HomeMy WebLinkAboutPROSPECT SPORTS CLUB - FDP240002 - SUBMITTAL DOCUMENTS - ROUND 1 - Geotechnical (Soils) ReportGEOTECHNICAL SUBSURFACE EXPLORATION REPORT
PROSPECT PROPERTIES BASKETBALL FACILITY
LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
SOILOGIC # 22-1426
December 19, 2022
Soilogic, Inc.
3522 Draft Horse Court • Loveland, CO 80538 • (970) 535-6144
December 19, 2022
RB+B Architects, Inc.
315 E. Mountain Avenue, Suite 100
Fort Collins, Colorado 80524
Attn: Ms. Rebecca Spears
Re: Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility
Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
Ms. Spears:
Soilogic, Inc. (Soilogic) personnel have completed the geotechnical subsurface exploration
you requested for the proposed Prospect Properties Basketball Facility to be constructed
on Lot 5 of the Prospect Park East, P.U.D. in Fort Collins, Colorado. The results of our
subsurface exploration and pertinent geotechnical engineering recommendations are
included with this report.
In summary, the subsurface materials encountered in the completed site borings consisted
of a thin mantle of vegetation and topsoil underlain by brown/beige/rust lean clay with
varying amounts of sand. The near-surface portion of this material was somewhat mottled
in color and was identified as possible overlot grading fill material which may been placed
to develop existing site grades, and appeared to extend to depths of about 2 to 3 feet below
ground surface, where it was underlain by apparently-natural lean clay with sand. The
possible existing fill and/or natural lean clay contained minor amounts of gravel, varied
from medium stiff to hard in terms of consistency, exhibited no to high swell potential at
in-situ moisture and density conditions and extended to depths ranging from approximately
3½ to 7 feet below ground surface, where it was underlain by brown/rust sand with silt and
gravel. The sand and gravel varied from medium dense to very dense in terms of relative
density, would be expected to be non-expansive or possess low swell potential based on
the physical properties and engineering characteristics of the material, and extended to the
bottom of all borings at depths between approximately 10 and 15 feet below present ground
surface.
Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility - Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
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Groundwater was encountered at depths between 7 and 10 feet below ground surface in
borings B-1 through B-9, while boring B-10 remained dry to the depth explored (about 10
feet below ground surface) at the time of drilling. When checked six (6) days after the
completion of drilling, a dry cave-in was measured at a depth of about 6½ feet below
ground surface in boring B-1, groundwater or wet cave-ins were measured at depths
between about 6 and 8½ feet below ground surface in borings B-2 through B-9, and boring
B-10 remained dry to the depth explored at that time.
Based on the subsurface conditions encountered in the completed site borings, results of
laboratory testing and type of construction proposed, it is our opinion the proposed
basketball facility building could be constructed with conventional spread footing
foundations and floor slabs bearing directly on a mat of properly placed and compacted
overexcavation/backfill due to the presence of possible existing fill and expansive near-
surface lean clay soils. Similar overexcavation/backfill methods are recommended to
develop low volume-change (LVC) pavement support. The reconditioned site lean clay
soils appear suitable for use as LVC fill and overexcavation/backfill to develop the site and
could be used for support of the building floor slabs and site pavements. The
overexcavation/backfill procedures will help develop LVC-potential foundation bearing/
floor slab and pavement support, reducing the potential for total and differential movement
of those supported elements subsequent to construction. The risk of some movement cannot
be eliminated. Other opinions and recommendations concerning design criteria and
construction details for the proposed site improvements are included with this report.
Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility - Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
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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. Alec Kaljian, P.E.
Senior Project Engineer Project Engineer
12/19/2022 12/19/2022
Soilogic, Inc.
3522 Draft Horse Court • Loveland, CO 80538 • (970) 535-6144
GEOTECHNICAL SUBSURFACE EXPLORATION REPORT
PROSPECT PROPERTIES BASKETBALL FACILITY
LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
SOILOGIC # 22-1426
December 19, 2022
INTRODUCTION
This report contains the results of the completed geotechnical subsurface exploration for
the proposed Prospect Properties Basketball Facility to be constructed on Lot 5 of the
Prospect Park East, P.U.D., located at 1601 Sharp Point Drive 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 proposed automobile wash building foundations
and support of floor slabs and site pavements. The conclusions and recommendations
outlined in this report are based on the results of the completed field and laboratory testing
and our experience with subsurface conditions in this area.
PROPOSED CONSTRUCTION
Based on the provided site plan, we understand the proposed building will be a single-story
concrete masonry unit (CMU) and/or steel-frame structure constructed as slab-on-grade
encompassing a plan area of approximately 40,000 square feet. Foundation loads for the
structure are expected to be light to moderate, with continuous wall loads on the order of 4
to 6 kips per lineal foot and individual column loads less than 150 kips. Paved drive lane
and parking areas are anticipated on the east side of the building as part of the proposed
site improvements. Traffic loading on site pavements is expected to consist of relatively
low volumes of light passenger vehicles, with occasional delivery and trash truck traffic.
