sheehangeotech.pdfSTREET FILE
GEOTECHNICAL ENGINEERING
EVALUATION
SHEERAN POOL REPAIRS
EDMONDS, WASHINGTON
PREPARED FOR
MR. TOM SHEERAN
RECEIVED
JUN Z 9 2006
DEVELOPMENT SERVICES GTR.
CITY OF EDMONDS
y
�
NGA
17311 —1351h Avenue NE, A-500
Woodinville, WA 98072
IN (425) 486-1669 . (425) Fax 481-2510
July 27, 2405
Mr. Tom Sheehan
14 P.O. Box 1477
Edmonds, Washington 98020
Cl
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NELSON GEOTECHNICAL,
ASSOCIATES, INC.
GEOTECHNICAL ENGINEERS & GEOLOGISTS
Geotechnical Engineering Evaluation
Sheehan Pool Repairs
Edmonds, Washington
NGA File No. 712905
Dear Mr. Sheehan:
Snohomish County (425) 337-1669
WenatcheelChelan (509) 784-2756
We are pleased to submit the attached report titled "Geotechnical Engineering Evaluation -- Sheehan Pool
Repairs, Edmonds, Washington." This report summarizes the existing surface and subsurface conditions
within the project site and provides recommendations for repairing the area around your pool. Our
services were completed in general accordance with the proposal signed by you on May 23, 2005.
The site is currently occupied by one residential structure with a pool on the western side of the residence.
An approximate 6 -foot high block wall is located on the southern and western sides of the pool. The wall
is exhibiting cracking and areas of deflection. The purpose of this study was to explore the conditions
that lead to the wall deterioration and provide recommendations for wall repairs/replacement.
We monitored the drilling of four borings in the vicinity of the pool. Our explorations indicated that the
perimeter of the pool is surrounded with loose fill that in turn is supported by the block wall. The loose
fill is underlain by competent native glacial material. We have concluded that the loose fill is exerting
significant loads on the wall, which have led to the distress observed in the wall. We have also concluded
that this distress will continue if no remedial actions are taken, and may ultimately endanger the pool
itself. We have recommended that the existing wall and loose fill be removed and replaced with
structural fill and a new concrete wall. Care should be taken not to distress the pool during wall
replacement. General recommendations for wall design and construction are provided in this report.
The new wall should be designed by a qualified
qualified contractor. We recommend retaining Mr.
(425-339-0293) to complete the structural design.
structural engineer and the work carried out by a
Chris Covington, PE of Structural Design Associates
Geotechnical Engineering Evaluation
Sheehan Pool Repairs
July 27, 2005
NGA File No. 712905
Summary - Page 2
It has been a pleasure to provide service to you on this project. Please contact us if you have any
questions regarding this report or require further information.
Sincerely,
NELSON GEOTECHNICAL ASSOCIATES, INC.
Khaled M. Shawish, PE
IN Principal
Three Copies Submitted
1:1
4 TABLE OF CONTENTS
INTRODUCTION......................................................................................................................................1
SCOPE.........................................................................................................................................................1
SITECONDITIONS.................................................................................................................................. 2
SurfaceConditions.................................................................................................................................... 2
SubsurfaceConditions.............................................................................................................................. 2
HydrologicConditions...................•......................................................................................................... 3
SENSITIVE AREA EVALUATION.........................................................................................................4
SeismicHazard......................................................................................................................................... 4
ErosionHazard..........................................................................................................................................4
CONCLUSIONS AND RECOMMENDATIONS .....................
INGeneral...................................................................................................................................................... 5
ErosionControl Measures......................................................................................................................... 5
SitePreparation......................................................................................................................................... 6
14
New Retaining Wall Design and Construction......................................................................................... 6
StructuralFill............................................................................................................................................ 9
ConcreteWalkway and Planter................................................................................................................. 9
SiteDrainage........................................................................................................................................... 10
USEOF THIS REPORT..........................................................................................................................1Q
IN LIST OF FIGURES
Figure 1 —Vicinity Map
Figure 2 — Schematic Site Plan
Figure 3 — Soil Classification Chart
Figures 4 through 7 — Boring Logs
NELSON GEOTECHNICAL ASSOCIATES, INC.
t 7
Geotechnical Engineering Evaluation
Sheehan Pool Repairs
Edmonds, Washington
INTRODUCTION
This report presents the results of our geotechnical engineering investigation and evaluation of the distress
in the vicinity of the pool area at the Sheehan residence in Edmonds, Washington. The residence is
located at 18902 — 94"' Avenue West as shown on the Vicinity Map in Figure 1. The pool is located on
the western side of the residence.
The pool is surrounded on the southern and western sides by a masonry block wall up to six feet in height.
