HomeMy WebLinkAboutGLENMOOR DRIVE PUD - PRELIMINARY - 8-95A - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTLOG OF BORING No. 4
Page I of 1
CLIENT
ARCHITECT/ENGINEER
R. Kint Glover
SITE West Plum Street & Glenmoor Drive
PROJECT
Fort Collins, Colorado
Glenmoor Drive Subdivision
SAMPLES
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10.0 85.5
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BOTTOM OF BORING
THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES
BETWEEN SOIL AND ROCK TYPES: IN -SITU, THE TRANSITION MAY BE GRADUAL.
WATER LEVEL OBSERVATIONS
BORING STARTED 3-7-95
Empire Laboratories
Incorporated
Division of Terrecon
g 2.5' W.D.
= 1_0A.B.
BORING COMPLETED 3-7-95
rWL
WL
RIG CME-55
FOREMAN DML
WL
Water checked 7 days A.B.
APPROVED LRS
JOB if 20955038
LOG OF BORING No. 3 Page 1 of 1
CLIENT
R. 1{int Glover
ARCHITECT/ENGINEER
SITE West Plum Street & Glemnoor Drive
Fort Collins, Colorado
PROJECT
Glenmoor Drive Subdivision
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12.0 84.0
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12"
23
16
C'LAYSTONE
Tan/olive, moist, moderately hard
15.0 81.0
BOTTOM OF BORING
5
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12"
45
19
THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES
BETWEEN SOIL AND ROCK TYPES: IN -SITU, THE TRANSITION MAY BE GRADUAL.
WATER LEVEL OBSERVATIONS
Empire Laboratories
Incorporated
Division of Terracon
BORING STARTED 3-7-95
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1X A.B.
BORING COMPLETED 3-7-95
wL
RIG CME-55
FOREMAN DMI,
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Water checked 7 days A.B.
APPROVED LRS
JOB k 20955038
I
LOG OF BORING No. 2 Page 1 of 1
CLIENT
R. I{int Glover
ARCHITECT/ENGINEER
SITE West Plum Street & Glenmoor Drive
Fort Collins, Colorado
PROJECT
Glenmoor Drive Subdivision
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6
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12"
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113
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SANDY LEAN CLAY
Tan, wet, stiff to medium stiff
6.5 88.5
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8
22
WEATHERED CLAYSTONE
Tan/olive, moist, soft
10.0 8 5 01
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12"
35
18
CLAYSTONE
Tan/olive, moist, moderately hard
15.0 8040
5
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12"
42
15
BOTTOM OF BORING
THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES
BETWEEN SOIL AND ROCK TYPES: IN -SITU, THE TRANSITION MAY BE GRADUAL.
WATER LEVEL OBSERVATIONS
Empire Laboratories
Incorporated
Division of Termcon
BORING STARTED 3-7-95
WL
y None W.D.
i 0.3' A.B.
BORING COMPLETED 3-7-95
,M
RIG CME-554FOOREMAN
D1y11
Water checked 7 days A.B.
APPROVED LR20955038
B NwL
LOG OF BORING No. 1
Page 1 of 1
CLIENT
ARCHITECT/ENGINEER
R. Vint Glover
SITE West Plum Street & Glenmoor Drive
PROJECT
Fort Collins, Colorado
Glenmoor Drive Subdivision
SAMPLES
TESTS
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140
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12"
8
22
SANDY LEAN CLAY
Tan, wet, stiff to medium stiff
5
7.0 89.0
3
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12"
17
20
WEATHERED CLAYSTONE
Tan/olive, moist, soft
10
12.5 83.5
15
CLAYSTONE
Tan/olive, moist, moderately hard
15.0 81.0
4
SS
12"
36
15
BOTTOM OF BORING
THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES
BETWEEN SOIL AND ROCK TYPES: IN -SITU, THE TRANSITION MAY BE GRADUAL.
WATER LEVEL OBSERVATIONS
Empire Laboratories
Incorporated
Division of Terracon
BORING STARTED 3-7-95
WL
g None W.D.
i 1.0' A.B.
BORING COMPLETED 3-7-95
WL
RIG CME-55
FOREMAN DML
WL
Water checked 7 days A.B.
APPROVED LRS
JOB H 20955038
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FIGURE 1:
WEST PLUM STREET
SITE PLAN
GLENMOOR DRIVE SUBDIVISION
FORT COLLINS, COLORADO
ELI. PROJECT No. 20955038
SCALE 1" = 100'
Empire Laboratories, Inc.
Geotechnical Engineering Exploration Terracon
Mr. R. Kint Glover
ELI Project No. 20955038
The analyses and recommendations in this report are based in part upon data obtained from
the field exploration. The nature and extent of variations beyond the location of test
borings may not become evident until construction. If variations then appear evident, it
may be necessary to re-evaluate the recommendations of this report.
