HomeMy WebLinkAboutGEO2012-00004 for BLD2011-00993 - GEO Geological Review - 12/16/2011 Mason County Review Checklist GE
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: AW Al �.
Permit#: o2o/l_ 2 Parcel#'s: �33 �� �� T
el
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 f the ground water conditions at the site,
OK? Comment:
(b) A discussio f the estimated depth to water,
OK? Comment:
(c) A discussion of the quantity of surface seepage,
OK? V' Comment:
(d) A discussion of the upslope geomorphology,
OK? ✓ Comment:
(e) A discussion of location of upland waterbodies and wetlands.
OK? 1/ Comment:
3. The approximate depth to hard or dense competent soil, e.g. glacial till or outwash sand.
OK? I-' 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? 7 Comment:
5. A discussion of the history of landslide activity in the vicinity, as available in the referenced maps and records.
OK? 1--"' 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? ✓ 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? v1 Comment: A/ /c(
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
(a) the aZofeposed development,
OK? omment:
(b) the boundaries of the landslide hazard area (top, both sides, and toe),
V OK? Comment:
�p ( the associated buffers (top, both sides, and toe)
t OK? Comment:
(d) building or other setbacks (top, both sides, and toe).
OK? Comment:
9. A site map drawn to scale showing the property boundaries, scale, north arrow, and the location and nature of
existing and proposed development on the site.
OK? Comment:
Are the Documents signed and stamped? y 5 By whom?
License#: �(� License type:
FIRST REVIEW Approved ❑ Need more info.
If not approved, what is the next action/recommendation for further action?
Reviewed by lL� on ,7 Time spent in review: < ' y� �►+. --�
SECOND REVIEW/UPDATE ❑ Approved ❑ Need more info.
If not approved, what is the next action/recommendation for furt er ac 'on.
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
2/9/2012) Rebecca Hersha- Re: Mason Lake LLC Page 1
From: <envirotech@geotechnicalinfo.com>
To: "Rebecca Hersha" <RebeccaH@co.mason.wa.us>
Date: 2/8/2012 12:20 PM
Subject: Re: Mason Lake LLC
Hi Rebecca,
I've caused some grief for the homeowner with this line in the past. I
revised this in my reports, but not the assessments. I'll clarify it
better next time. For this project it is suppose to be an "or." My
intention is that an engineer is not needed during construction if the
report is followed, and soil conditions are just as I presented them (i.e.
no significant groundwater, no clay, no landfill, etc..) Since we are
suppose to provide a depth to competent bearing soil in the report, this
presents some unknowns for us. It is standard in our industry to look at
the bearing soils in one or two or three locations beneath the proposed
building, but there is always a possibility that there is soft clay or
buried garbage where we did not check. Also, there are occasions where the
owner decides to put the house in a different location that originally
planned. For the most part, soils are pretty consistent on a property, and
we can easily identify fill by looking at the ground surface.
I believe that the engineer should be called out to inspect footings if
the building requires over 2000 psf bearing, or the inspector finds soft,
saturated or susceptible soils.
Thank you,
Michael Staten
> Hello Michael,
> Thank you for the Geological Assessment prepared for Mason Lake LLC. It
> looks great, but I just need one minor clarification. On page 10 you
> stated "... it is recommended that a qualified engineer observes and
> documents the construction, or Envirotech is promptly notified if the
> project or subsurface conditions found on-site are not as presented in
> this report..."
> Did you mean for the"or"to be an "and?"
> Thank you.
> Rebecca Hersha, Planner
> Mason County DCD
> 360-427-9670 ext. 287
> P Go Green! Please consider the environment before printing this email or
> its attachments.
>
C�Eb 20 12-C,bao� RECEIVED
JAN 3 0 2012
426 W. CEDAR ST.
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 �19,1 ("k - Parcel# ZZ2/3 3 -S Z-y 006t
Site Address 27�'� /yam�^,� !mac„b� ur�lir L ,y� L,r� ?C dr e�✓
r
(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)
(2) (a)A discussion of the ground ater conditions at the site,
Located on page(s)
(b) A discussion of the estimated depth to water
Located on page(s) 6
(c) A discussion of the quanti of surface seepage
Located on page(s) E•
(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) The approximate depth to hard or dense competent soil,e.g.glacial till or outwash sand.
