HomeMy WebLinkAboutPOUDRE VALLEY PLAZA MIXED-USE - FDP220001 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTGEOTECHNICAL SUBSURFACE EXPLORATION REPORT
LOT 7 POUDRE VALLEY PLAZA – 4-STORY APARTMENT BUILDING
SOUTHEAST CORNER OF HORSETOOTH ROAD AND SHIELDS STREET
FORT COLLINS, COLORADO
EEC PROJECT NO. 1202075
Prepared for:
Schuman Companies, Inc.
4630 Royal Vista Circle Suite 13
Windsor, Colorado 80550
Attn: Mr. Mark Morrison (markm@schumanco.com)
Prepared by:
Earth Engineering Consultants, LLC
4396 Greenfield Drive
Windsor, Colorado 80550
4396 GREENFIELD DRIVE
W INDSOR, COLORADO 80550
(970) 545-3908 FAX (970) 663-0282
November 3, 2020
Schuman Companies, Inc.
4630 Royal Vista Circle Suite 13
Windsor, Colorado 80550
Attn: Mr. Mark Morrison (markm@schumanco.com)
Re: Geotechnical Subsurface Exploration Report
Lot 7 Poudre Valley Plaza – 4-Story Apartment Building
Southeast Corner of Horsetooth Road and Shields Street
Fort Collins, Colorado
EEC Project No. 1202075
Mr. Morrison:
Enclosed, herewith, are the results of the subsurface exploration completed by Earth Engineering
Consultants, LLC (EEC) for the referenced project. For this exploration, three (3) soil borings
were extended to depths of approximately 20 to 35 feet below existing site grades. This
subsurface exploration was carried out in general accordance with our proposal dated October 1,
2020.
In summary, the subsurface conditions encountered beneath the surficial sparse vegetation layer
in the test borings, generally consisted of soils classified as clayey sand/sandy lean clay
extending to the underlying bedrock at depths of approximately 14 to 17 feet below the ground
surface. The clayey sand/sandy lean clay was generally dry to moist nearing the groundwater
table, very stiff, and exhibited moderate to high swell potential at current moisture and density
conditions. Claystone/siltstone/sandstone bedrock was encountered below the clayey sand/sandy
lean clay soils in a majority of the borings and extended to the depths explored, approximately
20 to 35 feet below the ground surface. The bedrock was generally moist in situ, highly
weathered to moderately hard/poorly cemented and exhibited low swell potential at current
moisture and density conditions. Groundwater was encountered at depths of approximately 14½
to 15 feet below the ground surface in borings B-1 and B-2. Groundwater was not encountered in
boring B-3 which extended to a maximum depth of approximately 20 feet below the ground
surface.
GEOTECHNICAL SUBSURFACE EXPLORATION REPORT
LOT 7 POUDRE VALLEY PLAZA – 4-STORY APARTMENT BUILDING
SOUTHEAST CORNER OF HORSETOOTH ROAD AND SHIELDS STREET
FORT COLLINS, COLORADO
EEC PROJECT NO. 1202075
November 3, 2020
INTRODUCTION
The geotechnical subsurface exploration for the proposed 4-story apartment building planned for
construction on Lot 7 within the Poudre Valley Plaza development in Fort Collins, Colorado has
been completed. To develop subsurface information for the proposed in-fill development lot, three
(3) soil borings were drilled within the proposed building footprint to depths of approximately 20 to
35 feet below existing site grades. A site diagram indicating the approximate boring locations is
included with this report.
We understand the proposed development will consist of a 4-story slab-on-grade (no basement)
apartment building. We anticipate maximum foundations loads will be relatively light to moderate
with maximum wall and column loads less than 4 klf and 150 kips, respectively. If the actual loads
vary significantly from the assumed loads, or if below grade construction is planned, we should be
consulted to verify our recommendations are consistent for the actual loads and construction depths.
Floor loads are expected to be light to moderate. Small grade changes are expected to develop site
grades for the proposed improvements. Overall, cuts and fills are anticipated to be less than 3 feet
(+/-) to develop finish site grades.
The purpose of this report is to describe the subsurface conditions encountered in the test borings,
analyze, and evaluate the field and laboratory test data and provide geotechnical recommendations
concerning design and construction of foundations and floor slabs and support of flatwork.
EXPLORATION AND TESTING PROCEDURES
The test boring locations were selected and established in the field by EEC personnel by pacing and
estimating angles from identifiable site features. Ground surface elevations at each boring location
were estimated based on “Google Earth” and are presented on the boring logs. The approximate
locations of the borings are shown on the attached boring location diagram and “Google Earth”
image. The boring locations and estimate ground surface elevations should be considered accurate
only to the degree implied by the methods used to make the field measurements.
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The test borings were advanced using a truck mounted CME-55 drill rig equipped with a hydraulic
head employed in drilling and sampling operations. The boreholes were advanced using 4-inch
nominal diameter continuous flight augers. Samples of the subsurface materials encountered were
obtained using split-barrel and California barrel sampling procedures in general accordance with
ASTM Specifications D1586 and D3550, respectively.
In the split-barrel and California barrel sampling procedures, standard sampling spoons are advanced
into the ground by means of a 140-pound hammer falling a distance of 30 inches. The number of
blows required to advance the split-barrel and California barrel samplers is recorded and is used to
estimate the in-situ relative density of cohesionless soils and, to a lesser degree of accuracy, the
consistency of cohesive soils. In the California barrel sampling procedure, relatively intact samples
are obtained in removable brass liners. All samples obtained in the field were sealed and returned to
our laboratory for further examination, classification, and testing.
Laboratory moisture content tests were completed on each of the recovered samples with unconfined
compressive strength of appropriate samples estimated using a calibrated hand penetrometer.
Atterberg limits and washed sieve analysis tests were completed on select samples to evaluate the
quantity and plasticity of fines in the subgrades. Swell/consolidation testing was completed on select
samples to evaluate the potential for the subgrade materials to change volume with variation in
moisture content and load. Soluble sulfate tests were completed on selected samples to estimate the
potential for sulfate attack on site cast concrete. Results of the outlined tests are indicated on the
attached boring logs and summary sheets.
As part of the testing program, all samples were examined in the laboratory and classified in general
accordance with the attached General Notes and the Unified Soil Classification System, based on the
soil’s texture and plasticity. The estimated group symbol for the Unified Soil Classification System
is indicated on the boring logs and a brief description of that classification system is included with
this report.
