HomeMy WebLinkAboutGEO2015-00001 for BLD2014-01102 - BLD Engineering / Geo-tech Reports - 12/10/2013 Zb ,d
PLANNING
Geotechnical Report
for
Single Family Residential Property
361 E Great Bend Drive
Union, WA 98592
Parcel No. 32232-75-90021
Mason County, Washington
December 10, 2013
Project# 13112
Prepared For: CLYDE s
Christine Callison GAP wAsy, '9,
15824 Wildaire Drive
Yelm, WA 98597
k 43045 tc�
Prepared By: OAFS IOISTERE
S��NALti�
Envirotech Engineering
PO Box 984
Belfair, Washington 98528
Phone: 360-275-9374
Fax: 360-275-4789
f0az County Departrt-ent of Community DeveiopmenF
�u�;,`rr�[«i vil 6hiiSi or a Geoi:ecnnicai Repor
instruciicns:
This check!isi must be submitted with a Geotechnicai Report and completed_ signed, and the
licensed professionals)!mho prepared the Geoiechnical Report for review by Mason County pu=suanl to
c ,.raSSn vv`i;tt'y: asu's.i....::Da�L-oiti,c. __ a;i =eEii to e`1e aE)t ci3}1itcaie, iiie report SiiOi.iid explain
life basis for the concif ision- Ii �/
ApplicanUOt,--1ner / �1 94(h kl C_rld(56r Parcel# 3^/i L3 L ' 7 5 --300 7- 1
(1) (a)A discussion of general geologic conditions in the vicinity of the proposed developrlfent:
Located on page(s)
(b) ii discuss-On vT specivc s_.. y res
Located on pape(s)- a
(c) A discussion of ground ivater conditions
Locuied en page(s)
(d) A discussion of the upslope geo,rnorphology
Lucaieo on page(s)
dis-cussicn of the!ec iron of upland v.aternodies and wetlands
Located on page(s)
r iScvSSit:rt �i .s.0"Y or ianositoe activity in the activity in the'vicinity, as available in the
referenced reaps and records
{2} A site plan which ic! identifies the irrcNN��1a13i L velopm�in and geologic:eatures-
Locatsd on Maps)_lL l a �
(3) Locations and logs of exploratory ho or Probes.
�SSaicii Oil ft'2 ;.$) S cth �jOr I? L
(4) The area of the proposed development, the boundaries of the hazard, and associated buffers and
setbacks shall be de!jne2ted(top, both sides, and toe)on a geologic map of the site.
(5) A:inirnum of One cross sector:at a scale whiff adequately depicts the subsurface profile, and
i fhich inrornflraies the details-of p/roposed grade changes.
�".ItiaCGtF or, tViG�l cx i 1�
(6) and of. slope to31lIt�- iaVSsS 3erO TEd to'rn arc! rri :n_': -:
-
conditions-Analysis should examine worst easa fa t we -The army is should include the
is;cc p`s' od of Gt as-The:ninftnLui static safeili facior is 1.5, the miniri1(_s!i.
se:Srnd_safeiv=actor is M- and the quasi-si;-;ffc analysis ci ef" eeats should be a value of 0_115
Located or, page(s) 13, cl W. C-,-
(7). (a) Ann:opriate restrictions on plac-eiment of drainage features
Located on pages) ZO
lid. t\^ atrial SC 3fS cP,Placement flr s er C drafn^!ells
Located on page(s)
restrictions on piacernent of compacted fills and footings
Located on pages; 17. /Y
Page I of 2 Form Effective June 2008
Disciair—ner= i.�ason Couniv does not certiiv fhe Rr,aiitj�of the work done it it:is
(d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other
siopes on the properly.
Located on p2ge(s) �fl
(e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of
oii:er siopes on the property.
Located on page(s) L�
(8} i�acur;mendauons for the preparation or, a deiaiied clearing and grading plait �v:+ici,SlUeciFIGaily
identifies vegetation to be removed, a schedule for vegetation removal and replanting, and the
method of vegetation removal.
Located on page(s) Z10
(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
siope 1-1 om erosion, landslides and harmful construction methods.
Located on page(s) 13
(-i0) An anaiysis of both on-site and off-site impacts of the proposed development.
Located on page(s) !6
(i i) Specifications of final development conditions such as, vegetative management, drainage,
erosion control,and buffer widths_
Located on page(s) 9 t1 Z
(9 2) Recommendations for the preparation of structural mitigation or details of other proposed
mitigation.
Located on page(s) c,
(!3) is site crap drawn to scale sbowing the property-bQuntiaries,scale,north arrow, and the location
and nature of existing and
'pro
(�osed development on the site.
6..iRrl.:_" O'i i Wap(s j 5', r a n
c, �Ygtt?n hereby cesd y tinder penalty of
pequry ihat i argil a dAi engineer licensed. &, to of VvQshmagior,w- spe=.ciaiized knowiedge of
geatechn YgeoiG se;ni a"igifi +iiig Or a 960109 Or c,igbseca"ing gwlogi:t ficer,si_U a,ais�r�ec Of
S ==ma`s z"; @ e1�',.'a f f"�L(�f t.ai 9--::-
rapport, dated Oec, 1? cAi 3 , and entitled
30 p (Jl �VGt 1� g�,�/,,�,I✓��L_q A D A miaeis aii i17e ii'e'.;i3,i�ire-mienis fib 3?e esasor'
County Resource Ordinance.Landslide Fam-6 Se�e.n. is E;J::'1j21. a and tMe,';.hat die assessmeniit
demonstrates conclusively that flha sst s posed by the landslide hazard can bz€nidWed though the
included gamy-M-anicai L WKgji,•GJ=!2'_L�G�d1:C��'�LTy Qi+d iataii us ara,mi^i s i c rrtanret as
r.tyl3Z a
43045 4/,
Page 2 of 2 Form Effective June 2008
Di of er- N42s C t dce t certify,Ih-- .I
s afire . .^:� our.., s no .. duality of the wo, ;done in this ;� ctres�ric-1 ^;•,=j.
