HomeMy WebLinkAboutBROOKVIEW APARTMENTS - PDP - PDP160003 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTGEOTECHNICAL EXPLORATION REPORT
BROOKVIEW APARTMENTS – NEW BUILDING DEVELOPMENT
NORTH OF EAST STUART STREET AND WEST OF WELCH STREET
FORT COLLINS, COLORADO
EEC PROJECT NO. 1152090
Prepared for:
Progressive Brookview, LLC
c/o Old Town Square Properties
5 Old Time Square #216
Fort Collins, Colorado 80524
Attn: Mr. Ed Stoner (estoner@oldtownsq.com)
Prepared by:
Earth Engineering Consultants, LLC
4396 Greenfield Drive
Windsor, Colorado 80550
4396 GREENFIELD DRIVE
WINDSOR, COLORADO 80550
(970) 224-1522 FAX (970) 663-0282
September 22, 2015
Progressive Brookview, LLC
c/o Old Town Square Properties
5 Old Time Square #216
Fort Collins, Colorado 80524
Attn: Mr. Ed Stoner (estoner@oldtownsq.com)
Re: Geotechnical Exploration Report
Brookview Apartments – New Building Development
North of East Stuart Street and West of Welch Street
Fort Collins, Colorado
EEC Project No. 1152090
Mr. Stoner:
Enclosed, herewith, are the results of the geotechnical subsurface exploration completed by Earth
Engineering Consultants, LLC (EEC) personnel for the referenced project. For this exploration,
two (2) soil borings were drilled to depths of approximately 15 to 25 feet at the approximate
locations as indicated on the enclosed Test Boring Location Diagram. Individual boring logs,
including results of laboratory testing, are included as a part of the attached report. This
exploration was completed in general accordance with our proposal dated August 25, 2015.
We understand this project involves the development of two (2) new buildings at the existing
Brookview Apartments north of Stuart Street and west of Welch Street in Fort Collins. We
understand this project involves the construction of multi-unit two or three-story, wood frame
residential apartments. Foundation loads for the structures are expected to be light; floor loads
are expected to be light. The development area is currently landscaping with grade change of 5
to 10 feet.
Based on the materials observed within the test borings and the proposed building construction,
we believe the proposed apartment buildings could be supported on a post-tensioned slab-on-
grade foundation/floor system or conventional type spread footings bearing on suitable native
materials or a zone of engineered fill material placed and compacted as described within this
report.
In general, it appears the in-situ site materials or similar import materials could be used for
support of interior slab-on-grades and exterior flatwork. Post-construction movement cannot be
GEOTECHNICAL EXPLORATION REPORT
BROOKVIEW APARTMENTS – NEW BUILDING DEVELOPMENT
NORTH OF EAST STUART STREET AND WEST OF WELCH STREET
FORT COLLINS, COLORADO
EEC PROJECT NO. 1152090
September 22, 2015
INTRODUCTION
The geotechnical subsurface exploration for the proposed development of two (2) new buildings for
the existing Brookview Apartments located north of East Stuart Street and west of Welch Street in
Fort Collins, Colorado, has been completed. For this exploration, (2) soil borings were drilled
within the proposed building areas at the site extending to approximate depths of 15 to 25 feet below
existing site grades. This exploration was completed in general accordance with our proposal dated
August 25, 2015.
We understand the proposed development will generally include the construction of two (2) new
multi-unit residential apartments at the existing Brookview Apartments complex. The apartment
buildings are anticipated to be two or three-story, wood-frame, slab-on-grade (non-basement)
structures. Foundation loads for the structures are expected to be light with continuous wall loads
less than 3 kips per lineal foot and individual column loads less than 100 kips. Floor loads are
expected to be light. Cuts/fills less than 5 feet are expected to develop the new site grades in the
area of the new buildings.
The purpose of this report is to describe the subsurface conditions encountered in the test borings,
analyze and evaluate the test data and provide geotechnical recommendations concerning design and
construction of foundations and support of floor slabs for the new buildings.
EXPLORATION AND TESTING PROCEDURES
The test borings were completed using a track mounted, CME-55 drill rig equipped with a hydraulic
head employed in drilling and sampling operations. The track rig was needed to access the site. 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.
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EEC Project No. 1152090
September 22, 2015
Page 2
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.
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 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 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
is indicated on the boring logs and a brief description of that classification system is included with
this report.
