HomeMy WebLinkAbout209 CHERRY STREET - MIXED USE - PDP230006 - SUBMITTAL DOCUMENTS - ROUND 2 - GEOTECHNICAL (SOILS) REPORTSUBSURFACE EXPLORATION REPORT
PROPOSED 209 CHERRY STREET – MIXED USE DEVELOPMENT
SOUTH OF CHERRY STREET, WEST OF MASON STREET AND
NORTH OF PENNY FLATS PHASE I
FORT COLLINS, COLORADO
EEC PROJECT NO. 1232016
Prepared for:
Colmena Group
1201 E. Wilmington Avenue- Suite 115
Salt Lake City, Utah 84106
Attn: Mr. Matthew Ratelle (matthew@colmenagroup.com)
Prepared by:
Earth Engineering Consultants, LLC
4396 Greenfield Drive
Windsor, Colorado 80550
4396 GREENFIELD D RIVE
W INDSOR, COLORADO 80550
(970) 545-3908 FAX (970) 663-0282
March 24, 2023
Colmena Group
1201 E. Wilmington Avenue- Suite 115
Salt Lake City, Utah 84106
Attn: Mr. Matthew Ratelle (matthew@colmenagroup.com)
Re: Geotechnical Engineering Subsurface Exploration Report
Proposed 209 Cherry Street – Mixed Use Development Project
South of Cherry Street, West of Mason Street, and North of Penny Flats - Phase 1
Fort Collins, Colorado
EEC Project No. 1232016
Mr. Ratelle:
Enclosed herewith, are the results of the subsurface exploration completed by Earth Engineering
Consultants, LLC (EEC) for the referenced 209 Cherry Street Mixed Use Development project
planned for design and construction on the vacant the lot located south of Cherry Street, west of
Mason Street, and north of the previously constructed Penny Flats – Phase 1 project in Fort
Collins, Colorado. For this exploration, a total of four (4) supplemental borings were completed
at select locations across the site within the proposed mixed use building footprint as presented
herein. It should be noted that our sister firm, Earth Engineering Company (Earth COMPANY)
performed a subsurface exploration for the site in 2015 when the original concept for the site
were single-family residential townhomes. With the current complexity of the project planned as
a 7-story mixed use development, it was a project team decision to complete four (4)
supplemental borings at select locations to further characterize the underlying bedrock for a deep
foundation in lieu of the spread footings as previously described in the Earth COMPANY Geo-
Report dated October 7, 2015, Project No. 15-01-272. These site-specific supplemental borings
were extended to depths of approximately 35 feet below existing site grades. This subsurface
exploration was carried out in general accordance with our proposal dated January 6, 2023.
We understand the conceptual development plan for the site will consist of a 7-story mixed used
development project with a for-rent apartment building that is 5 levels of wood framing over 2
levels of podium decks, with an additional level of underground parking. We expect foundation
loads for the proposed project would be moderate to heavy with the anticipation of supporting
the building footprint on a deep foundation system consisting of either straight shaft drilled piers
or possibly a rammed aggregate pier (RAP) system extending into the underlying bedrock
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EEC Project No. 1232016
March 24, 2023
Page 2
formation. The proposed garage level diagram for the site is included herein which also
illustrates our proposed supplemental boring locations. We expect foundation loads for the
proposed mixed-use development, 7-story building with below grade parking, would be
moderate to heavy with anticipated wall loads of 3 to 6 kips per linear foot and concentrated
column loads on the order of 50 to 350 kips. Floor loads are expected to be moderate.
In summary, a surficial of layer of gravel, and/or topsoil/landscape materials were observed
throughout the site at the boring locations. An approximate 3 to 3-1/2 foot (±) layer of existing
fill material was encountered immediately beneath the surface materials; variations may exist
across the site. Native cohesive to slightly cohesive sandy lean clay and/or clayey sand subsoils
were encountered beneath the existing fill zone in boring B-2; while a fine to coarse granular
strata was encountered the fill zone in the remaining borings. The fine to coarse silty sand with
gravel and intermittent cobbles strata was encountered below the surficial zone in borings B-1,
and B-3 and B-4, and beneath the upper overburden subsoils in boring B-2 and extended to the
bedrock formation below. Claystone/siltstone/sandstone bedrock was encountered in all of the
supplemental borings at depths of approximately 9 to 12 feet below present site grades and
extended to maximum depths of exploration, approximately 35 feet. It should be noted the
subsurface profile described herein is relatively consistent with that described in the Earth
COMPANY subsurface exploration report dated October 7, 2015 Project No. 15-01-272.
At the time of drilling, free water was not observed in any of the supplemental borings
completed to maximum depths of exploration, approximately 35-feet below site grades. The
borings were backfilled with augers cuttings upon completion of the drilling operations,
therefore subsequent groundwater measurements were not obtained.
Based on the subsurface conditions encountered in the test borings, as well as the anticipated
maximum loading conditions, we recommend the proposed 7-story mixed use development
structure with below grade parking, be supported on either a grade beam and straight shaft drilled
pier foundation system extending into the underlying bedrock formation or on foundation
footings supported on subgrades improved with rammed aggregate piers (RAP) as described in
the text of the attached report. We anticipate floor slabs, and exterior flatwork could be
supported on newly placed and compacted fill soils or on ground modified in-place subsoils.
SUBSURFACE EXPLORATION REPORT
PROPOSED 209 CHERRY STREET – MIXED USE DEVELOPMENT
SOUTH OF CHERRY STREET, WEST OF MASON STREET AND
NORTH OF PENNY FLATS PHASE I
FORT COLLINS, COLORADO
EEC PROJECT NO. 1232016
March 24, 2023
INTRODUCTION
The geotechnical subsurface exploration for the proposed 7-story 209 Cherry Street Mixed Use
building, planned for design and construction on the vacant lot located south of Cherry Street, west
of Mason Street, and north of the previously constructed Penny Flats – Phase 1 project in Fort
Collins, Colorado has been completed. To develop subsurface information in the proposed
development area, four (4) supplemental soil borings were drilled within the proposed building
footprint to depths of approximately 35 feet below existing site grades. A site diagram indicating the
approximate boring locations is included with this report. It should be noted that our sister firm,
Earth Engineering Company (Earth COMPANY) performed a subsurface exploration for the site in
2015 when the original concept for the site were single-family residential townhomes. With the
current complexity of the project planned as a 7-story mixed use development, it was a project team
decision to complete four (4) supplemental borings at select locations to further characterize the
underlying bedrock for a deep foundation in lieu of the spread footings as previously described in the
Earth COMPANY Geo-Report dated October 7, 2015, Project No. 15-01-272.
We understand the conceptual development plan for the site will consist of a 7-story mixed used
development project with a for-rent apartment building that is 5 levels of wood framing over 2 levels
of podium decks, with an additional level of underground parking. We expect foundation loads for
the proposed project would be moderate to heavy with the anticipation of supporting the building
footprint on a deep foundation system consisting of either straight shaft drilled piers or possibly a
rammed aggregate pier (RAP) system extending into the underlying bedrock formation. The
proposed garage level diagram for the site is included herein which also illustrates our proposed
supplemental boring locations. We expect foundation loads for the proposed mixed use
development, 7-story building with below grade parking, would be moderate to heavy with
anticipated wall loads of 3 to 6 kips per linear foot and concentrated column loads on the order of 50
to 350 kips. Floor loads are expected to be moderate.
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The purpose of this report is to describe the subsurface conditions encountered in the supplemental
test borings completed as part of the subsurface exploration, analyze and evaluate the test data and
provide geotechnical recommendations concerning design and construction of foundations, support
of floor slabs, on-site pavement improvements and other earth related features for the proposed site
development.
EXPLORATION AND TESTING PROCEDURES
The boring locations were determined in the request for proposal and established in the field by a
representative of Earth Engineering Consultants, LLC (EEC) by pacing and estimating angles from
identifiable site features and by use of a hand-held GPS unit. Approximate ground surface
elevations at each boring location were estimated based on linear interpolation between contours
presented on the Fort Collins topographic quadrangle map, and Google Earth, and are recorded on
the boring logs included with this report. The location for each boring and estimated ground surface
elevations should be considered accurate only to the degree implied by the methods used for the field
measurements. Photographs of the site, taken at the time of drilling, are provided with this report.
The test borings were advanced using a truck mounted CME-75 drill rig equipped with a hydraulic
head employed in drilling and sampling operations. The boreholes were advanced using a
combination of 4-inch nominal diameter continuous flight augers and 4-1/4-inch inside diameter
hollow stem 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.
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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 by an engineer and
classified in 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. Classification of the bedrock was based on visual and tactual
observation of disturbed samples and auger cuttings. Coring and/or petrographic analysis may
reveal other rock types.