Small grade changes are anticipated to develop finish site grades in the building and
pavement areas.
SITE DESCRIPTION
The development property is identified as Lot 5 of the Prospect Park East, P.U.D., located
at 1601 Sharp Point Drive in Fort Collins, Colorado. At the time of our site exploration,
the lot was vacant/undeveloped. The ground surface across the site contained a moderate
Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility - Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
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growth of native grass vegetation and was observed to be relatively level within a majority
of the approximate building footprint. The maximum difference in ground surface
elevation across most of the building footprint is estimated to be on the order of about two
(2) feet or less based upon review of a provided topographic survey of the property. A
small grove of small to medium-sized diameter deciduous trees was noted in a slight
depression in the south-central portion of the property, within the eastern portion of the
proposed building footprint. This area appeared to be two (2) to three (3) feet lower in
elevation than the rest of the approximate area of construction. Evidence of prior building
construction was not observed in the proposed construction area at the time of our
exploration. The Prospect Ponds, which appear to consist of reclaimed aggregate mining
water impoundments, were also noted to the east of the property.
SITE EXPLORATION
Field Exploration
To develop subsurface information for the proposed site improvements, a total of ten (10)
soil borings were completed. Eight (8) borings were advanced in the area of the proposed
gym building to a depth of approximately 15 feet below ground surface. Two (2) additional
borings were completed in proposed pavement areas to a depth of approximately 10 feet
below ground surface. The boring locations were established in the field by Soilogic
personnel based on a provided site plan, by pacing and estimating angles and distances
from identifiable site references. A diagram indicating the approximate boring locations is
included with this report. The boring locations indicated on the attached diagram should
be considered accurate only to the degree implied by the methods used to make the field
measurements. 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 and split-barrel sampling procedures in general
accordance with ASTM specification D-1586. As part of the D-1586 sampling procedure,
standard sampling barrels are driven into the substrata using a 140-pound hammer falling
a distance of 30 inches. The number of blows required to advance the samplers a distance
of 12 inches is recorded and helpful in estimating the consistency or relative density of the
Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility - Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
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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 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/bedrock 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/bedrock characteristics.
Atterberg limits tests are used to determine soil/bedrock 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/bedrock 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. As part of laboratory testing, water soluble sulfate (WSS) tests are being
completed on two (2) selected samples of the lean clay soils to help evaluate corrosive soil
characteristics with respect to buried concrete and results will be provided under separate
cover when they become available.
SUBSURFACE CONDITIONS
In summary, the subsurface materials encountered in the completed site borings consisted
of a thin mantle of vegetation and topsoil underlain by brown/beige/rust lean clay with
varying amounts of sand. The near-surface portion of this material was somewhat mottled
in color and was identified as possible overlot grading fill material which may been placed
to develop existing site grades, and appeared to extend to depths of about 2 to 3 feet below
Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility - Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
4
ground surface, where it was underlain by apparently-natural lean clay with sand. The
possible existing fill and/or natural lean clay contained minor amounts of gravel, varied
from medium stiff to hard in terms of consistency, exhibited no to high swell potential at
in-situ moisture and density conditions and extended to depths ranging from approximately
3½ to 7 feet below ground surface, where it was underlain by brown/rust sand with silt and
gravel. The sand and gravel varied from medium dense to very dense in terms of relative
density, would be expected to be non-expansive or possess low swell potential based on
the physical properties and engineering characteristics of the material, and extended to the
bottom of all borings at depths between approximately 10 and 15 feet below present ground
surface.
The stratigraphy on the included boring logs represents the approximate location of
changes in soil types. Actual changes may be more gradual than those indicated.
Groundwater was encountered at depths between 7 and 10 feet below ground surface in
borings B-1 through B-9, while boring B-10 remained dry to the depth explored (about 10
feet below ground surface) at the time of drilling. When checked six (6) days after the
completion of drilling, a dry cave-in was measured at a depth of about 6½ feet below
ground surface in boring B-1, groundwater or wet cave-ins were measured at depths
between about 6 and 8½ feet below ground surface in borings B-2 through B-9, and boring
B-10 remained dry to the depth explored at that time. Groundwater levels are recorded in
the upper right-hand corner of the attached boring logs.
Groundwater levels will vary seasonally and over time based on weather conditions, site
development, irrigation practices and other hydrologic conditions. Groundwater levels
would be expected to be directly impacted by water levels in the Prospect Ponds. 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. Trapped water is typically encountered within more permeable zones of
layered soil and bedrock systems. The location and amount of perched/trapped water can
also vary over time.
Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility - Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
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ANALYSIS AND RECOMMENDATIONS
General
The possible existing fill and/or natural lean clay soils encountered near-surface in the
borings drilled across this site exhibited variable swell potential (ranging from low to high)
at in-situ moisture and density conditions. Total and differential heaving of site
improvements placed directly on or immediately above the existing fill and/or expansive
lean clay soil would be expected as the moisture content of those materials increases
subsequent to construction.
Based on the subsurface conditions encountered in the completed site borings, results of
laboratory testing and type of construction proposed, it is our opinion overexcavation/
backfill procedures could be completed beneath the building foundations and floor slabs to
reduce the potential for movement of those supported elements subsequent to construction.
The risk of some movement cannot be eliminated. Recommendations concerning
overexcavation/backfill procedures to redevelop low volume change (LVC) foundation
and floor slab support for the building are outlined below. If some structural and floor slab
movement and associated distress cannot be tolerated, drilled pier foundations and
structural floor systems should be employed.
Drilled pier foundations and structural floor systems would offer an effective system for
mitigating the potential for total and differential movement of the building foundation and
floor slab subsequent to construction in the expansive soil environment. Drilled piers would
anchor the building into bedrock underlying the site, significantly reducing the potential
for movement of the structure. Deeper subsurface exploration would be required to develop
soil design parameters for use in drilled pier design. If drilled pier foundations are to be
used, structural flooring systems or overexcavation/backfill procedures to develop LVC
floor slab subgrades would be required. Recommendations concerning the design and
construction of drilled pier foundations and structural flooring systems can be provided at
your request.
Groundwater was measured in the open boreholes at depths ranging from approximately 6
to 8½ feet below ground surface when checked six (6) days after the completion of drilling.
Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility - Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
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Although not anticipated, dewatering of removal excavations as part of the overexcavation/
backfill procedures outlined above may be required to facilitate proper construction.
Recommendations concerning dewatering procedures (if necessary) are included with this
report.
Foundation Bearing and Subgrade Development
To develop low-volume-change (LVC) potential foundation and floor slab support, and
reduce the potential for total and differential movement of the building foundation and
floor slab subsequent to construction, we recommend a zone of reconditioned soil be
developed beneath those supported elements. The reconditioned mat will provide a zone
of material immediately beneath the building foundation and floor slab which will have
low potential for volume change subsequent to construction. The LVC mat and surcharge
loads placed on the underlying soils/bedrock by the reconditioned mat would reduce the
potential for total and differential movement of the supported improvements subsequent to
construction. The reconditioned zone would also assist in distributing movement in the
event that some swelling of the materials underlying the reconditioned zone occurs.
The overexcavation zone should include the entire building footprint and extend to natural,
undisturbed, moist lean clay and/or sand and gravel with no to low swell potential,
anticipated to be encountered at depths within about three (3) feet of intended foundation
bearing elevations. The overexcavation area should also extend a minimum of two (2) feet
laterally beyond the exterior edges of the building footprint.
Since movement of site pavements is generally considered to be less consequential than
structural and floor slab movement, it is our opinion the overexcavation zone beneath site
pavements could be reduced to a minimum of 24 inches below finish subgrade levels, with
the understanding that some movement of site pavements may occur subsequent to
construction. The 24-inch LVC zone beneath site pavements could be developed through
any combination of overexcavation/backfill procedures, subgrade reconditioning and new
fill placement.
Soils used as overexcavation/backfill should consist of approved materials free from
organic matter, debris and other objectionable materials. Based on results of the completed
Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility - Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
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laboratory testing, it is our opinion the possible existing fill and/or natural site lean clay
could be used as overexcavation/backfill provided care is taken to develop the proper
moisture content in those materials at the time of placement and compaction. Essentially-
granular structural fill materials could be used below the building footprint where
overexcavation will remove the existing fill and expansive lean clay soil to natural
underlying soil with no to low swell potential, but should not be used as backfill below site
pavements where only limited overexcavation will be completed due to the ability of these
materials to pond and transmit water.
All existing topsoil and vegetation should be removed from the proposed building,
pavement and any proposed fill areas. After stripping and completing all cuts and
overexcavation procedures and prior to placement of any new fill or overexcavation/
backfill, 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 scarified lean soils should be adjusted to
be within the range of -1 to +3% of standard Proctor optimum moisture content at the time
of compaction, while scarified sand and gravel soils should be adjusted to within the range
of ±2% of the materials standard Proctor optimum moisture content. Fill and
overexcavation/backfill materials consisting of the site lean clay, sand and gravel and/or
similar soils 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. At the high end
of the above recommended moisture content range, some pumping of the lean clay
overexcavation/backfill materials may be observed and would be expected.
Care should be taken to maintain the proper moisture content in the bearing/subgrade soils
prior to foundation and floor slab concrete placement and/or paving. The prepared
structural mat 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.
