HomeMy WebLinkAboutOLD TOWN NORTH FIFTH FILING REPLAT OF TRACT F - BDR190016 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTSeptember 30, 2019
PhilGreen Construction
1420 Blue Spruce Drive, Unit G
Fort Collins, Colorado 80524
Attn: Mr. Mitch Greeno (mitch@philgreenco.com)
Re: Geotechnical Subsurface Exploration
Old Town North Townhomes/Commercial Building M1-M4
Detached Garages G1-G4
Fort Collins, Colorado
EEC Project No. 19-01-150
Mr. Greeno:
Earth Engineering Company, Inc. (EEC) personnel have completed the geotechnical subsurface
exploration you requested for the construction of a multi-plex townhome building, commercial
building and detached garages to be constructed in an area north of the intersection of Osiander
Street and Jerome Streets in the Old Town North Subdivision in Fort Collins, Colorado. Results
of the subsurface exploration completed by EEC personnel are provided with this report.
We understand the proposed multi-plex townhome building, commercial building and detached
garages will be one or two-story wood frame structures constructed with full basements and/or
slab-on-grade type foundations. We expect foundation loads for that structure would be light with
continuous wall loads less than 3 kips per lineal foot and individual column loads less than 50 kips.
Small grade changes are expected to develop final site grades for the structure.
The purpose of this report is to describe the subsurface conditions encountered in the test borings
completed within the identified building envelopes on the site and provide geotechnical
recommendations for design and construction of foundations and support of floor slabs and
exterior flatwork.
To develop information on existing subsurface conditions in the area of the proposed buildings,
six (6) soil borings were extended to a depth of approximately 20 and 25 feet within the designated
building envelopes. The locations of the test borings were established by pacing and estimating
angles from site property pins and identifiable site features. The locations of the borings should
Earth Engineering Company, Inc.
EEC Project No. 19-01-150
September 30, 2019
Page 2
be considered accurate only to the degree implied by the methods used to make the field
measurements.
The borings were performed using a truck-mounted, rotary-type 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 and samples of the subsurface materials encountered
were obtained using split-barrel and California barrel sampling procedures in general accordance
with ASTM Specification D-1586. All samples obtained in the field were sealed and returned to
the laboratory for further examination, classification and testing.
EEC field personnel were on-site during drilling to evaluate the subsurface conditions encountered
and direct the drilling activities. Field boring logs were prepared based on observation of disturbed
samples and auger cuttings. Based on results of the field borings and laboratory testing, subsurface
conditions in the proposed residence location can be generalized as follows.
Dark brown sandy lean clay soils were encountered at the surface at the boring locations. The dark
brown sandy lean clay soils encountered in the borings were very stiff in consistency, contained
gravel and exhibited a low to moderate potential for swelling with increase in moisture content at
current moisture/density conditions. The moderately plastic sandy lean clay soils were underlain
by brown sand and gravel materials at a depth of approximately 6 feet below present site grades.
The essentially granular materials encountered in the borings contained cobbles and were dense to
very dense in consistency. The sand and gravel materials extended to the bottom of the borings at
a depth of approximately 20 and 25 feet below present site grades.
Observations were made at the time of drilling and approximately 24 hours after drilling to
evaluate the presence and depth to free water at the test boring locations. At the time of drilling,
free water was observed at a depth of approximately 12 to 14 feet below present site grades.
Approximately 24 hours after drilling, the borings were collapsed at a depth of approximately 5 to
8 feet below present site grades. Longer-term observations in holes which are cased and sealed
from the influence of surface water would be required to more accurately evaluate groundwater
levels and possible fluctuations in those groundwater levels over time. Fluctuations in
groundwater levels can occur based on hydrologic conditions and other conditions not apparent at
the time of this report. Zones of perched and/or trapped water may also be encountered in more
permeable zones within the subgrade soils at times throughout the year.
Earth Engineering Company, Inc.
EEC Project No. 19-01-150
September 30, 2019
Page 3
The stratification boundaries indicated on the boring logs represent the approximate location of
changes in soil types; in-situ, the transition of materials may be gradual and indistinct. In addition,
the soil borings provide an indication of subsurface conditions at the test locations; however,
subsurface conditions may vary in relatively short distances away from the borings. Potential
variations in subsurface conditions can best be evaluated by close observation and testing of the
subgrade materials during construction. If significant variations from the conditions anticipated
from the test borings appear evident at that time, it may be necessary to re-evaluate the
recommendations provided in this report.
