HomeMy WebLinkAboutGEOtech Report 2 parcels - BLD Engineering / Geo-tech Reports - 12/23/2009 1
GEOTECHNICAL
REPORT
PARCEL #S 12108-42-00140 AND 12108-42-00052
462 EAST STRETCH ISLAND DR S
MASON COUNTY, WASHINGTON
Submitted to:
Dick and Patty Funk
9015 172nd Avenue NE
Redmond, Washington 98052
Submitted by:
E3RA, Inc.
PO Box 44840
Tacoma, WA 98448
sl
f
December 23, 2009
T09108
's
Mason County Department of Community Development
Submittal Checklist For a Geotechnical Report
Instructions:
This checklist must be submitted with a Geotechnical Report and completed, signed, and stamped by the
licensed professional(s)who prepared the Geotechnical Report 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: Richard Funk Parcel# 12108-42-00140 and 12108-42-00052
Site Address: 462 East Stretch Island Drive South, Grapeview, WA
(1) (a)A discussion of general geologic conditions in the vicinity of the proposed development,
Located on page(s)4, 5, 6
A discussion of specific soil types
Located on page(s) 5, 6
(b) A discussion of ground water conditions
Located on page(s) 5, 6
(c) A discussion of the upslope geomorphology
Located on page(s)4
(d) A discussion of the location of upland waterbodies and wetlands
Located on page(s)4
(e) A discussion of history of landslide activity in the activity in the vicinity, as available in the
referenced maps and records
Located on page(s) 5
(2) A site plan which identifies the important development and geologic features.
Located on Map(s) Fig. 2
(3) Locations and logs of exploratory holes or probes.
Located on Map(s) Fig. 2
(4) The area of the proposed development, the boundaries of the hazard, and associated buffers and
setbacks shall be delineated (top, both sides, and toe) on a geologic map of the site.
Located on Map(s) Fig. 2
(5) A minimum of one cross section at a scale which adequately depicts the subsurface profile, and
which incorporates the details of proposed grade changes.
Located on Map(s) Fig. 3
(6) A description and results of slope stability analyses performed for both static and seismic loading
conditions. Analysis should examine worst case failures. The analysis should include the
Simplified Bishop's Method of Circles. The minimum static safety factor is 1.5 (not applicable), the
minimum seismic safety factor is 1.1. (Not applicable) and the quasi-static analysis coefficients
should be a value of 0.15.
Located on page(s) 5, 6, Appendix A
(7) (a)Appropriate restrictions on placement of drainage features
Located on page(s) Not applicable
(b) Appropriate restrictions on placement of septic drain fields
Located on page(s) Not Applicable
(c) Appropriate restrictions on placement of compacted fills and footings
Located on page(s) not applicable
Page 1 of 2 Form Effective June 2008
Disclaimer: Mason County does not certify the quality of the work done in this Geotechnical Report.
(d) Recommended buffers from the landslide hazard areas shoreline bluffs and the tops of other
slopes on the property.
Located on page(s) 7, Figure 2
(e) Recommended setbacks from the landslide hazard areas shoreline bluffs and the tops of
other slopes on the property.
Located on page(s) 7, Figure 2
(8) Recommendations for the preparation of a detailed clearing and grading plan which specifically
identifies vegetation to be removed, a schedule for vegetation removal and replanting, and the
method of vegetation removal.
Located on page(s) 7, 8, 9
(9) Recommendations for the preparation of a detailed temporary erosion control plan which
identifies the specific mitigating measures to be implemented during construction to protect the
slope from erosion, landslides and harmful construction methods.
Located on page(s) 7, 8, 9
(10) An analysis of both on-site and off-site impacts of the proposed development.
Located on page(s) 7, 8
(11) Specifications of final development conditions such as, vegetative management, drainage,
erosion control, and buffer widths.
Located on page(s) 7
(12) Recommendations for the preparation of structural mitigation or details of other proposed
mitigation.
Located on page(s) 8, 9
(13) A site map drawn to scale showing the property boundaries, scale, north arrow, and the location
and nature of existing and proposed development on the site.
Located on Map(s) Fig. 2
I, rlZIcW �i�/�/�z�✓�i-GL/-7 hereby certify under penalty of
perjury that I am a civil engineer licensed in the State of Washington with specialized knowledge of
geotechnical/geological engineering or a geologist or engineering geologist licensed in the State of
Washington with special knowledge of the local conditions. I also certify thatthat the Geotechnical
Report, dated f L �3ILI) and entitled ���
Ir s /II0i-`/1 00&,o foy /)/4-yi- meets all the requirements of the Mason
County Resource Ordinance, Landslide Hazard Section, is complete and true, that the assessment
demonstrates conclusively that the risks posed by the landslide hazard can be mitigated through the
included geotechnical design recommendations, and that all hazards are mitigated in such a manner as
to prevent harm to property an . health and safety. (Signature and Stamp)
-oE aSh/,)
o
7
�. Ervin*eng aeo ist y
711 `
� d Geo�o
Fred Ernest Rennebaum
Page 2 of 2 Form Effective June 2008
Disclaimer: Mason County does not certify the quality of the work done in this Geotechnical Report.
TABLE OF CONTENTS
Page No.
1.0 SITE AND PROJECT DESCRIPTION..................................................................................1
2.0 EXPLORATORY METHODS................................................................................................2
2.1 Hand Boring Procedures ..........................................................................................3
3.0 SITE CONDITIONS..............................................................................................................3
3.1 Surface Conditions...................................................................................................3
3.2 Soil Conditions..........................................................................................................4
3.3 Groundwater Conditions...........................................................................................5
3.4 Seismic Conditions...................................................................................................5
3.5 Liquefaction Potential ..............................................................................................5
3.6 Slope Stability Analysis ............................................................................................5
4.0 CONCLUSIONS AND RECOMMENDATIONS.....................................................................6
4.1 Site Preparation........................................................................................................8
4.2 Pin Piles ..................................................................................................................9
5.0 RECOMMENDED ADDITIONAL SERVICES.....................................................................10
6.0 CLOSURE..........................................................................................................................11
List of Tables
Table 1. Approximate Locations and Depths of Explorations......................................................................2
Table 2. Estimated Properties of Onsite Soils for Stability Analysis............................................................6
List of Figures
Figure 1. Topographic and Location Map
Figure 2. Site Plan
Figure 3. Geologic Cross Section A-A'
APPENDIX A
Soils Classification Chart and Key to Test Data .......................................................................................A-1
Logs of Hand Borings HB-1 and HB-2 .............................................................................................A-2. .A-3
APPENDIX B
Slope Stability Analysis
i
PO Box 44840
Tacoma WA 98448
253-537-9400
253-537-9401 fax
E3RA
December 23,2009
T09108
Dick and Patty Funk
9015 172nd Avenue NE
Redmond, Washington 98052
(425)466-9885
Subject: Geotechnical Report
Parcel#'s 12108-42-00140 and 12108-42-00052
462 East Stretch Island Drive South
Mason County,Washington
Dear Mr. and Mrs.Funk:
E3RA is pleased to submit this Geotechnical Report for your two-parcel residential site. The purpose of
our Report is to address Title 17 of Mason County Critical Areas Ordinances as they relate to landslide
and erosion hazards on the site. Plans call for building a new stairway down a bluff to the shoreline of
Case Inlet.
Our scope of services is limited to surface observations, subsurface hand borings, geologic research, and
letter preparation. This report has been prepared for the exclusive use of Dick and Patty Funk, and their
consultants, for specific application to this project in accordance with generally accepted geotechnical
practice.
1.0 SITE AND PROJECT DESCRIPTION
The project site is a roughly trapezoidal tract comprised of two adjacent tax parcels that together
encompass about 5 acres. The site measures slightly less than 700 feet east to west and slightly more than
300 feet north to south. It is located on east side of Stretch Island on the west shore of the North Bay part
of Case Inlet, as shown on our Topographic and Location Map (Figure 1). The site is in an area of
residential parcels and open land.
Plans call for the construction of new stairway down a steep, approximately 60 foot high bluff that slopes
down to the shoreline of Case Inlet. The stairway will be built on the west-central part of the site. It will
replace an existing stairway located on the northwest corner of the site.
The existing stairway,which was originally based on shallow foundations,was damaged by surficial land
sliding and erosion that occurred during the torrential rainfall of early December 2007. After the existing
stairway was damaged, it was repaired, but then it was decided that a new stairway, located away from
the existing stairway in an area where slopes are can be negotiated and surface water is not likely to flow
down the bluff face,should be built. It was also decided that the new stairway should be based on deeper
foundations so that if damage occurs to above-grade elements of the new stairway from surficial land
December 23, 2009 E3RA, Inc.
T09108/ Funk Geotechnical Report
sliding/sloughing, it is possible that all or substantial portions of the pin pile foundation would survive, so
that damaged above-grade stairway elements could more easily be rebuilt.
The new stairway will consist of an upland landing, based on the top of the steep bluff, and 11 or so
platforms,each of which will be supported by pin piles,that stair-step down the bluff toward the top of an
existing shoreline rockery. Flights of stairs will connect the upland landing and the platforms.
