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SWP-27-2800
Tamoron Pointe
Geotechnical Study
June 1998
( Copy from Consultant May 2005)
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SWP-27-2800
Tamoron Pointe
Geotechnical Study
J u ne 1998
( Copy from Consultant May 2005)
From: "Collin Barrett" <CollinBarrett@paceng.com>
To: <dcarey@ci.renton.wa.us>
Date: 05/25/2005 4:32:57 PM
Subject: Tamaron Pointe Geotechnical Study
Mr. Carey,
Here is the Geotechnical Study per your request.
Regards,
Coilin Barrett
Pacific Engineering Design LLC
cbarrett@paceng.com
Phone (425) 251-8811
Fax (425) 251 8880
CC: "Jayna Paradise" <jayna@paceng.com>, "Darrin Sanford" <dsanford@paceng.com>
From: "Jayna Paradise" <jayna@paceng.com>
To: <Dcarey@ci.renton.wa.us>
Date: 05/27/2005 12:02 02 PM
Subject: Tamaron Pointe
Daniel:
Attached per you request are the boring log plates 2-14 for the Tamaron
Pointe project.
Thank you,
Jayna Paradise
Pacific Engineering Design, LLC
4180 Lind Avenue SW
Renton, WA 98055
(425) 251-8811 phone
(425) 251-8880 fax
uvuvw.paceng.com
CC: Dar���:n, Sanfor��" <dsa^ford����acera c�__._
j � �� u� : ��p (4Z5 ) 747-9561 p . 2
GEOTECHNICAL ENGINEERING STUOY
Prop�sed Tart�aron Pointe Apartmen;s
2100 Lake Washington Boulevarci
Renton, Washington
This report presents the findings and recommendations of our geotechnical er�g�neering study for
the site of the proposed apartm�nt complex in Renton. The Vicinity Map, Piate 1, illustrates the
generai location �f the site.
We wcrc provided with a grading plan dated April 15, 1998 and develaped by Pacific Engineering
Design. A copy of the Land Title Survey prEpared by Hallin and Associates, and ctated June 5,
1998 was aiso provided. The plans illustrated property boundaries, existing topography, and the
ioCations and finish #Ioor elevatior7s for the planned buslcEings. E3ased on this information, we '
anticipate that the existing mobile homes v+�il) be removed, and 15 apa�tment buildings will be
constructed on the site. The two existing accesses off Lake Washington Boulevard will be
mairrtained. Several of the buiidings are shown to be situated close to the crest of steep slopes
that are located along the north and west sides of the property_ Buildings 2, 4, and 6 are indicated
to be 20 to 30 feet from the toe of steep cut slopes that exist on the eastem side of the site.
Farther north, carports and paved areas abut the toes of these steep, eastern slopes.
SITE CONDITtONS
Sutface �
The site is a large, irregularly-shaped parcel siEuated immecliately east of LaEce Washingtan
Boulevard, near Coulon Park in Renton. Currently develv{�ed with the Lake Terrace mobiie home
park, the property is occupied by numerous mobile hornes, and several wood-framed structures.
Each of the homes has a small paved parkin� strip accessed from the asphalt drives that extend
through the property. In many locations the asphalt drives have broken up or have experienced
noticeable settlement_ The remainder of the site is covered with grass, landscaping, or gravel.
8ased on our observations, the site has undergone extensive grading, likefy associated with its
development for a mobile home park_ The ground surface oves the majority of the site slopes
gently tQ moderatefy down toward t�i� southwest. Along the westem and northem sides of the
site are steep slopes having inclinations of 50 to 70 percent. Generally, the westem slopes, which
extend down to the ditch along �ake Washington Boulevard, increase in height from south to
north. The maximurn height of the westem slopes is 30 feet. The steep, northern slope has a
height of up to approximately 20 feet. There are some shor�, steep slopes in the centraf portion of
the site. Along the east side of the site are very steep cut slopes. These siopes have heights of
up to 40 feet and are near-vertical in places.
During our site visits we observeci a small landslide that had QC2Vi0USIy OCCIirrQc� �n the steep,
western slope, near the proposed Building 5. This sfide had apparently occurred as a shallow 'i
slump that affected only the upper approximately 2 feet of soil on the slope. '
Single-f�mily homes are located north of the site_ To the south and southeast is tne Marina �
Village apartment complex. _ �
D ° s � � '
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Subsurface
The subsurface conditions were explored by drilling 12 test borings at the approxin�ate locations
shown on the Site Exploration PEan, Plaie 2. The field exploration program was based upon the
proposed canstruction and required design criteria, the site topography and access, trze
subsurface conditions rev�aled du�ing drilling, and the scope c�= �vorn o��'i���r�r�: �n «�;r pr_�F%��-�:_
Bonngs 1 through 8 were drilled on May 14, 1998, while Bc,-:rgs �<,a thr.�u.;!� ���:_ ��vere d��:l���� ��;n J..��^�
9, 1998. These borings were conducted using a truck-mounted, hollow-stem auger drill. Samples
were taken at 5-foot interva{s with a standard penetration sarnpier. This sp�it-spoon sampler.
which has a 2-inch outsicie diameter, is driven into the soii with a 140-pound hammet falling 30
inches. The number of blows required to advance the sampler a given distance is an indication o`
the soil densfty or consistency. A geotechnical engineer from our staff observed the driliing
process, logged the test borings, and obtained representative samples of the soil encounterec
The Test Boring Logs are attachQd as Plates 3 thraugh 14.
The native soils that underlie the site conslst of silty s�r�ds containing varying amounts of gravel.
Where the original topsoil was still in place, the underlying native sands were loose for a depth of
several feet. Below this, the soifs were dense to very dense, and relatively unweathered. These
competent soils have been glacially-compressed. The gradatian of the sands varied over the site,
and in Boring 7, sandy silt was encountered. In Borings 1, 2, 5, and 8 the soils were very dense,
native, silty sands within a few inches of the ground surface. These areas have apparently been
sfiripped of the looser, weathered soils du�ing past grading.
A substantial thickness of fill was encountered in Borings 3, 4, 6, 7, and 9 through 12. This fiil
consisted of silty s�nd with varying amounts of gravel a�d o�ganics, and appears to have been
usec! to construct the steep siopes along the north and west sides ot the properry. The deepest fili
was encountered in Borings 3 and 11 to d�pths of 18 feet and 23 feet, respectively. The fill was
generally Ioose, indicating that it was not compacted at the time of its placeme�t. The fill soils
likely ariginated, at least in part, from cuts made on the eastem side of the property.
