HomeMy WebLinkAboutHOMESTEAD AT CLARENDON HILLS - PDP190007 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORT (3)November 6, 2018
Kenneth R. Mitchell (kmitch2000@gmail.com)
1021 Nightingale Drive
Fort Collins, Colorado 80525
Re: Preliminary Subsurface Exploration
Proposed Single-Family Development
Clarendon Village Preliminary
Fort Collins, Colorado
EEC Project No. 18-01-197
Mr. Mitchell:
Enclosed herewith, are the results of the preliminary subsurface exploration completed by
Earth Engineering Company, Inc. personnel for the referenced project. For this study, five
(5) soil borings were drilled on October 23rd
, 2018 at various locations in the proposed
development. Those borings were extended to depths of approximately 14½ to 24½ feet
below present site grades.
In summary, the near surface subsurface conditions encountered in the borings consisted of
clayey sand and gravel materials underlain by clayey sandstone bedrock at a depth of
approximately 2 to 7 feet below present site grades which extended to the depths explored,
approximately 14½ to 24½ feet below present site grades. During the initial field
exploration, groundwater was not observed at borings B-1, B-2, B-3 and B-5 and
groundwater was observed at a depth of approximately 24 feet below present site grades at
boring B-4. Approximately 24 hours after drilling, groundwater was observed at depths of
approximately 19½, 15½ and 14½ feet below site grades at borings B-1, B-3 and B-4
respectively. Approximately 24 hours after drilling, free water was not observed at borings
B-2 and B-5. Seven days after drilling of the borings, free water was observed at a depth of
approximately 17, 15½, 14½ and 17 feet below present site grades at borings B-1, B-3, B-4
and B-5, respectively. Groundwater was not observed at boring B-2 seven days after drilling.
The near surface site soils observed are comprised of essentially granular materials underlain
by clayey sandstone bedrock at a depth of approximately 2 to 7 feet below present site
grades. To reduce the potential for differential movement in the foundation and floor slabs
subsequent to construction, we recommend all foundation footings extend through the
essentially granular materials and be constructed to bear directly on the low swell potential
clayey sandstone bedrock. Based on the observed depth to bedrock at the borings, we
estimate the depth of the at-grade (i.e. garage) and basement footing foundation bearing
levels would be approximately 2 to 7 feet below present site grades resulting in ‘tall’ at-
grade (i.e. garage) and walk-out basement foundation walls. However, the near surface
clayey sandstone bedrock encountered at boring B-1 showed moderate potential for swelling
PRELIMINARY SUBSURFACE EXPLORATION REPORT
CLARENDON VILLAGE PRELIMINARY
FORT COLLINS, COLORADO
EEC PROJECT NO. 18-01-197
November 6, 2018
INTRODUCTION
The preliminary geotechnical subsurface exploration for the proposed development at the
proposed Clarendon Village development in Fort Collins, Colorado, has been completed.
For this assessment, five (5) soil borings were drilled on October 23, 2018 to depths of
approximately 14½ to 24½ feet below present site grades at the proposed development
parcel. The approximate boring locations are shown on the enclosed site diagram included
with this report.
We understand this project involves the preliminary evaluation of the soils and groundwater
conditions at the proposed development area. Site structures are expected to be lightly
loaded, constructed with either basement and/or non-basement foundations. Infrastructure
improvements would likely include utility installation and construction of local streets and
on-site parking areas. We expect grade changes will be required to develop final site grades.
The purpose of this report is to describe the subsurface conditions encountered in the test
borings, analyze and evaluate the test data and provide preliminary geotechnical
recommendations concerning design and construction of foundations and support of floor
slabs for site structures and development of site infrastructure.
EXPLORATION AND TESTING PROCEDURES
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 were obtained using split barrel and California barrel sampling
Earth Engineering Company, Inc.
EEC Project No. 18-01-197
November 6, 2018
Page 2
procedures. 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.
