21-105280_12 Geotechnical Report_12-17-2021-V1RECEIVED
1/3/22
CITY OF FEDERAL WAY
COMMUNITY DEVELOPMENT
Geotechnical Engineering Report
The Commons
Prepared For:
Merlone Geier Partners
457 SW 1481" Street, Suite 202
Burien, WA 98166
Attn: Glenn Goodman
GEOTEST
I,BW-251.5276
Bellingham I Arlington I Oak Harbor
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GeoTest Services, Inc.
The Commons - Federal Way, WA - Revised
J u ly 23, 2019
Project No.19-0193
Merlone Geier Partners
457 SW 1481" Street, Suite 202
Burien, Washington 98166
Regarding: Geotechnical Engineering Report - Revised
The Commons
32000 Block of Pacific Highway South
Federal Way, Washington 98003
Dear Mr. Goodman,
J u ly 23, 2019
GeoTest Project No.19-0193
As requested, GeoTest Services, Inc. (GeoTest) is pleased to submit the following report
summarizing the results of our geotechnical evaluation for the proposed
development at The Commons located on the 32000 Block of Pacific Highway South
in Federal Way, Washington (Vicinity Map, Figure 1). This report has been prepared in
general accordance with the terms and conditions established in our services
agreement dated March 12, 2019 and authorized by Mr. Glen Goodman.
We appreciate the opportunity to provide geotechnical services on this project and
look forward to assisting you during the construction phase. Should you have any
further questions regarding the information contained within the report, or if we may
be of service in other regards, please contact the undersigned.
Respectfully,
GeoTest Services, Inc.
Kurt Parker, L.E.G.
Geotechnical Department Manager
pC A.
Edwardo Garcia, P.E.
Geotechnical Department Manager
Enclosure: Revised Geotechnical Engineering Report
GeoTest Services, Inc. July 23, 2019
The Commons - Federal Way, WA - Revised GeoTest Project No.19-0193
TABLE OF CONTENTS
PURPOSE AND SCOPE OF SERVICES..................................................................................................................................1
PROJECTDESCRIPTION...............................................................................................................................................................1
SITECONDITIONS.............................................................................................................................................................................1
SurfaceConditions.........................................................................................................................................................................1
SubsurfaceSoil Conditions......................................................................................................................................................2
GeneralGeologic Conditions.................................................................................................................................................3
Groundwater..................................................................................................................................................................................... 4
GEOLOGICHAZARDS...................................................................................................................................................................4
LandslideHazard...........................................................................................................................................................................4
ErosionHazard................................................................................................................................................................................4
SeismicHazard.................................................................................................................................................................................5
VolcanicHazard...............................................................................................................................................................................5
CONCLUSIONS AND RECOMMENDATIONS...................................................................................................................6
Site Preparation and Earthwork..........................................................................................................................................7
Filland Compaction.....................................................................................................................................................................7
Reuseof On -Site Soil.............................................................................................................................................................8
StructuralFill...............................................................................................................................................................................8
Compactionof Structural Fill..........................................................................................................................................8
WetWeather Earthwork..........................................................................................................................................................9
Seismic Design Considerations...........................................................................................................................................9
FoundationSupport..................................................................................................................................................................10
AllowableBearing Capacity.............................................................................................................................................11
FoundationSettlement.......................................................................................................................................................11
FloorSupport....................................................................................................................................................................................11
Foundationand Site Drainage...........................................................................................................................................12
Resistanceto Lateral Loads..................................................................................................................................................13
Temporary and Permanent Slopes................................................................................................................................14
Utilities.................................................................................................................................................................................................14
Pavement Subgrade Preparation....................................................................................................................................15
Reuseof Existing Material................................................................................................................................................15
Flexible Pavement Sections - Light Duty..............................................................................................................16
Concrete Pavement Sections........................................................................................................................................16
Stormwater Infiltration Potential......................................................................................................................................16
StormwaterTreatment.......................................................................................................................................................17
Geotechnical Consultation and Construction Monitoring.............................................................................17
USEOF THIS REPORT..................................................................................................................................................................18
REFERENCES...................................................................................................................................................................................20
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The Commons - Federal Way, WA - Revised GeoTest Project No.19-0193
PURPOSE AND SCOPE OF SERVICES
The purpose of this evaluation is to establish general subsurface conditions beneath
the site from which conclusions and recommendations pertaining to project design
can be formulated. Our scope of services includes the following tasks:
• Exploration of soil and groundwater conditions underlying the site by
advancing 8 hollow stem auger borings with a subcontracted drilling service to
evaluate subsurface conditions.
Laboratory testing on representative samples to classify and evaluate the
engineering characteristics of the soils encountered.
• To provide a written report containing a description of subsurface conditions,
exploration logs, findings and recommendations pertaining to site preparation
and earthwork, fill and compaction, seismic design, foundation
recommendations, concrete slab -on -grade construction, foundation and site
drainage, utilities, temporary and permanent slopes, utilities, pavement,
stormwater infiltration feasibility, geotechnical consultation and construction
monitoring.
PROJECT DESCRIPTION
GeoTest understands that there are plans to construct three new single -story retail
buildings and associated infrastructure at the above location. The new structures will
contain a total of approximately 28,300 SF of new retail building space along with
parking stall and drive access. We were provided a conceptual site plan for the
purpose of project planning and report composition.
SITE CONDITIONS
This section includes a description of the general surface and subsurface conditions
observed at the project site during the time of our field investigation. Interpretations
of site conditions are based on the results and review of available information, site
reconnaissance, subsurface explorations, laboratory testing, and previous experience
in the project vicinity.
Surface Conditions
The subject area is presently surfaced with asphalt and contains established drive
lanes and parking. The project site and vicinity are generally level in all directions and
contain retail businesses in an urban environment. The project site is bordered to the
north by South 320t" Street, to the west by Pacific Highway South, and to the east and
south by asphalt parking and drive lanes, with The Commons retail shopping mall
further to the south.The area is sparsely vegetated with landscape plantings including
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various grass lawns, shrubs, hedges and deciduous trees. There was no observed
surface water noted at the time of our exploration.
Photo 1. Site surface conditions taken from the vicinity of B-6 in the north -central area of the project
near South320'hStreet. View looking southwest.
Subsurface Soil Conditions
Subsurface conditions were explored by advancing 8 soil borings (B-1 through B-8) on
April 26, 2019. The explorations were advanced to depths of between 16.5 and 21.5 feet
below ground surface (BGS) using a 6-inch diameter, hollow -stem auger soil drill on a
trailer -mounted assembly. Samples were generally taken at 2.5-foot and 5-foot
intervals. A GeoTest Staff Geologist directed and observed drilling operations and
logged the soils encountered. Upon completion, all of the boring locations were
backfilled with soil tailings and bentonite, and the upper approximately 6 inches of
the boring were capped with compacted cold patch asphalt. Please refer to the
attached Site and Exploration Plan, Figure 2, for approximate boring locations. The
borehole logs can be found in Appendix A (A-1 through A-8) of this report, with
laboratory analysis attached as A-9 and A-10.
Disturbed but representative samples were obtained during drilling by using the
Standard Penetration Test (SPT) procedure in accordance with American Society for
Testing and Materials ASTM D1586 during the explorations. This test and sampling
method consists of driving a standard 2-inch outside -diameter, split -barrel sampler a
distance of18 inches into the soil with a 140-pound hammer free -falling a height of 30
inches. The number of blows for each 6-inch interval is recorded and the number of
blows required to drive the sampler the final 12 inches is known as the Standard
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Penetration Resistance ("N") or blow count. If a total of 50 blows is recorded within
one 6-inch interval, the blow count is recorded as the number of blows for the
corresponding number of inches of penetration. The resistance, or N-value, provides
a measure of the relative density of granular soils or the relative consistency of
cohesive soils; these values are reported on the attached boring logs.
The subject site was generally surfaced by 2 inches of asphalt pavement in locations
tested. Below the pavement surfacing, imported, structural quality fill was found to
about 2.5 feet BGS before encountering native borrow fill soils. The native borrow fill
soils were observed in all locations, in varying thicknesses before encountering native
soil conditions. Native borrow fill soils were encountered to depths between 10 and
16.5 feet BGS. These soils ranged from medium dense to very dense, with occasional
loose intervals, were of variable color and were primarily silty, gravelly sand with
occasional construction debris.
Native soils encountered are interpreted to be glacial till. In majority, the underlying
native soils were dense to very dense, light brown to gray, silty, gravelly sand. The
native soils extended to the full depth of all explorations. The drill -rig generally had
difficultly advancing through this soil horizon and blow counts or N-Values were
commonly over 50 for a one -foot interval.
Photo 2. Drilling in progress at borehole B-6 in the north -central area of the site, adjacent to South 3201h
Street. View looking south.
General Geologic Conditions
General geologic conditions at the site are mapped as glacial till of the Vashon Stade
of the Fraser Glaciation, specifically known as Vashon Till (Booth, 2004). Glacial till
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refers to heterogeneous soils mixed, transported, and deposited directly by a glacier.
Glacial till is generally compact diamicton containing subrounded to well-rounded
clasts in a massive, silt- or sand -rich matrix. Generally, the glacial till is a few meters to
a few tens of meters thick, forming undulatory surfaces. Till typically exhibits excellent
bearing characteristics and low permeability due to its poor grain size sorting and
high density. Areas within this mapped deposit may locally contain peat, non -glacial
sediments, artificial fill and modified lands.
Our on -site explorations indicate that the encountered native subsurface soil
conditions are in accordance with the mapped soil units.
