HomeMy WebLinkAboutGeoTech Report for BLD2010-00478 - BLD Engineering / Geo-tech Reports - 5/19/2010 ao -,51 78
APPROVED
MASON COUNTY DCD PLANNING
81TE PLAN REQUIRED TO 13E ON P!TE-
CHANGES SUBJETT O APPROVAL
Q�Daft—iO
Geotechnical Report
for
Larson Single Family Residence
Portion of Gov't Lot 2, Sec 36, T22N, R3W, W.M.
Parcel No. 32236 75 00060, also known as Resulting Parcel 6 of
BLA 10-10, under Auditor's File # 1956202 & 1956203
Mason County, Washington
May 19, 2010
Project#0938
Prepared For:
Bruce Larson
P.O. Box 606 G�`P��FCWA 811,
Tracyton, Washington 98393
Prepared By S�19/lam
A� 43045 w�
Envirotech Engineering o��s FCISTV, G��k
74 NE Hurd Road S�NALti�
Belfair, Washington 98528
Phone: 360-275-9374
Fax: 360-275-4789
RECEIVED
JUN 3 0 `1
Mason County Department of Community Development
M C C D - PLA�`;'°!
Submittal Checklist For a 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 found to be not applicable,the report should explain
the basis for the conclusion.
ApplicanUOwner SrLtr_2_ "00 Parcel# 3Z2M_ 75 OOOCO
Site Address WOul�t /06 It aol C'9" bT�✓�
(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) ti
(c) A discussion of ground water conditions
Located on page(s) Z
(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 activity in the vicinity, as available in the
referenced maps and records
Located on page(s) 649
J ••
(2) A site plan which identifies the .' portent develo�meat and geologic features.
Located on Map(s)identifier,
cth &12'
(3) Locations and logs of explorato�r holes or probes.
Located on Map(s)Vi e- /U, -64T o, A�
(4) The area of the proposed development, the boundaries of the hazard, and associated buffers and
setbacks shall be delineated.(top,both sidgs,and toe)on a'geologic map of the site.
Located on Maps)C2e.4r 1l/t=°2(Ted•8 )
(5) A minimum of one cross section at a scale which adequately depicts the subsurface profile,and
which incorporates the details of p ed grade changes_
Located on Map(s)So. Fro. la G
(6) A description and results of slope stability analyses performed for both static and seismic loafing
conditions.Analysis should examine worst case failures.The analysis should include the
Simplified Bishop's Method of Ckdes.The mk*Tvn static safety factor is 1.5,the minimum
seismic safety factor is 1.1.and the quasi-static analysis marts should be a value of 0.15.
Located on page(s) /0 " /4on, i7
(7) (a)Appropriate restrictions on placement of drainage feattfes
Located on page(s) /K
(b) Appropriate restrictions on placement of septic drain fields
Located on page(s) I I
(c) Appropriate restrictions on placement of compacted lift and footings
Located on page(s) 13, IS
Page 1 of 2 Form Effective June 2008
Disclaimer: Mason County does not certify the quality of the work done in this Geotechnical Report.
1
(d) Recommended buffers from the landslide hazard areas shorellne'bluffs and the tops of other
slopes on the propeTtV.
Located on page(s)
(e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of
other slopes on the property.
Located on page(s)
(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 remoya1.
Located on page(s)
(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, lands) s and harmful construction methods.
Located on page(s) �//
(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) I6 17
(12) Recommendations for the preparation of structural mitigation or details of other proposed
mitigation.
Located on page(s) h tJn�e ys liu;l on q s6p�,�se zP. 16
(13) A site map drawn to scale showing the property.bqunc(aries,scale,north arrow, and the location
and nature of existin artd proa sed deve,'opment on"site,
Located on Map(s) �, r nn.
T�7
t, hereby co tlfY under penalty of
perjury that I am a civil tagirmw Iicnsed in the State of Washington with specialized knowledge of
geotechnicallgeotogicai engineering or a geologist or engir»g geologist Ocensed in the state of
Washington with specla l knowledge of the local conditions..t also cergy the the GeOkK-Anicat
Report, dated/41av 20
10 and entitled _(
t, Y -00 Ark rn meets ag the requirements of the Mason
County Resource ice.LandrJlde Hazard Section.is cornplefe and true.that the assessment
demonstrates conclusively that the risks posed by the landslide hazard can be mitigated through the
Induded geotechnicai design r .and th"an hwards are mid in such a manner as
to prevent harm to property and public health and safety.(SIe and stamp)
rc by
WAsyj
43l}45 O w
NAc.E`1G
Page 2 of 2 Form Effective June 2008
Disclaimer. Mason County does not certify the quality of the work done In this Geotechnfcal Report.
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.
c
Applicant's Name: teO Z*25r/7
Permit#: &a oli/ 7'00f Y79 Parcel #: 000 4 0
Date(s) of the Document(s) reviewed: 511i9llp
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: /00
(d) A discussion of the upslope geomorphology
OK? ✓ Comment:
(e) A discussion of the location of upland waterbodies and wetlands
OK? ✓ Comment:
(f) A discussion of history of landslide activity in the activity in the vicinity, as available in the referenced maps
and record /
OK? Comment: Coa// aSS''O /alto-tf r�c��'o�l� S/ �P 1
2. A site plan which identifies the important development and geologic features.
OK? ✓ Comment:
3. Locations and logs of exploratory holes or probes.
OK? Comment: c>? lees 7t /J/
(5 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.✓Comment: 0&0 S�I��a��G. Ss .,o� S�'ls�d�7 ��a O f
OK? W�r' S� ^a 5�^"�`'�•
5. A minimum of one cross section at a scale which adequately depicts the subsurface profile, and which
incorporates the details of proposed grade changes.
OK? '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: fl%fffll o CIA 340e Zi "6 LA )1/4T JuSf
7. (a) Appropriate/restrictions on placement of drainage features
ff
OK? Comment:
Page 1 of 2 Form Effective June 2008
(b) Appropriate restrictions on placement of septic drain fields
OK? Comment:
(c) Appropriate restrictions on placement of compacted fills and footings
OK? ✓ Comment:
(d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other slopes on the
property. O �u /� o' �/A•
OK? ✓ Comment: ��0� /fdf ,/YIOAh►rh / 4u i � � G "�
(e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of other slopes on the
property. / /
OK? ✓ Comment: � r0CT - �w 3
(�8 ;?Recom mend ations 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.
7 /( a/Pa-5
(/O Comment: a to e le-e:"11-7
rKe ar pt >y0
9. Recommendations for the preparation of a detailed temporary erosion control plan whidh identifies the specific
mitigating measures to be implemented during construction to protect the slope from erosion, landslides and
harmful construction methods.
OK? ✓ Comment: Ayl_ezelywf rl/. 17. 5�o
10. An analysis of both on-site and off-site impacts of the proposed development.
OK? Comment:
11. Specifications of final development conditions such as, vegetative management, drainage, erosion control, and
buffer widths.
OK? • Comment:
12. Recommend tions 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
existing and proposed development on the site.
OK? Comment:
Are the Documents signed and stamped? By whom? /u., C_•S
License#: 'V 30 License type: g!5�' e..-
-If not approved, what is the next action/recommendation for further action?
/r G/n X --
Reviewed by ele �rSf►� on 1'30 7�0 Time spent in review: �u/r
SECOND REVIEW/UPDATE:
Reviewed by on . Time spent in second review:
THIRD REVIEW/ UPDATE:
Reviewed by on
Time spent in third review:
Disclaimer. Mason County does not certify the quality of the work done in this Geological Report.
Page 2 of 2 Form Effective June 2008
TABLE OF CONTENTS
1.0 INTRODUCTION...........................................................................................................................1
1.1 PROJECT INFORMATION............................................................................................................... 1
1.2 PURPOSE OF INVESTIGATION AND SCOPE OF WORK..................................................................... 1
2.0 SURFACE CONDITIONS..............................................................................................................3
2.1 GENERAL OBSERVATIONS............................................................................................................3
2.2 TOPOGRAPHY...............................................................................................................................3
2.2.1 Upslope Geomorphology and Water Bodies.......................................................................... 3
2.3 SURFACE DRAINAGE.....................................................................................................................3
2.4 SLOPE AND EROSION OBSERVATIONS...........................................................................................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
3.31 Groundwater......................................................................................................................... 7
3.4 SOILS TESTING.............................................................................................................................7
4.0 ENGINEERING ANALYSES AND CONCLUSIONS...................................................................8
4.1 SLOPE STABILITY .........................................................................................................................8
4.1.1 Slope Stability Analysis....................................................................................................... 10
4.1.2 Slope Stability Assessment...........................................................................................I...... 10
4.L3 Septic Drainfield Impact to Critical Slopes.......................................................................... 11
4.2 EROSION..................................................................................................................................... 11
4.3 SEISMIC CONSIDERATIONS AND LIQUEFACTION......................................................................... 11
4.3.1 Liquefaction........................................................................................................................ 11
4.4 LATERAL EARTH PRESSURES...................................................................................................... 12
4.5 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
5.22 Placement and Compaction of Native Soils and Engineered Fill........................................ 15
5.23 Retaining Wall Backfill....................................................................................................... 16
5.3 BUILDING AND FOOTING SETBACKS........................................................................................... 16
5.4 SURFACE AND SUBSURFACE DRAINAGE...................................................................................... 16
5.5 VEGETATION BUFFER AND CONSIDERATIONS............................................................................. 17
5.6 TEMPORARY AND PERMANENT EROSION CONTROL................................................................... 17
6.0 CLOSURE..................................................................................................................................... 18
Appendix A-Site Plan
Appendix B-Geologic Map
Appendix C-Soil Information(Soil Profile; Soil Logs; Well Reports)
Appendix D-Slope Stability Input&Output
Appendix E-Erosion Control
Appendix F-Drainage Details
1.0 INTRODUCTION
Envirotech Engineering (Envirotech) has completed a geotechnical investigation for a single
family residential property located off of State Route 106, identified as parcel number 32236 75
00060, also known as Resulting Parcel 6 of BLA 10-10 under Auditors File # 1956202 and
1956203, Mason County, Washington. See the vicinity map on the following page for a general
depiction of the site location.