Our professional services were performed using that degree of care and skill ordinarily _-
exercised, under similar circumstances, by reputable geotechnical engineers practicing in
this or similar localities. No warranty, express or implied, is made. We prepared the report
as an aid in design of the proposed project. This report is not a bidding document. Any
contractor reviewing this report must draw his own conclusions regarding site conditions
and specific construction techniques to be used on this project.
This report is for the exclusive purpose of providing geotechnical engineering and/or testing
information and recommendations. The scope of services for this project does not include,
either specifically or by implication, any environmental assessment of the site or
identification of contaminated or hazardous materials or conditions. If the owner is
concerned about the potential for such contamination, other studies should be undertaken.
17
Geotechnical Engineering Exploration Terracon
Mr. R. Kint Glover
ELI Project No. 20955038
• placing effective control joints on relatively close centers
• allowing vertical movements in utility connections
• Underground Utility Systems: All piping should be adequately bedded for proper load
distribution. It is suggested that clean, graded gravel compacted to 80 percent of
Relative Density ASTM D4253 be used as bedding below the pipe. Where utilities
are.excavated below groundwater, temporary dewatering will be required during
excavation, pipe placement and backfilling operations for proper construction. Utility
trenches should be excavated on safe and stable slopes in accordance with OSHA
regulations as discussed above. Backfill should consist of the on -site soils. The pipe
backfill should be compacted to a minimum of 95 percent of Standard Proctor
Density ASTM D698.
• Corrosion Protection: Results of soluble sulfate testing indicate that ASTM Type 1-II
Portland cement is suitable for all concrete on and below grade. Foundation
concrete should be designed in accordance with the provisions of the ACI Design
Manual, Section 318, Chapter 4.
GENERAL COMMENTS
It is recommended that the Geotechnical Engineer be retained to provide a general review
of final design plans and specifications in order to confirm that grading and foundation
recommendations have been interpreted and implemented. In the event that any changes
I of the proposed project are planned, the conclusions and recommendations contained in this
report should be reviewed and the report modified or supplemented as necessary.
The Geotechnical Engineer should also be retained to provide services during excavation,
grading, foundation and construction phases of the work. Observation of footing
excavations should be performed prior to placement of reinforcing and concrete to confirm
] that satisfactory bearing materials are present and is considered a necessary part of
continuing geotechnical engineering services for the project. Construction testing, including
field and laboratory evaluation of fill, backf ill, pavement materials, concrete and steel should
be performed to determine whether applicable project requirements have been met. It
would be logical for Empire Laboratories, Inc. to provide these additional services for
continuing from design through construction and to determine the consistency of field
conditions with those data used in our analyses.
16
Geotechnical Engineering Exploration
Mr. R. Kint Glover
i' ELI Project No. 20955038
Drainage:
• Surface Drainage:
Terracon
1. Positive drainage should be provided during construction and maintained
throughout the life of the proposed construction. Infiltration of water into
utility or foundation excavations must be prevented during construction.
Planters and other surface features which could retain water in areas adjacent
to the building or pavements should be sealed or eliminated.
2. In areas where sidewalks or paving do not immediately adjoin the structure,
we recommend that protective slopes be provided with a minimum grade of
approximately 10 percent for at least 10 feet from perimeter walls. Backfill
against footings, exterior walls, and in utility and sprinkler line trenches
should be well compacted and free of all construction debris to reduce the
possibility of moisture infiltration.
3. Downspouts, roof drains or scuppers should discharge into splash blocks or
extensions when the ground surface beneath such features is not protected
by exterior slabs or paving.
4. Sprinkler systems should not be installed within 5 feet of foundation walls.
Landscaped irrigation adjacent to the foundation system should be minimized
or eliminated.
Additional Design and Construction Considerations:
• Exterior Slab Design and Construction: Exterior slabs -on -grade, exterior architectural
features, and utilities founded on, or in backfill may experience some movement due
to the volume change of the backfill. Potential movement could be reduced by:
• minimizing moisture increases in the backfill
�I • controlling moisture -density during placement of backfill
• using designs which allow vertical movement between the exterior
features and adjoining structural elements
15
�I'
I
Geotechnical Engineering Exploration
Mr. R. Kint Glover
`j ELI Project No. 20955038
Material
Terracon
Minimum Percent
(ASTM D698)
Subgrade soils beneath fill areas ..................... 95
On -site soils or approved imported fill:
Beneath foundations ......................... 98
Beneath slabs 95
Beneath pavements ......................... 95
Aggregate base (beneath pavement) ................... 95
Miscellaneous backfill ............................. 90
4. If a well defined maximum density curve cannot be generated by impact
compaction in the laboratory for any fill type, engineered fill should be
compacted to a minimum of 80 percent relative density by determined by
ASTM D4253 D4254.