Pin piles will extend down to firm and non-yielding soils, and concrete, likely formed with sonotubes,
will cap the pile tops. Platforms will then be connected to the concrete-capped piles.
The alignment of the stairway will be directed side-hill to the southwest from the upland landing to the
uppermost platforms. The alignment will then turn so that it trends directly down slope at a location
where the face of the bluff is somewhat less steep than adjacent areas.
It is recognized by the owner and by E3RA that the bluff is prone to surface sloughing and shallow
landslides and that there can be no guarantee that future instability will not occur after the stairway is
constructed and cause damage to the planned structure.
Clearing will be limited to the alignment of the stairway, which will amount to the removal brush and
saplings along a 5 or 6 foot wide pathway. No clearing is planned outside of the stairway alignment.
2.0 EXPLORATORY METHODS
We observed site conditions on May 21, 2009 and December 7, 2009. Our evaluation program for the
project comprised the following elements:
• A surface reconnaissance of the site and nearby areas;
• Two hand boring explorations;and
• A review of published geologic and seismologic maps and literature.
Table 1 summarizes the approximate functional locations and termination depths of our probes and
Figure 2 depicts their approximate relative locations.
TABLE 1
APPROXIMATE LOCATIONS AND DEPTHS OF EXPLORATIONS
Exploration Functional Location Termination
Depth (feet)
HB-1 On hillside, within alignment of planned stairway, 15 to 20 feet above shoreline 6
HB-2 On hillside,within alignment of planned stairway, 30 to 40 feet above shoreline 6
It should be realized that the explorations performed and utilized for this evaluation reveal subsurface
conditions only at discrete locations across the project site and that actual conditions in other areas could
vary. Furthermore, the nature and extent of any such variations would not become evident until
additional explorations are performed or until construction activities have begun. If significant variations
are observed at that time,we may need to modify our conclusions and recommendations contained in this
report to reflect the actual site conditions.
2
December 23, 2009 ORA, Inc.
T09108/Funk Geotechnica! Report
2.1 Hand Boring Procedures
Our exploratory hand boring was advanced with a shovel and 3-inch hand auger by an E3RA geologist.
After our hand boring was completed,we backfilled it with excavated soils and tamped the surface.
The enclosed Hand Boring Log describes the vertical sequence of soils and materials encountered in our
hand boring, based on our field classification. Where a soil contact was observed to be gradational or
undulating, our log indicates the average contact depth. Our log also indicates the approximate depth of
any sidewall caving or groundwater seepage observed in the boring. Soils were classified visually in
general accordance with the system described in Figure A-1,which includes a key to the exploration logs.
3.0 SITE CONDITIONS
The following sections present our observations, measurements, findings, and interpretations regarding,
surface,soil;groundwater,seismic,liquefaction,and slope conditions.
3.1 Surface Conditions
The site can be divided into two topographic areas. The first is gently rolling upland that comprises all
but the westernmost part of the site. The second is a steep, approximately 60-foot high bluff that slopes
down to the west to the shoreline of Case Inlet. Grades along the bluff vary somewhat. The uppermost
part of the bluff is nearly vertical and ranges from 5 to 20 feet in relief. Grades lower along the bluff vary
and range from more than 120 percent to about 75 percent. Much of the less steep part of the bluff is
covered by loose colluvium. Colluvium is a collection of unconsolidated materials deposited on a bluff
face or at the base of a bluff by small landslides,raveling, sloughing,and erosion.
Slopes within 300 feet of the site along the bluff to the northeast and southwest are similar to those on site
and generally slope down to the Case Inlet at very steep grades. Slopes on the upland within 300 feet of
the site are gentle average less than 15 percent.
Areas adjacent to the upland have a rolling topography and are gently to moderately sloped with upslope
geomorphologic features typical of a rolling glacial till plain.
Grades along the bluff in the vicinity of the planned stairway alignment descend nearly vertically from the
upland about 5 feet; descend another 15 feet or so at about 100 percent; descend 30 feet or so more at
about 75 percent, then descend an additional 10 feet, to the top of the shoreline rockery, at about
100 percent.
The shoreline rockery is 5 to 6 feet high and is comprised of boulders that measure three feet or more in
size. No shoreline erosion was observed behind the rockery.
A residence occupies the southwest part of the site, 50 feet or so from the top of the bluff. An existing
stairway is located on the northwest part of the site. As mentioned, this stairway was damaged during
early December 2007, when torrential rains plagued the area and caused a small surficial slough/landslide
above the stairway and erosion from surface flow over the top of the bluff partially undermined the lower
part of the stairway.
3
December 23, 2009 ORA, Inc.
T09108 / Funk Geotechnical Report
The uppermost, nearly vertical parts of the bluff of are bare of vegetation. The areas immediately below
vertical areas of the bluff are vegetated with small hardwood saplings, sparse grass, and brush. The
lowermost half of the bluff is vegetated with alders and maples that range in size from saplings to almost
2 feet in diameter,with an under story of ferns and other brush.
The upland part of the site is vegetated by lawn and pasture grass, scattered firs and madronas, smaller
hardwoods,and,near the existing residence, scattered landscape plants.
A very small pond or large puddle was observed near the central part of the north boundary area. No
other features indicating surface hydrology were observed except near the existing stairway, where
surface flow generated during the torrential rains of early December 2007 flowed over the top of slope
and eroded a channel just north of the stairway.
No seeps, springs, or other surface expressions of groundwater flow were observed. No upland water
bodies were observed near the site,outside of the small pond/puddle described above.
The Coastal Zone Atlas maps the steep bluff both on and nearby off site as U,Unstable. According to the
Atlas, Unstable slopes are considered unstable because of geology, groundwater, slope and/or erosional
factors. They include areas of landslides and talus too small or obscure to be individually mapped. The
upland portion of the site and nearby areas is mapped by the same source as S, Stable.
We observed several areas where small surficial landslides and sloughs have occurred on the bluff face,
both on site and on adjacent parcels to the north and south, in the last few decades. The largest of these
on site, southwest of the planned stairway alignment, appears to measure tens of yards in volume, while
others appear to be less than 10 yards in volume. No global,deep-seated landslides were observed on site
or nearby off site.
3.2 Soil Conditions
Soils exposed on the upper vertical part of the bluff in the vicinity of the planned stairway consist of
medium dense to dense, silty fine to medium sand with some gravel. Soils exposed in the upper bluff
face elsewhere on site consist of medium dense to dense, silty fine sand with interbeds of stiff to hard fine
sandy silt.
Our two hand borings were conducted within the alignment of the planned stairway in the area where
slopes measure about 75 percent. The lower of the two borings,HB-1, augered at a location about 15 feet
above the elevation of the top of the shoreline rockery, encountered loose colluvium, comprised of silty
fine sand,to the termination depth of the exploration at a depth of 6 feet. The higher of the two borings,
BB-2, augered about 35 feet above the elevation of the top of the shoreline rockery, encountered
colluvium, comprised of loose, silty fine sand, to a depth of 2 feet underlain by loose to medium dense
colluvium, comprised of fine to medium sand with small inter-beds of fine sandy silt, to the termination
depth of the exploration at a depth of 6 feet.
It is to be expected that the colluvium that mantles the bluff is thinner toward the bluff top and thicker
toward the bluff toe.
4
December 23, 2009 OR& Inc.
T09108 I Funk Geotechnical Report
The Coastal Zone Atlas maps the upland part of the site as Qvt, Vashon glacial till, deposited as
lodgement till by the last glacier to cover the site. The Coastal Zone Atlas generally maps soils in the
steep bluff as Qu, undifferentiated Pleistocene Deposits. These deposits are subdivided into Qva,Vashon
advance outwash sand, which comprise the upper 15 feet of the bluff. The lower part of the bluff is
mapped as Qps, stratified and non-stratified non-glacial deposits that are similar to Esperence Sand.
Esperence Sand is a subcategory of Qva,Vashon Advance Outwash.
Our observations of in situ soils exposed in the bluff correspond closely to the mapped stratigraphy in that
the soils are generally sandy, with smaller inter-beds of sandy silt and all have been consolidated by
over-riding glacial ice (the non glacial deposits underlie the advance outwash, so predate the advance
outwash, and,although not glacially deposited,have been glacially over-ridden).
Soils within the tidelands,observed during our May reconnaissance,consist of a thin mantle of gravel and
sand overlying dense to very dense silty,gravelly sand and hard gravelly sandy silt.
Our logs of our recent subsurface explorations are presented in Appendix A and our interpretation of soil
stratigraphy is depicted in Geologic Profile A'A'.
33 Groundwater Conditions
We did not observe groundwater in our two hand borings nor did we observe seeps or springs along the
bluff. Soils within our borings were damp to moist in moisture content.
It is possible that perched groundwater forms above silty interbeds within the bluff face, but, as
mentioned, no seeps or springs were observed. It is also possible that perched groundwater forms at the
base of the bluff near sea level, where it is presumed that the very dense silty sand and hard sandy silt
extends inland under sandy bluff soils.
3.4 Seismic Conditions
Based on our classification of onsite soils and our review of published geologic maps, we interpret the
soil conditions in the vicinity of the planned stairway correspond with class D, as defined by
Table 1613.5.2 of the 2006 International Building Code(IBC).
