HomeMy WebLinkAboutPSD PROSPECT SCHOOL SITE SITE PLAN ADVISORY REVIEW - SPA190002 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTGeotechnical Subsurface Exploration Program
Poudre School District:
New Prospect 6-12 School
Fort Collins, Colorado
Prepared for:
Poudre School District
2407 La Porte Avenue
Fort Collins, Colorado
Attention: Mr. John Little
Job Number: 19-0013 June 17, 2019
Project Site
TABLE OF CONTENTS
Page
Purpose and Scope of Study ..................................................................................... 1
Proposed Construction .............................................................................................. 1
Site Conditions .......................................................................................................... 2
Subsurface Exploration ............................................................................................. 2
Laboratory Testing .................................................................................................... 3
Geologic Setting ........................................................................................................ 3
Subsurface Conditions .............................................................................................. 4
Seismic Classification ................................................................................................ 5
Foundation/Floor System Overview ............................................................................. 6
Shallow Foundation System ...................................................................................... 8
Slab-on-Grade Floor System ..................................................................................... 9
Post-Tensioned Tennis Court Slabs .......................................................................... 13
Water Soluble Sulfates .............................................................................................. 15
Soil Corrosivity .......................................................................................................... 15
Lateral Earth Pressures ........................................................................................... 18
Irrigation Pond Liner ................................................................................................ 19
Project Earthwork .................................................................................................... 20
Excavation Considerations ...................................................................................... 24
Exterior Flatwork ..................................................................................................... 25
Utility Pipe Installation and Backfilling ....................................................................... 28
Surface Drainage .................................................................................................... 31
Subsurface Drainage ................................................................................................ 35
Pavement Sections ..................................................................................................... 36
Closure and Limitations ........................................................................................... 43
Locations of Test Holes ................................................................................... Figure 1
Logs of Test Holes ................................................................................ Figures 2 to 6
Legend and Notes ........................................................................................... Figure 7
Proctor Curve .................................................................................................. Figure 8
R-Value ........................................................................................................... Figure 9
Summary of Laboratory Test Results .............................................................. Table 1
Summary of Soil Corrosion Test Results ............................................................. Table 2
Detailed Drilling Logs .................................................................................. Appendix A
Pavement Section Calculations ................................................................... Appendix B
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 1 of 46
PURPOSE AND SCOPE OF STUDY
This report presents the results of a geotechnical evaluation performed by GROUND
Engineering Consultants, Inc. (GROUND) for the Poudre School District in support of
design of the proposed New Prospect 6-12 School in Fort Collins, Colorado. Our study
was conducted in general accordance with GROUND’s Proposal No. 1904-0693, dated
April 11th, 2019
A field exploration program was conducted to obtain information on the subsurface
conditions. Material samples obtained during the subsurface exploration were tested in
the laboratory to provide data on the engineering characteristics of the on-site soils. The
results of the field exploration and laboratory testing are presented herein.
This report has been prepared to summarize the data obtained and to present our
findings and conclusions based on the proposed development/improvements and the
subsurface conditions encountered. Design parameters and a discussion of engineering
considerations related to the proposed improvements are included herein. This report
should be understood and utilized in its entirety; specific sections of the text, drawings,
graphs, tables, and other information contained within this report are intended to be
understood in the context of the entire report. This includes the Closure section of the
report which outlines important limitations on the information contained herein.
This report was prepared for design purposes of Poudre School District based on our
understanding of the proposed project at the time of preparation of this report. The data,
conclusions, opinions, and geotechnical parameters provided herein should not be
construed to be sufficient for other purposes, including the use by contractors, or any
other parties for any reason not specifically related to the design of the project.
Furthermore, the information provided in this report was based on the exploration and
testing methods described below. Deviations between what was reported herein and the
actual surface and/or subsurface conditions may exist, and in some cases those
deviations may be significant.
PROPOSED CONSTRUCTION
GROUND understands this project will consist of the construction of a new school
building, with no below-grade levels. Playgrounds, recreation fields, a track and football
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 2 of 46
field, parking areas, drive lanes, flatwork, and landscaping also will be included as part
of the project. Preliminary information indicated that strip footing loads are anticipated to
be 4000 lbs/ft or less and column loads are anticipated to be 200 kips or less. Grading
plans were not available at the time of our exploration, however based on preliminary
information it appears that the site will require some minimal fills on the order of 1 to 4
feet to achieve project lines and grades. The project area and test hole locations are
shown on Figure 1.
