HomeMy WebLinkAboutHARMONY MARKET PUD - Filed GR-GEOTECHNICAL REPORT/SOILS REPORT - (2)REPORT
OF A
GEOTECHNICAL INVESTIGATION
FOR
PACE MEMBERSHIP WAREHOUSE
FORT COLLINS, COLORADO
PACE MEMBERSHIP WAREHOUSE
AURORA, COLORADO
PROJECT NO. 7882-89
EMPIRE LABORATORIES, INC.
301 NORTH HOWES STREET
FORT COLLINS, COLORADO 80521
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TABLE OF CONTENTS
Tableof Contents ..............................................
Letterof Transmittal ..........................................
Report.........................................................
AppendixA ....................................................
Test Boring Location Plan and Geologic Map ..................
Keyto Borings ...............................................
Logof Borings ...............................................
Appendix B....................................................
Consolidation Test Data ......................................
Hveem Stabilometer Data .....................................
Summaryof Test Results .....................................
AppendixC....................................................
AppendixD....................................................
SoilsMap ...................................................
SoilsDescriptions ..........................................
Empire Laboratories, Inc.
GEOTECHNICAL ENGINEERING & MATERIALS TESTING
13, 1989
Pace Membership Warehouse
3315 Peoria Street
Aurora, Colorado 80010
Attention: Mr. Peter Insana, P.E.
Gentlemen:
CORPORATE OFFICE
P.O. Box 503 • (303) 484-0359
301 No. Howes • Fort Collins, Colorado 80522
We are pleased to submit our Report of a Geotechnical Investigation
prepared for the proposed Pace Membership Warehouse facility located
south of Harmony Road on Boardwalk Drive in south Fort Collins,
Colorado.
Based upon our findings in the subsurface, it is our opinion the site is
suitable for the proposed construction, providing the design criteria and
recommendations set forth in this report are met. The accompanying
report presents our findings in the subsurface and our recommendations
based upon these findings.
Very truly yours,
EMPIRE LABOR DRIES, INC.
f CC \^" "
Neil R. errod " '
Senior Engineering Geologist
Reviewed by:
Chester C. Smith, P.E.
President
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cc: Vaught Frye Architects - Mr. FFWRRI""Vaught
RBD, Inc. - Mr. Lloyd McLaughlin
City of Fort Collins - Mr. Mike Hertzig (2)
Branch Offices
P.O. Box 16859 P.O. Box 1135 P.O. Box 1744
Colorado Springs, CO 80935 Longmont, CO 80502 Greeley, CO 80632
719) 597-2116 (303) 776-3921 (303) 351-0460
Member of Consulting Engineers Council
P.O. Box 5659
Cheyenne, WY 82003
307) 632-9224
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REPORT
OF A
GEOTECHNICAL INVESTIGATION
SCOPE
This report presents the results of a geotechnical evaluation
prepared for the proposed Pace Warehouse facility located south of
Harmony Road on Boardwalk Drive in south Fort Collins, Colorado. The
investigation included test borings and laboratory testing of samples
obtained from these borings.
The objectives of this study were to (1) determine the geologic
characteristics at the site, 2) prepare an environmental assessment of
the property, (3) evaluate the subsurface conditions at the site relative
to the proposed construction, 4) make recommendations regarding the
design of the substructures, (5) recommend certain precautions which
should be taken because of adverse soil and/or ground water conditions,
and (6) make recommendations regarding pavement types and thicknesses
for the proposed driveways, parking areas and streets to be constructed
at the site.
SITE EXPLORATION
The field exploration, carried out on March 2, 3 and 6, 1989,
consisted of drilling, logging, and sampling nineteen (19) test borings.
The test borings were located by Empire Laboratories, Inc. from existing
property lines and streets using conventional chaining methods. The
locations of the test borings are shown on the Test Boring Location Plan
and Geologic Map included in Appendix A of this report. Boring logs
prepared from the field logs are shown in Appendix A. These logs show
soils encountered, location of sampling, and ground water at the time of
the exploration.