Moisture content tests were completed on each of the recovered samples. Atterberg Limits
and washed sieve analysis tests were completed on select samples to evaluate the quantity
and plasticity of fines in the subgrade samples. 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 by an engineer
and classified in 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 Clarendon Village development parcel is located in Fort Collins, Colorado in
an area east of the intersection of South Shields Street and Clarendon Hills Drive. The
building site is relatively flat and was vegetated at the time of our observations.
Based on results of the field borings and laboratory testing, subsurface conditions can be
generalized as follows. In summary, the subsurface conditions encountered beneath the
development parcel consisted of medium dense to dense brown and brown/light brown
clayey sand and gravel materials underlain by clayey sandstone bedrock at a depth of
approximately 2 to 7 feet below present site grades. The near surface low plasticity clayey
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EEC Project No. 18-01-197
November 6, 2018
Page 3
sand and gravel materials exhibited a low potential for swelling with variation in moisture
content at current moisture/density conditions. The clayey sandstone bedrock was poorly
cemented in consistency and exhibited a low to moderate potential for swelling with
variation in moisture content at current moisture/density conditions. The clayey sandstone
bedrock extended to the depths explored, approximately 14½ to 24½ feet below present site
grades. The stratification boundaries indicated on the boring logs represent the approximate
locations of changes in soil and rock types. In-situ, the transition of materials may be gradual
and indistinct.
GROUNDWATER CONDITIONS
Observations were made while drilling, 24 hours and 7 days after completion of the borings
to detect the presence and depth to hydrostatic groundwater. During the initial field
exploration, groundwater was not observed at borings B-1, B-2, B-3 and B-5 and
groundwater was observed at a depth of approximately 24 feet below present site grades at
boring B-4. Approximately 24 hours after drilling, groundwater was observed at depths of
approximately 19½, 15½ and 14½ feet below site grades at borings B-1, B-3 and B-4
respectively. Approximately 24 hours after drilling, free water was not observed at borings
B-2 and B-5. Seven days after drilling of the borings, free water was observed at a depth of
approximately 17, 15½, 14½ and 17 feet below present site grades at borings B-1, B-3, B-4
and B-5, respectively. Groundwater was not observed at boring B-2 seven days after drilling.
We recommend maintaining a minimum 3-feet separation between the foundation bearing
elevation and peak seasonal groundwater levels. Close observation would be needed to
evaluate the groundwater depths during the spring and summer months to determine the peak
groundwater levels at the site.
Zones of perched and/or trapped groundwater may occur at times in the subsurface soils
overlying bedrock, on top of the bedrock surface or within permeable fractures in the
bedrock materials. The location and amount of perched water is dependent upon several
factors, including hydrologic conditions, type of site development, irrigation demands on or
adjacent to the site and seasonal and weather conditions. These observations represent
groundwater conditions at the time of the field exploration, and may not be indicative of
other times, or at other locations.
Earth Engineering Company, Inc.
EEC Project No. 18-01-197
November 6, 2018
Page 4
ANALYSIS AND RECOMMENDATIONS
Preliminary Foundation Systems – General Considerations
The near surface site soils observed are comprised of essentially granular materials underlain
by clayey sandstone bedrock at a depth of approximately 2 to 7 feet below present site
grades. To reduce the potential for differential movement in the foundation and floor slabs
subsequent to construction, we recommend all foundation footings extend through the
essentially granular materials and be constructed to bear directly on the low swell potential
clayey sandstone bedrock. Based on the observed depth to bedrock at the borings, we
estimate the depth of the at-grade (i.e. garage) and basement footing foundation bearing
levels would be approximately 2 to 7 feet below present site grades resulting in ‘tall’ at-
grade (i.e. garage) foundation walls. However, the near surface clayey sandstone bedrock
encountered at boring B-1 showed moderate potential for swelling when inundated with an
increase in moisture content. A deep foundation system such as drilled pier foundations for
heavily loaded structures may be appropriate for the site in the area of boring B-1. Footings,
where utilized, should be placed on similar like material to minimize or reduce the potential
for differential movement.
