HomeMy WebLinkAboutBLD2022-00003 SFR - BLD Engineering / Geo-tech Reports - 6/12/2008 RECEIVED
JAN 0 3 2022
615 W. Alder Street
Geotechnical Report
for
Knudsen Tracts Single Family Residences
East Sherwood Creek Road
Parcels 12220 33 00210, 12229 22 00320, 12220 33 90221,
12220 33 90222912220 33 90223 & 12220 33 90224
Mason County, Washington
June 12, 2008
Project#0857
Prepared For:
Jack Johnson Construction, Inc.
PO Box 1119
Belfair, Washington 98528
Prepared By
Envirotech Engineering
PO Box 984
Belfair, Washington 98528
Phone: 360-275-9374
6/12/08
TABLE OF CONTENTS
1.0 INTRODUCTION»..»»»»»»»»»»»»»»»......»»»..»....»»..........»....»»»»..»....»»..»..»»....»»..»»».........1
1.1 PROJECT INFORMATION.................................................................................................................... 1
1.2 PURPOSE OF INVESTIGATION............................................................................................................. 1
1.3 SCOPE OF WORK................................................................................................................................ 1
2.0 SURFACE CONDITIONS.....»»»....»..»..»....»..»»..»....»»..»..»»»»»»»..»..»»»..»..»»»....»»...............3
2.1 GENERAL OBSERVATIONS..................................................................................................................3
2.2 TOPOGRAPHY.....................................................................................................................................3
2.2.1 Upslope Geomorphology............................................................................................................3
2.2.2 Downslope Geomorphology.......................................................................................................3
2.3 SURFACE DRAINAGE..........................................................................................................................3
2.4 SLOPE AND EROSION OBSERVATIONS...............................................................................................4
3.0 SUBSURFACE INVESTIGATION»»»»»»»»»»»»»»»..»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»»....».5
3.1 FIELD METHODS,SAMPLING AND FIELD TESTING...........................................................................5
3.2 GENERAL GEOLOGIC CONDITIONS.........................•--•---.........................................................•.........5
3.3 SPECIFIC SUBSURFACE CONDITIONS.................................................................................................6
3.3.1 Groundwater................................................................•-------.......................................................6
3.4 SOUS TESTING................................................................................................................................... 6
4.0 ENGINEERING ANALYSIS,CONCLUSIONS AND RECOMMENDATIONS»..»....»»............8
4.1 BUILDING FOUNDATION RECOMMENDATIONS.................................................................................. 8
4.1.1 Bearing Capacity........................................................................................................................ 8
4.1.2 Settlement...................................................................................................................................8
4.1.3 Concrete Slabs-on-Grade........................................................................................................... 9
4.2 LATERAL EARTH PRESSURES...................................................•---..................................................... 9
4.3 EARTHWORK CONSTRUCTION RECOMMENDATIONS........................................................................9
4.3.1 Excavation....................................•-••---•--...................------------...............................--...................10
4.3.2 Placement and Compaction of Native Soils and Engineered Fill..................... ......10
4.3.3 Retaining Wall Backfill.............................................................................................................11
4.3.4 Wet Weather Considerations.................................................................•---•--............................11
4.3.5 Building Pads............................................................................................................................11
4.4 SLOPE STABILITY AND EROSION CONTROL.....................................................................................11
4.4.1 Septic Drainfield Impacts.........................................................................................................16
4.4.2 Building and Footing Setbacks.................................................................................................16
4.4.3 Temporary and Permanent Erosion Control...........................................................................16
4.4.4 Surface and Subsurface Drainage...........................................................................................17
4.4.5 Vegetation Considerations........................................................................................................17
4.4.6 Off-site impacts........................................................................................................•---...---.......18
4.5 SEISMIC CONSIDERATIONS AND LIQUEFACTION..............................................................................18
5.0 CLOSURE.......»..»........»»»»»»»..»»....»......»..»»..»..»»..»..»»»..». ...»..»......19
Appendix A-Site Plan
Appendix B—Geological Map
Appendix C-Soil Information
Appendix D-Slope Stability
Appendix E—Erosion Control
Appendix F—Drainage Details
1.0 INTRODUCTION
Envirotech Engineering(Envirotech)has completed a geotechnical investigation for a future nine
lot subdivision on parcel numbers 12220 33 00210, 12229 22 00320, 12220 33 90221, 12220 33
90222. 12220 33 90223, and 12220 33 90224, Mason County, Washington (Project). As
presented herein, this report 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 soil descriptions in the Subsurface Investigation Section; and.
recommendations for foundation, settlement, earthwork construction, lateral earth pressures.
slope stability, erosion control, drainage and vegetation considerations in the Engineering
Analysis and Recommendations Section.
An initial geotechnical evaluation of the Project was conducted by Envirotech with the property
owner,Jack Johnson,on May 9, 2008. It was previously determined that slopes in excess of 40%
with a vertical relief of at least 10 feet were present within 300 feet of the planned development.
Consequently, the proposed development will require a geotechnical report pursuant to Landslide
Hazard Areas of Mason County Resource Ordinance 17.01.100. During the site visit by
Envirotech, surface and subsurface conditions were assessed. After completion of the field work
and applicable Project research, Envirotech prepared this geotechnical report.
1.1 Project Information
Information pertaining to the Project was provided by the property owner and owner's
representative with general assumptions by Envirotech that are typical of this type of
development. The Project is accessed from an unimproved road linking Sherwood Creek Road.
See the vicinity map on the following page of this report for a general location of the site. The
property is currently vacant land with a dirt road accessing all the planned lots, and one well
head. The planned development consists of I- or 2-story single family residences on each lot.
Foundation construction is expected to consist of continuous strip footings and concrete slab-on-
grade or stem walls. Anticipated construction other than the residence will include driveways,
stormwater management systems, and possible ancillary features typical of this type of
development. Septic drainfields are not anticipated for this Project. Earth movement consisting of
cutting high areas and filling the low portion of undulations is expected. Approximate building
footprint with relation to site features are illustrated in the Site Map in Appendix A.
1.2 Purpose of Investigation
The purpose of this geotechnical investigation was to evaluate the Project in order to provide
geotechnical recommendations relating to the development of the property. The investigation
included characterizing the general Project surface and subsurface conditions, and evaluating the
suitability of the soils to support the planned site activities.
1.3 Scope of Work
In order to fulfill the purpose of investigation, the geotechnical program completed for the
proposed improvements of the Project include:
• Review project information provided by the Project owner and/ or owner's
Envirotech Engineering Geotechnical Investigation
PO Box 984 na_e 1 Knudsen Tracts
Belfair,Washington 98528 Mason County.Washington
Ph. 360-275-9374 June 12.2008
representative. This included a grading and stormwater management plan completed by
Michael Wnek.P.E.;
• Conduct a site visit to document the site conditions that may influence the construction
and performance of the proposed improvements;
• Define the general subsurface conditions of the site by observing subsoils extending to a
depth of up to 35 feet below the natural ground surface, review geological maps for the
general area, research published references concerning slope stability, and review water
well reports from existing wells near the Project;
• Collect bulk samples at various depths and locations;
• Perform soils testing to determine selected index properties of the soils that include 8
visual classifications,2 in-place density tests, and one direct shear test;
• Complete an engineering analysis supported by the planned site alterations, and the
surface and subsurface conditions that were identified by the field investigation, soil
testing,and applicable project research;and,
• Establish conclusions based on findings, and make recommendations for foundations,
drainage, slope stability, erosion control, earthwork construction requirements. and other
considerations.
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Vicinity Map from Mason County Websire
Envirotech Engineering Geotechnical Investigation
PO Box 984 page 2 Knudsen Tracts
Belfair,Washington 98528 Mason County.Washington
Ph. 360-275-9374 June 12.2008
2.0 SURFACE CONDITIONS
Information pertaining to the existing surface conditions for the Project was gathered on May 9,
May 16, and May 24, 2008 by Michael Staten,geotechnical engineer with Envirotech. During the
site visits,the type of geotechnical investigation was assessed. site features were documented that
may influence construction and slope stability, soil samples were collected from selected
locations. and near-surface soils were visually classified. This Surface Conditions Section
provides information on general observations, vegetation, topography, drainage and slope/
erosion conditions for the Project and surrounding areas that may impact the Project.
2.1 General Observations
The Project is currently vacant land as previously mentioned. Sherwood Creek Road borders the
southeast portion of the property,and a residential subdivision is located to the north and west of
the property. Beyond the property lines, exist low to moderate density residential development.
Vegetation on and near the Project consists primarily of firs,alders,maples,blackberry, and other
trees and shrubbery common to this area of the Pacific Northwest. Past clearing has been
completed for this property. An aerial photo of the project and immediate vicinity is provided on
the following page.