TABLE OF CONTENTS
1.0 INTRODUCTION..................................................................................................................................2
1.1 PROJECT INFORMATION.....................................................................................................................2
1.2 PURPOSE OF INVESTIGATION AND SCOPE OF WORK.........................................................................3
2.0 SURFACE CONDITIONS....................................................................................................................4
2.1 GENERAL OBSERVATIONS..................................................................................................................4
2.2 TOPOGRAPHY......................................................................................................................................4
ZZIUpslope Geomorphology.............................................................................................................4
2.3 SURFACE DRAINAGE...........................................................................................................................4
Z3.1 Upslope Water Bodies.................................................................................................................4
2.4 SLOPE AND EROSION OBSERVATIONS................................................................................................5
3.0 SUBSURFACE INVESTIGATION......................................................................................................6
3.1 FIELD METHODS,SAMPLING AND FIELD TESTING............................................................................6
3.2 GENERAL GEOLOGIC CONDITIONS....................................................................................................6
3.3 SPECIFIC SUBSURFACE CONDITIONS..................................................................................................8
3.3.1 Groundwater...............................................................................................................................9
4.0 ENGINEERING ANALYSES AND CONCLUSIONS.....................................................................10
4.1 SLOPE STABH ITV..............................................................................................................................10
4.1.1 Slope Stability Analysis.............................................................................................................13
4.2 EROSION............................................................................................................................................13
4.3 SEISMIC CONSIDERATIONS AND LIQUEFACTION.............................................................................14
4.3.1 Liquefaction..............................................................................................................................15
4.4 LANDSLIDE,EROSION AND SEISMIC HAZARDS CONCLUSIONS.......................................................16
4.5 LATERAL EARTH PRESSURES...........................................................................................................16
4.6 ON-SITE AND OFF-SITE IMPACTS.....................................................................................................16
5.0 ENGINEERING RECOMMENDATIONS.......................................................................................17
5.1 BUILDING FOUNDATION RECOMMENDATIONS................................................................................17
5.1.1 Bearing Capacity.......................................................................................................................17
S1.2 Settlement..................................................................................................................................18
5.1.3 Concrete Slabs-on-Grade..........................................................................................................18
5.2 EARTHWORK CONSTRUCTION RECOMMENDATIONS......................................................................18
5.2.1 Excavation..................................................................................................................................18
5.Z2 Placement and Compaction of Native Soils and Engineered FiU...........................................19
5.Z3 Retaining WaQ Backfdl............................................................................................................19
5.2.4 Wet Weather Considerations....................................................................................................20
5.3 BUILDING AND FOOTING SETBACKS.................................................................................................20
5.4 SURFACE AND SUBSURFACE DRAINAGE...........................................................................................20
5.5 VEGETATION BUFFER AND CONSIDERATIONS.................................................................................20
5.6 TEMPORARY AND PERMANENT EROSION CONTROL.......................................................................21
5.7 SEPTIC DRAINFIELDS........................................................................................................................21
5.8 STRUCTURAL MITIGATION...............................................................................................................21
6.0 CLOSURE..........................................................................................................................................-22
Appendix A-Site Plan
Appendix B-Soil Information(Soil Profile;Soil Logs;Well Reports)
Appendix C-Slope Stability Input&Output
Appendix D-Erosion Control
1.0 INTRODUCTION
Envirotech Engineering (Envirotech) has completed a geotechnical investigation for a planned
single family residential replacement located at 361 E Great Bend Drive, identified as parcel
number 32232-75-90021, Union, Mason County, Washington, Section 31, Township 22 North,
Range 3 West, Willamette Meridian. 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 proponent of the property,
Christine Callison,in support of the proposed development as detailed below.
An initial geotechnical evaluation of the Project was conducted by Envirotech on November 15s',
2013. 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 during the geotechnical investigation. Other Project information was obtained by
Envirotech.The property consists of an undisturbed wooded area, cleared area and septic system.
The proposed development is expected to consist of a new single family residence.Approximate
building footprint and other proposed features with relation to existing site conditions are
illustrated on the Site Map provided in Appendix A of this report.
1.2 Purpose of Investigation and Scope of Work
The purpose of this geotechnical investigation is to assess geological hazards, and evaluate the
Project in order to provide geotechnical recommendations that should be implemented during
development. The investigation included characterizing the general Project surface and
subsurface conditions, and evaluating the suitability of the soils to support the planned site
activities.
In order to fulfill the purpose of investigation, the geotechnical program completed for the
proposed improvements of the Project include:
Envirotech Engineering Callison Geotechnical Report
PO Box 984 page 2 361 E Great Bend Drive
Belfair,Washington 98528 Parcel 32232-75-90021
Ph. 360-275-9374 Union,Mason County,Washington
• Fax: 360-275-4789 December loth,2013
r
• 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 Callison Geotechnical Report
PO Box 984 page 3 361 E Great Bend Drive
Belfair,Washington 98528 Parcel 32232-75-90021
Ph. 360-275-9374 Union,Mason County,Washington
• Fax:360-2754789 December loth,2013
r
2.0 SURFACE CONDITIONS
Information pertaining to the existing surface conditions for the Project was gathered on
November 15'', 2013 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 East Great Bend Drive, and State Route 106 is about 750 feet to
the west. The Project currently consists of partially cleared land and the rest is native vegetation.
Beyond the property, residential development exists. Hood Canal is located over 750 feet to the
west of the property line. Vegetation on and near the property consists primarily of alders, and
other trees and shrubbery common to this area of the Pacific Northwest. An aerial photo of the
Project and immediate vicinity is provided on the following page.
2.2 Topography
The topographic information provided in this section was extrapolated from a public lidar source,
and incorporated observations and field measurements. Where necessary, slope verification
included measuring slope lengths and inclinations with a cloth tape and inclinometer. See the Site
Plan in Appendix A in this report for an illustration of general topography with respect to the
planned development.
Critical descending slopes,with grades exceeding 40%are located on the property.The maximum
critical slope is about 43%with a total critical vertical relief of approximately 20 feet.
2.2.1 Upslope Geomorphology
The upland area of the property and from the property is situated on a hillside and ridge
of glacial origin.
2.3 Surface Drainage
Stormwater runoff originating upslope from the anticipated development appears to primarily
sheet flow, and is expected to be moderate. Runoff originating upslope of the property is mostly
diverted away from the property by upslope development and accommodating topography.
Excessive scour, erosion or other indications of past drainage problems were not observed within
the existing 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 Callison Geotechnical Report
PO Box 984 page 4 361 E Great Bend Drive
Belfair,Washington 98528 Parcel 32232-75-90021
Ph. 360-275-9374 Union,Mason County,Washington
Fax: 360-2754789 December loth,2013
2A Slope and Erosion Observations
The slope grades near the Project signal a potential landslide or erosion hazard area. Some indica-
tors that may suggest past slope movements include:
• Outwash of sediments near the bottom of the slope,
• Fissures, tension cracks, hummocky ground or stepped land masses on the face or top of
the slope,and parallel to the slope,
• Fine,saturated subsurface soils,
• Old landslide debris,
• Significant bowing or leaning trees,or,
• Slope sloughing or calving.
These slope instability indicators or other significant mass wasting on the property or within the
general vicinity of the Project were not observed or discovered during research. Indications of
past landslides, current unstable slopes, deep-seated slope problems, or surficial slope failures
were not observed during the site visit.
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Aerial Photo from Mason County Website
Envirotech Engineering Callison Geotechnical Report
PO Box 984 page 5 361 E Great Bend Drive
Belfair,Washington 98528 Parcel 32232-75-90021
Ph. 360-275-9374 Union,Mason County,Washington
Fax:360-275-4789 December loth,2013
r
3.0 SUBSURFACE INVESTIGATION
Information on subsurface conditions pertaining to the Project was primarily gathered on
November 15'h, 2013. Specific information on field methods, sampling, field testing, general
geologic conditions, specific subsurface conditions, and results from soil testing are presented in
this section of the report.Appendix B of this report includes pertinent information on subsurface
conditions for the Project,such as subsoil cross-section(s),test pit log(s),and water well report(s).
Water well reports were utilized to estimate ground water levels, and if sufficient, were used in
identifying subsoil types. Additional well reports than what is provided in this report may be
available from Envirotech upon request.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 onsite.
Information on subsurface conditions also included reviewing geological maps representing the
general vicinity of the project, and water well reports originating from nearby properties.
