HomeMy WebLinkAboutGEO2010-00002 - GEO Geological Review - 1/14/2010 RECEIVED
JAN 2 0 20M
` 426 W. CEDAR SL
Geotechnical Report
Prepared for:
Steve & Jim Kessler
Site:
241 NE Alder Creek Lane
Belfair, Washington
Date:
January 14, 2010
by:
Geotechnical Investigations Group
To 3EKEPT IN THE
PR
33 � -�� -oo906
241 NF Alder Creek Lane. Seifair,Washington
CONTACT INFORMATION
CLIENT INFORMATION
Client: Steve Kessler
' Alternate Contact: Jim Kessler
Telephone: (541) 504-5234
' Cellular: (541)410-9599
Email Address: stevesally@bendcable.com,jkblackwood@comcast.net
' Mailing Address: 2249 Hawk Owl Court
Redmond, Oregon 97756
Site Address: 241 NE Alder Creek Lane
Belfair,Washington 98528
Parcel Number: 123325000906
GPS Location: N471 26.020', W 122, 50.057'
PREPARER INFORMATION
Project: 10-0020
Contact: Lance Levine or Blaise Jelinek
Telephone: (360) 923-2561
Facsimile: (360)754-1893
Cellular(Lance) (360)259-7660
Cellular(Blaise) (360)481-7062
Email Address: blaisejelinek@gmail.com, Iglgeological@gmail.com
Geotechnical Investigations Group 2
5933 54`h Way SE, Lacey, Washington 98513
Office (360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek Lane, Belfair,Washington
TABLE OF CONTENTS
CONTACTINFORMATION..........................................................................................................................................2
CLIENTINFORMATION....................................................................................................................................................................2
PREPARERINFORMATION...............................................................................................................................................................2
' INTRODUCTION ..........................................................................................................................................................4
SITECONDITIONS......................................................................................................................................................5
GENERAL.....................................................................................................................................................................................5
SURFACECONDITIONS...................................................................................................................................................................6
SEPTICDRAINFIELD.......................................................................................................................................................................8
ROOF DRAINS EASTERN SIDE OF RESIDENCE..................................................................................................................................9
THE NORTH SIDE OF THE RESIDENCE ROOF DRAIN AND YARD DRAIN............................................................................................... 10
ROOF DRAINS WESTERN SIDE OF RESIDENCE...............................................................................................................................10
BELOWTHE RETAINING STRUCTURE.............................................................................................................................................12
GEOLOGICALLYHAZARDOUS AREAS.................................................................................................................14
LANDSLIDE HAZARD CLASSIFICATION............................................................................................................................................14
SEISMIC HAZARD CLASSIFICATION................................................................................................................................................14
EROSION HAZARD CLASSIFICATION...............................................................................................................................................15
SITEGEOLOGY...........................................................................................................................................................................15
SITESOILS.................................................................................................................................................................................16
SUBSURFACEEXPLORATIONS.......................................................................................................................................................17
SUBSURFACE CONDITIONS...........................................................................................................................................................17
SOILLOG...................................................................................................................................................................................17
SLOPE STABILITY AND ANALYSIS...................................................................................................................................................18
RECOMMENDATIONS FOR BUILDING SETBACK................................................................................................................................21
LIQUEFACTIONHAZARD...............................................................................................................................................................21
SEISMICHAZARD........................................................................................................................................................................22
CONCLUSIONS AND RECOMMENDATIONS..........................................................................................................23
RECOMMENDATIONS FOR SUITABILITY OF ONSITE SOILS AS FILL......................................................................................................23
RECOMMENDATIONS FOR EROSION CONTROL................................................................................................................................24
RECOMMENDATIONS FOR STRUCTURAL FILL..................................................................................................................................24
RECOMMENDATIONS FOR FOUNDATION SUPPORT...........................................................................................................................24
RECOMMENDATIONS FOR CUT AND FILL SLOPES............................................................................................................................25
RECOMMENDATIONS FOR SITE DRAINAGE......................................................................................................................................25
SEPTICIMPACT...........................................................................................................................................................................25
REPORT LIMITATIONS AND GUIDELINES FOR USE............................................................................................26
CONTRACTORS ARE RESPONSIBLE FOR SITE SAFETY ON THEIR OWN CONSTRUCTION PROJECTS........................................................26
READTHESE PROVISIONS CLOSELY........................... ..................................................................................................................26
GEOTECHNICAL,GEOLOGIC,AND ENVIRONMENTAL REPORTS SHOULD NOT BE INTERCHANGED..........................................................26
CLOSING....................................................................................................................................................................................26
APPENDIX.....................................................................................................................................................................
REFERENCES.................................................................................................................................................................................11
LABORATORYRESULTS..................................................................................................................................................................IV
WELLLOGS..................................................................................................................................................................................VI
CONTRIBUTING ROOF AREAS CALCULATIONS.................................................................................................................................VIII
SEPTICAS BUILT..........................................................................................................................................................................IX
FIGURE1 VICINITY MAP.................................................................................................................................................................X
FIGURE 2 SITE PLAN ATTACHED
FIGURE 3 CROSS SECTION ATTACHED
FIGURE 4 EXISTING SOLDIER PILE RETAINING WALL ATTACHED
Geotechnical Investigations Group 3
5933 54" Way SE, Lacey, Washington 98513
Office(360)923-2561 Cellular(360)481-7062
241 NE Alder Creek !_anp. Belfair.Washington
INTRODUCTION
This report summarizes the results of our geotechnical consulting services. The existing structure (single-family
residence) is under a Do Not Occupy order (Dec-17-2007) from the Mason County Department of Community
Development. The emergency activity response is due to the onsite landsliding of saturated soil. Earth movement
occurred approximately 2 years ago destroying the wing section of an existing soldier pile retaining wall, see photo
below.
The subject site is located at 241 NE Alder Creek Lane, Belfair, Washington 98528. The report has been
commissioned by Steve&Jim Kessler.
Scarp ,
Wing Wa!I
Vie Looking g Southwest I
The GPS location of the site is shown relative to the surrounding area on the Vicinity Map, Figure 1 (near the end of
this report). The layout of the site is shown on the Site Plan, Figure 2. A cross section is presented as Figure 3.
Figure 4 is the approximate as-built drawing for the existing soldier pile retaining wall.
The focus of the investigation was to determine the cause of failure, the resulting impact on the existing structure,
and possible remediation. The report concludes with drainage recommendations to reduce the probability of future
failures. Specifically, our scope of services for this project includes the following:
• Review the existing site-specific geotechnical report by Krazan and Associates, Inc. (November 15, 1999),
the soldier pile design by Civiltech Corporation (May 30, 2000) and the addendum by Krazan and
Associates, Inc. (February 3, 2000).
• Review the published geologic, hydrogeological, and geotechnical data for the site area. Inspection of
aerial photographs and LiDAR images.
• A geologic reconnaissance of the site area and surrounding vicinity.
• Site plan and cross section development-
• Investigation and identification of shallow subsurface conditions at the site by characterizing the exposed
soil and by reviewing published well logs.
• Laboratory grain size analyses for soil samples collected from the site.
• Evaluation of the landslide, erosion, and seismic hazards at the site per the Mason County Critical Areas
Ordinance regulations (December 27, 2006).
Geotechnical Investigations Group 4
5933 54'h Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
241 NF Alter Creek Lane. Belfair,Washington
• Geotechnical recommendations for site grading including site preparation, subgrade preparation, fill
placement criteria (including hillside grading), temporary and permanent cut and fill slopes, typical drainage
and erosion control measures.
17.01.100E5(1) --A discussion of general geologic conditions, specific soil types, ground water conditions,
the upslope geomorphology and location of upland waterbodies and wetlands, and history of landslide
activity in the vicinity.
SITE CONDITIONS
GENERAL
The site is located along the hills east of the eastern portion of the Hood Canal in Mason County. The parcel (1.99
acres) is situated on a point overlooking the northwest to west trending stream drainage. The site is approximately
'/2 mile south of the center of Belfair, Washington. The site is accessed from the three existing driveways off NE
Alder Creek Lane; the nearest cross street is State Highway 3 (WA-3).
A site reconnaissance was conducted on November 4, 2008. An additional site reconnaissance was conducted on
April 29 and May 19, 2009. Test pits were sampled by Jelinek and Levine on May 19, 2009. A final site inspection
occurred on December 15, 2009 to confirm that no significant changes have occurred at the site over the past year.
The site is currently bordered by a residential parcel to the northwest. Forested (undeveloped) parcels are located
to the north, east, and south (see Figure 2 Site Plan).
The current single-family residence is uninhabited. The eastern slope demonstrates signs of landsliding,
specifically the block slump type, see photo below. Therefore, Mason County requires that a geotechnical report be
prepared in accordance with the Critical Areas Ordinance(17.01.100E1a).
r
View Looking West
A soldier pile retaining wall is located 9 feet to the northeast of the residence, see photo next page. The wall was to
protect the existing residence. The original geotechnical report was by Krazan and Associates, Inc. (November 15,
1999). The design was reviewed and stamped by Civiltech Corporation (May 31, 2000). The retaining wall was
completed in 2000 by DBM Contractors, Inc. A copy of the available geotechnical report and retaining wall design
may be obtained from Mason County at:
http://www.co.mason.wa.us/forms/Community_Dev/research_request.pdf
Geotechnical Investigations Group 5
5933 54"'Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
i
241 NE Alder Creek Lane, Belfair,Washington
WAMW
i Looking Southeast
The existing retaining wall was examined for signs of deflection and failure. All support pile was measured to be
plumb. The wood lagging appear unaffected- no drainage material was visible though the gaps. Other than the
wing section, the wail does not appear to be adversely impacted by the new slumping. Since the wall has not
moved,then the existing residence has not been impacted by the new slumping.
The final site inspection occurred on December 15, 2009. The septic design as built drawing was provided by the
client, see appendix. No changes were observed.
