HomeMy WebLinkAboutGEO2019-00032 - GEO Geological Review - 3/1/2019 BUILDING GebAoqao3
Geological Assessment
RECEIVED
Brunner Single Family Residential Property APR 1 12019
XXX N Seitz Drive sus W.Alder s
Parcel No. 12330-33-90026
Mason County, Washington
March 1, 2019
Project#1917
Prepared For:
Michael Brunner
PO Box 4
Wauna, Washington 98395
Prepared By:
Envirotech Engineering, PLLC
PO Box 984
Belfair, Washington 98528
Phone: 360-275-9374
CLYbp
�tcpF wASI 7T�2
J
43045
GA CG/STE(iE
3/1/19
MASON COUNTY Submittal Checklist
COMMUNITY SERVICES Geological Assessment
Instructions:
This checklist must be submitled with a Geolowcat Assessmert and completed,signed.and stamped by the licensed
professionals)who prepared the Geological Assessment for review by Mason County pursuant to the Mason County
Resource Ordinance. If an Rem is found not appieade,the report should explain the basis for the conclusion.
hmW tAruess specbltary doscsr#en K ants report does notpvvW coatpft"to are lnremovonal ResldenaW Code Secom
R403.1.7 for tbuidattons on or agacent 10 30M Sermon RI03.1.8 for e*anstwe sons or seaw,180e.7.1 of Me trpemadbnal
awd&V Code Sector+for Foundamocra on or a¢toent b scopes
ApplicantpOwner Mike Brunner paw s 12330-33-90025
Sae Address XXX fE Seitz Drive.Belfair
t) A discusson of geoknpc conckkins in the general vicinity of 0*pmposed devebpment,with geologic unit
designation based on referenced maps.
Located on page{s) 5
(2) (a)A discussion of the grounc water condition at the site,
Located on page(s) 7
(b) A d+scrssion of the estimated depth to water.
Located on page-s; 7
(c) A d scission of the Quantity of surface seepage
Located on pages) 6
(d) A discussion of the upsiope geomorphology,
Located on page(s) 3
(e) A discussion of location of upland walerbOdtes and wedads-
Located on pages) 3
(3) The approxnmace depth to hard or dense competent soil.e.g_glacial till or ouAaaash sand.
Located on page.,s 7
(4) A discussion of any geomorphic expression of past slope instability(presence of hummocky ground or ground
cracks,terraeeo topograpt►y indicative of kandside block movement.mowed or arctnect trees inoicaaing
downslope movement,etc-).
Located on page(s) 4
?5) A discussion of the history of landslide actvrty in the vitr+ .as 3vag3ble in the re`e*enced raps and records.
Located on pages) g
(6) An opinion on whether the proposed development s wthin the landside hazard area or its associated buffer or
setback and the potential for landslide activty a'the site in light of the proposed development.
Located on pap(s) g
7) A reoarrnendation by the prepaeer whether a Geatechn cal Report should be requited d further evaluate site
conditions and the proposed development of the subtec:property.
Resv.February 2019
II
II
Locates on page(s)
3) If the presence of a hazara s determned within 300 fleet of the proposed development.then the following are
delineated on a geologic map' site map:
►a1 the area of the proposed development.
Located on Map(s) n/a
(b) the boundaries of the landslide hazard area (top, bo4h skies.and toe).
Located on Map(s) nla
(c) the associated butlers(top,both skies. and toe).
Located on Map(s) rVa
(d) budding or other setbacks(top.both sides. and toe).
Located on Map(s) n1a
(g) A site map drs■ttn to soak showing the property boundaries. scale,north arrow.and the location and nature of
existing and proposed development on the site.
Located on Map(s) Site Plan(appendix A)
I. Michael C. Staten hereby certify under penalty of perjury that I am a
'civil engineer licensed in the State of Washington with specohzed knowledge of geotechnicallgeological engineering
or a geologist or engineering geologist licensed in the State of Washroon with special krrawie4ge of the local
condtiorks. I also certify that the Geological Assessment.dated February 11.-00IQ and entitled
Brunner Single Fancy Resc*ntial Property meets all the
requirements of the Mason County Resource Ordnance, Geologically Hazardous Areas Section, is complete and true,
that the assessment demonstrates ooncusmely that the nsks posed by the landslide hazard can be mitigated through
the included geolechnical design recommendations, and that all hazards are mitigated in such a manner as to prevent
harm to property and public health and safety.
�1r C LV D'�-S
�= 1
434/5
rr .AGrirrt A X
(Signature and Stamp)
Rage 2 or 2
Disciamw-kbsan County does not certify the Quality of lire work done kn Um Geological Assessment.
