HomeMy WebLinkAboutGeological Assessment for FPA2017-00006 - FPA Reports - 9/20/2017 (6%12/2008) Michael MacSems -Geological Assessment Review Checklist 6-08.doc Page 1
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 refer the case to the Planning Manager or
Director.
Applicant's Name: !;
Permit# I`J* 2c,I — UC Parcel# ) Z?� Z cl — Y T UUC"'v
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: 3- Z
(2) (a)A discussion of the ground water conditions at the site,
OK? ! Comment: �. 3 . i
(b) A discussion of the estimated depth to water
OK? "' Comment: Z, 'a. j
(c) A discussion of the quantity of surf seepage
A OK?_ L_Comment: _a 13 . 1
(d) A discussion of the upslope geomorphology
OK?�L Comment: 7 _ Z. 1
(e) A discussion of location of upland waterbodies and wetlands.
OK? ✓ Comment: Z_ 3 1
(3) The approximate depth to hard or dense competent soil,e.g.glacial till or outwash sand.
OK? y Comment: 3, 3
(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 indjcating downslope movement,etc.).
OK? / Comment: s 0
(5) A discussion of the history of landslide activity in the vicinity,as available in the referenced
maps and records.
OK? V 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? I/ Comment:
(7) A recommendation by the preparer whether a Geotechnical Report should be required to
further ev luate site conditions and the proposed development of the subject property.
OK? Comment: 5_ 0
(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:
(a) the area of the proposed development,
OK? ✓ Comment: 4, i, 1
(b) the boundaries of the landslide hazard area (top, both sides, and toe),
Page 1 of 2 Form Effective June 2008
(6/12/2008) Michael MacSems-Geological Assessment Review Checklist 6-08.doc Page 2
OK? Comment: i /
(c) the associated buffers(top, both side ,and toe)
OK? ✓ Comment: N /
(d) building or other setbacks(top, both sides,and toe).
OK. 7 Comment: Al 2�.
(9) A site map drawn to scale showing property boundaries, scale, north arrow, and the
location aid nature of existing aAd proposed development on the site.
OK? f Comment: tp/)c--.od1i x
Are the Document(s)signed and stamped? \/ .
Type and#of License:_i� y-0V t\A ��o. tF 30 S
If not approved,what is the next action/recommendation for further action?
Reviewed by V V`'VV S ,onGt�
Time spent in review:
SECOND REVIEW/UPDATE:
Reviewed by on
Time spent in second review:
THIRD REVIEW/UPDATE:
Reviewed by on
Time spent in third review:
Disclaimer: Mason County does not certify the quality of the work done in this Geological
Assessment
Page 2 of 2 Form Effective June 2008
r--
Geological Assessment
(Revised)
Tree Harvesting
Cady Tree Farm, LLC
XXX NE State Route 3
Parcel No's 12329-41-00180, 12329-44-00000
Mason County, Washington
September 20, 2017
Project#1756
Prepared For:
Alan Cady
Cady Tree Farm, LLC CLYp
PO BOX 2022 'ASy ST9T
Belfair, Washington 98528
Prepared By: '
9/1 17
Envirotech Engineering �o k`Q ST ti� ��
PO Box 984 SlONAIJr
Belfair, Washington 98528
Phone: 360-275-9374
Mason County Department of Community Development
Submittal Checklist For a Geological Assessment
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 found to be not
applicable, the report should explain the basis for the conclusion.
Applicant/Owner Alan Cady Parcel# 12329-41-00180, 12329-41-00000
Site Address XXX NE State Route 3, Belfair
(1) A discussion of 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 the ground water conditions at the site,
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) 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.
Page 1 of 2 Form Effective June 2008
Located on page(s) 11
(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:
(a) the area of the 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) NIA
(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(app.A)
1, Michael C. 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 Sep. 20, 2017 , and entitled Tree Harvesting
Cady Tree Farm, LLC (Revised) meets all the requirements of the
Mason County Resource Ordinance, Landslide Hazard 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.
(Signature and Stamp)
C L1!\ S_
,{ 4304 s j
9/20/17
Disclaimer: Mason County does not certify the quality of the work done in this Geological
Assessment.