Located on page(s) S
(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) 7 0
(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.
Page 1 of 2 Form Effective June 2008
Located on page(s) 10
(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 d velopment,
Located on Map(s) �✓I/�
(b) the boundaries of the Ian tide hazard area(top,both sides,and toe),
Located on Maps)/)`
(c) the associated buffers(t911,both sides,and toe)
Located on Map(s) /V
(d) building or other setbacks,(top,both sides,and toe).
Located on Map(s) /V /r
(9) A site map drawn to scale showing the property boundaries,scale, north arrow,and the
location and nature of existin and Proposed development on the site.
Located on Map(s) S 6An_(A10n.4)
I, i L V1 • hereby certify under penalty
of perjury that I am a civil Ibngineer 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/� JUG �� Z'9IZ and entitled�G}�,i �•� LL(,
11je- �M I �i�per � I"l9/�W�� meets all the requirements of the
Masofi County Re ource 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)
�L CLYpE S
of WASy TI
J� C ,
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Fcis
�sS/CNAL.F�G`�
Disclaimer: Mason County does not certify the quality of the work done in this Geological
Assessment.
Page 2 of 2 Form Effective June 2008
• ED ?-O a - DDOv�
RECEIVED
OIL, ?�(d l - DD q 173 JAN 3 0 2012
426 W. CEDAR ST.
Geological Assessment
for
Mason Lake, LLC Single Family Residential Property
2741 E Mason Lake Drive East
Parcel No. 22233-52-00064
Mason County, Washington
January 16, 2012
Project#1103
Prepared For:
Mason Lake, LLC,
625 Windsor Drive SE PAL CLYpE s�
Sammamish, Washington 98074 ��� °� w ;'���c9�F�
0
Prepared By:
Envirotech Engineering 43045 'Z
PO Box 984 OAF�FQ-ISTf
Belfair, Washington 98528 SS�ONALV
Phone: 360-275-9374
Fax: 360-275-4789
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
2.21 Upslope Geomorphology and Upland Water Bodies.................................................................3
2.3 SURFACE DRAINAGE...........................................................................................................................3
2.4 SLOPE AND EROSION OBSERVATIONS................................................................................................3
3.0 SUBSURFACE INVESTIGATION......................................................................................................5
3.1 FIELD METHODS,SAMPLING AND FIELD TESTING............................................................................5
3.2 GEOLOGIC CONDITIONS.....................................................................................................................5
3.3 SPECIFIC SUBSURFACE CONDITIONS..................................................................................................5
3.3.1 Groundwater...............................................................................................................................6
4.0 ENGINEERING CONCLUSIONS.......................................................................................................7
4.1 LANDSLIDE HAZARDS.........................................................................................................................7
4.1.1 Landslides and Slope Stability Analysis.....................................................................................8
4.1.2 Surface and Subsurface Drainage.............................................................................................8
4.2 EROSION HAZARDS.............................................................................................................................8
4.3 SEISMIC HAZARDS..............................................................................................................................9
4.4 OTHER CONSIDERATIONS...................................................................................................................9
5.0 CLOSURE............................................................................................................................................10
Appendix A-Site Plan
Appendix B- Soil Information
1.0 INTRODUCTION
Envirotech Engineering (Envirotech) has completed this geological assessment for a residential
property located at 2741 E Mason Lake Drive East, identified as parcel number 22233 52 00064
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.
An initial geological/geotechnical evaluation of the Project was conducted by Envirotech without
the property owner or owner's representative on January 9, 2012. 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 property owner's representative, and
observations from a field visit by Envirotech. The property consists of a garage, paved driveway/
parking, and other ancillary developments. The proposed development is expected to consist of a
new single family residence and septic features. Approximate site development with relation to
existing 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 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 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 Project.