ANALYSIS AND RECOMMENDATIONS
General
The near surface materials encountered in the soil borings completed in the approximate location
of the townhome, garage and commercial building structures consisted of moderately plastic sandy
lean clay soils underlain by essentially granular materials. The sandy lean clay soils exhibited a
low to moderate potential for swelling with variation in moisture content. Foundation elements
supported directly on the moderately expansive sandy lean clay soils in their current
moisture/density conditions would be expected to experience some post-construction heaving.
Presented below are our recommendations for construction of the residence using conventional
footing foundations supported over a zone of low-swelling controlled, compacted fill. It should be
noted that construction in areas with expansive soils and bedrock carries with it inherent risks
regardless of the foundation type chosen. Those risks include post-construction movement of
foundations, floor slabs, exterior flatwork and other site improvements.
Overexcavation
To reduce the potential for post-construction movement in the foundation and floor slabs
subsequent to construction, we recommend a zone of material immediately underlying foundations
and floor slabs where the expansive sandy lean clay soils are encountered be overexcavated and
backfilled to develop floor slab and foundation bearing levels. The overexcavation and backfill
procedures will provide a zone of material immediately beneath the foundations and floor slabs
which will have low potential for swelling subsequent to construction and, therefore, would reduce
the potential for total and differential movement subsequent to construction.
Earth Engineering Company, Inc.
EEC Project No. 19-01-150
September 30, 2019
Page 4
To develop the floor slab and footing support, we recommend areas beneath the floor slabs and
footings be undercut by at least 4 feet or through the expansive sandy lean clay soil layer to the
underlying sand and gravel and the overexcavation material be replaced as controlled, compacted
fill. The overexcavation area should extend at least 2 feet beyond the exterior perimeter of the
foundations. The overexcavation zones should be completed at both the at-grade (i.e. garage) and
basement areas of the structures and any other areas where the expansive sandy lean clay soils are
encountered.
Fill soils required to develop foundation and floor slab support should consist of approved,
cohesive low- volume change fill free from organic matter and debris. Class-7 structural fill, reject,
“chips”, crushed/recycled concrete or other approved materials could be used as fill. Fill materials
should contain sufficient fines to prevent ponding of water in the subgrade. The fill soils should
be placed in loose lifts not to exceed 9 inches thick, adjusted in moisture content and compacted
to be 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 fill soils should
be adjusted to be with a ±2% of optimum moisture at the time of compaction.
Footing Foundations
For design of footing foundations supported on suitable fill soils placed as outlined above and on
the essentially granular materials, we recommend using a net allowable total load soil bearing
pressure not to exceed 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.
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. Trenched foundations or grade beam foundations could be used in site soils.
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
Earth Engineering Company, Inc.
EEC Project No. 19-01-150
September 30, 2019
Page 5
long-term movement of footing foundations designed and constructed as recommended above
would be less than 1 inch.
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 movement of footing foundations designed and constructed as recommended above
would be less than 1 inch.
Groundwater was observed in the test borings at a depth of approximately 12 to 14 feet below
present site grades. Approximately 24 hours after drilling, the borings were collapsed at a depth of
approximately 5 to 8 feet below present site grades. 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. Full depth basement
construction may not be feasible for the proposed structures.
Care should be taken during construction to avoid disturbing the bearing soils. Soils which are
loosened or disturbed by the construction activities or materials which become wetted and softened
or dry and desiccated should be removed and replaced or reworked in place prior to placement of
reinforcing steel and foundation concrete.
While the overexcavation and backfill procedure outlined above would reduce the potential for
post-construction heaving of the overlying improvements, the potential for post-construction
movement cannot be entirely eliminated. Deeper overexcavation and backfilling could be
considered to further reduce the risk of heaving of the overlying improvements, but that risk cannot
be eliminated.
Floor Slab Subgrades
Floor slabs could be placed directly on the subgrade soils prepared as outlined above and on the
essentially granular materials. Care should be taken immediately prior to placement of the floor
Earth Engineering Company, Inc.
EEC Project No. 19-01-150
September 30, 2019
Page 6
slab concrete to evaluate the moisture content of the subgrade materials and, if necessary, adjust
the moisture content to the range recommended for the backfill placement.
