HomeMy WebLinkAbout993200322 Geotech Assessment
INCORPORATED
301 East 6th Street, Suite 1
Port Angeles,Washingron 98362
(360) 417-0501
Fax (360) 417-0514
E-mail: zenoyic@olympus.net
GEOTECHNICAL REPORT
NEW SINGLE FAMILY RESIDENCE
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DAVID AND ANDREA NEAULT
640 TALA SHORE DRIVE
PORT LUDLOW, WA 98365
1.0 INTRODUCTION
Zenovic & Associates, Inc. was retained by David and Andrea Neault to complete a
geotechnical report for the proposed construction of a new single-family residence at
640 Tala Shore Drive in Port Ludlow. The report is required pursuant to Jefferson
County Code Section 18.22 (Critical Areas) and 18.25 (Shoreline Master Program) prior
to permitting a residence within 200 feet of the Ordinary High Water mark of Hood Canal
and within a mapped Geologically Hazardous Area.
1.1 Site Location
The site is located on the east side of Tala Shore Drive, approximately 2/3 miles north of
Paradise Bay Road, south and east of the community of Port Ludlow, within the NW ~ of
the SE ~ of Section 15, T 30 N, R 1 E, W.M. The site is at 47 deg. 55' 04" N Lat. and
122 deg. 39' 17" W Long. The site location is shown on the Site Vicinity Map, Figure 1.
1.2 Proposed Construction
We understand that the proposed project consists of the demolition of the existing
dwelling on the property and the construction of a new residence easterly of the existing
house, closer to the marine bluff on the property. A new on-site sewage disposal drain
field will be installed at the approximate location of the existing dwelling.
1.3 Purpose
Pursuant to the Jefferson County Unified Development Code (JCC 18.22), a
Geotechnical Report is required for development on lots which have a designated
Landslide Hazard Area. The marine bank along the east edge of the property meets the
definition of a Landslide Hazard Area as set forth in JCC 18.22.160. The purpose of the
investigation was to evaluate the potential of the failure of the marine bluff that forms the
east edge of the property and establish appropriate protection standards for the lot that
will minimize the potential for impacts to the bank from the proposed development.
Page 2
Geotechnical Report for David and Andrea Neault - 640 Tala Shore Drive, Port Ludlow
October 30, 2008
2.0 SITE INVESTIGATION
2.1 Site Description
The project site is currently developed with a single-family residence, two-story
garage/shop, and a gravel driveway. The lot slopes downhill consistently from west to
east (towards the marine bank) at an average slope of 8-10%. The existing dwelling is
located approximately 100 feet from the top of the marine bank. The garage/shop is
located approximately 20 feet west (uphill) from the dwelling.
The marine bank varies in height from an estimated 50 feet at the north line of the
property to 54 feet at the south line of the property (based on measurements using a
hand-held inclinometer). A concrete bulkhead is situated on the beach at the base of the
bluff, protecting the bluff from the wave and tidal action of the marine waters. A wood
stairway extends up the face of the bank in a zig-zag configuration for a height of
approximately 36 feet. A grass path with a slope of approximately 25 to 30% traverses
the upper portion of the bank from the top of the stairway to the upland part of the
property.
The upland portion of the lot between the top of the bank and the existing dwelling is
covered with lawn and some ornamental plantings. A wood deck extends out a distance
of 16 feet along approximately the middle 1/3 of the dwelling. The upper portion of the
marine bank (above 27' vertical from the beach) slopes at an estimated 70% and is
covered with dense native brush including blackberry, salmonberry, vine maple, and
horsetail ferns. Some non-native plantings are present on the bank, including ivy and
cedar starts.
The lower portion of the bank from the top of the bulkhead to the 27' level slopes at an
estimated 150% and is free of vegetation. A small level area extends from the top of the
bulkhead to the base of the bank for a distance of approximately 10 feet. The top of the
bulkhead is approximately 3 feet above the beach level.
2.2 Geologic Setting
The site lies within the Strait of Juan de Fuca branch of the Georgia Depression. The
Strait of Juan de Fuca Branch was occupied by the Juan de Fuca lobe of the Cordilleran
ice sheet during the Vashon Stade of the Fraser Glaciation.
The Geologic Map of Eastern Jefferson County indicates that the basic geologic
formation of the project area is Vashon Lodgement Till. Till is described as an unsorted,
unstratified, highly compacted mixture of clay, silt, sand, gravel, and boulders deposited
by glacial ice and may contain interbedded stratified sand, silt, and gravel.
