HomeMy WebLinkAboutMAPLE HILL PARK - BASIC DEVELOPMENT REVIEW - BDR170002 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORT400 North Link Lane | Fort Collins, Colorado 80524
Telephone: 970-206-9455 Fax: 970-206-9441
GEOTECHNICAL INVESTIGATION
MAPLE HILL PARK IMPROVEMENTS
SW MAPLE HILL DRIVE
AND BAR HARBOR DRIVE
FORT COLLINS, COLORADO
215 North Mason Street
Fort Collins, Colorado 80522
Attention: Matthew Day, RLA
Project No. FC07300-125
January 10, 2017
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTLT PROJECT NO. FC07300-125
TABLE OF CONTENTS
SCOPE 1
SUMMARY OF CONCLUSIONS 1
SITE CONDITIONS AND PROPOSED CONSTRUCTION 2
INVESTIGATION 3
SUBSURFACE CONDITIONS 3
GEOLOGIC HAZARDS 4
Expansive Soils 4
Seismicity 4
SITE DEVELOPMENT 4
Over-Excavation 4
Fill Placement 5
Excavations 6
FOUNDATIONS 6
Footings 6
BELOW GRADE WALLS AND SUBSURFACE DRAINS 7
FLOOR SYSTEMS AND SLABS-ON-GRADE 8
WATER-SOLUBLE SULFATES 10
SURFACE DRAINAGE 11
CONSTRUCTION OBSERVATIONS 11
GEOTECHNICAL RISK 11
LIMITATIONS 12
FIGURE 1 – LOCATIONS OF EXPLORATORY BORINGS
FIGURE 2 – SUMMARY LOGS OF EXPLORATORY BORINGS
APPENDIX A – RESULTS OF LABORATORY TESTING
APPENDIX B – SAMPLE SITE GRADING SPECIFICATIONS
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTLT PROJECT NO. FC07300-125
1
SCOPE
This report presents the results of our Geotechnical Investigation for the
proposed Maple Hill Neighborhood Park in Fort Collins, Colorado. The purpose of
the investigation was to evaluate the subsurface conditions and provide foundation
recommendations and geotechnical design criteria for the project. The scope was
described in our Service Agreement (Proposal No. FC-16-0100, dated March 1,
2016).
The report was prepared from data developed during field exploration,
laboratory testing, engineering analysis and experience with similar conditions.
The report includes a description of subsurface conditions found in our exploratory
borings and discussions of site development as influenced by geotechnical
considerations. Our opinions and recommendations regarding design criteria and
construction details for site development, foundations, slabs-on-grade, lateral
earth loads and drainage are provided. The report was prepared for the exclusive
use of the City of Fort Collins in design and construction of single-family residences
in the referenced subdivision. If the proposed construction changes, we should be
requested to review our recommendations. Our conclusions are summarized in
the following paragraphs.
SUMMARY OF CONCLUSIONS
1. Soils encountered in our borings consisted in general of sandy clay
and clayey sand. Claystone bedrock was encountered in one boring
at 8 feet to the depth explored. Groundwater was encountered in
five of the borings during drilling at depths of 14 to 18 feet and was
measured several days after drilling at depths of 8½ to 15 feet. We
recommend a minimum 3-foot separation from foundation
excavations to groundwater.
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTLT PROJECT NO. FC07300-125
2
2. The presence of expansive soils and bedrock constitutes a geologic
hazard. There is risk that slabs-on-grade and foundations will heave
or settle and be damaged. We believe the recommendations
presented in this report will help to control risk of damage; they will
not eliminate that risk. Slabs-on-grade and, in some instances,
foundations may be damaged.
3. Testing indicated higher swells in the upper clays. We recommend
footing foundations designed to maintain a minimum dead load
placed on 2 feet of over-excavated, properly compacted fill. Design
and construction criteria for foundations are presented in the report.
4. We judge the risk of poor slab-on-grade performance is moderate to
high for surficial slabs. We recommend placing slabs-on-grade on 2
feet of over-excavated, properly compacted fill. Some slab
movements should be anticipated. We expect movements will be
minor, on the order of 1 inch or less. If movement cannot be
tolerated, structural floors should be considered for the structures.
5. Surface drainage should be designed, constructed and maintained
to provide rapid removal of surface runoff away from the proposed
structures. Conservative irrigation practices should be followed to
avoid excessive wetting.
SITE CONDITIONS AND PROPOSED CONSTRUCTION
The site is located on the south side of Maple Hill Drive between Forecastle
Drive and Bar Harbor Drive in Fort Collins, Colorado (Figure 1). At the time of our
investigation the parcel was undeveloped. The ground surface slopes generally
downward to the south and west from the adjacent roadways. Ground cover
consisted of natural grasses and weeds. Based on conversations with our client,
we understand that a variety of improvements have been proposed that may
include restrooms, canopy shelters, concrete walkways, sport courts and a
detention pond.