SURFACE CONDITIONS
The subject parcel is located along a west, north, and east sloping hillside. The topographic ridge follows the upper
portion of Alder Creek Lane to the south of the parcel. No upland water bodies or wetland features were observed
during the site reconnaissance or through the inspection of aerial photographs within 1,000 feet of the parcel.
The onsite structures are located on multiple benches. The single-family residence is situated on the uppermost
eastern portion. The garage is located to the northwest and downhill of the residence. A sauna, shed, and pond
are located in the southwestern portion of the site.
Site elevations range from 120 feet in the north to approximately 200 feet in the southeast. The general topography
of the site area indicates that drainage flows toward the west, north, and east from the existing residence towards
the northern drainage, see photo below.
View Looking Northeast
Geotechnical Investigations Group 6
5933 541h Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek Lane, Belfair,Washington
The site was inspected before and after the wet season. The � _ I w
purpose of the site inspections was to physically observe the «•
property and adjacent properties and to identify geologic and K '
hydrogeologic conditions. Visual observations were documented
and photographed. Site-specific features were mapped and the
vegetation noted.
The site is well vegetated with native and introduced flora species.
A manicured lawn surrounds the residence. From the residence, s"
the site slopes to the west, north, and east. Sections of the site
slopes are nearly 48 percent. Slump scarps are located along the
top of the eastern slope (see photo right). The existing residence is
located where the slope ranges from 0 to 2 percent. The existing
septic drainfield is located in the level lawn area to the south of the
residence; the as-built drawing is located in the appendix. An
infiltration gallery was located near the scarp. The photo to the Infiltration Gallery
right has been illustrated to show infiltration lines.
sy.
View Looking Northwest
46
'ems
The lower eastern slope exhibits evidence of
<p older landsliding. The sliding most likely
:.' occurred between 10 and 20 years ago; re-
vegetation has occurred over most of the
►_ landslide debris. In multiple locations, younger
trees are straight and vertical. Recent shallow
block slumping was observed along the
eastern slope; the headscarp has not re-
vegetated. Two tight-line pipes terminate near
the new slump; pipe two (2) is shown in the
photo left.
View Looking North (2)
Geotechnical Investigations Group 7
5933 54`h Way SE, Lacey, Washington 98513
Office (360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek Lane, Belfair,Washington
SEPTIC DRAINFIELD
The subsurface infiltration features were identified at the site and plotted on the lawn. The septic drainfield is
located to the south of the primary residence. The primary septic drainfield measures approximately 1000 square
feet and is approximately 30 feet from the scarp. The septic drainfield is not impacting the landslide hazard area.
See the as-built drawing located in the appendix.
INFILTRATION GALLERY
The week of January 101", Jim Kessler unearthed a drain to the southeast of the residence. Roof drains(1) and (2)
entered the box; a single pipe exits to the south leading to the infiltration gallery. The gallery is constructed of
corrugated pipe perforated embedded in gravel.
An infiltration gallery is located to the southeast of the residence near the scarp. See photo below. The gallery
receives 1129 square feet from the contributing roof areas. This gallery directly added water to the landslide.
s ,
T.
Infiltration Gallery
Soil subject to
saturation
Scarp
View Looking South
Along the outside (east face) of the drain box, a corrugated pipe (2b) leads towards the slump. The pipe is blocked
up with fabric and not connected into the drain box.
Geotechnical Investigations Group 8
5933 54"'Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek Lane, Belfair,Washington
ROOF DRAINS EASTERN SIDE OF RESIDENCE
The roof drains are connected to black flexible pipes that
are buried beneath the lawn. Four roof drainpipes were view Looking Northwest
identified that convey roof water to the east.
r
The southern most drainpipe (1) transports water from thedownspout from the areas indicated in green in the sketchDrain 2)
to the left, on the south side of the
residence. This downspout collects i (2b)
p I To Infiltration Gallery
rain from a surface area of 791
square feet of roof. The effluent
(discharge) of this line was not
observed entering the drain.
The downspout on the southeastern corner of the residence (2) is connected to the drain. This downspout collects
rain from a surface area of 338 square feet on the �� ,'N- r
southeastern portion of the upper roof. Exiting the drain,
the blocked discharge line (2b) ends at the failure. Very dry ='
sand was found inside of the pipe. A significant cloudburst
occurred during the site reconnaissance, such that one (2b)
would assume flow would occur in a tight line discharge
line. No discharge occurred from drainpipe (2b) within a
reasonable time of the storm event. Probing revealed dry sand and gravel five "
feet from the end of the exposed drainpipe. The blockage indicates the pipe has View Looking North
become disconnected or ruptured.
H.° .
The downspout located at the alcove south of northeastern corner of the .�
residence (3) is connected to a buried black drain line. The 4 ► " -
drain line diverts water toward the retaining structure. A
tight line outlet was not identified for this feature. The roof
area of the water collected via this downspout is 338 square (3)
feet.
View Looking North
The roof drain line on the east side of the residence (4) is located in the
northeastern corner of the structure. The drain line was
detected in the subsurface and found to divert water toward 4
the retaining structure-, an outlet for this line was not 3)verified. The roof area of the water collected via this 1[(
downspout is 64 square feet.
View Looking North
Geotechnical Investigations Group 9
5933 54`h Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek i ane, Belfair,Washington
THE NORTH SIDE OF THE RESIDENCE ROOF DRAIN AND YARD DRAIN
Two drains are located on the north side of the residence: a
roof drain (6) and a yard drain (5) see
4,4m` photo right. The roof drain has a
contributing area of 626 square feet. The
yard drain appears to gather water from
approximately 350 square feet.
Both of the lines are tight-lined to the base of the northern
slope. The terminus of the drain lines is downslope from the
soldier pile retaining wall and uphill from the old logging road.
The current discharge location is indicated on Figure 2 Site
Plan.
'0 .
.. ape i�..: '• *,ky
wi�Ol� ,N
iR
View Looking Northeast
View Looking South
ROOF DRAINS WESTERN SIDE OF RESIDENCE
A gutter system controls and gathers the water primarily from
the porch and the crows nest. The '
combined contributing area is ., .z
approximately 240 square feet.
Water from the gutter system is
dispersed upon the lawn on the -
western side of the residence " �►,r..'
approximately four feet from the porch and twelve feet from the
foundation.
The western side of the residence is characterized by road
cuts into the slope allowing access to the various outbuildings
on the property. This slope is well vegetated, areas devoid of
vegetation are concrete or asphalt. View Looking Northeast
Geotechnical Investigations Group 10
5933 54`h Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek Lane. Belfair,Washington
Downslope from the residence are a series of road cuts that zigzag down the hillside to the garage and to the
steam room. The soil observed in the upper road cut on the western side of the residence is well vegetated and
appears stable.
A seep was observed south of the shed and north of Alder Creek Lane. Skunk cabbage marks the seepage
location, see photo the below.
s
5 _
r. Seep . `^*7� +"M`
Wq-ookIrT9SOUth •�
In the southwest portion of the site and adjacent to the
sauna, minor ponding was observed (outlined in red
right). Additionally, the hillside was saturated during our -
site visits on April 29 and May 19, 2009. A final site
inspection occurred on December 15, 2009 to confirm
that no significant changes have occurred at the site over
the past year.
Seep
#.
View Looking West
Geotechnical Investigations Group 11
5933 54`h WaySE, Lacey, Washington 98513
Y 9
Office(360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek Lane, Belfair,Washington
p . '
BELOW THE RETAINING STRUCTURE
An old logging road (access road) parallels the
retaining wall; see photo right. The road was most �. s
recently used to construct the retaining wall.
Shallow failures have occurred and the road cut
has slumped.
y View Looking South ,
Trees on the slope are relatively straight growing but all
a t leaning in different directions, see photo left. Offsite to
the north, a weir forms a pond, see photo below.
040
View Looking East
v ,
ri r'l1M View Looking East
Li
Geotechnical Investigations Group 12
5933 54`h Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
241 NF Alder Creek Lane. R 9 a f '
1 arr,Washington
During the November 4, 2008 site visit, no seepage was observed along eastern the site slopes. Far to the north,
surficial flow was observed in the northern drainage--a class 5 stream. During the 2009 site visits, seepage was
observed flowing from two locations in the southwestern portion of the parcel. No surface water flow or ponding
was observed at the existing building location. No evidence of active surface erosion was observed within 200 feet
the existing building location with the exception of the upper(recent) slump.
The subject parcel is mostly vegetated with huckleberry, blackberry, Scot's broom, sword fern bracken fern,
horsetail fern, salal, holly, ivy, skunk cabbage, trillium, and Oregon grape as well as cedar, fir, madrone, hemlock,
alder, and maple trees. See photo below of the lower eastern slope.
�•- �4a .A- !Imo. • }• . t• ,��M
w Looking South ,
17.01.100E5(2) --A site plan which identifies the important development and geologic features.
A site plan is attached as Figure 2 Site Plan at the end of this report.
17.01.100E5(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.
A site plan is attached as Figure 2 Site Plan at the end of this report.
17.01.100E5(3)--Locations and logs of exploratory holes or probes.
The locations of the soil logs (SL-1 and SL-2) are labeled on the Figure 2 Site Plan at the end of this report.
17.01.100E5(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.
The boundaries of the landslide hazard area and appropriate geology are demarcated on Figure 2 Site Plan at the
end of this report. No new structures are proposed. Therefore, buffer and setbacks are not included in the site
plan.
17.01.100E5(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.
A cross-section is attached to this report as Figure 3 Cross-section.