The geotechnical investigation was conducted at the request of the property owner, Bruce Larson,
in support of the proposed development as detailed below. The proposed development, as
provided herein, and the surrounding area is identified in this report as the Project.
An initial geotechnical evaluation of the Project was conducted by Envirotech on April 14, 2010.
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. Consequently, 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 in order to fulfill the MCRO.
As presented herein,this report includes information pertaining to the Project in this Introduction
Section; observations of the property and surrounding terrain in the Surface Conditions Section;
field methods and soil descriptions in the Subsurface Investigation Section; supporting
documentation with relation to slope stability, erosion, seismic considerations, and lateral earth
pressures in the Engineering Analyses and Conclusions Section; and, recommendations for
foundation, settlement, earthwork construction, retaining walls, erosion control, drainage, and
vegetation in the Engineering Recommendations Section.
1.1 Project Information
Information pertaining to the Project was provided by the proponent of the property during the
geotechnical investigation. Other information, such as site observations and assumed parameters
typical of this type of development were provided by Evirotech during the preparation of this
report.
The planned development consists of a 1- or 2-story single family residence, on-site septic
system, driveway and other ancillaryfeatures typical of this a of development. Foundation
Y Y
n'P type
construction is expected to consist of continuous strip footings with concrete slabs-on-grade or ;
stem walls.Approximate building footprint-and other proposed features with relation to existing
site conditions are illustrated on th'Site Map provided in Appendix A of this report.
9�I lf7
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
Envirotech Engineering Larson Geotechnical Report
74 NE Hurd Road page 1 State Route 106
Belfair,Washington 98528 Parcel 32236 75 00060
Ph. 360-275-9374 Mason County, Washington
Fax: 360-275-4789 May 19,2010
subsurface conditions, and evaluating the suitability of the soils to support the planned site
activities.
In order to fulfill the purpose of investigation, the geotechnical program completed for the
proposed improvements of the Project include:
• Review project information provided by the Project owner and/ or owner's
representative;
• Conduct a site visit to document the site conditions that may influence the construction
and performance of the proposed improvements of the Project;
• Define general subsurface conditions of the site by observing subsoils within test pits
and/ or cut banks, review geological maps for the general area, research published
references concerning slope stability, and review water well reports from existing wells
near the 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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Vicinity Map from Mason County Website
Envirotech Engineering Larson Geotechnical Report
74 NE Hurd Road page 2 State Route 106
Belfair,Washington 98528 Parcel 32236 75 00060
Ph. 360-275-9374 Mason County,Washington
Fax: 360-275-4789 May 19, 2010
2.0 SURFACE CONDITIONS
Information pertaining to the existing surface conditions for the Project was gathered on April 14,
and May 10, 2010 by Michael Staten, geotechnical engineer with Envirotech. During the site
visit,the type of geotechnical investigation was assessed,site features were documented that may
influence construction, and site features were examined that may be influenced by construction.
This Surface Conditions Section provides information on general observations, vegetation,
topography, drainage and observed slope/ erosion conditions for the Project and surrounding
areas that may impact the Project.
2.1 General Observations
The property is accessed from a gravel access road linking State Route 106. The Project is
currently undeveloped land. The Hood Canal is located approximately 250 feet to the northwest
of the property. Beyond the property, rural residential development exists. Vegetation on and near
the Project consists primarily of secondary growth firs, madronas, cedars, huckleberry, 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.
Maximum descending grades near the planned development is approximately 20%with a vertical
relief of over 50 feet. A steep highway cut is beyond this slope, and is not within the zone of
influence for this Project.
2.2.1 Upslope Geomorphology and Water Bodies
Ascending grades are generally located to the southeast of the planned development. This
slope is approximately 42%with a vertical relief of about 22 feet. The upland area of the
property is situated on a hillside with local crests. Additional geomorphology that is
pertinent to both upslope and downslope areas are provided in the Subsurface
Investigation Section of this report.
There are no apparent water bodies or wetlands located directly upslope from the planned
development that would significantly influence the Project.
2.3 Surface Drainage
Stormwater runoff originating upslope from the anticipated development is expected to be
minimal. Runoff 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. Drainage problems within the nearby
Envirotech Engineering Larson Geotechnical Report
74 NE Hurd Road page 3 State Route 106
Belfair,Washington 98528 Parcel 32236 75 00060
Ph. 360-275-9374 Mason County,Washington
Fax: 360-2754789 May 19,2010
convergences have been known to be severe, but appear to not influence this Project.
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.
Significant mass wasting on the property or within the general vicinity of the Project were not
observed. Indications of past landslides, current unstable slopes, deep-seated slope problems, or
surficial slope failures were not observed during the site visit.
l
Aerial Photo from Mason County Website
Envirotech Engineering Larson Geotechnical Report
74 NE Hurd Road page 4 State Route 106
Belfair,Washington 98528 Parcel 32236 75 00060
Ph. 360-275-9374 Mason County, Washington
Fax: 360-275-4789 May 19,2010
3.0 SUBSURFACE INVESTIGATION
Information on subsurface conditions pertaining to the Project was primarily gathered on May 10,
2010 by Michael Staten, geotechnical engineer with Envirotech. Specific information on field
methods, sampling, field testing, general geologic conditions, specific subsurface conditions, and
results from soil testing are presented in this section of the report. Appendix C of this report
includes pertinent information on subsurface conditions for the Project, such as subsoil cross-
section(s),test pit log(s),and water well report(s). Applicable test pit locations are depicted on the
Site Plan provided in the appendix of this report.
3.1 Field Methods, Sampling and Field Testing
Information on subsurface conditions for the Project was accomplished by examining soils within
test pits extending to depths of up to 4 feet below the existing ground surface. Information on
subsurface conditions also included reviewing geological maps representing the general vicinity
of the project, and water well reports originating from nearby properties.
One bulk sample was collected at the Project site at approximately 18 inches below the existing
ground surface near the anticipated building location. The soil sample collected was secured and
transported for possible laboratory testing.
Envirotech measured the relative density of the near-surface in-situ soils by gauging the
resistance of hand tools. Within testing locations, field testing results generally indicated medium
dense soils in the upper 42 to 48 inches with very dense soils below.
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, Q8. 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.
According to the "Interactive Geologic Map, 1:100,000 Quadrangle," as depicted by the
Department of Natural Resources, this Project consists mostly of glacial till, Qo,, with the lower
portion of the property classified as advanced outwash. Glacial Till is usually described as
"unsorted, unstratified, highly compacted mixture of clay, silt, sand, gravel, and boulders
deposited by glacial ice of the Puget lobe; gray; may contain interbedded stratified silt, and
gravel; sand-size fraction is very angular and contains abundant polycrystalline quartz, which
distinguishes this unit from alpine till; cobbles and boulders are commonly striated and (or)
faceted; although unweathered almost everywhere, may contain cobbles or small boulders of
deeply weathered granitic rock."
Envirotech Engineering Larson Geotechnical Report
74 NE Hurd Road page 5 State Route 106
Belfair,Washington 98528 Parcel 32236 75 00060
Ph. 360-275-9374 Mason County, Washington
Fax: 360-2754789 May 19,2010
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 composed of native soils with no indications of borrowed fill. For engineering
purposes,these native soils consist of distinguishable layers, as presented below.
Soils within the upper 3.5 to 4 feet of natural ground were observed to be moist,brown silty sand
with gravel (SM), and poorly graded sand with gravel(SP)and traces of silt.
Soils below the upper 3.5 to 4 feet layer were observed to be mostly grey, low moisture, silty
sand with gravel (SM). These soils were very dense, and are locally known as hardpan. The
hardpan may extend to depths greater than 10 feet. This is based on nearby well reports, site
geology, and/or knowledge of the general area.
The relative densities of the soil are provided above in Section 3.1. Expanded and specific
subsurface descriptions, other than what is provided in this section, are provided in the soil logs
located in Appendix C 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,with 15%-45%slopes. The soil designations are depicted in the aerial photograph below.
s.
A ..r
T22N R7W r�
t'
Soil Survey From USDA Natural Resources Conservation Service
Envirotech Engineering Larson Geotechnical Report
74 NE Hurd Road page 6 State Route 106
Belfair,Washington 98528 Parcel 32236 75 00060
Ph. 360-275-9374 Mason County,Washington
Fax: 360-275-4789 May 19,2010
3.3.1 Groundwater
From the water well report(s)and knowledge of the general area,permanent groundwater
is at least 100 feet directly below the property at the building pad location. Perched
groundwater at shallow depths was not observed on-site, nor indicated on the well
reports.