2.2 Topography
The Project is situated within and near moderate to very steep sloping terrain. The topographic
information provided in this section was extrapolated from a public lidar source,and incorporated
observations and field measurements. Slope verification included measuring slope lengths and
inclinations with a cloth tape and clinometer. See the Site Map in Appendix A and the Geological
Map in Appendix B in this report for an illustration of general topography with respect to the
planned development.
2.2.1 Upslope Geomorphology
Ascending grades are located to the north and west of the planned development. These
slopes are extremely variable, with undulations and vertical reliefs ranging from 10 to 40
feet from the property line. There are no apparent water bodies or wetlands located
upslope from the planned development.
2.2.2 Downslope Geomorphology
Descending grades also vary considerably, and are limited to a vertical relief of no more
than 130 feet of slopes exceeding 40%. Some isolated areas with vertical reliefs of less
than 25 feet were observed to have slopes greater than 100%. See the Site Plan and
Geologic Map in the appendices of this report.
2.3 Surface Drainage
Stormwater runoff originating upslope from the anticipated development is expected to be
minimal. Sheet flow down the sloping grades towards the planned development is expected. Most
of the upslope runoff appears to be diverted away from the property due to the upslope
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Belfair.Washington 98528 Mason Countv.Washington
Ph. 360-275-9374 June 12.2008
development. Sheet flow down the steeper slopes can be expected, with some minor
convergences. Excessive scour, erosion or other indications of past drainage problems were not
observed at or near the planned development. It is apparent that the upslope development
manages most of its stormwater,and distributes runoff without impacting the Project.
2.4 Slope and Erosion Observations
The existing steep 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.
Significant mass wasting on the property was observed. Indications of recent and past landslides
were apparent on the very steep descending slopes. The landslides were limited to shallow
translational failures extending to depths of almost 2 feet.The slides did not exceed a length of 30
feet at the bottom failure surface, and had widths of less than 15 feet. Indications of deep seated
slope problems were not apparent or observed during the site visit.
17
3.0 SUBSURFACE INVESTIGATION
Information on subsurface conditions pertaining to the Project was gathered on May 16, and May
24, 2008 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 C of this report includes pertinent information on
subsurface conditions for the Project, such as subsoil cross-sections, test pit log(s) representative
of the bearing soils of the planned building, and water well report(s). Applicable test pit and well
log locations are depicted on the Site Plan and Geologic Map provided in the appendix of this
report.
3.1 Field Methods,Sampling and Field Testing
Information on subsurface conditions for the Project was accomplished by examining soils within
test pits extending to depths of up to 15 feet below the existing ground surface, observing soils
within existing cuts on the slope of up to approximately 35 feet below the natural ground surface,
and observing soils within the shallow landslides. Information on subsurface conditions also
included reviewing geological maps and water well reports originating from nearby properties.
Bulk samples were collected at the Project site ranging from approximately 2 feet to 15 feet
below the existing ground surface. A bulk sample was transported to PSI laboratory for direct
shear testing. An additional sample was obtained by driving brass rings into the sandy clay soils
exposed at the landslide. The soil samples collected were secured and transported for laboratory
testing.
From a sand cone test.Envirotech measured the relative density of the upper soils,at a depth of 1-
foot below the existing grade. Relative density was also measured from the exposed sandy clay
soils from the aforementioned slide by measuring the unit weight from brass rings. Relative
density was also gauged from observing the excavations performed by a John Deere 16OLC
backhoe. See the soils testing section below for specific testing results.
3.2 General 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, Q,,. 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 Washington—Northwest Quadrant" (2002), the site geology
is composed of both glacial till (Q_,,) and advance outwash (QgJ. The glacial till is primarily
located in the upper portion of the property such as the building areas,and the advance outwash is
shown to be within the lower site geology.
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Glacial till, %t, is unsorted, unstratified, highly compacted mixture of clay, silt, sand, gravel, and
boulders deposited by glacial ice;may contain interbedded stratified sand,silt,and gravel.
Advance outwash. Q., is glaciofluvial sand and gravel and lacustrine clay, silt, and sand
deposited during the advance of glaciers; sandy units commonly thick, well sorted, and fine
grained, with interlayered coarser sand, gravel, and cobbles;locally contains nonglacial sediments
and deposits mapped as transitional between glacial and nonglacial.
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 composed of native soils with no indications of borrowed fill. For engineering
purposes,these native soils consist of distinguishable layers,as presented below.
Soils within the upper 15 feet of natural ground were observed to be moist, brown and grey sitly
sand (SM) with traces of gravel, cobbles and boulders. This soil description generally includes
gravel in the upper 18 inches from the ground surface. Sand content was primarily well graded
near the surface, and significant fine sands at depths of over 10 feet. The fines content exhibited
low plasticity with small layers of medium plasticity. Weak to moderate cementation was
observed throughout test pit 1, and the upper 12 feet of test pit 2.
According to the well report soils below the upper 20 feet soil layer consists of brown sandy clay
(SC), which extends to a depth of 80 feet below the ground surface. This soil was verified at the
face of the recent landside located near the slope toe on Lot 5.
3.3.1 Groundwater
From the water well report and knowledge of the general area,permanent groundwater is
approximately 150 feet directly below the property at an elevation of about 100 feet
above sea level. Perched groundwater at shallow depths was not observed on-site. nor
indicated on the well reports. Seepage during wet weather was apparent near the toe of
the steep slopes on Lots 4 and 5.
3.4 Soils Testing
The soil samples obtained at the Project site during the field investigation were preserved and
transported for possible laboratory testing. Visual classification of soils was performed in the
field. The following soil tests were performed in accordance with the American Standards for
Testing and Materials(ASTM):
8 Visual Classifications(ASTM D2488);
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Belfair.Washington 98528 Mason County.Washington
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I Sand cone test(ASTM D1556);
1 Brass ring unit weight test;and,
1 Direct Shear(ASTM D3080).
The results from the visual classification are presented above in the Subsurface Conditions
Section at depths of up to 35 feet below the natural ground surface. Specifically, upper sandy
soils consisted of approximately 30% gravel. 50% sand-sized soils. and 20% silt. Variations
included as a silt content ranging from 10% to 25%, and gravel content of less than 5%. The
underlying clayey soils consisted of approximately 0% gravel, 35% sand, and 65% medium
plastic clay.
A sand cone test, completed by Envirotech was performed near test pit 1. This test indicated that
near surface dense, low to moderately cemented soils had a moisture content of 8.1%, and a dry
density of 128.1 pcf.
One unit weight test was performed by Envirotech by measuring the soils within brass rings that
were driven in the exposed clayey strata.This test indicated an in-situ density of 142.2 pcf.
Direct shear testing of the weakest substructure was performed by HWA Geosciences. Inc., via
PSI. The direct shear test was prepared by remolding the minus No. 4 material to a dry unit
weight of approximately 110 pcf, and a moisture content of about 10%. Three shear trials were
run at normal stresses of 2.0. 4.0 and 8.0 ksf. The apparent strength parameters from the direct
shear test indicated soil cohesion of 70 psf,and an angle of internal friction of 32.8 degrees.
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4.0 ENGINEERING ANALYSIS.CONCLUSIONS AND RECOMMENDATIONS
The following sections present engineering analysis and recommendations for the proposed
improvements of the Project. These recommendations have been made available based on the
planned improvements as outlined in the Introduction Section of this report; general observations,
including drainage and topography as recapitulated in the Surface Conditions Section; and. soil
conditions that were identified from the geotechnical investigation that is summarized in the
Subsurface Investigation Section. Engineering analysis and recommendations for the Project that
is provided herein, includes pertinent information for building foundations, earthwork
construction, slope stability/erosion control,drainage,vegetation and seismic considerations.
4.1 Building Foundation Recommendations
Recommendations provided in this section account for the site development of a typical one- or
two-story, single family residential structure. Below the upper 12 inches of Project soils, there is
apparently one distinguishable layers of soil that will influence the bearing capacity and
settlement of the structures. The recommended allowable bearing capacities and settlements as
presented below, consider the probable type of construction as well as the field investigation
results by implementing practical engineering judgment within published engineering standards.
Evaluations include classifying site soils, and deriving probable relative densities, unit weights
and angles of internal friction of the in-situ soils based on observed field conditions and soil
testing for this Project.
The frost penetration depth is not expected to extend beyond 12 inches below the ground surface
for this Project under normal circumstances and anticipated design features. The soils on-site
have moderate frost susceptible characteristics and should be used only to the extents provided in
this report.
4.1.1 Bearing Capacity
For the existing site conditions, bearing values should increase with depth. Existing in-
situ soils for this Project indicates that the structure can be established on shallow.
continuous or isolated footings. Foundations shall be established on relatively
undisturbed native soil. Alternatively, foundations may be constructed on selective re-
compacted native soil or compacted engineered fill as described in the Earthwork
Construction Recommendations Section of this report. Footing width and depth
recommendations shall be adhered to, and are based on 1500 pounds per square feet(psf)
maximum structural bearing pressure.
