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City of Edmonds
Critical Areas Checklist
The Critical Areas Checklist contained on
this form is to be filled out by any person
preparing a Development Permit
Application for the City of Edmonds prior
to his/her submittal of a development
permit to the City.
The purpose of the Checklist is to enable
City staff to determine whether any
potential Critical Areas are or may be
present on the subject property. The
information needed to complete the
Checklist should be easily available from
observations of the site or data available at
City Hall (Critical Areas inventories, maps,
or soil surveys).
An .applicant, or his/her representative,
must fill out the checklist, sign and date it,
MAR - 7 1997
COMMUNITY SERVICES
and submit it to the City. The City will
review the checklist, make a precursory site
visit, and make a determination of the
subsequent steps necessary to complete a
development permit application.
With a signed copy of this form, the
applicant should also submit a vicinity map
or plot plan for individual lots of the parcel
with enough detail that City staff can find
and identify the subject parcel(s). In
addition, the applicant shall include
other pertinent information (e.g. site
Plan, toPOgraphy map, etc.) or studies in
conjunction with this Checklist to assist
staff .in .completing their preliminary
assessment of the site.
I have completed the attached Critical Area Checklist and attest that the answers provided are
factual; to the best of my knowledge (fill out the appropriate column below).
Owner / Applicant:
Qg
Name
pt)-'�
Street Address
City, State, ZIP 7� J phone
Signature Date
Applicant Representative:
Name
Street Address.
City, State, ZIP Phone
Signature Date
CA FILE NO.
Critical Areas Checklist
Site Information (soils/topography/hydrology/vegetation) 00-d- St
L Site Address/Location: _ E7P > �6rV,57)_ 4-�, 7 A*-, 7-
2. Property Tax Account Number; 43W 0*6 j—� 0�' 0%6 Z
3. Approximate Site Size (acres or square feet): _ Z! 0
4. Is this site currently developed? _yes; no.
r
If yes; how is site developed?_ S//✓�,e4 rrogtii, �y
5. Describe the general site topography_ Check all that apply.
Flat: less than 5-feet elevation change over entire site.
Rolling: slopes on site generally less than 15% (a vertical rise of 10-feet over a
horizontal distance of 66-feet).
Hilly: slopes present on site of more than 15% and less than 30% ( a vertical rise
of 10-feet over a horizontal distance of 33 to 66-feet).
. Steep: grades of greater than 30% present on site (a vertical rise of 10-feet over a
horizontal distance of less than 33-feet).
Other (please describe):
6. Site contains areas of year-round standing water: ,// ; Approx. Depth:
7. Site contains areas of seasonal standing water: v�('� ; Approx. Depth:
What season(s) of the year?
8. Site is in the floodway fioodplain of a water course.
Olt JV AAnge,c w�
9. Site contains a creek or an area where water flows across the grounds surface? Flows are year-
round? Flows are seasonal? (What time of year? ).
10. Site is primarily: forested ; meadow ; shrubs _ ; mixed— ;
urban landscaped (lawn,sbrubs etc)
11. Obvious wetland is present on site:
-- -- —For City Staff Use Only ------ ---
1. Site is Zoned? `-P
�.'p a� — �'reia'r1� cedu1i4.4'Y NMt`1la�r l.wK �,S-'�a '"r/M
2. SCS mapped soil type(s)? k,peWo%,.F *oV %AX4&4r4 bhp G4 MVL4 C if -I S, "f.
3. Wetland inventory or C.A. map indicates wetland present on site? rJ �j"",,.�,
4 ...Critical Areas inventory or C.A. map indicates Critical Area on site? G� "' 'Marl .l�t'1 uJ1 71 (7Q� d
5.. Site within designated earth subsidence landslide hazard area? -1
ST�'P S 1-oi"e 0 K'r_
6. Site designated on the Environmentally Sensitive Areas Map? Hy Atn-4 cil..�``iT% 7-o
DETERMINATION �?T�
STUDY REQUIRED CONDITIONAL WAIVER
WAIV R
Reviewed by:.I Id �
Planner ate
Pev 2-1/�
� ZZC
City of Edmonds
Critical Areas Determination
Applicant: Rob Michel Determination #: CA-97-38
Project Name: Permit Number:
Site Location: 1 811 & 821 Edmonds St. Property Tax Acct #: 14342-080-033-00
Project Description
Non -Project Specific
Determination: Study Required
Due to the presence of Shell Creek and the Shell Creek ravine on or adjacent to the subject
property, a study is required. The purpose of this study would be to identify the location and type
of the slope and the required buffers and setbacks as well as the location of the stream buffers
and setbacks. This reach of Shell Creek is a class 2 stream without salmonids and requires a 25
foot buffer and a 15 foot building setback from the buffer. The ravine appears to be a Steep
Slope Hazard Area. This would need to be confirmed with a Geotechnical study. If it is a Steep
Slope Hazard Area, a buffer of 50 feet is required from the top of the bank/slope and a 15
building setback from the edge of the buffer. The Geotechnical study may recommend a
modification of the 50 buffer down to 10 feet.