This wall has experienced ongoing distress for some time. The wall movement has affected a concrete
14 walkway and brick pavers that surround the pool. The main concern now is that further movement of the
wall might lead to distressing the pool itself, which may lead to a major wall failure. The site layout is
shown on the Schematic Site Plan in Figure 2. The purpose of this study is to explore and characterize
the site's surface and subsurface conditions in the pool vicinity and to provide geotechnical
recommendations for wall and pool area repairs.
SCOPE
The purpose of this study is to explore and characterize the site surface and subsurface conditions, and
provide general recommendations for pool and wall repairs. Specifically, our scope of services includes
the following:
11
1. Review existing soils, and geologic information for this project.
14 2. Explore the site subsurface soil and groundwater conditions with four 13- to 17 -foot
exploratory borings using a limited access portable drill rig. The drill rig was
subcontracted by NGA.
3. Provideeotechnical findings relate
g g d to subsurface soils and groundwater conditions.
4. Perform wall observations, measurements and mapping of existing conditions.
5. Perform laboratory analyses on selected soil samples, as needed.
6. Provide recommendations for site area stabilization, including retaining wall design and
installation.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Sheehan Pool Repairs
.July 27, 2005
NGA File No. 712905
Page 2
7. Provide recommendations for pool stabilization techniques.
8. Provide recommendations for site drainage and erosion control.
9. Document the results of our explorations, findings, conclusions and recommendations in
a written geotechnical report.
SITE CONDITIONS
Surface Conditions
The project area is located to the west of the existing residence and is bounded to the north by a walkway
and pool house, to the south by an access driveway to the neighboring property, to the east by the
residence, and to the west by a driveway pull-out for the neighboring house. The site layout is shown on
the Schematic Site Plan in Figure 2.
The pool is rectangular in shape with dimensions of roughly 37 feet in the east -west direction and 15.5
feet in the north -south direction. A one -foot wide outline of bricks was observed along all sides of the
14 pool. A concrete walkway approximately two feet wide was observed along the south and west sides of
the pool. Concrete slabs also extended from the residence on the east side of the pool to a maximum
distance of 12 feet. A concrete patio with a pool house bordered the pool along the north side. Young
deciduous trees and plants were observed along the southern and western portions of the pool. A concrete
block wall surrounded the pool area on the southern and western sides below the planter strip. We
observed that the existing concrete block wall appears to be bowed outward in several locations, including
cracking and breaking of some of the blocks. On the south side, the wall increases in height from 4.9 feet
on the southeast corner to 6.0 feet on the southwest corner. The height of the western wall is 6.0 feet. A
4 -foot, wood fence was observed along the top of the wall. We did not observe water seepage from the
wall during our visits on June 7 and 8, 2005.
Subsurface Conditions
Geology: The Geologic Map of the Edmonds East and _Part of the Edmonds West Quadrangles,
Washington, by James P. Minard (U.S.G.S., 1983) was referenced for the geologic conditions at the site.
The site is mapped as.. Till (Qvt). This unit is described as a non -sorted mixture of clay, silt, sand, and
gravel. Our explorations generally encountered silty sand with gravel consistent with the description of
the Till.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Sheehan Pool Repairs
July 27, 2005
NGA File No. 712905
Page 3
Explorations: The subsurface conditions within the site were explored on June 7 and 8, 2005 by drilling
four borings to depths ranging from 13.0 to 17.2 feet below the existing surface using a portable drill rig.
The approximate locations of our explorations are shown on Figure 2.
An engineer from NGA was present during the explorations, examined the soils and geologic conditions
encountered, obtained samples of the different soil types, and maintained logs of the explorations. A
Standard Penetration Test (SPT) was performed on each of the samples during drilling to document soil
density at depth. The SPT consists of driving a 2 -inch outer -diameter, split -spoon sampler 18 inches
using a 140 -pound hammer with a drop of 30 inches. The number of blows required to drive the sampler
the final 12 inches is referred to as the "N" value and is presented on the boring logs. The N value is used
to evaluate the strength and density of the deposit.
The soils were visually classified in general accordance with the Unified Soil Classification System,
presented in Figure 3. The logs of our borings are attached to this report and are presented as Figures 4
through 7. We present a brief summary of the subsurface conditions in the following paragraph. For a
detailed description of the subsurface conditions, the boring logs should be reviewed.
In Boring 1, we encountered approximately 18 inches of topsoil underlain by approximately four feet of
loose, dark brown to grayish brown fine to medium sand, interpreted to be fill. Below the sand, we
encountered very dense, brownish -gray, silty fine to medium sand with gravel. This soil was interpreted
to be glacial till.
In Borings 2 through 4, below the 4- to 7 -inch thick concrete slab, we encountered 9.0 to 12.0 feet of very
loose to medium dense, brownish -gray to black, silty fine to medium sand with gravel. This soil was also
interpreted as fill. Below the fill, we encountered very dense, brownish -gray, silty fine to medium sand
with gravel, and interpreted this material to be till. All borings were terminated in the glacial till.