Page 2 of 2 Form Effective June 2008
Table of Contents
1.0 INTRODUCTION.................................................................................................................................I
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.................................................................................................7
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 TIMBER HARVESTING RECOMMENDATIONS...................................................................................10
5.0 CLOSURE............................................................................................................................................11
Appendix A-Site Plan
Appendix B-Soil Information
1.0 INTRODUCTION
Envirotech Engineering (Envirotech) has completed this geological assessment for a property
located at XXX NE State Route 3, identified as parcel numbers 1232941-00180 & 12329-44-
00000 in Mason County, Washington (Project). 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.
A geological assessment was prepared for this project in lieu of a geotechnical report. Per
17.01.100.E.2 of the Mason County Resource Ordinance (MCRO), the Director may waive the
requirement for the Geotechnical Report if there is adequate geological information available on
the area proposed for development to determine the impacts of the proposed development and
appropriate mitigating measures. This assessment covers land modification, and not future
development.
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 property owner's representative, and
observations from a field visit by Envirotech. The property is currently vacant with an un-
improved access road. The proposed site alterations are expected to consist of tree harvesting,
which has been conducted in the past on the property. Tree harvesting will be primarily confined
to the south and southeast portions of the property. Significant land disturbing such as stump
removal will be less than 1 acre, and significant earth movement (over 250 cy) is not expected.
Approximate site features are illustrated in the Site Map in Appendix A.
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 Project owner's representative;
• Conduct a site visit to document the site conditions that may influence the land
modification;
• 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 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
Envirotech Engineering Geological Assessment
Ph. 360-275-9374 page I Parcels 12329-41-00180, 1232944-00000
Mason County,Washington
September 20,2017
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 Project.
F i
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Vicinity Map from Mason County Website
Envirotech Engineering Geological Assessment
Ph. 360-275-9374 page 2 Parcels 12329-41-00180, 12329-44-00000
Mason County,Washington
September 20,2017
2.0 SURFACE CONDITIONS
Information pertaining to the existing surface conditions for the Project was gathered on April 17,
2017,and September 15, 2017 by Robert McNearny and Michael Staten with Envirotech.During
the site visit, site features were documented that may influence site alterations 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 Project is currently vacant land with few improvements as previously mentioned, and
surrounded by mixed development. State route 3 extends to the west of the project.Vegetation on
and near the property consists primarily of 2"d growth firs, alders, cedars, 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
Map in Appendix A for an illustration of the general slope indicators with respect to the planned
development.
Average slope grades are approximately 26%with a total vertical relief spanning both parcels of
approximately 260 feet. Although field measurements were less, public lidar indicates isolated
areas of sloping grades of up to 50%with vertical reliefs of less than 40 feet.
2.2.1 Upslope Geomorphology
The upland area of the property is situated on hillsides and crests. 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
Sheet flow on much of the properties is apparent, and directed to multiple un-named streams
crossing both parcels. Significant scour, erosion and sediment transport was confined to the
stream convergences only.
2.3.1 Upland Water Bodies
Except for the above mentioned streams, there are no large water bodies or wetlands
located upslope from the planned development that would significantly influence the
Project.
Envirotech Engineering Geological Assessment
Ph. 360-275-9374 page 3 Parcels 12329-41-00180, 12329-44-00000
Mason County,Washington
September 20,2017
2.4 Slope and Erosion Obser
vations
rvations
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.
10
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t
Aerial Photo from Google Website
Envirotech Engineering Geological Assessment
Ph. 360-275-9374 page 4 Parcels 12329-41-00180, 12329-44-00000
Mason County,Washington
September 20,2017
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 April 17, 2017 by Robert McNearny,
staff engineer 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
Ph.360-275-9374 page 5 Parcels 12329-41-00180, 12329-44-00000
Mason County,Washington
September 20,2017
Qqt Vashon till—Unsorted,unstratified(but locally banded)mix of clay. silt.
sand. and gravel: typically supported by a sandy matrix.mostly gray but
locally ranging to tan. light brown.or orange: typically unweathered:
lodgment till compact.With Well-developed facies resembling concrete.
but near the surface cormmonly hackly and(or) looser and covered by 1 to
6 ft of loose ablation till: deposited directly by glacial ice and commonly
includes casts or clumps plucked from underlying units. Clasts are
commonly striated and faceted.with angular or rounded edges. Boulders
are generally sparse Within the till but large(erratic)boulders of plutonic
or metamorphic rock are connnron on till surfaces. Some exposures include
interbands and lenses of sand and gravel.locally with shears and joints.