If an applicant feels that their development proposal will not effect the Critical Area in any way,
they may request a Conditional Waiver from the requirement to prepare a Study.
Conditional Waiver Criteria must be reviewed on a project by project basis and all criteria must
be found to apply:
1. There will be no alteration of the Critical Area or its required buffers;
2. The development proposal will not impact the Critical Area in a manner contrary to
the goals, purposes, objectives and requirements of the Critical Areas ordinance;
3. The development proposal meets the minimum standards of the Critical Areas
ordinance;
4. The above findings are based on the following conditions of approval:
a.)
Ultimately, the City's goal is to ensure that a Critical Area or its buffer is not adversely impacted
by development. So, prior to issuance of any permits on the site, the following must be
submitted:
A native growth protection easement, in a form acceptable to the City Attorney, must be
recorded on the property with a legal description of the location of the Critical Area
and/or its buffer. A statement must be included which prohibits the construction of
buildings within 15 of a Critical Areas buffer. (Any encroachment into a Critical Area or
its buffer would require the City to grant a reasonable use exception prior to issuance of a
building permit.)
March 13, 1997
Date
ti i TERRA ASSOCIATES, Inc.
`.m. Consultants in Geotechnical Engineering, Geology
and
Environmental Earth Sciences
MAY 3 0 2001
PERMIT COUNTER
Billy and Ilona Anderson
321 NW 201 st Place
Shoreline, Washington 98177
Subject: Geotechnical Consultation
Anderson Addition
811 Edmonds Street
Edmonds, Washington
May 21, 2001
Project No. T-4482
Reference: Preliminary Geotechnical Report, Anderson Additions; by Terra Associates,. Inc.,
Project No. T-4482, dated October.15, 1999
Dear Mr. and Mrs. Anderson:
Based on our conversation with your architect, Mr. Ron Johnson, we understand that the proposed
north foundation wall of the building at.811 Edmonds Street will be approximately six feet north of the
north side of the existing residence. In our referenced report, we recommended that additions to the
existing residences extend no further north than the current northern edge of the existing structures.
We reviewed the proposed building location and foundation on plan sheets prepared by Ronald D.
Johnson Architect, dated May 1, 2001. Based on our review of these plans and our preliminary
geotechnical report, it is our opinion that the north building wall can be located as planned, provided
the foundation is supported by competent native soil with the outer edge of the footing at least ten feet
from. the face of the slope, and. building and lot drainage is not directed toward .the slope in an
uncontrolled manner. Based on conditions observed in Boring B-2, it may be necessary to lower
footing elevations on the north side of the building by several feet to reach the native bearing soil.
12525 Willows Road, Suite 101, Kirkland, Washington 98034
Phone (425) 821-7777 * Fax (425) 821-4334 • terra@terra-associates.com
M
Billy and Ilona Anderson
May 21, 2001
We trust this information is sufficient for your current needs. If you have any questions or require
additional information, please call.
Sincerely yours,
TERRA ASSOCIATES, INC.
Sae.('
Pr ct Engitepn g Ge
�}bY
The f
Princip
cc: Mr. Ron Johnson, Ronald D. Johnson Architect, P.S
Project No. T-4482
Page No. 2
PRELIMINARY GEOTECHNICAL REPORT
RECEIVED
.., , 2 f/y 4 � ry
i.✓V
DEVELI SERVICES
C'TM OF EDMOND",
Anderson Additions
811 and 821 Edmonds Street
Edmonds, Washington
Project No. T-4482
Prepared for:
Billy and Ilona Anderson
Edmonds, Washington
October 15, 1999
TERRA ASSOCIATES, Inc.