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
21 TOPOGRAPHY..................................................................................................................................... 3
2.2.1 Upslope Geomorphology............................................................................................................3
2.3 SURFACE DRAINAGE..........................................................................................................................3
2.3.1 Upland Water Bodies.................................................................................................................3
2.4 SLOPE AND EROSION OBSERVATIONS...............................................................................................4
3.0 SUBSURFACE INVESTIGATION.....................................................................................................5
3.1 FIELD METHODS,SAMPLING AND FIELD TESTING...........................................................................5
3.2 GEOLOGIC CONDITIONS.................................................................................................................... 5
3.3 SPECIFIC SUBSURFACE CONDITIONS.................................................................................................6
3.3.1 Groundwater............................................................................................................................... 7
4.0 ENGINEERING CONCLUSIONS.........»..»»............»......................................................................9
4.1 LANDSLIDE HAZARDS.........................................................................................................................9
4.1.1 Landslides and Slope Stability Analysis...................................................................................10
4.1.2 Surface and Subsurface Drainage...........................................................................................10
4.2 EROSION HAZARDS...........................................................................................................................10
4.3 SEISMIC HAZARDS.............................................................................................................................11
4.4 OTHER CONSIDERATIONS.................................................................................................................11
5.0 CLOSURE.............................................................................................................................................12
Appendix A-Site Plan
Appendix B -Soil Information
1.0 INTRODUCTION
Envirotech Engineering, PLLC. (Envirotech) has completed this geological assessment for a
residential property located at XXX NE Seitz Drive, identified as parcel number 12330-33-90026
in Mason County, Washington. As presented herein, this assessment 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 soils descriptions in the
Subsurface Investigation Section; and, assessments for landslides, erosion, seismic hazards, and
other considerations in the Conclusions Section.
An initial geological/ geotechnical evaluation of the project was conducted by Envirotech on
February 1, 2019. It was determined that natural slopes between 15% and 40% were present
within 300 feet of the project. Due to these slope grades, a geological assessment is required
pursuant to landslide hazard areas of the Mason County Resource Ordinance(MCRO).
During the evaluation and site visit by Envirotech, surface and subsurface conditions were
assessed in order to determine if further geotechnical studies are required. After completion of the
field work and applicable Project research,Envirotech prepared this geological assessment.
1.1 Project Information
Information pertaining to the project was provided by the proponent of the property, and
observations from a field visit by Envirotech. The proposed development is expected to consist of
a new single family residence, on-site septic system, and other ancillary features typical of this
type of development. Approximate site development with relation to existing site features are
illustrated in the Site Plan in Appendix A of this report.
1.2 Purpose of Investigation and Scope of Work
The purpose of this geological assessment was to evaluate the project in order to confirm that the
proposed development is outside of any landslide hazard area and its associated buffers and
setbacks as determined in the MCRO. The investigation included characterizing the general
project surface and subsurface conditions,and evaluating the suitability of the soils to support the
planned site development. In order to fulfill the purpose of investigation, the geological/
geotechnical program completed for the proposed improvements of the Project include:
• Review project information provided by the proponent of the project;
• Conduct a site visit to document the site conditions that may influence the construction
and performance of the proposed improvements;
• Define general subsurface conditions of the site by observing soils within test pit
excavations, review well logs from existing wells near the Project, and evaluate
geological and hazard maps depicting the site geology for the vicinity of the project;
• Perform soils testing, such as visual classifications,to determine selected index properties
of the soils;
• Complete an engineering assessment supported by planned site alterations and the surface
and subsurface conditions that were identified by the field investigation, soil testing, and
applicable project research; and,
• Establish engineering conclusions based on findings and anticipated development.
Envirotech Engineering Geological Assessment
PO Box 984 page I Parcel 12330-33-90026
Belfair,Washington 98528 Mason County,Washington
360-275-9374 January 1, 2019
enw.•rton
�, rMu,trW
FaA
dn,m,ron CbrlMr Ok
� Mr,onal.nFun w�MP PW hr
( Y7t{4
LOA*
po-..
• Behar
c•�
Project
KITSAP - -
r--ter, (' '� :.� •:, PlERCF
Vicinity Map from Mason County Website
Envirotech Engineering Geological Assessment
PO Box 984 page 2 Parcel 12330-33-90026
Belfair,Washington 98528 Mason County,Washington
360-275-9374 January 1,2019
2.0 SURFACE CONDITIONS
Information pertaining to the existing surface conditions for the project was gathered on February
1, 2019 by a representative with Envirotech. During the site visit, site features were documented
that may influence construction or reveal potential geological hazards. This Surface Conditions
Section provides information on general observations, vegetation, topography, drainage and
slope/erosion conditions for the project and surrounding areas.
