HomeMy WebLinkAboutGEO BLD2006-01315 - BLD Engineering / Geo-tech Reports - 1/11/2007 MASON COUNTY
PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER
Shelton, Washington 98584
i - P
DATE: January 11 , 2007
INTER-DEPARTMENTAL COMMUNICATIONS
TO: Tammi Clark PARCEL # 52025-75-00080
FROM: John Sliva, Programs Engineer-PW BUILDING PERMIT NUMBER: BLD2006-01315
SUBJECT: Geotechnical Report Review NAME: Lawrence Jim
Tammi,
The Geotechnical Report prepared for the proposed single-family residence at 100 W Reller Road.
near Shelton has been received and reviewed by Public Works.
The geotechnical report was written for the two parcels. The steepest slope noted was in the
western parcel and was measured at 47%. This slope was also noted as being cut into bedrock in
some locations. A drawing indicates the location of the proposed residence is in the southeastern
portion of the east parcel. Slopes in the eastern parcel were not noted in the geological report.
I made a visit to the site on January 9, 2007. The site has now been harvested. The location of the
proposed residence appears to be over 300 feet from the steeper slope in the west parcel. The
location of the proposed residence will be near the base of an approximately 30 foot high knoll
which has an approximate 38% slope measured by clinometer. The geotechnical report does
address set backs from the crest of slopes but does not address setbacks from the toe of this
slope.
Last summer I had talked with Mr. Lawrence and he indicated the knoll above the proposed home
may be lowered. This may relax or increase the slope. Currently the slope is 38% with the trees
removed.
In order to approve this geological report I recommend an addendum letter be provided from the
applicant's engineering firm. The letter should address:
• Do site conditions since the harvest prompt new recommendations
• Clarify the final planned outcome for the knoll slope facing the proposed residence
• Recommended setback for structures from the toe of the knoll slope.
Please feel free to contact me at 724 if you have any questions regarding these comments, or if
you feel any features need further discussion or attention.
Since
John Sliva
Programs Engineer
GEOTECHNICAL REPORT
100 WEST RELLER ROAD
SHELTON, WASHINGTON
PREPARED FOR
JIM & BRENDA LAWRENCE
BY
GEOTECHNICAL TESTING LABORATORY
OLYMPIA, WASHINGTON
JuNE 11 , 2007
J U N 2 p 'lte,",Jr)7
""�'Spiv'Cil.
yr '+ OTECHNICAL TESTING LABORATORY"
CONTACT INFORMATION
PREPARER INFORMATION
GTL PROJECT NUMBER: 07-0276
CONTACT: LANCE LEVINE
ADDRESS: 10011 BLOMBERG STREET SOUTHWEST
OLYMPIA,WASHINGTON 98512
TELEPHONE: (360)754-4612
FACSIMILE: (360)754-4848
EMAIL ADDRESS: GEOTESTLAB@COMCAST.NET
CLIENT INFORMATION
CLIENT: JIM&BRENDA LAWRENCE
HOME TELEPHONE: (360)893-8147
CELLULAR TELEPHONE: (360)970-8695
BILLING ADDRESS: 507 SKINNER WAY SW
ORTING,WASHINGTON 98360
SITE ADDRESS: 100 WEST RELLER ROAD
SHELTON,WASHINGTON 98584
PARCEL: 520257500080
GPS LOCATION: N47o 11.7941 W123o 15.5991
10011 Blomberg Street SW,Olympia, WA 98512 2
Phone#: (360)754-4612 Fax#: (360)754-4848
GEOTECHNICAL 'TESTING LABORATORY
SCOPE OF UNDERSTANDING
JIM&BRENDA LAWRENCE
507 SKINNER WAY SW
ORTING,WA 98360
RE: GEOTECHNICAL REPORT
100 WEST RELLER ROAD
SHELTON,WA 98584
PARCEL 520257500080
N47011.794'W 123°15.599'
Mr. &Mrs. Lawrence:
As per your request, we have conducted a soils exploration, foundation evaluation, and slope stability analysis for
the above referenced parcel. The results of this investigation,together with our recommendations, are to be found
in the following report. We have provided three copies for your review and distribution.
The results of the exploration and analysis indicate that conventional spread and continuous wall footings appear
to be the most suitable type of foundation for the support of the proposed structure. Some variability was
encountered in comparing the soil profiles of the site. Net allowable soil pressures, embedment depth, and total
expected settlements have been presented for the site later in the report.
We are also a full service laboratory that can meet all your building, testing (compaction, asphalt, concrete), and
inspection needs. 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.
of "Jagh� Respectfully Submitted,
GEOTECHNICAL TESTING LABORATORY fo�
Engineering Geplogfat .`
Coo 827 Harold Parks,L.G.,L.E.G.
c d_G e°\0 Senior Engineering Geologist
HAROLD PARKS
?-n ftAts X-al
10011 Blomberg Street SW,Olympia, WA 98512 3
Phone#: (360)754-4612 Fax#: (360)754-4848
GEOTEC'HNICAL NESTING LABORATORY
TABLE OF CONTENTS
CONTACTINFORMATION..................................................................................................................................2
SCOPEOF UNDERSTANDING.............................................................................................................................3
INTRODUCTION.....................................................................................................................................................5
SITECONDITIONS.................................................................................................................................................6
SURFACECONDITIONS ............................................................................................................................................6
SITEGEOLOGY ........................................................................................................................................................7
SITESOILS...............................................................................................................................................................8
SUBSURFACEEXPLORATIONS .................................................................................................................................8
SUBSURFACECONDITIONS......................................................................................................................................9
SLOPESTABILITY ....................................................................................................................................................9
CONCLUSIONS AND RECOMMENDATIONS................................................................................................10
GENERAL............................................................................................................................................................... 10
GEOLOGICALLYHAZARDOUS AREAS........................................................................................................11
LANDSLIDE HAZARD CLASSIFICATION.................................................................................................................. 11
SEISMIC HAZARD CLASSIFICATION....................................................................................................................... 11
EROSIONHAZARD CLASSIFICATION...................................................................................................................... 12
SLOPESTABILITY .................................................................................................................................................. 12
BUILDINGSETBACK .............................................................................................................................................. 13
SEISMIC—LIQUEFACTION HAZARD....................................................................................................................... 14
EROSIONCONTROL ............................................................................................................................................... 15
EARTHWORK.......................................................................................................................................................15
SITEPREPARATION................................................................................................................................................ 15
STRUCTURALFILL................................................................................................................................................. 16
SUITABILITYOF ONSITE SOILS AS FILL................................................................................................................. 16
CUTAND FILL SLOPES........................................................................................................................................... 17
FOUNDATIONSUPPORT......................................................................................................................................... 17
FLOORSLAB SUPPORT .......................................................................................................................................... 18
RETAININGWALLS................................................................................................................................................ 18
RETAININGWALL ALTERNATIVES........................................................................................................................20
SITEDRAINAGE.....................................................................................................................................................20
SEPTICIMPACT......................................................................................................................................................20
LIMITATIONS.......................................................................................................................................................21
FIGURE1 VICINITY MAP.......................................................................................................................................22
10011 Blomberg Street SW, Olympia, WA 98512 4
Phone#: (360) 754-4612 Fax#: (360) 754-4848
GZvoTEcHNicAL TESTING LABORATORY
INTRODUCTION
This report summarizes the results of our geotechnical consulting services for the proposed single-family
residence. The site is located along the north-facing hillside in western Mason County. The site is approximately
7.5 miles west of Shelton, Washington. The location of the site is shown relative to the surrounding area on the
Vicinity Map,Figure 1.
i
r
1_"�"'s� ..tea.. .� -•`= .�JM"`n�.`.� .�
r -
Our understanding of the project is based on our discussions with you and our explorations and review of the site.
We understand that the parcel is to be developed with a single-family residence. The site will be accessed by a
proposed driveway from Reller Road. In general, grading will consist of the excavation of the foundation,
footings,and septic drainfield. The approximate layout of the site is shown on the Site Plan, Figure 2.
The site slopes toward the north and east from the proposed building location. The steepest slope measured onsite
was approximately 80 percent. Therefore, Mason County requires that a geotechnical report be prepared in
accordance with the Critical Areas Ordinance.
The purpose of our services is to evaluate the surface and subsurface conditions at the site as a basis for providing
geotechnical recommendations and design criteria for the project and to satisfy the requirements of the Mason
County Critical Areas Ordinance. Geotechnical Testing Laboratory is therefore providing geologic and
hydrogeologic services for the project. Specifically, our scope of services for this project will include the
following:
1. Review the available geologic,hydrogeologic,and geotechnical data for the site area.
2. Conduct a geologic reconnaissance of the site area and surrounding vicinity.
3. Investigate shallow subsurface conditions at the site by observing the exposed soil and reviewing
published well logs.
4. Evaluate the landslide and erosion hazards at the site per the Mason County Critical Areas Ordinance
regulations.
5. Provide geotechnical recommendations for site grading including site preparation, subgrade preparation,
fill placement criteria(including hillside grading), temporary and permanent cut and fill slopes, drainage
and erosion control measures.
10011 Blomberg Street SW, Olympia,WA 98512 5
Phone#: (360) 754-4612 Fax#: (360) 754-4848
GEOT ' CHNICAL TESTING LABORATORY
4-
, 4 `
SITE CONDITIONS
SURFACE CONDITIONS
The proposed building site is located in an area of sparse residential development along the western margin of the
Puget Sound glacial upland in western Mason County. We conducted a reconnaissance of the site area on May
22, 2007. The site has a predominant northern exposure with minor slopes to the east and west. Site elevations
range from approximately 465 to 510 feet.
The building area of the site has vegetation common to the Northwest. The vegetation includes fir, alder, aspen,
cedar, and maple trees as well as salal, Scot's broom, huckleberry, bracken fern, sword fern, foxglove,blackberry,
holly,and grasses.
At the time of the site visit,we observed no evidence of active surface erosion. No evidence of deep-seated slope
instability was observed onsite. Raveling and sloughing were not observed onsite.
Surface water flow was not observed onsite. The general topography of the site area indicates that drainage flows
toward the north and possibly to the east from the proposed building location.
4 '
10011 Blomberg Street SW,Olympia, WA 98512 6
Phone#: (360)754-4612 Fax#: (360)754-4848
GEOTECHNICAL TESTING LABORATORY
SITE GEOLOGY
The site is generally situated within the Puget Sound glacial upland. The existing topography has been created by
the carving action of the glaciers. Extrusive igneous material outcrops throughout the site. A description of the
surficial soils is included in the"Site Soils" section of this report. In general,the soils are composed of weathered
and unweathered basaltic material.
The Geologic Map of Washington — Southwest Quadrant (1987) has mapped the site geology as deposits of
Eocene volcanic rocks(Evc). The report reads:
Volcaniclastic rocks — Andesitic volcaniclastic breccia, conglomerate, lithic tuff, volcanic
sandstone, and siltstone; commonly interbedded with feldspathic sandstones and andesite
flows; north of the Puyallup River, breccias and conglomerates of probable mudflow origin
dominate; between the Puyallup and Nisqually Rivers and north of the Skookumchuck River,
dominantly volcanic sandstones and siltstones, and lesser interbedded breccia and
conglomerate. Includes part of the Northcraft Formation.
y 1 (J
The Geologic Map of the Shelton 1:100,000 Quadrangle, Washington, by Logan (2003) describes the site as
Tertiary Igneous Rock(Eve). The Tertiary Igneous Rock(Eve)is described as:
Crescent Formation basalt, undifferentiated (lower to middle Eocene)—Submarine,
plagioclase pyroxene basalt with local diabase and gabbro; pervasive zeolite and chlorite
alteration in the matrix; commonly amygdaloidal with zeolite and(or) chlorite amygdules; dark
gray with greenish tint, brown where weathered, reddish and variegated along altered contact
zones; contains flows, pillow basalt, and breccias; refilled lava tubes common in breccias;
columnar joint orientation is commonly highly variable; highly vesiculated and (or) pillowed
units are commonly highly altered and contain abundant clay minerals, whereas thick units with
strong columnar joint formation tend to be less altered; commonly sheared and faulted; contains
rare interbeds of laminar basaltic siltstone or fine sandstone with foraminiferal faunas referable
to the L latisian Stage (Rau, 1981).
s .`�til•
r-_
r t _
10011 Blomberg Street SW, Olympia, WA 98512 7
Phone#: (360)754-4612 Fax#: (360)754-4848
GEOTECHMCAL TESTING LABORATORY
The Geologic Map of Southeastern Mason County, Washington, USGS Water-Supply Bulletin 29 by Noble and
Molenaar(1970)describes the site as Volcanic rocks. The Volcanic rocks(Tv)is described as:
Basalt of Crescent Formation, exposed only in Black Hills province and in northwestern corner
of study area. Generally dense and impermeable and unimportant as source of groundwater.
SITE SOILS
The Soil Survey of Mason County, Washington, USDA Soil Conservation Service(1960)has mapped the site soils
as Shelton gravelly loam, 5 to 15 percent slopes(Sd). The report reads:
The Shelton soils typically formed from gravelly glacial till. The substratum is cemented till.
They are described as having good natural drainage. Typically, there is no occurrence of a high
water table. Internal drainage is described as medium. Root penetration is limited by cemented
till at depths of 30 to 36 inches. Nearly all of this soil is 5 to 6 miles west of Shelton. It differs
from Shelton gravelly sandy loam, 5 to 15 percent slopes, in texture of the surface soil and
subsoil and in being 2 to 5 inches deeper to underlying till. The few areas bordering the
Cloquallum soils are also different in that the surface soil is more finely textured because of the
influence of Cloquallum parent material.
-NORM
�?, a ,r.:1Yj _ - _ _. ''•�� .r� .0 !`�. +..,,.�..
t
SUBSURFACE EXPLORATIONS
Subsurface conditions at the site were evaluated by observing the exposed building site soil and reviewing
available well logs. Groundwater was not encountered at the proposed building location. Research of
neighboring well logs within the same quarter section have reported static water levels ranging from 24 to 119 feet
below ground surface. Depth to competent soil is approximately 8 inches throughout the proposed building
location.