5. Clay soils beneath pavement should be compacted within a moisture content
range of 2 percent below, to 2 percent above optimum. Clay soils placed
around or beneath the foundations should be compacted within a moisture
content range of optimum to 2 percent above optimum. Imported granular
soils should be compacted within a moisture range of 3 percent below to 3
percent above optimum.
Compliance: Performance of slabs -on -grade, foundations and pavement elements
i
supported on compacted fills or prepared subgrade depend upon compliance with
"Earthwork" recommendations. To assess compliance, observation and testing
should be performed under the direction of the geotechnical engineer.
• Excavation and Trench Construction: Excavations into the on -site soils may
encounter caving soils and groundwater, depending upon the final depth of
excavation. 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
Q: OSHA excavation and trench safety standards. If any excavation, including a utility
trench, is extended to a depth of more than 20 feet, it will be necessary to have the
side slopes designed by a professional engineer.
-1
14
Geotechnical Engineering Exploration Terracon
Mr. R. Kint Glover
ELI Project No. 20955038
Proof -rolling of the subgrade may be required to determine stability prior to
paving.
• Fill Materials:
1. Frozen soils should not be used as fill or backfill.
2. Imported soils should conform to the following or be approved. by the Project
Geotechnical Engineer:
Percent fines by weight
Gradation (ASTM C136)
6" ......................................... 100
3"....................................... 70-100
No. 4 Sieve .................................. 50-80
No. 200 Sieve .............................. 75 (max)
• Liquid Limit ........................... 40 (max)
• Plasticity Index ......................... 20 (max)
• Minimum R-value ............................ 5
3. Aggregate base should conform to Colorado Department of Transportation
Class 5 or 6 specifications.
• Placement and Compaction:
1. Place and compact fill in horizontal lifts, using equipment and procedures that
will produce recommended moisture contents and densities throughout the
lift.
2. No fill should be placed over frozen ground.
3. Materials should be compacted to the following:
13
Geotechnical Engineering Exploration
Mr. R. Kint Glover
ELI Project No. 20955038
Earthwork:
Terracon
Due to the shallow depth to groundwater, it is strongly suggested that the sewerline be
constructed across the site to provide overall site drainage prior to earthwork or
construction of the street or foundations. Consideration should also be given to initiating
earthwork during a time of year when groundwater is at a relatively low level.
• Site Clearing and Subgrade Preparation:
1. Strip and remove existing vegetation, and any other deleterious materials
from proposed building and pavement areas. All exposed surfaces should be
free of mounds and depressions which could prevent uniform compaction.
2. If unexpected fills or underground facilities are encountered during site
clearing, such features should be removed and the excavation thoroughly
cleaned prior to backfill placement and/or construction. All excavations
should be observed by the geotechnical engineer prior to backf ill placement.
3. Stripped materials consisting of vegetation and organic materials should be
wasted from the site, or used to revegetate exposed slopes after completion
of grading operations.
4. All exposed areas which will receive fill and/or floor slabs, once properly
cleared, should be scarified to a minimum depth of eight inches, conditioned
to near optimum moisture content, and compacted.
5. On -site clay soils may pump or become unstable or unworkable at high water
contents. Workability may be improved by scarifying and drying.
Lightweight excavation equipment may be required to reduce subgrade
pumping.
Use of lime, fly ash, kiln dust, cement or geotextiles could also be considered
as a stabilization technique. Laboratory evaluation is recommended to
determine the effect of chemical stabilization on subgrade soils prior to
construction.
12
�I
J;
a
Geotechnical Engineering Exploration Terracon
Mr. R. Kint Glover
ELI Project No. 20955038
The performance of all pavements can be enhanced by minimizing excess moisture which
can reach the subgrade soils. The following recommendations should be considered at
minimum:
• Site grading at a minimum 2% grade away from the pavements;
• Compaction of any utility trenches for landscaped areas to the same criteria
as the pavement subgrade;
• Sealing all landscaped areas in, or adjacent to pavements to minimize or
prevent moisture migration to subgrade soils;
• Placing compacted backfill against the exterior side of curb and gutter; and,
• Placing curb, gutter and/or sidewalk directly on subgrade soils without the
use of base course materials.
Preventative maintenance should be planned and provided for an on -going pavement
management program in order to enhance future pavement performance. Preventative
maintenance activities are intended to slow the rate of pavement deterioration, and to
preserve the pavement investment.