Consultants in Geotechnical Engineering, Geology
and
Environmental Earth Sciences
October 15, 1999
Project No. T-4482
Billy and Ilona Anderson
321 NW 201stPlace
Shoreline, Washington 98177
Subject: Preliminary Geotechnical Report
Anderson Additions
811 and 821 Edmonds Street
Edmonds, Washington
Dear Mr. and Ms. Anderson:
As requested,. we have conducted a preliminary geotechnical engineering study for the subject project. The
attached report presents our findings and recommendations for the geotechnical aspects of project design and
construction.
Our field exploration indicates the site is generally underlain by medium dense to very dense sand with varying
amounts of gravel, followed by hard silt and clay. We did not encounter groundwater in either of the borings
drilled at the site. We did not observe indications of recent significant instability, groundwater seepage, or
erosion on the steep slope in the central and northern portions of the site.
In our opinion, the site conditions are suitable for the planned renovation/expansibn. The undisturbed native
soils are suitable for supporting the expected building loads. However, based on the results of our stability
analyses, we do not recommend expansion beyond the northern edges of the existing residences.
Provided the recommendations presented in this report are incorporated into project design and construction, we
do not expect that the planned renovation/expansion will have an adverse impact on the stability of the steep
slope at the site, or on adjacent properties.
We appreciate the opportunity to be of service to you during the design phase of this project and look forward to
working with you during the final design and construction phases.
12525 Willows Road, Suite 101, Kirkland, Washington 98034
Phone (425) 821-7777 • Fax (425) 821-4334 • terra@terra-associates.com
Billy and Ilona Anderson
October 15, 1999
We trust the information presented in this report is sufficient for your current needs. If you have any questions or
require additional information, please call.
Sincerely yours,
TERRA ASSOCIATES, INC.
c
7ohnSadler, R.P.G.
Project Engineering Ge
T eodore J. Sc er, P. O
�ora742
Principal Engineer 010iAL
JCS/TJS:dvp W RES 6118/4
Cc: Mr. Percy Tse, Roth Hill Engineering Partners
Project No. T-4482
Page No. ii
TABLE OF CONTENTS
Page
1.0
Project Description.................:....................................................................................... 1
2.0
Scope of Work................................................................................................................ 1
3.0
Site Conditions............................................................................................................... 1
3.1 Surface............................................................................................................... 1
3.2 Soils................................................................................................................... 2
3.3 Groundwater...................................................................................................... 3
4.0
Geologic Hazards............................................................................................................ 3
4.1 Erosion...............................................................................................................3
4.2 Steep Slope........................................................................................................ 3
4.3 Landslide........................................................................................................... 4
4.4 Seismic........................:......................................................................................5
5.0
Discussion and Preliminary Recommendations............................................................. 5
5.1 General...............................................................................................................5
5.2 Building Setbacks from Steep Slopes................................................................ 5
5.3 Site Preparation and Grading.............................................................. :.............. 5
5.4 Foundations....................................................................................................... 6
5.5 Drainage.............................................................................................................7
6.0
Additional Services......................................................................................................... 7
7.0
Limitations.......................................:..............................................................................8
Figure_
VicinityMap.......................................................................................................................Figure 1
Exploration Location Plan...................................................................................................Figure 2
Generalized Geologic Section A-A..................................................................................... Figure 3
Generalized Geologic Section B-B.....................................................................................Figure 4
Appendix
Field Exploration and Laboratory Testing....................................................................Appendix A
(i)
Preliminary Geotechnical Report
Anderson Additions
811 and 821 Edmonds Street
Edmonds, Washington
1.0 PROJECT DESCRIPTION
The proposed project consists of the renovation/expansion of the two existing residences on the site. No building
or development plans were available at the time of our study.
The recommendations contained in this report are based on limited site development information. Therefore, our
recommendations should be considered preliminary. We should review final design drawings and specifications
to verify that our recommendations have been properly interpreted and incorporated into project design.
2.0 SCOPE OF WORK
On September 8, 1999, we drilled 2 test borings to a maximum depth of 31.5 feet below the existing surface
grades. Using the information obtained from the subsurface exploration, we developed preliminary geotechnical
recommendations for project design and construction. Specifically, this report addresses the following:
• Soil and groundwater conditions
• Geologic hazards
• Site preparation and excavation
• Building setbacks from steep slopes
• Foundation design
• Surface and subsurface drainage
3.0 SITE CONDITIONS
3.1 Surface
The project site is comprised of two residential lots located at 811 and 821 Edmonds Street in Edmonds,
Washington. The approximate location of the site is shown on Figure 1. The site is bordered by Edmonds Street
to the south, single-family residences to the east and west, and a steep ravine to the north. Shell Creek is located
at the bottom of the ravine.