Hydrologic Conditions
Slight groundwater seepage was encountered in Borings 2, 3, and 4 at depths ranging from five to ten feet
below the existing ground surface. It is our opinion that this seepage is perched water. Perched water
occurs when surface water infiltrates through less dense, more permeable soils such as the fill and topsoil,
and accumulates on top of a relatively impermeable material such as the underlying silty sand. Perched
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Sheehan Pool Repairs
July 27, 2005
NGA File No. 712905
Page 4
water does not represent a regional groundwater "table" within the upper soil horizons. Perched water
tends to vary spatially and is dependent upon the amount of rainfall. We would expect the amount of any
groundwater to decrease during drier times of the year and increase during wetter periods.
Although no evidence of pool cracking was observed, the observed water seepage could have originated
14 from the pool. We recommend that the pool be thoroughly inspected for cracking and repaired as needed,
14 as part of the planned improvements.
SENSITIVE AREA EVALUATION
Seismic Hazard
Medium dense to very dense glacial soils were encountered underlying the site. Based on the 2003
International Building Code (IBC), the site conditions best fit the description for Site Class D.
Hazards associated with seismic activity include liquefaction potential and amplification of ground
motion by soft deposits. Liquefaction is caused by a rise in pore pressures in a loose, fine sand deposit
beneath the groundwater table. The medium dense to dense glacial material interpreted to underlie the
site has a Iow potential for liquefaction or amplification of ground motion.
Erosion Hazard
The erosion hazard criteria used for determination of affected areas includes soil type, slope gradient,
vegetation cover, and groundwater conditions. The erosion sensitivity is related to vegetative cover and
the specific surface soil types, which are related to the underlying geologic soil units. The Soil Survey,
Snohomish County Area, Washington, by the Soil Conservation Service (SCS) was reviewed to
determine the erosion hazard of the on-site soils. The site surface soils were classified using the SCS
classification system as Alderwood gravelly sandy loam, 15 to 25 percent slopes. This unit is listed as
having a moderate erosion hazard. We would expect that the loose fill that exists behind the wall would
have a high erosion potential when the wall is removed.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Sheehan Pool Repairs
July 27, 2005
NGA File No. 712905
Page 5
CONCLUSIONS AND RECOMMENDATIONS
General
Based on our observations and exploration data, it is our opinion that the block wall that surrounds the
pool and the southern and western sides is currently marginally stable. It is our opinion that cracking of
the blocks and deflection of the wall will continue to occur, and wall stability will become even more
marginal. If the wall fails and there is a breach in the swimming pool, damage to the neighboring
property and adjacent slope may result.
We recommend that the block wall and the loose fill behind the wall be removed and replaced with an
engineered wall and structural fill, to mitigate the ongoing wall and fill movement and to reduce the
potential for pool distress and catastrophic failure. We should note that although the pool does not show
signs of cracking or leaking, it should be thoroughly inspected and repaired as part of the overall
improvements planned on this site.
Approximately seven to eight feet of fill was encountered in the borings underlain by very dense glacial
till. The native glacial till should provide adequate support for a new wall. We recommend that the water
be drained from the pool prior to removing the wall and fill. The block wall and backfill should be
carefully removed and the exposed pool braced to reduce pool distress during construction. Once the
existing wall and fill are removed and the subgrade is prepared as recommended in this report, the new
wall and backfill should be placed. The wall and backfilled should be placed as recommended in this
report. Also, ample drainage systems should be installed behind the wall and around the pool, and
tightlined to an appropriate discharge location.
The soils that are expected to be encountered during site development are considered moisture -sensitive
IN and can disturb and erode in wet conditions. We recommend that the repairs be carried out during dry
weather, if possible. If construction takes place during wet weather, additional expenses and delays
IN related to material handling and erosion control should be expected.
4 Erosion Control Measures
Best Management Practices (BMPs) should be used to control erosion. Areas disturbed during
construction should be protected from erosion. Measures taken may include diverting surface water away
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Sheehan Pool Repairs
July 27, ZppS
NGA File No. 712905
Page 6
from the stripped areas. Silt fences and/or straw bales should be erected to prevent muddy water from
leaving the site. The erosion potential of areas not disturbed should be low.
Site Preparation
After the water is drained from the pool, and the railing and landscaping have been removed, we
recommend that the block wall and the fill be removed simultaneously. The pool should be braced while
the fill is being removed to reduce the potential for pool distress. The excavated material should be
- hauled off-site. We anticipate that dense glacial till will be exposed in the new wall subgrade. If the
ground surface, after excavating down to planned subgrade elevations appears to be loose, it should be
compacted to a non -yielding condition. Areas observed to pump or weave during subgrade compaction
should be reworked to structural fill specifications or over -excavated and replaced with properly
compacted structural fill or crushed rock.