, ._ A& ,.
t:
�,. sA
u, d..�'O � - •� _ ° ,,, .y. 'fit , _ _
10011 Blomberg Street SW,Olympia, WA 98512 8
Phone#: (360)754-4612 Fax#: (360) 754-4848
GEOTECHNICAL TESTING LABORATORY
SUBSURFACE CONDITIONS
In general, dense Shelton gravelly loam was observed in the undisturbed portions of the site. Basaltic material
was observed below the Shelton material. Groundwater was not observed or encountered. Groundwater seepage
was not observed onsite. Based on the site topography and the fractured nature of the near surface rock,
seasonally perched groundwater conditions may not be expected even during periods of extended wet weather.
jLj
•i -.ate
r
SLOPE STABILITY
Small slopes of approximately 80 percent were observed onsite. Since slopes of 40 percent or greater with 10 feet
or more of vertical relief occur onsite, Mason County requires that a geotechnical report be completed according
to the Critical Areas Ordinance.
The near-surface soils are in a dense to very dense condition except at the ground surface. The surficial soils are
generally in a medium dense condition.
In general,the undisturbed native soils of the site consist of a mixture of variable amounts of sand, silt,gravel,and
cobbles. These soil materials are in a dense condition except where they have been disturbed by weathering
activity. No evidence of deep-seated landslide activity or significant erosion was observed onsite at the time of
our investigation.
Weathering, erosion, and the resultant sloughing and shallow landsliding are natural processes that can affect
steep slope areas. Instability of this nature is typically confined to the upper weathered or disturbed zone, which
has been disturbed and has a lower strength. Raveling and sloughing were not observed onsite.
Significant weathering typically occurs in the upper 2 to 3 feet and is the result of oxidation, root penetration,
wet/dry cycles, and freeze/thaw cycles. Erosion in steep slope areas such as this can be reduced by encouraging
vegetation and discouraging runoff from the steep slopes. Erosion control recommendations for the sloping areas
are provided in the"Erosion Control"section of this report.
ffl9qf
N
L
10011 Blomberg Street SW, Olympia, WA 98512 9
Phone#: (360)754-4612 Fax#: (360) 754-4848
GEOTECHNICAL TESTING LABORATORY
AS
CONCLUSIONS AND RECOMMENDATIONS
GENERAL
Based on the results of our site reconnaissance, subsurface observations, and our experience in the area, it is our
opinion that the site is suitable for the proposed project. The proposed building location is stable relative to deep-
seated instability and will not be affected by the proposed structure. The proposed structure will not undermine
adjacent slopes. Proper drainage control measures will reduce or eliminate the potential for erosion in this area
and improve slope stability. 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.
In general, the Sinclair soils observed at the site may be suitable for use as structural fill material. Saturated soil
conditions may be associated with these soils during or following extended periods of rainfall. However, to
reduce grading time and construction costs, we recommend that earthwork be undertaken during favorable
weather conditions.
Conventional construction equipment may be utilized for work at the site. Conventional spread footings may be
utilized at the site for support of the structure. We do recommend that roof and footing drains be installed for the
structure with conventional spread footings. A vapor barrier is recommended for all slab-on-grades.
Pertinent conclusions and geotechnical recommendations regarding the design and construction of the proposed
single-family residence are presented below.
f
Y
Y..
10011 Blomberg Street SW, Olympia, WA 98512 10
Phone#: (360)754-4612 Fax#: (360)754-4848
%AOTECHNICAL 'TESTING LABORATORY
GEOLOGICALLY HAZARDOUS AREAS
LANDSLIDE HAZARD CLASSIFICATION
The Mason County Critical Areas Ordinance(17.01.100)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 rockfalls (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 1 S%(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.
SEISMIC HAZARD CLASSIFICATION
The Mason County Critical Areas Ordinance(17.01.102)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, Qal, 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
This site does qualify as a seismic hazard area because the site is categorized as, "l.f. Areas designated as
potential Landslide Hazard Areas"
10011 Blomberg Street SW,Olympia,WA 98512 11
Phone#: (360)754-4612 Fax#: (360)754-4848
G oTEcHNicAL TESTING LABORATORY
ORY
EROSION HAZARD CLASSIFICATION
The purpose of the Erosion Hazard Section(17.01.104) is to identify areas that present potential dangers to public
health and safety, and 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 1 S%or steeper:
a.Alderwood gravelly sandy loam("Ac"and"Ad')
b. Cloquallum silt loam rCd')
c. Harstine gravelly sandy loam ("Hb')
d. Kitsap silt loam ("Kc')
The soils at the site are mapped as Shelton gravelly loam(Sd). This site does not meet the technical criteria of an
erosion hazard area.
.
SLOPE STABILITY
Based on our field observations, explorations and our experience with the soil types encountered on the property,
we conclude that although slopes approach 80 percent, they are generally stable relative to deep-seated failure in
their present configuration. The proposed building location is in an area where the slope is approximately 5
percent.
Excavation and backfilling will occur based on appropriate engineering and earthwork recommendations found in
the following"Earthwork" section. Grading in the building portion of the site should be conducted in accordance
with geotechnical recommendations provided herein.
As previously discussed, weathering, erosion, and the resultant surficial sloughing and landsliding are natural
processes that affect slope areas. Significant weathering typically occurs in the upper 2 to 3 feet and is the result
of oxidation,root penetration,wet/dry cycles and freeze/thaw cycles. Over excavation may be necessary to ensure
the removal of deleterious material.
These processes can be managed and the risk reduced through proper construction of the residence. Erosion
control recommendations in the slope and buffer areas are provided in the "Building Setback" and "Erosion
Control"sections of this report.
10011 Blomberg Street SW,Olympia, WA 98512 12
Phone#: (360)754-4612 Fax#: (360)754-4848
(Xi 1160
"10 TECHW AL TESTING LABORATORY
BUILDING SETBACK
A building setback (50 feet) from landslide
hazard areas is required unless evaluated and
reduced by an engineering geologist or a
licensed professional engineer. Based on our
geotechnical evaluation of the site and our
experience in the area, a building setback will
be needed for this lot. The building setback
may be measured from the bottom of the
footing to the face of the steep slope in Setback
accordance with the International Building
Code (1805.3.1). The following figure
represents a shear angle for the gravelly sandy
loam. Shear angle and cohesion are variables
used to model the site.
Peak Shear Stress vs. Normal Stress
3000
45`
2500
a 2000 ' ---
d
1500 —
A
W
V)
Y
a 1000
a
500
t 19 ton
AD—1f2 ton
--A-1 ton
0
0 500 1000 1500 2000 2500 3000
Normal Stress(psf)
Slope stability was modeled using the GeoStudio 2004 program (version 6.20) in both static and dynamic
conditions (ca = 0.30). Factors of safety were determined using Bishop's, Janbu, and the Morgenstern-Price
methods. The site was modeled using a monolithic layer of unweathered basalt. The material was determined to
have a unit weight of 135 pcf, cohesion of 400 psf, and a shear angle (�) of 451. Under static conditions, the
slopes remained stable to deep-seated and shallow failure (F.S. = 3.34). Under dynamic loading, the 3328
computations demonstrated that the slope is not susceptible to surficial raveling or large deep-seated failure. The
following figure illustrates the moment factor of safety for slope "A" under the existing conditions. The critical
slip surface factor of safety is equal to 2.02. Mason County code requires a factor of safety to be at least 1.1 at the
proposed building location. This figure is the solution of greatest concern and exhibits the need for a building
setback of 20-feet from the crest of the northern slope. No building setback will be required from the small
eastern slope. All foundation elements shall be constructed on native material or engineered fill material.
10011 Blomberg Street SW, Olympia, WA 98512 13
Phone#: (360)754-4612 Fax#: (360)754-4848
GEOTEC.HNicA L TESTING LABORATORY
Lawrence Site -- Slope A
M:A.a, ••.
530 � • /
520
510
C ••.
O 500 Description: Basalt- .•
aso Wt: 135
� aeo Cohesion: 300
N 470
W 460
450
0 50 ton 150 ?0c 250 300 350 aoo aso 500 550 600
Distance (ft)
As previously discussed, weathering, erosion and the resultant surficial sloughing and shallow landsliding are
natural processes that affect slope areas. Minor surficial raveling and sloughing was observed along the
southeastern road cut. To manage and reduce the potential for these natural processes, we recommend the
following:
➢ No drainage of concentrated surface water or significant sheet flow onto the sloped areas.
➢ No filling within the setback zone unless retained by retaining walls or constructed as an engineered fill.
SEISMIC—LIQUEFACTION HAZARD
According to the Seismic Zone Map of the United States contained in the 2003 International Building Code(IBC),
the project site is located where the maximum spectral response acceleration is 45 percent of gravity(g).
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 very low liquefaction potential due to
bedrock.
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 B. Site class B is rock.
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 1615.1.1 (IBC). This is based on probing with a 'V2-inch
diameter steel probe rod. The shallow soil conditions were assumed to be representative for the site conditions
beyond the depths explored.
Based on our review of the subsurface conditions, we conclude that the site soils are only mildly susceptible to
liquefaction. The near-surface soils are generally in a dense condition and the static water table is located well
below the surface. Shaking of the already dense soil is not apt to produce a denser configuration and subsequently
excess pore water pressures are not likely to be produced.
10011 Blomberg Street SW,Olympia,WA 98512 14
Phone#: (360)754-4612 Fax#: (360)754-4848
GJEMOTECHNICAL TESTING LABORATORY
it
,
e ..
EROSION CONTROL
It is our opinion that the potential erosion hazard of the site is not a limiting factor for the proposed development.
Removal of natural vegetation should be minimized and limited to the active construction areas. Yard
landscaping around the home is permissible, but understory growth on the slopes should be encouraged as much
as possible as a deterrent to erosion. Hazard trees located on steep slopes may be removed only if the stumps
remain to deter erosion.
Temporary and permanent erosion control measures should be implemented and maintained during construction
and/or as soon as practical thereafter to limit the additional influx of water to exposed areas and protect potential
receiving waters.
Erosion control measures should include, but not be limited to, silt fences, berms, and swales with ground
cover/protection in exposed areas. A typical silt fence detail is included on Figure 2. Any re-contouring of the
site will create a need for erosion control measures as listed above.
EARTHWORK
SITE PREPARATION
All areas to be excavated should be cleared of deleterious matter including any existing structures, debris, duff,
and vegetation. Based on our observations, we estimate that stripping on the order of 2 to 12 inches will be
necessary to remove the root zone and surficial soils containing organics. Areas with deeper, unsuitable organics
should be expected in the vicinity of depressions or heavy vegetation. Stripping depths of up to 3 feet may occur
in these areas. These materials may be stockpiled and later used for erosion control and landscaping. Materials
that cannot be used for landscaping or erosion control should be removed from the project site. No foundation
elements shall be constructed on fill material.
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. We recommend that trees be removed with the roots, unless
located on a slope. Excavations for tree stump removal in any building area should be backfilled with structural
fill,compacted to the density requirements described in the"Structural Fill" section of this report.
If structural fill is needed, we recommend that a member of our staff evaluate the exposed subgrade conditions
after removal of vegetation and topsoil stripping is completed.
10011 Blomberg Street SW,Olympia,WA 98512 15
Phone#: (360)754-4612 Fax#: (360)754-4848
GEOTECHNICAL TESTING LABORATORY
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.
i n
4-4
y r
A
aY
STRUCTURAL FILL
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)to within 2 feet of
subgrade and 95 percent MDD in the upper 2 feet.
The appropriate lift thickness will depend on the fill characteristics and compaction equipment used. We
recommend that the appropriate lift thickness be evaluated by our field representative during construction.
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 9 percent(by weight)passing the No. 200 sieve
based on that fraction passing the 3/4-inch sieve.
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.
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.
SUITABILITY OF ONSITE SOILS AS FILL
Onsite soils may be considered for use as structural fill if industry standards are satisfied. In general, the native
soils (sand, silt, and gravel) encountered on the site must have less than 10 percent fines(material passing the US
No. 200 sieve)to be suitable for use as structural fill.
10011 Blomberg Street SW, Olympia, WA 98512 16
Phone#: (360)754-4612 Fax#: (360) 754-4848
Limo EcHNicA L TESTING LABORATORY
TORY
1
a s
� V
ti.
_, i� .4 -. - ,. •... ,. ) 'tea.' - �O
CUT AND FILL SLOPES
All job site safety issues and precautions are the responsibility of the contractor providing services and/or work.
The following cut/fill slope guidelines are provided for planning purposes.
Temporary cut slopes will likely be necessary during grading operations. As a general guide,temporary slopes of
1.5 to 1 (horizontal to vertical) or flatter may be used for temporary cuts in the upper 3 to 4 feet of the glacially
consolidated soils that are weathered to a loose/medium-dense condition. Temporary slopes of 1 to 1 or flatter
may be used in the unweathered dense to very dense sands and gravel.
These guidelines assume that all surface loads are kept at a minimum distance of at least one half the depth of the
cut away from the top of the slope and that significant seepage is not present on the slope face. Flatter cut slopes
will be necessary where significant raveling or seepage occurs.
Surface drainage should be directed away from all slope faces. All slopes should be seeded as soon as practical to
facilitate the development of a protective vegetative cover or otherwise protected.
FOUNDATION SUPPORT
Where foundation elements are located near slopes between 5 and 30 percent, the footings should be located a
minimum of 2 times the footing width from the slope face(horizontally), and founded in medium dense or denser
native soils or properly prepared structural fill.
We recommend a minimum width for isolated and continuous wall footings to meet IBC 2003. 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.
The weight of the footing and any overlying backfill may be neglected. The allowable bearing value may be
increased by one-third for transient loads such as those induced by seismic events or wind loads.