Envirotech measured the relative density of the near-surface in-situ soils by gauging the
resistance of hand tools.
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 uncomfortably overlie the
Crescent Formation." as revealed in the Geologic Map. Initial sedimentary rocks were formed
from shales, sandstones and coal deposits from rivers. During the Quaternary period, the Puget
Lowland was covered by numerous ice sheets, with the most recent being the Fraser glacier with
a peak of approximately 14,000 years ago. Upon the glacial retreat,the landscape was formed by
glacial erosion glacial drift deposits.
The"Geologic Map of the Skokomish Valley and Union 7.5-minute Quadrangles,Mason County,
Washington' by Michael Polenz, Jessica L. Czajkowski, Gabriel Legorreta Paulin, Trevor A.
Conteras, Brendon A. Miller, Maria E. Martin, Timothy J. Walsh, Robert L. Logan, Robert J.
Carson, Chris N. Johnson, Rian H. Skov, Shannon A. Mahan, and Cody R. Cohan, June 2010,
provides the following caption(s)for the project area:
Qga Vashon advance outwash—Pebbles,cobbles,sand,and beds and lenses of silt and clay;gray to tan;clasts typi-
cally well rounded and well sorted;clean(<5%silt or clay in matrix),except in less-sorted and more angular ice-
proximal deposits;generally compact(see fig.4 of Polenz and others,2009),but commonly cohesionless;very thinly
to very thickly bedded;contains planarand graded beds,cut-and-fill structures,trough and ripple crossbeds,and fore-
sets;thickness typically between 100 and 300 k with the unit top elevation rising gently across the map area from
—200 ft in the southeast to--6W ft in the northwest,generally coinciding roughly with the surface elevation suggested
for the"great Lowland fill"of Booth(1994);deposited as proglacial fluvial and deltaic sediment during Vashon glacial
advance and typically overlain by unit Qgt along a sharp,unconformable contact.Exposures are generally gravel domi-
nated,but some are insufficient to confirm gravel dominance or are more evenly divided between gravel,sand,and
(rarer)fines.Such exceptions were common along the slopes above the North Fork Skokomish River,within about 1.5
mi south of the town of Union,within about 3 mi of the southeastern comer of the Union quadrangle,and on the
Envirotech Engineering Callison Geotechnical Report
PO Box 984 page 6 361 E Great Bend Drive
Belfair,Washington 98528 Parcel 32232-75-90021
Ph. 360-275-9374 Union,Mason County,Washington
Fax: 360-275-4789 December 10th,2013
• Tahuya peninsula.Sand dominates the southern end of one long and skinny polygon along the northeastern channel
margin of a recessional outwash channel near the southwest comer of the Skokomish Valley quadrangle.Widespread
debris slides and debris flows associated with the Great Coastal Gale of December 1-3,2007,and other significant
storms contained ample gravel from unit Qga,thus confirming that it is prone to rapid,hazardous landslides.Springs
are common at the apparent base of the highly permeable unit,indicating that the well-sorted,nearly matrix-free unit is
an important aquifer.If correct,our suspicion that the fluted upland surface above is a`leaky"aquitard suggests that
this aquifer may be sensitive to contamination(see also unit Qgt;Polenz and others,2010,suggest a way to test this
suspicion).Unit Qga was generally identified based on stratigraphic position beneath Vashon till,the presence of
northem-source clasts or matrix,and paucity of weathering.It is otherwise undated and may locally include pre-Vashon
northern outwash.A boundary mismatch between the Union and Mason Lake quadrangles near Hood Canal resulted
where Derkey and others(2009)mapped unit Qls.We acknowledged the instability and mapped mass wasting deposits
downslope,but mapped the upper slope,where ridges expose seemingly undisturbed thick gravel,as unit Qga.
However,the gravel may have been deposited as a kame next to stagnant ice.A discrepancy also exists between the
Union quadrangle and the Shelton quadrangle(Schasse and others,2003),where unit Qgo was mapped in the valley
walls of Johns Creek.Our identification of unit Qga was based in part on recent gravel pit exposures that did
not exist when the Shelton quadrangle was mapped.
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33 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 Callison Geotechnical Report
PO Box 984 page 7 361 E Great Bend Drive
Belfair, Washington 98528 Parcel 32232-75-90021
Ph. 360-275-9374 Union, Mason County,Washington
Fax: 360-275-4789 December 10th,2013
The Project is currently composed of native soils without indications of borrowed fill. Within test
pit locations, soils within the upper 3 feet of natural ground were observed to be moist, brown
moderately dense silty sand with gravel (SM). Sand is well-graded with medium plasticity index.
Based on nearby well reports, site geology and knowledge of the general area, soils below the
upper 3 feet layer to a depth of 50 feet below the ground surface are expected to be very dense
1 gravel, sand silt and/or clay.
conglomerate of gra o y
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 lowland site soils are described as Alderwood
Gravelly Sandy Loam,Ad,with 30%-45%slopes.The soil designations are depicted in the aerial
photograph below,and descriptions are provided in Appendix B of this report.
Project
I
�y}
o03 ft
Soil Survey From USDA Natural Resources Conservation Service
Envirotech Engineering Callison Geotechnical Report
PO Box 984 page 8 361 E Great Bend Drive
Belfair,Washington 98528 Parcel 32232-75-90021
Ph. 360-275-9374 Union,Mason County,Washington
• Fax:360-275-4789 December loth,2013
Soil Map Unit Legend
Legend' Map Unit
Mason County, Washington (WA645)
Map Map Unit Narne Acres Percent
Unit in of AOI
Symbol AOI
Aa Alderwood gravelly loam, 5 20.2 27.6%
to 15 percent slopes
Ac Alderwood gravelly sandy 25.2 34.4%
loam, 15 to 30 percent
slopes
Ad Alderwood gravelly sandy 27.9 38.1%
loam, 30 to 45 percent
slopes
Totals for Area of Interest 73.3 100.0%
3.3.1 Groundwater
From the water well report(s)and knowledge of the general area, permanent groundwater
is at least 60 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.
Envirotech Engineering Callison Geotechnical Report
PO Box 984 page 9 361 E Great Bend Drive
Belfair,Washington 98528 Parcel 32232-75-90021
Ph. 360-275-9374 Union, Mason County,Washington
Fax: 360-275-4789 December 1 Oth,2013
4.0 ENGINEERING ANALYSES AND CONCLUSIONS
The following sections present engineering analyses and conclusions with relation to the existing
conditions and proposed improvements of the Project. This section includes slope stability,
erosion, seismic considerations, lateral earth pressures, and impacts to both on-site and off-site
properties.
4.1 Slope Stability
Landslides are natural geologic processes, and structures near slopes possess an inherent risk of
adverse settlement, sliding or structural damage due to these processes. Geotechnical engineering
cannot eliminate these risks for any site with sloping grades because gravity is constantly
inducing strain on the sloping soil mass. Excessive wet weather and/ or earthquakes will
exacerbate these strains. Geotechnical engineering considers excessive wet weather and `design'
earthquakes in order to provide an acceptable factor of safety for developing on or near sloping
terrain with relation to current engineering protocol. These factors of safeties are based on
engineering standards such as defming engineering properties of the soil, topography, water
conditions,seismic acceleration and surcharges.
