HomeMy WebLinkAboutHARMONY COMMONS HOTEL - PDP - PDP160027 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTGEOTECHNICAL SUBSURFACE EXPLORATION REPORT
PROPOSED HARMONY COMMONS HOTEL
LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
SOILOGIC # 16-1180
August 18, 2016
Soilogic, Inc.
3050 67th Avenue, Suite 200 • Greeley, CO 80634 • (970) 535-6144
P.O. Box 1121 • Hayden, CO 81639 • (970) 276-2087
August 18, 2016
Willco XV, LLLP
4836 S. College Avenue, Suite 11
Fort Collins, Colorado 80525
Attn: Mrs. Moira Bright
Re: Geotechnical Subsurface Exploration Report
Proposed Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive
Fort Collins, Colorado
Soilogic Project # 16-1180
Mrs. Bright:
Soilogic, Inc. (Soilogic) personnel have completed the geotechnical subsurface
exploration you requested for the proposed Harmony Commons Hotel to be constructed
on Lot 6 in the Harmony Commons development in Fort Collins, Colorado. The results
of our subsurface exploration and pertinent geotechnical engineering recommendations
are included with this report.
In general, the subsurface materials encountered in the completed site borings can be
summarized as follows. A thin layer of vegetation and topsoil was encountered at the
surface at the locations of borings B-1, B-2 and B-4. Brown/rust/beige sandy lean clay
containing clayey sand lenses and trace amounts of gravel was encountered underlying
the vegetative soil layer or at the surface at the locations of borings B-3, B-5 and B-6.
The apparently-natural lean clay varied from very soft to stiff in terms of consistency, or
from very loose to loose in terms of relative density, exhibited no to low swell potential
and low consolidation potential at current moisture and density conditions and extended
to the full depths of exploration (approximately 10 to 15 feet below ground surface) at the
locations of all borings except boring B-3, where the lean clay/clayey sand transitioned to
gray-brown/rust lean to fat clay with sand at a depth of about 13 feet below ground
surface. The lean to fat clay was very stiff in consistency and extended to the bottom of
boring B-3 at a depth of approximately 15 feet below present site grade.
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
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Groundwater was not encountered to the depths explored in any of the completed site
borings at the time of drilling. When checked eight (8) days after drilling, groundwater
was measured at depths of about 12 to 12½ feet below ground surface in borings B-1
through B-3. Borings B-4 through B-6 remained dry to the approximate depth explored
(about 10 feet below ground surface) at that time.
Based on the subsurface conditions encountered, results of laboratory testing and type of
construction proposed, it is our opinion the proposed hotel building could be constructed
with conventional spread footing foundations bearing on a zone of properly moisture-
conditioned and compacted, essentially-granular select import fill due to the presence of
comparatively soft/loose soils and the potential for excessive foundation settlement
resulting from the moderate foundation loads. The natural, undisturbed site lean clay/
clayey sand could be used for direct support of more lightly-loaded trash enclosure and
retaining wall footing foundations.
The site lean clay/clayey sand soils would be considered low volume-change (LVC)
potential soils and could be used as fill to develop the site. The reconditioned near-
surface site lean clay/clayey sand and properly placed and compacted fill consisting of
on-site lean clay/clayey sand and/or similar import LVC soils could be used for support
of the building floor slabs, exterior flatwork and site pavements. Pavement section
design options for the site drive and parking area pavements are included with this report.
Other opinions and recommendations concerning design criteria and construction details
for the proposed site improvements are also provided.
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
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We appreciate the opportunity to be of service to you on this project. If you have any
questions concerning the enclosed information or if we can provide any further
assistance, please do not hesitate to contact us.
Very Truly Yours,
Soilogic, Inc. Reviewed by:
Darrel DiCarlo, P.E. Wolf von Carlowitz, P.E.
Senior Project Engineer Principal Engineer
44271 36746
GEOTECHNICAL SUBSURFACE EXPLORATION REPORT
PROPOSED HARMONY COMMONS HOTEL
LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
SOILOGIC # 16-1180
August 18, 2016
INTRODUCTION
This report contains the results of the completed geotechnical subsurface exploration for
the proposed Harmony Commons Hotel to be constructed on Lot 6 in the Harmony
Commons development in Fort Collins, Colorado. The purpose of our exploration was to
describe the subsurface conditions encountered in the completed site borings and develop
the test data necessary to provide recommendations concerning design and construction
of the hotel building, trash enclosure, gazebo, porte-cochere, retaining wall, in-ground
pool and high-mast lighting foundations and support of floor slabs, exterior flatwork and
site pavements. Pavement section design recommendations are also provided. The
conclusions and recommendations outlined in this report are based on results of the
completed field and laboratory testing and our experience with subsurface conditions in
this area. As part of our analysis, a Geotechnical Subsurface Exploration Report
prepared by Soilogic Inc. (Soilogic) for the HTP North Retail and Office Center (Project
#15-1138, dated July 1, 2015) was reviewed.
PROPOSED CONSTRUCTION
We understand the proposed hotel building will be a 3-story wood-frame structure
constructed as slab-on-grade. Foundation loads for the structure are expected to be
moderate, with continuous wall loads on the order of 5 kips per lineal foot and individual
column loads on the order of 150 kips or less. Trash enclosure, high-mast lighting,
retaining wall and indoor pool construction are also anticipated. Paved drive and parking
area pavements will be constructed as part of the proposed site improvements. Traffic
loading on site pavements is expected to consist of low volumes of light passenger
vehicles, with occasional trash and delivery truck traffic. Small grade changes (on the
order of 4 feet or less) are anticipated to develop finish site grades in the building and
pavement areas.
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
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SITE DESCRIPTION
The development property includes an approximate 1.75-acre parcel located at 3520
Timberwood Drive in south Fort Collins, Colorado. At the time of our site exploration,
the ground surface across the central portion of the property contained a moderate growth
of native grass and weed vegetation, while the eastern and western potions of the
property were barren and/or appeared to have been stripped of vegetation. The site was
observed to be relatively level, with a gentle overall slope downward to the southeast.
The maximum difference in ground surface elevation across the building footprint is
estimated to be approximately 2 feet based on a provided topographic map of the
property. Evidence of prior building construction was not observed on the development
lots by Soilogic personnel at the time of our site exploration.
SITE EXPLORATION
Field Exploration
To develop site specific subsurface information, a total of six (6) soil borings were
completed across the site. Three (3) borings were drilled in the area of the proposed
structure to a depth of approximately 15 feet below present site grades. Three (3) borings
were drilled in areas of proposed drive lanes/parking areas to a depth of approximately 10
feet below present site grades. The boring locations were established in the field by
Soilogic personnel based on a provided concept plan and by pacing and estimating angles
and distances from identifiable site references. The boring locations should be
considered accurate only to the degree implied by the methods used to make the field
measurements. A diagram indicating the approximate boring locations is included with
this report. Graphic logs of each of the auger borings are also included.
The test holes were advanced using 4-inch diameter continuous flight auger powered by a
truck-mounted CME-45 drill rig. Samples of the subsurface materials were obtained at
regular intervals using California barrel sampling procedures in general accordance with
ASTM specification D-1586. As part of the D-1586 sampling procedure, the standard
sampling barrel is driven into the substrata using a 140-pound hammer falling a distance
of 30 inches. The number of blows required to advance the sampler a distance of 12
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
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inches is recorded and helpful in estimating the consistency, relative density of the soils
encountered. In the California barrel sampling procedure, lesser disturbed samples are
obtained in removable brass liners. Samples of the subsurface materials obtained in the
field were sealed and returned to the laboratory for further evaluation, classification and
testing.