3.4 Soils Testing
The soil samples obtained at the Project site during the field investigation were preserved and
transported for possible laboratory testing. Visual classification of soils was performed in the
field at all observed soil profiles. Visual classifications were performed in accordance with the
American Standards for Testing and Materials (ASTM D2488).
The general results from the visual classification are presented above in the Subsurface
Conditions Section. Specifically, soils within the upper 4 feet in one testing location consisted of
approximately 20% gravel, 70% sand-sized soils, and 10% fines with low plasticity. Minor
variations observed during the visual classification of particle size content (i.e. gravel, sand,
fines), or isolated pockets within the soil stratification were insignificant in relation to the overall
engineering properties of the soil.
Envirotech Engineering Larson Geotechnical Report
74 NE Hurd Road page 7 State Route 106
Belfair,Washington 98528 Parcel 32236 75 00060
Ph. 360-275-9374 Mason County,Washington
Fax: 360-275-4789 May 19, 2010
4.0 ENGINEERING ANALYSES AND CONCLUSIONS
The following sections present engineering analyses and conclusions with relation to the existing
conditions and proposed improvements of the Project. This section includes slope stability,
erosion, seismic considerations, lateral earth pressures, and impacts to both on-site and off-site
properties.
4.1 Slope Stability
Landslides are natural geologic processes, and structures near slopes possess an inherent risk of
adverse settlement, sliding or structural damage due to these processes. Geotechnical engineering
cannot eliminate these risks for any site with sloping grades because gravity is constantly
inducing strain on the sloping soil mass. Excessive wet weather and/ or earthquakes will
exacerbate these strains. Geotechnical engineering considers excessive wet weather and `design'
earthquakes in order to provide an acceptable factor of safety for developing on or near sloping
terrain for the current conditions. These factors of safeties are based on engineering standards
such as defining engineering properties of the soil, topography, water conditions, seismic
acceleration and surcharges.
Surface sloughing or other types of surficial slope movements usually do not affect the deep-
seated structural capability of the slope. However, excessive and/or repeated surficial slope
movements, if not repaired, may represent a threat to the structural integrity of the slope. If this
situation does arise, the slope shall be inspected by a ggoWinical en ineer. ubsequently,
maintenance may be required in order to prevent the possibility of further surficial or deep seated
slope movements that may be damaging to life and property.
According to the Coastal Zone Atlas of Mason County, Washington, the Project is within and
near terrain labeled `Stable' and `Intermediate' regarding potential landslide activity. Stable
slopes are generally not prone to landslides due to small grades and accommodating geology.
Historically, intermediate terrains have no known landslides. However, this site is considered
inherently hazardous due the existing geology and/ or topography, and additional analyses and
recommendations concerning the slopes are presented herein. A Stability Map from the Coastal
Zone Atlas for the general area of this Project is provided below:
Envirotech Engineering Larson Geotechnical Report
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Y
t
AX
a �
Project x _
Map from Washington State Department of Ecology Website
According to the Resource Map from the Washington State Department of Natural Resources
(DNR), the Project is not within terrain labeled `highly unstable' relating to soils. DNR labeled
portions of this project as medium and high slope instability with relation to slopes. This
delineation is primarily dependent upon slopes and convergence. Secondly, lithology and
precipitation are modeled within this delineation. In summary, this designation is based on
mapping without field observations or knowledge of the specific site geology or soils. A
Resource Map from the DNR Forest Practices Application Review System is provided below:
M]03109 K NTOPJ !—
c i
110118e •f� ,' ITO4490
{Y.`F ....♦ f
aL
Project
,ih�ilea 1Ta4ea iTw
F
1 TM240
Resource Map from Washington State Department of Natural Resources Website
Envirotech Engineering Larson Geotechnical Report
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4.1.1 Slope Stability Analysis
Based on site geology, a non-circular slope stability analysis should be performed.
However, the Simplified Bishop Method, as presented herein, was utilized. Although the
method of circles could be an inappropriate tool, it is almost invariable much more
conservative in these situations than other conforming slope stability models. In addition,
the geotechnical analysis utilized the subsurface angle of repose,where necessary.
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 4 feet soil depth
Soil unit weight: 135 pcf
Angle of internal friction: 35 degrees
Cohesion: 0 psf
Soils below 4 feet in depth
Soil unit weight: 140 pcf
Angle of internal friction: 40 degrees
Cohesion: 400 psf
Based on the slope stability analysis, a minimum factor of safety was determined to be
1.7 relative to static slope failures, and 1.0 with relation to seismic conditions. These
factor of safeties were primarily limited to the face of the steep slope. The upslope
dynamic factor of safety applies to only the upper 6 inches of soil over a small span of
about 8 feet. For a significant soil mass,the dynamic factor of safety is well over 1.1. See
the slope stability in ornia on m ppen x or a depiction o input parameters and
example of outputs.
4.1.2 Slope Stability Assessment
DNR indicatedXrgyjVm3alod_slide activity and unstable slopes near the Project. However,
insta i ity appears to be within highway cuts and convergences located away from the
Project. Based on the proximity of the DNR delineations with respect to the proposed
development, and results of the aforesaid slope stability analysis it is our opinion that the
proposed development should occur in accordance with this geotechnical report.
Envirotech Engineering Larson Geotechnical Report
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4.1.3 Septic Drainfield Impact to Critical Slopes
The approximate location of the proposed septic drainfield is presented on the Site Plan
in Appendix A of this report. Based on the septic drainfield location with relation to the
existing and proposed topography,the drainfields are not expected to adversely influence
the structures near the critical slopes. This is also based on compliance with the
recommendations in this report.
4.2 Erosion
Based on the USCS description of the Project soils, the surface soils are considered low to
moderately erodible. According to the Resource Map from the Washington State DNR, as
provided above,the Project is not within terrain labeled `highly erodible.'
Undisturbed vegetation and grass lawns located downslone from land disturbing activities should
be sufficient for erosion control. 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. Additional erosion control measures may need to be employed if
excessive erosion occurs or required by the County or other prevailing agencies.
The Temporary and Permanent Erosion Control Section (Section 5.6) of this report consists of
specific erosion controls, if necessary. 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
Soils immediately below the expected foundation depth for this Project are generally Type D,
corresponding to the International Building Code(IBC) soil profiles. Soils below a depth of 4 feet
from the existing ground surface may be considered Type C. According to the IBC, the regional
seismic zone is 3 for this Project. The estimated peak ground acceleration ranges from 0.50g to
0.60g. This estimation is based on the United States Geological Survey(USGS)National Seismic
Hazard Project in which there is an estimated 2% probability of exceedance within the next 50
years.
There are no known faults beneath this Project. The nearest Class `A' or Class `B' fault to this
property is the Tacoma Fault Zone, in which is less than 2 miles to the northeast of this Project.
This information is based on the USGS Quaternary Fault and Fold Database for the United States.
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.
Envirotech Engineering Larson Geotechnical Report
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gravel, sand, silt). Although gravel-and silt-sized soil particles could be problematic, fine
and medium grained sands are typically subjected to these types of seismic hazards. No
significant saturated sand stratifications are anticipated to be within the upper 50 feet of
the subsoil for this Project.
4.4 Lateral Earth Pressures
Retainingwalls may be utilized for this Project. The lateral earth pressures exerted through the
Y J
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.
An equivalent fluid unit weight used for structural design may be estimated as the product of the
backfill soil unit weight and the earth pressure coefficient for at-rest pressures. Retaining walls
should be designed to resist a lateral earth pressure based on an equivalent fluid unit weight of 45
pounds per cubic foot (pcf)and 55 pcf for backfill consisting of engineered fill and native soils,
respectively. These values shall be increased by 1 pcf for every 1 degree of backfill/natural slope
angle. These equivalent fluid unit weight values do not include lateral earth pressures induced by
earthquakes or surcharges from live loads. See the Earthwork Construction Recommendations
Section for details concerning the use of native soils, engineered fill and placement of backfill.
Lateral earth pressure recommendations are based on active or at-rest earth pressures, and the
backfill conforming to the recommendations outlined in the Earthwork Construction
Recommendations Section of this report. For instances when it is necessary for the retained earth
to induce passive earth pressures, additional design parameters must be accounted for in the
retaining wall analysis. For theses cases,recommendations should only be provided by a qualified
engineer after the type of backfill is specified, and the final wall height is determined.
4.5 On-Site and Off-Site Impacts
From a geotechnical position, it is Envirotech's opinion that the subject property and adjacent !
properties to the proposed development should not be significantly impacted if all
recommendations in this report are followed. This is based on the expected site development,
existing topography, land cover, and the recommendations presented in this report.
Envirotech Engineering Larson Geotechnical Report
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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 coil
investi ation.
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. The
soils on-site have low to moderate frost susceptible characteristics and should be used only to the
extents provided in this report.
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 16 inches shall be placed at a minimum of 12 inches below the existing
-- --- ------- i
ground surface. These bearing capacity requirements also apply to isolated outings,
except the width should be increased to 24 inches for both round and square foundations.
Envirotech Engineering Larson Geotechnical Report
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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.