For a bearing capacity requirement of no more than 1500 psf, a minimum footing width
of 15 inches shall be placed at a minimum of 18 inches below the existing ground
surface. Foundation recommendations are made available based on adherence to the
remaining recommendations that are provided in this report. For foundations placed in
building pads consisting of engineered fill, 12-inch footings may be used at a depth of 12
inches below the final ground surface.
4.1.2 Settlement
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Total and differential settlement that a structure will undergo depends primarily on the
subsurface conditions, type of structure, amount and duration of pressure exerted by the
structure. reduction of pore water pressure, and in some instances, the infiltration of free
moisture. Based on the expected native soil conditions, anticipated development. and
construction abides by the recommendations in this report, the assumed foundation
system may undergo a maximum of 1.0 inch total settlement,and a maximum differential
settlement of 0.75 inch.
4.13 Concrete Slahs-on-Grade
Interior slabs, if utilized, should be supported on a minimum of 6 inches of compacted
coarse, granular material that is placed over undisturbed native subgrade or engineered
fill. Native soils found at the Project site are not suitable for use as the material directly
beneath concrete slabs. The top 4 to 12 inches of native soil should be removed prior to
the placement and compaction of the aforementioned 6-inch coarse, granular material.
Although not required for the structural integrity of the concrete slab-on-grade, a vapor
barrier is usually used for damp-proofing. If vapor barriers are used, it is suggested to
utilize a barrier that is sufficiently thick to resist puncturing during construction, or place
a 2 inch layer of sand above the barrier prior to placing the concrete slab.
4.2 Lateral Earth Pressures
Retaining walls may be utilized for this Project. The lateral earth pressures exerted through the
backfill of a retaining wall are dependent upon several factors including height of retained soil
behind the wall, type of soil that is retained, degree of backfill compaction, slope of backfill.
surcharges,hydrostatic pressures,earthquake pressures,and the direction and distance that the top
of the wall moves.
An equivalent fluid unit weight used for structural design may be estimated as the product of the
backfill soil unit weight and the earth pressure coefficient for at-rest pressures. Retaining walls
should be designed to resist a lateral earth pressure based on an equivalent fluid unit weight of 45
pounds per cubic foot (pcf) and 60 pcf for backfill consisting of engineered fill and native soils.
respectively. See the Earthwork Construction Recommendations Section for details concerning
the use of native soils,engineered fill and placement of backfill.
Lateral earth pressure recommendations are based on retaining structures with relatively flat or
descending sloping backfill, and the backfill conforming to the recommendations outlined in the
Earthwork Construction Recommendations Section of this report. For instances when it is
necessary to require ascending sloping backfill or structures will induce passive earth pressures,
additional design parameters must be accounted for in the retaining wall analysis.For these cases,
recommendations should only be provided by a qualified engineer after the type of backfill is
specified,inclination of backfill slope is estimated,and the final wall height is determined.
4.3 Earthwork Construction Recommendations
Founding material for building foundations shall consist of undisturbed native soils. Compacted
engineered fill, or selective re-compacted native soils may be used to the extents provided in this
Earthwork Construction Recommendations Section. The following recommendations include
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excavations, subgrade preparation,type of fill, and placement of fill for building foundations.
4.3.1 Excavation
Excavation is recommended to remove any excessive organic content or other deleterious
material, if present, beneath foundations and to achieve appropriate foundation depth.
Additional sub-excavation will be required for this Project if the soils below the required
foundation depth are loose, saturated, or otherwise incompetent due to inappropriate land
disturbing, or excessive water trapped within foundation excavations prior to foundation
construction. All soils below the bottom of the excavation shall be competent, and
relatively undisturbed or properly compacted fill. If these soils are disturbed or deemed
incompetent, re-compaction of these soils below the anticipated footing depth is
necessary. Excavations shall be completely dewatered, compacted, and suitable before
placement of additional native soil, engineered fill or structural concrete. It is suggested
that foundation excavations are inspected by a geotechnical engineer or qualified
professional in order to assess the bearing material prior to the placement of structural
footings.
4.3.2 Placement and Compaction of Native Soils and Engineered FIR
For engineered fill or disturbed native soils that will be utilized as fill material directly
beneath foundations, observation and/ or geotechnical testing is recommended prior to
foundation construction. The following placement and compaction requirements are
necessary.
For disturbed native soils or engineered fill beneath foundations, limits of compacted or
re-compacted fill shall extend laterally from the bottom edge of the foundation at a rate of
one foot for each foot of compacted or re-compacted fill beneath the foundation. See the
illustration below.
J&FOOTINGC❑MPACTEDNATIVE SOILS
OR ENGINEEREDFILL
I I UNDISTURBED SUBGRA)lE
Both engineered fill and native soils used as compacted fill should be free of roots and
other organics, rocks over 6 inches in size, or any other deleterious matter. Engineered
fill should consist of 60%to 100% gravel-sized material(particles between 3/16-inch and
3 inches), and less than 10% fines(particles passing#200 standard sieve)by weight.
Compaction shall be achieved in compacted lifts not to exceed 8 inches and 12 inches for
native soils and engineered fill, respectively. Each lift should be uniformly compacted to
at least 95% of the modified Proctor maximum dry density (ASTM D 1557) and within
3% of optimum moisture content. Each lift surface should be adequately maintained
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during construction in order to achieve acceptable compaction and inter-lift bonding.
4.33 Retaining Wall Backfdl
Native soils may be used as retaining wall backfill for this Project. Backfill may also
consist of engineered fill, as presented in this report, or borrow material approved by a
geotechnical engineer. Compaction of these materials shall be achieved in compacted lifts
of about 12 to 24 inches. Each lift should be uniformly compacted to no more than 90%
of the modified Proctor maximum dry density (ASTM D 1557). Over-compaction should
be prevented since this will cause lateral earth pressures to increase, which may be
detrimental to the retaining structure. If clean, coarse gravel soils are utilized as
engineered fill, compaction may be achieved from by reasonably densifying granular
soils with construction equipment.
Backfill for the retaining wall should extend vertically from the top of the footing to the
proposed ground surface.At the ground surface,backfill should extend horizontally from
the face of the retaining wall to at least 2 feet in back of the wall for every 4 feet in
height. Perforated drains for retaining walls should have a minimum diameter of 4 inches
and direct water to an appropriate outfall as recommended in the Surface and Subsurface
Drainage Section of this report.Coarse,clean gravel is recommended to be placed at least
12 inches around the drain pipe in order to provide increased drainage capabilities. Non-
woven geotextile filter fabric should be wrapped around the aforementioned coarse
gravel for reducing the potential of silt migration and clogging of the drain pipe.
4.3.4 Wet Weather Considerations
Due to the types of subsurface soils, additional provisions may be required during
prolonged wet weather. Every precaution should be made in order to prevent free
moisture from saturating the soils within excavations. If the bottom of excavations used
for footing placement changes from a moist and dense/hard characteristic as presented in
this report to muck or soft, saturated conditions, then these soils become unsuitable for
foundation bearing material. If this situation occurs, a geotechnical engineer should be
notified, and these soils should be completely removed and replaced with compacted
engineered fill or suitable native material as presented in this section.
4.3.5 Building Pads
Building pads for this Project shall be constructed per the fill placement and compaction
recommendations as presented above. Both engineered fill and native soils may be used
for building pads. Building pad slopes shall be no steeper than 2:1 for both compacted
engineered fill and re-compacted native soils used as fill. Building pad fill shall not
exceed 12 feet for this Project unless approved by a geotechnical engineer.
4.4 Slope Stability and Erosion Control
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
Envirotech Engineering Geotechnical Investigation
PO Box 984 page 11 Knudsen Tracts
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 June 12,2008
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.Surficial
slope movements have occurred are expected to continue naturally on the steep descending slopes
during times of extreme inclement weather. It is our opinion that these successive shallow
landslides will not threat the planned development during the design life of the structures.
According to the Coastal Zone Atlas of Mason County, Washington, the Project is within and
near terrain labeled `Stable' and `Intermediate' regarding potential landslide activity. Stable
slopes,located within the building areas, are generally not prone to landslides due to small grades
and accommodating geology. Historically, intermediate terrains have no known landslides.
However, this site is considered inherently hazardous due the existing geology, topography, and
the presence of surface sloughing. An additional analyses and recommendations concerning the
slopes are presented herein. A Stability Map from the Coastal Zone Atlas for the general area of
this Project may be found below in this report this report.