Lateral loads may be resisted by friction on the bases of footings and floor slabs and as passive pressure on the
sides of footings. We recommend that an allowable coefficient of friction of 0.50 be used to calculate friction
between the concrete and the underlying soil. Active pressure may be determined using an allowable equivalent
fluid density of 250 pcf(pounds per cubic foot).
10011 Blomberg Street SW,Olympia, WA 98512 17
Phone#: (360)754-4612 Fax#: (360)754-4848
GEOT ECHNICAL TESTING LABORATORY
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 y2 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.
FLOOR SLAB SUPPORT
Slabs-on-grade should be supported on medium dense or dense native soils or on structural fill prepared as
described in the "Structural Fill" section of this report. We recommend that floor slabs be directly underlain by a
minimum 6-inch thickness of coarse sand and/or gravel containing less than 5 percent fines (by weight). The
drainage material should be placed and compacted to an unyielding condition.
A synthetic vapor barrier may be used for the control of moisture migration through the slab, particularly where
adhesives are used to anchor carpet or tile to the slab. A thin layer of sand may be placed over the vapor barrier
and immediately below the slab to protect the liner during steel and/or concrete placement. The lack of a vapor
barrier could result in wet spots on the slab, particularly in storage areas.
Ar-
.✓„plly
r
RETAINING WALLS
Retaining walls may be utilized on the sloping portion of the site to retain fill material. The lateral pressures
acting on the subgrade and retaining walls will depend upon the nature and density of the soil behind the wall. It
is also dependent upon the presence or absence of hydrostatic pressure. If the adjacent exterior wall space is
backfilled with clean granular, well-drained soil (washed rock), the design active pressure may be determined
using an active pressure coefficient equal to 0.25 (Ka = 0.25). This design value assumes a level backslope and
drained conditions as described below.
Retaining walls located on or near the toe of the slope that extends up behind the wall should be designed for a
lateral pressure, which includes the surcharge effects of the steep slope in proximity to the wall. Although not
expected at this site,the following data is provided for planning purposes.
For an irregular or composite slope, the equivalent slope angle may be determined by extending a line upward
from the toe of the wall at an angle of 1 to 1 (Horizontal to Vertical)to a point where the line intersects the ground
surface. The surcharge effects may be modeled by increasing the equivalent fluid pressure for flat ground by the
percentage given in the following table:
10011 Blomberg Street SW,Olympia,WA 98512 18
Phone #: (360)754-4612 Fax#: (360)754-4848
GEOTEcHNicAL TESTING ]LABORATORY
Sol
"1►
SLOPE INCLINATION:EQUIVALENT FLUID PRESSURE
Slope Angle Percent Increase Equivalent Fluid Pressure
Horizontal 0% 35 pcf
3H:1 V 25% 44 pcf
2H:1 V 50% 53 pcf
1 H:1 V 75% 61 pcf
If the walls are greater than 4 feet in height, exclusive of the footing, additional design considerations should be
applied.
Positive drainage, which controls the development of hydrostatic pressure, can be accomplished by placing a zone
of coarse sand and gravel behind the walls. The granular drainage material should contain less than 5 percent
fines. The drainage zone should extend horizontally at least 18 inches from the back of the wall. The drainage
zone should also extend from the base of the wall to within 1 foot of the top of the wall. The drainage zone
should be compacted to approximately 90 percent of the MDD. Over compaction should be avoided as this can
lead to excessive lateral pressures.
A perforated PVC pipe with a minimum diameter of 4 inches should be placed in the drainage zone along the base
of the wall to direct accumulated water to an appropriate discharge location.
We recommend that a non-woven geotextile filter fabric be placed between the drainage material and the
remaining wall backfill to reduce silt migration into the drainage zone. The infiltration of silt into the drainage
zone can,with time,reduce the permeability of the granular material.
.� .„I,T��l '`-. �'` ,�}-',,_ .L� •- ems.. ,�'..�t'. -
10011 Blomberg Street SW, Olympia, WA 98512 19
Phone#: (360)754-4612 Fax#: (360)754-4848
y
rya f�„ e �•.. _ . s. -
�' .cif µTR. ,!. •��"�.+ a� r: �. '4.1� � ♦'J ,�k =i
1sr.,
The filter fabric should be placed in such a way that it fully separates the drainage material and the backfill, and
should be extended over the top of the drainage zone.
Lateral loads may be resisted by friction on the bases of footings and as passive pressure on the sides of footings
and the buried portions of the wall. We recommend that an allowable coefficient of friction of 0.40 be used to
calculate friction between the concrete and the underlying soil.
RETAINING WALL ALTERNATIVES
Typically, block wall systems are more cost effective for long-term walls than the other options. Specific design
criteria for these options can be provided at your request by the block manufacturers.
SITE DRAINAGE
All ground surfaces, pavements and sidewalks should be sloped away from the residence and associated
structures. Surface water runoff should be controlled by a system of curbs, berms, drainage swales, and/or catch
basins and tight-lined into the appropriate drainage facilities or to the base of the northern slope. We recommend
that conventional roof drains be installed. Footing drains shall be installed for the single-family residence. The
roof drain should not be connected to the footing drain. For footing drains, the drain invert should be below the
bottom of the footing.
We recommend that the collected stormwater runoff be directed into the appropriate drainage facilities by tight-
line. Drainage control measures are included on Figure 3. Onsite irrigation to lawn areas should be closely
monitored. We do not expect any adverse affects on the recharge condition of the groundwater system.
SEPTIC IMPACT
The proposed septic drainfield will be located in the central portion of the site. The proposed drainfield location
setback will be greater than 30 feet from the toe of any slope over 40 percent. We conclude the slope stability of
the site will not be adversely impacted.
10011 Blomberg Street SW,Olympia,WA 98512 20
Phone#: (360)754-4612 Fax#: (360)754-4848
GEOTECHNicAL TESTING LABORATORY
1•D 1 xa� 1
Aug a
LIMITATIONS
We have prepared this report for the use of Jim and Brenda Lawrence and members of their design team,to use in
the design of a portion of this project. The data used in preparing this report, and this report, should be provided
to prospective contractors for their bidding or estimating purposes only. Our report, conclusions and
interpretations are based on data from others and our site reconnaissance, and should not be construed as a
warranty of the subsurface conditions. This report is quantified as a micro-study and not a macro-study.
Geotechnical Testing Laboratory and its personnel cannot be responsible for unforeseen and widespread geologic
events(such as earthquakes, large-scale faulting,and mass wasting)beyond the scope of this project.
Variations in subsurface conditions are possible and may occur with time. A contingency for unanticipated
conditions should be included in the budget and schedule. Sufficient consultation should be made with our firm
during construction to confirm that the conditions encountered are consistent with those indicated by the
recommendations and for design changes should the conditions revealed during the work differ from those
anticipated,and to evaluate whether earthwork and foundation installation activities comply with contract plans.
If our analysis and recommendations are followed, we do not anticipate any on site or off site impact from the
construction. It is our conclusion that potential landslide hazards from the landslide area can be overcome so as
not to cause harm to property,public health and safety,or the environment.
The scope of our services does not include services related to environmental remediation and construction safety
precautions. Our recommendations are not intended to direct
the contractor's methods, techniques, sequences or
procedures, except as specifically described in our report for
consideration in design.
If there are any changes in the loads, grades, locations,
configurations or types of facilities to be constructed, the
conclusions and recommendations presented in this report
may not be fully applicable. If such changes are made, we
should be given the opportunity to review our
recommendations and provide written modifications or
verifications, as appropriate. Recent changes in the Mason
County Code require our firm to revisit the site (after six
months) to ensure the conditions are in agreement with our
original report.
10011 Blomberg Street SW,Olympia,WA 98512
Phone#: (360)754-4612 Fax#: (360)754-4848
GEOTECHNICAL TESTING LABORATORY
FIGURE 1 VICINITY MAP
BM •OM
759
- 1 t_ I yt011
18
_ I �
• �Y
l I
i r
q 4 �/
r
AWRFNw
26Ic
, a
I
i
I' Porrow
I f
' s 49 _
_ 8{ 630
)
01
/
Borrow
Pit
Bi amp
shop
10011 Blomberg Street SW, Olympia, WA 98512
Phone#: (360) 754-4612 Fax#: (360) 754-4848
1/2 INCH MINIMUM DIAMETER STEEL ROD
(STRAP)CLAMPED SECURELY TO PIPE
CORRUGATED TIGHTLINE 4 INCH
MINIMUM,6 INCH SUGGESTED
qM 10
. n�^•iY•I:N.^:i^ �l/^t` ....:j...:'mow.
+'�� >' ,.r•t:•^,4�>+.tt \w�r•`.RT�y` n::ti+;".; �_L:
•fin:' .>..C.:.,u.�:.:�ii� °•:"•..:f_tea�l'�".�.rx'S,•�f_ Yj,^. _., r,1�•or
'.': :ti'•' -;\ ..;_ .. ,. ;,..`.-��•"\'his li.�•;l;T:,
J.
`�• �r: ��:r;i';�" mil'- •:.1•:(:'• :,t_i.•t..:.. y�4,' .v,��.�..•
TIGHTLINE ANCHORED WITH TWO,
3 FOOT REBAR LENGTHS OR BOLTS.
FLARE END SECTION \r:
'QUARRY SPALL
OR ENERGY :�: � ' � =• ...::_..�.:;; . .;;A.,.,.w..�...
DISPERSION DEVICE
GRASS-LINED SWALE SHOULD BE A
MINIMUM ONE FOOT WIDE AT THE
BOTTOM AND ONE FOOT DEEP WITH
A MAXIMUM SLOPE OF 5 PERCENT.
MINIMUM 4 FEET
LEVEL SECTION
GEOTEXTILE FABRIC
Geotechnical Testing Laboratory
Geotechnical Services 10D118bmbergSt.SW ��
QA/QC Services Olympia,WA 99512 FIGURE 3
e Pbo�e:(360)'SM1612 DRAINAGE DETAILS
Testin Services Fax:(3W)754-4M Not to Scale
GEOTECHNICAL TESTING LABORATORY
JIM& BRENDA LAWRENCE
507 SKINNER WAY SW ECE 11;`
ORTING,WA 98360 ---—-.
RE: GEOTECHNICAL REPORT MCCD - PLAN, ^N
100 WEST RELLER ROAD
SHELTON,WA 98584
PARCEL 520257500080
SEPTEMBER 12,2007
Lawrences:
As per the request of the third party reviewer, we are providing additional comments to satisfy the requirements
of the Mason County Resource Ordinance for Geologically Hazardous Areas.
Item i requests the L.E.G. stamp be properly signed over with a handwritten expiration date and signed date.
We have included the properly signed page with this letter.
Item 2 suggests that all figures and photos be annotated with text references in the report. We thank the
reviewer for the advice. Mason County Code makes no such suggestions; we will make the appropriate changes
on future reports.
Item 3 (Page 9) confuses the saturation of the onsite material with the presence of a shallow water table. The
reviewer must not confuse wet soil after a rain event with a perched or unconfined groundwater surface.
Item 4 (Page 13) requests clarification of the shear specimen and the slope model label. The shear sample was
collected from the onsite weathered material. A gradation classifies the material as gravelly sandy loam
(gravelly sandy silt). Since no clear contact was observed between the weathered material and the parent
material, the slope model (40 feet in height) illustrates the parent(basaltic) material.
Item 5 (Page 13) requests clarification of the dynamic values in the slope model. The dynamic coefficient
(ca 0.3) is higher than the Code mandated dynamic coefficient (ca 0.15). We modeled all sites with the higher
value to be conservative. Instead, we only confused the reviewer.
Item 6 (Page 14) requests our review of additional sources detailing the faults in the Mason County area. We
have since reviewed the available references and determined that the site is not underlain by or is near to any
mapped faults.
Item 7 (Page 17) requests changes to the report based on, "Active pressure may be determined using an
allowable equivalent fluid density of 250 pcf(pounds per cubic foot)." The comment contains an inaccurate
quote. The geotechnical report reads, "Active pressure may be determined using an allowable equivalent fluid
density of 150 pcf(pounds per cubic foot)."
10011 Blomberg Street SW,Olympia, WA 98512
Phone#: (360) 7544612 Fax#: (360) 754-4848
GEOTECHNICAL TESTING LABORATORY
Item 8 (Page 17) requests that we modify our recommendations for foundation support and retaining walls. We
recommend a coefficient of friction of 0.50 for concrete in contact with underlying soil (foundation support)
and a coefficient of friction of 0.40 for concrete in contact with underlying soil (retaining walls). The lower
value for retaining walls is a conservative coefficient because a retaining wall is more likely to mobilize than a
foundation. Additionally, the values are within 20 percent of each other and does not constitute a significant
difference.
Item 9 (Page 18 and 19) reads, "Provide calculations to substantiate your conclusions for active earth
pressures." Mason County Code does not require calculations to substantiate our conclusions for active earth
pressures. Hence, we will not validate the request with a reply.
Item 10 and 11 (Page 19 and 20) requests additional information on the proposed retaining walls. The current
plan does not utilize retaining walls.
Item 12 (Page 20) requests a "discussion of upland waterbodies and wetlands." Reviewing the aerial
photographs and topographic map (vicinity map) contained in our report, we conclude that no upland
waterbodies or wetlands exist between the site and the topographic ridge located 50 feet to the south.
Item 13 (Page 20) requests that the septic drainfield, "... be verified by Mason County Code based on required
wetland buffer, which will vary based on wetland delineation." We are not sure why this comment is included
with the review of the geotechnical report. The Mason County Code reads, "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."
The geotechnical report reads, "The proposed septic drainfield will be located in the central portion of the site.
The proposed drainfield location setback will be greater than 30 feet from the toe of any slope over 40 percent.
We conclude the slope stability of the site will not be adversely impacted."
Item 14 (Site Plan) requests changes to the site plan to meet the latest version of the Mason County Code. The
revised site plan is included with this letter. The reviewer also requests that the silt fence details be provided.
