HomeMy WebLinkAboutJEFFERSON & LINDEN RESTAURANT - PDP - PDP160030 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTGEOTECHNICAL EXPLORATION REPORT
JEFFERSON STREET AND LINDEN STREET DEVELOPMENT
FORT COLLINS, COLORADO
EEC PROJECT NO. 1162014
Prepared for:
Blue Ocean Real Estate Management, LLC
401 West Mountain Avenue – Suite 200
Fort Collins, Colorado 80521
Attn: Mr. Brandon Grebe (Brandon.Grebe@blueoceanrem.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
www.earth-engineering.com
March 16, 2016
Blue Ocean Real Estate Management, LLC
401 West Mountain Avenue – Suite 200
Fort Collins, Colorado 80521
Attn: Mr. Brandon Grebe (Brandon.Grebe@blueoceanrem.com)
Re: Geotechnical Exploration Report
Jefferson Street and Linden Street Development
Fort Collins, Colorado
EEC Project No. 1162014
Mr. Grebe:
Enclosed herewith, are the results of the subsurface exploration completed by Earth Engineering
Consultants, LLC for the referenced project. For this exploration, four (4) soil borings were
extended to depths of approximately 10 to 30 feet below existing site grades within the proposed
building and site improvements. This subsurface exploration was completed in general
accordance with our proposal dated February 12, 2016.
In summary, the subsurface conditions encountered in the test borings generally consisted of
clayey sand which was underlain by silty sand and gravel encountered at approximate depths of
4 to 5 feet below site grades, and extending to the depths explored in borings B-3 and B-4,
approximately 10 feet below existing site grades, or to the underlying sandstone/siltstone
bedrock in the remaining borings. The near surface soils showed generally low swell potential
with light to moderate bearing capacity characteristics. The underlying silty sand and gravel
showed moderate bearing capacity characteristics while the underlying sandstone/siltstone
bedrock showed moderate to high bearing capacity characteristics. Groundwater was not
observed in any of the borings at the time of drilling to the maximum depths explored,
approximately 10 to 30 feet below site grades. The borings were backfield upon completion of
the drilling operations; therefore subsequent measurements were not obtained.
Based on the subsurface conditions encountered in the test borings and the anticipated loading
conditions, we believe the proposed 2-story slab-on-grade building could be supported on
conventional type spread footings bearing on approved in-situ cohesive native subsoils or on a
zone of approved engineered fill. It is our opinion floor slabs, exterior flatwork, and pavements
GEOTECHNICAL EXPLORATION REPORT
JEFFERSON STREET AND LINDEN STREET DEVELOPMENT
FORT COLLINS, COLORADO
EEC PROJECT NO. 1162014
March 16, 2016
INTRODUCTION
The geotechnical subsurface exploration for the proposed development planned for construction
north of the intersection of Jefferson Street (aka Riverside Avenue / Highway 14) and Linden Street
in Fort Collins, Colorado has been completed. As a part of this exploration, two (2) foundation
related borings (borings B-1 and B-2), one (1) pavement related boring (boring B-3) and one (1)
plaza area related boring (boring B-4) were drilled at the approximate locations as shown on the
boring location diagram included with this report. Foundation related soil borings completed within
the proposed building footprint were extended to depths of approximately 20 to 30 feet below
existing site grades while the pavement and plaza area related soil borings extended to approximate
depths of 10 feet below existing site grades. Individual boring logs are provided with this report.
Site photographs of the property at the time of our exploration are also provided with this report.
We understand the proposed development involves the construction of an approximate 4,500 square
foot in plan line dimensions, 2-story, slab-on-grade building, a plaza area, and pavements/parking.
Foundation loads for the structure are expected to be light to moderate with continuous wall loads
less than 4 kips per lineal foot and individual column loads less than 150 kips. Floor loads are
expected to be light. Paved drives and parking are expected as a part of the site development. The
pavements are expected to carry light traffic volume consisting predominately of automobiles and
light trucks. Small grade changes are expected to develop site grades for the proposed
improvements.