According to the Resource Map from the Washington State Department of Natural Resources
(DNR), the Project is not within terrain labeled `highly unstable' or `highly erodible' relating to
soils. In addition, DNR did not indicated previous landslide activity near the Project. DNR
labeled portions of this project as 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
considering the specific site geology or soils. A DNR map is provided below in this report.
The Simplified Bishop Method, utilizing `STABLE' software, was used to analyze the static
stability of the site slopes. Various radii's and center points of the circle were automatically
selected, and produced factor of safeties in a graphical and tabular format. Worst case scenario
values were used in the slope stability analysis in regards to topography, surcharges, water
content, and cohesion of the site soils. STABLE software has been repeatedly checked with
manual calculations, and consistently proved to be a very conservative program. The following
soil properties were used in the analysis, and are based on observed conditions, known geology,
and/or published parameters:
Top 2 feet of weathered soils
• Soil unit weight: 132 pcf
• Angle of internal friction: 30 degrees
• Cohesion: 100 psf
Soils from 2 feet to 12 feet
Envirotech Engineering Geotechnical Investigation
PO Box 984 page 12 Knudsen Tracts
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 June 12,2008
• Soil unit weight: 135 pcf
• Angle of internal friction: 39 degrees
• Cohesion: 400 psf
Soils from 12 feet to 20 feet
• Soil unit weight: 110 pcf
• Angle of internal friction: 34 degrees
• Cohesion: 100 psf
Soils below 20 feet
• Soil unit weight: 130 pcf
• Angle of internal friction: 30 degrees
• Cohesion: 1000 psf
Seismic conditions were estimated utilizing worst case scenario values from the static analysis, a
quasi-static analysis coefficient of at least 0.15, and applying the applicable values to STABLE
software.
Envirotech Engineering Geotechnical Investigation
PO Box 984 page 13 Knudsen Tracts
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 June 12.2008
Anticipated building loads, building pads or cuts, are not expected to have any detrimental
influence on the global stability of the slopes, provided that the setback requirements, drainage
and all other recommendations in this report are adhered to. Based on the aforementioned Project
criteria, observations, slope stability analysis, and the recommendations in this report, the
building locations have an acceptable factor of safety of over 1.5 relative to deep-seated, static
slope failures. Furthermore, an acceptable factor of safety of over 1.1 for seismic conditions was
also concluded for this Project. See the slope stability information in Appendix D for input
parameters and example of outputs.
F
/035tN 11 � 17060M
..is x'n�20
M"1F���•ttt 1703M0 17N"2 *70SM{
►.Nt NON
T. 4
Project _=J
29
Map from Washington State Department of Natural Resources
Envirotech Engineering Geotechnical Investigation
PO Box 984 page 14 Knudsen Tracts
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 June 12,2008
_-
i Project
u ..
o1 Pi
n
) s
Rocky int
/ Scale 1:24.000
is 1 MOC,
j 0 jQll IOW IWO \IHrn
Map from Washington State Department of Ecology Website
The aforementioned slope stability factors of safety are for the planned building sites.This model
depicted safe building sites beyond 40 feet from the top of steep descending slopes. Site
conditions and the slope stability model concluded unstable descending slopes.
Several slope stability analyses were performed for this Project, and one extremely conservative
analysis with relation to site topography and soils is presented herein. The topography was
modeled based on potential future conditions due to successive shallow slides. This model
included moderate slopes of nearly 20% beyond the top, 10% grades beyond the toe, and an 86%
slope with a vertical relief of 100 feet. These grades are excessive with relation to probable
conditions during the design life of the structures.
Soil inputs, as provided above, were based on direct shear testing for the weakest structure, field
testing for the upper dense soils, and laboratory testing for the underlying clay layer. Both
published soil characteristics and direct correlation of specific soils testing for this Project
Envirotech Engineering Geotechnical Investigation
PO Box 984 page 15 Knudsen Tracts
Belfair,Washington 98.528 Mason County,Washington
Ph. 360-275-9374 June 12,2008
provide greater strength parameters than what was used in the analysis.
4.4.1 Septic Drainfield Impacts
Septic drainfields are not anticipated for this Project due to future plans of stubbing into a
municipal system.
4.4.2 Building and Footing Setbacks
Provided that assumptions relating to construction occur and recommendations are
followed as presented in this report, the factor of safety for slope stability is sufficient for
a 40 feet footing setback from the face of the nearby descending slopes exceeding 40%.
See the figure below and the Geologic Map in Appendix B for an illustration of the
setbacks.
TOP OF STRUCTURE
SLOPE — SLOPE
FACE
' IiLL—III• —III
*— 40 FT MIN --�-� FOOTING
In addition, footings shall have a minimum setback of 5 feet from the top of building
pads consisting of engineered fill.
4.4.3 Temporary and Permanent Erosion Control
Based on the USCS description of the Project soils, the native soils have a moderate
erodibility factor. Temporary and permanent erosion control measures will be required
for site development. Existing erosion control present on-site such as silt fencing appear
to be sufficient for this Project. Additional temporary erosion control measures may need
to be employed if excessive erosion occurs or required by the County or other prevailing
agencies. See Appendix A for approximate locations of existing erosion control facilities.
A stormwater management plan has been prepared for this Project, and addresses
appropriate temporary and permanent erosion control. Silt fencing is presented in this
report as the first choice for temporary erosion control. Any erosion control should be
located down-slope and beyond the limits of construction and clearing of vegetation
where surface water is expected to flow. If the loss of sediments appears to be greater
than expected, or erosion control measures are not functioning as needed, additional
measures must be implemented immediately. See Appendix E for sketches and general
notes regarding selected erosion control measures.
Permanent erosion control is required per the stormwater management plan, and may also
be necessary if substantial vegetation has not been established within disturbed areas
upon completion of the Project. Temporary erosion control should remain in place until
permanent erosion control has been established. Permanent erosion control may include
Envirotech Engineering Geotechnical Investigation
PO Box 984 page 16 Knudsen Tracts
Belfair,Washington 98.528 Mason County,Washington
Ph. 360-275-9374 June 12,2008
promoting the growth of vegetation within the exposed areas by mulching, seeding or an
equivalent measure. Selected recommendations for permanent erosion control are
provided in Appendix E. Additional erosion control measures that should be performed
include routine maintenance and replacement, when necessary, of permanent erosion
control, vegetation,drainage structures and/or features.
Sedimentation control should be adequate when utilizing the erosion control
recommendations as presented herein together with implementing appropriate erosion
controls with the degree of care as expected from a licensed contractor. Erosion control
information and specifications in addition to what is provided in this report may be found
in the appropriate "Stormwater Management Manual for Western Washington,"prepared
by the Washington State Department of Ecology Water Quality Program.
4.4.4 Surface and Subsurface Drainage
Positive drainage should be provided in the final design for all planned residential
buildings. Drainage shall include sloping the ground surface, driveways and sidewalks
away from the Project structures.All constructed surface and subsurface drains should be
adequately maintained during the life of the structure. If drainage problems occur during
or after construction, additional engineered water mitigation will be required. This may
include a combination of swales, berms, drain pipes, infiltration facilities, or outlet
protection in order to divert water away from the structures to an appropriate protected
discharge area.
Both footing perimeter drains and roof drains are required for this Project. Subsurface
water intercepted in the footing perimeter drains, and stormwater collected from roof
drains shall be tight-lined to an appropriate outfall location beyond the toe of the steep
40%+ slopes. Recommended outfall locations are delineated on the Geologic Map in
Appendix B, and optional drainage details for tightlining are provided in Appendix F of
this report.
4.4.5 Vegetation Considerations
Vegetation is an excellent measure to minimize surficial slope movements and erosion on
slope faces and exposed surfaces. By removing trees, the root strength is decreased over
time, thereby lowering the `apparent' cohesion of the soil. Transpiration is decreased,
which results in additional groundwater, increased pore water pressure and less cohesion/
friction of the soil particles. Stormwater runoff also increases, and, fewer plants will
create less absorption of the force from raindrops, thereby creating the potential for
erosion hazards.
For existing conditions, vegetation shall not be removed on the face of the steep slope or
within 40 feet from the top of the slope.This buffer may be reduced 15 feet as necessary
for construction. However, any tree deemed hazardous to life or property shall be
removed. If tree removal is necessary, then stumps and roots shall remain in place, and
the underbrush and soil shall remain undisturbed as much as possible. Any disturbed soil
shall be graded and re-compacted in order to restore the terrain similar to preexisting
conditions and drainage patterns. See the Geologic Map in Appendix B of this report for
Envirotech Engineering Geotechnical Investigation
PO Box 984 page 17 Knudsen Tracts
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 June 12,2008
a depiction of the vegetation buffer.
4.4.6 Off-site impacts
From a geotechnical position, it is Envirotech's opinion that the adjacent properties to the
proposed development should not be significantly impacted as a result of this
development if all recommendations in this report are followed. This is based on the
expected site development,and the recommendations presented in this report.