3.5 Liquefaction Potential
Liquefaction is a sudden increase in pore water pressure and a sudden loss of soil shear strength caused by
shear strains, as could result from an earthquake. Research has shown that saturated, loose sands with
fines (silt and clay) content less than about 20 percent are most susceptible to liquefaction. The loose
colluvial soils that mantle the site do not appear to become saturated during the rainy season, and the in
situ soils within the bluff are too well consolidated to liquefy.
3.6 Slope Stability Analysis
We analyzed the slope stability under selected conditions. The following sections describe our method of
analysis and present our results.
Besides the actual geometry of the slope, slope stability analyses typically involve five basic slope
parameters: (1) location and shape of the potential failure surface, (2) internal friction angle of the
various soils, (3) cohesion of the various soils, (4) density of the various soils, and (5) location of the
piezometric groundwater surface. Once all five parameters have been estimated, the critical slip surface
5
December 23, 2009 ORA, Inc.
T09108 / Funk Geotechnical Report
and associated safety factor of a given slope can be calculated. A critical slip surface is defined as the
most likely surface along which a soil mass will slide,and a safety factor is defined as the ratio of the sum
of all moments resisting slope movement versus the sum of all moments tending to cause slope
movement. Consequently, a slope that possesses a safety factor of 1 is on the verge of sliding, whereas a
slope with a safety factor greater than 1 has some resistance to sliding. According to standard
geotechnical engineering practice, a static safety factor of 1.5 and a seismic safety factor of 1.1 are
considered the desirable minimum values for most slopes, but 1.25 and 1.01, respectively, are often
regarded as acceptable values.
Slope stability conditions for the project site were analyzed by means of Bishop Circular Analysis. All
calculations were performed utilizing the computer program WINSTABLE and are attached in
Appendix B.
Our site observations indicate that the bluff is comprised of well consolidated sandy soil and, surficial,
loose colluvium. Soils in the beach are very dense/hard. In order to model site slopes under the least
stable soil condition that our geologic research and field measurements indicate, our measurement of the
surface of the slope,measured in the field using a hand-held clinometer,tended to overstate the steepness
of the slope face; our estimation of the thickness of the loose colluvial layer, which we could not
determine by hand-augering was somewhat thicker than our experience would indicate; and the estimated
values of internal friction angle,cohesion,and density are fairly conservative.
Because the stairway will be built on pin piles,which their transfer loads to the pile tips,we did not apply
a load for the structure. We also did not assign any additional resistance to sliding that piling
reinforcement would supply to soils underlying the stairway alignment.
Based on the conservative parameters used in our computer model, our analysis yielded a Seismic Factor
of Safety Of 0.8 and a Static Factor of Safety of 1.03. Our analysis indicates that the site is globally stable
under non-seismic conditions, but could become unstable during a strong earthquake. The slide that
could develop during a strong earthquake begins within in situ bluff soils at the top of the bluff and
transitions into loose colluvium on the middle and lower parts of the slope.
TABLE 2
ESTIMATED PROPERTIES OF ONSITE SOILS FOR STABILITY ANALYSIS
Soil Type Density Cohesion Internal Friction Angle
(pcfl (psi) (degrees)
Colluvium 110 100 30
In situ bluff soils 120 125 34
4.0 CONCLUSIONS AND RECOMMENDATIONS
Plans call for the construction of a pin-pile supported stairway down to the shoreline.
• Landslide Hazards: Based on our conservative slope analysis, which was modeled using
a thick layer of loose colluvium,the site is a landslide hazard during a strong earthquake,
with the critical slip surface of an earthquake-induced landslide passing largely through
loose colluvium. Based on our reconnaissance, geologic mapping, and recent history,the
site is prone to surfical land sliding during the rainy season.
6
December 23, 2009 E3RA, Inc.
T09108/ Funk Geotechnical Report
Our recommendations for pin piles, presented below, include the driving of pin piles to
refusal. It has been our experience that pin piles will not meet refusal within loose
colluvial soils like those on site, but will meet refusal within the denser in situ soils that
underlie the loose colluvium. Based on this, it is our opinion that the construction of a
stairway down the bluff face, based on pin piles driven to refusal, will help to pin a
potential landslide block to underlying soils, and would somewhat reduce, but not
eliminate, the potential for seismic global instability along the stairway alignment,
provided our recommendations are followed.
Additionally,numerous pin piles driven along the stairway alignment would likely reduce
the potential for sloughing and surficial land sliding, provided our recommendations are
followed,because of lateral strength that the piles would supply to the soil.
• Erosion Hazards: Surficial soils in the alignment of the planned stairway present an
erosion hazard. We recommend that a silt fence be placed just down slope of earthwork
activities and remain in place until bare soils created during the planned construction can
be re-vegetated. We also recommend that the stairway be built during the dry season,
which generally begins in May. An early start during the dry season is preferable,so that
vegetation can be planted and established before the rainy season begins. If bare soils
due to construction activities persist into the rainy season, we recommend that bare soils
be covered temporarily with straw. Specific recommendations for silt fences are
provided in the Section 4.1.
• Pin Piles: Pin piles should be driven to refusal, which should be at relatively shallow
depths on the upslope part of the site, where colluvial soils are likely thinner. Refusal
will likely be achieved at deeper depths on down slope part of the stairway alignment,
where colluvial soils are likely thicker. The upland landing on the rim of the bluff should
also be supported by pin piles that are driven to refusal. Recommendations for pin piles
are provided in Section 4.
• Buffers and Setbacks: After the stairway is complete, the entire bluff face should be
considered a vegetative buffer,and a persistent attempt should be made to keep the bluff
face vegetated. We recommend that two publications by the Washington State
Department of Ecology, Slope Stabilization and Erosion Control Using Vegetation,
Publication 93-30, and Vegetation Management:A Guide to Puget Sound Bluff Property
Owners, Publication 93-31, be used as guidelines for maintaining the vegetative buffer.
Both publications are available online at the Washington State Department of Ecology
website.
• Bearing Soils: We anticipate that firm bearing soils, in which refusal to pile driving will
be met, will be encountered at shallower depths on the upslope part of the bluff, where
colluvium is thinner and shallower and deeper near the bluff toe, where colluvium is
thicker. Our subsurface explorations indicate that firm soils are deeper than 6 feet in the
mid slope and slope toe areas.
• Onsite and Offsite Impact of Planned Development: Because dozens of pin piles, driven
into well consolidated glacially-over ridden soils, will be used to support the stairway,
slope stability should improve somewhat along the planned stairway alignment, provided
our recommendations are followed. Short term erosion should be controlled in
7
December 23, 2009 E3RA, Inc.
T09108/Funk Geotechnical Report
accordance with the recommendations provided in the Erosion Hazard paragraph above
and in Section 4.1. Long term erosion is best dealt with using the guidelines presented in
the two DOE publications cited above.
• Clearing and Grading Plan: Based on our observation of the stairway alignment flagged
by the owner, no trees will be removed and only minor brush and limb removal will be
necessary. Grading will be limited to the small hand excavations necessary to
accommodate the concrete pile caps and,possibly,very small hand excavations necessary
to provide level platform construction. Site preparation recommendations are provided in
Section 4.1.
• Feasibility: We recommend that the planned stairway be built, with the understanding
that it be viewed as a temporary structure that will likely be damaged at some time by
surficial sloughing or by a seismically-induced landslide event,and will likely have to be
repaired periodically. Although the foundation of the structure will not eliminate the
potential for surficial and seismically induced landslides, it should reduce that potential
somewhat.
• Transfer of Ownership: In the event that ownership of the site is transferred or sold, new
owners should be informed that the stairway is a temporary structure that will likely be
damaged at some time by surficial sloughing or by a seismically-induced landslide event,
and will likely have to be repaired periodically.
The following sections present our specific geotechnical conclusions and recommendations concerning
site preparation and pin piles. The Washington State Department of Transportation (WSDOT) Standard
Specifications and Standard Plans cited herein refer to WSDOT publications M41-10, 1996 Standard
Specifications for Road, Bridge, and Municipal Construction, and M21-01, Standard Plans for Road,
Bridge, and Municipal Construction,respectively.
4.1 Site Preparation
Preparation of the project site should involve erosion control,temporary drainage,and slope protection.
Erosion Control: Before new construction begins, an appropriate erosion control system should be
installed. This system should collect and filter all surface water runoff through silt fencing. We
anticipate a system of berms and drainage ditches around construction areas will provide an adequate
collection system. Silt fencing fabric should meet the requirements of WSDOT Standard
Specification 9-33.2 Table 3. In addition, silt fencing should embed a minimum of 6 inches below
existing grade. An erosion control system requires occasional observation and maintenance. Specifically,
holes in the filter and areas where the filter has shifted above ground surface should be replaced or
repaired as soon as they are identified.
All areas of bare soils should be re-vegetated as soon as possible. If bare soils persist into the rainy
season,they should be covered with straw until vegetation can be established.
Temporary Drainage: We recommend intercepting and diverting any potential sources of surface or
near-surface water that might flow over the top of the bluff into the construction zone. Based on our
current understanding of the construction plans, surface and subsurface conditions, it appears that surface
water generated on the upland will not flow over the top of the bluff. If it is found that upland surface
8
December23, 2009 ORA, Inc.