Envirotech Engineering Mason Lake, LLC Geological Assessment
Ph.360-275-9374 page 1 Parcel 22233-52-00064
Fax: 360-275-4789 Mason County,Washington
January 16,2012
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Vicinity Map from Mason County Website
Envirotech Engineering Mason Lake,LLC Geological Assessment
Ph.360-275-9374 page 2 Parcel 22233-52-00064
Fax:360-275-4789 Mason County,Washington
January 16,2012
2.0 SURFACE CONDITIONS
Information pertaining to the existing surface conditions for the Project was gathered on January
9, 2012 by Michael Staten, geotechnical engineer 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 Project is currently vacant land with few improvements as previously mentioned, and
surrounded by rural residential development. East Mason Lake Drive East extends along the
southeast side of the property, and Mason Lake is primarily adjacent to the northwest. Vegetation
on and near the property consists primarily of 2"d growth firs, huckleberry, 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
Map in Appendix A for an illustration of the general slope indicators with respect to the planned
development.
The new residence will be located on or near slopes exceeding 15%. These slopes average 21%,
with a vertical relief of nearly 15 feet, and the land is terraced with walls of less than 4 feet in
height.
2.2.1 Upslope Geomorphology and Upland Water Bodies
Ascending grades are generally located to the southeast 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 gentle sloping hillside to a
crest along the roadway. Additional geomorphology that is pertinent to both upslope and
downslope areas are provided in the Subsurface Investigation Section of this report.
Wetlands are located beyond the roadway, after the terrain descends. This water appears
to drain to the northeast,and not significantly influence the Project.
2.3 Surface Drainage
The majority of the stormwater runoff originating upslope from the anticipated development is
expected to be minimal. Significant scour, erosion and sediment transport was not apparent near
the Project.
2.4 Slope and Erosion Observations
The existing moderate slopes near the Project signal a potential landslide or erosion hazard area.
Envirotech Engineering Mason Lake,LLC Geological Assessment
Ph.360-275-9374 page 3 Parcel 22233-52-00064
Fax:360-2754789 Mason County, Washington
January 16,2012
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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2009 Aerial Photo from Mason County Website
Envirotech Engineering Mason Lake,LLC Geological Assessment
Ph.360-275-9374 page 4 Parcel 22233-52-00064
Fax:360-2754789 Mason County,Washington
January 16,2012
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 January 9, 2012 by Michael Staten,
geotechnical 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.
According to the "Geologic Map of the Mason Lake 7.5-minute Quadrangle, Mason County,
Washington" by Robert E. Derkey, et al, July 2009, the site soils are described as Vashon
advance outwash(Pleistocene),Qge,and provides the following caption:
Vashon advance outwash (Pleistocene)—Sand and gravel with lacustrine clay,silt,and sand;
Qga gray to light brown;compact;consists of sediment rich in northern-provenance clasts;well
rounded and most commonly well sorted;mostly polycrystalline quartz,plutonic,volcanic,and
minor metamorphic grains;deposited during Vashon glacial advance;generally more compact
than recessional outwash;most easily distinguished from recessional outwash if covered directly
by Vashon till;may also contain pre-Vashon sediment at its base.
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
Envirotech Engineering Mason Lake,LLC Geological Assessment
Ph.360-275-9374 page 5 Parcel 22233-52-00064
Fax: 360-275-4789 Mason County, Washington
January 16,2012
engineering properties of the soil, susceptibility for potential landslides, erosion and seismic
hazards may be assessed.
The Project is composed of native soils beneath an organic/ soil mixture of about 8 to 12 inches.
Competent bearing soils were encountered at 18 inches below the existing native ground surface.
However, existing retaining wall fill may be within foundation areas, and is not suitable for
bearing. For engineering purposes, these native soils consist of distinguishable layers, as
presented below.