If significant surface water flow is encountered during excavation, this flow should be collected in small
sump and pump pits and pumped out of the excavation. The exposed subgrade should not be compacted
in wet conditions, as compaction of a wet subgrade may result in further disturbance of the native soils.
Instead, a layer of crushed rock or all-weather material may be placed over the prepared areas for
protection from further disturbance.
As mentioned earlier, the site soils are considered highly moisture sensitive and can disturb when wet.
- We therefore recommend that construction take place during a period of extended dry weather, and
suspended during rainfall. If work is to take place during the wetter part of the year, care should be taken
during site preparation not to disturb the exposed subgrade. This can be accomplished by utilizing an
excavator equipped with a smooth bucket for site grading, and diverting surface and, groundwater flow
away from the prepared subgrades. Also, construction traffic should not be allowed on the exposed
IN subgrade.
New Retaining Wall Design and Construction
Lateral Loads: An approximately 6 -foot high concrete retaining wall will be constructed after the
existing wall is. removed. The new wall will provide support for the fill to be placed between the new
wall and the pool, which in turn will support the pool itself.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Sheehan Pool Repairs
July 27, 2005
NGA File No. 712905
Page 7
The lateral pressure acting on retaining walls is dependent on the nature and density of the soil behind the
wall, the amount.of lateral wall movement which can occur as backfill is placed, wall drainage conditions,
and the inclination of the backfill. For walls that are free to yield at the top at least one thousandth of the
height of the wall (active condition), soil pressures will be less than if movement is limited by such
factors as wall stiffness or bracing (at -rest condition). We recommend that the new wall be designed
using a triangular earth pressure distribution equivalent to that exerted by a fluid with a density of 45 pcf
for yielding (active) condition, and 65 pcf for non -yielding (at -rest) condition.
These recommended lateral earth pressures are for a drained granular backfill and are based on the
assumption that the loading conditions behind the new wall will be similar to the current conditions.
Additional lateral earth pressures should be considered for surcharge loads acting adjacent to the wall and
within a distance equal to the subsurface height of the wall. This would include the effects of surcharges
such as slab or foundation loads or other surface loads. We could consult with you and your structural
engineer regarding additional loads on retaining wails during final design, if needed.
The lateral pressures on the wall may be resisted by friction between the wall base and subgrade soil, and
by passive resistance acting on the below -grade portion of the foundation. A coefficient of friction of
0.35 may be used to calculate the base friction and should be applied to the vertical dead load only.
Passive resistance may be calculated as a triangular equivalent fluid pressure distribution. An equivalent
fluid density of 250 pcf should be used for passive resistance design for a level ground surface adjacent to
the footing. This level surface should extend a distance equal to at least three times the footing depth.
These recommended values incorporate safety factors of '1.5 and 2.0 applied to the estimated ultimate
values for frictional and passive resistance, respectively. To achieve this value of passive resistance, the
wall footing should be poured "neat" against the native medium dense soils or compacted fill should be
used as backfill against the front of the footing. We recommend that the upper one -foot of soil be
neglected when calculating the passive resistance.
Wall Backfill and Drainage: All wall backfill should be well compacted as outlined in the Structural
Fill subsection of this report. Care should be taken to prevent the buildup of excess lateral soil pressures,
due to over -compaction of the wall backfill. This can be accomplished by placing wall backfill in eight -
inch loose lifts and compacting the backfill with small, hand -operated compactors within a distance
behind the wall equal to at least one-half the height of the wall. The thickness of the loose lifts should be
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Sheehan Pool Repairs
July 27, 2005
NGA File No. 712905
Page 8
lessened to accommodate the lower compactive energy of the hand -operated equipment. The
recommended level of compaction should still be maintained.
Permanent drainage systems should be installed behind the wall and around the pool. Recommendations
for these systems are found in the Site Drainage subsection of this report. We recommend that we be
retained to evaluate the proposed wall drains and backfill material, and observe installation of the
drainage systems.
Wall Foundations. The wall foundation should be placed on undisturbed medium dense or better native
soils or be supported on structural fill or rock spalls extending to those soils. Where less dense soils are
encountered at footing bearing elevation, the subgrade should be over -excavated to expose suitable
bearing soil. The over -excavation may be filled with structural fill or footing concrete cast directly on the
native subgrade. If footings are supported on structural fill, the fill zone should extend outside the edges
of the footings a distance equal to one-half of the depth of the over -excavation below the bottom of the
footings.
Wall footings should extend at least 18 inches below the lowest adjacent finished ground surface for frost
protection and bearing capacity considerations. Standing water should not be allowed to accumulate on
the foundation subgrade. All loose or disturbed soil should be removed from the foundation excavation
prior to placing concrete.