The Fnal logs represent our interpretations of the field logs. The stratification lines on the Iags
represent the approximate boundaries between soil types at the exploration locations. The actual
transition between soil types may be gradual, and subsurface conditions can vary betwe�n
explofatian locations. Tt'se logs provide specific subsurface information only at the loeations
tested. If a transition in sail type occurred between samples in the borings, the depth of the
transition was interpreted. The relative densities and rnoisture descriptions indicated on the test
boring logs a�e interpretive descnptions based on the condrtions observeci during drilEing
Groundwater
Groundwater seepage was observed at a- va�iety of depths in approximatPly one half of the
banngs. The eneour�tered seepage appears to prirrEarily represent groundwater that is perched
above the dense, native soils, in the looser fill and native soils. Some grourtdwater may also have
originated from more perrtieable �ones within the dense native soils. The test borings were lef�
open for only a short time period. Therefore, the seepage levels on the logs represent the locatior
of transient water seepage and may not indicate the static groundwater level. It should be noted
?hat around�vater levels varv sPason�llv with rainfafl and other facto�s rvoica!iv tne an�o;��� or
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locatized seepage �ncountered in an excavation witl be greatest following periods of extended
tieavy precipitation.
CONCLUSIONS AND RECOMMENDATlONS
Generaf
Based on the results of our obsecvations and subsurface explorations, it appears that the
proposed dev�lopment is feasible from a geotechnicat engineering standpoin#. The competent,
native soits encountered in the test borings are relatively incompressible, and are suitable to
support foUndation elements for the planned apartment buildings.
No structures should be placed on the existing fill, as this soil is Eoose and will consolidate under
even light foundation loads. Where the dense to very dense, native soils are exposed by the
pEanned building excavations, the structures can be supported on conventional foundations,
Overexcavation, then backfiliing the overexcavation with structural fill, could be used for buildings
Where competent native soils fie within approximately 5 feet of the planned battom of excavation.
For areas where cieeper fll exists, it will likely be most economical to utilize deep foundations.
This will probably affect al) of Buildings 5, 7, 9, 11, 13, and 15, and possibly portions of other
buildings. Augercast concrete piers or driven, smafi-diameter pipe piles will likely be the most cost
effective deep foundatiort options for the site. Heavlly-reinforc�d, closely-spaced piers will be
needed for the downslope sides of Buiidings 11, 13, and ')5 to retain soil under the buildings in the
event af slope rlZovernent.
We suggest that tesf pifs be excavafed around the proposed buifdings once the existing mobile
homes have been removed. This would allow a more detailed evaluation of the extent of deep
foundations necessary for the construction.
The steep, westem and northem fill slopes wiEl likely experienCe soil movement in the fo�eseeable
future. This siope movem�nt could damage facilities constructed between the buildings and the
steep slopes. For this reason, we recomrrtend that np c;ritic-al utilities or structures be IOC3t2d
downslope of the westem buildings. If possibEe, in-ground irrigation systems should be avoided in
iandscaped areas above thQ steep fill sfopes. Broken and leakinQ s�rinkler lines that a�
undetected can cause slope failures irt these condition�
While comprised of very dense soils having high stren�. ,.�, �:. . � .._ .: _.. __� . . . �. . . . _ .
property wil! tikely experience shalfow slougning over time. This is a natural process that result:.
from weathenng of the exposed soils. Only carpo�ts or pavements are located withi;
approximately 50 feet of the cut sEopes, where the slopes a�e ta(lest. However, Buildings 2, 4, anc
6 will be situated approximately 25 fe�t from the slopes, with yard area likely occupying sorne c�
the area between the buildings and the steep sfopes. We recommend that, as a minimurt't, a �-
foot catchment wall be constructed at ths toe of the cut s{opes to co((ect. or at {east Sfow, 5oi) that
may sEough off of these slopes. The Marina Village apartment complex has catchment walis
constructed of railroati ties spanning between metal beams embedded into the ground. Similar
�at�hment walls woufd be appropriate for the Tamaron Pointe p�oject 31so_ :
Disturbance of the steep, westem slopes should be avoided, wherever possib(e, in order to
prevent a decrease in tne stabi�i�y of these sfopes. Fili should not be placed with�iri approxirliately
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7rammel Crow Residerttial JN 98192
June xx, 1998 Page 4
15 feet of the crest of these slopes_ Water from drains and impervious surfaces should not be I
directed toward, or discharged onto, the steep, westem sfopes. i
The on-site soifs are siity and fine-grained, which makes them moisture-sensiiive. Reuse of the �I,
native silty sands as structural fifl will only be possiple during dry weather and if the excavdted ,
soils are prevented from becoming wet prior to �lacement and compaction, Where very moist to ',
wet soils are encountered during earthwork, they wil! �eed to be dried prior to compaction. This is �
generally only possible during hot, dry weather. Adequate compaction of all fill, including utility
�ackfill, for structural areas must be campleted in accordance with our recommendations to limit '
the potential for set�fement. ,
Subgrades for footings and sfabs should be protected with a 2- to 4inch layer of gravel_ This re-
duces subgrade disfutbance due to foot traffic. Additional e�osion end subgrade protection meas-
ures may be necessary, depending on the conditions encountered during construction.
The native soiis have poor drainage charactenst�cs so using them for wall backfill involves a risk
that some water may seep through walls. As a minimum, waterproofing should be provided where
there will be below-gracie, occupied spaces or moisture-sensitive areas, such as storage and me-
chanical rooms. In general, the more care and expense taken during the initial drainage and wa-
terproofing instaflation, the fewer water problems fhat will develop later.
Geotech Consultants, lr�c. should be allowed to review the final devefopment plans to verify that
the recommendations presented irt this report are adequately addressed in the design. Such a
�larr review would be additional work beyond the current scope of work for this study, �nd it may
include revisions to our recommendations to accomrnodate site, development, and geotechnical
constraints th�t become more evident during the review process.
Conventional Foundations
The proposed structures can be supported oR Conventiona( continuous and sp�ead tootings
bearing on undisturbed, medium-dense to very dense, native soil or on structuraf fill placed abave
this competent, native soil. See the iater sub-section entitEed General Earthwaric and Structurat
Fil! for recommendations regarding the placerrient and compaction of structural fill beneath
structures. We recornmend that cor�tii�uous and ir�dividual spread footings have minimum widths
of 12 and 16 inches, respectively. They shouid be bottomed at least 12 inches below ths lowest
adjacent finish ground surface for frost protection. The (ocal buiiding codes shou{d be reviewed to
determi�e if different faot�ng widths or embedment depths are required. Footing subgratles must
be cleaned of loose or disturbed soii prior to pouring concrete. Depending upon site and
equipment constraints, this may require removinq the disturbed soil by hand.