Inherent risks exist when building in areas of expansive soils/bedrock. The overexcavation/
backfill procedures outlined above will reduce, but not eliminate, the potential for
movement of the building foundation, floor slab and site pavements subsequent to
Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility - Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
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construction. The in-place materials below the moisture conditioned zone can increase in
moisture content causing movement of the overlying improvements. Some movement of
the lightly-loaded building floor slab and site pavements should be expected. If some
limited structural and floor slab movement and associated distress cannot be tolerated,
drilled pier foundations and structural floor systems should be employed.
Dewatering
Groundwater was measured in most of the open boreholes at depths ranging from
approximately 6 to 8½ feet below ground surface when checked about six (6) days after
the completion of drilling. As a result, dewatering parts of the removal excavations as
recommended above is not expected, but may be required in limited areas.
Based on the materials encountered in the completed site borings, results of laboratory
testing and observed depth to groundwater, we expect dewatering of smaller removal
excavations could be completed through open pumping procedures from sumps and
ditches. Larger removal excavations may require well-point systems to keep up with
infiltration water. Dewatering procedures would be expected to be facilitated if
construction is completed during periods of seasonal low groundwater levels. It has been
our experience that seasonal low groundwater levels typically occur over winter or late
summer, several weeks after localized irrigation features stop running water.
For open pumping dewatering procedures, care should be taken to construct a suitable
sump outside of the improvement area. Fine-grained materials can be drawn to the sump
area, creating unsuitable bearing conditions. A sump should consist of a slotted pipe large
enough to house a submersible pump, extended deep enough such that when it is pumped
out, the entire excavation will be drained. Pumps are typically suspended a minimum of 12
inches above the bottom of the pit in order to provide room for sediment. The slotted pipe
should be surrounded by a much larger mass of free-draining gravel. A ¾-inch screened
rock could be considered to develop the sedimentation zone. A larger sedimentation zone
will reduce water velocities, allowing fines to settle out prior to entering the slotted pipe
and mechanical pump. Periodic cleaning and maintenance of the sump should be
anticipated.
Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility - Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
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Drainage ditches should be constructed outside of the immediate work area to allow for
collection of the infiltration waters and feeding of the sump. It may be necessary to
construct shallow ditches around the perimeter of the foundation excavations in order to
help intercept any infiltration water before it enters and flows laterally across the interior
of the excavation to reach the drains. Ditches should be filled with free-draining gravel to
reduce the potential for erosion and sloped to provide positive gravity drainage to the sump.
For larger water infiltration rates, socked perforated pipe could be installed within the free
draining aggregate in the collection ditches in order to facilitate drainage to the sump.
Perforated pipe should not be installed beneath foundation concrete or within the zone of
foundation influence which can be estimated at a 1:1 slope extending out from the bottom
edges of the pads.
Careful observation of seepage waters should be completed at the start of pumping. If
excessive fines are observed being transported up from the bottom or out of the sides of
any excavation, pumping should be stopped and the excavation flooded until methods to
reduce soil migration can be employed.
Foundations
For design of spread footing foundations bearing on a suitable zone of overexcavation/
backfill soils placed and compacted as outlined above, we recommend using a maximum
net allowable soil bearing pressure of 1,500 psf. As a precaution, we recommend
continuous spread footing and isolated pad foundations be designed to maintain a minimum
dead-load pressure of 500 psf (or as high as practical) on the supporting soils.
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
order to facilitate construction and reduce the potential for development of eccentrically
loaded footings. Actual footing widths should be designed by a structural engineer.
For design of spread footing foundations and foundation walls to resist lateral movement,
a passive equivalent fluid pressure value of 250 pcf could be used. The top 30 inches of
subgrade could be considered a surcharge load but should not be used in the passive
Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility - Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
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resistance calculations. A coefficient of friction of 0.35 could be used between foundation
and floor slab concrete and the bearing/subgrade soils to resist sliding. The recommended
passive equivalent fluid pressure value and coefficient of friction do not include a factor of
safety.
Backfill placed adjacent to foundation walls should consist of approved LVC soils free
from organic matter, debris and other objectionable materials. The on-site lean clay and
sand and gravel could be used as foundation wall backfill. Foundation wall backfill soils
should be placed in loose lifts not to exceed 9 inches thick, adjusted in moisture and
compacted as outlined in the “Foundation Bearing and Subgrade Development” section of
this report.
Excessive lateral stresses can be imposed on 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.
We estimate settlement of footing foundations supported on a suitable mat of properly-
placed and compacted overexcavation/backfill and resulting from the assumed structural
loads would be less than 1 inch. Differential settlement could approach the amount of total
settlement estimated above. If water from any source is allowed to infiltrate the foundation
bearing soils, additional movement of those supported elements could occur.
Seismicity
Based on the results of this investigation and Soilogic review of the Minimum Design
Loads and Associated Criteria for Buildings and Other Structures (ASCE/SEI 7-22), a soil
profile type CD 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 = 0.15 and SD1 = 0.051 could be used.
