly compacted to at least
95% of the modified Proctor maximum dry density (ASTM D 1557) and within 3% of
optimum moisture content. Each lift surface should be adequately maintained during
construction in order to achieve acceptable compaction and inter-lift bonding.
Temporary earth cuts and temporary fill slopes exceeding 4 feet in height should be
limited to a slope of 2:1 (horizontal:vertical). Utility trenches or other confined
excavations exceeding 4 feet should conform to OSHA safety regulations. Permanent cut
and fill slopes shall be limited to a slope of 2:1, unless otherwise approved by an
engineer.
Envirotech Engineering Geotechnical Report
PO Box 984 page 15 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
5.2.3 Retaining Wall Backfill
Native soils may be used as retaining wall backfill for this project if the total wall height
is 4 feet or less and the recommendations below are followed. Native soils for retaining
walls exceeding 4 feet in height must be approved by the local authority or evaluated by
an engineer. Backfill may consist of engineered fill,as presented in this report,or borrow
material approved by a geotechnical engineer. Compaction of these materials shall be
achieved in compacted lifts of about 12 inches. Each lift should be uniformly compacted
to at least 85%, and no more than 90% of the modified Proctor maximum dry density
(ASTM D 1557).If pavement or building loads are planned to be located within retaining
wall backfill, then 90% compaction is required. In addition, heavy construction
equipment should be at a distance of at least 1/2 the wall height. Over-compaction and
limiting heavy construction equipment should be prevented to minimize the risk of excess
lateral earth pressure on the retaining structure. Envirotech recommends that retaining
wall backfill is compacted with light equipment such as a hand-held power tamper. If
clean,coarse gravel soils are utilized as engineered fill, and surcharges will not influence
the retaining wall, compaction may be achieved by reasonably densifying granular soils
with construction equipment.
5.2.4 Wet Weather Considerations
Due to the types of subsurface soils, additional provisions may be required during
prolonged wet weather. Every precaution should be made in order to prevent free
moisture from saturating the soils within excavations. If the bottom of excavations used
for footing placement changes from a moist and dense/hard characteristic as presented in
this report to muck or soft, saturated conditions, then these soils become unsuitable for
foundation bearing material. If this situation occurs, a geotechnical engineer should be
notified, and these soils should be completely removed and replaced with compacted
engineered fill or suitable native material as presented in this section.
5.2.5 Building Pads
Building pads consisting of built-up fill is not expected for this project. If utilized, pads
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.
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 35 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.
Envirotech Engineering Geotechnical Report
PO Box 984 page 16 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
STRUCTURE
TOP OF
SLOPE SLOPE
FACE
I I-I
SETBACK FOOTING
From the illustration above, structures may be located closer to the top of slope by extending the
foundation deep enough to maintain the recommended setback. In addition, the required setback
may be reduced by mitigation, and subsequently would require additional geotechnical studies.
5.4 Surface and Subsurface Drainage
Positive drainage should be provided in the final design for all planned residential buildings.
Drainage shall include sloping the ground surface, driveways and sidewalks away from the
project structures. All constructed surface and subsurface drains should be adequately maintained
during the life of the structure. If drainage problems occur during or after construction, additional
engineered water mitigation will be required immediately. This may include a combination of
swales,berms, drain pipes, infiltration facilities, or outlet protection in order to divert water away
from the structures to an appropriate protected discharge area. Leakage of water pipes, both
drainage and supply lines,shall be prevented at all times.
If impervious thresholds are exceeded per the prevailing agency code, then engineered
stormwater management plans are required for this project. The drainage engineer must
coordinate with a geotechnical engineer for input with relation to slope stability prior to
submitting drainage plans. If stormwater management plans are not required for this project, then
the following recommendations should be followed.
For this project, we recommend that infiltration is avoided in order to maintain slope stability,
and that roof downspout dispersion on splash blocks are employed for roof areas of 1400 sf or
less. If larger roof areas are proposed, we strongly recommend that roof water is tightlined with
the outlet on the beach using a pipe tee for energy dissipation.
5.5 Vegetation Buffer and Considerations
For this project, we believe that a detailed clearing and grading plan is not warranted unless the
prevailing agency thresholds are exceeded, and basic vegetation management practices should be
adhered to.