SITE AND SUBSURFACE CONDITIONS
The 209 Cherry Street Mixed Use Development project is located on the south side of Cherry, west
of Mason Street, and north of the recently completed Penny Flats – Phase I project in downtown Fort
Collins. As shown on the enclosed site plan and Google Earth image of the site, the BNSF railroad
tracks run north and south on the east side of Mason Street. The ground surface was relatively flat
and level and covered with sparse vegetation and surficial gravel.
In summary, a surficial of layer of gravel, and/or topsoil/landscape materials were observed
throughout the site at the boring locations. An approximate 3 to 3-1/2 foot (±) layer of existing fill
material was encountered immediately beneath the surface materials; variations may exist across the
site. Native cohesive to slightly cohesive sandy lean clay and/or clayey sand subsoils were
encountered beneath the existing fill zone in boring B-2; while a fine to coarse granular strata was
encountered the fill zone in the remaining borings. The fine to coarse silty sand with gravel and
intermittent cobbles strata was encountered below the surficial zone in borings B-1, and B-3 and B-
4, and beneath the upper overburden subsoils in boring B-2 and extended to the bedrock formation
below. Claystone/siltstone/sandstone bedrock was encountered in all of the supplemental borings at
depths of approximately 9 to 12 feet below present site grades and extended to maximum depths of
exploration, approximately 35 feet. It should be noted the subsurface profile described herein is
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EEC Project No. 1232016
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relatively consistent with that described in the Earth COMPANY subsurface exploration report dated
October 7, 2015 Project No. 15-01-272.
The stratification boundaries indicated on the boring logs represent the approximate locations of
changes in soil and bedrock types. In-situ, the transition of materials may be gradual and indistinct.
Well-cemented sandstone bedrock lenses were encountered at increased depths, as evident by the
Standard Penetration Test (SPT) results presented on the boring logs. SPT results of the underlying
bedrock formation with intermittent well-cemented sandstone lenses ranged from 50 blows per 6
inches to 50 blows per 3 inches at increased depths.
Existing Fill Material
Approximately 3 to 4 feet (+/-) of fill material was encountered across the site, as indicated in the
attached boring logs; variations may exist across the site. The fill material generally consisted of
silty sand with gravel, clayey sand with gravel and sandy lean clay with gravel. Based upon the
limited field penetration resistance values recorded within the fill zone during our exploration, the in-
situ moisture contents, and the in-situ dry densities, in general, the fill material is not uniform.
Variations of depth, quality, and characteristics of the fill material may exist across the site and may
not be revealed until time of construction. Additional field and laboratory testing as well as site
observations will be required during construction phases to verify consistency across each building
footprint.
GROUNDWATER CONDITIONS
Observations were made while drilling the borings to detect the presence and depth to hydrostatic
groundwater. At the time of drilling, free water was not observed in the supplemental borings to
maximum depths of exploration, approximately 35-feet below site grades. The borings were
backfilled with augers cuttings upon completion of the drilling operations, therefore subsequent
groundwater measurements were not obtained.
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
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to more accurately evaluate fluctuations 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.
Zones of perched and/or trapped water can be encountered at times throughout the year in more
permeable zones in the subgrade soils. Perched groundwater should be expected in the subgrade
soils immediately above the less permeable bedrock strata.
ANALYSIS AND RECOMMENDATIONS
General Considerations
The site appears suitable for the proposed development based on the subsurface conditions observed at
the test boring locations; however, certain precautions will be required in the design and construction
addressing the near surface variable fill, the removal/excavation of cobbles at increased depths and
penetration of the underlying well cemented sandstone bedrock lenses.
Based on review of Google Earth imagery, the site may have been used as parking lot as presented in
the Google Earth image circa 1999. Other than this particular image it did not appear that the site
was used for any other activities; however, previous operations may have taken place that were
present in the various Google Earth images dating date to circa 1985. In addition, any uncontrolled
fill material that may be encountered during the excavation phases, should be removed from
improvement and/or fill areas on the site. Demolition of any previous construction related activities,
should include complete removal of all concrete or debris within the proposed construction area.
Site preparation should include removal of any loose backfill found adjacent to any previous site
structures/improvements. All materials derived from the demolition of the site, or other site
improvements should be removed from the site and not be allowed for use in any on-site fills.
Depending upon the depth of excavation (i.e., for the lower parking structure lower level),
consideration should be given to installing an underdrain/underslab drainage system to intercept
surface water infiltration from impacting the lowest opening. Removal of large sized cobbles during
excavation procedures should be implemented to reduce the potential for point loading conditions
developing on the floor slabs.
It is anticipated that excavations for the proposed construction can be accomplished with
conventional earthmoving equipment. However, excavations penetrating the well-cemented
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sandstone bedrock may require the use of specialized heavy-duty equipment such as a rock hammer
or core barrel to achieve final design elevations. Consideration should be given to obtaining a unit
price for difficult excavation in the contract documents for the project.
Depending upon the depth of any lower-level construction, a shoring plan may be necessary to protect
the adjacent sidewall slopes. EEC is available to provide supplemental design criteria or details such
as but not limited to secant piles or piers, soldier piers, or a tie-back/bracing concept if requested.
Although evidence of fill materials beyond the depths described herein, or underground facilities
were not observed during the site exploration, such features could be encountered during
construction. If unexpected fills or underground facilities are encountered, such features should be
removed, and the excavation thoroughly cleaned prior to backfill placement and/or construction.
Swell – Consolidation Test Results
The swell-consolidation test is performed to evaluate the swell or collapse potential of soils or bedrock
to help determine foundation, floor slab and pavement design criteria. In this test, relatively intact
samples obtained directly from the California barrel 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 initial thickness. Samples
obtained at approximate depths of 1 to 2 feet are generally pre-loaded at 150 psf to simulate the
pavement loading conditions, while samples obtained at the 3 to 4-foot intervals are pre-loaded at 500
psf to simulate the overburden soil pressure. All samples are inundated with water and monitored for
swell and consolidation. After the inundation period, additional incremental loads are applied to
evaluate the swell pressure and consolidation response.
Within this phase of the project, we conducted six (6) swell-consolidation tests at various
intervals/depths. The swell index values for the samples analyzed revealed low swell characteristics of
(-) 0.2 % to (+) 1.9 %. The higher swell index values determined in the laboratory were of the
underlying claystone bedrock formation samples.
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
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influence slab performance.” Geotechnical engineers use this information to also evaluate the swell
potential risks for foundation performance based on the risk categories.
Table I - 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 soil and bedrock samples analyzed for this project were
within the low range.
Site Preparation
Although final site grades were not available at the time of this report, based on our understanding of
the proposed development, we expect small cuts and/or fills, less than 2 to 3 feet, would be required
to achieve pavement subgrade and finished floor elevations. After removal of all existing
pavements, any existing fill material, and removal of any previous demolition debris across the site,
an extensive/thorough evaluation of the exposed over excavation base material should be completed.
Prior to placement of any fill or site improvements, we recommend the exposed soils be scarified to
a minimum 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. If excavations
extend to the underlying cemented sandstone bedrock, scarification and recompacting is not
necessary.
With the potential soft/compressible characteristics of native cohesive to slightly cohesive
clay/clayey sand soils across portions of the site, ground stabilization mechanism may be necessary
to create a working platform for fill placement. Placement of a granular material, such as a 3-inch
minus recycled concrete or equivalent, may be necessary as a subgrade enhancement layer
embedded into the soft soils, prior to placement of additional fill material or operating heavy earth-
moving equipment. Removal and replacement of the soft/compressible soils could also be
considered. Supplemental recommendations can be provided upon request.
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Fill soils required for developing the building and site subgrades, after the initial zone has been
stabilized, should consist of approved, low-volume-change materials, which are free from organic
matter and debris. We recommend approved imported structural fill materials be placed and
compacted within the building footprint(s) and consist of essentially granular soils with less than
20% material passing the No. 200 sieve. Beneath the lower level parking structure and the at-grade
level floor slabs for the project, we recommend a minimum 2-foot layer of structural fill material be
placed and compacted to reduce potential differential movement across the building footprint due to
the variations of the on-site subsoils. In our opinion, with close observation/evaluation of the
subgrades in the pavement areas, that imported structural fill zone could be eliminated as long as the
in-place over-excavated and replaced on-site subsoils, replaced placed as engineered/controlled fill
material appears stable. We recommend fill materials be placed in loose lifts not to exceed 9 inches
thick, adjusted in moisture content to within ±2% of optimum moisture content, and compacted to at
least 95% of the material’s maximum dry density as determined in accordance with ASTM
Specification D698, the standard Proctor procedure. The moisture content of granular structural fill
in the floor areas should be adjusted to within ±3% of optimum moisture content and compacted to
at least 95% of standard Proctor maximum dry density.