As a precaution, the floor slabs should be isolated from structural portions of the building to
prevent differential movement to those elements causing distress to the structure. With the
overexcavation procedures recommended, we expect the differential movement would be limited.
We recommend the basement floor slab be isolated from non-load bearing partitions to help reduce
the potential for slab movement causing distress in upper sections of the building. That isolation
is typically developed through the use of a voided wall which is suspended from the overhead first
floor joist. Care should be taken in door framing, 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.
Exterior Slab-on-Grade Subgrades
In exterior slab-on-grade areas, those slabs may be supported on existing site soils or newly placed
and compacted fill. Any existing vegetation and/or topsoil should be removed from the flatwork
areas. After stripping and completing all cuts and prior to placement of any fill or flatwork, we
recommend the in-place soils be scarified to a minimum depth of 9 inches, adjusted in moisture
content and compacted to be 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 exterior flatwork subgrades should consist of approved, low-volume
change materials which are free from organic matter and debris. The on-site granular materials
could be used as fill beneath the exterior slabs-on-grade. We recommend fill soils for support of
exterior slabs be placed in loose lifts not to exceed 9 inches thick, adjusted in moisture content as
recommended for the scarified materials and compacted to be 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 in-place materials.
Soils which become loosened or disturbed or materials which become dry and desiccated or wet
Earth Engineering Company, Inc.
EEC Project No. 19-01-150
September 30, 2019
Page 7
and softened should be removed and replaced or reworked in place prior to placement of the
overlying improvements.
Post-construction movement of exterior flatwork placed directly on the near surface site soils could
occur and should be expected. To reduce the potential for post-construction movement of exterior
flatwork overexcavation and backfilling as outlined in the General section could be considered;
however, that potential cannot be eliminated.
Below Grade Areas
We recommend a perimeter drain system be installed around all below grade areas to reduce the
potential for development of hydrostatic loads on the below grade walls and to help prevent
accumulation of infiltration water in below grade areas. In general, a perimeter drain system
should consist of perforated metal or plastic pipe placed at approximate foundation bearing level
around the exterior perimeter of the structure. The drainline should be surrounded by a minimum
of 6 inches of appropriately sized granular filter soil and either the filter soil or drainline should be
surrounded by a filter fabric to help reduce the potential infiltration of fines into the drain system.
The drainline should be sloped to provide positive gravity drainage of water to a sump area or
gravity outfall where reverse flow cannot occur into the system.
Backfill placed adjacent to the below grade walls should consist of approved, low-volume change
soils which are free from organic matter and debris. The on-site essentially granular materials
could be used as fill in this area. If free draining granular soils are used as backfill adjacent to the
below grade areas, we recommend the top 2 feet of material be an essentially cohesive material to
help reduce the potential for immediate surface water infiltration into the backfill. The backfill
soils should be placed in loose lifts not to exceed 9 inches thick, adjusted in moisture content and
compacted to be at least 95% of the material's maximum dry density as determined in accordance
with the standard Proctor procedure. The moisture content of the backfill soils should be adjusted
to be within the range of ±2% of standard Proctor optimum moisture.
Care should be taken in placing and compacting the wall backfill to avoid placing undue lateral
stress on the below grade walls. We recommend compaction using light mechanical or hand
compaction equipment.
Earth Engineering Company, Inc.
EEC Project No. 19-01-150
September 30, 2019
Page 8
For design of below grade walls where appropriate steps have been taken to eliminate hydrostatic
loads, we recommend using an equivalent fluid pressure of 55 pounds per cubic foot. The
recommended design equivalent fluid pressure is based on an active stress distribution case where
slight rotation is expected in the below grade walls. The rotation expected to develop an active
stress distribution case results in deflection on the wall of approximately 0.5% times the height of
the wall. That deflection may result in stress cracks on the interior of the basement walls,
particularly near the center of spans between corners or other restrained points. The recommended
equivalent fluid pressure does not include an allowance for hydrostatic loads nor does it include a
factor of safety. Surcharge loads placed adjacent to below grade walls or point loads placed in the
wall backfill may add to the lateral pressures of below grade walls.
Other Considerations
Positive drainage should be developed away from the structure 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.