Overexcavation may be required below the footings to expose competent, native soil_ Unless lean
concrete is used to fill an overexcavated hole, the overexcavation-must be at least as wide at the
bottom as the sum of the depth of the overexcavation and the foating wicith. For example, an
overexcavation extending 2 feet below the bottom of a 3-foot-wide footing must be at least 5 feet
wide al lhe base of the excavation. If lean concrete is used, the overexcavation need only extand
6 inches beyond the edges of the footir?g.
An alfowabfe bearing pressure of 3,UOU pounds per' square foot (ps� is appropriate fo� footings
constructed aceording to the above recommendatio�l5. A one�third increase in this design bearing
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pressure may be used when considering s�ort-terrr� wind or seismic loads. For the above design
critEria, it is anticipated that the total pust-cor7struction settlement oP footings founded on
campetent, native soil, or on structural fi{I up to 5 feet in thickness, will be about one-half inch, with
di�ferential settlements on the order of one-quarter inch in a distance of 50 feet along a continuous
footing.
La#eral loacis due to wind or seismic forces may be resisted by friction between the foundation and
the bearing soil, or by passive earth pressure acting on tne vertical, embedded po�tions of the
foundation. For the latter Condition, the foundation must be either poured directly against
relatively level, undisturbed soil or surrounded by level, structur�l til1. We recommend using the
following design vafues for the foundation's resistance fo lateral [oading:
Parameter Design Value
Coefficient of Friction 0.40
......-�-•--�-:_.........................................................._.--�-----�-•�---�--........._._..................
Pass�ve Earth Pressure 300 pcf
Where: (i) pcf is pounds peY Cubic foot, a►�d (ii} passive earth
pressure is computed using the equivaEent fluid density.
lf the ground in front of a foundation is loose or stoping, the passive ear#h pressure given above
will not be appropriate. We recommend a safery factor of at least 1.5 for the foundation's
resistance to lateral lo�ding, when using the above design values.
Augercast Concrete Piers
Auy�rcast piers are installed using continuous fli9ht, hollow-stem auger equfpment. Concrete
grout must be pumped continuously through the auger as it is withdrawn. We �ecommend that
augercast piers be installed by an expetienced contractor who is familiar with the anticipated sub-
surface conditions.
An allowable compressive capacity o� 40 tons can be attained by installing a 16-inch-diameter,
augercast concrete pier at least 10 feet into dense strata. For transient ioading, such as wind or
seismic loads, the allowable pier capacity may be increased by one-third. We can provide design
cri#eria for different pier diameters and err�bedment lengtl'�s, if greater capacities are required. The
minimum center-to-center pier spacing should be three times the pier diameter.
We estimate tl�at the total sEttlement of singie piers instal(ed as described above wil! be oR the
order of on�half inch_ Most of this settlement should occur during the construction phase as the
dead loads are ap�iied_ The remaining post-constn.ictiort settEement wouid be realized as ti�e live-
loads are applied. We estimate that diiie�ential settfements over any poRion of the structures
should be less than about one-q�arter inch.
We recommend reinforcing each pier its entire length. This typically consists of a rebar cage ex-
tending a portion of the pier's length with a full-leng!h center bar. Each pier can be assumed to
have a paint af f'rxity at 12 feet below the ground surtace for the eomputation of later�l load resis- '
tance, The piers that wil! support the downslope sides of Buildings 11, 13, and 15 should be I
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Trammel Crow Residential JN 98192 �
June xx, 1998 Page 6
spaced no further than 3 feet edge-to-eclge. These piers should be designed to cantilever to a
depth of 90 feet, resistirTg a lateral aclive soil density of 40 pounds per cubic foot (pc� act�ng over
the pier spacing within the cantile�er portion. This is intended to retain the near-surface soil be- !,
neath these buildings in the event of future slope movement. I
Piqe Piles
As an alternative to augercast pie�s, 3- or 4inch-diameter pipe piles can be used to support por-
tions of the buildings that are unde�lain by deep ftll. Pipe pites cannat be used for the downslope
sides of Buildings 11, 13, and 15, where large latera! soil loads need to be resisted by the deep
foundations. Pipe piles driven with a 650- or 800-pound jackhammer to the following final pene-
tration rates may be assigned the f�ll�wing c�rrrpressive capacilies.
Pile Diameter Final Driving Rate Final Driving Rate AElowable Bearing Capacity
(650-pound ham- (800-pound hammer)
mer �
3 inches 12 seGinch 10 sec/inch 6 tons �
4 inches 20 seGinch 15 sec/inch 10 tons
Pile caps and grade beams may be used to transmit loads to the piles. Pile caps should include a
minimum of two piles to reduce the potentia( for eccentric loads being applied to the pifes.
Welded, slip or threaded couplers should be used to connect subsequent pipe sections on pites
that need to be extended in length.
Due to their small diameter, the lateraf capacity of vertical p'tpe piles is relatively small. Lateraf
loads due to wind or seismic foress may be resisted by passive earth pressure aciing on the verti-
cal, ambecided portions of the foundation. For this condition, the foundation must be either poured
directly agairtst relatively level, undisturbeci soil or surrounded by level, structural fill. We recom-
mend using a passive earth pressure of 250 pounds per cubic foot for this resistance. !f the
ground ici front of a foundation is (oose or sloping, the passive ea�th pnessure given above will not
be appropriate. We recommend a safety factor of at least 1.5 for the foiandation's resistance to
lateral loading, when using the above design values. if additional lateral resistance is required we
recommend driving battered piles in the same direction as the appfied 4ateral load. The lateral ca-
pacity of a battered pile is equal to one-half of the lateral component of the allowable compressive
load, up to a maximum allowable lateral capacity of one ton. The allowable verticaf capacity of
battered piles does not need to be reduced if the piles are battered steeper than 1:5
(Horizontal:Verticaf},
Seismic Considetations
�he site is located within Seismic Zone 3, as illustrated on Figure No. 16-2 of the 1994 Uniform
Building Code (UBC). In accordance wi#h Table 16-J of the 1994 UBC and the 1997 UBC, the
native site soii profile is best represented py Pfofile Type 51 anp �� (QenSe Soil}; respectively.
The loose, wet fill encountered in several of the borings is potentialEy liquefiable during a large
earthquake. This hazard is mitigated by the use of deep foundations embedded into non-
liquefiable soils to support the affected �uildings,
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Slabs-on-G�ade
Where undisturbed native soils are exposed, the building fioo�s may be constr�cted as slabs-on-
grade. The subgrade so31 must be in a firm, non-yieiding condition at the tirne of slab construction
or unders(ab fitl placement. Any soft areas encauntered shouRd be excavated and replaced with
select, imported, siructural fifl_ Building floors that are underlain by (oose fiil or native soils should
be supported on piers, either as structural slabs or as framed floors over a crawl space.