2.1 General Observations
The property is currently vacant land with no improvements, surrounded by residential
development. NE Seitz Drive extends along the south side of the property. Vegetation on and
near the property consists primarily of firs, 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 for an illustration of the general slope indicators with respect to the planned
development.
Descending slopes exceeding 15% are located on and beyond the property. Average slope grades
where development will occur are approximately 8%, and maximum grades of averaging 38%
with a vertical relief of approximately 30 feet were observed.
2.2.1 Upslope Geomorphology
Ascending grades are generally located to the east of the planned development. This slope is
relatively minor within 300 feet of the Project, with no apparent slope grades of at least 15%. The
upland area of the property is situated on a hillside and crest. Landforms are primarily of glacial
origin with centuries of weathering overburden. Additional geomorphology that is pertinent to
both upslope and downslope areas are provided in the Subsurface Investigation Section of this
report.
2.3 Surface Drainage
The majority of the stormwater runoff originating upslope from the anticipated development is
expected to be minimal to moderate. Significant scour, erosion and sediment transport was not
apparent near the project.
2.3.1 Upland Water Bodies
There are no apparent water bodies or wetlands located upslope from the planned development
that would significantly influence the Project.
Envirotech Engineering Geological Assessment
PO Box 984 page 3 Parcel 12330-33-90026
Belfair.Washington 98528 Mason County,Washington
360-275-9374 January 1,2019
2.4 Slope and Erosion Observations
The existing moderate slopes 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 or naturally 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.
The above mentioned indicators, or other signs of 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.
N
A
Aerial Photo from Mason County Website
Envirotech Engineering Geological Assessment
PO Box 984 page 4 Parcel 12330-33-90026
Belfair,Washington 98528 Mason County,Washington
360-275-9374 January 1,2019
3.0 SUBSURFACE INVESTIGATION
Information on subsurface conditions pertaining to the project was gathered during research and a
site reconnaissance. The site visit was accomplished on February 1,2019 by a representative with
Envirotech. Specific information on field methods, sampling, field testing, subsurface conditions,
and results from soil testing are presented in this section of the report. Appendix B has pertinent
information on subsurface conditions for the Project,including test pit log(s)representative of the
site soils, and water well report(s)originating from the subject property and/or nearby properties.
3.1 Field Methods,Sampling and Field Testing
Information on subsurface conditions for the Project was accomplished by probing anticipated
foundation areas with hand tools, and observing soils within test pit excavations and/ or earth
cuts. Information on subsurface conditions also included reviewing geological maps within the
Project vicinity, and water well reports originating from nearby properties. No soil samples were
collected for this Project. Envirotech measured the relative density of the in-situ soils by gauging
the resistance of hand tools.
3.2 Geologic Conditions
In general, soils at the project are composed of materials from glacial advances. The geologic
conditions as presented in the "Geologic Map of Washington," compiled by J. Eric Schuster,
2002 indicates Quaternary sediments, Qg. Quaternary sediments are generally unconsolidated
deposits, and dominantly deposited from glacial drift,including alluvium deposits. This project is
located within the Puget Lowland. Typically, "lower tertiary sedimentary rocks unconformably
overlie the Crescent Formation." as revealed in the Geologic Map. Initial sedimentary rocks were
formed from shales, sandstones and coal deposits from rivers. During the Quaternary period, the
Puget Lowland was covered by numerous ice sheets,with the most recent being the Fraser glacier
with a peak of approximately 14,000 years ago. Upon the glacial retreat, the landscape was
formed by glacial erosion glacial drift deposits.
The "Geologic Map of the Belfair 7.5-minute Quadrangle, Mason, Kitsap and Pierce Counties,
Washington" by Michael Polenz, Katelin Alldritt, Nicholas J. Hehemann, Isablle Y. Sarikhan,
and Robert L. Logan,July 2009,provides the following caption(s) for the project area:
Envirotech Engineering Geological Assessment
PO Box 984 page 5 Parcel 12330-33-90026
Belfair,Washington 98528 Mason County,Washington
360-275-9374 January 1. 2019
Vashon glacial ice-contact deposits Sand,gravel,lodgment till,and
flow till;minor silt and clay beds;tan to gray;variably sorted;loose to
compact;massive to well stratified;locally includes over-steepened beds
that typically reflect sub-icc flow,but their dip may,along with
small-scale shears,also have developed as collapse features or due to
glaciotectonic and tectonic deformation;formed in the presence of
mcltwatcr alongside ice,generally toward the end of the glaciation,and is
thus conunonly accompanied by stagnant-ice features,such as kettles and
less-orderly hummocky topography,eskers(also s paratcly mapped as
subunit Qgc),and subglacial or subacrial uutwash channels.Lk-posits and
morphologies that support conceptual association with loth ice and
meltwater are cominon in the map area and suggest that"here unit Qgic is
mapped in the presence of fluted topography,it is commonly only a few
feet thick and locally could have been mapped a-s undifferentiated drift
(unit Qgd).Elsewhere,the unit may he over I f)thick.Unit Qgic also
includes poorly consolidated till commonly accompanied by underlying.
