HomeMy WebLinkAboutReports - Soils - 06/10/2025GEOTECHNICAL SUBSURFACE EXPLORATION REPORT
PROPOSED MIXED-USE DEVELOPMNT – 360 LINDEN STREET
S/W/C OF LINDEN STREET AND WILLOW STREET
FORT COLLINS, COLORADO
EEC PROJECT NO. 1252035
Prepared for:
Realty Capital Residential
909 Lake Carolyn Parkway, Suite 150
Irving, Texas 75039
Attn: Mr. Spencer Long (Spencer@realtycapital.com)
Earth Engineering Consultants, LLC
4396 Greenfield Drive
Windsor, Colorado 80550
4396 GREENFIELD DRIVE
WINDSOR, COLORADO 80550
(970) 545 - 3908 (FAX) 663-0282
www.earth-engineering.com
June 10, 2025
Realty Capital Residential
909 Lake Carolyn Parkway, Suite 150
Irving, Texas 75039
Attn: Mr. Spencer Long (Spencer@realtycapital.com)
Re: Geotechnical Subsurface Exploration Report
Proposed Development of Property Located at 360 Linden Street
Southwest Corner of Linden Street and Willow Street – Multi-Family Development
Fort Collins, Colorado
EEC Project No. 1252035
Mr. Long:
Enclosed, herewith, are the results of the supplemental geotechnical engineering subsurface
exploration services completed by Earth Engineering Consultants, LLC (EEC) personnel for the
proposed multi-family/mixed use development project planned for design and construction at 360
Linden Street in Fort Collins, Colorado. It should be noted that in 2014, EEC completed a subsurface
exploration on this property for, at that time, the proposed “Old Elk Distillery.” For further information
and findings thereof, please refer to our “Subsurface Exploration Report” with a revised date of May
10, 2016, EEC Project No. 1142032. During our 2014 subsurface exploration, five (5) borings were
completed at select locations across the site. We have reviewed these borings, and we have relied
upon the data for the currently proposed development concept.
Based on the most recently updated plan concept of the proposed site, we now understand the
development will consist of two (2) 5-story wood-framed multi-family buildings having at grade
parking along with store front retail, and lobby/amenity space, then 4 levels above for multi-family
apartments with a total of 160 units, along with on-site pavement improvements as indicated on the
enclosed site diagram. Based on the new development plan concept, the design team and the developer
determined that a supplemental subsurface exploration should be performed to provide comprehensive
subsurface condition coverage across the entire development plan concept, as well as to update the
geotechnical recommendations for the new plan concept. The updated detailed site plan/schematic
included herein also illustrates our proposed test boring locations in comparison to those previously
completed. This supplemental subsurface exploration was completed in general accordance with our
proposal dated April 10, 2025.
In summary, the subsurface materials encountered in the four (4) supplemental exploration borings
completed on the site on May 16, 2025, generally consisted of approximately 2 to 4½ feet of existing
GEOTECHNICAL SUBSURFACE EXPLORATION REPORT
PROPOSED MIXED-USE DEVELOPMNT – 360 LINDEN STREET
S/W/C OF LINDEN STREET AND WILLOW STREET
FORT COLLINS, COLORADO
EEC PROJECT NO. 1252035
June 10, 2025
INTRODUCTION
The supplemental geotechnical subsurface exploration for the proposed 360 Linden Street mixed-use
development project in Fort Collins, Colorado has been completed. It should be noted that in 2014,
EEC completed a subsurface exploration on this property for, at that time, the proposed “Old Elk
Distillery.” For further information and findings thereof, please refer to our “Subsurface Exploration
Report” with a revised date of May 10, 2016, EEC Project No. 1142032. During our 2014
subsurface exploration, five (5) borings were completed at select locations across the site. We have
reviewed these borings, and we have relied upon the data for the currently proposed development
concept. The site was occupied in 2014 and based on the current Google Earth Imagery; the
southern portion of the site is still occupied with existing buildings. EEC borings in 2014 were
mainly within the northern portion of the site as depicted in blue font on the enclosed site plan/test
boring location diagram. Due to the increase in size and complexity of the proposed building
footprints also exhibiting greater anticipated wall and column loads, three (3) supplemental borings
were completed within the building footprints in areas accessible to our drilling equipment. A 4th
boring was also completed within the proposed pavement improvement area. This scope of services
was completed in general accordance with our signed service agreement dated April 10, 2025.
We understand the proposed project involves the design and construction of two (2) multi-family
development buildings having at grade parking along with store front retail, lobby/amenity space,
and 4 levels of wood framing multi-family apartments above with a total of 160 units, along with on-
site pavement improvements as indicated on the enclosed site diagrams. We anticipate maximum
foundations loads will be relatively low to moderate with maximum wall and column loads less than
4 klf and 100 kips, respectively. If the actual loads vary significantly from the assumed loads, we
should be consulted to verify our recommendations are consistent for the actual loads. Floor loads
are expected to be light to moderate. Pavement areas are expected to accommodate larger volumes
of light vehicles and smaller volumes of heavy-duty traffic. 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.