SITE AND SUBSURFACE CONDITIONS
The existing Brookview Apartment development is located north of East Stuart Street between South
Lemay Avenue and Welch Street in Fort Collins. The new buildings will be constructed
immediately north of East Stuart Street about halfway between South Lemay Avenue and Welch
Street. The building area is currently a landscape area with grass surface and several large trees.
Berming and an apparent detention area are located in the general area of the new buildings with
current surface elevation difference in the range of 5 to 10 feet.
Based on results of the field borings and laboratory testing, subsurface conditions can be generalized
as follows. A surficial layer of vegetation and topsoil was encountered at the boring locations.
Cohesive lean clay subsoils were encountered beneath the topsoil/vegetation and extended to the
bottom of the borings at depths of approximately 15 to 25 feet below existing site grades. The
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EEC Project No. 1152090
September 22, 2015
Page 3
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.
The essentially cohesive soils encountered beneath the surface topsoil/vegetation layer varied from
medium stiff to soft in consistency and exhibited low swell potential and typically low bearing
capacity characteristics. A portion of the near surface soils may be fill soils from prior site grading.
Portions of the essentially cohesive soils exhibited soft/compressible conditions.
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, no free water was observed in the borings
to the depths of exploration.
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
Swell/consolidation testing is performed to evaluate the swell or collapse potential of soil or bedrock to
assist in determining/evaluating foundation, floor slab and/or pavement design criteria. In the
swell/consolidation test, samples obtained directly from the California barrel sampler are placed in a
laboratory apparatus and inundated with water under a pre-established load. The swell-index is the
resulting amount of swell or collapse under the initial loading condition expressed as a percent of the
sample’s initial thickness. After the initial monitoring period, additional incremental loads are applied
to evaluate swell pressure and/or consolidation response.
For this assessment, we conducted three (3) swell-consolidation tests at various depths. The swell
index values for the samples analyzed revealed low swell characteristics with a tendency to consolidate
for the softer sample.
Earth Engineering Consultants, LLC
EEC Project No. 1152090
September 22, 2015
Page 4
Colorado Association of Geotechnical Engineers (CAGE) uses the following information 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 I: 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
Site Preparation
Based on our understanding of the proposed development, cuts and fills on the order of 3 to 5 feet
may be completed to achieve design grades. Existing fill materials were not identified during our
field borings, however, based on the site grades, we expect that fill materials may exist on the site
particularly in the berm area and close observation during construction is advised. After stripping
the topsoil/vegetation, cutting any undocumented fill materials, and prior to placement of any fill
and/or site improvements, we recommend the exposed soils be scarified to a depth of at least 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 soils to develop the building flatwork 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 cohesive soils or similar import soils could be used as fill in these areas, provided adequate
moisture treatment and compaction procedures are followed. We recommend the 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 soils or similar import materials are used as
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EEC Project No. 1152090
September 22, 2015
Page 5
fill material, care will be needed to maintain the recommended moisture content prior to and during
construction of overlying improvements.
Care should be exercised after preparation of the subgrades to avoid disturbing the subgrade
materials. Positive drainage should be developed away from the structures to avoid wetting of
subgrade materials. Subgrade materials becoming wet subsequent to construction of the site
improvements can result in unacceptable performance.
As shown on the attached boring logs and summary sheets, low swelling soils are present on this
site; however, zones of relatively loose soils were observed as indicated by the blow count of boring
B-1, Sample 2 (N=2). This report provides recommendations to help mitigate the effects of soil
volume changes. Even if these procedures are followed, some movement and at least minor cracking
in the structures should be anticipated. The severity of cracking and other cosmetic damage such as
uneven floor slabs/exterior flatwork will probably increase if any modification of the site results in
excessive wetting or drying of the site soils. Eliminating the risk of movement and cosmetic distress
may not be feasible, but it may be possible to further reduce the risk of movement if significantly
more expensive measures are used during construction. We would be pleased to discuss other
construction alternatives with you upon request.
Areas of deeper fills may experience settlement from within the placed fill materials. Settlement on
the order of 1 to 1.5% of the fill depth would be estimated. The rate of settlement will be dependent
on the type of fill material placed and construction methods. Granular soils will consolidate
essentially immediately upon placement of overlying loads. Cohesive soils will consolidate at a
much slower rate.