Groundwater
Subsurface water was observed at depths of approximately 10.5 to 19.5 feet below the
existing ground surface at the time of our explorations. We interpret the encountered
water to be perched horizons or transient water conditions that fluctuate seasonally
and with storm events. The Washington State Department of Ecology Weii Report
Viewer indicates that nearby resource protection wells reported for The Commons
shopping mall area in 2016 from depths of 11 to 16 feet BGS were in a dry condition.
The groundwater conditions reported on the exploration logs are for the specific
locations and dates indicated, and therefore may not be indicative of other locations
and/or times. Groundwater levels are variable, and conditions will fluctuate
depending on local subsurface conditions, precipitation, and changes in on -site and
off -site use.
GEOLOGIC HAZARDS
Landslide Hazard
Landslide hazard areas are those locations potentially subject to episodic downslope
movement of a mass of soil or rock. There are no steep slopes mapped in the vicinity
of the project site. As such, no slope related hazards exist for the new development
per the Federal Way Revised Code (FWRC 19.05.070). No mitigation is recommended
for this potential geologic hazard.
Erosion Hazard
According to the FWRC 19.05.070 an erosion hazard area is identified by having a
moderate to severe or severe to very severe rill and inter -rill erosion hazard due to
natural agents such as wind, rain, splash, frost action or stream flow; those areas
containing the following group of soils when they occur on slopes of 15 percent or
greater: Alderwood-Kitsap ("AkF"), Alderwood gravelly sandy loam ("AgD"), Kitsap silt
loam ("KpD"), Everett ("EvD"), and Indianola ("InD"); and those areas impacted by
shoreline and/or stream bank erosion.
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The site is generally level and does not contain slopes greater than 15 percent with the
above -mentioned soil types and are considered not susceptible to rill and inter -rill
erosion; therefore, no mitigation is recommended for potential erosion hazards per
FWRC 19.05.070.
Seismic Hazard
According to the FWRC 19.05.070, seismic hazard areas "are those areas subject to
severe risk of earthquake damage as a result of seismically induced ground shaking,
slope failure, settlement or soil liquefaction, or surface faulting. These conditions occur
in areas underlain by cohesionless soils of low density usually in association with a
shallow groundwater table." Field findings and mapped resources indicate the site is
not susceptible to severe seismic induced settlement, shaking, lateral spreading,
surface faulting or slope failure because of the generally flat topography, dense,
glacially compacted soils and lack of structural fault zones in the vicinity ofthe subject
site.
The site is mapped by Palmer et al., in the Liquefaction Susceptibility Map of King
County, Washington (2004) as having a "very low" liquefaction susceptibility for native
soils. Due to the nature of the near surface fill soils being granular, in a medium dense
or greater condition in majority, and in combination with a relatively low subsurface
water level, GeoTest considers the upper fill soils to be of a low risk for liquefaction
induced settlement. Two locations to the south and west of the proposed
development are mapped as having "low to moderate" susceptibility to liquefaction.
Given the relative density and granular nature of the near surface soils as a whole,
GeoTest does not recommend anyspecific mitigations related to a liquefaction hazard
for the proposed development location.
Volcanic Hazard
The City of Federal Way and vicinity are in proximity to potential volcanic hazards of
the Mount Rainier stratovolcano. Direct volcanic hazards associated in the City of
Federal Way include lahars (volcanic mudflows) and tephra (ash fall), according to the
DNR Geologic Hazards Maps webpage. Lahars are generally described as volcanic
mudflows that can travel long distances from their source volcano. We recommend
no mitigation for this potential geologic hazard based on project elevation and
proximity to the hazard.
Tephra or volcanic ashfall related hazards exist at the subject site, as they do for the
entire Pacific Northwest region, which could be affected by an eruption of Mount
Rainier or other Cascade Range volcanoes. We recommend no additional mitigation
for this type of volcanic hazard, however the client and owner should be aware that
volcanic ash "can pose significant disruption and damage to buildings, transportation,
water and wastewater, power supply, communications equipment, and agriculture,
leading to potentially substantial societal impacts and costs, even at thicknesses of
only a few millimeters or inches. Fine-grained ash, when ingested, can cause health
impacts to humans and animals" according to DNR sources.
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CONCLUSIONS AND RECOMMENDATIONS
Based on the evaluation of the data collected during this investigation, it is our opinion
that the subsurface conditions at the site are suitable for the proposed development,
provided the recommendations contained herein are incorporated into the project
design.
As previously stated, our explorations generally encountered native dense to very
dense, silty, gravelly sand glacial till soils underlying varying depths of medium dense
to very dense native borrow fill from previous development. The native soils will
provide excellent bearing capacity but poor to negligible permeability. Glacial till was
found at depths that are not considered to be cost effective if utilizing traditional
shallow foundation construction techniques.
Our delineation of the existing borrow fill sections was determined in part by
topographic map review, as well as encountering of construction debris at depths of
near 10 feet BGS. The 1949 Poverty Bay, Washington topographic map published by
the USGS depicts the site as having low lying or swampy areas in the southwest area
of the project as well as a seasonal creek channel on the eastern margin. GeoTest
assumes that site was filled to near present grade with locally sourced material during
development of The Commonsshopping mall and other local vicinity areas.
Due to the assumed relatively light loading conditions of the new structures, we
recommend placing new foundations on properly compacted structural fill over the
existing native borrow fill soils found across the site. GeoTest recommends that the
new foundation locations be supported by at least 2 feet of structural fill, following
removal of the existing borrow fill. Geotest also recommends the use of a woven
geotextile fabric such as TenCate® Mirafi® RS280i (or industry equivalent) be placed
at the interface between the existing fill soil and the new imported structural fill for
uniform support across the foundation alignments.
Foundation support may be provided by placing foundations directly on undisturbed
dense to very dense, glacial till encountered at depths ranging between 10.5 and 16.5
feet BGS. Removal of the native borrow fill sections may not be feasible due to the
depth to which they extend and the associated cost of removal and replacement. If it
is the intent of the designer to place foundations in direct contact with the native
glacial till soils, we recommend that a deep foundation system be considered in lieu
of significant overexcavation and removal of existing material. Further
recommendations for deep foundation systems can be made on request.
The majority of on -site near surface soils contain elevated fines content ranging from
20 to 40 percent. We consider the reuse of existing fill soils to be feasible across the
site if the soils are at or within 3 percent of optimum moisture content. Soils with a
fines content greater than 5 to 10 percent can be difficult or impossible to compact to
industry standards when over optimum moisture levels. We recommend existing
soils be reused during the dry season (April through October) or as conditions permit.
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Based on the presence of the uncontrolled and variable density native borrow fill soils,
GeoTest does not recommend that on -site infiltration be incorporated as part of
stormwater design for the proposed development. Low Impact Development
stormwater management with the use of raingardens or bioswales can be considered
by the designer, however existing fill and dense native conditions may dictate the use
of detention or retention systems, depending on final design.
Site Preparation and Earthwork
The portions of the site proposed for new foundation(s), floor slabs, pavement and/or
sidewalk development should be prepared by removing existing pavements, topsoil,
deleterious material and significant accumulations of organics. We recommend that
new foundations be supported by a minimum of 2 feet of structural fill with TenCate®
Mirafi® RS280i (or industry equivalent) geotextile fabric placed at the existing fill
interface before placing new imported fill. Areas planned for floor slabs, pavement and
walkways may be prepared by removing at least 1 foot of existing fill soils and
replacement with structural fill as discussed further herein.
Prior to placement of any foundation elements or structural fill, the exposed subgrade
under all areas to be occupied by soil -supported floor slabs, spread, or continuous
foundations should be recompacted to a firm and unyielding condition. Verification
of compaction can be accomplished through proof rolling with a loaded dump truck,
large self-propelled vibrating roller, or similar piece of equipment applicable to the
size of the excavation. The purpose of this effort is to identify loose or soft soil deposits
so that, if feasible, the soil disturbed during site work can be recompacted.
Proof rolling should be carefully observed by qualified geotechnical personnel. Areas
exhibiting significant deflection, pumping, or over -saturation that cannot be readily
compacted should be overexcavated to firm soil. Overexcavated areas should be
backfilled with compacted granular material placed in accordance with subsequent
recommendations for structural fill. During periods of wet weather, proof rolling could
damage the exposed subgrade. Under these conditions, qualified geotechnical
personnel should observe subgrade conditions to determine if proof rolling is feasible.
Proof rolling may not be feasible for certain locations within excavated footings,
trench areas, or other difficult access zones when using a full-size dump truck or other
large machinery. In this situation, we recommend alternate means of verification such
as nuclear-densometer testing, Dynamic Cone Penetrometer (DCP) testing or soil
probe methods be employed to verify suitability of field conditions.
Fill and Compaction
Structural fill used to obtain final elevations for footings and soil -supported floor slabs
must be properly placed and compacted. In most cases, any non -organic,
predominantly granular soil may be used for fill material provided the material is
properly moisture conditioned prior to placement and compaction, and the specified
degree of compaction is obtained. Fill soil containing topsoil, wood, trash, organic
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material, or construction debris is not suitable for reuse as structural fill and should be
properly disposed offsite or placed in nonstructural areas.
Soils containing more than approximately 5 percent fines are considered moisture
sensitive and are difficult to compact to a firm and unyielding condition when over
the optimum moisture content by more than approximately 2 percent. The optimum
moisture content is that which allows the greatest dry density to be achieved at a
given level of compactive effort.