SITE CONDITIONS
At the time of our subsurface exploration
program, the site generally existed as an
agricultural field that had been partially
harvested. The site is bordered by South
County Road 5 to the east, an irrigation ditch
and East Prospect Road to the south,
undeveloped agricultural fields to the west,
and residential housing to the north. The
ground surface generally is flat with little notable slope.
Man-made fill was not recognized in the test holes during the subsurface exploration
program. Based on historical Google Earth Imagery several structures formerly stood
centrally located near the irrigation ditch on the south of the site. Man-made fill materials
likely exist near where these structures stood. The exact extents, limits, and
composition of any man-made fill were not determined under the scope of this study.
Fills potentially, exist at varying depths and locations across the site.
SUBSURFACE EXPLORATION
The subsurface exploration for the project was conducted in May 2019. A total of thirty-
three (32) test holes were drilled with a truck-mounted, continuous flight power auger rig
to evaluate the subsurface conditions as well as to retrieve soil samples for laboratory
testing and analysis. Nine (9) of the test holes were drilled within the approximate
footprint of the new school building. One (1) test hole was drilled for the restroom
structure near the baseball/softball fields. Four (4) test holes were drilled for the track
and football field grandstands. Two (2) test holes were drilled for PT tennis courts. Ten
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 3 of 46
(10) test holes were drilled for site improvements including pavements and an irrigation
pond. Four (4) test holes were drilled within the public right-of-way south and east of the
site. The foundation test holes were drilled to depths ranging from approximately 30 to
40 feet below existing grade. The site and pavement test holes were drilled to depths
ranging from 5 to 15 feet below existing grades. A GROUND engineer directed the
subsurface exploration, logged the test holes in the field, and prepared the soil samples
for transport to our laboratory.
Samples of the subsurface materials were retrieved with a 2-inch I.D. California liner
sampler. The sampler was driven into the substrata with blows from a 140-pound
hammer falling 30-inches. This procedure is similar to the Standard Penetration Test
described by ASTM Method D1586. Penetration resistance values, when properly
evaluated, indicate the relative density or consistency of soils. Depths at which the
samples were obtained and associated penetration resistance values are shown on the
test hole logs.
The approximate locations of the test holes are shown in Figure 1. Logs of the
exploratory test holes are presented in Figure 2 to 6. Explanatory notes and a legend
are provided in Figure 7.
LABORATORY TESTING
Samples retrieved from our test holes were examined and visually classified in the
laboratory by the project engineer. Laboratory testing of soil samples obtained from the
subject site included standard property tests, such as natural moisture contents, dry unit
weights, grain size analyses, liquid and plastic limits. Water-soluble sulfate and
corrosivity tests were completed on selected samples of the soils as well. Laboratory
tests were performed in general accordance with applicable ASTM protocols. Results of
the laboratory testing program are summarized on Tables 1 and 2.
GEOLOGIC SETTING
The site lies within a geological structural depression within the Great Plains called the
Denver Basin. Within this basin a sequence of sedimentary rock formations including the
Pierre Shale were deposited. In the general project area, these sedimentary rocks dip
eastward at low angles (less than 10 degrees, typically).
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 4 of 46
Published geologic maps, e.g., Moore et al. (2003)1 depict the project area as underlain,
by, Pleistocene Broadway Alluvium (Qb). Windblown deposits were mapped a short
distance to the northeast, however. These alluvial materials are described as sand and
gravel deposited by the South Platte River and its tributaries. These alluvial deposits are
mapped as underlain by the upper shale member of the Upper Cretaceous Pierre Shale
(Kpu). This unit is generally described as silty shale.
SUBSURFACE CONDITIONS
In general, the site test holes penetrated a thin layer of topsoil2, approximately 12 inches
thick (greater or lesser thicknesses likely exist locally), underlain by sand and gravel to
depths of approximately 12 to 20 feet below grade. The sand and gravel was underlain
by clay and sand with occasional gravel and extended to the test hole termination depths
of approximately 25 to 40 feet below existing grades.
The test holes advanced within the public pavements encountered approximately 4.5 to
6.5 inches of asphalt at the surface underlain by sand and clay materials to a depth of
1 Moore, Theodore R., Brandt David W., and Kyle E. Murray. "A spatial database of bedding attitudes to
accompany Geologic Map of the Boulder--Fort Collins--Greeley area, Colorado, by Roger B. Colton."