Earth Engineering Consultants, LLC
360 Linden Street – Fort Collins, Colorado
Proposed Mixed-Use Development
EEC Project No. 1252035
June 10, 2025
Page 2
The purpose of this report is to describe the subsurface conditions encountered in the four (4)
supplemental test borings, analyze and evaluate the field and laboratory test data and provide
geotechnical recommendations concerning design and construction of foundations, floors, and
pavements for the project.
EXPLORATION AND TESTING PROCEDURES
The supplemental boring locations were established on-site by EEC representatives and identified in
the field by pacing and estimating angles from identifiable site features. The approximate boring
locations are indicated on the attached boring location diagrams. The location of the borings should
be considered accurate only to the degree implied by the methods used to make the field
measurements.
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 in the
borings 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. Particle size
analysis and Atterberg limits tests were completed on select samples for classification and to
evaluate the quantity and plasticity of fines in the subgrades. Swell/consolidation tests were
completed on selected samples to evaluate the potential for the subgrade materials to change volume
with variation in moisture and load. Select samples were tested to determine the quantity of water-
soluble sulfates to evaluate the potential for sulfate attack on site concrete. Results of the outlined
tests are indicated herein and/or on the attached boring logs and summary sheets.
Earth Engineering Consultants, LLC
360 Linden Street – Fort Collins, Colorado
Proposed Mixed-Use Development
EEC Project No. 1252035
June 10, 2025
Page 3
As part of the testing program, all samples were examined in the laboratory by an engineer 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. Classification of the bedrock was based on visual and tactual
observation of disturbed samples and auger cuttings.
EXISTING SITE CONDITIONS
The proposed construction site was previously used by Kiefer Concrete and has various outbuildings
still present at the southern portion of the property, while the northern portion has been razed and
currently utilized as an asphalt paved parking lot. The referenced property is surrounded by
properties developed as light industrial. The property is relatively level with less than 2 to 3 feet of
relief across the sites. Photographs of the site were taken during the subsurface exploration and are
included with this report. An aerial/Google Earth image of the site is below.
Google Earth Aerial Image, April 2025
Earth Engineering Consultants, LLC
360 Linden Street – Fort Collins, Colorado
Proposed Mixed-Use Development
EEC Project No. 1252035
June 10, 2025
Page 4
SUBSURFACE CONDITIONS
To develop subsurface information for the project, four (4) supplemental soil borings were advanced
across the site to depths of approximately 10 to 30 feet below existing site grades during this
exploration. A diagram indicating the approximate boring locations is included with this report.
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.
Approximately 4 inches of a surficial gravel base course material was observed at the surface at the
boring locations. The materials below the surfacing layer generally consisted of fill and apparent fill
soils consisting of clayey sand with gravel and/or sandy lean clay extending the underlying native
sand and gravel zones. The fill and apparent fill soils generally extended to depths of approximately
4 to 7 feet below current site grades. The consistency of the fill soils was generally in the medium
dense to medium stiff.
The site apparent fill soils were underlain by medium dense to dense native sands and gravels with
silt. The granular soils were typically tan in color and contained apparent cobbles and variable sand,
gravel, and fines. The sands and gravel extended to depths of approximately 10 to 12 feet and were
underlain by sandstone/siltstone bedrock. The bedrock was typically cemented/hard and contained
zones of well cemented materials. Auger refusal was encountered in our previous 2014 boring B-3
at a depth of approximately 14 feet on apparent well cemented sandstone bedrock, however auger
refusal was not encountered during our most recent subsurface explorations. As noted on the
enclosed boring logs, interbedded well cemented sandstone lenses were encountered with increased
depth within the sandstone bedrock formation, (i.e., SPT results of less than 1 inch of penetration per
50 blows). Excavation penetrating the bedrock or cemented soils may require the use of specialized
heavy-duty equipment, together with drilling and/or controlled blasting to facilitate rock break-up
and removal. Consideration should be given to obtaining a unit price for difficult excavation in the
contract documents for the project.
Earth Engineering Consultants, LLC
360 Linden Street – Fort Collins, Colorado
Proposed Mixed-Use Development
EEC Project No. 1252035
June 10, 2025
Page 5
The stratification boundaries shown on the boring logs indicate the general locations where changes
in soil type occur. In-situ, these transitions may be gradual and less distinct. The conditions recorded
at the test boring locations may not fully represent the variations in subsurface conditions that can
occur over relatively short distances from these points.
Groundwater
Observations were made while drilling the borings to detect the presence and depth to hydrostatic
groundwater. Groundwater was encountered during drilling of the supplemental borings B-2 and B-
3 at approximate depths of 17 to 20 feet below existing site grades and not encountered in borings B-
1 and B-4 to maximum depths explored. The boreholes were backfilled the day after completion of
the drilling operation; therefore, subsequent groundwater measurements were not obtained. During
the previous subsurface explorations of the site in 2014, groundwater was encountered at depths of
11 to 13 feet.
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. In addition, zones of perched
and/or trapped water may be encountered at times throughout the year in more permeable areas
within the subgrade materials. Perched water is commonly observed in more permeable soils
overlying lower permeability bedrock. The location and amount of perched water can also vary over
time depending on variations in hydrologic conditions and other conditions not apparent at the time
of this report.
Seismic
The subsurface conditions generally consist of up to 10 to feet of intermittent sandy lean clay/clayey
sand subsoils transitioning to the sand and gravel strata, which extended to the underlying bedrock at
depths of approximately 10 to 2 feet below site grades. In accordance with ASCE 7 and considering
International Building Code, we believe this site would have a Seismic Site Classification of C.