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 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
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
OLD TOWN NORTH
TOWNHOMES
FORT COLLINS, CO
EEC PROJECT No. 19-01-150
SEPTEMBER 2019
OLD TOWN NORTH TOWNHOMES/COMMERCIAL BUILDING M1-M4
FORT COLLINS, COLORADO
PROJECT NO: 19-01-150 DATE: SEPTEMBER 2019
LOG OF BORING B-1
RIG TYPE: CME55 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 9/24/2019 WHILE DRILLING 14'
AUGER TYPE: 4" CFA FINISH DATE 9/24/2019 AFTER DRILLING 14'
SPT HAMMER: AUTO SURFACE ELEV N/A 24 HOUR COLLAPSED @ 5'
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
_ _
SANDY LEAN CLAY (CL) 1
dark brown _ _
very stiff 2
silty with gravel _ _
CS 3 46 9000+ 13.2 98.2 1700 psf 3.3%
_ _
4
_ _
CS 5 26 9000+ 6.9 107.4 < 500 psf None
_ _
6
_ _
SAND AND GRAVEL (SP-GP) 7
brown _ _
very dense 8
with cobbles _ _
9
_ _
SS 10 50/11" -- 0.8
_ _
11
_ _
12
_ _
13
_ _
14
_ _
BS 15 -- -- 2.6
_ _
16
_ _
17
_ _
18
_ _
19
_ _
BS 20 -- -- 0.5
_ _
21
_ _
22
_ _
23
_ _
24
_ _
25' BOTTOM OF BORING BS 25 -- -- 9.3
OLD TOWN NORTH TOWNHOMES/COMMERCIAL BUILDING M1-M4
FORT COLLINS, COLORADO
PROJECT NO: 19-01-150 DATE: SEPTEMBER 2019
LOG OF BORING B-2
RIG TYPE: CME55 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 9/24/2019 WHILE DRILLING 14'
AUGER TYPE: 4" CFA FINISH DATE 9/24/2019 AFTER DRILLING 14'
SPT HAMMER: AUTO SURFACE ELEV N/A 24 HOUR COLLAPSED @ 8'
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
_ _
SANDY LEAN CLAY (CL) 1
dark brown _ _
very stiff 2
silty with gravel _ _
3
_ _
4
_ _
CS 5 23 9000+ 11.8 109.0 46 34 83.3 5400 psf 4.9%
_ _
6
_ _
SAND AND GRAVEL (SP-GP) 7
brown _ _
dense 8
with cobbles _ _
9
_ _
SS 10 50 -- 1.0
_ _
11
_ _
12
_ _
13
_ _
14
_ _
BS 15 -- -- 5.9
_ _
16
_ _
17
_ _
18
_ _
19
_ _
BS 20 -- -- 8.6
20' BOTTOM OF BORING _ _
21
_ _
22
_ _
23
_ _
24
_ _
25
OLD TOWN NORTH TOWNHOMES/COMMERCIAL BUILDING M1-M4
FORT COLLINS, COLORADO
PROJECT NO: 19-01-150 DATE: SEPTEMBER 2019
LOG OF BORING B-3
RIG TYPE: CME55 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 9/24/2019 WHILE DRILLING 14'
AUGER TYPE: 4" CFA FINISH DATE 9/24/2019 AFTER DRILLING 14'
SPT HAMMER: AUTO SURFACE ELEV N/A 24 HOUR COLLAPSED @ 7'
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
_ _
SANDY LEAN CLAY (CL) 1
dark brown _ _
very stiff 2
silty with gravel _ _
CS 3 20 9000+ 11.7 114.9 37 26 73.3 1600 psf 1.7%
_ _
4
_ _
CS 5 16 9000+ 9.1 99.0 800 psf 0.7%
_ _
6
_ _
SAND AND GRAVEL (SP-GP) 7
brown _ _
very dense 8
with cobbles _ _
9
_ _
SS 10 33/9" -- 0.9
_ _
11
_ _
12
_ _
13
_ _
14
_ _
BS 15 -- -- 6.2
_ _
16
_ _
17
_ _
18
_ _
19
_ _
BS 20 -- -- 3.2
_ _
21
_ _
22
_ _
23
_ _
24
_ _
25' BOTTOM OF BORING BS 25 -- -- 5.5
OLD TOWN NORTH TOWNHOMES/COMMERCIAL BUILDING M1-M4
FORT COLLINS, COLORADO
PROJECT NO: 19-01-150 DATE: SEPTEMBER 2019
LOG OF BORING B-4
RIG TYPE: CME55 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 9/24/2019 WHILE DRILLING 12'
AUGER TYPE: 4" CFA FINISH DATE 9/24/2019 AFTER DRILLING 12'