Footing Foundations
Based on the materials observed in the preliminary test borings B-2 through B-5, it is our
opinion the proposed lightly loaded single-family residential structures could be supported
on conventional footing foundations bearing in the poorly cemented low swell potential
clayey sandstone bedrock. For design of footing foundations supported on the poorly
cemented clayey sandstone bedrock, we anticipate net allowable total load soil bearing
pressures in the range of 2,000 to 3,000 psf with a minimum dead load pressure of 500 to
1000 psf appear usable for design of footing foundations at this site. 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 and live loads.
Exterior foundations and foundations in unheated areas should be located at least 30 inches
below final adjacent exterior grades 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. Trenched foundations or grade beam foundations could
be used in the site cohesive soils.
Earth Engineering Company, Inc.
EEC Project No. 18-01-197
November 6, 2018
Page 5
We recommend the foundation footing design loads be balanced to promote relatively
uniform settlement, thereby reducing the potential for differential settlement. As an
alternative to balancing the design loads solely on settlement, designing the foundation such
that the dead-load pressure is balanced throughout the foundations could be considered.
Balancing the dead-load pressure would also reduce the potential for differential settlement
between adjacent footings. We estimate the long-term settlement of footing foundations
designed and constructed as recommended above would be less than 1 inch.
Groundwater was observed at a depth of approximately 14½ to 17 feet below present site
grades at the completed site borings. We recommend maintaining a minimum vertical
separation of at least three feet between foundation bearing elevation and the peak seasonal
groundwater levels. Close observation would be needed to evaluate the groundwater depths
during the spring and summer months to determine the peak groundwater levels at the site.
Care will be needed to avoid placing structural elements directly on any areas of expansive
or soft materials. Careful observation should be completed prior to placement of foundation
concrete to evaluate the bearing materials. If expansive or soft materials are observed at that
time, overexcavation and replacement may be required to provide a zone of material
immediately beneath the foundations and floor slabs which would have low potential for
swelling and/or consolidation subsequent to construction and, therefore, would reduce the
potential for total and differential movement subsequent to construction.
We estimate the long-term settlement of footing foundations designed and constructed as
outlined above would be less than 1 inch.
Drilled Pier Foundations
Based on the materials observed in the area of test boring B-1, it is our opinion the proposed
lightly loaded single-family residential structures may be recommended to be supported on
drilled pier foundations. It should be noted that after the site has been developed and final
site grades achieved, site-specific soils test for the lots in this area may conclude that
conventional footings are feasible in those areas. Should drilled piers be appropriate, we
typically recommend those drilled pier foundations extend to bear at least 25 to 35 feet below
finished top-of-pier elevation or extend into the underlying clayey sandstone bedrock
stratum at least 15 to 25 feet, whichever results in the longer drilled pier. For design of
Earth Engineering Company, Inc.
EEC Project No. 18-01-197
November 6, 2018
Page 6
drilled pier foundations bearing in the moderately hard claystone bedrock, we typically
recommend using a total load end bearing pressure not to exceed 25 kips per square foot.
Additional pier capacity can be developed by extending the drilled piers beyond the
recommended minimum bedrock penetration and taking advantage of additional friction
capacity between the drilled pier and surrounding bedrock. We recommend an allowable
friction value of 2.5 kips per square foot be used for that portion of the drilled pier shaft
extending below the upper 15 feet of the pier. The skin friction on the drilled piers can also
be used to offset an inability to develop the recommended dead load on the piers. We
recommend an uplift skin friction value of 1.7 kip per square foot be used to calculate
additional uplift resistance.