Till forms a locally patchy and seemingly randomly distributed cover up to
a several tens of feet thick. With a thickness of 5 to 20 ft most common. It
typically dominates. but is also locally discontinuous on. fluted surfaces.
with individual druurrinrs measuring 0.1 to 0.3 mi wide by 0.8 to 1.3 nu
long and the long axis aligned With the direction of ice flow. Till typically
is in sharp.unconforimable contact Aitll underlying units.most commonly
advance outWash(unit Qaa and subunit). Unit Qgt lies stratigraphically
below unit Qgo. It may include unrecognized exposures of older till.A
map boundary mismatch between unit Qgt on this map and unit Qgos on
the Vaughn quadrangle to the south (Logan and Walsh. 2047)may have
resulted from a map-production error in the northwest corner of the
Vaughn map(Josh Logan.Wash. Divn. of Geology and Earth Resources.
oral connnn.. 2009).
Vashon advance outuash—Pebble to cobble gravel. sand. and layers and
Qga lenses of silt and clay: gray to tau: typically stratified.Well rounded. Well
sorted. and clean(<50,'o silt or clay in matrix).except in less-sorted and
more angular ice-proximal deposits:compact(Fig. 4)and resistant to
erosion. except where Well sorted and well rounded.very thinly to very
thickly bedded: contains planar and graded beds. cut-arid-fill structures.
trough and ripple cross-beds. and foresets: thickness not Well constrained
by this mapping but ranges from a few feet to more than(?) 100 ft:
deposited as proglacial fluvial and deltaic sediment during Vaslron glacial
advance and typically overlain by uuiit Qgt along a sharp.unconformabhe
contact. Locally divided unto:
aaf Alluivial fan—Silt. sand. gravel. and boulders: typically poorly sorted and
stratified:forms concentric lobes where streams emerge from confuting
F-------1 valleys and reduced gradients cause sediment load to be deposited.
Envirotech Engineering Geological Assessment
Ph.360-275-9374 page 6 Parcels 12329-41-00180, 12329-44-00000
Mason County,Washington
September 20,2017
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 6 feet of natural ground were observed to be primarily moist, brown silty
sand with gravel (SM). Soils below the upper SM layer are expected to be an SM 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, Natural Resource Conservation Service (NRCS), the site soils are described as
Everett Very Gravelly Sandy Loam, Eh, 8% to 15% slopes,and Everett Very Gravelly Sandy
Loam, Ek, 15% to 30% slopes. See the soil map below and the applicable SCS soil profile in
Appendix B of this report.
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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 50 feet directly below the property. Surface seepage or perched groundwater at
shallow depths was not observed on-site,nor indicated on the well reports.
Envirotech Engineering g Geological Assessment
Ph.360-275-9374 page 7 Parcels 12329-41-00180, 12329-44-00000
Mason County,Washington
September 20,2017
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 project 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 site alterations, as provided in the Introduction Section of this report, it is
Envirotech's opinion that these site alterations 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. However, future building development on the
property should be required to be evaluated by a geotechnical engineer.
According to the Washington Interactive Geologic Map, Division of Geology and Earth
Resources-Washington's Geologic Survey, previous landslide activity recorded on and near the
property is a deep seated, dormant landslide. 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:
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Map from Washington State Department of Natural Resources Website
Envirotech Engineering Geological Assessment
Ph.360-275-9374 page 8 Parcels 1232941-00180, 12329-44-00000
Mason County,Washington
September 20,2017
4.1.1 Landslides and Slope Stability Analysis
Past landslide activity near the planned site alterations was revealed during the Project
research. This landslide is over 1500 feet to the east of the edge of property. The
landslide appears to be ancient,and is due to a combination of over-steepened terrain and
glacial retreat,and not similar to the existing and proposed conditions of this project site.
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.
Considering the planned site alterations 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
It is our opinion that standard and ordinary stream setbacks from the network of un-
named steams on both properties are sufficient for this project with relation to
geotechnical and geological hazards.
Due to the acreage of timber to be removed, we recommend that applicable re-planting
per County/State permitting is sufficient for this project.
If more than an acre of stumps are removed or future residential development is planned,
an engineered drainage and erosion control plan should be prepared 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
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. An erosion control plan is needed for this project if required by code or
sediments are observed to leave the site during timber harvesting. We also recommend an erosion
control plan if residential development is planned in the future.
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.