SPT HAMMER: AUTO SURFACE ELEV N/A 24 HOUR COLLAPSED @ 7'
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
_ _
SANDY LEAN CLAY (CL) 1
dark brown _ _
very stiff 2
silty with gravel _ _
3
_ _
4
_ _
CS 5 16 9000+ 10.8 112.5 1800 psf 2.0%
_ _
6
_ _
SAND AND GRAVEL (SP-GP) 7
brown _ _
very dense 8
with cobbles _ _
9
_ _
SS 10 50/11" -- 1.3
_ _
11
_ _
12
_ _
13
_ _
14
_ _
BS 15 -- -- 2.4
_ _
16
_ _
17
_ _
18
_ _
19
_ _
BS 20 -- -- 7.9
20' BOTTOM OF BORING _ _
21
_ _
22
_ _
23
_ _
24
_ _
25
OLD TOWN NORTH TOWNHOMES/COMMERCIAL BUILDING M1-M4
FORT COLLINS, COLORADO
PROJECT NO: 19-01-150 DATE: SEPTEMBER 2019
LOG OF BORING B-5
RIG TYPE: CME55 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 9/24/2019 WHILE DRILLING 14'
AUGER TYPE: 4" CFA FINISH DATE 9/24/2019 AFTER DRILLING 14'
SPT HAMMER: AUTO SURFACE ELEV N/A 24 HOUR COLLAPSED @ 7'
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
_ _
SANDY LEAN CLAY (CL) 1
dark brown _ _
very stiff 2
silty with gravel _ _
CS 3 13 9000+ 18.6 104.7 41 25 93.3 4000 psf 2.5%
_ _
4
_ _
CS 5 20 9000+ 11.9 115.6 1700 psf 1.1%
_ _
6
_ _
SAND AND GRAVEL (SP-GP) 7
brown _ _
very dense 8
with cobbles _ _
9
_ _
SS 10 41/11" -- 1.2
_ _
11
_ _
12
_ _
13
_ _
14
_ _
BS 15 -- -- 3.7
_ _
16
_ _
17
_ _
18
_ _
19
_ _
BS 20 -- -- 10.0
_ _
21
_ _
22
_ _
23
_ _
24
_ _
25' BOTTOM OF BORING BS 25 -- -- 13.0
OLD TOWN NORTH TOWNHOMES/COMMERCIAL BUILDING M1-M4
FORT COLLINS, COLORADO
PROJECT NO: 19-01-150 DATE: SEPTEMBER 2019
LOG OF BORING B-6
RIG TYPE: CME55 SHEET 1 OF 1 WATER DEPTH
FOREMAN: SM START DATE 9/24/2019 WHILE DRILLING 14'
AUGER TYPE: 4" CFA FINISH DATE 9/24/2019 AFTER DRILLING 14'
SPT HAMMER: AUTO SURFACE ELEV N/A 24 HOUR COLLAPSED @ 8'
SOIL DESCRIPTION D N QU MC DD A-LIMITS -200 SWELL
TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF
_ _
SANDY LEAN CLAY (CL) 1
dark brown _ _
very stiff 2
silty with gravel _ _
3
_ _
4
_ _
CS 5 10 9000+ 13.0 99.7 3000 psf 4.7%
_ _
6
_ _
SAND AND GRAVEL (SP-GP) 7
brown _ _
very dense 8
with cobbles _ _
9
SS _ _ 50/3" -- 5.1
10
_ _
11
_ _
12
_ _
13
_ _
14
_ _
BS 15 -- -- 4.3
_ _
16
_ _
17
_ _
18
_ _
19
_ _
BS 20 -- -- 5.7
20' BOTTOM OF BORING _ _
21
_ _
22
_ _
23
_ _
24
_ _
25
SWELL / CONSOLIDATION TEST RESULTS
Material Description: Dark Brown Sandy Lean Clay with Gravel
Sample Location: B-1, S-1 @ 2'
Liquid Limit: -- Plasticity Index: -- % Passing #200: --
Beginning Moisture: 9.7% Dry Density: 98.2 pcf Ending Moisture: 25.2%
Swell Pressure: 1700 psf % Swell @ 500 psf: 3.3%
Project: Old Town North Townhomes M1-M4
Fort Collins, Colorado
Project No.: 19-01-150
Date: September 2019
-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: Dark Brown Sandy Lean Clay with Gravel
Sample Location: B-1, S-2 @ 4'
Liquid Limit: -- Plasticity Index: -- % Passing #200: --
Beginning Moisture: 7.2% Dry Density: 107.4 pcf Ending Moisture: 20.0%
Swell Pressure: < 500 psf % Swell @ 500 psf: None
Project: Old Town North Townhomes M1-M4
Fort Collins, Colorado
Project No.: 19-01-150
Date: September 2019