Foundation Systems – General Considerations
The site appears suitable for the proposed construction based on the results of our field exploration and
review of the proposed development plans. The following foundation systems were evaluated for use
on the site:
Conventional Spread Footings
Post-Tensioned Slab Foundation System
Earth Engineering Consultants, LLC
EEC Project No. 1152090
September 22, 2015
Page 6
Conventional Spread Footing Foundations
The native undisturbed lean clay generally exhibited low swell potential and low bearing
characteristics. The laboratory and field testing suggested a tendency to consolidate under load. To
reduce the potential for post-construction settlement of the footings subsequent to construction, we
recommend the existing site subgrades and proposed fill materials be reworked and placed as
recommended in the Site Preparation section of this report. Some removal and replacement of in-
place soft subgrade soils should be expected to establish foundation bearing.
Conventional type spread footings could be used to support proposed slab on grade buildings
provided the footings are placed on approved native subgrade material or moisture/density
controlled fill material and the maximum anticipated wall and column loads do not exceed those
presented herein. If actual design loads exceed the assumed values as previously presented, we
should be consulted to provide supplemental design criteria, possibly including alternative
foundations.
Footings bearing on approved native subsoils or moisture/density conditioned soils could be
designed for a maximum net allowable total load bearing pressure of 1,500 psf. The net bearing
pressure refers to the pressure at foundation bearing level in excess of the minimum surrounding
overburden pressure. Total load should include full dead and live loads.
Footings should be proportioned to reduce differential foundation movement. We estimate the total
long term settlement of footings designed as outlined above would be less than 1-inch.
The backfill soils adjacent to the foundations should be placed in loose lifts not to exceed 9 inches
thick, moisture conditioned to ±2% of the material’s standard Proctor optimum moisture content,
and compacted to at least 95% of standard Proctor maximum dry density (ASTM D698).
After placement of the fill materials, care should be taken to avoid wetting or drying of those
materials. Bearing 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 or
reworked in place prior to construction of the overlying improvements.
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EEC Project No. 1152090
September 22, 2015
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Exterior foundations and foundations in unheated areas should be located at least 30 inches below
adjacent exterior grade to provide frost protection. We recommend formed continuous footings have
a minimum width of 12 inches and isolated column foundations have a minimum width of 24 inches.
Post-Tensioned Slab Foundation Systems
The results of our field exploration and laboratory testing completed for this study indicate the upper
cohesive clay subsoils exhibited low swell potential and low bearing capabilities. Based on the
subsurface conditions encountered and the expected fill materials across the site, we expect the
proposed apartment buildings could be supported by post-tensioned slab-on-grade foundations that are
supported/bear on a zone of engineered/controlled fill materials placed and compacted as outlined in
the Site Preparation section of this report or on acceptable underlying native soils. The design
parameters provided below assume subgrade materials outlined under Site Preparation.
Outlined below are the post-tensioned slab-on-grade design criteria based on the subsurface
conditions observed and information provided in the 3rd Edition of the Post-Tensioning Institutes
design manual. Post-tensioned slabs, thickened or turn-down edges, and/or interior beams should be
designed and constructed in accordance with the appropriate design criteria.
Table II – Post-Tension Slab (PTS) Design Criteria
Post-Tensioned Slab (PTS) – 3rd Edition Design Parameters
Maximum Allowable Bearing Pressure, psf 1500
Edge Moisture Variation Distance, em Center Lift Condition, ft 8.6
Edge Lift Condition, ft 4.3
Differential Soil Movement, ym Center Lift Condition, in 0.4
Edge Lift Condition, in 0.8
Slab-Subgrade friction coefficient,
on polyethylene sheeting 0.75
on cohesionless soils (sands) 1.0
on cohesive soils (clays) 2.0
Earth Engineering Consultants, LLC
EEC Project No. 1152090
September 22, 2015
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Seismic
The site soil conditions consist of greater than 25 feet of overburden soils. For those site conditions,
the 2012 International Building Code indicates a Seismic Site Classification of D.
Lateral Earth Pressures
For any area of the proposed development having below grade construction, such as retaining walls,
or crawl spaces, those portions will be subject to lateral earth pressures. Passive lateral earth
pressures may help resist the driving forces for retaining wall or other similar site structures. Active
lateral earth pressures could be used for design of structures where some movement of the structure
is anticipated, such as retaining walls. The total deflection of structures for design with active earth
pressure is estimated to be on the order of one half of one percent of the height of the down slope
side of the structure. We recommend at-rest pressures be used for design of structures where
rotation of the walls is restrained. Passive pressures and friction between the footing and bearing
soils could be used for design of resistance to movement of retaining walls.
