HomeMy WebLinkAboutWILLOW STREET RESIDENCES - FDP - FDP180027 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTSUBSURFACE EXPLORATION REPORT
PROPOSED 232 WILLOW STREET 5-STORY MIXED USE DEVELOPMENT
FORT COLLINS, COLORADO
EEC PROJECT NO. 1182008
Prepared for:
CA Ventures
130 East Randolph Street - Suite 2100
Chicago, Illinois 60601
Attn: Mr. Ryan Sadowy (RSadowy@ca-ventures.com)
Prepared by:
Earth Engineering Consultants, LLC
4396 Greenfield Drive
Windsor, Colorado 80550
4396 GREENFIELD DRIVE
WINDSOR, COLORADO 80550
(970) 545-3908 FAX (970) 663-0282
February 23, 2018
CA Ventures
130 East Randolph Street - Suite 2100
Chicago, Illinois 60601
Attn: Mr. Ryan Sadowy (RSadowy@ca-ventures.com)
Re: Subsurface Exploration Report
Proposed 232 Willow Street 5-Story Mixed Use Development Project
Fort Collins, Colorado
EEC Project No. 1182008
Mr. Sadowy:
Enclosed, herewith, are the results of the geotechnical subsurface exploration completed by Earth
Engineering Consultants, LLC (EEC) for the referenced project. For this exploration, nine (9)
soil borings were drilled on January 31, 2018 at preselect locations accessible to our drilling
equipment within the footprint of the proposed approximate 156,650 gross square foot (GSF), or
approximately 31,300 SF per level, in plan-line dimensions, 5-story mixed use development
project with an at grade parking structure and retail space on main level, and 4-stories of
residential/apartments above. The site for the planned construction is at 232 Willow Street within
the River Downtown Redevelopment (RDR) District in Old Town Fort Collins, Colorado. The
borings were extended to approximate depths of 15 to 30 feet below present site grades. This
study was completed in general accordance with our updated/revised proposal dated January 24,
2018.
In summary, the subsurface soils encountered, in general, consisted of a surficial layer of
aggregate base course (ABC) and/or sandy lean clay to clayey/silty sand with variable amounts
of gravel which extended to the underlying sand and gravel with occasional cobbles at depths of
approximately 4 to 6 feet below existing site grades. Portions of the near surface soils were
identified as fill material on the order of 1 to 6 feet below existing site grades. The sand and
gravel with varying fines and intermittent cobbles extended to the bedrock formation below.
Siltstone/sandstone bedrock was encountered in each of the borings at depths of approximately
11 to 14 feet below existing site grades and extended to the depths explored, approximately 15 to
30 feet. At the time of drilling free water was not encountered across the site to the depths
explored.
SUBSURFACE EXPLORATION REPORT
PROPOSED 232 WILLOW STREET 5-STORY MIXED USE DEVELOPMENT
FORT COLLINS, COLORADO
EEC PROJECT NO. 1182008
February 23, 2018
INTRODUCTION
The subsurface exploration for the proposed 5-story mixed use building planned for construction at
232 Willow Street in Fort Collins, Colorado, has been completed. For this exploration, nine (9) soil
borings extending to depths of approximately 15 to 30 feet below present site grades were drilled on
January 31, 2018 at pre-selected locations within the proposed development area. Boring B-10 was
not drilled at the request of Paragon Consulting Group (PCG) due to existing/on-going
environmental concerns and utilities in the general vicinity. For additional information regarding
environmental concerns consult PCG. Additional Geotech services could be provided at boring B-
10 at the approval/direction of PCG. This exploration was completed in general accordance with our
updated/revised proposal dated January 24, 2018.
We understand for this project an approximate 156,650 gross square foot (GSF), or approximately
31,300 square foot (SF) per level in plan-line dimension, 5-story mixed use building with at grade
parking and retail space and 4-stories of residential/apartment above and associated site pavements.
Currently the site is occupied by an existing metal frame single-story storage type warehouse
building towards the north end of the site with surrounding areas having gravel surfacing. The
existing building on the southern portion of the site will be demolished prior to construction of the
new building. Foundation loads for the new structure are estimated to be moderate to high with wall
and column loads on the order of 1 to 5 klf and 25 to 350 kips, respectively. Floor loads are
expected to be light. Minor grade changes are expected to develop final site grades.
The purpose of this report is to describe the subsurface conditions encountered in the test borings,
analyze and evaluate the test data and provide geotechnical recommendations concerning design and
construction of foundations and support of floor slabs for the new building and site pavements.
EXPLORATION AND TESTING PROCEDURES
The boring locations were established in the field by representatives from Earth Engineering
Consultants, LLC (EEC) by pacing and estimating angles from identifiable site features. The
borings were positioned in locations accessible to our drilling equipment. Those approximate boring
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February 23, 2018
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locations are indicated on the attached boring location diagram. The locations of the borings should
be considered accurate only to the degree implied by the methods used to make the field
measurements. Photographs of the site taken at the time of drilling are included with this report.
The test borings were completed using a truck mounted, CME-75 drill rig equipped with a hydraulic
head employed in drilling and sampling operations. The boreholes were advanced using 4-inch
nominal diameter continuous flight augers. Samples of the subsurface materials encountered were
obtained using split barrel and California barrel sampling procedures in general accordance with
ASTM Specifications D1586 and D3550, respectively.
In the split barrel and California barrel sampling procedures, standard sampling spoons are advanced
into the ground with 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 and hardness of weathered bedrock. 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. Atterberg
Limits and washed sieve analysis tests were completed on selected samples to evaluate the quantity
and plasticity of fines in the subgrade samples. 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. Soluble sulfate tests were completed on selected samples to evaluate potential
adverse reactions to site-cast concrete. Results of the outlined tests are indicated herein and/or 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 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. Coring and/or petrographic analysis may reveal
other rock types.
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SITE AND SUBSURFACE CONDITIONS
The referenced site is generally gravel surface yard areas with several parked semi-trucks and an
existing metal frame single-story storage type warehouse building towards the north end of the site.
The area is relatively flat.
