HomeMy WebLinkAboutGEO2019-00072 BLD2019-01119 - BLD Engineering / Geo-tech Reports - 9/14/2019 RECEIVED
SEP 2 0 L o
615 W. Alder Street
Geological Assessment
Mullen Single Family Residential Property
282 SE Dawnview Dr, Shelton
Parcel No. 22028-32-90021
Mason County, Washington
September 14, 2019
Project#19183
Prepared For:
Robert and Jean Mullen
28223 34th Ave S
Auburn, Washington 98001
Prepared By:
Envirotech Engineering
PO Box 984
Belfair, Washington 98528
Phone: 360-275-9374
CLY•r)r s
` w t
• 4303!5 ` a
9/14/19
MASON COUNTY
j COMMUNITY SERVICES Geological Assessment
Building.Planning,Environmental Health,Community Health
Instructions:
This checklist must be submitted with a Geological Assessment and completed,signed,and stamped by the licensed
professional(s)who prepared the Geological Assessment for review by Mason County pursuant to the Mason County
Resource Ordinance. If an item is found not applicable,the report should explain the basis for the conclusion.
Note:Unless specifically documented, this report does not provide compliance to the International Residential Code
Sections R403.1.7 for foundations on or adjacent to slopes, Section R403.1.8 for expansive soils or section 1808.7.1
of the International Building Code Section for Foundations on or adjacent to slopes.
Applicant/Owner Robert and Jean Mullen Parcel# 22028-32-90021
Site Address 282 SE Dawnview Dr Shelton
(1) A discussion of the geologic conditions in the general vicinity of the proposed development,with geologic unit
designation based on referenced maps.
Located on page(s) 5-6
(2) (a) A discussion of ground water conditions,
Located on page(s) 7
(b) A discussion of the estimated depth to water,
Located on page(s) 7
(c) A discussion of the quantity of surface seepage,
Located on page(s) 4 and 7
(d) A discussion of the upslope geomorphology,
Located on page(s) 3
(e) A discussion of location of upland waterbodies and wetlands.
Located on page(s) 3
(3) The approximate depth to hard or dense,competent soil,e.g.glacial till or outwash sand.
Located on page(s) 5
(4) A discussion 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.).
Located on page(s) 4
(5) A discussion of the history of landslide activity in the vicinity,as available in the referenced maps and .
records.
Located on page(s) 8
(6) An opinion on whether the proposed development is within the landslide hazard area or its associated buffer or
setback and the potential for landslide activity at the site in light of the proposed development.
Located on page(s) 8
(7) A recommendation by the preparer whether a Geotechnical Report should be required to further evaluate site
conditions and the proposed development of the subject property.
Located on page(s) 12
(8) If the presence of a hazard is located within 300 feet of the proposed development,then the following are
delineated on a geologic map/site map:
(a) The area of proposed development,
Located on map(s) Site Plan (Appendix A)
(b) The boundaries of the landslide hazard area(top, both sides,and toe),
Located on map(s) Site Plan(Appendix A)
(c) The associated buffers (top,both sides,and toe),
Located on map(s) Site Plan(Appendix A)
(d) Building or other setbacks(top,both sides,and toe),
Located on map(s) Site Plan (Appendix A)
(9) A site map drawn to scale showing the property boundaries,scale,north arrow, and the location and nature of
existing and proposed development on the site.
Located on Map(s) Site Plan(Appendix A)
I, Michael Staten, hereby certify under penalty of perjury that I am a civil engineer licensed in the State of Washington
with specialized knowledge of geotechnical/geological engineering or a geologist or engineering geologist licensed in
the State of Washington with special knowledge of the local conditions. I also certify that the Geological Assessment
dated September 14,2019 ,and entitled Mullen Single Family Residential Property , meets all
the requirements of the Mason County Resource Ordinance,Geologically Hazardous Areas Section,is complete and
true,that the assessment demonstrates conclusively that the risks posed by the landslide hazard can be mitigated
through the included geotechnical design recommendations,and that all hazards are mitigated in such a manner as
to prevent harm to property and public health and safety.