Vegetation Buffer—Vegetation shall not be removed from the face of the critical slope or within
a distance of 10 feet beyond the top of the slope. However, any tree deemed hazardous to life or
property shall be removed. If tree removal is necessary, then stumps and roots shall remain in
place, and the underbrush and soil shall remain undisturbed as much as possible. Any disturbed
soil shall be graded and re-compacted in order to restore the terrain similar to preexisting
Envirotech Engineering Geotechnical Report
PO Box 984 page 17 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
conditions and drainage patterns. See the Site Plan in Appendix A of this report for a depiction of
the vegetation buffer.
5.6 Temporary and Permanent Erosion Control
Erosion control during construction should include minimizing the removal of vegetation to the
least extent possible. Erosion control measures during construction may include stockpiling
cleared vegetation, silt fencing, intercepting swales, berms, straw bales, plastic cover or other
standard controls. Although other controls may be used, if adequate, silt fencing is presented in
this report as the first choice for temporary erosion control. Any erosion control should be located
down-slope and beyond the limits of construction and clearing of vegetation where surface water
is expected to flow. If the loss of sediments appears to be greater than expected, or erosion
control measures are not functioning as needed, additional measures must be implemented
immediately. See Appendix D for sketches and general notes regarding selected erosion control
measures. The Site Plan in Appendix A depicts the recommended locations for erosion control
facilities to be installed as necessary.
Permanent erosion control is necessary if substantial vegetation has not been established within
disturbed areas upon completion of the project.Temporary erosion control should remain in place
until permanent erosion control has been established. Permanent erosion control may include
promoting the growth of vegetation within the exposed areas by mulching, seeding or an
equivalent measure. Selected recommendations for permanent erosion control are provided in
Appendix D. Additional erosion control measures that should be performed include routine
maintenance and replacement, when necessary, of permanent erosion control, vegetation,
drainage structures and/or features.
5.7 Septic Drainfields
Septic drainfields were considered in our geotechnical evaluation.This includes septic drainfields
with relation to the observed soil conditions, expected vegetation removal, and existing and
proposed topography. Based on the aforesaid parameters, the septic drainfields are not expected
to adversely influence critical slopes.This is also based on compliance with all recommendations
in this report.
5.8 Structural Mitigation
With respect to landslide alleviation or slope improvements, structural mitigation is not necessary
for this project. This determination is based on the anticipated improvements of the project,
engineering conclusions,and compliance with all recommendations provided in this report.
Envirotech Engineering Geotechnical Report
PO Box 984 page 18 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
6.0 CLOSURE
Based on the project information provided by the owner, the proposed development, and site
conditions as presented in this report, it is Envirotech's opinion that additional geotechnical
studies are not required to further evaluate this project.
Due to the inherent natural variations of the soil stratification and the nature of the geotechnical
subsurface exploration, there is always a possibility that soil conditions encountered during
construction are different than those described in this report. It is not recommended that a
qualified engineer performs a site inspection during earthwork construction unless fill soils will
influence the impending foundation. However, if native, undisturbed subsurface conditions found
on-site are not as presented in this report,then a geotechnical engineer should be consulted.
This report presents geotechnical design guidelines, and is intended only for the owner, or
owners' representative,and location of project described herein.This report should not be used to
dictate construction procedures or relieve the contractor of his responsibility.
Any and all content of this geotechnical report is only valid in conjunction with the compliance of
all recommendations provided in this report. Semantics throughout this report such as `shall,'
`should' and `recommended' imply that the correlating design and/or specifications must be
adhered to in order to potentially protect life and/or property. Semantics such as `suggested' or
`optional' refer that the associated design or specification may or may not be performed, but is
provided for optimal performance. The recommendations provided in this report are valid for the
proposed development at the issuance date of this report. Changes to the site other than the
expected development, changes to neighboring properties, changes to ordinances or regulatory
codes, or broadening of accepted geotechnical standards may affect the long-term conclusions
and recommendations of this report.
The services described in this report were prepared under the responsible charge of Michael
Staten, a professional engineer with Envirotech. Michael Staten has appropriate education and
experience in the field of geotechnical engineering in order to assess landslide hazards,
earthquake hazards,and general soil mechanics.
Please contact Michael Staten at 360-275-9374 if you have any questions, comments, or require
additional information.