T09108/Funk Geotechnical Report
water does flow over the bluff down to the construction area, we anticipate that curbs, berms, or ditches
placed on the upland will adequately intercept surface water runoff.
Slope Protection: A hardy vegetative groundcover should be established as soon as feasible, to further
protect the gently-sloped from the potential from runoff water erosion. Alternatively, permanent slopes
could be armored with quarry spalls or a geosynthetic erosion mat.
4.2 Pin Piles
Pin piles are planned to support the stairway. The following recommendations and comments are offered
for pin pile design and installation purposes.
Materials: For relatively low loads, pin piles typically consist of 2-inch-diameter Schedule-80
(2.375-inch O.D.)steel pipe. Individual pipe segments typically range from about 3 to 5 feet long and are
successively joined with external threaded couplings, internal slip couplings, or butt welds as pile driving
progresses.
Corrosion Considerations: Although we did not perform corrosivity tests on the site soils, our experience
with similar soils indicates a low probability that the site soils are corrosive to steel. Consequently, we
infer that conventional Schedule-80 pipe can be used for pin piles. We recommend the use of galvanized
pipe due to the proximity of salt water at this location.
Driving Procedures: We tentatively anticipate that the pin piles will first encounter bearing soils,
comprised of in situ bluff soils,at fairly shallow depths just below the top of the bluff,but at much greater
depths on the down slope part of the stairway alignment, where the overlying loose colluvium is thought
to be relatively thick. Piles should be driven to refusal, which is defined as 1 inch or less penetration in
1 minute. However,because refusal depths are difficult to predict and because soil conditions could vary
significantly across the site, the contractor should be prepared for variable pile lengths. Also, it may be
necessary to modify pile layouts if rocks or other obstructions are encountered during pile-driving.
Pile Butt Treatment: When refusal has been achieved, the pile butts can be cut off to a predetermined
height or elevation. To provide a good bond between the piles and the concrete pile caps,reinforcing bars
with 90-degree bends can be welded to the top of the pile or, alternatively, the top of the pile can be
splayed apart.
Axial Load Capacities: In our opinion,a properly installed 2-inch-diameter pin pile driven to refusal will
provide the following allowable axial capacities. These capacities assume a minimum pile spacing
(center to center) of six diameters. Furthermore, the stated uplift capacities would be applicable only to
pin piles that are installed with tension-resisting couplings.
Design Parameter Allowable Value
Static Compressive Capacity 4,000 pounds
Transient Compressive Capacity 5,300 pounds
Transient Uplift Capacity 2,600 pounds
9
December23, 2009 E3RA, Inc.
T09108/Funk Geotechnical Report
Load Testing: It is possible that Mason County may require load testing in order to verify static
compressive pile capacities. Specifically, the county may require load testing of at least 3 percent of all
piles installed at the site, with a minimum of one test and a maximum of five tests. If required, all tests
must conform to the Quick Load Test Method per ASTM D-1143. Additionally, the county may require
that driving of at least one pile be observed and documented to confirm that pile refusal can be met.
5.0 RECOMY[ENDED ADDITIONAL SERVICES
Because the future performance and integrity of the structural elements will depend largely on proper site
preparation, drainage, fill placement;and construction procedures,monitoring and testing by experienced
geotechnical personnel should be considered an integral part of the construction process. Consequently,
we recommend that E3RA be retained to provide the following post-report services:
• Review all construction plans and specifications to verify that our design criteria
presented in this report have been properly integrated into the design;
• Prepare a letter summarizing all review comments(if required by Mason County);and
■ Observe the installation of and provide documentation of some of the pin pile
installation;
• Prepare a post-construction letter summarizing all field observations, inspections, and test
results(if required by Mason County).
10
December 23, 2009 E3RA, Inc.
T09108/ Funk Geotechnical Report
6.0 CLOSURE
The conclusions and recommendations presented in this report are based, in part, on the explorations that
we observed for this study; therefore, if variations in the subgrade conditions are observed at a later time,
we may need to modify this report to reflect those changes. Also, because the future performance and
integrity of the project elements depend largely on proper initial site preparation, drainage, and
construction procedures, monitoring and testing by experienced geotechnical personnel should be
considered an integral part of the construction process. E3RA is available to provide geotechnical
monitoring throughout construction.
We appreciate the opportunity to be of service on this project. If you have any questions regarding this
report or any aspects of the project, please feel free to contact our office.
Sincerely,
o� Was
E3RA,Inc. 01
���e ��o� ti� E• Bj�jC
ti A
y._
<� E. `y 20540
�� 711 �O
Sed Geo
Fred Ernest Rennebaum
Fred E. Rennebaum, L.E.G. James E. Brigham, P.E.
Senior Geologist Principal Engineer
FER:JEB:jb
TACO\\Tacoma-server\c\JOB FILES\2009 JOB FILES\T09108 FUNK GEOTECMT09108 Funk Mason Report.doc
Four copies submitted
11
TOPO! map printed on 12/17/09 from "Untitled,tpo"
122051.000' W 122050,000' W WGS84 1221149,000' W
z77
/r •� 0
0 i • f '\ 0
0 0
� ry
!STRETCH K)fNr
�
STATE PARK
• h ,
• '.fly ' �
Oir !T • e r
✓�
z s
( RO r
r f
• ,r , 0
rn
1221151,000' W 1221150,000' W WGS84 122°49,000' W
TN IMN D 5 I MILE
�'l� 004 FEE1 D fial 1000 hiETEAS
Map created with TOPO!6 @2003 National Geographic(wwwmationalgeographic.comltopo)
E3RA, Inc. FUNK GEOTECH REPORT
PO Box 44840 TOPOGRAPHIC AND LOCATION MAP FIGURE 1
Tacoma, WA 98448 T09108
MASON COUNTY, WASHINGTON
APPENDIX A
SOILS CLASSIFICATION CHART AND
KEY TO TEST DATA
LOGS OF TEST PITS
MAJOR DIVISIONS TYPICAL NAMES
CLEAN GRAVELS JGP
JV WELL GRADED GRAVELS,GRAVEL-SAND MIXTURES
GRAVELS WITH LITTLE OR
MORE THAN HALF NO FINES 3' POORLY GRADED GRAVELS,GRAVEL-SAND MIXTURES
o'•D.
COARSE FRACTION ° SILTY GRAVELS,POORLY GRADED GRAVEL-SAND-SILTI IS LARGER THAN GM ° MIXTURES
o NO.4 SIEVE GRAVELS WITH
❑ N OVER 15%FINES CLAYEY GRAVELS,POORLY GRADED GRAVEL-SAND-CLAY
Z AA GC' MIXTURES
m
c9 _
w CLEAN SANDS SW WELL GRADED SANDS,GRAVELLY SANDS
SANDS WITH LITTLE
O 0 OR NO FINES SP ; POORLY GRADED SANDS,GRAVELLY SANDS
MORE THAN HALF
COARSE FRACTION
IS SMALLER THAN SANDS WITH SM SILTY SANDS,POOORLY GRADED SAND-SILT MIXTURES
N0.4 SIEVE OVER 15%FINES
SC CLAYEY SANDS,POORLY GRADED SAND-CLAY MIXTURES
INORGANIC SILTS AND VERY FINE SANDS,ROCK FLOUR,
ML SILTY OR CLAYEY FINE SANDS,OR CLAYEY SILTS WITH
SILTS AND CLAYS SLIGHT PLASTICITY
i INORGANIC CLAYS OF LOW TO MEDIUM PLASTICITY,
LIQUID LIMIT LESS THAN 50 CL GRAVELLY CLAYS,SANDY CLAYS,SILTY CLAYS,
O o _ LEAN CLAYS
N o
N ORGANIC CLAYS AND ORGANIC SILTY CLAYS OF LOW
w OL = PLASTICITY
z =
m
JH
INORGANIC SILTS,MICACEOUS OR DIATOMACIOUS FINE
w r SANDY OR SILTY SOILS,ELASTIC SILTS
z SILTS AND CLAYS
` INORGANIC CLAYS OF HIGH PLASTICITY,FAT CLAYS
LIQUID LIMIT GREATER THAN 50
ORGANIC CLAYS OF MEDIUM TO HIGH PLASTICITY,
ORGANIC SILTS
HIGHLY ORGANIC SOILS Pt PEAT AND OTHER HIGHLY ORGANIC SOILS
8 Modified California RV R-Value
® Split Spoon SA Sieve Analysis
Pushed Shelby Tube SW Swell Test
m Auger Cuttings TC Cyclic Triaxial
® Grab Sample TX Unconsolidated Undrained Triaxial
Sample Attempt with No Recovery TV Torvane Shear
CA Chemical Analysis UC Unconfined Compression
CN Consolidation (1.2) (Shear Strength,ksf)
CID Compaction WA Wash Analysis
DS Direct Shear (20) (with%Passing No.200 Sieve)
a PM Permeability Q Water Level at Time of Drilling
PP Pocket Penetrometer 1 Water Level after Drilling(with date measured)
a
m
SOIL CLASSIFICATION CHART AND KEY TO TEST DATA
E3RA
z Figure A-1
Z
Z
Q
c�
E3RA, Inc. BORING NUMBER HB-1
P.O. Box 44840 PAGE 1 OF 1
E3RA,nc Tacoma,Washington 98448 Figure A-2
Telephone: 2 5 3-5 37-94 00
Fax: 253-537-9401
CLIENT Dick and Patty Funk PROJECT NAME Funk Geotech Report
PROJECT NUMBER T09108 PROJECT LOCATION Mason County,Washington
DATE STARTED 12/7/09 COMPLETED 12/7/09 GROUND ELEVATION HOLE SIZE
DRILLING CONTRACTOR GROUND WATER LEVELS:
DRILLING METHOD Hand Auger AT TIME OF DRILLING —
LOGGED BY FER CHECKED BY JEB AT END OF DRILLING —
NOTES Lower stair alignment; 15 feet above top of rockery breakwall AFTER DRILLING —
W
a ~Lu =c7
W O MATERIAL DESCRIPTION
o a�
Qz
w
0.0
(SM)Light brown silty fine to medium sand(loose,damp to moist)(Colluvium)
a'
O
Z
O
m
O
Z
Q
S
m
O
O
H
U
W
0
O
w
t7
Y
2
LL
0 2.5
0
H
co
w
J
o SM
0
co
co
J
LL
m
O
U
Uj
W
LU
W
y
Q
0
O
U
Q
N_
C
5.0
0
n
N
H
0
N
D
f-
Z
6.0
Bottom of borehole at 6.0 feet.