Water Soluble Sulfates (SO4)
Results of water-soluble sulfate testing on selected samples obtained from the subsurface exploration
of the overburden subsoils and of the underlying bedrock indicated sulfate (S04) contents of 0.02
percent of soil by weight. ACI 318-19, Section 19.3.1 indicates the site soils have a low risk of
sulfate attack on Portland cement concrete. Considering the laboratory test results and ACI 318-19,
Earth Engineering Consultants, LLC
360 Linden Street – Fort Collins, Colorado
Proposed Mixed-Use Development
EEC Project No. 1252035
June 10, 2025
Page 6
we recommend that site concrete be designed with a sulfate exposure class of S0. Special
requirements regarding the cementitious materials can be found in Table 19.3.2.1 of the ACI code.
Swell – Consolidation Test Results
The swell-consolidation test is performed to evaluate the swell or collapse potential of soils and/or
bedrock to assist in determining foundation, floor slab and pavement design criteria. In this test,
relatively intact 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 exploration and the previous exploration at this site, we conducted five (5) swell-
consolidation tests on relatively intact soil samples obtained at various intervals/depths. The swell
index values for the in-situ soil samples analyzed indicated a slight tendency to hydro-compact when
inundated with water. The majority of the swell-consolidation samples were of the upper fill
material, which as previously indicated we are recommending removing and replacement as
moisture conditioned, engineered/controlled fill material.
ANALYSIS AND RECOMMENDATIONS
General Considerations
Precautions will be required in the design and construction of the new building(s) and any new
pavements to address the existing fill material, the removal/excavation of cobbles at increased depths,
penetration of the underlying well cemented sandstone bedrock lenses, and shoring/protection of
adjacent properties during excavation for the proposed basement level of site.
It is anticipated that excavations for the proposed construction can be accomplished with
conventional earthmoving equipment. However, if excavations penetrating the well-cemented
sandstone bedrock are required, the use of specialized heavy-duty equipment such as a rock hammer
or core barrel to achieve final design elevations may be necessary. Consideration should be given to
obtaining a unit price for difficult excavation in the contract documents for the project.
Earth Engineering Consultants, LLC
360 Linden Street – Fort Collins, Colorado
Proposed Mixed-Use Development
EEC Project No. 1252035
June 10, 2025
Page 7
Depending upon the depth and proximity to the property line of any lower level construction, a shoring
plan may be necessary to protect the adjacent sidewall slopes. The project design team should use the
subsurface information provided herein to properly design a mechanism for shoring protection. 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 concepts.
Site Preparation
Final site grades were not available at the time of this report. We are basing the recommendations in
this report on an assumption that cuts and fills of less than 2 to 3 feet will be necessary to achieve
design grades. All of the existing fill material should be removed in the new building areas,
including adjacent flatwork areas. The majority of the in-place fill material appears suitable for
reuse as “moisture conditioned/engineered fill material.” In-place fill materials could probably
remain in pavement and landscape areas with an acknowledgement that some future settlement could
occur in the remaining fill areas and that future settlement could result in differential movements in
the overlying improvements.
After stripping, over-excavating as necessary and completing all cuts, and prior to placement of any
fill material or site improvements, we recommend the exposed subsoils be scarified to a minimum
depth of 9-inches, adjusted in moisture content to within ±3% of standard Proctor optimum moisture
content, and compacted to at least 98% of the material's standard Proctor maximum dry density as
determined in accordance with ASTM Specification D698. If cuts extend into zones of cinder and/or
ash fill that was encountered during our 2014 subsurface exploration, scarification and recompaction
would generally not be possible. Removal and replacement of unstable zones of cinder/ash fill may
be necessary in near surface subgrades in all areas not specifically designated as landscaping.
Fill soils required to develop the building, pavement, and site subgrades, after the initial subgrade
zone (i.e., the layer beneath any over-excavation requirements) has been stabilized, should consist of
approved, low-volume-change materials which are free from organic matter and debris. We
recommend structural fill materials, similar to that of a CDOT Class 5, 6, or 7 aggregate base course
(ABC) material, be placed and compacted within the building footprint. Sandy lean clay to
silty/clayey on-site fill material and/or underlying native sands and gravels excluding cobble sized
material could be used for fill in these areas. We recommend fill materials be placed in loose lifts
not to exceed 9 inches thick and adjusted in moisture content to within ± 3% of optimum moisture
Earth Engineering Consultants, LLC
360 Linden Street – Fort Collins, Colorado
Proposed Mixed-Use Development
EEC Project No. 1252035
June 10, 2025
Page 8
content and compacted to at least 98% of the material’s maximum dry density as determined in
accordance with ASTM Specification D698, the standard Proctor procedure.
Care should be exercised after preparation of the subgrades to avoid disturbing the subgrade
materials. Positive drainage should be developed away from the structure to avoid wetting of
subgrade materials. Subgrade materials becoming wet subsequent to construction of the site
structure can result in unacceptable performance.