L
43o45WSJ
9/14/19
Disclaimer:Mason County does not certify the quality of
the work done in this Geological Assessment.
Page 2 of 2
TABLE OF CONTENTS
1.0 INTRODUCTION................................................................................................................................. 1
1.1 PROJECT INFORMATION.................................................................................................................... 1
1.2 PURPOSE OF INVESTIGATION AND SCOPE OF WORK........................................................................ 1
2.0 SURFACE CONDITIONS....................................................................................................................3
2.1 GENERAL OBSERVATIONS..................................................................................................................3
2.2 TOPOGRAPHY..................................................................................................................................... 3
2.2.1 Upslope Geomorphology............................................................................................................ 3
2.3 SURFACE DRAINAGE.......................................................................................................................... 3
2.3.1 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......................................................................................................8
4.1 LANDSLIDE HAZARDS......................................................................................................................... 8
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 282 SE Dawnview Drive, identified as parcel number 22028-32-
90021 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
September 5, 2019. 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 garage and driveway, new septic tank, and other ancillary features typical of this type of
development. The development is expected to be over 50 feet from any slope exceeding 40%
grades, and land clearing is expected to be at least 25 feet from the top of such slopes.In addition,
roof drainage is expected to be through downspouts atop splash blocks, and infiltration facilities
avoided. 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 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 1 Parcel 22028-32-90021
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 14,2019
N
C-
1:S
Project
Vicinity Map from Mason County Website
Envirotech Engineering Geological Assessment
PO Box 984 page 2 Parcel 22028-32-90021
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 14,2019
2.0 SURFACE CONDITIONS
Information pertaining to the existing surface conditions for the project was gathered on
September 5, 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 currently has an existing single-family residence, on-site septic, and driveway, and
is surrounded by residential development. SE Dawnview Drive extends along the north side of
the property, and a private access road bisects the parcel to the south and west of the home.
Vegetation on and near the property consists primarily of firs, maples, and other trees and
shrubbery common to this area of the Pacific Northwest. An aerial photo of the Project and
immediate vicinity is provided on the following page.
2.2 Topography
The topographic information provided in this section was extrapolated from a public lidar source,
and incorporated observations and field measurements. Where necessary, slope verification
included measuring slope lengths and inclinations with a cloth tape and inclinometer. See the Site
Plan in Appendix A 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.The steepest,average
slope grades within 300 feet of the development are approximately 56% with a vertical relief of
approximately 40 feet.
2.2.1 Upslope Geomorphology
Ascending grades are generally located to the northwest of the planned development.
This slope is relatively minor within 300 feet of the Project, with no apparent slope
grades of at least 15%.The upland area of the property is situated on a hillside and crest.
Landforms are primarily of glacial origin with centuries of weathering overburden.
Additional geomorphology that is pertinent to both upslope and downslope areas are
provided in the Subsurface Investigation Section of this report.
2.3 Surface Drainage
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 influence of 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 22028-32-90021
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 14,2019
2.4 Slope and Erosion Observations
The existing 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.
A tension crack was observed within four feet of the top of the steeper ravine slope. Groundwater
seepage and leaning/bowing trees were also noted within the ravine slope during the site visit
indicating shallow earth slippage.
N
300
Aerial Photo from Mason County Website
Envirotech Engineering Geological Assessment
PO Box 984 page 4 Parcel 22028-32-90021
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 14.2019
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 September 5, 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 Squaxin Island 7.5 Minute Quadrangle,Mason and Thurston Counties,
Washington by Robert Logan et al.,2003,"provides the following caption(s)for the project area:
Envirotech Engineering Geological Assessment
PO Box 984 page 5 Parcel 22028-32-90021
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 14,2019
Vasbou till UnsoRed and highly compacted mixture of
clay,stlt.sand,and gran el deposited duectly by vlacin tie.