The borings were advanced with a four -inch diameter, continuous -
type, power -flight auger drill. During the drilling operations, a
geotechnical engineer from Empire Laboratories, Inc. was present and
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made continuous observations of the soils encountered. A visual
inspection of the site was made by an engineering geologist of Empire
Laboratories, Inc. on March 6, 1989. At the time of the investigation,
concentrations of benzene gas were measured at each test boring with an
HNU Model PI-101 trace gas analyzer.
SITE LOCATION AND DESCRIPTION
The proposed site is located at the northeast corner of Boardwalk
and OakRidge Drives in south Fort Collins, Colorado. More particularly,
the site is described as a tract of land situate in the Northeast 1 /4 of
Section 1, Township 6 North, Range 69 West of the Sixth P.M., City of
Fort Collins, Larimer County, Colorado.
The site of currently consists vacant farm land. The property is
relatively flat and exhibits minor drainage to the east toward Lemay
Avenue. An irrigation ditch runs in an east -west direction through the
southern portion of the site. A farm including an abandoned farmhouse
and a shed is located northeast of the property. The shed is currently
being used as a construction office and storage area. The majority of
the land is plowed and is sparsely vegetated with corn stubble and
weeds. The site is bordered on the north by Harmony Road, on the
east, south and west by cultivated farm land.
LABORATORY TESTS AND EVALUATION
Samples obtained from the test borings were subjected to testing in
the laboratory to provide a sound basis for evaluating the physical
properties of the soils encountered. Moisture contents, dry unit
weights, unconfined compressive strengths, water soluble sulfates,
resistivity, sulfide, oxidation-reduction potential, pH, swelling
potentials, and the Atterberg limits were determined. A summary of the
test results is included in Appendix B. Consolidation,
swell -consolidation and Hveem stabilometer characteristics were also
determined, and curves showing this data are included in Appendix B.
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SOIL AND GROUND WATER CONDITIONS
The soil profile at the site consists of strata of materials arranged
in different combinations. In order of increasing depths, they are as
follows:
1) Silty Topsoil and Fill Material: The majority of the site is
overlain by a six (6) inch layer of cultivated topsoil. The
topsoil has been penetrated by root growth and organic matter
and should not be used as a bearing soil or as a fill and/or
backfill material. It is recommended that the topsoil be
forstrippedandstockpiled reuse in planted areas. A two (2)
foot layer of fill material was encountered at the surface of
Boring 8, drilled through the bank of the irrigation ditch
located in the southern portion of the site. The fill consists of
a mixture of silty clay and sandy silty clay. It is not known
whether the fill has been uniformly or properly compacted;
therefore, it should not be used as a bearing soil or as a fill
and/or backfill material.
2) Silty Clay: A layer of brown to tan silty clay underlies the
topsoil and/or fill and extends to depths one and one-half
1-1 /2) to eleven and one-half (11-1 /2) feet below the surface.
The silty clay contains minor to varying amounts of sand, is
damp to moist in situ and exhibits generally moderate bearing
characteristics. When wetted, the clay stratum exhibits slight
swell potential; and upon loading, consolidation occurs.
3) Sandy and/or Gravelly Silty Clay: This stratum underlies the
upper clay and extends to depth seven and one-half (7-1 /2) to
twenty-six (26) feet below the surface. The tan to red silty
clay contains varying amounts of sand and/or gravel and lenses
of sand and gravel, is plastic and exhibits generally moderate
bearing characteristics in its moist to saturated in situ
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condition. When wetted and upon loading, consolidation of the
clay stratum occurs.
4) Silty and/or Clayey Sand and Gravel: The sand and gravel
stratum was encountered in Borings 4, 6, 16 and 18 at depths
of seven and one-half (7-1 /2) to sixteen and one -Ralf (16-1/2)
feet and extends to the bedrock below and/or the depths
explored. The sand and gravel is poorly graded, contains
varying amounts of silt and/or clay and exhibits moderate
bearing characteristics in its medium dense damp to saturated
condition.
5) Siltstone Bedrock: The bedrock was encountered in Borings 1
through 9 at depths of nineteen (19) to twenty-seven (27) feet
below the surface and extends to greater depths. The upper
two (2) feet of the Siltstone is highly weathered; however, the
underlying bedrock is firm and exhibits very high bearing
characteristics. The siltstone, interbedded with minor amounts
of sandstone, exhibits high swell potential when wetted.