4.5 Seismic Considerations and Liquefaction
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 Class `B' fault to this
property is the Tacoma Fault Zone,in which is approximately 2 miles to the south of this Project.
This information is based on 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, in part, on the slope stability analysis utilizing seismic considerations
in addition to subsurface conditions such as soil characteristics and the lack of a permanent
shallow water table. Subgrade characteristics that particularly contribute to problems caused from
liquefaction include submerged, 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. No significant saturated sand stratifications are
anticipated to be within the upper 50 feet of the subsoil for this Project.
Envirotech Engineering Geotechnical Investigation
PO Box 984 page 18 Knudsen Tracts
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 June 12,2008
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 construction, or 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 geotechnical design guidelines, and is intended only for the owner, or
owners' representative, and location of project described herein.This report should not be used to
dictate construction procedures or relieve the contractor of his responsibility.
Any and all content of this geotechnical report is only valid in conjunction with the compliance of
all recommendations provided in this report. Semantics throughout this report such as `shall,'
`should' and `recommended' imply that the correlating design and/or specifications must be
adhered to in order to protect life and property. Semantics such as `suggested' or `optional' refer
that the associated design or specification may or may not be performed. The recommendations
provided in this report are valid for the proposed development at the issuance date of this report.
Changes to the site other than the expected development, changes to ordinances or regulatory
codes, or broadening of accepted geotechnical standards may affect the conclusions and
recommendations of this report.
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
:7tr szwltc
Michael Staten,P.E.
Geotechnical Engineer
Envirotech Engineering Geotechnical Investigation
PO Box 984 page 19 Knudsen Tracts
Belfair,Washington 98528 Mason County,Washington
Ph. 360-275-9374 June 12,2008
APPENDIX A
SITE PLAN
A
SCALE, 1 INCH 150 FEET PROPOSED ACCESS ROAD
140 tea
200 1B0 160
c�7 150 1113'
ANTIC PATE _ ATEDLAUMJ=
TED 100
BULL NG AN ] PATE BU2L NG / LOI
�fON ANTIC PA 9U1L I13N ®TED ANTI AM BUIL NltTED LOLA]ON T¢2 80
BU1LD NG LOCATIIIN'� BUIL CA 60
SILT FENCE----" BIDN
T1( 4E—
40
77' 2 LOT i
FN—lTqPATED
OSED
DETENTION
WSIN
9 102,
213, LE1T LOr 4
POSSIBLE
RETENTION/
DETENTION
AREA
W L
4
EXISTING ACCESS ROAD
PROJECT/ OWNER/ LOCATMN.
PROPOSE KNUDSEN TRACTS
5 BASDI LEGEND GE❑TECHNICAL REPORT
JACK JOHNSON CONSTRUCTION, LLC
�Tp1 TEST PIT SHERWOOD CREEWK ROAD, ALLYN
SLOPES MASON COUNTY, WASHINGTON
ENGINEER-
EXISTING CONTOUR_ 75 ENVIROTECH ENGINEERING
T 3 10. 74 NE HURD ROAD
+� SILT FENCE OR APPROVED BE AIR. 74
W S14INGTON 98528
EROSION CONTROL
SITE PLAN
APPENDIX B
GEOLOGIC MAP
9 PROPOSED ACCESS ROAD
SCALE- 1 INCH 150 FEET ,Opp 140 no
le0 160
lU 3'
T AN PATE PATEO TED 100
BUIL NG ANTI PATE A ATED IL NG
ON ANTIC PATE BOIL NGNUILlind
VWTrMqTED BUILD G UdD�J�A LUCA 80
BULL NG �� ATD]N` HIM Ta 60
LOT 8 A
T 1
40
LOT 1
40FT BUIL045, K
R D
FRW TGETA_IO- P NOTTRAN
D. T EX DDKi 40% PEE AS NEC y _
DUI i
V4 LU ^
y ARPRO IMATE TIP OF
OPE EXCEEDING 4 1K'
731 LOT 4
APPROXIMATE TIE OF SLOPES
SEWERS ARE TO BE P EXCEEDING 40%
STUBBED INTO ETEN N/ SOILS- DENSE SILTY
LOCAL COMMUNITY DETENTION SAND OVERLYING
SYSTEM AREA HARD SANDY CLAY
4
N
EXISTING ACCESS
ROAD
PROJECT/ OWNER/ LOCATION-
KNUDSEN TRACTS
5 ME S GEOTECHNICAL REPORT
DAASI LEGEND JACK JOHNSON CONSTRUCTION, LLC
�Tpl TEST PIT SHE WOOD CREEWK ROAD, ALLY
N
MASON COUNTY, WASHINGTON
—y SLOPES ENGINEER,
ENVIROTECH ENGINEERING
75 EXISTING CONTOUR 74 ME HURD ROAD
03 300 /�I SILT FENCE OR APPROVED 360F27S=9374HINGTON 98528
EROSION CONTROL
GEOLOGIC MAP
APPENDIX C
SOIL INFORMATION
AND
PROPOSED HOUSE VERTICAL NCH Mo40 FM T 40
�o
zS%+
20'
MED, TO DENSE SILTY SAND (SM)
LOW TO MODERATE CEMENTATI❑N
60'
v
BROWN, HARD SANDY CLAY (CL)
GLACIAL TILL
PROJECT/ OWNER/ LOCATION,
KNUDSEN TRACTS
GEOTECHNICAL REPORT
JACK JOHNSON CONSTRUCTION,LLC
SHERWOOD CREEWK ROAD, ALLYN
MASON COUNTY, WASHINGTON
NOTESi
ENGINEER
1)GRADE CHANGES WILL BE COMPLETED PER THE ST13RMWATER ENVIROTECH ENGINEERING
MANAGEMENT PLAN AS EXPLAINED IN THE GEOTECHNICAL REPORT. SECTION A-A 74 NE HURD ROAD
2) THE SOIL PROFILE IS ACCURATE FOR THE DEPTH OF
THE OBSERVED TEST PITS AT THE SPECIFIED LOCATIONS. BELFAIR, VASH[NGTON 98528
360-275-9374
LOWER DEPTHS ARE BASED ON SITE GEOLOGY,
WELL LOG(S),AND/OR EXPERIENCE IN THE GENERAL AREA,
SOIL PROFILE
TEST PIT LOG
TEST PIT NUMBER TP-1
PROJECT: Geotechnical Report DATE OF LOG: 05/16/2008
PROJECT NO: 0857 LOGGED BY: MCS
CLIENT:J. Johnson Construction, Inc EXCAVATOR: Thomas Sharpe
LOCATION: Parcel 122203300210,122292200320, 122203390221, DRILL RIG: Deere 160 LC backhoe
122203390222,122203390223,&122203390224 ELEVATION: N/A
Mason County,Washington
INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: N/A
SOIL STRATA, STANDARD PENETRATION TEST
DEPTH SAMPLERS USCS DESCRIPTION LL PI CURVE
AND TEST DATA DEPTH N 10 30 50
0
SM Brown,moist SILTY SAND with
GRAVEL,loose to medium dense.Gravel
is coarse.Sand is fine.Low plasticity.
2 Dense to very dense,brown and gray
Low to modeately cemented,trace of
gravel
4 Increasing coarse gravel
g = Occasional cobble
8
10
12
14
Excavation terminated at approximately
16 15.0 feet
18
120
No Groundwater Encountered ENVIROTECH ENGINEERING
This information pertains only to this boring and should not be Geotechnical Engineering
interpreted as being indicitrve of the entire site.
TEST PIT LOG
TEST PIT NUMBER TP-2
PROJECT: Geotechnical Report DATE OF LOG: 05/16/2008
PROJECT NO: 0857 LOGGED BY: MCS
CLIENT:J.Johnson Construction, Inc EXCAVATOR: Thomas Sharp
LOCATION: Parcel 122203300210, 122292200320, 122203390221, DRILL RIG: Deere 160LC backhoe
122203390222, 122203390223,&122203390224 ELEVATION: N/A
Mason County,Washington
INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: N/A
SOIL STRATA, STANDARD PENETRATION TEST
DEPTH SAMPLERS USCS DESCRIPTION LL PI CUJRVE
AND TEST DATA DEPTH N 10 30 50
0
SM Brown,moist SILTY SAND with
GRAVEL,loose to medium dense.Gravel
_ is coarse_Sand is fine.Low plasticity.
2
Dense,brown and gray,patches of low
to medium plasticity,occasional cobble
or boulder
4 Dense to very dense,brown and gray.
low to moderate cementation
6
8
10
12
Medium dense to dense,increasing fine
sand,trace of gravels
14
Increasing densty,increasing coarse
aravel
Excavation terminated at approximately
16 15.0 feet
18
20
No Groundwater Encountered ENVIROTECH ENGINEERING
This information pertains only to this bong and should not be Geotechnical Engineering
interpreted as being indlcrt+ve of the entire site.