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JEFFERSO,~ COUI!TY
OEPT. Of CU;:~lj"'lU;,lrY OEVELOPi\1E;\jT
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Page 3
Geotechnical Report for David and Andrea Neault - 640 Tala Shore Drive, Port Ludlow
October 30, 2008
2.3 USDA Soil Conservation Service Soils Information
The United States Department of Agriculture (USDA) Soil Survey of Jefferson County
Area, Washington, issued August 1975, indicates that the near surface soils (0 to 5 feet
below the existing ground surface (bgs)) at the site consists of the Alderwood-Sinclair
association, soils that are typically moderately well-drained, dominantly strongly sloping
to steep, gravelly soils underlain by compact glacial till. The site soils are mapped as
Cassolary-Kitsap complex (CkD), 15 to 30% slopes.
2.4 Coastal Zone Atlas Information
The marine bank along the project site is designated as and Unstable Old Slide by the
Coastal Zone Atlas. The instability of the slope is a result of the impacts from surface
erosion of the marine bank and shoreline dynamics. While the glacial till soil mass is
relatively stable, the flow of intercepted groundwater will erode the bank face and freeze-
thaw cycles in winter tend to increase this impact. The eroded soil is deposited at the
toe of the bluff, providing some protection of the bank. The wave and tidal action will
erode these soils and allow for further oversteepening. At this site, however, a concrete
bulkhead has been constructed along the base of the bluff, negating this impact. As
such, the slope stability in this location is much greater than a typical marine bank.
2.5 Subsurface Exploration
No test pits were completed for this project due to the lack of access to the portion of the
site adjacent to the marine bank, the ability to observe the near vertical portion of the
bluff adjacent to the shoreline, and the availability of soils information and observation of
two hand dug excavations at the northeast corner of the existing dwelling and along the
west side of the dwelling.
The hand dug test pits revealed soils more typical of the Cassolary sandy loam
characterization. These soils have a surface layer approximately 24" deep of a sandy
loam soil. A thin layer of a variable thickness of silt loam is typically encountered in the
23" to 38" depth range and the soils below 38" tend to be mixed sandy loam and fine to
medium sands to the underlying glacial till layer. The depth to the glacial till is unknown,
but is estimated to be approximately 20 feet based on observation of the face of the
marine bank.
2.6 Groundwater
No groundwater or perched water was encountered in the test pits. The near vertical
face of the marine bank did have surface moisture, indicating that the relatively
impervious glacial till material intercepts moisture that percolates through the overlying
porous soils. Typically, the glacial till material will slope at a grade relatively consistent
with the surface soils. The moisture intercepted by the glacial till material runs downhill
towards the marine bank and discharges at an elevationoiabout27~_abavathe beach
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Page 4
Geotechnical Report for David and Andrea Neault - 640 Tala Shore Drive, Port Ludlow
October 30, 2008
3.0 CONCLUSIONS AND RECOMMENDATIONS
3.1 General
The recommendations for design and construction presented in the following sections
are based on our understanding of the proposed construction (Section 1.2), engineering
assessment of the anticipated subsurface conditions (Section 2.4), and experience with
similar projects in similar soil conditions. If there is any change in the project criteria,
including project location on the site, a review should be made by this office prior to final
design and construction at the site. The design recommendations included in this report
do not apply to future structures.
3.2 Setback from the Top of the Marine Bank
Two slope conditions dictate the appropriate building setback from the top of the bank.
The lower portion of the bank, that portion that is nearly vertical, will slowly recede and
the slope will lessen. This portion of the bank is comprised of the very dense, very
compact fine sand and the rate if recession will be very slow. It is estimated that the rate
of recession will be less than 3_4" per year and that the formation will stabilize when the
slope approaches approximately 1 horizontal to 1 vertical. As such, the top of the glacial
till formation will stabilize about 10 feet westerly of is current location in not less than 30
to 40 years.
The upper portion of the marine bank is comprised of the looser, more porous fine to
medium sands that were found in the test pits. As this soil is relatively porous and does
not retain moisture, the typical slope of repose is about 32 degrees (60%) in the
unsaturated condition. This slope is slightly shallower than the existing slope of 70%. It
is anticipated that the top of this slope will further recede an estimated 8 to 10 feet.
Combining these bank recession numbers results in a total anticipated recession of up to
20 feet. Using a typical safety factor of 100%, the recommended setback from the
existing top of the bluff would be 40 feet. This setback is less than the bank height
setback required by the Shoreline Master Plan.
3.3 Shallow Foundations
Based on preliminary design information, the proposed structure will apparently be
founded on the sandy gravel material well above the till layer. We recommend that the
structure be founded on conventional spread footings or slab on grade bearing on the
natural sandy gravel. A net allowable bearing pressure of 3,000 pounds per square foot
(pst) should be used for the design of all foundations. The allowable bearing pressure
may be increased by 33 percent for short term or infrequent loading such as wind and
seismic loads. The recommended minimlJrtLeJimension of continuous or isolated
footings is 18 inches. .. I, -<_. '::'.'-ri~---_.