6) Ground Water: Twenty-four hours after drilling, free ground
water was encountered in Borings 1 through 12, 14, 18 and 19
at depths of eight and one-half (8-1 /2) to thirteen and one-half
13-1 /2) feet below the surface. No free ground water was
encountered in Borings 13, 15, 16 and 17 to the depths
explored. Water levels in this area are subject to change due
to seasonal variations and irrigation demands on and/or adjacent
to the site. Based on the ground water elevations at the site,
the hydraulic gradient in this area is to the southeast.
GEOLOGY
The proposed site is located within the Colorado Piedmont section
of the Great Plains physiographic province. The Colorado Piedmont,
formed during Late Tertiary and Early Quaternary time (approximately
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sixty-five million (65,000,000) years ago), is a broad, erosional trench
which separates the Southern Rocky Mountains from the High Plains.
Structurally, the property lies along the western flank of the Denver
Basin. During the Late Mesozoic and Early Cenozoic Periods
approximately seventy million (70,000,000) years ago), intense tectonic
activity occurred, causing the uplifting of the Front Range and the
associated downwarping of the Denver Basin to the east. Relatively flat
uplands and broad valleys characterize the present-day topography of the
Colorado Piedmont in this region. The site is underlain by the
Cretaceous Pierre Formation. The Pierre formation is overlain by
residual and alluvial soils of Pleistocene and/or Recent Age.
The property is relatively flat with total relief across the site
approximately fifteen (15) feet. Due to the relatively flat nature of the
site, geologic hazards due to mass movement clue to gravity, such as
landslides, mudflows, etc., are not anticipated on the property. With
proper site grading around structures, erosional problems should be
minimal. Bedrock underlies the site at depths of nineteen (19) to
twenty-seven (27) feet below the surface. The regional dip of the
bedrock in this area is slight and in an easterly direction. Seismic
activity in the area is expected to be low; therefore, from a structural
standpoint, the property should be relatively stable. The property lies
within the drainage basin of the Cache La Poudre River. Major drainage
at the site is to the east. The property does not lie within the flood
plain of the Cache La Poudre River and should not be subject to flooding_
by the stream.
ENVIRONMENTAL ASSESSMENT
The site consists of irrigated farm land. An abandoned farmhouse
and shed, one of which is currently used as a construction office, is
located northeast of the site. Benzene gas concentrations were measured
TheateachtestboringusinganHNUtracegasanalyzer. results of
the trace gas analyze- tests do not indicate petroleum contamination at
the site. The results of these tests are included in Appendix B. It is
our opinion that unacceptable levels of petroleum products do not exist
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at the site. The area surrounding the property consists of farm land
and residential areas to the west, residential areas and vacant land to
farmthenorthand land to the east and south. Commercial and
residential developments are currently being constructed east of Lemay
Avenue. Churches are located southeast and west of the site, and a
psychiatric hospital is being constructed southeast of the property. The
site is bordered on the north by Harmony Road. A convenience store
with gasoline pumps is located at the northwest corner of Boardwalk
Drive and Harmony Road adjacent to the northwest corner of the
property. Three 1200 gallon gasoline tanks were installed at the
convenience store in June 1984. There are no public records of any
leaks from these tanks, information includingandonthesetanks any
monitoring devices are not available from the owner. In addition, the
Poudre Fire Authority No. 3 firehouse located on Harmony Road
approximately one-half mile west of the site has two underground tanks.
The tanks have 560 gallon capacity. One is used to store gasoline and
one is used to store diesel fuel. These tanks were replaced eight
months ago and are provided with monitoring devices. Records of the
Poudre Fire Authority do not indicate any underground tanks of oil or
gas spills on the Pace property. It should be noted that our survey of
existing underground tanks is based on public record and verbal
communication. The possibility exists that non -recorded underground
tanks may exist on or adjacent to the property. The flow of ground
water in this area is to the east-southeast.