Geotechnical Investigations Group 13
5933 54`h Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek lane, Belfair,Washington
GEOLOGICALLY HAZARDOUS AREAS
LANDSLIDE HAZARD CLASSIFICATION
The Mason County Critical Areas Ordinance(17.01.100A1) defines a landslide hazard area as:
The following shall be classified as Landslide Hazard Areas.
a. Areas with any indications of earth movement such as debris slides, earthflows, slumps and rock falls (see
figure F.100).
b. Areas with artificial oversteepened or unengineered slopes, i.e. cuts or fills.
c. Areas with slopes containing soft or potentially liquefiable soils.
d. Areas oversteepened or otherwise unstable as a result of stream incision, stream bank erosion, and
undercutting by wave action.
e. Slopes greater than 15% (8.5 degrees) and having the following.
i. Hillsides intersecting geologic contacts with a relatively permeable sediment overlying a relatively
impermeable sediment or bedrock(e.g. sand overlying clay); and
ii. Springs or groundwater seepage.
f. Any area with a slope of forty percent or steeper and with a vertical relief of ten or more feet except areas
composed of consolidated rock. A slope is delineated by establishing its toe and top and measured by
averaging the inclination over at least ten feet of vertical relief.
The subject site meets the qualification of a landslide hazard area because the eastern slope has slumped
(17.01.100A1 a).
SEISMIC HAZARD CLASSIFICATION
The Mason County Critical Areas Ordinance(17.01.102A) defines a seismic hazard area as.
1. Areas susceptible to ground failure including the following.
a. Areas with mapped geologic faults until proven inactive;
b. Deep road fills and areas of poorly compacted artificial fill;
c. Areas with artificially steepened slopes(i.e. old gravel pits);
d. Postglacial stream, lake or beach sediments,-
e. River deltas,
f. Areas designated as potential Landslide Hazard Areas,
g. Bluff areas; and
h. Areas underlain by potentially liquefiable soils
2. The following criteria may be used as a guide by the County to indicate areas that have a higher likelihood of
meeting the classification criteria above:
a. Areas identified on the Coastal Zone Atlas of Washington, Volume 9, Mason County as Af, Qa1, Qa2, Qvc,
Qls, Qos and Qp.
b. Areas identified on the Mason County Soil Survey Map as having slopes greater than 15 percent.
c. Faults identified on "Map Showing Known or Suspected Faults With Quaternary Displacement in the
Pacific Northwest" A.M. Rogers, T.J. Walsh, W.J. Kockelman and G.R. Priest, US Geologic Survey,
1996; or described in Active Faulting Investigations on the Canyon River Fault, Southern Olympic
Range, Washington", T.J. Walsh and K.G. Neal, U.S. Geologic Survey, 1997.
d. Areas underlain by potentially liquefiable soils as shown Liquefaction Susceptibility Map of Mason County,
Washington" by Stephen P. Palmer, Sammantha L. Magsino, James L. Poelstra, Eric L. Bilderback,
Derek S. Folger, and Rebecca A. Niggemann, September 2004.
Geotechnical Investigations Group 14
5933 54`h Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
241 NF .Q!der Creek Lane, Belfair,Washington
This site does qualify as a seismic hazard area because the site is categorized as, 1.f. Areas designated as
potential Landslide Hazard Areas."
EROSION HAZARD CLASSIFICATION
The purpose of the Erosion Hazard Section (17.01.104A) is to identify areas that present potential dangers to public
health and safety, and to prevent the acceleration of natural geological hazards, and to neutralize the risk to the
property owner from development activities.
Areas in Mason County underlain by soils which are subject to severe erosion when
disturbed. Such soils include, but are not limited to, those for which potential for erosion is
identified in the Soil Survey of Mason County, USDA Soil Conservation Service, 1960, or
any subsequent revisions or additions to this source. These soils include, but are not
limited to, any occurrence of River Wash ("Ra') or Coastal Beaches ("Cg') and the
following when they occur on slopes 15% or steeper:
a. Alderwood gravelly sandy loam("Ac"and 'Ad')
b. Cloquallum silt loam("Cd')
c. Harstine gravelly sandy loam("Hb')
d. Kitsap silt loam("Kc')
The soils at the site are mapped as Everett gravelly sandy loam (Ek). This site does not meet the technical criteria
of an erosion hazard area.
SITE GEOLOGY
The site is generally situated within the Puget Sound glacial upland. Multiple glacial advances deposited the onsite
material. The near surface material was deposited during the most recent Vashon stade (stage) of the Fraser
glaciation that occurred between
about 9,000 and 15,000 years Puget Sound LiDAR
ago. Weathering, erosion, and
landsliding has occurred since.
The figure right is a LiDAR image
at a 12-feet resolution. In the
local vicinity, ridgelines trend �-
northeast to southwest. Local '
drainages follow the troughs and
then cut perpendicular to the i
ridgelines. Landslide material is r
visible along portions of the 0
drainage to the northeast of the
site. The small drainage has yet
4
to reform awell-defined v-shaped t 01
,
valley.
I
x
Geotechnical Investigations Group 15
5933 54`"Way SE. Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek Lane, Belfair,Washington
The following geologic excerpts are from previously published documents, maps, and reports. The following photos
portray the onsite material.
The Geologic Map of Washington-Northwest Quadrant(2002) has mapped the site geology as advance outwash
deposits(Qga)of continental glacial origin. The report reads:
Advance outwash - Glaciofluvial sand and gravel and lacustrine clay, silt, and sand deposited
during the advance of glaciers, sandy units commonly thick, well sorted, and line grained, with
interlayered coarser sand, gravel, and cobbles, locally contains nonglacial sediments and deposits
mapped as transitional between glacial and nonglacial. Includes the Colvos and Esperance Sand
Members of the Vashon Drift and part of the Vashon Drift undivided.
SITE SOILS
The onsite soils are composed of silty sand with gravel underlain by silt. Material from SL-1 is pictured below. A
gradation of the onsite native material follows this report.
The Soil Survey of Mason County, Washington, USDA Soil Conservation Service (1960) has mapped the site soils
as an Everett very gravelly sandy loam, 15 to 30 percent slopes(Ek). The survey describes the soil as follows:
This very deep, somewhat excessively drained soil on terraces and outwash plains formed
in the glacial outwash stage of the most recent Fraser glaciation. Permeability is rapid(up
to 20 inches per hour) with a high rate of water transmission. These soils are typically
classified as a "Group A"relative to surficial runoff. The soils are further characterized as
having medium runoff potential and moderate water erosion potential. Shrink-swell
potential is described as low due to the low organic content.
0ii 4' wft '5
Geotechnical Investigations Group 16
5933 541h Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek Lane, Belfair,Washington
SUBSURFACE EXPLORATIONS
Subsurface conditions at the site were evaluated by excavating
two shallow test pits behind the existing retaining wall and next to
the existing residence. "T" bar probing was conducted at many Scarp
locations behind the existing retaining wall and along the top of
the eastern slope. Only at one location was the subsurface soft
enough to push the probe beyond 2 inches. The photo right
illustrates the "T' bar sunk to the handle with little effort in the
western most slump block.
Fill material (drainage sand) was observed behind the existing
soldier pile retaining wall, see photos below. No grading has
"T"Bar next to Scarp
occurred recently.
Available well logs were reviewed-, see the provided well logs in the Appendix. A well could not be located onsite.
Shallow groundwater may be expected near seepage areas. In 1999, the groundwater was reported at 27 feet in
one the pile auger holes.
Soil gradations were determined by Geotechnical Investigations Group using laboratory test method ASTM D-2487
(Unified Soil Classification System). The soil gradations are included in the appendix
SUBSURFACE CONDITIONS
The building location is underlain by Vashon glacial advance outwash material with a thin horizon (5 inches) of
Everett gravely sandy loarn near the surface. This material was observed at approximately 5 to 12 inches below
the existing ground surface near the existing building location. .
SOIL LOG
Soil Log 1 (SL-1)
0"—2" Grass and roots.
2"—6" Topsoil — Very dark gray (2.5Y3/1), silty sand, moist, roots, well graded, firm, massive, minor
gravels up to 2 inches.
6"—38" Drainage Material -- Gray (5Y5/1), sand with minor silt, moist, minor roots, dense, well sorted,
massive, sampled at 36 inches.
Geotechnical Investigations Group 17
5933 54`h Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360) 481-7062
241 NE Alder Creek Lane, Belfair,Washington
Soil Log 2 (SL-2)
0"—2" Grass and roots.
2"—5" Topsoil -- Very dark gray (2.5Y3/1), silty sand, moist, roots, well sorted, firm, massive, minor
gravels up to 1 inch.
5"—28" Native Material — Light olive gray (5Y6/2), silty sand with gravel, moist, minor roots to 10 inches,
well graded, massive, very hard to probe, minor cementation, sub-round to round gravels up to 3
inches, sampled at 20 inches.
SLOPE STABILITY AND ANALYSIS
No evidence of significant erosion was observed onsite at the time of our investigation. Slopes are well vegetated
throughout the site.
At the existing building location, the slope is nearly level with no indication of previous landsliding. The foundation
expresses only one small settlement crack. Bowed and leaning trees were observed on the lower portions of the
eastern old landslide, over 150 feet from the existing residence.
Slumping was observed along the top of the eastern slope, occurring in late 2007. The slumps are the uppermost
portion of an older landslide (before 1999). The slumps are the final expressions of former movement. Landside
debris was observed downhill of the slide area, see photo below. Fresh or new landslide features were not
observed in the lower portions of the landslide.
Jo
k '
i ^ View Looking Ea ' [Y
Saturated soil conditions likely triggered the new slumps. The excess groundwater came from collected surface
water and the existing (damaged) roof downspout drainpipes.
The Relative Slope Stability of the Southern Hood Canal Area, Washington, (1977)describes the site area as Class
2. Class 2 is described as:
Areas believed to be stable under normal conditions, but may become unstable if disturbed
by man's activities, if slope is oversteepened by erosion, or if subjected to strong seismic
shaking. Slopes generally steeper than 15 percent, but may be less in some areas of weak
geologic materials. Includes areas underlain by: well-drained sand and gravel, mostly on
valley sides that lack known slope failures;glacial till with steep slopes; and bedrock.
Geotechnical Investigations Group 18
5933 54`h Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
• 241 NE Alder Creek Lane, Belfair,Washington
Mll!!IM i
WA Dept. of Ecology Coastal Atlas Map of
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The Coastal Atlas Map of Washington maps the site as an area of"intermediate" slope stability see figure above.