Based on results of the field borings and laboratory testing, subsurface conditions can be generalized
as follows. At the surface of the borings, in general, was a layer of surficial aggregate base course
(ABC) and/or sandy lean clay to clayey/silty sand with variable amounts of gravel fill material
which extended to depths of approximately 1 to 6 feet below existing site grades to the underlying
apparent native sand and gravel material with variable silt in boring B-4 or to the apparent native
sandy lean clay to clayey/silty sand in the remaining borings. The apparent native sandy lean clay to
clayey/silty sand with occasional gravels encountered in borings B-1 through B-3 and borings B-5
through B-9 extended to the underlying sand and gravel material with variable silt at depths of
approximately 4 to 6 feet below existing site grades. The apparent native sand and gravel material
with variable silt encountered in boring B-4 underlying the apparent fill materials and underlying the
apparent native sandy lean clay to clayey/silty sand material in the remaining borings extended to
the underlying siltstone/sandstone bedrock. As presented on the enclosed boring logs, interbedded
cobbles were encountered at increased depths. The near surface apparent fill and native sandy lean
clay to clayey/silty sand materials, in general, were medium stiff to very stiff in consistency and
loose to medium dense in relative density, exhibited low to nil swell potential and low to moderate
bearing capacity characteristics. The sand and gravel materials materials, in general, were medium
dense to very dense in relative density, exhibited low to nil swell potential and moderate to high
bearing capacity characteristics.
Siltstone/sandstone bedrock was encountered in each of the borings at depths of approximately 11 to
14 feet below existing site grades and extended to the depths explored, approximately 15 to 30 feet.
The siltstone/sandstone bedrock, in general, was cemented to well cemented, demonstrated high
bearing capacity characteristics, and low to nil swell potential.
The stratification boundaries indicated on the boring logs represent the approximate locations of
changes in soil and rock types. In-situ, the transition of materials may be gradual and indistinct.
GROUNDWATER CONDITIONS
Observations were made while drilling and after completion of the borings to detect the presence and
depth to hydrostatic groundwater. At the time of drilling, free water was not encountered in any of
the borings to the depths explored, approximately 15 to 30 feet below existing site grades.
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Fluctuations in groundwater levels can occur over time depending on variations in hydrologic
conditions and other conditions not apparent at the time of this report. Longer term monitoring of
water levels in cased wells, which are sealed from the influence of surface water would be required to
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 and perched water is commonly observed in subgrade soils
immediately above lower permeability bedrock.
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, underlying sand and gravel with cobbles, and penetration of
the underlying well cemented sandstone bedrock lenses.
It is anticipated that excavations for the proposed construction can be accomplished with
conventional earthmoving equipment. However, excavations penetrating the well-cemented
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.
Swell/Consolidation Test Results
As a part of our laboratory testing, we conducted five (5) swell/consolidation tests on samples of the
overburden materials and underlying bedrock. The swell index values for the samples analyzed
revealed low to nil swell characteristics when inundated with water and pre-loaded at 150 psf, 500
psf and 1000 psf, as well as exhibiting a slight tendency to hydro-compact and consolidate with the
addition of water and increased loads. Results of the laboratory swell tests are indicated in the table
below, on the attached boring logs, and on the enclosed summary sheets.
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TABLE I - Swell Consolidation Test Results
Boring
No.
Depth,
ft.
Material Type
In-Situ Moisture
Content, %
Dry Density,
PCF
Inundation
Pressure, psf
Swell Index,
(+/-) %
B-1 14 Siltstone / Sandstone 14.1 104.8 1000 (-) 0.3
B-2 2 Sandy Lean Clay 14.0 119.7 500 (-) 0.3
B-4 4 Silty Sand with Gravel 9.0 123.2 500 (-) 0.1
B-5 2 Clayey/Silty Sand 10.9 118.7 150 (+) 0.7
B-7 2 Clayey Sand 13.4 113.9 150 (+) 0.1
The Colorado Association of Geotechnical Engineers (CAGE) uses the following information to
provide uniformity in terminology between geotechnical engineers to provide a relative correlation risk
performance to measured swell. “The representative percent swell values are not necessarily measured
values; rather, they are a judgment of the swell of the soil and/or bedrock profile likely to influence
slab performance.” Geotechnical engineers use this information to also evaluate the swell potential
risks for foundation performance based on the risk categories.
TABLE II: Recommended Representative Swell Potential Descriptions and Corresponding
Slab Performance Risk Categories
Slab Performance Risk
Category
Representative Percent Swell
(500 psf Surcharge)
Representative Percent Swell
(1000 psf Surcharge)
Low 0 to < 3 0 < 2
Moderate 3 to < 5 2 to < 4
High 5 to < 8 4 to < 6
Very High > 8 > 6
Based on the laboratory test results, the in-situ samples of overburden material and underlying
bedrock were in the low risk range.
Site Preparation
We understand the existing building near the north end of the site along with any associated site
improvements will be demolished/removed from the site prior to the construction of the new
development. 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
the existing structures, concrete sidewalks, pavement and other miscellaneous features 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 the existing site
structures/improvements. All materials derived from the demolition of the existing building,
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pavements, sidewalks or other site improvements should be removed from the site and not be
allowed for use in any on-site fills. Any demolition activities in the general vicinity of our boring B-
10, PCG should also be consulted to provide environmental related guidance.
Although final site grades were not available at the time of this report, based on our understanding of
the proposed development, we expect minor cuts and fills may be necessary to achieve design grades
in the improvement areas. After completing all cuts, and removing all unacceptable materials/soils,
and prior to placement of any fill or site improvements, we recommend the exposed soils be
scarified to a depth of 9-inches, adjusted in moisture content to within ±2% of standard Proctor
optimum moisture content for essentially cohesive materials or to a workable moisture content for
cohesionless materials and compacted to at least 95% of the material's standard Proctor maximum
dry density as determined in accordance with ASTM Specification D698.
Fill soils required for developing the buildings and site subgrades, after the initial zone has been
prepared or stabilized where necessary, should consist of approved, low-volume-change materials,
which are free from organic matter and debris. It is our opinion the on-site sandy lean clay to
clayey/silty sand and sand and gravel with varying silt material could be used as general site fill
material, provided adequate moisture treatment and compaction procedures are followed. Due to
potential site environmental concerns PCG should be consulted on potential reuse of site materials.