Sincerely,
Envirotech Engineering
Jessica Smith,M.S. Michael Staten,P.E.
Staff Geologist Geotechnical Engineer
Envirotech Engineering Geotechnical Report
PO Box 984 page 19 Parcel 12119-50-00155
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 July 20,2020
SCALE- 1 INCH DO FEET
2u 4u go
APPROXIMATE TOP OF CRITICAL
SLOPE EXCEEDING 40%
APPROXIMATE TOE OF CRITICAL
SLOPE EXCEEDING 40%
M Ft Mi TNUCTIIIN SETBACK
FROM TOP OE CRITICAL SLOPE
Ft�EED[3{ii 43X
NSF A
D�
+
+ TPI
+ A
W
+
PFLIPERTT LINE 10 FT VEGETATIO`( REMOVAL
BUFFER FRDN TO? OF CRITICAL
SLOPE EXCCLaING 40%
PROJECT/ OWNER/LOCATION,
E34EVM CEMAa IMY E IEOUIRED FOR THIS SITE GENERAL LOCATI004 SINGLE FAMILY RESIDENCE
PIE DEPICTFD ANA ALTERMATIVES MAY BE UTILIZED AS EXPLAINED IN THE GEOTECHNICAL REPORT
OFT'rQWA TAL W0WT.
B.C'ONTrU RB WERE NOT PME#0" BY A LICENSED LAND SURVEYOR TUPPER
CCKTMM VEIE EXtRAPOLATEB FROM A PUBLIC LIDAR SOURCE,AND 374 E POINTES DR E
Ik0WeAATED FIELB fEASthXlENTS AS EXPLAINED 1N THE GEOTECHNICAL LEGEND PARCEL 121.19-50-00155
BiEYOITT. MASON COUNTY, VA N N T N
Z 91504tRS VR.WF NOT P7E7ARED BY A LICENSED SURVEYOR. LOCA71rtd 84
TEMPORARY ENGINEER
OF YETF FFATUl"THAT AM SHOWN HERE. SUCH AS TOP If SLOPES,TOE + +EROSIDN CONTROL
OF SLOOM14 WATER FEATUREX�ETC.,WITH RELATION TO THE PROPERTY + ENVIROT ENGINEERING
LENES MW E VER:F]ED BY THE OWNER.RECOMMENDATIONS IN THE SLOPE INDICATOR PO BOX 984
GECTEC OICAL REPORT PROYNE SETBACKS. BUFFERS, DEPTHS,ETC. WITH B0.FAIR, vASHINGTON 98528
KLATM TO L�U[C FEATURES,NOT PROPERTY LINKS. TICSE GEOUIRC --80 EXISTING CONTOUR 360-275-9374
1-41U"MAY IE LOCATYD.1M IHE SUBJECT PROPERTY OR NIEIGHBORINS TPI" TEST PIT SITE PLAN
I A3+FItrIEB,
APPENDIX B
SOIL INFORMATION
VERTICAL MV MIRIZU.M FEET
SC11LE-
�1 MH-40 FEET II
Ql eu (0
PROPOSED MEDIUM DENSE SILTY SAND
HOUSE WITH GRAVEL (SM)
8%± EXISTING GRADE
I2
V�
CASE INLET
DENSE GLACIAL TILL
SFPTIIIN A-A
PROJECT/ OWNER/ LOCATIOM
SINGLE FAMILY RESIDENCE
GEOTECHNICAL REPORT
TUPPER
PARCEL 12119-50-00133
MASON COUNTY, WASHINGTCN
NOTES
1)HIM GRADE CH00"S REOUIRCD IN ORDER TO ACHIEVE ENGIREEM
TECH ENGINEERING
POSITIVE DRAINAGE PC BOX 984
2)THE SOIL PROFILE IS ACCURATE FOR THE DEPTH OF BE B
THE OBSERVED TEST PITS AT THE SPECIFIED LOCA17INS. LFADT, WASHINGTOI 9B32B
LOVER DEPTHS ARE BASED OR SITE GEO.OGY,
360-273-9371
WELL LOG(S),AND/OR EXPERIENCE IN THE GENERAL AREA SOIL PROFILE
TEST PIT LOG
TEST PIT NUMBER TP-1
PROJECT: Tupper Geotechnical Report DATE OF LOG: 7/1312020
PROJECT NO: 2096 LOGGED BY: MCS
CLIENT: Jokwo Tupper EXCAVATOR: N/A
LOCATION: 374 E Pointes Drive E DRILL RIG: None
Mason County,Washington ELEVATION: N/A
INITIAL DEPTH OF WATER: NIA FINAL DEPTH OF WATER: WA
SOIL STRATA, STANDARD PENEFRAT1oN TEST
DEPTH SAMPLERS USCS DESCRIPTION LL PI DEPTH N CURVE
AND TEST DATA 10 30 50
0
SM Medium brown,moist,medium dense
.� SILTY SAND with GRAVEL Gravel is
r , primarily well-graded and sutxounded
1 Sand is mostly medium.No plasticity
2
Light brown.very dense glacial till T
3
SM Hardpan
r'
4
s.