Preventative maintenance consists of both localized maintenance (e.g. crack sealing and
patching) and global maintenance (e.g. surface sealing). Preventative maintenance is
usually the first priority when implementing a planned pavement maintenance program and
provides the highest return on investment for pavements.
Recommended preventative maintenance policies for asphalt and jointed concrete
pavements, based upon type and severity of distress, are provided in Appendix D. Prior to
implementing any maintenance, additional engineering observation is recommended to
determine the type and extent of preventative maintenance.
11 '
Geotechnical Engineering Exploration
Mr. R. Kint Glover
ELI Project No. 20955038
Terracon
Where rigid pavements are used, the concrete should be obtained from an approved mix
design with the following minimum properties:
• Modulus of Rupture @ 28 days ................. 650 psi minimum
• Strength Requirements ASTM C94
• Minimum Cement Content ..................... 6.5 sacks/cu. yd.
• Cement Type ................................ Type I Portland
• Entrained Air Content .............................. 6 to 8%
• Concrete Aggregate ............ ASTM C33.and CDOT Section 703
• Aggregate Size 1 inch maximum
• Maximum Water Content 0.49 lb/lb of cement
• Maximum Allowable Slump .......................... 4 inches
Concrete should be deposited by truck mixers or agitators and placed a maximum of 90
minutes from time the water is added to the mix. Other specifications outlined by the
Colorado Department of Transportation should be followed.
Longitudinal and transverse joints should be provided as needed in concrete pavements for
expansion/contraction and isolation. The location and extent of joints should be based upon
the final pavement geometry and should be placed (in feet), at roughly twice the slab
thickness (in inches), on center in either direction. Sawed joints should be cut within 24-
hours of concrete placement, and should be a minimum of 25% of slab thickness plus 1/4
in All joints should be sealed to prevent entry of foreign material and dowelled where
necessary for load transfer. Where dowels cannot be used at joints accessible to wheel
loads, pavement thickness should be increased by 25 percent at the joints and tapered to
regular thickness in 5 feet.
Future performance of pavements constructed on clay soils will be dependent upon several
factors, including:
• maintaining stable moisture content of the subgrade soils; and,
• providing for a planned program of preventative maintenance.
Since clay soils have shrink/swell characteristics, pavements could crack in the future
primarily because of expansion of the soils when subjected to an increase in moisture
content to the subgrade. The cracking, while not desirable, does not necessarily constitute
structural failure of the pavement.
10
Geotechnical Engineering Exploration
Mr. R. Kint Glover
ELI Project No. 20955038
Terracon
Structural fill placed in the area of proposed pavement should have a minimum R-value of
5. Pavement materials should be placed at least 3 feet above groundwater.
Aggregate base course (if used on the site) should consist of a blend of sand and gravel
which meets strict specifications for quality and gradation. Use .of materials meeting
Colorado Department of Transportation Class 5 or 6 specifications is recommended for base
course.
In addition, the base course material should be moisture stable. Moisture stability is
determined by R-value testing which shows a maximum 12 point difference in R-values
between exudation pressures of 300 psi and 100 psi. Aggregate base course material
should be tested to determined compliance with these specifications prior to importation to
the site.
Aggregate base course and structural fill should be placed in lifts not exceeding six inches
and should be compacted to a minimum of 95% Standard Proctor Density (ASTM D698).
Asphalt concrete should be obtained from an approved mix design stating the Marshall or
Hveem properties, optimum asphalt content, job mix formula, and recommended mixing and
placing temperatures. Aggregate used in asphalt concrete 'should meet a particular
gradation. Use of materials meeting Colorado Department of Transportation Grading C or
CX specification is recommended. The mix design should be submitted prior to construction
to verify its adequacy. The asphalt materials should be placed in maximum 3-inch lifts, and
should be compacted to a minimum of 95% Marshall or Hveem density (ASTM D1559)
(ASTM D1560).
Plant -mixed bituminous base course should be composed of a mixture of aggregate, filler
and additives if required, and approved bituminous material. The bituminous base should
conform to an approved mix design stating the Marshall or Hveem properties, optimum
asphalt content, job mix formula, and recommended mixing and placing temperatures.
Aggregate used in plant -mixed bituminous base course should meet a particular gradation.
Use of aggregates meeting Colorado Department of Transportation Grading G or C
specifications is recommended. The mix design should be submitted prior to construction
to verify it adequacy. The asphalt material should be placed in maximum. 3-inch lifts, and
should be compacted to a minimum of 95%Marshall or Hveem density (ASTM D1559)
(ASTM D1560).
E
Geotechnical Engineering Exploration
Mr. R. Kint Glover
ELI Project No. 20955038
Terracon
moisture conditions. The AASHTO criteria suggests that these moisture conditions are
prevalent for approximately 12-1/2% of the annual moisture variation cycle.