Laboratory Testing
The samples collected were tested in the laboratory to measure natural moisture content
and were visually and/or manually classified in accordance with the Unified Soil
Classification System (USCS). The USCS group symbols are indicated on the attached
boring logs. An outline of the USCS classification system is included with this report.
As part of the laboratory testing, a calibrated hand penetrometer (CHP) was used to
estimate the unconfined compressive strength of essentially-cohesive specimens. The
CHP also provides a more reliable estimate of soil consistency than tactual observation
alone. Dry density, Atterberg limits, -200 wash and swell/consolidation tests were
completed on selected samples to help establish specific soil characteristics. Atterberg
limits tests are used to determine soil plasticity. The percent passing the #200 size sieve
(-200 wash test) is used to determine the percentage of fine-grained materials (clay and
silt) in a sample. Swell/consolidation tests are performed to evaluate soil volume change
potential with variation in moisture content. The results of the completed laboratory tests
are outlined on the attached boring logs and swell/consolidation test summaries. Water
Soluble Sulfates (WSS) tests were also completed on two (2) selected soil samples to
evaluate corrosive soil characteristics with respect to buried concrete and results
discussed subsequently in this report.
SUBSURFACE CONDITIONS
The subsurface materials encountered in the completed site borings can be summarized as
follows. A thin layer of vegetation and topsoil was encountered at the surface at the
locations of borings B-1, B-2 and B-4. Brown/rust/beige sandy lean clay containing
clayey sand lenses and trace amounts of gravel was encountered underlying the
vegetative soil layer or at the surface at the locations of borings B-3, B-5 and B-6. The
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
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apparently-natural lean clay varied from very soft to stiff in terms of consistency, or from
very loose to loose in terms of relative density, exhibited no to low swell potential and
low consolidation potential at current moisture and density conditions and extended to the
full depths of exploration (approximately 10 to 15 feet below ground surface) at the
locations of all borings except boring B-3, where the lean clay/clayey sand transitioned to
gray-brown/rust lean to fat clay with sand at a depth of about 13 feet below ground
surface. The lean to fat clay was very stiff in consistency and extended to the bottom of
boring B-3 at a depth of approximately 15 feet below present site grade.
The stratigraphy indicated on the included boring logs represents the approximate
location of changes in soil and bedrock types. Actual changes may be more gradual than
those indicated.
Groundwater was not encountered to the depths explored in any of the completed site
borings at the time of drilling. When checked eight (8) days after drilling, groundwater
was measured at depths of about 12 to 12½ feet below ground surface in borings B-1
through B-3. Borings B-4 through B-6 remained dry to the approximate depth explored
(about 10 feet below ground surface) at that time.
Groundwater levels will vary seasonally and over time based on weather conditions, site
development, irrigation practices and other hydrologic conditions. Perched and/or
trapped groundwater conditions may also be encountered at times throughout the year.
Perched water is commonly encountered in soils overlying less permeable soil layers
and/or bedrock. The location and amount of perched/trapped water can also vary over
time.
ANALYSIS AND RECOMMENDATIONS
General
Excessive settlement/consolidation of the soft/loose overburden lean clay/clayey sand
soils would be expected to occur as a result of the moderate foundation loads anticipated.
In order to reduce potential foundation settlement to an acceptable level and develop
higher allowable soil bearing capacities, overexcavation of a portion of the lean clay/
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
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clayey sand foundation bearing soils and replacement with properly placed and
compacted, essentially-granular imported structural fill will be required.
Recommendations concerning overexcavation/replacement/backfill procedures to
redevelop low volume change potential (LVC) and higher strength foundation bearing
conditions for the hotel building are outlined below.
Drilled pier foundations could also be considered for support of the structure. Drilled
piers would anchor the building into bedrock underlying the site, significantly reducing
the potential for movement of the structure subsequent to construction. As groundwater
and very soft/saturated lean clay/clayey sand soils were encountered at greater depth and
bedrock is located at depths greater than 15 feet below ground surface, we expect casing
of drilled pier excavations would be required to prevent soil and groundwater from
entering the pier excavations prior to placement of reinforcing steel and pier concrete.
Additionally, we understand design and construction of this type of structure utilizing
drilled pier foundations can be cost-prohibitive. Recommendations concerning the
design and construction of drilled pier foundations can be provided at your request.
Foundation Bearing and Subgrade Development
To develop suitable foundation bearing strength and consistent LVC support and reduce
the potential for total and differential movement of the hotel building foundation
subsequent to construction, we recommend a zone of select granular fill be developed
beneath all footing foundations and isolated column pads. The removed and replaced
essentially-granular LVC soils will provide a zone of higher strength material
immediately beneath the hotel building footing foundations, reducing the potential for
total and differential movement of the supported improvements subsequent to
construction.
Overexcavation/replacement procedures should be performed below all hotel building
footing foundations (including the porte-cochere) and should extend to depths and widths
as outlined below. For continuous wall footing foundations, the overexcavation/
replacement area should extend a minimum of 8 inches laterally past the interior and
exterior perimeters of the footings for every 12 inches of overexcavation depth. For
isolated column pad foundations, the overexcavation/replacement area should extend a
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
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minimum of 8 inches laterally past the perimeter of all four (4) sides of the pad
foundations for every 12 inches of overexcavation depth. Overexcavation/replacement
procedures would not be required below the lightly-loaded detached trash enclosure
structure and/or retaining walls (if constructed).
Soils used as overexcavation/replacement below foundations should consist of approved
essentially-granular import structural fill soils free from organic matter, debris and other
objectionable materials. Imported structural fill consistent with Colorado Department of
Transportation (CDOT) Class 6 or 7 Aggregate Base Course specifications would be
suitable as engineered fill below foundations. Based on results of the completed
laboratory testing and analyses, we recommend a minimum of three (3) feet of approved
import structural fill material be developed below continuous strip footing foundations
and isolated column pad foundations to achieve higher bearing capacity and to reduce
potential settlement as previously discussed. The increased bearing capacity would also
reduce the size of continuous wall and column pad foundations.
All existing topsoil and vegetation should be removed from the building, pavement and
exterior flatwork areas. After stripping and completing all cuts and prior to placement of
any new fill, flatwork concrete or pavements, we recommend the exposed subgrades be
scarified to a depth of 9 inches, adjusted in moisture content and compacted to at least
95% of the materials standard Proctor maximum dry density. The moisture content of the
scarified soils should be adjusted to within the range of ±2% of standard Proctor optimum
moisture content at the time of compaction. Scarification and recompaction of the
exposed subgrade soils in overexcavation/replacement/backfill areas would not be
required prior to the placement of select granular fill.
General site fill and backfill materials consisting of the site lean clay/clayey sand or
similar materials should be placed in loose lifts not to exceed 9 inches thick, adjusted in
moisture content and compacted as outlined for the scarified soils above. Essentially-
granular import structural fill used as overexcavation/replacement below foundations
should be placed in loose lifts not to exceed 9 inches thick, moisture conditioned to
within ±2% of standard Proctor optimum moisture content and compacted to at least 98%
of the materials standard Proctor maximum dry density.
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
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Care should be taken to maintain the proper moisture content in the bearing/subgrade
soils prior to concrete placement and/or paving. The prepared structural soils should not
be left exposed for extended periods of time. In the event that the reconditioned soils are
allowed to dry out or if rain, snowmelt or water from any source is allowed to infiltrate
the bearing/subgrade soils, reworking of those materials or removal/replacement
procedures may be required.