The drilled piers should be designed with full-length steel reinforcement to help transmit any
tensile stresses in the drilled pier shafts. Grade beams between the drilled piers should be
designed with a minimum 6-inch void space between the grade beam and underlying
subgrade to prevent heaving of the subgrades causing uplift forces on the bottom of those
grade beams. The voids should be formed using cardboard void boxes or other approved
methods to prevent an influx of debris or soil into the void space beneath the grade beams.
Based on previous experience with similar subsurface conditions in the area and on soil and
groundwater conditions observed at the time of our test borings, we do anticipate that
temporary casing may be required to prevent an influx of soil and water into the boreholes
required for construction of the drilled piers. Based on previous experience with similar
subsurface conditions in the area and on materials observed in the test borings, we anticipate
the drilled piers could be constructed using conventional augering techniques.
At the time of construction, care should be taken to place concrete in the open borings as
soon as practical after completion to prevent sloughing of the sidewalls of the caissons into
the open boreholes and/or drying of the bearing materials. Concrete placed in the drilled
piers should have a slump within the range of 5 to 8 inches to promote complete filling of
the drilled shaft excavation and prevent formation of voids in the shaft concrete. Care should
be taken at the time of construction to avoid "mushrooming" at the top of the drilled pier
excavations. The use of sono-tubes or other approved means may be necessary to maintain
a consistent shaft diameter if sloughing occurs in the near surface soils.
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EEC Project No. 18-01-197
November 6, 2018
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We estimate the long-term movement of drilled caisson foundations designed and
constructed as outlined above would be less than 1 inch. Developing and maintaining
positive drainage away from the structure and preventing accumulation of water below or
adjacent to the building will be critical for long-term performance of the drilled pier
foundations in the expansive claystone materials.
Interior Floors
Use of drilled pier foundations is recommended to reduce the potential for movement of the
building foundations with fluctuations in moisture content in the moderately expansive
clayey sandstone bedrock observed near anticipated foundation bearing levels in the area of
boring B-1. To prevent movement of the floor slabs in the same subsurface conditions,
interior living space floors for the residence could be supported as structural floors with a
void space between the bottom of the floor system and underlying expansive subgrade
materials. A minimum 10-inch void space could be developed beneath the bottom of the
floor system and underlying subgrade.
Garage and Exterior Slab-on-Grade Subgrades
Any existing vegetation and/or topsoil should be removed from floor slab areas. After
stripping and completing all cuts and prior to placement of any floor slabs or fill, we
recommend the exposed subgrades be scarified to a minimum depth of 9 inches, adjusted in
moisture content and compacted to at least 95% of the material's maximum dry density as
determined in accordance with ASTM Specification D-698, the standard Proctor procedure.
The moisture content of the scarified soils should be adjusted to be within the range of ±2%
of standard Proctor optimum moisture at the time of compaction.
Fill soils required to develop the floor slab subgrades should consist of approved, low-
volume change materials which are free from organic matter and debris. It is our opinion
the on-site clayey sand and gravel materials could be used as low-volume change fill in the
floor areas. The on-site clayey sandstone bedrock could be used for fill providing those
materials are thoroughly broken up prior to use for backfilling. Those fill materials should
be placed in loose lifts not to exceed 9 inches thick, adjusted in moisture content as
recommended for the scarified soils and compacted to at least 95% of standard Proctor
maximum dry density.
Earth Engineering Company, Inc.
EEC Project No. 18-01-197
November 6, 2018
Page 8
After preparation of the subgrades, care should be taken to avoid disturbing the in-place
materials. Subgrade materials 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 placement of the floor slab concrete.
As a precaution, the floor slabs should be isolated from structural portions of the building to
prevent distress to the structure due to differential movement of the structural elements. We
also recommend isolating the basement floor slab from non-load bearing partitions to help
reduce the potential for distress in upper sections of the building due to slab movement. That
isolation is typically developed through the use of a voided wall which is suspended from
the overhead first floor joist. Care should be exercised when framing doors, drywalling and
finishing to maintain a voided space which will allow for movement of the floor slab without
transmission of stresses to the overlying structure.
