HomeMy WebLinkAbout03216 - Technical Information Report - Geotechnical --- - - ---- - --- _ _- - - - - - �--- -- ----- ------ --- - - - - - -- -- --
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G E O T E C H 13256 Northeast 20th Street,S�ite 16 ;
Bellewe,Washington 98005
CONSiJI.TANTS, INC. (425)747-5618 FAX(425)747-8561
July 25, 2008
CITYOFRENTph J N08183
RECEIVED
Gurtown Homes ��� 2 $ ���,8
24020— 118th Place Southeast
Kent, Washington 9803o BUILOINGDiVIS10N
via email �
Attention: Kanwaljit Dulai �
' I
Subject: Geotechnical Engineering Study I
Propased Two Townhouse Buildings I
972 Edmonds Avenue Northeast �I
Renton, Washington
Dear Mr. Dulai:
This geotechnical engineering report presents our geotechnical findings and conclusions related to
the proposed construction of two townhouse buifdings on the subject property. The scope of our
services consisted of exploring site surFace and subsurface conditions of the property, and then
preparing this report to provide geotechnical considerations for foundations, retaining walls,
subsurface drainage, and general earthwork. This work was authorized by your acceptance of our
proposal, P-7653, dated June 17, 2008.
• Detailed pians were not provided to us at the time of this report. We were provided with typical
floor plans and efevation views for one building. A site plan showing the locations of the planned
two buildings was not available. The only information available to us regarding the planned finish
grades on the site is shown on the elevation views of the proposed building. We expect that the
slal�on-grade for the lower floor will be a few feet below the existing site grade. The provided
plans do not show how close the buildings will be to the property lines. However, based on the
previously-excavated area for the southem building, it appears that the structure will be several feet
fr�rn the south and west property lines and will not extend any closer than approxirrtately 10 feet to
the eastern property line. This eastem setback is signficar�t because of the presence of an
existing concrete retaining wall near the eastem property line tiiat netains fill tor the adjacent
neighbors parking lot.
!f the scope of the project changes from what we have described above, we should be provided
with revised plans in order to determine if mod�cations to the recommendations and conclusions of
� this report are warranted.
SITE CONDlT70NS
SURFACE
The subject property is a rectangufar shaped lot located on the eastem side of Edmonds Avenue
Northeast. This property slopes gently from the east down to the west. The site has been
previously cleared of most vegetation and it is apparent that the utilities have been stubbed into the
site from Edmonds Avenue Northeast. Stakes that protrude from the ground in the central portion
GE�TECH GONSULTANTS,IIVC.
32 ��
KanwaljitDulai JN 08183
July 25, 2008 Page 2
of the prope�ty indicate that sewer and water fines have been installed. Additionally, there is a
storm sewer catchbasin located in the approidmate middle of the property. This appears to be
connected to the City storm sewer located in Edmonds Avenue Northeast. The area of the
proposed southem building was previously excavated down 2 to 3 feet below the original ground
surtace. The northem buiiding area had not been excavated and there is a pile of filf in the eastem
end of this building. It is unclear where the property boundaries are exactly. An asphalt-pa�ed
driveway extends aiong the northem side of the property. This driveway provides vehicle access
from Edmonds Avenue Northeast to the apartment building located to the east of the subject
property. Along the eastem side of the property is a concxete wall that retains approximately 5 to 8
feet of fill, above which is the parking fot for the adjacent apartment building. During our visit to the
site we did notice that there were some vertical cracks in the face of this wall: To the south of the
property, beyond an ebsting fence, is a concrete driveway, and then a house. As discussed
above, there is an asphatt drnreway along the northem side of the property, beyond which is a
parking lot.
There are no steep slopes on, or near, the subject property.