We recommend all fill and backfill materials, be placed in loose lifts not to exceed 9 inches thick
and adjusted in moisture content and compacted as recommended for the scarified soils above.
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.
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. Due to an existing covenant related to
environmental concerns for the referenced site, site groundwater shall not be used for domestic,
agricultural, commercial or other use and activities that disturb site soils shall be minimized to the extent
practical. With the proposed 5-story building with at grade parking, to reduce the required disturbance
of site soils, straight shaft drilled piers extending into the siltstone/sandstone bedrock should be
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considered. The following foundation system was evaluated for use on the site for the proposed
building development.
Straight shaft drilled piers bearing in the underlying bedrock formation for the proposed 5-story
building with at grade parking.
Drilled Piers/Caissons Foundations
Based on the subgrade conditions observed in the test borings and the anticipated foundation loads, we
recommend supporting the proposed building on 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 essentially cohesionless materials,
occasional cobbles, zones of well cemented sandstone and likely presence of perched groundwater.
For removal of cobbles at increased depths, consideration should be given to the use of 24-inch
diameter drilled piers.
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. Lower values may be appropriate
for pier “groupings” depending on the pier diameters and spacing. Pile groups should be evaluated
individually. Straight shaft piers should be drilled a minimum of 5 feet into competent or harder
bedrock with minimum shaft lengths of 20-feet are recommended.
To satisfy forces in the horizontal direction, piers may be designed for lateral loads using a modulus of
100 tons per cubic foot (tcf) for the portion of the pier in the fine to course granular subsoils, and 400
tcf in bedrock for a pier diameter of 12 inches. The coefficient of subgrade reaction for varying pier
diameters are as follows and generally conform to the formula of kh = 100/D, or 400/D, respectively,
for cohesionless soils and bedrock, in which D = pier diameter in feet:
Pier Diameter (inches) Coefficient of Subgrade Reaction (tons/ft3)
Cohesive Soils
Engineered Fill or
Granular Soils
Bedrock
18 33 50 267
24 25 38 200
30 20 30 160
36 17 25 133
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When the lateral capacity of drilled piers is evaluated by the L-Pile (COM 624) computer program, we
recommend that internally generated load-deformation (P-Y) curves be used. The following
parameters may be used for the design of laterally loaded piers, using the L-Pile (COM 624) computer
program:
Parameters Native Granular Soils or Structural Fill Bedrock
Unit Weight of Soil (pcf) 130
(1) 125(1)
Average Undrained Shear Strength (psf) 0 5,000
Angle of Internal Friction () (degrees) 35 25
Coefficient of Subgrade Reaction, ks & kc (pci)
800-static
500 – cyclic
2,000 – static
800 - cyclic
Strain, 50 (%) (2) --- 0.004
*Notes: 1) Reduced by 62.4 PCF below the water table
2) The 50 values represent the strain corresponding to 50 percent of the maximum principal stress
difference. The modulus of subgrade reaction for static (ks) and cyclical (kc) are used by the L-Pile
computer programs to generate the slope of the initial portion of the “p-y curves.”
All piers should be reinforced full depth for the applied axial, lateral, and uplift stresses imposed.
The amount of reinforcing steel for expansion should be determined by the tensile force created by
the uplift force on each pier, with allowance for dead load.
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.
With granular soils encountered on-site, as well as removal and/or drilling within large sized cobbles
zones, maintaining shafts may be difficult without stabilizing measures. We expect temporary casing
will be required to adequately/properly drill and clean piers prior to concrete placement.
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Groundwater, if encountered, 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.
Variable cobbles may be encountered in the granular materials overlying the siltstone/sandstone
bedrock. We suggest using larger diameter drilled piers, such as 24-inch or larger, to allow for
extraction of cobbles through the drilling process.
Foundation excavations should be observed by the geotechnical engineer. A representative of the
geotechnical engineer should inspect the bearing surface and pier configuration. Representation and/or
supplemental consultation services from PCG may be necessary during caisson installation due to
potential environmental related concerns. If the soil conditions encountered differ from those
presented in this report, supplemental recommendations may be required.
We estimate the long-term settlement of drilled pier foundations designed and constructed as
outlined above would be less than 1-inch.
Seismic Site Classification
The site soil conditions consist of approximately 11-14 feet of medium stiff to very stiff and/or dense
to very dense overburden soils overlying cemented to well cemented siltstone/sandstone bedrock
which extended to the depths explored, approximately 15 to 30 feet below existing site grades. For
those site conditions, the 2015 International Building Code indicates a Seismic Site Classification of
C.
Floor Slab/Pavement/Flatwork Subgrades – General Considerations
Due to the covenant related to environmental concerns for the referenced site, activities that disturb site
soils shall be minimized to the extent practical. With variable amounts of fill on the site and to minimize
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disturbance of site soils, consideration could be given to a structural slab system for the building. With
the understanding of greater potential movement, and activities that disturb site soils, consideration
could be given to over excavation of all or portions of the existing fills and replace in general accordance
with the recommendations provided in the Site Preparation section of this report for the building slab,
area flatwork and pavements. The following subgrade preparation options in order of least risk to
greatest risk were evaluated for use on the site for the proposed site development.
For the building: Use of a structural floor system structurally supported independent of the
underlying subsoils in conjunction with the proposed drilled pier foundation system.
For the building/pavement/flatwork: Over excavate previously placed fill materials to native
materials and replace with approved on-site or import materials to proposed grades to allow for
a conventional slab-on-grade.
For the building/pavement/flatwork: Over excavate at least three (3) feet of previously placed
fill material below proposed subgrades and replace with approved on-site or imported materials
to proposed grades to allow for a conventional slab-on-grade.
Floor Slab/Pavement/Flatwork Subgrades
If the over excavation and replacement method for the building is selected, and for preparation of
pavement/flatwork areas, after completing all cuts and prior to placement of any fill, floor slabs,
pavements or flatwork, we recommend the in-place materials be proof rolled with heavy
construction equipment to help locate any soft or loose materials in the exposed subgrades.