October 15, 1999
Project No. T-4482
Both lots are occupied by single-family residences. The residence at 811 Edmonds Street is a single -story wood -
frame building with a daylight basement and a carport. A topographic survey by Roth Hill Engineering Partners,
Inc., dated July 29, 1999, indicates that the main and basement floor elevations of the residence are Elev. 209.3
and Elev. 201.8, respectively. A large wooden deck extends from the northern side of the residence at the main
floor elevation.
The residence at 821 Edmonds Street is single -story concrete block building. A floor elevation of 210.0 is shown
on the topographic plan. An eight -foot wide concrete patio extends from the northern side of the residence. A
wood -frame shed is adjacent to the northeastern corner of the residence. We did not .observe any signs of
significant distress to the buildings due to settlement or apparent slope movement.
Site grades are relatively flat on the southern side of the residences. The gradient slopes moderately to steeply
down to the north-northeast on the northern side of the residences. The topographic survey indicates the slope on
the northern side of the residences is approximately 60 to 70 feet high, with elevations ranging from about Elev.
210 near the southeastern corner of the site to about Elev. 140 along the southern edge of Shell Creek. Grades on
the upper 20 to 25 feet of the slope range between 20 and 50 percent. Grades on the lower 40 feet of the slope
range between about 75 and 90 percent.
We did not observe indications of recent significant movement or instability on the slope. We did not observe
indications of groundwater seepage, saturated surface conditions, or recent significant erosion on the slope.
However, in addition to relatively straight coniferous trees, we did observe several mature conifers with bowed
trunks on the steeper portions of the slope, indicating long-term relatively shallow soil creep.
Site vegetation in the vicinity of the residences generally consists of mature coniferous trees and landscaping
shrubs and bushes. The slope is generally vegetated with mature coniferous and deciduous trees with a brush
undergrowth.
3.2 Soils
The soil encountered in the borings generally consists of 26.5 to 31.0 feet of medium dense to dense sand with
varying amounts of gravel overlying hard clay. We encountered dry, very loose to loose sand in the upper six to
seven feet of each boring. The very loose sand appeared to be fill that was placed when the houses were
constructed. The fill appears to be localized to the northern side of the houses and does not appear to extend
downslope.
Detailed descriptions of the subsurface conditions encountered in the borings are presented in Appendix A. The
approximate boring locations are shown on Figure 2.
The Geologic Map of the Edmonds East and Part of the Edmonds West Quadrangles, Washington, by James P.
Minard, dated 1983, classifies the soils in the vicinity of the site as advance outwash sands. Transitional bed
sediments, described as massive to bedded clay, silt, and fine to very fine sand, are shown underlying the advance
outwash sands. The silt and clay soils encountered in the borings are consistent with this classification. The map
shows the contact between the advance outwash and the transitional beds at approximately Elev. 120. We
encountered the silt and clay at elevations of approximately Elev. 170 to Elev. 180.
Page No. 2
October 15, 1999
Project No. T-4482
3.3 Groundwater
We did not encounter groundwater in the borings. However, the sands immediately above the silt and clay in
Boring B-2 were wet. We expect that a perched water table will develop on top of the hard silt and clay during
the wet winter and spring months.
In general, water infiltrates through the sands and becomes perched on the hard silt and clay. The relatively low
permeability of the silt and clay impedes the downward migration of water and causes it to flow laterally along
the surface of the silt and clay, where it can emerge as seeps and springs at lower elevations.
4.0 GEOLOGIC HAZARDS
4.1 Erosion
The Soil Conservation Service (SCS) has mapped the site soils as Alderwood-Urban land complex, 8 to 15
percent slopes in the relatively flat southern portion of the site, and Alderwood-Everett gravelly sandy loams, 25
to 70 percent slopes in the sloping northern portion of the site. The hard silt and clay observed at depth in the
borings, and expected to occur at lower elevations on the slope, would best correlate with Kitsap silt loam, 25 to
50 percent slopes.