SUBSURFACE
The subsurtace conditions were explored by excavating five test pits in the approximate footprint of
the southem building and five test pits in the approximate footprint of the northem building. The '
locations of the test pit� tNP�P �!R111P.� E?!'+�'1P, n�PSP.'lCP !�f P.Y�Stir`G• !I}Ill�j(?c in �I-�o rontPf !)r ffl? C1fo An^ I
along its northem edge
The test pits were excu.u��._; _. .,.. , ��:_ .�� ,; �; uu�.�_ u,_:,::u �.,,�u�u��: ,. y,:��:;:;, :�.,�: �
engineer from our staff observed the excavation process, logged the test pits, and obtained
representative samples of the soil encountered. "Grab" samples of selected subsurface soil were I
coUected from the backhoe bucket. The subsurface conditi�ns encountered in each of the two 'I
building areas are �ummariz�d belo�n� �I
Soi!Conditions ��
The test pits conducted in the southem buildinQ were scattered around the anticipated Ii
building footprint. These explorations encountered similar soil condfions that generally '
consisted of a thin layer of fill or topsoil extending to a depth of at most, approximately 12 '
inches, beneath which was native, medium-dense sfightly sitty to siliy sand. This native ,
sand was gerterally brown in color and became denser with depth. The test pits in this
building area were excavated to a maximum depth of approximately 6 feet below the
existing grade.
In the northem buildinq, it was oniy possible to excavate test pits in the southem half of the
building, due to the presence of unmarked buried uti(ities in the northem portion of the site.
These explorations encountered up to 2 feet�f ioose, sitty sand fill overfying the old topsoil.
No test pits were excavated in the existing fill stockpile where the depth of fill would likely be
greater. The topsoil beneath the fill was up to approximately 2 feet thidc. Underlying the
topsoil was native, medium-dense slightly silty to silty sand as was encountered in the test
pits in the southem building. The maximum test pit depth in the northem building was 8.5
feet below existing grade. .
GEOTECH CONSULTANTS,INC.
Kanwaljif Dulai JN 08183 '
July 25, 2008 Page 3
No obstructions were revealed by our explorations. However, debris, buried utilities, and old
foundation and slab elements are commonly encountered on sites that have had previous
development. As discussed above, there appears to be several different types of utilities
buried on the site already.
Groundwater Conditions
No groundwater seepage or wet soil conditions were observed in the test pits. Based on
this, we do not anticipate that near surface grouncfwater is present beneath this site within
the explored depth.
The compaction of test pit backfill was not in the scope of our senrices. Loose soil will therefore be
found in the area of the test pits. If this presents a �rcb!em the "ack�i'' v���!� reed ±o he r�mo„��
and replaced with structural fill durina constructior..
CONCLUSIONS AND RECOMMENDATIONS
GENERAL
TH1S SECT/ON CONTAINS A SUMMARY �F CUR STUDY AND FNVDINGS FOR THE PURPOSES OF A
GENER.4� OVERVIEW ONLY. MORE SPECIFIC RECOMMENDATIONS AND CONCLUSIONS ARE
CONTAlNED IN THE REMA/NDER OF THlS REPORT. ANY PARTY RELYING ON TH/S REPORT SHOULD
READ THE ENT(RE DOCUMENT.
The test pits excavated for this study encountered native, medium-dense sands within
approximately 4 feet of the existing ground surface. These soils are shallower in the southern
building area where the grade has already been excavated down approxirnately 2 feet below the
original ground surface. The native sands ars suitable to support the two buildings using
conventional foundations. It will be necessary to excavate all footings through existing fill and
topsoil to reach the mediurr�-dense sands. We recommend that the foundation subgrades be
excavated using a smooth bucket on the excavator or that they be deaned of loosen soil using a
grade bar. Once the subgrades have been sc;raped clean of any loosen soil, the subgrades should
be lightly compacted using a small vibratory sled compactor. If it is necessary to overexcavate
below the planned footing elevations to reach medium-dense, native soils, the overexcavation can
be backfilled using compacted quarry spalls, ballast rodc, 2-to 4inch recyded concrete, or crush
rock. The on-site soils should not be re-used as structural fill undemeath foundations.
It would be prudent to remove the existing fi(I and old topsoil beneath the planned building slab
areas. Any overexcavation resu�ing from this can be backfilled up to the slab grade using
compacted on-site sands. Generally this sand should be placed in {ifts no thicker than 9 to 12
inches and be compacted with a small vibratory roller or a hoe-pack.