Surface sloughing or other types of surficial slope movements usually do not affect the deep-
seated structural capability of the slope. However, excessive and/or repeated surficial slope
movements, if not repaired, may represent a threat to the structural integrity of the slope. If this
situation does arise, the slope shall be inspected by a geotechnical engineer. Subsequently,
maintenance may be required in order to prevent the possibility of further surficial or deep seated
slope movements that may be damaging to life and property.
According to the Coastal Zone Atlas of Mason County,Washington,the Project is within and near
terrain labeled `Stable' regarding potential landslide activity. A Stability Map from the Coastal
Zone Atlas for the general area of this Project is provided below:
Envirotech Engineering Callison Geotechnical Report
PO Box 984 page 10 361 E Great Bend Drive
Belfair,Washington 98528 Parcel 32232-75-90021
Ph. 360-275-9374 Union,Mason County,Washington
Fax:360-2754789 December 10th,2013
Scale 1.24,IMN1
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Project
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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 high slope instability with relation to slopes. This delineation is
primarily dependent upon slopes and convergence. Secondly, lithology and precipitation are
modeled within this delineation. In summary, this designation is based on mapping without field
observations or knowledge of the specific site geology or soils.A Resource Map from the DNR
Forest Practices Application Review System is provided below:
Envirotech Engineering Callison Geotechnical Report
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Resource Map - T 22 0 - R 3 0 - W - S 31 Get Map Refresh Site
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Resource Map from Washington State Department of Natural Resources Website
SOILS—On Resource Nlap onh•
Hydric Soils
Highly Unstable
Highly Erodible
Highly Unstable&
Hiahh•Erodible
No Data or Gravel
Pits
SLOPE—On Resource\tap only
Medium Slope
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_High Slope Instability
Envirotech Engineering Callison Geotechnical Report
• PO Box 984 page 12 361 E Great Bend Drive
Belfair,Washington 98528 Parcel 32232-75-90021
Ph. 360-275-9374 Union,Mason County,Washington
Fax: 360-275-4789 December 10th,2013
i
4.1.1 Slope Stability Analysis
Based on site geology, a non-circular slope stability analysis should be performed. However, the
Simplified Bishop Method (circular analysis), as presented herein, was utilized. Although the
method of circles does not fit the site conditions, Envirotech certifies that our analysis is more
conservative for these project conditions than other conforming slope stability models. For this
Project and level of geotechnical investigation,our conclusions or recommendations would not be
changed by this variation in analysis. Where applicable, our slope stability analysis utilizes the
subsurface angle of repose.
The Simplified Bishop Method, utilizing `STABLE' software, was used to analyze the static
stability of the site slopes. Seismic conditions were estimated utilizing worst case scenario values
from the static analysis, a quasi-static analysis coefficient of at least 0.15, and applying the
applicable values to STABLE software. Various radii's and center points of the circle were
automatically selected, and produced factor of safeties in a graphical and tabular format. Worst
case scenario values were used in the slope stability analysis in regards to topography, surcharges,
water content, internal friction and cohesion of the site soils. STABLE software has been
repeatedly checked with manual calculations, and consistently proved to be a very conservative
program. The following soil properties were used in the analysis, and are based on observed
conditions,known geology, and/or published parameters:
Upper 5 feet soil depth
Soil unit weight: 132 pcf
Angle of internal friction: 30 degrees
Cohesion: 50 psf
Soils below 5 feet in depth
Soil unit weight: 138 pcf
Angle of internal friction: 38 degrees
Cohesion: 200 psf
Based on the slope stability analysis, minimum factors of safety were determined to be
1.7 relative to static slope failures, and 1.1 with relation to seismic conditions. See the
slope stability information in Appendix C for a depiction of input parameters and exam-
ple of outputs.
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 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).
Envirotech Engineering Callison Geotechnical Report
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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 storm-
water runoff or tracking off-site with construction equipment.
The Temporary and Permanent Erosion Control Section (Section 5.6) of this report contain spe-
cific erosion control options recommended for this Project. Additional erosion control measures
than what is initially established may need to be employed if excessive erosion occurs during
construction, or required by the prevailing agency. Complete erosion control information and
specifications may be found in the latest addition of the "Stonnwater Management Manual for
Western Washington," prepared by the Washington State Department of Ecology Water Quality
Program.
4.3 Seismic Considerations and Liquefaction
There are no known faults beneath this Project. The nearest Class `A' or Class `B' fault to this
property is the Hood Canal Fault Zone, in which is approximately 3 miles to the northwest 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
0.46g to 0.59g.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.
Envirotech Engineering Callison Geotechnical Report
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Ph. 360-275-9374 Union,Mason County,Washington
• Fax:360-2754789 December 10th,2013
PGA. 20. PE in 50y. 1 150m/s. Site Class B.
50`
48°
c
46' .
44-
42'
40° �.
t_
380
36'
1.00
0.77 °
0.59
34° 0.46
0.35 ••�
- 0.27 p
0.21 G
32` 0.16
0.12 A
0.10 km
0.08 9
30 0.06 0100900.
y
43.1 Liquefaction
The potential for liquefaction is believed to be medium to 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.
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4.4 Landslide,Erosion and Seismic Hazards Conclusions
DNR did not indicate previous 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, and
observed surface condition, it is our opinion that the proposed development should occur in
accordance with this geotechnical report.
4.5 Retaining Walls and Lateral Earth Pressures
Lateral earth pressures exerted through the backfill of a retaining wall are dependent upon several
factors including height of retained soil behind the wall, type of soil that is retained, degree of
backfill compaction, slope of backfill, surcharges, hydrostatic pressures, earthquake pressures,
and the direction and distance that the top of the wall moves. Significant retaining structures are
not anticipated for this Project. If retaining walls are later planned for this Project, prescriptive
requirements from the County should be adhered to. For retaining structures with a height ex-
ceeding County prescriptive requirements, additional design parameters must be accounted for in
the retaining wall analysis,and recommendations should only be provided by a qualified engineer
after the type of backfill is acquired, inclination of backfill slope is estimated, and the final wall
height is determined.
4.6 On-Site and Off-Site Impacts
From a geotechnical position, it is Envirotech's opinion that the subject property and adjacent
properties to the proposed development should not be significantly impacted if all
recommendations in this report are followed. This opinion is based on the expected site
development, existing topography, existing nearby development, land cover, and adhering to the
recommendations presented in this report. Future development or land disturbing activities on
neighboring properties or properties beyond adjacent parcels that are upslope and/or downslope
from the subject property could cause problems to the subject property. For this reason, future
development or land disturbance near the subject property should be evaluated by a geotechnical
engineer.
Envirotech Engineering Callison 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 Terzaghi ultimate bearing capacity
equation was utilized for determining foundation width and depth. Foundation parameters
provided herein account for typical structural pressures due to the planned type of development.A
structural analysis is beyond the scope of a geotechnical report,and a structural engineer may be
required to design specific foundations and other structural elements based on the soil
investigation.
Stepped foundations are acceptable, if warranted for this Project.Continuous, isolated, or stepped
foundations shall be horizontally level between the bottom of the foundation and the top of the
bearing strata. The frost penetration depth is not expected to extend beyond 12 inches below the
ground surface for this Project under normal circumstances and anticipated design features.