SOIL LOG
TEST PIT NUMBER TP-3
PROJECT: Geotechnical Report DATE OF LOG: 05/16/2008
PROJECT NO: 0857 LOGGED BY: MCS
CLIENT: J.Johnson Construction, Inc EXCAVATOR: N/A
LOCATION: Parcel 122203300210, 122292200320, 122203390221, DRILL RIG: None
122203390222, 122203390223,& 122203390224 ELEVATION: N/A
Mason County,Washington
INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: N/A
SOIL STRATA, STANDARD PENETRATION TEST
DEPTH SAMPLERS USCS DESCRIPTION LL PI DEPTH N CURVE
AND TEST DATA 10 30 50
0
SM Brown and gray,moist SILTY SAND with
GRAVEL,loose to medium dense
4 - Dense
8
12
16
20 Sandy,clay pocket
24 J.
28
32
Hardpan
36 Excavation terminated at approximately
35.0 feet
40
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.
SOIL LOG
TEST PIT NUMBER TP-4
PROJECT: Geotechnical Report DATE OF LOG: 05/16/2008
PROJECT NO: 0857 LOGGED BY: MCS
CLIENT:J. Johnson Construction, Inc EXCAVATOR: N/A
LOCATION: Parcel 122203300210, 122292200320, 122203390221, DRILL RIG: None
122203390222, 122203390223,&122203390224 ELEVATION: N/A
Mason County,Washington
INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: N/A
SOIL STRATA, STANDARD PENETRATION TEST
DEPTH SAMPLERS USCS DESCRIPTION LL PI CURVE
AND TEST DATA DEPTH N 10 30 50
0
SM Brown,moist SILTY SAND with
GRAVEL,loose to medium dense.Gravel
is coarse-Sand is fine.Low plasticity.
2 -
4
6
8
CL Brown,hard,low moisture,SANDY LEAN
CLAY.Medium plasticity
10
Excavation terminated at approximately
10.5 feet
12
14
16
18
20
No Groundwater Encountered ENVIROTECH ENGINEERING
This information pertains only to this boring and should not be Geotechnical Engineering
interpreted as being indicrtrve of the entire site.
SOIL LOG
TEST PIT NUMBER TP-5
PROJECT: Geotechnical Report DATE OF LOG: 05/16/2008
PROJECT NO: 0857 LOGGED BY: MCS
CLIENT:J.Johnson Construction, Inc EXCAVATOR: N/A
LOCATION: Parcel 122203300210, 122292200320, 122203390221, DRILL RIG: N/A
122203390222, 122203390223,&122203390224 ELEVATION: N/A
Mason County,Washington
INITIAL DEPTH OF WATER: N/A FINAL DEPTH OF WATER: N/A
SOIL STRATA, STANDARD PENETRATION TEST
DEPTH SAMPLERS USCS DESCRIPTION LL PI CURVE
AND TEST DATA DEPTH N 10 30 50
0
SM Brown,moist SILTY SAND with
GRAVEL,loose to medium dense.Gravel
Is mostly coarse_Sand is fine and
2 medium.Low plasticity.
Dense to very dense,brownish gray,
hardpan
4
6
8
10
14
16
Excavation terminated at approximately
16.0 feet
18
20
No Groundwater Encountered ENVIROTECH ENGINEERING
This information pertains only to this boring and should not be Geotechnical Engineering
interpreted as being rndicitrve of the entire site.
r
y WATER WELL-REPORT CURRENT
r Osiglael a I•-py-ecology,Y!copy_—er,j..M_dry. Notice of Intent No. W 190101
Unique Ecology Well ID Tag No. AIG 421
Is Construetion/Decommissionf"s"incircle)
3.a -XO Construction Water Right Permit No.
y1 O Decommission.ORIGINAL-INSTALLAT/ONNotice Property Owner Name Jack Johnson
of Intent Number
� 2� Well Street Address wood Creek Rd-
PROPOSED USE: - �7 DomWic 0 Industrial M®icipl,
7 - 17 Dewamr -b Irnpbm O Ten Wen O other City Allyn County MasM
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ID Newwdl O Recadinoed lferhod:O Dug_ O 6aed O Drim
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Depth ofeacpleeed weR 1 AO t Long Deg Long Min/Sec
Ct NSTRUC 17M DETAILS Tax Parcel No. 12220-33-00210
LC"heg yG Welded 6 uAm Rao _ft b 1 75 IL .
larolyd:. O Lnev inmued - Dille.Rom It b R.. CONSTRUCTION OR DECOMMISSION PROCEDURE
0 Thmaded Di.dmm R.b .ft
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-- SUE of perfs - - to by ..k and oe.of paR_Rom - Il`o_n. MATERIAL I7tOA1 TO
scrteaa: 31 Yes O No R K-Pat Loulioo 1:73
V MsodacoaysName' J ns
'+0 Type rta i nl pcc ibdel No. -Tbp soil 0
Dism.�_SIa size A--any—n°t°
aam Sla sou nom ft b ft
L Gray.Yl OW padid:O Ya O No O Sine ofpaveVaad
Mrerials placed from ft
Serb.Seel:IR Ya Cl No To wlr_deplh7 IRn
Maknd umd in xal BEtnn i t-..p _ -
9 Did my stran corn tamsabk wew O Yes MNo Brown {ill 80 150
`y Type of waft, Depth of saga
Medmdorsdiq sum off Sand $ Gravel with water 150 180
Pl1MP:mondamaer's Nolce -rif�tr�
1 Type: ..Rtyh_
WATER LEVELS.-Landaut8ce elevation above neanaheel ft
St.".level 83-r R idow top of w it Dmt
Ancsian preame Ile;pa Apure wok Ore
^j Anesion waver is mmmaed by '
WELL TESM Dmwdowo is ammied Syr Iwo is bread bebw srlie level
2 was a pun p set mdc7 O Yes 3.1 No tf yes,by wbom7
YaW� dlssio.nvilh ft6aadoa+Men brio .
LI Yield. dARM wart R.d'madoaw aRer Ws.
Yield. d.hoin with ft dnavdowa all" bm
Ra'drorydaeo(riwr rdews au avro wAwrpwprunadoA/:h'aar/e'vd mrMairadJrow well..
tap 14 v '1err11 - -
- Time Wider Level Tlae Weer Level Time water Lev
6. Daft of teat
j, Bailerku-211-01-atwith 2n n.RmeowwMen�tn.
Mnen gal./ma wth tan xi at R.for hm
y Arte9rt Ron ash.Dole
Teepemae of wra—Was■chowd a mlym mak7 O Yes)p W -
swD.w 8[25/OS carplekdDafe 10/16/OS
WELL CONSTRUCTION CERTIFICATION: 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 are true to my best knowledge and belief.
MDrilla OE%inar OTrainee Name(") ilr� - Drilling Coagmy rk%ui a nriI leg
DnikdEngioea/rrnnee Siprae /��-.��`-T�--� Address 34n NR naui c 1:arts th3
Dnlla a e inee Licaoc W 797— — - City.Swe•Zip Apr fa i r r WA QRS7R
If TRAINEE. Caamttm•S '-
DrAer'o IJcoad No. - Registration No.DAVISDI11 OQA Ore f-Ct 05_
dioar'a SnpsYn Fcorop is an Equal Oppawoly E4lo x-
ECY 050-1-20(Rev 3/05) The Department of EcolM.does NOT warranty the Data andfor Informsdon on this Well Report.
APPENDIX D
SLOPE STABILITY
STABLE Slope Stability Analysis System
Envirotech Engineering
Project Knudsen Tracts
Datafile: final static Bishop
STABLE Version 9.03.00u
Bishop
.............a...........a...••...w.a...a.....a...........
TITLE
final static
..w..aa.a.a.....aw.a........a....a...•.a.a.a.........r...a
UNITS (Metric/Imperial) I
GEOMETRY DEFINITION
POINTS
NO. X Y
1 0.000 0.000
50.000 5.000
3 166.000 105.000
4 266.000 123.000
5 26.600 2.660
6 37.800 3.780
7 49.000 4.900
8 60.:00 13.790
9 71.40023.450
10 82.600 33.100
11 93.800 4:.760
1: 105.000 52.410
13 116.:00 62.070
14 127.400 71.720
15 138.600 81.380
16 149.800 91.030
17 161.000 100.690
18 17:.200 106.120
19 163.400 108.130
20 194.600 110.150
:1 :05.800 112.160
__ 217.000 114.180
:3 228.200 116.:00
25 0.000 -:.000
:6 50.000 3.000
:7 166.000 103.000
:8 266.000 121.000
29 0.000 -14.000
30 50.000 -9.000
31 166.000 91.000
3: 266.000 109.000
33 0.000 -20.000
34 50.000 -15.000
35 166.000 85.000
36 266.000 103.000
37 206.000 112.200
38 206.000 110.200
LINES
Lo X Hi X SOIL
1 _ 1
3 1
STABLE62002 AQ Asaodalaa Ltd Ptittyd on: 11106105 A 15:3/3t pow.