-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: Dark Brown Sandy Lean Clay with Gravel
Sample Location: B-2, S-1 @ 4'
Liquid Limit: 46 Plasticity Index: 34 % Passing #200: 83.3
Beginning Moisture: 14.3% Dry Density: 109.0 pcf Ending Moisture: 20.6%
Swell Pressure: 5400 psf % Swell @ 500 psf: 4.9%
Project: Old Town North Townhomes M1-M4
Fort Collins, Colorado
Project No.: 19-01-150
Date: September 2019
-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: Dark Brown Sandy Lean Clay with Gravel
Sample Location: B-3, S-1 @ 2'
Liquid Limit: 37 Plasticity Index: 26 % Passing #200: 73.3
Beginning Moisture: 11.3% Dry Density: 114.9 pcf Ending Moisture: 19.4%
Swell Pressure: 1600 psf % Swell @ 500 psf: 1.7%
Project: Old Town North Townhomes M1-M4
Fort Collins, Colorado
Project No.: 19-01-150
Date: September 2019
-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: Dark Brown Sandy Lean Clay with Gravel
Sample Location: B-3, S-2 @ 4'
Liquid Limit: -- Plasticity Index: -- % Passing #200: --
Beginning Moisture: 12.3% Dry Density: 99.0 pcf Ending Moisture: 26.2%
Swell Pressure: 800 psf % Swell @ 500 psf: 0.7%
Project: Old Town North Townhomes M1-M4
Fort Collins, Colorado
Project No.: 19-01-150
Date: September 2019
-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: Dark Brown Sandy Lean Clay with Gravel
Sample Location: B-4, S-1 @ 4'
Liquid Limit: -- Plasticity Index: -- % Passing #200: --
Beginning Moisture: 13.5% Dry Density: 112.5 pcf Ending Moisture: 20.6%
Swell Pressure: 1800 psf % Swell @ 500 psf: 2.0%
Project: Old Town North Townhomes M1-M4
Fort Collins, Colorado
Project No.: 19-01-150
Date: September 2019
-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: Dark Brown Sandy Lean Clay with Gravel
Sample Location: B-5, S-1 @ 2'
Liquid Limit: 41 Plasticity Index: 25 % Passing #200: 93.3
Beginning Moisture: 17.0% Dry Density: 104.7 pcf Ending Moisture: 23.9%
Swell Pressure: 4000 psf % Swell @ 500 psf: 2.5%
Project: Old Town North Townhomes M1-M4
Fort Collins, Colorado
Project No.: 19-01-150
Date: September 2019
-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: Dark Brown Sandy Lean Clay with Gravel
Sample Location: B-5, S-2 @ 4'
Liquid Limit: -- Plasticity Index: -- % Passing #200: --
Beginning Moisture: 15.2% Dry Density: 115.6 pcf Ending Moisture: 19.5%
Swell Pressure: 1700 psf % Swell @ 500 psf: 1.1%
Project: Old Town North Townhomes M1-M4
Fort Collins, Colorado
Project No.: 19-01-150
Date: September 2019
-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: Dark Brown Sandy Lean Clay with Gravel
Sample Location: B-6, S-1 @ 4'
Liquid Limit: -- Plasticity Index: -- % Passing #200: --
Beginning Moisture: 14.9% Dry Density: 99.7 pcf Ending Moisture: 28.1%
Swell Pressure: 3000 psf % Swell @ 500 psf: 4.7%
Project: Old Town North Townhomes M1-M4
Fort Collins, Colorado
Project No.: 19-01-150
Date: September 2019
-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
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