ANALYSIS AND RECOMMENDATIONS
Foundation Systems – General Considerations
The existing fill material encountered across the site at various depths, (please refer to the previously
completed borings logs in 2014 as well as the current boring logs completed in May of 2025 for more
detail), will require particular attention in the design and construction to reduce the amount of
movement due to the variability of the materials characteristics. The following foundation systems
were evaluated for use on the site.
Conventional type spread footings bearing on the native sand and gravel zone or extended into
the underlying bedrock formation or supported on newly placed and compacted imported
structural fill material that extends to the undisturbed native sand and gravel strata. All
foundations and floor slab should bear on properly prepared fill material to minimize the
potential for differential movement of dissimilar materials.
Rammed Aggregate Piers – an alternative approach versus the removal and replacement of the
existing fill material would be to support the building (s) on conventional spread footings that
are supported by the use of aggregate piers (RAPs) that extended to the underlying bedrock
formation.
Foundations – Conventional Type Spread Footings
Based on results of field borings and laboratory testing as outlined in this report, it is our opinion the
proposed building(s) could be supported on conventional type spread footing foundations bearing on
the native granular stratum, on a zone of engineered fill material extending to the native granular
soils, or extending to the underlying sandstone bedrock. In no case should any foundation system be
Earth Engineering Consultants, LLC
360 Linden Street – Fort Collins, Colorado
Proposed Mixed-Use Development
EEC Project No. 1252035
June 10, 2025
Page 9
placed on the existing on-site fill material. Footings bearing on approved native granular subsoils or
on imported structural fill material, (similar to that of a CDOT Class 5, 6 or 7 aggregate base course
material), extended to the granular strata could be designed for a maximum net allowable total load
soil bearing pressure of 2,500 psf. Footing foundations extending to the sandstone bedrock could be
designed using a net allowable total load soil bearing pressure not to exceed 5,000 psf. The net
bearing pressure refers to the pressure at foundation bearing level in excess of the minimum
surrounding overburden pressure. Total load includes full dead and live loads. A minimum dead
load pressure would not be required in the low swell potential subsoils and bedrock.
If fill material is required to achieve foundation bearing elevations, the engineered fill material
should consist of structural fill similar to that of a CDOT Class 5, 6, or 7 ABC material, placed in
uniform lifts, properly moisture conditioned, and compacted to at least 98% of standard Proctor
density (ASTM D698). Overexcavation for placement of the structural fill should extend to the
native granular subsoils and should extend at least eight (8) inches beyond the edges of the
foundations for each 12 inches of structural fill placed beneath the footings.
Exterior footings and foundations in unheated areas must be protected from frost action. Footings
should be proportioned to reduce differential foundation movement. Proportioning on the basis of
equal total settlement is recommended; however, proportioning to relative constant dead-load
pressure will also reduce differential settlement between adjacent footings. Total settlement
resulting from the assumed structural loads is estimated to be on the order of 1 inch or less.
Differential settlement is estimated to be on the order of 1/2 of the estimated total settlement.
Additional foundation movements could occur if water from any source infiltrates the foundation
soils; therefore, proper drainage should be provided in the final design and during construction.
Care should be taken during construction to see that the footing foundations are supported on
similar, suitable strength native subsoils, approved fill material or suitable sandstone bedrock. Extra
care should be taken in evaluating the in-place soils with potentially variable depths of in-place fill
across the site. If unacceptable materials are encountered at the time of construction, it may be
necessary to extend the footing foundations to bear below the unacceptable materials or removal and
replacement of a portion, or all of the unacceptable materials may be required. Those conditions can
best be evaluated in open excavations at the time of construction.
No unusual problems are anticipated in completing the excavation required for construction of the
footing foundations. Care should be taken during construction to avoid disturbing the foundation
Earth Engineering Consultants, LLC
360 Linden Street – Fort Collins, Colorado
Proposed Mixed-Use Development
EEC Project No. 1252035
June 10, 2025
Page 10
bearing materials. Materials which are loosened or disturbed by the construction activities or
materials which become dry and desiccated or wet and softened should be removed and replaced
prior to placement of foundation concrete.
Rammed Aggregate Piers
As an alternative to over excavation, rammed aggregate piers (RAP) could be considered for support
of spread footings. RAP systems are ground improvement technologies that create a densified
column of aggregate surrounded by a stiffened matrix soil. These foundation systems are ideal for
nearly all soil types and design applications. There are “drill and fill” solutions for non-caving soils
(silts and clays) and there are “displacement” solutions for caving soils (sands below the
groundwater table). The end result is a stiffened mass of soil that provides improved bearing and
excellent settlement control for support of spread footings and slabs-on-grade. A RAP system
generally consists of driving aggregate into the supporting subgrade to develop aggregate piers or
columns. The rammed aggregate piers would provide support capacity for the overlying spread
footings while also improving the adjacent subgrades. Typical maximum net allowable bearing
pressures with the use of RAP range from 4,000 to 8,000 psf or even higher can be developed with
this system; however, project-specific design bearing pressures should be provided by the installer.
To develop pier capacity, we recommend that the rammed aggregate piers extend through the clay to
bear on the dense to very dense sand and gravel or extend into the bedrock formation. Rammed
aggregate piers would likely be installed after completion of any site cuts and fills and any over-
excavation and replacement concepts. Although we have experienced the use of RAP for sites
exhibiting similar fill material layers and the RAPs were installed beneath the foundation and floor
slabs to provide adequate support with the fill material remaining in-place, the RAP design engineer
should be consulted if this approach is selected, and qualified rammed aggregate pier installer should
provide the necessary design recommendations for the piers.
