HomeMy WebLinkAboutGeoTech Report for BLD2006-01289 - BLD Engineering / Geo-tech Reports - 8/22/2006 ypN.sTAV. 0� MASON COUNTY
�P MCp PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER
S N Shelton, Washington 98584
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DATE: August 22, 2006
INTER-DEPARTMENTAL COMMUNICATIONS
TO: Chuck McCoy PARCEL # 12330-51-00074
FROM: John Sliva, Programs Engineer-PW BUILDING PERMIT NUMBER: BLD2006-01289
SUBJECT: Geotechnical Report Review NAME: Burgess Bill
Chuck,
The Geotechnical Report prepared for the proposed residence located at 40 NE Skipper Ct. at
Belfair has been received and reviewed by Public Works.
The report itself leads me to believe the residence will be built close to a 40% plus slope. Slopes
that are over 40%with a greater than 10 foot vertical relief with-in 300 feet of the structure require a
Geotechnical Report. The author indicates this is the case at this site. A review of the
Geotechnical Report does not address Chapter 17.01 .100.E.5 Items 4, 5 & 9.
Item 4 Addresses a cross section at scale depicting the subsurface profile and which incorporates
the details of proposed grade changes.
Item 5 Addresses the County receiving a description and results of slope stability analyses
performed for both static and dynamic loading conditions. (This requires a copy of
calculations/modeling used).
Item 9 Addresses analysis of both On-site and Off-site impacts of the proposed development.
I cannot recommend accepting the Geotechnical Report until all items in Chapter 17.01.100.E.5
are addressed in the Report. The additional required information can be submitted as an
addendum to the initial report.
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.
S.nc�erely,
ohn iva
'Programs Engineer
GeoResources, LLC
Fx. 253-896-1011 5007 Pacific Hwy. E. Ste. 20
Fx. 253-896-2633 Fife, Washington 98424-2462
June 21, 2006
Mr. Bill Burgess ' —
Real Estate USA R E C t
5209 Point Fosdick Rd NW 2 JUL 0 7tfl1F
Gig Harbor, WA 98335
Geotechnical Report BELFAIR
C3
F*ICE
Single-Family Residence
9 Y
40 NE Skipper Ct.
Mason County, WA
JobNo: Real EstateU SA.NESkipperCt.RG
INTRODUCTION
This geotechnical report summarizes the results of our geotechnical engineering
services for the proposed single-family dwelling to be constructed at 40 NE Skipper Ct in
Mason County, Washington. The approximate location of the site is shown on the Site
Vicinity map provided in Figure 1.
The middle portion of the lot slopes at greater than 40 percent and has a vertical
height of greater than 10 feet. Mason County therefore requires a geotechnical report be
prepared to address slope stability issues and provide geotechnical recommendations
and design criteria for the proposed two story single-family residence utilizing a
conventional foundation. The site slopes are delineated on the Exploration Location Plan
provided in Figure 2.
We understand that you propose to construct a single-family residential structure
in the flat, northern portion of the site. Site access will be from the north and the cul-de-
sac of NE Skipper Court. Specific design details are not available. However, it is our
understanding the house is designed according to current IBC Standards.
Our understanding of the project is based on our discussions with you, our review
of the available project plans and our local experience with similar projects in the vicinity
of the site.
SCOPE
The purpose of our services is to address the landslide and erosion hazard issues at
the site according to the Mason County environmental policies provided in the Mason
County Code, and to provide geotechnical recommendations and design criteria for
design and construction the proposed residential site improvements. Specifically, the
scope of services for this project will include the following:
1. Conducting a geologic reconnaissance of the site area.
2. Exploring the subsurface conditions at the site by monitoring the excavation of a
series of back-hoe excavated test pits at selected locations across the site.
3. Addressing the appropriate geotechnical regulatory requirements for the
proposed site development, including landslide and seismic hazards.
4. Providing geotechnical recommendations for site grading including site
preparation, subgrade preparation, fill placement criteria, suitability of on-site soils
for use as structural fill, excavations, and drainage and erosion control measures.