5 -
6
7
s
Excavation terminated at approximately
10 10 feet
No Groundwater Encountered ENVIROTECH ENGINEERING
This inrormabon pertam only to thus bonng and shmAd not be Geotechnical Engineering
interpreted as being indicitrHe of the enbm site.
Map Unit Descnpbw Smctarr sholty loam.5 to 15 percent slopes—Mason County,
Wastungion
Mason County. Washington
So—Sinclair shotty loam. 5 to 15 percent slopes
Map Unit Setting
National map unit symbol 2hn7
Elevation 0 to 300 feet
Llean annual prectpdation 25 to 50 inches
Llean annual air temperature 50 degrees F
Frost-free period 200 days
Farmland classification Farmland of statewide importance
Map Unit Composition
Sinclair and similar soils. 100 percent
Estimates are based on observations,descnplions,and transects of
the mapund,
Description of Sinclair
Setting
Landform Till plains
Typical profile
H 1-0 to 11 inches gravelly loam
H2-11 to 35 inches. very gravelly loam
H3-35 to 60 inches gravelly sandy loam
Properties and qualities
Slope 5 to 15 percent
Depth to restrictive feature 28 to 42 inches to densic material
Natural drainage class Moderately well drained
Capacity of the most limiting layer to transmit water(Ksat) Very
low to moderately low(0 00 to 0 06 inlhr)
Depth to water table About 18 to 30 inches
Frequency of flooding None
Frequency of pending None
Available water storage 1n profile Low(about 3.7 inches)
Interpretive groups
Land capability classification(irrigated) None specified
Land capability classification(nonimgated) 4s
Hydrologic Sod Group B
Forage suitability group Limited Depth Sods(G002XN302WA)
Hyddc soil rating No
Data Source Information
Sod Survey Area Mason County,Washington
Survey Area Data Version 16,Jun 4,2020
't Natural Re wcee web Soil Survey 71192020
� Conservation Service National Cooperative Sod Survey Page 1 of r
CL ( STATE OF WASHINGTO(
QJ DEPARTMENT OF CONSERVATION t
AND DEVELUXE`tT AppW7273
WELL Loa
Date.
y ---i
Record by.. Dri I I-or --
++ DrilSeT a ReCOPd t '
� Sot=ce_... t •.:
0 Location: State of WASHINGTON -- i
ba
++ C
Method of Drilling- -•••--
Cable Date.�•. , 19. .:�,w�
�- R rhaeuser ProPertiesa Iac._ _.-
0 Owner_.-.-_.. --
a Addzess_ P•0•_Bc% 1645tTacotna�.7fashill$ton 981t0I
above
R Laud surface, dat.im--.-_..--..--n
�„t Tptcttwta>t Dori
tQ Ceati• MATYtaL ItMt) ([wt)
Q LATMIN .