gray"here fresh and light yrllox%i%h brDun-where oxidized,
:ery low pe►meabiltty,moo commonly"maum supported
but may be clast-supported,matrix generally feels more
grim than oumash sands nben rubbed benyeen fingers.due
to being more angular than waxet-isorked srdimrms cobbles
and boulders commonly faceted and i or)striated,rWits in
this knt-from Willi) disconnrnwns taxers less than 1 in
duck to more than 10 ft thick,thicknesses of 2 to 10 ft are
most�mnruon,till may include oust ash clay,sand,silt_and
gravel.or ablation nil that is too thm to subsranually mask
the tmirtlymg,tolling ill plain,ritauc botddrrs me
commonly associated with till plains but may also occur as
lag depoun%hrn the undrrh usg:Se}osns hat,bmt
modified by melnxatet,typically,weakly developed modern
soil has formed on the cap of lose gravrl but the
undctl mg ttil is unweathered,local textural features in the
till mcludr(lost banding and apophvses extending 10 to 13
ti downwtud into underly-ing sand and gravel(or till)and
that we oriented transverse to ice Mott direction
N
.�. Project
P I ;
nr '._ j ray /�`�},} •�'n./ � � } ®".>> -
�rf
,A q X 7/
4.
V
Geologic Meth from Washington Department of Natural Resources
3.3 Specific Subsurface Conditions
The following subsurface conditions are estimated descriptions of the project subgrade utilizing
information from the depth of penetration at all testing, sampling, observed and investigated
locations. Soils for this project were 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.
Envirotech Engineering Geological Assessment
PO Box 994 page 6 Parcel 22028-32-90021
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 14,2019
The project is primarily composed of undisturbed, native soils, without indications of substantial
fill. Competent bearing soils were encountered at 18 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 18 inches of natural ground were observed to be primarily organic laden
soils. Soils below the duff layer extending to a depth of 4 feet are silty sands with gravel as
typical in the area and shown on the well log. Varying soil conglomerates are below. 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 loamy
sand, Ih and L, with 8% - 30% slopes. See the soil map below, and the applicable SCS soil
profile(s)in Appendix B of this report.
N
0 9 f10 dID n
Soil Survey from USDA Natural Resources Conservation Service
3.3.1 Groundwater
From the water well report(s)and knowledge of the general area,permanent groundwater
is at least 160 feet below the current ground surface. 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 as
seepage from the hillside was indicated.
Envirotech Engineering Geological Assessment
PO Box 984 page 7 Parcel 22028-32-90021
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 14,2019
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
Our conclusions are based on the planned development, as provided in the site plan and
Introduction Section of this report. Although the development is within 300 feet of the landslide
hazard area, it is Envirotech's opinion that the proposed development is not subjected to or cause
adverse impacts to the landslide hazard area. This conclusion is based on the contents provided in
this report.
Landslides are natural geologic processes, and structures near slopes possess an inherent risk of
adverse settlement, sliding or structural damage due to these processes. Geotechnical engineering
cannot eliminate these risks for any site with sloping grades because gravity is constantly
inducing strain on the sloping soil mass. Excessive wet weather and/ or earthquakes will
exacerbate these strains. Geotechnical engineering considers excessive wet weather and `design'
earthquakes in order to provide an acceptable factor of safety for developing on or near sloping
terrain.These factors of safeties are based on engineering standards such as defining engineering
properties of the soil,topography,water conditions,seismic acceleration and surcharges.
Surface sloughing or other types of surficial slope movements usually do not affect the deep-
seated structural capability of the slope. However, excessive and/or repeated surficial slope
movements, if not repaired, may represent a threat to the structural integrity of the slope.
Maintenance of the slope should be completed if the situation does arise in order to prevent the
possibility of further surficial or deep seated slope movements that may be damaging to life or
Property
According to the Coastal Zone Atlas of Mason County, Washington, the Project is within and
near terrain labeled `Stable' and `Unstable' regarding potential landslide activity. Stable slopes
are generally not prone to landslides due to small grades and accommodating geology.