RealEstateUSA.NESkipperCt
June 21, 2006
Page 2
5. Providing recommendations and design criteria for foundation and floor slab
support, including allowable bearing capacity, lateral soil pressures and estimates
of settlement.
SITE CONDITIONS
Surface
The site is located south of Larsen Lake and west of the town of Belfair within a
developed residential community. The site is lot 74 of the Beards Cove Division 4
development. Existing residential structures are located along the east and west sides of
the lot. The site is currently vacant and undeveloped. A Site Vicinity Map is attached as
Figure 1.
The site is triangular, becoming wider as it extends south from the end of the end
of the cul-de-sac for NE Skipper Court. The northern portion of the lot is flat from the
cul-de-sac to approximately 80-feet before sloping down at an approximate 75 percent
grade for a vertical height of approximately 17 feet. Surface grades beyond the toe at
the east end of the steep slope flatten out to inclinations ranging from 5-15 percent.
Surface grades beyond the toe at the west end of the steep slope flatten out to
inclinations of approximately 30 percent. It is our understanding the area south of the
site was previously used as a borrow source. The current slopes south of the site are
the result of this past activity.
Vegetation along the northern, flat portion of the site generally consists of a
mowed grass lawn and a couple small to medium sized evergreen trees. The majority of
the ground surface was chewed up by recent activity at the site. The vegetation along
the site slopes located in the southern portion of the site generally consists of various
medium-sized evergreen trees with occasional deciduous trees. The underbrush is very
thick and dense. Due to recent exploration activity at the site, a small portion of the east
end of the slope has been denuded of vegetation but showed no signs of erosion or
instability at the time of our site visit.
Geology
The Geologic Map of Washington State, by Eric Schuster, dated 2005, shows soils
in the vicinity of the site consisting of Pleistocene Continental Glacial Drift (Qgd). These
soils are described as undifferentiated Till and Outwash sand and gravel. The medium
dense sands and gravels observed in the test pits are consistent with the classification of
Outwash. The existing topography, as well as the surficial and shallow subsurface soils
in the area, is the result of the most recent Vashon stade of the Fraser glaciation that
occurred between about 12,000 and 15,000 years ago, and natural weathering and
erosion processes that have occurred since. A textural description of the surficial soils is
included in the "Soils" section of this report.
Soils
A review of the Soil Conservation Survey (SCS) for Mason County indicates the sites'
surface soils consist of Everett gravelly loamy sand (Eg) that form on 0 to 5 percent slopes.
Past grading activity, south of the site has resulted in slopes steeper than those mapped by
the SCS. The Everett gravelly loamy sand is generally derived from Outwash and is
described as well drained. The Everett soils are listed as having a slight potential for
erosion when exposed according to the SCS. A copy of the SCS soils map for the site is
included as Figure 3. As previously discussed, we observed no evidence of surficial
erosion at the time of our site visit.
J
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June 21, 2006
Page 3
Subsurface Explorations
We explored subsurface conditions at the site by monitoring the excavation of 2 test
pits to a maximum depth of 6 feet below existing surface grades. The test pits were
approximately located in the field by our representative by pacing from existing site features
such as property corners and adjacent roadways. The approximate locations of the test
pits are indicated on the attached Exploration Location Plan presented in Figure 2.
A representative from our office continuously monitored the excavations, maintained
logs of the subsurface conditions encountered in each test pit, obtained representative soil
samples, and observed pertinent site features. The soils encountered were visually
classified in accordance with the Unified Soil Classification System (USCS) described on
Figure 4. The test pit logs are shown in Figure 5. Representative soil samples obtained
from the test pits were placed in sealed containers and taken to a laboratory for further
examination and testing.
Subsurface
The soils observed in our test pits generally consisted of 3 to 6 inches of topsoil
overlying medium dense, moist, sand with gravel and cobbles consistent with glacial
Outwash. Natural weathering processes have disturbed the surficial soils at the site to a
loose to medium dense condition. These soils likely extend to depths in the range of 10
to several 10's of feet. The subsurface conditions encountered in our test pits were
uniform and confirmed the mapped geology of the site.