We respectfully suggest the reviewer carefully inspect the site plan for the previously provided silt fence details.
After making the appropriate changes (per Mason County Code), we adamantly request that a building permit
be granted without further delay.
We appreciate this opportunity to be of service to you and we look forward to working with you in the future.
If you have �A�oncerning the above items, the procedures used, or if we can be of any further
assistance p one number listed below.
co �.!>
Respectfully Submitted,
GEOTECHNICAL TESTING LABORATORY
Enginee oio 1st ,� Harold Parks, L.G., L.E.G.
c+ 27 �`' i Senior Engineering Geologist
used Ge°`O 'iZ107
cc: Mas ommunity Development, Robert Fink
�xP>�1d 7/311oPS I0011 Blomberg Street SW,Olympia, WA 98512 2
Phone#: (360)754-4612 Fax#: (360) 754-4848
GEOTECHNICAL TESTING LABORATORY
SCOPE OF UNDERSTANDING
Jim& BRENDA LAWRENCE
507 SKINNER WAY SW
ORTING,WA 98360
RE: GEOTECHNICAL REPORT
100 WEST RELLER ROAD
SHELTON,WA 98584
PARCEL 520257500080
N470 11.794' W123° 15.599'
Mr. & Mrs. Lawrence:
As per your request, we have conducted a soils exploration, foundation evaluation, and slope stability analysis
for the above-mentioned parcel. The results of this investigation, together with our recommendations, are to be
found in the following report. We have provided three copies for your review and distribution.
The results of the exploration and analysis indicate that conventional spread and continuous wall footings
appear to be the most suitable type of foundation for the support of the proposed structure. Some variability
was encountered in comparing the soil profiles of the site. Net allowable soil pressures, embedment depth, and
total expected settlements have been presented for the site later in the report.
We are also a full service laboratory that can meet all your building, testing (compaction, asphalt, concrete), and
inspection needs. 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.
�e 01 was/7- Respectfully Submitted,
0� GEOTECHNICAL TESTING LABORATORY
Harold Parks, L.G., L.E.G.
Engine is Senior Engineering Geologist
O�
oat Ge°`
HQ.ROLD PARKS
8�_'M 7/�'11 C'
10011 Blomberg Street SW,Olympia, WA 98512
Phone#: (360) 754-4612 Fax#: (360) 754-4848
Se&ing Clients-in
Pacif&Northwest States AGUA TIERRA
and Provinces since 1993 LAND & WATER SERVICES, INC.
RECEIV :
Jim and Brenda Lawrence "
li
507 Skinner Way SW JUL 2 4 2006
Orting, WA 98360 MASON
COUNTY
SUBJECT: SLOPE STABILITY GEOTECHNICAL REPORT(Mason County)
Location: West Reller Road(off of Highland Road)
Parcel Number/s: 520 257 5000 70 and 520 257 5000 80
Dear Mr. and Mrs. Lawrence:
At your request Agua Tierra Land and Water Services,Inc. (Agua Tierra)conducted a
Geotechnical Report(GR) for the above-mentioned property. This work was pursuant to Mason
County Resource Ordinances governing landslide hazard areas.
1.0 INTRODUCTION
The landslide hazard area ordinance mandates a site evaluation for development plans proposed
within 300 feet of a landslide hazard area(i.e. within 250 feet of slope(crest or toe) plus 50 feet
of buffer,totaling 300 feet). The type and rigor of site evaluation performed depends on the
intensity of slope conditions. A Geologic Assessment(GA)or the more rigorous Geotechnical
Report(GR)are mandated by site conditions, interpretation and opinion of the slope professional,
and ultimately the findings of County staff.
Definition of Landslide Hazard Areas
County ordinance generally defines landslide hazard areas based on the presence of one or more
of the following characteristics (determined to be present by County staff or investigator):
(1) Geomorphic indications of past slope instability;
(2) Artificial oversteepened or unengineered slopes(cuts or fills);
(3) Slopes containing soft or potentially liquefiable soils;
(4) Slopes oversteepened/unstable as result of stream or wave erosion;
(5) Slopes greater than 15 percent(8.5 degrees)AND potentially containing a
slippage plain and groundwater discharge(mandating a Geologic Report-GR); or
(6) Slopes greater than 40 percent(21.8 degrees)with 10 or more feet of vertical
relief, excluding bedrock(mandating a Geologic Report GR).
Typically either a GA or a GR are prepared pursuant to these conditions. The ordinance further
calls for the discretion of the investigator to govern the need to increase evaluation rigor from that
of a GA to a GR if site or proposed development conditions so warrant. All work done under
either study is subject to final approval by the County.
Site inspection revealed characteristics from the above list including items: (1), (2), and(6)with
bedrock at or near surface.
In our opinion site conditions in combination with the proposed low intensity land use do not
warrant the rigor and expense of a full Geotechnical Report. We therefore recommend that the
AGUA TIERRA LAND&WATER SERVICES,INC.
506 Edison Street SE,Suite'00 • Oiyrrpia,VVA 98501 • T.11360)754-3755 • - '001754-3431 • w,.vw a5uatierra net
1
County accept a limited scope Geotechmcal Report for this project. Consistent with this
recommendation, a limited scope report follows.
The following sections of this report provide an evaluation of site conditions within a context of
the proposed development plans. Recommendations are provided prior to making larger financial
investments.
1.1 SITE LOCATION
The project site is located on the undeveloped Weller Road in rural Mason County. Address and
parcel number information are noted above and location maps are provided in the Attachments.
Note: all supporting figures for this report are included in the Attachments. Several maps show
the site location and specific natural resource features(as referenced within the report).
1.2 EXISTING LANDUSE and GENERAL PROPERTY DESCRIPTION
Two adjoining parcels are involved in this project. Each parcel is approximately 5 acres in size.
The land is currently undeveloped and forested except for a gravel road. A parcel map showing
site layout and the existing road is included within the Attachments.
A substantial amount of this property is covered by wetland or its buffer. A wetland report was
prepared by Agua Tierra under separate cover. The eastern parcel is lower elevation with gently
undulating topography. Wetland area extends onto both parcels. Steep ground lies within the
western parcel. Some flatter ground lies within the southwest corner of the overall site(upslope
of the road). We understand the proposed use of this upland area includes timber removal and
pasture.
The gravel road is cut into the side slope as it ascends the hillside within the western parcel.
Erosion within the road and the back cut berm were noted. Simple drainage and erosion control
measures for the road will address the erosion observed and are discussed later.
1.3 PROPOSED LANDUSE/SCOPE OF THIS REPORT
Proposed landuse for the site includes but is not necessarily limited to:
• A residence and garage;
• Driveway access;
• Utility installation: Well, power, septic, phone;
• Possible additional shop building or out building/s for livestock;
• Timber harvest; and
• Pasture installation on the hill top in the southwest corner of the site.
1.4 FIELD WORK
Field work occurred on two separate visits and included a meeting with owners to understand
proposed project locations. We inspected slope, soils, wetlands area, and drainage conditions.
We examined the exposed slope in the road cut and within the same formations on the property.
Observations included a traverse of the site by foot; visual inspection of geologic landforms and
exposed stratigraphy on and/or adjacent to the site; condition of any existing human built
development on or adjoining the site; and comparison of site conditions with the proposed
development plans. Slope geometric measurements were collected. Any observed geomorphic
indicators of active slope processes were noted.
2.0 TOPOGRAPHY
The property can be divided into four distinct topographic zones:
• Undulating to flatter lowland/wetland dominating the eastern parcel;
• Slope(with bedrock)diagonally through the western parcel. An old logging road
traverses the slope within the lower third. The road parallels slope contour and is cut into
bedrock in some locations. Based on visual age estimate of vegetation growing in the old
road, it appears to be 30 -35 years or more since its last use. Old slope cuts/fills
associated with the road are generally stable. The overall slope rate was measured by
clinometer. A representative slope rate of47 percent was determined;
• The cut/ fill slopes associated with the active access road traverse the slope. The upslope
back cut is eroding locally. No signs of mass wasting were observed. Bedrock was
observed locally; and the
• Upland/hilltop area within the southwest corner of the parcel. This area is forested,
planned for harvest and conversion to pasture. It measures about 2 acres.
Wetland, slope, active road, and hilltop areas are noted on the General Sketch Map in the
Attachments.
3.0 GEOLOGY,GEOMORPHOLOGY AND SOILS
3.1 GEOLOGY
Geologic mapping for the vicinity is included within:
Geologic Map of the Shelton 7.S-minute Quadrangle, Mason and Thurston Counties, WA
(Washington Department of Natural Resources, Division of Geology and Earth
Resources, OFR 2003-04); by Henry W. Schasse, Robert L. Logan, Michael Polenz, and
Timothy J. Walsh; 2003
and in,
Geology and Related Ground Water Resources, Southeastern Mason County,WA.
(Washington Department of Water Resources Water Supply Bulletin 29, by Molennar,
Dee, and Noble; J.B, 1970)
Mapped geologic units on site are shown in the Attachments and included:
• Crescent Formation(lower to middle Eocene): Basalt(and diabase). Basalt typically
occurs as fine to coarse grained, blocky sills and submarine flows or possibly
subaerial flows; and
• Alluvium: Silt, sand, gravel, and peat deposited in stream beds and estuaries,these
may include some lacustrine(lake) deposits.
Site inspection confirmed the presence of basalt and alluvial materials. The basalt was present
within the western portion of the site in the hillslope and appeared to be just below the surface in
the hilltop portion of the site. Surface soil (soil mantle)overlying the basalt is subject to creep on
sloped ground. Moisture and gravity acting on this thin mantle(not appearing to be more than 10
feet deep)appears to have some minor localized influence on slope motion. The lower portion of
the site, the home area, and the wetland area include alluvial materials.
The gravel road through the site is positioned within the basalt material as it traverses the sloped
portion of the site. The proposed pasture area is located above the basalt unit with surface soils as
described later.
3.2 SURFACE CONDITIONS AND GEOMORPHOLOGY
Land surface conditions were inspected, slope geometry measurements were collected and
evaluated, and the site was generally inspected for indicators of slope mobility/ instability.
Erosion was observed along the access road downslope fill shoulder, upslope cut bank, and
surface. Surface water runoff on exposed soil areas were noted as the source. The road surface
itself represented the greatest concern. Ditch design improvements are needed to divert water
from the surface and into a controlled route. Ditch check dams may be required.
Slope creep was noted downslope of the road. Trees indicated curvature and a slow rate of
shallow soil mantle creep. Visual estimates of tree age integrated with degree of curvature
suggest a slow rate of creep and with buffer setbacks this condition does not present a problem
for the proposed land use. The road itself appears to be well founded on basalt sub-grade
material.
Minor localized slope creep was noted in the upper slope above the gravel road. Individual trees
rooted in the shallow soil mantle(mostly less than 6 feet in depth and not appearing to exceed 10
feet in depth)demonstrated some minor degree of curvature in the trunk/stump area. The
contact between soil and bedrock is a slippage surface. Creep rates are extremely slow and at
most involve 10 feet vertically and horizontally along the slope crest.
3.3 SOILS
Soils are mapped in the Soil Survey of Mason County, USDA Soil Conservation Service(1960).
Mapped soils include the following descriptions from the Soil Survey:
• Shelton gravelly sandy loam: The granular surface and subsurface layers may extend to a
depth of 30 inches(+/-) before contacting the underlying indurated till layer. The
substratum is typically cemented and derived from glacial till. Infiltration is low and
surface runoff is high.
Site soils were sampled randomly on slope and hilltop areas.
Observed site soils generally matched those reported in the mapping work. However, some
variation was found within the colluvium on and below the sloped portion of the site. This soil
was dominated locally by weathered basalt materials.
4.0 GROUNDWATER
Inspection for indicators of groundwater discharge (springs or seeps)was performed on site,
within slope areas, and within the toe zone.
No evidence groundwater discharge was found within the slope.No indicators of groundwater
related earth instability were observed within the slope or adjoining toe or crest areas. Wetland
area near the toe of slope does not appear to be fed by groundwater from the slope area.
5.0 SURFACE WATER
Sheet flow runoff is high due to tight soils and sloped terrain. Sheet flow drains over the road
surface. Erosion from poorly controlled road drainage was noted. An improved road side ditch
drainage system is needed to control erosion.
The wetland does not appear to cause any slope instability concerns.
Septic drainfield and proposed structures will be placed outside of the wetland and buffer area.
All structures must be fitted with adequate under drainage to avoid excessive moisture within the
foundation area, under any slab,or within any crawl space.
A near surface water table elevation within the construction area may create foundation baring
capacity concerns. Careful attention should be given to subgrade baring capacity and moisture/
density relations for buildings.
5.1 IMPERVIOUS SURFACE DRAINAGE: BUILDINGS,ROADWAYS,OTHER
Existing impervious surface is limited to the gravel road. Proposed impervious surfaces include:
• Rooftop and paved walking areas;
• Parking area; and
• Driveway
Adequate drainage provisions will be needed to capture and route all stormwater away from
slopes, foundations,and septic areas.
5.2 SEPTIC AND IRRIGATION
No septic system existed on site at the time of field work. An on-site septic system is planned
with a drainfield located in the lower portion of the site adjoining and outside the wetland buffer.
Routinely, drainfield placement within 100 feet upslope of any slope crest is discouraged. The
proposed site is acceptable for slope stability.
No irrigation system is on the property. Buried irrigation systems are strongly discouraged within
200 feet of any slope crest. Undetected failing irrigation systems can cause slope damage.
6.0 EXISTING VEGETATION
Low elevation areas are dominated by wetland plants: emergent, shrub, and tree species. Forested
areas dominated the balance of the site.
Sloped and slope crest areas support mature forest/trees. These should not be harvested, except
for any hazard individual trees. The root system of a mature stand provides soil reinforcement.