/�U slabs-on-grade shoulci be underiain by a capillary break os drainage layer consisting af a
minimum 4-inch thickness of coarse, free-draining, stnictural filt with a gradation similar to that
discussed later in Permanent Foundafiion and Retainin� Walls. In areas where the passage of
moisture through the slat� is undesirable, a vapor barrier, such as a 6-mil plastic membrane,
should be placed beneath ihe s{ab. Additional(y, sand shouid be used in the fine-grading process
to reduce damage to the vapor bamer, to provide uniform support under the slab, and to reduce
shrirtkage cracking by improving the concrete curmg process.
Permanent Foundation and Retaininq Wafls
Retaining walls back€il3ed on ortly ona side should be desigr�ed to resist the later'al earEh pressures
imposed by the soil they retain_ The following recommended design parameters are for wa!Is that
restrain level backfiil:
Parameter Design Value
Active EaRh Pressure'` 40 pcf
�
--._.........................�----------�----�--..........,,...._._....___'........-�--�-----._........�............... �
= Passive �arth Pressure 300 f ',
--�......................................�--.._......-�---�--...---.............:.--�----.......--��---�----�--._..........,..........
Coefficient of Friction 0.40
.....-�--�----�-�-•.................................�---------�-�---.___......:.................._.._...-----�-----._.._.........,
Soit Unit Weight 130 pc€
Where:(i)pcf is pouttdS per cubic foot,and(ii)active and passive
earth pressures are computed using t�e equivafent fluid
pressures.
` Fw a restrained walt that carenot deflect at least 0.002 times Ks
heigM,a uniform latera!pressure equa!to 10 psf times the height
of the wall ShOuld be added to the abOve acvve equ�valerrt fluid
pressure.
The value5 given abUve are to be used to design permanent foundation �rtd retaining walls only.
The passive pressure given is appropriate for the depth of level, structural fill placed in front of a
retaining or foundatian wall only. We recommend a safety factor of at least 1_5 for overtuming
� and sliding, when using the above values to desigR tne walls.
The design values given above do not indude the effects of any hydrostatic pressures be�ind the
walls and assume that no sutcharge slopes or loads, such as vehicles, will be placed behind tt�e _
walls. if these conciitions exist, those pressures shouic4 be added to the above lateral soi!
pressures. Akso, if sloping backfill is d�sired behind the walls, we will need to be given the wall
dimensions and the slope of the backfill in order to provide the appro�riate design earth
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Trammel Crow Residentiai JN 98�y2
June xx, 'E 998 Page 8
pressures. Yhe surch�rge due to traffic loads behind a wa{I can typi�afly be accounted for by
adding a uniform pressure equal to 2 feet multiplied by the above active fluid d�nsity,
Heavy cflnstn.,ction equipment should not be operated behind retaining and foundation walEs
within a distance equal to the height ot a wa�l, unless the wa(ls are desiyned for the additional
lateral pressures res�iting from the equipment. The wall design criteria assume that the backfill
will be well-compacted in lifts no thicker than '12 inches_ The compaction of bacEcfill near the walls
should be accomplished with hand-operated equipment to prevent the wails from being
overloaded by the higher soil forces that occur during compaction.
Retaining Wall Backfilt
BaCkfill placed behind retaining or four�dalion wafls should be coarse, free-draining,
structural fill containing no organics. This baCkfil! should contain no more than 5 percent
silt or clay particles and have no gravel greater than 4 inches in diameter. Ttte percentage
of particles passir�g the No. 4 sieve shouid be between 25 antl 70 percent_ Where the on-
site silty sands, which are not free-draining, are used as wall backfill, at least 12 iRches of
free-draining gravel shoulci be placed against the wal�s fo� proper drainage.
The purpose of these backfll requirements is to ensure that the design criteria for a
retaining wall arC not exceeded because of a bu'tld-up of hycirostatic pressure behind the
wall. The top '�2 to 18 inches of the backfill should consist of a compacted, relatively
impermeable soil or topsoil, ar the surface shoufd k�e paved. Tt�e ground surface must also
slope away from backfilled walls ta reduce the potential for surface water to percolate into
the backfill. The sub-ssction entitled General Earthwork and Sfructural �il! contains
recommer�dations regarding the placement anCf compaction of st�uctural fill behind
retaining and foundation walls.
The ahnve recorrzmend�tions are not irttended to waterproof the below-gtade walls. If
some seepage t!'irough the walis or moist conditions are not acceptabfe, waterproofing
shoufd be provided. This could include limiting cold-joir�ts and wall penetraf�ons, and using
bentortite pansls or membrsnes on the outside of the walls. Applying � thin cc�at of asphaft
emulsion is not consldered waterproofing, but it wil! only help to prevent moisture,
generated from water vapor or capiliary action, from seeping through the concrete.
Rockeries
antici afe t at rockeries be used in the site devefo ment. A rocke is not ir�tended to
We h ma
P Y P rY
f�nction as an enc�inPered strucfure to resist lateral earth pressufes, as a retaining wal! wauld do.
The primary function of a rockery is to cover the exposed, excavated surFace and thereby refard
the erosion process_ We recomrnend limiting rockeries to a height of 8 feet and pkacing them
against only dense, corl�petent, native soil. Wh�re rockeries are canstr�ccted in fr�nt of
compacted fill they should be limited to 5 feet in height. The lower twa�thirds of each fill rockery
should be constructed using 3- to 4-man rocks. Taller �II rockeries would require the use of
geogrid reinforcement in the compa�ted backfiil.
The construction of rockeries is, to a {arge extent, an art not entirefy contro(table by engineering
methods and standards. It is imperative that rockeries, if used, are constructed with care and in a
proper manner by an experienced con#r�ctor with proven ab�lify in rockery construction, The
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Tramrnel Crow Residential �N 98192
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rockeries should be constructed with hard, sound, durable rock in accordance wiih accepted local
praCtice and star�dards. Sof{ rock, or rock with a significant number of fractures nr inclusions,
should not be used, in order to limit t�e amount of maintenance and repair needed over time.
Pr�visions for maintenance, such as access to the rockery, should be considered in the design. ln
general, we recommend that rockeries have a minimum dimensivn of one-third fhe height of the
slope cut above them. Given the existing soil conditions tiered rockeries �re not recommended.