Local drainage characteristics of the proposed pavement area is considered to be fair,
provided approximately 2 feet of structural fill is placed along the street alignment, as
planned. These drainage characteristics, coupled with the approximate duration of
saturated subgrade conditions, results in a design drainage coefficient of 0.9 when applying
the AASHTO criteria for design.
For flexible pavement design, a terminal serviceability index of 2.0 was utilized along with
an inherent reliability of 70%. Using the correlated design R-value of 5, environmental
criteria and other factors, the structural numbers (SN) of the pavement sections were
determined on the basis of the 1986 AASHTO design equation.
In addition to the flexible pavement design analyses, a rigid pavement design analysis was
completed, based upon AASHTO design procedures. Rigid pavement design is based on an
evaluation of the Modulus of Subgrade Reaction of the soils (K-value), the Modulus of
Rupture of the concrete, and other factors previously outlined. The design K-value of 100
for the subgrade soil was determined by correlation to the laboratory tests results. A
modulus of rupture of 650 psi (working stress 488 psi) was used for pavement concrete.
The rigid pavement thicknesses for each traffic category were determined on the basis of
the AASHTO design equation.
Recommended alternatives for flexible and rigid pavements, summarized for each traffic
area, are as follows:
J
J
J Each alternative should be investigated with respect to current material availability and
economic conditions.
8
Geotechnical Engineering Exploration Terracon
Mr. R. Kint Glover
ELI Project No. 20955038
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.
• Contraction joints should be provided in slabs to control the location and
extent of cracking. Maximum joint spacing of 15 to 20 feet in each direction
is recommended.
• Interior trench backfill paced beneath slabs should be compacted in
accordance with recommended specifications outlined below. _
• In areas subjected to normal loading, a minimum 4-inch layer of clean -graded
gravel should be placed beneath upper level interior slabs.
• A minimum 8-inch layer of free -draining gravel should be placed beneath
garden level floor slabs in conjunction with the underslab drainage system.
• If moisture sensitive floor coverings are used on interior slabs, consideration
should be given to the use of barriers to minimize potential vapor rise through
the slab.
• Floor slabs should not be constructed on frozen subgrade.
• Other design and construction considerations, as outlined in the ACI Design
Manual, Section 302.1 R are recommended.
Pavement Design and Construction: Design of pavements for the project have been based
on the procedures outlined in the 1986 Guideline for Design of Pavement Structures by the
American Association of State Highway and Transportation Officials (AASHTO).
An 18-kip equivalent daily load application (EDLA) of 5 was provided by the client for
pavement thickness designs. When actual traffic data becomes available, modification to
the pavement design may be required.
Based upon AASHTO criteria, Colorado is located within Climatic Region VI of the United
States. This region is characterized as being dry, with hard ground freeze and spring thaw.
The spring thaw condition typically results in saturated or near -saturated subgrade soil
7
Geotechnical Engineering Exploration Terracon
Mr. R. Kint Glover
ELI Project No. 20955038
Foundation excavations should be observed by the geotechnical engineer. If the soil
conditions encountered differ from those presented in this report, supplemental
recommendations may be required.
Garden -Level Construction: Groundwater was encountered seven days after the site
exploration at depths of 4 inches to 15 inches below existing grade. If the top of a garden
level slab is placed within 3 feet of the existing water level, the garden level should be
provided with a dewatering system. Consideration should be given to installing the
dewatering system prior to foundation construction. The dewatering system should as a
minimum include an underslab gravel drainage layer sloped to a perimeter drainage system.
The drainage system should be constructed around the exterior perimeter of the garden -level
foundation, and slope at a minimum 1 /8 inch per foot. The drainage system should empty
into a suitable outlet, such as a sump and pump system. If approved by the City of Fort
Collins, consideration may be given to emptying. the perimeter drains into a sewer
underdrain adequately sized to accept the anticipated flows.
J The drainage system should consist of a properly sized perforated pipe, embedded in free -
draining gravel, placed in a trench at least 12 inches wide. Gravel should extend a minimum
of 3-inches beneath the bottom of the pipe, and at least 1 foot above the bottom of the
foundation wall. The gravel should be covered_ with drainage fabric prior to placement of
foundation backfill.
The underslab drainage layer should consist of a minimum 8 inch thickness of free -draining
gravel meeting the specifications of ASTM C33, Size No. 57 or 67.
Floor Slab Design and Construction: Some differential movement of a slab -on -grade floor
l system is possible should the subgrade soils increase in moisture content. Such movements
d are considered within general tolerance for normal slab -on -grade construction. To reduce
any potential slab movements, the subgrade soils should be prepared as outlined in the
"Earthwork" section of this report.
