HomeMy WebLinkAboutKAPPA KAPPA GAMMA ADDITION - BASIC DEVELOPMENT REVIEW - BDR170015 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTSUBSURFACE EXPLORATION REPORT
PROPOSED EXPANSION TO THE EXISTING KAPPA KAPPA GAMMA SORORITY
729 SOUTH SHEILDS STREET
FORT COLLINS, COLORADO
EEC PROJECT NO. 1172062
Prepared for:
Reliance Construction Consulting
201 Commerce Drive – Unit 1
Fort Collins, Colorado 80524
Attn: Mr. Greg Orr (greg@relianceconstructionconsulting.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
August 22, 2017
Reliance Construction Consulting
201 Commerce Drive – Unit 1
Fort Collins, Colorado 80524
Attn: Mr. Greg Orr (greg@relianceconstructionconsulting.com)
Re: Subsurface Exploration Report
Proposed Expansion to the Existing Kappa Kappa Gamma Sorority
729 South Shields Street
Fort Collins, Colorado
EEC Project No. 1172062
Mr. Orr:
Enclosed, herewith, are the results of the subsurface exploration completed by Earth Engineering
Consultants, LLC (EEC) for the referenced project. For this exploration, three (3) soil borings
were extended to depths of approximately 10 to 35 feet below existing site grades. Soil borings
B-1 and B-2 were extended within the proposed building foundation footprint, while boring B-3
was extended within the proposed parking lot improvement area. This subsurface exploration
was completed in general accordance with our proposal dated August 1, 2017.
In summary, the subsurface conditions encountered in the test borings beneath the surficial
topsoil/vegetation layer in boring B-2 and the existing pavement section in borings B-1 and B-3,
generally consisted of overburden cohesive to slightly cohesive subsoils classified as either lean
clay with sand, sandy lean clay and/or clayey sand with trace amounts of gravel, which extended
to the underlying bedrock formation in boring B-1 and to a layer of sands and gravels with
intermittent clay seams in borings B-2 and B-3. Sedimentary sandstone/siltstone/claystone
bedrock was encountered in the general vicinity of boring B-1 at an approximate depth of 18 feet
below existing site grades and extended to the depths explored, approximately 35 feet. Granular
sands and gravels were encountered in borings B-2 and B-3 at approximate depths of 2 to 19 feet
and extended to the depths explored.
As presented on the enclosed boring logs, B-1 and B-3 were located within an existing paved
area and the surficial pavement section consisted of approximately 2 inches of existing asphaltic
concrete/hot mix asphalt (HMA), underlain by approximately 6 inches of existing aggregate base
course (ABC) material in the general vicinity of B-3 with no apparent ABC found in B-1. The
SUBSURFACE EXPLORATION REPORT
PROPOSED EXPANSION TO THE EXISTING KAPPA KAPPA GAMMA SORORITY
729 SOUTH SHEILDS STREET
FORT COLLINS, COLORADO
EEC PROJECT NO. 1172062
August 22, 2017
INTRODUCTION
The geotechnical subsurface exploration for the proposed building addition, planned for construction
adjacent to the existing single to two-story structure located at 729 South Shields 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) and one (1) pavement related boring were drilled at the approximate
locations as shown on the enclosed boring location diagrams included with this report. The
foundation related soil borings completed within the proposed building additions were extended to
depths of approximately 20 to 35 feet below existing site grades and the pavement boring was
extended to an approximate depth of 10 feet below existing site grades.
We understand for this phase of the project, the proposed expansion is expected to be an
approximate 3,650 square foot (SF), in plan dimensions, two-story addition having slab-on-grade
construction, as well as exterior pavement improvements. Foundation loads for the planned
additions are expected to be light to moderate with continuous wall loads less than 4 kips per lineal
foot and individual column loads less than 75 kips. Floor loads are expected to be light to moderate.
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 and exterior
flatwork/pavement improvements for the proposed development.
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.