(2003).
2
‘Topsoil’ as used herein is defined geotechnically. The materials so described may or may not be suitable
for landscaping or as a growth medium for such plantings as may be proposed for the project.
Approximate
Project Site
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 5 of 46
approximately 1 to 5 feet below existing grades. Sand and gravel materials were
encountered below sand and clay materials and extended to the test hole termination
depths of approximately 7 to 10 feet below existing grades.
It also should be noted that coarse gravel, cobbles and boulders are not well
represented in samples obtained from small diameter test holes. At this site, therefore, it
should be anticipated that gravel and cobbles, and possibly boulders, may be present in
the fill and native soils, as well as comparably sized fragments of construction debris,
even where not included in the general descriptions of the site soil types below. We
interpret the soil to be Broadway Alluvium.
Topsoil was observed in the upper 12 inches of the site and was brown and humic.
Sand and Gravel were silty to clayey, non- to low plastic, fine to coarse grained with
gravel, moist to wet, loose to dense, and light brown to pink to dark brown in color.
Sand and Clay was, was moderately plastic, fine to coarse grained, moist, medium to
very stiff, and light brown to brown in color.
Bedrock materials were not encountered to the depths explored.
Groundwater was encountered in the majority of test holes at depths ranging from 8.5
to 16 feet below existing grades. Groundwater depths observed at the time of the
preliminary study performed at this project site were as shallow as 6.5 feet below
existing grades. Groundwater levels can be expected to fluctuate, however, in response
to annual and longer-term cycles of precipitation, irrigation, surface drainage, nearby
rivers, and drainage, land use, and the development of transient, perched water
conditions.
SEISMIC CLASSIFICATION
According to the 2015 International Building Code® (Section 1613 Earthquake Loads),
“Every structure, and portion thereof, including nonstructural components that are
permanently attached to structures and their supports and attachments, shall be
designed and constructed to resist the effects of earthquake motions in accordance with
ASCE 7, excluding Chapter 14 and Appendix 11A. The seismic design category for a
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 6 of 46
structure is permitted to be determined in accordance with Section 1613 (2015 IBC) or
ASCE 7.” Exceptions to this are further noted in Section 1613.
Based on extrapolation of available data to depth and our experience in the project area,
we consider the site likely to meet the criteria for a Seismic Site Classification of D
according to the 2015 IBC classification (Section 1613.3.2). If, however, a quantitative
assessment of the site seismic properties is desired, then sampling or shear wave
velocity testing to a depth of 100 feet or more should be performed.
Utilizing the OSHPD Seismic Design Maps website (https://seismicmaps.org/), the
project area is indicated to possess an SDS value of 0.188g and an SD1 value of 0.091g
for the site latitude and longitude and a Site Class of D.
FOUNDATION/FLOOR SYSTEMS OVERVIEW
Geotechnical Considerations for Design: The native overburden materials
encountered at the project site are in general suitable to support lightly loaded spread
footing and slab on grade construction. The primary geotechnical concerns at the
project site include some locally soft layers of subsurface materials below a depth of
approximately 15 feet below grade and removal of potential relic foundations or utilities
associated with the previously removed structures on the south central portion of the
site.
School Facility Foundations: Footings should bear on firm undisturbed native
materials at depths of at least 3 feet below exterior grades. A representative of the
geotechnical engineer should be retained to verify bearing conditions. Footings bearing
on native soil may be designed for an allowable soil bearing pressure (Q) of 2,000
psf.
Bleacher and Secondary Structure Foundations: Footings should bear on firm
undisturbed native materials at depths of at least 3 feet below exterior grades. A
representative of the geotechnical engineer should be retained to verify bearing
conditions. Footings bearing on native soil may be designed for an allowable soil
bearing pressure (Q) of 1,750 psf.
Floor System: At least 12 inches of onsite materials below the proposed slab-on-grade
floor and under-slab gravel should be scarified and re-compacted in a properly moisture-
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 7 of 46
density conditioned state in accordance with the Project Earthworks section of this
report. If no sub-slab gravel is used, the re-work section should be increased
correspondingly.