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTLT PROJECT NO. FC07300-125
3
INVESTIGATION
The field investigation included drilling six exploratory borings at the
locations presented on Figure 1. The borings were drilled to depths of
approximately 10 to 30 feet using 4-inch diameter, continuous-flight augers and a
truck-mounted drill. Drilling was observed by our field representative who logged
the soils and bedrock encountered. Summary logs of the borings, including results
of field penetration resistance tests, are presented on Figure 2.
Soil and bedrock samples obtained during drilling were returned to our
laboratory and visually examined by our geotechnical engineer. Laboratory testing
was assigned and included moisture content, dry density, swell-consolidation,
particle-size analysis, Atterberg limits and water-soluble sulfate tests. Swell-
consolidation test samples were wetted at a confining pressure which
approximated the weight of overlying soils (overburden pressures). Results of the
laboratory tests are presented in Appendix A.
SUBSURFACE CONDITIONS
Soils encountered in our borings consisted in general of sandy clay and
clayey sand. Claystone bedrock was encountered in one boring at 8 feet to the
depth explored. The overburden soils classified as medium stiff to very stiff / loose
to medium dense based on field penetration test results. The competent claystone
bedrock classified as medium hard to hard. Swell-consolidation testing of seven
soil and bedrock samples indicated 0.0 to 7.3 percent swell; samples tested from
4 feet and below swelled a maximum of 1.2 percent.
Groundwater was encountered in five of the borings during drilling at depths
of 14 to 18 feet and was measured several days after drilling at depths of 8½ to 15
feet. We recommend a minimum 3-foot separation from foundation excavations to
groundwater. Further descriptions of the subsurface conditions are presented on
our boring logs and in our laboratory test results.
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTLT PROJECT NO. FC07300-125
4
GEOLOGIC HAZARDS
Expansive Soils
Expansive soils and bedrock are present at the site. The presence of
expansive soils and bedrock, collectively referred to as expansive or swelling soils,
constitutes a geologic hazard. There is a risk that ground heave will damage slabs-
on-grade and foundations. The risks associated with swelling soils can be
mitigated, but not eliminated, by careful design, construction, and maintenance
procedures. We believe the recommendations in this report will help control risk
of foundations and/or slab damage; they will not eliminate that risk.
Seismicity
This area, like most of central Colorado, is subject to a low degree of seismic
risk. As in most areas of recognized low seismicity, the record of the past
earthquake activity in Colorado is incomplete.
According to the 2012 International Building Code and the subsurface
conditions encountered in our borings, this site probably classifies as a Site Class
D. Only minor damage to relatively new, properly designed and built buildings
would be expected. Wind loads, not seismic considerations, typically govern
dynamic structural design in this area.
SITE DEVELOPMENT
Over-Excavation
Testing indicated higher swells in the upper clays. We recommend over-
excavation below footings and slabs-on-grade. The over-excavation should
consist of removal of the existing soils to a depth of 2 feet, moisture conditioning
and compaction of the soils as described in the Fill Placement section below.
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTLT PROJECT NO. FC07300-125
5
The over-excavation should extend a minimum 1-foot beyond the perimeter of the
improvements.
Fill Placement
The existing onsite soils are suitable for re-use as fill material provided
debris or deleterious organic materials are removed. If import material is used, it
should be tested and approved as acceptable fill by CTL|Thompson. In general,
import fill should meet or exceed the engineering qualities of the onsite soils. Areas
to receive fill should be scarified, moisture-conditioned and compacted to at least
95 percent of standard Proctor maximum dry density (ASTM D698, AASHTO T99).
Sand soils used as fill should be moistened to within 2 percent of optimum moisture
content. Clay soils should be moistened between optimum and 3 percent above
optimum moisture content. The fill should be moisture-conditioned, placed in thin,
loose lifts (8 inches or less) and compacted as described above. We should
observe placement and compaction of fill during construction. Fill placement and
compaction should not be conducted when the fill material is frozen.
Site grading in areas of landscaping where no future improvements are
planned can be placed at a dry density of at least 90 percent of standard Proctor
maximum dry density (ASTM D 698, AASHTO T 99). Example site grading
specifications are presented in Appendix B.
Water and sewer lines are often constructed beneath areas where
improvements are planned. Compaction of trench backfill can have a significant
effect on the life and serviceability overlying structures. We recommend trench
backfill be moisture conditioned and compacted as described in the Fill Placement
section of this report. Placement and compaction of fill and backfill should be
observed and tested by a representative of our firm during construction.