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The test borings were completed using a truck mounted, CME-75 drill rig equipped with a hydraulic
head employed in drilling and sampling operations. The boreholes were advanced using 4-inch
nominal diameter continuous flight augers. Samples of the subsurface materials encountered in the
borings were obtained using split barrel and California barrel sampling procedures in general
accordance with ASTM Specifications D1586 and D3550, respectively.
In the split barrel and California barrel sampling procedures, standard sampling spoons are advanced
into the ground by means of a 140-pound hammer falling a distance of 30 inches. The number of
blows required to advance the split barrel and California barrel samplers is recorded and is used to
estimate the in-situ relative density of cohesionless soils and, to a lesser degree of accuracy, the
consistency of cohesive soils and hardness of weathered bedrock. In the California barrel sampling
procedure, relatively intact samples are obtained in removable brass liners. All samples obtained in
the field were sealed and returned to our laboratory for further examination, classification and
testing.
Laboratory moisture content tests were completed on each of the recovered samples. Atterberg
limits and washed sieve analysis tests were completed on selected samples to evaluate the quantity
and plasticity of fines in the subgrade. 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. Results of the outlined tests are indicated on the attached boring logs, summary
sheets, and/or included herein.
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
is indicated on the boring logs and a brief description of that classification system is included with
this report. Classification of the bedrock was based on visual and tactual observation of disturbed
samples and auger cuttings. Coring and/or petrographic analysis may reveal other rock types.
SITE AND SUBSURFACE CONDITIONS
The proposed building addition is currently planned for construction on the west side of the existing
building located at 729 South Shields Street. The parcel is presently a sorority development lot with
an existing asphaltic concrete paved parking area and mature landscaping. Ground surface in this
area is relatively flat.
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In summary, the subsurface conditions encountered in the test borings beneath the surficial
topsoil/vegetation layer in boring B-2 and the existing pavement section in borings B-2 and B-3,
generally consisted of overburden cohesive to slightly cohesive subsoils classified as either lean clay
with sand, sandy lean clay and/or clayey sand with trace amounts of gravel, which extended to the
underlying bedrock formation in boring B-1 and to a layer of sands and gravels with intermittent
clay seams in borings B-2 and B-3. Sedimentary sandstone/siltstone/claystone bedrock was
encountered in the general vicinity of boring B-1 at an approximate depth of 18 feet below existing
site grades and extended to the depths explored, approximately 35 feet. Granular sands and gravels
were encountered in borings B-2 and B-3 at approximate depths of 2 to 19 feet and extended to the
depths explored. As presented on the enclosed boring logs, B-1 and B-3 were located within an
existing paved area and the surficial pavement section consisted of approximately 2 inches of
existing asphaltic concrete/hot mix asphalt (HMA), underlain by approximately 6 inches of existing
aggregate base course (ABC) material in the general vicinity of B-3 with no apparent ABC found in
B-1. The near surface cohesive to slightly cohesive subsoils exhibited low swell potential,
intermitted loose/soft lenses, and low bearing capacity characteristics. The underlying sands and
gravels in borings B-2 and B-3 exhibited no swell potential, and moderate to high bearing capacity
characteristics and the underlying bedrock in B-1 exhibited low swell potential.
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 water was observed in boring B-1 at
an approximate depth of 20 feet below existing site grades. Groundwater was not observed in
borings B-2 or B-3 which were drilled to approximate depths of 20 and 10 feet respectively. The
borings were backfilled upon completion of the drilling operations; 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. We have typically noted
deepest groundwater levels in late winter and shallowest groundwater levels in mid to late summer.
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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 intact
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 response.
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
clay/clayey sand subsoils and underlying bedrock revealed generally low swell characteristics of
approximately (-) 0.8% to (+) 0.4% at 500 psf and 1000 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.
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) 99.9 11.6 500 (-) 0.1 <500
1 24 Sandstone/Siltstone/Claystone 150.0 9.7 1000 (+) 0.4 2000
2 1 Lean Clay with Sand (CL) 115.7 16.5 500 (+) 0.0 <500
2 9 Lean Clay with Sand (CL) 112.0 16.6 500 (-) 0.8 <500
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
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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 density conditions were generally in the low range.