7.0 SLOPE STABILITY EVALUATION AND ANALYSIS
7.1 EVALUATION
A slope that possesses a safety factor of 1.0 is on the verge of failing, whereas slopes with a
safety factor greater than 1.0 has some resistance to failure. Typically, a static safety factor of 1.5
and a seismic safety factor of 1.1 are considered the recommended minimum values for most
slopes where risk to structures or human safety are involved. Lower values may be evaluated in
circumstances where such risks are not involved.
In general, a slope stability analysis using analytical methods is used where conditions suggest
that the safety factors approach those described above.
Site conditions and the proposed landuse did not warrant the added expense to this landowner of a
slope stability analysis. The slope contains sufficient bedrock and sufficient history of visual
geomorphic stability to not warrant the added depth of analysis within the context of the proposed
landuse(timber harvest, land clearing for pasture, and perhaps livestock building/s).
This conclusion in made with the understanding that a slope crest setback/buffer
recommendation(no less than 35 feet)will be observed for all proposed landuse actions.
8.0 STANDARD DISCLOSURE STATEMENT REGARDING SLOPE STABILITY
All slopes retreat by natural and human processes and,within this context, slope stability is a
relative term. It is rarely economically feasible or achievable to completely arrest slope instability
and erosion. Instead, the endeavor becomes one of managing risk by decreasing the degree of
instability, slowing the rate of land retreat and,when appropriate, restoring lost material. Thus,
property owners have options and choices for improving stability conditions on slopes and for
limiting risks by building in safer locations. Choices are typically based on a balance between risk
and financial expense. Reduced risk typically comes at a greater financial cost. Within this
context, Agua Tierra is available to provide project designers additional analysis/design
assistance beyond that included within this report.
Recommendations for completing this project within generally accepted risks of slope instability
are offered below. Our conclusions are based upon conditions observed and discussed within this
report. Other conditions not encountered by this investigation may exist within the influence of
the proposed development, and could result in greater risks than described. Should subsurface
conditions appear to differ from those described in this report,this office should be contacted to
evaluate these conditions and revise the recommendations accordingly.
9.0 CONCLUSIONS
We offer the following conclusions related to proposed development activity for the site:
• New structure construction: Structures may be built on this property within the specified
constraints outlined within the recommendations section below. Anticipated items include a
home, possible related detached buildings(garage, well pump house, and perhaps a shop or
other out buildings);
• Access road/driveway construction/buried utilities placement: Construction of an access
road/driveway add no additional slope related constraints. Utility trenching should be
carefully backfilled and anti-seep collars of clay may be warranted to prevent the backfilled
trench from becoming a preferential flow path for subsurface water;
10.0 RECOMMENDATIONS AND GUIDELINES
Geotechnical recommendations are offered below. In some cases design work is involved.
Design work is not within the scope of this report.
Recommendations provided are of a general nature. Refinement and tailoring to specific site
design conditions will occur as plans evolve.
10.1 SLOPE STABILITY BUFFER AND SETBACKS
Mason County has a prescriptive buffer(setback)of 50 feet from landslide hazard areas(crest or
toe)for development activities. This distance is subject to modification(increases or conditional
decreases)based on results from a geologic evaluation and approval by the agency.
We recommend that structures for human occupancy be built with a buffer not less than 50 feet
from the crest of slope.
Timber harvest and other structures may be within 35 feet of slope crest.
10.2 SITE PREPARATION (and temporary erosion control)
Preparation of the project site will involve clearing, stripping,and subgrade compaction within
specific locations. The following recommendations are offered:
Temporary Construction Erosion Control: Before construction begins an appropriate erosion
control system should be installed.This system should collect and filter all surface run off
through either silt fencing or a series of properly placed and secured straw bales. We anticipate a
system of berms and drainage ditches will provide an adequate collection system. If silt fencing is
selected as the filter the fencing fabric should meet the requirements of WSDOT Standard
Specification 9-33.2. The silt fence should be buried so that sediment cannot pass beneath it. If
straw bails are used as the silt filter,the bales should be secured to the ground such that they will
not shift under the weight of any water retained. Regardless of the sediment filter selected, it
should be inspected and maintained during the time that the site soils are exposed,on a periodic
basis and after any major rainstorm event. Specifically, holes in the filter and areas where the
filter has shifted above ground surface should be repaired as soon as they are identified.
Because stripped surfaces and soil stockpiles are typically a source of runoff sediments,they
should be given particular attention. If earthwork occurs during wet weather, we recommend that
all stripped surfaces be covered with straw to reduce the runoff erosion. Similarly soil stockpiles
and cut slopes should be covered with plastic sheeting for erosion protection.
Clearing and Stripping_ Construction areas should be cleared and stripped of all grass, sod,
topsoil,trees, wood, concrete,construction debris, and fill.
Our explorations indicate that an average thickness of about 1/2 foot of topsoil is present on the
site, but slight variations in thickness may be encountered when excavation begins.
Filling: Any holes created by the stripping operation should be filled with structural fill, such as
"pit run" or"gravel borrow". Regardless of soil type, all fill should be placed and compacted to
sufficient density. No organic waste should be buried within foundation areas.
Temporary Cut Slopes: All temporary soil cuts associated with site regrading or excavations
should be adequately sloped back to prevent sloughing and collapse.
Undisturbed site sub-soils should hold a temporary cut face of 1 H:IV. However, flatter slopes
may be necessary if the actual soil conditions exposed vary from those identified.
Subgrade Compaction: We recommend that exposed subgrades for footings, floors, pavements,
and other structures be proof rolled or compacted to a dense condition. Any localized zones of
loose granular soils observed with a subgrade should be compacted to a density commensurate
with the surrounding soils.Any organic, soft, or pumping soils observed within a subgrade should
be over excavated and replaced with structural fill.
Wet-Weather Considerations: Site soils appear to have poor infiltration rates.
Project specifications should include provisions for using imported, clean, granular fill in case the
on-site soils become too wet and filling must proceed during wet weather. For general structural
fill purposes, we recommend using a well-graded sand and gravel, such as"Ballast"or"Gravel
Borrow"per WSDOT Standard Specifications 9-03.9(1) and 9-03.14, respectively. In addition,
undisturbed native soils that are exposed to excessive moisture water for an extended period of
time may become unsuitable for use as structural support. Hence, we recommend scheduling
construction for periods of dry weather.
Quarry spalls should be used to protect high traffic areas at the discretion of the builder.
Typically,coarse rock, ranging from 3 to 6 inches in diameter(WSDOT Section 9.33,Quarry
Spalls) is placed under high traffic areas to prevent rutting and soil tracking by construction
equipment.
10.3 SLOPE STABILITY MITIGATION
Drainage for the active access road is necessary. A good ditch system with a shoulder ditch along
the backslope toe is recommended. Drainage discharge should be safely routed with erosion
control provisions. If a culvert is to be placed under the road, placement should avoid slope
locations if possible. Culvert discharge must be tightlined or channeled to a safe outlet point at
the toe of the slope.
10.4 FOUNDATION PAD AND FOUNDATION DRAINAGE
A foundation pad design must meet Universal Building Code(UBC) standards for placement on
dense, unyielding material of sufficient density. This condition may be found by excavating to
native material of sufficient strength or by use of engineered materials compacted to meet
standards.
It appears that on site native material, if not disturbed below excavation and footing depth, may
meet this requirement. Avoid disturbing site soils below footing depth. However, near surface
water table conditions may compromise soil baring capacity for the proposed home foundation.
Inspection and testing may be required upon test excavation. The foundation contractor should
be sure that soil and water table conditions are acceptable.
Drainage of the foundation pad and/or footings should have a perimeter or footing drain system to
insure the structure maintains a dry crawlspace(where included)and sufficient drainage
surrounding solid careful attention should be given to details of under drainage and moisture
barrier for the foundation walls and footings.
10.5 DRAINAGE
A drainage plan should be developed before development starts to minimize the risk of future
moisture problems. We offer the following recommendations for long term and construction
purposes.
10.5.1 SUBSURFACE DRAINAGE
Perimeter/Foundation drain should encircle the structure to collect and bypass groundwater. All
foundation and site underdrains should be installed prior to foundation and utility construction. A
typical detail drawing is offered for consideration and use.
Surface drainage(downspouts, paved areas,catch basins, etc.)should NOT be combined with the
subsurface drainage system.
Every effort should be made to avoid wet weather excavation.
10.5.2 SURFACE DRAINAGE
We recommend that the site be provided with permanent drainage systems to minimize the risk of
future instability and moisture problems. We offer the following recommendations and comments
for long term drainage design and short term construction purposes.
Overall Collection System Network
All site surface drainage flowing toward the slope should be collected, routed to the base of the
slope,and discharged as described in following sections. Tightline drain/s should be installed to
carry all water intercepted by other devices to the base of the slope. System monitoring should be
performed twice annually, and following any larger storm events(wind, ice, or runoff) on a
disciplined regular basis that fits the owner's schedule. We recommend scheduling the routine
inspections in the spring and fall to coincide with daylight savings time shifts for ease of tracking.
System should be inspected for damage and leaks.
Energy Dissipation for Discharged Water
All stormwater discharge points should be equipped with energy dissipation treatments at their
outlets to control erosion. Hand placed quarry spalls(angular rock 3 to 6 inches in diameter)
should be fit into a stable apron/fan like configuration within the topography of the receiving
swale,ditch, or toe of slope site. Enough material sufficient to protect the site from erosion
should be placed at each site. Additional provisions should be considered when use of quarry
spalls alone is inadequate. Energy dissipation pipe fittings and perforated sections are effective
and long term vegetation plantings should be installed.
Grading and Capping: Final site grading should slope downward away from the building and very
steep slope so that runoff water will flow by gravity to suitable collection points, rather than
ponding near the building.
Perimeter Drains: We recommend that the building foundations be encircled with a perimeter
drain system(sometimes called footing drains or foundation underdrains)to collect seepage
water. This drain should consist of a 4-inch-diameter perforated pipe within an envelope of pea
gravel or washed rock, extending at least 6 inches on all sides of the pipe, and the gravel envelope
should be wrapped with filter fabric to reduce the migration of fines from the surrounding
soils. Ideally, the drain invert would be installed no more than 4 inches above or below the base
of the perimeter footings.
Runoff Water: Roof-runoff and surface-runoff water should not discharge into the perimeter
drain system. In addition runoff water should not be infiltrated within 200 feet upslope of
landslide hazard areas or any distance upgradient if it appears likely to create a `point source'
concentrated flow path that will reduce slope stability within a landslide hazard area. Runoff
water should discharge into tightline pipes and be routed away from structures to a storm drain or
other appropriate location.
Drainage Swales: Single-family residence projects can use shallow, gently sloped, vegetated
drainage swales to convey stormwater away from erosion prone sites. Dense, clay-rich soil is well
suited for swales to convey water without allowing infiltration and surcharge to down gradient
sensitive slopes and soils. Swales dimensions are broad, and shallow, with gentle side slopes.
Swale surface can be lawn, landscaped with ground cover,or lined with stone. Swale dimensions
vary with flow volume requirements. Swale slopes should range between 0.5 and 2 percent.
Drainages steeper than 2 percent should adhere to Drainage Ditch guidance.
Drainage Ditches: Single family residence projects can use shallow drainage ditches can be used
in the same soil types described under the heading of Drainage Swales. Ditches with slopes
ranging from 2 to 4 percent require placement of quarry spall check dams periodically along their
length, and keyed into the bed and banks(1 foot minimum—all directions)and placed with a
maximum spacing of 50 lineal feet between dams and a maximum of 2 feet of elevation change
between adjoining dam crests. Slopes greater than 4 percent should be avoided and flow(once
filtered from debris and sediment with a catch basin and/or settling basin)placed within a
tightline drainage pipe and safely routed to a non-erosive discharge site. Ditches must be
maintained annually to keep them free of obstructions(debris, soil, vegetation, etc.).
Discharge Sites
Candidate discharge locations for water captured/ intercepted by drainage systems on site were
identified. The final designer/owner must confirm acceptability of all system components. If
other land ownership is involved,appropriate approval must be obtained.
Captured and piped flow can be routed to a swale within the wetland buffer for infiltration.
Catch Basins: Any catch basins used on site should be inspected several times every wet season.
We recommend on or about the first day of every odd numbered month for ease of owner
tracking. Minimum inspection criteria should include: sump cleaning and sealing of any leaks.
10.6 SEPTIC DRAINFIELDS AND IRRIGATION SYSTEMS
Generally, septic drainfields should be located more than 100 feet up-gradient of any slope crest.
Permanent Irrigation systems within 200 feet of the any site slopes exceeding 15 percent should
be avoided. Such systems present an unnecessary risk to slope stability. Irrigation systems require
regular maintenance, inspection,and are subject to failure without detection. Temporary above
ground irrigation systems may be warranted to establish new site vegetation on exposed soils.
Irrigation systems should be removed following the plant establishment(2-3 growing seasons).
10.7 GRADING AND LONGTERM EROSION CONTROL
General guidelines are provided with this report at this initial planning level of design
development. Detailed plans are best provided when construction plans are finalized and prior to
permit submittal.
Site soils are moderately resistant to erosion if protected from concentrated runoff. The soils are
moisture sensitive, and become rutted if traversed by equipment when moisture is too high.
Earthwork should be limited to conditions which are neither excessively dry nor wet so that the
soil can be compacted to a stable density. Exposed soils outside the structure footprint areas
should be covered immediately with straw after excavation and as preparation for revegetation. A
blanket of mulch material,compost, or topsoil mix 3-4 inches thick should be applied over
exposed till or gravel and sand-dominated soil lacking organic matter.
Soils exposed by construction should be replanted and/or treated for erosion control no later than
October 1, prior to the onset of the rainy season.
Site grading should direct runoff away from structures, and avoid any concentration of flow near
structures to prevent high moisture concentrations in these areas. Uncontrolled,concentrated
flow off impervious ground is more likely to adversely affect soil conditions below.