Reuse of On -Site Soil
The on -site fill soils are considered suitable for reuse as structural fill if free from prior
construction debris and significant organic material and are within 2 percent of
optimum moisture content. As such, we recommend reuse of these soils be limited to
use during the dry season (April through October) or as conditions permit. The
existing fill soils may be used for landscape and other non-structural fill elements.
During the winter wet season, it may be difficult or impossible to reuse the existing fill
soil as structural fill and compact to acceptable standards due to high fines content.
Structural Fill
GeoTest recommends that imported structural fill consist of clean, well -graded sandy
gravel, gravelly sand, or other approved naturally occurring granular material ("pit
run") with at least 30 percent retained on the No. 4 sieve, or a well -graded crushed
rock. Structural fill for dry weather construction may contain up to 10 percent fines
(that portion passing the U.S. No. 200 sieve) based on the portion passing the U.S. No.
4 sieve. The use of an imported fill having more than 10 percent fines may be feasible,
but the use of these soils should generally be reviewed by the design team prior to
the start of construction.
Imported structural fill with less than 5 percent fines should be used during wet
weather conditions. If construction occurs during the wet season or rainy conditions,
soil moisture contents could be high enough that it may be difficult to compact even
clean imported select granular fill to a firm and unyielding condition. Soils with an
over -optimum moisture content should be scarified and dried back to a suitable
moisture content during periods of dry weather or removed and replaced with drier
structural fill.
Compaction of Structural Fill
Structural fill should be placed in horizontal lifts. The structural fill must measure 8 to
10 inches in loose thickness and be thoroughly compacted with machinery
appropriate to the task. All structural fill placed under load bearing areas should be
compacted to at least 95 percent of the maximum dry density, as determined using
test method ASTM D1557. The top of the compacted structural fill should extend
outside all foundations and other structural improvements a minimum distance
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equal to the thickness of the fill. We recommend that compaction be tested after
placement of each lift in the fill zones.
Wet Weather Earthwork
The existing fill and native soils are particularly susceptible to degradation during wet
weather. As a result, it may be difficult to control the moisture content of site soils
during the wet season. If construction takes place during wet weather, GeoTest
recommends that structural fill consist of imported, clean, well -graded sandy gravel
or gravelly sand with low fines content as described above. If fill is to be placed or
earthwork is to be performed in wet conditions, the contractor may reduce soil
disturbance by:
• Limiting the size of areas that are stripped of topsoil and left exposed
• Accomplishing earthwork in small sections
• Limiting construction traffic over unprotected soil
• Sloping excavated surfaces to promote runoff
• Limiting the size and type of construction equipment used
• Providing gravel 'working mats' over areas of prepared subgrade
• Removing wet surficial soil prior to commencing fill placement each day
• Sealing the exposed ground surface by rolling with a smooth drum compactor
or rubber -tired roller at the end of each working day
• Providing up -gradient perimeter ditches or low earthen berms and using
temporary sumps to collect runoff and prevent water from ponding and
damaging exposed subgrades
Seismic Design Considerations
The Pacific Northwest is seismically active and the site could be subject to movement
from a moderate or major earthquake. Consequently, moderate levels of seismic
shaking should be accounted for during the design life of the project, and the
proposed structure should be designed to resist earthquake loading using
appropriate design methodology.
For structures designed using the seismic design provisions of the 2015 International
Building Code, the existing fill and glacial till soils underlying the site within the upper
100 feet is classified as Site Class D, according to 2010 ASCE -7 Standard -Table 20.3-1,
Site Class Definitions. The corresponding values for calculating a design response
spectrum for the soil profile type is considered appropriate for the site.
Please reference the following values for seismic structural design purposes:
Conterminous 48 States - 2015 International Building Code
Zip Code 98003
Central Latitude = 47.3145, Central Longitude =-122.3120
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Short Period (0.2 sec) Spectral Acceleration
Maximum Considered Earthquake (MCE) Value of Ss=1.294 (g)
Site Response Coefficient, Fa = 1 (Site Class D)
Adjusted spectral response acceleration for Site Class D, SMs = Ssx Fa = 1.294 (g)
Design spectral response acceleration for Site Class D, Sos = 2/3 x SMS= 0.862 (g)
One Second Period (1 sec) Spectral Acceleration
Maximum Considered Earthquake (MCE) Value of S, = 0.496 (g)
Site Response Coefficient, F = 1.504 (Site Class D)
Adjusted spectral response acceleration for Site Class D, SM, = Six Fv = 0.746 (g)
Design spectral response acceleration for Site Class D, So, = 2/3 x SM,= 0.497 (g)
Foundation Support
Continuous or isolated spread footings founded on two feet of properly compacted
structural fill placed over the native borrow fill soils can provide foundation support
for the proposed improvements. We recommend that a woven geotextile fabric, such
as Tencate® Mirafi® RS280i (or industry equivalent), be placed directly on native
borrow fill soils prior to the placement of structural fill. GeoTest recommends that the
existing fill be recompacted prior to the placement of geotextile fabric. We
recommend that qualified geotechnical personnel confirm that suitable bearing
conditions have been reached prior to placement of geotextile fabric, structural fill or
foundation formwork.
To provide proper support, GeoTest recommends that any pavement, construction
debris, deleterious material or soil with organic content greater than 3 percent be
removed from beneath the building foundation area(s) and be replaced with properly
compacted structural fill as described in the Fi//and Compaction section of this report.
Localized overexcavation, if necessary, can be backfilled to the design footing
elevation with structural fill or lean concrete.
The limits of the excavation should extend laterally beyond the edge of each side of
the footing a distance equal to the depth of the excavation below the base of the
footing. If lean concrete is used to backfill the excavation, the limits of the excavation
need only extend a nominal distance beyond the width of the footing. In addition,
GeoTest recommends that foundation elements for the proposed structure(s) bear
entirely on similar soil conditions to help prevent differential settlement from
occurring.
Continuous and isolated spread footings should be founded 18 inches, minimum,
below the lowest adjacent final grade for freeze/thaw protection. The footings should
be sized in accordance with the structural engineer's prescribed design criteria and
seismic considerations.
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Allowable Bearing Capacity
Assuming the above foundation support criteria are satisfied, continuous or isolated
spread footings founded on geotextile supported, compacted structural fill placed
directly over existing fill soils may be proportioned using a net allowable soil bearing
pressure of up to 2,000 pounds per square foot (psf).
The "net allowable bearing pressure" refers to the pressure that can be imposed on
the soil at foundation level. This pressure includes all dead loads, live loads, the weight
of the footing, and any backfill placed above the footing. The net allowable bearing
pressure may be increased by one-third for transient wind or seismic loads.
Foundation Settlement
Settlement of shallow foundations depends on foundation size and bearing pressure,
as well as the strength and compressibility characteristics of the underlying soil. If
construction is accomplished as recommended and at the maximum allowable soil
bearing pressure, GeoTest estimates the total settlement of building foundations to
be less than one inch. Differential settlement between two adjacent load -bearing
components supported on competent soil is estimated to be less than one half the
total settlement.
Floor Support
Conventional slab -on -grade floor construction is feasible for the planned site
improvements. Floor slabs may be supported on properly placed and compacted
structural fill placed over properly prepared native soil. We recommend that floor
slabs be supported by at least 1 foot of imported structural fill, which may include a
capillary break as addressed below. Prior to placement of structural fill, the native
borrow fill soil should be recompacted if disturbed and proof -rolled or otherwise
verified as firm and unyielding as recommended in the Site Preparation and
Earth work section of this report.
Floor slabs may be supported by existing fill soils that were found at our borehole
locations below the asphalt surfacing, however the potential for differential
settlement exists and may be mitigated by placing 6 inches of structural fill below 6
inches of capillary break material prior to concrete placement. GeoTest recommends
verification of existing conditions by shallow potholing prior to placement of imported
fill and concrete elements if proof rolling is not feasible. All existing fill soils to remain
in place for slab support should be recompacted with proper equipment such as a
large vibrating roller or hoe -pack prior to new fill placement.
GeoTest recommends that interior concrete slab -on -grade floors be underlain with at
least 6 inches of clean, compacted, angular free -draining gravel. The gravel should
contain less than 3 percent passing the U.S. Standard No. 200 sieve (based on a wet
sieve analysis of that portion passing the U.S. Standard No. 4 sieve). The purpose of
this gravel layer is to provide uniform support for the slab, provide a capillary break,
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and act as a drainage layer. To help reduce the potential for water vapor migration
through floor slabs, a continuous 10 to 15-mil minimum thickness polyethylene sheet
with tape -sealed joints should be installed below the slab to serve as an impermeable
vapor barrier. The vapor barrier should be installed and sealed in accordance with the
manufacturer's instructions.
Exterior concrete slabs -on -grade, such as sidewalks, may be supported directly on
properly placed and compacted structural fill or existing fill; however, long-term
performance will be enhanced if exterior slabs are placed on a layer of clean, durable,
well -draining granular material.
Foundation and Site Drainage
GeoTest understands that new development will likely utilize the existing drainage
system in part and incorporate additional stormwater controls, as necessary, on
completion of the final design and site layout. Positive surface gradients should be
provided adjacent to the proposed building(s) to direct surface water away from the
structure and toward suitable drainage facilities. Roof drainage should not be
introduced into the perimeter footing drains but should be separately discharged
directly to the stormwater collection system or similar municipality -approved outlet.
Pavement and sidewalk areas should be sloped, and drainage gradients should be
maintained to carry surface water away from the buildings toward an approved
stormwater collection system. Surface water should not be allowed to pond and soak
into the ground surface near buildings or paved areas during or after construction.