While laboratory testing completed for this report indicated the near surface site soils
sampled exhibited relatively low swell potential, floor slab and exterior flatwork movement
could occur and should be expected. Slab movement is common in Colorado even in areas
with relatively low-swelling soils. Mitigation techniques to reduce the potential for post-
construction movement, such as overexcavation, moisture conditioning and replacement
could be considered; however, the risk for slab movement cannot be eliminated.
Other Considerations
Positive drainage should be developed away from the structures with a minimum slope of 1
inch per foot for the first 10 feet away from the building. Care should be taken in planning
of landscaping adjacent to the residence to avoid features which would pond water adjacent
to the foundations or stemwalls. Placement of plants which require irrigation system or
could result in fluctuations of the moisture content of the subgrade material should be
avoided adjacent to the structure. Lawn watering systems should not be placed within 5 feet
of the perimeter of the building and spray heads should be designed not to spray water on or
immediately adjacent to the structure. Roof drains should be designed to discharge at least
5 feet away from the structure and away from the pavement areas.
Earth Engineering Company, Inc.
EEC Project No. 18-01-197
November 6, 2018
Page 9
GENERAL COMMENTS
The analysis and recommendations presented in this report are based upon the data obtained
from the preliminary 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 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 that 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 and foundation construction phases to help determine that the design
requirements are fulfilled.
This preliminary report has been prepared for the exclusive use of Mr. Kenneth Mitchell 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 modified or verified in writing by the geotechnical engineer.
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.
HARDNESS AND DEGREE OF CEMENTATION:
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
Silts and Clays
Liquid Limit 50 or
more
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
CLARENDON VILLAGE
PRELIMINARY
FORT COLLINS, CO
EEC PROJECT No. 18-01-197
OCTOBER 2018
CLARENDON VILLAGE PRELIMINARY
FORT COLLINS, COLORADO
PROJECT NO: 18-01-197 DATE: OCTOBER 2018
LOG OF BORING B-1
RIG TYPE: CME55 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 10/23/2018 WHILE DRILLING None
AUGER TYPE: 4" CFA FINISH DATE 10/23/2018 24 HOUR 19.5'
SPT HAMMER: AUTO SURFACE ELEV N/A 7 DAYS 17'
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
SAND AND GRAVEL (SP-GP) _ _
brown 1
clayey _ _
2
_ _
SANDSTONE CS 3 35 9000+ 7.9 119.0 36 20 51.0 6000 psf 3.7%
grey/tan/rust _ _
clayey 4
poorly cemented _ _
SS 5 50/11" 9000+ 10.4
_ _
6
_ _
7
_ _
8
_ _
9
_ _
CS 10 50/7" 9000+ 10.3 123.4 1200 psf 0.5%
_ _
11
_ _
12
_ _
13
_ _
14
_ _
SS 15 50/7" 8000 13.2
_ _
16
_ _
17
_ _
18
_ _
19
with claystone lenses CS _ _ 50/6" 9000+ 14.0 120.8 1600 psf 0.3%@1000
20
_ _
21
_ _
22
_ _
23
_ _
24
SS _ _ 50/4" 9000+ 12.4
24.5' BOTTOM OF BORING 25