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTLT PROJECT NO. FC07300-125
6
Excavations
The materials found in our borings can be excavated using conventional
heavy-duty excavation equipment. Excavations should be sloped or shored to
meet local, State and Federal safety regulations. Excavation slopes specified by
OSHA are dependent upon types of soil and groundwater conditions encountered.
The contractor’s “competent person” should identify the soils and/or rock
encountered in the excavation and refer to OSHA standards to determine
appropriate slopes. Excavations deeper than 20 feet should be braced or a
professional engineer should design the slopes.
FOUNDATIONS
Testing indicated higher swells in the upper clays. We recommend footing
foundations designed to maintain a minimum dead load placed on 2 feet of over-
excavated, properly compacted fill as described in the SITE DEVELOPMENT
section of this report. Design criteria for footing foundations developed from
analysis of field and laboratory data and our experience are presented below.
Footings
1. Footings should be constructed on undisturbed natural soils or
properly compacted fill (see the Fill Placement section of this report).
All existing, uncontrolled fill should be removed from under footings
and within one footing width around footings and replaced with
properly compacted fill. Where soil is loosened during excavation, it
should be removed and replaced with on-site soils compacted
following the criteria in the Fill Placement section of this report.
2. Footings should be designed for a net allowable soil pressure of
2,000 psf and a minimum dead load pressure of 700 psf. The soil
pressure can be increased 33 percent for transient loads such as
wind or seismic loads. We recommend a minimum 3-foot separation
between foundation elements and groundwater.
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTLT PROJECT NO. FC07300-125
7
3. Footings should have a minimum width of at least 16 inches.
Foundations for isolated columns should have minimum dimensions
of 20 inches by 20 inches. Larger sizes may be required depending
on loads and the structural system used.
4. The soils beneath footing pads can be assigned an ultimate
coefficient of friction of 0.4 to resist lateral loads. The ability of grade
beam or footing backfill to resist lateral loads can be calculated using
a passive equivalent fluid pressure of 250 pcf. This assumes the
backfill is densely compacted and will not be removed. Backfill
should be placed and compacted to the criteria in the Fill Placement
section of this report.
5. To meet the minimum deadload criteria, a continuous void with
minimum 4-inch thickness should be placed below grade beams,
between pads to concentrate the load of the structures on the footing
pads.
6. Exterior footings should be protected from frost action. We believe
30 inches of frost cover is appropriate for this site.
7. Foundation walls and grade beams should be well reinforced both
top and bottom. We recommend the amount of steel equivalent to
that required for a simply supported span of 10 feet.
8. We should observe completed footing excavations to confirm that the
subsurface conditions are similar to those found in our borings.
BELOW GRADE WALLS
Some of the structures constructed may include below grade areas. Below
grade walls should be designed for lateral earth pressures where backfill is not
present to about the same extent on both sides of the wall. Many factors affect the
value of the design lateral earth pressure. These factors include, but are not limited
to, the type, compaction, slope and drainage of the backfill, and the rigidity of the
wall against rotation and deflection. For a very rigid wall where negligible or very
little deflection will occur, an "at-rest" lateral earth pressure should be used in
design. For walls that can deflect or rotate 0.5 to 1 percent of the wall height
(depending upon the backfill types), lower "active" lateral earth pressures are
appropriate. Our experience indicates walls can deflect or rotate slightly under
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTLT PROJECT NO. FC07300-125
8
normal design loads and that this deflection results in satisfactory wall
performance. Thus, the earth pressure on the walls will likely be between the
"active" and "at-rest" conditions.
If on-site soils are used as backfill and the backfill is not saturated, we
recommend design of below grade walls at this site using an equivalent fluid
density of at least 50 pounds per cubic foot (pcf). This value assumes deflection;
some minor cracking of walls may occur. If very little wall deflection is desired,
higher design density may be appropriate. The structural engineer should also
consider site-specific grade restrictions and the effects of large openings on the
behavior of the walls.
FLOOR SYSTEMS AND SLABS-ON-GRADE
Testing indicated higher swell potential in the upper couple feet of clay. We
recommend slabs-on-grade be constructed on 2 feet of over-excavated, properly
compacted fill as described in the SITE DEVELOPMENT section of this report.
It is impossible to construct slabs-on-grade with no risk of movement.
Based on our experience, we believe movements due to swell will be less than 1
inch. If movements for floor slabs cannot be tolerated, structural floors should be
used. Structural floors can be considered for specific areas that are particularly
sensitive to movement or where equipment on the floor is sensitive to movement.