For wall foundations constructed as outlined above, we recommend an allowable design bearing pressure
of not more than 3,000 pounds per square foot (psf) be used for the footing design for a minimum of a-
foot wide wall footing founded on the dense or better glacial soils or structural fill extending to the native
competent material. The foundation bearing soil should be evaluated by a representative of our firm. We
should be consulted if higher bearing pressures are needed. Current IBC guidelines should be used when
considering increased allowable bearing pressure for short-term transitory wind or seismic loads.
Potential foundation settlement using the recommended allowable bearing pressure is estimated to be less
than one inch total and 112 inch differential between adjacent footings or across a distance of about 20
feet, based on our experience with similar projects.
` NELSON GEOTECHNICAL ASSOCIATES, INC.
If
Geotechnical Engineering Evaluation
Sheehan Pool Repairs
July 27, 2005
NGA File No. 712905
Page 9
Structural Fill
General: Fill placed behind the wall should be placed as structural fill. Structural fill, by definition, is
placed in accordance with prescribed methods and standards, and is monitored by an experienced
geotechnical professional or soils technician. Field monitoring procedures would include the
performance of a representative number of in-place density tests to document the attainment of the
desired degree of relative compaction. The area to receive the fill should be suitably prepared as
described in the Site Preparation and Grading subsection prior to beginning fill placement.
Materials: Structural fill should consist of a good quality, granular soil, free of organics and other
deleterious material and be well graded to a maximum size of about three inches. All-weather fill should
contain no more than five -percent fines (soil finer than U.S. No. 200 sieve, based on that fraction passing
the U.S. 314 -inch sieve). The use of the on-site soils as structural fill is not recommended. We
recommend that imported clean pit run or 2 -inch crushed rock be used as wall backfill. We should be
retained to evaluate proposed structural fill material prior to construction.
Fill Placement: Following subgrade preparation, placement of structural fill may proceed. All filling
should be accomplished in uniform lifts up to eight inches thick. Each lift should be spread evenly and be
thoroughly compacted prior to placement of subsequent lifts. All structural fill should be compacted to a
minimum of 95 percent of its maximum dry density. Maximum dry density, in this report, refers to that
density as determined by the ASTM D-1557 Compaction Test procedure. The moisture content of the
soils to be compacted should be within about two percent of optimum so that a readily compactable
condition exists. It may be necessary to over -excavate and remove wet soils in cases where drying to a
compactable condition is not feasible. All compaction should be accomplished by equipment of a type
and size sufficient to attain the desired degree of compaction.
Concrete Walkivay and Planter
The concrete walkway could be supported directly on the compacted wall backfill. If the planter is to be
restored along the top of the wall, we recommend that the wall be backfilled to within a foot to 18 inches
from finished grade and the wall backfill covered with a layer of filter fabric in the area of the planter.
Once the concrete walkway is cast, the planter strip could be filled with a topsoil mix to facilitate
vegetation growth. Irrigation lines placed in the planter should have an automatic shutoff to reduce the
potential of system failures to flood the wall and increase hydrostatic loads on the wall.
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Sheehan Pool Repairs
July 27, 2005
NGA File No. 712905
Page 10
Site Drainage
We recommend. that the existing surficial drains around the residence be evaluated for proper
functionality and repaired as needed. Additional surficial drains may be utilized to collect surface water
and divert it away from the new improvements.
We recommend the use of subsurface drains behind the wail and around the pool. The drains should be
installed at least six inches below planned subgrade elevation. The drains should consist of a minimum
four -inch -diameter, rigid, slotted or perforated, PVC pipe surrounded by free -draining material wrapped
in a filter fabric. We recommend that the free -draining material consist of an 18 -inch -wide zone of clean
(less than three -percent fines), granular material placed along the back of wails. Pea gravel is an
acceptable drain material or drainage composite may also be used instead. The free -draining material
should extend up the wall to one to two feet below the finished surface. The top two feet of soil should
consist of impermeable soil or topsoil placed over plastic sheeting to minimize surface water or fines or
root migration into the drainage material. Drains should discharge into tightlines leading to an
appropriate collection and discharge point. Surface drains should not be connected to subsurface drains
or terminate behind the wall or pool. We should be retained to review plans for the drainage systems.
USE OF THIS REPORT
v NGA has prepared this report for Mr. Tom Sheehan and his agents for use in the feasibility planning and
budgeting of the development planned on this site only. The scope of our work does not include services
related to construction safety precautions and our recommendations are not intended to direct the
contractors' methods, techniques, sequences, or procedures, except as specifically described in our report
for consideration in design. There are possible variations in subsurface conditions between the
explorations and also with time. Our report, conclusions, and interpretations should not be construed as a
warranty of subsurface conditions. A contingency for unanticipated conditions should be included in the
budget and schedule.