It will be importarrt that excavation for buildings not undermine adjacent properties or the
neighboring eastem retaining wall. In general, temporary cuts should be sloped no steeper than
1:1 (Horizotal:Vertical) along the eastem side of the site. The ground in front of ttie e�asting wall
should remain undisturbed for a minimum distanoe of 3 feet from the face of the existing wall
before starting any temporary slope cuts.
The erosion control measures needed during the site developmerrt will depend heavily on the
weather conditions that are encoun#ered. The erosion potential of the sandy soils on the relatively
GEOTECH CONSULTAPfrS,1NC.
Kanwaljit Dulai JN 08183
July 25,2008 Page 4
flat lot is low. We anticipate that a silt fence will be needed around the downslope sides of any
cleared areas. A rocked construction access road should be extended into the site to reduce the
amourrt of soil or mud carried off the property by trucks and equipment. This road should follow the
aiignment of planned pavements, and trucks should not be allowed ta drive off of the rock�overed
areas. Cut slopes and soil stockpiles should be covered with plastic during wet weather. Following
rough grading, it may be necessary to mulch or hydroseed bare areas that wifl not be immediately
covered with landscaping or an impervious surface.
The drainage and/or waterproofing recommendations presented in this report are intended only to
prevent active seepage from flowing through concrete walls or slabs. Even in the absence of active
seepage into and beneath structures, water vapor can migrate through walls, slabs, and floors from
the surrounding soil, and can even be transmitted from slabs and foundation walls due to the
concrete curing proce,ss. Water vapor also results from occupant uses, such as cooking and
bathing. Excessive water vapor trapped withirt structures can result in a variety of undesirable
conditions, including, but not limited to, moisture problems with flooring systems, excessively moist
air within occupied areas, and the growth of molds, fungi, and other biological organisms that may
be harmful to the health of the occupants. The designer or architect must consider the potential
vapor sources and likely occupant uses, and provide sufficient verrtilation, either passive or
mechanical, to prevent a build up of excessive water vapor within the planned structure.
We recommend induding this report, in its entirety, in the project cor�tract documents. This report
should alsa be provided to any future property owners so they witl be aware of our findings and
recommendations.
SEISMIC CONSIDERATIONS �
In accordance with Table 1613.5.2 of the 2006 Intemational Building Code (IBC), the site soil
profile within 100 feet of the ground surFace is best represerrted by Soil Profile Type C (Very Dense
Soil and Soft Rock. The site soils are not susceptible to seismic I'iquefaction because of their
dense nature and/or the absence of near-surface groundwater.
CONVENTIONAL FOUNDATIONS
We recommend that continuous and individual spread footings have minimum widths of 16 and 24
inches, respectively. Exterior footings shou{d also be bottomed at least 18 inches below the iowest
adjacent finish ground surface for protection against frost and erosion. The local building codes
should be reviewed to determine if different footing widths or embedment depths are required.
An alfowable bearing pressure of 3,000 pounds per square foot (psfl is appropriate for footings
supported on competerit native soil. A one-third incxease in this design bearing pressure may be
used when considering short-term wind or seismic loads. For the above design cxiteria, it is
anticipated that the total post-constnaction settlement of footings founded on competent native soil,
or on structural fill up to 5 feet in thickness, �will be less than one inch, with differerrtial settlements
on the order of one-haff inch in a distance of 25 feet along a continuous fo�ting with a un'rform load.
Lateral loads 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 the vertical, embedded portions of the
foundation. For the iatter condition, the foundation must be either poured directly against relatively
GEOTECH CONSULTANTS,INC.
Kanwaljit Dulai JN 08183
July 25,2008 Page 5
levef, undisturbed soil or be surrounded by level structural fill. We recommend using the following
ultimate values for the foundation's resistance fo lateral loading:
. . , �
Coefficient of Friction 0.45
Passive Earth Pressure 300 pcf
Where:(i)pcf Is paunds per cubic foot,and{ii)passive earth
pressure is compuEed using the equivalent fluid density.