Coefficient values for backfill with anticipated types of soils for calculation of active, at rest and
passive earth pressures are provided in the table below. Equivalent fluid pressure is equal to the
coefficient times the appropriate soil unit weight. Those coefficient values are based on horizontal
backfill with backfill soils consisting of essentially on-site cohesive subsoils, or approved imported
granular materials with friction angles of 25 and 35 degrees, respectively. For the at-rest and active
earth pressures, slopes down and away from the structure would result in reduced driving forces with
slopes up and away from the structures resulting in greater forces on the walls. The passive
resistance would be reduced with slopes away from the wall. The top 30 inches of soil on the
passive resistance side of walls could be used as a surcharge load; however, should not be used as a
part of the passive resistance value. Frictional resistance is equal to the tangent of the friction angle
times the normal force. Surcharge loads or point loads placed in the backfill can also create
additional loads on below grade walls. Those situations should be designed on an individual basis.
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EEC Project No. 1152090
September 22, 2015
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Table III – Lateral Earth Pressure Design Values
Soil Type On-Site Low Plasticity Cohesive Imported Medium Dense
Granular
Wet Unit Weight 120 135
Saturated Unit Weight 135 140
Friction Angle () – (assumed) 25° 35°
Active Pressure Coefficient 0.40 0.27
At-rest Pressure Coefficient 0.58 0.43
Passive Pressure Coefficient 2.46 3.70
The outlined values do not include factors of safety nor allowances for hydrostatic loads and are
based on assumed friction angles, which should be verified before construction and once potential
material sources have been identified. Care should be taken to develop appropriate drainage systems
behind below grade walls to eliminate potential for hydrostatic loads developing on the walls. Those
systems would likely include perimeter drain systems extending to sump areas or free outfall where
reverse flow cannot occur into the system. Where necessary, appropriate hydrostatic load values
should be used for design.
Floor Slabs
To reduce floor slab movement, we recommend the proposed floor slab bear upon a properly placed
and compacted engineered fill material and/or reworked subgrade soils as outlined under Site
Preparation. It is our opinion the on-site essentially cohesive soils could be used as fill in these
areas, provided adequate moisture treatment and compaction procedures are followed. If the site
lean clay soils or similar import materials are used as fill material, care will be needed to maintain
the recommended moisture content prior to and during construction of overlying improvements.
This procedure will not fully eliminate the possibilities of slab movement; but movements should be
reduced and tend to be more uniform. We estimate the long-term movement of floor slabs with
properly prepared subgrade subsoils as outlined above would be about 1-inch or less.
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 compacted on-site or similar import soils. A
modulus of 200 pci could be used for floors supported on at least 18 inches of imported granular
structural fill material.
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EEC Project No. 1152090
September 22, 2015
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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,
are recommended.
Other Considerations
Positive drainage should be developed away from structures with a minimum slope of 1 inch per foot
for the first 10 feet away from the improvements in landscape areas. Care should be taken in
planning of landscaping adjacent to the buildings to avoid features 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 clays’ can be expected to stand on relatively steep temporary slopes
during construction. 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.
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EEC Project No. 1152090
September 22, 2015
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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 Progressive Brookview, LLL for specific
application to the project discussed and has been prepared in accordance with generally accepted
geotechnical engineering practices. No warranty, expressed or implied, is made. In the event that
any changes in the nature, design, or location of the project as outlined in this report are planned, the
conclusions and recommendations contained in this report shall not be considered valid unless the
changes are reviewed and the conclusions of this report are modified or verified in writing by the
geotechnical engineer.
Earth Engineering Consultants, LLC
DRILLING AND EXPLORATION
DRILLING & SAMPLING SYMBOLS:
SS: Split Spoon ‐ 13/8" I.D., 2" O.D., unless otherwise noted PS: Piston Sample
ST: Thin‐Walled Tube ‐ 2" O.D., unless otherwise noted WS: Wash Sample
R: Ring Barrel Sampler ‐ 2.42" I.D., 3" O.D. unless otherwise noted
PA: Power Auger FT: Fish Tail Bit
HA: Hand Auger RB: Rock Bit
DB: Diamond Bit = 4", N, B BS: Bulk Sample
AS: Auger Sample PM: Pressure Meter
HS: Hollow Stem Auger WB: Wash Bore
Standard "N" Penetration: Blows per foot of a 140 pound hammer falling 30 inches on a 2‐inch O.D. split spoon, except where noted.