(Ti><n•trtba dril:ar". termino:ofy literally but panphrtts•a4 eK^s rl, dr Dtlnnlnfi f.+t
tt tnebrlal+cur-4wrk�s. .n.tat-♦nd neord.fella.emVt-�d.tretLE-Ow tolumn.ti
Selo+ l+nd-.art•ot d•tup� at-*at)+.r+IN U t"jag* C^tQM�a.►crteo..ttc.1
It t.Lmblc yoEorrtaa log of tnatert"'It"aU tuiap•W L
C Co=nit dmestic su 1 xe
r
;awl-
O Gra cli-j, and
80
z Gra hard 80 1
Brmm
mWater sand and Tel 1 �
G Small avel with c
0 - Small ravel and cl 16$ �t
w
G fine sand and silt 6�_-2 --,.:
O Casin 8" from 0 to t -1--- -
Screened from 1Jt to 1 8t ---rete
—
E Surface sealed with cconc �
sheet...—.--ot stteeu
>` Turu up
R
CL
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41
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1 _ 1 O
1 20
1 _ 30
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1 60
1 . 70
1 so
1 90
. 00
1 _ 489
P r o j e c t T u pp a r Ra p o r t
D a t a f i 1 a _ D y n ami c Ana 1 y s i s
Analysis Bishop
—......... .. ....uv..e.. zee
1 . 30
1 1 . 00
1 . 10
1 . 20
1 . 3 O
1 . 4 O
1 . 50
1 . 60
1 . 7 0
. 80
. 90
. 00
022
P r o j e c t T u pp e r R a p r t
D a t a f i 1 er S t a t i c A n a l y s i s
Analysis Bishop
•T......... . .......2
GEOTEXTILE FABRIC
WRAP AROUND TRENCH
TO AT LEAST ENTIRE
BOTTOM OF TRENCH
BEFORE PLACING GRAVEL 2'x2'x5' WOOD POST OR
12' DEEP, B' WIDE TRENCH EQUIVALENT OR BETTER
FILLED WITH 3/4' TO 1 1/2'
WASHED GRAVEL OR VEGETAT�N
es n
DIRECTMN OF EMSTING
HATER FLOV GROUND SURFACE
rr
Tjr rr
SILT FENCE - CROSS SECTION
N.T.S.
2'x2' WOOD POST (TYP) GEOTEXTILE FABRIC
OR EQUIVALENT OR BETTER AND WIRE MESH
2 6 FT MAX. O.C.
i FT-+'� 40 R
EXISTING rl
GROUND SURFACE
12- DEEP, 8' VIDE
TRENCH FD i cn VITH I"
3/4' TO 1 Me �PT
WASHED GRAVEL OR VEG L
BOTTOM EXTENTS OF
GEOTEXTILE FABRIC SILT FENCE - DETAIL
N.T.S.
PROVIDE FULL WIDTH
3/4 IN TO 1 1/ N2o rr INGRESS/EGRESS
CRUSHED GRAVEL
PLACED AT 6 IN
MINIMUM DEPTH
WELL-DRAINED
SOILS
-0.02 IN/MIN vui LDam
R=25 FT MIN
4 —
_r"s MAD
STABILIZED CONSTRUCTION ENTRANCE
N.T.S.
AEP--SANEHT ERCIF"12WML IDTM
Emom►am-
SmlcID.0 FGE Fca SLOPES
@COLD THE TENMRA'T EXTWN MIE SEmQVT CDRTQ3L NEA547ES WVA ON
HESIE PL.M mve TO I E NVAU BRTE IIu"a L'QIS"TZIN.THE 6OITiTAY.TIIR L 3EFORE ice.0"TALL HE£CED SLWACE RLNEFF CONT11L
WILL DOTALL ADMIONL ERIOMIN NWO SEDDIENF CiAII101.FACLITIE& NlEASURE ELZH M WIADS NT TEIIIIIIIIIIIES,MT ION cmwS.
PILL EDS M AM SEMJIT CORBEL.FACLIT=AND DEVJ=SHALL BE SYALCS.LEYEL.3MCADERS AM SEIVEYT A4!SDT.