The purpose of this report is to describe the subsurface conditions encountered in the test borings,
analyze and evaluate the field and laboratory test data and provide geotechnical recommendations
concerning design and construction of foundations and support of floor slabs, exterior flatwork, and
pavements for the proposed development.
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EXPLORATION AND TESTING PROCEDURES
The boring locations were established in the field by a representative of Earth Engineering
Consultants, LLC (EEC) by pacing and estimating angles from identifiable site features. The
locations of the borings should be considered accurate only to the degree implied by the methods
used. Photographs of the site at the time of drilling are included with this report and the approximate
locations of the borings are indicated on the attached boring location diagrams.
The test borings were completed 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
foundation related 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 and hardness of weathered bedrock. In the California barrel sampling
procedure, relatively undisturbed samples are obtained in removable brass liners. All samples
obtained in the field were sealed and returned to the 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. 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. Water soluble sulfate was determined on select samples of site overburden
materials to estimate the potential for sulfate attack on site-cast Portland cement concrete. Results of
the outlined tests are indicated on the attached boring logs and summary sheets.
As part of the testing program, all samples were examined in the laboratory and classified in general
accordance with the attached General Notes and the Unified Soil Classification System, based on the
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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 auger
cuttings and disturbed samples. Coring and/or petrographic analysis may reveal other rock types.
SITE AND SUBSURFACE CONDITIONS
The proposed development is planned for construction north of the intersection of Jefferson Street
and Linden Street. The development parcel is presently a park with sparse vegetation and topsoil,
various trees, and various site improvements. Ground surface in this area is relatively flat.
The near surface materials in test borings B-1, B-2, and B-4 generally consisted of a thin layer of
sparse vegetation. The near surface materials in test boring B-3 consisted of approximately 2 inches
of asphalt with 3 ½ inches of underlying aggregate base course (ABC) materials. Possible fill on the
order of 1 to 3 feet, difficult to distinguish from apparent native subsoils, was observed in the
borings underlying the sparse vegetation and asphalt/ABC materials generally classified as clayey
sand. Underlying the thin layer of sparse vegetation or asphalt/ABC and underlying the possible fill
was relatively dry, very stiff/dense clayey sand. The essentially cohesive soils exhibited generally
low swells in laboratory testing at in-situ moisture and density. The essentially cohesive soils
extended to depths of approximately 4 to 5 feet and were underlain by silty sand and gravel which
extended to the depths explored in borings B-3 and B-4, approximately 10 feet below existing grade,
or to the underlying bedrock in the foundation related borings B-1 and B-2. The granular soils
exhibited no plasticity and moderate bearing capacity characteristics. Sandstone/siltstone bedrock
was encountered in borings B-1 and B-2 at approximate depths of 10 and 14 feet, respectively, and
extended to the depths explored, approximately 20 to 30 feet below existing site grades. The
sandstone/siltstone bedrock exhibited moderate to high bearing capacity characteristics.
The stratification boundaries indicated on the boring logs represent the approximate locations of
changes in soil types. In-situ, the transition of materials may be gradual and indistinct.
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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 groundwater was not observed in any
of the borings. The borings were backfilled upon completion of the drilling; therefore subsequent
groundwater measurements were not performed.
Fluctuations in groundwater levels can occur over time depending on variations in hydrologic
conditions and other conditions not apparent at the time of this report. Longer term monitoring of
water levels in cased wells, which are sealed from the influence of surface water, would be required
to more accurately evaluate fluctuations in groundwater levels at the site. Perched groundwater is
commonly observed in subgrade soils overlying less permeable bedrock. We have typically noted
deepest groundwater levels in late winter and shallowest groundwater levels in mid to late summer.