STABLE Slope Stability Analysis System
Envirotech Engineering
Project Knudsen Tracts
Datafile: final static : Bishop
3 37 1
37 4 1
25 26 _
=6 27 _
27 38 -
38 28 -
29 30 3
30 31 3
31 32 3
33 34 5
34 35 5
35 36 5
a.........w.....a.....a+aw+.w..w.ww.....a....a..«.a.aw.w.
SOILS
SOIL NAME LINETYPE-PEN COHESION FRICTION UNIT WT.
1 Soil-1 CONTINUOUS-BLACK 100.00 30.0 132.000
Soil-2 CONTINUOUS-BLUE 400.00 39.0 135.000
3 Soil-3 CONTINUOUS-BROWN 100.00 34.0 110.000
5 Soil-5 CONTINUOUS-CYAN 1000.00 30.0 130.000
6 Soil-6 CONTINUOUS-GRAY 0.00 0.0 0.000
..aaa..a......a..«...........a...a..w.wa.....r........a..
PORE PRESSURE SPECIFICATION
SOIL PIEZO RU EXCESS
Y/N/P Value Value
1 N 0.000 0.000
N 0.000 0.000
3 N 0.000 0.000
5 N 0.000 0.000
6 N 0.000 0.000
PIEZOMETRIC SURFACE
POINT
POINT PORE PRESSURES
POINT PRESSURE
..a.aa.a..a...a..ara•aa...as.aar.r...•..a..a......aar.....
SLIP DIRECTION (+/- X) -
SLIP-CIRCLES
MANUAL
Circle Centre Grid Extremities
335.800
STABLE®2OO2 MZ AssoaNsa Ltd hinMd qg 11� 41 M30,36 P; Z
APPENDIX E
EROSION CONTROL
GEOTEXTILE FABRIC GEOTEXTILE FABRIC
WRAP AROUND TRENCH 2'x2' IVA POST BETYP) AND WORE MESH
TO AT LEAST ENTIRE DR EQUIVALENT OR BETTER
BOTTOM OF TRENCH M 6 FT MAX.QL. M FT BEFORE PLACING GRAV� If— 6 FT —�I
\\ 2'x2'x5' WOOD POST OR
12' DEEP, 8' V[DE TRENCH fE.WZE:NT OR BETTER EXISTING
FILLED WITH 3/4' TO
1 1/2'� GROUND SURFACE
WASHED GRAVEL 2
DIRECTION ---� 2S FT 12' DEEP, 8' VIDE
WATER ROW EXISTING TRENCH FILLED WITH 1_tLr
12' GROUND SURFACE 3/4' TO 1 112' T Z5 FT
2.5 FT WASHED GRAVEL
BOTTOM EXTENTS OF
GEOTEXTILE FABRIC SILT FEM10E—OE'TAIL
SILT FENCE-- CROSS SECTION N.T.S.
N.T.S. PERMANENT EROSION CONTROL NOTES,
GENERAL NOTES, SOD PLACEMENT
L SHOULD THE TEMPORARY EROSION AND SEDIMENT CONTROL MEASURES SHOWN ON L SOD FOR GRASS SWALES SHALL BE MACHINE CUT AT A
THESE PLANS PROVE TO BE INADEQUATE DURING CONSTRUCTION, THE CONTRACTOR 3/4—INCH UNIFORM THICKNESS AT THE TIME OF CURING.
SHALL INSTALL ADDITIONAL EROSION AND SEDIMENT CONTROL FACILITIES. MEASUREMENTS FOR THICKNESS SHALL EXCLUDE TOP GROWTH AND
2.ALL EROSION AND SEDIMENT CONTROL FACILITIES AND DEVICES SHALL BE THATCH
INSPECTED DAILY AND IMMEDIATELY MAINTAINED,IF NECESSARY. 2.STANDARD SIZE SECTIONS OF SOD FIR GRASS SWALES SHALL
3.ALL EROSION AND SEDIMENT CONTROL FACILITIES AND DEVICES SHALL BE LEFT IN BE STRONG ENOUGH TO SUPPORT THEIR OWN WEIGHT AND RETAIN
PLACE UNTIL THE UPSLOPE AREAS HAVE BEEN PERMANENTLY STABILIZED. THEIR SIZE AND SHAPE WHEN SUSPENDED BY THE END OF A 3
TEMPORARY EROSION CONTROL NOTES, FIAT SECTION.
FOR G.
3. SOD GRASS SHALES SHALL NOT BE HARVESTED OR
TRANSPLANTED WHEN EXCESSIVELY DRY IR WET MOISTURE
FOR ALL AREAS WHICH HAVE BEEN STRIPPED OF VEGETATION OR EXPERIENCED LAN➢ CONTENT MAY ADVERSELY AFFECT ITS SURVIVAL.
DISTURBING ACTIVITIES.AND WHERE NO FURTHER WORK 1S ANTICIPATED FOR A 4. SOD FOR GRASS SWALES SHALL BE HARVESTED, DELIVERED
PERIOD EXCEEDING THE LISTED CRITERIA BELOW,ALL DISTURBED AREAS MUST BE AND PLACED WITHIN A PERIOD OF 36 HOURS.
IMMEDIATELY STABILIZED WITH MULCHING, GRASS PLANTING IR OTHER APPROVED
EROSION CONTROL TREATMENT APPLICABLE TO THE TIME OF YEAR. GRASS SEEDING SEEDING FOR RAW SLOPES
ALONE WILL ONLY BE ACCEPTABLE DURING THE MONTHS OF APRIL THROUGH
SEPTEMBER. HOVEVER, SEEDING MAY PROCEED WHENEVER IT IS IN THE INTEREST IF L BEFORE SEEDING, INSTALL NEEDED SURFACE RUNOFF CONTROL
THE OWNER/CONTRACTOR, BUT MUST ALSO BE AUGMENTED WITH MULCHING. NETTING MEASURES SUCH AS GRADIENT TERRACES, INTERCEPTOR DIKES,
OR OTHER APPROVED TREATMENT. SVALES, LEVEL SPREADERS AND SEDIMENT BASINS.
2. THE SEED BED SHALL BE FIRM WITH FAIRLY FINE SURFACE,
DRY SEASON (MAY I THRU SEPTEMBER 30) —THE CLEARING[IFLAND,INCLUDING THE FOLLOWING SURFACE ROUGHENING.PERFORM ALL OPERATIONS
REMOVAL OF EXISTING VEGETATION OR OTHER GROUND COVER, MUST BE LOOTED TO ACCROSS OR PERPENDICULAR TO THE SLOPE.
ONLY AS MUCH LAND AS CAN RECEIVE APPROPRIATE PROTECTIVE COVER OR BE 3. SEEDING RECOMMENDATIONS, AS SHOWN BELOW, AND SHOULD BE
OTHERWISE STABILIZED, AFTER HAVING BEEN CLEARED OR OTHERWISE DISTURBED , APPLIED AT THE RATE OF 120 POUNDS PER ACRE.
BY NO LATER THAN SEPTEMBER 30 OF A GIVEN YEAR.UNLESS IMMEDIATE 4. SEED BEDS PLANTED BETWEEN MAY 1 AND OCTOBER 31 WILL
STABILIZATION IS SPECIFIED IN THE EROSION AND SEDIMENT CONTROL PLAN, ALL REQUIRE IRRIGATION AND OTHER MAINTENANCE AS NECESSARY TO
AREAS CLEARED OR OTHERWISE DISTURBED MUST BE APPROPRIATELY STABILIZED FOSTER AND PROTECT THE ROUT STRUCTURE.
THROUGH THE USE IF MULCHING,NETTING,PLASTIC SHEETING,EROSION BLANKETS, 5.SEED BEDS PLANTED BETWEEN NOVEMBER 1 AND APRIL 30,
FREE DRAINING MATERIAL,ETC., BY SEPTEMBER 30 OR SOONER PER THE APPROVED ARMORING OF THE SEED BED WILL BE NECESSARY, (e.g.,
PLAN OF ACTION.UNLESS OTHERWISE APPROVED BY THE COUNTY, SEEDING, GEOTEXTIL.ES, JUTE MAT, CLEAR PLASTIC COVERING).