Care should be exercised after preparation of the subgrades to avoid disturbing the subgrade
materials. Positive drainage should be developed away from the structures to avoid wetting of
subgrade materials. Subgrade materials becoming wet subsequent to construction of the site
structures can result in unacceptable performance.
Areas of deeper fills may experience settlement from underlying native soils and within the placed
fill materials. Settlement on the order of 1-inch or more per each 10 feet of fill depth would be
estimated. The rate of settlement will be dependent on the type of fill material placed and
construction methods. Granular soils will consolidate essentially immediately upon placement of
overlying loads. Cohesive soils will consolidate at a slower rate.
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 systems were
evaluated for use on the site for the proposed buildings.
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• Straight shaft drilled piers bearing into the underlying bedrock formation.
• Ground modification by use of a Geo-pier system extending into the underlying dense sand
and gravels or to bedrock and supporting the buildings of spread footings and/or a structural
mat.
Other alternative foundation systems could be considered, and we would be pleased to provide
additional alternatives upon request.
Drilled Piers/Caissons
Based on the maximum anticipated wall and columns loads, we recommend the proposed 7-story
structure be supported by a grade beam and straight shaft drilled pier/caisson foundation system
extending into the underlying bedrock formation. Particular attention will be required in the
construction of drilled piers due to the presence of intermittent cobbles within the granular zone and
groundwater or a perched surface water condition.
For axial compression loads, the drilled piers could be designed using a maximum end bearing
pressure of 40,000 pounds per square foot (psf), along with a skin-friction of 4,000 psf for the portion
of the pier extended into the underlying firm and/or harder bedrock formation. Straight shaft piers
should be drilled a minimum of 10 feet into competent or harder bedrock.
Required pier penetration should be balanced against potential uplift forces due to the potential for low
expansive characteristics of the subsoils and underlying bedrock on 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 16-feet from ground surface and into the bearing strata.
To satisfy forces in the horizontal direction, piers may be designed for lateral loads using a modulus of
50 tons per cubic foot (tcf) for the portion of the pier in native cohesive soils, 75 tcf for native granular
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materials or engineered fill, and 400 tcf in bedrock for a pier diameter of 12 inches. The coefficient of
subgrade reaction for varying pier diameters is as follows:
Table II - Lateral Load Coefficient of Subgrade Reaction
Pier Diameter (inches)
Coefficient of Subgrade Reaction (tons/ft3)
Essentially Cohesive Soils Engineered Fill or
Granular Soils Bedrock
18 33 50 267
24 25 38 200
30 20 30 160
36 17 25 133
When the lateral capacity of drilled piers is evaluated by the L-Pile 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 program:
Table III - L-Pile Parameters
Parameters Native Granular Soils
or Structural Fill
On-Site Overburden
Essentially Cohesive
Soils
Bedrock
Unit Weight of Soil (pcf) 130(1) 115(1) 125(1)
Cohesion (psf) 0 1000 5000
Angle of Internal Friction ∅ (degrees) 35 25 20
Strain Corresponding to ½ Max. Principal
Stress Difference ε50
--- 0.007 0.004
*Notes: 1) Use of 64 PCF below the water table
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
sandstone bedrock lenses may be encountered throughout the site at various depths where specialized
drilling equipment and/or rock excavating equipment may be required. Excavation penetrating the
well-cemented sandstone bedrock may require the use of specialized heavy-duty equipment, together
with rock augers and/or core barrels. Consideration should be given to obtaining a unit price for
difficult caisson excavation in the contract documents for the project.
Due to the depth of groundwater or the presence of groundwater via perched surface water conditions,
as well as removal and/or drilling within large sized cobbles zones, maintaining shafts may be difficult
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without stabilizing measures. Groundwater was not observed in the supplemental borings completed
to depths of approximately 35-feet below site grades; however, perched surface water may be
encountered at the bedrock interface. Therefore, temporary casing may be required to
adequately/properly drill and clean piers prior to concrete placement. Groundwater should be removed
from each pier hole prior to concrete placement. Pier concrete should be placed immediately after
completion of drilling and cleaning.
A maximum 3-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. Pier concrete with slump in the range of 6 to 8 inches is recommended. Casing used for pier
construction 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.
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 significantly from those presented in this report, supplemental recommendations
will be required.
Ground Modifications – Rammed Aggregate Pier (RAP) Foundation System
Based on the soils observed at the boring locations, it is our opinion the proposed building could also
be supported on spread footing foundations bearing on ground modified/improved subgrades.
Without ground modifications/improvements, the natural site soils would not be suitable for direct
support of spread footing foundations.
To develop support for spread footing/grade beam foundations, we recommend improving the
subgrades using rammed aggregate piers. Recommendations for ground improvement using rammed
aggregate piers are provided to develop adequate support capacity for the foundations and reduce the
potential for post-construction settlement of the building’s foundations. Note that rammed aggregate
piers are also recommended under heavy floor slabs and are included in the section titled Floor
Slabs.
Rammed aggregate piers generally consist of driving/placing aggregate into the supporting
subgrades to develop aggregate piers or columns. The rammed aggregate piers would provide
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support for the overlying spread footings while also improving the stiffness of the adjacent
subgrades. Common allowable bearing pressures of 3,000 to 6,000 psf or higher can be developed
with this system; design bearing pressures should be provided by the installer/designer. To develop
pier capacity, we recommend the rammed aggregate piers extend through the near surface cohesive
soils and bear in the underlying dense sand and gravels and/or into the underlying bedrock
formation. Pile load tests should be carried out to verify actual pile load and displacement
characteristics. Rammed aggregate piers would likely be installed after completion of any site cuts
and fills. A qualified and reputable rammed aggregate pier installer should provide the necessary
design recommendations for the piers.
We recommend formed continuous footings be a minimum of 16 inches wide and column
foundations have minimum width of 30 inches. Exterior foundations and foundations in unheated
areas should be located a minimum of 30 inches below adjacent exterior grades to provide frost
protection. Trenched or grade beam foundations should not be used.
Care should be taken at the time of construction to avoid disturbing the bearing soils. Bearing soils
should be closely observed to see that aggregate piers are properly located beneath planned
foundations. Soils which are loosened or disturbed by the construction activities or soils which
become dry and desiccated or wet and softened should be removed and replaced with a material
approved by the aggregate pier designer prior to construction of the footings.
Foundation and Utility Backfill
Backfill needed to develop site grades following installation of foundations and site utilities should
consist of low volume change materials which are free of organic matter and debris. In our opinion the
site sandy lean clay, clayey sand, or sand soils could be used. Those soils should be moisture
conditioned and compacted as outlined for the fill soils in the section Site Preparation.
Seismic
The site soil conditions consist of approximately 9 to 17 feet of overburden soils overlying
moderately hard/cemented bedrock. For those site conditions, the 2018 International Building Code
indicates a Seismic Site Classification of C.
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Lateral Earth Pressures
A portion of the structure(s) may be constructed “below grade” given the anticipated final site
grades. Those structures will 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. 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 IV 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 essentially granular materials with a friction angle of a 30
degrees or low volume change cohesive soils. For the at-rest and active earth pressures, slopes away
from the structure would result in reduced driving forces with slopes up 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. 1232016
March 24, 2023
Page 14
Table IV - Lateral Earth Pressures
Soil Type Low Plasticity Cohesive Medium Dense Granular
Wet Unit Weight 115 135
Saturated Unit Weight 135 140
Friction Angle (∅) 25° 35°
Active Pressure Coefficient 0.41 0.27
At-rest Pressure Coefficient 0.58 0.43
Passive Pressure Coefficient 2.46 3.70
Coefficient of Friction at Base 0.25 0.35
The outlined values do not include factors of safety nor allowances for hydrostatic loads. 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. A relatively impervious soil should be
used in the upper layer of backfill to reduce the potential for surface 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.
Floor Slabs
Slab-on-grade construction is feasible for the site provided certain precautions are adhered to.
Conventional slab-on-grade construction is feasible where slabs are placed a minimum of 4 feet
above the groundwater levels. If lower level “floor” slabs encroach on the minimum 4-foot
Earth Engineering Consultants, LLC
EEC Project No. 1232016
March 24, 2023
Page 15
separation, consideration should be given to installing an underslab drainage system. Due to the type
of construction and variability of the on-site subsoils and existing fill material encountered, and to
reduce floor slab movement for the below grade parking level slab, as presented in the Site
Preparation of this report, we recommend the proposed floor slab on grade bear on a zone of
properly placed and compacted imported structural fill material, such as CDOT Class 5, 6, or 7
aggregate base course material or recycled concrete. As indicated in the section Site Preparation,
the zone of granular fill should be at 2 feet thick for the below parking level slab. The approved fill
material should be placed in 9-inch loose lifts, moisture conditioned to within ±3% of optimum
moisture content and compacted to at least 95% of standard Proctor maximum dry density (ASTM
Specification D698). This procedure will not fully eliminate the possibilities of slab movement; but
movements should be reduced and tend to be more uniform. We estimate the long-term movement
of floor slabs with properly prepared subgrade subsoils as outlined above would be about one inch or
less.