We recommend that NGA be retained to review final project plans. We also recommend that NGA be
retained to provide monitoring and consultation services during construction to confirm that the
conditions encountered are consistent with those indicated by the explorations, to provide
recommendations for design changes should the conditions revealed during the work differ from those
anticipated, and to evaluate whether or not earthwork and foundation installation activities comply with
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Sheehan Pool Repairs
July 27, 2005
NGA File No. 712905
Page 11
contract plans and specifications. We should be contacted a minimum of one week prior to construction
activities and could attend pre -construction meetings if requested.
Within the limitations of scope, schedule, and budget, our services have been performed in accordance
with generally accepted geotechnical engineering practices in effect in this area at the time this report was
prepared. No other warranty, expressed or implied, is made. Our observations, findings, and opinions are
a means to identify and reduce the inherent risks to the owner.
. • .
NELSON GEOTECHNICAL ASSOCIATES, INC.
Geotechnical Engineering Evaluation
Sheehan Pool Repairs
July 27, 2005
NGA File No. 712905
Page 12
It has been a pleasure to provide service to you on this project. If you have any questions or require
further information, please call.
Sincerely,
NELSON GEOTECHNICAL ASSOCIATES, INC.
Bala Dodoye-Alali((//
Project Geologist{:
EXPIRES
Khaled M. Shawish, PE
Principal
ADH:BD:KMS:Iam
Seven Figures Attached
NELSON GEOTECHNICAL ASSOCIATES, INC.
Project
Site
Edmonds
v.02000 Thomas Bros. M
NOT TO SCALE
NELSON GEOTECHNICAL, No. I Date Revision By I CK
Sheehan Residence Pool NGA ASSOCIATES, INC. 1 mros original ACO ADH
GEOTECHNICAL ENGINEERS & GEOLOGISTS
Vicinity Map 17311•138+h AW.NEA388 aminmtYi Ce sntyi"' 337.,888
Block Wall
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Above -ground deck
LEGEND
B-1
Number and Approximate
Location of Boring
0
10 20
Reference: Site Plan based on field measurements using a 100 -ft tape measure. Approximate Scale: 1 inch = 10 feet
Project Number
NELSON GEOTECHNICAL
No.
Date
Revision
By
CK
712905
Sheehan Residence Pool
-'-'NGA ASSOCIATES, INC.
1
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Figure 2
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GEOT£CHN[CAL ENGINEERS & GEOLOI
Figure 3 Soil Classification 47317-135p,AvaW@,A60°
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MAJOR DIVISIONS
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GROUP
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GROUP NAME
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SYMBOL
COARSE- GRAVEL
CLEAN
GW
WELL -GRADED, FINE TO COARSE GRAVEL
GRAVEL.
GP
POORLY -GRADED GRAVEL
GRAINED
MORE THAN 50
OF COARSE FRACTION
GRAVEL
GM
SILTY GRAVEL
RETAINED
SOILS nio 4 sly ON
WITH FINES
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CLAYEY GRAVEL
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WELL -GRADED SAND, FINE TO COARSE SAND
SAND
MORE THAN 50 %
SP
POORLY GRADED SAND
RETAINED ON MORE THAN 50 %
NO. 200 SIEVE OF COARSE FRACTION
PASSES NO. 4 SIEVE
SAND
SM
51LTY SAND
WITH FINES
SC
CLAYEY SAND
FINE - SILT AND CLAY
ML
SILT
ENORGANIC
GRAINED LIQUID LIMIT
CL
CLAY
LESS THAN 50 %
SOILS
ORGANIC
OL
ORGANIC SILT, ORGANIC CLAY
SILT AND CLAY
MH
SILT OF HIGH PLASTICITY, ELASTIC SILT
MORE THAN 50 %
INORGANIC
PASSES LIQUID LIMIT
N0.200 SIEVE
CH
CLAY OF HIGH PLASTICITY, FLAT CLAY
50 % OR MORE
ORGANIC
OH
ORGANIC CLAY, ORGANIC SILT
HIGHLY ORGANIC SOILS
PT
t
PEAT
NOTES:
1) Field classification is based on visual
examination of soil In general
SOIL MOISTURE MODIFIERS:
accordance with ASTM D 2488-93.
Dry - Absence of moisture, dusty, dry to
t
2) SoIE classiflcatlon using laboratory tests
the touch
is based on ASTM D 2488-93.
Moist - Damp, but no visible water.
!