After completing all cuts including removal of existing fill (over excavation depths dependent on
amount of fill encountered and/or acceptable risk by owner), and prior to placement of fill and floor
slabs, pavements or flatwork, we recommend the top 9 inches of the exposed subgrades be scarified
and recompacted as outlined in the Site Preparation section of this report. We recommend fill
materials required to develop the subgrades consist of approved, low-volume change materials
which are free from organic matter and debris as recommended in the Site Preparation section of
this report. Although gravel bedding would not be required beneath the floor slabs to provide floor
slab support, a gravel leveling course could be considered.
Positive drainage should be developed away from the building and site improvements to reduce
potential for wetting of the subgrades. Typically, a minimum slope away from the building of 1 inch
per foot for the first 10 feet is recommended. Flatter slopes may be used in flatwork areas.
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Pavements
We expect the site pavements will include areas designated for low volume automobile and light
truck traffic. We are using an assumed equivalent daily load axle (EDLA) rating of 5.
Recompacting and proofrolling 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. Based on the subsurface
conditions encountered at the site, and the laboratory test results, it is recommended the on-site
drives and parking areas be designed using an assumed R-value of 10.
Pumping conditions could develop within higher moisture content on-site essentially cohesive soils.
Subgrade stabilization could be needed to develop a stable subgrade for paving. A stabilized subgrade
could also reduce the overlying pavement structure. Stabilization, if needed, would include
incorporating approximately 12 percent, by weight, Class C fly ash into the upper 12-inches of
subgrade.
Hot Mix Asphalt (HMA) underlain by crushed aggregate base course with or without a fly ash treated
subgrade, and non-reinforced concrete pavement could be considered for the proposed on-site paved
sections. Eliminating the risk of movement within the proposed pavement section may not be feasible
due to the characteristics of the subsurface materials; but it may be possible to further reduce the risk of
movement if significantly more expensive subgrade stabilization measures are used during
construction. We would be pleased to discuss other construction alternatives with you upon request.
Pavement design methods are intended to provide structural sections with adequate thickness over a
particular subgrade such that wheel loads are reduced to a level the subgrade can support. The
support characteristics of the subgrade for pavement design do not account for shrink/swell
movements of an expansive clay subgrade or consolidation of a wetted subgrade. Thus, the
pavement may be adequate from a structural standpoint, yet still experience cracking and
deformation due to shrink/swell related movement of the subgrade. It is, therefore, important to
minimize moisture changes in the subgrade to reduce shrink/swell movements.
Recommended pavement sections are provided in the table below. The hot bituminous pavement
(HBP) could be grading SX (75) or S (75) with PG 58-28 oil. The aggregate base should be Class 5
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or Class 6 base. Portland cement concrete for pavements should be a pavement design mix with a
minimum 28-day compressive strength of 4000 psi and should be air entrained.
TABLE III – Recommended Minimum Pavement Sections
18-kip EDLA
18-kip ESAL
Reliability
Resilient Modulus (R-Value = 10)
PSI Loss
5
36,500
75%
3562 psi
2.5
Design Structure Number 2.34
Composite:
Hot Mix Asphalt
Aggregate Base Course
Structure Number
4" @ 0.44 = 1.76
6" @ 0.11 = 0.66
(2.42)
Composite with Fly Ash Treated Subgrade
Hot Bituminous Pavement
Aggregate Base
Fly Ash Treated Subgrade
Structure Number
3" @ 0.44 = 1.32
6" @ 0.11 = 0.66
10" @ 0.05 = 0.50
(2.48)
PCC (Non-reinforced) – placed on a stable subgrade 5"
The recommended pavement sections are minimums and periodic maintenance should be expected.
Longitudinal and transverse joints should be provided as needed in concrete pavements for
expansion/contraction and isolation. The location and extent of joints should be based upon the final
pavement geometry. Sawed joints should be cut in general accordance with ACI recommendations.
All joints should be sealed to prevent entry of foreign material and dowelled where necessary for load
transfer.
The collection and diversion of surface drainage away from paved areas is critical to the satisfactory
performance of the pavement. Drainage design should provide for the removal of water from paved
areas in order to reduce the potential for wetting of the subgrade soils. 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:
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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. garden centers,
wash racks)
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.
Preventive maintenance should be planned and provided for through an on-going pavement
management program. Preventive maintenance activities are intended to slow the rate of pavement
deterioration, and to preserve the pavement investment. Preventive maintenance consists of both
localized maintenance (e.g. crack and joint sealing and patching) and global maintenance (e.g. surface
sealing). Preventive maintenance is usually the first priority when implementing a planned pavement
maintenance program and provides the highest return on investment for pavements. Prior to
implementing any maintenance, additional engineering observation is recommended to determine the
type and extent of preventive maintenance.
Site grading is generally accomplished early in the construction phase. However, as construction
proceeds, the subgrade may be disturbed due to utility excavations, construction traffic, desiccation, or
rainfall. As a result, the pavement subgrade may not be suitable for pavement construction and
corrective action will be required. The subgrade should be carefully evaluated at the time of pavement
construction for signs of disturbance, such as but not limited to drying, or excessive rutting. If
disturbance has occurred, pavement subgrade areas should be reworked, moisture conditioned, and
properly compacted to the recommendations in this report immediately prior to paving.
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) testing of the on-site overburden and bedrock materials taken during
our subsurface exploration at varying depths are provided in the table below. Based on the reported
Earth Engineering Consultants, LLC
EEC Project No. 1182008
February 23, 2018
Page 14
sulfate content test results, this report includes a recommendation for the CLASS or TYPE of cement
for use for contact in association with the on-site overburden and bedrock.
TABLE IV - Water Soluble Sulfate Test Results
Sample Location Description
Soluble Sulfate Content
(mg/kg)
Soluble Sulfate
Content (%)
B-1, S-4 @ 19’ Siltstone / Sandstone 100 0.01
B-2, S-2 @ 4’ Sand and Gravel with Silt 130 0.01
B-5, S-3 @ 9’ Sand and Gravel 90 0.01
Based on the results as presented in the table above, ACI 318, Section 4.2 indicates the site
overburden soils and bedrock generally have a low risk of sulfate attack on Portland cement
concrete. Therefore, Class 0 and Type I or Type I/II cement could be used for concrete on and
below site grades within the overburden soils and/or bedrock. Foundation concrete should be
designed in accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4.