The Coastal Zone Atlas, Volume 9, Mason County maps the site as an area of"intermediate" slope stability, see
figure below.
'14"XI
1 \IJn
. Yu II1L IYp mam
r
- l /
00Y
u
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U ,r�
r-
Coastal Zone Atlas of Washington, Volume 9, 1979(Mason
Resources by Rogers and Walsh detailing faults in the Puget Sound were reviewed. The Tacoma fault is mapped
3% miles to the south of the subject site. No known faults are mapped in the immediate vicinity ('12 mile) of the site
(17.01.100.E.4(5)).
Geotechnical Investigations Group 19
5933 541h Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360) 481-7062
741 NE Alder rrPFk Lane, Belfair,Washington
17.01.100E5(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, the minimum seismic safety
factor is 1.1.and the quasi-static analysis coeffients should be a value of 0.15.
Slope stability was modeled using the GeoStudio 2004 program (version 6.20) in both static and dynamic
conditions (ca = 0.15). Factors of safety were determined using Bishop's, Janbu, and the Morgenstern-Price
methods. Previous landslides are difficult to model due to the multiple failure planes of a slump block landslide and
the variable pore pressure.
The site was modeled using the Krazan data that was collected to design the original retaining wall. Landslide
material forms the eastern portion of the slope model (see Figure 3 Cross-section). Groundwater was modeled at
27 feet at the top of the slope. Using laboratory data from Krazan the following values were utilized in the slope
model.
Silty Sand with Gravel layer--unit weight of 107.3 pcf, cohesion of 400 psf, and a shear angle (0) of 291.
Landslide material (composed of similar Silty Sand with Gravel) -- unit weight of 98.6 pcf (measured in-situ),
cohesion of 400 psf, and a shear angle(�)of 291.
Under static loading, the 3328 computations demonstrated that the slope is not susceptible to surficial raveling or
large deep-seated failure. The minimum static factor of safety is equal to 2.55 for section "A." The figure (below)
demonstrates that largest failure solution with a static factor of safety of 2.55. This failure does not intersect the
existing building location.
Static Model
Minimum FS= 2.55
Descnptow LardsWje Maw.t
NA "6
Coheswa 400
0
ON 29
Pe2'ernitnt I.mr t
y' Desuo-on Sft Saed vM Gnvet
u- At.107 D
CaAei+ort 4N
Ph 29 —
PKzorrrnK Low t
Distance t tt i
Geotechnical Investigations Group 20
5933 54th Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek Lane Belfair,Washington
The dynamic model demonstrated that the slope is susceptible to surficial raveling and not large deep-seated
failure. The following figure illustrates the moment factor of safety for section "A" under the existing conditions.
The critical slip surface factor of safety is equal to 1.35 for section "A." Mason County code requires a dynamic
factor of safety to be at least 1.1 at the existing building location. The figure below demonstrates that largest failure
solution with a static factor of safety of 1.35. This failure does not intersect the existing building location.
Dynamic Model
Minimum FS = 1.35
241 NE Alder Creek Lane
DescrvWn LaneskW Matenai
Wt 98 B
= Cohes.on 400
c Ph :9
PKz~nc L e t
Deserpeiort 51tp Said nil+Gravel' -
i:. 04 1073
Cohesion 400 _
Me 29
P"Won"tm L" 1
Distance lit,
17.01.100E5(7) -- Appropriate restrictions on placement of drainage features, septic drain fields and
compacted fills and footings, including recommended buffers and setbacks from the landslide hazard
areas.
17.01.100E5(11) -- Specifications of final development conditions such as, vegetative management,
drainage, erosion control, and buffer widths.
RECOMMENDATIONS FOR BUILDING SETBACK
At this time, no new structures are proposed. Due to the recent earth movement, no new structures shall be
constructed within 20 feet of the eastern scarp. Drainage facilities may be constructed where necessary.
LIQUEFACTION HAZARD
The Site Class Map of Mason County, Washington by Palmer, Magsino, Bilderback, Poelstra, Folger, and
Niggemann (September 2004) maps the site area as site class C. Site class C is a very stiff soil.
Geotechnical Investigations Group 21
5933 54`h Way SE, Lacey, Washington 98513
Office (360) 923-2561 Cellular(360)481-7062
241 NF Alder Creek Lane. Belfair,Washington
The Liquefaction Susceptibility Map of Mason County, Washington by Palmer, Magsino, Poelstra, Bilderback,
Folger, and Niggemann (September 2004) maps the site area as having a low liquefaction potential.
Near the existing building location, the surrounding undisturbed slopes are well vegetated. Perched groundwater
was not encountered during our exploration or observed along the eastern slope. Krazan did observe groundwater
at 27 feet where the soldier pile wall is located. Two seeps are located in the southwestern portion of the site. The
seeps are at least 15 feet lower than the existing building location.
Shaking of the already dense and well-mixed glacial material may produce a denser configuration and
subsequently excess pore water pressures may be produced. Located on a hillside, the mixed well-graded material
is not a likely candidate for liquefaction concerns since slumping is more likely.
Grain-size analyses are found in the Appendix. Based on our review of the subsurface conditions, geologic
references, and laboratory data, we conclude that the site soils are not susceptible to liquefaction.
SEISMIC HAZARD
According to the Seismic Zone Map of the United States contained in the 2006 International Building Code (IBC),
the project site is located where the maximum spectral response acceleration is 45 percent of gravity(g).
Several locations behind the wall and along the eastern slope were probed with a steel "T" bar. Most locations
were firm at 3 inches. The only soft area was clearly a slump block that was demonstrating 2 inches of vertical
movement. See photo below.
Scarp
"T"Bar next to Scarp
The base of the shallow test hole (SL-2) was probed with a steel "T" bar. Based on the subsurface conditions
observed at the site, we interpret the site conditions to correspond to a seismic Soil Profile Type D, for Stiff Soil, as
defined by Table 1613.5.2 (IBC).
Geotechnical Investigations Group 22
5933 54"'Way SE, Lacey. Washington 98513
Office (360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek Lane. Belfair,Washington
17.01.100E5(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.
17.01.100E5(12) -- Recommendations for the preparation of structural mitigation or details of other
proposed mitigation.
CONCLUSIONS AND RECOMMENDATIONS
The existing soldier pile retaining wall is unaffected by the recent earth movement. No recent signs indicate the toe
of the old landslide has reactivated. The existing residence is currently stable relative to deep-seated instability and
has not been adversely impacted by recent landslide activity. The existing residence is safe for habitation.
Recent slumping along the top of the eastern slope resulted from saturated soil conditions caused primarily by an
improperly placed infiltration gallery. Proper drainage control measures will improve overall slope stability. The
existing infiltration gallery must be disconnected from the roof drains. A new drainage system will eliminate roof
discharge to the slump. All existing roof downspouts must be connected to new tight-line pipe and conveyed to the
base of the northern slope. Energy dissipaters will be placed at the discharge to reduce the water's energy No
drainage of concentrated surface water or significant sheet flow onto the sloped areas. Proper drainage control
measures will reduce or eliminate the potential for erosion in this area.
We recommend contouring and vegetating the scarp and upper slump. Exposed soils must be re-vegetated. Jute
matting or similar materials shall be used to cover exposed soils until vegetation is established. Jute matting or
temporary straw netting reduces the energy impact of rainwater. Onsite soils may not be used as structural fill
material or drainage material. As an additional repair, the wing wall could be replaced.
Following all recommendations, the hazards of the landslide area can be overcome in such a manner as to prevent
harm to property and public health and safety, and the project will cause no significant environmental impact for the
life of the project. Since conditions change, the homeowner will be responsible to monitor the landslide scarps and
retaining wall(s).
RECOMMENDATIONS FOR SUITABILITY OF ONSITE SOILS AS FILL
The collected samples are mostly silty sands or sands with gravel. This material may be sensitive to moisture.
Therefore, onsite soils may not be considered for use as structural fill or drainage material.
Fill material requirements are found on page 9-30 of the WSDOT Standard Specifications 2008. In general, the
native material encountered onsite must have less than 10 percent fines (material passing the US No. 200 sieve) to
be suitable for use as structural fill. The onsite material sampled may not be used as structural fill.
17.01.100E5(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.
Geotechnical Investigations Group 23
5933 541h Way SE. Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek Lane, Belfair,Washington
RECOMMENDATIONS FOR EROSION CONTROL
Vegetation along the eastern slope must not be removed. All vegetation along and near the eastern slope shall be
encouraged. Removal of natural vegetation should be minimized and limited to the active construction area. Yard
landscaping is permissible, but understory growth on the slopes should be encouraged as much as possible as a
deterrent to erosion. If soil spoil piles are to be left onsite overnight, they must be covered by plastic sheeting.
RECOMMENDATIONS FOR STRUCTURAL FILL
Where placement of fill material is required, the exposed subgrade areas should be proof-rolled to a firm and
unyielding surface prior to placement of any fill. Excavations for the potential building area should be backfilled with
structural fill, compacted to the density requirements described in this section of the report. No foundation
elements shall be constructed on"untested"or nonconforming fill material.
If structural fill is needed, we recommend that our representative be contacted to evaluate the exposed subgrade
conditions after removal of vegetation and topsoil stripping is completed. Any soft, loose or otherwise unsuitable
areas delineated during foundation preparation or probing should be compacted, if practical, or over-excavated and
replaced with structural fill, based on the recommendations of our report.
All fill material should be placed as structural fill. The structural fill should be placed in horizontal lifts of appropriate
thickness to allow adequate and uniform compaction of each lift. Fill should be compacted to at least 90 percent of
MDD (maximum dry density as determined in accordance with ASTM D-1557). We recommend the appropriate lift
thickness be evaluated by our representative.