Floor Slabs
The building floor slab could be supported directly on a suitable zone of overexcavation/
backfill material placed and compacted as outlined above. A modulus of subgrade reaction
Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility - Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
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(k) value of 150 pci could be used for design of floor slabs supported on overexcavation/
backfill soils consisting of the on-site clay and/or similar soils. Disturbed subgrades or
subgrade materials that have been allowed to dry out or become wet and softened should
be removed and replaced or reconditioned in place prior to concrete placement.
The floor slab should be designed and constructed as a floating slab, separated from
foundation walls, columns and plumbing and mechanical penetrations by the use of block-
outs or appropriate isolation material. In addition, we recommend all partition walls
supported above isolated 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 slab, 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, a vapor barrier
may be required immediately beneath the floor slab in order to maintain flooring product
manufacturer warranties. A vapor barrier would help reduce the transmission of moisture
through the floor slabs. However, the unilateral moisture release caused by placing
concrete on an impermeable surface can increase slab curl. The amount of slab curl can be
reduced by careful selection of an appropriate concrete mix. Slab curl cannot be eliminated.
We recommend 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.
Pavement and Exterior Flatwork Subgrades
Pavement subgrades should be developed as outlined in the “Foundation Bearing and
Subgrade Development” section of this report. Site pavements could be supported directly
on suitable overexcavation/backfill soils placed and compacted as outlined in that section.
Care should be taken to avoid disturbing the overexcavation/backfill soils prior to
Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility - Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
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placement of site pavements. 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.
Some movement of site pavements should be expected as the moisture content of the
subgrade soils increases subsequent to construction. Deeper overexcavation/backfill
procedures could be considered beneath site pavements to further reduce the potential for
post-construction movement of those supported improvements. Care should be taken to
ensure that when site pavements move, positive drainage will be maintained away from the
structure.
Site Pavements
Based on the materials encountered in the completed site borings and results of laboratory
testing, pavement subgrades are expected to consist of reconditioned lean clay. These soils
classify as A-6 soils in accordance with the American Association of State and Highway
Transportation Officials (AASHTO) classification system and would be expected to
exhibit low remolded shear strength. A resistance value (R-value) of 5 was estimated for
the 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 of higher light vehicle traffic volumes and
occasional heavier trash and delivery trucks. 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 higher traffic volumes or heavy truck
traffic.
Proofrolling of the pavement subgrades should be completed to help identify unstable
areas. Areas which pump or deform excessively should be mended prior to aggregate base
course and asphaltic concrete placement. Isolated areas of subgrade instability can be
mended on a case-by-case basis. If more extensive areas of subgrade instability are
Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility - Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
13
observed we recommend consideration be given to stabilization of the pavement subgrades
with Class C fly ash or Portland cement (pending results of water-soluble sulfate testing).
With the increase in support strength developed by the chemical 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 chemical-stabilized subgrade
soils are outlined below in Table I.
It has been our experience that full-depth asphaltic concrete pavement sections typically
do not perform as well as structurally equivalent composite pavement sections in areas of
lean clay subgrade soils and we do not recommend full-depth asphalt sections be
constructed for this project. Alternative pavement sections could be considered and we
would be happy to discuss any alternatives at your request.
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)
Chemically Stabilized Subgrade
3”
4”
12”
4”
6”
12”
Option C – Portland Cement Concrete Pavement 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 or other governing entity. Aggregate used in the asphaltic concrete
should meet specific 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
Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility - Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
14
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 (or 5% Portland cement, pending results of water-soluble sulfate content
testing being completed on the subgrade soils) based on component dry unit weights. A
12-inch thick stabilized zone should be constructed by thoroughly blending the fly ash or
Portland cement 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 and 30 minutes of cement 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 4,000 or 4,500 psi (pending results of WSS testing). Woven wire
mesh or fiber entrained concrete should be considered to help in the control of shrinkage
cracking.
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.
Drainage
Positive drainage is imperative for satisfactory long-term performance of the proposed
building and associated site improvements. We recommend positive drainage be developed
away from the structure 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 building.
Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility - Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
15
Shallower slopes could be considered in hardscape areas. In the event that poor or negative
drainage develops adjacent to the building 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 structure, 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.
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
Geotechnical Subsurface Exploration Report
Prospect Properties Basketball Facility - Lot 5, Prospect Park East, P.U.D.