Groundwater
No groundwater seepage was observed in the test pits at the time of our site
exploration. Based on our observations and experience in the local area, the
groundwater table resides well below the sites surface.
Landslide Hazard Indicators per Mason County Municipal Code
According to the Mason County Code, Section 8.52.140, the purpose of the
landslide hazard section is to identify areas that present potential dangers to public
health and safety, to prevent the acceleration of natural geological hazards, to address
off site environmental impacts, and to minimize the risk to the property owner or adjacent
property owners from development activities. This code defines a landslide hazard area
as:
(A) Areas with any indications of earth movement such as debris slides,
earthflows, slumps and rock falls (see figure F.100 attached to the ordinance codified in
this chapter);
(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 fifteen percent (eight and one-half 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.
Real EstateUSA.NESkipperCt
June 21, 2006
Page 4
(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."
In addition, the following information may be used as a guide by the County to
indicate areas that have a higher likelihood of meeting the above criterion.
(2) The following information may be used as a guide by the county to indicate
areas that have a higher likelihood of meeting the classification criteria above:
(A) The areas identified on the Mason County soil survey map as having slopes
greater than fifteen percent.
(B) The areas identified on the Coastal Zone Atlas, Volume 9, of Mason County,
Washington as:
(i) Unstable - "U"
(ii) Unstable Old Slides - "UOS"
(iii) Unstable Recent Slides - "URS"
(iv) Intermediate Slopes - "I"
(v) Modified Slopes - "M"
(C) The areas identified as Class 2, 3, 4, or 5 of the maps: "Relative Slope
Stability of the Southern Hood Canal Area, Washington," by M. Smith and R.J. Carson,
Washington State Department of Natural Resources, Division of Earth Resources, 1,977
and "The Geological Map of North Central Mason County, Washington," by R.J. Carson,
1,976, U.S. Geologic Survey OFR 76-2.
A review of the Coastal Zone Atlas for Mason County indicates that the site is
located in an area mapped as being Stable (S) for slope stability. According to Mason
County, the site is classified as having landslide hazard areas due to the site having
areas with slopes of forty percent or steeper with a vertical relief of ten or more feet.
CONCLUSIONS
General
Based on a review of the available geologic information, our site reconnaissance,
and our test pits excavated at the site, it is our opinion that the site is currently stable
under the existing conditions. It is also our opinion that the site is suitable for the
residential structure provided the recommended drainage and foundation support options
are incorporated into the site development. Proper surface drainage and erosion control
will reduce the future risk of erosion and slope instability. Deepened foundation support
will provide the necessary erosion protection and slope setback for long term support for
the structure.
Pertinent conclusions and geotechnical recommendations regarding the design and
construction of the proposed development are presented below.
Landslide Hazard Classification
According to Mason County, the site contains landslide hazard areas. Based on our
observations of the site and review of published information, no evidence of past or
ongoing earth movement, landslide activity, or significant erosion was observed. The
slopes south of the site are the result of past borrow activity and were left in a stable
configuration. No significant areas of constructed or over steepened slopes were
observed, nor were slopes with areas containing soft or potentially liquefiable soils
observed. We did not observe areas of active or past stream erosion, nor were there
any areas steepened due to undercutting by wave action. While we did observe areas of
15 percent slopes, we did not observe intersecting contacts or seeps on the slope below
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June 21, 2006
Page 5
the building site. We did, however, observe areas of greater than 40 percent slopes with
more than 10 feet of vertical relief.
Although portions of the site meet the technical criteria of a Landslide Hazard
area, it is our opinion that the site soils are in a stable condition. The construction of the
residence at the site will not have any adverse impact on the stability of the slopes.
Control of the surface drainage at the top of the slope will likely improve the overall
stability on the site.
Slope Stability
Based on our field observations and experience with the soil types encountered
on the property, the site soils appear stable relative to deep-seated failure in their
present configuration. No evidence of past or current landslide activity or significant
erosion was observed at the site at the time of our site visit. No groundwater seeps or
springs were observed on the site or the adjacent slopes at the time of our site visits. No
adverse change in the adjacent area slope stability is expected as a result of the
proposed development.