Site Preparation
Prior to placement of any fill and/or improvements, we recommend any existing topsoil, vegetation,
flatwork, pavements, and undocumented fill, and any unsuitable materials be removed from the
planned improvement areas. Care should be taken to remove any previously placed fill material,
especially adjacent to the existing building, with unknown origin or compaction verification. If trees
are removed, care should be taken to remove all roots and any soils disturbed or dry and desiccated
surrounding the root system. After removal of all topsoil, vegetation, and unacceptable or unsuitable
subsoils and prior to placement of fill, and floor slabs, 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 over excavation areas and to develop site grades in the floor slab,
and flatwork areas, after the initial zone has been prepared as recommended above, should consist of
approved on-site subsoils, similar imported material or approved imported 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. Care will be needed to maintain
the recommended moisture content and densities prior to and during construction of overlying
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improvements. Subgrade soils allowed to become dry or densified by construction traffic may show
increased swell potential. 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.
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
Due to possible variation of subsoils across the site, in-situ characteristics of foundation bearing
strata materials, and intermittent loose/soft lenses of subsoils, we recommend the foundation bearing
zone be over excavated a minimum depth of 2 feet below foundation bearing elevations and be
replaced as approved engineered fill material. All foundations should bear on uniform type subsoils
to minimize the potential for differential movement of dissimilar soils types.
Over excavation should extend laterally beyond all edges of the footings, where practical, at least 8
inches per foot of over excavation depth below footing base elevation. The over excavation should
then be backfilled up to the footing base elevation with approved engineered fill material. In our
opinion, the on-site subsoils are suitable for reuse as the engineered fill zone provided the materials
are properly moisture conditioned. The engineered fill material should be placed in uniform lifts of 9
inches or less in loose thickness and compacted to at least 95% of the material's standard Proctor
maximum dry density (ASTM Specification D698). The over excavation and backfill procedure is
illustrated in the following figure.
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Prior to placement and compaction of the engineered fill material an open-hole/foundation
excavation observation should be performed to observe the existing subsoils below the fill zone to
determine if additional over excavation is necessary.
Footings bearing on a zone of approved engineered fill material as described above could be
designed for a maximum net allowable total load soil bearing pressure of 2,000 psf. A minimum
dead load pressure would not be required. The net bearing pressure refers to the pressure at
foundation bearing level in excess of the minimum surrounding overburden pressure. Total load
includes full dead load and live load conditions.
We estimate the long-term settlement of footing foundations supported on a minimum 2-foot zone of
approved engineered fill material and designed and constructed as outlined above would be about 1
inch or less. Differential settlement could be expected between the new additions and the existing
building. The differential settlement could approach the expected total settlement. Steps should be
taken to accommodate the anticipated differential settlement between the existing building and the
new addition. Exterior foundations and foundations in unheated areas should be located a minimum
of 30 inches below adjacent exterior grade to provide frost protection.
Care should be taken during construction to see that the footing foundations are supported on
suitable strength approved/engineered fill material. In areas immediately adjacent to the existing
structure, previously placed backfill materials may be encountered beneath the foundation bearing
levels. Extra care should be taken in evaluating the in-place soils in these areas as the backfill
materials are commonly not placed for future support of foundations. If unacceptable materials are
encountered at the time of construction, it may be necessary to extend the footing foundations to
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bear below the unacceptable materials or to remove and replace a portion or all of the unacceptable
materials. Those conditions can best be evaluated in open excavations at the time of construction.
No unusual problems are anticipated in completing the excavation required for construction of the
footing foundations. Care should be taken during construction to avoid disturbing the foundation
bearing materials. Materials which are loosened or disturbed by the construction activities or
materials which become dry and desiccated or wet and softened should be removed and replaced
prior to placement of foundation concrete.