Floor Slabs and Exterior Flatwork
Depending upon the foundation system approach, (i.e., the use of spread footing bearing on native
subsoils or engineered fill material, versus on RAPs), will determine if the entire building footprint is
over-ex-excavated to the native sand and gravel zones. If conventional spread footings placed on
the native subsoils and/or on engineered fill material is selected, then the removal of all fill material
within the building will be required to take place. The floor slab will then be placed on fill material
as described in the Site Preparation section of this report. Floors supported on a zone of approved
Earth Engineering Consultants, LLC
360 Linden Street – Fort Collins, Colorado
Proposed Mixed-Use Development
EEC Project No. 1252035
June 10, 2025
Page 11
prepared and compacted fill material could be designed using a subgrade modulus (k-value) of 150
pci. If granular structural fill material such as a CDOT Class 5, 6, or 7 ABC is utilized, then a
subgrade modulus of 200 pci could be used.
Care should be taken after the preparation of the subgrades to avoid disturbing the subgrade
materials. Materials which are loosened or materials which become dry and desiccated or wet and
softened should be removed and replaced prior to placement of the overlying floor slabs. Care
should be taken to maintain proper moisture contents in the subgrade soils prior to placement of any
overlying improvements. An underslab gravel layer or thin leveling course could be used
underneath the concrete floor slabs to provide a leveling course for the concrete placement.
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. Special framing details should be provided at door jams and
frames within partition walls to avoid potential distortion. Partition walls should be
isolated from suspended ceilings.
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 on-site materials.
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.
Care should be exercised after development of the floor slab subgrades to prevent disturbance of the
in-place materials. Subgrade soils which are loosened or disturbed by construction activities or soils
Earth Engineering Consultants, LLC
360 Linden Street – Fort Collins, Colorado
Proposed Mixed-Use Development
EEC Project No. 1252035
June 10, 2025
Page 12
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.
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. The site soils or
similar could be used. Backfill soils should 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. Care should be taken when backfilling against laterally
unrestrained walls to minimize unbalanced lateral pressures.
Lateral Earth Pressures
Portions of the new structures 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 III 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 cohesive subsoils or import granular material. 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
Earth Engineering Consultants, LLC
360 Linden Street – Fort Collins, Colorado
Proposed Mixed-Use Development
EEC Project No. 1252035
June 10, 2025
Page 13
create additional loads on below grade walls. Those situations should be designed on an individual
basis.
Table III - Lateral Earth Pressures
Soil Type On-Site Overburden Cohesive
Soils
Imported Medium Dense
Granular Material
Wet Unit Weight (psf) 120 135
Saturated Unit Weight (psf) 135 140
Friction Angle (φ) – (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
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. 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.
Earth Engineering Consultants, LLC
360 Linden Street – Fort Collins, Colorado
Proposed Mixed-Use Development
EEC Project No. 1252035
June 10, 2025
Page 14
Pavement
Subgrades below the site pavements should be prepared as outlined in the Site Preparation section,
with at least 2 feet of over-excavation, moisture treatment, and re-compaction. Once site grades are
established, pavement subgrades should be proof rolled to identify any soft or unstable areas, which
should then be removed and replaced, reworked in place. Consideration should be given to an over-
excavation and replacement approach with a minimum 2-foot zone of imported structural ill
material. Additional recommendations can be provided at the time of proof roll observation, if
warranted.
We understand that the new site pavements will be private. Paved areas will include parking and
access drives for light to medium duty passenger vehicles (Light Duty) and occasional heavier
delivery and/or truck traffic (Heavy Duty). The project design team will need to decide which of the
areas will receive which type of traffic. If all areas are to receive Heavy Duty traffic, the pavement
should be designed based on our Heavy-Duty recommendations.
For Light-Duty and Heavy-Duty conditions, equivalent daily load applications (EDLA) values of 7
and 25 were assumed in the design, respectively. A conservative R-value of 10 was assumed for the
pavement subgrade considering the site soils encountered during the exploration. The pavements are
based on a 20-year pavement design life. Asphalt pavement may show rutting or distress in areas of
frequent turning or stopping in the delivery and heavy truck areas and concrete pavement sections
should be considered in those areas. Our recommendations for minimum pavement sections are
provided below in Table IV. The recommended pavement sections are considered minimum.
Periodic maintenance is necessary to realize the maximum lifetime of a pavement and should be
expected.
Earth Engineering Consultants, LLC
360 Linden Street – Fort Collins, Colorado
Proposed Mixed-Use Development
EEC Project No. 1252035
June 10, 2025
Page 15
Table IV: Recommended minimum pavement sections for assumed traffic conditions.