Soils within the upper 4 feet of natural ground were observed to be moist, brown poorly graded
sand with gravel (SP). Soils from 4 to 5 feet below the ground surface were observed to be a
relatively impermeable silty clayey sand (SM-SC). This layer with variable amounts of sand and
clay are believed to extend to depths of at least 25 feet. This is based on nearby well reports, site
geology, and/ or knowledge of the general area. Expanded and specific subsurface descriptions,
other than what is provided in this section, are provided in the soil logs located in Appendix B of
this report.
According to the "Soil Survey of Mason County," by the United States Department of
Agriculture, Soil Conservation Service (SCS), the site soils are described as Alderwood gravelly
sandy loam, Ab,with 5%- 15% slopes. See the SCS soil profiles 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 at the building pad location. 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
relatively impermeable soils on occasion.
Envirotech Engineering Mason Lake, LLC Geological Assessment
Ph. 360-275-9374 page 6 Parcel 22233-52-00064
Fax: 360-275-4789 Mason County, Washington
January 16,2012
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, surface and subsurface
conditions as presented in 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.
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 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 Mason Lake, LLC Geological Assessment
Ph.360-275-9374 page 7 Parcel22233-52-00064
Fax: 360-2754789 Mason County, Washington
January 16,2012
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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. Therefore,a slope stability
analysis was not deemed necessary for this Project. Considering the planned construction
as summarized in the Introduction Section of this report; the aforementioned surface and
subsurface conditions for the Project; the slope stability assessment provided herein; and
the Engineering Conclusions provided later in this report, it is our opinion that the Project
is not within a landslide hazard area, and that the proposed site alterations will not
encourage a landslide hazard.
4.1.2 Surface and Subsurface Drainage
This project does not appear to experience significant subsurface drainage or surface
runoff. It is our opinion that groundwater or surface drainage is not a limiting factor for
this Project.
4.2 Erosion Hazards
Based on the USCS description of the Project soils, the surface soils are considered moderately
erodible. According to the Resource Map from the Washington State DNR, as provided above,
Envirotech Engineering Mason Lake,LLC Geological Assessment
Ph.360-275-9374 page 8 Parcel 22233-52-00064
Fax:360-2754789 Mason County,Washington
January 16,2012
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. 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 sit `
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 1.5 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 may require geotechnical design
recommendations.
Envirotech Engineering Mason Lake, LLC Geological Assessment
Ph. 360-275-9374 page 9 Parcel 22233-52-00064
Fax: 360-275-4789 Mason County, Washington
January 16,2012
5.0 CLOSURE
Based on the project information and site conditions as presented in this report, it is Envirotech's
opinion that additional geotechnical studies are not required to further evaluate this Project.
Due to the inherent natural variations of the soil stratification and the nature of the geotechnical
subsurface exploration, there is always a possibility that soil conditions encountered during
construction are different than those described in this report. Therefore, it is recommended that a
qualified engineer observes and documents the constmQtion, or Envirotech is promptly notified if
project and su su ace conditions found on-site are not as presented in this r_port so that we can
Te-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,
Envirote/ch EEngin�eering
1 fi �7�
Michael Staten, P.E.