Construction excavations should be sloped to drain to sumps where water from
seepage, rainfall, and runoff can be collected and pumped to a suitable discharge
facility.
To reduce the potential for groundwater and surface water to seep into interior
spaces, GeoTest recommends that an exterior footing drain system be constructed
around the perimeter of new building foundations as shown in the Typical Footing
Drain Section (Figure 3) of this report. The drain should consist of a perforated pipe
measuring 4 inches in diameter at minimum, surrounded by at least 12 inches of
filtering media. The pipe should be sloped to carry water to an approved collection
system.
The filtering media may consist of open -graded drain rock wrapped in a nonwoven
geotextile fabric such as Mirafi 140N (or industry equivalent). For foundations
supporting retaining walls, drainage backfill should be carried up the back of the wall
and be at least 12 inches wide. The drainage backfill should extend from the
foundation drain to within approximately 1 foot of the finished grade and consist of
open -graded drain rock containing less than 3 percent fines by weight passing the
U.S. Standard No. 200 sieve. The invert of the footing drain pipe should be placed at
approximately the same elevation as the bottom of the footing or 12 inches below the
adjacent floor slab grade, whichever is deeper, so that water will be contained. This
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GeoTest Project No.19-0193
process prevents water from seeping through walls or floor slabs. The drain system
should include cleanouts to allow for periodic maintenance and inspection.
Resistance to Lateral Loads
The lateral earth pressures that develop against foundation walls will depend on the
method of backfill placement, degree of compaction, slope of backfill, type of backfill
material, provisions for drainage, magnitude and location of any adjacent surcharge
loads, and the degree to which the wall can yield laterally during or after placement
of backfill. If the wall is allowed to rotate or yield so the top of the wall moves an
amount equal to or greater than about 0.001 to 0.002 times its height (a yielding wall),
the soil pressure exerted comprises the active soil pressure. When a wall is restrained
against lateral movement or tilting (a nonyielding wall), the soil pressure exerted
comprises the at rest soil pressure. Wall restraint may develop if a rigid structural
network is constructed prior to backfilling or if the wall is inherently stiff.
GeoTest recommends that yielding walls under drained conditions be designed for
an equivalent fluid density of 35 pounds per cubic ft (pcf) for structural fill and 40 pcf
for existing fill or native material in active soil conditions. Nonyielding walls under
drained conditions should be designed for an equivalent fluid density of 55 pcf for
structural fill and 60 pcf for existing fill or native material in at -rest conditions. Design
of walls should include appropriate lateral pressures caused by surcharge loads
located within a horizontal distance equal to or less than the height of the wall. For
uniform surcharge pressures, a uniformly distributed lateral pressure equal to 35
percent and 50 percent of the vertical surcharge pressure should be added to the
lateral soil pressures for yielding and nonyielding walls, respectively.
Passive earth pressures developed against the sides of building foundations, in
conjunction with friction developed between the base of the footings and the
supporting subgrade, will resist lateral loads transmitted from the structure to its
foundation. For design purposes, the passive resistance of well -compacted structural
fill placed against the sides of foundations is equivalent to a fluid with a density of 250
pounds per cubic foot. If utilizing native soil as backfill, the passive resistance of well -
compacted existing or native fill placed against the sides of foundations is equivalent
to a fluid with a density of 250 pounds per cubic foot. The recommended value
includes a safety factor of about 1.5 and is based on the assumption that the ground
surface adjacent to the structure is level in the direction of movement for a distance
equal to or greater than twice the embedment depth.
The recommended value also assumes drained conditions that will prevent the
buildup of hydrostatic pressure in the compacted fill. Foundation walls should include
a drain system constructed in general accordance with the recommendations
presented in the Foundation and Site Drainage section of this report. In design
computations, the upper 12 inches of passive resistance should be neglected if the soil
is not covered by floor slabs or pavement. If future plans call for the removal of the soil
providing resistance, the passive resistance should not be considered.
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Ana I Iowa blecoefficient of base friction of 0.35, applied to vertical dead loads only, may
be used between the underlying imported granular structural fill and the base of the
footing. We recommend an allowable coefficient of friction of 0.30 for native soil or
existing fill. If passive and frictional resistance are considered together, one half the
recommended passive soil resistance value should be used since larger strains are
required to mobilize the passive soil resistance as compared to frictional resistance. A
safety factor of about 1.5 is included in the base friction design value. GeoTest does
not recommend increasing the coefficient of friction to resist seismic or wind loads.
Temporary and Permanent Slopes
Actual construction slope configurations and maintenance of safe working
conditions, including temporary excavation stability, should be the responsibility of
the contractor, who is able to monitor the construction activities and has direct
control over the means and methods of construction. All applicable local, state, and
federal safety codes should be followed. All open cuts should be monitored during
and after excavation for any evidence of instability. If instability is detected, the
contractor should flatten the side slopes or install temporary shoring.
Temporary excavations in excess of 4 ft should be shored or sloped in accordance with
Safety Standards for Construction Work Part N, WAC 296-155-66403. Temporary
unsupported excavations in the fill and native soil encountered at the project site are
classified as a Type B soil according to WAC 296-155-66401 and may be sloped as steep
as 1:1 (Horizontal: Vertical). All soils encountered are classified as Type C soil in the
presence of groundwater seepage and shall be sloped at 1.5:1 (H:V). Flatter slopes or
temporary shoring may be required in areas where groundwater flow is present and
unstable conditions develop.
Temporary slopes and excavations should be protected as soon as possible using
appropriate methods to prevent erosion during periods of wet weather.
We recommend that permanent cut or fill slopes be designed for inclinations of 2H:1V
or flatter. Sloped areas that contain ponds, reservoirs or other water
retaining/detaining structures shall be designed for inclinations of 3H:1V or flatter
geometry. All permanent slopes should be vegetated or otherwise protected to limit
the potential for erosion as soon as practical after construction.
Utilities
Utility trenches must be properly backfilled and compacted to reduce cracking or
localized loss of foundation, slab, or pavement support. Excavations for new shallow
underground utilities are expected to be placed within very dense glacial till soils or in
existing fill, dependent on elevation and location.
Trench backfill in improved areas (beneath structures, pavements, sidewalks, etc.)
should consist of structural fill as defined in the Fill and Compaction section of this
report and may consist of imported, existing or native soils. The selection of soil
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GeoTest Project No.19-0193
material for trench backfill will depend on moisture contents and general seasonal
conditions. Outside of improved areas, trench backfill may consist of reused native
material or existing fill provided the backfill can be compacted to the project
specifications. Trench backfill should be placed and compacted in general
accordance with the recommendations presented in the Fill and Compaction section
of this report.
Surcharge loads on trench support systems due to construction equipment,
stockpiled material, and vehicle traffic should be included in the design of any
anticipated shoring system. The contractor should implement measures to prevent
surface water runoff from entering trenches and excavations. In addition, vibration as
a result of construction activity and traffic may cause caving of the trench walls.
The contractor is responsible for trench configurations. All applicable local, state, and
federal safety codes should be followed. All open cuts should be monitored by the
contractor during excavation for any evidence of instability. If instability is detected,
the contractor should flatten the side slopes or install temporary shoring. If
groundwater or groundwater seepage is present, and the trench is not properly
dewatered, the soil within the trench zone may be prone to caving, channeling, and
running. Trench widths may be substantially wider than under dewatered conditions.
Pavement Subgrade Preparation
The final design and lateral extent of new pavements at the project site is unknown at
present. We assume that some areas of the project site will be designed for new
pavements, while other locations may be designated for resurfacing by crack/chip
seal, grind and overlay or other similar methods. Some locations are anticipated to
incorporate new imported fill, while other areas may be suited to use the in -place near
surface fill material typically encountered in the upper 2 feet for asphalt pavement
support. The following recommendations are meant as a guideline for the design
engineer to develop final pavement sections in accordance with current codes and
standards.
Reuse of Existing Material
We understand that the reuse of the existing gravel base material is being considered
by the design team for parking and driveway subgrade support. Soils explored in
boreholes B-1 through B-8 were similar in composition in the upper 2 to 2.5 feet and
consisted of generally medium dense, brown, dry to damp, silty, gravelly sand. These
near surface soils were considered to be of structural fill quality and, in our opinion,
are suitable for reuse as parking subgrade soil provided that they are placed and/or
remedially compacted to structural fill requirements per the plans and specifications.
During construction and where site grading lowers the site by more than 2 vertical
feet, we recommend that the material being considered for reuse be separated from
the underlying native borrow fill and stockpiled separately. GeoTest should observe
stripping and stockpiling operations in order to document issues or concerns with the
stripping process. GeoTest is specifically concerned about the mixing of the "clean",
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low silt content structural fill quality materials and the siltier borrow fill materials at
depth. After the near -surface soils have been appropriately stripped and stockpiled,
they can be placed and compacted as structural fill per our report. In areas where the
near -surface soils are left in place and remedially compacted to structural fill
requirements, GeoTest should perform suitable testing methods such as nuclear
densometer testing or proof roll observation to confirm that the required densities per
the plans and specifications are obtained.
Flexible Pavement Sections- Light Duty
If utilized within light vehicle parking and driveway areas, we recommend a standard,
or "light duty", pavement section consist of 2 inches of Class 1/2-inch HMA asphalt
above 2 inches of Crushed Surfacing Top Course (CSTC) meeting criteria set forth in
the Washington State Department of Transportation (WSDOT) Standard Specification
9-03.9(3). The base material for the road section should consist of "gravel base" which
may include 8 inches of gravel borrow (with 100% passing the 2-inch sieve) or 6 inches
of Crushed Surfacing Base Bourse (CSBC) as classified by WSDOT 9-03.9(3) Standards
and Specifications.