10.8 VEGETATION MANAGEMENT RECOMMENDATIONS
Avoidance Zones: Only shallow rooted(less than 18 inches) species with thin fibrous root
systems(equivalent to grass roots)should be planted within 10 feet of underground drainage/
septic related features(drainfields,perimeter drains, underdrains,and infiltration systems).
Native Species Selection:Native species are adapted to the native soil types and natural moisture
conditions on the site. Irrigation requirements are typically limited to the plant establishment
period(2-3 growing seasons). Avoid installation of any permanent irrigation system anywhere on
site.
Preferential Selection of Shrub Species: Shrub species(generally less than 20 feet tall)that form
dense root networks and provide year round vegetative cover(evergreen)are recommended
preferentially over tree species on any slope areas with gradients steeper than 15 percent. Taller
tree species catch considerable wind. During wet winter periods when soils are wettest, "wind
throw" forces delivered to the treetops can increase soil stress and slope instability risks.
Vegetation Clearing/Replanting_The following guidance is offered for clearing, pruning, or
removal of specific plants and/or vegetation zones not addressed elsewhere in this report.
• Construction activity no entry zones. Do not disturb zones should be specifically
noted on the final design drawings and these zones should be clearly marked in the
field prior to construction (flagging ribbon or, or orange plastic fencing);
• Hazard trees removal: At the discretion of the owner, trees within 10 feet of the
proposed structure may be removed for future structure access and to reduce risk
following partial cutting of roots during excavation;
• Vegetation clearing areas. Such areas should be limited to footprint of proposed
structures, excavation areas, staging areas, roads, and should avoid extending more
than 10 feet beyond the perimeter of structures;
• Method of vegetation removal: Except where organic matter is removed for purposes
of foundation pad specifications, and other engineering requirements, any vegetation
selectively approved for removal within buffer or slope areas should retain all
organic matter on the land surface and retain the stump in place for root-soil
reinforcement. Retained stumps should be kept live and supported to resprout(for
species capable of such)to provide sustained root strength;
• Vegetation removal for the, purpose of view clearing and maintenance shall be
performed by a Certified Arborist. Topping of conifers(fatal) should be avoided.
Crown thinning shall be used as a view clearing and wind throw reduction method
for conifer species; and
• Any area cleared of vegetation to support construction activities should be
revegetated as soon as possible and no more than two weeks following completion of
construction segments impacting said areas. Interim erosion control measures should
be implemented if soil is to remain exposed for extended periods prior to completion
of construction tasks impacting such locations.
10.9 SLOPE STABILITY MONITORING (UNIVERSAL RECOMMENDATION)
We recommend that most slope owners institute a slope stability-monitoring program. This
allows changes to be quantified and documented, Other than relying on human memory and
perception. Monitoring includes a baseline survey of slope conditions and if appropriate, survey
measurements of slope geometry at known fixed points. Tell tales can also be placed on the slope
to measure displacements directly.
Monitoring should be implemented upon completion of construction to detect any developing
problems early enough to make site modifications, if needed. Included in the monitoring checks
would be systematic inspections of the slope geometry mentioned above,vegetation conditions,
structural integrity of built objects on site, and deformations of any paved surfaces, etc.
11.0 ADDITIONAL SERVICES/NEXT STEPS
Design work may be needed as noted:
• Drainage, stormwater,and erosion control plan;
• Possible foundation subgrade reinforcement;
• Permitting.
12.0 REFERENCES
References reviewed or included in conjunction with this report included:
• Molennar, Dee,and Noble,J.B, 1970. Geology and Related Ground Water Resources,
Southeastern Mason County, WA; (Washington Department of Water Resources Water
Supply Bulletin 29)
• Schasse, Henry W., Robert L. Logan, Michael Polenz, and Timothy J. Walsh, 2003;
Geologic Map of the Shelton 7.5-minute Quadrangle, Mason and Thurston Counties,
WA. (Washington Department of Natural Resources, Division of Geology and Earth
Resources, OFR 2003-04).
• USDA, 1960. United States Dept. of Agriculture, Soil Conservation Service, Soil Survey
of Mason County, Washington.
• Smith, Maekey,and Car-s@R, R.j., 19-:77. Rel-ative Slope Stability of the Seuihem Read
• Washington State Department of Transportation, Standard Specifications, current edition.
Ritter, Dale F., 1982
STANDARD DISCLOSURE STATEMENT (0605)
This report is based on a limited inspection of existing site conditions. Limited and site specific
measurements and subsurface evaluations were performed. The recommendations provided here were
prepared at a general level, as judged appropriate to the current level of project design and within a
budget commensurate to the typical residential home owner. More detailed design work may be
recommended. Agua Tierra should be involved in design and construction phases,while this document is
being used as a reference. No warranty is made by Agua Tierra concerning conformity of the
construction to the conclusions and recommendations of this report unless the plans are reviewed and the
construction work inspected by a representative of Agua Tierra.
Within the limitations of the scope, schedule and budget, our services have been executed in accordance
with generally accepted professional practices. Conditions may change at the site due to human
influences, floods, groundwater regime changes,or other factors.
The content of this report is client, project,and site specific. Time is a consideration in the validity of this
report. Site conditions will change over time from human or natural influences. The content of this report
is not warranted beyond one year or in the event of heavy storms or earthquake. This warrantee is in lieu
of all others, either expressed or implied.
Thank you for this opportunity to contribute to your project. If we may be of further assistance, please do
not hesitate to call.
Sincerely,
Charles Coddin on, P.E.;�Sc,C.E. ris ' rProject
,Sc;C.E.
t S
Civil Engineer Hydrolo Manager
a.
SjC:VA:•_.Y:
EXPIRES: 7-9- C 1
ATTACHMENTS
• MAPS
• FOOTING DRAIN/PERIMETER DRAIN TYPICAL DETAIL
AGUA TIERRA LAND AND WATER SERVICES, INC.
506 EDISON STREET,SE, SUITE 100
'GU' ' OLYMPIA,WA 98501
TEL.(360)754-3755
LAN1 &WATERSERVICES', FAX(360)754-3431
t�AnoavEST.
�Bushcrgo- o�ooft
x
a
W Rellet Rd W Reilar Rd W J"Im Rd
®2006 MapQuest,Inc;m 2006 Tole Atlas
PROJECT AREA = 0
MAP Street Map
SOURCE www.mapquest.com
. AGUA TIERRA LAND AND WATER SERVICES, INC.
506 EDISON STREET,SE,SUITE 100
AGUA ' OLYMPIA,WA 98501
LAND&WATER SERVICES,INC. TEL.(360)754-3755
FAX(360)754-3431
dD
2s__
s J 1....
PROJECT AREA =
MAP Vicinity Map
SOURCE www.topozone.com
, r
AGUA TIERRA LAND AND WATER SERVICES, INC.
506 EDISON STREET,SE, SUITE 100
AGU ' ' OLYMPIA,WA 98501
TEL.(360)754-3755
LAND&WATER SERVICES,INC. FAX(360)754-3431
2
2190040 f!
rr. 4
LZGCGC 2200coo s r ,0:1 44/S'
2190030
rr. 3 rr Z
Z19ccoo 2 COC20
7500050 7!00070
150080 7500090
� S
rr T Tr 8 Tr. 9
s A a0 Ifi
_- - - - -- si or R004 - --
150+0060 . i eK=70 �00030
Tr. 6t3 I trr. T
I_9'.x'4Bc, 2'IOC
2dCCCGO
rr 6
MAP: Parcel Map
SOURCE: Mason County Assessors Office
AGUA TIERRA LAND AND WATER SERVICES, INC.
506 EDISON STREET, SE,SUITE 100
OLYMPIA,WA 98501
' TEL. (360)754-3755
&WATER SERVICES,INC. FAX(360)754-3431 41
r lot lb
YF-
Z' ,IM
f
Is It V Vol
*a
PROJECT AREA =
MAP Aerial Photograph
SOURCE www.terraserver.com
AGUA TIERRA LAND AND WATER SERVICES, INC.
506 EDISON STREET, SE, SUITE 100
AQUA R R + OLYMPIA,WA 98501
TEL. (360)754-3755
LAND& FAX(360)754-3431
fto
rk .' _.,aas..• .•a` • J� °tp:-. s4
e� � k ,Y", :�. •,j �• ij r " r}Or.
r
•`r
Map Unit Symbol Map Unit Name
Bb Belfast silt loam: 0 to 3 percent slopes
Sd Shelton gravelly loam: 5 to 15 percent slopes
PROJECT AREA = 0
MAP Soil Map
i
SOURCE http://websoilsurveV.nres.usda.gov/app/
AGUA TIERRA LAND AND WATER SERVICES, INC.
k 506 EDISON STREET,SE,SUITE 100
OLYMPIA,WA 98501
' SERVICES, TEL.(360)754-3755
FAX(360)754-3431
Evc
i
� 5 G
JJ 1
Q a
14
r Qa)
Map Unit Symbol Map Unit Name
Qa Alluvium
Eve Lower to middle Eocene Crescent Formation
PROJECT AREA = 0
MAP Geologic Map
SOURCE http://www.dnr.wa.gov/geology/pubs/pubs ol.htm
a ' . W A T F. R W E L L R E P 0 R 'I' fit.at: ;'.I:-•: N, W012818
l;nigt:• N••�'. �t ACN325
STATE OF WASHINGTON W.a.•: 1:id.I I' r..' N•:.
= :......:-.=.........
:..-_...... .. .,..•
O it• CWNb:: NAM- ZIMMERMAN, CHARLES Address 2221 =AST SAY DSM OLYIQZA, Xh 90506-
O. _•'-••._. - •-__ -=___-____--_------._....�_.___...._... �i ...- �. .
! ...:I AT f l',K 'd' WE..i ••••i l.!.• MASON SE t enr 04
.. 2s lox T. I sN ''•
t.•.. �I'EE:!•:f ft:'.'ia:c;:: . .. '.•!.?!,i, {,q 11••.r::r•ft •r.ldr'::;t:: W 91 JOSLIN, SHELTON
.......................... .
• - r".i'iYiriiilr I!"r:. DOMESTIC I i10) WELL TM
t
t nw;r: Nt:nb r of wral I Formation: i;esrribn by r•olnr, ,9.:r. rer, ^ir.• r
.1. .TYPU : t' W: r'
(A I r n•.,c,- rtan onri I and structure, and show Ihickn••:,• :1 tI n:'.t:•,o- nuu r!:
K,-rhtni: ROTARY and nature ul the nk�!'rrial nI r•o':I rt::r1 m:1 1'•rt,;-I
NEWWELL ..,___... _______-. .___________________:.( at least one vnrry 1 my ..-r...Ll.• ,.1 ...I LrL ..I.
- ------ .
r �1u4NS10N::: Diameter at Weil 6 inches (_-_____-___-
0 I•ti•N
Lrtil••d 124 It, f>,•pch nC ccrllplet.rd well 124 ft. I MATERIAL TOP SOIL ' 0 i 1
-__... .._•..-,-. - - ---____________.._=="- ---...I
O - •___•�__.. --- I GRAVEL COURSE SAND YLW CLAY HINDER 1 s 30
In; :'<)NS'JRUC'TT-':C I:1•:rAfrS: j 10 10
),:.!it t11,•:1: 6 " pia. from ♦2 ft. to 100.8 ft. I FRACTURED HASLT ORAVEZ YLW CLAY HINDER
%TELDED CASING Din from ft. to ft. I GRAVEL FRACTURED HASLT YLW CLAY HINDER 30 61
E " hia. from ft. to ft. I FRACTURED IASLT COURSE SAND GRAVEL a WATER 83 124
f.. •-------I
C N
Tyr,
0• .. •:1
n!%� r,t :•I..:.,:.i•,I:•. :n. I:y in. I
5.+ 1:.•:!,.:.i: .. u. trcr; Lt. to
L p.•rtcrIl1•�a:: :r�,lp ft. to ft.
0 ----.. .._---- - ---------------nnn NO
�f.0141:;tr l.:l r•::'', V.Irr• I
TYF'• model No. I !
I
hi•ur., •a•: ::.zr• from ft. to ft. ..
I t;.lm. :.!••t 170 from ft. t0 I '
Ito --------ft----k
.�1'.1V. t:•r•I••••;. NO size of gt'•wrl
------- -------
�.d :I:t•f,. ,:.1 YES To whet depth? 20 ft
� p•,i .u,i: •.a un'.rsable. wHte:1•': NO
I1r•pth of strata ft.
"it I
Type. H.P.
Wxj,Ex r.f:VF.Ll✓: - .=---Ixlnd-AUrfdt:e elevation=__'•-______�
z tlx,vc bean sea level ... ft. I
H r;1..ICi•• I••r,,.l 43 tr , below top of well Date 10/16/96
T,'r.••+'-:ro 1`r••s:+1,I•,• Ins. per square 111r.11 Date I
Q AI-1 ^-:.nl •w..,c •I .':.1:1•...I lrci Ly I 10/15/96 ,, I 1 10/1F/9F
'Nock sT nt t:•:R ... ''r-:
'fa£:7::: 1•rr,�i,•w:I i.� aTwItirtt� war-rr leveiois lowered-below ifELL CONSTRUCTOR �^f:RTIF'll.'ATT!7N:
p), WET,:.
O .r.r ,: I •v••I. I T CoI1.Frrnlac•d and/or n:•r•,pt • :: .'ru:�i•:i II.. •«.
W struction Of 4-his well, nud :1' n:np +.tn.•1 I
O a:? d I;nvq, 1 •:•1 ,:L,<i, NO 1: y+:s, by whom? .
11..I.t: :,..':ri' 'ir•1: ft. dt•awdown after hrs. Wae
I hingt utt wr•li r..rn,t.tu.•ti„1. rl.,cl4nri�: FL,r,.: : ,t:. .
and I.lu• information T,:{>•,i:. .I .II": n• t l:w 1
W knuwlo:ltle and
0 I
J.d ['inn.• ii,Il,•: I'.i^.•• Water Level Ti:nc• Water Level I NAME AACADIA DRILLING INC. '
I U',•rs„n, 17rm, c,i. cc rE.,rht 1•:n: t'i'yt,• r F., -.