Envirotech Engineering Geological Assessment
Ph.360-275-9374 page 9 Parcels 12329-41-00180. 12329-44-00000
Mason County,Washington
September 20,2017
L
4.3 Seismic Hazards
There are no known faults beneath this Project. The nearest Class `A' or'B' fault to this property
is the Sunset Beach Scarp, Tacoma Fault Zone. This fault is a Class `A,` and is located
approximately 1 mile 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 very low to
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 Timber Harvesting Recommendations
The selective harvesting areas encompass the approximate area as shown in Appendix A of this
report. Although not a geotechnical constraint, the selective harvesting is expected to include
partial cutting by leaving all trees with a breast height diameter of less than 4 inches in place and
undisturbed.All trees left in place, and underbrush shall be minimally disturbed. Due to the small
and isolated areas where slopes exceed 40%, we do not recommend buffers or setbacks with
relation to slopes.
Conventional equipment such as skidders and crawlers may be used for this Project.Logs shall be
elevated on one end when dragging across the Project, although dragging should be minimized as
much as possible for this site. Timber harvesting causes a disturbance of a complex interaction
between water, soil and vegetation. Recommendations in this report are provided as a cost
efficient way to alleviate problems that may arise from this disturbance. Young trees should be
monitored and protected from competing vegetation. Permanent erosion control, drainage
facilities and slopes shall be immediately maintained as necessary. Some conditions that may
need immediate attention includes excessive erosion, scour, sloughing, significant changes to
drainage patterns, new springs, new seepages or isolated areas of ground saturation. Maintenance
may include curtain drains, swales, other drainage facilities, or slope remediation such as
reinforcement,retaining structures or surface protection.
Conclusions in this report are based on the type and location of the anticipated site alterations and
existing surface and subsurface conditions. Site work that significantly deviates from the
anticipated improvements presented in this report may require geotechnical design
recommendations.
Envirotech Engineering Geological Assessment
Ph.360-275-9374 page 10 Parcels 1232941-00180, 12329-44-00000
Mason County,Washington
September 20,2017
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.
However,future developments should require additional geotechnical studies.
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 site
modifications 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
Robert McNearny,E.I.T. Michael Staten,P.E.
Staff Engineer Geotechnical Engineer
Envirotech Engineering Geological Assessment
Ph.360-275-9374 page t 1 Parcels t2329-41-00180, 12329-44-00000
Mason County,Washington
September 20,2017
APPENDIX A
SITE PLAN
APPROXIMATE SILT FENCE
LOGGING LIMITS SCALE, 1'=300'
i121±
0 75150 300 600
60' VEGETATED 1
BUFFER (ASSUME
FROM STREAM
+i / x
I60' VEGETATED
BUFFER FROM 01
TOE OF SLOPE STREAM
EXCEEDING 40% UNNAMED`
STREAM o v v
s
EXISTING
TOP OF SLOPE EXISTING GRAVEL � BRIDGE
EXCEEDING 40% _ / DRIVEWAY., OVER STREAM
EXISTING CLEARED- TOE OF SLOPE
AREA FOR LANDING i EDING 40;