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 (Passing U.S. Sieve #10 or greater) that is placed over
undisturbed native subgrade or engineered fill. Native soils found at the Project site may
be suitable for use as material directly beneath concrete slabs if it meets the aforesaid
requirements or screened to meet these requirements. The top 2 to 6 inches of native soil
should be removed prior to the placement and compaction of the aforementioned 4-inch
coarse,granular material.
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
geotechnical engineering, concrete slabs should also be designed for structural integrity
and environmental reliability. This may include some type of vapor barrier 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. Compacted
engineered fill, or selective re-compacted native soils may be used to the extents provided in this
Earthwork Construction Recommendations Section. The following recommendations include
excavations, subgrade preparation,type of fill, and placement of fill for building foundations.
5.2.1 Excavation
Excavation is recommended to remove any excessive organic content or other deleterious
material, if present, beneath foundations and to achieve appropriate foundation depth.
Additional sub-excavation will be required for this Project if the soils below the required-
foundation depth are loose, saturated, or otherwise incompetent due to inappropriate land
disturbing, or excessive water trapped within foundation excavations prior to foundation
construction. All soils below the bottom of the excavation shall be competent, and
relatively undisturbed or properly compacted fill. If these soils are disturbed or deemed
incompetent, re-compaction of these soils below the anticipated footing depth is
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necessary. Excavations shall be completely dewatered, compacted, and suitable before
placement of additional native soil, engineered fill or structural concrete. It is suggested
that foundation excavations are inspected by a geotechnical engineer or qualified
professional in order to assess the bearing material prior to the placement of structural
footings.
5.2.2 Placement and Compaction of Native Soils and Engineered Fill
For engineered fill or disturbed native soils that will be utilized as fill material directly
beneath foundations, observation and/ or geotechnical testing is required prior to
foundation construction. The following placement and compaction requirements are
necessary.
For disturbed native soils or engineered fill beneath foundations, limits of compacted or
re-compacted fill shall extend laterally from the bottom edge of the foundation at a rate of
one foot for each foot of compacted or re-compacted fill beneath the foundation. See the
illustration below.
FOOTING
COMPACTED
NATIVE SOILS
OR ENGINEERED 1
FILL 1
1-1
I I 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. Engineered
fill should consist of the following gradation:
U.S. Standard Sieve %Finer(by weight)
6" 100
3" 60— 100
No. 4 20—60
No. 200 0 - 8
Table 1
Partical Size Distribution of Engineered Fill
Compaction shall be achieved in compacted lifts not to exceed 8 inches and 12 inches for
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.
Envirotech Engineering Larson Geotechnical Report
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5.2.3 Retaining Wall Backfill
Native soils may be used as retaining wall Backfill for this Project if the
recommendations below are followed. Backfill may also 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 to 24
inches. Each lift should be uniformly compacted to no more than 90% of the modified
Proctor maximum dry density (ASTM D 1557). In addition, heavy construction
equipment should be at a distance of at least %s 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.
Backfill for the retaining wall should extend vertically from the top of the footing to the
proposed ground surface. The backfill should also extend horizontally from the back of
the retaining wall to at least 2 feet. Perforated drain pipe for retaining walls should have a
minimum diameter of 4 inches and direct water to an appropriate infiltration or outfall as
recommended in the Surface and Subsurface Drainage Section of this report. Coarse,
clean gravel(1 inch diameter) is recommended to be placed at least 24 inches around the
drain pipe in order to provide increased drainage capabilities.Non-woven geotextile filter
fabric designed to impede fine particles should be wrapped around the aforementioned
coarse gravel for reducing the potential of silt migration and clogging of the drain pipe.
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 zero feet building
setback from the toe of the nearby ascending slope exceeding 40%.
The required setbacks may be reduced, if necessary. The residence may be developed on the face
of the 40% slope with an engineered foundation design. This may include engineered stem/
retaining walls and additional earthwork recommendations.
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 Tr
Project structures. All constructed surface and subsurface drains should be adequately maintained
during the life of the structure. If drainage problems occur during or after construction, additional
engineered water mitigation will be required. This may include a combination of swales, berms,
drain pipes, infiltration facilities, or outlet protection in order to divert water away from the
structures to an appropriate protected discharge area.
Envirotech Engineering Larson Geotechnical Report
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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 an appropriate infiltration location downslope from the residence.
Footing drains may be tied to roof drains if a backflow preventer is used to prevent water from
entering the foundation. Infiltration facilities shall be at least 10 feet from foundations, and 30
feet from septic drainfields. Recommended infiltration locations are delineated on the Geologic
Map in Appendix B, and drainage details are provided in Appendix F of this report.
5.5 Vegetation Buffer and Considerations
Vegetation is an excellent measure to minimize surficial slope movements and erosion on slope
faces and exposed surfaces. By removing trees, the root strength is decreased over time, thereby
lowering the `apparent' cohesion of the soil. Transpiration is decreased, which results in
additional groundwater, increased pore water pressure and less cohesion/ friction of the soil
particles. Stormwater runoff also increases, and, fewer plants will create less absorption of the
force from raindrops,thereby creating the potential for erosion hazards.
Vegetation shall not be removed from the face of any slope with grades exceeding 40%.
However, any tree deemed hazardous to life or property shall be removed. If tree removal is
necessary, then stumps and roots shall remain in place, and the underbrush and soil shall remain
undisturbed as much as possible. Any disturbed soil shall be graded and re-compacted in order to
restore the terrain similar to preexisting conditions and drainage patterns.
5.6 Temporary and Permanent Erosion Control
Erosion control during construction should include minimizing the removal of vegetation to the
least extent possible. If necessary, erosion control measures during construction may include
stockpiling cleared vegetation, silt fencing, intercepting swales, berms, straw bales, plastic cover
or other standard controls. Native vegetation and grass lawns located downslope from the
development should be sufficient for controlling erosion during construction. If additional erosion
control is necessary, silt fencing is presented in this report as the first choice for temporary
erosion control. Any erosion control should be located down-slope and beyond the limits of
construction and clearing of vegetation where surface water is expected to flow. If the loss of
sediments appears to be greater than expected, or erosion control measures are not functioning as
needed,additional measures must be implemented immediately. See Appendix E for sketches and
general notes regarding selected erosion control measures. The Site Map in Appendix A depicts
the recommended locations for erosion control facilities to be installed, if necessary.
Permanent erosion control may also be necessary if substantial vegetation has not been
established within disturbed areas upon completion of the Project. Temporary erosion control
should remain in place until permanent erosion control has been established. Permanent erosion
control may include promoting the growth of vegetation within the exposed areas by mulching,
seeding or an equivalent measure. Selected recommendations for permanent erosion control are
provided in Appendix E. Additional erosion control measures that should be performed include
routine maintenance and replacement, when necessary, of permanent erosion control, vegetation,
drainage structures and/or features. The following Surface and Subsurface Drainage Section may
have additional recommendations with relation to permanent erosion for surface drainage
features.
Envirotech Engineering Larson Geotechnical Report
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Fax: 360-275-4789 May 19, 2010
6.0 CLOSURE
Based on the project information and site conditions as presented in this report, it is Envirotech's
opinion that additional geotechnical studies are not required to further evaluate this Project.
Due to the inherent natural variations of the soil stratification and the nature of the geotechnical
subsurface exploration, there is always a possibility that soil conditions encountered during
construction are different than those described in this report. Therefore, it is recommended that a
qualified engineer performs a site inspection during the earthwork construction if subsurface
conditions found on-site are not as presented in this report.
This report presents geotechnical design guidelines, and is intended only for the owner, or
owners' representative, and location of project described herein. This report should not be used to
dictate construction procedures or relieve the contractor of his responsibility.
Any and all content of this geotechnical report is only valid in conjunction with the compliance of
all recommendations provided in this report. Semantics throughout this report such as `shall,'
`should' and `recommended' imply that the correlating design and/or specifications must be
adhered to in order to potentially protect life and/ or property. Semantics such as `suggested' or
`optional' refer that the associated design or specification may or may not be performed, but is
provided for optimal performance. The recommendations provided in this report are valid for the
proposed development at the issuance date of this report. Changes to the site other than the
expected development, changes to ordinances or regulatory codes, or broadening of accepted
geotechnical standards may affect the long-term conclusions and recommendations of this report.
The services described in this report were prepared under the responsible charge of Michael
Staten, a professional engineer with Envirotech. Michael Staten has appropriate education and
experience in the field of geotechnical engineering in order to assess landslide hazards,
earthquake hazards, and general soil mechanics.
Please contact Michael Staten at 360-275-9374 if you have any questions, comments, or require
additional information.
Sincerely,
Envirotech Engineering
Michael Staten, P.E.