For structural design of concrete slabs-on-grade, a modulus of subgrade reaction of 200 pounds per
cubic inch (pci) may be used for floors supported on non-expansive imported structural fill material
as previously described.
Additional floor slab design and construction recommendations are as follows:
• Positive separations and/or isolation joints should be provided between slabs and all
foundations, columns or utility lines to allow 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,
Section 302.1R are recommended.
Pavements
Pavement subgrades should be prepared as outlined in the section Site Preparation. We anticipate
the site pavements would include areas designated for low volumes of light weight automobiles
(light duty) and areas of higher volumes for use with light weight trucks for delivery as well as the
Earth Engineering Consultants, LLC
EEC Project No. 1232016
March 24, 2023
Page 16
alley way between the retail/senior living building and parking garage (heavy duty). An equivalent
daily load application (EDLA) value of 7 was assumed for light duty areas, and an EDLA of 15 was
assumed for heavy duty areas. Based on the subsurface conditions encountered at the site, an
assumed R-value of 10 was used in design of the pavement sections.
Recommended minimum pavement sections are provided below in Table V. Hot Bituminous
Pavement (HBP) sections may show rutting/distress in truck loading and drive areas; therefore,
concrete pavements should be considered in these areas. The recommended pavement sections are
considered minimum; thus, periodic maintenance should be expected.
Table V - Recommended Minimum Pavement Sections
Automobile Parking Heavy Duty Areas
18-kip EDLA
18-kip ESAL’s
Reliability
Resilient Modulus (R = 10)
PSI Loss
7
51,100
75%
3562 psi
2.5
15
109,500
85%
3562 psi
2.2
Design Structure Number 2.47 2.96
(A) Composite
Hot Bituminous Pavement
Aggregate Base
(Design Structural Number)
4"
7"
(2.53)
5"
7"
(2.98)
(B) Composite with Fly Ash Treated Subgrade
Hot Bituminous Pavement
Aggregate Base
Fly Ash Treated Subgrade
(Design Structure Number)
3½"
6"
12"
(2.70)
4"
7"
12"
(3.03)
(C) PCC (Non-reinforced) 5" 6"
Proofrolling and recompacting the subgrade is recommended immediately prior to placement of the
aggregate road base section. Soft or weak areas delineated by the proofrolling operations should be
undercut or stabilized in-place to achieve the appropriate subgrade support. We recommend
aggregate base meet a CDOT Class 5 or Class 6 aggregate base. Aggregate base should be adjusted
in moisture content and compacted to achieve a minimum of 95% of standard Proctor maximum dry
density.
HBP should be graded as SX or S and be prepared with 75 gyrations using a Superpave gyratory
compactor in accordance with CDOT standards. The HBP should consist of PG 58-28 or PG 64-22
asphalt binder. HBP should be compacted to achieve 92 to 96% of the mix’s theoretical maximum
specific gravity (Rice Value).
Earth Engineering Consultants, LLC
EEC Project No. 1232016
March 24, 2023
Page 17
Portland cement concrete should be an approved exterior pavement mix with a minimum 28-day
compressive strength of 4,500 psi and should be air entrained. Wire mesh or fiber could be considered
to reduce shrinkage cracking.
Long-term pavement performance will be dependent upon several factors, including maintaining
subgrade moisture levels and providing for preventive maintenance. The following
recommendations should be considered the minimum:
• The subgrade and the pavement surface should be adequately sloped to promote proper surface
drainage.
• Install pavement drainage surrounding areas anticipated for frequent wetting (e.g., landscaped and
irrigated islands, etc.),
• Install joint sealant and seal cracks immediately,
• Seal all landscaped areas in, or adjacent to pavements to minimize or prevent moisture migration
to subgrade soils;
• Placing compacted, low permeability backfill against the exterior side of curb and gutter; and,
• Placing curb, gutter, and/or sidewalk directly on approved proof rolled subgrade soils without
the use of base course materials.
Please note that if during or after placement of the stabilization or initial lift of pavement, the area is
observed to be yielding under vehicle traffic or construction equipment, it is recommended that EEC
be contacted for additional alternative methods of stabilization, or a change in the pavement section.
Water Soluble Sulfates (SO4)
The water-soluble sulfate (SO4) content of the on-site overburden subsoils, 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 is provided in this report.
Earth Engineering Consultants, LLC
EEC Project No. 1232016
March 24, 2023
Page 18
Table VI - Water Soluble Sulfate Test Results
Sample Location Description Soluble Sulfate Content (%)
B-2, S-9, at 9’ Sandy Lean Clay 0.02
B-4, S-5, at 19’ Siltstone / Claystone Bedrock 0.02
Based on the results as presented above, ACI 318, Section 4.2 indicates the overburden subsoils and
underlying sandstone bedrock materials have a low risk of sulfate attack on Portland cement
concrete, therefore, ACI 318 indicates site concrete should be designed with a sulfate exposure of S0
or higher. 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 structure and pavement 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 building 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 placed
within 5 feet of the perimeter of the building and parking areas. Spray heads should be designed not
to spray water on or immediately adjacent to the structure or site pavements. Roof drains should be
designed to discharge at least 5 feet away from the structure and away from the pavement areas.
Excavations into the on-site soils may encounter a variety of conditions. Excavations into the on-site
clays can be expected to stand on relatively steep temporary slopes during construction. However, if
excavations extend into the underlying granular strata, caving soils may be encountered. 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.
Earth Engineering Consultants, LLC
EEC Project No. 1232016
March 24, 2023
Page 19
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 Colmena Group, 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.
209 CHERRY STREET
FORT COLLINS, COLORADO
EEC PROJECT NO. 1232016
MARCH 2023
B-1 B-2
B-3 B-4
1
2
Figure 1: Test Boring Location Diagram
209 Cherry Street