ADDRES:; SE 170 jV�ERfVARX RD
h lr.Wdowr, atrrr )Ira. I (SIGNET',] � I••' K'• 1149
a Air 1,:1 25 .1.'•'r t ^! :'I••nt set at 119 ft. for 1 lire.I
,:1.. •u: 11••w 't.1i.1:1. Date Cont raCtot'r: .
Q .,.E,• I ,., ..t W:,.. ,t t•hemic.el asrl kysis.inade?=310p-I-R'9iatrat i:)n N-,_ AR=ADD1096)(1 ...
I—
-� AGUA TIERRA LAND AND WATER SERVICES, INC.
OLYMPIA, WASHINGTON
FOOTING / ROOF DRAIN SECTION
(NTS)
ROOF DRAIN FINISH GRADE ® 2% (MIN)
TIGHTLINE FOR A DISTANCE OF 8FT.
4" DIA PVC SCH2O (MIN),GLUE ALL JOINTS (MIN) FROM STRUCTURE.
1% (t) SLOPE (SEE NOTE 1)
E
'A
._STEM °WALL t2"
(TYP) (MIN
4 )
6'
° (MIN) 1-1/2" TO
2-1/2"
WASHED DRAIN
° ROCK
B
a °
FOOTING `
(TYP)
u
1.5 MIN.
1.0 c
_.-D
12"MIN
GEOTEXTILE FOR DRAINAGE
SHALL MEET WSDOT STANDARD
A= 3" TO 6" SPECIFICATION SECTION 9-33.2,
MATERIAL SHALL BE SPECIFIED AS: MODERATE SURVIVABILITY CLASS B
(STRIKE OUT OPTIONS NOT USED) FOOTING DRAIN CONFORMING TO AASHTO M288-96
(1) TOPSOIL + GRASS SEED PPERp AR
(2) GRAVEL PVC SCH 40 (REC)
(3) GRAVEL W/STEPING STONES
(4) CRUSHED OYSTER SHELL (1" LAYER) OVER GRAVEL
B= GRAVEL / DRAIN ROCK LAYER
APPROXIMATE THICKNESS ABOVE PIPE INVERT:
C= DRAIN PIPE DIAMETER:
4" OR 6". (MUST BE SPECIFIED)
D= GRAVEL / DRAIN ROCK LAYER
THICKNESS BELOW PIPE: 2" TO 4".
E= TRENCH 'MOTH: (VARIES WITH EXCAVATION METHOD 12" TO 24" TYP.)
NOTES:
1) SURFACE CAPPING. IF SPECIFIED, INSTALL SURFACE CAPPING
MATERIAL WITHIN 8FT. (MIN), CAPPING SHALL BE LOW
PERMEABILITY SOIL (SILTY), 6 INCHES THICK, AND COMPACTED.
10
AGUA TIERRA FIGURE:
LAND AND WATER SERVICES,INC.
506 EDISON STREET SE,SUITE 100
OLYMPIA.WA.9a501 FOOTING/ROOF DRAIN(SECTION-DETAIL)
TEL(3W)754-3755
FAX.(3so)7s4-3431 (ROOF DRAIN BUILDING SIDE OF TRENCH) J
W WW AGUATIERRA.NET
C'.DETAIL DRAWINGSIDra+n d Irrigate Dow"(Curtain orans,pipe outlets)JootYigtod-dralrt 12-0aM3 Avg,421?00611:44:42 AM
r
FINDINGS OF FACT
FPA Case# 2006-00015
APPLICANT: James Lawrence
APPLICATION DATE: August 5, 2005
Mason County has reviewed the above referenced application for Class IV General Forest
Practices and finds it in conformance with all applicable County land use regulations in
effect at the time of application.
FINDINGS
The proposed FPA is compliant with the following conditions:
The proponent has paid the prescribed fees.
The proponent has filed a complete, signed application.
A map has been received that complies with the requirements of 11.05.120:
(I) Harvest boundaries and tree retention areas.
(II) The approximate location of any structures.
(III) The location of all existing and proposed streets, right-of-ways, easements, skid
roads, haul roads, and landings within the proposal.
(IV) The location of future land development including stormwater management
facilities and vegetation to be retained for site landscaping, open space, wildlife
habitat, screening, and/or buffers.
(V) Site topography at contour intervals of 40 feet.
(VI) Critical areas and critical area buffers regulated pursuant to the Critical Areas
Ordinance.
(VII) Drainage ways and culverts.
(VIII) Site area targeted for further harvest including proposed timing.
(IX) North arrow and scale shall be shown on all site plans. The scale shall be no
smaller than one inch to 200 feet.
That this FPA is in conformance with the following Mason County ordinances:
11.05
That the proposed FPA involves 10 acres.
That the notifications required by 11.05.060 have been made if applicable.
Note: Not applicable in this case.
1
Mason County Resource Ordinance
_X_That at the issuance of this permit will not result in a violation of the Mason
County Resource Lands and Critical Areas Ordinance. The site was inspected by
Michael MacSems of the Mason County Planning Department who determined
that any critical area buffer and/or steep slope issues have been resolved.
A wetlands study and a geo-technical report were approved by Mason County.
Geo-Technical Report/Assessment Review
A Geo-Technical _ Assessment_X_Report(check one)was written by
Christian Fromuth approved by John Sliva of Mason County Public Works on
July 28, 2006.
Washington State Department of Transportation
X A DOT Access Permit is not required for this proposal.
A DOT Access Permit is required for this proposal.
Date Approved by DOT: N/A
Shoreline Master Program
That, if applicable, all activity under this application are in conformance with the
Mason County Shoreline Master Program and has a shore line designation of
N/A.
State Environmental Policy Act
This application for FPA#2005-00015:
X_Has been reviewed for SEPA compliance under case#: SEP 2005-00119.
_Is SEPA exempt.
_DNS
X MDNS
CONCLUSION
In conclusion,this application for Class IV General Forest Practices is consistent with the
above criteria and that the public uses and Mason County has fulfilled its statutory
obligations.
RECOMMENDATIONS
I,being the Manager of the Mason County Planning Department, hereby attest to and
certify that appropriate provisions have been made for this Class IV General Forest
2
Practices Application and hereby recommend approval. In addition these facts evidenced
by the contents of the file for this Forest Practice Application.
Signed,
a' t�t yj Zw 91164(s
Robert Fink, Planning Manager Date
0
Michael MacSems, Subdivision Planner Date
3
FOREST PRACTICE BASE MAP
TOWNSHIP 20 NORTH , RANGE 05 WEST ( W . M . ) SECTION 25
APPLICATION
11 W
EH
S_�/JifJy to
/ O
O '
o z
o �
o �
/
27 4 ' 26
ED
O
o
� l
2 \ 26
I \
I /
I �
1 /
1
°o I
/ � o
25 24 / 259
/ I
SCALE
0 1000 2000 3000 4000 5000 6000
FEET 1 Mile (5m e)
MAP DATE: February 2t 1997
CONTOUR INTERVAL : 40 Feet LEGEND : See Instructions
NAD 27 DISCLAIMER : See Legend
Water/Wetlands including their location and class may be incorrectly displayed or not shown
on the Base Map. Applicants are responsible for verification and correction.
FILTER FABRIC MATERIAL W"WIDE ROLLS
USE STAPLES OR WIRE RING TO ATTACH G e o t e c h n i c al
FABRIC TO HARE
27(77(14 GAUOE WIRE
FABRIC OR EQUIVALENT
Testing
�! 327.72' i 64r AQ T
7C VAX Laboratory
1
2X4
BET ER Op POSTS,STANDARD OR BURY BOTTOM OF FILTER
I BETTER OR EQUAL ALTERNATE. MATERIAL IN 8'X17 TRENCH
i 1
� STEEL FENCE POSTS
i 1
% 1
/ I
I
SILT FILTER FABRIC r
2X7%14 GAIgE WIRE
FENCE FABRIC OR EQUIVALENT ?
GROUND SURFACE
DETAILS ea
WASHED
GRAVEL BACKFILL IN TRENCH 17
AND ON BOTH SIDES OF FILTER
FENCE FABRIC ON THE SURFACE 8.
/ S POSTS Geotechnical Services
FILTER FABRIC FENCENOTES: QA/QC Services
AAA 1.FILTER FABRIC SHALL BE PURCHASED IN A CONTINUOUS ROLL CUT TO
THE LENGTH OF THE BARRIER TO AVOID USE OF JOINTS.WHEN JOINTS Testing Services
ARE NECESSARY,FILTER CLOTH SHALL BE SPLICED TOGETHER ONLY AT
A SUPPORT POST VATH A MINIMUM 6-INCH OVERLAP AND SECURELY
FASTENED AT BOTH ENDS TO THE POST.
A
2.POSTS SHALL BE SPACED A MAXIMUM OF 6 FEET APART AND DRIVEN
II / SECURELY INTO THE GROUND(MINIMUM OF 30 INCHES).
n--- 3.A TRENCH SHALL BE EXCAVATED APPROXIMATELY B INCHES WIDE AND IY 10011 Blomberg St.SW
INCS DEEP ALONG THE LINE OF POSTS AND UPSLOPE FROM T BARRIER.
l l E Olympia,WA 98512
4.WHEN STANDARD STRENGTH FILTER FABRIC IS USED,A WIRE MESH
SUP PORT FENCE SHALL BE FASTENED SECURELY TO THE UPSLOPE SIDE Phone:(360)754-4612
OF THE POSTS HEAVYOUTY WIRE STAPLES1 LEAST i INCH
LONG.TIE AIIRESSING OR HOG RINGS.THE WIRESHALLAEXTEIDINTOTE Fax:(360)754-4848
4 J TRENCH A MINIMUM OF 41NCHES AND SHALL NOT EXTEND MORE THAN 38
INCHES ABOVE THE ORIGINAL GROUND SURFACE.
5.THE STANDARD STRENGTH FILTER FABRIC SHALL BE STAPLED OR WIRED Date: 06/07/2007
I J TO THE FENCE AND 201NCES OF FABRIC SHALL BE EXTENDED
1 INTO TE H.TRENC THE FABRIC SHALL NOT EXTEND MORE THAN 36
L0 �/ j INCHESABOVETHEORIGINALGROUNDSURFACE.FILTER FABRIC SHALL Designed by: LL
1 (0 _ O I NOT BE STAPLED TO THE EXISTING TREES. Drawn by: LL
6.WHEN EXTRA-STRENGTH FILTER FABRIC AND CLOSER POST SPACING IS Checked by: LL
USED,THE WIRE MESH SUPPORT FENCE MAP BE ELIMINATED,IN SUCH
A CASE,THEFILTER FABRIC IS STAPLED OR WIRED DIRECTLY TO THEDwg#:06-07-07-061
PDST9 OTHER ALL OiR PROVISIONS OR ABOVE NOTES APPLYING.
7.FILTER FABRIC FENCES SHALL NOT BE REMOVED BEFORE THE UPSLOPE
AREA HAS BEEN PERMANENTLY STABILIZED.
8.FILTER FABRIC FENCES SHALL BE INSPECTED IMMEDIATELY AFTER EACH
RAINFALL AND AT LEAST DAILY DURING PROLONGED RAINFALL.ANY
L REQUIRED REPAIRS SHALL BE MADE IMMEDIATELY.
I
GENERAL EROSION CONTROL NOTES:
✓✓ ` `AW` 1. EROSION CONTROL MEASURES SHALL BE IN PLACE PRIOR TO THE
i POTENT] L O OJECT ENGIN
SHALL INSPE TCAND AP ROIVE THE INSTALLATION OF EER AND THE COUNTY
INFILTRA ION I EROSION CONTROL MEASURES PRIOR TO BEGINNING CONSTRUCTION.
2.EROSION CONTROL MEASURES ARE NOT LIMITED TO THE ITEMS
.\` J LOCATIO Q ; ON THIS PLAN.THE CONTRACTOR IS RESPONSIBLE FOR THE
_ INSTALLATION AND MAINTAINANCE OF ALL EROSION CONTROL MEASURES.
NO SILTATION OF EXISTING OR PROPOSED DRAINAGE FACILITIES
SHALL BE ALLOWED.CARE SHALL BE TAKEN TO PREVENT MIGRATION PROJECT NAME:
_ //��RR w' OF SILTS TO OFF SITE PROPERTIES.
`- -4BO //H 'r 3.THE CONTRACTOR SHALL MAKE DAILY SURVEILLANCE OF ALL EROSION LAWRENCE SITE
OUTCROP Ago OUTCROP 1i CONTROL MEASURES AND MAXE NE
CESSARY 100 RELLER ROAD
TO THE EROSION CONTROL MEASURES.THE CONTRACTOR SHALL PROVIDE
__ ---- /;' ADDITIONALEROS ION CONTROL MEASURES ASDETERMINEDNECESSARY SHELTON,WASHINGTON
------------------ - ----'--'---- BY THE COUNTY
INSPECTOR AND/OR THE PROJECT ENGINEER.FAILURE
TO COMPLY WITH ALL LOCAL AND STATE EROSION CONTROL
OUTCROP ui REQUIREMENTS MAY RESULT IN CIVIL PENALTIES BEING LEVIED
OUTCROP OUTCROP_ - \OUTCROP AGANSTTHE CONTRACTORAND(OR PROJECT OWNER
" DU ING THE MT SEASON( . PARCEL 52O2575000SO
-' DISTURBED OILS
----- - --�-/- -ZQ%�/ 4 SHAL BE STABILIZED WITMNOVEMBER 48HOURS AOFTER TOPMARCH) LOF WORK EROSION
WCONTROL MEASURES SHALL INCLUDE,BUT HOT BE LIMITED TO, Revisions:
COVERING THE EFFECTE D AREA INCLUDING SPOIL PILES WITH (�.1 /� 7
OUTCROP 'A PLASTIC SHEETING,STRAW MATTING,JUTE MATTING.STRAW MULCH, OJ'I��LOOI
-Mn'CROP ROPO D I`W`WW OUTCROP OR WOOD CHIPS.SEEDING OF THE DISTURBED AREAS SHALL TAKE
NORTH PUCE AS WEATHER PERMITS
SCALE 1"=80' OUTCROP 5.ALL SEEDED OR SODDED AREAS SHALL BE CHECKED REGULARLY
C.I.-10' Ul L D/N P R�f�O S E D TO MAKE SURE VEGETATIVE COVERAGE IS COMLETE.AREAS SHALL BE
REPAIRED,RESEEDED,AND FERTILIZED AS REQUIRED.