Geotechnical Engineer
Envirotech Engineering Larson Geotechnical Report
74 NE Hurd Road page 18 State Route 106
Belfair,Washington 98528 Parcel 32236 75 00060
Ph 360-275-9374 Mason County, Washington
Fax: 360-275-4789 May 19,2010
APPENDIX A
SITE PLAN
SCALE: 1 INCH = 150 FEET
,fUNDISTURBED VEGETATION OF
AT LEAST 50 FEET IN LENGTH 0 75 150
FOR VEGETATIVE FLOW PATH
2
PROPOSED SILT FENCE
�(TYP) IF NECESSARY REPOSED (2) 2FT X 50 FT
PROPOSED SEPTIC ROOF INFILTRATION TRENCHES
PR
PROPOSE LD SEE DRAINAGE DETAILS
PPRX) ��yf
F` �9
ors
rj
tiC ACCFsf �Oy REPOSED SINGLE
tp0 R�qd P2 �.� FAMILY RESIDENCE
t20 j ROPERTY LINE
REPOSED 4A,* 200
DRIVEWAY T 1
lAD PPRX)
160 220
i
t�
hn°
240
y60
LEGEND
2g0 TEMPORARY
+ 'EROSION CONTROL
SLOPE INDICATOR
300 BO EXISTING CONTOUR
TPIe TEST PIT
PROJECT/ OWNER/ LOCATION-
SINGLE FAMILY RESIDENCE
NOTES, GE❑TECHNICAL REPORT
1. EROSION CONTROL MAY BE REQUIRED FOR THIS SITE. GENERAL LOCATIONS
ARE DEPICTED, AND ALTERNATIVES MAY BE UTILIZED AS EXPLAINED IN THE BRUCE LARSON
GEOTECHNICAL REPORT. RESULTING PARCEL 6 OF BLA 10-10
2. CONTOURS WERE NOT PREPARED BY A LICENSED LAND SURVEYOR. PARCEL 32236 75 00060
CONTOURS WERE EXTRAPOLATED FROM A PUBLIC LIDAR SOURCE, AND MASON COUNTY WASHINGTON
INCORPORATED FIELD MEASUREMENTS AS EXPLAINED IN THE GEOTECHNICAL ENGINEER,
REPORT. ENVIROTECH ENGINEERING
3. BOUNDARIES WERE NOT PREPARED BY A LICENSED SURVEYOR, LOCATION OF 74 NE HURD ROAD
PROPERTY LINES AND SITE FEATURES, SUCH AS TOP OF SLOPES, WATER BELFAIR, WASHINGTON 98528
FEATURES, ETC.., WITH RELATION TO THE PROPERTY LINES MUST BE 360-275-9374
VERIFIED BY THE OWNER. RECOMMENDATIONS IN THIS REPORT PROVIDE
SETBACKS, DEPTHS, ETC.. WITH RELATION TO GEOLOGIC FEATURES, NOT SITE PLAN
PROPERTY LINES.
APPENDIX B
GEOLOGIC MAP
A
SCALE, I INCH = 150 FEET
NDISTURBED VEGETATION OF
AT LEAST 50 FEET IN LENGTH 0 150
FOR VEGETATIVE FLOW PATH
PR OSED SILT FENCE
( P) IF NECESSARY ROPOSED (2) 2FT X 50 FT
ROOF INFILTRATION TRENCHES
P OPOSED SEPTIC SEE DRAINAGE DETAILS
RAINFIELD
PPRX)
ROPOSED(A PR>RESIDENCE
g0
C�•F,, 9
S Q P2 �p�* BUILDING SETBACK AT
100 �d TOE OF SLOPE (SEE
REPORT)
PROXIMATE TOE OF
SLOPE EXCEEDING 40%
120 ROPOSED
DRIVEWAY
PRX>
T 9
140 A ROXIMATE TOP OF
S PE EXCEEDING 40%
160 220
DO NOT R VE VEGETATION FROM
FACE OF % SLOPE EXCEPT WHERE
TBO PERMITTE IN GEOTECHNICAL REPORT
SOILS- MEDIUM
DENSE SILTY SAND
(SM) AND POORLY
GRADED SAND (SP) ,,PROPERTY LINE
WITH GRAVEL
OVERLYING VERY
DENSE SM
240
260
2M30
300
PROJECT/ OWNER/ LOCATION
SINGLE FAMILY RESIDENCE
NOTES, GE❑TECHNICAL REPORT
1. ALTERNATIVES FOR REDUCING BUILDING SETBACKS OR VEGETATION BRUCE LARSON
BUFFERS MAY BE PROVIDED IN THE GEOTECHNICAL REPORT. RESULTING PARCEL 6 OF BLA ID-10
2. CONTOURS WERE NOT PREPARED BY A LICENSED LAND SURVEYOR. PARCEL 32236 75 00060
CONTOURS WERE EXTRAPOLATED FROM A PUBLIC LIDAR SOURCE, AND MASON COUNTY WASHINGTON
INCORPORATED FIELD MEASUREMENTS AS EXPLAINED IN THE GEOTECHNICAL LEGEN
REPORT. ENGINEER
3. BO ENVIROTECH ENGINEERINGINDARIES WERE N07 PREPARED BY A LICENSED SURVEYOR. LOCATION 74 NE HURD ROAD
OF PROPERTY LINES AND SITE FEATURES, SUCH AS TOP OF SLOPES, WATER —� SLOE INDICATOR BELFAIR, RD ROAD
98528
FEATURES, ETC.., WITH RELATION TO THE PROPERTY LINES MUST BE BELFAI5-9374
VERIFIED BY THE OWNER. RECOMMENDATIONS IN THIS REPORT PROVIDE --80� EXISTING CONTOUR
SETBACKS, DEPTHS, ETC.. WITH RELATION TO GEOLOGIC FEATURES, NOT GEOLOGIC MAP PROPERTY LINES. TPI TEST PIT
APPENDIX C
SOIL INFORMATION
VERTICAL AND HORIZONTAL SCALE;
1 INCH 40 FEET
0 1 40
MEDIUM DENSE POORLY GRADED
SAND AND SILTY SAND WITH
GRAVEL (SM-SP)
PROPOSED HOUSE
EXISTING GRA
DE
DE
DENSE GLACIAL TILL
SECTION A-A
PROJECT/ OVNER/ LOCATION-
SINGLE FAMILY RESIDENCE
GE❑TECHNICAL REPORT
GRATRIX
PARCEL 32218 50 00018
MASON COUNTY, WASHINGTON
NOTES-
1) MINOR GRADE CHANGES REQUIRED IN ORDER TO ACHIEVE ENGINEER
E ENGINEERING
POSITIVE DRAINAGE AND DRIVEVAY CONSTRUCTION. 74 NE NE HURD HURD ROAD
2) THE SOIL PROFILE IS ACCURATE FOR THE DEPTH OF BELFAIR, WASHINGTON 98528
THE OBSERVED TEST PITS AT THE SPECIFIED LOCATIONS. 360-275-9374
LOVER DEPTHS ARE BASED ON SITE GEOLOGY,
WELL LOG(S), AND/OR EXPERIENCE IN THE GENERAL AREA. S❑IL PROFILE
TEST PIT LOG
TEST PIT NUMBER TP-1
PROJECT: SFR Geotechnical Report DATE OF LOG: 5/10/2010
PROJECT NO: 1038 LOGGED BY: MCS
CLIENT: Bruce Larson EXCAVATOR: N/A
LOCATION: Parcel 32236 75 00060 DRILL RIG: None
Mason County, Washington ELEVATION: N/A
INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: N/A
SOIL STRATA, STANDARD PENETRATION TEST
DEPTH SAMPLERS USCS DESCRIPTION LL PI CURVE
AND TEST DATA DEPTH N 10 30 50
0 . ...... .........................................
SP Brown, moist, medium dense POORLY
GRADED SAND with GRAVEL and a
_ trace of silt. Gravel is primarily well
_ graded and subrounded to subangular.
Sand is mostly coarse. No plasticity.
2 K-
3 _ Grey and light brown, very dense, very
low moisture'hardpan'
Excavation terminated at approximately
4 3.5 feet
5
6
7
8
9
10
No Groundwater Encountered ENVIROTECH ENGINEERING
This information pertains only to this boring and should not be Geotechnical Engineering
interpreted as being indicitive of the entire site.
TEST PIT LOG
TEST PIT NUMBER TP-2
PROJECT: SFR Geotechnical Report DATE OF LOG: 5/10/2010
PROJECT NO: 1038 LOGGED BY: MCS
CLIENT: Bruce Larson EXCAVATOR: N/A
LOCATION: Parcel 32236 75 00060 DRILL RIG: None
Mason County, Washington ELEVATION: N/A
INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: N/A
SOIL STRATA, STANDARD PENETRATION TEST
DEPTH SAMPLERS USCS DESCRIPTION LL PI CURVE
AND TEST DATA DEPTH N 10 30 50
0 ............... .............. .. ..... .. ...
SM Brown, moist, medium dense SILTY
SAND with GRAVEL. Gravel is primarily
_ fine and subangular. Sand is mostly
1 medium and coarse. Low plasticity.
3
Grey and light brown, very dense, very
low moisture'hardpan'
C-- 4
Excavation terminated at approximately
4.0 feet
5
6
7
8
9
10
No Groundwater Encountered ENVIROTECH ENGINEERING
This inlormation pertains only to this boring and should not be Geotechnical Engineering
interpreted as being indicative of the entire site.
r
L `
0
Q
WATER WELL REPORT CURRENT
Original•I'copy-Ecology,e cW-owner,are copy-driller Notice of Intent No.W 2402N
A� OLPAI"MLMT Of
YS/ ECOLOGY ConstruetioWDeeommission (•'z"in cor�) - Unique Ecology Well ID Tag No.BAR 104
N ® Construction 49 Water Right Permit No.