Concrete Pavement Sections
Concrete pavements could be used for access drives, parking areas, sidewalks, aprons
and other features such as garbage enclosures. Design of concrete pavements is a
function of concrete strength, reinforcement steel, and the anticipated loading
conditions for the roads. For design purposes, a vertical modulus ofsubgrade reaction
of 200 pounds per cubic inch (pci) should be expected for concrete elements
constructed over properly placed and compacted Structural Fill. GeoTest expects that
concrete pavement sections, if utilized, will be at least 4 inches thick and be founded
on a minimum of 6 inches of compacted gravel base. The design of concrete access
and parking areas will need to be performed by a structural engineer. GeoTest
recommends that subgrade soils supporting concrete pavement sections include
minor grade changes to allow for passive drainage away from the pavement.
GeoTest is available to further consult, review and/or modify our pavement section
recommendations based on further discussion and/or analysis with the project
team/owner. The above pavement sections are initial recommendations and may be
accepted and/or modified by the site civil engineer based on the actual finished site
grading elevations and/or the owner's preferences.
Stormwater Infiltration Potential
Based on the presence of the uncontrolled and variable density native borrow fill soils
overlying dense to very dense native conditions, GeoTest does not recommend that
on -site Stormwater infiltration be incorporated as part of the design for the proposed
development.The designer mayconsider Low Impact Development (LID) design such
as raingardens or bioswales be incorporated in combination with detention facilities.
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Stormwater Treatment
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GeoTest Project No.19-0193
The stormwater facilities on -site may require some form of pollutant pretreatment
with an amended soil prior to on -site infiltration or offsite discharge. The reuse of on -
site soil is often the most sustainable and cost-effective method for pollutant
treatment purposes. Cation exchange capacities, organic contents, and pH of site
subsurface soilswere also tested to determine possible pollutant treatment suitability.
Cation exchange capacity, organic content, and pH tests were performed by
Northwest Agricultural Consultants on four soil samples collected from the
explorations shown in Table 1. A summary of the laboratory test results is presented
below.
TABLET
Cation Exchange Capacity, Organic Content, and pH Laboratory Test
Results
Test Pit
Sample
Geologic
Cation Exchange
Organic
Depth
Capacity
Content
pH
ID
(ft)
Unit
(meq/100 grams)
N
Native
B-3
2.5
Fill
5.8
0.83
7.0
Native
B-4
2.5
Fill
6.3
1.91
7.1
Native
B-4
5.0
Fill
6.3
2.10
6.5
Native
B-7
5.0
Fill
13.0
5.06
5.9
Suitability for onsite pollutant treatment is determined in accordance with SSC-6 of
the 2012 Washington State Department of Ecology Storm water Management Manual
for Western Washington. Soils with an organic content of greater than or equal to 1
percent and a cation exchange capacity of greater than or equal to 5 meq/100 grams
are characterized as suitable for stormwater treatment.
Based on the results shown in Table 1, soils within the upper 5 feet are generally meet
the organic and CEC criteria. However, due to the elevated fines content, variable
construction debris volume and potential for low to negligible infiltration, the owner
may elect to import amended soils with the desired properties for planned treatment
facilities. GeoTest is available to perform additional laboratory testing as part of an
expanded scope of services.
Geotechnical Consultation and Construction Monitoring
GeoTest recommends that we be involved in the project design review process. The
purpose of the review is to verify that the recommendations presented in this report
are understood and incorporated in the design and specifications.
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We also recommend that geotechnical construction monitoring services be provided.
These services should include observation by GeoTest personnel during structural fill
placement, compaction activities and subgrade preparation operations to confirm
that design subgrade conditions are obtained beneath the areas of improvement.
Periodic field density testing should be performed to verify that the appropriate
degree of compaction is obtained. The purpose of these services is to observe
compliance with the design concepts, specifications, and recommendations of this
report. In the event that subsurface conditions differ from those anticipated before
the start of construction, GeoTest Services would be pleased to provide revised
recommendations appropriate to the conditions revealed during construction.
GeoTest is available to provide a full range of materials testing and special inspection
during construction as required by the local building department and the
International Building Code. This may include specific construction inspections on
materials such as reinforced concrete, reinforced masonry, wood framing and
structural steel. These services are supported by our fully accredited materials testing
laboratory.
USE OF THIS REPORT
GeoTest Services has prepared this report for the exclusive use of Merlone Geier
Partners and their design consultants for specific application to the design of the
proposed The Commons development located at the 32000 Block of Pacific Highway
South in Federal Way, Washington. Use of this report by others is at the user's sole
risk. This report is not applicable to other site locations. Our services are conducted
in accordance with accepted practices of the geotechnical engineering profession; no
other warranty, express or implied, is made as to the professional advice included in
this report.
Our site explorations indicate subsurface conditions at the dates and locations
indicated. It is not warranted that these conditions are representative of conditions
at other locations and times. The analyses, conclusions, and recommendations
contained in this report are based on site conditions to the limited depth and time of
our explorations, a geological reconnaissance of the area, and a review of previously
published geological information for the site. If variations in subsurface conditions are
encountered during construction that differs from those contained within this report,
GeoTest should be allowed to review the recommendations and, if necessary, make
revisions. If there is a substantial lapse of time between submission of this report and
the start of construction, or if conditions change due to construction operations at or
adjacent to the project site, we recommend that we review this report to determine
the applicability of the conclusions and recommendations contained herein.
The earthwork contractor is responsible to perform all work in conformance with all
applicable WISHA/OSHA regulations. GeoTest Services, Inc. is not responsible for job
site safety on this project, and this responsibility is specifically disclaimed.
IN
GeoTest Services, Inc.
The Commons - Federal Way, WA - Revised
J u ly 23, 2019
GeoTest Project No.19-0193
Attachments: Figure 1
Vicinity Map
Figure 2
Site and Exploration Plan
Figure 3
Typical Footing and Wall Drain Section
Figure 4
Soil Classification System and Key
Figures S-12
Field Exploration Logs
Figures13-14
Laboratory Testing
Attached
NW Agricultural Consultants Results
Attached
Limitations and Use of This Report
WE
GeoTest Services, Inc.
019
The Commons- Federal Way, WA - Revised July 23, GeoTest Project No. 19-01930193
REFERENCES
Bakeman, S., Dan, G., Howie, D., Killelea, J., Labib, F., & Ed, O. (n.d.). 2012 Stormwater Management
Manual for Western Washington, as Amended in December 2014 (The 2014 SWMMWW) (pp. 1-1042)
(United States, Washington State Department of Ecology).
Booth, D. B.; Waldron, H. H.; Troost, K. G., 2004, Geoiogicmap of the Poverty Bay 7.5'quadrang/e,
King and Pierce Counties, Washington: U.S. Geological Survey Scientific Investigations Map 2854,1 sheet,
scale 1:24,000.
Federal Way Revised Code - Zoning and Development Code - Definitions, §§ 19.05 (2019).
Palmer et al., 2004. Liquefaction SusceptibiiityMap of King County, Washington [Map].
Washington State Department of Natural Resources, Division of Geology and Earth Resources, Open
File Report 2004-20
Structural Engineers Association of California/ Office of Statewide Health, Planning and
Development (SEAOC/OSH PD) Seismic Design Maps Tool, Retrieved May 2019 from
https.//seismicmaps.org
United States Geological Survey, Department of the Interior, 7.5-Minute Topographic Map of
Poverty Bay, Washington (1949-2017) Retrieved May 2019 from https://store.usgs.gov/map-locator
Washington Geologic Information Portal. (n.d.). Retrieved May 2019, from
https-//geologyportal.dnr.wa.gov/
Washington State Department of Ecology. (n.d.). We#Report Viewer, Retrieved May 2019 from
https://fortress.wa.goc/ecy/wel cconstruction/ma p
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Date: 5-20-19 By: ZC Scale: As Shown Project
GEOTEST SERVICES, INC. VICINITY MAP 19-0193
741 Marine Drive
Bellingham, WA 98225 THE COMMONS Figure
phone: (360) 733-7318 PACIFIC HIGHWAY SOUTH
fax: (360) 733-7418 FEDERAL WAY, WA 98406 1
_ ' f�
Atd
B-# = Approximate Boring Location
Date: 5-20-19 By: ZC Scale: As Shown Project
741 Marine Drive
GEOTESERVICES, INC. SITE AND EXPLORATION PLAN 19-0193
100 Feet Bellingham, WA 98225 THE COMMONS Figure
N phone: (360) 733-7318 PACIFIC HIGHWAY SOUTH
fax: (360) 733-7418 FEDERAL WAY, WASHINGTON 2
SHALLOW FOOTINGS WITH INTERIOR SLAB -ON -GRADE
• Typical Framing
Compacted Impervious Soil • , • , • ,
(12 inch minimum) , Floor Slab
or Pavement •
(2 inch minimum) ���::.
,' ,' ,'RVaDor
... . . ........�.�.,<tE';-.I.I.I..,.,.,.,.,.,.,.,.,',',',"a'
Barrier
Slope to drain away
,
from structure.
.f.r.f.f.r.f.f.r.f.f.r.f.f.r.
,' ,' ,'
�. �.,.