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Page 5
Geotechnical Report for David and Andrea Neault - 640 Tala Shore Drive, Port Ludlow
October 30, 2008
JE"FEHSOi'i COUri TY
DEPT. Of CO;',:MUd fY DEVELOPi,'E,'i r
Due to the proximity of the proposed structure to the top of the nearby slope, the
increases allowable sliding resistance as set for the in Section 1804.3.1 of the 2006
International Building Code is not permitted for this project.
3.4 Permanent Slopes
Permanent cut or fill slopes should be designed to be no steeper than 2 horizontal to 1
vertical. Permanent slopes should be replanted with fast-growing, deep rooted grasses,
shrubs, and other ground cover after final grading. If vegetation is not fully established
prior to wet weather occurring, the slopes should be covered with visquene to aid in
preventing excessive erosion and water infiltration.
3.5 Drainage
Control of drainage from impervious surfaces on the site is critical for protecting the
integrity of the marine bank. Saturation of the soils lowers the grade at which the soils
are stable. In addition, the surface soils are very erosive and discharging concentrated
runoff onto these soils will negatively impact slope stability.
Drainage from roof runoff and other impervious surfaces should be collected into a tight
line system and directed to the existing drainage system for the garage/shop structure
that discharges at the base of the marine bank. Proper analysis of runoff rates needs to
be completed to assure that the existing system will not be overloaded with the addition
of this new runoff.
3.6 Groundwater Influence on Structures/Construction
Groundwater was not encountered in the test pit excavations as noted previously. It is
not anticipated that groundwater will be encountered in excavation for the building.
4.0 REVIEW AND CONSTRUCTION OBSERVATIONS
4.1 Review of Plans and Specifications
The recommendations outlined in this report are based only on preliminary plans and
verbal discussions about the project with the Client. It is recommended that Zenovic &
Associates, Inc. be retained to review the final plans and specifications to assure that the
requirements set forth herein are met.
5.2 Construction Observations
Due to the scope of the project, construction observation is not anticipated to be required
for this project. However, if soil conditions that vary significantly from those presented
herein are encountered during site excavation activities, Zenovic & Associates, Inc.
should be contacted to review the conditions and make appropriate changes, if required.
Page 6
Geotechnical Report for David and Andrea Neault - 640 Tala Shore Drive, Port Ludlow
October 30, 2008
5.0 LIMITATIONS
This report has been prepared for David and Andrea Neault regarding the subject
project. Information provided in this report has been collected and interpreted in a
manner consistent with the level of care and skill ordinarily exercised by members of the
profession currently practicing under similar conditions, and in accordance with sound
and generally accepted principles consistent with normal consulting practice. No other
warranty, expressed or implied, including (but not limited to) any warranty or
merchantability or fitness for a particular use has been made.
In the event that change in nature, design, or location of the proposed construction is
made, or any physical changes to the site occur, recommendations are not considered
valid unless the changes are reviewed by our firm and conclusions of this report are
modified or verified in writing.
The subsurface exploration logs and related information depicts conditions only at the
specific locations and at the particular time designated on the logs. The passage of time
may result in a change of subsurface conditions at these exploration locations.
Subsurface conditions at other locations may differ from conditions occurring at the
exploration locations. The nature and extent of variations of subsurface conditions
between exploration locations are not known. If variations appear during additional
exploration or construction, reevaluation of recommendations in this report may be
necessary.
The scope of Zenovic's services did not include an environmental assessment for the
presence or absence of 1) hazardous and/or toxic materials, in the soil, groundwater,
surface water, or atmosphere, and 2) wetlands. Any statements or absence of
statements in this report on any subsurface exploration log regarding staining or odor of
soil, groundwater, surface water, unusual or suspicious items, or conditions observed
are strictly descriptive information for David and Andrea Neault and their selected
consultants and contractors.
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and cobbles; medium acid; clear, wavy boundary. (8 to 12 inches
thick)
CI-18 to 30 inches, dark-gray (lOYR 4/1) gravelly medium sand,
gray (10YR 6/1) dry; single grained; loose, nonsticky, nonpIastic;
common rme and medium roots; 45 percent gravel and cobbles;
medium acid; clear, wavy boundary. (10 to 15 inches thick)
IIC2-30 to 39 inches, dark-gray (lOYR 4/1) very gravelly coarse sand,
gray (10YR 6 /1) dry; single grained; loose, nonsticky, nonpIastic; 55
percent gravel and cobbles; medium acid;
abrupt, wavy boundary. (8 to 13 inches thick)
IIlC3-39 to 60 inches, dark grayish-brown (lOYR 4/2) gravelly loamy
sand, light brownish gray (10YR 6/2) dry; massive; soft, very friable,
nonsticky, nonplastic; 30 percent gravel; slightly acid.