If the round in front of a foundation is loose or slo in the assive earth ressure iven above will ��
9 P 9, P p 9
not be appropriate. We recommend maintaining a safety factor ofi at least 1.5 for the foundation's
resisfance to lateral Ioading, when using the above ultimate vafues.
PERMANENT FOUNDATIOIV AIYD RETAIN/IVG WALLS
No ta11 retaining or foundation walls are expected for this project. However, retaining walls
backfi(led on only one side should be designed to resist the lateral earth pressures imposed by the
soi(they retain. The following recommended parameters are far walls that restrain leve! backfll:
; i
,
�I Active Earth Pressure` 35 pcf
� Passive Earth Pressure 300 pcf
� Coefficient of Friction 0.45
Soil Unit Weight 130 pcf
Where: (Q pcf is pounds per cubic foat, and (il) active and
passive earth pressures are computed using the equFvalent flu3d
pressures.
'For a restrained wall that cannot deflect at least 0.002 time.s its
height,a unitortn lateral pressure equa!to 10 psf times the height
of the wall should be ad�d to the above acUve equivalent fluid
pressure.
The values given above are to be used to design permanent foundation and retaining walls only.
The passive pressure given is appropriate for the depth of level structural fill placed in front of a
retaining or foundation wall only. The values for friction and passive resistance are ultimate values
and do not include a safety factor. We recommend a safety factor of at least 1.5 for averturning
and sliding, when using the above values to design the walls. Restrained wall sail parameters
should be utilized for a distance of 1.5 times the wall height from comers or bends in the wa)Is.
This,is intended to reduce the amount of cradcing that can occur where a wall is restrained by a
comer.
The design values given above do not include the effects of any hydrostatic pressures behind the
walis and assume that no surcharges, such as those caused by slopes, vehicles, or adjacent
GEOTECH CONSULTANTS,INC.
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Kanwaljit Dulai JN 08183 ��
July 25, 2008 Page 6
foundations wili be exerted on the walls. If these conditions exist, those pressures should be added
to the above lateral soif pressures. Where sloping backfill is desired behind the walls, we will need �
to be given the wall dimensions and the slope of the backflll in order to provide the appropriate ',
design earth pressures. The surcharge due to traffic loads behind a wall can typically be
accounted for by adding a uniform pressure equal to 2 feet multiplied by the above active fluid '
density.
Wall Pressures Due to Seismic Forces
The surcharge wall loads that could be imposed by an earthquake can be accounted for by
adding a uniform lateral pressure to the above-recommended active pressure. The
recommended surcharge pressure is 7ti pounds per square foot (psfl, where H is the
design retention height of the wall. Using this increased pressure, the safety factor against
sliding and overtuming can be reduced to 1.2 for the seismic analysis.
Heavy construction equipment should not be operated behind retaining and foundation walls within
a distance equal to the height of a wall, unless the walts are designed for the additional fateral
pressures resulting from the equipment. The wall design ciiteria assume that the backfill will be
well-compacted in lifts no thicker than 12 inches. The compaction of backfill near the walls shoufd
be accompfished with hand-operated equipment to prevent the walls from being overloaded by the
higher soil forces that occur during compaction.
DrainaAe and Waterproo�np
Bac[cfilt placed behind retaining or foundation walls should be coarse, free-draining
structural fill containing no organics. This backfill should caritain no more than 5 percent silt
or clay particles and have no gravel greater than 4 inches in diameter. The percentage of
particles passing the No. 4 sieve should be between 25 and 70 percent. If the native sand
is used as backfill, a minimum 12-inch width of free-draining gravel should be placed
against the backfilled retaining walls. For increased protection, drainage oomposites should
be placed along cut slope faces, and the watls should be backfilleri entirely with free-
draining soil. The later section entitled Drainage Considerations should also be reviewed
for recommendations related to subsurtace drainage behind foundation and Fetaining waJts.