For structural design of concrete slabs -on -grade, a modulus of subgrade reaction to 75
pounds per cubic inch (pci) may be used for floors supported on existing or engineered fill
consisting of on -site soils.
J
6
Geotechnical Engineering Exploration
Mr. R. Kint Glover
ELI Project No. 20955038
Terracon
Fluctuations in groundwater levels can best be determined by implementation of a
groundwater monitoring plan. Such a plan would include installation of groundwater
monitoring wells, and periodic measurement of groundwater levels over a sufficient period
of time.
The possibility of groundwater fluctuations should be considered when developing design
and construction plans for the project.
CONCLUSIONS AND RECOMMENDATIONS
Foundation Systems: Based on the soil conditions encountered on the site, spread footing
and/or grade beam foundations bearing upon undisturbed subsoils and/or engineered fill are
recommended for support for the proposed structures. The footings may be designed for
a maximum bearing pressure of 1500 psf., The design bearing pressure applies to dead
loads plus '/z design live load conditions. In addition, the footings should be sized to
maintain a minimum dead -load pressure of 500 psf.
Exterior footings should be placed a minimum of 30 inches below finished grade for frost
protection. Interior footings should bear a minimum of 12 inches below finished grade.
Finished grade is the lowest adjacent grade for perimeter footings and floor level for interior
footings.
Footings should be proportioned to minimize differential foundation movement.
Proportioning on the basis of equal total settlement is recommended; however,
proportioning to relative constant dead -load pressure will also reduce differential settlement
between adjacent footings. Total or differential settlement resulting from the assumed
structural loads are estimated to be on the order of 3/4 inch.
Site settlement due to the placement of four feet of fill around the garden levels is
estimated to be approximately 1 inch. This settlement is in addition to the estimated
settlement of 3/4 inch due to structural loads. Therefore, it is recommended that fill be
placed on the lots rie or to foundation construction to allow for some consolidation of the
subsoils from the added weight of the fill.
Foundations and masonry walls should be reinforced as necessary to reduce the potential
for distress caused by differential foundation movement. The use of joints at openings or
other discontinuities in masonry walls is recommended.
5
Geotechnical Engineering Exploration
Mr. R. Kint Glover
ELI Project No. 20955038
SUBSURFACE CONDITIONS
Terracon
Soil and Bedrock Conditions: The following describes the characteristics of the primary soil
strata in order of increasing depths:
• Topsoil: A '/2-foot layer of topsoil was encountered at the surface of the test
borings. The topsoil has been penetrated by root growth and organic matter.
• Lean Clay with Sand: A layer of dark brown clay was encountered below the topsoil
and extends to depths of 1 Yz to 2'/2 feet. This upper clay layer ismoist to wet and
contains moderate quantities of sand.
• Sandy Lean Clay: The lower clay stratum was encountered below the upper clay
layer and extends to depths of 6Y2 to 7 feet. This tan clay is wet and contains
substantial quantities of sand.
• Sand with Gravel: A 1-foot granular stratum was encountered below the clay layers
in Borings 3 and 4. The sand layer is wet and contains moderate quantities of
gravel.
• Claystone Bedrock: The bedrock stratum was encountered at depths of 6 Y2 to 7 Yz
feet and extends to the depths explored. The upper 2'/Z to 5Yz feet of bedrock
encountered is weathered.
Field and Laboratory Test Results: Field test results indicate the clay soils vary from
medium stiff to stiff in consistency. The granular soil is.medium dense. The weathered
bedrock is soft, and the underlying bedrock is moderately hard.
JLaboratory test results indicate the lean clay with sand at anticipated foundation bearing
depth has low to moderate bearing capacity and low expansive potential at its existing
water content.
Groundwater Conditions: Groundwater was encountered at approximate depths of 2 and
2Yz feet in Borings 3 and 4, respectively, at the time of the field exploration. When
checked 7 days after drilling, groundwater was measured at approximate depths of 4 inches
to 15 inches in all four borings. These observations represent only current groundwater
conditions, and may not be indicative of other times, or at other locations. Groundwater
levels can be expected to fluctuate with varying seasonal and weather conditions.
4
Geotechnical Engineering Exploration
Mr. R. Kint Glover
ELI Project No. 20955038
Terracon
Laboratory Testing: All samples retrieved during the field exploration were returned to the
laboratory for observation by the project geotechnical engineer, and were classified in
accordance with the Unified Soil Classification System described in Appendix C. Samples
of bedrock were classified in accordance with the general notes for Bedrock Classification.
At that time, the field descriptions were confirmed or modified as necessary and an
applicable laboratory testing program was formulated to determine engineering properties
of the subsurface materials. Boring logs were prepared and are presented in Appendix A.