The B2ir horizons range from dark brown to dark yellowish brown.
The C horizons are dark-gray or dark grayish-brown, gravelly to very
gravelly, coarse and medium sand to a depth of 39 inches. Below this
depth is dark grayish-brown gravelly loamy sand or gravelly fine sand.
Reaction of this soil ranges from medium acid to slightly acid.
Included with this soil in mapping are small areas of
Kitsap soils.
This soil is somewhat excessively drained. Permeability
is rapid. Roots penetrate to a depth of more than 60 inches.
This soil holds 3 to 4 inches of water available for plants.
Runoff is slow, and the hazard of water erosion is slight.
This soil is used mainly for production of trees and for
recreation areas and wildlife habitat. Small areas are used
for grass pasture. Capability unit Vis-I; woodland group 312.
Carlsborg ~ravellr. loamy sand, 15 to 30 percent slo{Jes
(CaD).- This hilly SOIl is along the glacial outwash morlUne
terraces where they converge with the steep ravines and
drainageways.
Runoff is slow to medium, and the hazard of water erosion is
slight to moderate.
This soil is used mainly for production of trees and for
recreation areas and wildlife habitat. Capability unit Vis-I;
woodland group 312.
Casey Series
The Casey series consists of somewhat poorly drained soils
that are on terraces. Slopes range from 0 to 8 percent.
Elevation ranges from slightly above sea level to about 500
feet. These soils formed in glacial lacustrine or marine sedi-
ments. Native vegetation is Douglas-fir, western redcedar,
western hemlock, maple, red alder, willow, red elderberry,
salmonberry, and swordfern. Annual precipitation ranges from
180 to 40 inches. T~e avefl~ge annual air temperature is 49 to
50 F. The above 32 F growmg season ranges from 200 to 250
days, and the above 280F growing season ranges from 300 to
330 days. These soils are associated with Agnew, Alderwood,
Everett, and Indianola soils.
In a representative profile the upper 3 inches of the soil is
very dark brown silt loam. Below this, to a depth of 10
inches, is grayish-brown, faintly mottled silt loam. Between
depths of 10 and 17 inches is grayish-brown loam that has
distinct, dark-brown mottles. Beneath this, and extending to
a depth of 33 inches, is gray clay that has distinct,
yellowish-brown mottles. Between depths of 33 and 40 inches is
dark grayish-brown loamy fine sand. Beneath this is gray,
mottled clay that extends to a depth of 60 inches. The
soil is slightly acid above a depth of 17 inches and neutral
below that depth.
Casey soils are used mainly for pasture, wildlife habitat,
recreation areas, and rural homesites. About 50 percent of the
acreage is under cultivation.
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Casey silt loam, 0 to 8 percent slopes (CeB).-This
nearly level to gently sloping soil is on terraces. Most
areas are near marine bluffs at elevations of less than 300
feet. Most slopes range from 2 to 5 percent.
Representative profile in NEl/4SWl/4SWl/4 sec. 33, T. 3 N.,
R. 1 E., 50 yards south of farm road midway between Sound
View cemetery and the Main Marrowstone Island Road:
AI-O to 3 inches, very dark brown (IOYR 212) silt loam, grayish brown
(IOYR 5/2) dry; moderate, medium and coarse, granular structure;
slightly hard, friable, nonsticky, slightly plastic; many fine roots;
slightly acid; gradual, wavy boundary. (2 to 4 inches thick)
A21-3 to 10 inches, grayish-brown (lOYR 5/2) silt loam, light gray
(IOYR 7/2) dry; common, medium, faint dark yellowish-brown
(10YR 4/4) mottles; moderate, medium, subangular blocky structure;
hard, firm, slightly acid; clear, smooth boundary. (4 to 10 inches
thick)
A22-10 to 17 inches, grayish-brown (2.5Y 5/2) loam, light gray (2.5Y
7/2) dry; common, medium, distinct dark-brown (IOYR 4/3)
mottles; moderate, medium, subangular blocky structure; slightly
hard, firm, sticky, plastic; few rme roots; about 5 percent soft, iron-
cemented nodules; thin, patchy clay films in some pores; slightly
acid; abrupt, smooth boundary. (4 to 10 inches thick)
IIB2tg-17 to 33 inches, gray (5Y 5/1) clay, light gray (2.5Y 7/2) dry;
common, medium, distinct yellowish-brown (10YR 5/6) mottles;
strong, medium, prismatic structure; very hard, very firm, very
sticky, very plastic: few fine roots; thin, con~inuo,:,s. clay films in
pores and on faces of peds; moderate organic stammg on faces of
peds; neutral; abrupt, smooth boundary. (14 to 24 inches thick)
IIlCI-33 to 40 inches, dark grayish-brown (2.5Y 4/ 2) loamy fine sand,
light brownish gray (IOYR 6/2) dry; common, fine, prominent
yellowish-red (5YR 4/6) mottles; massive; soft, friable, nonsticky,
nonpIastic: few fine roots; neutral; abrupt, smooth boundary. (0 to 8
inches thick)
IVC2g-40 to 60 inches, gray (5Y 5/1) clay, light gray (5Y 7/2) dry;
few, rme, distinct dark-brown (IOYR 3/3) mottles; massive; very
hard, very firm, very sticky, very plastic; neutral.