TF]P ❑F`SL❑PE
EXCEEDINC\40%
NOTE! BUILDING SETBACKS NOT 1326*TOP OF SLOPE — 610-
+
APPLICABLE FOR THIS PROJECT. EXCEEDING 40% TOE OF ❑PE
ZERO VEGETATION BUFFERS '�
RECOMMENDED � EXCEEDING 407
PROJECT/ OWNER/ LOCATIEft
LOGGING
NOTES- GEOTECHNICAL REPORT
1. CONTOURS WERE NOT PREPARED BY A LICENSED LAND SURVEYOR.
CONTOURS WERE EXTRAPOLATED FROM A PUBLIC LIDAR SOURCE, AND _ CADY TREE FARM,INCORPORATED FIELD MEASUREMENTS AS EXPLAINED IN THE GEOTECHNICAL XXX NE STATE ROUTTEE
3
REPORT. LEGEND PARCELS 12329-41-00180, 12329-44-00000
2. BOUNDARIES WERE NOT PREPARED BY A LICENSED SURVEYOR. LOCATIONS MASON COUNTY, WASHINGTON
OF SITE FEATURES THAT ARE SHOWN HERE, SUCH AS TOP OF SLOPES, TOE ENGINEER,
13F SLOPES, WATER FEATURES, ETC., WITH RELATION TO THE PROPERTY SLOPE INDICATOR ENVIROTECH ENGINEERING
LINES MUST BE VERIFIED BY THE OWNER, RECOMMENDATIONS IN THE PO BOX 984
GEOTECHNICAL REPORT PROVIDE SETBACKS, BUFFERS, DEPTHS, ETC. WITH EXISTING CONTOUR BELFAIR, WASHINGTON 98528
RELATION TO GEOLOGIC FEATURES, NOT PROPERTY LINES. THESE GEOLOGIC TP TEST PIT 360-275-9374
FEATURES MAY BE LOCATED ON THE SUBJECT PROPERTY OR NEIGHBORING
PROPERTIES SITE PLAN
APPENDIX B
SOIL INFORMATION
I
TEST PIT LOG
TEST PIT NUMBER TP-1
PROJECT: Cady Geotechnical Report DATE OF LOG: 4/17/2017
PROJECT NO: 1756 LOGGED BY: RJM
CLIENT: Alan Cady EXCAVATOR: N/A
LOCATION: Parcel 12329-41-00180, 12329-44-00000 DRILL RIG: None
Mason County, Washington ELEVATION: N/A
INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: N/A
STANDARD PENETRATION TEST
SOIL STRATA,
DEPTH SAMPLERS USCS DESCRIPTION ILL PI CURVE
AND TEST DATA DEPTH N 10 30 50
0
SM Brown, moist, loose to medium dense
SILTY SAND with GRAVEL. Gravel is
primarily well-graded and subangular.
1 Sand is mostly medium. Low plasticity.
r,
2 i
• i
3 I .I
4 s :�
t
5
6 Excavation terminated at approximately
6.0 feet
7
8
9
10
No Groundwater Encountered ENVIROTECH ENGINEERING
This information pertains only to this boring and should not be Geotechnical Engineering
interpreted as being indicitive of the entire site.
Map Unit Description:Everett very gravelly sandy loam. 15 to 30 percent slopes—Mason
County,Washington
Mason County, Washington
Ek—Everett very gravelly sandy loam, 15 to 30 percent
slopes
Map Unit Setting
National map unit symbol: 2t62c
Elevation: 30 to 900 feet
Mean annual precipitation: 35 to 91 inches
Mean annual air temperature: 48 to 52 degrees F
Frost-free period. 180 to 240 days
Farmland classification: Farmland of statewide importance
Map Unit Composition
Everett and similar soils: 80 percent
Minor components: 20 percent
Estimates are based on observations, descriptions, and transects of
the mapunit.
Description of Everett
Setting
Landform: Karnes, eskers, moraines
Landform position(two-dimensional): Backslope
Landform position (three-dimensional): Side slope
Down-slope shape: Convex
Across-slope shape: Convex
Parent material: Sandy and gravelly glacial outwash
Typical profile
Oi-0 to 1 inches: slightly decomposed plant material
A - 1 to 3 inches: very gravelly sandy loam
Bw-3 to 24 inches: very gravelly sandy loam
C1 -24 to 35 inches: very gravelly loamy sand
C2-35 to 60 inches: extremely cobbly coarse sand
Properties and qualities
Slope: 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
(1.98 to 5.95 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Available water storage in profile: Low(about 3.2 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated). 4e
Hydrologic Soil Group: A
t !;, Natural Resources Web Soil Survey 511 512 0 1 7
Conservation Service National Cooperative Soil Survey Page 1 of 2
Map Unit Description:Everett very gravelly sandy loam, 15 to 30 percent slopes--Mason
County,Washington
Other vegetative classification: Droughty Soils (G002XN402WA),
Droughty Soils (G002XS401 WA)
Hydric soil rating. No
Minor Components
Aiderwood
Percent of map unit: 10 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
Indianola
Percent of map unit: 10 percent
Landform: Eskers, kames, terraces
Landform position(two-dimensional): Backslope
Landform position(three-dimensional): Side slope
Down-slope shape: Linear
Across-slope shape: Linear
Hydric soil rating: No
Data Source Information
Soil Survey Area: Mason County, Washington
Survey Area Data: Version 12, Sep 9, 2016
Natural Resources Web Soil Survey 511 512 0 1 7
Conservation Service National Cooperative Soil Survey Page 2 of 2
�.i
L -
G
lQ
RESOURCE PROTECTION/GEOTECH SOIL BORING
WELL REPORT
N
Washington State Department of Ecology
O Original and t"copy—Ecology,2"'Copy—owner,3r°copy-driller
r
PROPOSED USE: /
l.0Consa•ucuun Current Notice of Intent No.