5.1.1 Bearing Capacity
Existing in-situ soils for this Project indicates that the structure can be established on
shallow, continuous or isolated footings. Foundations shall be established on relatively
undisturbed native soil. Alternatively, foundations may be constructed on selective re-
compacted native soil or compacted engineered fill as described in the Earthwork
Construction Recommendations Section of this report.
For a bearing capacity requirement of no more than 1500 psf, a minimum continuous
footing width of 15 inches shall be placed at a minimum of 18 inches below the existing
ground surface. 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
Envirotech Engineering Callison Geotechnical Report
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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, competent 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 upper organic
laden 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 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,
Envirotech Engineering Callison Geotechnical Report
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compacted, and suitable before placement of additional native soil, engineered fill or
structural concrete.
5.2.2 Placement and Compaction of Native Soils and Engineered Fill
For engineered fill or disturbed native soils that will be utilized as fill material directly
beneath foundations, observation and/ or geotechnical testing is required prior to
foundation construction. The following placement and compaction requirements are
necessary.
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.
F❑❑TING
COMPACTED
NATIVE SOILS
OR ENGINEERED 1
FILL
1
II UNDISTURBED SUBGRADEI
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 an other deleterious matter. Because of
g Y
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
90% of the modified Proctor maximum dry density (ASTM D 1557) and within 3% of
optimum moisture content. Each lift surface should be adequately maintained during
construction in order to achieve acceptable compaction and inter-lift bonding.
Temporary earth cuts and temporary fill slopes exceeding 4 feet in height should be
limited to a slope of 2:1 (horizontal:vertical). Utility trenches or other confined
excavations exceeding 4 feet should conform to OSHA safety regulations. Permanent cut
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and fill slopes shall be limited to a slope of 2:1, unless otherwise approved by an
engineer.
5.2.3 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.
5.3 Building and Footing Setbacks
Provided that assumptions relating to construction occur and recommendations are followed as
presented in this report, the factor of safety for slope stability is sufficient for a 25 feet building
setback from both the tops of natural critical descending slopes and man-made earth cuts.
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.
Roof drain facilities are required for this project. Roof water should be infiltrated at least 15 feet
from foundations, located downslope. In addition water should not be infiltrated within the 25
feet building setbacks from the tops of slopes.
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.
For this project, we believe that a detailed clearing and grading plan is not warranted, and basic
vegetation management practices should be adhered to. Vegetation shall not be removed from the
face of the critical 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
Envirotech Engineering Callison Geotechnical Report
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underbrush and soil shall remain undisturbed as much as possible. Any disturbed soil shall be
graded and re-compacted in order to restore the terrain similar to preexisting conditions and
drainage patterns. See the Site Plan in Appendix A of this report for a depiction of the vegetation
buffer.
5.6 Temporary and Permanent Erosion Control
Erosion control during construction should include minimizing the removal of vegetation to the
least extent possible, and may include stockpiling cleared vegetation, silt fencing, intercepting
swales, berms, straw bales, plastic cover or other standard controls. 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 con-
trol measures are not functioning as needed, additional measures must be implemented immedi-
ately. See Appendix D for sketches and general notes regarding selected erosion control
measures. The Site Map in Appendix A depicts the recommended locations for erosion control
facilities to be installed.
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 equiva-
lent 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 Daannfields
Based on the septic drainfield location with relation to the existing and proposed topography, the
drainfields are not expected to adversely influence critical slopes. This is also based on
compliance with all recommendations in this report.
5.8 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,engi-
neering conclusions,and compliance with all recommendations provided in this report.
Envirotech Engineering Callison Geotechnical Report
PO Box 984 page 21 361 E Great Bend Drive
Belfair,Washington 98528 Parcel 32232-75-90021
Ph. 360-275-9374 Union,Mason County,Washington
• Fax:360-275-4789 December loth,2013
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.
By developing the property and following the recommendations provided in this report, the
property owner(s) shall be required to acknowledge in writing the risks inherent in developing in
a geologic hazard area,to accept the responsibility of any adverse effects which may occur to the
subject property or other properties as a result of the development, and to agree to convey the
knowledge of this risk to persons purchasing the site by filing a notice on the property title.
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,
Envirot En ineer
Michael Staten,P.E.
Geotechnical Engineer
Envirotech Engineering Callison Geotechnical Report
PO Box 984 page 22 361 E Great Bend Drive
Belfair,Washington 98528 Parcel 32232-75-90021
Ph. 360-275-9374 Union,Mason County,Washington
Fax:360-275-4789 December 10th,2013
APPENDIX A
SITE PLAN
SOILS: MEDIUM DENSE SILTY SAND WITH GRAVEL (SM) SCALE- I INCH = 60 FEET
OVERLYING DENSE GLACIAL ❑UTWASN 0 15 30 60
\ � P
PR ER'TY LINE �
230FT± \ APPROXIMATE TOE OF
VEGETATION SH❑UL \
T SLOPE EXCEEDING 40%
BE REMOVED F
\CRIT,I\CAL SLOPE \
UrLESS, ALLOW PER
GE❑TECH'NCA REPORT. \ \�
++ \ APPROXIMATE TOP\ OF \
L \� SLOPE EXC ING 40 .
v `
TEMPORARY EROSION
BUILDING P\ 2�;� CONTROL. SEE REPORT
S ACK FROM TOP
OF C TICAL SLOPE \
\ 1
\ m
PROPOSED REA FOR
EXISITNG'vSEPTIC ROOF DRAINAGE
DRAINFIELD\AREA u'
PROPERTY LINE
PROPERTY LINE
EXISTING EARTH CUT
TPl FOR NEIGHBORS
DEVELOPMENT
�sr POSSIBLE L❑CATION FOR
A� RESIDENTAL STRUCTURE,
SEE REPORT FOR EARTH
0
,',,CUT SETBACKS
0
Li
VEGETATE DENUDED
AREAS PER PERMANENT
EROSION CONTROL PLAN. A DRIVEWAY &
SEE REPORT. z STABILIZED
L CONSTRUCTION
ENTRANCE
NOTES lk PROJECT/ OWNER/ LOCATION-
1. CONTOURS WERE NOT PREPARED BY A LICENSED LAND SURVEYOR. l7 SINGLE FAMILY RESIDENCE
CONTOURS WERE EXTRAPOLATED FROM A PUBLIC LIDAR SOURCE, AND 1., GE❑TECHNICAL REPORT
INCORPORATED FIELD MEASUREMENTS AS EXPLAINED IN THE GEOTECHNICAL
REPORT. CHRISTINE CALLISON
2. BOUNDARIES WERE NOT PREPARED BY A LICENSED SURVEYOR. LOCATIONS 361 EAST GREAT BEND DRIVE
OF SITE FEATURES THAT ARE SHOWN HERE, SUCH AS TOP OF SLOPES, TOE LEGEND PARCEL 32232 75 90021
OF SLOOPES, WATER FEATURES, ETC.., WITH RELATION TO THE PROPERTY MASON COUNTY WASHINGTON
LINES MUST BE VERIFIED BY THE OWNER. RECOMMENDATIONS IN THE TEMPORARY ENGINEER-
GEOTECHNICAL REPORT PROVIDE SETBACKS, BUFFERS, DEPTHS, ETC.. WITH +++EROSION CONTROL ENVIROTECH ENGINEERING
RELATION TO GEOLOGIC FEATURES, NOT PROPERTY LINES. THESE GEOLOGIC PO BOX 984
PROPERTIES.