Where structurally supported floors are selected, we recommend a
minimum void between the ground surface and the underside of the floor system
of 4 inches. The minimum void should be constructed below beams and utilities
that penetrate the floor. The floor may be cast over void form. Void form should
be chosen to break down quickly after the slab is placed. We recommend against
the use of wax or plastic-coated void boxes.
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTLT PROJECT NO. FC07300-125
9
Slabs may be subject to heavy point loads. The structural engineer should
design floor slab reinforcement. For design of slabs-on-grade, we recommend a
modulus of subgrade reaction of 75 pci for on-site soils.
If the owner elects to use slab-on-grade construction and accepts the risk
of movement and associated damage, we recommend the following precautions
for slab-on-grade construction at this site. These precautions can help reduce, but
not eliminate, damage or distress due to slab movement.
1. Slabs should be separated from exterior walls and interior bearing
members with a slip joint that allows free vertical movement of the
slabs. This can reduce cracking if some movement of the slab
occurs.
2. Slabs should be placed directly on exposed soils or properly moisture
conditioned, compacted fill. The 2012 International Building Code
(IBC) requires a vapor retarder be placed between the base course
or subgrade soils and the concrete slab-on-grade floor. The merits
of installation of a vapor retarder below floor slabs depend on the
sensitivity of floor coverings and building use to moisture. A properly
installed vapor retarder (minimum 6-mil; 10-mil recommended) is
more beneficial below concrete slab-on-grade floors where floor
coverings, painted floor surfaces or products stored on the floor will
be sensitive to moisture. The vapor retarder is most effective when
concrete is placed directly on top of it, rather than placing a sand or
gravel leveling course between the vapor retarder and the floor slab.
The placement of concrete on the vapor retarder may increase the
risk of shrinkage cracking and curling. Use of concrete with reduced
shrinkage characteristics including minimized water content,
maximized coarse aggregate content, and reasonably low slump will
reduce the risk of shrinkage cracking and curling. Considerations
and recommendations for the installation of vapor retarders below
concrete slabs are outlined in Section 3.2.3 of the 2006 report of
American Concrete Institute (ACI) Committee 302, “Guide for
Concrete Floor and Slab Construction (ACI 302.R1-04)”.
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTLT PROJECT NO. FC07300-125
10
3. If slab-bearing partitions are used, they should be designed and
constructed to allow for slab movement. At least a 3-inch void should
be maintained below or above the partitions. If the “float” is provided
at the top of partitions, the connection between interior, slab-
supported partitions and exterior, foundation supported walls should
be detailed to allow differential movement.
4. Underslab plumbing should be eliminated where feasible. Where
such plumbing is unavoidable it should be thoroughly pressure
tested for leaks prior to slab construction and be provided with
flexible couplings. Pressurized water supply lines should be brought
above the floors as quickly as possible.
5. Plumbing and utilities that pass through the slabs should be isolated
from the slabs and constructed with flexible couplings. Where water
and gas lines are connected to furnaces or heaters, the lines should
be constructed with sufficient flexibility to allow for movement.
6. The American Concrete Institute (ACI) recommends frequent control
joints be provided in slabs to reduce problems associated with
shrinkage cracking and curling. To reduce curling, the concrete mix
should have a high aggregate content and a low slump. If desired,
a shrinkage compensating admixture could be added to the concrete
to reduce the risk of shrinkage cracking. We can perform a mix
design or assist the design team in selecting a pre-existing mix.
WATER-SOLUBLE SULFATES
Concrete that comes into contact with soils can be subject to sulfate attack.
We measured water-soluble sulfate concentrations in three samples from this site.
Concentrations were measured from 0.01 to 0.13 percent. Water-soluble sulfate
concentrations between 0.1 and 0.2 percent indicate Class 1 exposure to sulfate
attack, according to the American Concrete Institute (ACI). ACI indicates adequate
sulfate resistance can be achieved by using Type II cement with a water-to-
cementitious material ratio of 0.50 or less. ACI also indicates concrete in Class 1
exposure environments should have a minimum compressive strength of 4,000
psi.
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTLT PROJECT NO. FC07300-125
11
Superficial damage may occur to the exposed surfaces of highly permeable
concrete. To control this risk and to resist freeze-thaw deterioration, the water-to-
cementitious materials ratio should not exceed 0.50 for concrete in contact with
soils that are likely to stay moist due to surface drainage or high water tables.
Concrete should have a total air content of 6 percent ± 1.5 percent. We advocate
all foundation walls and grade beams in contact with the soils (including the inside
and outside faces of garage and crawl space grade beams) be damp-proofed.