Geotechnical Risk: To use these parameters, the Owner must accept the risk of post-
construction foundation movement associated with shallow foundation systems placed
on the on-site soils. Utilizing the above parameters as well as other parameters in this
report, we estimate likely post-construction foundation and floor movements to be on the
order of 1 inch, with 1/2 inch differential movements over spans of about 40 feet.
Movement estimates are difficult to predict and actual movements may be more or less
The conclusions and parameters provided in this report were based on the data
presented herein, our experience in the general project area with similar structures, and
our engineering judgment with regard to the applicability of the data and methods of
forecasting future performance. A variety of engineering parameters were considered as
indicators of potential future soil movements. Our recommendations were based on our
judgment of “likely movement potentials,” (i.e., the amount of movement likely to be
realized if site drainage is generally effective, estimated to a reasonable degree of
engineering certainty) as well as our assumptions about the owner’s willingness to
accept geotechnical risk. “Maximum possible” movement estimates necessarily will be
larger than those presented herein. They also have a significantly lower likelihood of
being realized in our opinion, and generally require more expensive measures to
address. We encourage the Poudre School District, upon receipt of this report, however,
to discuss potential risks and the geotechnical alternatives with us.
The Poudre School District must, therefore, understand the risks and remedial
approaches presented in this report (and the risk-cost trade-offs addressed by the civil
engineer and structural engineer) in order to direct the design team to the portion of the
Higher Cost / Lower Risk – Lower Cost / Higher Risk spectrum in which this project
should be designed. If the Poudre School District does not understand these risks, it is
critical that they request additional information or clarification so that their expectations
reasonably can be met.
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 8 of 46
SHALLOW FOUNDATION SYSTEM
The construction details should be considered when preparing project documents. The
precautions and recommendations provided below will not prevent movement of the
footings if the underlying materials are subjected to alternate wetting and drying cycles.
However, the recommended measures will tend to make the movement more uniform,
and reduce resultant damage if such movement occurs.
Geotechnical Parameters for Shallow Foundation Design:
1) Footings bearing on undisturbed, native materials or CDOT Class 5/6 Aggregate
Base Course Materials can be designed for the allowable bearing pressure
provided above.
These values may be increased by ⅓ for transient loads such as wind or seismic
loading.
Compression of the bearing soils for the provided allowable bearing pressure is
estimated to be 1 inch, based on an assumption of drained foundation conditions.
If foundation soils are subjected to an increase/fluctuation in moisture content,
the effective bearing capacity will be reduced and greater post-construction
movements than those estimated above may result.
2) To be able to use the allowable bearing capacity values presented above, strip
footings should be limited to 5 feet or less in width and pad footing should have
a maximum dimension of 10 feet. For other estimated settlements associated
with allowable bearing pressure values or footing widths exceeding the
dimensions above please contact this office. To evaluate locally, GROUND
requests proposed loading, depth, footing size, and location.
3) In order to reduce differential settlements between footings or along continuous
footings, footing loads should be as uniform as possible. Differentially loaded
footings will settle differentially.
Similarly, differential fill thickness beneath footings will result in increased
differential settlements.
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 9 of 46
4) Spread footings should have a minimum lateral dimension of 18 or more inches
for linear strip footings and 24 or more inches for isolated pad footings. Actual
footing dimensions, however, should be determined by the structural engineer.
5) All footings should bear at an elevation 3 or more feet below the lowest adjacent
exterior finish grades.
6) Continuous foundation walls should be reinforced top and bottom to span an
unsupported length of at least 10 feet.
7) Geotechnical parameters for lateral resistance to foundation loads are provided
in the Lateral Earth Pressures section of this report.
8) Connections to the building of all types must be flexible and/or adjustable to
accommodate the anticipated, post-construction movements.
9) Care should be taken when excavating the foundations to avoid disturbing the
supporting materials. Hand excavation or careful backhoe soil removal may be
required in excavating the last few inches.
10) Footing excavation bottoms may expose loose, organic or otherwise deleterious
materials, including debris. Firm materials may become disturbed by the
excavation process. All such unsuitable materials should be excavated and
replaced with properly compacted fill or the footing deepened.
11) Compacted fill placed below and against the sides of the footings should be
compacted in accordance with the criteria in the Project Earthwork section of this
report.
SLAB-ON-GRADE FLOOR SYSTEM
The materials encountered during our field and laboratory study appear suitable, in
general, to support a slab-on-grade floor system. However, as stated previously the
materials should be scarified and re-compacted in general conformance with the Project
Earthworks section of this report.