Hotel Building Foundations
For design of continuous spread footing and isolated column pad hotel building
foundations bearing on a minimum of three (3) feet of essentially-granular imported LVC
structural fill developed as outlined above and compacted to at least 98% of the
material’s standard Proctor maximum dry density, we recommend using a maximum net
allowable soil bearing pressure of 2,500 psf.
Based on the materials encountered in the completed site borings and results of
laboratory testing, it is our opinion the proposed lightly-loaded detached trash enclosure
and retaining walls could be supported by continuous spread footing and isolated pad
foundations bearing on natural, undisturbed lean clay/clayey sand with no to low swell
potential. For design of footing foundations bearing on natural, undisturbed medium stiff
to stiff/loose lean clay/ clayey sand, we recommend using a maximum net allowable soil
bearing pressure of 1,500 psf.
For design of footing foundations and foundation walls to resist lateral movement, a
passive equivalent fluid pressure value of 250 pcf could be used for the site lean clay/
clayey sand or similar soils. A coefficient of friction of 0.35 could be used between floor
slab concrete and the bearing/subgrade soils to resist sliding for the on-site lean clay/
clayey sand. A coefficient of friction of 0.45 could be used between foundation concrete
and select granular import fill. The recommended passive equivalent fluid pressure value
and coefficients of friction do not include a factor of safety.
Exterior footings should bear a minimum of 30 inches below finished adjacent exterior
grade to provide frost protection. We recommend formed strip footings have a minimum
width of 12 inches and isolated pad foundations have a minimum width of 24 inches in
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
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order to facilitate construction and reduce the potential for development of eccentrically
loaded footings. Actual footing widths should be designed by a structural engineer.
We estimate settlement of footing foundations designed and constructed as outlined
above and resulting from the assumed structural loads would be on the order of 1 inch.
Differential settlement could approach the amount of total settlement estimated above.
Gazebo & High-mast Light Standard Foundations
We anticipate the gazebo and high-mast light standards planned as part of site
development will be constructed using shallow drilled shaft foundations. For design of
shallow drilled shaft foundations bearing on very soft to medium stiff/very loose to loose
site lean clay/clayey sand, we recommend using a maximum net allowable soil bearing
pressure of 1,000 psf. Additional pier capacity can be developed by accounting for
friction capacity between the drilled pier and surrounding lean clay/clayey sand stratum.
An allowable skin friction value of 100 psf could be used for that portion of the pier
concrete in contact with the site lean clay/clayey sand soils below frost depth. Skin
friction should be neglected within the top 30 inches of depth below finish grade due to
the potential for frost action.
Drilled shaft foundations shall bear a minimum of 30 inches below finished adjacent
exterior grade to provide frost protection. For design of the foundation systems to resist
overturning, a passive equivalent fluid pressure of 250 pcf could be used for that portion
of the foundation system extended below frost depth. The top 30 inches of soil could be
considered a surcharge load but should not be used in passive resistance calculations. A
coefficient of friction of 0.35 could be used between foundation concrete and lean clay/
clayey sand bearing soils to resist sliding. The recommended passive equivalent fluid
pressure value and coefficient of friction do not include a factor of safety. For design of
uplift resistance, an in-place soil unit weight of 125 pcf and angle of internal friction
value of 20° could be used. Typically, light-pole base foundations are constructed with a
minimum embedment length on the order of seven (7) feet below grade in accordance
with current building code.
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
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We expect the pier excavations could be completed using conventional augering
techniques. Pier excavations extended more than about 10 feet below ground surface
would not be expected to remain stable for short periods during construction such that
temporary casing of the drilled shafts or mudded (bentonite slurry) construction
procedures may be required. Pier concrete should have a slump in the range of 5 to 7
inches and be placed in the pier holes immediately after the completion of drilling,
cleaning and placement of reinforcing steel.
We estimate settlement of gazebo and light-pole standard foundations designed and
constructed as outlined above and resulting from the assumed structural loads would be
less than 1 inch. If water from any source is allowed to infiltrate the foundation soils,
additional movement of the foundations could occur. Settlement of shallow drilled shaft
foundations would be expected to be less than ½ inch.
Foundation Backfill
Backfill placed adjacent to foundation walls should consist of approved LVC soils free
from organic matter, debris and other objectionable materials. Based on results of the
completed field and laboratory testing, it is our opinion the native site lean clay/clayey
sand could be used as backfill in this area provided care is taken to develop the proper
moisture content in those materials at the time of placement and compaction. We
recommend the site lean clay/clayey sand or similar soils be placed in loose lifts not to
exceed 9 inches thick, adjusted in moisture and compacted as previously outlined in the
“Foundation Bearing and Subgrade Development” section of this report.
Excessive lateral stresses can be imposed on un-braced foundation walls when using
heavier mechanical compaction equipment. We recommend compaction of unbalanced
foundation wall backfill soils be completed using light mechanical or hand compaction
equipment.
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
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Seismicity
Based on our review of the International Building Code (2003), a soil profile type D
could be used for the site strata. Based on our review of United States Geologic Survey
(USGS) mapped information, design spectral response acceleration values of SDS = .218
(21.8%) and SD1 = .092 (9.2%) could be used.
Floor Slabs and Exterior Flatwork
The building floor slab and exterior flatwork could be supported on reconditioned natural
site soils or properly placed and compacted fill developed as outlined in the “Foundation
Bearing and Subgrade Development” section of this report. A modulus of subgrade
reaction (k) value of 125 pci could be used for design of floor slabs supported on
reconditioned natural site lean clay/clayey sand or similar LVC fill materials. Disturbed
subgrades or subgrade soils that have been allowed to dry out or become wet and
softened should be removed and replaced or reconditioned in place prior to floor slab and
exterior flatwork construction.
Floor slabs should designed and constructed as floating slabs, separated from foundation
walls, columns and plumbing and mechanical penetrations by the use of block outs or
appropriate isolation material. Additionally, we recommend all partition walls supported
above slabs-on-grade be constructed as floating walls to help reduce the potential for
differential slab-to-foundation movement causing distress in upper sections of the
structure. A minimum one and one-half (1½) inch void space is recommended beneath
all floating walls. Special attention to door and stair framing, drywall installation and
trim carpentry should be taken to isolate those elements from the floor slabs, allowing for
some differential floor slab-to-foundation movement to occur without transmitting
stresses to the overlying structure.
Depending on the type of floor covering and floor covering adhesive used in finished
slab-on-ground areas, a vapor barrier may be required immediately beneath the floor
slabs to maintain flooring product manufacturer warranties. A vapor barrier would help
reduce the transmission of moisture through floor slabs. However, the unilateral moisture
release caused by placing concrete on an impermeable surface can increase slab curl.
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
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The amount of slab curl can be reduced by careful selection of an appropriate concrete
mix and proper placement and curing procedures. Slab curl cannot be eliminated.
Soilogic recommends the owner, architect and flooring contractor consider the
performance of the slab in conjunction with the proposed flooring products to help
determine if a vapor barrier will be required and where best to position the vapor barrier
in relation to the floor slab. Additional guidance and recommendations concerning slab-
on-grade design can be found in American Concrete Institute (ACI) section 302.
Exterior flatwork will experience some movement subsequent to construction as the
subgrade soils increase in moisture content. Based on results of the completed field and
laboratory testing, we expect the amount of movement of exterior flatwork supported on
reconditioned natural site soils and/or properly placed and compacted fill would be
limited. Care should be taken to ensure that when exterior flatwork moves, positive
drainage will be maintained away from the structure.