ANALYSIS AND RECOMMENDATIONS
Swell – Consolidation Test Results
The swell-consolidation test is performed to evaluate the swell or collapse potential of soils or bedrock
to help determine foundation, floor slab, and pavement design criteria. In this test, relatively
undisturbed samples obtained directly from the California barrel sampler are placed in a laboratory
apparatus and inundated with water under a predetermined load. All inundated samples are monitored
for swell and consolidation. The swell-index is the resulting amount of swell or collapse after
inundation, expressed as a percent of the sample’s initial thickness. After the initial inundation period,
additional incremental loads are applied to evaluate the swell pressure and consolidation.
For this assessment, we conducted four (4) swell-consolidation tests on samples recovered from
various intervals/depths. The swell index values for the samples analyzed in the overburden clayey
sand soils revealed generally low swell characteristics of approximately (-) 0.4% to (+) 2.0% at 150
and 500 psf dead loads. The laboratory swell-consolidation test results are summarized in the table
below and the swell test data sheets are provided with this report.
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TABLE I – Summary of Swell Test Results
Boring
No.
Depth
(ft) Material Type
Swell Consolidation Test Results
Dry
Density,
(pcf)
In-Situ
Moisture
Content
(%)
Inundation
Pressure
(psf)
Swell
Index
(%)
Swell
Pressure
(psf)
1 4’ Clayey Sand (SC) 109.7 6.9 500 (-) 0.4 <500
2 2’ Clayey Sand (SC) 120.8 6.9 500 (+) 2.0 2500
3 2’ Clayey Sand (SC) 119.3 7.9 150 (+) 0.8 850
4 2’ Clayey Sand (SC) 119.8 5.5 150 (+) 1.6 1200
Colorado Association of Geotechnical Engineers (CAGE) uses the following information presented
below to provide uniformity in terminology between geotechnical engineers to provide a relative
correlation of performance risk to measured swell. “The representative percent swell values are not
necessarily measured values; rather, they are a judgment of the swell of the soil and/or bedrock profile
likely to influence slab performance.” Geotechnical engineers use this information to also evaluate the
swell potential risks for foundation performance based on the risk categories.
TABLE II - Recommended Representative Swell Potential Descriptions and Corresponding
Slab Performance Risk Categories
Slab Performance Risk Category Representative Percent Swell
(500 psf Surcharge)
Representative Percent Swell
(1000 psf Surcharge)
Low 0 to < 3 0 < 2
Moderate 3 to < 5 2 to < 4
High 5 to < 8 4 to < 6
Very High > 8 > 6
Base on the laboratory test results, the swell samples analyzed for this project at current moisture
contents and dry densities conditions were generally in the low range.
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Site Preparation
Prior to placement of any fill and/or improvements, we recommend any existing vegetation, topsoil,
undocumented fill, trees and associated roots, and any unsuitable materials be removed from the
planned improvement areas. In the areas of the existing park improvements to be removed, all
existing elements should be removed. Care should be taken to remove any previously placed fill
material with unknown origin or compaction verification. In addition, we recommend two feet of
subgrade materials be overexcavated below floor slabs, exterior flatwork and pavement areas below
current grades as a swell-mitigation approach. After removal of all topsoil/vegetation within the
planned development areas, as well as removal of unacceptable or unsuitable subsoils and removal
of overexcavation materials, and prior to placement of fill, floor slabs and pavements, the exposed
soils should be scarified to a depth of 9 inches, adjusted in moisture content to within (+/-) 2% of
standard Proctor optimum moisture content and compacted to at least 95% of the material's standard
Proctor maximum dry density as determined in accordance with ASTM Specification D698.