SURFACE DRAINAGE
Performance of foundations, flatwork and pavements are influenced by
changes in subgrade moisture conditions. Carefully planned and maintained
surface grading can reduce the risk of wetting of the foundation soils and pavement
subgrade. Positive drainage should be provided away from foundations. Backfill
around foundations should be moisture treated and compacted as described in Fill
Placement. Roof drains should be directed away from buildings. Downspout
extensions and splash blocks should be provided at discharge points.
CONSTRUCTION OBSERVATIONS
We recommend that CTL | Thompson, Inc. provide construction observation
services to allow us the opportunity to verify whether soil conditions are consistent
with those found during this investigation. Other observations are recommended
to review general conformance with design plans. If others perform these
observations, they must accept responsibility to judge whether the
recommendations in this report remain appropriate.
GEOTECHNICAL RISK
The concept of risk is an important aspect with any geotechnical evaluation
primarily because the methods used to develop geotechnical recommendations do
not comprise an exact science. We never have complete knowledge of subsurface
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTLT PROJECT NO. FC07300-125
12
conditions. Our analysis must be tempered with engineering judgment and
experience. Therefore, the recommendations presented in any geotechnical
evaluation should not be considered risk-free. Our recommendations represent our
judgment of those measures that are necessary to increase the chances that the
structures will perform satisfactorily. It is critical that all recommendations in this
report are followed during construction. Owners must assume responsibility for
maintaining the structures and use appropriate practices regarding drainage and
landscaping. Improvements performed by owners after construction, such as
construction of additions, retaining walls, landscaping and exterior flatwork, should
be completed in accordance with recommendations in this report.
LIMITATIONS
This report has been prepared for the exclusive use of the City of Fort
Collins for the purpose of providing geotechnical design and construction criteria
for the proposed project. The information, conclusions, and recommendations
presented herein are based upon consideration of many factors including, but not
limited to, the type of construction proposed, the geologic setting, and the
subsurface conditions encountered. The conclusions and recommendations
contained in the report are not valid for use by others. Standards of practice evolve
in the area of geotechnical engineering. The recommendations provided are
appropriate for about three years. If the proposed construction is not constructed
within about three years, we should be contacted to determine if we should update
this report.
Six borings were drilled during this investigation to obtain a reasonably
accurate picture of the subsurface conditions. Variations in the subsurface
conditions not indicated by our borings are possible. A representative of our firm
should observe foundation excavations to confirm the exposed materials are as
anticipated from our borings. We should also test compaction of fill if over-
excavation is used.
TH-1
TH-2
TH-3
TH-4
TH-5
TH-6
TBM
MAPLE HILL DR.
GIDDINGS RD.
SITE
COUNTRY CLUB DR.
RICHARDS LAKE RD.
TIMBERLINE
TURNBERRY RD.
LEGEND:
INDICATES APPROXIMATE
LOCATION OF EXPLORATORY
TEST HOLE
INDICATES APPROXIMATE
LOCATION OF TEMPORARY
BENCHMARK; WATER TAP
(ASSUMED ELEVATION 100')
TH-1
TBM
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTL I T PROJECT NO. FC07300-125
FIGURE 1
Locations of
Exploratory
Borings
VICINITY MAP
(FORT COLLINS, COLORADO)
NOT TO SCALE
100'
APPROXIMATE
SCALE: 1" = 100'
65
70
75
80
85
90
95
100
105
110
65
70
75
80
85
90
95
100
105
110
22/12
12/12
11/12
7/12
WC=8.0
DD=120
SW=7.3
SS=0.010
WC=11.4
LL=24 PI=8
-200=34
WC=8.0
DD=120
SW=7.3
SS=0.010
WC=11.4
LL=24 PI=8
-200=34
TH-1
El. 106.0
10/12
9/12
12/12
14/12
5/12
WC=15.0
DD=114
SW=0.4
WC=19.9
DD=108
-200=52
WC=15.0
DD=114
SW=0.4
WC=19.9
DD=108
-200=52
TH-2
El. 101.0
24/12
APPENDIX A
RESULTS OF LABORATORY TESTING
Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 120 PCF