ElIL Decommission ownvAL MrA now 1
+-�,, Ndloee It, Ntoltber Property Owner Name Mike Obiizalo
_ PROPOSED USK: 0 Domaetie ❑ ludlisdd ❑ MAnteval Well St vet Address 8830 E Stare Route 106
0 ❑ DeWatcr ❑ hrigation- ❑ Tom Well ❑ Oher
_
0 TYPE OF WORK: Owner's number of well(if m then t one) City Union County Mason _
® New well ❑ Raoaaioned i ifed wd:❑ rang El w
Bored ❑ Dnvm Dion rl@ 1/4-1/4 Sec
x Twn 22n R 3w gM ❑
fC ❑ �od 0 tibia [IRotary ❑ Jamd (s,t,r Still REQUIRED) or
E DI M MSIONS: Dianseter of well Q iaKbm&MadZZ tL W WtM
L Depth of coopleted well
0- CONSTRUCTION DETAILS Let/Long Lat Deg Lat Min/Sec
= Ca>ing 19 Welded G' Dian fiom +1 iL to 67 8. Long Deg Long N in/Sec
loMRed ❑ U.W mvallcd " Mwn-rrom tt to R Tax Parcel No,(Required)3223532oom
s ❑ Threaded - Diem.From 0.to IL
+'r Perforadom: 0 Yes 0 No
L Type of pcsfazafoi used CONSTRUCTION OR DECOatuNISSION PROCKDURK
0 Formation:Describe by color,character,sin of matavd and structure,and the 1®d and
1 SUE of m m and�.of from_tt b raurue aft material m esrh stratum penetrated,with at kart old entry for each change
��— �� ofmfarmatioa (USE ADDITIONAL SHEETS IF NECESSARY.)
� 9rss�s: ® Yes ❑ No ® K-Peer location 65
RMandacto es Name Johnson Br sand&gravelMA�L U FROM TO
�.r Typo stainless steel Model No. 14
Br fill 14 1 g
Dim_5slat sine 12 from 077&to 72 fL R b❑ Diem R.
Br day with gravel Soot 19 48 slot suer 6om
Dark br gravel&Water 48 53
Gra.tl/Fdthi packed: ❑ Yea ® No sin or paveUsand Tan fine sand Water bearing 53 72
4.0 Materiels placed from B to it
Sarfam Sea]: 0 Yes ❑ No To what dgAh?19.5fL
Mat nal mod in scat bentonite
LDid any strain contain uauelble ware(! El Yes ® No
L Type of c crier? Depth of=eau
R
Method of sealing meta off
F. PUMP. Marrttfactrasr's Name-goufd4 — — —_
O Type:sttbmersble Hp. 1
Z WATER LEVELS: Iod-sofmc elevation about mean sea level fi
tic
m -� ern
O Sta Ievtl 3 below top of well Date 3 5 10 Cn -0
a � Id
Artesian presauc_._lbs.pa square inch Date o (� �\ � t—(.
Artesian wwa is coW oiled by (-p.vat--�-) � C6 ,v r _
WKLL TESTS: Drawdowa is sumunt water level a lowered below sta ie level
0 Was a pump test made? ❑ Yes 10 No If yes,by whom7 O C C
0 Yidd: nl/min.with_R.drawdown affc hn_ 'Tt � a OD
V YwTd_gdlmin With_fL drawdown a8a bts,
W Y'WU-_—Val nin with-_&drawdown afta •fin. 00
0 Remarry dole(tmLe tahm as zero rA v pmrp ftvywd og(wmer lewd mono edfiom
weQ top to wmer level)
J..v
= Time Water Laud Time WatcrLevel Tuner WaterLevd
d
E
4-1
L
4) Bailer test 2Q PdJmm.with 19R.&.do.after 4hrs.
0 Anlest _gal/mm with stem set at tL for hM
Artesian flow zp.m. Date 3-5-10 Start Date 3-01-10 Completed Date 3-05-10
TemFaatmc of wattt was a chcmiml analysis®de? ❑ Yes 0 No
WELL CONSL•BUCTION CERTIFICATION: I conshucted and/or rr=oept tet.'pooslbildy for m=rudim of this welt arW ds complisom with all Washingmn well
ooasbutban standards. Materials used and the information reported above are tare to my bCM icomyledge and belict
Drilling Co nptmy KNAPP DRILLING
Dnikr Trainee N me L S Address 50 EAST LFSACA DR_
Drilic/Eogoetr/Tramce Sigtature City,State, SHELTON WA_48584
Dn71er or franc=Leetmse No.2921 T '
IE TRAINEE:Drilfer'S License No:1706 Contractors
Drdws SignaMM7 ; w fC,,,-C
Ron No. IINAPPD1952B1 Date �-10
ECY 0504-20(Rev 02/10) Ijyou need this docaone'a in mt alternate format,Please call the Water Resowres Program a/360-107-6872.
Persons wilh hearing loss can call 711 jor Washmgiorr Relay Service. Persons with a speech dmabiliry can call 877-833-6341.
File Original and ollrt Copy„;�,
Dee WATER WELT. REPORT
Department of Ecology Application No. ........
Second COPY—Owner's Copy
Third Copy—Driller's Copy Y�r� BTATs(W WAilit@ia"Pt permit No. ....
r (1) OWNER: N.afo?.....f.,Azea-44,..........................-•--••----.._......... Ad&..Wf 7 A1111.4
L (2) LOCATION OF WELL: �o,t„v_ 2[ _.. ..N.. x?.W.W.M.
CL d Bearing and distance from section or subdivision comer
(3) PROPOSED USE: Damsaae)d industrial p Municipal p (10) WELL LOG: - --
d Irrigation ❑ Teat Well ❑ Other ❑ Formation:Describe by color,character size of material and structure,and
*how lhiekrtm of agvf sad the kind and nature of tow material in each
of formatiew.
ehan
en
(4) TYPE OF WORK: owners number of weu > �•to ee at least oeach lwe try for Chan"H (if more than onel-... ._..............._._............_... stsaatrm MATlaIAL FROM TO
New wall Method: Dug C7 Bored 17
Deep-ad p Cable Jr Driven[] -r�L---------- —
C Reconditioned❑ Rotary❑ Jetted ❑
O
_ (5) DIMENSI S: Diameter of well ... ,k•.......... inches.
0 DriuedAR.Q..-.._.__n. Depth of completed ww1a ___._st aae.&1IeL�dL��Qrt.1l
(6) CONSTRUCTION DETAILS: — WJAII
E 6"v^&A., 6dWWCasing installed:5 " Diam. from _Q._... ft.to,/A& ft. 44)
Ow Threaded❑ ._sass__.._'Dian. from ._..._._._ft.to _. t<.Welda� ...-..__...... Dlam. from ......._..__ ft. to --_.._..-__ a --
Perforations: Yes❑ N0k' r —
Type of pesforator=ad._............---..._..................................................
O SIZE of perforations _......................_...... in. by ....._......._......-•_-. In.
perforation/from ....-..................fL to ___.._......__.... ft.
C --................ perforations front __.................. tL to _._._ __ sass ft.
perforations trom ....................... & to —----------ft.
SCr*M= Yes O NaX --
mmulacturees
Model No—_--__—...
clot size------- hero ------- n-to — --- n-
Diam—_..___...blot sire_____----from -------ft to_— _ rL
C Gravel padmd: T.Cl No)< aim of gravel: /i/ —
i P Gravel laced?seen ft.to................- ft.
----- _
S11rf0Ce gepl: Yes)< No❑ To what depth? 16 _---_.. !L S •� T —ter
Material used In seal.delua-U--174T....----...------ -------• - ��" r.
Did any strata contain Unusable wato. Yea❑ N.)IJ
OType of veto....................-------- Depth of etraza_._----•------
Z Method of sealing strata off............................ -
N
d (7) PUMP-
lianulacturer'■ Name..........................._.._...._...._..-•---.---.._.._
0 Type: ..._.._..___..._.._......__.._....-----..--._..._.........8p___..__.___._. —
�. (8) WATER LEVELS: Land—alace elevation
above mean sea level.... .............._.__—ti.
Ocm
static level ...l�'... ..------__ft.below top a! w.il Data; 24._.
OArtesian preseuee ..__.._....-._.._........Me. per aqua"Inch Data._--_-_-_-•............
(� Artesian water V controlled by-------------_.....__..___lve..-...____..-------..
LU (Gp, valve,eteJ
'~ (9) WELL TESTS: Drawdown is amount water level is ��ll '••rr — LL
O lowered 4low static level Work started.......D!...�..�.�......._, l9.76. completed.... �' ..... 1a...7r
�+ Was a pump test made? Yes❑ No.'If yes.by whom7............... .... ._._.....
Yield: gal-/min, with ft. drswdown after bra. WELL DRILLER'S STATEMENT:
This well was drilled raider my jurisdiction and this report is
" - true to the best of my knowledge and belief.
Recovery data (time taken as wro when pump turned off) (water level
tZ measured from well top to water level) 1•/' ,. l� / /��
Q rime Water Leysl Time Water Level Time Wader Level NAME. lIM�.GL- `rL. !!YL�...'lSe..-----.-.k. ...............
(Person,firm.or corporation) (Type or print)
---------------......
... ........_................._..._.... ........._....
z ......-••....... ..........................................................................•---..............-....... Address.- 1'l- �k1.S�t�.-- ZE??;'FJ!P711.tJ...�!/r.L--...
...................................I........................._..................._..........._sass_...- ...