Fill materials used to replace the overexcavated zone and establish grades in the floor slab, flatwork
and pavement areas, after the initial zone has been prepared as recommended above, should consist
of approved on-site clayey sand, similar import material or approved structural fill material which is
free from organic matter and debris. If on-site cohesive subsoils or similar import materials are used
as engineered fill, they should be placed in maximum 9-inch loose lifts, moisture conditioned and
compacted as recommended for the scarified soils. If structural fill materials are used they should be
graded similarly to a CDOT Class 5, 6 or 7 aggregate base with sufficient fines to prevent ponding
of water within the fill. Structural fill material should be placed in loose lifts not to exceed 9 inches
thick, adjusted to a workable moisture content and compacted to at least 95% of standard Proctor
maximum dry density as determined by ASTM Specification D698.
Fill soils to develop the floor slab, flatwork, pavement and site subgrades should consist of
approved, low-volume-change materials, which are free from organic matter and debris. It is our
opinion the on-site near surface soils, similar import fill soils, or import structural fill could be used
as fill in these areas, provided adequate moisture treatment and compaction procedures are followed.
We recommend fill soils be placed in loose lifts not to exceed 9 inches thick and adjusted in
moisture content and compacted as recommended for the scarified and/or backfill soils. If the site
clayey sand soils are used as fill material, care will be needed to maintain the recommended
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moisture content and densities prior to and during construction of overlying improvements.
Subgrade soils allowed to become dry or densified by construction traffic may show increased swell
potential.
Care should be exercised after preparation of the subgrades to avoid disturbing the subgrade
materials. Positive drainage should be developed away from the structures, flatwork and pavements
to avoid wetting of subgrade materials. Subgrade materials becoming wet subsequent to
construction of the site improvements can result in unacceptable performance.
Footing Foundations
It is our opinion the proposed building could be supported on conventional footing foundations bearing
on approved on-site native subgrade soils or a zone of approved/placed and compacted engineered fill.
For design of footing foundations supported on properly placed and compacted engineered fill as
outlined in the section “Site Preparation” or on approved native subgrade soils, we recommend using a
maximum net allowable total load soil bearing pressure of 2,000 psf. The net bearing pressure refers to
the pressure at foundation bearing level in excess of the minimum surrounding overburden pressure.
Total load would include full dead and live loads.
Exterior foundations and foundations in unheated areas should be located at least 30 inches below
adjacent exterior grades to provide frost protection. Formed continuous footings should have a
minimum width of 16 inches and isolated column foundations should have a minimum width of 30
inches.
Care should be taken to thoroughly evaluate anticipated bearing materials at the time of construction.
All footings for the structures should bear on uniform/similar materials to reduce the potential for
differential movement between soil types. We estimate the long term settlement of footings designed
and constructed as outlined would be less than 1-inch.
Seismic
The site soil conditions generally consist of very stiff clayey sand with underlying dense to very
dense silty sand and gravel materials to the depths explored in borings B-3 and B-4, approximately
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10 feet below site grades, or to the underlying sandstone/siltstone bedrock in borings B-1 and B-2 at
approximate depths of 10 to 14 feet below existing site grades. For those site conditions, the 2012
International Building Codes indicates a Seismic Site Classification of C.
Floor Slabs, Flatwork and Pavement Subgrades
Subgrades for floor slabs, flatwork and site pavements should be prepared as outlined in the “Site
Preparation” section of this report. We estimate the long-term movement of floor slabs with
properly prepared subgrade subsoils as outlined above would be about one-inch or less assuming
reasonable moisture accumulation in the subgrade materials. Excessive moisture accumulation from
any source can result in additional movements.
For structural design of concrete slabs-on-grade, a modulus of subgrade reaction of 75 pounds per
cubic inch (pci) may be used for floors supported on a zone of reconditioned engineered fill.
Additional floor slab design and construction recommendations are as follows:
Positive separations and/or isolation joints should be provided between slabs and all
foundations, columns or utility lines to allow independent movement.
Control joints should be provided in slabs to control the location and extent of
cracking.
Interior trench backfill placed beneath slabs should be compacted in a similar manner
as previously described for on-site or imported structural fill material.
Floor slabs should not be constructed on frozen subgrade.
Other design and construction considerations, as outlined in the ACI Design Manual,
Section 302.1R are recommended.
Pavements
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.
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Proofrolling and recompacting the subgrade is recommended immediately prior to placement of the
aggregate road base section. Soft or weak areas delineated by the proofrolling operations should be
undercut or stabilized in-place to achieve the appropriate subgrade support. 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
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.
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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.
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Soil Corrosivity
The water soluble sulfate (SO4) testing of the near surface on-site overburden material taken during
our subsurface exploration is provided in the table below. Based on the reported 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 subsoils.
TABLE IV - Water Soluble Sulfate Test Results
Sample Location Description
Soluble Sulfate Content
(mg/kg)
Soluble Sulfate Content
(%)
B-2, S-2 at 4’ Clayey Sand (SC) 250 0.03
B-4, S-1 at 2’ Clayey Sand (SC) 370 0.04
Based on the results as presented in the table above, ACI 318, Section 4.2 indicates the site
overburden soils have a low risk of sulfate attack on Portland cement concrete. Therefore Class 0
and/or Type I/II cement could be used for concrete on and below site grade within the overburden
soils. Foundation concrete should be designed in accordance with the provisions of the ACI Design
Manual, Section 318, Chapter 4. These results are being compared to the following table.
TABLE V - Requirements to Protect Against Damage to Concrete by Sulfate Attack from External Sources of
Sulfate
Severity of Sulfate
exposure
Water-soluble sulfate (SO4)
in dry soil, percent
Water-cement ratio,
maximum
Cementatious material
Requirements
Class 0 0.00 to 0.10% 0.45 Class 0
Class 1 0.11 to 0.20% 0.45 Class 1
Class 2 0.21 to 2.00% 0.45 Class 2
Class 3 2.01 of greater 0.45 Class 3
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, (if required), adjacent to the buildings to
avoid features which would pond water adjacent to the foundations or stemwalls. Placement of
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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.
Excavations into the on-site clayey sand can be expected to stand on relatively steep, temporary
slopes during construction. Deeper excavations into the underlying silty sand with gravel have the
potential for caving/sloughing side walls. 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 Blue Ocean Real Estate Management, LLC 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
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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-1
B-2
B-4
B-3
Boring Location Diagram
Jefferson & Linden St Development
Fort Collins, Colorado
EEC Project Number: 1162014 Date: February 2016
EARTH ENGINEERING CONSULTANTS, LLC
Approximate Boring
Locations
1
Legend
Site Photos
(Photos taken in approximate
location, in direction of arrow)
JEFFERSON STREET & LINDEN STREET DEVELOPMENT