angular sand and noted as"sub-glacially reworked till"by L.aprade(2003)
(see Geologic Scitmgl,especially in fluted areas that lack dead-ice
features.See unit Qgo and Fig.4 for discussion of similarities between
units Qgic and Qgo(and its subunits Qgos.Qgof,and Qgol).A
discrepancy between this map and the Vaughn quadrangle to the south
resulted where Logan and Walsh(2007)mapped undifferentiated
Quaternary deposits(unit Qu)tccause they lacked field exposures and
geomorphic signs of the dead-ice deposits that are apparent north of the
boundary.lkad-icc topography north of the boundary also rcccals a sandy
deposit mapped as unit Qgo.by Logan and'Walsh(2007)to be a facics
within unit Qgic.Locally divided into:
ago
Qgic I /-"Qge
.'
af�Qoa
,Oaf i Qgof
Qls r Qgt �
Qgt Qgo 1 - rOafQoa
�. r Qa
3
y / 1
Qgic Omw`',-Q 9 Qgt Qpf
� Qts_1 .
Ooa
i Qgt� Qgic /' am Qa
Qa(� i
CQ9B f Qa J o
Q� r�_ am
•
Qgic i' A,
Qgic Project ai
Qm
,Oaf.) Qa. Q3s? Qaf
Oaf
Om
a Vaps j
OmW /
Qoa
all am QQ
1 0.5 0 1 MILE briM
aia!►7nairei .. i .
Geologic Map obtained from WA DNR
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
Envirotech Engineering Geological Assessment
PO Box 984 page 6 Parcel 12330-33-90026
Belfair,Washington 98528 Mason County,Washington
360-275-9374 January 1,2019
locations. Soils for this project were described utilizing the Unified Soil Classification System
(USCS). Using the USCS in conjunction with estimated relative densities and other anticipated
engineering properties of the soil, susceptibility for potential landslides, erosion and seismic
hazards may be assessed.
The project is primarily composed of undisturbed, native soils, without indications of substantial
fill. Competent bearing soils were encountered at 12 inches below the existing native ground
surface in locations where the ground was probed. For engineering purposes, these native soils
consist of distinguishable layers, as presented below.
Soils within the upper 4 feet of natural ground were observed to be primarily moist, brown silty
sand with gravel (SM). Soils below the upper SM layer were observed to be an SM medium
dense hardpan. The hardpan is believed to extend to depths of at least 50 feet. This is based on
nearby well reports, site geology, and/ or knowledge of the general area. 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 (SCS), the site soils are described as Indianola gravelly
loamy sand, h, with 15% - 30% slopes. See the soil map below, and the applicable SCS soil
profile(s)in Appendix B of this report.
N
A
o m 1W m m
Soil Survey From USDA Natural Resources Conservation Service
3.3.1 Groundwater
From the water well report(s) and knowledge of the general area, permanent groundwater is at
Envirotech Engineering Geological Assessment
PO Box 984 page 7 Parcel 12330-33-90026
Belfair,Washington 98528 Mason County,Washington
360-275-9374 January 1,2019
least 100 feet below the current ground surface. Surface seepage or perched groundwater at
shallow depths was not observed on-site, nor indicated on the well reports. However, some
seasonal groundwater is expected to flow directly above the hardpan on occasion.
Envirotech Engineering Geological Assessment
PO Box 984 page 8 Parcel 12330-33-90026
Belfair,Washington 98528 Mason County,Washington
360-275-9374 January 1,2019
4.0 ENGINEERING CONCLUSIONS
The following sections present engineering assessments and conclusions concerning the project.
These conclusions have been made available based on the planned construction activities as
outlined in the Introduction Section of this report; general observations of drainage and
topography as summarized in the Surface Conditions Section; and, soil conditions that were
identified by the field investigation and soils testing as outlined in the Subsurface Investigation
Section. Conclusions for the Project that is provided herein, includes pertinent information for
landslide,erosion and seismic hazards.
4.1 Landslide Hazards
For the planned development, as provided in the Introduction Section of this report, it is
Envirotech's opinion that the proposed development is not subjected to or cause adverse impacts
to a landslide hazard area or its associated buffer or setback as defined in the MCRO. This
conclusion is based on the contents provided in this report.