• ,' ,' ,' /
Coarse Gravel Capillary Break
inch minimum typically clear crushed)
Suitable Soil
' �' �' �' '•
Free Draining Sand
' ' ' and Gravel Fill
Approved Non -woven
• •
Geotextile Filter Fabric
(18 inch minimum fabric lap)
Suitable Soil
Drainage Material
(Drain Rock or Clear
Crushed Rock w/no fines)
Appropriate Waterproofing
Applied to Exterior of Wall
Four Inch Diameter, Perforated, Rigid PVC Pipe
(Perforations oriented down, wrapped in non -woven
geotextile filter fabric, directed to suitable discharge)
Notes:
Footings Should be properly buried for frost protection in accordance with
International Building Code or local building codes
(Typically 18 inches below exterior finished grades)
The footing drain will need to be modified from this typical drawing to fit the
dimensions of the planned monolithic footing and slab configuration
Date: 5-22-19 By: ZC Scale: None Project
741 Marine Drive
GEOTESERVICES, INC. TYPICAL FOOTING & WALL DRAIN SECTION 19-0193
Bellingham, WA 98225 THE COMMONS Figure
phone: (360) 733-7318 PACIFIC HIGHWAY SOUTH
fax: (360) 733-7418 FEDERAL WAY, WA 3
MAJOR
DIVISIONS
Soil Classification System
Uscs
GRAPHIC LETTER
SYMBOL SYMBOL
TYPICAL
DESCRIPTIONSt't(2)
GRAVEL AND
CLEAN GRAVEL
° o o °o; o
GW
Well -graded gravel; gravel/sand mixture(s); little or no fines
p c. p �? o
GP
GRAVELLY SOIL
(Little or no fines)
Poorly graded gravel; gravellsand mixture(s); little or no fines
O 'N
m y
° ° .
GRAVEL WITH FINES
GM
.a m
m
(More than 50% of
coarse fraction retained
Silty gravel; gravel/sand/silt mixture(s)
W o
on No. 4 sieve)
(Appreciable amount of
fines)
Clayey
GC
Q o N
gravel; gravel/sand/clay mixture(s)
3 LO z
w
SAND AND
CLEAN SAND
$W
Well -graded sand; gravelly sand; little or no fines
CO t
QSP
SANDY SOIL
(Little or no fines)
Poorly graded sand; gravelly sand; little or no fines
SAND WITH FINES
SM
O 2
U v@
(More than 50% of
coarse fraction passed
Silty sand; sand/siltmixture(s)
SC
through No. 4 sieve)
(Appreciable amount of
fines)
Clayey sand; sand/clay mixture(s)
ML
Inorganic silt and very fine sand; rock flour; silty or clayey fine
0 m
SILT AND CLAY
sand or clayey silt with slight plasticity
C�'
O' .N
Inorganic clay of low to medium plasticity; gravelly clay; sandy
E N
(Liquid limit less than 50)
clay; silty clay; lean clay
QL
LLI o 0
z o z
Organic silt; organic, silty clay of low plasticity
Q N (0 ill
:F;
MH
Inorganic silt; micaceous or diatomaceous fine sand
(5 t
SILT AND CLAY
CH
w v m
E
Inorganic clay of high plasticity; fat clay
0
(Liquid limit greater than 50)
OH
Organic clay of medium to high plasticity; organic silt
HIGHLY ORGANIC SOIL
PT
Peat; humus; swamp soil with high organic content
GRAPHIC LETTER
OTHER MATERIALS SYMBOL SYMBOL TYPICAL DESCRIPTIONS
PAVEMENT
AC Or PC
Asphalt concrete pavement or Portland cement pavement
ROCK
RK
Rock (See Rock Classification)
WOOD
WD
Wood, lumber, wood chips
DEBRIS
O O O
DB
Construction debris, garbage
Notes: 1. Soil descriptions are based on the general approach presented in the Standard Practice for Description and Identification of Soils (Visual -Manual Procedure),
as outlined in ASTM D 2488. Where laboratory index testing has been conducted, soil classifications are based on the Standard Test Method for Classification
of Soils for Engineering Purposes, as outlined in ASTM D 2487.
2. Soil description terminology is based on visual estimates (in the absence of laboratory test data) of the percentages of each soil type and is defined as follows:
Primary Constituent: > 50% - "GRAVEL," "SAND," "SILT," "CLAY," etc.
Secondary Constituents: > 30% and < 50% - "very gravelly," "very sandy," "very silty," etc.
> 12% and < 30% - "gravelly," "sandy," "silty," etc.
Additional Constituents: > 5% and < 12% -"slightly gravelly," "slightly sandy," "slightly silty," etc.
< 5% - "trace gravel," "trace sand," "trace silt," etc., or not noted.
Drilling and Sampling Key
Field and Lab Test Data
SAMPLE NUMBER & INTERVAL SAMPLER TYPE
Code Description
Code
Description
Sample Identification Number a 3.25-inch O.D., 2.42-inch I.D. Split Spoon
PP = 1.0
Pocket Penetrometer, tsf
b 2.00-inch O.D., 1.50-inch I.D. Split Spoon
TV = 0.5
Torvane, tsf
Recovery Depth Interval c Shelby Tube
PID = 100
Photoionization Detector VOC screening, ppm
1�14-- Sample Depth Interval d Grab Sample
W = 10
Moisture Content, %
J e Other - See text if applicable
D = 120
Dry Density, pcf
Portion of Sample Retained 1 300-lb Hammer, 30-inch Drop
-200 = 60
Material smaller than No. 200 sieve, %
for Archive or Analysis 2 140-lb Hammer, 30-inch Drop
GS
Grain Size - See separate figure for data
3 Pushed
AL
Atterberg Limits - See separate figure for data
4 Other - See text if applicable
GT
CA
Other Geotechnical Testing
Chemical Analysis
Groundwater
L7 Approximate water elevation at time of drilling (ATD) or on date noted. Groundwater
ATD levels can fluctuate due to precipitation, seasonal conditions, and other factors.
e oTe ST
B-1
SAMPLE DATA
SOIL PROFILE
GROUNDWATER
-0
a)
-0
o
Drilling Method: Hollow -stem Auger
j
z m
T
~
°o
:a
T
E
T
Ground Elevation (ft). Not Determined
N
N
y a
c
a)
a
LL
oco
(6
U
fl
(n
�
Drilled By: Bortec1 Inc.
J
o co 06
co
(n
m
a)
c7
Z
co
0
AC
Pavement (Asphalt)
SM
Medium dense, brown, dry to damp, silty,
gravelly SAND (Fill)
2
SM
Very dense, gray to blue, damp, silty, very
gravelly SAND with occasional organics
1
b2
46
(Native Borrow Fill)
4
-Relative density changes to Medium Dense
21
b2
25
W = 4
6
GS
8
3
b2
25
10
Den
se, nse, light brown to gray, wet, silty,
gravelly SAND (Glacial Till)
41
b2
4
12
Perched Conditions, ATD
14
-Relative density changes to Very Dense
51
b2
50/
5
16
Boring Completed 04/26/19
Total Depth of Boring = 16.5 ft.
18
Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate.
2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols.
The Commons Figure
CSC oTe5T Pacific Highway South Log of Boring B-1
Federal Way, WA
B-2
SAMPLE DATA
SOIL PROFILE
GROUNDWATER
-0
a)
-0
o
Drilling Method: Hollow -stem Auger
j
z m
T
~
°o
:a
T
E
T
Ground Elevation (ft). Not Determined
N
N
y a
c
a)
a
LL
oco
(6
U
fl
(n
�
Drilled By: Bortec1 Inc.
J
o co 06
co
(n
m
a)
c7
Z
co
0
AC
Pavement (Asphalt)
SM
Medium dense, brown, dry to damp, silty,
gravelly SAND (Fill)
2
SM
Medium dense, gray to blue, damp, silty,
very gravelly SAND with occasional organics
6
b2
26
W = 6
(Native Borrow Fill)
GS
4
- Relative density changes to Medium
Dense
7
b2
22
6
Relative density changes to Very Dense
8
50/
Rock lodged in sampler
8
b2
5„
10
- Brick and metal debris observed in
Perched ATD
9
b2
50/
sampler
Conditions,
6„
SM
Dense, light brown to gray, wet, silty,
12
gravelly SAND (Glacial Till)
14
-Relative density changes to Very Dense
10
b2
50/
W = 11
16
Y
GS
Boring Completed 04/26/19
Total Depth of Boring = 16.5 ft.
18
Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate.
2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols.
The Commons Figure
CSC oTe5T Pacific Highway South Log of Boring B-2
Federal Way, WA
B-3
SAMPLE DATA
SOIL PROFILE
GROUNDWATER
-0
a)
-0
o
Drilling Method: Hollow -stem Auger
j
z m
T
~
°o
:a
T
E
T
Ground Elevation (ft). Not Determined
N
N
y a
c
a)
a
LL
oco
(6
U
fl
(n
�
Drilled By: Bortec1 Inc.
J
o co 06
co
(n
m
a)
c7
Z
co
0
AC
Pavement (Asphalt)
SM
Medium dense, brown, dry to damp, silty,
gravelly SAND (Fill)
2
SM
Very dense, gray to blue, damp, silty,
11
b2
16
gravelly SAND with occasional organics
(Native Borrow Fill)
4
Relative density changes to Very Dense
12
b2
50/
6
5„
Relative density changes to Medium
8 13
b2
13
Dense
10
SM
Very dense, light brown to gray, wet, silty,
14
b2
60
gravelly SAND (Glacial Till)
12
Perched Conditions, ATD
14
Relative density changes to Dense
15
16
b2
48
18
20
Relative density changes to Very Dense
161
b2
50/
W = 18
5"
GS
22 Boring Completed 04/26/19
Total Depth of Boring = 21.5 ft.
Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate.
2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols.