Geotechnical Engineer
Envirotech Engineering Mason Lake, LLC Geological Assessment
Ph. 360-275-9374 page 10 Parcel 22233-52-00064
Fax:360-2754789 Mason County,Washington
January 16,2012
APPENDIX A
SITE PLAN
EXISTING 2' A
BLOCK
SCALE 1 INCH = 60 FEET
MASON BULKHEAD
LAKE 1� 0
c,
PR SED
H❑US APPRX)
O
EXISTING 3' F❑U ON
AND 3.5' PROBE
BLOCK WALLS,
CONCRETE
PATI❑,
EXISTING
PAVED
DRIVEWAY
EXISTING
GARAGE g�Tp
�T
TP1
9 q�
PROPOSED
DRAINFIELD
AREA
A, P5
PROPERTY LINE
PROJECT/ OWNER/ LOCATION,
SINGLE FAMILY PROPERTY
GE❑L❑GICAL ASSESSMENT
MASON LAKE, LLC
2741 E MASON LAKE DRIVE E
PARCEL 22233-52-00064
MASON COUNTY WASHINGTON
LEGEND ENGINEER,
ENVIROTECH ENGINEERING
SLOPE INDICATOR PO BOX 984
HELFAIR, WASHINGTON 98528
360-275-9374
TPI@ TEST PIT SITE PLAN
APPENDIX B
SOIL INFORMATION
Map Unit Description:Alderwood gravelly sandy loam,5 to 15 percent slopes—
Mason County,Washington
Mason County, Washington
Ab—Alderwood gravelly sandy loam, 5 to 15 percent slopes
Map Unit Setting
Elevation: 50 to 800 feet
Mean annual precipitation: 25 to 60 inches
Mean annual air temperature:48 to 52 degrees F
Frost-free period: 180 to 220 days
Map Unit Composition
Alderwood and similar soils: 100 percent
Description of Alderwood
Setting
Landform: Moraines
Parent material: Basal till with a component of volcanic ash
Properties and qualities
Slope: 5 to 15 percent
Depth to restrictive feature: 24 to 32 inches to dense material
Drainage class: Moderately well drained
Capacity of the most limiting layer to transmit water(Ksat):Very low
to moderately low (0.00 to 0.06 in/hr)
Depth to water table:About 18 to 36 inches
Frequency of flooding: None
Frequency of ponding: None
Available water capacity. Very low (about 2.5 inches)
Interpretive groups
Land capability(nonirrigated):4s
Typical profile
0 to 10 inches: Gravelly sandy loam
10 to 28 inches: Very gravelly sandy loam
28 to 60 inches: Gravelly sandy loam
Data Source Information
Soil Survey Area: Mason County, Washington
Survey Area Data: Version 6, Sep 22, 2009
USDA Natural Resources Web Soil Survey 1/12/2012
i1111111iil Conservation Service National Cooperative Soil Survey Page 1 of 1
TEST PIT LOG
TEST PIT NUMBER TP-1
PROJECT: SFR Geological Assessment DATE OF LOG: 01/9/2012
PROJECT NO: 1201 LOGGED BY: MCS
CLIENT: Mason Lake, LLC EXCAVATOR: N/A
LOCATION: Parcel 22233-52-00064 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
SP Brown, moist, medium dense POORLY
GRADED SAND with GRAVEL. Gravel is
fine and subrounded. Sand is primarily
1 coarse. Non plastic.
2
3
q . .. .. .. . . . . . .... .... . . . . .
SM-SC Brown, moist, dense SILTY CLAYEY
SAND with GRAVEL. Low to medium
plasticity. Silty clay pockets.
5 Dense sandy 'hardpan.'
Excavation terminated at approximately
5.0 feet
6
7
8
9
110
No Groundwater Encountered ENVIROTECH ENGINEERING
This information pertains only to this boring and should not be Geotechnical Engineering
interpreted as being indicitive of the entire site.
File Original end FirstCopy with WATER WELL REPORT Start c•`d"° 218314
f)♦pMnient of Ecology
'y
Second Copy—Owner's Copy . UNIQUE WELL I.D.ff
Third Copy—Drillers Copy STATE OF WASHINGTON
Water Right Parma No.
(1) OWNER: N...William Fletcher _ Address Olo n3agruAl c r 4]R
>< (2) LOCATION OF WELL: County Mason 34 __ T 22 2W
—�'A NW 1i Sea N..R W.M.
30t U M14S11H C L1 /ii/PdPL= r✓/E-r+LJ J.✓1F �t
(2e) STREET ADDDRESS OF WELL(or nearest address) &' /Q_[—� �_yl
1 (3) PROPOSED USE: ® Domestic Industrial El Municipal❑ (10) WELL LOG or ABANDONMENT PROCEDURE DESCRIPTION
r O Irrigation
• ❑ DoWater Test Well ❑ Other ❑ Formation: Describe by color. character, sire of material and structure• and show
1 thickness of o"d•rs and the kind and nature of the material in each stratum penetrated.