From TH - 1 AT 2 FEET MOISTURE CONTENT= 8.0 %
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTL | T PROJECT NO. FC07300-125
APPLIED PRESSURE - KSF
COMPRESSION % EXPANSION
Swell Consolidation
Test Results
FIGURE A-1
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
8
9
10
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 114 PCF
From TH - 2 AT 4 FEET MOISTURE CONTENT= 15.0 %
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTL | T PROJECT NO. FC07300-125
APPLIED PRESSURE - KSF
COMPRESSION % EXPANSION
Swell Consolidation
Test Results
FIGURE A-2
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 126 PCF
From TH - 3 AT 2 FEET MOISTURE CONTENT= 9.2 %
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTL | T PROJECT NO. FC07300-125
APPLIED PRESSURE - KSF
COMPRESSION % EXPANSION
Swell Consolidation
Test Results
FIGURE A-3
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
7
8
9
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 119 PCF
From TH - 3 AT 9 FEET MOISTURE CONTENT= 14.5 %
Sample of CLAYSTONE, WEATHERED DRY UNIT WEIGHT= 108 PCF
From TH - 4 AT 9 FEET MOISTURE CONTENT= 20.3 %
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTL | T PROJECT NO. FC07300-125
APPLIED PRESSURE - KSF
APPLIED PRESSURE - KSF
COMPRESSION % EXPANSION
Swell Consolidation
FIGURE A-4
COMPRESSION % EXPANSION
-4
-3
-2
-1
0
1
2
3
NO MOVEMENT DUE TO WETTING
-4
-3
-2
-1
0
1
2
3
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
0.1 1.0 10 100
Sample of CLAYSTONE, WEATHERED DRY UNIT WEIGHT= 113 PCF
From TH - 4 AT 14 FEET MOISTURE CONTENT= 18.3 %
Sample of CLAY, SANDY (CL) DRY UNIT WEIGHT= 113 PCF
From TH - 5 AT 9 FEET MOISTURE CONTENT= 17.4 %
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTL | T PROJECT NO. FC07300-125
APPLIED PRESSURE - KSF
APPLIED PRESSURE - KSF
COMPRESSION % EXPANSION
Swell Consolidation
FIGURE A-5
COMPRESSION % EXPANSION
-4
-3
-2
-1
0
1
2
3
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
-4
-3
-2
-1
0
1
2
3
EXPANSION UNDER CONSTANT
PRESSURE DUE TO WETTING
0.1 1.0 10 100
0.1 1.0 10 100
PASSING WATER-
MOISTURE DRY LIQUID PLASTICITY APPLIED SWELL NO. 200 SOLUBLE
DEPTH CONTENT DENSITY LIMIT INDEX SWELL* PRESSURE PRESSURE SIEVE SULFATES
BORING (FEET) (%) (PCF) (%) (PSF) (PSF) (%) (%) DESCRIPTION
TH-1 2 8.0 120 7.3 200 12,000 0.01 CLAY, SANDY (CL)
TH-1 9 11.4 24 8 34 SAND, CLAYEY (SC)
TH-2 4 15.0 114 0.4 500 CLAY, SANDY (CL)
TH-2 14 19.9 108 52 CLAY, SANDY (CL)
TH-3 2 9.2 126 6.5 200 11,000 0.02 CLAY, SANDY (CL)
TH-3 9 14.5 119 0.0 1,100 CLAY, SANDY (CL)
TH-4 9 20.3 108 1.2 1,100 CLAYSTONE, WEATHERED
TH-4 14 18.3 113 0.8 1,800 CLAYSTONE, WEATHERED
TH-5 2 9.7 76 CLAY, SANDY (CL)
TH-5 9 13.9 113 0.2 1,100 0.13 CLAY, SANDY (CL)
SWELL TEST RESULTS*
TABLE A-I
SUMMARY OF LABORATORY TESTING
ATTERBERG LIMITS
Page 1 of 1
* NEGATIVE VALUE INDICATES COMPRESSION.
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTL|T PROJECT NO. FC07300-125
APPENDIX B
SAMPLE SITE GRADING SPECIFICATIONS
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTLT PROJECT NO. FC07300-125
B-1
SAMPLE SITE GRADING SPECIFICATIONS
1. DESCRIPTION
This item shall consist of the excavation, transportation, placement and
compaction of materials from locations indicated on the plans, or staked by the
Engineer, as necessary to achieve building site elevations.
2. GENERAL
The Geotechnical Engineer shall be the Owner's representative. The
Geotechnical Engineer shall approve fill materials, method of placement, moisture
contents and percent compaction, and shall give written approval of the completed
fill.
3. CLEARING JOB SITE
The Contractor shall remove all trees, brush and rubbish before excavation or fill
placement is begun. The Contractor shall dispose of the cleared material to
provide the Owner with a clean, neat appearing job site. Cleared material shall not
be placed in areas to receive fill or where the material will support structures of any
kind.
4. SCARIFYING AREA TO BE FILLED
All topsoil and vegetable matter shall be removed from the ground surface upon
which fill is to be placed. The surface shall then be plowed or scarified to a depth
of 8 inches until the surface is free from ruts, hummocks or other uneven features,
which would prevent uniform compaction by the equipment to be used.