The steeper slopes along the south end of the site are likely the result of
permanent, stable slope cuts remaining after the gravel mining in the area was
terminated. Additionally, the undisturbed native soils in the steeper slope portions of the
site slopes consist of glacially derived outwash. These soils are in a medium dense to
dense condition except where they have been disturbed by weathering activity. This thin
veneer of surficially weathered soils is typically in a loose to medium dense condition.
Proper planning, design and excavation techniques will reduce the risk of
potential surficial erosion or movement in these areas during site activities and future
development. Erosion control recommendations are provided in the "Erosion Hazards"
section of this report.
Erosion Hazards
A review of the Soil Conservation Survey (SCS) for Mason County indicates the
sites' surface soils consist of Everett gravelly loamy sand (Eg) that form on 0 to 5 percent
slopes. Past grading activity, south of the site has resulted in slopes steeper than those
mapped by the SCS. The Everett soils are listed as having a slight potential for erosion
when exposed according to the SCS. The removal of vegetation and grading activity will
result in an increased risk for erosion. We recommend that temporary and permanent
erosion control measures be installed and maintained during and following construction,
until permanent erosion control measures or landscaping is in place.
We recommend that the existing denuded area be re-vegetated as soon as
practical with native type vegetation or other slope stabilizing landscaping.
During wet weather conditions, erosion control measures may include but should
not be limited to berms and swales to channel surface water runoff, and ground
cover/protection in exposed or disturbed areas. Temporary ground cover/protection such
as jute matting, excelsior matting, wood chips or clear plastic sheeting should be used
during wet weather conditions until permanent erosion protection is established. Silt fences
should be utilized where appropriate.
Graded or disturbed areas should be shaped to avoid concentrations of runoff onto
the site slopes or other erosion-sensitive areas. Collected stormwater from the site should
be dispersed away from the slope, beyond the toe.
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June 21, 2006
Page 6
Buffers
According to Section 8.52.140 in the Mason County Code, a 50 foot buffer of
vegetation is required around landslide hazard areas. As previously discussed, based on
our evaluation, it is our opinion the slope along the south side of the planned residence
location does not constitute a landslide hazard. Therefore, no buffer is required.
Recommended Setback
The Mason County building department may require setback in accordance with
IBC standard requirements. The IBC does require a building setback from slopes that are
greater than 30 percent unless evaluated and reduced, and/or a structural setback is
provided, by a licensed geotechnical engineer. The setback distance is calculated based
on the vertical height of the slope. Vegetation in the setback area may be enhanced, if
approved/required by Mason County. Clearing, grading and filling within the setback area
is allowed if it can be demonstrated that the existing vegetation will not be adversely
impacted or that it can be mitigated (enhanced).
Based on our site observations, in accordance with UBC/IBC guidelines, we
recommend a setback distance of 15 feet from the crest of the slope located south of the
building area. Where this setback distance cannot be met, the foundation elements of the
structure can be extended vertically to meet the horizontal setback distance. Where the
foundation is extended vertically, we recommend that the setback be measured horizontally
from the lower outside edge of the foundation element to the face of the slope. This
structural setback is based on the foundation elements extending to and being founded in
the medium dense to dense native soils.
As previously discussed, weathering, erosion and the resulting surficial sloughing and
shallow land sliding are natural processes that affect steep slope areas. As noted, no
evidence of surficial raveling or sloughing was observed at the site. 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 or near the
steep slope area. Drainage from the roof area should be tightlined to flatter, lowland
area beyond the toe of the steep slope.
• No fill should be placed within the setback area. Grading should be limited to providing
surface grades that promote surface flows away from the slope crest to an approved
point of collection for dispersal beyond the toe of the slope
• No percolation of surface water within 20 feet of Building Setback or top of the steep
slope.
• The septic system may be installed in the front of the house or along the toe of the
steep slope without a setback.