The pur�ose of these backfill requirements is to ensure that the design criteria for a
retaining wafl are nat exceeded because of a build-up of hydrostatic pressure behind the
wall. The top 12 to 18 inches of tFte backfilt should consist of a compacted, relatively
impermeable soil or topsoil, or the surFace shouid be paved. The ground surface must also
slope away from backfilled walls to reduce the potentiaf for surtace water to percolate into
the ba�ll. The seckion entitled General Earthwork and Structur�/ Fit1 contains
recommendations regarding the placement and oompaction of structural fill behind retaining
arid foundation walls.
The above recommendations are not intended to waterproof below-grade wa(Is, or to
prevent the formafion of mold, mildew or fungi in interior spaces_ Over time, the
performance of subsurface drainage systems can degrade, subsurtace groundwater flow
patterns can change, and utilities can break or devefop leaks. Therefore, waterproofing
should be provided where future seepage through the walls is not acceptable. This typically
includes limiting cold joints and wall penetrations, and using berrtonite panels or
membranes on the otafside of the wal�s. There are a variefy of different waterproofing
materials and systems, which should be installed by an experienced contractor famiiiar with
GEOTECH CONSULTANTS,INC.
Kanwaljit Dulai JN 08183
July 25,2008 Page 7
the anticipated. construction and subsurtace conditions. Applying a thin coat of asphalt
emulsion to the outside face of a wall is not considered waterproofing, and will only help to
reduce moisture generated from water vapor or capiflary action ftom seeping through the
concrete. As with any project, adequate verrtilation of basement antl crawl space areas is
important to prevent a build up of water vapor that is commonfy transmitted through
concrete walls from the surrounding soil, even when seepage is not present. This is
appropriate even when waterproofing is applied to the outside of foundation and retaining
walls. We recommend that you contact a specialty consultarrt if detailed recommendations
or specifications refated to waterproofing design, or minimizing the potenfral for infestations
of mold and mildew are desired.
SLABS-ON-GRADE
The building floors can be constructed as stabs-on-gracfe atop native sand that underlies the
topsoil, or on structural fill placed above this suitable native soil. The subgrade soil must be in a
firm, non-yielding condition at the time of slab constnaction. Any soft areas encountered should be
excavated and replaced with select, imported structural fill.
Even where the exposed soils appear dry, water vapor will tend to naturally migrate upward through
the soil to the new constructed space above it. All interior slabs-on-grade must be underlain by a
capitlary break or drainage layer consisting of a minimum 4inch thickness of gravel or crushed
rock that has a fines content (peroent passing the No. 200 sieve) of less than 3 percent and a sand
conterrt (percent passing the No. 4 sieve) of no more than 10 percent. As noted by the American
Concrete Institute (ACI} in the Guides for Concrete Floor and Slab Structur�es, proper moisture
protection is desirabie immediately below any on-grade slab that will be covered by tile, wood,
carpet, impermeable floor coverings, or any moisture-sensfive equipmerat or pralucts. ACI also
notes that vapor retarders, such as 6-mif plastic sheeting, are typically used. A vapor retarder is
defined as a material with a permeance of less than 0.3 US perms per square foot (psfl per hour,
as determined by ASTM E 96. It is possible that concrete admixtures may meet this specfication,
although the manufacturers of the admixtures should be consulted. Where plastic sF�eeting is used
under slabs, joints should overlap by at least 6 inches and be sealed with adhesive tape. The
sheeting should extend to the foundation walls for maximum vapor protection. !f no poterrtial for
vapor passage through the slab is desired, a vapor barrier shou{d be used. A vapor barrier, as
defined by ACI, is a product with a water transmission rate of 0.00 perms per square foot per hour
when tested in accordance with ASTM � �6 Re�nfo�ced membranPs ha�.,;ng sealed overla�s ��ar
meet this requirement.