The IIB2tg horizon is silty, clay, or silty clay loam, but in places
subhorizons of sandy loam or loamy fine sand are present In places coarse-
textured glacial drift is below a depth of 40 inches.
Included with this soil in mapping are small areas of
moderately well drained and somewhat excessively drained
soils.
This soil is somewhat poorly drained. Permeability is
slow. Roots penetrate to a depth of more than 60 inches.
This soil holds 8 to 10 inches of water available for plants.
Runoff is slow, and the hazard of water erosion is slight. A
seasonal water table is at a depth of 1 to 2 feet.
About 60 to 70 percent of the acreage of this soil has been
cleared and is used mostly for pasture. Berries and vegetable
crops are of minor importance. Capability unit III-w-l;
woodland group 4w2.
Casey fine sandy loam, 0 to 8 percent slopes (CdB).
The upper part of this soil is fine sandy loam.
Included with this soil in mapping, and making up as
much as 20 percent of the mapped areas, are soils that have
layers of stratified sandy loam and loamy sand and that are
gravelly in various parts of the profile.
Most areas of this soil are used for pasture, hay, and silage
crops. About 25 percent of the areas are in native trees.
Capability unit IIIw-l; woodland group 4w2.
Cassolary Series /
The Cassolary series consists of well-drained soils on upland
terraces. Slopes range from 0 to 50 percent. Elevation ranges
from 50 to 500 feet. These soils formed in reworked glacial
and marine sediments. Native vegetation is mainly Douglas-
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fir, western redcedar, western hemlock, red alder, bigleaf
maple, rhododendron, salal, huckleberry, and swordfern.
Annual precipitation ranges from 17 to 25 inches. The
average annual air temperature is 50oF. The above 320F
growing season ranges from about 160 to 260 days, and the
above 280F growing season ranges from about 220 to 320
days. Cassolary soils are associated mainly with Agnew,
Alderwood, Clallam, Dick, Everett, Indianola, Kitsap, and
Tukey soils.
In a representative profile in a wooded area, a thin layer
of organIc litter covers the surface. The upper 23 inches of
the soil is sandy loam. To a depth of 3 inches it is dark
gray, between depths of 3 and 15 inches it is dark brown,
and between depths of 15 and 23 inches it is dark grayish
brown. Below this is grayish-brown silt loam that extends
to a depth of 27 inches. Beneath this, and extending to a
depth of 33 inches, is grayish-brown silty clay loam. The
next layer is li~t olive-brown fme sandy- loam that extends to
a depth of 49 mches. It is underlain to a depth of 60 inches by
very dark grayish-brown medium sand.
Most of the acreage of Cassolary soils is wooded. The
soils are used mainly for production of trees and for small
ranches and rural homesites.
Cassolary sandy loam, 0 to 15 percent slopes (cte). This
nearly level to rolling soil is on upland terraces.
In most places slopes range from 5 to 10 percent.