Historically, intermediate terrains have no known landslides. A site specific analyses and
conclusions concerning the slopes are presented herein. A Stability Map from the Coastal Zone
Atlas for the general area of this Project may be found below.
Envirotech Engineering Geological Assessment
PO Box 984 page 8 Parcel 22028-32-90021
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 14,2019
N
j t-iairtstene island
,
v
n
,4
V
Project
0�!stable
Wif".r Intermediate
x. 77 07 "
Modified
I� Unstable
OW Unstable(old slide)
t uutabte(recent slide)
Map from Washington State Department of Ecology Website
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
recorded near the project, but over 300 feet away from the project. Per the Resource Map from
DNR, the Project is adjacent to 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 22028-32-9002 t
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 14,2019
N ■
A ■
noun
Project ■ %
a on
ip
■ So is
a s Highly Un tatle
�r
tik t� 'J r.'- H,ghiy cre6bie
r� o= No Data or Gavel Fits
Slope Stability-West
` hlodetatP Slope InSlabWtiy
Iso
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
were revealed during the project research. In addition, landslide activity and potential
high landslide indicators were observed during the site visit as outlined in the Surface and
Subsurface Conditions Sections of this report. Due to the planned setbacks and drainage
control for the proposed development, as described in the Introduction Section of this
report, 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 will not be affected by a landslide hazard area,
and that the proposed site alterations will not encourage additional landslides.
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
Envirotech Engineering Geological Assessment
PO Box 984 page 10 Parcel 22028-32-90021
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 14,2019
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).
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 12 miles to the
north 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 t t Parcel 22028-32-90021
Belfair.Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 14,2019
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. This
conclusion is based on our geotechnical study of the project, and does not consider codes,
ordinances,or differing geotechnical judgment.
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,
Envirotech Engineering
Jessica Legarza,M.S. Michael Staten,P.E.
Staff Geologist Geotechnical Engineer
Envirotech Engineering Geological Assessment
PO Box 984 page 12 Parcel 22028-32-90021
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 September 14,2019
APPENDIX A
SITE PLAN
A
SCALE l INCH 150 FEET
150
E%STING SHED
EXISTING DRIVEWAY
EXISTIM SJWLE FAMILY
RESIDFNLE
SE DOVNVWJ DRIVE
EXISTING SEPTIC DRAINFIELD
AREA
t '
PROPOSED
DRIVEWAYPo
�
1 !
t P
ro
t
�% -EXISTING PRIVATE ROADWAY
°` •. KIPOSED GARAGE
PROPERTY L_
° 41 SEA FRdI TOP
e� OF RDX UMPA.
�' VMEJAYION BUFFER FROM
e� —TW OF SI.3PE EXCEEDING 40%
i�F?'ROXDiATE�
TCP W SLOPE EXCEEDING 40%
faUt"f201<Id[A'Ls
PRM=/ OWNER/ LOCATION,
TEE 3P SLOPE SING! E FAMILY PROPERTY
40x GFOGGICAL ASSESSMENT
0PPRO)WATC
WLULM
NOTES, ffiers-38-90021
1. SLOPE INDICATORS WERE FIELD MEASURED BY V4VbMk0.4 AM/OR L66 %X 24VNVIEW DR