RECOMMENDATIONS AND DISCUSSION
It is our understanding the proposed warehouse facility is to be a
single -story, slab -on -grade structure having tilt -up wall panels with a
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barJ joist roof system. Column loads are anticipated to be between 75
and 100 kips, and wall loads are anticipated to be four (11) kips per
linear foot. The building will have six-inch thick concrete floor. A
portion of the structure will be dock height. In addition, two
commercial buildings are to be located to the west and northwest of the
Pace facility. It is anticipated that these will be single -story structures
having slab -on -grade construction. Parking areas will be located to the
north and west of the warehouse. Boardwalk and OakRidge Drives are
to be constructed along the west and south sides of the property.
Site Grading, Excavation and Utilities
Specifications pertaining to site grading are included below and in
Appendix C of this report. It is recommended that the upper six (6)
inches of topsoil below building, filled and paved areas be stripped and
stockpiled for reuse in planted areas. All existing fill should be
removed from below building, filled and paved areas and stockpiled for
reuse. The existing irrigation ditch to be abandoned should be
thoroughly cleaned of all vegetation and saturated subsoils. If the
existing irrigation ditch is to be maintained east of the site, it should be
properly relocated around the property. The upper six (6) inches of
subgrade below building, paved and filled areas should be scarified and
recompacted two percent (2°) wet of optimum moisture to a minimum of
ninety-five percent (95%) of Standard Proctor Density ASTM D 698-78.
See Appendix C.) Where this subgrade compaction cannot be obtained
due to saturated or unstable subsoil conditions, the subgrade should be
stabilized by use of granular pit -run material, geotextiles, lime, fly ash,
kiln dust or other suitable material. If lime, kiln dust or fly ash are
used to stabilize the subgrade below paved areas, pavement thicknesses
recommended in this report may possibly be reduced. Fill should consist
of the on -site soils or imported granular material approved by the
geotechnical engineer. All fill in paved areas shall have a minimum "R"
value of 8. Fill should be placed in uniform six (6) to eight (8) inch
lifts and mechanically compacted two percent (2 ) wet of optimum
moisture to a minimum of ninety-five percent (95%) of Standard Proctor
Density ASTM D 698-78.
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In computing earthwork quantities, an estimated shrinkage factor of
eighteen percent (186) to twenty-three percent (23%) may be used for
the on -site clays compacted to the above -recommended density.
All excavations should be dug on safe and stable slopes. It is
suggested that excavated slopes be on minimum grades of 1-1 /2:1 or
flatter. The slope of the sides of the excavations should comply with
local codes or OSHA regulations. Where this is not practical, sheeting,
shoring and/or bracing of the excavation will be required. The
IN sheeting, shoring and bracing of the excavation should be done to
prevent sliding or caving of the excavation walls and to protect
construction workers and adjacent structures. The side slopes of the
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excavation or sheeting, shoring or bracing should be maintained under
safe conditions until completion of backfilling. In addition, heavy
construction equipment should be kept a safe distance from the edge of
the excavation.
Utility trenches dug four (4) feet or more into the upper soils
should be excavated on stable and safe slopes in accordance with OSHA
regulations, or the excavations should be properly shored as discussed
above. Where utilities are excavated below ground water, dewatering
will be needed during placement of pipe and backfilling for proper
construction. All piping should be adequately bedded for proper load
distribution.
Backfill placed in utility trenches in open and planted areas should
be compacted in uniform lifts at optimum moisture to at least ninety
percent (90%) of Standard Proctor Density ASTM D 698-78 the full
depth of the trench. The upper four (4) feet of backfill placed in
utility trenches under roadways and paved areas should be compacted
at or near optimum moisture to at least ninety-five percent (95%) of
Standard Proctor Density ASTM D 698-78, and the lower portion of
these trenches should be compacted to at least ninety percent (90%) of
Standard Proctor Density ASTM D 698-78. Addition of moisture to
drying be forand/or of the subsoils may needed proper compaction.
Proper placement of the bedrock as backfill may be difficult.