Selected soil and bedrock samples were tested for the following engineering properties:
• Water content • Liquid Limit
• Dry density • Plasticity Index
• Consolidation • % Fines
• Compressive strength • R-Value
• Expansion • Water soluble sulfate content
The significance and purpose of each laboratory test is described in Appendix C. Laboratory
test results are presented on the boring logs and in Appendix B, and were used for the
geotechnical engineering analyses, and the development of foundation, pavement and
earthwork recommendations. All laboratory tests were performed in general accordance
with the applicable ASTM, local or other accepted standards.
SITE CONDITIONS
The site is a field vegetated with short, dense grass.. A shallow ditch runs along the west
and south edges of the property. Standing water and cattails were observed in the ditch.
Ponded water was also observed on the ground surface in the north portion of the site. The
property is bordered by Moore Elementary School to the northeast and east, the developing
Glenmoor P.U.D. to the northwest, undeveloped land to the west, and existing apartments,
residences and Glenmoor Drive to the south. The area slopes slightly to the east-southeast
and exhibits poor surface drainage.
3
Geotechnical Engineering Exploration
Terracon
Mr. R. Kint Glover
ELI Project No. 20955038
Other major site development will include the extension of Glenmoor Drive across the
middle of the site. Approximately 2 feet of fill will be placed in conjunction with the street
construction.
SITE EXPLORATION
The scope of the services performed for this project included site reconnaissance by an
engineering geologist, a subsurface exploration program, laboratory testing and engineering
analysis.
Field Exploration: A total of four test borings were drilled on March 7, 1995 to depths of
10 to 15 feet at the locations shown on the Site Plan, Figure 1. Three borings were drilled
in the area of proposed buildings, and one boring was drilled in the area of proposed
pavement. All borings were advanced with a truck -mounted drilling rig, utilizing 4-inch
diameter solid stem auger.
The borings were located in the field by pacing from the centerline of Glenmoor Drive at the
south property line. Elevations were taken at each boring location with an engineer's level
from a temporary bench mark (TBM) shown on the Site Plan. The accuracy of boring
locations and elevations should only be assumed to the level implied by the methods used.
Continuous lithologic logs of each boring were recorded by the engineering geologist during
the drilling operations. At selected intervals, samples of the subsurface materials were
taken by pushing thin -walled Shelby tubes, or driving split -spoon samplers. A
representative bulk sample of subsurface material was obtained from the pavement boring.
Penetration resistance measurements were obtained by driving the split -spoon into the
subsurface materials with a 140-pound hammer falling 30 inches. The penetration
resistance value is a useful index to the consistency, relative density or hardness of the
materials encountered.
Groundwater measurements were made in each boring at the time of the site exploration,
and seven days after drilling.
2
GEOTECHNICAL ENGINEERING REPORT
GLENMOOR DRIVE SUBDIVISION
FORT COLLINS, COLORADO
ELI Project No. 20955038
March 16, 1995
INTRODUCTION
Terracon
This report contains the results of our geotechnical engineering exploration for the proposed
subdivision to be located north of West Plum Street and Glenmoor Drive in southwest Fort
Collins, Colorado. The site is located in the Northwest 1 /4 of Section 15, Township 7
North, Range 69 West of the 6th Principal Meridian.
The purpose of these services is to provide information and geotechnical engineering
recommendations relative to:
• subsurface soil and bedrock conditions
• groundwater conditions
• foundation design and construction
• garden -level construction
• floor slab design and construction
• pavement design and construction
• earthwork
• drainage
The conclusions and recommendations contained in this report are based upon the results
of field and laboratory testing, engineering analysis, our experience with similar soil
conditions and structures and our understanding of the proposed project.
J
PROPOSED CONSTRUCTION
Based on information provided concerning construction, the proposed buildings will be
I duplex, triplex and/or four-plex residential units with garden -level construction. Wall and
column loads are expected to be less than 3 kips per lineal foot and 30 kips, respectively.
Although final site grading plans were not available prior to preparation of this report,
foundation levels are anticipated to be between '/z-foot below existing site grade to 2 feet
above existing site grade. In addition, approximately 4 feet of fill will be placed on the lots
to raise the grade for garden levels.
�,I
Geotechnical Engineering Exploration
Mr. R. Kint Glover
ELI Project No. 20955038
TABLE OF CONTENTS (Cont'd)
APPENDIX A
Figure No.