FEATURES MAY BE LOCATED ON THE SUBJECT PROPERTY OR NEIGHBORING SLOPE INDICATOR BELFAIR, WASHINGTON 98528
-80 EXISTING CONTOUR 360-275-9374
TPIe TEST PIT SITE PLAN
APPENDIX B
SOIL INFORMATION
VERTICAL AND HORIZONTAL SCALE
1 INCH - 40 FEET
0
15�±
MEDIUM DENSE
OVERBURDEN (GM)
..•.nJl:li4..t
GLACIAL ADVANCE OUTWASH
SECTION A-A
PROJECT/ OWNER/ LOCATION,
SINGLE FAMILY RESIDENCE
GE❑TECHNICAL REPORT
C CALLISON
PARCEL 32232 75 90021
MASON COUNTY, WASHINGTON
NOTESi
ENGINEERt
1) MINOR GRADE CHANGES REQUIRED IN ORDER TO ACHIEVE ENVIROTECH ENGINEERING
POSITIVE DRAINAGE PO BOX 984
2) THE SOIL PROFILE IS ACCURATE FOR THE DEPTH OF BELFAIR, WASHINGTON 98528
THE OBSERVED TEST PITS AT THE SPECIFIED LOCATIONS, 360-275-9374
LOWER DEPTHS ARE BASED ON SITE GEOLOGY,
WELL LOG(S), AND/OR EXPERIENCE IN THE GENERAL AREA. SOIL PROFILE
TEST PIT LOG
TEST PIT NUMBER TP-1
PROJECT: Callison Geotechnical Report DATE OF LOG: 11/15/2013
PROJECT NO: 13112 LOGGED BY: MCS
CLIENT: Christine Callison EXCAVATOR: N/A
LOCATION: Parcel 32232 75 90021 DRILL RIG: None
Mason County, Washington ELEVATION: N/A
INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: N/A
SOIL STRATA, STANDARD PENETRATION TEST
DEPTH SAMPLERS USCS DESCRIPTION LL PI CURVE
AND TEST DATA DEPTH N 10 30 50
0
SM Brown, moist, loose to medium dense
SILTY SAND with GRAVEL. Gravel is
primarily well-graded and subangular.
1
Sand is mostlymedium. Low plasticity.P Y
2
3
Density increases with depth
4
Excavation terminated at approximately
4.0 feet
5
6
7
8
9
110
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.
APPENDIX C
SLOPE STABILITY
STABLE Slope Stability Analysis System
New User
Project Callison
Datafile : static Bishop
STABLE Version 9.03.00u
Bishop
TITLE
static
UNITS (Metric/Imperial) = I
GEOMETRY DEFINITION
POINTS
NO. X Y
1 0.000 0.000
2 50.000 -7.000
3 110.000 -32.000
4 160.000 -47.000
5 0.000 -5.000
6 50.000 -12.000
7 110.000 -37.000
8 160.000 -52.000
9 16.000 -2.240
10 22.740 -3.180
11 29.470 -4.130
12 36.210 -5.070
13 42.950 -6.010
14 49.680 -6.960
15 56.420 -9.680
16 63.160 -12.480
17 69.890 -15.290
18 76.630 -18.100
19 83.370 -20.900
20 90.110 -23.710
21 96.840 -26.520
22 103.560 -29.320
23 110.320 -32.090
24 117.050 -34.120
25 123.790 -36.140
26 130.530 -38.160
27 137.260 -40.180
28 144.000 -42.200
LINES
Lo X Hi X SOIL
1 2 1
2 3 1
3 4 1
5 6 2
6 7 2
7 8 2
SOILS
STABLE Slope Stability Analysis System
New User
Project Callison
Datafile : static Bishop
SOIL NAME LINETYPE-PEN COHESION FRICTION UNIT WT.
1 Soil-1 CONTINUOUS-BLACK 50.00 30.0 132.000
2 Soil-2 CONTINUOUS-BLUE 200.00 38.0 138.000
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
128.000
***************
* *
16.000 * * 144.000
***************
0.000
X spacing -- no. of cols (max 10)= 10
Y spacing -- no. of rows (max 20)= 20
Grid 1 Circles through point 9
Grid 2 Circles through point 10
Grid 3 Circles through point 11
Grid 4 Circles through point 12
Grid 5 Circles through point 13
Grid 6 Circles through point 14
Grid 7 Circles through point 15
Grid 8 Circles through point 16
Grid 9 Circles through point 17
Grid 10 Circles through point 18
1 . 00
1 . 10
1 _ 20
1 . 30
1 . 40
1 . 50
1 . 60
1 . 70
1 . 80
.1 _ 90
=2 _ 00
I
1 . 59
P r o j e c t Ca 1 1 i s o n
Dataf'i1e _ static
Analysis _ Bishop
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APPENDIX D
EROSION CONTROL
GE❑TEXTILE FABRIC
WRAP AROUND TRENCH
TO AT LEAST ENTIRE
BOTTOM OF TRENCH
BEFORE PLACING GRAVEL 2'x2'x5' WOOD POST OR
12' DEEP, 8' WIDE TRENCH f EQUIVALENT OR BETTER
FILLED WITH 3/4' TO 1 1/2'
WASHED GRAVEL OR VEGETAT N
ol 2.5 FT
DIRECTI❑N OF — EXISTING
WATER FLOW GROUND SURFACE
12'
2.51 FT
1
8' t-
SILT FENCE - CROSS SECTION
N.T.S.
2'x2' WOOD POST (TYP) GEOTEXTILE FABRIC
OR EQUIVALENT OR BETTER AND WIRE MESH
@ 6 FT MAX. ❑.C.
6FT 0.5 FT
EXISTING /IF I F-1
\\\\\\
GROUND SURFACE
2 T
12' DEEP, 8' WIDE }
TRENCH FILLED WITH 1 FT
3/4' TO 1 1/2' 2.5 FT
WASHED GRAVEL OR VEGE TI
BOTTOM EXTENTS OF
GEOTEXTILE FABRIC SILT FENCE - DETAIL
N.T.S.