1601 Sharp Point Drive, Fort Collins, Colorado
Soilogic # 22-1426
16
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
JJ / BM
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
POSSIBLE EXISTING FILL MATERIAL;-
CL LEAN CLAY with SAND 2
brown, beige, rust -
minor GRAVEL 3
-
4
-
5 CS 42 7.4 -N/A --NL NP 6.5%
-
6
-
7
-
SP-SM SAND with SILT and GRAVEL 8
brown, rust -
medium dense to dense 9
-
10 CS 34 5.0 -N/A -----
-
11
-
12
-
13
-
14
-
15 CS 50/11 6.0 -N/A -----
BOTTOM OF BORING @ 15.0'-
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
US
C
S
Sa
m
p
l
e
r
Atterberg Limits
Surface Elev.-Field Personnel:6 Days After Drilling Dci @ 6'
Finish Date 12/5/2022 Hammer Type:After Drilling Wci @ 7'
Sheet Drilling Rig:Water Depth Information
Start Date 12/5/2022 Auger Type:During Drilling 7.0'
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
LOG OF BORING B-2
1/1 CME 45
4" CFA
Automatic
JJ / BM
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' POSSIBLE EXISTING FILL -
2
CL LEAN CLAY with SAND -
to SC varies to CLAYEY SAND 3 CS 28 9.6 116.9 9000+2.8%5600 ---
brown, beige, rust -
stiff to very stiff / loose to medium dense 4
minor GRAVEL -
5 CS 12 19.5 106.7 7500 --34 15 44.4%
-
6
-
7
-
8
-
9
-
SP-SM SAND with SILT and GRAVEL 10 CS 36 4.7 -N/A -----
brown, rust -
medium dense to dense 11
-
12
-
13
-
14
-
15 CS 50 8.0 -N/A -----
BOTTOM OF BORING @ 15.0'-
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
Sheet Drilling Rig:Water Depth Information
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
US
C
S
Sa
m
p
l
e
r
Atterberg Limits
Start Date 12/5/2022 Auger Type:During Drilling 9.0'
Finish Date 12/5/2022 Hammer Type:After Drilling Wci @ 9'
Surface Elev.-Field Personnel:6 Days After Drilling 8.0'
LOG OF BORING B-3
1/1 CME 45
4" CFA
Automatic
JJ / BM
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' POSSIBLE EXISTING FILL -
2
-
CL LEAN CLAY with SAND 3
brown, beige, rust -
hard 4
minor GRAVEL -
5 CS 50/11 14.1 105.3 9000+3.2%4500 ---
-
6
-
7
-
8
-
9
-
SP-SM SAND with SILT and GRAVEL 10 CS 26 4.8 -N/A -----
brown, rust -
medium dense to dense 11
-
12
-
13
-
14
-
15 CS 50/8 6.2 -N/A -----
BOTTOM OF BORING @ 15.0'-
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
Sheet Drilling Rig:Water Depth Information
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
US
C
S
Sa
m
p
l
e
r
Atterberg Limits
Start Date 12/5/2022 Auger Type:During Drilling 9.5'
Finish Date 12/5/2022 Hammer Type:After Drilling Wci @ 9.5'
Surface Elev.-Field Personnel:6 Days After Drilling Wci @ 8.5'
LOG OF BORING B-4
1/1 CME 45
4" CFA
Automatic
JJ / BM
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' POSSIBLE EXISTING FILL -
2
-
CL LEAN CLAY with SAND 3 CS 40 9.4 120.3 9000+5.5%10400 ---
brown, beige, rust -
medium stiff to hard 4
minor GRAVEL -
5 CS 7 15.6 100.3 5000 None <500 ---
-
6
-
7
-
8
-
9
-
SP-SM SAND with SILT and GRAVEL 10 CS 32 NR NR ------
brown, rust -
medium dense to very dense 11
-
12
-
13
-
14
-
15 CS 50/6 7.1 -N/A -----
BOTTOM OF BORING @ 15.0'-
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
Sheet Drilling Rig:Water Depth Information
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
US
C
S
Sa
m
p
l
e
r
Atterberg Limits
Start Date 12/5/2022 Auger Type:During Drilling 9.0'
Finish Date 12/5/2022 Hammer Type:After Drilling Wci @ 9'
Surface Elev.-Field Personnel:6 Days After Drilling 6.0'
LOG OF BORING B-5
1/1 CME 45
4" CFA
Automatic
JJ / BM
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' POSSIBLE EXISTING FILL -
2
CL LEAN CLAY with SAND -
brown, beige, rust 3 CS 34 11.3 120.1 9000+2.4%4700 ---
very stiff -
minor GRAVEL 4
-
5 CS 20 12.1 115.3 9000+-----
-
6
-
7
-
8
-
9
SP-SM SAND with SILT and GRAVEL -
brown, rust 10 CS 29 9.0 -N/A -----
medium dense -
11
-
12
-
13
-
14
-
15 CS 34 7.0 -N/A -----
BOTTOM OF BORING @ 15.0'-
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
Sheet Drilling Rig:Water Depth Information
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
US
C
S
Sa
m
p
l
e
r
Atterberg Limits
Start Date 12/5/2022 Auger Type:During Drilling 9.5'
Finish Date 12/5/2022 Hammer Type:After Drilling Wci @ 9.5'