The erosion hazards for soils classified as Alderwood-Urban land complex, 8 to 15 percent slopes and
Alderwood-Everett gravelly sandy loams, 25 to 70 percent slopes are classified as slight and moderate,
respectively. The erosion hazard for soils classified as Kitsap silt loam, 25 to 50 percent slopes is considered
high. While we did not observe indications of significant active erosion on the slope at the site, the soils on the
slope will be susceptible to erosion if exposed. Erosion protection measures, as required by the City of Edmonds,
will need to be in place prior to and during grading activities at the site.
4.2 Steep Slope
The City of Edmonds defines steep slope hazard areas as any ground that rises at an inclination of 40 percent or
more within a vertical elevation change of at least 20 feet. Based on this definition and the topographic
information provided to us, the slope located north of the eastern residence (821 Edmonds Street) is considered a
steep slope hazard area.
The slope located immediately north of the western residence (811 Edmonds Street) is not considered a steep
slope hazard area. The topographic information provided to us indicates that slope grades in that area range
between about 23 and 39 percent. The slope located off the northern edge of the subject property would be
considered a steep slope hazard area.
Page No. 3
October 15, 1999
Project No. T-4482
4.3 Landslide
The City of Edmonds defines landslide hazard areas as follows:
1. Any area with slopes of 15 percent or greater and impermeable soils (typically silt and clay) frequently
interbedded with granular soils (predominantly sand and gravel) and springs or groundwater.
2. Any area that includes areas with significant visible evidence of groundwater seepage, which also
includes existing landslide deposits, regardless of slopes.
3. Any area that has shown movement during the Holocene epoch (from 10,000 years ago to present) or is
underlain by mass wastage debris of that epoch as determined by a qualified geologist or geotechnical
engineer.
4. Any area potentially unstable as a result of rapid stream incision or stream bank erosion.
5. Any area located on an alluvial fan, presently subject to or potentially subject to, inundation by debris
flow or deposition of stream -transported sediments.
During our site visit, we did not observe on -site indications of recent significant instability, groundwater seepage,
or significant erosion on the slope face. The slope generally supported growth of mature trees, including some
relatively straight coniferous trees. However, because of the soil conditions observed at the test boring, the site
slopes would be defined as a landslide hazard area.
Stability analysis indicates that the steep slope north of the residences is currently stable and would be marginally
stable during a severe seismic event. The minimum factors of safety determined by our analysis for static
conditions and under severe seismic loading conditions north of each residence are as follows:
811 Edmonds Street
Static: Minimum factor of safety = 1.53
Seismic: Minimum factor of safety = 1.03
821 Edmonds Street
Static: Minimum factor of safety = 1.45
Seismic: Minimum factor of safety = 1.001
Our pseudostatic (seismic) analysis is based on a horizontal acceleration value of 0.2g.
Our test borings and available geologic information indicate that the soils on the slope consist primarily of
medium dense to dense sand and gravel overlying hard transitional bed silt and clays. In our opinion, provided
the recommendations in this report are followed, the proposed project will not increase the potential for slope
instability on -site or on adjacent properties, and the risk for such an occurrence is minimal.
Page No. 4
October 15, 1999
Project No. T-4482
4.4 Seismic
The Puget Sound area falls within Seismic Zone 3, as classified by the 1997 Uniform Building Code (UBC).
Based on the soil conditions encountered and the local geology, a soil profile type of Sc, from Table 16-J of the
1997 UBC, should be used in design.
Liquefaction is a phenomenon where there is a reduction or complete loss of soil strength due to an increase in
water pressure induced by vibrations. Liquefaction mainly affects geologically recent deposits of fine-grained
sands that are below the groundwater table. Based on the soil and groundwater conditions we encountered, it is
our opinion that the risk for liquefaction to occur in potential building areas at this site is negligible.
5.0 DISCUSSION AND PRELIMINARY RECOMMENDATIONS
5.1 General
Based on our study, the site is suitable for the planned expansion/remodel from a geotechnical standpoint. The
native soils encountered below the surficial fills are suitable for supporting residential building loads.
The following recommendations should be incorporated into the project design drawings and construction
specifications. These recommendations are preliminary and may be altered or augmented upon review of the
final plans.
5.2 Building Setbacks from Steep Slopes
Because of the proximity of the steep slope to the existing residences, we used the results of our stability analyses
to determine limits of encroachment to the steep slope areas. As discussed, our analysis indicates the stability of
the slope will be marginal during a severe seismic event. The failure surface representing the lowest determined
factors of safety would affect the slope within about 24 feet of the northern edge of the western residence, and
immediately north of the northern edge of the eastern residence.