Any setback areas that are disturbed to allow for excavation of the footings should
be restored with structural fill as outlined in the "Structural Fill" section of this report.
The flatter portions of the site (slopes less than 5:1 slopes) may be re-vegetated with
grass. Steeper slopes should be vegetated with a combination of shallow and deep
rooting plants.
Site Preparation
Based on our review of the site plan and our discussions with you, additional
grading at the site will be minimal and generally be limited to the excavation of the
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June 21, 2006
Page 7
foundation and utilities. We expect that grading at the site can be accomplished with
conventional earth moving equipment.
To prepare the site for construction, all vegetation, organic surface soils, and
other deleterious materials including any existing structures, foundations or abandoned
utility lines should be stripped and removed from the site. Organic topsoil will not be
suitable for use as structural fill, but may be used for limited depths in non-structural
areas. Stripping depths ranging from 3 to 6 inches should be expected to remove these
unsuitable soils.
Suitability of On-Site Materials as Fill
Our study indicates the native soils are currently in a moist condition and contain
a relatively low percentage of fines (silt and clay-size particles), which will make them
suitable for use as structural fill in most weather conditions. Accordingly, the ability to
use native soils from site excavations as structural fill will depend on their moisture
content and the prevailing weather conditions when site grading activities take place.
If structural fill will be imported to the site and grading activities are planned
during the wet winter months, or if they are initiated during the summer and extend into
fall and winter, the owner should be prepared to import a wet weather structural fill. For
this purpose, we recommend importing a wet weather structural fill as described in the
"Structural Fill" Section of this report.
Structural Fill
All fill placed to establish finish grades and utility trench backfill should be placed as
structural fill. 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. For planning purposes, we
recommend a maximum loose-lift thickness of 12 inches. We recommend that our
representative be present during site grading activities to observe the work and perform
field density tests.
Fill should be compacted to at least 95 percent of the soils laboratory maximum dry
density (MDD) as determined in accordance with ASTM D-1557 (Modified Proctor). The
moisture content of the soil at the time of compaction should be within two percent of its
optimum, as determined by this same ASTM standard.
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 the No. 200 sieve)
increases, soil becomes increasingly sensitive to small changes in moisture content and
compaction becomes more difficult to achieve. During wet weather, we recommend
using a well-graded sand and gravel with less than 5 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 slightly higher (up to 10 to 12 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.
Excavations
All excavations at the site associated with confined spaces, such as utility
trenches and retaining walls, must be completed in accordance with local, state, or
federal requirements. Based on current Washington State Safety and Health
Administration (WSHA) regulations, the native, loose to medium dense sands and
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June 21, 2006
Page 8
gravels observed on the site would be classified as Type C soils. The deeper dense to
very dense sands and gravels would be classified as Type B soils.
Accordingly, for temporary excavations of less than 20 feet in depth, the side
slopes in Type C soils should be laid back at a slope inclination of 1.5:1
(Horizontal:Vertical) or flatter from the toe to the crest of the slope. Side slopes in Type
B soils can be laid back at a slope inclination of 1:1. All exposed slope faces should be
covered with a durable reinforced plastic membrane during construction to prevent slope
raveling and rutting during periods of precipitation. 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,
or if construction materials will be stockpiled along the slope crest. Where site
constraints prevent safe excavation side slopes, shoring may be necessary.
This information is provided solely for the benefit of the owner and other design
consultants, and should not be construed to imply that GeoResources assumes
responsibility for job site safety. It is understood that job site safety is the sole
responsibility of the project contractor.
Foundations
Residential structures may be supported on conventional spread footing
foundations bearing on competent native soils or on structural fills placed above these
native soils. Foundation subgrades should be prepared as recommended in the "Site
Preparation" section of this report.
Perimeter foundations exposed to the weather should bear at a minimum depth of
1.5 feet below final exterior grades for frost protection. Interior foundations can be
constructed at any convenient depth below the floor slab. We recommend a minimum
width of 18 inches for isolated spread footings and 16 inches for continuous footings.