Other Considerations
Positive drainage should be developed away from the structure with a minimum slope of 1-inch per
foot for the first 10-feet away from the improvements in landscape areas. Flatter slopes could be
used in hardscapes areas although positive drainage should be maintained. Care should be taken in
planning of landscaping adjacent to the building and site improvement areas to avoid features which
would pond water adjacent to those elements. 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.
Excavations into the on-site soils may encounter a variety of conditions. If excavations extend into
the underlying cohesionless 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. 1182008
February 23, 2018
Page 15
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 for CA Ventures 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.
Group
Symbol
Group Name
Cu≥4 and 1<Cc≤3
E
GW Well-graded gravel
F
Cu<4 and/or 1>Cc>3
E
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≤3
E
SW Well-graded sand
I
Cu<6 and/or 1>Cc>3
E
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
1
2
B-10
B-4
B-9
B-3
B-7
B-1
B-2
B-5
B-8
B-6
Boring Location Diagram
232 Willow Development - Fort Collins, Colorado
EEC Project Number: 1182008
January 2018
EARTH ENGINEERING CONSULTANTS, LLC
Approximate Boring
Locations
1
Legend
Site Photos
(Photos taken in approximate
location, in direction of arrow)
B-10 was Omitted
232 WILLOW STREET DEVELOPMENT
FORT COLLINS, COLORADO
EEC PROJECT NO. 1182008
JANUARY 2018
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
SANDY LEAN CLAY to CLAYEY/SILTY SAND with _ _
GRAVEL - FILL 1
dark brown _ _
2
SANDY LEAN CLAY (CL) _ _
dark brown to brown 3
_ _
4
_ _
CS 5 53 9000+ 6.0 131.8
POORLY GRADED SAND with SILT (SP) _ _
brown 6
very dense to dense _ _
with gravel 7
_ _
8
_ _
9
_ _
SS 10 41 -- 2.8 6.4
_ _
11
_ _
12
_ _
13
_ _
SILTSTONE / SANDSTONE 14
brown / rust _ _ % @ 1000 psf
well cemented CS 15 50/3" 9000+ 14.1 104.8 NL NP 17.5 <1000 psf None
*classifies as SILTY SAND (SM) _ _
16
_ _
17
_ _
18
_ _
19
gray _ _
SS 20 50/2" 9000+ 14.4
_ _
21
_ _
22
_ _
23
_ _
24
_ _
CS 25 50/1.5" 9000+ 13.0
Continued on Sheet 2 of 2 _ _
Earth Engineering Consultants, LLC
PROPOSED 232 WILLOW STREET 5-STORY MIXED USE DEVELOPMENT
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
Continued from Sheet 1 of 2 26
_ _
27
SILTSTONE / SANDSTONE _ _
gray 28
well cemented _ _
29
_ _
no recovery SS 30 50/2"
_ _
BOTTOM OF BORING DEPTH 30.5' 31
_ _
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Earth Engineering Consultants, LLC
PROPOSED 232 WILLOW STREET 5-STORY MIXED USE DEVELOPMENT
FORT COLLINS, COLORADO
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
ABC - 4" _ _
SANDY LEAN CLAY (CL) - FILL 1
dark brown _ _
stiff 2
_ _
SANDY LEAN CLAY (CL) CS 3 12 9000+ 14.0 115.9 25 15 50.9 <500 psf None
brown; stiff _ _
4
SAND / GRAVEL with SILT (SP / GP) _ _
brown SS 5 60 -- 2.8
very dense _ _
6
_ _
7
_ _
8
_ _
9
with cobbles _ _
CS 10 50/5" -- 2.1
_ _
11
_ _
SILTSTONE / SANDSTONE 12
brown / rust _ _
well cemented 13
_ _
14
gray _ _
SS 15 50/0.5" 9000+ 17.0
_ _
16
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17
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18
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19
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CS 20 50/0.5" -- 12.4
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21
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24
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SS 25 50/1" 9000+ 15.7
BOTTOM OF BORING DEPTH 25.5' _ _
Earth Engineering Consultants, LLC
PROPOSED 232 WILLOW STREET 5-STORY MIXED USE DEVELOPMENT
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
ABC - 5" _ _
SANDY LEAN CLAY / CLAYEY SAND (CL/SC) - FILL 1
dark brown to brown _ _
2
SANDY LEAN CLAY / CLAYEY SAND (CL/SC) _ _
brown 3
medium stiff to stiff _ _
with occasional gravel 4
_ _
CS 5 27 -- 5.4 114.1
POORLY GRADED SAND with SILT (SP) _ _
brown 6
medium dense to dense _ _
with occasional cobbles 7
_ _
8
_ _
9
_ _
SS 10 50 -- 3.1 5.9
_ _
11
_ _
12
_ _
SILTSTONE / SANDSTONE 13
brown / rust _ _
cemented 14
_ _
CS 15 50/3" 3000 12.0 95.0
BOTTOM OF BORING DEPTH 15.0' _ _
16
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Earth Engineering Consultants, LLC
PROPOSED 232 WILLOW STREET 5-STORY MIXED USE DEVELOPMENT
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
_ _
CLAYEY/SILTY SAND (SC/SM0 - FILL 1
brown _ _
loose 2
with gravel and occasional debris _ _
3
_ _
4
_ _
CS 5 6 1500 9.0 123.2 22 2 19.6 <500 psf None
_ _
6
_ _
SAND / GRAVEL (SP / GP) 7
brown _ _
very dense 8
_ _
9
_ _
SS 10 50 -- 1.5
_ _
11
_ _
12
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13
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SILTSTONE / SANDSTONE 14
brown / rust _ _
cemented CS 15 50/5" 8500 11.3 131.8
_ _
16
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17
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18
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19
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SS 20 50/3.5" 7500 12.7
_ _
21
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22
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23
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24
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CS 25 50/3" 9000+ 12.8 99.4
BOTTOM OF BORING DEPTH 25.0' _ _