Landslides are natural geologic processes, and structures near slopes possess an inherent risk of
adverse settlement, sliding or structural damage due to these processes. Geotechnical engineering
cannot eliminate these risks for any site with sloping grades because gravity is constantly
inducing strain on the sloping soil mass. Excessive wet weather and/ or earthquakes will
exacerbate these strains. Geotechnical engineering considers excessive wet weather and `design'
earthquakes in order to provide an acceptable factor of safety for developing on or near sloping
terrain. These factors of safeties are based on engineering standards such as defining engineering
properties of the soil,topography, water conditions, seismic acceleration and surcharges.
Surface sloughing or other types of surficial slope movements usually do not affect the deep-
seated structural capability of the slope. However, excessive and/or repeated surficial slope
movements, if not repaired, may represent a threat to the structural integrity of the slope.
Maintenance of the slope should be completed if the situation does arise in order to prevent the
possibility of further surficial or deep seated slope movements that may be damaging to life or
property.
According to the Department of Natural Resources (DNR) "LHZ — Final A-1 Map — Landslide
Inventory—Mason Watershed, by Sarikhan, et. al., May 2007," previous landslide activity is not
recorded near the project. Per the Resource Map from DNR, the Project is not within terrain
labeled `highly unstable' or `highly erodible' relating to soils. DNR labeled portions of this
project as medium to 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 DNR is
provided below:
Envirotech Engineering Geological Assessment
PO Box 984 page 9 Parcel 12330-33-90026
Belfair,Washington 98528 Mason County,Washington
360-275-9374 January 1, 2019
F 0.0
Project ,
(l j
1
Y4tir
9.
Soils
Hydnc Sods
Highly Unstable
/ RJ r ; • .�. ---..__--- -. Highly Erodible
• --
No Data or Gravel Pits
�r r _.-- _-- _ Slope Stability-West •-
1
Moderate Slope Instability_.
0 0.2Nu High Slope Instability
0
Map from Washington State Department of Natural Resources Website
4.1.1 Landslides and Slope Stability Analysis
Past landslide activity or high slope instability indicators near the proposed development was not
revealed during the project research. In addition, detrimental landslide activity or potential high
landslide indicators were not observed during the site visit as outlined in the Surface and
Subsurface Conditions Sections of this report. Due to these factors, and existing/ proposed
conditions, a slope stability analysis was not deemed necessary for this project. Considering the
planned construction as summarized in the Introduction Section of this report; the aforementioned
surface and subsurface conditions for the project; the slope stability assessment provided herein;
and the Engineering Conclusions provided later in this report, it is our opinion that the project is
not within a landslide hazard area, and that the proposed site alterations will not encourage a
landslide hazard.
4.1.2 Surface and Subsurface Drainage
This project does not appear to experience significant subsurface drainage or surface runoff. It is
our opinion that groundwater or surface drainage is not a limiting factor for this Project.
4.2 Erosion Hazards
Based on the USCS description of the Project soils, the surface soils are considered moderately
erodible. According to the Resource Map from the Washington State DNR, as provided above,
the Project is not within terrain labeled `highly erodible.' This Project is not within an erosion
hazard area as defined by the MCRO. Erosion hazard areas are those with USDA SCS
designations of River Wash (Ra), Coastal Beaches (Cg), Alderwood Gravelly Sandy Loam on
Envirotech Engineering Geological Assessment
PO Box 984 page 10 Parcel 12330-33-90026
Belfair,Washington 98528 Mason County,Washington
360-275-9374 January 1,2019
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).
Temporary and/ or permanent erosion control measures may be required for any site when land
disturbance is involved. 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 conditions and planned disturbance of this Project include wind-borne silts during dry
weather, and sediment transport during prolonged wet weather. Sediment transport of disturbed
soils could be from stormwater runoff or tracking off-site with construction equipment. Although
an engineered erosion control plan is not warranted for this project, Best Management Practices
(BMP's) should be employed during and after construction. Ordinary BMP's includes silt
fencing,protection of drainage outlets and vegetating denuded areas.
Erosion control information and specifications may be found in the applicable "Stormwater
Management Manual for Western Washington,"prepared by the Washington State Department of
Ecology Water Quality Program.
4.3 Seismic Hazards
Soils immediately below the expected foundation depth for this Project are generally Type D,
corresponding to the International Building Code (IBC) soil profiles. According to the IBC, the
regional seismic zone is 3 for this Project. The estimated peak ground acceleration ranges from
0.50g to 0.60g. This estimation is based on the United States Geological Survey(USGS) National
Seismic Hazard Project in which there is an estimated 2% probability of exceedance within the
next 50 years.