Retaining Walls
We understand concrete retaining walls may also be constructed as part of the site
development. For design of retaining wall footing foundations bearing on natural,
undisturbed medium stiff to stiff/loose lean clay/clayey sand with low swell potential, we
recommend using a maximum net allowable soil bearing pressure of 1,500 psf. The
retaining wall footing foundation should bear a minimum of 30 inches below grade at the
front (unretained earth) side of the wall to provide frost protection. We estimate
settlement of the retaining wall footing foundation resulting from the assumed structural
loads would be less than 1 inch. Differential settlement along the length of the wall could
approach the amount of total settlement estimated above.
Care should be taken to prevent the development of unbalanced hydrostatic loads on site
retaining walls. A drainage blanket consisting of 12 inches of free-draining rock placed
behind the wall and extending the full height of the wall from approximate grade at the
front of the wall to approximately 12 to 18 inches below finish grade on the retained soil
side of the wall should be constructed. We recommend ¾-inch or larger washed rock be
used to construct the drainage blanket. The top 12 to 18 inches of retaining wall backfill
should consist of an essentially-cohesive soil to reduce the potential for immediate
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
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surface water infiltration into the wall backfill. The site lean clay/clayey sand would be
suitable for use in this area. A filter fabric should be employed between all free-draining
aggregate and adjacent soil interfaces to reduce the potential for the migration of finer-
grained soils into the gap-graded rock.
Weep holes or other approved methods should be employed to help transfer any collected
water to the front of the wall. A water collection system, similar to a perimeter drain
system could also be considered. A typical collection drain system would consist of 4-
inch diameter rigid perforated pipe surrounded by a minimum of 6 inches of the free-
draining aggregate and placed at the base of the retained soils side of the wall. The invert
of the drain pipe at the high point of the system should be placed at approximate front-of-
wall grade and sloped a minimum of ⅛-inch per foot to facilitate efficient water removal
to an appropriate outfall. Flap gates or other approved methods should be employed at all
free outfalls to reduce the potential for animal access and reverse flow in the system.
Retaining wall backfill should consist of approved low-volume-change (LVC) and
essentially-granular materials free from organic matter and debris. Essentially-granular
soils offer better stacking characteristics and are less prone to movements associated with
freezing through the face of the walls than finer-grained materials. Materials consistent
with Colorado Department of Transportation (CDOT) Class 6 or 7 aggregate base course
or Class I structure backfill could be used as retaining wall backfill. Retaining wall
backfill should be placed in loose lifts not to exceed 9 inches thick, adjusted in moisture
content and compacted to at least 95% of the materials standard Proctor maximum dry
density. The moisture content of the backfill soils should be adjusted to within ±2% of
standard Proctor optimum moisture content at the time of compaction.
Excessive lateral stresses can be imposed on retaining walls during backfilling when
using heavier mechanical compaction equipment. We recommend compaction of
retaining wall backfill be completed using light mechanical or hand compaction
equipment.
For design of retaining walls protected from hydrostatic loading and backfilled with
select granular fill, we recommend using an angle of internal friction of Φ=30° and active
equivalent fluid pressure value of 40 pounds per cubic foot in addition to any surcharge
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
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loads. The equivalent fluid pressure value outlined above is based on an active stress
distribution analysis in which some rotation of the retaining wall is assumed. The angle
of internal friction and equivalent fluid pressure values outlined above do not include a
factor of safety. Sloped backfill geometry, surcharge loads on the retained soil side of the
walls or point loads developed in the wall backfill can add to the lateral forces on
retaining walls. If parking areas are anticipated at the top of site retaining walls, we
recommend the walls be designed to include surcharge loads from parked vehicles in
these areas.
The lateral driving forces on the walls will be resisted through a combination of the
sliding friction of the footing foundations and passive earth pressure against the
embedded portion of the wall below frost depth. A passive equivalent fluid pressure
value of 250 pcf could be used for that portion of the wall extended below frost depth,
considered to be 30 inches in this area. A coefficient of friction of 0.35 could be used
between foundation concrete and the bearing soils to resist sliding. The recommended
passive equivalent fluid pressure value and coefficient of friction do not include a factor
of safety.
Indoor Pool
We understand an indoor, in-ground pool will be constructed extending to a maximum
depth in the range of approximately 5 to 6 feet below present site grades. Based on the
materials encountered in the completed site borings and results of laboratory testing, it is
our opinion the lightly-loaded swimming pool could be supported on natural, undisturbed
lean clay/clayey sand. For design of the pool foundation bearing on natural, undisturbed
medium stiff to stiff/loose lean clay/clayey sand, we recommend using a maximum net
allowable soil bearing pressure of 1,500 psf.
Care should be taken to avoid developing unbalanced hydrostatic loads on the pool walls
and pool bottom. Pressure relief valves could be considered to avoid developing uplift
and excessive horizontal hydrostatic loads. For design of the below-grade pool walls
protected from unilateral hydrostatic loading, we recommend using an active equivalent
fluid pressure value of 40 pounds per cubic foot. Some rotation of the pool walls must
occur to develop the active earth pressure state. That rotation can result in cracking of
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
14
the walls typically in between corners and other restrained points. The amount of
deflection of the top of the wall required to develop the “active” state can be estimated at
0.5% times the height of the wall. An equivalent fluid pressure value of 60 pounds per
cubic foot could be used for restrained conditions.
Variables that affect active lateral earth pressures include but are not limited to the swell
potential of the backfill soils, backfill compaction and geometry, wetting of the backfill
soils, surcharge loads and point loads developed in the backfill materials. The
recommended equivalent fluid pressure values do not include a factor of safety or an
allowance for hydrostatic loading. Use of expansive soil backfill, excessive compaction
of the wall backfill or surcharge loads placed adjacent to the pool walls can add to the
lateral earth pressures causing the equivalent fluid pressure values used in design to be
exceeded.
If backfill is required adjacent to any below-grade pool walls, we recommend those
materials consist of approved low-volume change (LVC) soils free from organic matter,
debris and other objectionable materials. We understand pea gravel is typically used as
pool wall backfill due to the limited area that backfill will extend and inability to access
these areas with compaction equipment. If site lean clay/clayey sand soils will be used
as backfill adjacent to the pool and access with compaction equipment is possible,
backfill soils should be placed in loose lifts not to exceed 9 inches thick, adjusted to in
moisture and compacted as outlined in the “Foundation Bearing and Subgrade
Development” section of this report.
Excessive lateral stresses can be imposed on below grade walls when using heavier
mechanical compaction equipment. We recommend compaction of unbalanced pool wall
backfill soils be completed using light mechanical or hand compaction equipment.
No unusual problems are anticipated in completing the excavation required for
construction of the pool; however, soft/loose and higher moisture content lean clay/
clayey sand soils were encountered with depth in the completed site borings and may be
encountered in the pool excavation. The site soils would be expected to be soft/loose
near current groundwater levels and would be easily disturbed by the construction
activities. Care should be taken at the time of construction to avoid disturbing the
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
15
foundation bearing subgrade soils and the need for corrective action. To reduce the
potential of “pumping” and softening of the foundation soils at foundation bearing level
and the requirement for corrective work, we strongly suggest the pool excavation be
completed remotely with a track-hoe. Materials which are loosened or disturbed by the
construction activities or materials which become dry and desiccated or wet and softened
should be removed and replaced or reworked in place prior to placement of pool
concrete. We estimate the long-term total and differential settlement of the pool
constructed as outlined above would be less than 1 inch.