a
f-
x
m
J
W
Z
W
E3RA, Inc. BORING NUMBER HB-2
P.O. Box 44840
3 Tacoma,Washington 98448 PAGE 1
E RAino. Telephone: 253-537-9400 Figure A-3
OF 1
Fax: 253-537-9401
CLIENT Dick and Patty Funk PROJECT NAME Funk Geotech Report
PROJECT NUMBER T09108 PROJECT LOCATION Mason County Washington
DATE STARTED 12/7/09 COMPLETED 1217/09 GROUND ELEVATION HOLE SIZE
DRILLING CONTRACTOR GROUND WATER LEVELS:
DRILLING METHOD Hand Auger AT TIME OF DRILLING —
LOGGED BY FER CHECKED BY JEB AT END OF DRILLING —
NOTES Middle stair alignment 35 feet above top of rockery breakwall AFTER DRILLING —
W
_ HW U
(L i W 00 0 a p MATERIAL DESCRIPTION
WW" a? U5
Q z c�
U)
0.0
(SM)Light brown silty fine to medium sand;somewhat better consolidated below 2 feet(loose,damp to moist)
(Colluvium)
'LL
cn
0
z
Ix
0
m
0
z
a
m
0
rn
F
U
W
H
O
w
Y
Z
LL
0 2.5
01
0
H
w
w
J
LL
o SM
0
0
h
m
Uj
J
LL
m
U
Uj
LU
W
Q
0
U
H
N_
Q
5.0
0
n
N
r
0
c7
ai
0
z
c�
6.0
Bottom of borehole at 6.0 feet.
a
s
m
J
W
Z
W
U
APPENDIX B
SLOPE STABILITY ANALYSIS
Geometry and Boundary Conditions
Problem: T09108 Stairway
210
200--
190-
180-
170 6 7
160- 5
150
140-
4
130-
120
9
110
100- _
90-
80--
70-
0 20 40 60 80 100 120 140 160 180 200
(Scale in Feet)
Geometry and Boundary Conditions
Problem: T09108 Stairway Static - FS Min = 1 .093
210
200
190
180
170 6 7
160 _ 5
150
i
140
4�.
130-
120-
3
110
100
90-
80
70
, .
0 20 40 60 80 100 120 140 160 180 200
(Scale in Feet)
Geometry and Boundary Conditions
Problem: T09108 Stairway Static - FS Min = 1 .093
210
200
190
180
170- 6 7
150r
�A'
r
140
4
130
3
100
90
80
70
0 20 40 60 80 100 120 140 160 180 200
(Scale in Feet)
Factor of Safety Distribution Histogram
14
c�
4
12
0
0 10.
L 8
6
0
a�
cm 4-
2-
0- 0 ,
1 2 3 4
Factor of Safety Values
result.out
PCSTABL6
by
Purdue University
1
--Slope Stability Analysis--
Simplified 3anbu, simplified Bishop
or Spencers Method of slices
Run Date:
Time of Run:
Run By:
Input Data Filename: run.in
Output Filename: result.out
Unit: ENGLISH
Plotted output Filename: result.plt
PROBLEM DESCRIPTION T09108 Stairway static
BOUNDARY COORDINATES
7 Top Boundaries
10 Total Boundaries
Boundary X-Left Y-Left X-Right Y-Right Soil Type
No. (ft) (ft) (ft) (ft) Below Bnd
1 0.00 100.00 50.00 100.00 1
2 50.00 100.00 50.10 106.00 2
3 50.10 106.00 60.00 116.00 2
4 60.00 116.00 100.00 146.00 2
5 100.00 146.00 115.00 161.00 2
6 115.00 161.00 118.00 166.00 1
7 118.00 166.00 200.00 166.00 1
8 50.00 100.00 65.00 100.00 1
9 65.00 100.00 90.00 120.00 1
10 90.00 120.00 115.00 161.00 1
1
ISOTROPIC SOIL PARAMETERS
2 Type(s) of soil
Soil Total Saturated Cohesion Friction Pore Pressure Piez.
Type Unit Wt. Unit Wt. Intercept Angle Pressure Constant Surface
No. (pcf) (pcf) (psf) (deg) Param. (psf) No.
1 120.0 125.0 100.0 34.0 0.00 0.0 1
2 110.0 115.0 100.0 30.0 0.00 0.0 1
1
Page 1
result.out
1 PIEZOMETRIC SURFACE(S) HAVE BEEN SPECIFIED
Unit Weight of Water = 62.40
Piezometric surface No. 1 specified by 2 Coordinate Points
Point X-Water Y-Water
No. (ft) (ft)
1 0.00 104.00
2 200.00 104.00
1
A Critical Failure surface Searching Method, using A Random
Technique For Generating Circular Surfaces, Has Been Specified.
400 Trial surfaces Have Been Generated.
20 surfaces Initiate From Each of 20 Points Equally Spaced
Along The Ground Surface Between X = 0.00 ft.
and X = 80.00 ft.
Each Surface Terminates Between X = 85.00 ft.
and X = 200.00 ft.
unless Further Limitations were Imposed, The Minimum Elevation
At which A Surface Extends Is Y = 0.00 ft.
5.00 ft. Line segments Define Each Trial Failure surface.
1
Following Are Displayed The Ten Most Critical Of The Trial
Failure surfaces Examined. They Are Ordered - Most Critical
First.
Safety Factors Are Calculated By The Modified Bishop Method
Failure surface specified By 23 Coordinate Points
Point X-surf Y-surf
No. (ft) (ft)
1 50.53 106.43
2 55.16 108.32
3 59.75 110.31
Page 2
NNNNNNNr-iHH -�r�--�rrrrr Z�
V61V7�WNrOl000Vd1ln�WN�--�O1000VQ1V�.pWN�-•gyp --�.
• n
rD
rwwwwwOwOw��wrNr�� p� A��i pp p p hQ n
rviQ101V0oVOrlDOOOr-VNW W� AV'7l.rIW WQ141uS �•
n NNNNrrF-�F-�rrrrF-+�--�
--� WNrol0M0 JM n4WNrOl0001401vt4
NN4 UnVHQ1 VVOI�rwNV7V t_nUq p�iWN N � > >f �
NVWlDUgM4Nt-nF �M t,.gvi 4.N 4ulw0Mrj M i.0HC> 4/1fD 0. �F n
00viI -4M00rONOr-iMa)v1tVOOlnNNtnO00W6n14o-jJ• J•
�r =D
NVIO0tllrN0lvlH004Q1VVlNlpONWF•-4v1W0r�ln1,0010 < O
PHr, �JOO rrt J
Q (D
C
a rrrrrrrrrrr
r D WWWIVNNF"rr00%0l0tDoMM 4VjMM
-l : rt VOlWl041NO0.A.OVW004O011VVW004
000000000000000000000000000�0 0
-3 Pi CL 0
rt w t�o X t000 400�0OOt"O4 ,l Ol 1N0oN
• !n'p n fD rt W 01Wut0V00Nl0l0Wrfv0000WrjM no(.0
(D � 0)
0
m :E =1 �t i
�Co O Ar w
000
OOOOOOOOOOOOO. . . . . . OOOOOOOO6 f�l N S
• V1 (D -1 rD Ol Ol Ql VI v7 In? IV IN fV 1-Ar r F"
00000000000000000000000000 Ili�C)144HOoviNl0m4H- om r1i-3
V• O V r(nIV 00 v7 W fV rN W Vl V r0)NM�.n W 0
lfl
ZTI N '� O00lOVWmVInNVOrrlOVWOOIVmm J
rD —j O O rh
w00000O00000OOOO000OOOOOOOOoE� n o
fD
v C
0OOoOOooOoo0Oo0O00000000000 w rt
J. IJ
n
—'-i O (D
ti� O
oOOOOopOOOOOooOOOooO000000OL=3n a
u (D O
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o 0 0 0 0 0 0 0 0 0 o Q
r, a
m a
. . . . . . O .. . . . . . . . . . . . . . . . . . . c
v
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 O r
S cn
I M
nC
M W N
-�< T A
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ~
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 v C to
-s
n
r,r s
—�O vu
O O O O O O O O O o O O O O O O O O O O O O O O L Q O O Oto
. v (D
O O O O O O O O O O O O O O O O O O O O O O O O O O O
n .n
NIVF-AF-AF-ANF-1F-AhaIJF-i -a zO —+ fl ►-�F�NF�F✓F�H+NN�-� z -0
FJ 0 lD W V M In.A W Iv F-A 0 lD W V M v1_p,W tV F a O J• C lD 00V a1 v'i.A W NF-'OlD 00V d1 In WNF-+ Q J
O rD
rt rD n rt r�o
(n rD cn
� � c
rt
-hnN���N���N�N x a
WWWNNNf-4N0001D1O0000V4M0) n I rp 000lDw 00� w Ln rD0IWOVW0a)N00JAOa1NVW00WlDAIaA hLA rt ValW0a)W tD �olfv0000 fi�
v'iv'i+1N00WQ100lplDVVi1-+VNO1l0N�a1V �/-7 13 N X -AmUn M0Wv7VVVmo.rjo0.AOlnID �-3 'p
1.V 00 V N W O�VI W►••1 V W lD aIA ut W V7 M N 4�- --h r0 lD 00WWWW Mtn 00 H-4 p.W VtO V 00W N Vl -h rD
r)
Jy.