We recommend that the G�i�ifaGtvi, i}�c �C;i,BGi ;i;ai�iiaiS @Il�iilcci, �i�'u" ihC OW!l@C c�ISGUSS it12S�
issues and review recent ACI literature and ASTM E-1643 for installation guidelines and guidanc=
on the use of the protectioNblotter material. Our opinion is th�F �r��th �m��R,;���� � +����� ��-:a
means should be under+.aken to reduce water vapor transmissi�
Foundation drains should be used where {1) crawl spaces or basements wiil �e oeiow a structure,
(2} a slab is below the outside grade, or (3) the outside grade does not slope downward from a
building. Drains should also be plaoed at the base of al! earth-retaining walls. These drains should
be surrounded by at least fi inches of 1-inch-minus, washed rock and then wrapped in non-woven,
geotextile filter fabric (Mirafi 140N, Supac 4NP, or similar material). At its highest poirrt, a
GEOTECH CONSULTANTS,INC.
Kanwaljit Dulai JN U8183
July 25,2008 Page 8
perforated pipe invert should be at least 6 inches below the bottom af a slab floar or the ievel of a
crawl space, and it should be sloped #or drainage. All roof and surface water drains must be kept
separate from the foundation drain system. A typical drain detail is attached to this report as Plate
1. For the best long-term perFormance, perforated PVC pipe is recommended for all subsurface
drains.
As a minimum, a vapor retarder, as defined in the Slabs-On-Grade section, should be provided in '�
any crawl space area to limit the transmission of water vapor from the underlying soifs. Also, an I�
outlet drain is recommended for all crawl spaces to preverrt a build up of any water that may
bypass the footing drains. '
No groundwater was observed during our field work. If seepage is encountered in an excavation, it
sh�uld be drained from the site by directing it through drainage ditches, perforated pipe, or French
drains, or by pumping it from sumps interconnected by shallow connector trenches at the bottom of
the excavation.
The excavation and site should be graded so that surtace water is directed off the site and away
from the tops of slopes. Water should not be a(lowed to stand in any area where foundations,
slabs, or pavements are to be constructed. Final s�e grading in areas adjacent to (a ) buifding(s)
should slope away at least 2 percent, except where the area is paved. Surface drains should be
provided where necessary to prevent ponding of water behind foundation or retaining wails.
GENERAL EARTHWORK AND STRUCTURAL FILL
All building and pavement areas should be stripped of surface vegetation, topsoil, organic soil, and
other deleterious material. The stripped or removed materials should no# be moced with any
materials to be used as stru�tural fill, but they could be used in non-structural areas, such as
landscape beds.
Structural fill is ciefined as any fitl, including utifify backfilt, placed under, or dose to, a building,
behind permanent retaining or foundation watls, or in other areas where the underiying soil needs
to support loads. All structural fill shoufd be placed in horizontal lifts with a moisture content at, or
near, the optimum moisture conterrt. The optimum moisture corrtent is that moisture corrterrt that
results in the greatest compacted dry density. The moisture corrterrt of fill is very importarrt and
must be closely controlled during the fi(ling and compaction process.
The allowable thickness of the fil! lift will depend on the material type selected, the compaction
equipment used, and the number af passes made to compact the lift. The loase lift thickness
should not exceed 12 inches. We recommend testing the fill as it is placed. If the fill is not
sufficientfy campacted, it can be recompacted before another lift is placed. This eliminates the
need to rernove the fill to achieve the required compaction.
GEOTECH CONSULTANTS,INC.
Kanwal��t Dulai JN 08183
July 25,2008 Page 9
The following table presents recommended relative compactions for structural fill:
� � �
- �
, � � .
Beneath slabs or 95%
walkwa s
Filled slopes and behind 90°�
retainin walls
95%for upper 12 inches of
Beneath pavements subgrade; 90%below that
level
Where:Minimum Relative Compaction is the ratio,expressed in
percentages,of the compacted dry density to the maximum dry
denslty, as detertnined in accwdance with ASTM Test
Desigretion D 1557-91(Nlodified Procto►')-
Structural.fill that will be placed in wet weather should consist of a coarse, granular soil with a silt or
clay corrtent of no more than 5 percent. The percentage of particles passing the No. 200 sieve
� should be measured from that portion of soil passing the three-quarter-incfi sieve.