Representative profile 350 feet east of west quarter corner f
the NWl/4SWl/4SWl/4 sec. 33, T. 30 N., R 1 W.:
01-3 inches to I inch, needles, leaves, bark, and fragments of\WOd
02-1 inch to 0, dark reddish-brown (5YR 2,/2) partly decayed
needles, leaves, bark, and fragments of wood; strongly acid; abrupt,
wavy boundary. (1/2 to I 1/2 inches thick)
A2- 0 to 3 inches, dark-gray (IOYR 4/1) sandy loam, light gray (lOYR
7/1) <by; massive; soft, very friable, nonsticky, nonpIastic; many fine,
medium, and coarse roots; strongly acid; clear, wavy boundary. (2
to 4 inches thick)
B21ir-3 to 15 inches, dark-brown (lOYR 4/3) sandy loam, pale brown
(IOYR 6/3) <by; few, faint dark-brown (7.5YR 4/4) mottles; weak:,
fine and medium, subanguIar blocky structure; soft, very friable,
nonsticky, nonpIastic; many fine, medium, and coarse roots; 10
percent very hard, dark reddish-brown (5YR 3/4) iron concretions;
medium acid; gradual, wavy boundary. (10 to 18 inches thick)
B22-15 to 23 inches, dark grayish-brown (lOYR 4/2) sandy loam, light
brownish gray (lOYR 6/2) dry; few, medium and coarse, distinct
dark-brown (7.5YR 4/4) mottles; weak:, medium and coarse,
subanguIar blocky structure; soft, very friable, nonsticky, nonplastic;
common fme, medium, and coarse roots; 8 percent very hard, dark
reddish-brown (5YR 3/4) iron concretions: medium acid; abrupt,
smooth boundary. (6 to 10 inches thick)
IICI-23 to 27 inches, grayish-brown (lOYR 5/2) silt loam, light gray
(lOYR 712) dry; few, medium, faint dark yellowish-brown
(IOYR 4/4) mottles, massive; hard, firm, slightly sticky, plastic; few
fme and medium roots; medium acid; clear, smooth boundary. (3 to 6
inches thick)
IIC2-27 to 38 inches, grayish-brown (2.5Y 5/2) silty clay loam, light
gray (2.5Y 7, 2) dry; common, medium, distinct dark yellowish-
brown (IOYR 4/4) mottles; massive; hard, firm, sticky, plastic; few
fine and medium roots; slightly acid; clear, smooth boundary. (10 to
16 inches thick)
II1C3-38 to 49 inches, light olive-brown (2.5Y 5/4) fine sandy loam,
light yellowish brown (2.5Y 6/4) dry; few, medium and coarse, faint
yellowish-brown (lOYR 5/4) mottles; massive; soft, very friable,
nonsticky, nonpIastic; slightly acid; clear, wavy boundary. (8 to 12
inches thick)
IVC4-49 to 60 inches, very dark grayish-brown (2.5Y 3/2) and
grayish-brown (2.5Y 5/2) medium sand; dark grayish brown (2.5Y
4/2) and light brownish gray (2.5Y 612) <by; few, coarse, faint
yellowish-brown (IOYR 5/4) mottles; single grained; loose,
nonsticky, nonplastic; few pebbles; neutral.
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The depth to sand or loamy sa~d~;-~~-40 inches-:-l1ieATliiii'iZolls
range from fme sandy loam to sandy loam. The B21ir hori~on i.s dark bro':"l1
or brown fine sandy loam. or sandy loam. The B22 honzon IS dark graYISh
brown or brown fme sandy loam or sandy loam. The C horizons are
interstratified silty clay loam, silt loam, fine sandy loam, sandy loam, loamy
sand, and sand.
Included with this soil in mapping are small areas of
Kitsap soils.
ThIS soil is well drained. Permeability is moderately slow.
Roots penetrate to a depth of more than 60 inches. This soil
holds about 7 to 9 inches of water available for plan.ts. ~unoff
is slow to medium, and the hazard of water erosIOn IS slIght to
moderate.
This soil is used mainly- for production of trees ~d for
recreation areas and wildlife habitat. A small acreage IS used
for permanent pasture, hay, and home garden crops.
Capability unit IIIe-l; woodland group 3d2.
Cassolary sandy loam, 15 to 30 percent slol,)es (CfD).T~is
hilly soil is on terraces along the breaks of ravmes or manne
bluffs. . .
Runoff is medium, and the hazard of water erosIOn IS
moderate. This soil is used mainly for production of trees and
for recreation areas and wildlife habitat. Small acreages are
used for rural homesites and for growing pasture, hay, and
diversified garden crops. Capability unit IVe-3; woodland group
3<12. fE Th'
Cassolary sandy loam, 30 to 50 percent slopes (C ).- IS
steep soil is on canyon slopes and ocean bluffs. The d.ark-gray
surface layer is absent in many places, and the SIlty clay
loam layer in the underlying material is nearer the surface on
the upper part of canyon slopes and ocean bluffs than it is on the
lower ones.
Runoff is rapid, and the hazard of water erosion is severe.
This soil is mainly used for production of trees and for
recreation areas and wildlife habitat. Capability unit Vie-I;
woodland group 3<12.
Cassolary-Everett complex, 0 to 15 percent slopes
(ChC).-This mapping unit is about 60 percent Cassolary
sandy loam, 0 to 15 percent slopes, and 40 percent Everett
gravelly sandy loam, 0 ~o 15 percent slopes. :r~e Ca~solary
soil is mostly gently slop-mg, and the Everett soIl IS roilIng.
Included with these soIls in mapping are small areas where
slopes are as stee(l as 30 per~ent. .