J. 7� I 11
rD CL
J.
u u u
F"E"AHHrHF�HFu"F u-kF-IF�u HF1u H r HF-AF"HFJ -< JI A
a1viviLn ;z-k.A?WWWIvtvNNHHHHNHH n I W HHHHNHF-AF"HHHF�F-`HHHF-AHH
WlOLnN00?HOOV71VlDa)11HlDVal�Wh-�O �1V1 H a1a)a1V'�V7Lq� .pWWWNIV(VNHHF" I 07
a) H V W O V W 0 V4�-,H 00 a1 W H lD al A --h LA l �
lDlDlDHUglD1-nWNN.AVNlD00000•AOVM `/-3 N r• 000F1�00WOVtoAV'iM�oUjV•AHlDlD
�F+I0IOH14VH0WW00lp00W0101A0v100 -h N Oal0-Aa1l0HwQg001v1IWOIDONVP. fi lD C
fD n u —'
Q o 0
O- 00 Q rt
J. V1 J.
rt w
rD rt
su rD
v m
O tZ Q
rt rt
to C- to
J.
F�
00
V1
result.out
22 137.92 166.00
circle center At x = 29.2 ; Y = 239.3 and Radius, 131.1
-�� 1.130
Failure surface specified By 20 Coordinate Points
Point x-surf Y-Surf
No. (ft) (ft)
1 25.26 100.00
2 30.20 99.17
3 35.18 98.75
4 40.18 98.74
5 45.16 99.12
6 50.10 99.92
7 54.95 101.11
8 59.70 102.69
9 64.30 104.65
10 68.72 106.98
11 72.94 109.66
12 76.93 112.67
13 80.66 116.00
14 84.11 119.62
15 87.26 123.51
16 90.08 127.64
17 92. 55 131.99
18 94.66 136.52
19 96.40 141.21
20 97.14 143.86
circle center At x = 37.9 ; Y = 160.1 and Radius, 61.4
1.150
1
Failure Surface specified By 30 Coordinate Points
Point x-surf Y-surf
No. (ft) (ft)
1 21.05 100.00
2 26.02 99.40
3 31.00 99.04
4 36.00 98.91
5 41.00 99.02
6 45.99 99.37
7 50.96 99.95
8 55.89 100.77
9 60.78 101.81
10 65.61 103.09
11 70.38 104.60
Page 5
result.out
12 75.07 106.32
13 79.68 108.27
14 84.18 110.44
15 88.58 112.81
16 92.87 115.39
17 97.02 118.17
18 101.04 121.14
19 104.92 124.30
20 108.64 127.64
21 112.20 131.15
22 115. 59 134.83
23 118.80 138.66
24 121.83 142.64
25 124.66 146.76
26 127.30 151.01
27 129.73 155.38
28 131.96 159.85
29 133.97 164.43
30 134. 57 166.00
circle center At x = 36.2 ; Y = 204.6 and Radius, 105.7
1.161
Failure surface specified By 26 coordinate Points
Point x-surf Y-surf
No. (ft) (ft)
1 21.05 100.00
2 25.99 99.23
3 30.97 98.76
4 35.97 98.62
5 40.97 98.78
6 45.94 99.26
7 50.88 100.06
8 55.76 101.16
9 60. 55 102.57
10 65.25 104.27
11 69.84 106.27
12 74.29 108.55
13 78. 58 111.11
14 82.71 113.93
15 86.65 117.01
16 90.39 120.33
17 93.91 123.88
18 97.21 127.64
19 100.26 131.60
20 103.05 135.75
21 105. 58 140.06
22 107.83 144.53
23 109.80 149.12
24 111.47 153.84
25 112.84 158.64
26 112.90 158.90
circle center At x = 35.8 ; Y = 178.0 and Radius, 79.4
Page 6
result.out
1.166
1
Failure surface specified By 16 coordinate Points
Point X-Surf Y-surf
No. (ft) (ft)
1 50.53 106.43
2 55.51 106.84
3 60.44 107.69
4 65.26 108.99
5 69.95 110.72
6 74.47 112.88
7 78.77 115.43
8 82.81 118.37
9 86.58 121.66
10 90.03 125.27
11 93.14 129.19
12 95.87 133.38
13 98.22 137.79
14 100.16 142.40
15 101.66 147.17
16 101.80 147.80
circle center At X = 48.6 ; Y = 161.3 and Radius, 54.9
1.174
Failure Surface Specified By 15 coordinate Points
Point X-Surf Y-Surf
No. (ft) (ft)
1 71.58 124.68
2 76.49 125.64
3 81.29 127.02
4 85.96 128.80
5 90.47 130.98
6 94.77 133.53
7 98.83 136.44
8 102.64 139.69
9 106.15 143.25
10 109.34 147.09
11 112.19 151.20
12 114.69 155.53
13 116.80 160.07
14 118. 52 164.76
15 118.85 166.00
circle center At X = 62.8 ; Y = 182.5 and Radius, 58.4
Page 7
result.out
1.175
1
Failure surface specified By 16 coordinate Points
Point X-surf Y-surf
No. (ft) (ft)
1 37.90 100.00
2 42.82 99.14
3 47.81 98.89
4 52.80 99.26
5 57.70 100.24
6 62.45 101.81
7 66.97 103.96
8 71.19 106.64
9 75.05 109.82
10 78.48 113.45
11 81.45 117.47
12 83.90 121.83
13 85.79 126.46
14 87.11 131.28
15 87.82 136.23
16 87.83 136.87
circle center At X = 47.3 ; Y = 139.5 and Radius, 40.6
�-� 1.189
Failure surface specified By 17 coordinate Points
Point X-Surf Y-Surf
No. (ft) (ft)
1 71.58 124.68
2 76.54 125.31
3 81.45 126.24
4 86.30 127.47
5 91.06 129.01
6 95.71 130.84
7 100.24 132.96
8 104.62 135.36
9 108.85 138.03
10 112.90 140.96
11 116.76 144.14
12 120.41 147.56
13 123.85 151.19
14 127.04 155.03
15 130.00 159.07
16 132.69 163.28
17 134.19 166.00
circle center At X = 64.2 ; Y = 204.1 and Radius, 79.8
Page 8
result.out
1.198
1
Y A x I 5 F T
0.00 36.52 73.04 109.56 146.08 182.60
x 0.00 +---------+---------+------*w-+---------+---------+
5
4
. . . . .4
36.52 + . . . . . . .4
. . . . . .4
. . . . . . . .9471
. . . . . . . . . .4712*
. . . . . . . . .*'5471.2
A 73.04 + . . . . . . . . . . .547128.
- . . . . . . . . . . . . 543122.
- . . . . . . . . . . . .56631299
- . . . . . . . . . . . . . 55*3122.
- . . . . . . . . . . . . . .5. .11424*
- . . . . . . . . . . . . . . .55331227.
x 109.56 + . . . . . . . . . . . . . . . . .55311266.
. . . . . . . . . . . . . . . . . .5331226**
. . . . . . . . . . . . . . . . . . .5511.228
. . . . . . . . . . . . . . . . . . . . . 51102
- . . . . . . . . . . . . . . . . . . . . . . . .11
. . . . . . . . . . . . . . . . . . . . . . . .1
I 146.08 + . . . . . . . . . . . . . . . . . . . . . . . .
- . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . .
s 182.60 + . . . . . . . . . . . . . . .
- w . . . . . . . .