With footings founded as recommended, we recommend they be designed for an
allowable soil bearing capacity of 2,500 pounds per square foot (psf) for combined dead
and long-term live loads. The weight of the footing and any overlying backfill should be
neglected. The allowable bearing value may be increased by one-third for short-term
loads such as those induced by seismic events or wind loads. With the anticipated loads
and this bearing stress applied, building settlements should be less than one-half inch
total and one-quarter inch differential. All footing areas should be evaluated by a
representative of GeoResources prior to placement of forms.
For designing foundations to resist lateral loads, a base friction coefficient of 0.40
can be used. Passive earth pressures acting on the sides of the footings can also be
considered. We recommend calculating this lateral resistance using an equivalent fluid
weight of 300 pounds per cubic foot (pcf). We recommend not including the upper 12
inches of soil in this computation because it can be affected by weather or disturbed by
future grading activity. This value assumes the foundations will be constructed neat
against competent native soil or backfilled with structural fill, as described in the
"Structural Fill" section of this report. The values recommended include a safety factor
of 1.5.
Lower-level Building and Retaining Walls
The magnitude of earth pressure development on below-grade walls, such as
lower-level building or retaining walls, will partly depend on the quality of the wall backfill.
We recommend placing and compacting wall backfill as structural fill. Wall backfill below
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June 21, 2006
Page 9
structurally loaded areas, such as pavements or floor slabs, should be compacted
according to the specifications provided in the "Structural Fill" section of this report.
To guard against hydrostatic pressure development, drainage must be installed
behind the wall. We recommend that wall drainage consist of a minimum 12 inches of
clean sand and/or gravel with less than 3 percent fines placed against the back of the wall.
In addition, a drainage collector system consisting of 4-inch perforated PVC pipe should be
installed behind the wall to provide an outlet for any accumulated water. The wall drainage
material should be capped at the ground surface with 1-foot of relatively impermeable soil
to prevent surface intrusion into the drainage zone.
With wall backfill placed and compacted as recommended and drainage properly
installed, unrestrained walls can be designed for an active earth pressure equivalent to a
fluid weighing 35 pcf. For restrained walls, an additional uniform lateral pressure of 100
psf should be included. These values assume a horizontal backfill condition and that no
other surcharge loading, such as traffic, sloping embankments, or adjacent buildings, will
act on the wall. If such conditions exist, then the imposed loading must be included in
the wall design. Friction at the base of the wall foundation and passive earth pressure
will provide resistance to these lateral loads. Values for these parameters are provided
in the "Foundations" section of this report.
Slab-On-Grade Floors
Slab-on-grade floors should be supported on subgrades prepared as recommended
in the "Site Preparation" section of this report. Immediately below the floor slab, we
recommend placing a four-inch thick capillary break layer of clean, free-draining, coarse
sand or fine gravel that has less than three percent passing the No. 200 sieve. This
material will reduce the potential for upward capillary movement of water through the
underlying soil and subsequent wetting of the floor slabs. The drainage material should
be placed in one lift and compacted to a firm and unyielding condition.
The capillary break layer will not prevent moisture intrusion through the slab
caused by water vapor transmission. Where moisture by vapor transmission is
undesirable, such as covered floor areas, a common practice is to place a durable plastic
membrane on the capillary break layer and then cover the membrane with a layer of
clean sand or fine gravel to protect it from damage during construction, and aid in
uniform curing of the concrete slab. It should be noted that if the sand or gravel layer
overlying the membrane is saturated prior to pouring the slab, it will not assist in uniform
curing of the slab, and may serve as a water supply for moisture transmission through
the slab and affecting floor coverings. Therefore, in our opinion, covering the membrane
with a layer of sand or gravel should be avoided if floor slab construction occurs during
the wet winter months and the layer cannot be effectively drained.
Drainage
Final exterior grades should promote free and positive drainage away from the
building areas. We recommend providing a gradient of at least three percent for a
minimum distance of ten feet from the building perimeter, except in paved locations. In
paved locations, a minimum gradient of one percent should be provided, unless
provisions are included for collection and disposal of surface water adjacent to the
structure.