Stripping, grubbing, subgrade preparation, and fill and backfill
placement should be accomplished under continuous observation of the
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geotechnical engineer. Field density tests should be taken daily in the
compacted subgrade, fill, and backfill under the direction of the
geotechnical engineer.
Laboratory resistivity tests, pH, oxidation-reduction anti sulfide
tests performed in the laboratory indicate that the subsoils at the site
are noncorrosive, and protection of metal utility pipe, in our opinion,
will not be required.
Foundation
In view of the loads transmitted by the proposed construction and
the soil conditions encountered at the site, it is recommended that the
structures be supported by conventional -type spread footings and/or
grade beams. All footings and/or grade beams should be founded on the
original, undisturbed soil or on a structural fill extended to the
undisturbed soil. All exterior- footings should be placed a minimum of
thirty (30) inches below finished grade for frost protection. In no case
should footings be founded on the existing fill encountered at the site.
The structural fill should be constructed in accordance with the
recommendations discussed in the "Site Grading, Excavation and Utilities"
section of this report. The structural integrity of the fill as well as the
identification and undisturbed nature of the soil should be verified by
the geotechnical engineer prior to placement of any foundation concrete.
Footings and/or grade beams founded at the above levels may be
designed for a rrraximum allowable bearing capacity of two thousand
2000) pounds per square foot (dead load plus maximum live load). To
counteract swelling pressures which will develop if the subsoils become
wetted, all footings and/or grade beams should be designed for a
minimum dead load of five hundred (500) pounds per square foot.
The predicted settlement under the above maximum loading, as
determined by laboratory consolidation tests, should be less than
three -fourths (3/4) inch, generally considered to be within acceptable
tolerances.
A feasible foundation alternate would be to support the warehouse
structure by a drilled pier foundation system. Using this type of
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foundation system, the structure is supported by piers drilled into the
bedrock stratum and structural grade beams spanning the piers. Piers
should be straight -shaft and should be drilled within plumb tolerances of
one and one-half percent (1-112%) relative to the length of the pier.
The piers are supported by the bedrock stratum partially through end
bearing and partially through skin friction. It is recommended that all
piers be drilled a minimum of three (3) feet into the firm bedrock
stratum. Piers founded at the above level may be designed for a
maximum allowable end bearing pressure of thirty thousand (30,000)
pounds per square foot. It is estimated that a skin friction of three
thousand (3000) pounds per square foot will be developed for that
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portion of the pier embedded into the firm bedrock stratum. To
counteract swelling pressures which will develop if the subsoils become
wetted, all piers should be designed for a minimum dead load of five
thousand (5000) pounds per square foot. Where this minimum dead load
Nrequirement cannot be satisfied, it is recommended that skin friction
from additional embedment into the firm bedrock be used to resist uplift.
To help provide the required skin friction, the sides of the pier drilled
into the bedrock stratum should be roughened. All piers should be
reinforced their full length to resist tensile stresses created by swelling
pressures acting on the pier. It is recommended that all grade beams
have a minimum four (4) inch void between the bottom of the beam and
the soil below. The predicted settlement under the above maximum
loading should be negligible.
Drilled piers should be designed to resist all induced lateral forces.
The ultimate passive resistance of the upper clay overburden materials
above existing ground water may be computed using the equation Pp =
20OZ + 2500 pounds per square foot. Below existing ground water, the
ultimate passive resistance of the overburden clay material may be
computed using the equation Pp = 150Z + 2500 pounds per square foot.
The ultimate passive resistance of the sand and gravel below ground
be by the Pp = 275Zwatermaycomputedequation pounds per square
foot. In all cases, Z is the depth below the top of the stratum. It is
recommended that a safety factor of 3 be used in conjunction with the
above equations. Since all bedrock is below ground water, temporary
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casing of the drill holes will be required. It is suggested that all piers
should have minimum eighteen (18) inch diameters.
It is strongly recommended that the geotechnical engineer be
present during the drilling operations to (1) identify the firm bedrock
stratum, (2) assure that proper penetration is obtained into the sound
bedrock stratum, (3) ascertain that all drill holes are thoroughly
roughened, cleaned and dewatered prior to placement of any foundation
concrete, (4) check all drill holes to assure that they are plumb and of
the proper diameter, and (5) ensure proper placement of concrete and
reinforcement.