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SITE AND SUBSURFACE CONDITIONS
The proposed 4-story apartment building is planned for construction on Lot 7 within the Poudre
Valley Plaza, situated at the southeast corner of Horsetooth Road and Shields Street in Fort Collins,
Colorado. Sparse vegetation was encountered at the surface of the borings. Ground surface in this
area is relatively flat with approximately 2 feet ± of relief from west to east, based on our cursory
review of the site on Google Earth.
EEC field personnel were on site during drilling to evaluate the subsurface conditions encountered
and direct the drilling activities. Field logs prepared by EEC site personnel were based on visual and
tactual observation of disturbed samples and auger cuttings. The final boring logs included with this
report may contain modifications to the field logs based on results of laboratory testing and
evaluation. Based on results of the field borings and laboratory testing, subsurface conditions can be
generalized as follows.
From the ground surface, the subgrades underlying the vegetation layer consisted of soils classified
as clayey sand/sandy lean clay extending to the underlying bedrock at depths of approximately 14 to
17 feet below the ground surface. The clayey sand/sandy lean clay was generally dry to moist
nearing the groundwater table, very stiff, and exhibited moderate to high swell potential at current
moisture and density conditions. Claystone/siltstone/sandstone bedrock was encountered below the
clayey sand/sandy lean clay soils in a majority of the borings and extended to the depths explored,
approximately 20 to 35 feet below the ground surface. The bedrock was generally moist in situ,
highly weathered to moderately hard/poorly cemented and exhibited low swell potential at current
moisture and density conditions.
The stratification boundaries indicated on the boring logs represent the approximate location of
changes in soil types; in-situ, the transition of materials may be gradual and indistinct.
GROUNDWATER CONDITIONS
Observations were made while drilling and after completion of the borings to detect the presence and
depth to hydrostatic groundwater. At the time of drilling, groundwater was encountered at depths of
approximately 14½ to 15 feet below the ground surface in borings B-1 and B-2. Groundwater was
not encountered in boring B-3 which extended to a maximum depth of approximately 20 feet below
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the ground surface. The borings were backfilled upon completion of the drilling operations;
therefore, subsequent groundwater measurements were not performed.
Fluctuations in groundwater levels can occur over time depending on variations in hydrologic
conditions and other conditions not apparent at the time of this report. Longer term monitoring of
water levels in cased wells, which are sealed from the influence of surface water, would be required
to evaluate fluctuations more accurately in groundwater levels at the site. We have typically noted
deepest groundwater levels in late winter and shallowest groundwater levels in mid to late summer.
ANALYSIS AND RECOMMENDATIONS
Swell – Consolidation Test Results
The swell-consolidation test is performed to evaluate the swell or collapse potential of soils to assist in
determining foundation and floor slab design criteria. In this test, relatively undisturbed samples
obtained directly from the California sampler are placed in a laboratory apparatus and inundated with
water under a predetermined load. The swell-index is the resulting amount of swell or collapse after
the inundation period expressed as a percent of the sample’s preload/initial thickness. After the
inundation period, additional incremental loads are applied to evaluate the swell pressure and/or
consolidation.
For this assessment, we conducted eight (8) swell-consolidation tests on relatively undisturbed soil
samples obtained at various intervals/depths on the site. The swell index values for the in-situ soil
samples analyzed revealed low to moderate swell characteristics as indicated on the attached swell
test summaries. The (+) test results indicate the soil materials swell potential characteristics while
the (-) test results indicate the soils materials collapse/consolidation potential characteristics when
inundated with water. The following table summarizes the swell-consolidation laboratory test results
for samples obtained during our field explorations for the subject site.
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Table I – Laboratory Swell-Consolidation Test Results
No of
Samples
Tested
Pre-Load /
Inundation
Pressure,
PSF
Description of Material
In-Situ Characteristics Range of Swell – Index
Test Results Range of Moisture
Contents, %
Range of Dry Densities,
PCF
Low
End, %
High
End, %
Low End,
PCF
High End,
PCF
Low End
(+/-) %
High
End, (+/-)
%
1 150 Sandy Lean Clay (CL) 6.3 102.5 (+) 3.5
2 500 Clayey Sand/Sandy Lean Clay
(SC/CL) 9.4 9.5 118.4 124.3 (+) 3.6 (+) 5.2
3 1000 Sandy Lean Clay (CL) or
Claystone/Siltstone/Sandstone 10.7 15.9 103.3 128.3 (-) 0.1 (+) 4.0
Colorado Association of Geotechnical Engineers (CAGE) uses the following information to provide
uniformity in terminology between geotechnical engineers to provide a relative correlation of slab
performance risk to measured swell. “The representative percent swell values are not necessarily
measured values; rather, they are a judgment of the swell of the soil and/or bedrock profile likely to
influence slab performance.” Geotechnical engineers use this information to also evaluate the swell
potential risks for foundation performance based on the risk categories.
Table II - Recommended Representative Swell Potential Descriptions and Corresponding
Slab Performance Risk Categories
Slab Performance Risk Category Representative Percent Swell
(500 psf Surcharge)
Representative Percent Swell
(1000 psf Surcharge)
Low 0 to < 3 0 < 2
Moderate 3 to < 5 2 to < 4
High 5 to < 8 4 to < 6
Very High > 8 > 6
Based on the laboratory test results, the swell samples analyzed for this project at current moisture
contents and dry density conditioned were within the low to high range. The upper cohesive soils were
generally dry, very stiff/dense in-situ, and exhibited moderate to high swell potential characteristics;
thus, a possible over-excavation and replacement concept could be considered provided the ownership
group is willing to accept the risk of movement.
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General Considerations
The overburden soils on these lots include approximately 14 to 17 feet of lean clay with varying
amounts of sand soils transitioning to more granular soils. Moderate to high swell potential was
exhibited by the overburden soil samples, in our opinion this is likely due to the dry and stiff to very
stiff conditions of the lean clay soils. In general, clay soils tend to swell when inundated with water
when in-situ moisture contents are less than -2% dry of optimum moisture content. Typical optimum
moisture contents for clay soils range from approximately 15 to 20%. The moisture contents
observed in the borings were approximately 6 to 2% less than that range. Additionally, the soils
appeared to be very stiff/dense, When moisture conditioned and re-compacted to near optimum
moisture and density conditions, the swell potential of clay soils can be significantly reduced as
shown by the lower swell potential exhibited by the near surface sample in boring B-3. The site
preparation section of this report includes recommendations for an over excavation moisture
treatment, and re-compaction procedure to reduce the risk of movement for the soils underlying the
proposed site improvements. Although these methods reduce the overall risk of potential movement,
that risk cannot be completely eliminated.