Design Information Light Duty Heavy Duty
EDLA
18-Kip ESALs
Reliability (%)
Resilient Modulus (psi) – R-Value - 10
Serviceability Loss (psi)
7
51,100
75
6482
2.2
25
182,500
75
6482
2.2
Design Structure Number 2.09 2.58
Option 1: Asphalt
Hot Mix Asphalt
Aggregate Base
4"
6"
5"
6"
Option 2: Concrete (Non-reinforced)
Portland Cement Concrete
6"
7"
Aggregate base should meet CDOT Class 5 or Class 6 aggregate base. Recycled asphalt (RAP) and
recycled concrete (RCP) pavement materials are acceptable as long as they can meet Class 5 or Class
6 gradation specifications. Base should have an R-value (ASTM Specification D2844) of at least 70,
and a plastic index no greater than 6 percent (ASTM Specification D4318). Those materials should
be placed in loose lifts not to exceed 9 inches, adjusted in moisture content, and compacted to
achieve a minimum of 95% of MODIFIED Proctor maximum dry density (ASTM Specification
D1557).
Asphalt pavements should be graded as S or SX and prepared with 75 gyrations using a Superpave
gyratory compactor in accordance with CDOT standards. Grading SX is recommended for surface
course of the pavement. The asphalt mix should consist of PG 58-28 or PG 64-22 asphalt binder;
however, if the mix contains reclaimed asphalt pavement (RAP) material, we recommend using PG
58-28 binder. The hot mix asphalt should be compacted to achieve 92 to 96% of the mix’s
theoretical maximum specific gravity (Rice Value).
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.
Other Considerations
Positive drainage should be developed away from the structures 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 adjacent to the buildings to avoid features
Earth Engineering Consultants, LLC
360 Linden Street – Fort Collins, Colorado
Proposed Mixed-Use Development
EEC Project No. 1252035
June 10, 2025
Page 16
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 buildings and parking areas. Spray heads should be designed
not to spray water on or immediately adjacent to the structures or site pavements. Roof drains
should be designed to discharge at least 5 feet away from the structures and away from the pavement
areas.
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 Realty Capital Residential, and/or assignee,
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 90 100 110
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
360 LINDEN STREET
FORT COLLINS, COLORADO
EEC PROJECT NO. 1252035
MAY 2025
360 Linden Street
Fort Collins, Colorado
Log of Soil Boring
B-1
Page 1 of 1
Project Number:1252035
Drilling Firm:Quality
Rig Type:CME-55
Drilling Method:Auger
Logged By:DG
Date Drilled:05/16/2025
Boring Elevation:N/A
Boring Depth:25.5'
Lat / long:
,
At time of drilling:None After Drilling:N/A
De
p
t
h
(
f
t
)
5
10
15
20
25
30
35
Gr
a
p
h
i
c
L
o
g
Visual Classification and Remarks
0.3
4.0
12.0
25.5
GRAVEL LOT
SANDY LEAN CLAY - FILL (CL)
brown
SILTY SAND WITH GRAVEL (SM)
dense
SANDSTONE
brown, olive, gray
well cemented, hard
Interbedded cemented lenses with
depth
Samples
Sa
m
p
l
e
T
y
p
e
Modified
CA
SS
Modified
CA
SS
SS
Sa
m
p
l
e
G
r
a
p
h
i
c
De
p
t
h
o
f
S
a
m
p
l
e
(
ft
)
14 ft
19 ft
4 ft
24 ft
9 ft
N-
V
a
l
u
e
43
50
50/1"
50/0.75"
50/3"
Lab
Un
c
o
n
f
i
n
e
d
S
t
r
e
n
g
t
h
(P
S
F
)
Mo
i
s
t
u
r
e
C
o
n
t
e
n
t
(
%
)
4.3
2.4
11.2
8.2
15.7
Dr
y
D
e
n
s
i
t
y
(
P
C
F
)
119.0
Li
q
u
i
d
L
i
m
i
t
Pl
a
s
t
i
c
i
t
y
I
n
d
e
x
%
Fi
n
e
s
12.2
Lo
a
d
i
n
g
S
t
r
e
s
s
(
P
S
F
)
%
Sw
e
l
l
Sw
e
l
l
P
r
e
s
s
u
r
e
(
P
S
F
)
Su
l
f
a
t
e
(
%
)