EXTRAPOLATED FROM A PUBLIC LIDAR SOURCE VIER£A?P%d!',ATR BOUNDARY OF LMZSLM JVSM COLVOY, WASHINGTON
2. BOUNDARIES ON THIS SITE PLAN WERE NOT PREP/Y A lam'_ HAZARD ARkA LEGEND t1'W=l
SURVEYOR.LOCATIONS OF SITE FEATURES AND Milg[CA+'ilUOR'WACE (APPROXIMATE; ._., f)C#lKIYf N ENGINEERING
DESIMUST�BETIONS AS VEERIF ED BY THE OWNER, THE CDN�D TO TW Mrl�'Y L'�'tjS ...-�'
RECD*f DATIDNS PROVIDED IN THE GEOTECHI(JtAL,'OfOLairA.,AF,POrT SLOPE INDICATOR DE FA tiN4
FSFAtR,1lASHINGTON 98528
ARE BASED ON GEOLOGIC AND SPECIFIC SUBSURFACE FEA74U'WA .11AY PQ PROBE ya�Q•Yyg-9y74
BE LOCATED ON AND OFF THE PROPERTY,AND AK NOf NEl'LS$MMY BASED OFF OF PROPERTY LINES SHOWN ON THIS"..EDE PEAR. TM TEST PIT SITE PLAN
APPENDIX B
SOIL INFORMATION
TEST PIT LOG
TEST PIT NUMBER TP-1
PROJECT: SFR Geological Assessment DATE OF LOG: 09/05/2019
PROJECT NO: 19183 LOGGED BY: MCS
CLIENT: Mullen EXCAVATOR: N/A
LOCATION: Parcel 22028-32-90021 DRILL RIG: None
Mason Counti,Washington ELEVATION: NIA
INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: NIA
STANDARD PENETRATION TEST
SOIL STRATA,
DEPTH SAMPLERS USCS DESCRIPTION LL PI CURVE
AND TEST DATA DEPTH N 10 30 50
0 PT DUFF
r
rr
1 r
f�i
r ,
SM Brown,moist,medium dense SILTY
2 SAND with GRAVEL Gravel is fine and
subrounded Sand is primarily coarse.
Non plastic
3 Excavation terminated at approximately
3 0 feet
4
5
6
7
8
9
10
No Groundwater Encountered ENVIROTECH ENGINEERING
This intonnabon pertarns only to des bmng and should not be Geotechrncal Engineering
interpreted as bung mdrcfte of ft entire site
Map Unit Description Indianola loan iv sand 15 to 30 percent slopes-Mason County.
Yeashngton
Mason County. Washington
Ic—Indianola loamy sand. 15 to 30 percent slopes
Map Unit Setting
National map unit symbol 2t639
Elevation 0 to 980 feet
A.lean annual precipitation 30 to 81 inches
Mean annual air temperature 48 to 50 degrees F
Frost-free period 170 to 210 days
Farmland classification Farmland of statewide importance
Map Unit Composition
Indianola and sin dar soils 85 percent
A9inoi components 15 percent
Estimates are based on observations,descriptions,and transects of
the mapund
Description of Indianola
Setting
Landform. Eskers,kames,terraces
Landform position(two-dimensionO. Backslope
Laridfonn position(three-dimensional) Side slope
gown-slope shape Linear
Across-slope shape Linear
Parent material Sandy glacial outwash
Typical profile
01-0 to 1 inches slightly decomposed plant material
A- 1 to 6 inches loamy sand
Bw 1-6 to 17 inches. loamy sand
Bw2- 17 to 27 inches sand
BC-27 to 37 inches sand
C'-37 to 60 inches sand
Properties and qualities
,lope 15 to 30 percent
Depth to restrictive feature More than 80 inches
Natural drainage class Somewhat excessively drained
Capacity of the most limiting layer to transmit water(Ksat) High to
very high(5.95 to 99 90 mihr)
Depth to water table. More than 80 inches
Frequency of flooding None
Frequency of pondntg None
Available water storage in profile Low(about 3.9 inches)
Interpretive groups
Land capability classification(irrigated) 6e
Land capability classification(noninigated) 4e
Hydrologic Soil Group. A
i e% Natural Resources "eb Sod Survey 918/2019
41110 Conservation Service National Cooperative Sal Survey Page 1 of 2
Map Unit Description Indianola loamv sand.15 to 30 percent slopes---Mason County.