WATER LEVEL MEASUREMENT SYMBOLS:
WL : Water Level WS : While Sampling
WCI: Wet Cave in WD : While Drilling
DCI: Dry Cave in BCR: Before Casing Removal
AB : After Boring ACR: After Casting Removal
Water levels indicated on the boring logs are the levels measured in the borings at the time indicated. In pervious soils, the indicated
levels may reflect the location of ground water. In low permeability soils, the accurate determination of ground water levels is not
possible with only short term observations.
DESCRIPTIVE SOIL CLASSIFICATION
Soil Classification is based on the Unified Soil Classification
system and the ASTM Designations D‐2488. Coarse Grained
Soils have move than 50% of their dry weight retained on a
#200 sieve; they are described as: boulders, cobbles, gravel or
sand. Fine Grained Soils have less than 50% of their dry weight
retained on a #200 sieve; they are described as : clays, if they
are plastic, and silts if they are slightly plastic or non‐plastic.
Major constituents may be added as modifiers and minor
constituents may be added according to the relative
proportions based on grain size. In addition to gradation,
coarse grained soils are defined on the basis of their relative in‐
place density and fine grained soils on the basis of their
consistency. Example: Lean clay with sand, trace gravel, stiff
(CL); silty sand, trace gravel, medium dense (SM).
CONSISTENCY OF FINE‐GRAINED SOILS
Unconfined Compressive
Strength, Qu, psf Consistency
< 500 Very Soft
500 ‐ 1,000 Soft
1,001 ‐ 2,000 Medium
2,001 ‐ 4,000 Stiff
4,001 ‐ 8,000 Very Stiff
8,001 ‐ 16,000 Very Hard
RELATIVE DENSITY OF COARSE‐GRAINED SOILS:
N‐Blows/ft Relative Density
0‐3 Very Loose
4‐9 Loose
10‐29 Medium Dense
30‐49 Dense
50‐80 Very Dense
80 + Extremely Dense
PHYSICAL PROPERTIES OF BEDROCK
DEGREE OF WEATHERING:
Slight Slight decomposition of parent material on
joints. May be color change.
Moderate Some decomposition and color change
throughout.
High Rock highly decomposed, may be extremely
broken.
Group
Symbol
Group Name
Cu≥4 and 1<Cc≤3
E
GW Well-graded gravel
F
Cu<4 and/or 1>Cc>3
E
GP Poorly-graded gravel
F
Fines classify as ML or MH GM Silty gravel
G,H
Fines Classify as CL or CH GC Clayey Gravel
F,G,H
Cu≥6 and 1<Cc≤3
E
SW Well-graded sand
I
Cu<6 and/or 1>Cc>3
E
SP Poorly-graded sand
I
Fines classify as ML or MH SM Silty sand
G,H,I
Fines classify as CL or CH SC Clayey sand
G,H,I
inorganic PI>7 and plots on or above "A" Line CL Lean clay
K,L,M
PI<4 or plots below "A" Line ML Silt
K,L,M
organic Liquid Limit - oven dried Organic clay
K,L,M,N
Liquid Limit - not dried Organic silt
K,L,M,O
inorganic PI plots on or above "A" Line CH Fat clay
K,L,M
PI plots below "A" Line MH Elastic Silt
K,L,M
organic Liquid Limit - oven dried Organic clay
K,L,M,P
Liquid Limit - not dried Organic silt
K,L,M,O
Highly organic soils PT Peat
(D30)2
D10 x D60
GW-GM well graded gravel with silt NPI≥4 and plots on or above "A" line.
GW-GC well-graded gravel with clay OPI≤4 or plots below "A" line.
GP-GM poorly-graded gravel with silt PPI plots on or above "A" line.
GP-GC poorly-graded gravel with clay QPI plots below "A" line.