0.02
0.02
RE
M
A
R
K
S
1. Unconfined strength was estimated using a calibrated hand penetrometer.
2. Latitude, longitude, and elevation were taken from Google Earth and should be considered approximate.
Graphics Legend
Gravel Lot
CL
Sandstone
SM
Modified CA - Modified
California Sampler
SS - Small Split Spoon
DRAFT
Earth Engineering Consultants, LLC | 4396 Greenfield Drive | Windsor, Colorado | 970-545-3908 | www.earth-engineering.com
360 Linden Street
Fort Collins, Colorado
Log of Soil Boring
B-2
Page 1 of 1
Project Number:1252035
Drilling Firm:Quality
Rig Type:CME-55
Drilling Method:Auger
Logged By:DG
Date Drilled:05/16/2025
Boring Elevation:N/A
Boring Depth:30.5'
Lat / long:
,
At time of drilling:17'After Drilling:N/A
De
p
t
h
(
f
t
)
5
10
15
20
25
30
35
Gr
a
p
h
i
c
L
o
g
Visual Classification and Remarks
7.0
10.5
30.5
SILTY, CLAYEY SAND - FILL (SC)
brown
medium dense
SAND WITH GRAVEL (SP-GP)
brown
dense
SANDSTONE
brown, gray, rust
well cemented, hard
Interbedded cemented lenses with
depth
Samples
Sa
m
p
l
e
T
y
p
e
SS
Modified
CA
SS
Modified
CA
SS
Modified
CA
SS
Sa
m
p
l
e
G
r
a
p
h
i
c
De
p
t
h
o
f
S
a
m
p
l
e
(
ft
)
24 ft
29 ft
14 ft
4 ft
19 ft
2 ft
9 ft
N-
V
a
l
u
e
16
7
40
50/7"
50/4"
50/1.25"
50/0.5"
Lab
Un
c
o
n
f
i
n
e
d
S
t
r
e
n
g
t
h
(P
S
F
)
3000
4000
3000
Mo
i
s
t
u
r
e
C
o
n
t
e
n
t
(
%
)
8.5
7.2
1.9
15.3
18.0
8.7
20.9
Dr
y
D
e
n
s
i
t
y
(
P
C
F
)
101.5
104.4
Li
q
u
i
d
L
i
m
i
t
NV
Pl
a
s
t
i
c
i
t
y
I
n
d
e
x
NP
%
Fi
n
e
s
11.8
50.7
Lo
a
d
i
n
g
S
t
r
e
s
s
(
P
S
F
)
500
1000
%
Sw
e
l
l
0.0
0.0
Sw
e
l
l
P
r
e
s
s
u
r
e
(
P
S
F
)
0
0
Su
l
f
a
t
e
(
%
)
RE
M
A
R
K
S
1. Unconfined strength was estimated using a calibrated hand penetrometer.
2. Latitude, longitude, and elevation were taken from Google Earth and should be considered approximate.
Graphics Legend
Water at Time of Drilling
(ATD)
SP-GP
SC
Sandstone
Modified CA - Modified
California Sampler
SS - Small Split Spoon
DRAFT
Earth Engineering Consultants, LLC | 4396 Greenfield Drive | Windsor, Colorado | 970-545-3908 | www.earth-engineering.com
360 Linden Street
Fort Collins, Colorado
Log of Soil Boring
B-3
Page 1 of 1
Project Number:1252035
Drilling Firm:Quality
Rig Type:CME-55
Drilling Method:Auger
Logged By:DG
Date Drilled:05/16/2025
Boring Elevation:N/A
Boring Depth:25.0'
Lat / long:
,
At time of drilling:20'After Drilling:N/A
De
p
t
h
(
f
t
)
5
10
15
20
25
30
35
Gr
a
p
h
i
c
L
o
g
Visual Classification and Remarks
0.6
6.0
12.0
25.0
GRAVEL LOT
CLAYEY SAND (SC)
brown
loose
SAND WITH SILT AND GRAVEL
(SP-SM)
brown
very dense
SANDSTONE
brown, gray, rust
well cemented, hard
Interbedded cemented lenses with
depth
Samples
Sa
m
p
l
e
T
y
p
e
Modified
CA
SS
Modified
CA
SS
Modified
CA
Sa
m
p
l
e
G
r
a
p
h
i
c
De
p
t
h
o
f
S
a
m
p
l
e
(
ft
)
9 ft
19 ft
4 ft
14 ft
24 ft
N-
V
a
l
u
e
9
50/6.5"
50/7"
50/10"
50/3"
Lab
Un
c
o
n
f
i
n
e
d
S
t
r
e
n
g
t
h
(P
S
F
)
4000
9000
7000
9000
Mo
i
s
t
u
r
e
C
o
n
t
e
n
t
(
%
)
9.9
2.5
11.7
14.3
12.6
Dr
y
D
e
n
s
i
t
y
(
P
C
F
)
108.3
120.3
Li
q
u
i
d
L
i
m
i
t
20
Pl
a
s
t
i
c
i
t
y
I
n
d
e
x
7
%
Fi
n
e
s
35.2
7.7
Lo
a
d
i
n
g
S
t
r
e
s
s
(
P
S
F
)
500
%
Sw
e
l
l
0.0
Sw
e
l
l
P
r
e
s
s
u
r
e
(
P
S
F
)
0
Su
l
f
a
t
e
(
%
)
