HomeMy WebLinkAboutGEO2020-00069 for BLD2020-01154 - GEO Geological Review - 10/21/2020 GE07lJZG�'LYo
Mason County Review Checklist
For a Geological Assessment
Instructions:
This checklist is intended to assist Staff in the review of a Geological Assessment.Ihe 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 refer the case to the Planning Manager or Director.
Applicant's Name: $rriAko Permit#: N127oZ0 '011 �' dT Parcel#'s: Z;� ?.,'75 �D�d
Date(s)of the Document(s)reviewed:
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? y Comment:
(c) A discussion of a quantity of surface seepage;
OK? Comment:
(d) A discussion of the upslope geomorphology,
OK? ✓ Comment:
(e) A discussion of location of upland waterbodies and wetlands.
OK? Comment:
3. The approximate depth to hard or dense competent soil, e.g. glacial till or outwash sand.
OK? V Comment:
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.).
OK? Comment:
5. A discussion of the historyof landslide activity in the vicinity, as available in the referenced maps and records.
OK? Comment:
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.
OK? V Comment:
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.
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:
Page 1 of 2 Form Effective June 2008
(\boundaribes
the proposed development,
Comment:
( ries of the landslide hazard area(top, both sides, and toe),
Comment:
.( ted buffers(top, both sides, and toe)
Comment:
( oth etbacks(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 p ed development on the site.
OK? rop Comment:
Are the Documents signed and stamped?.
By whom?
License#:
Li ed nse type:
3fl�4.S ----
FIRST REVIEW pproved ❑ Need more info.
If not approved, what is the next action/recommendation for further action?
Reviewed by.i*/ , on AO 1-1 U 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
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Geological Assessment
Marcinko Single Family Residential Property
410 NE Trudeau Mountain Road, Belfair
Parcel No. 22302-75-90101
Mason County, Washington
May 11, 2020
Project#2066
Prepared For:
Frank and Suze Marcinko
5677 Minnig Ln NW
Seabeck, Washington 98380
Prepared By:
Envirotech Engineering
PO Box 984
Belfair, Washington 98528
Phone: 360-275-9374
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MASON COUNTY )ubmittal Checkh t
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 Suze Marcinko Parcel# 22302-75-90101
Site Address 410 NE Trudeau Mountain Rd
(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
(2) (a) A discussion of ground water conditions,
Located on page(s) 6
(b) A discussion of the estimated depth to water,
Located on page(s) 6
(c) A discussion of the quantity of surface seepage,
Located on page(s) 6
(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) 7
(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) 7
(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) 11
(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) n/a
(b) The boundaries of the landslide hazard area(top, both sides, and toe),
Located on map(s) n/a
(c) The associated buffers (top, both sides, and toe),
Located on map(s) n/a
(d) Building or other setbacks (top, both sides, and toe),
Located on map(s) n/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 May 11,2020 , and entitled Marcinko 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.
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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.................................................................................... 9
4.1.2 Surface and Subsurface Drainage............................................................................................ 9
4.2 EROSION HAZARDS............................................................................................................................9
4.3 SEISMIC HAZARDS.............................................................................................................................10
4.4 OTHER CONSIDERATIONS.................................................................................................................10
5.0 CLOSURE.............................................................................................................................................11
Appendix A-Site Plan
Appendix B -Soil Information
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1.0 INTRODUCTION
Envirotech Engineering, PLLC. (Envirotech) has completed this geological assessment for a
residential property located at 410 NE Trudeau Mountain Rd, identified as parcel number 22302-
75-90101 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 May
1,2020.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 22302-75-90101
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 11,2020
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Envirotech Engineering Geological Assessment
PO Box 984 page 2 Parcel 22302-75-90101
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 11,2020
2.0 SURFACE CONDITIONS
Information pertaining to the existing surface conditions for the project was gathered on May 1,
2020 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 few improvements and is surrounded by residential
development.NE Trudeau Mountain Road extends along the east side of the property.Vegetation
on and near the property consists primarily of firs, salal, 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
are approximately 6% with a vertical relief of approximately 40 feet.
2.2.1 Upslope Geomorphology
Ascending grades are generally located to the northeast 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 22302-75-90101
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 11,2020
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.