The suitability of material for use as structural fill will depend on the gradation and moisture content of the soil. As
the amount of fines (material passing No. 200 sieve) increases, soil becomes increasingly sensitive to small
changes in moisture content and adequate compaction becomes more difficult to achieve. During wet weather, we
recommend the use of well-graded sand and gravel with less than 7 percent(by weight) passing the No. 200 sieve
based on that fraction passing the '/4-inch sieve. Material placed for structural fill should be free of debris, organic
matter, trash, and cobbles greater than 6 inches in diameter.
The moisture content of the fill material should be adjusted as necessary for proper compaction. If prolonged dry
weather prevails during the earthwork and foundation installation phase of construction, a somewhat higher (up to
10 percent) fines content will be acceptable.
RECOMMENDATIONS FOR FOUNDATION SUPPORT
We recommend a minimum width for isolated and continuous wall footings to meet current IBC standards.
Footings founded as described above can be designed using an allowable soil bearing capacity of 2,000 psf
(pounds per square foot)for combined dead and long-term live loads in areas of medium dense to dense soils.
Geotechnical Investigations Group 24
5933 54'h Way SE, Lacey, Washington 98513
Office (360) 923-2561 Cellular(360) 481-7062
241 NF Alder Creek Lane, Belfair,Washington
We estimate that settlements of footings designed and constructed as recommended will be less than 1 inch, for
the anticipated load conditions, with differential settlements between comparably loaded footings of/z inch or less.
Most of the settlements should occur essentially as loads are being applied. However, disturbance of the
foundation subgrade during construction could result in larger settlements than predicted.
RECOMMENDATIONS FOR CUT AND FILL SLOPES
Cut and fill slopes are not anticipated. Surface drainage should be directed away from all slope faces. Plastic
sheeting shall be used to cover any exposed soils until permanent vegetation is established. All slopes should be
seeded as soon as practical to facilitate the development of a protective vegetative cover or otherwise protected.
If soil spoils piles are to be left onsite overnight, they must be covered by plastic sheeting. All job site safety issues
and precautions are the responsibility of the contractor providing services and/or work.
RECOMMENDATIONS FOR SITE DRAINAGE
Installing new roof downspout drains are recommended. Roof drains shall be directed to the north of the existing
residence. Roof downspout drainpipes must be discharged away from the existing residence. Surface water must
not be directed towards the eastern slope.
Due to the fine-grained nature of the onsite soil, onsite infiltration structures are not advised (e.g., French drains).
Splash blocks are to be used at the terminus of downspout seven (7)on the western side of the residence.
17.01.100E i(10) --An analysis of both on-site and off-site impacts of the proposed development.
SEPTIC IMPACT
The existing septic drainfield is located to the south of the existing residence. Chapter 246-272A-0210 of the
Washington Administrative Code requires a minimal horizontal separation between septic drainfields and various
facilities including footing drains. The existing drainfield is 30 feet from the recent slump; it is our opinion that the
drainfield is not compromising the slump.
Geotechnical Investigations Group 25
5933 54"'Way SE, Lacey, Washington 98513
Office (360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek Lane. Belfair.Washington
REPORT LIMITATIONS AND GUIDELINES FOR USE
We have prepared this report for the exclusive use of Steve & Jim Kessler and their authorized agents for the
property located at 241 NE Alder Creek Lane, Belfair, Washington. Site inspections, research, and mapping have
culminated in this report. This report is intended to meet the requirements of the Mason County Critical Areas
Ordinance. This report does not specify setbacks for: line-of-sight setbacks, FWHCA setbacks, eagle tree
setbacks, wetland setbacks, or property line setbacks. Within the limitations of scope, schedule and budget, our
services have been executed in accordance with generally accepted practices in the field of geotechnical
engineering in this area at the time this report was prepared. The liability for this report is limited to the fee
charged. No warranty or other conditions, expressed or implied, should be understood.
CONTRACTORS ARE RESPONSIBLE FOR SITE SAFETY ON THEIR OWN CONSTRUCTION PROJECTS
Our geotechnical recommendations are not intended to direct the contractor's procedures, methods, schedule or
management of the work site. The contractor is solely responsible for job site safety and for managing construction
operations to minimize risks to onsite personnel and to adjacent properties.
READ THESE PROVISIONS CLOSELY
Some clients, design professionals, and contractors may not recognize that the geoscience practices (geotechnical
engineering or geology) are far less exact than other engineering and natural science disciplines. This lack of
understanding can create unrealistic expectations that could lead to disappointments, claims and disputes.
Geotechnical Investigations Group includes these explanatory "limitations' provisions in our reports to help reduce
such risks. Please confer with Geotechnical Investigations Group if you are unclear how these "Report Limitations
and Guidelines for Use"apply to your project or site.
GEOTECHNICAL, GEOLOGIC,AND ENVIRONMENTAL REPORTS SHOULD NOT BE INTERCHANGED
The equipment, techniques and personnel used to perform an environmental study differ significantly from those
used to perform a geotechnical or geologic study and vice versa. For that reason, geotechnical engineering or
geologic reporting does not usually relate any environmental findings, conclusions or recommendations; e.g., about
the likelihood of encountering underground storage tanks or regulated contaminants. Similarly, environmental
reports are not used to address geotechnical or geologic concerns regarding a specific project.
CLOSING
We appreciate this opportunity to be of service to you and we look forward to working with you in the future. If you
have any questions concerning the above items, the procedures used, or if we can be of any further assistance
please call us at the phone number listed below.
Respectfully Submitted,
Geotechnical Investigations Group GAR Y
�G of WAsy��
co Z
13�iCN 9F 45853
Lance Levine, P.E. �s GIST �•.�
Professional Engineer S/QN
Geotechnical Investigations Group 26
5933 54'h Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
• 241 NE Alder Creek Lane, Belfair,Washington
APPENDIX
Geotechnical Investigations Group g s i
5933 54`h Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek Lane, Belfair,Washington
REFERENCES
Maps
DeLorme 3-D TopoQuads (2002), Source Data USGS, Yarmouth, Maine.
Dragovich, Logan, Walsh, and Schasse (2002), Geological Map of Washington— Northwest Quadrant (Geological
Map GM-50), published by Washington State Department of Natural Resources.
Palmer, Magsino, Poelstra, Bilderback, Folger, and Niggemann (September 2004), The Liquefaction Susceptibility
Map of Mason County, Washington, published by Washington State Department of Natural Resources.
Palmer, Magsino, Bilderback, Poelstra, Folger, and Niggemann (September 2004), The Site Class Map of Mason
County, Washington, published by Washington State Department of Natural Resources.
Rogers, A. M., Walsh, T. J., Kockelman, W. J., and Priest, G. R. (1996), Map showing known or suspected faults
with quaternary displacement in the Pacific Northwest, published by U.S. Geological Survey OFR 91-441-0,
Plate 1, scale 1:2,000,000.
Smith, Carson (1977), Relative Slope Stability of the Southern Hood Canal Area, Washington, prepared in
cooperation with the Washington Department of Natural Resources Division of Geology and Earth
Resources; and, Department of the Interior United States Geological Survey.
Walsh (1997), The Canyon River fault, an active fault in the southern Olympic Range, Washington: Washington
Geology, v. 25, no. 4, p. 21-24, published by U.S. Geological Survey.
Washington State Department of Ecology (1979), Coastal Zone Atlas of Washington, Volume 9, published by
Washington State Department of Ecology.
' Publications
Ambrose (1981), Simplified Design of Building Foundations, Table 2.5, pages 48-57, published by John Wiley &
Sons, Inc.
' ASTM International (2005), Annual Book of Standards 2005, Section 4, Volume 4.08, published by ASTM
International, West Conshohocken, Pennsylvania.
' Bloom (1991), Geomorphology, published by Prentice-Hall, Inc., Upper Saddle River, New Jersey.
Burroughs, E. R. Jr., G. R. Chalfant, and M. A. Townsend (1976), Slope Stability in Road Construction, US
' Department of the Interior, Bureau of Land Management, Oregon State Office.
Gallagher, Patricia M. (October 27, 2000), Passive Site Remediation for Mitigation of Liquefaction Risk, Dissertation
submitted to the Faculty of the Virginia Polytechnic Institute and State University, Virginia.
International Code Council, Inc. (2004), 2003 International Building Code, published by International Code Council,
Inc.
' International Code Council, Inc. (2006), 2006 International Building Code, published by International Code Council,
Inc.
' Kollmorgen Instruments Corporation (1994), Munsell Soil Color Charts (1994 Revised Edition), published by
Macbeth Division of Kollmorgen Instruments Corporation, New Windsor, New York.
Krazan &Associates, Inc. (11-15-1999), Geotechnical Engineering Investigation Alder Creek Lane Landslide.
' Geotechnical Investigations Group P u
5933 54'h Way SE, Lacey, Washington 98513
' Office (360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek Lane, Belfair,Washington
McCarthy (1993), Essentials of Soil Mechanics and Foundations, published by Prentice-Hall, Inc., Upper Saddle
River, New Jersey.
Moffit(1992), Surveying e Edition, published by Harper Collins, New York, New York.
Ness, Fowler, Parvin (1960), The Soil Survey of Mason County, Washington, USDA Soil Conservation Service, in
cooperation with the United States Department of Agriculture, and Washington Agricultural Experimental
Station, and the Soils Conservation Service.
Parks, Neal, Koloski, Laprade, Molinari, Butler, and Lorentson (November 2006), Guidelines for Preparing
Engineering Geology Reports in Washington, published by Washington State Geologist Licensing Board,
Olympia, Washington.
Prakash (1981), Soil Dynamics, Figure 6.3, page 173, published by McGraw-Hill, Inc.
Sowers (1979), Introductory Soil Mechanics and Foundations: Geotechnical Engineering, Table 10:4, page 472,
published by Macmillan Publishing Co., Inc.
Washington State Department of Transportation (WSDOT) (2005), Standard Specifications for Road, Bridge, and
Municipal Construction 2006 M41-10, prepared by WSDOT Engineering Publications, P.O. Box 47408,
Olympia, Washington.