DAILY AM O!FffiATILT MADETAD".V 1ECESEARV, F.THE Sm 14 SEAALL E Fail WITH FAWLY FINE SURFACE,
FILL 1 AVID MOMENT LMITBm.PAmITlFS AIO EYS�S 1HALL RELEFT DM FOLLOWING ADHFACE 1laX�ttWJA6.PERFBan ALL®£..VAT'Imxxm
LACE UNTIL THE LPSIID'E A`W-03 HAVE LED(PFJtlUMRF MY STA31 1 ON P"'E42MILAR IO THE SL(D'G
1 xE:r F IRE2ximmEms1T'IINS,its ma'nTtl IEL,OW',A►A I►R.LD E
TNFCANPECRO7fOO1 f.13ATE L NOTEN APPLIEB AT THBC MTE Or WO PD1M PEAK AM
4 SEED[EE"MANTES Lr'TLEEN RAY 1 4WD WTODEN Ia VO.L
ALL ANEW WHICH FNVE IIZEH StT15!!'ED OF VENrAIM OR LNG EZURE 39COATION AM QRQ MAVITDWAX AS!43:EYsi1R1'TO
ACT[VrTKL AND WIEIE!N FTRTHIN W=NE/DRRIE.Wl M FOB:A FmT1TR A"FAIITI=THE BAaT S NUDTA.b[,
MERM 1011CIO01101111 TFC LIiIEA t7QTGCA so",AL 3ETEIOlICI1 ARM ART E S=0 E9S QLM=IIE VTiE11 BTOVENSER 1 09 APIM ML
lovEllovmCMRXL TREAAMO. M M TTw YEAR �f. CEamrra , x-rE�.,ass PL irl WILL�TZC �
COW WILL RLY K ACM"A to KING THE 11006 OF A14 L 71-MO S FEWMMEIM ARE TO BE k.20 ACt1RC M SPPLXRW
"TOOER.MIWM fE£OE3 NAY PIIMMI WHl CM R IS DH THE R TEW%7 OF F E)ILATIUMP ANOLNTS SFU 4A BE 7M�, ESPECIALLY
E QaAE'RJCORR/M,'1 MIT MUST ALM E MOON inTH ARLo-ca NETTm ATLhCEHT TO+.ATDE Borm Mae '.EhM1U5
OTH£R AN°'C'fIOJED T3EAri'EMNT. USE THE FOla'.M EfCWH4EMED WED MIYT,3f£ FOR EFKIS=
RY SEASM CHAT U THAU SEPTEMBER 33)—THE CLEARING OF LAND. INCLUIING THE 3DNTROL. U3 A COUNTY APPROVEC ALTERNATE SUB"TURRE.
OVAL Or E)CSTIMC VVIETATOIN OR OTf£7 GMhD COVER.MUST BE LIMITED TO
H$.Y AS MJCH LAND AS CAN RECEIVE APPROPRIATE PRai1;,TIVE COVEN OR BE PROPORTTE NS PURITY GERMVArM
M,ERVTSE STAI LIZED,AFTER HAVING BEEN CLEA ED OR OTHEZWISE DIST.R3RED SAME BY WEIGHTeA) M -.
T ND LATER THAN SEPTEMBER
30 IF A G3VEN TEAR.L111.ESS IMMEDIATE
ARRMATIEN II SPECTWO DA THE EROISMN AND SEDDE\T CONTROL PLAN,ALL RE➢TOP !ACROSTIS ALBS) _0 92
PEAS CLEARED OR 13THERVESE DISTURBED MUST BE APPROPRIATELY STABILIZED ANNUAL RYE CLOLIUM MULTTFLORUM) 40 98 90
ROUGH THE USE OF MULCFENG, NETTING,PLASTIC SHE-17m,EROSION BLANKETS, CHEWING FESCUE .0 97 DO
IEPTEMBER
EE DRAINING MATERIAL,ETC., BY SEPTEMBER 30 OR SOONER PER THE APPROVED (FESTUCA RUBRA CO MMUTATA)
AN 1F ACTODL UNLESS ORERWISE APPROVED BY THE CMATY, SEEDING. (JAMESTOWN, BANNER. SHADOW,KOCE)
RTILIZING AND MULCHING OF CLEARED OR OTHERWISE DISTURBED AREAS SHALL BE WHITE DUTCH CLOVER .0 96 90
RFORMED DURING THE FOLLOWING PERIODS$MARCH 1 TO MAY 15, AND AUGUST 15 M (TRFOLILAM REPENS)
MBER L SEEDING AFTER OCTOBER 1 WILL BE DONE WHEN PHYSICAL COMPLETION
THE PRO..ECT IS DMNUtENT AND THE ENVIRO£NTAL COND[TIDNS ARE CONDUCIVE MULCHING
SATISFACTORY GROWTH IN THE EVENT THAT PERANENT STASIMATMN 1S NOT
SSIDLE,AN ALTERNATIVE METHOD(IF O GR ND COVER, SUCH AS MULCHING,NETTING,L MATERIALS USED FIR MULCHING ARE RECOMMENDED TO BE WOOD
AST'1C SHEETING,EROSION BLANKETS,ETC.,MUST BE ONVALLED BY ND LATER THAN FIBER CELLULOSE,AND SHOULD BE APPLIED AT A RATE OF 1Coo