(4) TYPE OF WORK: Owne"s number of well with at Waal one entry for each change of Information.
(it more than one) -- MATERIALFROM To
Abandoned❑ New well 7K Method: Dug ❑ Bored ❑ _ - -- - — — -
Deepened ❑ Cable ® Driven ❑
Reconditioned ❑ Rotary❑ Jetted ❑ TODit with gravel 0 10
(6) DIMENSIONS: Diameter of well 6 inches.
= Drilled 155 feet. Depth of completed well 155 _--ft.. la with-gravel 10 so
(6) CONSTRUCTION DETAILS: Blue la with P-ravel & water ... 90 125
Casing Installed: 6 Diam.from 0 it.to 150 ft _
Welded 7�3 Diem.from ft.to ft. Grayclaywith ravel & water 125 150
Liner installed❑
TMeoded El Dism.from ft.to ft.
Perforatfons: Yee No Siand gravel-vith 150._ 155
Type of perforator used
f SIZE of perforations in.by In.
perforations from_—._ ft.to ft.
perforations from ft.to ft.
perforations from ft.to M.
Schenk!: Yee 19 No
Manutacturei a Name f o t c t n(t
Type stainless wire wrap _ Model No.
+ Diam. 5"---- Slot size_ 30 —from 150 h.to 155 ft.
+ Diam. Slot size—from—ft.to ft.
Y Gravel packed: Yea No 1A Size of gravel—_—
= Gravel placed from ft.to tl.
■
• Surface teal: Yes® No❑ To what depth? 18 ft.
Material used In**at Beton7 to
Did any strata contain unusable water? Yes❑ No® _
s
Type of water? Depth of strata '—
Method of sealing*testa off
(7) PUMP: Manufacturer's Name GnindfoS
s sub.
h TYPO: H.P.
11 (8) WATER LEVELS: abnovvesmeann elevation"l ft.
' Static level A 5 11.below top of well Data
Artesian pressure ___lbs.per square inch Dale
Artesian water is controlled by
.heirs,arc.
Work started 19. Completed
(9) WELL TESTS: Drawdnwn la amovnt water level is towered below stalk:level tg_
Was a pump test msde?Yes r_.- No® If ye*,by whom?
WELL CONSTRUCTOR CERTIFICATION:
_ Yield: J gal./min.with ft.deswdownafter hre.
I constructed and/or accept responsibility for construction of this well,
and its compliance with all Washington well construction standards.
+ _ _ _ _ Materials used and the information reported above ore true to my best
S Racovry data(lima takon as zero who pump turned oft)(water level measured knowledge and belief.
Z from well top to water level)
Time water Level Time wider Level Tres! widert.wel
� NAME Davis Drilling
(PERSON.FIRM.OR COPPORATION) (TYPE OR PRINT)
Address
Belfair WA 98528
: ______ -
Oat a of leaf
(Signed)_ "Cx _/ a License No-_ 1886
Bailm toot 10 gel_/min.with 8 ft.deswdown after 1 Ives. tv GRILLER)
Contractor's
Airiest gal.i min.with slew set at ft.for hro.
Artesian flow pp.m. Dale Neogia) W4SDTa100A Data June tg93
Temperature of water_Was a chemical analysis mode?Yee❑ Noll (USE ADDITIONAL SHEETS IF NECESSARY)
ECYG6o-1.20 (10187) -1329 i9•K%•';ic•Y.