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Envirotech Engineering Geological Assessment
PO Box 984 page 4 Parcel 22302-75-90101
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 11,2020
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 May 1, 2020 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 Holly 7.5-minute quadrangle, Jefferson, Kitsap, and Mason Counties,
Washington' by Contreras, Trevor A.; Weeks, Sarah A.; Stanton, Kelsay M. D.; Stanton,
Benjamin W.; Perry, Benjamin B.; Walsh, Timothy J.; Carson, Robert J.; Clark, Kenneth P.;
Mahan, Shannon A.,2012,provides the following caption(s)for the project area:
Envirotech Engineering Geological Assessment
PO Box 984 page 5 Parcel 22302-75-90101
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 11,2020
Geologic Unit Age: late Pleistocene
Geologic Unit Name. Vashon ice-contact deposits
Unit Description: Diamicton. cobbly pebble gravel,silty sandy till.silty pebble gravel, and pebbly sand. with
lesser sand and silt:yellow-tan to gray:loose to very dense: subangular to rounded clasts.variously sorted:
massive to well-stratified;accompanied by stagnant-ice features. such as kettles, hummocky topography.eskers
(separately mapped as unit Qge where distinct).and subglacial or subaerial outwash channels:formed in the
presence of meltwater alongside. in.on,or above ice.Where mapped on fluted uplands that lack more
recognizable stagnant-ice features, unit Qgic is commonly a friable but compact, subglacial melt-out till that
appears permeable Unit Ogic ranges in thickness from a few feet to tens of feet and is mapped over a large
extent of the fluted upland surface. It crudely corresponds to areas mapped by Haugerud(2009b)as rippled fluted
glaciated surface(unit gfr). Unit Ogic was also found in outcrops too small to depict at map scale near Holly in
what appear to be ice-contact slump features As Haugerud(2005)noted on Bainbridge Island,unit Ogic appears
directly on top of older material or locally on advance glacial deposits. and does not have Vashon-age lodgment till
beneath. In the southern portion of this map area, unit Ogic appears to be in contact with older northern-sourced
glacial till, speculated to be as old or older than MIS 6(Double Bluff age). Though found in fluted drumlins
(indicating subglacial emplacement and likely the same age as unit Ogt), unit Ogic is typically a diamict,without
subhorizontal foliation, and is permeable and less competent than a'standard'subglacial lodgment till. It may be
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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.
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 5 feet of natural ground were observed to be primarily moist, brown silty
sand with gravel (SM). 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 Alderwood gravelly
sandy loam, Ab and A,, with 8% - 30% slopes. See the soil map below, and the applicable SCS
soil profile(s)in Appendix B of this report.
Envirotech Engineering Geological Assessment
PO Box 984 page 6 Parcel 22302-75-90101
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 11,2020
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3.3.1 Groundwater
From the water well report(s) and knowledge of the general area, permanent groundwater
is at least 40 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 7 Parcel 22302-75-90101
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 11,2020
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 8 Parcel 22302-75-90101
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 11,2020
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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
te�threpo t is our opinion that the project is not within a landslide hazard area,
andd 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 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
Envirotech Engineering Geological Assessment
PO Box 984 page 9 Parcel 22302-75-90101
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 11,2020
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 an site when land
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disturbance is involved. Erosion control will mostly depend end 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 V fault to this property
is the Seattle Fault Zone. This fault is a Class V and is located approximately 4 miles to the
northeast 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 10 Parcel 22302-75-90101
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 11,2020
5.0 CLOSURE
Based on the project information and site conditions as presented in this report, it is Envirotech's
o inion 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,
Envirotech Engineering
/4" ", %7f� S
Jessica Smith, M.S. Michael Staten, P.E.