Pavements
Pavement subgrades should be develop as outlined in the “Foundation Bearing and
Subgrade Development” portion of this report. Care should be taken to avoid disturbing
the reconditioned subgrade soils prior to placement of site pavements and exterior
flatwork. In addition, efforts to maintain the proper moisture content in the subgrade
soils should be made. If subgrade soils are disturbed or allowed to dry out or become
elevated in moisture content, those materials should be reworked in place or removed and
replaced prior to paving or concrete placement.
We anticipate the site drive and parking areas will be surfaced with asphaltic concrete
and/or Portland cement concrete (PCC). The pavement subgrades are expected to consist
of reconditioned lean clay/clayey sand. The lean clay/clayey sand soils classify as A-4
and A-6 soils in accordance with the American Association of State and Highway
Transportation Officials (AASHTO) classification system and would be subject to low
remolded shear strength. A resistance value (R-value) of 10 was estimated for the lean
clay/clayey sand subgrade soils and used in the pavement section design. Traffic loading
on the site pavements is expected to consist of areas of low volumes of automobiles and
light trucks, as well as areas receiving heavier trash and delivery truck traffic. Equivalent
18-kip single axle loads (ESAL’s) were estimated for the quantity of site traffic
anticipated. Two (2) general pavement design categories are outlined below in Table I.
Standard duty pavements could be considered in automobile drive and parking areas.
Heavy duty pavements should be considered for access drives and other areas of the site
expected to receive heavy trash and delivery truck traffic. Thicker pavements sections
may be appropriate in some areas. We would be happy to complete a pavement section
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
16
design based on the actual type and quantity of heavy truck traffic anticipated to utilize
site pavements.
Proofrolling of the pavement subgrades should be completed to help identify unstable
areas. Areas which pump or deform excessively should be stabilized prior to surfacing.
Depending on the in-place moisture content of the subgrade soils immediately prior to
paving, the time of year when construction occurs and other hydrologic conditions,
stabilization of the subgrade soils may become necessary to develop a suitable paving
platform. Isolated areas of subgrade instability can be mended on a case-by-case basis.
If overall instability of the subgrade soils is observed at the time of proofrolling, chemical
stabilization of the subgrade soils could be considered to develop a suitable paving
platform. If required, we recommend consideration be given to stabilization of the
pavement subgrades with Class C fly ash. With the increase in support strength
developed by the fly ash stabilization procedures, it is our opinion some credit for the
stabilized zone could be included in the pavement section design, reducing the required
thickness of overlying asphaltic concrete and aggregate base course. Chemical
stabilization can also eliminate some of the uncertainty associated with attempting to
pave during periods of inclement weather. Pavement section design options
incorporating some structural credit for the chemically-stabilized subgrade soils are
outlined below in Table 1.
TABLE 1 – PAVEMENT SECTION DESIGN
Standard Duty Heavy Duty
Option A – Composite
Asphaltic Concrete (Grading S or SX)
Aggregate Base (Class 5 or 6)
4”
6”
5”
8”
Option B – Composite on Stabilized Subgrade
Asphaltic Concrete (Grading S or SX)
Aggregate Base (Class 5 or 6)
Fly Ash Stabilized Subgrade
3”
4”
12”
4”
6”
12”
Option C - Portland Cement Concrete Pavement
PCCP
5”
6”
Asphaltic concrete should consist of a bituminous plant mix composed of a mixture of
aggregate, filler, binders and additives (if required) meeting the design requirements of
the City of Fort Collins. Aggregate used in the asphaltic concrete should meet specific
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
17
gradation requirements such as Colorado Department of Transportation (CDOT) grading
S (¾-inch minus) or SX (½-inch minus) specifications. Hot mix asphalt designed using
“Superpave” criteria should be compacted to within 92 to 96% of the materials Maximum
Theoretical Density. Aggregate base should be consistent with CDOT requirements for
Class 5 or Class 6 aggregate base, placed in loose lifts not to exceed 9 inches thick and
compacted to at least 95% of the materials standard Proctor maximum dry density.
If chemical stabilization procedures will be completed, we recommend the addition of
12% Class ‘C’ fly ash based on component dry unit weights. A 12-inch thick stabilized
zone should be constructed by thoroughly blending the fly ash with the in-place subgrade
soils. Some “fluffing” of the finish subgrade level should be expected with the
stabilization procedures. The blended materials should be adjusted in moisture content to
within the range of ±2% of standard Proctor optimum moisture content and compacted to
at least 95% of the material’s standard Proctor maximum dry density within two (2) hours
of fly ash addition.
For areas subjected to truck turning movements and/or concentrated and repetitive
loading such as dumpster or truck parking and loading areas, we recommend
consideration be given to the use of Portland cement concrete pavement with a minimum
thickness of 6 inches. The concrete used for site pavements should be air entrained and
have a minimum 28-day compressive strength of 4,200 psi. Woven wire mesh or fiber
entrained concrete should be considered to help in the control of shrinkage cracking.
Areas of the site expected to receive higher volumes of heavy truck traffic may require
thicker pavement sections. We would be happy to complete a pavement section design
based on the actual type and quantity of heavy truck traffic anticipated.
The proposed pavement section designs do not include an allowance for excessive
loading conditions imposed by heavy construction vehicles or equipment. Heavily
loaded concrete or other building material trucks and construction equipment can cause
some localized distress to site pavements. The recommended pavement sections are
minimums and periodic maintenance efforts should be expected. A preventative
maintenance program can help increase the service life of site pavements.
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
18
Corrosive Soil Characteristics
We measured the soluble sulfate concentration of two (2) representative samples of the
subsoils which will likely be in contact with structural concrete. The sulfate
concentrations measured in the samples fell within the range of 0 to 150 parts per million.
ACI rates the measured concentrations as being a ‘negligible’ to risk of concrete sulfate
attack; therefore Type I cement should be suitable for concrete members on and below
grade. As an added precaution, Type I/II Portland cement could be considered for
additional sulfate resistance of construction concrete. Foundation concrete should be
designed in accordance with the provisions of the ACI Design Manual, Section 318,
Chapter 4.
Drainage
Positive drainage is imperative for satisfactory long-term performance of the proposed
building, trash enclosure and associated site improvements. We recommend positive
drainage be developed away from the structures during construction and maintained
throughout the life of the site improvements, with twelve (12) inches of fall in the first 10
feet away from the buildings, where possible. Shallower slopes could be considered in
hardscape areas. In the event that some settlement of the building backfill soils occurs
over time, the original grade and associated positive drainage outlined above should be
immediately restored.
Care should be taken in the planning of landscaping to avoid features which could result
in the fluctuation of the moisture content of the foundation bearing and flatwork and
pavement subgrade soils. We recommend watering systems be placed a minimum of 5
feet away from the perimeter of the site structure and be designed to discharge away from
all site improvements. Gutter systems should be considered to help reduce the potential
for water ponding adjacent to the structures, with the gutter downspouts, roof drains or
scuppers extended to discharge a minimum of 5 feet away from structural, flatwork and
pavement elements. Water which is allowed to pond adjacent to site improvements can
result in unsatisfactory performance of those improvements over time.
Geotechnical Subsurface Exploration Report
Harmony Commons Hotel - Lot 6, Harmony Commons
3520 Timberwood Drive, Fort Collins, Colorado
Soilogic # 16-1180
19
LIMITATIONS
This report was prepared based upon the data obtained from the completed site
exploration, laboratory testing, engineering analysis and any other information discussed.