Surface Elev.-Field Personnel:6 Days After Drilling Wci @ 8.5'
LOG OF BORING B-6
1/1 CME 45
4" CFA
Automatic
JJ / BM
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 -
POSSIBLE EXISTING FILL MATERIAL;1
CL LEAN CLAY with SAND -
brown, beige, rust 2
very stiff -
minor GRAVEL 3 CS 19 6.8 122.2 9000+-----
-
4
-
5 CS 34 7.9 -N/A -----
-
6
-
7
-
8
-
SP-SM SAND with SILT and GRAVEL 9
brown, rust -
medium dense to dense 10 CS 39 7.0 -N/A --NL NP 4.7%
-
11
-
12
-
13
-
14
-
15 CS 50/11 6.0 -N/A -----
BOTTOM OF BORING @ 15.0'-
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
Sheet Drilling Rig:Water Depth Information
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
US
C
S
Sa
m
p
l
e
r
Atterberg Limits
Start Date 12/5/2022 Auger Type:During Drilling 7.0'
Finish Date 12/5/2022 Hammer Type:After Drilling Wci @ 7'
Surface Elev.-Field Personnel:6 Days After Drilling Wci @ 6.5'
LOG OF BORING B-7
1/1 CME 45
4" CFA
Automatic
JJ / BM
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' POSSIBLE EXISTING FILL -
2
-
CL LEAN CLAY with SAND 3
brown, beige, rust -
hard 4
minor GRAVEL -
5 CS 50/10 10.4 118.0 9000+1.3%2900 ---
-
6
-
7
-
8
-
9
-
SP-SM SAND with SILT and GRAVEL 10 CS 28 5.9 -N/A -----
brown, rust -
medium dense to dense 11
-
12
-
13
-
14
-
15 CS 50/8 6.3 -N/A -----
BOTTOM OF BORING @ 15.0'-
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
Sheet Drilling Rig:Water Depth Information
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
US
C
S
Sa
m
p
l
e
r
Atterberg Limits
Start Date 12/5/2022 Auger Type:During Drilling 10.0'
Finish Date 12/5/2022 Hammer Type:After Drilling Wci @ 10'
Surface Elev.-Field Personnel:6 Days After Drilling Wci @ 8'
LOG OF BORING B-8
1/1 CME 45
4" CFA
Automatic
JJ / BM
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' POSSIBLE EXISTING FILL -
2
-
3 CS 28 9.4 118.6 9000+3.2%5500 ---
CL LEAN CLAY with SAND -
brown, beige, rust 4
very stiff -
minor GRAVEL 5 CS 30 10.2 120.7 9000+3.6%6800 ---
-
6
-
7
-
8
-
9
-
10 CS 36 6.6 -N/A -----
SP-SM SAND with SILT and GRAVEL -
brown, rust 11
medium dense to dense -
12
-
13
-
14
-
15 CS 50/10 7.2 -N/A -----
BOTTOM OF BORING @ 15.0'-
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
Sheet Drilling Rig:Water Depth Information
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
US
C
S
Sa
m
p
l
e
r
Atterberg Limits
Start Date 12/5/2022 Auger Type:During Drilling 9.0'
Finish Date 12/5/2022 Hammer Type:After Drilling Wci @ 9'
Surface Elev.-Field Personnel:6 Days After Drilling Wci @ 8.5'
LOG OF BORING B-9
1/1 CME 45
4" CFA
Automatic
JJ / BM
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' POSSIBLE EXISTING FILL -
2
-
CL LEAN CLAY with SAND 3 CS 31 10.3 122.9 9000+4.8%10600 ---
brown, beige, rust -
very stiff to hard 4
minor GRAVEL -
5 CS 38 8.8 122.5 9000+4.5%10200 ---
-
6
-
7
SP-SM SAND with SILT and GRAVEL -
brown, rust 8
medium dense -
9
-
10 CS 36 5.8 -N/A -----
BOTTOM OF BORING @ 10.0'-
11
-
12
-
13
-
14
-
15
-
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
Sheet Drilling Rig:Water Depth Information
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
US
C
S
Sa
m
p
l
e
r
Atterberg Limits
Start Date 12/5/2022 Auger Type:During Drilling 10.0'
Finish Date 12/5/2022 Hammer Type:After Drilling Wci @ 10'
Surface Elev.-Field Personnel:6 Days After Drilling Wci @ 8.5'
LOG OF BORING B-10
1/1 CME 45
4" CFA
Automatic
JJ / BM
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' POSSIBLE EXISTING FILL -
2
CL LEAN CLAY with SAND -
brown, beige, rust 3 CS 37 7.5 123.4 9000+-----
very stiff to hard -
minor GRAVEL 4
-
5 CS 50/7 6.3 -N/A -----
-
6
-
SP-SM SAND with SILT and GRAVEL 7
brown, rust -
medium dense 8
-
9
-
10 CS 31 8.0 -N/A -----
BOTTOM OF BORING @ 10.0'-
11
-
12
-
13
-
14
-
15
-
16
-
17
-
18
-
19
-
20
-
21
-
22
-
23
-
24
-
25
Sheet Drilling Rig:Water Depth Information
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
US
C
S
Sa
m
p
l
e
r
Atterberg Limits
Start Date 12/5/2022 Auger Type:During Drilling None
Finish Date 12/5/2022 Hammer Type:After Drilling None
Surface Elev.-Field Personnel:6 Days After Drilling None