This complex IS used mamly for productIon of trees and for
recreation areas and wildlife habitat. Small acreages are used
for rural homesites and for growing pasture, hay, and
diversified home garden crops. Capability unit IV e-l; woodland
group 3f2.
Cassolary-Everett complex, 15 to 30 percent slopes (ChD).-
This mapping unit is about 60 percent Cassolary sandy loam,
15 to 30 percent slopes, and 40 percent Everett gravelly ~an~y
loam. 15 to 30 percent slopes. The Cassolary SOIl IS
mode~ately steep. The Everett soil is hilly and is mostly on
glacial outwash terraces.
Included with these soils in mapping are small areas where
slopes are less th~ 15 perc~nt. .
This complex IS used mamly f~r productIOn ?f t~ees and. for
recreation areas, rural homesltes, and wIldlIfe habItat.
Capability unit Vie-I; woodland group 3f2.
Cassolary-Kitsap complex, 0 to 15 percent slopes (CkC).-
This mapping unit is about 60 percent Cassolary sandy loam,
o to 15 percent slopes, and 40 percent Kitsap silt loam, 0 to 15
percent slopes. Th~ Casso!ary soil is ~ently .sloping. to gently
rolling, and the Kltsap sOJlls mostly m roilIng terram.
Included with these soils in mapping are small areas where
slope~ are as steel' as 30 per~ent.
This complex IS used mamly for production of trees and for
recreation area~ and wildlife habitat. Small acreages are used
,_~~r rural homesItes and for pasture, hay, and diversified home
,arden crops. Capability unit IIIe-l; woodland group 3d2.
~assolary-Kits!,~ complex, 15 to 30 percent slopes (CkD).-
ThiS mappmg umt IS about 60 percent C.assolary sandy loam,
15 to 30 percent slopes, and 40 percent Kltsap silt loam, 15 to
30 percent sl?pes. T~e ~assolary soil is mainly moderately
steep. The Kltsap soIl IS moderately steep and is on hilly
te~ce benches along the upper margIns of steep ravines and
manne bluffs.
Included with these soils in mapping are small areas where
slopes are less than 15 percent and some where slopes are
more than 30 percent.
This. complex is used mainly for production of trees and for
recreation areas, rural home sites, and wildlife habitat. Small
acreages are used for pasture, hay, and diversified home
garden crops. Capability unit IVe-3; woodland group 3d2.
~assolary-Kits!lP. complex, 30 to 50 percent slopes (CkE).-
ThiS mappmg umt IS about 50 percent Cassolary sandy loam
30 to 50 percent slopes, and 50 percent Kitsap silt loam, 30 to 50
percent slopes.
Included with these soils in mapping are small areas where
slopes are less than 30 percent.
This. complex is used mainly for production of trees and for
recreatIOn areas, rural homesites, and wildlife habitat
Capability unit Vie-I; woodland group 3d2. .
Cathcart Series
The Cathcart series consists of well-drained soils underlain by
sand~tone bedrock at a depth of 24 to 40 inches. They are on
glaCiated uplands. Slopes range from 0 to 50 percent. Elevation
ranges from about 50 to 800 feet. These soils formed in
weathered sandstone and shale and some glacial till. Native
vegetation consists mostly of Douglas-fir, western hemlock,
western redcedar, red alder, maple, salal, salmonberry,
huckleberry, bracken, and swordfern. Annual precipitation
ranges from. 25 to 450 inches. The avoerage annual air
temperature IS about 50 F. The above 32 F growing season
rang~s from about 160 to 260 days, and the above 280F
growmg season ranges from about 220 to 320 days. These
soil.s are a~sociate~ mainl~ wi.th Alderwood, Cassolary,
Indlanola, KItsap, 9uIlcene, SInclair, and Whidbey soils.
In a representative profile the upper 9 inches of the soil is
~ark-br<?wn gravelly silt loam. Below this, to a depth of 21
Inches, IS dark-brown or dark yellowish-brown gravelly heavy
loam. The. next layer, to a depth of 30 inches, is yellowish-
brown, faIntly mottled gravelly loam. Beneath this and
exten~ing to a depth of 38 inches, is yellowish-b~own,
promInently mottled very gravelly heavy loam. It is
underlain by yellowish-brown and light brownish-gray
~andstone bed~ock. The soil !s medium acid throughout except
In the upper 3 ..nches, where It,iS strongly acid.
Cathcart soIls are used maInly for production of trees, for
pastur~, and for wildlife habitat, recreation areas, and rural
homesltes.
~athcart gravelly silt loam, 0 to 15 percent slopes (CIC).-
ThiS nearly level to rolling soil is on glaciated uplands. Most
slopes range from 5 to 10 percent.
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NOV - 5 2008
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JEFFEHSO!~ COU~TTY-'.