The completed borings provide an indication of subsurface conditions at the boring
locations only. Variations in subsurface conditions can occur in relatively short distances
away from the borings. This report does not reflect any variations which may occur
across the site or away from the borings. If variations in the subsurface conditions
anticipated become evident, the geotechnical engineer should be notified immediately so
that further evaluation and supplemental recommendations can be provided.
The scope of services for this project does not include either specifically or by
implication any biological or environmental assessment of the site or identification or
prevention of pollutants or hazardous materials or conditions. Other studies should be
completed if concerns over the potential of such contamination or pollution exist.
The geotechnical engineer should be retained to review the plans and specifications so
that comments can be made regarding the interpretation and implementation of our
geotechnical recommendations in the design and specifications. The geotechnical
engineer should also be retained to provide testing and observation services during
construction to help determine that the design requirements are fulfilled.
This report has been prepared for the exclusive use of our client for specific application
to the project discussed and has been prepared in accordance with the generally accepted
standard of care for the profession. No warranties express or implied, are made. The
conclusions and recommendations contained in this report should not be considered valid
in the event that any changes in the nature, design or location of the project as outlined in
this report are planned, unless those changes are reviewed and the conclusions of this
report modified and verified in writing by the geotechnical engineer.
LOG OF BORING B-1
1/1 CME 45
4" CFA
Automatic
BMc/ZG
Estimated Swell % Passing
SOIL DESCRIPTION Depth "N" MC DD qu % Swell @ Pressure # 200 Sieve
(ft) (%) (pcf) (psf) 500 psf (psf) LL PI (%)
4 - 6" VEGETATION & TOPSOIL -
1
-
2
-
3 CS 10 11.8 103.1 9000+ None <500 - - -
-
4
-
5 CS 11 11.1 112.2 9000+ None <500 22 9 39.0%
-
6
-
CL-SC SANDY LEAN CLAY with 7
CLAYEY SAND lenses -
brown, rust, beige 8
medium stiff to stiff / loose -
trace GRAVEL 9
-
10 CS 10 17.1 113.1 4000 None <500 - - -
-
11
-
12
-
13
-
14
-
15 CS 8 17.5 111.8 1500 - - - - -
BOTTOM OF BORING @ 15.0' -
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
Sampler
USCS
LOG OF BORING B-2
1/1 CME 45
4" CFA
Automatic
BMc/ZG
Estimated Swell % Passing
SOIL DESCRIPTION Depth "N" MC DD qu % Swell @ Pressure # 200 Sieve
(ft) (%) (pcf) (psf) 500 psf (psf) LL PI (%)
4 - 6" VEGETATION & TOPSOIL -
1
-
2
-
3
-
4
-
5 CS 10 6.8 118.7 9000+ 0.1% - 27 14 41.0%
-
6
-
CL-SC SANDY LEAN CLAY with 7
CLAYEY SAND lenses -
brown, rust, beige 8
medium stiff to stiff / loose -
trace GRAVEL 9
-
10 CS 14 14.9 115.0 6000 None <500 - - -
-
11
-
12
-
13
-
14
-
15 CS 6 20.3 108.4 1500 - - - - -
BOTTOM OF BORING @ 15.0' -
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
Surface Elev. - Field Personnel: 8 Days After Drilling 12.5'
USCS
LOG OF BORING B-3
1/1 CME 45
4" CFA
Automatic
BMc/ZG
Estimated Swell % Passing
SOIL DESCRIPTION Depth "N" MC DD qu % Swell @ Pressure # 200 Sieve
(ft) (%) (pcf) (psf) 500 psf (psf) LL PI (%)
-
1
-
2
-
3
-
4
-
5 CS 12 12.2 113.2 9000+ None <500 - - -
CL-SC SANDY LEAN CLAY with -
CLAYEY SAND lenses 6
brown, rust, beige -
stiff / loose 7
trace GRAVEL -
8
-
9
-
10 CS 11 20.0 109.5 6000 None <500 - - -
-
11
-
12
-
13
CL-CH LEAN to FAT CLAY with SAND -
gray-brown, rust 14
very stiff -
15 CS 26 18.4 112.9 9000 - - - - -
BOTTOM OF BORING @ 15.0' -
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
LOG OF BORING B-4
1/1 CME 45
4" CFA
Automatic
BMc/ZG
Estimated Swell % Passing
SOIL DESCRIPTION Depth "N" MC DD qu % Swell @ Pressure # 200 Sieve
(ft) (%) (pcf) (psf) 500 psf (psf) LL PI (%)
4 - 6" VEGETATION & TOPSOIL -
1
-
2
-
3 CS 10 13.6 108.0 9000+ 0.5% - - - -
-
4
CL-SC SANDY LEAN CLAY with -
CLAYEY SAND lenses 5 CS 9 11.7 114.0 9000+ None <500 - - -
brown, rust, beige -
soft to medium stiff / very loose to loose 6
trace GRAVEL -
7
-
8
-
9
-
10 CS 5 22.5 100.9 7500 - - - - -
BOTTOM OF BORING @ 10.0' -
11
-
12
-
13
-
14
-
15
-
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
Surface Elev. - Field Personnel: 8 Days After Drilling None
USCS
LOG OF BORING B-5
1/1 CME 45
4" CFA
Automatic
BMc/ZG
Estimated Swell % Passing
SOIL DESCRIPTION Depth "N" MC DD qu % Swell @ Pressure # 200 Sieve
(ft) (%) (pcf) (psf) 500 psf (psf) LL PI (%)
-
1
-
2
-
3 CS 9 13.4 109.0 9000+ None <500 - - -
-
CL-SC SANDY LEAN CLAY with 4
CLAYEY SAND lenses -
brown, rust, beige 5 CS 8 10.1 108.0 9000+ None <500 27 13 48.7%
medium stiff / loose -
trace GRAVEL 6
-
7
-
8
-
9
-
10 CS 9 16.5 113.3 4000 - - - - -
BOTTOM OF BORING @ 10.0' -
11
-
12
-
13
-
14
-
15
-
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
LOG OF BORING B-6
1/1 CME 45
4" CFA
Automatic
BMc/ZG
Estimated Swell % Passing
SOIL DESCRIPTION Depth "N" MC DD qu % Swell @ Pressure # 200 Sieve
(ft) (%) (pcf) (psf) 500 psf (psf) LL PI (%)
-
1
-
2
-
3 CS 10 15.8 103.9 9000+ 0.1% - - - -
-
CL-SC SANDY LEAN CLAY with 4
CLAYEY SAND lenses -
brown, rust, beige 5 CS 7 14.1 110.7 9000+ - - - - -
soft to medium stiff / -
very loose to loose 6
trace GRAVEL -
7
-
8
-
9
-
10 CS 3 18.4 95.3 5500 - - - - -
BOTTOM OF BORING @ 10.0' -
11
-
12
-
13
-
14
-
15
-
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
Liquid Limit -
Plasticity Index -
% Passing #200 -
Dry Density (pcf) 103.1
Final Moisture 23.5%
% Swell @ 500 psf None
Swell Pressure (psf) <500
Sample ID: B-1 @ 2'
Sample Description: Brown/Rust Sandy Lean Clay with Clayey Sand lenses (CL-SC)
Initial Moisture 11.8%
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
Project # 16-1180
August 2016
SWELL/CONSOLIDATION TEST SUMMARY
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
10 100 1000 10000 100000
---------
Applied Load (psf)
Liquid Limit 22
Plasticity Index 9
% Passing #200 39.0%
Dry Density (pcf) 112.2
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
Project # 16-1180
August 2016
SWELL/CONSOLIDATION TEST SUMMARY
Sample ID: B-1 @ 4'
Sample Description: Brown/Rust Sandy Lean Clay with Clayey Sand lenses (CL-SC)
(swell only)
Initial Moisture 11.1%
Final Moisture 18.5%
% Swell @ 500 psf None
Swell Pressure (psf) <500
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
10 100 1000 10000 100000
---------
Applied Load (psf)
Liquid Limit -
Plasticity Index -
% Passing #200 -