Staff Geologist Geotechnical Engineer
Envirotech Engineering Geological Assessment
PO Box 984 page 11 Parcel 22302-75-90101
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 May 11, 2020
r
APPENDIX A
SITE PLAN
SCALE. 1 INCH 100 FEET
0 25 50 100
PROPOUP
SINGLE FAMILY
RESIDENCE
PROPERTY LINE
TP1eo
6Xt DRIVEWAY
DRIVEWAY tADPRx)
PROPOSED
DRAT FDYD
AREA(APPRX)
PROJECT/ OWNER/ LOCATION-
SINGLE FAMILY PROPERTY
GEOLOGICAL ASSESSMENT
O
NOTES xxx NE E TRUDEAu MOUNTAIN ROAD
L SLOPE INDICATORS WERE FIELD MEASURED BY ENVIROTECH,AND/OR PARCEL 22302 75 90101
EXTRAPOLATED FROM A PUBLIC LIDAR SOURCE WHERE APPROPRIATE MA Y WA N
2.BOUNDARIES[INTH IS SITE PLAN WERE NOT PREPARED BY A LICENSED LEGEND ENGINEER,
SURVEYOR.LOCATIONS OF SITE FEATURES AND GEOLOGICAL/ SUBSURFACE
DESIGNATIONS AS SHOWN HERE, WITH RELATION TO THE PROPERTY LINES ENVIROTECH ENGINEERING
MUST BE VERIFIED BY THE OWNER. THE CDICLUSMNS AND SLOPE INDICATQH PO BOX 984
RECOMMENDATIONS PROVIDED IN THE GEOTECHNICAL/ GEOLOGICAL REPORT BELFAIR, WASHINGTON 98528
ARE BASED ON GEOLOGIC AND SPECIFIC SUBSURFACE FEATURES THAT MAY PO PROBE 36D-275-9374
BE LOCATED IN AND ffF THE PROPERTY, AND ARE NOT NECESSARILY
BASED OFF IF PROPERTY LIES SHDVN ON THIS SITE PLAN. TP1 TEST PIT SITE PLAN
APPENDIX B
SOIL INFORMATION
TEST PIT LOG
TEST PIT NUMBER TP-1
PROJECT: SFR Geological Assessment DATE OF LOG: 05,01 2020
PROJECT NO: 2066 LOGGED BY: MCS
CLIENT: Marcinko EXCAVATOR: N'A
LOCATION: Parcel 22302-75-90101 DRILL RIG: None
Mason County.Washington ELEVATION: N/A
INITIAL DEPTH OF WATER: N!A FINAL DEPTH OF WATER: N/A
SOIL STRATA, STANDARD PENETRATION TEST
DEPTH SAMPLERS USCS DESCRIPTION LL PI CURVE
AND TEST DATA DEPTH N 10 30 50
0
SM Brown,moist,medium dense SILTY
SAND with GRAVEL Gravel Is fine and
subrounded Sand Is primarily coarse
1 Non plastic
2
3
4
5 Excavation terminated at approximately
5.0 feet
6
7
8
9
10
No Groundwater Encountered ENVIROTECH ENGINEERING
This mformat,on peRans only to the boring and shoud rid be
Geotechnical Engineering
interpreted as being indrefi�*o/the enbre Me
Map Unit Description Alderwood gravelly sandv loam l5 to'�0 percent slopes-Mason
County,Washington
Mason County, Washington
Ac—Alderwood gravelly sandy loam, 15 to 30 percent slopes
Map Unit Setting
National map unit symbol: 2t627
Elevation 0 to 1,000 feet
Mean annual precipitation. 25 to 60 inches
Mean annual air temperature: 46 to 52 degrees F
Frost-free period 160 to 240 days
Famlland classification Farmland of state,•✓lde importance
Map Unit Composition
Alderwood and similar soils 85 percent
Minor components 15 percent
Estimates are based on observations. descriptions, and transects of
the mapunit
Description of Alderwood
Setting
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
Parent material Glacial drift and/or glacial outwash over dense
glaciomanne deposits
Typical profile
A-0 to 7 inches. gravelly sandy loam
Bwl-7 to 21 inches very gravelly sandy loam
Bw2-21 to 30 inches very gravelly sandy loam
Bg-30 to 35 inches: very gravelly sandy loam
2Cdi-35 to 43 inches. very gravelly sandy loam
2Cd2-43 to 59 inches very gravelly sandy loam
Properties and qualities
Slope. 15 to 30 percent
Depth to restrictive feature. 20 to 39 inches to densic material
Natural drainage class, Moderately well drained
Capacity of the most limiting layer to transmit water(Ksat): Very
loa:v to moderately low(0.00 to 0.06 in/hr)
Depth to water table. About 18 to 37 inches
Frequency of flooding. None
Frequency of ponding None
Available water storage in profile: Very low(about 2 7 inches)
Interpretive groups
Land capability classification(irrigated). None specified
Land capability classification(nonirrigated): 4e
Hydrologic Soil Group. B
LJDA Natural Resources Web Sod Survey 12/10/2016
i` Conservation Service National Cooperative Soil Survey Page 1 of 2
Map Unit Descnpuai Alderwood gravelly sandy loam 15 to 30 percent slopes---Mason
County.Washington
Forage suitability group: Limited Depth Soils(G002XS301 WA).