PR❑VIDE FULL WIDTH
3/4 IN TO 1
PF INGRESS/EGRESS
1/��IPL20 FT (-
CRUSHED GRAVEL
PLACED AT 6 IN
MINIMUM DEPTH
WELL-DRAINED
S❑ILS
-0.02 IN/MIN FULL LENGTH
R=25 FT MIN
G PROJECT/ OWNER/ LOCATION,
ACCESS ROAD SINGLE FAMILY RESIDENCE
GE❑TECHNICAL REPORT
STABILIZED CONSTRUCTION ENTRANCE CHRISTINE CALLISTON
N.T.S. PARCEL 32223-75-90021
MASON COUNTY, WASHINGTON
ENGINEER:
ENVIROTECH ENGINEERING
PO BOX 984
BELFAIR, WASHINGTON 98528
360-275-9374
ER❑SI❑N CONTROL P, 1
PERMANENT EROSION CONTROL NOTES:
ENERAL NOTES,
SEEDING FOR RAW SLOPES
' I. SHOULD THE TEMPORARY EROSION AND SEDIMENT CONTROL MEASURES SHOWN ON
THESE PLANS PROVE TO BE INADEQUATE DURING CONSTRUCTION, THE CONTRACTOR 1, BEFORE SEEDING, INSTALL NEEDED SURFACE RUNOFF CONTROL
HALL INSTALL ADDITIONAL EROSION AND SEDIMENT CONTROL FACILITIES. MEASURES SUCH AS GRADIENT TERRACES, INTERCEPTOR DIKES,
2. ALL EROSION AND SEDIMENT CONTROL FACILITIES AND DEVICES SHALL BE SWALES, LEVEL SPREADERS AND SEDIMENT BASINS.
INSPECTED DAILY AND IMMEDIATELY MAINTAINED, IF NECESSARY. 2. THE SEED BED SHALL BE FIRM WITH FAIRLY FINE SURFACE,
3. ALL EROSION AND SEDIMENT CONTROL FACILITIES AND DEVICES SHALL BE LEFT IN FOLLOWING SURFACE ROUGHENING. PERFORM ALL ❑PERATIONS ACCROS
LACE UNTIL THE UPSLOPE AREAS HAVE BEEN PERMANENTLY STABILIZED. OR PERPENDICULAR TO THE SLOPE,
3. SEEDING RECOMMENDATIONS, AS SHOWN BELOW, AND SHOULD BE
TEMPORARY EROSION CONTROL NOTES: APPLIED AT THE RATE OF 120 POUNDS PER ACRE.
4, SEED BEDS PLANTED BETWEEN MAY 1 AND ❑CTOBER 31 WILL
❑R ALL AREAS WHICH HAVE BEEN STRIPPED OF VEGETATION OR EXPERIENCED LAND REQUIRE IRRIGATION AND OTHER MAINTENANCE AS NECESSARY TO
ISTURBING ACTIVITIES, AND WHERE NO FURTHER WORK IS ANTICIPATED FOR A FOSTER AND PROTECT THE ROOT STRUCTURE.
ERIOD EXCEEDING THE LISTED CRITERIA BELOW, ALL DISTURBED AREAS MUST BE 5. SEED BEDS PLANTED BETWEEN NOVEMBER 1 AND APRIL 30,
MMEDIATELY STABILIZED WITH MULCHING, GRASS PLANTING OR OTHER APPROVED ARMORING OF THE SEED BED WILL BE NECESSARY, (e.g.,
ROSION CONTROL TREATMENT APPLICABLE TO THE TIME OF YEAR. GRASS SEEDING GEOTEXTILES, JUTE MAT, CLEAR PLASTIC COVERING).
%LONE WILL ONLY BE ACCEPTABLE DURING THE MONTHS OF APRIL THROUGH 6. FERTILIZERS ARE TO BE USED ACCORDING TO SUPPLIERS'
EPTEMBER. HOWEVER, SEEDING MAY PROCEED WHENEVER IT IS IN THE INTEREST OF RECOMMENDATIONS. AMOUNTS SHOULD BE MINIMIZED, ESPECIALLY
HE ❑WNER/CONTRACTOR, BUT MUST ALSO BE AUGMENTED WITH MULCHING, NETTING ADJACENT TO WATER BODIES AND WETLANDS.
R OTHER APPROVED TREATMENT.
USE THE FOLLOWING RECOMMENDED SEED MIXTURE FOR EROSION
RY SEASON (MAY 1 THRU SEPTEMBER 30) -- THE CLEARING OF LAND, INCLUDING THE CONTROL, OR A COUNTY APPROVED ALTERNATE SEED MIXTURE.
EMOVAL OF EXISTING VEGETATION OR OTHER GROUND COVER, MUST BE LIMITED TO
NLY AS MUCH LAND AS CAN RECEIVE APPROPRIATE PROTECTIVE COVER OR BE PROPORTIONS PURITY GERMINATI❑
THERWISE STABILIZED, AFTER HAVING BEEN CLEARED OR ❑THERWISE DISTURBED NAME BY WEIGHT(%) (%) (7)
Y NO LATER THAN SEPTEMBER 30 OF A GIVEN YEAR. UNLESS IMMEDIATE
TABILIZATION IS SPECIFIED IN THE EROSION AND SEDIMENT CONTROL PLAN, ALL REDTOP (AGROSTIS ALBA) 10 92 90
REAS CLEARED OR ❑THERWISE DISTURBED MUST BE APPROPRIATELY STABILIZED ANNUAL RYE (LOLIUM MULTIFLORUM) 40 98 90
HROUGH THE USE OF MULCHING, NETTING, PLASTIC SHEETING, EROSION BLANKETS, CHEWING FESUE 40 97 80
REE DRAINING MATERIAL, ETC., BY SEPTEMBER 30 OR SOONER PER THE APPROVED (FESTUCA RUBRA COMMUTATA)
LAN OF ACTION. UNLESS ❑THERWISE APPROVED BY THE COUNTY, SEEDING, (JAMESTOWN, BANNER, SHADOW, KOKET)
ERTILIZING AND MULCHING OF CLEARED OR ❑THERWISE DISTURBED AREAS SHALL BE WHITE DUTCH CLOVER 10 96 90
ERFORMED DURING THE FOLLOWING PERIODS: MARCH 1 TO MAY 15, AND AUGUST 15 TO (TRIFOLIUM REPENS)
CTOBER 1. SEEDING AFTER ❑CTOBER 1 WILL BE DONE WHEN PHYSICAL COMPLETION
F THE PROJECT IS IMMINENT AND THE ENVIROMENTAL CONDITIONS ARE CONDUCIVE MULCHING
❑ SATISFACTORY GROWTH. IN THE EVENT THAT PERANENT STABILIZATION IS NOT
❑SSIBLE, AN ALTERNATIVE METHOD OF GROUND COVER, SUCH AS MULCHING, NETTING, 1. MATERIALS USED FOR MULCHING ARE RECOMMENDED TO BE WOOD
LASTIC SHEETING, EROSION BLANKETS, ETC., MUST BE INSTALLED BY NO LATER THAN FIBER CELLULOSE, AND SHOULD BE APPLIED AT A RATE OF 1000
EPTEMBER 30. POUNDS PER ACRE.
2. MULCH SHOULD BE APPLIED IN ALL AREAS WITH EXPOSED SLOPES
N THE EVENT THAT CONSTRUCTION ACTIVITIES OR OTHER SITE DEVELOPMENT GREATER THAN 2:1 (HORIZONTAL:VERTICAL).
CTIVITIES ARE DISCONTINUED FOR AT LEAST 4 CONSECUTIVE DAYS, THE 3. MULCHING SHOULD BE USED IMMEDIATELY AFTER SEEDING OR IN
WNER/CONTRACTOR SHALL BE RESPONSIBLE FOR THE INSPECTION OF ALL EROSION AREAS WHICH CANNOT BE SEEDED BECAUSE OF THE SEASON. ALL
ND SEDIMENT CONTROL FACILITIES IMMEDIATELY AFTER STORM EVENTS, AND AT AREAS REQUIRING MULCH SHALL BE COVERED BY NOVEMBER 1.