Backfill
Backfill placed adjacent to the building should consist of the on -site
clay soils or imported granular material approved by the _geotechnical
engineer. The backfill should be mechanically compacted in uniform six
6) to eight (8) inch lifts to a minimum of ninety-five percent (95%) of
Standard Proctor Density ASTM D 698-78 (see Appendix C) or eighty
percent (80%) of Relative Density ASTM D 4253, D 4254. Free-standing
foundation walls backfilled with the on -site clay soils may be designed
using a hydrostatic pressure distribution and equivalent fluid pressure
of sixty (60) pounds per cubic foot per foot depth of backfill.
Slabs on Grade
It is our understanding that a six-inch thick slab on grade will be
constructed in all areas of the Pace Warehouse building. Subgrade below
all slabs on grade should be prepared in accordance with the
recommendations discussed in the "Site Grading, Excavation and Utilities"
section of this report. It is extremely important that the subgrade be
two percent (20) wet of optimum moisture just prior to placement of
underslab gravel and concrete. Should the subgrade below slabs on
grade be allowed to dry prior to placement of the underslab gravel, the
subgrade should be rewetted just prior to placement of the gravel and/or
concrete. Slabs on grade should be underlain by a minimum of four (4)
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inches of 3/4-inch aggregate meeting ASTM C 33, Size No. 67
specifications. The gravel will help to distribute floor loads and should
act as a capillary break. In our opinion, a vapor barrier will not be
required below slabs on grade. Slabs on grade for the Pace facility
should be designed for the imposed heavy warehouse loads including fork
lift loads, and it is recommended that all slabs be designed structurally
independent of bearing members. To minimize and control shrinkage
cracks which may develop in slabs on grade, we suggest that control
joints be placed every fifteen (15) to twenty (20) feet and that the total
area contained within these joints be no greater than four hundred (400)
square feet.
In addition, if building construction is done during winter months,
it is recommended that the slab on grade not be poured until the
building has been enclosed and heat is available within the building
area so that slab -on -grade concrete is not placed on frozen ground.
This will also aid in proper ci.,ring of the slab concrete.
Retaining Walls and Light Standards
Retaining walls three (3) feet or less in height constructed at the
site should be backfilled with the on -site clay soils. These relatively
impervious clays will help prevent surface water from reaching the
backfill area. The clay backfill should be compacted in uniform lifts two
percent (2%) wet of optimum moisture to a minimum of ninety-five percent
95%) of Standard Proctor Density ASTM D 698-78. (See Appendix C. )
Retaining wall structures over three (3) feet in height constructed at
the site should be backfilled with approved, free -draining granular
material to within one and one-half (1-1/2) to two (2) feet of the top of
the structure. The granular backfill should be compacted to at least
eighty percent (80%) of Relative Density ASTM D 4253-83, D 4254-83.
The granular backfill should be overlain by an untreated building paper
or filter fabric to prevent the overlying backfill from clogging the filter
material. The upper one and one-half (1-1/2) to two (2) feet of backfill
behind retaining walls over three (3) feet in height should consist of the
on -site relatively impervious clay material compacted to the
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above -required density. Retaining walls backfilled with the on -site clays
should be designed using a hydrostatic pressure distribution and
equivalent fluid pressure of sixty (60) pounds per cubic foot per foot
depth of backfill. Retaining walls backfilled with imported granular
material should be designed using a hydrostatic pressure distribution
and equivalent fluid pressure of forty (40) pounds per cubic foot per
foot depth of granular backfill. The maximum toe pressure should not
exceed two thousand (2000) pounds per square foot, and the bottom of
the footing should be placed a minimum of thirty (30) inches below the
low side finished grade for frost protection. Footings should be founded
on the original, undisturbed soil or on properly compacted structural fill
constructed in accordance with the recommendations discussed in the
Site Grading, Excavation and Utilities" section of this report. Weep
holes should be provided in the retaining wall so that hydrostatic
pressures which may develop behind the walls will be minimized.
Positive drainage should be provided away from the top of the wall to
prevent ponding of water in the area behind the wall.