Based on our study, it is our opinion that additions to the existing residences should extend no further north than
the current northern edge of the existing structures. The approximate locations of the failure surfaces
representing the lowest seismic safety factors determined by our analysis are shown on Figures 3 and 4.
5.3 Site Preparation and Grading
Areas to be prepared for new construction should be stripped of all vegetation, organic surface soils, and other
deleterious materials. Soils containing organic material will not be suitable for use as structural fill but may be
used in nonstructural areas or for landscaping purposes.
Page No. 5
October 15, 1999
Project No. T-4482
The on -site soils generally appear suitable for use as structural fill. However, the sands are fine grained and may
be difficult to compact as structural fill when too wet. The ability to use the on -site soils as structural fill will
depend on their moisture content and the prevailing weather conditions at the time of construction. In addition,
the upper three to four feet of soil is generally dry and will likely need moisture conditioning.
If the moisture content of the on -site soils cannot be maintained near their optimum percentage or if grading
activities will take place during the wet winter or spring months, the owner should be prepared to import wet
weather structural fill. For this purpose, we recommend importing a granular soil that meets the following
grading requirements:
U.S. Sieve Size
Percent Passing
3 inches
100
No. 4
75 maximum
No. 200
5 maximum*
*based on the 3/4-inch fraction
Prior to use, Terra Associates, Inc. should examine and test all materials imported to the site for use as structural
fill.
Structural fill should be placed on a firm subgrade of undisturbed native soil in uniform loose layers not
exceeding 12 inches. It should then be compacted to a minimum of 95 percent of the soil's maximum dry
density, as determined by ASTM Test Designation D-698 (Standard 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.
In nonstructural areas or for backfill in utility trenches below a depth of 4 feet, the degree of compaction could be
reduced to 90 percent.
Fill should not be placed at the top or on the face of the steep slope. Final grades at the top of the slope must
promote surface drainage away from the slope crest.
5.4 Foundations
Spread Footings
New construction may be supported on conventional spread footing foundations bearing on competent native
soils or on structural fills placed above competent native soils, as recommended in the Section 5.3 of this report.
Perimeter foundations should be placed at least 1.5 feet below final exterior grades for frost protection. New
foundations on the northern sides of the building areas should be placed to a depth that results in at least ten feet
of lateral separation between the outer edge of the footing and the face of the slope. Interior foundations can be
constructed at any convenient depth.
Page No. 6
October 15, 1999
Project No. T4482
We recommend designing foundations for a net allowable bearing capacity of 2,500 pounds per square foot (psf).
For short-term loads, such as wind and seismic, a one-third increase in this allowable capacity can be used. For
the anticipated building loads and this bearing pressure applied, building settlements should be negligible.
For designing foundations to resist lateral loads, a friction coefficient of 0.4 can be used. Passive earth pressures
acting on the side of the footing and buried portion of the foundation stem wall can also be considered. We
recommend calculating this lateral resistance using an equivalent fluid weight of 350 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 foundation will be constructed neat
against competent native soil or backfrlled with structural fill as described in Section 5.3 of this report. The
values recommended include a safety factor of 1.5.
5.5 Drainage
Surface
Water must not be allowed to flow uncontrolled over the crest of the steep slope or onto the slope face. Surface
water should be directed away from the slope crest to a point of collection and controlled discharge. If proposed
site grades do not allow for directing surface water away from the slope, then water should be collected and
tightlined to the bottom of the slope in a controlled manner.
Final exterior grades should promote free and positive drainage away from the building area. We recommend
providing a gradient of at least three percent for a minimum distance of ten feet from the building perimeter.
Subsurface
We recommend installing a continuous drain along the outside lower edge of the perimeter building foundations.
The foundation drains and roof downspouts should be tightlined to an approved discharge facility. Subsurface
drains must be laid with a gradient sufficient to promote positive flow to a controlled point of approved
discharge. All drains should be provided with cleanouts at easily accessible locations. These cleanouts should
be serviced at least once every year.
6.0 ADDITIONAL SERVICES
Terra Associates, Inc. should review the final design and specifications to verify that earthwork and foundation
recommendations have been properly interpreted and implemented in project design. We should also provide
geotechnical services during construction to observe compliance with the design concepts, specifications, and
recommendations. This will also allow for design changes if subsurface conditions differ from those anticipated
prior to the start of construction.