Seismic
The site soil conditions generally consist of cohesive to slightly cohesive clay/clayey sand subsoils
and underlying sands and gravels which extended to the depths explored, and/or to the underlying
bedrock formation at depths of approximately 18 feet in B-1. Therefore, for those site conditions, the
2015 International Building Codes indicates a Seismic Site Classification of D.
Floor Slabs, Flatwork, and Pavement Subgrades
All existing vegetation/topsoil, existing pavement materials and any uncontrolled/unsuitable fill
materials, should be removed from beneath the new floor slabs. Soft or loose in-place fill/backfill
associated with prior building or utility construction, and any wet and softened or dry and desiccated
soils should be removed from the floor areas.
After stripping, completing all cuts and removal of any unacceptable materials and prior to
placement of any fill or floor slabs, the in-place soils should be scarified to a minimum depth of 9
inches, adjusted in moisture content and compacted to at least 95% of maximum dry density as
determined in accordance with ASTM Specification D698, the standard Proctor procedure. The
moisture content of the scarified materials should be adjusted to be within the range of 2% of
standard Proctor optimum moisture at the time of compaction.
Fill materials required to develop the floor slab subgrade should consist of approved, low-volume
change materials which are free from organic matter and debris. We recommend the fill materials
contain sufficient fines to prevent ponding of water in the subgrade subsequent to construction. The
on-site clay materials may be evaluated for reuse as acceptable engineered fill material for use in the
floor slab subgrade areas. Fill materials beneath the floor slabs should be placed in loose lifts not to
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exceed 9 inches thick, adjusted in moisture content as recommended for the scarified materials and
compacted to at least 95% of the material's standard Proctor maximum dry density.
After preparation of the subgrades, care should be taken to avoid disturbing the subgrade materials.
Materials which are loosened or disturbed by the construction activities may require removal and
replacement or reworking in place prior to placement of the overlying floor slabs, flatwork, or
pavement sections. Positive drainage should be developed away from the proposed building
addition to avoid wetting the subgrade or bearing materials. Subgrade or bearing materials allowed
to become wetted subsequent to construction can result in unacceptable performance of the
improvements.
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 be designated primarily for light-duty automobile traffic use. For
design purposes, an assumed equivalent daily load axle (EDLA) rating of 7 is used in the automobile
areas.
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
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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 15.
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.
Recommendations for fly-ash stabilized subgrade pavement sections could be provided upon request.
Hot Mix Asphalt (HMA) underlain by crushed aggregate base course 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
Automobile Parking
18-kip EDLA
18-kip ESAL
Reliability
Resilient Modulus (R-value = 15)
PSI Loss
7
51,100
75%
4195
2.5
Design Structure Number 2.33
Composite Section
Hot Mix Asphalt
Aggregate Base Course
Structural Number
4"
6"
(2.42)
PCC (Non-reinforced) – placed on a stable subgrade 5-1/2"
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.
Since the cohesive intermittent clay seams on the site could have some shrink/swell potential,
pavements could crack in the future primarily because of the volume change of the soils when
subjected to an increase in moisture content to the subgrade. The cracking, while not desirable, does
not necessarily constitute structural failure of the pavement.
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.
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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.
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
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avoid features which would pond water adjacent to the foundations or stemwalls. Placement of
plants which require irrigation systems or could result in fluctuations of the moisture content of the
subgrade material should be avoided adjacent to site improvements. Irrigation systems should not be
placed within 5 feet of the perimeter of the 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 lean clay can be expected to stand on relatively steep, temporary slopes
during construction. Deeper excavations into the underlying silty sand/clayey sand subsoils 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 Reliance Construction Consulting and/or
assignees 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
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valid unless the changes are reviewed and the conclusions of this report are modified or verified in
writing by the geotechnical engineer.