Excavations arld Siopes
Excavation slopes should not exceed the limits specified in local, state, and national govemment
safety regulations_ Temporary cuts to a depth of aE�out 4 feet may be attempted verticalfy in
unsafurated soil, if thefe are no indications of slope instability. Bas�d upon Washington
Administrative Code (WAC) 296, Part N, the existing fill and loose, native soils at the subject site
would be classified as Type B. Therefore, tempocary cut slopes greater than 4 feet in height in
these loose soiis should not be excavated at an incEination steeper tnan 1:1 (Horizvntal_Vertical),
extending continuously between the top and the bottorn of a cut.
The above-recommended temporary skope inclination is based on what has been successful at
flther sites with similar soil conditions. Temporary cuts are those that will remain unsuppo�ted for
a relatively short duration to allow for the construction of fo�indati�ns, retaining walls, or utilities.
Temporary cut slopes shauld be protected with plastic sheeting during wet weather. The cut
slopes should also be backfilled or retained as soon as possibte to reduce the potential for
inst8bility, PIe3Se ilote that lovse soil can cave suddenly and withaut waming. Excavation
contractors should be made especially aware vf this potential danger, '
Al) permanent cuts into native soil should be inclined no steeper than 2:1 (H:v). Fil1 slopes sf�ould
not be constructed with an inclination greater than 2:1 {H:V). To reduce the potential for shallow
sloughing, fili m�st be compacted to the face of these slopes. This coul�i be accomplished by
ove�building the cornpacted fill and then trimming it back to its final inclination. Water should not
be allowed to flow uncontrolled over the top of any temporary or permanent slope. Also, aEl
permanently exposed s{opes should be seeded with an a�propriate species of vegetation to
reduce erosion and improve the stability of the surficial layer of soil.
Arty distuCbanCe to ttte existiny 5teep slopes outside of the building limits may reduce the stability
of the slope. Damage to the existing vegetation and ground shoufd be minimized, and any
disturbed areas should be revegetated as soon as possible. Soil from the excavation should not
be placed on the steep slopes, and this may require tne off-site disposal of any surplus s�il.
Drainaqe Considerations
We recommend the use of footing drains at the base of Perimeter foatir�gs and al! backfilled,
earth-retaining walls. These drains should be surrounded by at least 6 inches of 1-inch-minus,
washed rock and then wrapped in non-woven, geotextile filter fabric (Mirafi 140N, Supac 4NP, or
simi4ar mate�ial). At its highest point, a pertorated pipe invert should be at least as low as the
bottorn of the footing, and it should be sloped for drait�age. Drainage should also be provided -
inside the footprint of a structure, where (1) a crawi space will sEope or be iower than the
surrounding ground surface, (2) an excavation encounters significant sa�paye, or (3} an
excavation for a E�uilding will be close to the expected high groundwater elevations. We can
�un 1 � y8 03 : Z5p (4251747-8551 p . 11
Trammel Crow Residential JN 98i92
June xx, 1998 Page 10
provide recommendations for interior cirains, should they �ecome necessary, d�:ring excavation
and foundation construc.-tion,
All roof and surtace water drains must be kept separate from the foundation drain system. A
typical drain detail is attached to this report as Plate 15. For the best long-terar� performance.
perforated PVC pipe is �ecommended #or afl subsurface drains.
' Groundwater was observed during our field work. If seepage is encount�red in an excavation, it
snould be drained from the site by directing it through drainage ditches, perforated pipe, or French
dr�ins, or by pumping it from s�mps interconn�ctPd by shallow connector trenChes at the bottom
of the excavation.
The excavatioF� �r�d site should be graded so th�t surface water is directed off the site and away
from the tops of slopes. Water should not be allowed to stand in any area where foundations,
slabs, or pavemen#s are to be constructed. Final site grading in areas adjacent to (a ) building(s)
should slope away at least 2 gercent, except where tne area is paved_ Waler frorn roof, storm
water, and foundation drains shoufd not be discharged onto slopes; it should be tightiined to a
suitable outfail located away from any slopes,
�
Pavement Areas
As exhibited by the damaged existing pavements, the subgrade soi(s are subject to softening
under repetitive iraf�ic loads. To reduce the potential for this, we recommend that at least 9 inches
of irnported, gravelly structural fill be placed under ali pavement sections in drive lanes or entrys,
where the heaviEst, most frequent loading is anticipated. ThE subgrade soils must be in a stabfe,
non-yielding condition at the time ot paving, or the placement of stn.�ctural fill. Structural f;ll or
fabric may be needed to sEabilize soft, wet, or unstable areas. We recornmend using Supac SNP,
manufactured by Phillips Petroteum Cor�pany, or a non-woven fabric with equivalent strength and
permeability characteristics. In most instances where unstable subgrade conditions are
encountered, 12 inches af granuiar, structura! fll will stabilize the $ubgrade, except for very soft
areas where additiona4 fill coufd be req�aired. The subgrade should be evaluated by Geotecr
Consultants, Inc., after the site is stripped and cut to grade. Recommendations for the cornpaction
of structural fifl beneath pavements are given in a later sub-section entitled Generai Earthwork
and Structural Fill. The performa _ . - . i - -t . ,- _ �- �
stability of the underlying subgrade.
The pavement for (ightly-ioaded traffEc ard parki�g areas should consis� of 2 �nches of aspha
concrete (AC) ovEr 4 inches of crushed rock base (CRB) or 3 inches of asphalt-treated bas�
(ATB). We recommend providinq heavily-loaded areas with 3 inches of AC over 6 inches of CRt�
or 4 inches of ATB. Heavily-loaded areas are typically main driveways, dumpster sites, or areas
with truck traffic_
ThE pavement section recommendations and guidelines presented in t�is report are based on our
experience in the area and on what has been successful ir� similar situations. Sorne maintenance
and �epair of lirriited areas can be expeciecl. To provide for a design without the. need for �r�y
repair would be uneconomical.
G�nerat Ea�thwork and Structura! Fili
Jun i � �� U3: z5p (4zS1747-8561 p. 12
Trammel Crow Residentia! JN 98192
June xx, 1998 Page 11
AN building and paverr�ent areas should be stripped of surface vegcfation, topsoil, organic soii,
and other deleterious material. It is extremely important that the foundation(s) and slab(s) for the
existing structures are also removed. The stripped or removed r►�aterials should not be rr�ixed with
any materials to be used as struCtul'al fill, but they could be used in non-structural areds, such as
landscape beds.