5. COMPACTING AREA TO BE FILLED
After the foundation for the fill has been cleared and scarified, it shall be disked or
bladed until it is free from large clods, brought to the proper moisture content and
compacted to not less than 95 percent of maximum dry density as determined in
accordance with ASTM D 698 or AASHTO T 99.
6. FILL MATERIALS
On-site materials classifying as CL, SC, SM, SW, SP, GP, GC and GM are
acceptable. Fill soils shall be free from organic matter, debris, or other deleterious
substances, and shall not contain rocks or lumps having a diameter greater than
three (3) inches. Fill materials shall be obtained from the existing fill and other
approved sources.
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTLT PROJECT NO. FC07300-125
B-2
7. MOISTURE CONTENT
Fill materials shall be moisture treated. Clay soils placed below the building
envelope should be moisture-treated to between optimum and 3 percent above
optimum moisture content as determined from Standard Proctor compaction tests.
Clay soil placed exterior to the building should be moisture treated between
optimum and 3 percent above optimum moisture content. Sand soils can be
moistened to within 2 percent of optimum moisture content. Sufficient laboratory
compaction tests shall be performed to determine the optimum moisture content
for the various soils encountered in borrow areas.
The Contractor may be required to add moisture to the excavation materials in the
borrow area if, in the opinion of the Geotechnical Engineer, it is not possible to
obtain uniform moisture content by adding water on the fill surface. The Contractor
may be required to rake or disk the fill soils to provide uniform moisture content
through the soils.
The application of water to embankment materials shall be made with any type of
watering equipment approved by the Geotechnical Engineer, which will give the
desired results. Water jets from the spreader shall not be directed at the
embankment with such force that fill materials are washed out.
Should too much water be added to any part of the fill, such that the material is too
wet to permit the desired compaction from being obtained, rolling and all work on
that section of the fill shall be delayed until the material has been allowed to dry to
the required moisture content. The Contractor will be permitted to rework wet
material in an approved manner to hasten its drying.
8. COMPACTION OF FILL AREAS
Selected fill material shall be placed and mixed in evenly spread layers. After each
fill layer has been placed, it shall be uniformly compacted to not less than the
specified percentage of maximum dry density. Fill materials shall be placed such
that the thickness of loose material does not exceed 8 inches and the compacted
lift thickness does not exceed 6 inches.
Compaction, as specified above, shall be obtained by the use of sheepsfoot rollers,
multiple-wheel pneumatic-tired rollers, or other equipment approved by the
Engineer. Compaction shall be accomplished while the fill material is at the
specified moisture content. Compaction of each layer shall be continuous over the
entire area. Compaction equipment shall make sufficient trips to insure that the
required dry density is obtained.
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTLT PROJECT NO. FC07300-125
B-3
9. COMPACTION OF SLOPES
Fill slopes shall be compacted by means of sheepsfoot rollers or other suitable
equipment. Compaction operations shall be continued until slopes are stable, but
not too dense for planting, and there is no appreciable amount of loose soil on the
slopes. Compaction of slopes may be done progressively in increments of three
to five feet (3' to 5') in height or after the fill is brought to its total height. Permanent
fill slopes shall not exceed 3:1 (horizontal to vertical).
10. DENSITY TESTS
Field density tests shall be made by the Geotechnical Engineer at locations and
depths of his choosing. Where sheepsfoot rollers are used, the soil may be
disturbed to a depth of several inches. Density tests shall be taken in compacted
material below the disturbed surface. When density tests indicate that the dry
density or moisture content of any layer of fill or portion thereof is below that
required, the particular layer or portion shall be reworked until the required dry
density or moisture content has been achieved.
11. COMPLETED PRELIMINARY GRADES
All areas, both cut and fill, shall be finished to a level surface and shall meet the
following limits of construction:
A. Overlot cut or fill areas shall be within plus or minus 2/10 of one foot.
B. Street grading shall be within plus or minus 1/10 of one foot.
The civil engineer, or duly authorized representative, shall check all cut and fill
areas to observe that the work is in accordance with the above limits.
12. SUPERVISION AND CONSTRUCTION STAKING
Observation by the Geotechnical Engineer shall be continuous during the
placement of fill and compaction operations so that he can declare that the fill was
placed in general conformance with specifications. All site visits necessary to test
the placement of fill and observe compaction operations will be at the expense of
the Owner. All construction staking will be provided by the Civil Engineer or his
duly authorized representative. Initial and final grading staking shall be at the
expense of the owner. The replacement of grade stakes through construction shall
be at the expense of the contractor.