The Commons Figure
CSC oTe5T Pacific Highway South Log of Boring B-3 7
/
Federal Way, WA
B-4
SAMPLE DATA
SOIL PROFILE
GROUNDWATER
-0
a)
-0
o
Drilling Method: Hollow -stem Auger
j
z m
T
~
°o
:a
T
E
T
Ground Elevation (ft). Not Determined
N
N
y a
c
a)
a
LL
oco
(6
U
fl
(n
�
Drilled By: Bortec1 Inc.
J
o co 06
co
(n
m
a)
c7
Z
co
0
AC
Pavement (Asphalt)
SM
Medium dense, brown, dry to damp, silty,
gravelly SAND (Fill)
2
SM
Medium dense, gray to brown, damp, silty,
17
b2
12
gravelly SAND with occasional organics
(Native Borrow Fill)
4
18
6
b2
28
Relative density changes to Loose
8
19
b2
8
10
Relative density changes to Medium
20
b2
23
Dense
12
14
SM
Dense, light brown to gray, wet, silty,
Perched Conditions, ATD
21
b2
35
gravelly SAND (Glacial Till)
16
18
20
Relative density changes to Very Dense
22
b2
65
22 Boring Completed 04/26/19
Total Depth of Boring = 21.5 ft.
Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate.
2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols.
The Commons Figure
CSC oTe5T Pacific Highway South Log of Boring B-4 Q
Federal Way, WA 8
B-5
SAMPLE DATA
SOIL PROFILE
GROUNDWATER
-0
a)
-0
o
Drilling Method: Hollow -stem Auger
j
z m
T
~
°o
:a
T
E
T
Ground Elevation (ft). Not Determined
N
N
y a
c
a)
a
LL
oco
(6
U
fl
(n
�
Drilled By: Bortec1 Inc.
J
o co 06
co
(n
m
a)
c7
Z
co
0
AC
Pavement (Asphalt)
SM
Medium dense, brown, dry to damp, silty,
gravelly SAND (Fill)
2
SM
Medium dense, gray to blue, damp, silty,
22
b2
12
gravelly SAND with occasional organics
(Native Borrow Fill)
4
23
g
b2
13
W = 9
GS
Relative density changes to Loose
8
24
b2
5
10
Color grades to brown
25
b2
6
12
14
SM
Dense, gray, wet, silty, gravelly SAND
26
b2
34
(Glacial Till)
16
Perched Conditions, ATD
18
20
27
b2
40
22 Boring Completed 04/26/19
Total Depth of Boring = 21.5 ft.
Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate.
2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols.
The Commons Figure
CSC oTe5T Pacific Highway South Log of Boring B-5
9
Federal Way, WA
B-6
SAMPLE DATA
SOIL PROFILE
GROUNDWATER
-0
a)
-0
o
Drilling Method: Hollow -stem Auger
j
z m
T
~
°o
:a
T
E
T
Ground Elevation (ft). Not Determined
N
N
y a
c
a)
a
LL
oco
(6
U
fl
(n
�
Drilled By: Bortec1 Inc.
J
o co 06
co
(n
m
a)
c7
Z
co
0
AC
Pavement (Asphalt)
SM
Medium dense, brown, dry to damp, silty,
gravelly SAND (Fill)
2
SM
Medium dense, gray to blue, damp, silty,
28
b2
30
gravelly SAND with occasional organics
(Native Borrow Fill)
4
Relative density changes to Loose
29
6
b2
9
Relative density changes to Medium
8 30
b2
12
Dense
10
31
b2
29
12
14
Perched Conditions, ATD
Brick debris observed in sampler
32
b2
85
Relative density changes to Very Dense
16
SM
Very dense, gray, wet, silty, gravelly SAND
(Glacial Till)
18
20
33
b2
79
W - 11
GS
22 Boring Completed 04/26/19
Total Depth of Boring = 21.5 ft.
Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate.
2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols.
The Commons Figure
CSC oTe5T Pacific Highway South Log of Boring B-6 O
Federal Way, WA
B-7
SAMPLE DATA
SOIL PROFILE
GROUNDWATER
-0
a)
-0
o
Drilling Method: Hollow -stem Auger
j
z m
T
~
°o
:a
T
E
T
Ground Elevation (ft). Not Determined
N
N
y a
c
a)
a
LL
oco
(6
U
fl
(n
�
Drilled By: Bortec1 Inc.
J
o co 06
co
(n
m
a)
c7
Z
co
0
AC
Pavement (Asphalt)
SM
Medium dense, brown, dry to damp, silty,
gravelly SAND (Fill)
2
SM
Medium dense, gray to blue, damp, silty,
34
b2
19
gravelly SAND with occasional organics
(Native Borrow Fill)
4
Relative density changes to Loose
35
6
b2
5
Relative density changes to Medium
8 36
b2
24
Dense
10
Relative density changes to Dense
37
b2
32
12
14
SM
Ve dense, gra to brown, wet, silt ,
38
b2
65
W = 7
gravelly SAND (Glacial Till)
16
GS
18
Perched Conditions, ATD
20
39
b2
50/
4"
22 Boring Completed 04/26/19
Total Depth of Boring = 21.5 ft.
Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate.
2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols.
The Commons Figure
CSC oTe5T Pacific Highway South Log of Boring B-7 11
Federal Way, WA
B-8
SAMPLE DATA
SOIL PROFILE
GROUNDWATER
-0
a)
-0
o
Drilling Method: Hollow -stem Auger
j
z m
T
~
°o
:a
T
E
T
Ground Elevation (ft). Not Determined
N
N
y a
c
a)
a
LL
oco
(6
U
fl
(n
�
Drilled By: Bortec1 Inc.
J
o co 06
co
(n
m
a)
c7
Z
co
0
AC
Pavement (Asphalt)
SM
Medium dense, brown, dry to damp, silty,
gravelly SAND (Fill)
2
SM
Very dense, gray to blue, damp, silty,
40
b2
65
W - 18
gravelly SAND with occasional organics
GS
(Native Borrow Fill)
4
41
6
b2
60
Relative density changes to Medium
8 42
b2
26
Dense
10
43
b2
11
12
14
SM
Dense, gray to brown, wet, silty, gravelly
44
b2
41
SAND (Glacial Till)
16
Perched Conditions, ATD
18
20
Relative density changes to Very Dense
45
b2
50/
" 6
22 Boring Completed 04/26/19
Total Depth of Boring = 21.5 ft.
Notes: 1. Stratigraphic contacts are based on field interpretations and are approximate.
2. Reference to the text of this report is necessary for a proper understanding of subsurface conditions.
3. Refer to "Soil Classification System and Key" figure for explanation of graphics and symbols.
The Commons Figure
CSC oTe5T Pacific Highway South Log of Boring B-8
12
Federal Way, WA
w
N
co
Z
9
c9
100
90
80
70
a 40
30
20
10
0
U.S. SIEVE OPENING IN INCHES I U.S. SIEVE NUMBERS I HYDROMETER
d 9 9 1/9 '2 R 1n 1R 2n Fn inn 9nn
■■■■■11111■uiMMU11111■Y■■IIIII■■W■■IIIIII■■■■IIIII■■■■I
100 10 1 0.1
Grain Size in Millimeters
0.01 0.001
Cobbles
Gravel
Sand
Silt or Clay
coarse fine
coarse I medium fine
Point
Depth
Classification
LL
PL
PI
C,
Cu
•
B-1
5.0
SLIGHTLY SILTY, VERY GRAVELLY SAND (SM)
0.73
56.59
III
B-2
2.5
SLIGHTLY SILTY, VERY GRAVELLY SAND (SM)
A
B-2
15.0
SILTY, GRAVELLY SAND (SM)
*
B-3
20.0
SILTY, GRAVELLY SAND (SM)
Point
Depth
p
D 90
D 60
D 50
D 30
D 10
%Coarse
Gravel
% Fine
Gravel
% Coarse
Sand
% Medium
Sand
% Fine
Sand
% Fines
0
B-1
5.0
16.845
6.316
3.82
0.718
0.112
6.3
40.8
11.5
17.2
16.2
8.0
III
B-2
2.5
14.61
4.295
2.408
0.569
5.8
32.5
14.9
20.2
13.6
13.0
A
B-2
15.0
12.87
1.219
0.474
0.089
6.6
18.1
10.4
16.1
20.7
28.1
*
B-3
20.0
28.648
2.323
1.196
0.214
15.1
13.7
13.6
19.9
16.6
21.2
The Commons
eoTe5T
Pacific Highway South
Federal Way, WA
C. = D302/(D60* D,o) To be well graded: 1 < C, < 3 and
C. = D60/D,0 C, > 4 for GW or C, > 6 for SW
Figure
Grain Size Test Data 13
w
N
co
Z
9
c9
100
90
80
70
a 40
30
20
10
0
U.S. SIEVE OPENING IN INCHES I U.S. SIEVE NUMBERS I HYDROMETER
d 9 1 1/9 '2 R 1n 1R 2n Fn inn 9nn
■■■■■IIIII■��`►,,7■111111■Y■■IIIII■■W■■IIIIII■■■■IIIII■■■■I
100 10 1 0.1
Grain Size in Millimeters
0.01 0.001
Cobbles
Gravel
Sand
Silt or Clay
coarse fine
coarse I medium fine
Point
Depth
Classification
LL
PL
PI
Cc
C,
•
B-5
5.0
SILTY, VERY GRAVELLY SAND (SM)
III
B-6
20.0
VERY SILTY, GRAVELLY SAND (SM)
A
B-7
15.0
SILTY, VERY GRAVELLY SAND (SM)
*
B-8
2.5
SILTY, VERY GRAVELLY SAND (SM)
Point
Depth
p
D 90
D 60
D 50
D 30
D 10
%Coarse
Gravel
% Fine
Gravel
% Coarse
Sand
% Medium
Sand
% Fine
Sand
% Fines
0
B-5
5.0
28.261
4.065
1.018
0.102
14.3
24.4
6.8
10.8
16.6
27.0
III
B-6
20.0
10.454
0.381
0.163
2.7
17.2
7.7
11.2
19.6
41.6
A
B-7
15.0
20.335
2.35
0.847
0.102
11.4
19.9
10.6
14.3
16.6
27.1
*
B-8
2.5
16.271
3.983
1.436
0.141
4.8
33.3
9.4
11.9
15.8
24.8
The Commons
eoTe5T
Pacific Highway South
Federal Way, WA
Cc = D302/(D60* D,o) To be well graded: 1 < Cc < 3 and
Cu = D60/D,o C, > 4 for GW or C, > 6 for SW
Figure
Grain Size Test Data 14
Northwest Agricultural
COrlSllltal'ttS
2545 W Falls Avenue
Kennewick, WA 99336
509.783.7450
www.nwag.com
lab@nwag.com
GeoTest Services Inc.