Structural fi[! is defined as any fill placed under a bui{ding, behind permanent tetaining or
foundation walls, or in other areas where the unde�lying soil needs to support loads. A{i structural
fill should ba placed in horizontal lifts with a moisture conteRt at, or near, the optimum moisture
cantent. The optimurrt moisture content is that moisture content that results in the greatest
compacted dry density. The moisture content of fill is very important and must be closely
controlled during lhe filling and compaction process.
The allowabfe thickness of the filf lift will depend on the material type selected, the compaction
equipment used, and the number of passes made to compact the lif#. The loose lift thickness
should not exceed 12 inches. We recommend testing the fill as it is placed. If the fill is not
compacted to specificatians, it can be recompacted before another lift is placed. This eliminates
the need to remove the fifl to achiev� the required compaction. The following table presents
recommended relative compaCtions for structural ftll:
Location of Niinimum
Fill Placcment Ralativo Compaction
Beneath footings, slabs : 95°�
.or walkwaY.s................... �
...,.,..,.. •
-----..,..,.�...................�-----._.........................._._...__....._..
Behind retainin� wafls.......;..,. 90%..................-------.--.
.................. .... ......._......._.__...._._...
; 95% for upper 12 inches of
Beneath pavements : subgrade; 90% below that
levet
Where: Minimum Relative Compaction is the ratio, expr'essed in
percettt8ges, of ihe compacted dry density to the maxim�rn dry
tlenslty, ae f�C�CffIAllCII in dccordance with AS7M Test
Designation D 1557-78(Modified Proctor�.
Struc�uraf fill #hat will be p{aced in wet weather should consist of a coarse, granular soil with a silt
or clay content of no more than 5 percent_ The percentage of patticles passing th� No. 2Q0 sieve
should be measured from that portion of soil passing the thrPe-quarter-inch sieve.
UMiTATIp[�IS
The analyses, conclusions, a�1d recomrnendatior�s contained in this report are basetf on site
conditions as they existed at the time of our exploration and assume that the soil enCountered in
the test borings is r�pres�ntative of subsurface conditions on the site. ff the subsurface conditions
encountered during construction are siqnificantly different from those observed in our explorations,
we should be advised at once so that we can review these conditions and reconsicier our
recommendatrons whe�e necessary. Unanticipated soil conditions are commonly encountered on
construction sites and cannot be fully anticipated by merefy taking soil sarrtples in test bOfiflg5.
Subsurface conditions cart also vary between exploration locations. Such unexpected conditions
�un' 1 � �� 03: z6p ( 4251747-9561 p , l �
Trammel Crow Residential JN 98'192
June xx, 1998 Page 12
frequentfy require making additional expenditures to attain a properly constructed project. It is
c'ecomrnended that the owner consider providing a contingency fund to accornmodate such
potential extra costs and risks. This is a standard recommendation for all projects.
The recommendations presented in this report a�e direcied toward the pr�fection of onfy the
proposed structures from damage due to slope movement. Predicting the effects of development
on the stability of slopes is an inexact and imperfect science that is currently based mostly on the
past behavior of slopes with similar characteristics. Landslides and soi! movement can occur on
steep slopes before, during, or after the development of property. The owner must ultima#ely
accept the possibility that some slope movement co�lld occur, resultinq in possible koss of ground
or damage to the facilities around the proposed building.
This report has beer� prepared for the exclusive use of TrammeS Crow Resid�ntial, and its
representatives for specific application to this project and site. Our recommendations and
conclusions are based on observed site materiafs, and selective laboratory testing and
engineering analyses. Our canclusions �nd recommenciations are professi�nal opinions derived
in accordance with current standards of practice within the scope of our services and witFtin
budget and time constraints. No w�rranty is expressed or implied. The scope of our services
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 o�ir report for cansideration in design. We recommend including this
report, in its entirety, in the project corttract documents so the contractor may be aware of our
findings.
ADAITIONAL SERVECES
Geotech Consultants, Inc. should be retained to provide geatechnical consultation, #estirtg, and
observation services during construction. This is to confirm tY�at subsurface conditions are
consistent with those indicated by our exploration, to evaluate whether earthwork and foundat�on
construction activities comply with the general intent of the recommendations presented in this
report, and to provide suggestions for design changes in the event subsurface conditions differ
from those anticipated pnor to t�e sta�t of construction. However, our woric would not inclUde the
supervision or direction of the actuaf work of the contractor and its employees or agents. Also, job
� and site safeiy, and dimensional measurements, will be the responsibility of the contractor.
The following plates are attached to complete this report:
Plate � Vici�ity Map
Plate 2 Site Exploration Plan
Plates 3.. 14 Test Boring Lags
Plate '!5 Footing Dra�n Detail �I
We appreciate the opportunity to be of service on this project. If you have any questions, or if we
may be of further service, please do not hesitate to contaCt us.
••••�� i � .�o a�o. c�r l '+C� 1 !-t � -�s:�bl p . 14
7rammel Crow Residential JN 98��9Z
June xx, 'S 998 Page 13
RespectEully submitted,
GEOTECH CONSULTANTS, INC.
N1arc R. '.
Associate
James R. Finley, P.E.
Principal
MRM/JRF:aIt
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, � . . . � _.._ ,... � i [ e i im
. ,,
\�,•.. � , . . � - ' nEw��eo..wo+o. �u —� D - •_ 7_ !
. .• . � ' �eaa�w no...ie, 7.c . � -T�t— � — -° r••,«,,
. . . . .. .-.. CQrLCT rJO�n��)i0) ! -D r"— ' �_1� '�_ ! G..n W. . v
� • 10
� . . ' '-`00 . ' • D = p R..�..e.
. . ... ..� :� ... !' .... ..
- . � . . ' ' . .._ P�liCNS rpyiplD l G i ] 0
. . . . � '" IQAl1.6RlIS. s O K' .1 M 7e
� • , � . . . ' � OMiri[� CI � � �
, . ' �' � 10 9 W 4 1p
. • . . P`EN� iYA �1 C ` 6 7 9
1 � J�
, .. ' .. . . �• , . .. ' TOTK I�G. ]fi I! G 6
.. .. . � Gd�w�ne*1rr�ie v u a .i � za
. � � � . . ' .mu�aaa�c n� � � a _�_ e
, ,o, , � ,� v � .�,._ � p-1
� o� BORING 1
' �e��yti0� �ati��,���,0�5<4� fiQ`� 5
� ,�a � 5a �5G Description
": � � 2" asphait over
65 1 � , � f Brown/tan, slightly silty, fine-to medium-grained SAND, moist, very dense
, , �
i
� ;
I
5 82 2 � I ' � i
� �
i �
� ,
� �
10 S2 3 � SM � -with some pebbles
�
i ' ii
I I
,
15 91 4 � ` � � �
�, �
, i ';
I � , ,
, � , � �
� i ;
f
2� 60/6" 5 8 � �
* Test boring was terminate�l a120.5 jee!during drilling on Ma�' 14, 1998.