The overburden clayey sand/sandy lean clay soils generally exhibited low to high potential when
inundated with water. To mitigate for potential movement, we recommend either the use of a drilled
pier foundation system with a structural floor slab and/or an extensive over excavation and
replacement procedure for the use of a conventional slab-on-grade supported on a zone of
engineered fill material as described herein. The purpose of these procedures is to reduce the
potential for post-construction movement. It should be noted however, that the risk of potential
movement cannot be completely eliminated, and the ownership group accepts that risk.
Site Preparation
Prior to placement of any fill and/or improvements, we recommend any existing topsoil, vegetation,
and undocumented fill, and any unsuitable materials be removed from the planned development
areas. Depending on the chosen foundation system, an over excavation procedure for the entire
building footprint, below floor slabs should be completed to at least the minimum depths specified in
the section titled Floor Slabs and Exterior Flatwork. Potholing and/or other observations should be
completed prior to construction, to determine the depth to bedrock throughout the proposed building
footprint. Due to the very high swell potential encountered in the near surface clay soils,
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consideration should be given to using drilled pier foundations and a structural floor system. Drilled
piers are also recommended to minimize the impact to the surrounding pavement areas. If a 5-8 foot
over excavation and replacement procedure were utilized to allow for spread footing foundations, the
over excavation would extend well into the existing paved/developed areas adjacent to the infill lot.
The use of drilled pier foundations would minimize the extensive limit beyond the building footprint.
If elected as an alternative approach to a structural floor slab, and assuming a greater potential risk
for movement, consideration could be given to over-excavating the site subsoils a minimum of 8 feet
below existing ground surface or final floor slab elevation, whichever provides the greater overall
depth, within the entire building footprint. Over excavations should be extended laterally beyond the
edge of floor slabs, a minimum of 8-inches for every 12-inches of depth. Over excavations below the
proposed floor slab could be confined to extending less than 5 feet laterally beyond the building
footprint, to prevent them from extending into the adjacent pavement areas.
After removal of all topsoil, vegetation, and removal of unacceptable or unsuitable subsoils, any
overexcavation, and prior to placement of fill, the exposed soils should be scarified to a depth of 9
inches, adjusted in moisture content to within ±2% of standard Proctor optimum moisture content
and compacted to at least 95% of the material's standard Proctor maximum dry density as
determined in accordance with ASTM Specification D698.
Fill materials to develop the subgrades should consist of approved, low-volume-change materials,
which are free from organic matter and debris. It is our opinion, either granular structural fill or on-
site moisture conditioned overburden soils could be used as fill in these areas, provided adequate
moisture treatment and compaction procedures are followed. Bedrock should not be reused as
engineered fill material. It should be noted that if the site lean clay soils are used as fill materials in
lieu of a granular structural fill material, greater potential for movement should be expected. The
imported granular materials should be graded similarly to a CDOT Class 5, 6 or 7 aggregate base.
Fill materials should be placed in loose lifts not to exceed 9 inches thick, adjusted in moisture
content to within ±2% of standard Proctor optimum moisture content and compacted to at least 95%
of the material's standard Proctor maximum dry density as determined in accordance with ASTM
Specification D698. If the site lean clay soils are used as fill material, care will be needed to
maintain the recommended moisture content prior to and during construction of overlying
improvements.
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Care should be exercised after preparation of the subgrades to avoid disturbing the subgrade
materials. Materials which are loosened or disturbed should be reworked prior to placement of
foundations/flatwork.
Foundation Systems – General Considerations
The site appears suitable for the proposed construction based on the results of our field exploration and
our understanding of the proposed development plans. The following foundation system was evaluated
for use on the site for the proposed building.
Straight shaft drilled piers bearing into the underlying bedrock formation with either a
structural floor slab or a minimum 8 feet of engineered/controlled fill materials placed and
compacted below the floor slab
Other alternative foundation systems could be considered, and we would be pleased to provide
additional alternatives upon request.
Drilled Piers/Caissons Foundations
Due to the necessity to over-excavate, ground modify the existing moderately to highly expansive
cohesive overburden soils, and reduce the over-excavation impact to the surrounding areas,
consideration should be given to supporting the proposed building on a grade beam and straight shaft
drilled pier/caisson foundation system extending into the underlying bedrock formation.
For axial compression loads, the drilled piers could be designed using a maximum end bearing
pressure of 30,000 pounds per square foot (psf), along with a skin-friction of 3,000 psf for the portion
of the pier extended into the underlying firm and/or harder bedrock formation. The piers require
sufficient dead-load and/or additional penetration into the bearing strata to resist the potential uplift of
the expansive materials. All piers should be design for a minimum dead-load pressure of 5,000 psf,
based upon pier end area. Straight shaft piers should be drilled a minimum of 15 feet into competent or
harder bedrock with minimum pier length of at least 25 feet. Due to the weathered condition of the
upper strata of bedrock, the top 3 feet should be neglected for final penetration depth. Lower values
may be appropriate for pier “groupings” depending on the pier diameters and spacing. Pile groups
should be evaluated individually.
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Required pier penetration should be balanced against potential uplift forces due to expansion of the
subsoils and bedrock on the site. For design purposes, the uplift force on each pier can be determined
on the basis of the following equation:
Up = 20 x D
Where: Up = the uplift force in kips, and
D = the pier diameter in feet
Uplift forces on piers should be resisted by a combination of dead-load and pier penetration below a
depth of about 20 feet and into the bearing strata.
To satisfy forces in the horizontal direction, piers may be designed for lateral loads using a coefficient
of subgrade reaction for varying pier diameters is as follows:
Table III – Lateral Load Coefficient of Subgrade Reaction
Pier Diameter (inches) Coefficient of Subgrade Reaction (tons/ft3)
Site Soils Bedrock
12 50 400
18 33 267
24 25 200
30 20 160
36 17 133
When the lateral capacity of drilled piers is evaluated by the L-Pile computer program, we recommend
that internally generated load-deformation (P-Y) curves be used. The following parameters may be
used for the design of laterally loaded piers, using the L-Pile computer program:
Table IV – L-Pile Parameters
Parameters On-Site Overburden Soils Bedrock
Unit Weight of Soil (pcf) 120(1) 125(1)
Cohesion (psf) 200 5000
Angle of Internal Friction () (degrees) 25 20
Strain Corresponding to ½ Max. Principal Stress Difference 50 0.02 0.015
*Notes: 1) Reduce by 62.4 pcf below the water table
All piers should be reinforced full depth for the applied axial, lateral and uplift stresses imposed. The
amount of reinforcing steel for expansion should be determined by the tensile force created by the
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uplift force on each pier, with allowance for dead load. Minimum reinforcement of at least one percent
of the cross-sectional area of each pier should be specified.