Fort Collins, Colorado
EEC Project #: 1232016 Date: March 2023
ASSro[imate Boring
Locations
1
EARTH ENGINEERING CONSULTANTS, LLC
Legend
Site Photos
Photos taNen in aSSro[imate
location, in direction oI arroZ
B-1 B-2
B-3 B-4
B-1
B-2
B-3
B-4 B-5
B-6
B-7 B-8
B-9
B-10 B-11
1
2
EARTH ENGINEERING CONSULTANTS, LLC
Figure 2: Test Boring Location Diagram
209 Cherry Street
Fort Collins, Colorado
EEC Project #: 1232016 Date: March 2023
B1 Through B
ASSro[ Locations oI
SuSSlemental
Borings, 3
Legend
B1 Through B11
ASSro[ Locations oI
Earth Engineering
ComSany Borings
ComSleted in SeSt
201 Project No
10122
DATE:
RIG TYPE: CME55
FOREMAN: AK
AUGER TYPE: 4-1/4" Inside Dia. HSA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF
SPARSE VEGETATION AND COBBLES _ _
1
_ _
FILL MATERIAL: Silty Sand with Gravel 2
brown/red, dry to moist, presence of clay lens _ _
3
_ _
4
_ _
SAND / GRAVEL (SP / GP)SS 5 8 4500 9.6
brown/red _ _
loose to medium dense 6
_ _
7
_ _
8
_ _
9
_ _
* interbedded SANDY LEAN CLAY (CL) lens CS 10 14 15.3 101.3 33 18 52.3
_ _
11
_ _
12
_ _
CLAYSTONE/SILTSTONE BEDROCK 13
brown/gray/rust _ _
weathered, soft to moderately hard 14
_ _
SS 15 40 9000+14.9
_ _
*more competent with increased depths 16
_ _
17
_ _
18
_ _
19
_ _% @1000 PSF
CS 20 50/6"9000+12.1 119.0 3800 PSF 1.7%
_ _
21
*interbedded SANDSTONE lenses _ _
22
_ _
23
black/gray _ _
24
_ _
SS 25 50/5"9.2
Continued on Sheet 2 of 2 _ _
Earth Engineering Consultants, LLC
209 CHERRY STREET - MIXED USE DEVELOPMENT
LOG OF BORING B-1PROJECT NO: 1232016 MARCH 2023
FORT COLLINS, COLORADO
SHEET 1 OF 2 WATER DEPTH
START DATE 3/10/2023 WHILE DRILLING None
APPREOX. ELEV. 4979 24 HOUR N/A
FINISH DATE 3/10/2023 AFTER DRILLING N/A
A-LIMITS SWELL
DATE:
RIG TYPE: CME55
FOREMAN: AK
AUGER TYPE: 4-1/4" Inside Dia. HSA
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 27
brown/gray/rust _ _
moderately hard to hard 28
_ _
29
_ _
CS 30 50/4"9.4 114.0
*intermittent cemented SANDSTONE lenses _ _
31
_ _
32
_ _
33
_ _
34
_ _
SS 35 50/4"9.1
_ _
BOTTOM OF BORING DEPTH 35.5'36
_ _
37
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38
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39
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40
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41
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Earth Engineering Consultants, LLC
209 CHERRY STREET - MIXED USE DEVELOPMENT
LOG OF BORING B-1 MARCH 2023PROJECT NO: 1232016
FORT COLLINS, COLORADO
SHEET 2 OF 2 WATER DEPTH
START DATE 3/10/2023 WHILE DRILLING None
3/10/2023 AFTER DRILLING N/A
APPREOX. ELEV. 24 HOUR N/A
FINISH DATE
A-LIMITS SWELL
4979
DATE:
RIG TYPE: CME55
FOREMAN: AK
AUGER TYPE: 4-1/4" Inside Dia. HSA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF
SPARSE VEGETATION AND TOPSOIL _ _
1
FILL MATERIAL: - Sandy Lean Clay with Gravel _ _
brown, dry to moist, medium stiff 2
_ _
3
_ _
4
SANDY LEAN CLAY (CL)_ _
brown, dry to moist, medium stiff to stiff CS 5 10 3500 12.4 114.2 28 12 60.6 <500 PSF None
with trace gravel at increased depths _ _
6
_ _
7
_ _
8
_ _
9
_ _
SS 10 10 4000 18.1
_ _
11
_ _
12
_ _
SAND / GRAVEL (SP / GP)13
brown/red _ _
medium dense to dense 14
_ _
SS 15 24 1.4
_ _
16
_ _
17
_ _
CLAYSTONE/SILTSTONE BEDROCK 18
brown/gray/rust _ _
weathered, moderately hard to hard 19
_ _% @1000 PSF
CS 20 50/8"9000+15.5 114.4 1800 PSF 0.5%
_ _
*more competent with increased depths 21
_ _
22
_ _
23
*intermittent cemented SANDSTONE lenses _ _
24
_ _
CS 25 50/4"10.8
Continued on Sheet 2 of 2 _ _
Earth Engineering Consultants, LLC
A-LIMITS SWELL
APPREOX. ELEV. 4979 24 HOUR N/A
FINISH DATE 3/10/2023 AFTER DRILLING N/A
SHEET 1 OF 2 WATER DEPTH
START DATE 3/10/2023 WHILE DRILLING None
209 CHERRY STREET - MIXED USE DEVELOPMENT
PROJECT NO: 1232016 LOG OF BORING B-2 MARCH 2023
FORT COLLINS, COLORADO
DATE:
RIG TYPE: CME55
FOREMAN: AK
AUGER TYPE: 4-1/4" Inside Dia. HSA
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
_ _
SANDSTONE/ SILTSTONE BEDROCK 27
gray _ _
dry, moderately hard to hard, poorly cemented to cemented 28
_ _
29
_ _
CS 30 50/3"9.4 98.0
_ _
31
_ _
*intermittent cemented SANDSTONE lenses 32
_ _
33
_ _
34
_ _
CS 35 50/3.5"8.5
BOTTOM OF BORING DEPTH 35'_ _
36
_ _
37
_ _
38
_ _
39
_ _
40
_ _
41
_ _
42
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43
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Earth Engineering Consultants, LLC
A-LIMITS SWELL
4979
3/10/2023 AFTER DRILLING N/A
APPREOX. ELEV. 24 HOUR N/A
FINISH DATE
SHEET 2 OF 2 WATER DEPTH
START DATE 3/10/2023 WHILE DRILLING None
209 CHERRY STREET - MIXED USE DEVELOPMENT
PROJECT NO: 1232016 LOG OF BORING B-2 MARCH 2023
FORT COLLINS, COLORADO
DATE:
RIG TYPE: CME55
FOREMAN: AK
AUGER TYPE: 4-1/4" Inside Dia. HSA
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
FILL MATERIAL: - Sandy Lean Clay with Gravel _ _
brown, dry to moist, medium stiff 2
_ _
SS 3 12 4.6
SAND / GRAVEL (SP / GP)_ _
brown/red 4
medium dense to dense _ _
SS 5 12 5.7
_ _
6
_ _
7
_ _
8
_ _
9
_ _
SS 10 35 3.2
_ _
11
_ _
SILTSTONE/CLAYSTONE BEDROCK 12
brown/gray/rust _ _
weathered, soft to moderately hard 13
_ _
14
*classified as LEAN CLAY (CL)_ _% @1000 PSF
CS 15 50/8"9000+13.5 120.1 43 26 98.9 4000 PSF 1.9%
_ _
16
_ _
*more competent with increased depths 17
_ _
18
black/gray _ _
19
_ _
SS 20 50/5"9.5
_ _
21
*intermittent SANDSTONE lenses _ _
22
_ _
23
_ _
24
_ _
CS 25 50/5.5"9.9 107.8
Continued on Sheet 2 of 2 _ _
Earth Engineering Consultants, LLC
A-LIMITS SWELL
APPREOX. ELEV. 4980 24 HOUR N/A
FINISH DATE 3/10/2023 AFTER DRILLING N/A
SHEET 1 OF 2 WATER DEPTH
START DATE 3/10/2023 WHILE DRILLING None
209 CHERRY STREET - MIXED USE DEVELOPMENT
PROJECT NO: 1232016 LOG OF BORING B-3 MARCH 2023
FORT COLLINS, COLORADO
DATE:
RIG TYPE: CME55
FOREMAN: AK
AUGER TYPE: 4-1/4" Inside Dia. HSA
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
_ _
SANDSTONE/ SILTSTONE BEDROCK 27
gray _ _
dry, moderately hard to hard, poorly cemented to cemented 28
_ _
29
_ _
SS 30 50/4"8.8
_ _
31
_ _
*intermittent cemented SANDSTONE lenses 32
_ _
33
_ _
34
_ _
CS 35 50/5"9.2 107.6
BOTTOM OF BORING DEPTH 35'_ _
36
_ _
37
_ _
38
_ _
39
_ _
40
_ _
41
_ _
42
_ _
43
_ _
44
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Earth Engineering Consultants, LLC
A-LIMITS SWELL
4980
3/10/2023 AFTER DRILLING N/A
APPREOX. ELEV. 24 HOUR N/A
FINISH DATE
SHEET 2 OF 2 WATER DEPTH
START DATE 3/10/2023 WHILE DRILLING None