Earth Engineering Consultants, LLC
DRILLING AND EXPLORATION
DRILLING & SAMPLING SYMBOLS:
SS: Split Spoon ‐ 13/8" I.D., 2" O.D., unless otherwise noted PS: Piston Sample
ST: Thin‐Walled Tube ‐ 2" O.D., unless otherwise noted WS: Wash Sample
R: Ring Barrel Sampler ‐ 2.42" I.D., 3" O.D. unless otherwise noted
PA: Power Auger FT: Fish Tail Bit
HA: Hand Auger RB: Rock Bit
DB: Diamond Bit = 4", N, B BS: Bulk Sample
AS: Auger Sample PM: Pressure Meter
HS: Hollow Stem Auger WB: Wash Bore
Standard "N" Penetration: Blows per foot of a 140 pound hammer falling 30 inches on a 2‐inch O.D. split spoon, except where noted.
WATER LEVEL MEASUREMENT SYMBOLS:
WL : Water Level WS : While Sampling
WCI: Wet Cave in WD : While Drilling
DCI: Dry Cave in BCR: Before Casing Removal
AB : After Boring ACR: After Casting Removal
Water levels indicated on the boring logs are the levels measured in the borings at the time indicated. In pervious soils, the indicated
levels may reflect the location of ground water. In low permeability soils, the accurate determination of ground water levels is not
possible with only short term observations.
DESCRIPTIVE SOIL CLASSIFICATION
Soil Classification is based on the Unified Soil Classification
system and the ASTM Designations D‐2488. Coarse Grained
Soils have move than 50% of their dry weight retained on a
#200 sieve; they are described as: boulders, cobbles, gravel or
sand. Fine Grained Soils have less than 50% of their dry weight
retained on a #200 sieve; they are described as : clays, if they
are plastic, and silts if they are slightly plastic or non‐plastic.
Major constituents may be added as modifiers and minor
constituents may be added according to the relative
proportions based on grain size. In addition to gradation,
coarse grained soils are defined on the basis of their relative in‐
place density and fine grained soils on the basis of their
consistency. Example: Lean clay with sand, trace gravel, stiff
(CL); silty sand, trace gravel, medium dense (SM).
CONSISTENCY OF FINE‐GRAINED SOILS
Unconfined Compressive
Strength, Qu, psf Consistency
< 500 Very Soft
500 ‐ 1,000 Soft
1,001 ‐ 2,000 Medium
2,001 ‐ 4,000 Stiff
4,001 ‐ 8,000 Very Stiff
8,001 ‐ 16,000 Very Hard
RELATIVE DENSITY OF COARSE‐GRAINED SOILS:
N‐Blows/ft Relative Density
0‐3 Very Loose
4‐9 Loose
10‐29 Medium Dense
30‐49 Dense
50‐80 Very Dense
80 + Extremely Dense
PHYSICAL PROPERTIES OF BEDROCK
DEGREE OF WEATHERING:
Slight Slight decomposition of parent material on
joints. May be color change.
Moderate Some decomposition and color change
throughout.
High Rock highly decomposed, may be extremely
broken.
Group
Symbol
Group Name
Cu≥4 and 1<Cc≤3
E
GW Well-graded gravel
F
Cu<4 and/or 1>Cc>3
E
GP Poorly-graded gravel
F
Fines classify as ML or MH GM Silty gravel
G,H
Fines Classify as CL or CH GC Clayey Gravel
F,G,H
Cu≥6 and 1<Cc≤3
E
SW Well-graded sand
I
Cu<6 and/or 1>Cc>3
E
SP Poorly-graded sand
I
Fines classify as ML or MH SM Silty sand
G,H,I
Fines classify as CL or CH SC Clayey sand
G,H,I
inorganic PI>7 and plots on or above "A" Line CL Lean clay
K,L,M
PI<4 or plots below "A" Line ML Silt
K,L,M
organic Liquid Limit - oven dried Organic clay
K,L,M,N
Liquid Limit - not dried Organic silt
K,L,M,O
inorganic PI plots on or above "A" Line CH Fat clay
K,L,M
PI plots below "A" Line MH Elastic Silt
K,L,M
organic Liquid Limit - oven dried Organic clay
K,L,M,P
Liquid Limit - not dried Organic silt
K,L,M,O
Highly organic soils PT Peat
(D30)2
D10 x D60
GW-GM well graded gravel with silt NPI≥4 and plots on or above "A" line.