Page No. 7
October 15, 1999
Project No. T-4482
7.0 LIMITATIONS
We prepared this report in accordance with generally accepted geotechnical engineering practices. No other
warranty, expressed or implied, is made. This report is the property of Terra Associates, Inc. and is intended for
specific application to the Anderson Additions project in Edmonds, Washington. This report is for the exclusive
use of Billy and Ilona Anderson and their authorized representatives.
The analyses and preliminary recommendations presented in this report are based upon data obtained from the
on -site borings. Variations in soil conditions can occur, the nature and extent of which may not become evident
until construction. If variations appear evident, Terra Associates, Inc. should be requested to re-evaluate the
recommendations in this report prior to proceeding with construction.
Page No. 8
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REFERENCE: THE THOMAS GUIDE, METROPOLITAN PUGET SOUND, PAGE 454, 2000 EDITION.
VICINITY MAP
TERRA ANDERSON ADDITIONS
ASSOCIATES EDMONDS, WASHINGTON
Geotechnical Consultants Proj.No. 4482 Date OCT. 1999 Figure 1
Q
�a
A�
OF 1H EDGE
4 S WIDE
�o -Z CREEK
•
•..TWIN.
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O `4w LAUREL `>
N �� R UP• - - Z PARKING AREA
1
EGE OF A5PFIAL.T ; LOG—
��'� Al) BORDER
' A b� TOP \ 215.91
APPROXIMATE SCALE
30 0 30 60 feet
LEGEND:
APPROXIMATE BORING LOCATION
REFERENCE:
SITE PLAN PREPARED BY ROTH HILL ENGINEERING
PARTNERS, INC., JOB No. 99-459-11, SHEET 1 OF 1,
DATED 07/29/99.
SCALE: I" = 20' (H & V)
SCALE; !" = 20' (H 8t V)
APPENDIX A
FIELD EXPLORATION AND LABORATORY TESTING
Anderson Additions
Edmonds, Washington
On September 8, 1999, we explored subsurface conditions at the site by drilling 2 test borings to a maximum
depth of 31.5 feet below the existing ground surface. Soil samples were collected during drilling using the
Standard Penetration Test (SPT) in general accordance with ASTM Test Designation D-1586. The test boring
locations are shown on Figure 2. The Boring Logs are presented on Figures A-2 and A-3.
An engineering geologist from our office conducted the field exploration, classified the soil conditions
encountered, maintained a log of each test boring, obtained representative soil samples, and observed pertinent
site features. All soil samples were visually classified in accordance with the Unified Soil Classification System
(USCS) described on Figure A-1.
Representative soil samples obtained from the borings were placed in sealed containers and taken to our
laboratory for further examination and testing. Laboratory testing included measuring the moisture content of all
soil samples. In addition, we performed grain size analyses on five of the soil samples, and determined the
Atterberg limits of two soil samples. The results of the moisture content and Atterberg limit analyses are
presented in Appendix A. The results of the grain size analyses are presented in Figures A-4 through A-6.
Project No. T-4482
MAJOR DIVISIONS
LETTER
SYMBOL
TYPICAL DESCRIPTION
Clean
GW
Well -graded gravels, gravel -sand mixtures, little or no
GRAVELS
Gravels
fines.
a,
(less than
GP
Poorly -graded gravels, gravel -sand mixtures, little or
O
ca N
More than
5% fines)
no fines.
(n F5
50% of coarse
fraction is
GM
Silty gravels, gravel -sand -silt mixtures, non -plastic
`
W >
larger than No.
Gravels
with fines
fines.
Z
co �,
E
4 sieve
GC
Clayey gravels, gravel -sand -clay mixtures, plastic fines.
O
0
N
o
SANDS
Clean
Sands
SW
Well -graded sands, gravelly sands, little or no fines.
U) � Z
(less than
SP
Poorly -graded sands or gravelly sands, little or no
c c
<
More than
5 /° fines)
fines.
`�
�'
50% of coarse
O "�
o
fraction is
Sands
SM
Silty sands, sand -silt mixtures, non plastic fines.
U g
smaller than
SC
Clayey sands, sand -clay mixtures, plastic fines.
No. 4 sieve
with fines
ML
Inorganic silts, rock flour, clayey silts with slight
o
SILTS AND
CLAYS
plasticity.
CL
Inorganic clays of low to medium plasticity, (lean clay).
(Do
O (a N
co
E o
Liquid limit is less than 50%
OL
Organic silts and organic clays of low plasticity.