The following measures are recommended to reduce damage, which may result from
movement of the slab subgrade material. These measures will not eliminate potential
movements. If slab-on-grade construction is used in accordance with the following
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 10 of 46
criteria, as well as other applicable parameters contained in this report, we estimate that
potential slab movements may be on the order of 1 inch. The actual magnitude of
movement is difficult to estimate and may be more or less.
Geotechnical Parameters for Design of Slab-on-Grade Floors
1) An allowable subgrade vertical modulus (K) of 100 pci may be utilized for lightly
loaded slabs supported by properly moisture-density treated existing materials.
This value is for a 1-foot x 1-foot plate; they should be adjusted for slab
dimension.
2) Floor slabs should be separated from all bearing walls and columns with slip
joints, which allow unrestrained vertical movement.
Slip joints should be observed periodically, particularly during the first several
years after construction. Slab movement can cause previously free-slipping
joints to bind. Measures should be taken to assure that slab isolation is
maintained in order to reduce the likelihood of damage to walls and other interior
improvements.
3) Concrete slabs-on-grade should be provided with properly designed control
joints.
ACI, AASHTO and other industry groups provide guidelines for proper design
and construction concrete slabs-on-grade and associated jointing. The design
and construction of such joints should account for cracking as a result of
shrinkage, curling, tension, loading, and curing, as well as proposed slab use.
Joint layout based on the slab design may require more frequent, additional, or
deeper joints, and should reflect the configuration and proposed use of the slab.
Particular attention in slab joint layout should be paid to areas where slabs
consist of interior corners or curves (e.g., at column blockouts or reentrant
corners) or where slabs have high length to width ratios, significant slopes,
thickness transitions, high traffic loads, or other unique features. The improper
placement or construction of control joints will increase the potential for slab
cracking.
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 11 of 46
4) Interior partitions resting on floor slabs should be provided with slip joints so that
if the slabs move, the movement cannot be transmitted to the upper structure.
This detail is also important for wallboards and doorframes. Slip joints which will
allow 2 inches or more of differential vertical movement should be considered.
It may not be practical to construct slip joints capable of accommodating
movements of that magnitude. In such case, replacement of the slip joints or re-
establishment of slip capacity should be anticipated and incorporated into
building design. Accommodation for differential movement also should be made
where partitions meet bearing walls.
5) Post-construction soil movements may not displace slab-on-grade floors and
utility lines in the soils beneath them to the same extent. Design of floor
penetrations, connections and fixtures should accommodate at least 2 inches of
differential movement.
6) Moisture can be introduced into a slab subgrade during construction and
additional moisture will be released from the slab concrete as it cures. A properly
compacted layer of free-draining gravel, 4 or more inches in thickness, should be
placed beneath the slabs. This layer will help distribute floor slab loadings, ease
construction, reduce capillary moisture rise, and aid in drainage.
The free-draining gravel should contain less than 5 percent material passing the
No. 200 Sieve, more than 50 percent retained on the No. 4 Sieve, and a
maximum particle size of 2 inches.
The capillary break and the drainage space provided by the gravel layer also
may reduce the potential for excessive water vapor fluxes from the slab after
construction as mix water is released from the concrete.
We understand, however, that professional experience and opinion differ with
regard to inclusion of a free-draining gravel layer beneath slab-on-grade floors. If
these issues are understood by the owner and appropriate measures are
implemented to address potential concerns including slab curling and moisture
fluxes, then the gravel layer may be deleted.
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 12 of 46
7) A vapor barrier beneath a building floor slab is beneficial with regard to reducing
sub-slab moisture vapor transmission through the floor slab and into the building,
but can retard downward drainage of construction moisture. Elevated vapor
fluxes can be detrimental to the adhesion and performance of many floor
coverings and can also contribute to other moisture-induced concerns. Thus, an
effective sub-slab vapor barrier is a published industry requirement for most slab-
on-ground construction (i.e. IBC, ASTM), regardless of project location, soil
conditions, and water table depth.
8) Per ACI 302.2R-15, a vapor barrier is recommended under concrete slabs-on-
ground when they will receive (or could receive in the future) moisture-sensitive
floor coverings, coatings, adhesives, underlayments, and/or stored goods.