3) Descriptions of Boll density or
Wet - Visible free water or saturated,
consistency are based on
usually soil is obtained from
Interpretation of blowcount data,
below water table
visual appearance of soils, and/or
test data.
jeCt Number NELSON GEoTecHN
712905 Sheehan Residence PoolN�A ASSOCIATES, IN(
GEOT£CHN[CAL ENGINEERS & GEOLOI
Figure 3 Soil Classification 47317-135p,AvaW@,A60°
wAesm2
_ {428f.18B.1wtA 1 F.vta�.v..n
[CAL
No.
bate
Revision
By
1 CK
1
8130105
Orfglft
ACO
BAD
N5TB
5
'a -27W
a
Boring B-1
C
i
-ii
Approximate Ground Surface Elevation:
Sail Profile
Sample Data
Penetration Resistanoe
�
(Blowslfnat - �)
°c°
Piezometer
10 20 30 40 50 50
I't
Installation -
oDescription
c
1
Q B
0
m
E�
$
Ground
Moisture Content
(Percent -10
ch
Data
10 20 30 40 50 50+
0
Dark brown, silty fine to medium sand (loose, moist)
5
0
(Topsoil)
_------------------------------
Brownist ray, silty fine to medium sand with trace gravel
---
(very loose to loose, moist) U
4
,
5
5
5
Grayish -brown, silty fine to medium sand with gravel
8
'
(loose, moist) (Fill)
SM
Grayish -brown, silty fine to medium sand with trace gravel
55
'
(very dense, moist)
10
Grayish -brown, silty fine to medium sand
5016"
■1p
10
(very dense, moist)
50!5.5"
Boring was completed at 13.0 feet on 617105.
Groundwater seepage was not encountered during
15
drilling.
15
15
20
20
20
25
25
25
LEGEND Solid PVC Pipe Concrete M Moisture Content Lab Test
Depth Driven and Amount Recovered Bentonite G Grain -size Analysis ;
with 2 -inch O.D. Split -Spoon Sampler Slotted PVC Pipe Native Soil Til Torvane Reading, tons/ft
�c Liquid Limit
Monument/ Cap] Silica Sand PP Pocket Penetrometer Reading, tons/ft r
+ .Plastic Limit � to Piezometer = Water Level P Sample Pushed
"
NOTE: The strati icatian Ilnea represent the approximate boundaries between soll types and the transltlgn may be gradual `c
Project Number
NELSON GEOTECHNICAL
No.
Date
Revision
By
c
CK t
712905
Sheehan Residence Pool
tyGA AsSOCIATES, INC.
Boring Log
GEOTECHNICAL ENGINEERS Sc GEOLOGISTS
17311-1361h Ave. NE, A4= 9aehemhh Ceuny 4 S1% -lase
wen,aa,earcheen�6oa 7mmzr66
t
sraaros
fl�irw
Aoo
eao
a`
r
=
Figure 4
pono 1 nF
■ I®
Boring B-2
Approximate Ground Surface Elevation:
Soil Profile
Sample Data
Penetration Resistance
(Blows/foot - 0)
Piezometer
LL
10 2Q 30 40 50 50
F
� c
Installation -
�
n
Description
Q
_
3 g
� �
Q
0
Moisture Content
(Percent - 0)
Ground
Water
cn
Lo
Data
-'
10 20 30 40 50 504
0
0 -
inches of ConchRe
1
Light Grayish -brown, silty fine to medium sand
(very loose, moist) (Topsoil)
------------------------------
Brownish -gray, silty fine to medium sand
(very loose, moist) (F
2
5
5
1
5 -
Grayish -brown, silty fine to medium sand
.77,
SM
2
(very loose, moist to wet) (Fill)
Grayish -brown, silty fine to medium sand with gravel
(loose to medium dense, moist to wet) U
_
10
10
--- ---------------------------
Grayh-brown, silty fine to medium sand with gravel
-�-
—
-_
10 -
(very dense, moist)
65
'10
SM
5015.5"
■
41
15
5015"
N15
15 --
Boring was completed at 15.5 feet on 617105.
Groundwater seepage was encountered frrom 5.0 to 8.5
feet during drilling.
20
20
20-
Q-25
25
25
25-
5•-LEGEND
LEGEND
Solid PVC Pipe Concrete
M Moisture Content Lab Test
Depth Driven and Amount Recovered
%': Bentonite
G Grain -size Analysis
with 2 -Inch O.D. Split -Spoon Sampler -
Slatted PVC Pipet' Native Soil
TV Torvane Reading, tons/ft
is
Liquid Limit
Monument/
Cap Q Silica Sand
PP Pocket Penetrometer Reading, tonslft
+
Plastic Limit to Piezometer 1 Water Level
P Sample Pushed
NOTE: The stratiticadon Ilnes represent the approximate boundaries between Boll types
and the transition may be gradual.
Project Number
NELSON GEOTECHNICAL
No.
gate
Revision
By
CK
712905
Sheehan Residence Pool
ASSOCIATES, INC.