GW-GC well-graded gravel with clay OPI≤4 or plots below "A" line.
GP-GM poorly-graded gravel with silt PPI plots on or above "A" line.
GP-GC poorly-graded gravel with clay QPI plots below "A" line.
SW-SM well-graded sand with silt
SW-SC well-graded sand with clay
SP-SM poorly graded sand with silt
SP-SC poorly graded sand with clay
Earth Engineering Consultants, LLC
IIf soil contains >15% gravel, add "with gravel" to
group name
JIf Atterberg limits plots shaded area, soil is a CL-
ML, Silty clay
Unified Soil Classification System
1
2
B-1
B-2
B-3
Boring Location Diagram
Kappa Kappa Gamma Sorority Addition - CSU - Fort Collins, Colorado
EEC Project Number: 1172062
August 2017
EARTH ENGINEERING CONSULTANTS, LLC
Approximate Boring
Locations
1
Legend
Site Photos
(Photos taken in approximate
location, in direction of arrow)
KAPPA KAPPA GAMMA SORORITY ADDITION
FORT COLLINS, COLORADO
EEC PROJECT NO. 1172062
AUGUST 2017
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 - 2-3/4 INCHES _ _
1
_ _
CLAYEY SAND (SC) 2
red / brown _ _
medium stiff to stiff 3
_ _
4
_ _
CS 5 4 2000 11.6 98.7 30 9 35.8 <500 psf none
_ _
6
_ _
7
_ _
8
_ _
9
with trace gravel _ _
SS 10 8 8000 15.5
_ _
11
_ _
12
_ _
13
_ _
14
_ _
CS 15 9 7000 15.5 115.8
_ _
16
_ _
17
_ _
18
_ _
SANDSTONE / SILTSTONE / CLAYSTONE 19
brown / olive / rust _ _
highly weathered SS 20 18 8500 22.1
moderately hard to hard with depth _ _
21
_ _
22
_ _
23
_ _
24
brown / rust / gray _ _ % @ 1000 psf
CS 25 50/6" 9000+ 9.7 125.7 32 14 55.2 2000 psf 0.4%
_ _
Earth Engineering Consultants, LLC
A-LIMITS SWELL
DATE:
RIG TYPE: CME55
FOREMAN: DG
AUGER TYPE: 4" CFA
SPT HAMMER: AUTOMATIC
SOIL DESCRIPTION D N QU MC DD -200
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
Continued from Sheet 1 of 2 26
_ _
27
SANDSTONE / SILTSTONE / CLAYSTONE _ _
brown / rust / gray 28
moderately hard to hard _ _
29
_ _
SS 30 50/7.5" 9000 12.6
_ _
31
_ _
32
_ _
33
_ _
34
_ _
CS 35 50/7.5" 8500 12.5 121.3
BOTTOM OF BORING DEPTH 35' _ _
36
_ _
37
_ _
38
_ _
39
_ _
40
_ _
41
_ _
42
_ _
43
_ _
44
_ _
45
_ _
46
_ _
47
_ _
48
_ _
49
_ _
50
_ _
Earth Engineering Consultants, LLC
A-LIMITS SWELL
N/A
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
VEGETATION & TOPSOIL _ _
1
_ _
LEAN CLAY with SAND (CL) 2
brown / red _ _
soft to stiff CS 3 5 4000 16.5 107.8 <500 psf none
_ _
4
with trace gravel _ _
SS 5 1 -- 17.7
_ _
6
_ _
7
_ _
8
_ _
9
_ _
CS 10 13 9000 16.6 113.3 36 20 83.9 <500 psf none
_ _
11
_ _
12
_ _
13
_ _
14
_ _
SS 15 4 1500 17.7
_ _
16
_ _
17
_ _
18
_ _
19
SAND / GRAVEL (SP / GP) _ _
brown / red, dense CS 20 32 -- 4.7
BOTTOM OF BORING DEPTH 20' _ _
21
_ _
22
_ _
23
_ _
24
_ _
25
_ _
Earth Engineering Consultants, LLC
A-LIMITS SWELL
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 ", AGREGGATE BASE COURSE - 6" _ _
1
SANDY LEAN CLAY (CL) _ _
2
_ _
SAND / GRAVEL (SP / GP) CS 3 26 -- 5.8 111.5 NL NP 8.5
red _ _
loose to medium dense 4
intermittent clay seams _ _