Surface water must not be allowed to flow uncontrolled over the crest of the site
slopes and embankments. Surface water should be directed away from the slope crests
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June 21, 2006
Page 10
to a point of collection and controlled discharge. If site grades do not allow for directing
surface water away from the slopes, then water should be collected and tightlined down
the slope face in a controlled manner.
We recommend that roof runoff at the site be collected and directed to beyond
the toe of the steep slope and dispersed via a lateral spreader pipe anchored on the
more gradual slopes with rebar staples. A minimum 4-inch pipe is recommended, the
pipe must be a continuous length of polyethylene pipe from the top of the slope to the
toe. The spreader pipe should be a minimum of 50 feet in length of perforated pipe and
located so as to follow the contour of the slope. Typically the ends of the spreader pipe
are sloped up slightly to prevent direct discharge. Driveway runoff should be sheet
flowed to the adjacent vegetation.
Due to the high permeability of the native soils at the site, perimeter foundation
drains will not be necessary. However, this recommendation relies on the foundations
being backfilled with native site soils or a structural backfill material meeting the
specifications provided in the "Structural Fill" section of this report.
LIMITATIONS
K We have prepared this report for use by Mr. Bill Burgess and members of his
design team, for use in the design of a portion of this project. The data and
recommendations included in this report should be provided to prospective contractors for
their bidding or estimating purposes only. Our report, conclusions and interpretations
should not be construed as a warranty of the subsurface conditions that exist at the site.
Variations in subsurface conditions are possible between the available explorations
and may also occur with time. A contingency for unanticipated conditions should be
included in the budget and schedule.
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 specifi-
cally described in our report for consideration in design.
If there are any changes in the loads, grades, locations, configurations or type 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.
Within the limitations of scope, schedule and budget, our services have been executed in
accordance with generally accepted practices in this area at the time this report was
prepared. No other warranties or conditions, express or implied, should be construed.
RealEstateUSA.NESkipperCt
June 21, 2006
Page 11
Respectfully submitted,
GeoResources, LLC
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Glen Coad Bernard P. Knoll, PE
Engineering Technician Senior Engineer
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DocID:RealEstateUSA.NESkipperCt
Attachments: Figure 1 —Site Vicinity Map
Figure 2—Exploration Location Plan
Figure 3—USDA SCS Soils Map
Figure 4—Soil Classification System
Figure 5—Test Pit Logs
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Approximate Site Location
GeoResources, LLC Site Vicinity Map
5007 Pacific Highway East, Suite 20 40 NE Skipper Ct.
Fife,Washington 98424 Mason County, Washington
Phone: 253-896-1011
Fax: 253-896-2633
JOB# RealEstateUSAAESkipperCt June 2006 Figure 1
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Approximate Site Location
GeoResources, LLC USDA SCS Map
5007 Pacific Highway East, Suite 20 40 NE Skipper Ct.
Fife, Washington 98424 Mason Count Washington
Phone: 253-896-1011 y� g
Fax: 253-896-2633
JOB# Real EstateU SAM ESkipperCt .lone 2006 Figure 3
UNIFIED SOIL CLASSIFICATION SYSTEM
MAJOR DIVISIONS GROUP GROUP NAME
SYMBOL
GRAVEL CLEAN GW WELL-GRADED GRAVEL, FINE TO COARSE GRAVEL
GRAVEL
COARSE GP POORLY-GRADED GRAVEL
GRAINED More than 50%
SOILS Of Coarse Fraction GRAVEL GM SILTY GRAVEL
Retained on WITH FINES
No.4 Sieve GC CLAYEY GRAVEL
SAND CLEAN SAND SW WELL-GRADED SAND, FINE TO COARSE SAND
More than 50%
Retained on SP POORLY-GRADED SAND
No.200 Sieve
More than 50%
Of Coarse Fraction SAND SM SILTY SAND
Passes WITH FINES
No.4 Sieve SC CLAYEY SAND
SILT AND CLAY INORGANIC ML SILT
FINE CL CLAY
GRAINED
SOILS Liquid Limit
Less than 50 ORGANIC OL ORGANIC SILT,ORGANIC CLAY
SILT AND CLAY INORGANIC MH SILT OF HIGH PLASTICITY, ELASTIC SILT
More than 50%
Passes CH CLAY OF HIGH PLASTICITY, FAT CLAY
No.200 Sieve
Liquid Limit
50 or more ORGANIC OH ORGANIC CLAY,ORGANIC SILT
HIGHLY ORGANIC SOILS PT PEAT
NOTES: SOIL MOISTURE MODIFIERS:
1. Field classification is based on visual examination of soil Dry- Absence of moisture,dry to the touch
in general accordance with ASTM D2488-90.