Earth Engineering Consultants, LLC
PROPOSED 232 WILLOW STREET 5-STORY MIXED USE DEVELOPMENT
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
ABC - 2" _ _
CLAYEY SAND with GRAVEL (SC) - FILL 1
dark brown _ _
2
CLAYEY / SILTY SAND (SC-SM) _ _ % @ 150 psf
brown CS 3 11 4500 10.9 112.5 22 6 40.7 1000 psf 0.7%
medium dense _ _
4
_ _
SAND / GRAVEL (SP / GP) SS 5 49 -- 6.3
brown _ _
dense to very dense 6
_ _
7
_ _
8
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9
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CS 10 50/7" -- 3.1 117.2
_ _
11
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12
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13
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SILTSTONE / SANDSTONE 14
brown / olive / rust _ _
well cemented SS 15 50/1" -- 13.0
_ _
BOTTOM OF BORING DEPTH 15.5' 16
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25
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Earth Engineering Consultants, LLC
PROPOSED 232 WILLOW STREET 5-STORY MIXED USE DEVELOPMENT
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
ABC - 2" _ _
1
SANDY LEAN CLAY / CLAYEY SAND (CL/SC) - FILL _ _
brown / black 2
very stiff / medium dense _ _
with gravel and ash/coal CS 3 27 1000 8.7 92.2
_ _
4
CLAYEY SAND (SC) _ _
brown SS 5 6 2000 12.3 23 8 41.8
loose _ _
6
_ _
WELL GRADED SAND with GRAVEL and SILT (SW) 7
brown _ _
very dense 8
_ _
9
_ _
CS 10 50/9" -- 3.4 116.5 9.4
_ _
11
_ _
12
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13
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SILTSTONE / SANDSTONE 14
brown / rust _ _
cemented SS 15 50/5" -- 13.7
_ _
BOTTOM OF BORING DEPTH 15.5' 16
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17
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25
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Earth Engineering Consultants, LLC
PROPOSED 232 WILLOW STREET 5-STORY MIXED USE DEVELOPMENT
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
ABC - 10" _ _
SANDY LEAN CLAY to CLAYEY/SILTY SAND - FILL 1
dark brown, with gravel _ _
2
CLAYEY SAND (SC) _ _ % @ 150 psf
brown CS 3 9 6000 13.4 113.6 25 15 38.4 400 psf 0.1%
loose _ _
with gravel 4
_ _
SAND / GRAVEL (SP / GP) SS 5 50/7" -- 2.1
brown _ _
very dense 6
_ _
7
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8
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9
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SS 10 50/10" -- 1.7
_ _
11
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12
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13
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SILTSTONE / SANDSTONE 14
brown / rust _ _
weathered to well cemented CS 15 -- 2500 4.9 115.4
_ _
16
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17
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18
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19
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SS 20 50/0.25" 9000+ 11.0
_ _
21
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22
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23
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24
gray _ _
CS 25 50/1" 9000+ 9.9
Continued on Sheet 2 of 2 _ _
Earth Engineering Consultants, LLC
PROPOSED 232 WILLOW STREET 5-STORY MIXED USE DEVELOPMENT
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
Continued from Sheet 1 of 2 26
_ _
27
SILTSTONE / SANDSTONE _ _
gray 28
well cemented _ _
29
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SS 30 50/2" 9000+ 15.5
_ _
BOTTOM OF BORING DEPTH 30.5' 31
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Earth Engineering Consultants, LLC
PROPOSED 232 WILLOW STREET 5-STORY MIXED USE DEVELOPMENT
FORT COLLINS, COLORADO
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
_ _
SANDY LEAN CLAY to CLAYEY/SILTY SAND - FILL 1
dark brown, with gravel _ _
2
CLAYEY/SILTY SAND (SC/SM) _ _
brown 3
with gravel _ _
4
_ _
SILTY SAND with GRAVEL (SM) CS 5 50/8" -- 5.0 126.8
brown _ _
very dense 6
with cobbles _ _
7
_ _
8
_ _
9
_ _
SS 10 50/9" -- 3.3 14.4
_ _
11
_ _
12
_ _
SILTSTONE / SANDSTONE 13
brown / rust _ _
cemented 14
_ _
SS 15 50/5" 9000+ 13.3
_ _
16
_ _
17
_ _
18
_ _
19
*classifies as CLAYEY SAND (SC) _ _
CS 20 50/3" 9000+ 16.2 36 10 19.9
BOTTOM OF BORING DEPTH 20.0' _ _
21
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25
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Earth Engineering Consultants, LLC
PROPOSED 232 WILLOW STREET 5-STORY MIXED USE DEVELOPMENT
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
SANDY LEAN CLAY/CLAYEY SAND - FILL _ _
dark brown; with gravel 1
_ _
SANDY LEAN CLAY (CL) 2
dark brown to brown _ _
very stiff CS 3 29
no recovery _ _
4
_ _
SS 5 26 5000 15.9
WELL GRADED SAND with GRAVEL and SILT (SW) _ _
brown 6
dense _ _
7
_ _
8
_ _
9
_ _
CS 10 45 -- 2.5 120.1 9
_ _
11
_ _
12
_ _
13
_ _
14
SILTSTONE / SANDSTONE _ _
brown / rust SS 15 50/4" 3500 13.6
cemented to well cemented _ _
16
_ _
17
_ _
18
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19
gray _ _
CS 20 50/3" 9000+ 13.6
_ _
21
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22
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23
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24
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SS 25 50/2" 9000+ 12.8
Continued on Sheet 2 of 2 _ _
Earth Engineering Consultants, LLC
PROPOSED 232 WILLOW STREET 5-STORY MIXED USE DEVELOPMENT