W o Z
Z Lo
W
Q C >)
MH
Inorganic silts, elastic.
0 = 2 U'
SILTS AND
CLAYS
a) co
vi
CH
Inorganic clays of high plasticity, fat clays.
z 0
Liquid limit is greater
than 50%
OH
Organic clays of high plasticity.
HIGHLY ORGANIC SOILS
PT
Peat.
DEFINITION OF TERMS AND SYMBOLS
w
Q
Standard Penetration
Density Resistance in Blows/Foot
T 2" OUTSIDE DIAMETER SPLIT
I
SPOON SAMPLER
0
Very loose
0-4
2.4" INSIDE DIAMETER RING SAMPLER
o
Loose
4-10
OR SHELBY TUBE SAMPLER
Medium dense
10-30
z
Dense
30-50
1 WATER LEVEL (DATE)
<
Very dense
>50
Tr TORVANE READINGS, tsf
Pp PENETROMETER READING, tsf
Standard Penetration
J
Consistency Resistance in Blows/Foot
DID DRY DENSITY, pounds per cubic foot
U
Very soft
0-2
LL LIQUID LIMIT, percent
`o
Soft
2-4
J
Medium stiff
4-8
PI PLASTIC INDEX
Very stiff
6 32
N STANDARD PENETRATION, blows per foot
Hard
>32
UNIFIED SOIL CLASSIFICATION SYSTEM
TERRA
ANDERSON ADDITIONS
ASSOCIATES
EDMONDS, WASHINGTON
Geotechnical Consultants
Proj.
No. T-4482
Date OCT 1999
Figure A-1
Boring
No. B-1
Logged by: JCS
Date: 9/8/99
Approximate Elev. 206
Consistency/
a
(N)
Moisture
Soil Description
Relative
Depth
E
Blows/
Content
Notes
Density
(ft.)
ft.
(%)
Light brown SAND, fine grained, dry (SP)
Very Loose
3
6
With a few fine gravel.
Dry to moist.
Loose
=
7
2
=
Moist.
-------------------------------------------------------
Loose
------------- -
5
6
2
Gray -brown SAND with gravel, fine to
Medium Dense
24
2
medium sand, fine gravel, moist (SP).
Medium Dense
1 0
=
28
3
Becomes fine grained, with occasional
Dense
15
=
32
2
fine gravel.
Dense
20
41
2
Very Dense
25
=
50
6
Gray SILT, moist (ML).
LL=22
Blue -gray SILT and CLAY, moist (CL-ML).
Hard
30
=
85*
13
PI = 6
Gravel in tip of sampler.
Boring terminated at 31.5 feet.
No groundwater.
* Blow counts may not be accurate due to gravel in tip of sampler.
BORING LOG
TERRA
ANDERSON
ADDITIONS
ASSOCIATES
EDMONDS,
WASHINGTON
Geotechnical Consultants
Proj. No. T-4482
Date OCT 1999
Figure A
Boring
No. B-2
Logged by: JCS
Date: 9/8/99
Approximate Elev. 200
Soil Description
Consistency/
Relative
Density
Depth
(ft.)
Q
E
0
(N)
Blows/
ft.
Moisture
Content
(/o)
Notes
Brown SAND, fine to medium grained,
Very Loose
2
5
=
dry (SP) (Appears to be fill based on
topography).
Very Loose
2
7
-------------------------------------------------------
Gray -brown SAND with gravel, fine sand,
fine gravel, moist (SP).
-------------------------------------------------------
---------------------
Loose
---------------------
5
=
9
2
Gray-brown SAND, fine grained, moist
(SP). With occasional fine gravel.
Medium Dense
Medium Dense
1 0
18
14
2
3
=
Medium Dense
15
21
4
-------------------------------------------------------
Gray-brown SAND with gravel, fine sand,
fine to coarse gravel, moist (SP).
---------------------
Dense
20
31
4
Medium Dense
25
=
27
4
Becomes wet.
Dense
30
=
37
15
14
Pp = 3.5 tons/ftz
L = 22
PI = 7
Brown to gray SILT and CLAY, moist
CL-ML . With occasional fine ravel.
Hard
Boring terminated at 31.5 feet.
Wet soils encountered at approximately 30 feet.
BORING
LOG
TERRA
ASSOCIATES
ANDERSON
EDMONDS,
ADDITIONS
WASHINGTON
Geotechnical Consultants
Proj. No. T-4482
Date SEPT 1999
Figure A-3