Websites
Mason County Government Information Services
http://www.co.mason.wa.us
Mason County Codes, Ordinances, and Regulations
http://www.co.mason.wa.us/code
Puget Sound Lidar Consortium
http://pugetsoundlidar.ess.washington.edu/lidardata/index.html
Slope Stabilization Erosion Control Using Vegetation A Manual of Practice for Coastal Bluff
http://www.ecy.wa.gov/biblio/9330.html
Vegetation Management Guide for Puget Sound Bluff Property Owners
http://www.ecy.wa.gov/biblio/9331.html
United States Department of Agriculture Natural Resource Conservation Service
http-.//soildatamart.nrcs.usda.gov
Washington Administrative Code
hftp://apps.leg.wa.gov/wac/
Washington Department of Ecology
http://apps.ecy.wa.gov/welflog
hftps://fortress.wa.gov/ecy/coastalatlas/viewer.htm
Geotechnical Investigations Group
5933 54`h Way SE, Lacey, Washington 98513
Office (360) 923-2561 Cellular(360)481-7062
► 241 NE Alder Creek Lane,Belfair,Washington
LABORATORY RESULTS
SL-1 Native
Date Received: Sample Description Location Unified Soils Classification System:
5/19/09 Brownish Gray Sand Along Scarp SM,Silty Sand with Gravel
Prot Source: Syecifications:
241 NE ALDER CREEK LANE Native Sand No Specs
U.S.Standard Sieve Numbers Sample Meets Specs?
20 6 4 3 1'r4 '/. 'r4? f4 10 16 2030 4 a 100 200 %
100.0% 1111 1 1 I- t /oGravel• 34.1
rrrT-r-- 1 0
I I 1 1 I I I I I I I I I I I I 1 1
1 1 1 1 1 1 I I 1 1 1 1 1 I 1 III I I I 1 III 1 1 I 1 I III 11 1 I 1 %Sand:46.9%
90.0% LI 1 1 1 J_J___U l L L L 1_ ___11 L I J J_L_I___J L11 1 1 J_1_--L11 L l L l_L__. 0.9
I I 1 1 1 1 1 I 11 1 1 1 I I III I I I I 1 11 1 1 1 I I I III 11 1 1 1 %Fines: 19.1%
IIII 11 I I III 1 1 1 I I • III I I I I I IIII 11 I I III 11 1 I I
I I 1 1 1 I 1 11 1 1 I I I ` III I I I 1 1 11 1 1 1 1 1 1 III 1 1 1 1 1
80.0% Irl 1 '- ---i1 ii irr i i q\�i i i-i-r-I---ir1 i i i i--1---iii i ri i-i-- 0.8
I l t l l 1 I I I I 1 1 1 I I 1 I I I I 11
I I I I I 1 1 I I 1 1 1 1 1 1 1 1
70.0% U111 J_J_-_1J1 LI-Ll-L___11 1-1 J___JL1111 J__I___L11 L1_Ll_L__ 07
I I 1 1 1 1 I I IIII I I I 1 III I I I 11 1 1 1 1 I I 1 1 1 1 1 1 I I
II11 I I I I IIII 1 1 1 I IIII 1 1 IIII 1 1 I 1 111 1 1 1 1 I '.
I I 1 1 I I 1 I I I 1 1 I I I 1 I I 1 1 1 I I IIII 1 1 I I 11 1 1 1 I I I D(lo)=0.04 mm
to 60.0% nyrr�- ---rlYrl-rt-r---anti ti-r --tinYtr i-y---rlr1-1- -- 0.6
I I 1 1 I I I I 1 1 1 1 1 I I 1 1 1 1 1 1 I 1 1 1 1 1 1 1 1 I 1 III 1 1 1 I 1 d D(3e)=0.14 mm
I I I I I I I I 11 1 1 1 I I 1 1 1 1 1 1 I 1 I I 1 1 1 1 1 1 1 1 1 I I I
m 500% 11111i-1-----IIII I-I- - ---II LI -1-I--I---�L II- l-ILIIt [-1-�-L-- 0.5 D(6o)= 2.26 mm
aI I 1 1 1 1 1 I TIT 1 1 1 I I I 1 1 1 1 1 1 1 1 1 1 1 1 I I 1---1 1 1 1 1 I 1 1
I I 1 1 I I I I u 1 1 1 1 1 1 IMP I I I IIII I I I I 11 1 1 I I I 1 Psi D 96= 14.49 mm
o IIII I I I I I I I I I I I I IIII I I I I IIII 1 1 I I I I I I I I I 1 ( 1
40.0% nrrr I- ---rl7rrrt-r---rrrl��-r-I---tiHYrtti- ---rlYrrrt-r-- 0.4 Curvature Coef,Cc.
III 1 1 1 I I IIII 1 1 I I IIII 1 I 1 1 IIII I I I I I111 1 I I 1
IIII I I I 1 I I I I 1 1 I I IIII I I I I III 1 1 1 1 1 III 1 1 I I I
30.0% IL1111_I_ I 111L 1_I 1-'-- 0.3 0.21
IIII I I I I t l l I I I I I IIII I I I 1 IIII I I I I- -TIT I I I I I ..L .� U•
11 1 1 I I I I 1 1 1 1 1 I I 1 1 1 1 1 1 1 1 I 11 1 1 1 1 1 1 III 1 1 1 I 1 Uniformity Coef,C •
20.0% 111i?+ y- 1---tlirl rt-h---Hhliy-F ?y-y--- Ilhl I t-t-- O.G 57.57
I I I I I I I I I I I I I I 1 I III 1 1 1 I 1 I I I I I I I I III I I I 1 I
I I I I I I I I 1 1 1 1 1 I 1 1 III 1 1 1 1 I I I I I 1 1 I 1 11 1 1 I I I I Fineness Modulus:
10.0% III I I 1 -I- 1---Di 1-1 -I ---IIII I-1-1--1---i111 1 1_I- I I1111 I I 1 0.1
IIII I I I I III 1 1 I I I IIII I I I 1 I111 I I I �___-1-_-_-- -- 3.21
111III I � IIIIII I I 1111I I I I I11III I I 11II11 � � �
III I 1 11 1 1 1 1 1 1 11 1 1 I I I I I I I I Dust patio(✓/ :
0.0% 0
1000 100 10 1 0.1 0.01 0.38
Particle Size(mm) Sand/Silt ratio(#iw#=(:
GRAVEL I SAND 3.1
COBBLES COARSE ENE COARSE MEDIUM FINE Sand
Sand Equivalent:
N/A
Fracture count(Sgl/Dbl):
+ Sicvc sues --A�M,n Sip- �o--M.Sip- �•�Saisl
N/A
Actual Interpolated Actual Interpolated
Coarse Aggregate Cumulative Cumulative Fine Aggregate Cumulative Cumulative
Sieve Size Percent Percent Specs Specs Sieve Size Percent Percent Specs Specs
US Metric Passing Passing Max Min us Metric Passing Passing Max Min
6.00" 150.00 100.0% #4 4.75 65.9% 65.9%
4.00" 100.00 100.0% #8 2.360 60.2%
3.00" 75.00 100.0% #10 2.000 59.4% 59.4%
2.50" 63.00 100.0% #16 1.180 56.2%
2.00" 50.00 100.0% #20 0.850 55.0% 55.0%
1.75" 45.00 100.0% #30 0.600 52.5%
1.50" 37.50 100.0% #40 0.425 50.7% 50.7%
1.25" 31.50 100.0% #50 0.300 47.5%
1.00" 25.00 100.0% 100.0% #60 0.250 46.2% 46.2%
7/8" 22.40 95.1% #80 0.180 36.6%
3/4" 19.00 88.6% 88.6% #100 0.150 32.5% 32.5%
5/8" 16.00 86.3% 86.3% #140 0.106 24.6%
1/2" 12.50 80.4% 80.4% #170 0.090 21.8%
3/8" 9.50 75.3% 75.3% #200 0.075 19.1% 19.1%
1 4" 6.30 69.0%
Geotechnical Investigations Group iv
5933 54`h Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek Lane,Belfair,Washington
Drainage Material
Date Received: Sample Description: Location Unified Soils Classification System:
5/19/09 Gray Sand Behind Retaining Wall SP,Poorly graded Sand
Project: Source: Specifications:
241 NE ALDER CREEK LANE DRAINAGE SAND No Specs
U.S.Standard Sieve Numbers Sample Meets Specs?