File Ortpind and Flrsi Copy pith 91yrt card tie. V'�'Q ( �a f�
DeperbvwntofEcology WATER WELL REPORT UNIOMWULt).t�-
pond CapY 0wTw s Copy
STATE OF WASHiNGTON
Third Copy—Drillw's Copy tighter Right Penh No.---- _
(1) OWNER: Namery u /0
L
i ( LocATION OF wELL: Carry • C Sstx 1N sec 3 T ;�LN.R wa<
// 1
(2s) STREET ADDRESS OF WELL(orneere'sfalxiresey 1t t� .[5 ell (a'_ Dr. '4 <xe XX I-1
j � -
' (3) PROPOSED USE. Domestk I p .-,}. �r O (10) WELL LOG or ABANDONMENT PROCEDURE DESCRIPTION
■ ❑ Irrig anon❑ Dewater CAS fn i l " ❑ Formatwr DesaZe by&*Y.cttuarser,ske of material and Mire,and sttoteitlicAness of aquifers
r}ii ( G S and ft WA and nahae of lne material to sect,mf vi,peneb-.rted,*%at►sett one entry for each
j (4) TYPE OF WORK: Owner's number of well drange of"onnasbn.
(If more tt,an one)
Abandoned❑ Newwefl �( Method: Dug❑ Borod El MATERIAL m
Deepened ❑ Cab�&K Dtirren0 I
Rawndtianod El Rotary❑ Jetmd ElS-QL_ RR
i (5) DIMENSIONS: Dwnetor of weR Inches. L�l G
= Dolled _feet Depot of cwnpleied wel i��.�' ft. C r.Ig-
(6) CONSTRUCTION DETAILS: A —T
CoWng ktstoned: 6 ' Dorm.from / ft.to R. aC
Welded 9 Diam.Rom tL to R
Liner installed❑
Threadod ❑ Mam.from —ft.to R. +
+ perrorotlons: Yen No❑
Type of perforaln read
j SIZE of perforations In.by fri
_ portorotions from ft.to R.
pedonr&x s from ft Io R.
+ pedoratiorrs from ft.tD ft.
Screens: YeqA No❑
Mamrfect+rrerb Name _ /I.Cko K
j Type 65 Model W.g��i 'T
Diem. slot size
+ Dlarn. Slot shze from ft.to-ft.
SGravel pecked: Yes ❑ No 1K size of gravel
= Gravel placed from ft.to n OW UNIT
■ Sutfaee Seel: Yes 5? No❑ To wtW depth?—!—jj ft-
Material used in seal
r
Did any strata Contain un usable water? Yes❑ No
Type of water? Depth or 6trata
Method of sealing strata off
)
: (7) PUMP: MarAacturer'sNpme
Type: H.['
D
(8) WATER LEVELS: Land-su"amafevatiom WohlrShrhed TM t9 cnrmgleted /N 1�.� t9
above mean sea haves
Stack level � � It.below top cf we7 Date
Artes*n pressure lbs.per square rndh Data WELL CONSTRUCTOR CERTIFICATION:
Artestan water incontroledby I constructed andlor atxept responsibilfty for consnciKn of this well, and its
jr,ap w - compliance with all Washington well rAmstniction standard&Materials used and
+ (9) WELL TESTS: Drawdawn is amount water level is lowered below stark level the information reported above are true to my best knowledge arid ballet.
Was a pump Lost mado?Yos❑ No F- If yes,by whom?
NAME
Yield: gaUmin-with ft.drawdownaRer hf5. RwoIRCORPORPrr (TYPE ori PF*A�' --
Addrm �� e-16Arfjdz 11f144 Al e-14 ,
L .. / ay e
1 Vmcovwy data(tlrne takers as zero when pump turned of)(wabr level measurod frorn wen (signed) 2 L� LfCertSe t}
JC
top to water krvei)
Time water Level Time water Level Time Water Level Contractors
rJeorahen hale
L I
tlaa of heel (USE ADDITIONAL SHEETS IF NECESSARY)
Bailer Gast peL/min.with- �_ft.drawdown aftor Z� tars.
Airtost gal./min.with stem set at IL for his. Ecology Is an Equal Opportunity and Aifirmetive Action employer.For spe-
Artesian flow g p.m. Date- cial accommodation needs,contact the Water Resources Program at(20s)
Temperature of water Was a c hernlrml analysis made? Yes❑ No[RI 407-6600.The TDD number ir,(206)407-6006.
ECYOSat-20I%gl$ '1