FORT COLLINS, COLORADO
EEC PROJECT NO. 1162014
FEBRUARY 2016
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
SPARSE VEGETATION _ _
1
CLAYEY SAND (SC) _ _
brown 2
very stiff _ _
3
_ _
4
_ _
CS 5 21 9000+ 6.9 116.9 24 9 41.8 <500 psf None
_ _
SILTY SAND & GRAVEL (SM/GM) 6
brown / tan _ _
dense to very dense 7
with cobbles _ _
8
_ _
9
_ _
SS 10 50/11" -- 2.3
_ _
11
SANDSTONE / SILTSTONE _ _
brown / grey / rust 12
cemented / hard _ _
13
_ _
14
_ _
SS 15 50/6" -- 13.9
_ _
16
_ _
17
_ _
18
_ _
19
grey _ _
CS 20 50/1" 9000+ 12.1
BOTTOM OF BORING DEPTH 20.0' _ _
21
_ _
22
_ _
23
_ _
24
_ _
25
_ _
Earth Engineering Consultants, LLC
JEFFERSON STREET & LINDEN STREET 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
SPARSE VEGETATION _ _
1
CLAYEY SAND (SC) _ _
brown 2
very stiff _ _
CS 3 22 9000+ 6.9 108.7 27 11 44.2 2500 psf 2.0%
_ _
4
_ _
SS 5 34 -- 2.0
SILTY SAND & GRAVEL (SM/GM) _ _
brown / tan 6
dense to very dense _ _
with cobbles 7
_ _
8
_ _
9
_ _
SS 10 50 5000 13.5
_ _
11
_ _
12
_ _
13
_ _
14
_ _
SANDSTONE / SILTSTONE 15
grey _ _
well cemented / hard 16
_ _
17
_ _
18
_ _
19
_ _
SS 20 50/1.5" -- 11.9
_ _
21
_ _
22
_ _
23
_ _
24
_ _
CS 25 50/0.75"
Continued on Sheet 2 of 2 _ _
Earth Engineering Consultants, LLC
JEFFERSON STREET & LINDEN STREET 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
_ _
SANDSTONE / SILTSTONE 27
grey _ _
well cemented / hard 28
_ _
29
_ _
SS 30 50/1" -- 12.0
_ _
BOTTOM OF BORING DEPTH 30.5' 31
_ _
32
_ _
33
_ _
34
_ _
35
_ _
36
_ _
37
_ _
38
_ _
39
_ _
40
_ _
41
_ _
42
_ _
43
_ _
44
_ _
45
_ _
46
_ _
47
_ _
48
_ _
49
_ _
50
_ _
Earth Engineering Consultants, LLC
JEFFERSON STREET & LINDEN STREET 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
ASPHALT - 2" _ _
BASE - 3.5" 1
_ _
CLAYEY SAND (SC) 2
brown _ _ % @ 150 psf
very stiff CS 3 16 8000 7.9 118.0 850 psf 0.8%
with gravels _ _
4
_ _
SS 5 36 -- 2.5
SILTY SAND & GRAVEL (SM/GM) _ _
brown / tan 6
dense to very dense _ _
7
_ _
8
_ _
9
_ _
SS 10 50/9"
_ _
BOTTOM OF BORING DEPTH 10.5' 11
_ _
12
_ _
13
_ _
14
_ _
15
_ _
16
_ _
17
_ _
18
_ _
19
_ _
20
_ _
21
_ _
22
_ _
23
_ _
24
_ _
25
_ _
Earth Engineering Consultants, LLC
JEFFERSON STREET & LINDEN STREET 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
SPARSE VEGETATION _ _
CLAYEY SAND (SC) 1
brown _ _
very stiff 2
with gravels _ _ % @ 150 psf
CS 3 24 9000+ 5.5 116.5 22 8 30.1 1200 psf 1.6%
_ _
4
_ _
SS 5 44 9000+ 6.8
SILTY SAND & GRAVEL (SM/GM) _ _
brown / tan 6
dense to very dense _ _
with cobbles 7
_ _
8
_ _
9
_ _
SS 10 50/10" -- 1.5
_ _
BOTTOM OF BORING DEPTH 10.5' 11
_ _
12
_ _
13
_ _
14
_ _
15
_ _
16
_ _
17
_ _
18
_ _
19
_ _
20
_ _
21
_ _
22
_ _
23
_ _
24
_ _
25
_ _
Earth Engineering Consultants, LLC
JEFFERSON STREET & LINDEN STREET DEVELOPMENT
Project:
Location:
Project #:
Date:
Jefferson Street & Linden Street Development
Fort Collins, Colorado
1162014
February 2016
Beginning Moisture: 6.9% Dry Density: 109.7 pcf Ending Moisture: 18.2%
Swell Pressure: <500 psf % Swell @ 500: None
Sample Location: Boring 1, Sample 1, Depth 4'
Liquid Limit: 24 Plasticity Index: 9 % Passing #200: 41.8%
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
Project:
Location:
Project #:
Date:
Jefferson Street & Linden Street Development