Moist- Damp,but no visible water
2. Soil classification using laboratory tests is based on
ASTM D2487-90. Wet- Visible free water or saturated,usually soil is
obtained from below water table
3. Description of soil density or consistency are based on
interpretation of blow count data,visual appearance of
soils,and or test data.
GeoResources, LLC USCS
5007 Pacific Hwy. E, Ste 20 40 NE Skipper Ct.
Fife, Washington 98424-2648 Mason County, Washington
Ph. 253-896-1011
Fx. 253-896-2633
JOB# Real EstateU SA.NESkipperCt June 2006 FIGURE 4
5007 Pacific Wighway E, Suite 20
Fife, WA. 98424 GeoResources,
Office (253)896-1011 Fax (253) 896-2633
WMMMMj
Test Pit TP-1
DATE- June 9, 2006 LOGGED BY. BPK ELEV:
Depth Soil Description Notes
(feet) M% Other
0 (3 inches TOPSOIL)
Red-orange silty GRAVEL with sand, moist, loose. (GM)
Gray SAND with silt and gravel, moist, medium dense. (SP-SM)
(Outwash)
5
Test pit terminated at 6 feet.
No groundwater seepage encountered.
Test Pit TP-2
DATE: .June 9, 2006 LOGGED BY: BPK ELEV:
Depth Soil Description Notes
(feet) M% Other
(3 inches TOPSOIL)
Red-orange silty GRAVEL with sand, moist, loose. (GM)
Gray SAND with silt and gravel, moist, medium dense. (SP-SM)
(Outwash)
Test pit terminated at 6 feet.
No seepage a9 e encountered.
9 P
Figure 5 JOB: Real EstateU SA.N ESkippe rCt
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WeVEYOR'S CERTIFICATE �( I�"� I HOLM,4N �1SSOC��4TE5
THIS MAP M V SURVEYORS
CORREcn.Y REPRESENrs A SURVEY MADE eY HE OR PROFESSIONAL LAND SURVE UNDER MY DIRECtlCN IN COWFOWUNC.E UA714 TWE REQU/FaFl` T5 FOR P.O.80X 2379
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1 inch = 20 feet
5 to 15 PERCENT SLOPE AREA " • • Exploration Location Plan
TP-) roX�re%a+e 40 NE Skipper Court
Tpg� P,t 15 to 29 PERCENT SLOPE AREA 5007 Pacific Highway East, Suite 20 Mason County, Washington
Loc.A+- 40 PERCENT OR GREATER SLOPE AREA Fife, Washington 98424
Ph: 253-896-1011 Fax: 253-896-2633
JOB# Real EstateUSA.NESkipperCt June 2006 Figure 2
MASON COUNTY PUBLIC WORKS WORK ORDER
RECEIVEDPermit#: �Lp ?.606�- D I Z��f
Date: -2-0 1 ri6 JUL 2 8 2006
Requested by: � z�L(c._ (/4�C- MaNCOUNTYPII nm
Authorized by:
Type of Work:
Public Works
employee in charge: L? Si L J
CHARGE TO:
Name:
Billing Address: k-sk�R-ST
oft UJ14
Phone:
I
WORK PERFORMED:
Employee:
Date:
Hours: /� o
Hourly Rate: 3L .
Total: �6,
ACCOUNTS RECEIVABLE INFO:
Billed Date:
Invoice #:
Amount Billed:
Receipt #
Date:
Amount Paid: