HomeMy WebLinkAboutNORTH COLLEGE DRIVE THRU - PDP - PDP160014 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTGEOTECHNICAL EXPLORATION REPORT
PROPOSED 2500 SF FAST FOOD RESTAURANT WITH DRIVE-THRU
1603-1605 NORTH COLLEGE AVENUE
FORT COLLINS, COLORADO
EEC PROJECT NO. 1162019
Prepared for:
OPM Holdings, LLC
C/o Peak to Peak Properties
P.O. Box 102291
Denver, Colorado 80250
Attn: Mr. Chad Hirschfield (chirschfield@peaktopeakprop.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 22, 2016
OPM Holdings, LLC
C/o Peak to Peak Properties
P.O. Box 102291
Denver, Colorado 80250
Attn: Mr. Chad Hirschfield (chirschfield@peaktopeakprop.com)
Re: Geotechnical Exploration Report
Proposed 2500 SF Fast Food Restaurant with Drive-Thru
1603-1605 North College Avenue
Fort Collins, Colorado
EEC Project No. 1162019
Mr. Hirschfield:
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 20 feet below existing site grades within the proposed
improvement areas. This subsurface exploration was completed in general accordance with our
proposal dated February 25, 2016.
In summary, the subsurface conditions encountered in the test borings generally consisted of 2 to
4 feet of apparent fill material which generally consisted of sandy lean clay to clayey sand with
gravel materials. Underlying the apparent surficial fill materials, was lean clay with varying
amounts of sand underlain by silty/poorly graded sand and gravel materials. The near surface
soils showed generally low to moderate swell potential. Groundwater was observed in the test
borings at the time of drilling at approximate depths of 5 to 6 feet below site grades. The borings
were backfilled upon completion of the drilling operations; therefore subsequent measurements
were not obtained.
Based on the subsurface conditions encountered in the test borings, our previous experience in
this general vicinity and the anticipated loading conditions, we believe the proposed single story
slab-on-grade building could be supported on conventional type spread footings bearing on
approved ground modified native subsoils or on a zone of approved engineered fill material. It
is our opinion floor slabs, exterior flatwork, and pavements could be supported on a zone of
overexcavated and reconditioned engineered fill material.
GEOTECHNICAL EXPLORATION REPORT
PROPOSED 2500 SF FAST FOOD RESTAURANT WITH DRIVE-THRU
1603-1605 NORTH COLLEGE AVENUE
FORT COLLINS, COLORADO
EEC PROJECT NO. 1162019
March 22, 2016
INTRODUCTION
The geotechnical subsurface exploration for the proposed development planned for construction at
1603 – 1605 North College Avenue in Fort Collins, Colorado has been completed. As a part of this
exploration, two (2) foundation related borings (borings B-1 and B-2) and two (2) pavement related
borings (borings B-3 and B-4) were drilled at the approximate locations shown on the boring
location diagram included with this report. Foundation related and pavement related soil borings
completed within the proposed improvement areas were extended to depths of approximately 20 and
10 feet below existing site grades, respectively. 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 property will be developed for an approximate 2,500 SF in plan-line dimension
fast food restaurant with drive-thru along with on-site pavement improvements. As shown on the
enclosed site plan a bioswale/detention pond concept is planned south of the building footprint.
Geotechnical recommendations can be provided upon request for this area.
The proposed structure is expected to be a single-story, slab-on-grade structure. Foundation loads
for the structure are expected to be light with continuous wall loads less than 3 kips per lineal foot
and individual column loads less than 50 kips. Floor loads are expected to be light. Paved drives
and parking areas are expected as a part of the site development with the entrance being shared with
the carwash facility to the north. The pavements are expected to carry light traffic volume consisting
predominately of automobiles and light trucks. Small grade changes, cuts and fills less than 4 feet,
are expected to develop site grades for the proposed development.
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 developments.
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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.
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 diagram.
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 sulfates was determined for two (2) samples 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
soil’s texture and plasticity. The estimated group symbol for the Unified Soil Classification System
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is indicated on the boring logs and a brief description of that classification system is included with
this report.
SITE AND SUBSURFACE CONDITIONS
The proposed fast food development project is planned for construction at 1603 – 1605 North
College Avenue. The development parcel is presently an undeveloped lot with sparse vegetation and
topsoil with occasional trees along the north end and across the middle of the proposed development
site. Ground surface in this area is relatively flat. No evidence of prior building construction was
observed in the field by EEC personnel although some site improvements along the northern portion
of the property were observed.
The near surface materials in the test borings generally consisted of sandy lean clay / clayey sand
with gravel apparent fill material on the order of 2 to 4 feet with underlying lean clay with varying
amounts of sand which was generally stiff to very stiff becoming medium stiff to soft approaching or
in the groundwater table. The cohesive soils exhibited generally low to moderate swells in
laboratory testing at in-situ moisture and density. The cohesive soils extended to approximate
depths of 7 to 8 feet below existing site grades. The cohesive soils were underlain by silty/poorly
graded sand and gravel which extended to the depths explored, approximately 10 to 20 feet below
existing grade. Bedrock was not encountered in any of the borings to the depths explored. The
granular strata was medium dense to dense in relative density and exhibited moderate bearing
capabilities.
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.
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 observed in the
borings at depths of approximately 5 to 6 feet. The borings were backfilled upon completion of the
drilling operations; therefore subsequent groundwater measurements were not performed.
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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.
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 three (3) swell-consolidation tests on samples recovered from
various intervals/depths. The swell index values for the samples analyzed in the overburden lean clay
soils revealed generally low to moderate swell characteristics of approximately (-) 0.5% to (+/-) 0.0%
at 500 psf dead load, and (+) 5.9% at 150 psf. The (+) 5.9% test result may have been within an
apparent fill material zone. The laboratory swell-consolidation test results are summarized in the table
below and the swell test data sheets are provided with this report.
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 2’ Lean Clay with Sand (CL) 110.7 18.9 500 (+/-) 0.0 <500
2 4’ Sandy Lean Clay (CL) 99.1 27.2 500 (-) 0.5 <500
3 2’ Apparent Fill Lean Clay (CL) 107.3 21.7 150 (+) 5.9 ~4200
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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 to moderate range. The higher swell
was observed in a near surface sample which was relatively dry and very stiff, classifying as lean
clay.
Site Preparation
Prior to placement of any new fill and/or improvements, we recommend any existing vegetation,
topsoil, trees, and any unsuitable apparent fill materials be removed from the planned improvement
areas. In addition, we recommend two feet of subgrade materials be overexcavated below floor
slabs, exterior flatwork and pavement areas as a swell-mitigation approach.
After removal of all topsoil/vegetation and trees/roots 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. Areas of soft/compressible cohesive
subsoils across the site may require ground stabilization procedures to create a working platform for
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construction equipment prior to placement of any additional fill. If necessary, consideration could
be given to placement of a granular material, such as a 3-inch minus pit run and/or recycled concrete
or equivalent material, embedded into the soft soils, prior to placement of additional fill material or
operating heavy earth-moving equipment. Supplemental recommendations can be provided upon
request.
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 lean clay with varying amounts of sand subsoils or approved structural fill
material which is free from organic matter and debris. If on-site cohesive subsoils 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 or similar import fill soils could be used as fill in these areas,
provided adequate moisture treatment and compaction procedures are followed. We recommend
cohesive 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 soils. If the site lean clay with varying
sand soils are used as fill material, care will be needed to maintain the recommended 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.
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Footing Foundations
It is our opinion the proposed structures could be supported on conventional footing foundations
bearing on approved on-site native subgrade soils, ground modified native subsoils, or a zone of
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 2000 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
Bedrock was not encountered in any of the borings to the depths explored, approximately 10 to 20
feet below existing site grades. For those site conditions, the 2012 International Building Codes
indicates a Seismic Site Classification of D.
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.
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For structural design of concrete slabs-on-grade, a modulus of subgrade reaction of 100 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 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 7.
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
private drives and parking areas be designed using an assumed R-value of 7.
Pumping conditions could develop within higher moisture content on-site 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 13 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
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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.
TABLE III – Recommended Minimum Pavement Sections
18-kip EDLA
18-kip ESAL
Reliability
Resilient Modulus (R-Value = 7)
PSI Loss
7
51,100
70%
3230 psi
2.5
Design Structure Number 2.49
Composite:
Hot Mix Asphalt
Aggregate Base Course
Structure Number
4" @ 0.44 = 1.76
7" @ 0.11 = 0.77
(2.53)
Composite with Fly Ash Treated Subgrade
Hot Bituminous Pavement
Aggregate Base
Fly Ash Treated Subgrade
Structure Number
3½" @ 0.44 = 1.54
4" @ 0.11 = 0.44
12" @ 0.05 = 0.60
(2.58)
PCC (Non-reinforced) – placed on a stable subgrade 5-1/2"
The recommended pavement sections are minimums and periodic maintenance should be expected.
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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:
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.
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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.
Soil Corrosivity
The water soluble sulfate (SO4) testing of the near surface on-site overburden materials 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-1 at 4’ Sandy Lean Clay (CL) 12,600 1.26
B-4, S-1 at 2’ Sandy Lean Clay (CL) 4,300 0.43
Based on the results as presented in the table above, ACI 318, Section 4.2 indicates the site
overburden soils have a high risk of sulfate attack on Portland cement concrete. Therefore Class 2
and/or Type I/II cement should be used for concrete on and below site grades 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.
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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
Utilities
Near surface, the clay soils were relatively moist and stiff to very stiff becoming wet and medium
stiff to soft approaching groundwater with depth. The underlying sands and gravels below the water
table were medium dense to dense.
We expect excavations in the upper stiff to very stiff and lower soft to medium stiff cohesive soils
would maintain relatively steep slopes over short periods of time. Deeper excavations in the
groundwater and granular soils may show unstable side slopes and bottom. Stabilization of the sides
and bottoms of the trenches and dewatering should be anticipated for the utilities. Although the
excavated soils could be used for backfilling the utility excavations, drying of those soils will likely
be necessary before the excavated material can be used for backfilling.
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.
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
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
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placed within 5 feet of the perimeter of the building and pavement/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.
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 OPM Holdings, 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 unless the changes are
reviewed and the conclusions of this report are modified or verified in writing by the geotechnical
engineer.
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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
1603-1605 N. COLLEGE AVENUE
FORT COLLINS, COLORADO
EEC PROJECT NO. 1162019
MARCH 2016
1
2
B-1
B-2
B-4
B-3
Boring Location Diagram
1603-1605 North College Ave
Fort Collins, Colorado
EEC Project Number: 1162019 Date: March 2016
EARTH ENGINEERING CONSULTANTS, LLC
Approximate Boring
Locations
1
Legend
Site Photos
(Photos taken in approximate
location, in direction of arrow)
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 _ _
SANDY LEAN CLAY / CLAYEY SAND (CL/SC) - FILL 1
brown _ _
with gravel 2
_ _
CS 3 8 5500 18.9 108.1 36 22 84.5 <500 psf None
LEAN CLAY with SAND (CL) _ _
brown 4
stiff to soft _ _
SS 5 2 1000 22.2
_ _
6
_ _
7
_ _
8
_ _
SAND & GRAVEL (SP/GP) 9
brown / red / grey _ _
with cobbles SS 10 50/11" -- 7.8 4.9
dense to very dense _ _
11
_ _
12
_ _
13
_ _
14
_ _
SS 15 27 -- 15.8
_ _
16
_ _
17
_ _
18
_ _
19
_ _
SS 20 50 -- 11.3
_ _
BOTTOM OF BORING DEPTH 20.5' 21
_ _
22
_ _
23
_ _
24
_ _
25
_ _
Earth Engineering Consultants, LLC
1603 - 1605 NORTH COLLEGE AVENUE
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
SPARSE VEGETATION _ _
1
SANDY LEAN CLAY / CLAYEY SAND (CL/SC) - FILL _ _
brown 2
with gravel _ _
3
_ _
4
_ _
SANDY LEAN CLAY (CL) CS 5 7 1000 27.2 97.6 33 14 66.4 <500 psf None
brown _ _
stiff 6
with calcareous deposits _ _
7
_ _
8
_ _
SAND & GRAVEL (SP/GP) 9
brown / red / grey _ _
with cobbles SS 10 50/10" -- 14.0
dense to very dense _ _
11
_ _
12
_ _
13
_ _
14
_ _
SS 15 43 -- 13.1
_ _
16
_ _
17
_ _
18
_ _
19
_ _
SS 20 -- -- 14.4
_ _
BOTTOM OF BORING DEPTH 20.5' 21
_ _
22
_ _
23
_ _
24
_ _
25
_ _
Earth Engineering Consultants, LLC
1603 - 1605 NORTH COLLEGE AVENUE
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 _ _
SANDY LEAN CLAY / CLAYEY SAND (CL/SC) - FILL 1
brown _ _
with gravel 2
_ _ % @ 150 PSF
CS 3 15 9000 17.8 107.3 41 24 92.0 ~4200 psf 5.9%
LEAN CLAY (CL) _ _
brown 4
very stiff to soft _ _
SS 5 2 -- 25.2
_ _
6
_ _
7
_ _
8
_ _
9
SAND & GRAVEL (SP/GP) _ _
brown / red / grey SS 10 50 -- 12.1 11.2
dense _ _
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
1603 - 1605 NORTH COLLEGE AVENUE
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 _ _
SANDY LEAN CLAY / CLAYEY SAND (CL/SC) - FILL 1
brown _ _
with gravel 2
_ _
CS 3 19 9000+ 16.8 116.0
SANDY LEAN CLAY (CL) _ _
brown 4
very stiff to medium stiff _ _
SS 5 4 1000 24.2
_ _
with traces of gravel 6
_ _
7