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
Continued from Sheet 1 of 2 26
_ _
27
SILTSTONE / SANDSTONE _ _
gray 28
well cemented _ _
29
_ _
CS 30 50/2" 9000+ 11.9
BOTTOM OF BORING DEPTH 30.0' _ _
31
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Earth Engineering Consultants, LLC
PROPOSED 232 WILLOW STREET 5-STORY MIXED USE DEVELOPMENT
FORT COLLINS, COLORADO
Project:
Location:
Project #:
Date:
Proposed 232 Willow Street 5-Story Mixed Use Development
Fort Collins, Colorado
1182008
February 2018
Beginning Moisture: 14.1% Dry Density: 104.8 pcf Ending Moisture: 24.0%
Swell Pressure: <1000 psf % Swell @ 1000: None
Sample Location: Boring 1, Sample 3, Depth 14'
Liquid Limit: NL Plasticity Index: NP % Passing #200: 17.5%
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown / Rust Siltstone / Sandstone
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
10.0
0.01 0.1 1 10
Percent Movement
Load (TSF)
Consolidatio Swell
Water Added
Project:
Location:
Project #:
Date:
Proposed 232 Willow Street 5-Story Mixed Use Development
Fort Collins, Colorado
1182008
February 2018
Beginning Moisture: 14.0% Dry Density: 119.7 pcf Ending Moisture: 15.2%
Swell Pressure: <500 psf % Swell @ 500: None
Sample Location: Boring 2, Sample 1, Depth 2'
Liquid Limit: 25 Plasticity Index: 15 % Passing #200: 50.9%
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Dark 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
Percent Movement
Load (TSF)
Consolidatio Swell
Water Added
Project:
Location:
Project #:
Date:
Proposed 232 Willow Street 5-Story Mixed Use Development
Fort Collins, Colorado
1182008
February 2018
Beginning Moisture: 9.0% Dry Density: 123.2 pcf Ending Moisture: 14.3%
Swell Pressure: <500 psf % Swell @ 500: None
Sample Location: Boring 4, Sample 1, Depth 4'
Liquid Limit: 22 Plasticity Index: 2 % Passing #200: 19.6%
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown Silty Sand with Gravel and Occasional Debris (SM)
-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
Percent Movement
Load (TSF)
Consolidatio Swell
Water Added
Project:
Location:
Project #:
Date:
Proposed 232 Willow Street 5-Story Mixed Use Development
Fort Collins, Colorado
1182008
February 2018
Beginning Moisture: 10.9% Dry Density: 118.7 pcf Ending Moisture: 15.0%
Swell Pressure: 1000 psf % Swell @ 150: 0.7%
Sample Location: Boring 5, Sample 1, Depth 2'
Liquid Limit: 22 Plasticity Index: 6 % Passing #200: 40.7%
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown Clayey/Silty Sand (SC-SM)
-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
Percent Movement
Load (TSF)
Consolidatio Swell
Water Added
Project:
Location:
Project #:
Date:
Proposed 232 Willow Street 5-Story Mixed Use Development
Fort Collins, Colorado
1182008
February 2018
Beginning Moisture: 13.4% Dry Density: 113.9 pcf Ending Moisture: 19.7%
Swell Pressure: 400 psf % Swell @ 150: 0.1%
Sample Location: Boring 7, Sample 1, Depth 2'
Liquid Limit: 25 Plasticity Index: 15 % Passing #200: 38.4%
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown Clayey Sand (SC)
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
10.0
0.01 0.1 1 10
Percent Movement
Load (TSF)
Consolidatio Swell
Water Added
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: Proposed 232 Willow Street 5-Story Mixed Use Development
Location: Fort Collins, Colorado
Project No: 1182008
Sample ID: B-1, S-2, 9'
Sample Desc.: POORLY GRADED SAND with SILT (SP)
Date: February 2018
97
91
83
19
6.4
81
70
52
43
32
100
100
EARTH ENGINEERING CONSULTANTS, LLC
SUMMARY OF LABORATORY TEST RESULTS
Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136)
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 Clay
Gravel
Coarse Fine
Sand
Coarse Medium
February 2018
12.50 0.85 0.55
Proposed 232 Willow Street 5-Story Mixed Use Development
Fort Collins, Colorado
1182008
B-1, S-2, 9'
POORLY GRADED SAND with SILT (SP)
D100 D
60 D50
0.27 0.10
Fine
8.75 0.92
D30 D
10 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
1000 100 10 1 0.1 0.01
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: Proposed 232 Willow Street 5-Story Mixed Use Development
Location: Fort Collins, Colorado
Project No: 1182008
Sample ID: B-3, S-2, 9'
Sample Desc.: POORLY GRADED SAND with SILT (SP)
Date: February 2018
EARTH ENGINEERING CONSULTANTS, LLC
SUMMARY OF LABORATORY TEST RESULTS
Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136)
Sieve Size Percent Passing
100
100
99
91
80
11
5.9
77
63
42
35
27
0.35 0.14
Fine
7.84 0.80
D30 D
10 Cu
CC
February 2018
12.50 1.09 0.82
Proposed 232 Willow Street 5-Story Mixed Use Development
Fort Collins, Colorado
1182008
B-3, S-2, 9'
POORLY GRADED SAND with SILT (SP)
D100 D
60 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 Clay
Gravel
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
1000 100 10 1 0.1 0.01
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: Proposed 232 Willow Street 5-Story Mixed Use Development
Location: Fort Collins, Colorado
Project No: 1182008
Sample ID: B-6, S-3, 9'
Sample Desc.: WELL GRADED SAND with GRAVEL and SILT (SW)
Date: February 2018
74
62
51
14
9.4
49
39
29
25
20
100
100
86
84
78
EARTH ENGINEERING CONSULTANTS, LLC
SUMMARY OF LABORATORY TEST RESULTS
Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136)
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 Clay
Gravel
Coarse Fine
Sand
Coarse Medium