20 6 4 3 1'/: '/. '/ 10 t6 4 n/a
100 200
100.0% I ri I i i, i 10 Gravel: 2.4%I II I Ia: ItY�. I rrrr-r-- 1 0
i I I I !I I 1 I I I I I I 1 1 III I I 1 1 1 W III I I I I I I I I I I I III I I I ]loll I I 1 1 1 1 1 1 1 1 1 %Sand: 97.6%
90.0% LI111 J_J___111 LLL 1-L---u LUJ _IJU111 J_J_ L11 LLL1_L__ 0.9
III I I I I I III I I I I 1 III I I I I 11 1 1 1 I I I IIII t I I I %Fines• 0.0%
III I I I I 1 III 1 1 I I 1 III I I I I I IIII 1 1 I I III I I I I 1
1 1 1 I I I I I III I I I 1 1 11 1 1 1 1 1 11 1 1 1 I I 1 I I I I I I I 1
80.0% nrrrl-l---rlT rrr T-r---rt n1 1-r-I --�n�rr�- ---rtT rrr r-r- 0.8
I I I I I I I I III I I I I 1 IIII I I I I IIII I I I 1 1 1 1 1 1 I I I
I t l l I I I 1 11 1 1 1 I I I 1 1 1 1 1 I 1 I I I I I 11 1 I I I I I I I I 1
70.0% U111J_J___111LLL1_L___11UJJ_L_I__ L1111J_J___1J1L1_L1_L-_ 07
11 1 1 1 I I 1 11 1 1 1 I 1 1 1 1 1 1 1 I 1 1 11 1 1 1 I I I I I I I I I 1
I I I I I I I 1 III 1 1 1 I 1 1 1 1 1 1 I 1 1 I I I 11 1 I 11 1 1 1 1 I 1 �
I I I I 1 1 1 I IIII I I I I III 1 1 I I I I I I I 1 I I I I I I I I 1 D(lo)-0.16 mm
m 60.0% nYrtti-ti---rltrrrr-r---Itrl7ti-r-I---y Yrr I-y---rlYrrrr-r--
EE II I I I I 1 1 11 1 1 1 I I I IIII 1 1 I 1 1 1 I I I 1 I I I I I I I I 0.6 v D(3c)-0.32 mm
•m IIII I I 1 1 III 1 1 1 1 1 11 1 1 1 1 1 1 1 1 1 11 1 I 11 1 1 I I I 1
111111J_J---L11 LI-1-1-L__-1111I III-I__I--_J111 1_I_ 1_--IIII :-I-1 -I g -0.73 mm
� III I I I I 1 11 1 1 1 I I I IIII l l I I I I I I 1 I I I I I I I I I 1
IIII 11 1 I III I I I I I 11 1 1 1 I I I IIII I I I I 1 1 I I I I I 1 D(go)= 2.24 mm
c I I I I I I I I I I I I I I I I IIII I I I I IIII I I I I I I I I I 1 1 0
40.0% rl�r+-o--o---rlYrrrt-r---HH-i-i-r-I----1n-r ---1---rltrrrt-r-- 0.4 Curvature Coef,Cc•
IIII I I I I IIII I I I I 111 I I 1 1 I IIII I I I I III I I I I I '
I I I I 1 1 I I I I I I I I I I 11 1 1 1 I I I I I I I I I I I III 1 1 I I I
30.0% IL1111-1-1---111L 1-I-1-1---11LI--1-1--1---JLII11 --I---III I 1-'-1-L-- 0.3 0.86
I I 1 1 1 1 I I 11 1 1 I I I 1 1 1 I 1 I I I I I I I I I I I I I I I I 1 I
I I I I I I 1 I I I I I I I I 1 11 1 1 1 I I I IIII I I I 1 1 1 1 I I I I Uniformity Coef,Cu:
20.0% Iriyr-1111- -rtrrr+-r--- iri��-r-I---�ri�rrti ti---ri�rrrr-r-- 0.2 4.47
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 IIII I I I 1 I I 1 1 1 1 1 11 1 1 1 1 1 1
I I 1 1 1 I I I III I I I I 1 III I I I I IIII I I I I I 1 1 1 1 1 I Fineness Modulus:
10.0% 111111-I-1---11111-1-1-1---1111-1I-I-1- -111111 I �1111-1-I-L 0.1
I I I I I I I I III I 1 I 1 1 III I 1 1 1 -I_ IIII I I 1 11111 1 I I -- 260
III I I I I I IIII I I 1 I I I I I I I 1 IIII 1 1 1 1 I I I I I I I 1
C ! I I I IIII I I I I I I I I I I I I I I I 1 1 1 1 I I I 1 1 1 Dust Ratio(I2w/"m•
0.0 0
1000 100 10 1 0.1 0.01 0.00
Particle Size(mm) Sand/Silt ratio(nty"w):
GRAVEL SAND #DIV 0!
COBBlFS SILT OR CLAY
COARSE MNE COARSE MEDIUM FINE Sand Equivalent:
N A
+ -M-so- -0-M.so- -.-%-I Fracture count(Sgl/Dbl):
N A
Actual Interpolated Actual Interpolated
Coarse Aggregate Cumulative Cumulative Fine Aggregate Cumulative Cumulative
Sieve Size Percent Percent Specs Specs Sieve Size Percent Percent Specs Specs
us Metric Passing Passing Max Min us Metric Passing Passing Max Min
6.00" 150.00 100.0% #4 4.75 97.6% 97.6%
4.00" 100.00 100.0% #8 2.360 84.2%
3.00" 75.00 100.0% #10 2.000 822% 82.2%
2.50" 63.00 100.0% #16 1.180 70.8%
200" 50.00 100.0% #20 0.850 662% 66.2%
1.75" 45.00 100.0% #30 0.600 52.9%
1.50" 37.50 100.0% #40 0.425 43.5% 43.5%
1.25" 31.50 100.0% #50 0.300 27.2%
1.00" 25.00 100.0% #60 0.250 20.6% 20.6%
7/8" 22.40 100.0% #80 0.180 12.0%
3/4" 19.00 100.0% #100 0.150 8.3% 8.3%
5/8" 16.00 100.0% 100.0% #140 0.106 4.8%
1/2" 12.50 99.6% #170 0.090 3.6% 3.6%
3/8" 9.50 99.3% 99.3% #200 0.075 0.0%
1 4" 6.30 98.2%
Geotechnical Investigations Group v
5933 541h Way SE, Lacey, Washington 98513
Office (360) 923-2561 Cellular(360)481-7062
• 241 NE Alder Creek Lane,Belfair,Washington
WELL LOGS
r w b■s b! r a 1:a •e r e P t st.rt f� card lb. Al1mD+Ia+TN tgit LD t was?
-RU or tallallono NKef might ftrr■sl w
111 "am Addt.s. as aba t.A srLrl= r sous- .
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If■>OBLIM AWLKSi:r.1101.1. lot sm i M t•1/.eam• a at scrs C a tAM IMIIL l
...------..... .........,•...............................__.__._.... ............................................«......
In Powwow IFt• Isar is Am
............. ..-.........,...w.........,-...-_---•.—_-rl------------- . .._ .--......... ..
141 TTPC Or tOR hgwor-a aumar at wit I PeoN clog Dmarrihm bT ta{af. CN&Iaotmt. nw M wtyrtal
I if man chat cm1 I mad wt=ctum. aid ohm ch:dtmaa of ap..fan"rbv ri..l
dRi mcnod aawlrf I goad rat.Lty of cam MLirz&L to each sctac• Pa.iratal. .ue
..-... ••--••-.--•-••-•••••• ••• •••�• •••I at lost CM omrY for owb aaaare►o twiartal
I!m aTta>staw• Ouwty of wl..i t:dwa
yta1w ala ft D.Pth at cospLetrd yeti dam tl. its-r'.L, 1 fact I "
a.......+.rw.....a..u............e.........w.. Lmm Yam CiT t■vm 1 { I to
/i!�denitaucraafl DQAIIa• asom ems■■•o as as vm I at In
dawnp+mtai 4ed m •a,. o
fray.. ft to 416 ft. sugar lOjM ear I as I as
nib i■� Ou frm • ft is ft 1 SAS.Ywt GUY LU! ( Is I a
•gas crvr ft to ft 1 moms craw I !f I sa
..._....._.I............... 1 am=A
ar
hetot"uaa n I Elmira actsr same :ur 1 ira I ul
".a p..f...r.a..sad I mot Call I Nl I Ua
etta et por!arr_Y■ra In by in I lIItM brats DAVO lmATM a.OLTm I rN 1 a*I
parfacmims from Ft t. fa I aAaw:ra :itass seat m►aT. a nave i of N 1 a
porMeacams tam It to It. I 1
R.!.r.tat Le1M tow ft. co ft. I I I
.................................................
i I I
donors fair I I
warad"Xut<r'■ tbw lawwOf I i 1
Trya alorsso IA- M I I 1
01w. a flat mom .on hmrt Ya It. to Nr ft-
Dowslot a.M ors cc. to f■.
............I ................................_.._1 m■: ! 1
drawmL patted ! Slmr of drawl I
Geigi.yl pt.se•m Iry it to ft I z 1
.....................1 -
aurt.a....t rsa ?a moot dtptbl M ft. I f 1 I
NmcKL.l um■d is amaL II MOM 1
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type.r .arias wpu as argots ft { 1 I
der_sta of sso:.ry .erns afI
Ill Pw laarvlmct temr'm far" z
Tyke M►. ( � � 1 I
?Ali entlb taYrtmw r taaa•otrtats.Jwrarla 1 I I
above«ma mes level it I 1
ELM or t...l as It b.:ar tap of rU ado.rryraraf I 1 1
Attafaa Pasoan. The vet mode into Omty 1 1 I
Ano.—-&.a aw"waL..a so I 1 !
{Na.b srartad o'"WEr Ca•Aemef nf)UVF
imJ rlLLi taftY�•Or..tlm.bl:a mmtNK•Ymar LmW) t!to.Um.I►.Lm•1 qti MIFT04C71M COFTir..OtTICO ••••••+••••...............
■ucLc l.mml I I a..atauat./a.iJ.. wtw .esmmmLbrt.ty for ton•
tabs a p V taot asdsl•M If for. by Aer.l I atruetlm of this all, am its...qpir.ar+•i!b sot
Ticks. pl lain wet• ft. ot*-da after %to 1 tlubtera=omit rntar mim natnarAt rat.rWm wd
I add to. Lrtarvtaan rvDar;ad 9m,o.rns tow w my bate
I •r..te#mo...I teller.
ll e ry data
Tom Mum La"L 11im Ms:w Level, Teas tlat.t✓sal 1 Mai ab.......ffaLLoma IM
I Wrsg1. frfy, lr cvr06rat041011 Ryes vt feLrt•
l
I ADP■far P �m■uit m"I tl
Date of c.sc I 1 1 .