Date of teat ..............s a ss _ ____sass_-...__.._.... [SlQlledl-/L�[/ frSQf.�+.✓t/..��.f
Bailer teat-. ..Q_.....=tlJmin.with-. 's..--.--..ft.drawdown after__A......h". (Well a )
Artesian�low_._._.._..._._.._� ------�.p�, Dow_...............
_.._.._.--•-
Temperature of water._._..___-Was a chemical analysis model Yes p Nq;;J� Llcense No d^"r'��.'. L?_ ---Date--2. r......----... 19 ._
(JIBE ADDITIONAL SJDLLPS 17 NECESSARY)
a.F.No.7336--08—I Rev.4-71)- a
APPENDIX D
SLOPE STABILITY
STABLE Slope Stability Analysis System
New User
Project Bruce Larson
Datafile: Dynamic : Bishop
SOILS
SOIL NAME LINETYPE-PEN COHESION FRICTION UNIT WT.
1 Soil-1 CONTINUOUS-BLACK 0.00 35.0 135.000
2 Soil-2 CONTINUOUS-BLUE 400.00 40.0 140.000
PORE PRESSURE SPECIFICATION
SOIL PIEZO RU EXCESS
Y/N/P Value Value
1 N 0.000 0.000
2 N 0.000 0.000
PIEZOMETRIC SURFACE
POINT
POINT PORE PRESSURES
POINT PRESSURE
SLIP DIRECTION (+/- X)
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
SLIP-CIRCLES
AUTOMATIC
Circle Centre Grid Extremities
190.000
+++++++++++++++
+ +
18.500 * * 166.500
+ +
+++++++++++++++
42.000
X spacing -- no. of cols (max 10)= 10
Y spacing -- no. of rows (max 20)= 20
Grid 1 Circles through point 9
Grid 2 Circles through point 10
Grid 3 Circles through point 11
Grid 4 Circles through point 12
Grid 5 Circles through point 13
Grid 6 Circles through point 14
Grid 7 Circles through point 15
STABLE Slope Stability Analysis System
New User
Project Bruce Larson
Datafile: Dynamic Bishop
STABLE Version 9.03.00u
Bishop
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
TITLE
Dynamic
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
UNITS (Metric/Imperial) = I
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
GEOMETRY DEFINITION
POINTS
NO. X Y
1 0.000 0.000
2 100.000 20.000
3 152.000 42.000
4 185.000 42.000
5 0.000 -4.000
6 100.000 16.000
7 152.000 38.000
8 185.000 38.000
9 18.500 3.700
10 26.290 5.260
11 34.080 6.820
12 41.870 8.370
13 49.660 9.930
14 57.450 11.490
15 65.240 13.050
16 73.030 14.610
17 80.820 16.160
18 88.610 17.720
19 96.390 19.280
20 104.180 21.770
21 111.970 25.070
22 119.760 28.360
23 127.550 31.660
24 135.340 34.950
25 143.130 38.250
26 150.920 41.540
27 158.710 42.000
28 166.500 42.000
LINES
Lo X Hi X SOIL
1 2 1
2 3 1
3 4 1
5 6 2
6 7 2
7 8 2
i
1 .00
1 . 1 O
1 . 20
1 . 30
1 . 40
1 . 50
1 . 6
1 . 7
1 .8
1 . 0
2 0
1
Project Bruce Larson
Datafile Static
Analysis Bishop
STABLE.2002 MZ Assoc;otes Ltd
J
1 .00
1 . 1 O
1 . 20
1 . 30
1 . 40
l . 50/
l . 6
i . 7
1 .8
� . o
2 .00
i
Project Bruce Larson
Dotafile Dynamic
Analysis Bishop
STABLE.2002 MZ 4ssoc;otes Ltd
APPENDIX E
EROSION CONTROL
GEOTEXTILE FABRIC 2'x2' WOOD POST (TYP) GEOTEXTILE FABRIC
WRAP AROUND TRENCH OR EQUIVALENT OR BETTER AND WIRE MESH
TO AT LEAST ENTIRE 2 6 FT MAX. O.C.
BOTTOM OF TRENCH 6 FT �� 0.5 FT
GRAVEL
BEFORE PLACING GRAL 2'x2'x5' WOOD POST OR
12' DEEP, 8' WIDE TRENCH EQUIVALENT OR BETTER EXISTING 1
FILLED WITH 3/4' TO 1 1/2'� 1 GROUND SURFACE 2`T
WASHED GRAVEL r 1
DIRECTION OF r 2'S1FT 12' DEEP, 8' WIDE
WATER FLOV t EXISTING TRENCH FILLED WITH 1 T
121 GROUND SURFACE 3/4' TO 1 1/2' 2.5 FT
I I 2.5 FT WASHED GRAVEL
BOTTOM EXTENTS OF
II GEOTEXTILE FABRIC SILT FENCE - DETAIL
SILT FENCE - CR SS SECTION N.T.S.
N.T.S. HAY OR STRAW MATTING
ENERAL NOTES, 1. STRAW SHALL BE AIR DRIED, AND FREE FROM WEED SEEDS AND
COARSE MATERIAL.
SHOULD THE TEMPORARY EROSION AND SEDIMENT CONTROL MEASURES SHOWN ON 2, APPLY AT APPROXIMATELY 75 TO 100 POUNDS PER 1000 SQUARE
HESE PLANS PROVE TO BE INADEQUATE DURING CONSTRUCTION, THE CONTRACTOR FEET OF GROUND.
HALL INSTALL ADDITIONAL EROSION AND SEDIMENT CONTROL FACILITIES. 3. MINIMUM THICKNESS SHALL BE 2 INCHES.
ALL EROSION AND SEDIMENT CONTROL FACILITIES AND DEVICES SHALL BE 4. HAY OR STRAW IS SUBJECT TO BLOWING. KEEP MOIST OR TIED
NSPECTED DAILY AND IMMEDIATELY MAINTAINED, IF NECESSARY. DOWN.
ALL EROSION AND SEDIMENT CONTROL FACILITIES AND DEVICES SHALL BE LEFT IN
LACE UNTIL THE UPSLOPE AREAS HAVE BEEN PERMANENTLY STABILIZED. PERMANENT EROSION CONTROL NOTES:
EMPORARY EROSION CONTROL NOTES: SEEDING FOR RAW SLOPES
OR ALL AREAS WHICH HAVE BEEN STRIPPED OF VEGETATION OR EXPERIENCED LAND 1. BEFORE SEEDING, INSTALL NEEDED SURFACE RUNOFF CONTROL
ISTURBING ACTIVITIES, AND WHERE NO FURTHER WORK IS ANTICIPATED FOR A MEASURES SUCH AS GRADIENT TERRACES, INTERCEPTOR DIKES,
ERIOD EXCEEDING THE LISTED CRITERIA BELOW, ALL DISTURBED AREAS MUST BE SWALES, LEVEL SPREADERS AND SEDIMENT BASINS,
MMEDIATELY STABILIZED WITH MULCHING, GRASS PLANTING OR OTHER APPROVED 2. THE SEED BED SHALL BE FIRM WITH FAIRLY FINE SURFACE,
ROSION CONTROL TREATMENT APPLICABLE TO THE TIME OF YEAR, GRASS SEEDING FOLLOWING SURFACE ROUGHENING. PERFORM ALL OPERATIONS ACCROS
LONE WILL ONLY BE ACCEPTABLE DURING THE MONTHS OF APRIL THROUGH OR PERPENDICULAR TO THE SLOPE.
EPTEMBER. HOWEVER, SEEDING MAY PROCEED WHENEVER IT IS IN THE INTEREST OF 3. SEEDING RECOMMENDATIONS, AS SHOWN BELOW, AND SHOULD BE
HE OWNER/CONTRACTOR, BUT MUST ALSO BE AUGMENTED WITH MULCHING, NETTING APPLIED AT THE RATE OF 120 POUNDS PER ACRE,
R OTHER APPROVED TREATMENT. 4. SEED BEDS PLANTED BETWEEN MAY 1 AND OCTOBER 31 WILL
REQUIRE IRRIGATION AND OTHER MAINTENANCE AS NECESSARY TO
RY SEASON (MAY 1 THRU SEPTEMBER 30) -- THE CLEARING OF LAND, INCLUDING THE FOSTER AND PROTECT THE ROOT STRUCTURE,
EMOVAL OF EXISTING VEGETATION OR OTHER GROUND COVER, MUST BE LIMITED TO 5. SEED BEDS PLANTED BETWEEN NOVEMBER i AND APRIL 30,
NLY AS MUCH LAND AS CAN RECEIVE APPROPRIATE PROTECTIVE COVER OR BE ARMORING OF THE SEED BED WILL BE NECESSARY, (e.g„
THERWISE STABILIZED, AFTER HAVING BEEN CLEARED OR OTHERWISE DISTURBED , GEOTEXTILES, JUTE MAT, CLEAR PLASTIC COVERING).
Y NO LATER THAN SEPTEMBER 30 OF A GIVEN YEAR. UNLESS IMMEDIATE 6. FERTILIZERS ARE TO BE USED ACCORDING TO SUPPLIERS'
TABILIZATION IS SPECIFIED IN THE EROSION AND SEDIMENT CONTROL PLAN, ALL RECOMMENDATIONS. AMOUNTS SHOULD BE MINIMIZED, ESPECIALLY
EAS CLEARED OR OTHERWISE DISTURBED MUST BE APPROPRIATELY STABILIZED ADJACENT TO WATER BODIES AND WETLANDS.