Dry Density (pcf) 113.1
None
<500
Initial Moisture
Final Moisture
% Swell @ 500 psf
Swell Pressure (psf)
17.1%
18.8%
Sample Description: Brown/Beige/Rust Sandy Lean Clay (CL)
Sample ID: B-1 @ 9'
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
Project # 16-1180
August 2016
SWELL/CONSOLIDATION TEST SUMMARY
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
10 100 1000 10000 100000
---------
Applied Load (psf)
Liquid Limit 27
Plasticity Index 14
% Passing #200 41.0%
Dry Density (pcf) 118.7
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
Project # 16-1180
August 2016
SWELL/CONSOLIDATION TEST SUMMARY
Sample ID: B-2 @ 4'
Sample Description: Brown/Rust Sandy Lean Clay with Clayey Sand lenses (CL-SC)
(swell only)
Initial Moisture 6.8%
Final Moisture 18.5%
% Swell @ 500 psf 0.1%
Swell Pressure (psf) -
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
10 100 1000 10000 100000
---------
Applied Load (psf)
Liquid Limit -
Plasticity Index -
% Passing #200 -
Dry Density (pcf) 115.0
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
Project # 16-1180
August 2016
SWELL/CONSOLIDATION TEST SUMMARY
Sample ID: B-2 @ 9'
Sample Description: Brown/Beige/Rust Sandy Lean Clay (CL)
Initial Moisture 14.9%
Final Moisture 17.2%
% Swell @ 500 psf None
Swell Pressure (psf) <500
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
10 100 1000 10000 100000
---------
Applied Load (psf)
Liquid Limit -
Plasticity Index -
% Passing #200 -
Dry Density (pcf) 113.2
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
Project # 16-1180
August 2016
SWELL/CONSOLIDATION TEST SUMMARY
Sample ID: B-3 @ 4'
Sample Description: Brown/Rust Sandy Lean Clay with Clayey Sand lenses (CL-SC)
(swell only)
Initial Moisture 12.2%
Final Moisture 20.0%
% Swell @ 500 psf None
Swell Pressure (psf) <500
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
10 100 1000 10000 100000
---------
Applied Load (psf)
Liquid Limit -
Plasticity Index -
% Passing #200 -
Dry Density (pcf) 109.5
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
Project # 16-1180
August 2016
SWELL/CONSOLIDATION TEST SUMMARY
Sample ID: B-3 @ 9'
Sample Description: Light Brown/Beige Sandy Lean Clay (CL)
Initial Moisture 20.0%
Final Moisture 21.8%
% Swell @ 500 psf None
Swell Pressure (psf) <500
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
10 100 1000 10000 100000
---------
Applied Load (psf)
Liquid Limit -
Plasticity Index -
% Passing #200 -
Dry Density (pcf) 108.0
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
Project # 16-1180
August 2016
SWELL/CONSOLIDATION TEST SUMMARY
Sample ID: B-4 @ 2'
Sample Description: Brown/Rust Sandy Lean Clay with Clayey Sand lenses (CL-SC)
(swell only)
Initial Moisture 13.6%
Final Moisture 25.3%
% Swell @ 500 psf 0.5%
Swell Pressure (psf) -
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
10 100 1000 10000 100000
---------
Applied Load (psf)
Liquid Limit -
Plasticity Index -
% Passing #200 -
Dry Density (pcf) 114.0
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
Project # 16-1180
August 2016
SWELL/CONSOLIDATION TEST SUMMARY
Sample ID: B-4 @ 4'
Sample Description: Brown/Rust Sandy Lean Clay with Clayey Sand lenses (CL-SC)
(swell only)
Initial Moisture 11.7%
Final Moisture 18.1%
% Swell @ 500 psf None
Swell Pressure (psf) <500
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
10 100 1000 10000 100000
---------
Applied Load (psf)
Liquid Limit -
Plasticity Index -
% Passing #200 -
Dry Density (pcf) 109.0
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
Project # 16-1180
August 2016
SWELL/CONSOLIDATION TEST SUMMARY
Sample ID: B-5 @ 2'
Sample Description: Brown/Rust Sandy Lean Clay with Clayey Sand lenses (CL-SC)
(swell only)
Initial Moisture 13.4%
Final Moisture 19.3%
% Swell @ 500 psf None
Swell Pressure (psf) <500
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
10 100 1000 10000 100000
---------
Applied Load (psf)
Liquid Limit 27
Plasticity Index 13
% Passing #200 48.7%
Dry Density (pcf) 108.0
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
Project # 16-1180
August 2016
SWELL/CONSOLIDATION TEST SUMMARY
Sample ID: B-5 @ 4'
Sample Description: Brown/Rust Sandy Lean Clay with Clayey Sand lenses (CL-SC)
(swell only)
Initial Moisture 10.1%
Final Moisture 24.1%
% Swell @ 500 psf None
Swell Pressure (psf) <500
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
10 100 1000 10000 100000
---------
Applied Load (psf)
Liquid Limit -
Plasticity Index -
% Passing #200 -
Dry Density (pcf) 103.9
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
Project # 16-1180
August 2016
SWELL/CONSOLIDATION TEST SUMMARY
Sample ID: B-6 @ 2'
Sample Description: Brown/Rust Sandy Lean Clay with Clayey Sand lenses (CL-SC)
(swell only)
Initial Moisture 15.8%
Final Moisture 23.0%
% Swell @ 500 psf 0.1%
Swell Pressure (psf) -
-12
-10
-8
-6
-4
-2
0
2
4
6
8
10
12
10 100 1000 10000 100000
---------
Applied Load (psf)
UNIFIED SOIL CLASSIFICATION SYSTEM
Criteria for Assigning Group Symbols and Group Names Using Laboratory TestsA Soil Classification
Group
Symbol
Group NameB
Clean Gravels Cu ! 4 and 1 " Cc " 3E GW Well graded gravelF
Less than 5% finesC Cu
< 4 and/or 1 > Cc > 3E GP Poorly graded gravelF
Fines classify as ML or MH GM Silty gravelF,G, H
Coarse Grained Soils
More than 50% retained
on No. 200 sieve
Gravels
More than 50% of coarse
fraction retained on
No. 4 sieve Gravels with Fines More
than 12% finesC Fines classify as CL or CH GC Clayey gravelF,G,H
Clean Sands Cu ! 6 and 1 " Cc " 3E SW Well graded sandI
Less than 5% finesD Cu
< 6 and/or 1 > Cc > 3E SP Poorly graded sandI
Fines classify as ML or MH SM Silty sandG,H,I
Sands
50% or more of coarse
fraction passes
No. 4 sieve Sands with Fines
More than 12% finesD Fines classify as CL or CH SC Clayey sandG,H,I
Silts and Clays PI > 7 and plots on or above “A” lineJ CL Lean clayK,L,M
Liquid limit less than 50
Inorganic
PI < 4 or plots below “A” lineJ ML SiltK,L,M
Liquid limit - oven
dried
Organic clayK,L,M,N
Fine-Grained Soils
50% or more passes the
No. 200 sieve
Organic
Liquid limit - not
dried
< 0.75 OL
Organic siltK,L,M,O
Inorganic PI plots on or above “A” line CH Fat clayK,L,M
Silts and Clays
Liquid limit 50 or more
PI plots below “A” line MH Elastic siltK,L,M
Organic Liquid limit - oven dried Organic clayK,L,M,P
Liquid limit - not dried
< 0.75 OH
Organic siltK,L,M,Q
Highly organic soils Primarily organic matter, dark in color, and organic odor PT Peat
A Based on the material passing the 3-in. (75-mm) sieve
B If field sample contained cobbles or boulders, or both, add “with cobbles
or boulders, or both” to group name.