Nllre car.. M rtl■an. S ft r�..ov.. after I tam 1 IiStalf4l 1 _t1 lit ty.w/o aaa
Aar
cot �a►7Na rf act+mat at r. f..r 4" a
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T*-P--Vt•-R of .vter Now.cMltvt arNLrVLm Vidal M barlrroc.on a rmtir WWII
Geotechnical Investigations Group vi
5933 54th Way SE. Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
• 241 NE Alder Creek Lane,Belfair,Washington
12313 23 - 1 k/-32 (�
jM WATER WELL REPORT %om OF
,
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umoue En�logr v►•c�t m r.��., ��+�_ -/as
--
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ommm t.� �,Mi .uw well%M a"04 Artr yaLf 115—A
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1,,owm0w w IW Z_1lL Rcc> 7� 1M11rkp RAL n•rfr
wet ❑R•rs..d�r�.er •rr•n(❑ q ❑a,Ia ❑orww kwr
n�rme m(w& u A.. l 1 Amd rx�l:rrg Lr DM Le l W%c
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epLL doewlerf!well _R am mum 104 D tA4%Lb%K
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Yw of paGrarr wed MATERLAL PRUM Tp
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W sslwmp m mcL con%mxtm stadards Mwnikendmiltrudermmum repartee 16o+e ae Rue b My kM lM w6*Md MW
U;nL. ❑Eqs. ❑T'ame NORAIPW 11riv+.11 Ca.y 1 Dnlhr,9Cte[r}paoy Bria..b wf bP!tg4-X1WC
nller!fw�LraTrurwe I—�+�+A� ' A tIsImm .`O 6a1e s17 L
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(rtesrrear,ieraaad�s ('�.onww.
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Geotechnical Investigations Group vii
5933 541h Way SE. Lacey, Washington 98513
Office (360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek Lane, Belfair,Washington
CONTRIBUTING ROOF AREAS CALCULATIONS
The following diagram of the roof of the residence has been divided in to geometric shapes to calculate the
contributing areas going in each direction. The individual areas are discussed in more detail in the following
sections. Water from the green, blue, orange and a portion of the red area are directed toward the soldier pile.
Single Story Roof on north side .._
7.5 8.5 63.75 small roof
Total Contributing Area 63.75 RM
Drains to the North
0.50 14 3.1428571 38.4 112 of the turret
1 9.75 10 0.5 48.75 triangle on upper froof
0.5 13 15 97.5 half of rectangle from L
20 17 340 rectangle on north lower roof
2 9 10.33 0.5 92.97 Triangles on north upper roof
10 10.33 103.3 rectangle on north upper roof
Total Contributing Area 721.02
Drains to the west
1 9.75 10 0.5 48.75 Triangle on sw comer south side of porch
0.50 14 3.1428571 38.5 Triangle on sw comer west side of porch
11 10.5 115.5 rectangle area of porch
0.5 14 3.1428571 38.5 1/2 of the turret
Total Contributing Area 241.25
Drains to the South
2 9 10.33 0.5 92.97 Triangles on south upper roof
10 10.33 103.3 Rectangle on south upper roof
0.5 13 15 97.5 half of rectangle from upper roof(westside)
20 17 340 Rectangle on south lower roof
8.5 24 204 Sun room
1 9.75 10 0.5 48.75 triangle on upper(roof(sw)
Total Contributing Area 886.52
Drains to the East
15 13 195 Rectangle on upper roof(eastside)
2 9.75 10 0.5 48.75 Triangles on upper roof(eastside)
Total Contributing Area 243.75
Total of All Contributing Areas 2156.29
Geotechnical Investigations Group viii
5933 54"'Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
241 NE Alder Creek Lane, Belfair,Washington
SEPTIC As-BUILT
3Quo
'WVV *JW l
Geotechnical Investigations Group ix
5933 54`h Way SE, Lacey, Washington 98513
Office(360) 923-2561 Cellular(360)481-7062
« 241 NE Alder Creek Lane, Belfair,Washington
FIGURE 1 VICINITY MAP
r k :_ f f ,• �_ til , Wit, f ',f� ?.
=+w '!�t .3 `• a'241.HE Alder
,:C
r' f
d
WA- 3
/ f l
Site
"` ✓ o t \' ' Alder Creek Lane
WA-10
A WA- 3
V
Geotechnical Investigations Group x
5933 54`h Way SE, Lacey, Washington 98513
Office (360) 923-2561 Cellular(360)481-7062
Geotechnical
D�TUM FOR THE SITE PLAN INCORPORATED VARIOUS TECHNIQUES " ——
AND SOURCES INCLUDING THE FOLLOWING: " —— \�\ \ \ \♦ \\ �\
TAPING AND PACING,SLOPE MEASUREMENTS WITH AN Investigations
� INCLINOMETE ANGLES AND BEARINGS USING A HRUNTON®GEO
TRANSIT,SITE LOCATIONS USING A GARMINO HAND HELD GPS — \ `\
UNIT,TOPOGRAPHIC MAPS FROM DELORME®,MASON COUNTY // 75 61 I \\—_—1'10_` \ \\\ \\\ Group
G.I.S.WEBSITE,AND SURVEYS RECORDED AT THE MASON COUNTY N
ASSESSOR. GEOLOGIC SITE RECONNAISSANCE OCCURRED ON
APRIL 29 AND MAY 19,2009 BY JELINEK AND LEVINE. �'/ \ \\
THE PRESENT RECORDED SURVEY WAS CONDUCTED BY LOVITf.
SHORT PLAT#1491 IS DATED JANUARY 1985.
NORTH , ' ` `?0
SCALE 1'-40'
C.I.=10'
0 ,° 2D W 40 _——= Hydrogeological
Geotechnical &
Environmental Services
Zo
\�OG, \
55%SLOPE \,G'ti \`\\ \� \�\ \ \ 5933 54th Way SE
\,G O v \\ \ \ Lacey,Washington 98513
LANDSLIDE v g
w / HAZAR�A p \ \ \ Phone:(360)923-2561
� `\ `\ �p j Email:blaisejelinek@gmail.com
GARAGE 4 - asLOP4\ OLD(_1999
\
\\ LANDILIDE N \\ \ \
,.\\ \\ DEBRI \\\ LO \\ \\\\
44/o SLOPE N `\43%SLOPE \ 1
\
DRAIN 4 F+\ I VEG TA� \\ IS S \ I
\\V` OLD(-19") \ \ 1
LANDSLIDE \ \\ \
LAN I E DEBRIS\
EXISTING yc� \\ R\D REA
O
I o > ` \
/ I HOME TREE
, gip► . , ;� \ \
EE
/ // // •e W I I I !SLUMP \ \ \\ �\ `� \
SEo- sP° �I / VE�TATE D \ \ \ \ PROJECT NAME:
' ,' ,' '�_ -• I P \N� O"'- \ CDK\WIT EASE \ \\ \� \\
lD STEVE&JIM KESSLER
8i D \\ IS %\ `\ \j� \\ 241 NE ALDER CREEK LANE
'
EP EXISTING o\ BELFAIR,WASHINGTON
SAUNA SE / / -- \. \
^p %/ INAFILLTRATI 1 I\ \ \ Qga -\\Glacial Adva9gce Outwash PARCEL 12332-50-00906
EXISTING SEPTIC
1 ., DRAINFIELD \- \ \ \ \
� ` \ `\ Revisions;
/ POND `\ LANDSLIDE \
--`SHED
'1 �s � \ \\ \'\ \` HA�ARD AREA \\
'04
/ El \.�G, \\ \ \\
O \\ 52%SLOPE
SEEP
O
POWER LINE l9O
352.54 \ \\\ \�\\ \\\ SCALE:1 inch=40feet
o --,go---ALDER CREEK LANE
FIGURE 2
SITE PLAN
SOUTHWEST NORTHEAST
210 . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . PROPERTY LINE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... . . . . .
200 .........................................._...... ............................._.................................................................................................:................................................................................................................................................................................................... 200
190 �. . . . . . . . . . . . . . . : . . . . . . . . . . . . . . . .j. . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . 190
(•) LANDSLIDE LANDSLIDE
180 s. . . . . . ... . . . . . .HAZARD. ; . . . . . . . . . . . . . . . .I. . . . . . . . . . . . . . . . ... . . . . . . . . . . . . . . . 180
VEGETATED
170 SILTY SAND W/GRAVEL AREA ! , 170
. ... . . . . . . . . . ..�� . . . . . . . . . . . . . . . . . . . . . . . . .f. . . . . . . . . . . . . . . . ..
-� — VEGETATED f 160
160 ---=�_ ---,__� :. . . . . . . . . . . {. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SILT
150 �° 44%SLOPE 4
.................._.........................................................................`... ....L...,,,��`..................`..........DEBRSg IfSLr..... .... ............. .................................................. ..............................................................! 1
VEGETAT•,ED 50
I VEGETATED !
140 -�.. . . _ ST EAM. . . . 1140
-�--
130 � � 130
0 50 100 150 200 250 300
CROSS SECTION A
Geotechnical Investigations Group FIGURE 3
Geotechnical, 5933 54th Way SE CROSS SECTION
Lacey. A 98513
Hydrogeologlcal,& Phone:(360)481-7062W SCALE
Environmental Services Email:blalsefellnek®gmall,com V=40'
W 14x43
8 1/4' 4+—
7/16'
12 9/16' 13 1/2'
SIDE VIEW FRONT VIEW SCALE 1/4'
FENCE
MU LI MUDLN --------
------ --------------- ———————— ------
WOOD LAGGING
DAMAGED
WING
PILE it
SAND
ANCHOR MUD LINE —1
ANCHOR
I I I I I I I I I I I I I I I
II II II II II II II II
II II II II it it II II
�� li II II II II II II II
�a II II II II II II II II
53.5'
II II II II II II it II
II II II II II it II II
II II II II II II II II
II II II II II II II II
II II II II fl II II II
II II II II II II II II
I I I I ze' I I I I I I I I I I i t
II II II II II II tl II
it II II II II II II II
II 11 II II II II II II
II II II II II II II II
II II II II II II II it
II II II II II II II II
I I CAST IN CONCRETE I I I I CAST IN CONCRETE I I I I I I I I I
II II II II II II II II
II 11 II II II II II II
II II II II II II II II
II II II II II II II II
II II II tl II II II it
LJ LJ LJ LJ LJ LJ LJ LJ
Geotechnical Investigations Group FIGURE 4
Geotechnical, 59335+1h Way SE EXISTING SOLDIER PILE DETAIL
Levey,WA 88513 SCALE
Hydrogeologlcal,& Phone:(360)481.7062
Environmental Services Emaµ.elalaeeunehggmel.om ,.'8,