To reduce potential uplift forces on piers, use of long grade beam spans to increase individual pier
loading, and small diameter piers are recommended. For this project, use of a minimum pier diameter
of 18 inches is recommended. A minimum 6-inch void space should be provided beneath grade beams
between piers. The void material should be of suitable strength to support the weight of fresh concrete
used in grade beam construction and to avoid collapse when foundation backfill is placed.
Drilling caissons to design depth should be possible with conventional heavy-duty single flight power
augers equipped with rock teeth on the majority of the site. However, areas of well-cemented bedrock
may be encountered throughout the site at various depths where specialized drilling equipment and/or
rock excavating equipment may be required. Consideration should be given to obtaining a unit price
for difficult caisson excavation in the contract documents for the project.
To provide increased resistance to potential uplift forces, the sides of each pier should be mechanically
roughened in the bearing strata. This should be accomplished by a roughening tooth placed on the
auger. Pier bearing surfaces must be cleaned prior to concrete placement. A representative of the
geotechnical engineer should inspect the bearing surface and pier configuration.
Depending on the depth of groundwater encountered at the time of construction temporary casing
may be required to maintain open boreholes. Concrete should be placed as soon as practical after
drilling each shaft to reduce the potential for sloughing of sidewalls. Groundwater encountered
should be removed from each pier hole prior to concrete placement. Pier concrete should be placed
immediately after completion of drilling and cleaning.
If a casing is used for pier construction, it should be withdrawn in a slow continuous manner
maintaining a sufficient head of concrete to prevent infiltration of water or the creation of voids in pier
concrete. Pier concrete should have relatively high fluidity when placed in cased pier holes or through
a tremie. Pier concrete with slump in the range of 6 to 8 inches is recommended.
Free-fall concrete placement in piers will only be acceptable if provisions are taken to avoid striking
the concrete on the sides of the hole or reinforcing steel. The use of a bottom-dump hopper/tremie
pipe or an elephant's trunk discharging near the bottom of the hole where concrete segregation will be
minimized, is recommended.
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A maximum 6-inch depth of groundwater is acceptable in each pier prior to concrete placement. If
pier concrete cannot be placed in dry conditions, a tremie should be used for concrete placement. Due
to potential sloughing and raveling, foundation concrete quantities may exceed calculated geometric
volumes.
Foundation excavations should be observed by the geotechnical engineer. A representative of the
geotechnical engineer should inspect the bearing surface and pier configuration. If the soil conditions
encountered differ from those presented in this report, supplemental recommendations may be
required. We estimate the long-term settlement of drilled pier foundations designed and constructed as
outlined above would be less than 1-inch.
Floor Slabs and Exterior Flatwork
The variability of the existing soils at approximate slab subgrade elevation could result in differential
movement of floor slab-on-grade should the underlying expansive subsoils become elevated in
moisture content. Differential slab movement/heave on the order of 4 to 6 inches or more is
possible. Use of a structural floor system structurally supported independent of the subgrade soils, is
a positive means of eliminating the potentially detrimental effects of floor slab movement.
Subgrades for floor slabs and exterior flatwork should be prepared as outlined in the section Site
Preparation. If a conventional slab-on-grade is used, an over excavation extending a minimum of 8
feet below the bottom of the floor slab is recommended. A structural floor slab should strongly be
considered; however, if the ownership group is willing to assume a greater potential risk of slab
movement, an over excavation and replacement concept extending a minimum 8 feet below the floor
slab could be considered. A common practice to reduce potential slab heave involves overexcavation
of the expansive soils and replacing these materials with either moisture conditioned engineered fill
of with non-expansive imported structural fill material. This alternative over-excavation and
replacement concept will not eliminate the possibility of slab heave; but movements should be
reduced and tend to be more uniform. Constructing improvements (i.e. buildings, flatwork,
pavements, floor slabs, etc.) on a site which exhibits potential for swelling is inherently at high risk for
post construction heaving, causing distress of site improvements. The following recommendations
provided herein are to reduce the risk of post construction heaving; however, that risk cannot be
eliminated. If the owner does not accept that risk, we would be pleased to provide more stringent
recommendations.
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As an alternative to a preferred structural floor system as previously recommended in this subsurface
exploration report and assuming the owners are willing to accept total and differential movements of
the floor as outlined below the use of moisture conditioned engineered fill material and/or approved
imported structural fill material could be placed and compacted in an over-excavation zone beneath
the floor slab. An underslab gravel layer or thin leveling course could be used underneath the
concrete floor slabs to provide a capillary break mechanism, a load distribution layer, and as a
leveling course for the concrete placement.
Failure to limit the intrusion of water from any source, (i.e., surface water infiltration, seepage from
detention ponds and/or adjacent utility trenches bedding zone, run-off, etc.); into the expansive
subgrades materials could results in movement greater than those outlined below.
The following table provides estimates for the total and differential amounts of movement which
could be expected for a range of overexcavation depths, replaced with either non-expansive imported
structural/granular fill material or moisture conditioned on-site cohesive materials, should the
underlying subsoils or the bedrock formation below the over-excavated zone become elevated in
moisture content to a reasonable depth.
Table V - Calculated Heave Potential
Depth of Removal of Expansive Soil
and Replacement with Low to Non
Expansive Fill Materials (ft)
Calculated Heave Potential, Inches
Imported Structural/Granular
Fill Material
Reuse of on-site moisture conditioned
Subsoils
0 > 5+ > 5+
4 < 3-1/2 < 4
6 < 2 < 3
8 < 3/4 < 1-1/2
It should be noted that the heave potential is the heave that could occur if subsurface moisture
increases sufficiently subsequent to construction. When subsurface moisture does not increase, or
increases only nominally, the full heave potential may not be realized. For this reason, and assuming
some surface water run-off will be controlled with grading contours, drainage swales, etc., we
provided surface slope and drainage recommendations in our report to reduce the potential for
surface water infiltration. With appropriate surface features to limit the amount infiltration, we
would not expect the full amount of potential heave to occur.