CLARENDON VILLAGE PRELIMINARY
FORT COLLINS, COLORADO
PROJECT NO: 18-01-197 DATE: OCTOBER 2018
LOG OF BORING B-2
RIG TYPE: CME55 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 10/23/2018 WHILE DRILLING None
AUGER TYPE: 4" CFA FINISH DATE 10/23/2018 24 HOUR None
SPT HAMMER: AUTO SURFACE ELEV N/A 7 DAYS None
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
_ _
SAND AND GRAVEL (SP-GP) 1
brown _ _
medium dense 2
clayey _ _
CS 3 19 9000+ 9.1 107.6 < 500 psf None
_ _
4
_ _
SS 5 15 -- 6.7
_ _
6
_ _
7
_ _
SANDSTONE 8
grey/tan/rust _ _
poorly cemented 9
clayey CS _ _ 50/6" 9000+ 6.6 122.4 < 500 psf None
10
_ _
11
_ _
12
_ _
13
_ _
14
SS _ _ 50/6" -- 10.8
14.5' BOTTOM OF BORING 15
_ _
16
_ _
17
_ _
18
_ _
19
_ _
20
_ _
21
_ _
22
_ _
23
_ _
24
_ _
25
CLARENDON VILLAGE PRELIMINARY
FORT COLLINS, COLORADO
PROJECT NO: 18-01-197 DATE: OCTOBER 2018
LOG OF BORING B-3
RIG TYPE: CME55 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 10/23/2018 WHILE DRILLING None
AUGER TYPE: 4" CFA FINISH DATE 10/23/2018 24 HOUR 15.5'
SPT HAMMER: AUTO SURFACE ELEV N/A 7 DAYS 15.5'
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
_ _
SAND AND GRAVEL (SP-GP) 1
brown _ _
dense 2
clayey _ _
3
_ _
4
_ _
CS 5 31 9000+ 4.7 117.0 NL NP 20.9
_ _
6
_ _
SANDSTONE 7
grey/tan/rust _ _
poorly cemented 8
clayey _ _
9
_ _
SS 10 50/9" 7000 11.2
_ _
11
_ _
12
_ _
13
_ _
14
with a slight amount of clay CS _ _ 50/2" 8000 10.2 99.9 < 1000 psf None@1000
15
_ _
16
_ _
grey/rust 17
_ _
18
_ _
19
SS _ _ 50/3" -- 12.8
19.5' BOTTOM OF BORING 20
_ _
21
_ _
22
_ _
23
_ _
24
_ _
25
CLARENDON VILLAGE PRELIMINARY
FORT COLLINS, COLORADO
PROJECT NO: 18-01-197 DATE: OCTOBER 2018
LOG OF BORING B-4
RIG TYPE: CME55 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 10/23/2018 WHILE DRILLING 24'
AUGER TYPE: 4" CFA FINISH DATE 10/23/2018 24 HOUR 14.5'
SPT HAMMER: AUTO SURFACE ELEV N/A 7 DAYS 14.5'
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
_ _
SAND AND GRAVEL (SP-GP) 1
brown/light brown _ _
medium dense 2
clayey _ _
calcareous deposits 3
_ _
4
_ _
CS 5 30 9000+ 6.2 95.9 < 500 psf None
_ _
6
_ _
7
_ _
SANDSTONE 8
grey/tan/rust _ _
poorly cemented 9
clayey _ _
SS 10 50 9000+ 13.2
_ _
11
_ _
12
_ _
13
_ _
14
with a slight amount of clay CS _ _ 50/3" 6000 9.8 113.5 < 1000 psf None@1000
15
_ _
16
_ _
17
_ _
18
_ _
19
SS _ _ 50/3" -- 11.8
20
_ _
21
_ _
22
_ _
23
_ _
24
CS _ _ 50/2" -- 10.9
24.5' BOTTOM OF BORING 25
CLARENDON VILLAGE PRELIMINARY
FORT COLLINS, COLORADO
PROJECT NO: 18-01-197 DATE: OCTOBER 2018
LOG OF BORING B-5
RIG TYPE: CME55 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 10/23/2018 WHILE DRILLING None
AUGER TYPE: 4" CFA FINISH DATE 10/23/2018 24 HOUR None
SPT HAMMER: AUTO SURFACE ELEV N/A 7 DAYS 17'
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
_ _
SAND AND GRAVEL (SP-GP) 1
brown/light brown _ _
medium dense 2
clayey _ _
CS 3 29 9000+ 6.8 109.7 < 500 psf None
_ _
4
_ _
SS 5 16 -- 6.9
_ _
6
_ _
SANDSTONE 7
grey/tan/rust _ _
poorly cemented 8
clayey _ _
9
_ _
CS 10 50 9000+ 11.2 125.8 30 9 43.5 1500 psf 1.3%
_ _
11
_ _
12
_ _
13
_ _
14
with claystone lenses _ _
SS 15 50/7" 8000 11.3
_ _
16
_ _
17
_ _
18
_ _
19
CS _ _ 50/6" 9000+ 10.6 115.0 1200 psf 0.1%@1000
19.5' BOTTOM OF BORING 20