30. POUNDS PER ACRE.
?.MU.CH SHOULD DE APPLZU IN ALL AREAS WITH LWMEL SLOPES
THE EMFIBT THAT CUMMXIMN ACTrWr=OR aTHER SITE➢EVELO14M 3REATER TNSN Zia 40aOWTALNVERTICALIN
NITIE,S ARE IESCOICKED FOR AT LEAST 4 CBSEMMW DATE,THE S MU LCHI R3 SHQAU E U93 WNEMATELY AFTER LEEMkii OR
PUTIERJONTIIIACTOR SHR.L E REVORIDLE FOR THE DMIMT 13F ALL ESE= 4FEIS VH.MH CANNOT DE REELED E^..ACRE OF T'E SEAMC ALL
NID SEIT7ENi GOEISOL F14tA ETIEf DDiRATELY AFTER FiTOERat EYENTi )MiD AT ARE-AS R PLLAR ANIl TE tWFIKD Mtn WIT+DER i
�EVIL?!'AIEEII.T!E OLfNERJ rJ'DATAAL'TOR SI4Al1.g pEyPO�J:F'61
HAINTER"T AND RFINA[@ OF ALL ERMEON AN SEM4AIT CCkTXL FACLTTIES. Tup=.=
SE,134=M&ER I THRIf APUIUL M—DA WE S WHERE UNDAI LATER L TIP`,UL W11ILD BE USED FUR THL34 PAO.ECT LYE TO C�LY
CTI AVITY IS IN PR�ESL THE C.EQM OF LAND,INCY1J M THE 1KME EXAQED am I
A3 l�.STING VET TATOAN ONO UFFEA T; C01rM SHALL TIE LW= g,70"ML SIOLLD DE PLACED ON SUES IW DS
"A AS."AN E'.AWVR O O R STABILIZER WITHIN 24 HDU1D IN 36 STRD"m NO ST[ICHL'1LIM®R OI7E SST SHALL[PLY E
VEAET A 141,10R STOF"M FRECICTED OVA/OR CROU3I MO S�YEHT PICRI ITTED IF TW ML=FWAFLE As1D1 LOANY MXXiHNA SR1DY LOW
OFF-DFE a OEERYEL1 ELT L PK*V MY LOIN[.MAY LONE.
0.F.tEE9 OR ZMTLMM A;XM sWHLL RECEIVE APPSOAWIE PAaTFL'TISIE 4 STOW=SHALL E CONFORM TO THE DN�ATE wB'TRUCTI l
-a E DTHH}YAILE ATAY[LI7ED SIHpC Afi)ELP#DIFp NETTIIfi PLAOiTIC Rllt/i AFAR 70 t0[IBC/I 1CTIClPOii DL"TH a f21EQ1 RUT
�BLANICTS.IEEE DOOM MATERIAL.ETC„VMVI 3 SAYS LATER KWMZ MOOT MAY VARY O CONTROL T L THE PART9f1L.I IN I ALL
DE7]R CLEARED OR OTFETEWCSE D[ITJPIES F)OT ED6 ACTIVELY ►OiE7 COEfROL STAIJCTJREI 3HMl E 7J PLANE DEFTDK
7 FENCING. SEU[PENT TRAPS, SEDa1EM PONDS,ETC., VOLL WT E VZVEO AS
DEOUATE COVER IN AND OF THEMSELVES.IN THE EVENT THAT ANY LAND AREA NOT
Na ACTIVELY WORKED REMAINS UNPROTECTED OR HAS NOT BEEN APPROPRIATELY
TABLIZED 7 DAYS AFTER HAVING BEEN CLEARED,ALL CONSTRUCTION ACTIVITY 1N
SITE,EXCEPT FOR APPROVED EROSION AND SEDIMENT CONTROL ACTIVITY, SHALL
MMEDIATELY CEASE UNTIL SUCH A TIME AS AFOREMEUTEMED LAND AREA HAS BEEN
PPROPRIATELY PROTECTED OR STABILIZED.