It is recommended that all light standards be drilled pier type
foundations. The ultimate passive pressure of the upper clay soils
encountered at the site at depth Z may be expressed by the equation Pp
20OZ + 2500 pounds per square foot. The above passive pressure may
be used in the design criteria for resisting lateral loads and overturning
moments developed on the pier. It is suggested that a factor of safety
of 3 be used in conjunction with the above equation. All piers should
extend a minimum of thirty (30) inches below finished grade for frost
protection. Piers should be founded on the original, undisturbed soil or
properly placed fill that has been compacted to a minimum of ninety-five
percent (95%) of Standard Proctor Density ASTM D 698-78 in accordance
with the recommendations discussed in the "Site Grading, Excavation and
Utilities" section of this report.
Pavement
It is our opinion that flexible pavement is suitable for the proposed
pavement construction at the site. A flexible pavement alternate should
consist of asphalt concrete underlain by crushed aggregate base course
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or asphalt concrete underlain by plant mix bituminous base course.
Using the City of Fort Collins "Design Criteria and Standards for
Streets" dated July 1986, a serviceability index of 2.0 for all parking
and drive areas and 2.5 for Boardwalk and OakRidge Drives which are
collector -commercial streets, a regional factor of 1.0, an "R" value of 8,
a twenty (20) year design life, eighteen (18) kip equivalent daily load
applications of 5 for parking and drive areas, 40 for driveways and
truck loading areas and 65 for Boardwalk Drive and 35 for OakRidge
Drive, and weighted structural numbers of 2.30 for parking areas, 3.0
for drive areas, 3.55 for Boardwalk Drive and 3.20 for OakRidge Drive,
the following minimum pavement thicknesses are recommended:
Passenger Car Parking
Asphalt Concrete 24"
Crushed Aggregate Base Course 10"
Total Pavement Thickness 121"
Asphalt Concrete 2"
Plant Mix Bituminous Base Course 3111
Total Pavement Thickness 5111
Driveways and Truck Loading Areas
Asphalt Concrete 4"
Crushed Aggregate Base Course 11"
Total Pavement Thickness 15"
Asphalt Concrete 3"
Plant Mix Bituminous Base Course 5"
Total Pavement Thickness 8"
Boardwalk Drive
Asphalt Concrete 4"
Crushed Aggregate Base Course 16"
Total Pavement Thickness 20"
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Asphalt Concrete 3"
Plant Mix Bituminous Base Course 61"
Total Pavement Thickness 94"
i nakRidge Drive
Asphalt Concrete 4"
Crushed Aggregate Base Course 13"
Total Pavement Thickness 17"
Asphalt Concrete 3"
Plant Mix Bituminous Base Course 5111
Total Pavement Thickness 8111
The crushed aggregate base course should meet City of Fort Collins
Class 5 or 6 specifications. The subgrade below the proposed asphalt
pavement should be prepared in accordance with the recommendations
discussed in the "Site Grading, Excavation and Utilities" section of this
report. Upon proper preparation of the subgrade, the base course
should be placed and compacted at optimum moisture to at least
ninety-five percent (95%) of Standard Proctor Density ASTM D 698-78.
See Appendix C. )
It is recommended that the asphalt concrete and/or plant mix
bituminous base course be placed in two (2) to three (3) inch lifts. All
plant mix bituminous base course and asphalt concrete shall meet City of
Fort Collins specifications and should be placed in accordance with these
specifications. The crushed aggregate base course shall have an "R"
Nvalue between 70 and 77, the plant mix bituminous base course shall
have an Rt value of 90 or greater, and the asphalt concrete shall have
an Rt value of 95 or greater. The "R" value of the pavement materials
used should be verified by laboratory tests. Field density tests should
be taken in the aggregate base course, bituminous base course, and
asphalt concrete under the direction of the geotechnical engineer.
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Rigid Pavement
A feasible bepavementalternatLatthesitewould rigid pavement.