219.12 +
F 255.64 +
T 292.16 +
Page 9
Geometry and Boundary Conditions
Problem: T09108 Stairway Seismic - FS Min = 0.829
210-
200
190-
180-
170 6 7
160 5
150
140-
4
130 �
120
3 ;
110-
100P. IN
1
90
80-
70
0 20 40 60 80 100 120 140 160 180 200
(Scale in Feet)
Geometry and Boundary Conditions
Problem: T09108 Stairway Seismic - FS Min = 0.829
210-
200
190-
180
170 6 7
160 5
150-
y.. rx9 A,
140
4�
130 4
120
I s0 a
110 3
100-
90-
80-
70-
0 20 40 60 80 100 120 140 160 180 200
(Scale in Feet)
Factor of Safety Distribution Histogram
12
c�
CO
4-
0 10
0
8-
6
0
4
a
c
2
a�
o_
0.,
1 2
Factor of Safety Values
result.out
PCSTABL6
by
Purdue university
1
--Slope stability Analysis--
Simplified 3anbu, Simplified Bishop
or Spencers Method of Slices
Run Date:
Time of Run:
Run By:
Input Data Filename: run.in
Output Filename: result.out
Unit: ENGLISH
Plotted output Filename: result.plt
PROBLEM DESCRIPTION T09108 Stairway Seismic
BOUNDARY COORDINATES
7 Top Boundaries
10 Total Boundaries
Boundary x-Left Y-Left x-Right Y-Right Soil Type
No. (ft) (ft) (ft) (ft) Below Bnd
1 0.00 100.00 50.00 100.00 1
2 50.00 100.00 50.10 106.00 2
3 50.10 106.00 60.00 116.00 2
4 60.00 116.00 100.00 146.00 2
5 100.00 146.00 115.00 161.00 2
6 115.00 161.00 118.00 166.00 1
7 118.00 166.00 200.00 166.00 1
8 50.00 100.00 65.00 100.00 1
9 65.00 100.00 90.00 120.00 1
10 90.00 120.00 115.00 161.00 1
1
ISOTROPIC SOIL PARAMETERS
2 Type(s) of Soil
Soil Total Saturated Cohesion Friction Pore Pressure Piez.
Type Unit wt. Unit wt. Intercept Angle Pressure Constant Surface
No. (pcf) (pcf) (psf) (deg) Param. (psf) No.
1 120.0 125.0 100.0 34.0 0.00 0.0 1
2 110.0 115.0 100.0 30.0 0.00 0.0 1
1
Page 1
result.out
1 PIEZOMETRIC SURFACE(S) HAVE BEEN SPECIFIED
Unit weight of water = 62.40
Piezometric surface NO. 1 specified by 2 Coordinate Points
Point X-Water Y-Water
No. (ft) (ft)
1 0.00 104.00
2 200.00 104.00
A Horizontal Earthquake Loading Coefficient
of0.150 Has Been Assigned
A vertical Earthquake Loading Coefficient
Of0.000 Has Been Assigned
Cavitation Pressure = 0.0 (psf)
1
A Critical Failure surface Searching Method, using A Random
Technique For Generating Circular surfaces, Has Been specified.
400 Trial Surfaces Have Been Generated.
20 Surfaces Initiate From Each of 20 Points Equally spaced
Along The Ground surface Between x = 0.00 ft.
and x = 80.00 ft.
Each surface Terminates Between x = 85.00 ft.
and x = 200.00 ft.
unless Further Limitations were Imposed, The Minimum Elevation
At which A surface Extends Is Y = 0.00 ft.
5.00 ft. Line Segments Define Each Trial Failure surface.
1
Following Are Displayed The Ten Most Critical of The Trial
Failure surfaces Examined. They Are ordered - Most Critical
First.
Safety Factors Are Calculated By The Modified Bishop Method
Page 2
FJf-'FJNF-'FJF'FJ Z�
ValVIAwNNOlO0oV01tnAwNIJO -r•
• n
AAWf-+NI-+AAAAAAAAOAAfiQ m
n
O0OF"AVIvwWAAlnlnww0 M1 J. W
n IVNNNIJIJFJIJF-'FJF-'IJF-'F' ZO
wNF-AO1000V41lnAwNF"0(.0 MVJM 4n -WNIJ O J• c
H (D 3 1401AFJwNtntntntnAAwN IV rt NOltntnAAVtnWO0)Iv01t0NOV (D Q f)
N0101tnNOOtnNNlnO00wtnVO J• LA
00 P.m14 nNl0ONwF-ltnWOAlnl00'n < j O
J.
vll �IO�JAooOo�viwv�ujwUq tA rt p rD h
fi
0 ru Pr
'--' O D WWWNNNNF-'!-'OOl0loto 000VVQ1011nlnln ^x (nD
0 a) N r+ V0w100N00Ao-1w00Ao0rv14w00AtOtnO �file
• (A-0 n rD 0000000000000CD00CD0-0 srt Pi x N -
Wtn0V0NlfllflWHrJM0WNJ0tnOl0ln0W00000000000000000� D -3 a, fi
fD
n
O J.
TI :E 3 ]h
J.
CO O !1 )F w
O r) rt rt J 00 rD
IZ
OOOOOOOOOOOOOOOOOO'rf n rD s F�NF-'�,�,�,�,F,F-'NF,F-,F.,F,F-,F,F,1-,F,F,F•,F,F, �
In (D -3 rD A 010101tnlnVIAAAWwWNNNNF"F-'F-'F-AF-'0O W
00000000000000000 F•+VAOVAF- 00tnNtp01AF-'tOO)Jh.NO0001 -h(n l< Z
V• OVFJOINWtnwNF-'NWl!'IVF-'01FJ00tnwwWA `/-3 N to
0 M LO'4 W M-4UnNV0I--'F-+IOVWMrJ0)00FJNW fi W c
to n Z m N J
(D - 00 V II (l rt
W000000OOOOOOoOOOO(an o 0
0000000000000000o fD J w
c
w >Z rt
O tail O ¢'
r+
0 0 0 0 00 0 0 00 0 0 0 0 0 0 0(fi n (D
v (D
O O O O O O O O O O O O O O O O O Q
O
J.
3
~ rt nwmm141400)tnA WI-' m Q N
0)L000wF-'01tnWt0lntOWtJ7uJNN0cr0 W J.
(.0lOtnWWOQ)N00WVONlOWFJ01In Z -S
I--,NVO01l0AA0 -0, 14 o0 MF"AA O S rt fn
3-0
n c
r. rD N N
J< 7 A
00000000000000000�(D fD ~
. . . . v N to
O O O O O O O O O O O O O O O O O c
I
n
r,r 3-
-�O (11
0000000000000CD000(O_tQ
vrD
O O o 0 0 0 0 0 0 0 0 0 0 0 0 0 0
result.out
18 3.9 7501.2 0.0 0.0 0.0 0.0 1125.2 0.0 0.0
19 0.1 225.0 0.0 0.0 0.0 0.0 33.7 0.0 0.0
20 3.0 6406.2 0.0 0.0 0.0 0.0 960.9 0.0 0.0
21 0.7 1612.2 0.0 0.0 0.0 0.0 241.8 0.0 0.0
22 3.8 7581.3 0.0 0.0 0.0 0.0 1137.2 0.0 0.0
23 3.7 5965.8 0.0 0.0 0.0 0.0 894.9 0.0 0.0
24 3.6 4370.2 0.0 0.0 0.0 0.0 655.5 0.0 0.0
25 3.6 2799.1 0.0 0.0 0.0 0.0 419.9 0.0 0.0
26 3.5 1257.1 0.0 0.0 0.0 0.0 188.6 0.0 0.0
27 1.1 82.4 0.0 0.0 0.0 0.0 12.4 0.0 0.0
Failure surface specified By 22 Coordinate Points
Point X-Surf Y-Surf
No. (ft) (ft)
1 54.74 110.68
2 59.62 111.75
3 64.46 113.00
4 69.25 114.44
5 73.98 116.06
6 78.65 117.86
7 83.24 119.83
8 87.76 121.98
9 92.19 124.29
10 96.53 126.78
11 100.77 129.43
12 104.91 132.23
13 108.93 135.20
14 112.85 138.31
15 116.64 141.57
16 120.30 144.97
17 123.83 148.51
18 127.22 152.19
19 130.47 155.99
20 133.58 159.91
21 136. 53 163.94
22 137.92 166.00
Circle center At X = 29.2 ; Y = 239.3 and Radius, 131.1
��- 0.863
1
Failure Surface specified By 19 Coordinate Points
Point X-surf Y-surf
No. (ft) (ft)
1 58.95 114.94
2 63. 52 116.97
3 68.03 119.12
4 72.48 121.40
5 76.87 123.79
6 81.20 126.30
7 85.45 128.93
8 89.63 131.67
Page 4
result.out
9 93.74 134.52
10 97.77 137.48
11 101.71 140.55
12 105. 58 143.73
13 109.35 147.01
14 113.04 150.39
15 116.63 153.86
16 120.13 157.44
17 123.53 161.10
18 126.83 164.86
19 127.78 166.00
circle center At X = -14.1 ; Y = 285.3 and Radius, 185.4
��- 0.874
Failure surface specified By 30 coordinate Points
Point X-Surf Y-surf
No. (ft) (ft)
1 21.05 100.00
2 26.02 99.40
3 31.00 99.04
4 36.00 98.91
5 41.00 99.02
6 45.99 99.37