RE
M
A
R
K
S
1. Unconfined strength was estimated using a calibrated hand penetrometer.
2. Latitude, longitude, and elevation were taken from Google Earth and should be considered approximate.
Graphics Legend
Water at Time of Drilling (ATD)
SP-SM
SC
Gravel Lot
Sandstone
SS - Small Split Spoon
Modified CA - Modified California Sampler
DRAFT
Earth Engineering Consultants, LLC | 4396 Greenfield Drive | Windsor, Colorado | 970-545-3908 | www.earth-engineering.com
360 Linden Street
Fort Collins, Colorado
Log of Soil Boring
B-4
Page 1 of 1
Project Number:1252035
Drilling Firm:Quality
Rig Type:CME-55
Drilling Method:Auger
Logged By:DG
Date Drilled:05/16/2025
Boring Elevation:N/A
Boring Depth:10.5'
Lat / long:
,
At time of drilling:None After Drilling:N/A
De
p
t
h
(
f
t
)
5
10
15
20
25
30
35
Gr
a
p
h
i
c
L
o
g
Visual Classification and Remarks
6.0
10.0
10.5
SANDY LEAN CLAY - FILL (CL)
brown
medium stiff
SAND WITH GRAVEL (SP-GP)
brown
loose to medium dense
SANDSTONE
brown, rust
Samples
Sa
m
p
l
e
T
y
p
e
Modified
CA
SS
SS
Sa
m
p
l
e
G
r
a
p
h
i
c
De
p
t
h
o
f
S
a
m
p
l
e
(
ft
)
9 ft
2 ft
4 ft
N-
V
a
l
u
e
8
4
28
Lab
Un
c
o
n
f
i
n
e
d
S
t
r
e
n
g
t
h
(P
S
F
)
1000
Mo
i
s
t
u
r
e
C
o
n
t
e
n
t
(
%
)
3.6
7.3
9.3
Dr
y
D
e
n
s
i
t
y
(
P
C
F
)
111.2
Li
q
u
i
d
L
i
m
i
t
21
Pl
a
s
t
i
c
i
t
y
I
n
d
e
x
6
%
Fi
n
e
s
19.1
Lo
a
d
i
n
g
S
t
r
e
s
s
(
P
S
F
)
150
%
Sw
e
l
l
0.0
Sw
e
l
l
P
r
e
s
s
u
r
e
(
P
S
F
)
0
Su
l
f
a
t
e
(
%
)
RE
M
A
R
K
S
1. Unconfined strength was estimated using a calibrated hand penetrometer.
2. Latitude, longitude, and elevation were taken from Google Earth and should be considered approximate.
Graphics Legend
SP-GP
Sandstone
CL
SS - Small Split Spoon
Modified CA - Modified
California Sampler
DRAFT
Earth Engineering Consultants, LLC | 4396 Greenfield Drive | Windsor, Colorado | 970-545-3908 | www.earth-engineering.com
Project:
Location:
Project #:
Date:
360 Linden Street
Fort Collins, Colorado
1252035
May 2025
Beginning Moisture: 7.2%Dry Density: 98.1 pcf Ending Moisture: 19.7%
Swell Pressure: <500 psf % Swell @ 500:None
Sample Location:Boring 2, Sample 2, Depth 4'
Liquid Limit: NL Plasticity Index: NP % Passing #200: 11.8%
SWELL / CONSOLIDATION TEST RESULTS
Material Description:Silty, Clayey Sand (SC-SM) - Fill Material
-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
el
l
Co
n
s
o
l
i
d
a
t
i
o
Water Added
Project:
Location:
Project #:
Date:
360 Linden Street
Fort Collins, Colorado
1252035
May 2025
Beginning Moisture: 15.3%Dry Density: 100.1 pcf Ending Moisture: 20.5%
Swell Pressure: <1000 psf % Swell @ 1000:None
Sample Location:Boring 2, Sample 4, Depth 14'
Liquid Limit: - -Plasticity Index: - -% Passing #200: 50.7%
SWELL / CONSOLIDATION TEST RESULTS
Material Description:Sandstone/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
el
l
Co
n
s
o
l
i
d
a
t
i
o
Water Added
Project:
Location:
Project #:
Date:
360 Linden Street
Fort Collins, Colorado
1252035
May 2025
Beginning Moisture: 9.9%Dry Density: 105.7 pcf Ending Moisture: 17.3%
Swell Pressure: <500 psf % Swell @ 500:None
Sample Location:Boring 3, Sample 1, Depth 4'
Liquid Limit: 20 Plasticity Index: 7 % Passing #200: 35.2%
SWELL / CONSOLIDATION TEST RESULTS
Material Description:Silty, Clayey Sand (SC-SM) - Fill Material
-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
el
l
Co
n
s
o
l
i
d
a
t
i
o
Water Added
Project:
Location:
Project #:
Date:
360 Linden Street
Fort Collins, Colorado
1252035
May 2025
Beginning Moisture: 3.6%Dry Density: 97.9 pcf Ending Moisture: 20.0%
Swell Pressure: <150 psf % Swell @ 150:None
Sample Location:Boring 4, Sample 1, Depth 2'
Liquid Limit: 21 Plasticity Index: 6 % Passing #200: 19.1%
SWELL / CONSOLIDATION TEST RESULTS
Material Description:Silty, Clayey Sand (SC-SM) - Fill Material
-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
el
l
Co
n
s
o
l
i
d
a
t
i
o
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:360 Linden Street
Location:Fort Collins, Colorado
Project No:1252035
Sample ID:B1 S2 9
Sample Desc.:Silty Sand with Gravel (SM)
Date:May 2025
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
100
100
87
87
78
77
73
68
19
12.2
66
60
49
42
34
0.26 ---
Fine
------
D30 D10 Cu CC
May 2025
37.50 1.17 0.66
360 Linden Street
Fort Collins, Colorado
1252035
B1 S2 9
Silty Sand with Gravel (SM)
D100 D60 D50
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
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:360 Linden Street
Location:Fort Collins, Colorado
Project No:1252035
Sample ID:B3 S2 9
Sample Desc.:Poorly Graded Sand with Silt and Gravel (SP-SM)
Date:May 2025
77
67
54
12
7.7
52
43
31
25
20
100
100
92
92
86
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
May 2025
37.50 3.43 1.84
360 Linden Street
Fort Collins, Colorado
1252035
B3 S2 9
Poorly Graded Sand with Silt and Gravel (SP-SM)
D100 D60 D50
0.58 0.11
Fine
30.53 0.86
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