* :Yo groundwaler seepage was encountered during dri!ling.
25
30 �
35
40
BORING LOG
�_ � G E O T E C H 2100 Lake Washington Boulevard
CU�ISULTANTS,INC.
� Renton,`Vashington
�.- � ���! Job No: Date: Logged by: Plate:
, �� 98192 �Iay 1998 EOP 3
� o� BORING 2
��� ',,�� a�'��.� �°�y{�� 4�'� 5
`���5 `�,�a'� � 4 5a�' �5G Description
' � ' Grass
�
I ' Tan, sil ravell SAND with root fibers, fine-to medium- rained, moist, ve
50/4" 1 ■ � . �. � , h'� 9 Y 9 rY
1 �' ! '� ' ' dense
, ,I,
� �
5 59 2 ` ' .,: ' I :
i �. :
� ,
SM
',; '� ' : :
� 1 o sor2�� 3 e :I . , :
,.I : �
' �" : :
;
i.
�r� 76 4 � ' ' Tan, s(ightly silty SAND with some gravel, fine-to medium-grained, moist, very
dense
SP ;
SM �
20 � 73/6" 5 ■ I - becomes gravelly and wet
* Tes1 boring was lerminated at 20.5 feet during drilling on Niay 14, 1998.
* Grou�:dwater seepage was enco�mtered at 10 jeet during drilli�rg.
25
30
35
40
BORING LOG
� � GEOTECH 2100 Lake Washington Boulevard
CONSULTANTS,INC.
� Renton, Washington
S� � Job No: Date: Logged by: Plale:
, - 98192 blay 1998 EOP 4
� o� BORtNG 3
�����,°'� �a'�ro�,���,°�y�F� �4�e 5
�� ,�o- 4 50- J5� Description
Grass
15 1 e Tan, si1ty, gravelly SAND with some organics, fine- to medium-grained, moist,
medium-dense (FILL}
5 � 5 2 � - becomes gray, very moist, very loose
10 11 3 �
- becomes brown/black with organics, medium-dense
FILL
15 �g 4 ' - becomes gray
�
20 25 5 � -with fine root fibers and wood chips
, ;,, ; ,
25 55 6 � SM : Gray, silty, gravelly SAND, fine-to medium-grained, moist, very dense
I
__* Test boring wQs terminaterl at 26.5 feet during drilli�rg on May 14, 1998.
* Groundwater seepage was encountered at S jeet during drilling.
30
35
40
BORING LOG
� � GEOTECH 2100 Lake Washington Boulevard
CONSULTANI'S,INC.
� Renton, Washington
� � Job No: Date: Logged by: Plate:
� ��- 48192 htay 1998 EOP 5
- o� BORING 4
��'� '.�� d�'�t� ti��y�4� 4�� 5
`���y �,�a�° � 4 5a� J5� Description
Grass and gravef surfacing over
31 1 ' FILt Brown/black, slightly silty SAND with some gravei and organics, moist, dense
(FILL)
5 � Gray, slightly silty SAND with some gravel, fine-to medium-grained, moist,
�$ 2 ' SP medium-dense
SM
I
10 54/6" 3 ■ Tanlbrown, slightly silty, gravelly SAND, medium-to coarse-grained, moist,
very dense
; SP
SM
15 6016" 4 s
�
* Tes!boring was terminated at 1 S.S feet during dri!ling on May 14, 1998.
* No grounJwaler seepage was encountered during dri!ling.
2�
25
30
35
40
BORING LOG
� � G E O TE C H 2100 Lake Washington Boulevard
CONSULTAI�TS, INC.
� Renton, Washington
�! ,`��_-- .�..! Job No: Date: Logged by: Plate:
• 98192 hlay 1998 EOP 6
� BORING 5
. o
e�� •o,r a'��`e �,o~°y<F� 4��' �5
`����' �,�d�° � 4 50-�' �5 Description
i 2"asphalt and 2" crushed rock
, I ' i ;;.
60/4" 1 ' : I I , Brown, silty, gravelly SAND, medium-t�coarse-grained, moist, very dense
i' � ; ' (G/acial Ti1Q
5 , � ili
60/6" 2 ■ � '
I' � Ii
,:
�,
SM �
'10 50/4" 3 ■ � ', ;i : i
I: ;ii Ii
i �. .
� II
15 � 50/1" 4 0 � -becomes wet
1� ' i
��;I ' I
���; ;
� �:
� � � � i
� , �
20 56/6" 5 ■ � ; - becomes less silty
' ! I
* Tesl boring was ternrinated at 20.S jeet during drilling on May 1 S, 1998.
* Groundwater seepage was encountered at 1 SJeet during dri!ling.
25 I
30
35 I
40 i
BORING LOG
� � G E O T E C H 2100 Lake Washington Boulevard j
CONSULTAN'I'S,INC.
� Renton, Washington
� � Job No: Dale: Logged by: P!ale:
� 9819Z A1ay 1998 EOP 7
� o� BORING 6
���' •o,�` a'���,� �,o�'�<4� 4�� 5
`��¢��' `�,�a�° � Q 5dfi �SG Description
Grass
30 1 � Tan/brown, silty, gravelly SAND, fine-to medium-grained, moist, medium-
dense (FILL)
5 FILL
22 2 1
10 � 6 3 � Gray, silty, gravel(y SAND with extensive organics, fine-to medium-grained,
very moist, loose (FILL)
FILL
15 10 4 � - becomes very silty
� I ; �
20 83 5 ` ' SM , Gray, silty, graveily SAND, fine-to medium-grained, moist, very dense
III � IIi
* Tes1 boring was lerminaled at 21.S feet during drilling on�tifay I5, 1998.
* Groundwater seepage was encounlered at 9 feet during drilling.
25
i 30
i
i
35
40
BORING LOG
� � G E O TE C H 2100 Lake Washington Boulevard
CONSULTA;VTS, INC.
� Renton, Washington
� � Job No: Date: Logged by: Plate:
' 98192 May 1998 EOP 8
ti BORING 7
� �< 5 �° �
����5,,�r ,,�1�eb��g`� 4��4��'4� �SG� Description
0
Gra ss
1d 1 � Brown, slightly silty SAND with gravel and fine root fibers, moist, loose (FILL)
5 2� 2 � FILL
i :
� �
10 80 3 � Tan SILT with sand lenses, low plasticity, moist, very dense
; i
I
�
; ,
15 74 4 ' ML -with orange mottling
� � ; , .