ST13CKPLE MANAGEMENT
STOOKPOJO SHALL K STABOLMD(VITM PLASTIC ZW491NO OR OTHER APPROVED DEVICE)DAILY KTv6N MOVDNKR 1 AND MARCH
3L
2.DA MAY SEASON, SEDIMENT LEACHING FROM STOOK PILES MUST K PREVENTE0.
3.TOPSOIL SHALL NOT BE PLACED vNI E N A FROZEN O MUDCY CD,DIT04,v CH THE SUBGRACE IS EXCESSIVELY WET,OR WHEN
CRNUTOINS EXIST T14AT MAY OTHERWISE K DETRIMENTAL TO PROPER GRADING IR PROPOSED SOODRIG OR SEEDING.
FREVTRLMM-DTADLL7ED BPADC QA THE AREA TB E TOPULEB*W,L E lCAPNCADNED At MMU M THE APP MU KA. M
3TAE1ZER Cd@TIBZTIO N ENTRANCE
L NATEALAL SHALL NE 4"M I LARCH WANT SWILLS CA M 3 D CH FCA DEIMEMIAL SBaE M LY LOTS)AMD MAY E
TOP-MES'SEO WIN 1 DPCH TO 3 BMB'AR ROCK,(3TATE ITAVM VE"FR"ArIDUN.,SECTIID4 A-LIJ
B. THE 7EE M SHALL 1£AT LEAST W DIENE'S TH= AHD SO FEET L.WG C4 FEET FOR SITES VLTH LESS THAN 1 AGE 13F
DISTURBED Sall.). MOTH SHALL BE FULL VIM OF THE VEHICLE INGRESS AHD EGRESS AREA SMALLER PADS MAY E APPROVED
FOR SINGLE-FAMILY RESICE3NTIAL AND SMALL COMMERCIAL SITES
3. ADOITIDNAL ROCK SHALL BE AIDED PERIODICALLY TO MAINTAIN PRBPER FMANCTIIN E THE PAD.
4.IF THE PAD DOES NOT AEECUATELY REMOVE THE MUD FROM THE VEHICLE WHEELS. THE WHEELS SHALL BE HOSED OFF BEFORE
THE VEHICLE ENTERS A PAVED STREET, THE WASHING SHALL BE DONE ON AN AREA COVERED WITH CRUSHED ROCK AND WASH
[AER SHALL DRAIN TO A SEED-ENT RETENTION FACILITY OR rHRDu[7R A SILT FENCE.
ENCE
TEXTILE FLTR FABRIC TYPE SWLl E PER SPECIFD:C IN THE•S7VZRTWATER NWNACfICR4T +ANNUAL
E PU)ET SOUND VAS ON M'PLICADLE CEA'MTY STANDARDS
TEXTI.E FTLTENR FABRIC SHALL E PURCHASED IN A CaNTNX US PILL CUT TO THE LENGTH OF
ARRIER TO AVMD USE OF JOINTS,IF XINTS ARE KECESSMIf. FILTER FABRIC SHALL. BE SPL CE➢
HER ONLY AT A SLPPORY POST VTTN A MDNDMUN 6-INCH OVERLAP.AND SEMPELY FASTENED AT
ENDS TO THE POST.
NDARD FILTER FABRIC SHALL BE FASTENER:ISSN" 1'STAPLES O R TIE WIRES CHIT RDN3D L 4 LN
GTS&TALL E S>PACED AND PLACED AT IEPTHLS IND1C tTED IN TOE DETAILS OC THIS 9EET.AND
SECURELY UTD THE GRO,*a
E MESH SHALL BE 2'X2'X14 GAUGE OR E7AAVILENT.THE WIRE MESH MAY BE ELIMINATED IF
-STRENGTH FILTER FABRIC (MOffLAMENT),AND CLOSER POST SPACING IS USEL
RENCH SHALL BE EXCAVATED ACCORDING TO THE DETAILS BN THIS SHEET ALONG THE LINE OF THE
AND UPSLOPE FROM THE SILT FENCET FENCES SHALL BE LOCATED DOVNSLOK FROM THE CLEARING LD1TS [F THE PROJECT.