Washington
Forage suitability group Droughty Sods(0002XS401 WA),
Droughty Sods(0002XN402WA)
Hydrrc soil rating. No
Minor Components
Alderwood
Percent of map and 8 percent
Landform Ridges,hills
Landform position(trvo-dimensoorral) Backslope
Landform position(three-dimensional) Side slope,nose slope.talc
Down-slope shape Linear.convex
Across-slope shape Convex
Hydrrc soil rating No
Everett
Percent of rnap unit 5 percent
Landform Karnes.eskers.moraines
Landform position(two-drmensionaU: Backslope
Landform positron(three-dimensional): Side slope
Down-slope shape Convex
Across-slope shape Convex
Hydrrc sod rating No
Norma
Percent of map unit 2 percent
Larxfforw Depressions,drainageways
Landform po:itrorr(three-dtrmensronal) Dip
Down-slope shape. Concave,linear
Across-slope shape. Concave
Hydrrc sod rating Yes
Data Source Information
Sod Survey Area Mason County,Washington
Survey Area Data Version 14,Sep 10,2018
siix Natural Resources Web Soil Surrey 918/2019
adft Conservation Service National Coopetav a Soil Surrey Page 2 of 2
WATER WELL REPORT
copy-E-fty. d,Ar CURRENT
Notice ofkdentNo.WE(*19.3
Construction[DecommissWo rx'in circle) 2 ccj9'70
Construction lJni4uc Ecolop Well ID Tag No NAC328
(MM-4.ZMAIM1,10N WailRigm Itrow,NN
WNW Qtw=N*m4 rINA SCRAA!"
WC It S4ma 44ffmo 2-",F DAV6'MV"
city Clwuy MASON
Li Calitt L oem ion S*-' 114-1/4 N'A I Sc ,—A T%%%�'IVN ItZ—wmar M Chia K I,r SAO)KLQUJRED) w+wOnt
CO%c tar TION 1)"AII-19 Let/Long Lat Deg Lat.Min/Sec
(—., 0-W�+kd 6 fi.. a. 229 It
7. It- R e—A, Long Deg LmgMin/Sec
0- EA-F- R m ft, Tax Parcel No.(Required)120283290021
P110*961kIM OMMA-4 MOM,1111116111110111%F-10 OF WOW WA10400*4111. Artlottara
aiviathil to imit*%Up RAMMIMIA VA A*w-we ew tkva*ataeaa
14
SUZYCLAY 14
claw. mal*m tw U,V saw" d I?
Ob,K No"' GRAY 1lKTTftx*wEw7V8-L 17 SS-
mww"t*N two tw GRAV SILTY MAY 46 j3r—'
SM60solk o!r YI* C] T-1,00nW. 20 !m*wN§rfTYUay-FVwCAAVm —17"—a—M
mumlami.".a MWMNI*MCMPS GKAY1rMKVmy 142 psi-
D'A my emb mdapt -Yft---r- Fk M SH DAWN CLAY,MCI- 131 163
B34DWW 11111TYCIAVAMORAVAL Ids 1171
Qmyrm SAM Q"VV_wirr 17) ra
m Mw#Akuwmnmm COAMORAVILAMWAM 2M12
rum
'r
KIP.
wistip"matt" j3 To ft emir~
,�w PuaILVws 4"Amoftr im
ys" PtA-k-mft A.drarrdara Aff-1111%.
Rem, *k"%no%**Ado
ira- WIWL" Y.* WOW 1,04 "Im, WINI'Low •
boom
FI*VIA-_
AV&A JL—.0Sni►.4*.bA*Rd 2m IL air J__Wv.
Anvom ftw 5#0 IAM
WELL CONSTRUCTION CIERVIFICATIOM,coffitructed arid/or accept re%pot*bility for construction of tWS wet,"m comms,%tv with at Was"gton wet
cmurKismstandaids Materal,u%cd Anol�infortnation reported above are true to my test know'xillicanIl belief
CY)r,llvrjEngmow[.:Trawm N. MiliVA P Dn'lwgCnriparry ARCADIA DRILLING M. .
Driller"FAll"IterrTrairim Sigmt.. Address P0 BOX 1790
Driller or trainee Licem N. 297fr
City,Sme,Zip SHELTON
IF TRAINEE Vwdle� WA . 99584
Drdws signswe KrgrsrratmnNo ARCADDI099K1 Ow 715107
ECV OW 1-20(A.4m?) E.'"y is-Spa Orwri-ey E-Pt.)v,