In general, we believe the on-site cohesive subsoils and/or an approved imported, essentially
granular structural fill material with a sufficient amount of fines to prevent the ponding of water
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within the fill, could be used for supporting the interior floor slab. Particular care will be needed
with the use of cohesive subgrade soils to establish and maintain sufficient moisture in the fill
material to maintain a low swell potential in the fill zone. However, as illustrated above the slabs
post-construction total and differential movement cannot be completely eliminated. The cohesive
soil materials may also be subject to strength loss and instability when wetted.
Any over excavations should be completed, and fill materials should be placed as described in the
section Site Preparation. For structural design of concrete slabs-on-grade, a modulus of subgrade
reaction of 100 pounds per cubic inch (pci) or 200 pci could be used for floors supported on
controlled/engineered fill materials or imported structural fill materials, respectively.
Additional floor slab design and construction recommendations are as follows:
Interior partition walls should be separated/floated from floor slabs to allow for
independent movement.
Positive separations and/or isolation joints should be provided between slabs and all
foundations, columns, and utility lines to allow for independent movement.
Control joints should be provided in slabs to control the location and extent of
cracking.
Interior trench backfill placed beneath slabs should be compacted in a similar manner
as previously described for imported structural fill material.
Floor slabs should not be constructed on frozen subgrade.
Other design and construction considerations as outlined in the ACI Design Manual
should be followed.
For interior floor slabs, depending on the type of floor covering and adhesive used, those material
manufacturers may require that specific subgrade, capillary break, and/or vapor barrier requirements
be met. The project architect and/or material manufacturers should be consulted with for specific
under slab requirements.
We estimate the long-term movement of conventional floor slabs-on-grade designed and constructed
as outlined above would be about 1 inch. It should be noted that if the lean clay soils are used as
compacted fill materials below floor slabs, greater potential for movement could be expected.
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Care should be exercised after development of the floor slab and exterior flatwork subgrades to
prevent disturbance of the in-place materials. Subgrade soils which are loosened or disturbed by
construction activities or soils which become wet and softened or dry and desiccated should be
removed and replaced or reworked in place prior to placement of the overlying slabs.
Lateral Earth Pressures
Portions of the new structure or site improvements which are constructed below grade may be
subject to lateral earth pressures. Passive lateral earth pressures may help resist the driving forces
for retaining wall or other similar site structures. Active lateral earth pressures could be used for
design of structures where some movement of the structure is anticipated, such as retaining walls.
The total deflection of structures for design with active earth pressure is estimated to be on the order
of one half of one percent of the height of the down slope side of the structure. We recommend at-
rest pressures be used for design of structures where rotation of the walls is restrained, such as below
grade walls for a building. Passive pressures and friction between the footing and bearing soils
could be used for design of resistance to movement of retaining walls.
Coefficient values for backfill with anticipated types of soils for calculation of active, at-rest and
passive earth pressures are provided in Table V below. Equivalent fluid pressure is equal to the
coefficient times the appropriate soil unit weight. Those coefficient values are based on horizontal
backfill with backfill soils consisting of on-site essentially cohesive subsoils. For at-rest and active
earth pressures, slopes down and away from the structure would result in reduced driving forces with
slopes up and away from the structures resulting in greater forces on the walls. The passive
resistance would be reduced with slopes away from the wall. The top 30 inches of soil on the
passive resistance side of walls could be used as a surcharge load; however, should not be used as a
part of the passive resistance value. Frictional resistance is equal to the tangent of the friction angle
times the normal force. Surcharge loads or point loads placed in the backfill can also create
additional loads on below grade walls. Those situations should be designed on an individual basis.
Earth Engineering Consultants, LLC
EEC Project No. 1202075
November 3, 2020
Page 15
Table V - Lateral Earth Pressures
Soil Type On-Site Overburden Lean Clay Soils Imported Medium Dense Granular
Material
Wet Unit Weight (psf) 105 135
Saturated Unit Weight (psf) 115 140
Friction Angle () – (assumed) 20° 35°
Active Pressure Coefficient 0.49 0.27
At-rest Pressure Coefficient 0.66 0.43
Passive Pressure Coefficient 2.04 3.70
Coefficient of Friction at Base 0.20 0.35
The outlined values do not include factors of safety nor allowances for hydrostatic loads and are
based on assumed friction angles, which should be verified after potential material sources have been
identified. Care should be taken to develop appropriate drainage systems behind below grade walls
to eliminate potential for hydrostatic loads developing on the walls. Those systems would likely
include perimeter drain systems extending to sump areas or free outfall where reverse flow cannot
occur into the system. Where necessary, appropriate hydrostatic load values should be used for
design.
To reduce hydrostatic loading on retaining walls, a subsurface drain system should be placed behind
the wall. The drain system should consist of free-draining granular soils containing less than five
percent fines (by weight) passing a No. 200 sieve placed adjacent to the wall. The free-draining
granular material should be graded to prevent the intrusion of fines or encapsulated in a suitable
filter fabric. A drainage system consisting of either weep holes or perforated drain lines (placed near
the base of the wall) should be used to intercept and discharge water which would tend to saturate
the backfill. Where used, drain lines should be embedded in a uniformly graded filter material and
provided with adequate clean-outs for periodic maintenance. An impervious soil should be used in
the upper layer of backfill to reduce the potential for water infiltration. As an alternative, a
prefabricated drainage structure, such as geo-composite product, may be used as a substitute for the
granular backfill adjacent to the wall.
Earth Engineering Consultants, LLC
EEC Project No. 1202075
November 3, 2020
Page 16
Seismic
The site soil conditions generally consist of clayey sand /sandy lean clay which extended to the
underlying bedrock at depths of 14 to 17 feet. For those site conditions, the International Building
Code indicates a Seismic Site Classification of C. Drilling to a greater depth could reveal a different
site classification.
Water Soluble Sulfates (SO4)
The water-soluble sulfate (SO4) content of the on-site overburden subsoils and underlying bedrock
taken during our subsurface exploration at random locations and intervals are provided below. Based
on reported sulfate content test results, the Class/severity of sulfate exposure for concrete in contact
with the on-site subsoils and bedrock is provided in this report.
Table VII - Water Soluble Sulfate Test Results
Sample Location Description Soluble Sulfate Content (%)
B-2, S-2, at 4’ Sandy Lean Clay (CL) 0.03
B-3, S-3 at 14’ Claystone / Siltstone / Sandstone 0.02
Based on the results of completed soluble sulfate tests of the overburden soils and bedrock
formation, ACI 318, Section 4.2 indicates a low risk of sulfate attack on Portland cement concrete,
therefore, ACI Class S0 requirements should be followed for concrete placed in the overburden soils
and underlying bedrock. Foundation concrete should be designed in accordance with the provisions
of the ACI Design Manual, Section 318, Chapter 4.