February 2018
37.50 4.29 2.18
Proposed 232 Willow Street 5-Story Mixed Use Development
Fort Collins, Colorado
1182008
B-6, S-3, 9'
WELL GRADED SAND with GRAVEL and SILT (SW)
D100 D
60 D50
0.66 0.08
Fine
50.87 1.19
D30 D
10 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
1000 100 10 1 0.1 0.01
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: Proposed 232 Willow Street 5-Story Mixed Use Development
Location: Fort Collins, Colorado
Project No: 1182008
Sample ID: B-8, S-2, 9'
Sample Desc.: SILTY SAND with GRAVEL (SM)
Date: February 2018
83
72
63
19
14.4
61
52
37
31
26
100
100
100
97
89
EARTH ENGINEERING CONSULTANTS, LLC
SUMMARY OF LABORATORY TEST RESULTS
Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136)
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 Clay
Gravel
Coarse Fine
Sand
Coarse Medium
February 2018
25.00 1.95 1.11
Proposed 232 Willow Street 5-Story Mixed Use Development
Fort Collins, Colorado
1182008
B-8, S-2, 9'
SILTY SAND with GRAVEL (SM)
D100 D
60 D50
0.40 ‐‐‐
Fine
‐‐‐ ‐‐‐
D30 D
10 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
1000 100 10 1 0.1 0.01
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: Proposed 232 Willow Street 5-Story Mixed Use Development
Location: Fort Collins, Colorado
Project No: 1182008
Sample ID: B-9, S-3, 9'
Sample Desc.: WELL GRADED SAND with GRAVEL and SILT (SW)
Date: February 2018
83
76
64
14
9.0
60
48
32
26
21
100
100
100
92
86
EARTH ENGINEERING CONSULTANTS, LLC
SUMMARY OF LABORATORY TEST RESULTS
Sieve Analysis (AASHTO T 11 & T 27 / ASTM C 117 & C 136)
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 Clay
Gravel
Coarse Fine
Sand
Coarse Medium
February 2018
25.00 2.00 1.33
Proposed 232 Willow Street 5-Story Mixed Use Development
Fort Collins, Colorado
1182008
B-9, S-3, 9'
WELL GRADED SAND with GRAVEL and SILT (SW)
D100 D
60 D50
0.54 0.09
Fine
22.05 1.60
D30 D
10 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
1000 100 10 1 0.1 0.01
Finer by Weight (%)
Grain Size (mm)
Standard Sieve Size
Finer by Weight (%)
Grain Size (mm)
Standard Sieve Size
Finer by Weight (%)
Grain Size (mm)
Standard Sieve Size
Finer by Weight (%)
Grain Size (mm)
Standard Sieve Size
Finer by Weight (%)
Grain Size (mm)
Standard Sieve Size
PROJECT NO: 1182008 LOG OF BORING B-9 FEBRUARY 2018
SHEET 2 OF 2 WATER DEPTH
START DATE 1/31/2018 WHILE DRILLING None
1/31/2018 AFTER DRILLING N/A
SURFACE ELEV 24 HOUR N/A
FINISH DATE
A-LIMITS SWELL
N/A
FORT COLLINS, COLORADO
PROJECT NO: 1182008 LOG OF BORING B-9 FEBRUARY 2018
SHEET 1 OF 1 WATER DEPTH
START DATE 1/31/2018 WHILE DRILLING None
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 1/31/2018 AFTER DRILLING N/A
A-LIMITS SWELL
FORT COLLINS, COLORADO
PROJECT NO: 1182008 LOG OF BORING B-8 FEBRUARY 2018
SHEET 1 OF 1 WATER DEPTH
START DATE 1/31/2018 WHILE DRILLING None
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 1/31/2018 AFTER DRILLING N/A
A-LIMITS SWELL
PROJECT NO: 1182008 LOG OF BORING B-7 FEBRUARY 2018
SHEET 2 OF 2 WATER DEPTH
START DATE 1/31/2018 WHILE DRILLING None
1/31/2018 AFTER DRILLING N/A
SURFACE ELEV 24 HOUR N/A
FINISH DATE
A-LIMITS SWELL
N/A
FORT COLLINS, COLORADO
PROJECT NO: 1182008 LOG OF BORING B-7 FEBRUARY 2018
SHEET 1 OF 1 WATER DEPTH
START DATE 1/31/2018 WHILE DRILLING None
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 1/31/2018 AFTER DRILLING N/A
A-LIMITS SWELL
FORT COLLINS, COLORADO
PROJECT NO: 1182008 LOG OF BORING B-6 FEBRUARY 2018
SHEET 1 OF 1 WATER DEPTH
START DATE 1/31/2018 WHILE DRILLING None
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 1/31/2018 AFTER DRILLING N/A
A-LIMITS SWELL
FORT COLLINS, COLORADO
PROJECT NO: 1182008 LOG OF BORING B-5 FEBRUARY 2018
SHEET 1 OF 1 WATER DEPTH
START DATE 1/31/2018 WHILE DRILLING None
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 1/31/2018 AFTER DRILLING N/A
A-LIMITS SWELL
FORT COLLINS, COLORADO
PROJECT NO: 1182008 LOG OF BORING B-4 FEBRUARY 2018
SHEET 1 OF 1 WATER DEPTH
START DATE 1/31/2018 WHILE DRILLING None
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 1/31/2018 AFTER DRILLING N/A
A-LIMITS SWELL
FORT COLLINS, COLORADO
PROJECT NO: 1182008 LOG OF BORING B-3 FEBRUARY 2018
SHEET 1 OF 1 WATER DEPTH
START DATE 1/31/2018 WHILE DRILLING None
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 1/31/2018 AFTER DRILLING N/A
A-LIMITS SWELL
FORT COLLINS, COLORADO
PROJECT NO: 1182008 LOG OF BORING B-2 FEBRUARY 2018
SHEET 1 OF 1 WATER DEPTH
START DATE 1/31/2018 WHILE DRILLING None
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 1/31/2018 AFTER DRILLING N/A
A-LIMITS SWELL
PROJECT NO: 1182008 LOG OF BORING B-1 FEBRUARY 2018
SHEET 2 OF 2 WATER DEPTH
START DATE 1/31/2018 WHILE DRILLING None
1/31/2018 AFTER DRILLING N/A
SURFACE ELEV 24 HOUR N/A
FINISH DATE
A-LIMITS SWELL
N/A
FORT COLLINS, COLORADO
PROJECT NO: 1182008 LOG OF BORING B-1 FEBRUARY 2018
SHEET 1 OF 1 WATER DEPTH
START DATE 1/31/2018 WHILE DRILLING None
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 1/31/2018 AFTER DRILLING N/A
A-LIMITS SWELL
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
PLASTICITY INDEX (PI)
LIQUID LIMIT (LL)
ML OR OL
MH OR OH
For Classification of fine-grained soils and
fine-grained fraction of coarse-grained
soils.
Equation of "A"-line
Horizontal at PI=4 to LL=25.5
then PI-0.73 (LL-20)
Equation of "U"-line
Vertical at LL=16 to PI-7,
then PI=0.9 (LL-8)
CL-ML
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