SW-SM well-graded sand with silt
SW-SC well-graded sand with clay
SP-SM poorly graded sand with silt
SP-SC poorly graded sand with clay
Earth Engineering Consultants, LLC
IIf soil contains >15% gravel, add "with gravel" to
group name
JIf Atterberg limits plots shaded area, soil is a CL-
ML, Silty clay
Unified Soil Classification System
BROOKSIDE PROPERTIES
FORT COLLINS, COLORADO
EEC PROJECT NO. 1152090
SEPTEMBER 2015
2 STORY FRAME
APARTMENT BUILDING
FFE = 4968.04
2 STORY FRAME
APARTMENT BUILDING
FFE = 4969.86
2 STORY FRAME
APARTMENT BUILDING
FFE = 4966.12
TRASH
CAN
BARBECUE
G
BANK OF 21
GAS METERS
G
G
BANK OF 13
GAS METERS
FESSIONAL PARK
CONDOS 3RD
B-1
B-2
1
2
Boring Location Diagram
Brookview Apartments - New Building Development
Fort Collins, Colorado
EEC Project #: 1152090 Date: September 2015
Approximate Boring
Locations
1
EARTH ENGINEERING CONSULTANTS, LLC
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
TOPSOIL & VEGETATION _ _
1
SANDY LEAN CLAY (CL) _ _
brown 2
very stiff to stiff _ _ % @ 150 psf
with calcareous deposits CS 3 5 9000+ 9.9 92.7 30 12 85.3 700 psf 2.4%
_ _
4
_ _
with traces of gravel SS 5 2 4000 12.4
_ _
6
_ _
7
_ _
8
SANDY LEAN CLAY (CL) _ _
brown / red 9
very stiff to stiff _ _
CS 10 8 9000+ 11.7 114.3 30 17 73.9 600 psf 0.1%
_ _
11
_ _
12
_ _
13
_ _
14
_ _
SS 15 5 2000 10.2
_ _
16
_ _
17
_ _
18
_ _
19
with traces of gravel _ _
CS 20 13 5500 15.5 114.2
_ _
21
_ _
22
_ _
23
_ _
24
_ _
SS 25 12 2500 21.0
BOTTOM OF BORING DEPTH 25.5' _ _
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
TOPSOIL & VEGETATION _ _
1
SANDY LEAN CLAY (CL) _ _
brown 2
very stiff _ _
with traces of gravel 3
_ _
4
_ _
CS 5 6 7000 12.1 114.7 33 17 51.3 <500 psf None
_ _
6
_ _
7
_ _
8
_ _
9
_ _
LEAN CLAY (CL) SS 10 10 9000+ 12.5
brown / red _ _
very stiff 11
mottled _ _
12
_ _
13
_ _
14
SANDY LEAN CLAY (CL) _ _
very stiff, brown / red CS 15 6 9000 11.5 118.9
BOTTOM OF BORING DEPTH 15.0' _ _
16
_ _
17
_ _
18
_ _
19
_ _
20
_ _
21
_ _
22
_ _
23
_ _
24
_ _
25
_ _
Earth Engineering Consultants, LLC
A-LIMITS SWELL
Project:
Location:
Project #:
Date:
Brookview Apartments - New Building Development
Fort Collins, Colorado
1152090
September 2015
Beginning Moisture: 9.9% Dry Density: 98.1 pcf Ending Moisture: 27.9%
Swell Pressure: 700 psf % Swell @ 150: 2.4%
Sample Location: Boring 1, Sample 1, Depth 2'
Liquid Limit: 30 Plasticity Index: 12 % Passing #200: 85.3%
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:
Brookview Apartments - New Building Development
Fort Collins, Colorado
1152090
September 2015
Beginning Moisture: 11.7% Dry Density: 117 pcf Ending Moisture: 17.0%
Swell Pressure: 600 psf % Swell @ 500: 0.1%
Sample Location: Boring 1, Sample 3, Depth 9'
Liquid Limit: 30 Plasticity Index: 17 % Passing #200: 73.9%
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown / Red 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:
Brookview Apartments - New Building Development
Fort Collins, Colorado
1152090
September 2015
Beginning Moisture: 12.1% Dry Density: 123.3 pcf Ending Moisture: 12.7%
Swell Pressure: <500 psf % Swell @ 500: None
Sample Location: Boring 2, Sample 1, Depth 4'
Liquid Limit: 33 Plasticity Index: 17 % Passing #200: 51.3%
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
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 9/16/2015 AFTER DRILLING N/A
SHEET 1 OF 1 WATER DEPTH
START DATE 9/16/2015 WHILE DRILLING None
BROOKVIEW APARTMENTS - NEW BUILDING DEVELOPMENT
FORT COLLINS, COLORADO
PROJECT NO: 1152090 LOG OF BORING B-2 SEPTEMBER 2015
SURFACE ELEV N/A 24 HOUR N/A
FINISH DATE 9/16/2015 AFTER DRILLING N/A
SHEET 1 OF 1 WATER DEPTH
START DATE 9/16/2015 WHILE DRILLING None
BROOKVIEW APARTMENTS - NEW BUILDING DEVELOPMENT
FORT COLLINS, COLORADO
PROJECT NO: 1152090 LOG OF BORING B-1 SEPTEMBER 2015
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