Other Considerations
Positive drainage should be developed away from the structures and exterior flatwork areas with a
minimum slope of 1 inch per foot for the first 10 feet away from the improvements in landscape
areas. Care should be taken in planning of landscaping (if required) adjacent to the buildings to
avoid features which would pond water adjacent to the foundations or stemwalls. Placement of
plants which require irrigation systems or could result in fluctuations of the moisture content of the
subgrade material should be avoided adjacent to site improvements. Irrigation systems should not be
Earth Engineering Consultants, LLC
EEC Project No. 1202075
November 3, 2020
Page 17
placed within 5 feet of the perimeter of the buildings and parking areas. Spray heads should be
designed not to spray water on or immediately adjacent to the structures or site flatwork. Roof
drains should be designed to discharge at least 5 feet away from the structures and away from the
flatwork areas.
Excavations into the on-site clayey sand/sandy lean clay soils and underlying bedrock can be
expected to stand on relatively steep, temporary slopes during construction. The individual
contractor(s) should be made responsible for designing and constructing stable, temporary
excavations as required to maintain stability of both the excavation sides and bottom. All
excavations should be sloped or shored in the interest of safety following local and federal
regulations, including current OSHA excavation and trench safety standards.
GENERAL COMMENTS
The analysis and recommendations presented in this report are based upon the data obtained from the
soil borings performed at the indicated locations and from any other information discussed in this
report. This report does not reflect any variations, which may occur between borings or across the
site. The nature and extent of such variations may not become evident until construction. If
variations appear evident, it will be necessary to re-evaluate the recommendations of this report.
It is recommended that the geotechnical engineer be retained to review the plans and specifications,
so comments can be made regarding the interpretation and implementation of our geotechnical
recommendations in the design and specifications. It is further recommended that the geotechnical
engineer be retained for testing and observations during earthwork phases to help determine that the
design requirements are fulfilled.
This report has been prepared for the exclusive use of Schuman Companies for specific application
to the project discussed and has been prepared in accordance with generally accepted geotechnical
engineering practices. No warranty, express or implied, is made. In the event that any changes in
the nature, design, or location of the project as outlined in this report are planned, the conclusions
and recommendations contained in this report shall not be considered valid unless the changes are
reviewed, and the conclusions of this report are modified or verified in writing by the geotechnical
engineer.
Earth Engineering Consultants, LLC
DRILLING AND EXPLORATION
DRILLING & SAMPLING SYMBOLS:
SS: Split Spoon ‐ 13/8" I.D., 2" O.D., unless otherwise noted PS: Piston Sample
ST: Thin‐Walled Tube ‐ 2" O.D., unless otherwise noted WS: Wash Sample
R: Ring Barrel Sampler ‐ 2.42" I.D., 3" O.D. unless otherwise noted
PA: Power Auger FT: Fish Tail Bit
HA: Hand Auger RB: Rock Bit
DB: Diamond Bit = 4", N, B BS: Bulk Sample
AS: Auger Sample PM: Pressure Meter
HS: Hollow Stem Auger WB: Wash Bore
Standard "N" Penetration: Blows per foot of a 140 pound hammer falling 30 inches on a 2‐inch O.D. split spoon, except where noted.
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 Casting Removal
Water levels indicated on the boring logs are the levels measured in the borings at the time indicated. In pervious soils, the indicated
levels may reflect the location of ground water. In low permeability soils, the accurate determination of ground water levels is not
possible with only short term observations.
DESCRIPTIVE SOIL CLASSIFICATION
Soil Classification is based on the Unified Soil Classification
system and the ASTM Designations D‐2488. Coarse Grained
Soils have move than 50% of their dry weight retained on a
#200 sieve; they are described as: boulders, cobbles, gravel or
sand. Fine Grained Soils have less than 50% of their dry weight
retained on a #200 sieve; they are 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 relative in‐
place density and fine grained soils on the basis of their
consistency. Example: Lean clay with sand, trace gravel, stiff
(CL); silty sand, trace gravel, medium dense (SM).
CONSISTENCY OF FINE‐GRAINED SOILS
Unconfined Compressive
Strength, Qu, psf Consistency
< 500 Very Soft
500 ‐ 1,000 Soft
1,001 ‐ 2,000 Medium
2,001 ‐ 4,000 Stiff
4,001 ‐ 8,000 Very Stiff
8,001 ‐ 16,000 Very Hard
RELATIVE DENSITY OF COARSE‐GRAINED SOILS:
N‐Blows/ft Relative Density
0‐3 Very Loose
4‐9 Loose
10‐29 Medium Dense
30‐49 Dense
50‐80 Very Dense
80 + Extremely Dense
PHYSICAL PROPERTIES OF BEDROCK
DEGREE OF WEATHERING:
Slight Slight decomposition of parent material on
joints. May be color change.
Moderate Some decomposition and color change
throughout.
High Rock highly decomposed, may be extremely
broken.
HARDNESS AND DEGREE OF CEMENTATION:
Limestone and Dolomite:
Hard Difficult to scratch with knife.
Moderately Can be scratched easily with knife.
Hard Cannot be scratched with fingernail.
Soft Can be scratched with fingernail.
Shale, Siltstone and Claystone:
Hard Can be scratched easily with knife, cannot be
scratched with fingernail.
Moderately Can be scratched with fingernail.
Hard
Soft Can be easily dented but not molded with
fingers.
Sandstone and Conglomerate:
Well Capable of scratching a knife blade.
Cemented
Cemented Can be scratched with knife.
Poorly Can be broken apart easily with fingers.
Cemented
Group
Symbol
Group Name
Cu≥4 and 1<Cc≤3E GW Well-graded gravel F
Cu<4 and/or 1>Cc>3E GP Poorly-graded gravel F
Fines classify as ML or MH GM Silty gravel G,H
Fines Classify as CL or CH GC Clayey Gravel F,G,H
Cu≥6 and 1<Cc≤3E SW Well-graded sand I
Cu<6 and/or 1>Cc>3E SP Poorly-graded sand I
Fines classify as ML or MH SM Silty sand G,H,I
Fines classify as CL or CH SC Clayey sand G,H,I
inorganic PI>7 and plots on or above "A" Line CL Lean clay K,L,M
PI<4 or plots below "A" Line ML Silt K,L,M
organic Liquid Limit - oven dried Organic clay K,L,M,N
Liquid Limit - not dried Organic silt K,L,M,O
inorganic PI plots on or above "A" Line CH Fat clay K,L,M
PI plots below "A" Line MH Elastic Silt K,L,M
organic Liquid Limit - oven dried Organic clay K,L,M,P
Liquid Limit - not dried Organic silt K,L,M,O
Highly organic soils PT Peat
(D30)2
D10 x D60
GW-GM well graded gravel with silt NPI≥4 and plots on or above "A" line.