SS 5 9 7500 19.5
_ _
6
_ _
7
_ _
8
_ _
9
_ _
SS 10 17 9000+ 11.1
_ _
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
A-LIMITS SWELL
Project:
Location:
Project #:
Date:
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Red / Brown Clayey Sand (SC)
Sample Location: Boring 1, Sample 1, Depth 4'
Liquid Limit: 30 Plasticity Index: 9 % Passing #200: 35.8%
Beginning Moisture: 11.6% Dry Density: 99.9 pcf Ending Moisture: 17.5%
Swell Pressure: <500 psf % Swell @ 500: None
Kappa Kappa Gamma Sorority Addition
Fort Collins, Colorado
1172062
Aug-17
-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 / Rust / Gray Sandstone / Siltstone / Claystone - Sandy Lean Clay (CL)
Sample Location: Boring 1, Sample 5, Depth 24'
Liquid Limit: 32 Plasticity Index: 14 % Passing #200: 55.2%
Beginning Moisture: 9.7% Dry Density: 150 pcf Ending Moisture: 11.5%
Swell Pressure: 2000 psf % Swell @ 1000: 0.4%
Kappa Kappa Gamma Sorority Addition
Fort Collins, Colorado
1172062
Aug-17
-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:
Kappa Kappa Gamma Sorority Addition
Fort Collins, Colorado
1172062
Aug-17
Beginning Moisture: 16.5% Dry Density: 115.7 pcf Ending Moisture: 16.9%
Swell Pressure: <500 psf % Swell @ 500: None
Sample Location: Boring 2, Sample 1, Depth 2'
Liquid Limit: - - Plasticity Index: - - % Passing #200: - -
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown / Red 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:
Kappa Kappa Gamma Sorority Addition
Fort Collins, Colorado
1172062
Aug-17
Beginning Moisture: 16.6% Dry Density: 112 pcf Ending Moisture: 18.4%
Swell Pressure: <500 psf % Swell @ 500: None
Sample Location: Boring 2, Sample 3, Depth 9'
Liquid Limit: 36 Plasticity Index: 20 % Passing #200: 83.9%
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown / Red 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
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 8/11/2017 AFTER DRILLING N/A
SHEET 1 OF 1 WATER DEPTH
START DATE 8/11/2017 WHILE DRILLING None
KAPPA KAPPA GAMMA SORORITY EXPANSION
FORT COLLINS, COLORADO
PROJECT NO: 1172062 LOG OF BORING B-3 AUGUST 2017
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 8/11/2017 AFTER DRILLING N/A
SHEET 1 OF 1 WATER DEPTH
START DATE 8/11/2017 WHILE DRILLING None
KAPPA KAPPA GAMMA SORORITY EXPANSION
FORT COLLINS, COLORADO
PROJECT NO: 1172062 LOG OF BORING B-2 AUGUST 2017
8/11/2017 AFTER DRILLING N/A
SURFACE ELEV 24 HOUR N/A
FINISH DATE
SHEET 2 OF 2 WATER DEPTH
START DATE 8/11/2017 WHILE DRILLING 20.0'
KAPPA KAPPA GAMMA SORORITY EXPANSION
FORT COLLINS, COLORADO
PROJECT NO: 1172062 LOG OF BORING B-1 AUGUST 2017
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 8/11/2017 AFTER DRILLING N/A
SHEET 1 OF 1 WATER DEPTH
START DATE 8/11/2017 WHILE DRILLING 20.0'
KAPPA KAPPA GAMMA SORORITY EXPANSION
FORT COLLINS, COLORADO
PROJECT NO: 1172062 LOG OF BORING B-1 AUGUST 2017
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