SitePlan ................................................. 1
Logs of Borings ..................................... Al thru A4
APPENDIX B
Consolidation Test ......................................... B1
R-Value................................................. B2
APPENDIX C: GENERAL NOTES
Drilling & Exploration ....................................... C1
Unified Soil Classification .................................... C2
Bedrock Classification, Sedimentary Bedrock ....................... C3
Laboratory Testing, Significance and Purpose ...................... C4
Report Terminology ........................................ C5
APPENDIX D
Recommended Preventative Maintenance -Asphalt Concrete Pavements .... D1
Recommended Preventative Maintenance -Jointed Concrete Pavements .... D2
Geotechnical Engineering Exploration
Mr. R. Kint Glover
ELI Project No. 20955038
TABLE OF CONTENTS
Page No.
Letter of Transmittal ...............................................
INTRODUCTION ................................................ 1
PROPOSED CONSTRUCTION ...................................... 1
J SITE EXPLORATION ............................................. 2
Field Exploration 2
Laboratory Testing ......................................... 3
JSITE CONDITIONS .............................................. 3
SUBSURFACE CONDITIONS ....................................... 4
Soil and Bedrock Conditions .................................. 4
Field and Laboratory Test Results ............................... 4
Groundwater Conditions ..................................... 4
CONCLUSIONS AND RECOMMENDATIONS ............................ 5
Foundation Systems ........................................ 5
Garden -Level Construction ................................... 6
Floor Slab Design and Construction ............................. 6
Pavement Design and Construction ............................. 7
Earthwork............................................... 12
Site Clearing and Subgrade Preparation ...................... 12
Fill Materials ........................................ 13
Placement and Compaction .............................. 13
Compliance......................................... 14
Excavation and Trench Construction ........................ 14
Drainage................................................ 15
Surface Drainage ..................................... 15
Additional Design and Construction Considerations .................. 15
Exterior Slab Design and Construction ...................... 15
Underground Utility Systems ............................. 16
Corrosion Protection ................................... 16
GENERAL COMMENTS ........................................... 16
Empire Laboratories, Inc.
A Division of The Terracon Companies, Inc.
P.O. Box 503.301 No. Howes
Fort Collins, Colorado 80522
(303)484-0359
Fax (303) 484-0454
Chester C. Smith, P.E.
Larry G. O'Dell, P.E.
Neil R. Sherrod, C.P.G.
March 16, 1995
Mr. R. Kint Glover
2101 Lindenmeier Road
Fort Collins, Colorado 80524
Re: Geotechnical Engineering Report, Glenmoor Drive Subdivision
Fort Collins, Colorado
ELI Project No. 20955038
Empire Laboratories, Inc. (ELI) has completed a geotechnical engineering exploration for the
proposed subdivision to be located north of Plum Street and east of Taft Hill Road in west
Fort Collins, Colorado. This study was performed in general accordance with our proposal
number D2095060 dated March 7, 1995.
The results of our engineering study, including the boring location diagram, laboratory test
results, test boring records, and the geotechnical recommendations needed to aid in the
design and construction of foundations, pavement and other earth connected phases of this
project are attached.
The subsurface soils consisted of lean clay with sand, sandy lean clay and sand with gravel
overlying claystone bedrock. The information obtained by the results of field exploration
and laboratory testing indicates the lean clay with sand has low expansive potential at its
in -situ water content. The clay soil at anticipated foundation bearing depth has low to
moderate load bearing capability.
Based on the geotechnical engineering analysis, subsurface exploration and laboratory test
results, we recommend the proposed residential buildings be supported on spread footing
and/or grade beam foundation systems.
Other design and construction details, based upon geotechnical conditions, are presented
in the report.
Offices of The Terracon companies, Inc. Geotechnical, Environmental and Materials Engineers
Arizona ■ Arkansas ■ Colorado ■ Idaho ■ Illinois ■ Iowa N Kansas ■ Minnesota
Missouri III Montana ■ Nebraska ■ Nevada ■ Oklahoma ■ Texas ■ Utah ■ Wyoming
011ALITV FNnINFFRIN(A SRINr:F 15IRS
GEOTECHNICAL ENGINEERING REPORT
GLENMOOR DRIVE SUBDIVISION
FORT COLLINS, COLORADO
ELI PROJECT NO. 20955038
March 16, 1995
Prepared for.•
MR. R. KINT GLOVER
2101 LINDENMEIER ROAD
FORT COLLINS, COLORADO 80524
Prepared by.
Empire Laboratories, Inc.
A Division of The Terracon Companies, Inc.
301 North Howes Street
Fort Collins, Colorado 80521
Empire Laboratories, Inc.
A Division of The Terracon Companies, Inc.
GEOTECHNICAL ENGINEERING REPORT
GLENMOOR DRIVE SUBDIVISION
FORT COLLINS, COLORADO
ELI PROJECT NO. 20955038
March 16, 1995
0RAto
� N
re,
A Division of
The Terracon Companies, Inc.