There are no known faults beneath this project. The nearest Class `A' or 'B' fault to this property
is the Tacoma Fault Zone. This fault is a Class `A,` and is located approximately 5 miles to the
south of the Project. This information is supported by the USGS Quaternary Fault and Fold
Database for the United States.
The potential for liquefaction and other earthquake induced hazards are believed to be low for
this project. This is based on subsurface conditions such as soil characteristics and the lack of a
permanent and substantial shallow water table. Subgrade characteristics that particularly
contribute to problems caused by seismic events include submerged and confined, poorly-graded
granular soils. Although gravel- and silt-sized soil particles could be problematic, fine and
medium grained sands are typically subjected to these types of seismic hazards.
4.4 Other Considerations
Conclusions in this report are based on the type and location of the anticipated development, and
existing on-site and off-site conditions. Site development that significantly deviates from the
anticipated improvements presented in this report, or nearby development that influences this
Project may require geotechnical design recommendations.
Envirotech Engineering Geological Assessment
PO Box 984 page 11 Parcel 12330-33-90026
Belfair,Washington 98528 Mason County,Washington
360-275-9374 January 1,2019
5.0 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
Envirotech is promptly notified if project and subsurface conditions found on-site are not as
presented in this report so that we can re-evaluate our recommendations.
This report presents a geological/geotechnical assessment, and is intended only for the owner, or
owners' representative. Furthermore, this report is only valid for the project information and
location described herein.
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,
E'nvirootteechh Engineering
Michael Staten,P.E.
Geotechnical Engineer
Envirotech Engineering Geological Assessment
PO Box 984 page 12 Parcel 12330-33-90026
Belfair,Washington 98528 Mason County,Washington
360-275-9374 January 1,2019
i
�I APPENDIX A
SITE PLAN
I
�I
SCALD 1 ]ILH =W FEET
4�
T PE
_ PR PERr-f UM
PRMPOSED
=)JGiLE FWL'i—�`
NE :EIT2 CREVE
PDXCTf O%NEV/ LECATIEN
SZIrJGLE FAMILY PROPERTY
GEOLOGICAL ASSESSMENT
>w?mR
�� M NE GEITZ DR
i SIPE WCATDM'.FS£ FDSS WA&L�Yi EMJOIIITFM Afl'OR PARCEL LPZA 33 900e6
EXTRAPOLRTEO FROM 4 PUBLOC LIWR 93JEE WHERE 4PPROPREATE NAZON CO LINTY,VASHINGTON
Z BOLMIPR]EG ON THC: ATE PLNJ LERE fIPT PREPhREO BY N LltET6ID LEGEND E>WENE77?'
9.RVEYUP L�A7M3Z Cr CITE FEATLAM 42 �!]S7CA "UB".UEFACE EN,)3 MrH EKMEEPZG
IE_--aMrXXt AL MWR HERE,VCTH RELATEN TO M.E PM3E3FTf It M PO HO:9B4
Mr.T HE VER7FLEM Hf TTE OWNER, T}E CCF4LUZa3Z 40 —a fL PE DMCGTOP 8GFpA-IPXHINU ON 905iE6
REC"ENDAIne PPII,JEDU DJ T}E G0jM tGCN-- QTIDMEAL I S��'a REPORT
MEB4'f0 ON GEOLOGEC N ltwACE FEATurm, THAT'mn" P() PROIE %Q-M-"74
DE LCOWEO ON 4N0 OFF THE PROPERT'i, MP ARE NOT UMMAMLY �� T P� SITE PLAN
b4ZED OFF OF PROPERTY L9F•. W r 3M ON TY9G G[TE PLAC
APPENDIX B
SOIL INFORMATION
TEST PIT LOG
TEST PIT NUMBER TP-1
PROJECT: Banner GedogIcA Ammnw nt DATE OF LOG: 0=112019
PROJECT NO: 1917 LOOGED Or. RJM
CLIENT: Banner EXCAVATOR: NIA
LOCATION: ParaW 1 -90Q20 DRILL RIM Nm
Merton Caniy,Wa@Hn&m ELEVATIOht WA
NRIAL DEPTH OF WATER NIA FINAL DEPTH OF WATER WA
K&FMTAI trrANGNu m;WIRAImN nw
DEPTH aA11nm USCG WSCRIFinaw LL PI CuwE
AND TEST DATA DEPTH M 10 a0 S4
.............................I............