—___NGA
I
Mao;,
origrnai
ACO
eao
Figure 5
Boring Log
GEOTECHNICAL ENGINEERS
& GEOLOGISTS
17311A351h A",N%.A,W0
X10
9noMmbl,Comy[i2L)397-�H69
Wane CMkn 609}7642768
Page 1 of 1
i425IMBAMIF
U
C
i
Boring B-3
a
i
c
F Approximate Ground Surface Elevation: �
ISoil
Profile
Sample Data
Penetration Resistance
Piezometer
(Blows/foot - ID)
Z,
LL
10 20 30 40 50 50+
2 m
Installation -
a
Description
r
$'
_
O
Q E
>
O 0
m
o.
E
ld lT
Ground
Water
Moisture Content
(Percent
o
0
�°�
to
- E)
Data
10 20 30 40 50 50
0
8 inches of Concrete
0
7
Brown, silty fine to medium sand (very loose, moist) U
hark 'brown—to'
rownto black, silty fine to medium sand with gravel
(very loose, moist) U
3
5
Grayish -brown, silty fine to medium sand
5
1 5
(very loose, moist to wet) (Fill)
2
SM
-becomes dark brown to reddish brown
_
4
10
10
10
3
Grayish -brawn, silty fine to medium sand with gravel
5016,
■
(very dense, moist)
15
SM
5013,5"
E 1
15
5012"
Boring was completed at 17.2 feet on 6/7105.
Groundwater seepage was encountered frrom 5.0 to 12.0
feet during drilling.
20
20
20
25
25
25
LEGEND �.,
Solid PVC Pipe � Concrete M Moisture Content Lab Test
Depth Driven and Amount Recovered$
- Bentonite G Grain -size Analysis
m
with 2 -inch O.D. Split -Spoon Sampler Slotted PVC Pipe M
Native Soil TV Torvane Reading, tons/it
�Ir Liquid Limit
Monument/ Cap] Silica Sand Pocket Penetrometer Reading,
1� PP tonslft t
+ Plastic Limit to Piezometer = Water Level P Sample Pushed
NOTE: The atratillcatlon lines represent the approximate boundaries between loll types and the trensltbn may he gradual. S
Project Number
Nl~LsoN GEOTECHNICAL
No.
Date
Revision
By
CK 1
712905
Sheehan Residence Pool
NGA ASSOCIATES, INC.
S
Baring Log
GEOYrCHNICAL ENGINEERS & GEOLOGISTS
17911-136tMe. NE,Ab00 SrwMmish Cwnly 17E 337-1088
(475 ;= 610 W�., 's`„z7�6
1
&-Ams
otlw
ACO
13AD
O
6
Figure 6
Page 1 of 1
V
c
'C
u
Boring B-4 `
Approximate Ground Surface Elevation:
Soil Profile
Sample Data
Penetration Resistance
(Blows/foot- 0)
Piezometer
10 2fl 30 fl 50 50
o �+
c
Installation -
tnor-
a S1
_
CL
$ t-
Ground
Water
Moisture Content
n
Description
12
Q E
o
m 0
E
I (Percent -
Data
cn
n
10 20 30 40 50 50+
0
6 inches of concrete
0
—
Dark brown, silty fine to medium sand with gravel
13
(medium dense, moist) (Fill)
Dark brown, silty fine to medium sand (loose, moist)Fill
5
5
Dark brown to reddish brown, silty fine to medium sand
5
5
with gravel (very loose to loose, moist) U
SM
5
3
10
Light brown to reddish brown, silty fine to medium
10
= 10
sand(loose to medium dense, moist to wet) U
10
Grayish brown, silty fine to medium sand
5015"
(very dense, moist)
Grayish-brown to reddish brown, silty fine to medium sand
15
with gravel (very dense, moist)
SM
50/3"
X15
15
sofa,
Boring was completed at 17.2 feet on 617105.
Groundwater seepage was encountered frrom 10.0 to
12.0 feet during drilling.
20
20
1
1
1
20-
-25
25
25
LEGEND Solid PVC Pipe Concrete M Moisture Content Lab Test
Depth Drivers and Amount Recovered `: Bentonite G Grain-size Analysis
with 2-inch O.D. Split-Spoon Sampler Slotted PVC Pipet Native Soil TV Torvane Reading, tons/ft
7k Liquid Limn -
Monument/ Cap Q Silica Sand PP Pocket Penetrometer Reading, tons/ft
} Plastic Limit to Piezometer = Water Level P Sample Pushed
NOTE: The stratification fines,represent the approximate boundaries between sail types and the transition may be gradual.
Project Number
NELSON GEOTECHNICAL
No.
Date
Revision
By
CK
Sheehan Residence PDOI
ASSOCIATES, INC.
712985
Boring Log
GEOTECHNICAL ENGINEERS & GrOLOGISTS
t7311.136th Aw. NE,MG66 3,oMmLh CeuMy {I75 337-7688
(476)4N-1 91ftK44a12670 7be
wam5
o�iral
n00
BPD
Figure 7
Page 1 of 1