DATUM ASSUMED W LIi
I C/� 1 6 L OFFSITE WILL NOT BE R SHALL ALLOWED.
REMOV D B a THE END
L IS
THIS IS NOT A SURVEY OUTCROP LOCATION TRACKED ONTO A COUNTY STREET,'O TCROP OF THAT WORKING DAY.ANY FURTHER TRACKING OF MUD WILL THEN
' R
Q BE PREVENTED BY SWEEPING OR WASHING OF THE VEHICLES TIRES
BEFORE DRIVING ON A COUNTY STREET,
so ao Bo a0 o
II 7.NO MORE THAN 5W LF OF TRENCH ON A DOWNSLOPE OF MORE THAN 5
tI / 1 PERCENT SHALL BE OPENED AT ONE TIME.
NOTE TO REVIEWER: Q j/ O 8.EXCAVATED MATERIAL SHALL BE PLACED ON THE UPHILL SIDE OF TRENCHES.
OUTCROPS OF BASALT WERE OBSERVED R E L L E R ROA
WHERE LABELED.THE REMAINING AREAS I �}' 8.TRENCH ERDEWATERINGAFFECT
DEVICES SHALL E DISCHARGEDDRAINAGE
IN A MANNER THAT WALL
CONSIST OF A THIN LAYER OF WEATHERED `�\ NOT ADVERSELY AFFECT FLOWING STREAMS.DRAINAGE SYSTEMS OR
BASALT GRAVELLY SANDY LOAM OVER OFFSITE PROPERTIES.
( SCALE:1Inch=80 feet
THE PARTIALLY WEATHERED BEDROCK. \ I fO.ALL STORM
T RUC SEWERSHALL BE RECEIVING PROTECTED
80 THAT FROM THE PROTECT DURING
32 .0�3' CONSTRUCTION SMALL BE PROTECTED SO THAT EDICE SYSTEM.WATER
1 OUTC �/ WILL E FILTERED BEFORE ENTERING THE CONVEYANCE SYSTEM.
1 11.ALL OFFSITE CATCH BASINS IMMEDIATELY ADJACENT TO THE SITE FIGURE
,1 SHALL BE PROTECTED FROM SILTATION. �\1 1 L
/ 12.ALL DIMRSED AREAS SHALL BE SEEDED OR SODDED UPON COMPLETION
1 j OF WORK.THE CONTRACTOR SHALL BE RESPONSIBLE TO ENSURE THAT
COMPLETE COVERAGE OF THE DSTURBED AREAS 13 PROVIDED 8 THAT
A` A i GROWTH OF THE VEGETATION IS ESTABLISHED.
13.CATCH BASINS SHALL TRAP SEDIMENT OR FILTER FABRIC MUST BE SITE PLAN
PLACED UNDER GRATE UNTIL VEGETATION IS ESTABLISHED.
FILTER FABRIC MATERIAL 60'WIDE ROLLS
uSE
STAPLES OR WIRE RING TO A77ACM
FABRIC TO WIRE 14 GAUGE Geotechnical
HARE
FABRIC OR EQUIVALENT
2d Testing
327.72'
Laboratory
T
T
i 7d
i Hr MAx
I
1
I
I
i 27(4'WOOD POSTS,STANDARD OR BURY BOTTOM OF FILTER
BETTER OR EQUAL ALTERNATE. MATERIAL IN M12'TRENCH
STEEL FENCE POSTS
1
H
1
1
FILTER FABRIC 8"
I` 2 X2*X14 GAUGE WIRE
J T FABRIC OR EQUIVALENT
1 2'-0
GROUND SURFACE
PROVIDE 314-A 1?WASHED
ANDON BOTH S DES OrnF F'ILLTER 1 z
It FENCE FABRIC ON THE SURFACE 8'
1
AAA 274'WOOD POSTS
ALT'.STEEL FENCE POSTS
i Geotechnical Services
/ FILTER FRIC AB FENCE NOTES:
1.FILTER FABRIC SHALL BE PURCHASED INA CONTINUOUS ROLL CUT TOID QA/QC Services
111 THE LENGTH OF THE BARRIER TO AVO USE OF JOINTS.WHEN JOINTS
111A ARE NECESSARY,FILTER CLOTH SHALL BE SPLICED TOGETHER ONLY AT Testing Services
A SUPPORT POST MATH A MINIMUM 6-INCH OVERLAP AND SECURELY
IOU / FASTENED AT BOTH ENDS TO THE POST.
WAAA /' 2.POSTS SHALL BE SPACED A MAXIMUM OF 8 FEET APART AND DRIVEN
SECURELY INTO THE GROUND(MINIMUM OF W INCHES).
Lr) 3.A TRENCH SHALL BE EXCAVATED APPROXIMATELY 81NCHES WIDE AND 12 10011 Blomberg St.SW
INCHES DEEP ALONG THE LINE OF POSTS AND UPSLOPE FROM THE BARRIER.
C IS USED,A WIRE MESH Olympia,WA 98512
1 4 SUPPORTF NCESHALLBEWHEN STANDARD TFASTENEDB CH FILTER IURELYTOTHEUPSLOPESIDE Phone:(360)754-4612
OF THE POSTS USING HEAVY-DUTY WIRE STAPLES AT LEAST 1 INCH
..� , LONG,TIE WIRES OR HOG RINGS.THE WIRE SHALL EXTEND INTO THE Fax:(360)754-4848
- TRENC 4 H A MINIMUM OF 41NCHES AND SHALL NOT EXTEND MORE THAN 38
�` - J Y INCHES ABOVE THE ORIGINAL GROUND SURFACE.
5.THE STANDARD STRENGTH FILTER FABRIC SHALL BE STAPLED OR WIRED
`? i TO THE FENCE AND 20INCHES OF FABRIC SHALL BE EXTENDED Date: 06/07/2007
C6 J/ INTOTHE RETHAN38 TRENCH.THE FABRIC SHALL NOT Designed b LL
Lr) �O I INCHES ABOVE THE ORIGINAL GROUND SURFACE.FILTER FABRIC SMALL g y'
NOT BE STAPLED TO THE EXISTING TREES.
Drawn by: LL
8.WHEN E%TRASTRENGTH FILTER FABRIC AND CLOSER POSTSPACINGIS Checked by: LL
O1 USED.THE WARE MESH SUPPORT FENCE MAP BE ELIMINATED,M SUCH
A CASE,THE FILTER FABRIC IS STAPLED OR WIRED DIRECTLY TOT. Dwg#:06-07-07-061
POSTS WITH ALL OTHER PROVISIONS OR ABOVE NOTES APPLYING.
1 7 FL R FABRIC FENCES
PERMANENTLY NTL STABILIZEDVED BEFORE THE UPSLOPE
11 AREA FAB RMAN
1 ✓ F� !O 8.FILTER FABRIC FENCES SHALL BE INSPECTED IMMEDIATELY AFTER EACH
RAINFALL AND AT LEAST DAILY DURING PROLONGED RAINFALL.ANY
REWIRED REPAIRS SMALL BE MADE IMMEDIATELY.
A GENERAL EROSION CONTROL NOTES:
1. EROSION CONTROL MEASURES SHALL BE IN PUCE PRIOR TO THE
i BEGIN NGOFCONSTRUCTION THE PROJECT ENGINEER AND THE COUNTY
POTENTI L TI
SHALL INSPECT AND APPROVE THE INSTALLATION OF
INFILTRA ION 1 EROSION CONTROL MEASURES PRIOR TO BEGINNING CONSTRUCTION
A
' J LOCATIO Q 1 2.EROSION CONTROL MEASURES ARE N07 LIMITED TO THE ITEMS
`�\ I ON THIS PUN.THE CONTRACTOR IS RESPONSIBLE FOR THE
INSTALLATION AND MAINTAINANCE OF ALL EROSION CONTROL MEASURES.
T PROPOSEDNO SILTATION OF EXISTING OR SHALLBEALLOWED CARE SHALLB TTAKEN�TOIFPREVENT MIGRATION PROJECT NAME:
_-- T O Y OF SILTS TO OFF STE PROPERTIES.
-------480' '' --- �, 3. LAWRENCE SITE
i TO THE EROSION
CONTROL
MEASURES.
THE
CONTRACTOR SHALL
100 REELER ROAD
TO THE EROSION CONTROL MEASURES.THE CONTRACTORi SHALL PROVIDE
ADDITIONAL EROSION CONTROL MEASURES AS DETERMINED NECESSARY SHELTON WASHINGTON
- ---"- ----____ _ LL BY THE COUNTY INSPECTOR ANDIOR THE PROJECT ENGINEER.FAILURE
TO COMPLY WITH ALL LOCAL AND STATE EROSION CONTROL
FJOO-'''- W REQUIREMENTS MAY RESULT IN CIVIL PENALTIES BEING LEVIED PARCEL 520257500080
J AGAINST THE CONTRACTOR AND/OR PROJECT OJMER
-- - J 4.DURING THE WET SEASON(NOVEMBER TO MARCH)ALL DISTURBED SOILS
PRO OSED SHALL BE STABILIZED$HALLWITHINI48 HOURS AFTER STOP OF WORK EROSION TW
W CONTROL MEASURES SHALL INCLUDE,BUT NOT IL LIMITED TO, Revisions:
111 COVERING THE EFFECTED AREA INCLUDING SPOIL PILES WITH
PLASTIC HEETIN SG.STRAW MATTING,JUTE MATTING.STRAW MULCH,
OR WOOD CHIPS.SEEDING OF THE DISTURBED AREAS SHALL TAKE
NORTH lT' BU/L ING PLACE AS WEATHER PERMITS,
SCALE 1"=BO' ^ WW S.ALL SEEDED OR SODDED AREAS S MALL BE CHECKED REGULARLY
C.I.=10' L OV/ , ,ON W TO MAKE SURE VEGETATIVE COVERAGE IS COMLETE.AREAS SHALL BE
DATUM ASSUMED
I 11 Y' REPAIRED,RESEEDED,AND FERTILIZED AS REQUIRED.
I W T
l
TMHS IS NOT A SURVEY I it I B.TRACKING OF SOIL OFFSITE HILL NOT BE ALLOWED.IF ANY SOIL IS
I ---- 1 1 I
I TRA THAT
ONTO COUNTY STREET,IT SHALL TRACKING
REMOVED WILL
THE ENO
1 I I OF TWAT NARKING DAY.ANY FURTHER TRACKING V MUD ES TIRES
O I BE PREVENTED By
SWEEPING OR WASHING OF THE VEHICLES TIRES
I BEFORE DRIVING ON A COUNTY STREET.
0 20 40 60 80 I AI � ( I
1 i I 7.NO MORE THAN 500 LF OF TRENCH ON A DOWMSLOPE OF MORE THAN 5
WIW / I PERCENT SHALL BE OPENED AT ONE TIME,
R E L L E R '.OAD j/ O B EXCAVATED MATERIAL SMALL BE PLACED ON THE UPHILL SIDE OF TRENCHES
I CI' 9.TRENCHDEWATERINO DEVICES SMALL BE DISCHARGED INA MANNER THAT WALL
NOT ADVE RSELY AFFECT FLOWING STREAMS.DRAINAGE SYSTEMS OR
O OFFSITE PROPERTIES.
32 .03' SCALE:finch=80 feet
I Ar 10.ALL STORM SEWER INLETS RECEIVING RUNOFF SEDI THE PROJECT DURING
1 / CONSTRUCTION SHALL BE PROTECTED 90 THAT SEDIMENTIADEN WATER
WILL BE FILTERED BEFORE ENTERING THE CONVEYANCE SYSTEM.
A
11.ALL OFFSITE CATCH BASINS IMMEDIATELY ADJACENT TO THE SITE
SHALL BE PROTECTED FROM SILTATION. I G U R E 2
12.ALL DISTURBED AREAS SMALL BE SEEDED BOODLE UPON COMPLETION
OF WORK,THE CONTRACTOR SHALL BE RESPONSIBLE TO ENSURE THAT
I COMPLETE COVERAGE THE AREAS PROVIDED THAT
' ! GROWTH OF THE VEGETATION
W
IS ESTABLISHED. SITE PLAN
13.CATCH BASINS SHALL TRAP SEDIMENT OR FILTER FABRIC MUST BE
PLACED UNDER GRATE UNTIL VEGETATION IS ESTABLISHED.
�Q
4
r
NJ
f ,
I/ _.,.
1
... 1 1 i
wV-x
wj
' •- _.
0100,
_ 4.. 400
000
iool
1 /
P c Z �
400
. r
4000
woo
000,
ob
16
/` 1 - —• ' -
�.
� t i
...... ..:....i. \
F
f
AQUA TIERRA JOB NAME: Ati 2 SHEET
r
LAND AND WATER SERVICES INC. JOB ADDRESS: 2 Pc Q•T
CC
IN EDISON STREET SE,SUCt<E 160 DESIGNED
OLYMPIA.WA.QW1 FL ylr PG MCI 6 D IM 660 I-c Ca, DRAWN
TEL
CHECKED
oF:
FAX c 60i 1 DRAWING NAME: cr z n e it-a I S sk-. e4 c hREVISED