GW-GC well-graded gravel with clay OPI≤4 or plots below "A" line.
GP-GM poorly-graded gravel with silt PPI plots on or above "A" line.
GP-GC poorly-graded gravel with clay QPI plots below "A" line.
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
Earth Engineering Consultants, LLC
IIf soil contains >15% gravel, add "with gravel" to
group name
JIf Atterberg limits plots shaded area, soil is a CL-
ML, Silty clay
Unified Soil Classification System
Soil Classification
Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests
Sands 50% or more
coarse fraction
passes No. 4 sieve
Fine-Grained Soils
50% or more passes
the No. 200 sieve
<0.75 OL
Gravels with Fines
more than 12%
fines
Clean Sands Less
than 5% fines
Sands with Fines
more than 12%
fines
Clean Gravels Less
than 5% fines
Gravels more than
50% of coarse
fraction retained on
No. 4 sieve
Coarse - Grained Soils
more than 50%
retained on No. 200
sieve
CGravels with 5 to 12% fines required dual symbols:
Kif soil contains 15 to 29% plus No. 200, add "with sand"
or "with gravel", whichever is predominant.
<0.75 OH
Primarily organic matter, dark in color, and organic odor
ABased on the material passing the 3-in. (75-mm)
sieve
ECu=D60/D10 Cc=
HIf fines are organic, add "with organic fines" to
group name
LIf soil contains ≥ 30% plus No. 200 predominantly sand,
add "sandy" to group name.
MIf soil contains ≥30% plus No. 200 predominantly gravel,
add "gravelly" to group name.
DSands with 5 to 12% fines require dual symbols:
BIf field sample contained cobbles or boulders, or
both, add "with cobbles or boulders, or both" to
group name.FIf soil contains ≥15% sand, add "with sand" to
GIf fines classify as CL-ML, use dual symbol GC-
CM, or SC-SM.
Silts and Clays
Liquid Limit less
than 50
Silts and Clays
Liquid Limit 50 or
more
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70 80 90 100 110PLASTICITY INDEX (PI) LIQUID LIMIT (LL)
ML OR OL
MH OR OH
For Classification of fine-grained soils and
fine-grained fraction of coarse-grained
soils.
Equation of "A"-line
Horizontal at PI=4 to LL=25.5
then PI-0.73 (LL-20)
Equation of "U"-line
Vertical at LL=16 to PI-7,
then PI=0.9 (LL-8)
CL-ML
LOT 7 POUDRE VALLEY PLAZA
FORT COLLINS, COLORADO
EEC PROJECT NO. 1202075
OCTOBER 2020
Lot 7 - Poud re Valley Plaza - In -Fill Lo t for 4-Story Apartment Build i ng
Approxim ate locations for three (3) tes t borings with building footprint
300 ft
N➤➤N
B-1B-2B-312Boring Location DiagramLot 7 Poudre Valley Plaza - Fort Collins, ColoradoEEC Project #: 1202075October 2020EARTH ENGINEERING CONSULTANTS, LLCASSro[imate BoringLocations1LegendSite PKotosPKotos taNen in aSSro[imatelocation, in direction oI arroZ
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
SPARSE VEGETATION _ _
1
CLAYEY SAND (SC) _ _
red / brown / tan 2
dense to medium dense _ _
3
_ _
4
_ _
CS 5 32 9000+ 9.4 123.4 33 19 46.2 7500 psf 5.2%
_ _
6
_ _
7
_ _
8
_ _
9
_ _
SS 10 10 8000 16.4
_ _
11
_ _
12
_ _
13
_ _
with organics 14
_ _
CS 15 28 9.9 117.8
_ _
16
_ _
17
_ _
CLAYSTONE / SILTSTONE / SANDSTONE 18
brown / gray / rust _ _
weathered to moderately hard / poorly cemented 19
_ _
SS 20 50/11" 16.3
_ _
21
_ _
22
_ _
23
_ _
24
_ _
CS 25 50/5" 5500 15.9 112.5 29 4 20.3 < 1000 psf None
Continued on Sheet 2 of 2 _ _
Earth Engineering Consultants, LLC
POUDRE VALLEY PLAZA - LOT 7
FORT COLLINS, COLORADO
LOG OF BORING B-1PROJECT NO: 1202075 OCTOBER 2020
SHEET 1 OF 2 WATER DEPTH
START DATE 10/21/2020 WHILE DRILLING 15'
APPROX. SURFACE ELEV. 5086
FINISH DATE 10/21/2020
A-LIMITS SWELL
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
Continued from Sheet 1 of 2 26
_ _
CLAYSTONE / SILTSTONE / SANDSTONE 27
brown / gray / rust _ _
moderately hard to hard / poorly cemented 28
_ _
29
_ _
SS 30 50 16.2
_ _
31
_ _
32
_ _
33
_ _
34
_ _
CS 35 50/4" 9000+ 16.6 117.0
BOTTOM OF BORING DEPTH 35' _ _
36
_ _
37
_ _
38
_ _
39
_ _
40
_ _
41
_ _
42
_ _
43
_ _
44
_ _
45
_ _
46
_ _
47
_ _
48
_ _
49
_ _
50
_ _
Earth Engineering Consultants
POUDRE VALLEY PLAZA - LOT 7
FORT COLLINS, COLORADO
LOG OF BORING B-1 OCTOBER 2020PROJECT NO: 1202075
SHEET 2 OF 2 WATER DEPTH
START DATE 10/21/2020 WHILE DRILLING 15'
10/21/2020 AFTER DRILLING
APPROX. SURFACE ELEV. 24 HOUR
FINISH DATE
A-LIMITS SWELL
N/A
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
SPARSE VEGETATION _ _
1
SANDY LEAN CLAY (CL) _ _
red / brown 2
very stiff _ _% @150 psf
CS 3 30 6.3 99.7 33 17 50.6 800 psf 3.5%
_ _
4
_ _
SS 5 24 9000+ 11.9
_ _
6
_ _
7
_ _
8
_ _
9
with calcareous deposits _ _% @1000 psf
CS 10 28 9000+ 10.7 128.0 38 24 51.2 7500 psf 4.0%
_ _
11
_ _
12
_ _
13
_ _
14
_ _
SS 15 18 1500 23.8
_ _
CLAYSTONE / SILTSTONE / SANDSTONE 16