FERTILIZING AND MULCHING OF CLEARED OR OTHERWISE DISTURBED AREAS SHALL BE 6.FERTILIZERS ARE TO BE USED ACCORDING TO SUPPLIERS'
PERFORMED DURING THE FOLLOWING PERIODS, MARCH 1 TO MAY 15, AND AUGUST 15 TO RECOMMENDATIONS.AMOUNTS SHOULD BE MINIMIZED, ESPECIALLY
OCTOBM L SEEDING AFTER OCTOBER I WILL BE DOE WHEN PHYSICAL COMPLETION ADJACENT TO WATER BODIES AND WETLANDS.
OF THE PROJECT IS IMMINENT AND THE ENVIR04ENTAL CONDITIONS ARE CONDUCIVE
TO SATISFACTORY GROWTH.IN THE EVENT THAT PERANENT STABILIZATION IS NOT USE THE FOLLOWING RECOMMENDED SEED MIXTURE FOR EROSION
POSSIBLE, AN ALTERNATIVE METHOD(F GROUND COVER, SUCH AS MULCHING,NETTING, CONTROL,OR A COUNTY APPROVED ALTERNATE SEED MIXTURE.
PLASTIC SHEETING,EROSION BLANKETS, ETC.,MUST BE INSTALLED BY NA LATER THAN
SEPTEMBER 30, PROPORTIONS PURITY
GERMINATION
N THE EVENT THAT CONSTRUCTION ACTIVITIES OR OTHER SITE DEVELOPMENT NAME BY WEIGHT m M
ACTIVITIES ARE DISCONTINUED FIR AT LEAST 4 CONSECUTIVE DAYS, THE cX)
OWNER/CONTRACTOR SHALL BE RESPONSIBLE FOR THE INSPECTION 13F ALL EROSION
AND SEDIMENT CONTROL FACILITIES IMMEDIATELY AFTER STORM EVENTS, AND AT REDTOP (AGROSTIS ALBA) 10 92
LEAST DICE EVERY WED(. THE WNER/ CONTRACTOR SHALL BE RESPONSIBLE FOR 90
THE MAINTENANCE AND REPAIR OF ALL EROSION AN SEDIMENT CONTROL FACILITIES. ANNUAL RYE (LOLIUM MULTIFLORUM) 40 98
90
WET SEASON(OCTOBER I THRU APRIL 30)—IN SITES WHERE UNINTERUPTED CHEWING FESUE 40 97
CONSTRUCTION ACTIVITY IS IN PROGRESS, THE CLEARING OF LAND, INCLUDING THE NU
REMOVAL OF EXISTING VEGETAT04 AND OTHER GROUND COVER, SHALL BE LIMITED (FESTUCA RUBRA COMMUTATA)
TO AS MUCH LAND AREA AS CAN BE COVERED OR STABILIZED WITHIN 24 HORS IN (JAMESTOWN, BANNER, SHADOW, KOKET)
THE EVENT A MAJOR STORM IS PREDICTED AND/ OR EROSION AND SEDIMENT WHITE DUTCH CLOVER 10 96
TRANSPORT OFF—SITE IS OBSERVED. 90
ALL CLEARED OR DISTURBED AREAS SMALL RECEIVE APPROPRIATE PROTECTIVE (TRIF[LBN REPENS)
COVER OR BE OTHERWISE STABILIZED, SUCH AS MULCHING,NETTING, PLASTIC MULCHING
SHEETING,EROSION BLANKETS,FREE DRAINING MATERIAL,ETC., WITHIN 5 DAYS AFTER
HAVING BEEN CLEARED OR OTHERWISE DISTURBED IF NIT BEING ACTIVELY WORKED. L MATERIALS USED FOR MULCHING ARE RECOMMENDED TO BE WOOD
SILT FENCING, SEDIMENT TRAPS, SEDIMENT PONDS,ETC., WILL NOT BE VIEWED AS FIBER CELLULOSE, AND SHOULD BE APPLIED AT A RATE OF 1000
ADEQUATE COVER IN AND OF THEMSELVES IN THE EVENT THAT ANY LAND AREA NOT p"DS PER ACRE.
BEING ACTIVELY WORKED RDAINS UNPROTECTED OR HAS NOT BEEN APPROPRIATELY 2.MULCH SHOULD BE APPLIED IN ALL AREAS WITH EXPOSED
STABILIZED 5 DAYS AFTER HAVING BEEN CLEARED,ALL CONSTRUCTION ACTIVITY ON SLOPES GREATER THAN 211 (HARIZONTALIVERTICAL).
THE SITE, EXCEPT FOR APPROVED EROSION AND SEDIMENT CONTROL ACTIVITY, SHALL 3. MULCHING SHOULD BE USED IMMEDIATELY AFTER SEEDING OR IN
IMMEDIATELY CEASE UNTIL SUCH A TIME AS AFOREMENTIONED LAND AREA HAS BEEN AREAS WHICH CANNOT BE SEEDED BECAUSE OF THE SEASON.ALL
APPROPRIATELY PROTECTED OR STABILIZED. AREAS REQUIRING MULCH SHALL BE COVERED BY NIVEMBER L
SILT FENCE
PROJECT/ OWNER/ LOCATION+
1.GEOTEXTILE FILTER FABRIC TYPE SHALL BE PER SPECIFIED IN THE 'STORMWATER MANAGEMENT MANUAL KNUDSEN TRACTS
2.GEOTTEXTILE FILTEUGET R FABRIC SHALL BECABLE PURCHASEDTIN STANDARDS
A CONTINUOUS ROLL CUT TO THE LENGTH OF GE❑TECHNICAL REPORT
EACH BARRIER TO AVOID USE OF JOINTS.IF JOINTS ARE NECESSARY,FILTER FABRIC SHALL BE SPLICED JOHNS[N CONSTRUCTION,LLC
TOGETHER ONLY AT A SUPPORT POST WITH A MINIMA 6—INCH OVERLAP AND SECURELY FASTENED AT JACK JACK OH L'REEVK ROAD, ALLYN
BOTH ENDS TO THE POST. SHERMASON COUNTY, WASHINGTON
3. STANDARD FL NE 1'FILTER FABRIC SHALL BE FASTED USING STAPLES OR TIE VIBES CMG RINGS)2 4 IN
SPACING,
4. POSTS SHALL BE SPACED AND PLACED AT DEPTHS INDICATED N THE DETAILS(M THIS SHEET,AND ENGINEER,
DRIVEN SECURELY INTO THE GROUND. ENVI)MIECH ENGINEERING
5. VIBE MESH SHALL BE 2'X2'X14 GAUGE OR EOUIVILENT.THE WIRE MESH MAY IE ELIMINATED IF 74 NE HURD ROAD
EXTRA—STRENGTH FILTER FABRIC OKPIO MMENT),AND CLOSER POST SPACING IS USED. BELFAIR, WA94 NGTON 98528
6. A TRENCH SHALL BE EXCAVATED ACC13RODC TO THE DETAILS ON THIS SHEET ALONG THE LINE OF THE 360-275-9374
7ILµL � TET
.STFENCESS►AL LOCATED MVNA.IPE FROM THE CLEARING LIMITS OF THE PROJECT. ER❑SI❑N CONTROL
APPENDIX F
DRAINAGE DETAILS
STEEL CLAMPS (TYP)
CORRUGATED TIGHTLINE 30 FT Ma SPACING 1/2 INCH DIAMETER
6-INCH MIN. DIAMETER SECURELY FASTENED TO PIPE
8-12 INCH QUARRY SPALL OR
APPROVED ENERGY DISSIPATOR
LEVEL SECTION
TWO 3-FOOT o00000000000000
ANCHORS ITYP), 00000000000000 1 FT HIM
14 REHAR Ql O0O0 p00 0
EQUIVALENT 3 FT MIN
GEOTEXTILE FABRIC
TIGHTLINE DETAILS - IPTIDN 1
N.T.S.
FINAL GROUND
SURFACE GEOTEXTILE FABRIC WRAPPED
AROUND QUARRY SPALL
CORRUGATED TIGHTUME 8-12 INCH QUARRY SPALL OR
6-INCH M DL DIAMETER APPROVED INFILTRATION MEDIA
1
0�• .00000000000
00o00000000 FT MIN
O 00000000000
SUBSURFACE DRAINAGE DETAILS - OPTION 2
N.T.S.
MGM-
PROJECT/ OWNER/ LOCATION,
IMFILTRATION FACILITY lR PONDS SHALL BE SIZED FiR
THE I00YR 24HR STORM EVENT, KNUDSEN TRACTS
GE❑TECHNICAL REPORT
JACK JOHNSON CONSTRUCTION,LLC
SHERWOOD CREEVK ROAD, ALLYN
MASON COUNTY, WASHINGTON
ENGINEER'
ENVL'.OTECH ENGINEERING
74 HE HURD ROAD
BELFAIR, WASHINGTON 98528
360-275-9374
DRAINAGE DETAILS