Using the eighteen (18) kip equivalent daily load application described
above, a modulus of subgrade reaction of one hundred (100) pounds per
square inch per inch based on an "R" value of 8, a design life of twenty
20) years, and concrete designed with a modulus of rupture of six
hundred (600) pounds per square inch, the following minimum pavement
thicknesses are recommended:
Passenger Car Parking
Nonreinforced Concrete 5"
Driveways and Truck Loading Areas
Nonreinforced Concrete - 7"
Boardwalk Drive
Nonreinforced Concrete - 7"
OakRidge Drive
Nonreinforced Concrete - 6"
Subgrade below proposed streets should be prepared in accordance with
the recommendations discussed in the "Site Grading, Excavation and
Utilities" section of this report. Concrete pavement should be placed
directly on the Subgrade that has been uniformly and properly prepared
in accordance with the above recommendations. All concrete used in the
paving shall meet ASTM specifications, and all aggregate shall conform to
ASTM C-33 specifications. The concrete should be designed with a
minimum modulus of rupture of six hundred (600) pounds per square inch
in twenty-eight (28) days. It is recommended that laboratory mix
designs be done to determine the proper proportions of aggregates,
cement, and water necessary to meet these requirements. It is essential
that the concrete have a low water -cement ratio, an adequate cement
factor, and sufficient quantities of entrained air. Joints should be
carefully designed and constructed in accordance with the City of Fort
Collins "Design Criteria and Standards for Streets" to ensure good
performance of the pavement. It is recommended that all concrete
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pavement be placed in accordance with City of Fort Collins
specifications. If paving is done during cold weather, acceptable cold
weather procedures as outlined in the City specifications should be
utilized. The concrete pavement should be properly cured and protected
in accordance with the above specifications. Concrete injured by frost
should be removed and replaced. It is recommended that the pavement
not be opened to traffic until a flexural strength of four hundred (400)
pounds per square inch is obtained or a minimum of fourteen (14) days
after the concrete has been placed.
GENERAL RECOMMENDATIONS
1) Laboratory test results indicate that water soluble sulfates in
the soil are negligible, and a Type 1-II cement may he used in
concrete exposed to subsoils. Slabs on grade subjected to
de-icing chemicals should be composed of a more durable
concrete with low water -cement ratios and higher air contents.
2) Finished grade should be sloped away from the structures on all
sides to give positive drainage. Five percent (5%) for the first
ten (10) feet away from the structures is the suggested slope.
3) Gutters and downspouts should be designed to carry roof
runoff water well beyond the backfill area.
4) Underground sprinkling systems should be designed such that
piping is placed a minimum of five (5) feet outside the backfill
of the structures. Heads should be designed so that irrigation
water is not sprayed onto the foundation walls. These
recommendations should be taken into account in the landscape
planning.
5) Footing, grade beam and/or pier sizes should be proportioned
to equalize the unit loads applied to the soil and thus minimize
differential settlements.
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6) It is recommended that compaction requirements in the project
specifications be verified in the field with density tests
performed under the direction of the geotechnical engineer.
7) It is recommended that a registered professional engineer design
the substructures and that he take into account the findings
and recommendations of this report.
GENERAL COMMENTS
This report has been prepared to aid in the evaluation of the
property and to assist the architect and/or engineer in the design of
this project. In the event that any changes in the design of the
structures or their locations are planned, the conclusions and
recommendations contained in this report will not be considered valid
unless said changes are reviewed and conclusions of this report modified
or approved in writing by Empire Laboratories, Inc., the geotechnical
engineer of record.
Every effort -was made to provide comprehensive site coverage
through careful locations of the test borings, while keeping the site
investigation economically viable. Variations in soil and ground water
conditions between test borings may be encountered during construction.
In order to permit correlation between the reported subsurface conditions
and the actual conditions encountered during construction and to aid in
carrying out the plans and specifications as originally contemplated, it is
recommended that Empire Laboratories, Inc. be retained to perform
continuous construction review during the excavation and foundation
phases of the work. Empire Laboratories, Inc. assumes no responsibility
for compliance with the recommendations included in this report unless
they have been retained to perform adequate on -site construction review
during the course of construction.
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APPENDIX A.
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TEST BORING LOCATION PLAN
t,06116, MAP
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