Liquid Limit -
Plasticity Index -
% Passing #200 -
Dry Density (pcf)116.9
500
Final Moisture 13.6%
% Swell @ 500 psf 2.8%
Swell Pressure (psf)5,600
Sample ID: B-2 @ 2
Initial Moisture 9.6%
Sample Description: Possible Existing Fill; Brown Sandy Lean Clay (CL), minor Gravel
SWELL/CONSOLIDATION TEST SUMMARY
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
-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)105.3
SWELL/CONSOLIDATION TEST SUMMARY
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
Initial Moisture 14.1%
Sample ID: B-3 @ 4
Sample Description: Dark Brown/Brown Sandy Lean Clay (CL) with Gravel
500
Final Moisture 21.9%
% Swell @ 500 psf 3.2%
Swell Pressure (psf)4,500
-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)120.3
SWELL/CONSOLIDATION TEST SUMMARY
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
Initial Moisture 9.4%
Sample ID: B-4 @ 2
Sample Description: Possible Existing Fill; Brown Sandy Lean Clay (CL), minor Gravel
500
Final Moisture 13.7%
% Swell @ 500 psf 5.5%
Swell Pressure (psf)10,400
-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)100.3
SWELL/CONSOLIDATION TEST SUMMARY
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
Initial Moisture 15.6%
Sample ID: B-4 @ 4
Sample Description: Brown/Rust Lean Clay with Sand (CL), minor Gravel
500
Final Moisture 19.6%
% 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)120.1
SWELL/CONSOLIDATION TEST SUMMARY
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
Initial Moisture 11.3%
Sample ID: B-5 @ 2
Sample Description: Possible Existing Fill; Brown/Rust Sandy Lean Clay (CL), minor Gravel
500
Final Moisture 14.4%
% Swell @ 500 psf 2.4%
Swell Pressure (psf)4,700
-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)118.0
SWELL/CONSOLIDATION TEST SUMMARY
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
Initial Moisture 10.4%
Sample ID: B-7 @ 4
Sample Description: Brown/Beige Lean Clay with Sand (CL), minor Gravel
500
Final Moisture 13.3%
% Swell @ 500 psf 1.3%
Swell Pressure (psf)2,900
-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)118.6
SWELL/CONSOLIDATION TEST SUMMARY
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
Initial Moisture 9.4%
Sample ID: B-8 @ 2
Sample Description: Possible Existing Fill; Brown/Beige Sandy Lean Clay (CL), minor Gravel
500
Final Moisture 14.6%
% Swell @ 500 psf 3.2%
Swell Pressure (psf)5,500
-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)120.7
SWELL/CONSOLIDATION TEST SUMMARY
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
Initial Moisture 10.2%
Sample ID: B-8 @ 4
Sample Description: Brown Sandy Lean Clay (CL), trace Gravel
500
Final Moisture 13.9%
% Swell @ 500 psf 3.6%
Swell Pressure (psf)6,800
-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)122.9
SWELL/CONSOLIDATION TEST SUMMARY
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
Initial Moisture 10.3%
Sample ID: B-9 @ 2
Sample Description: Possible Existing Fill; Dark Brown/Brown Sandy Lean Clay (CL), minor Gravel
500
Final Moisture 13.2%
% Swell @ 500 psf 4.8%
Swell Pressure (psf)10,600
-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)122.5
SWELL/CONSOLIDATION TEST SUMMARY
PROPOSED BASKETBALL GYM - LOT 5, PROSPECT PARK EAST, P.U.D.
1601 SHARP POINT DRIVE, FORT COLLINS, COLORADO
Project # 22-1426
December 2022
Initial Moisture 8.8%
Sample ID: B-9 @ 4
Sample Description: Brown Lean Clay with Sand (CL), trace Gravel
500
Final Moisture 12.8%
% Swell @ 500 psf 4.5%
Swell Pressure (psf)10,200
-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
Cu ! 4 and 1 " Cc " 3E GW Well graded gravelF Clean Gravels
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
Cu ! 6 and 1 " Cc " 3E SW Well graded sandI Clean Sands
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
PI > 7 and plots on or above “A” lineJ CL Lean clayK,L,M Silts and Clays
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
Liquid limit - oven dried Organic clayK,L,M,P Organic
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 =
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.
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+