L IJ DecommissJon ORIGINAL J?VST-jL1_4710N1Votict a of Well
J02ri)'/ntr.rn.Vu,aber Type �I2tsouraPrutct:tion
C ❑Geotech Soil Boring
Consulting L'irm_fhp-w�-'( Unique Ecology Well ID Tag No. SaU 7
DRILLING METHOD WELL LOCATION
L
I lollow 11cm Auge, U Air Rotary Project Name IZEI rc..a-1 C2
�Nlud Ro"Iry Cl Dual Rotary Owner t4}e_r�—
17 Col', / ❑Other Well Add 1l�L
C Borehok:Diameter_ . City County_< Y1
Location /4 1/4 Sec aeTwn S R E o W
M. j ENT Tax Parcel No.
to have Ground Risei 6"s 3' 0 8"x 5' Suck up height ft Corutruction/Decotnmission Start Date AV
A*bw. 0 12" ❑Other Construction/Decommission Completed Date Q
aJ Arnotalt used Static Level
CASING INSTALLED CONSTRUCTION OR DECOMMISSION PROCEDURE
0 PVC XSch 40 CI Sch 80 fl inclinometer ❑Other Material or Formation From To
LI 7•hrcuded "Diameter from ft to ft I
11L.. Citucd ---�>Di ureter from
Ll Welded _"Diameter from ti to $
�... SCREEN W
Q 01PVC /._R Sch 40 rJ Sch go 0 Other
Z Diaultcter--I—Slot Size from _. to ft
11 Pre Puck Type 0 PVC ❑Sch 40 ❑'Sch 80 D Other _
Dtuuteter of inner screen "x Diameter of outer screen
C Slot Size _ Installed from ft to ft
fi stainless Steel "Diameter from ft to ft
pl 11 Uttter Diameter from ft to ft _
G SEAL ----
V Type or ntuterial toed )eBemouite Chips Amount
W
y,. '�t382ntonite Grout Amoun[r7,,�_
O 0 Portland Cement Amount -
C ❑Otther Amount.
Plu.ed frun,^�_ft t ft
SANDIGRAVEL PACK
Typr of nluterial usett*?'d Silica Sand Size ❑Pea Gravel
Q U Other
Placed tram k-&fl to M5511
— CO 0
Amount oftnaterial used pop
WELL CONSTRUCTION CERTIFICATION: I constructed and/or accept responsibility for construction of this well,and its compliance with all
Washinsnon well construction standards. Materials used and f.
the information reported above are true to my best knowledge and belie
f Driller Q Trainee N.urte(print) \vG Drilling Company Gregory Drilling,Inc. _
Driller:Trailtee Signature � IfTrautee,licensed driller's
Driller or Trainee License No._ 74y�_ Signature and License No. _ __
Mason County Department of Community Develoament
Submittal Checklist For a Geolonical Assessment
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 found to be not
applicable, the report should explain the basis for the conclusion.
Applicant/Owner Alan Cady parcel# 12329-41-00180, 1232941-00000
Site Address XXX NE State Route 3, Belfair
(1) A discussion of 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 the ground water conditions at the site,
Located on page(s) 8
(b) A discussion of the estimated depth to water
Located on page(s) 8
c) A discussion of the quantity of surface seepage
( q ty
Located on page(s) 8
(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) 3
(5) A discussion of the history of landslide activity in the vicinity, as available in the
referenced maps and records.
Located on page(s) 9
(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) 10
(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,
Page 1 of 2 Form Effective June 2008
Located on page(s) 1
(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:
(a) the area of the proposed development,
Located on Map(s) Site Plan
(b) the boundaries of the landslide hazard area(top, both sides, and toe),
Located on Map(s) Site Plan
(c) the associated buffers(top, both sides, and toe)
Located on Map(s) site Plan
(d) building or other setbacks(top, both sides,and toe).
Located on Map(s) Site Plan
(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(app.A)
I, Michael C. 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 15, 2017 , and entitled Tree Harvesting
Cady Tree Farm, LLC meets all the requirements of the
Mason County Resource Ordinance, Landslide Hazard 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.
(Signature and Stamp)
CLI
4304�
5/18/17
Disclaimer. Mason County does not certify the quality of the work done in this Geological
Assessment.
Page 2 of 2 Form Effective June 2008