209 CHERRY STREET - MIXED USE DEVELOPMENT
PROJECT NO: 1232016 LOG OF BORING B-3 MARCH 2023
FORT COLLINS, COLORADO
DATE:
RIG TYPE: CME55
FOREMAN: AK
AUGER TYPE: 4-1/4" Inside Dia. HSA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF
SPARSE VEGETATION AND TOPSOIL _ _
1
_ _
FILL MATERIAL: - Clayey Sand with Gravel 2
brown, dry to moist, stiff _ _% @ 150 PSF
CS 3 24 7.3 122.7 24 11 29.3 <150 PSF None
_ _
SAND / GRAVEL (SP / GP)4
brown/red _ _
medium dense to dense SS 5 50/12"1.6
_ _
6
_ _
7
_ _
8
_ _
9
_ _
CLAYSTONE/SILTSTONE BEDROCK SS 10 39 5500 16.9
brown/gray/rust _ _
weathered, soft to moderately hard 11
_ _
12
_ _
*more competent with increased depths 13
_ _
14
_ _% @1000 PSF
* classified as LEAN CLAY (CL)CS 15 50/6"9000+13.3 118.0 46 29 94.8 3000 PSF 1.3%
_ _
16
_ _
17
_ _
18
*interbedded SANDSTONE lenses _ _
19
_ _
SS 20 50/8"9000+14.5
_ _
21
_ _
22
_ _
23
_ _
24
_ _
black/gray CS 25 50/6"10.3 101.9
Continued on Sheet 2 of 2 _ _
Earth Engineering Consultants, LLC
209 CHERRY STREET - MIXED USE DEVELOPMENT
PROJECT NO: 1232016 LOG OF BORING B-4 MARCH 2023
FORT COLLINS, COLORADO
SHEET 1 OF 2 WATER DEPTH
START DATE 3/10/2023 WHILE DRILLING None
APPREOX. ELEV. 4980 24 HOUR N/A
FINISH DATE 3/10/2023 AFTER DRILLING N/A
A-LIMITS SWELL
DATE:
RIG TYPE: CME55
FOREMAN: AK
AUGER TYPE: 4-1/4" Inside Dia. HSA
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
_ _
SANDSTONE/ SILTSTONE BEDROCK 27
gray _ _
dry, moderately hard to hard, poorly cemented to cemented 28
_ _
29
_ _
SS 30 50/5.5"11.4
_ _
31
_ _
*intermittent cemented SANDSTONE lenses 32
_ _
33
_ _
34
_ _
CS 35 50/4"9.8 104.9
BOTTOM OF BORING DEPTH 35'_ _
36
_ _
37
_ _
38
_ _
39
_ _
40
_ _
41
_ _
42
_ _
43
_ _
44
_ _
45
_ _
46
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47
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48
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49
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50
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Earth Engineering Consultants, LLC
209 CHERRY STREET - MIXED USE DEVELOPMENT
PROJECT NO: 1232016 LOG OF BORING B-4 MARCH 2023
FORT COLLINS, COLORADO
SHEET 2 OF 2 WATER DEPTH
START DATE 3/10/2023 WHILE DRILLING None
3/10/2023 AFTER DRILLING N/A
APPREOX. ELEV. 24 HOUR N/A
FINISH DATE
A-LIMITS SWELL
4980
PENNY FLATS PHASE 2
FORT COLLINS, COLORADO
PROJECT NO: 15-01-272 DATE:SEPTEMBER 2015
LOG OF BORING B-1
RIG TYPE: CME75 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 9/10/2015 WHILE DRILLING None
AUGER TYPE: 4" CFA FINISH DATE 9/10/2015 AFTER DRILLING None
SPT HAMMER: AUTO SURFACE ELEV N/A 24 HOUR None
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF
FILL: SAND AND GRAVEL (SP-GP)_ _
brown 2
medium dense with a slight amount of clay SS _ _16 6000 8.2
4
SAND AND GRAVEL (SP-GP)SS _ _50/6"--1.5
brown 6
very dense _ _
with cobbles 8
_ _
SS 10 26 9000 17.8
CLAYSTONE _ _
grey/brown/rust 12
moderately hard _ _
14
CS _ _50/9"9000+12.3 122.7 3000 psf 1.2%@1000
16
_ _
18
_ _
SS 20 50/11"6000 17.9
_ _
22
_ _
24
CS _ _50/4"6000 8.8 86.4 < 1000 psf None@1000
SHALE 26
grey _ _
hard 28
_ _
30
_ _
32
_ _
34
_ _
35' BOTTOM OF BORING 36
_ _
38
_ _
40
_ _
42
_ _
44
_ _
46
_ _
48
_ _
50
Earth Engineering Company
PENNY FLATS PHASE 2
FORT COLLINS, COLORADO
PROJECT NO: 15-01-272 DATE:SEPTEMBER 2015
LOG OF BORING B-2
RIG TYPE: CME75 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 9/10/2015 WHILE DRILLING None
AUGER TYPE: 4" CFA FINISH DATE 9/10/2015 AFTER DRILLING None
SPT HAMMER: AUTO SURFACE ELEV N/A 24 HOUR None
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF
FILL: SAND AND GRAVEL (SP-GP)_ _
brown/dark brown 2
medium dense CS _ _23 9000+9.6 113.3 NL NP 31.7 < 500 psf None
clayey 4
SS _ _9 1500 10.1
SAND AND GRAVEL (SP-GP)6
brown _ _
loose 8
_ _
with clay lenses and cobbles SS 10 2 4500 15.1
_ _
12
_ _
14
medium dense CS _ _25 --4.5
16
_ _
CLAYSTONE 18
grey/brown/rust _ _
moderately hard CS 20 50/11"--17.9 112.4 1400 psf 0.3%@1000
20' BOTTOM OF BORING _ _
22
_ _
24
_ _
26
_ _
28
_ _
30
_ _
32
_ _
34
_ _
36
_ _
38
_ _
40
_ _
42
_ _
44
_ _
46
_ _
48
_ _
50
Earth Engineering Company
PENNY FLATS PHASE 2
FORT COLLINS, COLORADO
PROJECT NO: 15-01-272 DATE:SEPTEMBER 2015
LOG OF BORING B-3
RIG TYPE: CME75 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 9/10/2015 WHILE DRILLING None
AUGER TYPE: 4" CFA FINISH DATE 9/10/2015 AFTER DRILLING None
SPT HAMMER: AUTO SURFACE ELEV N/A 24 HOUR None
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF
_ _
FILL: SAND AND GRAVEL (SP-GP)2
brown/dark brown _ _
medium dense 4
clayey CS _ _16 9000+17.6 75.0 < 500 psf None
6
_ _
8
SANDY LEAN CLAY (CL)_ _
brown SS 10 7 3000 13.0 < 500 psf None
stiff _ _
silty with a slight amount of gravel 12
_ _
14
SAND AND GRAVEL (SP-GP)CS _ _28 --2.1
brown 16
medium dense _ _
with cobbles 18
_ _
BS 20 --1500 9.4
CLAYSTONE _ _
grey/brown/rust 22
moderately hard _ _
24
SS _ _50/5"--11.3
SHALE 26
grey _ _
hard 28
_ _
30
_ _
32
_ _
34
_ _
35' BOTTOM OF BORING 36
_ _
38
_ _
40
_ _
42
_ _
44
_ _
46
_ _
48
_ _
50
Earth Engineering Company
PENNY FLATS PHASE 2
FORT COLLINS, COLORADO
PROJECT NO: 15-01-272 DATE:SEPTEMBER 2015
LOG OF BORING B-4
RIG TYPE: CME75 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 9/10/2015 WHILE DRILLING None
AUGER TYPE: 4" CFA FINISH DATE 9/10/2015 AFTER DRILLING None
SPT HAMMER: AUTO SURFACE ELEV N/A 24 HOUR None
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF
FILL: SAND AND GRAVEL (SP-GP)_ _
brown/dark brown 2
_ _
SAND AND GRAVEL (SP-GP)4
brown SS _ _50/6"--2.6
very dense 6
with cobbles _ _
8
_ _
SS 10 50/11"--5.9
_ _
12
CLAYSTONE _ _
grey/brown/rust 14
moderately hard CS _ _50/8"9000+13.8 119.6 38 25 97.2 2800 psf 1.1%@1000
16
_ _
18
_ _
SS 20 50/8"9000+12.4
20' BOTTOM OF BORING _ _
22
_ _
24
_ _
26
_ _
28
_ _
30
_ _
32
_ _
34
_ _
36
_ _
38
_ _
40
_ _
42
_ _
44
_ _
46
_ _
48
_ _
50
Earth Engineering Company
PENNY FLATS PHASE 2
FORT COLLINS, COLORADO
PROJECT NO: 15-01-272 DATE:SEPTEMBER 2015
LOG OF BORING B-5
RIG TYPE: CME75 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 9/10/2015 WHILE DRILLING None
AUGER TYPE: 4" CFA FINISH DATE 9/10/2015 AFTER DRILLING None
SPT HAMMER: AUTO SURFACE ELEV N/A 24 HOUR None
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF
_ _
FILL: SAND AND GRAVEL (SP-GP)2
brown/dark brown _ _
medium dense 4
clayey SS _ _10 --14.7
6
_ _
SANDY LEAN CLAY (CL)8
brown _ _
very stiff CS 10 11 9000+11.2 123.4 26 15 55.6 < 500 psf None