_ _
SAND & GRAVEL 8
brown / red / grey _ _
with cobbles 9
dense _ _
SS 10 50 -- 13.4
_ _
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
1603 - 1605 NORTH COLLEGE AVENUE
Project:
Location:
Project #:
Date:
1603 - 1605 North College Avenue
Fort Collins, Colorado
1162019
March 2016
Beginning Moisture: 18.9% Dry Density: 110.7 pcf Ending Moisture: 19.2%
Swell Pressure: <500 psf % Swell @ 500: None
Sample Location: Boring 1, Sample 1, Depth 2'
Liquid Limit: 36 Plasticity Index: 22 % Passing #200: 84.5%
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown Lean Clay with Sand (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:
1603 - 1605 North College Avenue
Fort Collins, Colorado
1162019
March 2016
Beginning Moisture: 27.2% Dry Density: 99.1 pcf Ending Moisture: 23.2%
Swell Pressure: <500 psf % Swell @ 500: None
Sample Location: Boring 2, Sample 1, Depth 4'
Liquid Limit: 33 Plasticity Index: 14 % Passing #200: 66.4%
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown Sandy Lean CLay (CL)
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
10.0
0.01 0.1 1 10
Percent Movement
Load (TSF)
Consolidatio Swell
Water Added
Project:
Location:
Project #:
Date:
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown Lean Clay (CL)
Sample Location: Boring 3, Sample 1, Depth 2'
Liquid Limit: 41 Plasticity Index: 24 % Passing #200: 92.0%
Beginning Moisture: 17.8% Dry Density: 107.3 pcf Ending Moisture: 21.7%
Swell Pressure: ~4200 psf % Swell @ 150: 5.9%
1603 - 1605 North College Avenue
Fort Collins, Colorado
1162019
March 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
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: 1603 - 1605 North College Avenue
Location: Fort Collins, Colorado
Project No: 1162019
Sample ID: B-1, S-3, 9'
Sample Desc.: Bown / Red / Grey Sand & Gravel (SP/GP)
Date: March 2016
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
83
79
64
56
42
32
30
26
18
14
11
7
4.9
EARTH ENGINEERING CONSULTANTS, LLC
Summary of Washed Sieve Analysis Tests (ASTM C117 & C136)
Date:
1603 - 1605 North College Avenue
Fort Collins, Colorado
1162019
B-1, S-3, 9'
Bown / Red / Grey Sand & Gravel (SP/GP)
March 2016
Project:
Location:
Project No:
Sample ID:
Sample Desc.:
Cobble Silt or Clay
Gravel
Coarse Fine
Sand
Coarse Medium Fine
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
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: 1603 - 1605 North College Avenue
Location: Fort Collins, Colorado
Project No: 1162019
Sample ID: B-3, S-3, 9'
Sample Desc.: Sand & Gravel (SP/GP)
Date: March 2016
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
84
79
71
69
62
49
46
38
28
24
21
16
11.2
EARTH ENGINEERING CONSULTANTS, LLC
Summary of Washed Sieve Analysis Tests (ASTM C117 & C136)
Date:
1603 - 1605 North College Avenue
Fort Collins, Colorado
1162019
B-3, S-3, 9'
Sand & Gravel (SP/GP)
March 2016
Project:
Location:
Project No:
Sample ID:
Sample Desc.:
Cobble Silt or Clay
Gravel
Coarse Fine
Sand
Coarse Medium Fine
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: 1162019 LOG OF BORING B-4 MARCH 2016
SHEET 1 OF 1 WATER DEPTH
START DATE 3/8/2016 WHILE DRILLING 6'
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 3/8/2016 AFTER DRILLING N/A
A-LIMITS SWELL
FORT COLLINS, COLORADO
PROJECT NO: 1162019 LOG OF BORING B-3 MARCH 2016
SHEET 1 OF 1 WATER DEPTH
START DATE 3/8/2016 WHILE DRILLING 5.5'
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 3/8/2016 AFTER DRILLING N/A
A-LIMITS SWELL
FORT COLLINS, COLORADO
PROJECT NO: 1162019 LOG OF BORING B-2 MARCH 2016
SHEET 1 OF 1 WATER DEPTH
START DATE 3/8/2016 WHILE DRILLING 5.5-6'
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 3/8/2016 AFTER DRILLING N/A
A-LIMITS SWELL
FORT COLLINS, COLORADO
PROJECT NO: 1162019 LOG OF BORING B-1 MARCH 2016
SHEET 1 OF 1 WATER DEPTH
START DATE 3/8/2016 WHILE DRILLING 5.5'
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 3/8/2016 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