D - r 61r1 No et011t medlum da GILTY
BAND sM GRAVEL frsnl In*m wd
r mhm d ed.Sand k pMmmbr adman
1 Nan pteedn
I
Grey SaW,Madill daiyY
9Ae.
a
4
0 Excsobw iwTimied at wpcmkrmWy
&G feat
s
s
s
e
�a
No(breurdwn w Eftawyo m ENVIROTECH ENGINEERING
ttJbl�,��wt.1w sty o ar,tr.iea,d drn�fnat�
Geatadmkcd Ervirmedno
4ilmrdldwd�gtMrrimn dlfw�iR
►1aD Vnt Descroncr twyaoa parry as+a.}.D X ww--V Wopes—Mabm Carry
Wafin Igtor
Mason County, Washington
Ic—Indianola loamy sand, 15 to 30 percent slopes
Map Unit Se ir%;
AWwnaf map urut symbol: AM
Elevabm 0 to OW feet
Mean annual preaprft6arr.• 30 to 81 inches
Mean arrswl air Mgperave: 48 to 50 degrees F
Frost4iree period: 170 to 210 days
Fan7dand dasaicalmon: Farmland of statewide importance
Map Unit Composition
fndianola and san"r soils: 85 perce+n
Minor componerts. 15 percent
Ea6rnates are based an observations,descriptions,and t ansecfs of
Noe mapunit.
Description of kKlianota
Setting
Landlbrm: Eskers.kames.terraces
Landibrm Position jbsv m naio : Bactcsiope
Lamlbrmpo an : Side slope
001—i pe alepe• linear
Aamm-sbpe ahWe. Linear
Parer*material Sardy glacial outwash
Typical profile
Oil-0 b 1 wxlwa: slightly decorrposed plant material
A-1 b 6 inches. loamy sand
13wl-6 to 17 kxh": loamy sand
13w2-17 b 27 kwhes- sand
BC-27 to 37 loch t sand
C-37 to 60 ircher sand
Properties acid q-W—
Slape_ 15 to 30 percent
Depth to reef ich a leabwe: More than 80 inches
lNaft&W draarrage rues: Somewhat excessrMy draped
Cpaeiy of dee mod indOg layer b ba►rsmit agder(Ksao: Ffigh b
very high(5A6 to 99.90 n&r)
Depth to water table.• More titan 80 inches
FrequencydfAmbig Nam
Frequency ofporx*g: Now
AvadRanle water Mot in proms: law(abort 3.9 inches)
kNerprebw groups
Land capabady d undficabon(irrgaled): Oe
Land aapabRy daps fwlon(noninigated): 4e
Hydrologic SoN Grog: A
A-A Nab"AeeflcaCea Ham sac W" 29=19
» Con"noo a Senfte Natcal COOpNOW sl!sin" Pap 1 Of 2
r
Map Unit Description Indianola loamy sand, 15 to 30 percent slopes---Mason County,
Washington
Forage suitability group: Droughty Soils(G002XS401 WA),
Droughty Soils(G002XN402WA)
Hydric soil rating. No
Minor Components
Alderwood
Percent of map unit: 8 percent
Landform: Ridges, hills
Landform position(two-dimensional): Backslope
Landform position(three-dimensional): Side slope, nose slope,talf
Down-slope shape: Linear,convex
Across-slope shape: Convex
Hydric soil rating. No
Everett
Percent of map unit 5 percent
Landform: Kames,eskers, moraines
Landform position(two-dimensional): Backslope
Landform position(three-dimensional): Side slope
Down-slope shape: Convex
Across-slope shape: Convex
Hydric soil rating: No
Norma
Percent of map unit: 2 percent
Landform: Depressions,drainageways
Landform position(three-dimensional): Dip
Down-slope shape: Concave, linear
Across-slope shape: Concave
Hydric soil rating: Yes
Data Source Information
Soil Survey Area: Mason County,Washington
Survey Area Data: Version 14,Sep 10,2018
R,we print,sign ar,<J r�lui n It,(lie bel,;ylwer I(u:F uilcq y
WA(er Well Report CUrI-4rn1
t! 0.W..J-EwM,P:(,,;iy mm.TV(o)y drAm Nocitir of Jnt4vnt No. W T.Ttt526
0
x(:v t c I. r
CL trot lj��1:1.110V.� Wt'11 1)'1 A.;:IN I AVCZ 23A
[0011'_AIIJcLnm W:i"r 12 ielif Pcrnit N.,
Lj U:wm:.�i,%wn KcVin SL-iekLrer
put It'-Islut I.%L,:, 1zIJt.__I'_;__ r]Mk:vi. drczia;_Ma�t_ad.
1 Nrm F.n2r..ioq%TA1 1-4 A Sec 3o Tw"2.3 7!�I-
'
0 M-u,, 0.�J, 0 J..:1:N 1,1 1 AL I.%V LjL MiWS..
'
r_ . UI*LE!ISJONB Di—ofol '-11,' 258 - 16.,.`LEQ1:[p,2D'I
0 1:,r-r—P. .25a :_�mg
.M�5TJI;J;cm)Y11117r,111.% rux No 12330-76-90052
0.