HROUGH THE USE OF MULCHING, NETTING, PLASTIC SHEETING, EROSION BLANKETS,
REE DRAINING MATERIAL, ETC., BY SEPTEMBER 30 OR SOONER PER THE APPROVED USE THE FOLLOWING RECOMMENDED SEED MIXTURE FOR EROSION
LAN OF ACTION. UNLESS OTHERWISE APPROVED BY THE COUNTY, SEEDING, CONTROL, OR A COUNTY APPROVED ALTERNATE SEED MIXTURE.
ERTILIZING AND MULCHING OF CLEARED OR OTHERWISE DISTURBED AREAS SHALL BE
ERFORMED DURING THE FOLLOWING PERIODS MARCH I TO MAY 15, AND AUGUST 15 TO PROPORTIONS PURITY GERMINATIO
CTOBER 1. SEEDING AFTER OCTOBER 1 WILL BE DONE WHEN PHYSICAL COMPLETION NAME BY WEIGHT(%) (%) (%)
F THE PROJECT IS IMMINENT AND THE ENVIROMENTAL CONDITIONS ARE CONDUCIVE
❑ SATISFACTORY GROWTH. IN THE EVENT THAT PERANENT STABILIZATION IS NOT REDTOP (AGROSTIS ALBA) 10 92 90
OSSIBLE, AN ALTERNATIVE METHOD OF GROUND COVER, SUCH AS MULCHING, NETTING, ANNUAL RYE (LOLIUM MULTIFLORUM) 40 98 90
LASTIC SHEETING, EROSION BLANKETS, ETC., MUST BE INSTALLED BY NO LATER THAN CHEWING FESUE 40 97 80
EPTEMBER 30. (FESTUCA RUBRA COMMUTATA)
(JAMESTOWN, BANNER, SHADOW, KOKET)
N THE EVENT THAT CONSTRUCTION ACTIVITIES OR OTHER SITE DEVELOPMENT WHITE DUTCH CLOVER 10 96 90
NWAST
TIVITIES ARE DISCONTINUED FOR AT LEAST 4 CONSECUTIVE DAYS, THE (TRIFOLIUM REPENS)
NER/CONTRACTOR SHALL BE RESPONSIBLE FOR THE INSPECTION OF ALL EROSION
D SEDIMENT CONTROL FACILITIES IMMEDIATELY AFTER STORM EVENTS, AND AT MULCHING
ONCE EVERY WEEK. THE OWNER/ CONTRACTOR SHALL BE RESPONSIBLE FOR
HE MAINTENANCE AND REPAIR OF ALL EROSION AN SEDIMENT CONTROL FACILITIES. 1. MATERIALS USED FOR MULCHING ARE RECOMMENDED TO BE WOOD
FIBER CELLULOSE, AND SHOULD BE APPLIED AT A RATE OF 10DO
ET SEASON (OCTOBER 1 THRU APRIL 30) -- ON SITES WHERE UNINTERUPTED POUNDS PER ACRE.
ONSTRUCTION ACTIVITY IS IN PROGRESS, THE CLEARING OF LAND, INCLUDING THE 2. MULCH SHOULD BE APPLIED IN ALL AREAS WITH EXPOSED SLOPES
EMOVAL OF EXISTING VEGETATION AND OTHER GROUND COVER, SHALL BE LIMITED GREATER THAN 2:1 (HORIZONTAL:VERTICAL).
0 AS MUCH LAND AREA AS CAN BE COVERED OR STABILIZED WITHIN 24 HOURS IN 3. MULCHING SHOULD BE USED IMMEDIATELY AFTER SEEDING OR IN
HE EVENT A MAJOR STORM IS PREDICTED AND/ OR EROSION AND SEDIMENT AREAS WHICH CANNOT BE SEEDED BECAUSE OF THE SEASON. ALL
TRANSPORT OFF-SITE IS OBSERVED. AREAS REQUIRING MULCH SHALL BE COVERED BY NOVEMBER 1.
LL CLEARED OR DISTURBED AREAS SHALL RECEIVE APPROPRIATE PROTECTIVE
OVER OR BE OTHERWISE STABILIZED, SUCH AS MULCHING, NETTING, PLASTIC
HEETING, EROSION BLANKETS, FREE DRAINING MATERIAL, ETC., WITHIN 5 DAYS AFTER
AVING BEEN CLEARED OR OTHERWISE DISTURBED IF NOT BEING ACTIVELY WORKED.
ILT FENCING, SEDIMENT TRAPS, SEDIMENT PONDS, ETC., WILL NOT BE VIEWED AS
DEQUATE COVER IN AND OF THEMSELVES, IN THE EVENT THAT ANY LAND AREA NOT
ING ACTIVELY WORKED REMAINS UNPROTECTED OR HAS NOT BEEN APPROPRIATELY
TABILIZED 5 DAYS AFTER HAVING BEEN CLEARED, ALL CONSTRUCTION ACTIVITY ON
HE SITE, EXCEPT FOR APPROVED EROSION AND SEDIMENT CONTROL ACTIVITY, SHALL
MMEDIATELY CEASE UNTIL SUCH A TIME AS AFOREMENTIONED LAND AREA HAS BEEN
PPROPRIATELY PROTECTED OR STABILIZED.
ILT FENCE
PROJECT/ OWNER/ LOCATION:
GEOTEXTILE FILTER FABRIC TYPE SHALL BE PER SPECIFIED IN THE 'STORMWATER MANAGEMENT MANUAL SINGLE FAMILY RESIDENCE
OR THE PUGET SOUND BASIN,' OR APPLICABLE COUNTY STANDARDS
. GEOTEXTILE FILTER FABRIC SHALL BE PURCHASED IN A CONTINUOUS ROLL CUT TO THE LENGTH OF GE❑TECHNICAL REPORT
ACH BARRIER TO AVOID USE OF JOINTS. IF JOINTS ARE NECESSARY, FILTER FABRIC SHALL BE SPLICED BRUCE LARSON
OGETHER ONLY AT A SUPPORT POST WITH A MINIMUM 6-INCH OVERLAP AND SECURELY FASTENED AT OTH ENDS TO THE POST. RESULTING PARCEL 6 OF BLA 10-10
0
0006
. STANDARD FILTER FABRIC SHALL BE FASTENED USING 1' STAPLES OR TIE WIRES (HOG RINGS) 2 4 IN MASON COUNTY V PARCEL 232236 75 0006TON
PACING.
. POSTS SHALL BE SPACED AND PLACED AT DEPTHS INDICATED IN THE DETAILS ON THIS SHEET, AND ENGINEER:
RIVEN SECURELY INTO THE GROUND, ENVIROTECH ENGINEERING
. WIRE MESH SHALL BE 2'X2'X14 GAUGE OR EQUIVALENT. THE WIRE MESH MAY BE ELIMINATED IF 74 NE HURD ROAD
XTRA-STRENGTH FILTER FABRIC (MONOFILAMENT), AND CLOSER POST SPACING IS USED. BELFAIR, WASHINGTON 98528
. A TRENCH SHALL BE EXCAVATED ACCORDING TO THE DETAILS ON THIS SHEET ALONG THE LINE OF THE 360-275-9374
OSTS AND UPSLOPE FROM THE SILT FENCE.
SILT FENCES SHALL BE LOCATED DOWNSLOPE FROM THE CLEARING LIMITS OF THE PROJECT, ER❑SI❑N CONTROL
APPENDIX F
DRAINAGE DETAILS
HOUSE
,----ROOF DRAIN
SOLID
LID GROUND
SURFACE
BACKFILL 4' DIA. MIN
PERFORATED PVC
PIPE
"DIA.
ENCOMPASS + •.';-
...
2% MIN DRAINROCK WITH 'i`:� -:;•�.> _ .�,ti:.
FILTER FABRI >:i=
1'
NE MESH
SCREEN 4' DIA. MIN---/ 3/4'
CATCH BASIN SOLID PVC
(YARD DRAIN) WASHED DRAIN
ROCK
1' MIN
10 FT MIN
TRENCH BOTTOM
TO BE I FT MIN.
ABOVE SEASONAL
HIGH A-
GROUNDWATER I 2' MIN �I
ROOF DRAINAGE DETAILS INFILTRATION
N.T.S. TRENCH
ASTM C33 SAND GE❑TEXTILE WRAPPED
❑R DRAIN ROCK AR❑UND DRAIN ROCK
BLACK PLASTIC
LAWN EDGING
6• 1 112' WASHED
a
DRAIN ROCK
PROPOSED
? FOUNDATION
12' MIN
9'
PROJECT/ OWNER/ LOCATION,
SINGLE FAMILY RESIDENT
a.
4—INCH PVC PERFORATED PIPE (CLASS 200) GE❑TECHNICAL REPORT
20' BRUCE LARSON
RESULTING PARCEL 6 OF BLA 10-10
PARCEL 232236 75 00060
MASON COUNTY WASHINGTON
ENGINEER,
F❑❑TING PERIMETER DRAIN DETAILS ENVIROTECH ENGINEERING
N.T.S. 74 NE HURD ROAD
BELFAIR, WASHINGTON 98528
360-275-9374
DRAINAGE DETAILS