silty with a slight amount of gravel _ _
12
SAND AND GRAVEL (SP-GP)_ _
brown 14
medium dense SS _ _30 --1.6
with cobbles 16
_ _
18
CLAYSTONE _ _
grey/brown/rust, moderately hard CS 20 50/7"9000+8.2 122.9 4200 psf 1.6%@1000
20' BOTTOM OF BORING _ _
22
_ _
24
_ _
26
_ _
28
_ _
30
_ _
32
_ _
34
_ _
36
_ _
38
_ _
40
_ _
42
_ _
44
_ _
46
_ _
48
_ _
50
Earth Engineering Company
PENNY FLATS PHASE 2
FORT COLLINS, COLORADO
PROJECT NO: 15-01-272 DATE:SEPTEMBER 2015
LOG OF BORING B-6
RIG TYPE: CME75 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 9/10/2015 WHILE DRILLING None
AUGER TYPE: 4" CFA FINISH DATE 9/10/2015 AFTER DRILLING None
SPT HAMMER: AUTO SURFACE ELEV N/A 24 HOUR None
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF
FILL: SAND AND GRAVEL (SP-GP)_ _
brown/dark brown 2
SS _ _8 --6.3
SAND AND GRAVEL (SP-GP)4
brown CS _ _8 9000+8.2 113.8 < 500 psf None
loose 6
clayey with cobbles _ _
8
_ _
medium dense SS 10 25 --2.4
_ _
12
CLAYSTONE _ _
grey/brown/rust 14
moderately hard CS _ _50/8"9000+14.6 117.9 3200 psf 1.0%@1000
16
_ _
18
_ _
SS 20 34/9"9000+16.0
_ _
22
_ _
24
CS _ _50/6"8000 10.2 85.9 38 18 95.0 < 1000 psf None@1000
SHALE 26
grey _ _
hard 28
_ _
30
_ _
32
_ _
34
_ _
35' BOTTOM OF BORING 36
_ _
38
_ _
40
_ _
42
_ _
44
_ _
46
_ _
48
_ _
50
Earth Engineering Company
PENNY FLATS PHASE 2
FORT COLLINS, COLORADO
PROJECT NO: 15-01-272 DATE:SEPTEMBER 2015
LOG OF BORING B-7
RIG TYPE: CME75 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 9/10/2015 WHILE DRILLING None
AUGER TYPE: 4" CFA FINISH DATE 9/10/2015 AFTER DRILLING None
SPT HAMMER: AUTO SURFACE ELEV N/A 24 HOUR None
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF
FILL: SAND AND GRAVEL (SP-GP)_ _
brown/dark brown 2
loose, clayey SS _ _9 --9.0
4
SAND AND GRAVEL (SP-GP)CS _ _16 9000+5.0 127.1
brown 6
medium dense _ _
with cobbles 8
_ _
BS 10 ----2.1
_ _
12
CLAYSTONE _ _
grey/brown/rust 14
moderately hard CS _ _50/11"9000+12.7 121.3 5600 psf 2.9%@1000
16
_ _
18
_ _
SS 20 50/6"6500 11.6
20' BOTTOM OF BORING _ _
22
_ _
24
_ _
26
_ _
28
_ _
30
_ _
32
_ _
34
_ _
36
_ _
38
_ _
40
_ _
42
_ _
44
_ _
46
_ _
48
_ _
50
Earth Engineering Company
PENNY FLATS PHASE 2
FORT COLLINS, COLORADO
PROJECT NO: 15-01-272 DATE:SEPTEMBER 2015
LOG OF BORING B-8
RIG TYPE: CME75 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 9/10/2015 WHILE DRILLING None
AUGER TYPE: 4" CFA FINISH DATE 9/10/2015 AFTER DRILLING None
SPT HAMMER: AUTO SURFACE ELEV N/A 24 HOUR None
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF
FILL: SAND AND GRAVEL (SP-GP)_ _
brown/dark brown 2
clayey _ _
4
CS _ _14 9000+8.5 115.5 < 500 psf None
SANDY LEAN CLAY (CL)6
brown _ _
very stiff 8
silty with gravel _ _
SS 10 16 9000 13.2
_ _
SAND AND GRAVEL (SP-GP)12
brown _ _
medium dense 14
clayey SS _ _24 5500 11.5
16
CLAYSTONE _ _
grey/brown/rust 18
moderately hard _ _
CS 20 50/7"9000+11.0 121.6 2400 psf 0.5%@1000
20' BOTTOM OF BORING _ _
22
_ _
24
_ _
26
_ _
28
_ _
30
_ _
32
_ _
34
_ _
36
_ _
38
_ _
40
_ _
42
_ _
44
_ _
46
_ _
48
_ _
50
Earth Engineering Company
PENNY FLATS PHASE 2
FORT COLLINS, COLORADO
PROJECT NO: 15-01-272 DATE:SEPTEMBER 2015
LOG OF BORING B-9
RIG TYPE: CME75 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 9/10/2015 WHILE DRILLING None
AUGER TYPE: 4" CFA FINISH DATE 9/10/2015 AFTER DRILLING None
SPT HAMMER: AUTO SURFACE ELEV N/A 24 HOUR None
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF
FILL: SAND AND GRAVEL (SP-GP)_ _
brown/dark brown, clayey 2
SS _ _40 --28.4
SAND AND GRAVEL (SP-GP)4
brown SS _ _50 --4.2
very dense 6
with cobbles _ _
8
_ _
SS 10 50/4"--1.6
_ _
12
CLAYSTONE _ _
grey/brown/rust 14
moderately hard CS _ _50/10"9000+15.4 116.6 42 22 96.5 3400 psf 1.2%@1000
16
_ _
18
_ _
SS 20 50/11"9000+15.5
20' BOTTOM OF BORING _ _
22
_ _
24
_ _
26
_ _
28
_ _
30
_ _
32
_ _
34
_ _
36
_ _
38
_ _
40
_ _
42
_ _
44
_ _
46
_ _
48
_ _
50
Earth Engineering Company
PENNY FLATS PHASE 2
FORT COLLINS, COLORADO
PROJECT NO: 15-01-272 DATE:SEPTEMBER 2015
LOG OF BORING B-10
RIG TYPE: CME75 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 9/10/2015 WHILE DRILLING None
AUGER TYPE: 4" CFA FINISH DATE 9/10/2015 AFTER DRILLING None
SPT HAMMER: AUTO SURFACE ELEV N/A 24 HOUR None
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF
FILL: SAND AND GRAVEL (SP-GP)_ _
brown/dark brown 2
_ _
SAND AND GRAVEL (SP-GP)4
brown SS _ _42 --1.9
dense 6
with cobbles _ _
8
_ _
SS 10 22 9000+19.5
CLAYSTONE _ _
grey/brown/rust 12
moderately hard _ _
14
CS _ _48 9000+15.2 116.4 5000 psf 2.4%@1000
16
_ _
18
_ _
SS 20 50/6"--8.7
_ _
22
_ _
24
CS _ _50/4"9000+10.6 121.5 11000 psf 8.5%@1000
SHALE 26
grey _ _
moderately hard 28
_ _
30
_ _
32
_ _
34
_ _
35' BOTTOM OF BORING 36
_ _
38
_ _
40
_ _
42
_ _
44
_ _
46
_ _
48
_ _
50
Earth Engineering Company
PENNY FLATS PHASE 2
FORT COLLINS, COLORADO
PROJECT NO: 15-01-272 DATE:SEPTEMBER 2015
LOG OF BORING B-11
RIG TYPE: CME75 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 9/10/2015 WHILE DRILLING None
AUGER TYPE: 4" CFA FINISH DATE 9/10/2015 AFTER DRILLING None
SPT HAMMER: AUTO SURFACE ELEV N/A 24 HOUR None
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET)(BLOWS/FT)(PSF)(%)(PCF)LL PI (%)PRESSURE % @ 500 PSF
FILL: SAND AND GRAVEL (SP-GP)_ _
brown/dark brown 2
with a slight amount of clay SS _ _6 4500 8.4
4
SAND AND GRAVEL (SP-GP)CS _ _12 9000+7.8 122.1 25 11 41.4 < 500 psf None
brown 6
medium dense _ _
clayey with cobbles 8
_ _
very dense SS 10 50/5"--2.5
_ _
12
CLAYSTONE _ _
grey/brown/rust 14
moderately hard SS _ _50 9000+15.8
16
_ _
18
_ _
CS 20 50/7"9000+14.3 118.0 1800 psf 0.5%@1000
_ _
22
_ _
24
SS _ _50/5"--9.3
26
_ _
28
_ _
SHALE 30
grey _ _
hard 32
_ _
34
_ _
35' BOTTOM OF BORING 36
_ _
38
_ _
40
_ _
42
_ _
44
_ _
46
_ _
48
_ _
50
Earth Engineering Company
Project:
Location:
Project #:
Date:
209 Cherry Street
Fort Collins, Colorado
1232016
March 2023
Beginning Moisture: 12.1%Dry Density: 117.5 pcf Ending Moisture: 15.7%
Swell Pressure: 3800 psf % Swell @ 1000:1.7%
Sample Location:Boring 1, Sample 4, Depth 19'
Liquid Limit: - -Plasticity Index: - -% Passing #200: - -
SWELL / CONSOLIDATION TEST RESULTS
Material Description:Siltstone / Claystone Bedrock
-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 10
Pe
r
c
e
n
t
M
o
v
e
m
e
n
t
Load (TSF)
Sw
e
l
l
Co
n
s
o
l
i
d
a
t
i
o
n
Water Added
Project:
Location:
Project #:
Date:
209 Cherry Street
Fort Collins, Colorado
1232016