253
cuisi,rRUCTJOh OR UICOMMISSION PROLTDCRE.
0 11 h-
W-1 17,!;1-NIX:M.LVA
S 4. WTEFI-N_
------ To 1 4) 2
0
Di-
%rom zmed & i.4ravul
Ov.. J;."..
(L
R-iish hr,-,&m QrAyn.1 11)
Betcmite t,1 1 29 74
—mr,7- sarA.4 ,atth
c'Tmz. t P 74 (143
C rytt —sub.
PJlj-�h ta:g= Clay �itjj gy
WAIER LENILS::J
_ji. -; .__.210 I)ark hn-&Ti r'Yv:zr'yni, r;nmri
VAE gmrim ik.—
w; Fails.11 LCjZaj._r_1ay with aravel. U. 221
WZLL TESTS.
I JVs
with water 221 2FIR
0
VY 1At__,
E CTJ V E I
LU MAR
30
6/2/04
WELL CONSTRLMONC ERTI PECATION: J CLrA-%_,1eL x bx jeep.NsFmAxl.:y K cwtittickiwo a:clls wall, -Id cwlvl.111a' 11 d]
1Vv0.:I.V!mv W..l VuL.SDUO.J11 dll(711V iLdu:tm..An tJ�)ilcd AA�;,XX UU.
a-11.1i'L, kLb. 98528
P Aih-411Nw DAVISLI I OA D_jrc., C14
11-1..'P LIU.J.-I V.
GEO Z011- 6MZ
Mason County Review Checklist
For a Geological Assessment
Instructions:
This checklist is intended to assist Staff in the review of a Geological Assessment. The Assessment 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 Assessment 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 referthe case to the Planning Manager or Director.
Applicant's Name: Y-V r1 YlQuy-
Permit#: 12�J liol q' (��J33 � Parcel#'s:
17- 330-33-10oZ6
Date(s)of the Document(s) reviewed: M a✓C! / 21011
1. A discussion of geologic conditions in the general vicinity of the proposed development,with geologic unit
designation based on referenced maps.
OK?_ Comment:
2. (a) A discussion of the ground water conditions at the site,
OK? Comment:
(b) A discussion of the estimated depth to water,
OK? _Comment:
(c) A discussion of the quantity of se seepage,
OK? V Comment:
(d) A discussion of the upslope geomorphology,
OK? Comment:
(e) A disc sion of location of upland waterbodies and wetlands.
OK? Comment:
3. The approxi ate depth to hard or dense competent soil, e.g. glacial till or outwash sand.
OK? W, Comment:
4. A discussi n of any geomorphic expression of past slope instability(presence of hummocky ground or ground
cracks, terraced topography indicative of landslide block movement, bowed or arched trees indicating
downslope movement, etc.).
OK? X Comment:
5. A discussion of the history of landslide activity in the vicinity, as available in the referenced maps and records.
OK? Comment:
6. An opinion oh w ether the proposed development is within the landslide hazard area or its associated buffer or
setback a h potential for landslide activity at the site in light of the proposed development.
OK? Comment:
7. A recommendation by the preparer whether a Geotechnical Report should be required to further evaluate site
conditions and thg proposed development of the subject property.
OK? Comment:
8. If the presence of a hazard is determined within 300 feet of the proposed development, then the following are
delineated on a geologic map/site map:
Pagel of 2 Form Effective June 2008
(a) the area of the proposed development,
OK? Comment:
(b) the boundaries of the landslide hazard area(top, both sides, and toe),
OK? Comment:
(c) the associated buffers (top, both sides, and toe)
OK? -- Comment:
(d) building or other setbacks (top, both sides, and toe).
OK? Comment:
9. A site map drawn to scale showing the property boundaries, scale, north arrow, and the location and nature of
existing and pro osed development on the site.
OK? _Comment:
Are the Documents signed and stamped? _ By whom? e/v--
License#: License type: P
FIRST REVIEW Approved ❑ Need more info.
If not approved, what is the next action/recommendation for further action?
Reviewed by 1"�'`' '`J on Time spent in review:
SECOND REVIEW/UPDATE ❑ Approved ❑ Need more info.
If not approved, what is the next action/recommendation for further action?
Reviewed by on . Time spent in second review:
THIRD REVIEW/UPDATE ❑ Approved ❑ Need more info.
If not approved, what is the next action/recommendation for further action?
Reviewed by , on . Time spent in third review:
Disclaimer. Mason County does not certify the quality of the work done in this Geological Assessment
Page 2 of 2 Form Effective June 2008