Fort Collins, Colorado
1162014
February 2016
Beginning Moisture: 6.9% Dry Density: 120.8 pcf Ending Moisture: 16.2%
Swell Pressure: 2500 psf % Swell @ 500: 2.0%
Sample Location: Boring 2, Sample 1, Depth 2'
Liquid Limit: 27 Plasticity Index: 11 % Passing #200: 44.2%
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
Project:
Location:
Project #:
Date:
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown Clayey Sand (SC)
Sample Location: Boring 3, Sample 1, Depth 2'
Liquid Limit: - - Plasticity Index: - - % Passing #200: - -
Beginning Moisture: 7.9% Dry Density: 119.3 pcf Ending Moisture: 13.0%
Swell Pressure: 850 psf % Swell @ 150: 0.8%
Jefferson Street & Linden Street Development
Fort Collins, Colorado
1162014
February 2016
-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:
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown Clayey Sand (SC)
Sample Location: Boring 4, Sample 1, Depth 2'
Liquid Limit: 22 Plasticity Index: 8 % Passing #200: 30.1%
Beginning Moisture: 5.5% Dry Density: 119.8 pcf Ending Moisture: 15.8%
Swell Pressure: 1200 psf % Swell @ 150: 1.6%
Jefferson Street & Linden Street Development
Fort Collins, Colorado
1162014
February 2016
-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
6" (152.4 mm)
5" (127 mm)
4" (101.6 mm)
3" (76 mm)
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: Jefferson & Linden Street
Location: Fort Collins, Colorado
Project No: 1162014
Sample ID: B-1, S-2, 9'
Sample Desc.: Silty Sand & Gravel (SM/GM)
Date: March 2016
57
53
49
36
19.4
91
82
74
72
65
100
100
100
100
95
100
100
100
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
Gravel
Coarse Fine
Sand
Coarse Medium Fine
EARTH ENGINEERING CONSULTANTS, LLC
Summary of Washed Sieve Analysis Tests (ASTM C117 & C136)
Date:
Jefferson & Linden Street
Fort Collins, Colorado
1162014
B-1, S-2, 9'
Silty Sand & Gravel (SM/GM)
March 2016
Project:
Location:
Project No:
Sample ID:
Sample Desc.:
Cobble Silt or Clay
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
Fines by Weight (%)
Grain Size (mm)
Standard Sieve Size
FORT COLLINS, COLORADO
PROJECT NO: 1162014 LOG OF BORING B-4 FEBRUARY 2016
SHEET 1 OF 1 WATER DEPTH
START DATE 2/24/2016 WHILE DRILLING None
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 2/24/2016 AFTER DRILLING N/A
A-LIMITS SWELL
FORT COLLINS, COLORADO
PROJECT NO: 1162014 LOG OF BORING B-3 FEBRUARY 2016
SHEET 1 OF 1 WATER DEPTH
START DATE 2/24/2016 WHILE DRILLING None
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 2/24/2016 AFTER DRILLING N/A
A-LIMITS SWELL
PROJECT NO: 1162014 LOG OF BORING B-2 FEBRUARY 2016
SHEET 2 OF 2 WATER DEPTH
START DATE 2/24/2016 WHILE DRILLING None
2/24/2016 AFTER DRILLING N/A
SURFACE ELEV 24 HOUR N/A
FINISH DATE
A-LIMITS SWELL
N/A
FORT COLLINS, COLORADO
PROJECT NO: 1162014 LOG OF BORING B-2 FEBRUARY 2016
SHEET 1 OF 2 WATER DEPTH
START DATE 2/24/2016 WHILE DRILLING None
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 2/24/2016 AFTER DRILLING N/A
A-LIMITS SWELL
FORT COLLINS, COLORADO
PROJECT NO: 1162014 LOG OF BORING B-1 FEBRUARY 2016
SHEET 1 OF 1 WATER DEPTH
START DATE 2/24/2016 WHILE DRILLING None
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 2/24/2016 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