OWL OF COi\H..~u.ilrY OEVtLOP:'i'Ei~r
Representative profile 1,240 feet north and 100 feet west
of the east quarter comer sec. 17, T. 28 N., R. 1 W.:
ApI-O to 3 inches, dark-brown (7.5YR 3/2) gravelly silt loam,
brown (75YR 5/2) dry; moderate, fine and medium, granular
structure; soft, very friable, nonsticky, slightly plastic; many fine
roots; 30 percent small and medium, rounded glacial pebbles
and 5 percent fragmental sandstone pebbles; strongly acid; clear,
smooth boundary. (2 to 8 inches thick)
Ap2-3 to 9 inches, dark-brown (7.5YR 312) gravelly silt loam, brown
(7.5YR 5/2) dry; weak, fme, subangular blocky structure parting to
moderate, medium and coarse granular structure; soft, very friable
nonsticky, slightly plastic; many fine roots; 30 percent small and
medium, rounded glacial pebbles and 5 percent fragmental
sandstone pebbles; medium acid; clear, wavy boundary. (0 to 6
inches thick)
B21 ir-9 to 15 inches, dark-brown (7.5YR 4/4) gravelly heavy
loam, light yellowish brown (10YR 6/4) dry; moderate, medium,
subangular blocky structure; slightly hard, very friable slightly
sticky, slightly plastic; many fine roots; 15 percent' rounded
glacial pebbles and 15 percent fragmental sandstone pebbles;
medium acid; clear, wavy boundary. (4 to 10 inches thick)
B22-15 to 21 inches, dark yellowish-brown (JOYR 4/4) gravellr heavy
loam, light yellowish brown (JOY R 6/4) dry: moderate, medIUm and
coarse. subanguIar blocky structure; slightly hard, very friable
slightly sticky, slightly plastic; common fine roots; 15 percent
rounded glacial pebbles and 15 percent fragmental sandstone
pebbles; medium acid; clear, wavy boundary. (4 to 8 inches thick)
B3-21 to 30 inches, yellowish-brown (10YR 5/4) gravelly loam, very
pale brown (lOYR 7/4) dry; few, fine, faint yellowishbrown
(lOYR 5/8) mottles; weak, coarse, subanguIar blocky structure'
slightly hard, friable, slightly sticky, slightly plastic; 35 percent
fragmental sandstone pebbles and 10 percent rounded glacial
pebbles; medium acid; clear, wavy boundary. (4 to 10 inches thick)
C-30 to 38 inches, yellowish-brown (lOYR 5/4) very gravelly
heavy loam, very pale brown (lOYR 7/4) dry; common, fine and
m~dium, prominent yellowish-red (5YR 5/8) mottles; massive;
shghtIy hard, friable, slightly sticky, slightly plastic; few fine
roots; 65 to 70 percent fragmental sandstone pebbles; medium acid'
clear, wavy boundary. (0 to 8 inches thick) ,
R-38 to 60 inches, yellowish-brown (lOYR 5/4) and light brownish
gray (2.5Y 6,12) sandstone bedrock.
The depth to sandstone bedrock ranges from 24 to 40 inches. In
wooded areas the Al horizon is dark-brown gravelly loam as much as 4
inches thick, and in places the A2 horizon is less than 1 inch thick. The
Ap horizon is dark-brown or dark reddish-brown gravelly silt loam or
gravelly loam. The B2Iir horizon is dark-brown or dark reddish-brown
gravelly loam or gravelly clay loam. The B22 horizon is dark-brown
dark yellowish-brown, or yellowish-brown gravelly loam or gravelly clay
loam. The B3 and CI horizons have the same color range as the B22
horizons but in places are very gravelly loam or very gravelly clay
loam.
Included with this soil in mapping are small areas of
Kitsap soils. Also included are areas of soils more than 40
inches deep' to sandstone bedrock.
This soIl is well drained. Permeability is moderate. Roots
penetrate to the bedrock. This soil holds 3 to 6 inches of water
available for plants. Runoff is slow to medium, and the
hazard of water erosion is slight to moderate.
This soil is used mainly for production of trees and for
wildlife habitat and recreation areas. About 25 percent of
the acreage is under cultivation and is used for pasture and
small home gardens. Capability unit IIIe-l; woodland group
4d2.
Cathcart gravelly silt loam, 15 to 30 percent slopes
(ClD).-This hilly soil is on glaciated uplands. Along the
upper part of the slopes the soil is mostly 24 to 36 inches
deep to bedrock. In places along the lower part of the slopes
depth to bedrock is 40 to 48 inches.
Runoff is medium to rapid, and the hazard of water
erosion is moderate to severe. This soil is used mainly for