7 50.96 99.95
8 55.89 100.77
9 60.78 101.81
10 65.61 103.09
11 70.38 104.60
12 75.07 106.32
13 79.68 108.27
14 84.18 110.44
15 88. 58 112.81
16 92.87 115.39
17 97.02 118.17
18 101.04 121.14
19 104.92 124.30
20 108.64 127.64
21 112.20 131.15
22 115.59 134.83
23 118.80 138.66
24 121.83 142.64
25 124.66 146.76
26 127.30 151.01
27 129.73 155.38
28 131.96 159.85
29 133.97 164.43
30 134. 57 166.00
circle center At X = 36.2 ; Y = 204.6 and Radius, 105.7
�-� 0.902
Page 5
result.out
1
Failure surface specified By 20 Coordinate Points
Point x-surf Y-surf
No. (ft) (ft)
1 25.26 100.00
2 30.20 99.17
3 35.18 98.75
4 40.18 98.74
5 45.16 99.12
6 50.10 99.92
7 54.95 101.11
8 59.70 102.69
9 64.30 104.65
10 68.72 106.98
11 72.94 109.66
12 76.93 112.67
13 80.66 116.00
14 84.11 119.62
15 87.2-6 1-23.51
16 90.08 127.64
17 92.55 131.99
18 94.66 136.52
19 96.40 141.21
20 97.14 143.86
Circle center At x = 37.9 ; Y = 160.1 and Radius, 61.4
0.903
Failure surface specified By 26 Coordinate Points
Point x-surf Y-surf
No. (ft) (ft)
1 21.05 100.00
2 25.99 99.23
3 30.97 98.76
4 35.97 98.62
5 40.97 98.78
6 45.94 99.26
7 50.88 100.06
8 55.76 101.16
9 60.55 102.57
10 65.25 104.27
11 69.84 106.27
12 74.29 108. 55
13 78.58 111.11
14 82.71 113.93
15 86.65 117.01
16 90.39 120.33
17 93.91 123.88
18 97.21 127.64
19 100.26 131.60
Page 6
result.out
20 103.05 135.75
21 105.58 140.06
22 107.83 144.53
23 109.80 149.12
24 111.47 153.84
25 112.84 158.64
26 112.90 158.90
Circle Center At X = 35.8 ; Y = 178.0 and Radius, 79.4
�-� 0.908 ---
1
Failure surface specified By 21 Coordinate Points
Point X-Surf Y-surf
No. (ft) (ft)
1 54.74 110.68
2 59.07 113.17
3 63.39 115.70
4 67.69 118.25
5 71.96 120.85
6 76.21 123.48
7 80.44 126.14
8 84.65 128.84
9 88.84 131.58
10 93.00 134.34
11 97.15 137.15
12 101.26 139.98
13 105.36 142.85
14 109.43 145.75
15 113.47 148.69
16 117.50 151.66
17 121.49 154.66
18 125.47 157.70
19 129.42 160.77
20 133.34 163.87
21 135.99 166.00
Circle Center At X = -245.6 ; Y = 639.2 and Radius, 607.8
0.915 ***
Failure surface specified By 16 Coordinate Points
Point X-surf Y-surf
No. (ft) (ft)
1 50.53 106.43
2 55.51 106.84
3 60.44 107.69
4 65.26 108.99
Page 7
result.out
5 69.95 110.72
6 74.47 112.88
7 78.77 115.43
8 82.81 118.37
9 86.58 121.66
10 90.03 125.27
11 93.14 129.19
12 95.87 133.38
13 98.22 137.79
14 100.16 142.40
15 101.66 147.17
16 101.80 147.80
Circle Center At X = 48.6 ; Y = 161.3 and Radius, 54.9
-�� 0.919
1
Failure Surface Specified By 24 Coordinate Points
Point X-surf Y-Surf
No. (ft) (ft)
1 50.53 106.43
2 54.83 108.98
3 59.12 111.54
4 63.41 114.12
5 67.69 116.71
6 71.95 119.31
7 76.21 121.93
8 80.47 124. 56
9 84.71 127.20
10 88.94 129.86
11 93.17 132.54
12 97.38 135.22
13 101. 59 137.93
14 105.79 140.64
15 109.98 143.37
16 114.16 146.11
17 118.33 148.87
18 122. 50 151.64
19 126.65 154.42
20 130.79 157.22
21 134.93 160.03
22 139.06 162.85
23 143.17 165.69
24 143.62 166.00
Circle Center At X = -723.8 ; Y = 1419.1 and Radius, 1524.0
0.920
Failure surface specified By 15 Coordinate Points
Page 8
result.out
Point x-surf Y-Surf
No. (ft) (ft)
1 71.58 124.68
2 76.49 125.64
3 81.29 127.02
4 85.96 128.80
5 90.47 130.98
6 94.77 133. 53
7 98.83 136.44
8 102.64 139.69
9 106.15 143.25
10 109.34 147.09
11 112.19 151.20
12 114.69 155.53
13 116.80 160.07
14 118.52 164.76
15 118.85 166.00
Circle Center At x = 62.8 ; Y = 182.5 and Radius, 58.4
0.924
1
Y A x I S F T
0.00 36.52 73.04 109. 56 146.08 182.60
x 0.00 +---------+---------+------*w-+---------+---------+
. . . . .4
. . .4
36.52 + . . . . . . .4
- . . . . .4
- . . . . . . . . .481
- . . . . . . . . . .4812*
. . . . . . . . .*'458173
A 73.04 + . . . . . . . . . . .458130.
- . . . . . . . . . . . .452133.
- . . . . . . . . . . . .466213.
- . . . . . . . . . . . . .44*2133.
- . . . . . . . . . . . . . .4. .11535*
- . . . . . . . . . . . . . . .44221338.
x 109.56 + . . . . . . . . . . . . . . . . .44211366.
. . . . . . . . . . . . . . . . . .4221336=-*
. . . . . . . . . . . . . . . . . . .44117330
. . . . . . . . . . . . . . . . . . . . .41173
. . . . . . . . . . . . . . . . . . . . . . . .11
1
I 146.08 + . . . . . . . . . . . . . . . . . . . . . . .9
. . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . .
Page 9
result.out
- . . . . . . . . . . . . . . . . .
S 182.60 + . . . . . . . . . . . . . . .
219.12 +
F 255.64 +
T 292.16 +
Page 10
NOTE: NO SETBACK FROM
VEGETATED BUFFER AREA OR
LANDSLIDE HAZARD AREA
RECOMMENDED FOR PROPOSED
STAIRWAY, 1 — — _679.8' — — —
r
EXISTING
/ fli PUDDLE /
I t
%0
rn
1 PROPOSED �.
i STAIRCASE 0
Cb �.
5 1
N
lF — — - - - - — mac,
EXIST,
D 'AII�I IELD Q ti
J ,CN %S W E
EXISTING
HOME '2
mot.. ,A
I / / `
f
698,2' — — — — — —
LANDSLIDE HAZARD AREA AND
VEGETATED BUFFER AREA
HAND BORING LOCATION
HB-1 PROJECT: 462 E Stretch Island Dr S
® E3RAInc. Stretch Island, Washington
NOTE: 201 - 160th St. S SHEET TITLE: Site and Exploration Plan
60 0 60 120 Suite 401
BOUNDARY AND TOPOGRAPHY ARE BASED ON Tacoma, WA 98444 DESIGNER: CRL JOB NO.T09108
MAPPING PROVIDED TO E3RA AND OBSERVATIONS MADE
IN THE FIELD. THE INFORMATION SHOWN DOES NOT SCALE IN FEET 253-537-9400 PRAWN BY: CRL SCALE: 1"=60'
CONSTITUTE A FIELD SURVEY BY E3RA. 253-537-9401 fax CHECKED BY: JEB FIGURE:2
www.e3ra.com MATE: 12/9/09 FILE: T09108.dwg
A (EAST)
70
A' (WEST)
70
i
I \ ESTIMATED F IIN PILE
L❑CATI❑NS <ITYP.)
50
i
50
+ HB-2
I
40
, 40
MEDIUM DESE T I
❑ DENSE
30 $��❑ MEDIUM SILTY)
IN..IEBBD !- i
FINE SAND SILT
120 PCF j 30
20 I CO �LIVIUM
I C=10 20
30° I I f
10 I �
10
E TIMATED CONTACT LIN
I
i
s
0 20 '
40
60 80 '
100 120
E3RA PROJECT.- 462 E Stretch Island Dr S
Inc. Stretch Island, Washington
10 0 10 20 201 - 160th St. S SHEET TITLE: Geologic Profile
Suite 401
SCALE IN FEET Tacoma, WA 98444 DESIGNER: CRL JOB NO.T09108
253-537-9400 DRAWN BY: CRL SCALE: 1"=10'
253-537-9401 fax CHECKED BY: JEB FIGURE.-3www.e3ra.com DATE: 12i9/Og
FILE: T09108.dwg