brown / gray / rust _ _
weathered to moderately hard / poorly cemented 17
_ _
18
_ _
19
_ _
CS 20 50/5" 9000+ 15.6 117.4
BOTTOM OF BORING DEPTH 20' _ _
21
_ _
22
_ _
23
_ _
24
_ _
25
_ _
Earth Engineering Consultants, LLC
POUDRE VALLEY PLAZA - LOT 7
FORT COLLINS, COLORADO
PROJECT NO: 1202075 LOG OF BORING B-2 OCTOBER 2020
SHEET 1 OF 2 WATER DEPTH
14.5'START DATE 10/21/2020 WHILE DRILLING
FINISH DATE 10/21/2020
APPROX. SURFACE ELEV. 5086
A-LIMITS SWELL
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
SPARSE VEGETATION _ _
1
CLAYEY SAND / SANDY LEAN CLAY (SC / CL) _ _
red 2
dense to medium dense / very stiff to stiff _ _
3
_ _
4
_ _
CS 5 35 9000+ 9.5 123.4 3500 psf 3.6%
_ _
6
_ _
7
_ _
8
_ _
9
with trace gravel _ _
SS 10 12 9000+ 13.6
_ _
11
_ _
12
_ _
13
_ _
14
_ _% @1000 psf
CLAYSTONE / SILTSTONE / SANDSTONE CS 15 34 9000+ 15.4 118.8 1400 psf 0.3%
brown / gray / rust _ _
weathered to moderately hard / poorly cemented 16
_ _
17
_ _
18
_ _
19
_ _
SS 20 50/11" 9000+ 14.3
_ _
BOTTOM OF BORING DEPTH 20.5' 21
_ _
22
_ _
23
_ _
24
_ _
25
_ _
Earth Engineering Consultants, LLC
POUDRE VALLEY PLAZA - LOT 7
FORT COLLINS, COLORADO
PROJECT NO: 1202075 LOG OF BORING B-3 OCTOBER 2020
SHEET 1 OF 2 WATER DEPTH
NoneSTART DATE 10/21/2020 WHILE DRILLING
FINISH DATE 10/21/2020
APPROX. SURFACE ELEV. 5087
A-LIMITS SWELL
Project:
Location:
Project #:
Date:
Poudre Valley Plaza - Lot 7
Fort Collins, Colorado
1202075
October 2020
Beginning Moisture: 9.4% Dry Density: 124.3 pcf Ending Moisture: 13.6%
Swell Pressure: 7500 psf % Swell @ 500: 5.2%
Sample Location: Boring 1, Sample 1, Depth 4'
Liquid Limit: 33 Plasticity Index: 19 % Passing #200: 46.2%
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Red / Brown / Tan Clayey Sand (SC)
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
10.0
0.01 0.1 1 10Percent MovementLoad (TSF)SwellConsolidatioWater Added
Project:
Location:
Project #:
Date:
Poudre Valley Plaza - Lot 7
Fort Collins, Colorado
1202075
October 2020
Beginning Moisture: 15.9% Dry Density: 113.6 pcf Ending Moisture: 20.2%
Swell Pressure: < 1000 psf % Swell @ 1000: None
Sample Location: Boring 1, Sample 5, Depth 24'
Liquid Limit: 29 Plasticity Index: 4 % Passing #200: 20.3%
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown / Gray / Rust Claystone / Siltstone / Sandstone
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
10.0
0.01 0.1 1 10Percent MovementLoad (TSF)SwellConsolidatioWater Added
Project:
Location:
Project #:
Date:
Poudre Valley Plaza - Lot 7
Fort Collins, Colorado
1202075
October 2020
Beginning Moisture: 6.3% Dry Density: 102.5 pcf Ending Moisture: 20.7%
Swell Pressure: 800 psf % Swell @ 150: 3.5%
Sample Location: Boring 2, Sample 1, Depth 2'
Liquid Limit: 33 Plasticity Index: 17 % Passing #200: 50.6%
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Red / Brown Sandy Lean Clay (CL)
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
10.0
0.01 0.1 1 10Percent MovementLoad (TSF)SwellConsolidatioWater Added
Project:
Location:
Project #:
Date:
Poudre Valley Plaza - Lot 7
Fort Collins, Colorado
1202075
October 2020
Beginning Moisture: 10.7% Dry Density: 128.3 pcf Ending Moisture: 12.2%
Swell Pressure: 7500 psf % Swell @ 1000: 4.0%
Sample Location: Boring 2, Sample 3, Depth 9'
Liquid Limit: 38 Plasticity Index: 24 % Passing #200: 51.2%
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Red / Brown Sandy Lean Clay (CL)
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
10.0
0.01 0.1 1 10Percent MovementLoad (TSF)SwellConsolidatioWater Added
Project:
Location:
Project #:
Date:
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Red Clayey Sand / Sandy Lean Clay (SC / CL)
Sample Location: Boring 3, Sample 1, Depth 4'
Liquid Limit: - - Plasticity Index: - - % Passing #200: - -
Beginning Moisture: 9.5% Dry Density: 118.4 pcf Ending Moisture: 18.0%
Swell Pressure: 3500 psf % Swell @ 500: 3.6%
Poudre Valley Plaza - Lot 7
Fort Collins, Colorado
1202075
October 2020
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
10.0
0.01 0.1 1 10Percent MovementLoad (TSF)SwellConsolidatioWater Added
Project:
Location:
Project #:
Date:
Poudre Valley Plaza - Lot 7
Fort Collins, Colorado
1202075
October 2020
Beginning Moisture: 15.4% Dry Density: 118.8 pcf Ending Moisture: 17.4%
Swell Pressure: 1400 psf % Swell @ 1000: 0.3%
Sample Location: Boring 3, Sample 3, Depth 14'
Liquid Limit: - - Plasticity Index: - - % Passing #200: - -
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown / Gray / Rust Claystone / Siltstone / Sandstone
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
10.0
0.01 0.1 1 10Percent MovementLoad (TSF)SwellConsolidatioWater Added