EAST ONCE EVERY WEEK. THE OWNER/ CONTRACTOR SHALL BE RESPONSIBLE FOR
HE MAINTENANCE AND REPAIR OF ALL EROSION AN SEDIMENT CONTROL FACILITIES. TOPSOILING
ET SEASON (OCTOBER 1 THRU APRIL 30) -- ON SITES WHERE UNINTERUPTED 1. TOPSOIL SHOULD BE USED FOR THIS PROJECT DUE TO HIGHLY
ONSTRUCTION ACTIVITY IS IN PROGRESS, THE CLEARING OF LAND, INCLUDING THE DENSE EXPOSED SOILS.
REMOVAL OF EXISTING VEGETATION AND OTHER GROUND COVER, SHALL BE LIMITED 2. TOPSOIL SHOULD BE PLACED ON SLOPES NOT EXCEEDING 2-1.
TO AS MUCH LAND AREA AS CAN BE COVERED OR STABILIZED WITHIN 24 HOURS IN 3. STRIPPING AND STOCKPILING ON-SITE SOILS SHALL ONLY BE
HE EVENT A MAJOR STORM IS PREDICTED AND/ OR EROSION AND SEDIMENT PERMITTED IF TOPSOIL IS FRIABLE AND LOAMY (LOAM, SANDY LOAM,
TRANSPORT ❑FF-SITE IS OBSERVED. SILT LOAM, SANDY CLAY LOAM, CLAY LOAM).
LL CLEARED OR DISTURBED AREAS SHALL RECEIVE APPROPRIATE PROTECTIVE 4. STRIPPING SHALL BE CONFINED TO THE IMMEDIATE CONSTRUCTION
'OVER ❑R BE ❑THERWISE STABILIZED, SUCH AS MULCHING, NETTING, PLASTIC AREAS. A FOUR TO SIX INCH STRIPPING DEPTH IS COMMON, BUT
HEFTING, EROSION BLANKETS, FREE DRAINING MATERIAL, ETC., WITHIN 5 DAYS AFTER DEPTH MAY VARY DEPENDING ON THE PARTICULAR SOIL. ALL
SURFACE RUNOFF CONTROL STRUCTURES SHALL BE IN PLACE BEFORE
AVING BEEN CLEARED OR ❑THERWISE DISTURBED IF NOT BEING ACTIVELY WORKED.
STRIPPING.
ILT FENCING, SEDIMENT TRAPS, SEDIMENT PONDS, ETC., WILL NOT BE VIEWED AS
DEQUATE COVER IN AND OF THEMSELVES, IN THE EVENT THAT ANY LAND AREA NOT
EING ACTIVELY WORKED REMAINS UNPROTECTED OR HAS NOT BEEN APPROPRIATELY
TABILIZED 5 DAYS AFTER HAVING BEEN CLEARED, ALL CONSTRUCTION ACTIVITY ON
HE SITE, EXCEPT FOR APPROVED EROSION AND SEDIMENT CONTROL ACTIVITY, SHALL
MMEDIATELY CEASE UNTIL SUCH A TIME AS AFOREMENTIONED LAND AREA HAS BEEN
PPROPRIATELY PROTECTED OR STABILIZED.
STOCKPILE MANAGEMENT
1. STOCKPILE SHALL BE STABILIZED (WITH PLASTIC COVERING OR OTHER APPROVED DEVICE) DAILY BETWEEN NOVEMBER 1 AND MARCH
31.
2. IN ANY SEASON, SEDIMENT LEACHING FROM STOCK PILES MUST BE PREVENTED.
3. TOPSOIL SHALL NOT BE PLACED WHILE IN A FROZEN OR MUDDY CONDITION, WHEN THE SUBGRADE IS EXCESSIVELY WET, OR WHEN
CONDITIONS EXIST THAT MAY OTHERWISE BE DETRIMENTAL TO PROPER GRADING OR PROPOSED SODDING OR SEEDING.
4. PREVIOUSLY ESTABLISHED GRADES ON THE AREAS TO BE TOPSOILED SHALL BE MAINTAINED ACCORDING TO THE APPROVED PLANS.
STABILIZED CONSTRUCTION ENTRANCE
1. MATERIAL SHALL BE 4 INCH TO 8 INCH QUARRY SPALLS (4 TO 6 INCH FOR RESIDENTIAL SINGLE FAMILY LOTS) AND MAY BE
TOP-DRESSED WITH 1 INCH TO 3 INCH ROCK. (STATE STANDARD SPECIFICATIONS, SECTION 8-15.)
2. THE ROCK PAD SHALL BE AT LEAST 12 INCHES THICK AND 50 FEET LONG (20 FEET FOR SITES WITH LESS THAN 1 ACRE OF
DISTURBED SOIL). WIDTH SHALL BE FULL WIDTH OF THE VEHICLE INGRESS AND EGRESS AREA. SMALLER PADS MAY BE APPROVED
FOR SINGLE-FAMILY RESIDENTIAL AND SMALL COMMERCIAL SITES.
3. ADDITIONAL ROCK SHALL BE ADDED PERIODICALLY TO MAINTAIN PROPER FUNCTION OF THE PAD.
4. IF THE PAD DOES NOT ADEQUATELY 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
WATER SHALL DRAIN TO A SEDIMENT RETENTION FACILITY OR THROUGH A SILT FENCE.
SILT FENCE
PROJECT/ OWNER/ LOCATION-
1. 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
2. GEOTEXTILE FILTER FABRIC SHALL BE PURCHASED IN A CONTINUOUS ROLL CUT TO THE LENGTH OF GE❑TECHNICAL REPORT
EACH BARRIER TO AVOID USE OF JOINTS. IF JOINTS ARE NECESSARY, FILTER FABRIC SHALL BE SPLICED CHRISTINE CALLISON
TOGETHER ONLY AT A SUPPORT POST WITH A MINIMUM 6-INCH OVERLAP AND SECURELY FASTENED AT PARCEL 322 75 90021
BOTH ENDS TO THE POST. MASON COUNTY, WASHINGTON
3. STANDARD FILTER FABRIC SHALL BE FASTENED USING 1' STAPLES OR TIE WIRES (HOG RINGS) @ 4 IN
PACING.
4. POSTS SHALL BE SPACED AND PLACED AT DEPTHS INDICATED IN THE DETAILS ON THIS SHEET, AND ENGINEER-
DRIVEN SECURELY INT❑ THE GROUN➢, ENVIROTECH ENGINEERING
. WIRE MESH SHALL BE 2'X2'X14 GAUGE OR EQUIVILENT. THE WIRE MESH MAY BE ELIMINATED IF P❑ BOX 984
EXTRA-STRENGTH FILTER FABRIC (MONOFILAMENT), AND CLOSER POST SPACING IS USED. BELFAIR, WASHINGTON 98528
6. A TRENCH SHALL BE EXCAVATED ACCORDING TO THE DETAILS ON THIS SHEET ALONG THE LINE OF THE 360-275-9374
POSTS AND UPSLOPE FROM THE SILT FENCE.
7, SILT FENCES SHALL BE LOCATED DOWNSLOPE FROM THE CLEARING LIMITS OF THE PROJECT, ER❑SI❑N CONTROL P, 2