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTLT PROJECT NO. FC07300-125
B-4
13. SEASONAL LIMITS
No fill material shall be placed, spread or rolled while it is frozen, thawing, or during
unfavorable weather conditions. When work is interrupted by heavy precipitation,
fill operations shall not be resumed until the Geotechnical Engineer indicates that
the moisture content and dry density of previously placed materials are as
specified.
14. NOTICE REGARDING START OF GRADING
The contractor shall submit notification to the Geotechnical Engineer and Owner
advising them of the start of grading operations at least three (3) days in advance
of the starting date. Notification shall also be submitted at least 3 days in advance
of any resumption dates when grading operations have been stopped for any
reason other than adverse weather conditions.
15. REPORTING OF FIELD DENSITY TESTS
Density tests performed by the Geotechnical Engineer, as specified under "Density
Tests" above, shall be submitted progressively to the Owner. Dry density, moisture
content and percent compaction shall be reported for each test taken.
16. DECLARATION REGARDING COMPLETED FILL
The Geotechnical Engineer shall provide a written declaration stating that the site
was filled with acceptable materials, or was placed in general accordance with the
specifications.
7/12
12/12
22/12
4/12
13/12
WC=9.2
DD=126
SW=6.5
SS=0.020
WC=14.5
DD=119
SW=0.0
WC=9.2
DD=126
SW=6.5
SS=0.020
WC=14.5
DD=119
SW=0.0
TH-3
El. 101.0
7/12
13/12
28/12
50/12
42/12
WC=20.3
DD=108
SW=1.2
WC=18.3
DD=113
SW=0.8
WC=20.3
DD=108
SW=1.2
WC=18.3
DD=113
SW=0.8
TH-4
El. 108.5
11/12
8/12
4/12
10/12
WC=9.7
-200=76
WC=13.9
DD=113
SW=0.2
SS=0.130
WC=9.7
-200=76
WC=13.9
DD=113
SW=0.2
SS=0.130
TH-5
El. 98.0
21/12
16/12
8/12
9/12
7/12
TH-6
El. 99.5
ELEVATION - FEET
FIGURE 2
DRIVE SAMPLE. THE SYMBOL 22/12 INDICATES 22 BLOWS OF A 140-POUND HAMMER
FALLING 30 INCHES WERE REQUIRED TO DRIVE A 2.5-INCH O.D. SAMPLER 12 INCHES.
ELEVATION - FEET
WATER LEVEL MEASURED SEVERAL DAYS AFTER DRILLING.
SAND, CLEAN TO CLAYEY, WITH OCASSIONAL SANDY CLAY LAYERS, MOIST TO WET,
LOOSE TO MEDIUM DENSE, BROWN (SC, SP, CL)
2.
3.
CLAY, SANDY, WITH OCASSIONAL CLAYEY SAND LAYERS, MOIST TO WET, MEDIUM STIFF
TO VERY STIFF, BROWN, GRAY, TAN (CL, SC)
THE BORINGS WERE DRILLED ON DECEMBER 16, 2016 USING 4-INCH DIAMETER
CONTINUOUS-FLIGHT AUGERS AND A TRUCK-MOUNTED DRILL RIG.
1.
LEGEND:
NOTES:
WEATHERED CLAYSTONE, SANDY, MOIST, MEDIUM HARD, BROWN, GRAY, RUST
CLAYSTONE, SANDY, MOIST, MEDIUM HARD TO HARD, BROWN, GRAY, RUST
WATER LEVEL MEASURED AT TIME OF DRILLING.
BORING ELEVATIONS WERE SURVEYED BY A REPRESENTATIVE OF OUR FIRM
REFERENCING THE TEMPORARY BENCHMARK SHOWN ON FIGURE 1.
THESE LOGS ARE SUBJECT TO THE EXPLANATIONS, LIMITATIONS AND CONCLUSIONS IN
THIS REPORT.
4.
Summary Logs of
Exploratory Borings
WC
DD
SW
-200
LL
PI
UC
SS
-
-
-
-
-
-
-
-
INDICATES MOISTURE CONTENT (%).
INDICATES DRY DENSITY (PCF).
INDICATES SWELL WHEN WETTED UNDER OVERBURDEN PRESSURE (%).
INDICATES PASSING NO. 200 SIEVE (%).
INDICATES LIQUID LIMIT.
INDICATES PLASTICITY INDEX.
INDICATES UNCONFINED COMPRESSIVE STRENGTH (PSF).
INDICATES SOLUBLE SULFATE CONTENT (%).
CITY OF FORT COLLINS
MAPLE HILL NEIGHBORHOOD PARK
CTL | T PROJECT NO. FC07300-125