741 Marine Drive
Bellingham, WA 98225
PAP -Accredited
Report: 48139-1-1
Date: May 22, 2019
Project No: 19-0193
Project Name: The Commons
Sample ID
pH
Organic Matter
Cation Exchange Capacity
B-3 @ 5.0'
7.0
0.83%
5.8 meq/100g
B-4 @ 2.5'
7.1
1.91%
6.3 meq/100g
B-4 @ 5.0'
6.5
2.10%
6.9 meq/100g
B-7 @ 5.0'
5.9
5.06%
13.0 meq/100g
Method
SM 4500-H+ B
ASTM D2974
EPA 9081
REPORT LIMITATIONS AND GUIDELINES FOR ITS USE'
Subsurface issues may cause construction delays, cost overruns, claims, and disputes.
While you cannot eliminate all such risks, you can manage them. The following
information is provided to help:
Geotechnical Services are Performed for Specific Purposes, Persons, and Projects
At GeoTest our geotechnical engineers and geologists structure their services to meet
specific needs of our clients. A geotechnical engineering study conducted for a civil
engineer may not fulfill the needs of an owner, a construction contractor or even
another civil engineer. Because each geotechnical engineering study is unique, each
geotechnical engineering report is unique, prepared solely for the client. No one
except you should rely on your geotechnical engineer who prepared it. And no one -
not even you - should apply the report for any purpose or project except the one
originally contemplated.
Read the Full Report
Serious problems have occurred because those relying on a geotechnical engineering
report did not read it all. Do not rely on an executive summary. Do not read selected
elements only.
A Geotechnical Engineering Report is Based on a Unique Set of Project -Specific
Factors
GeoTest's geotechnical engineers consider a number of unique, project -specific
factors when establishing the scope of a study. Typical factors include: the clients
goals, objectives, and risk management preferences; the general nature of the
structure involved its size, and configuration; the location of the structure on the site;
and other planned or existing site improvements, such as access roads, parking lots,
and underground utilities. Unless GeoTest, who conducted the study specifically
states otherwise, do not rely on a geotechnical engineering report that was:
• not prepared for you,
• not prepared for your project,
• not prepared for the specific site explored, or
• completed before important project changes were made.
1
llnformation in this document is based upon material developed by ASFE, Professional Firms Practicing in the
Geosciences(asfe.org)
Typical changes that can erode the reliability of an existing geotechnical engineering
report include those that affect:
• the function of the proposed structure, as when it's changed, for example, from
a parking garage to an office building, or from a light industrial plant to a
refrigerated warehouse,
• elevation, configuration, location, orientation, or weight of the proposed
construction,
• alterations in drainage designs; or
• composition of the design team; the passage of time; man-made alterations
and construction whether on or adjacent to the site; or by natural alterations
and events, such as floods, earthquakes or groundwater fluctuations; or project
ownership.
Always inform GeoTest's geotechnical engineer of project changes - even minor ones
- and request an assessment of their impact. Geotechnical engineers cannot accept
responsibility or liability for problems that occur because their reports do not consider
developments of which they were not informed.
Subsurface Conditions Can Change
This geotechnical or geologic report is based on conditions that existed at the time
the study was performed. Do not rely on the findings and conclusions of this report,
whose adequacy may have been affected by: the passage of time; by man-made
events, such as construction on or adjacent to the site; or by natural events, such as
floods, earthquakes, or groundwater fluctuations. Always contact GeoTest before
applying the report to determine if it is still relevant. A minor amount of additional
testing or analysis will help determine if the report remains applicable.
Most Geotechnical and Geologic Findings are Professional Opinions
Our site exploration identifies subsurface conditions only at those points where
subsurface tests are conducted or samples are taken. GeoTest's engineers and
geologists review field and laboratory data and then apply their professional
judgment to render an opinion about subsurface conditions throughout the site.
Actual subsurface conditions may differ - sometimes significantly - from those
indicated in your report. Retaining GeoTest who developed this report to provide
construction observation is the most effective method of managing the risks
associated with anticipated or unanticipated conditions.
2
llnformation in this document is based upon material developed by ASFE, Professional Firms Practicing in the
Geosciences(asfe.org)
A Report's Recommendations are Not Final
Do not over -rely on the construction recommendations included in this report. Those
recommendations are not final, because geotechnical engineers or geologists
develop them principally from judgment and opinion. GeoTest's geotechnical
engineers or geologists can finalize their recommendations only by observing actual
subsurface conditions revealed during construction. GeoTest cannot assume
responsibility or liabilityfor the report's recommendations if our firm does not perform
the construction observation.
A Geotechnical Engineering or Geologic Report may be Subject to Misinterpretation
Misinterpretation of this report by other design team members can result in costly
problems. Lower that risk by having GeoTest confer with appropriate members of the
design team after submitting the report. Also, we suggest retaining GeoTest to review
pertinent elements of the design teams plans and specifications. Contractors can also
misinterpret a geotechnical engineering report. Reduce that risk by having GeoTest
participate in pre -bid and preconstruction conferences, and by providing
construction observation.
Do not Redraw the Exploration Logs
Our geotechnical engineers and geologists prepare final boring and testing logs
based upon their interpretation of field logs and laboratory data. To prevent errors of
omissions, the logs included in this report should never be redrawn for inclusion in
architectural or other design drawings. Only photographic or electronic reproduction
is acceptable; but recognizes that separating logs from the report can elevate risk.
Give Contractors a Complete Report and Guidance
Some owners and design professionals mistakenly believe they can make contractors
liable for unanticipated subsurface conditions by limiting what they provide for bid
preparation. To help prevent costly problems, give contractors the complete
geotechnical engineering report, but preface it with a clearly written letter of
transmittal. In that letter, consider advising the contractors that the report was not
prepared for purposes of bid development and that the report's accuracy is limited;
encourage them to confer with the GeoTest and/or to conduct additional study to
obtain the specific types of information they need or prefer. A pre -bid conference can
also be valuable. Be sure contractors have sufficient time to perform additional study.
Only then might you be in a position to give contractors the best information
available, while requiring them to at least share some of the financial responsibilities
3
llnformation in this document is based upon material developed by ASFE, Professional Firms Practicing in the
Geosciences(asfe.org)
stemming from unanticipated conditions. In addition, it is recommended that a
contingency for unanticipated conditions be included in your project budget and
schedule.
Read Responsibility Provisions Closely
Some clients, design professionals, and contractors do not recognize that
geotechnical engineering or geology is far less exact than other engineering
disciplines. This lack of understanding can create unrealistic expectations that can
lead to disappointments, claims, and disputes. To help reduce risk, GeoTest includes
an explanatory limitations section in our reports. Read these provisions closely. Ask
questions and we encourage our clients or their representative to contact our office if
you are unclear as to how these provisions apply to your project.
Environmental Concerns Are Not Covered in this Geotechnical or Geologic Report
The equipment, techniques, and personnel used to perform an environmental study
differ significantly from those used to perform a geotechnical or geologic study. For
that reason, a geotechnical engineering or geologic report does not usually relate any
environmental findings, conclusions, or recommendations; e.g., about the likelihood
of encountering underground storage tanks or regulated containments, etc. If you
have not yet obtained your own environmental information, ask your geotechnical
consultant for risk management guidance. Do not rely on environmental report
prepared for some one else.
Obtain Professional Assistance to Deal with Biological Pollutants
Diverse strategies can be applied during building design, construction, operation, and
maintenance to prevent significant amounts biological pollutants from growing on
indoor surfaces. Biological pollutants includes but is not limited to molds, fungi,
spores, bacteria and viruses. To be effective, all such strategies should be devised for
the express purpose of prevention, integrated into a comprehensive plan, and
executed with diligent oversight by a professional biological pollutant prevention
consultant. Because just a small amount of water or moisture can lead to the
development of severe biological infestations, a number of prevention strategies
focus on keeping building surfaces dry. While groundwater, water infiltration, and
similar issues may have been addressed as part of this study, the geotechnical
engineer or geologist in charge of this project is not a biological pollutant prevention
consultant; none of the services preformed in connection with this geotechnical
engineering or geological study were designed or conducted for the purpose of
preventing biological infestations.
4
llnformation in this document is based upon material developed by ASFE, Professional Firms Practicing in the
Geosciences(asfe.org)