_ _
21
_ _
22
_ _
23
_ _
24
_ _
25
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Grey/Tan/Rust Clayey Sandstone
Sample Location: B-1, S-1 @ 2'
Liquid Limit: 36 Plasticity Index: 20 % Passing #200: 51.0
Beginning Moisture: 10.3% Dry Density: 119.0 pcf Ending Moisture: 17.1%
Swell Pressure: 6000 psf % Swell @ 500 psf: 3.7%
Project: Clarendon Village Preliminary
Fort Collins, Colorado
Project No.: 18-01-197
Date: October 2018
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.01 0.1 1 10
Percent Movement
Load (TSF)
Water Added
Consolidation Swell
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Grey/Tan/Rust Clayey Sandstone
Sample Location: B-1, S-3 @ 9'
Liquid Limit: -- Plasticity Index: -- % Passing #200: --
Beginning Moisture: 10.7% Dry Density: 123.4 pcf Ending Moisture: 13.6%
Swell Pressure: 1200 psf % Swell @ 500 psf: 0.5%
Project: Clarendon Village Preliminary
Fort Collins, Colorado
Project No.: 18-01-197
Date: October 2018
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.01 0.1 1 10
Percent Movement
Load (TSF)
Water Added
Consolidation Swell
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Grey/Tan/Rust Clayey Sandstone
Sample Location: B-1, S-5 @ 19'
Liquid Limit: -- Plasticity Index: -- % Passing #200: --
Beginning Moisture: 11.3% Dry Density: 120.8 pcf Ending Moisture: 15.6%
Swell Pressure: 1600 psf % Swell @ 500 psf: 0.3%
Project: Clarendon Village Preliminary
Fort Collins, Colorado
Project No.: 18-01-197
Date: October 2018
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.01 0.1 1 10
Percent Movement
Load (TSF)
Water Added
Consolidation Swell
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown Clayey Sand and Gravel
Sample Location: B-2, S-1 @ 2'
Liquid Limit: -- Plasticity Index: -- % Passing #200: --
Beginning Moisture: 8.6% Dry Density: 107.6 pcf Ending Moisture: 19.0%
Swell Pressure: < 500 psf % Swell @ 500 psf: None
Project: Clarendon Village Preliminary
Fort Collins, Colorado
Project No.: 18-01-197
Date: October 2018
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.01 0.1 1 10
Percent Movement
Load (TSF)
Water Added
Consolidation Swell
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Grey/Tan/Rust Clayey Sandstone
Sample Location: B-2, S-3 @ 9'
Liquid Limit: -- Plasticity Index: -- % Passing #200: --
Beginning Moisture: 6.8% Dry Density: 122.4 pcf Ending Moisture: 16.3%
Swell Pressure: < 500 psf % Swell @ 500 psf: None
Project: Clarendon Village Preliminary
Fort Collins, Colorado
Project No.: 18-01-197
Date: October 2018
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.01 0.1 1 10
Percent Movement
Load (TSF)
Water Added
Consolidation Swell
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Grey/Tan/Rust Clayey Sandstone
Sample Location: B-3, S-3 @ 14'
Liquid Limit: -- Plasticity Index: -- % Passing #200: --
Beginning Moisture: 19.2% Dry Density: 99.9 pcf Ending Moisture: 15.5%
Swell Pressure: < 500 psf % Swell @ 500 psf: None
Project: Clarendon Village Preliminary
Fort Collins, Colorado
Project No.: 18-01-197
Date: October 2018
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.01 0.1 1 10
Percent Movement
Load (TSF)
Water Added
Consolidation Swell