C Gravels with 5 to 12% fines require dual symbols: GW-GM well graded
gravel with silt, GW-GC well graded gravel with clay, GP-GM poorly
graded gravel with silt, GP-GC poorly graded gravel with clay.
D Sands with 5 to 12% fines require dual symbols: SW-SM well graded
sand with silt, SW-SC well graded sand with clay, SP-SM poorly graded
sand with silt, SP-SC poorly graded sand with clay
E Cu = D60/D10 Cc =
GENERAL NOTES
DRILLING & SAMPLING SYMBOLS:
SS: Split Spoon - 1⅜" I.D., 2" O.D., unless otherwise noted HS: Hollow Stem Auger
ST: Thin-Walled Tube – 2.5" O.D., unless otherwise noted PA: Power Auger
RS: Ring Sampler - 2.42" I.D., 3" O.D., unless otherwise noted HA: Hand Auger
CS: California Barrel - 1.92" I.D., 2.5" O.D., unless otherwise noted RB: Rock Bit
BS: Bulk Sample or Auger Sample WB: Wash Boring or Mud Rotary
The number of blows required to advance a standard 2-inch O.D. split-spoon sampler (SS) the last 12 inches of the total 18-inch
penetration with a 140-pound hammer falling 30 inches is considered the “Standard Penetration” or “N-value”. For 2.5” O.D.
California Barrel samplers (CB) the penetration value is reported as the number of blows required to advance the sampler 12
inches using a 140-pound hammer falling 30 inches, reported as “blows per inch,” and is not considered equivalent to the
“Standard Penetration” or “N-value”.
WATER LEVEL MEASUREMENT SYMBOLS:
WL: Water Level WS: While Sampling
WCI: Wet Cave in WD: While Drilling
DCI: Dry Cave in BCR: Before Casing Removal
AB: After Boring ACR: After Casing Removal
Water levels indicated on the boring logs are the levels measured in the borings at the times indicated. Groundwater levels at other
times and other locations across the site could vary. In pervious soils, the indicated levels may reflect the location of groundwater.
In low permeability soils, the accurate determination of groundwater levels may not be possible with only short-term observations.
DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the Unified Classification System. Coarse Grained Soils
have more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand.
Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they
are plastic, and silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents
may be added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined
on the basis of their in-place relative density and fine-grained soils on the basis of their consistency.
FINE-GRAINED SOILS COARSE-GRAINED SOILS BEDROCK
(CB)
Blows/Ft.
(SS)
Blows/Ft.
Consistency
(CB)
Blows/Ft.
(SS)
Blows/Ft.
Relative
Density
(CB)
Blows/Ft.
(SS)
Blows/Ft.
Consistency
< 3 0-2 Very Soft 0-5 < 3 Very Loose < 24 < 20 Weathered
3-5 3-4 Soft 6-14 4-9 Loose 24-35 20-29 Firm
6-10 5-8 Medium Stiff 15-46 10-29 Medium Dense 36-60 30-49 Medium Hard
11-18 9-15 Stiff 47-79 30-50 Dense 61-96 50-79 Hard
19-36 16-30 Very Stiff > 79 > 50 Very Dense > 96 > 79 Very Hard
> 36 > 30 Hard
RELATIVE PROPORTIONS OF SAND AND
GRAVEL
GRAIN SIZE TERMINOLOGY
Descriptive Terms of
Other Constituents
Percent of
Dry Weight
Major Component
of Sample
Particle Size
Trace < 15 Boulders Over 12 in. (300mm)
With 15 – 29 Cobbles 12 in. to 3 in. (300mm to 75 mm)
Modifier > 30 Gravel 3 in. to #4 sieve (75mm to 4.75 mm)
Sand
Silt or Clay
#4 to #200 sieve (4.75mm to 0.075mm)
Passing #200 Sieve (0.075mm)
RELATIVE PROPORTIONS OF FINES PLASTICITY DESCRIPTION
Descriptive Terms of
Other Constituents
Percent of
Dry Weight
Term Plasticity Index
Trace
With
Modifiers
< 5
5 – 12
> 12
Non-plastic
Low
Medium
High
0
1-10
11-30
30+
F If soil contains ! 15% sand, add “with sand” to group name.
G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.
HIf fines are organic, add “with organic fines” to group name.
I If soil contains ! 15% gravel, add “with gravel” to group name.
J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.
K If soil contains 15 to 29% plus No. 200, add “with sand” or “with
gravel,” whichever is predominant.
L If soil contains ! 30% plus No. 200 predominantly sand, add
“sandy” to group name.
M If soil contains ! 30% plus No. 200, predominantly gravel, add
“gravelly” to group name.
N PI ! 4 and plots on or above “A” line.
O PI < 4 or plots below “A” line.
P PI plots on or above “A” line.
Q PI plots below “A” line.
Project # 16-1180
August 2016
Sheet Drilling Rig: Water Depth Information
Start Date 7/21/2016 Auger Type: During Drilling None
Finish Date 7/21/2016 Hammer Type: After Drilling None
Surface Elev. - Field Personnel: 8 Days After Drilling None
USCS
Sampler
Atterberg Limits
Project # 16-1180
August 2016
Sheet Drilling Rig: Water Depth Information
Start Date 7/21/2016 Auger Type: During Drilling None
Finish Date 7/21/2016 Hammer Type: After Drilling None
Surface Elev. - Field Personnel: 8 Days After Drilling None
USCS
Sampler
Atterberg Limits
Sampler
Atterberg Limits
Start Date 7/21/2016 Auger Type: During Drilling None
Finish Date 7/21/2016 Hammer Type: After Drilling None
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
Project # 16-1180
August 2016
Sheet Drilling Rig: Water Depth Information
Project # 16-1180
August 2016
Sheet Drilling Rig: Water Depth Information
Start Date 7/21/2016 Auger Type: During Drilling None
Finish Date 7/21/2016 Hammer Type: After Drilling None
Surface Elev. - Field Personnel: 8 Days After Drilling 12.0'
USCS
Sampler
Atterberg Limits
Sampler
Atterberg Limits
Start Date 7/21/2016 Auger Type: During Drilling None
Finish Date 7/21/2016 Hammer Type: After Drilling None
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
Project # 16-1180
August 2016
Sheet Drilling Rig: Water Depth Information
Surface Elev.
None
Auger Type:
Drilling Rig:
Hammer Type:
Field Personnel:
7/21/2016
-
Water Depth Information
7/21/2016 None
3520 TIMBERWOOD DRIVE, FORT COLLINS, COLORADO
Project # 16-1180
August 2016
HARMONY COMMONS HOTEL - LOT 6, HARMONY COMMONS
Atterberg Limits
12.5'
During Drilling
After Drilling
Sheet
Start Date
Finish Date
8 Days After Drilling