March 2023
Beginning Moisture: 12.4%Dry Density: 111.1 pcf Ending Moisture: 16.9%
Swell Pressure: <500 psf % Swell @ 500:None
Sample Location:Boring 2, Sample 1, Depth 4'
Liquid Limit: 28 Plasticity Index: 12 % Passing #200: 60.6%
SWELL / CONSOLIDATION TEST RESULTS
Material Description: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 10
Pe
r
c
e
n
t
M
o
v
e
m
e
n
t
Load (TSF)
Sw
e
l
l
Co
n
s
o
l
i
d
a
t
i
o
n
Water Added
Project:
Location:
Project #:
Date:
209 Cherry Street
Fort Collins, Colorado
1232016
March 2023
Beginning Moisture: 15.5%Dry Density: 110 pcf Ending Moisture: 19.2%
Swell Pressure: 1800 psf % Swell @ 1000:0.5%
Sample Location:Boring 2, Sample 4, Depth 19'
Liquid Limit: - -Plasticity Index: - -% Passing #200: - -
SWELL / CONSOLIDATION TEST RESULTS
Material Description:Siltstone / Claystone Bedrock
-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 10
Pe
r
c
e
n
t
M
o
v
e
m
e
n
t
Load (TSF)
Sw
e
l
l
Co
n
s
o
l
i
d
a
t
i
o
n
Water Added
Project:
Location:
Project #:
Date:
209 Cherry Street
Fort Collins, Colorado
1232016
March 2023
Beginning Moisture: 13.5%Dry Density: 113.8 pcf Ending Moisture: 17.2%
Swell Pressure: 4000 psf % Swell @ 1000:1.9%
Sample Location:Boring 3, Sample 4, Depth 14'
Liquid Limit: 43 Plasticity Index: 26 % Passing #200: 98.9%
SWELL / CONSOLIDATION TEST RESULTS
Material Description:Siltstone / Claystone Bedrock - classified as 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 10
Pe
r
c
e
n
t
M
o
v
e
m
e
n
t
Load (TSF)
Sw
e
l
l
Co
n
s
o
l
i
d
a
t
i
o
n
Water Added
Project:
Location:
Project #:
Date:
SWELL / CONSOLIDATION TEST RESULTS
Material Description:Clayey Sand (SC)
Sample Location:Boring 4, Sample 1, Depth 2'
Liquid Limit: 24 Plasticity Index: 11 % Passing #200: 29.3%
Beginning Moisture: 7.3%Dry Density: 106.2 pcf Ending Moisture: 15.5%
Swell Pressure: <150 psf % Swell @ 150:None
209 Cherry Street
Fort Collins, Colorado
1232016
March 2023
-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 10
Pe
r
c
e
n
t
M
o
v
e
m
e
n
t
Load (TSF)
Sw
e
l
l
Co
n
s
o
l
i
d
a
t
i
o
n
Water Added
Project:
Location:
Project #:
Date:
209 Cherry Street
Fort Collins, Colorado
1232016
March 2023
Beginning Moisture: 13.3%Dry Density: 108.9 pcf Ending Moisture: 17.5%
Swell Pressure: 3000 psf % Swell @ 1000:1.3%
Sample Location:Boring 4, Sample 4, Depth 14'
Liquid Limit: 46 Plasticity Index: 29 % Passing #200: 94.8%
SWELL / CONSOLIDATION TEST RESULTS
Material Description:Siltstone / Claystone Bedrock - classified as 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 10
Pe
r
c
e
n
t
M
o
v
e
m
e
n
t
Load (TSF)
Sw
e
l
l
Co
n
s
o
l
i
d
a
t
i
o
n
Water Added
2 1/2"(63 mm)
2"(50 mm)
1 1/2"(37.5 mm)
1"(25 mm)
3/4"(19 mm)
1/2"(12.5 mm)
3/8"(9.5 mm)
No. 4 (4.75 mm)
No. 8 (2.36 mm)
No. 10 (2 mm)
No. 16 (1.18 mm)
No. 30 (0.6 mm)
No. 40 (0.425 mm)
No. 50 (0.3 mm)
No. 100 (0.15 mm)
No. 200 (0.075 mm)
Project:209 Cherry Street
Location:Fort Collins, Colorado
Project No:1232016
Sample ID:B1 S1 4
Sample Desc.:Silty, Clayey Sand with Gravel (SC-SM)
Date:March 2023
83
78
71
47
44.0
69
64
57
54
52
100
100
100
94
87
EARTH ENGINEERING CONSULTANTS, LLC
SUMMARY OF LABORATORY TEST RESULTS
Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136)
100
Sieve Size Percent Passing
EARTH ENGINEERING CONSULTANTS, LLC
Summary of Washed Sieve Analysis Tests (ASTM C117 & C136)
Date:
Project:
Location:
Project No:
Sample ID:
Sample Desc.:
Cobble Silt or ClayGravel
Coarse Fine
Sand
Coarse Medium
March 2023
25.00 0.84 0.25
209 Cherry Street
Fort Collins, Colorado
1232016
B1 S1 4
Silty, Clayey Sand with Gravel (SC-SM)
D100 D60 D50
------
Fine
------
D30 D10 Cu CC
6"
5"
4"
3"
2.5"
2"
1.5"
1"
3/4"
1/2"
3/8"
No. 4
No. 8
No. 10
No. 16
No. 30
No. 40
No. 50
No. 100
No. 200
0
10
20
30
40
50
60
70
80
90
100
0.010.11101001000
Fi
n
e
r
b
y
W
e
i
g
h
t
(
%
)
Grain Size (mm)
Standard Sieve Size
2 1/2"(63 mm)
2"(50 mm)
1 1/2"(37.5 mm)
1"(25 mm)
3/4"(19 mm)
1/2"(12.5 mm)
3/8"(9.5 mm)
No. 4 (4.75 mm)
No. 8 (2.36 mm)
No. 10 (2 mm)
No. 16 (1.18 mm)
No. 30 (0.6 mm)
No. 40 (0.425 mm)
No. 50 (0.3 mm)
No. 100 (0.15 mm)
No. 200 (0.075 mm)
Project:209 Cherry Street
Location:Fort Collins, Colorado
Project No:1232016
Sample ID:B3 S2 4
Sample Desc.:Silty Sand with Gravel (SM)
Date:March 2023
78
71
60
26
21.2
57
49
39
35
32
100
100
100
100
87
EARTH ENGINEERING CONSULTANTS, LLC
SUMMARY OF LABORATORY TEST RESULTS
Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136)
100
Sieve Size Percent Passing
EARTH ENGINEERING CONSULTANTS, LLC
Summary of Washed Sieve Analysis Tests (ASTM C117 & C136)
Date:
Project:
Location:
Project No:
Sample ID:
Sample Desc.:
Cobble Silt or ClayGravel
Coarse Fine
Sand
Coarse Medium
March 2023
19.00 2.37 1.29
209 Cherry Street
Fort Collins, Colorado
1232016
B3 S2 4
Silty Sand with Gravel (SM)
D100 D60 D50
0.26 ---
Fine
------
D30 D10 Cu CC
6"
5"
4"
3"
2.5"
2"
1.5"
1"
3/4"
1/2"
3/8"
No. 4
No. 8
No. 10
No. 16
No. 30
No. 40
No. 50
No. 100
No. 200
0
10
20
30
40
50
60
70
80
90
100
0.010.11101001000
Fi
n
e
r
b
y
W
e
i
g
h
t
(
%
)
Grain Size (mm)
Standard Sieve Size
2 1/2"(63 mm)
2"(50 mm)
1 1/2"(37.5 mm)
1"(25 mm)
3/4"(19 mm)
1/2"(12.5 mm)
3/8"(9.5 mm)
No. 4 (4.75 mm)
No. 8 (2.36 mm)
No. 10 (2 mm)
No. 16 (1.18 mm)
No. 30 (0.6 mm)
No. 40 (0.425 mm)
No. 50 (0.3 mm)
No. 100 (0.15 mm)
No. 200 (0.075 mm)
Project:209 Cherry Street
Location:Fort Collins, Colorado
Project No:1232016
Sample ID:B3 S3 9
Sample Desc.:Silty Sand with Gravel (SM)
Date:March 2023
83
75
66
38
34.5
64
58
50
46
43
100
100
89
89
84
EARTH ENGINEERING CONSULTANTS, LLC
SUMMARY OF LABORATORY TEST RESULTS
Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136)
100
Sieve Size Percent Passing
EARTH ENGINEERING CONSULTANTS, LLC
Summary of Washed Sieve Analysis Tests (ASTM C117 & C136)
Date:
Project:
Location:
Project No:
Sample ID:
Sample Desc.:
Cobble Silt or ClayGravel
Coarse Fine
Sand
Coarse Medium
March 2023
37.50 1.50 0.62
209 Cherry Street
Fort Collins, Colorado
1232016
B3 S3 9
Silty Sand with Gravel (SM)
D100 D60 D50
------
Fine
------
D30 D10 Cu CC
6"
5"
4"
3"
2.5"
2"
1.5"
1"
3/4"
1/2"
3/8"
No. 4
No. 8
No. 10
No. 16
No. 30
No. 40
No. 50
No. 100
No. 200
0
10
20
30
40
50
60
70
80
90
100
0.010.11101001000
Fi
n
e
r
b
y
W
e
i
g
h
t
(
%
)
Grain Size (mm)
Standard Sieve Size
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 90 100 110
PL
A
S
T
I
C
I
T
Y
I
N
D
E
X
(
P
I
)
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