Limited Depth Soils(G002XF303WA). Limited Depth Soils
(G002XN302WA)
Hydnc soil rating No
Minor Components
Everett
Percent of map unit 5 percent
Landform Karnes,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
Indianola
Percent of map unit 5 percent
Landform Eskers.kames.terraces
Landform position(three-dimensional) Tread
Down-slope shape: Linear
Across-slope shape. Linear
Hydric soil rating: No
Shalcar
Percent of map unit, 3 percent
Landform Depressions
Landform position(three-dimensional) Dip
Down-slope shape Concave
Across-slope shape: Concave
Hydric soil rating. Yes
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
LS0.1 Natural Resourees Web Soil Survey 1210'2018
Conservatlon Service National Cooperative Soil Survey Page 2 of 2
WATER WEE L REPORT
AppLc.itod Ne
Second Cbp- a CoD1
71U.d Copy--Drlllee'e Copy ar"11 or WASERYQTON Formal No ..
(1) OWNER:
Name chuck. Pratt Addrer... � �i�ek
(2) LOCATION OF WELL: county. Mason -- -
!✓!.
. .. - . !t .gee.
heM "it mom"or as1hcbrima n trlc' fy�
(3) Peorom USA nomwlle in bithlaow ti mmsW 1 G I.Of'l l
itrllraat CI 9ra tgw i] orre a
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(4) 1 a air now Sir ittslr�i 1Nr mq ol1O
mp tma p �l SM
ctt(j »1aNa O awn Q Ito
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e - '---iati IMOf� �MIK CI
(9) r-rd _ ((sling ✓.��__
nv�1ONS na iseda
casing fasWletl: 6.. ••Dl.m.rr.m._0._.a to......_...__
Threaded o ..Dlaer.Lela ------
welded Ut ..imam troln..._ IL r at. -- - --- .-
Perforations: vas o Naa _ _ —
Type of perforator ased.. _...... ..._....._�._..-..._..-...-.__.
SIZE of peRor.Uoes......_.... ... M1.by__ ....»la.
--- --- -
perforations groin. .. q.M»».- »_
Perforations from IL Is
...�-.IL --- -
prreomben from._....__,.,_.r.Is At
Screens: Ya Q No o Hydrophyli�- —
ar.aar..er e..ar.�. --
Type- plalstic ygdel No
D:.m. 6. Slot slt< ,020from li4 fl to R _-
DI.- Slot atu from .....fl.to ......_._n -_
Gravel peeked: re.o Na Q sin si gravel: . _ _ -- — �I DE_ECDLQ�
Gravel placed from-_._......-...... __.It.to...._--.....IL _ OFFICE ---
Slrrfg" gNl-' Yes a He O To what deptht --
Material used to seal_.... __......._.. ___...._.__..�.�
Dld my strata contain unu..ble water, We 0 me 0
'type of water!. Depth of strata
.Method of around st.m.off - ---- ��•i —�-�
(7) PUMP: Manufacturer's Naar-_...-_.. -------.--- .— —
Type: _.... BJr.... ..._.—_
(9) WATER LEVELS: Land-surface elevmwn --- —
.bow mean no Level.. _.p.
Static level ..43 .. rim below top of well Deal_FQ�
Artesian prerare.._.._..._,_....._The per sgwre Inch Dam
Arsom tlMMa d tteelaellad t•y .. - i�i►m�"ett' �—
m WW..L 2UM a nw i:latsibr iw!r — — ab
O s DOW fat oladn VM 12 Sifts o Us- Rf ti.noa.< _._... eleaw< q. 3-CeeAghlttd,.22_92L_—rL�
TMM*. 90LA o.Wish it drawdown.har Ln. WELL DRILLER'S STATEMENT:
• _ _— .._ .__ _ _ •• This well was drilled under my Jurisdiction and this report is
•• _ _ _ __^ true to the beat of my knowledge and belief.
It<c.—Y Gat. fume taken m Lf0 hen pump tamed OM (water I.vel
stte.aured cram roll top to ware.aw Water,
NAIEL-11 hOlSo1.1. Drilling C.o.
St.ne Water LOOM Slays Ne Least Y'N lwete e►7.epM plmeon erm,er cerpo ) (T"e or tMaa
Add,,_P 0 Box 123 Port Orcha3 d, _Ws,
sews- _�..»___.__ - .... .. ... .__._ ... .. .... ......_
ier%n_.1 _stAwl. nrb4_ rl+www rill-s, ),�~ ._ �__.......•.
arefgwueaa et—+ae wu a mdn 7tl o O ft n Idawss
tUSE ADDITIONAL EIKffn II NECE87ARY)
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