�
. �
' i
�
20 86 5 � f �
, i I
! I
* Test boring was terminaled at 21.25 feet during drilli�rg a�May I5, 1998.
* No groundwater seepage was encountered during drilling.
25
30
35
40
BORING LOG
`_ � GE O TE C H 2100 Lake Washington Boulevard I
CONSULTA?VTS,INC.
� Renton, Washington �
� � _ Job No: Date: Logged by: Plate:
� 98192 htay 1998 EOP 9 �i
I
o� BORING 8
. `��` 1�r b���� `o�y t4o 4`� �
`�'�e5 `�,�a�° � 4 5a� J5G Description
Grass
75 � , ' Brown, slightly silty, gravelly SAND, fine-to medium-grained, very moist, very
dense
5 � 40 2 0 gM -becomes wet
I II
; I ',: i
10 I � � i Brown, silty, gravelly SAND with orange mottling, fine-to medium-grained, moist,
81 3 0 i very dense
I ; I'; ;
, � ;:,'�
' SM
iII
15 50/5" 4 ■ ! ; I i i' ;
� � �
97 5 � � i i
;�
2� * Test boring was terminated at 18.75 jeet during dri!lr�rg due to auger refusa!on
May 1 S, 1998.
* Groundwater seepage was encotrntered at 4 feet drrring d�illing.
25
30
35
40
BORING LOG
� � GEOTECH 2100 Lake Washington Boulevard
CONSULTANTS,INC.
� Renton, Washington
� Job No: Date: Logged by: Plate:
, � 98192 May 1998 EOP 10
- ot BORING 9
��� �.�fi a`��� �.��y�4� Q�� 5
`��e5 `�,�a'� � 4 �afi �5� Description
2" of asphalt over
Brown to gray, silty SAND with some gravei, fine-to medium-grained, very
moist, loose (FILL)
5
14 1 � FILL
10 '�
6 2 i �
I Brown-gray, siightly silty, gravelly SAND, fine-to medium-grained, moist, very
� dense
15 65 3 � I(
SP
SM
20 59 4 '
* Test boring was terminated at 21.5 jeet during dri!ling on June 9, 1998.
* No groundwater seepage was encountered durrng drilling.
25
30
35
;
�
;
40
BORING LOG
� � GE O TE C H 2100 Lake Washington Boulevard
CONSULTANTS,INC.
� Renton, Washington
� Job No: Date: Logged by: Plate:
' —��- 98192 blay 1998 DBG t 1
o� BORING 10
m�� �o,� atie�,� �,0�5�F� Q�� 5
`����' `�,�a�° � 4 c�afi �5� Description
4" of asphait over
Brown-gray, silty SAND with gravel, moist, loose (F/LL)
5 46 1 � - becomes gravelly
FILL
10 �6 2 � -with some waod debris
15 50/4" 3 � Gra silty, gravelly SAND, very moist to wet, very dense
�'�' i ;; Y�
,., ,
'i;'
,S,M, �
�
"il `;i
' ' I
20 61 4 � � �"
* Test borirrg was terminated at 21.5 jee!during drilling on June 9, I998.
* No grauadwater seepage was encourrtered dttring drilling.
Zv
30
35
40
' BORING LOG
� � G E O T E C H 2100 Lake Washington Boulevard
CONSULTAN'I'S, INC.
� Renton,Washington
S� ! Job No: Date: Logged by: Plate:
� 98192 Niay 1998 DBC l2
� BORING 'i 1
t e�'�' ��� �1a�'�ti� `��5���0 4�� 5
`���5 `',�a� � 4 5afi �5� Description
Grass over
Brown, gravelly SAND with some silt, dry to moist, medium-dense (F1LL)
- becomes less graveliy
5 36 1 � FILL
10 � 11 2 � Dark brown, silty SAND with organics, wet, loose (TOPSOIL)
I�', ','II;
SM Dark gray, silty SAND, fine- ta medium-grained, wet, loose
��
15 50/4" 3 � � `s Gray-brown, silty SAND with some gravel, very moist, very dense (Glacial TiIQ
; SM ;
� i
50/2" 4 ■ ''. ' ` i l' (
* Test boring was terminated at 18 jeel dtre to Auger refusal during drilling on
20 June 9, 1998.
* Groundwalerseepage was encounlered at IOJeet during drrlling.
25
30
35
40
' BORING LOG
� � GE O TE C H 2100 Lake Washington Boulevard
CONStiLTANTS,INC.
� Renton,Washington
��� � Job No: Date: Logged by: P[ate:
��- 98192 Nlay 1998 DBG 13
�
� BORING 12
` ��'� :0� Qa�'��,� �,��y���o Q�� 5
`���y `',�o-b � 4 5a� �5G Description
Grass
5 14 � t Brown-gray, silry SAND with some gravet, very moist to wet, ioose to medium-
dense (FlLL)
F1LL
10
4 2 '
�
15 13 3 � Dark brown, silty SAND with organics, very moist, loose (TOPSO/L)
, , .
'� � ! �: Dark gray, silty SAND with some gravel, very moist, loose
i ; '
,i;�,i, ,;',,
, ; , :
; , ,,,
� , .
20 49 4 � � � I I -becomes wet, dense
SM
25 60 5 ■ Ii,, �: � - becomes less silty
* Test boring was terminaled a126 jeef during drilling on June 9, 1948.
* Croundwater seepage was encounlered af 12 feet during drill�ng.
30
35
40
BORING LOG �
� � G E O T E C H 2100 Lake Washington Boulevard
CONSULTANTS,INC.
� Renton, Washington
� ! Job No: Date: Logged by: Plate:
98192 N1ay 1998 DBC 1�
.
,
�
�
�� �
, __
- /
�
/
i �
i
�
. -_ \
,�
B-$ �B-$ �,
� �
10 � \
�� 14 12 _ I,
� 6 �' .
_ 8
B-7
4 �
2
�� B-12 13 B-11
� 11
15 - 9 7 � B_3 � --
5 � B'�
g_4 3
� B-6 �,
� g_g � g_� 1
. -----�.. _
LAKE WASHINGTON BLVD.
LEGEND:
� APPR�XIMATE 80RINO LOCATIONS
Q PROPOSED BUILDINGS = SITE EXPLORATION PLAN
_-- � GEOTECH 2100 LAKE WASHINGTON BLVD.
-� CONSULTANTS RENTON, WA
�
�
� Job No.: Oalt+ Scole: Plalt�
""�'�"'- 98162 JUNE 1998 2