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown/Light Brown Clayey Sand and Gravel
Sample Location: B-4, S-1 @ 4'
Liquid Limit: -- Plasticity Index: -- % Passing #200: --
Beginning Moisture: 6.2% Dry Density: 95.9 pcf Ending Moisture: 27.3%
Swell Pressure: < 500 psf % Swell @ 500 psf: None
Project: Clarendon Village Preliminary
Fort Collins, Colorado
Project No.: 18-01-197
Date: October 2018
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.01 0.1 1 10
Percent Movement
Load (TSF)
Water Added
Consolidation Swell
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Grey/Tan/Rust Sandstone
Sample Location: B-4, S-3 @ 14'
Liquid Limit: -- Plasticity Index: -- % Passing #200: --
Beginning Moisture: 9.6% Dry Density: 113.5 pcf Ending Moisture: 16.2%
Swell Pressure: < 500 psf % Swell @ 500 psf: None
Project: Clarendon Village Preliminary
Fort Collins, Colorado
Project No.: 18-01-197
Date: October 2018
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.01 0.1 1 10
Percent Movement
Load (TSF)
Water Added
Consolidation Swell
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Brown/Light Brown Clayey Sand and Gravel
Sample Location: B-5, S-1 @ 2'
Liquid Limit: -- Plasticity Index: -- % Passing #200: --
Beginning Moisture: 5.5% Dry Density: 109.7 pcf Ending Moisture: 22.6%
Swell Pressure: < 500 psf % Swell @ 500 psf: None
Project: Clarendon Village Preliminary
Fort Collins, Colorado
Project No.: 18-01-197
Date: October 2018
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.01 0.1 1 10
Percent Movement
Load (TSF)
Water Added
Consolidation Swell
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Grey/Tan/Rust Clayey Sandstone
Sample Location: B-5, S-3 @ 9'
Liquid Limit: 30 Plasticity Index: 9 % Passing #200: 43.5
Beginning Moisture: 9.6% Dry Density: 125.8 pcf Ending Moisture: --
Swell Pressure: 1500 psf % Swell @ 500 psf: 1.3%
Project: Clarendon Village Preliminary
Fort Collins, Colorado
Project No.: 18-01-197
Date: October 2018
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.01 0.1 1 10
Percent Movement
Load (TSF)
Water Added
Consolidation Swell
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Grey/Tan/Rust Clayey Sandstone
Sample Location: B-5, S-5 @ 19'
Liquid Limit: -- Plasticity Index: -- % Passing #200: --
Beginning Moisture: 11.7% Dry Density: 115.0 pcf Ending Moisture: --
Swell Pressure: 1200 psf % Swell @ 500 psf: 0.1%
Project: Clarendon Village Preliminary
Fort Collins, Colorado
Project No.: 18-01-197
Date: October 2018
-10
-8
-6
-4
-2
0
2
4
6
8
10
0.01 0.1 1 10
Percent Movement
Load (TSF)
Water Added
Consolidation Swell
Earth Engineering Company
Earth Engineering Company
Earth Engineering Company
Earth Engineering Company
Earth Engineering Company
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
Unified Soil ClaSSifiCation SyStem
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
Silts and Clays
Liquid Limit less
than 50
IIf soil contains >15% gravel, add "with gravel" to
group name
JIf Atterberg limits plots shaded area, soil is a CL-
ML, Silty clay
GIf fines classify as CL-ML, use dual symbol GC-
CM, or SC-SM.
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
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
Earth Engineering Company