LIMITATIONS �
The conclusions and recommendations contained in this report are based on site conditions as
they existed at the time of our exploration and assume that the soil and groundwater conditions
encountered in the test pits are representative of subsurtace conditions on the s�te. If the
subsurtace conditions encountered during construction are significantly different from those
observed in our explorations, we shfluld be advised at once so that we can review these conditions
and reconsider our recommendations where necessary. Unanticipated soif conditions are ',
commonly encountered on construction sites and cannot be fulty anticipated by merely taking soil
samples in test pits. Subsurface conditions can also vary between exploration locafions. Such
unexpec;ted conditions frequently require making additional expenditures to attain a properly
� constructed project. It is recommended that the owner consider providing a contingency fund to
accommaiate such potential extra costs and risks. This is a standard recommendation for all
projects.
This report has been prepared for the exdusive use of Gurtown Homes, and its representatives, for
specfic application to this project and site. Our conclusions and recommenda#ions are
professional opinions derived in accordance with currerrt standards of practice within the scope of
our services and within buc3get and time constraints. No warranty is expressed or implied. The
scope of our services does not inGude services related to construction safety precautions, and our
recommendations are not intended to direct the contractor's meth�s, techniques, sequences, or
procedures, except as speafically described in our report for consideration in design. Our senrices
also do not include assessing or minimizing the potentia! for bio(ogical hazards, such as mold,
bacteria, mildew and fungi in either the existing or proposed site development.
ADDITIONAL SERVICES
Geotech Consultants, Inc. should be retained to provide geotechnical consultation, testing, and
observation senrices during construction. This is to confirm that subsurtace conditions are
GE07ECH CONSULTANTS,INC.
Kanwaljit Du1ai JN 08183
July 25, 2008 Page 10
consistent with those indicated by our expforation, to evaluate whether earthwork and foundation
construction activities compiy with the genera[ intent of the recommendations presented in this
report, and to provide suggestions fvr design changes in the event subsurFace conditions differ
from those ariticipated prior to the start of construction. However, our work would not include the
supervision or direction of the actual work of the contractor and i�s employees or agents. Also, job
and site safety, and dimensional measurements, will be the responsibiiity of the contractor.
During the construction phase, we will provide geatechnicaf obserrration and testing services when
requested by you or your representatives. Please be aware that we can only document site work
we actually observe. lt is still the responsibility of your contractor or on-site construction team ta
verify that our recommendations are being followed, whether we are present at the site or not.
The folfowing plate is attached to complete this report:
Plate 1 Typical Footing Drain Detail
We appreciate the oppartunity to be of service on this project. !f you have any quesfions, or if we
may be of further service, please do not hesitate to contact us. .
RespectFully submitted,
GEOTECH CONSULTANTS, INC.
, R• Me�►
:�.�.�o�w�ss���'.r�,�
'��� t}' % �,�y ip
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S��NAI.E��
7 Lr o�
�XAIREg ��ji�ii3
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Marc R. McGinnis, P.E.
Principal
MRM:jyb
GEOTECH CONSULTANTS,INC.
Slope backfili away from
foundation. Provide surFace
drains where necessary.
- __�
� Tightline Roof Drain
_ (Do not connect to footing drain}
____�
Backfill '�a_.-
(See text for � :�;, =
requirements) e � o ,;
�
-ca.`'
, ,�
Nonwoven Geotextile �
. � ,;
Filter Fabric ' �
Washed Rock �" Possible Slab
(7/8"min. size) . .
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4" min. �°°°°,°°°� � Vapor Retarder/Barrier and
- Capillary Break/Drainage Layer
(Refer to Report text)
4" Perforated Hard PVC Pipe
(Invert at least 6 inches below
slab or crawl space. Slope to
drain to appropriate outfall.
Place holes downward.) -
NOTES:
(1) In crawl spaces, provide an outlet drain to prevent buildup of water that �
bypasses the perimeter footing drains.
(2} Refer to report text for additional drainage, waterproofing, and slab considerations.
� FOOTING DR.AIN DETAIL
1,.. GEOTECH 972 Edmonds Avenue Northeast
CONSULTANI'S,INC. Renton, Washington
�
Job Date: Sca e: Plate:
�' � 08183 July 2008 Not to Scale �