Moreover, ACI recommends a vapor barrier for any building which will be
humidity or climate controlled, including exposed slabs (such as industrial
warehouse). ACI 302 provides further guidance on the location of the vapor
barrier beneath the slab.
However, when slabs are placed directly on the vapor barrier, considerations and
steps may be needed to help reduce uneven drying/shrinkage concerns and
potential slab curl.
Therefore, the owner, architect, and/or contractor should weigh many
considerations when designing and implementing the sub-slab vapor barrier
system, including building use and operating conditions, flooring products, sub-
base (gravel layer) type, size, and thickness, expected construction traffic, etc.
When a vapor barrier is used, it should consist of a minimum 15-mil thickness,
extruded polyolefin plastic (no recycled content or woven materials), maintain a
permeance less than 0.01 perms per ASTM E96 or ASTM E1249 before and
after mandatory conditioning testing, and comply with ASTM E1745-17 (Class
“A”). Vapor barriers should be installed in accordance with ASTM E1643-18 and
the manufacturer’s guidelines. (Note that Polyethylene (“poly”) sheeting (even if
15 mils in thickness which polyethylene sheeting commonly is not) does not meet
the ASTM E1745 criteria and generally should not be used as a vapor barrier
material.)
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 13 of 46
9) Loose, soft or otherwise unsuitable materials exposed on the prepared surface
on which the floor slab will be cast should be excavated and replaced with
properly compacted fill.
10) Concrete floor slabs should be constructed and cured in accordance with
applicable industry standards and slab design specifications.
11) All plumbing lines should be carefully tested before operation. Where plumbing
lines enter through the floor, a positive bond break should be provided.
POST-TENSIONED TENNIS COURT SLABS
The soils underlying the site generally consisted of sandy soils that should provide
adequate support for the proposed improvements.
Remedial Earthwork A minimum of 12 inches of existing materials below the tennis
court should be scarified and re-compacted in a moisture conditioned and compacted
state in accordance with the parameters provided in the Project Earthwork section of this
report.
Inadequate site drainage and/or ineffective fill processing and compaction will result in
an increase in the slab movement estimate provided. In addition, actual movements
may be more or less depending on the subsurface materials present and the overall site
drainage after construction is completed and landscape irrigation commences.
A post-tensioned slab will experience total and differential vertical movements. The
remedial earthwork indicated will tend to make those movements more uniform but will
not preclude them. The slabs will move and experience differential strains across their
lengths and widths. If properly designed and constructed, post-tensioned slabs typically
will accommodate those differential strains without unacceptable levels of cracking.
We estimate that likely post-construction (total) vertical slab movements where post-
tensioned slabs bear on properly compacted fill will be about 1 inch. This estimated
post-construction (total) vertical movements will be superimposed on the differential
vertical movements indicated below that were estimated by means of the PTI Institute
methodology.
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New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 14 of 46
Parameters for Post-Tensioned Slab Design The parameters below were developed
in general accordance with PTI methodology using the methods and recommendations
provided by the Post-Tensioning Institute (PTI) in their recent design manuals.3, 4, 5 PTI’s
3rd Edition design methodology requires engineering judgment and interpretation of
available data in order to develop the recommended parameters and differing
interpretations can yield different parameters. Soil suction testing was not included in our
scope of work and was not performed for this study. Therefore, some parameters used
in this analysis were estimated, based on our experience with similar soils.
It should be noted that the use of PTI’s 3rd Edition methodology remains a matter of
controversy in Colorado within the geotechnical profession – particularly for residential
structures. It also should be noted, however, that many structures have been
constructed on post-tensioned slabs in the Colorado Front Range and, to our
knowledge, the great majority of them have performed as intended.
Geotechnical Parameters for Post-Tensioned Slab Design
Edge Moisture Variation Distance (Em)
Edge Lift …………………………………………………………….… 5.3 ft.
Center Lift ………………………………………………………......… 9.0 ft.
Differential Vertical Deflection (ym)
Edge Lift ……………………………………………………….. …….. 0.6 in.
Center Lift ………………………………………………………….…. 0.4 in.
Allowable Soil Bearing Pressure ………………………………………….. 1,750 psf
Design Frost Depth ……………………………………………………. 3 ft.
Vertical Modulus of Subgrade Reaction………………………………… 75 pci
(This value is for a 1-foot x 1-foot plate, and should be adjusted for slab dimension.)
3 Post-Tensioning Institute, 2004, Design and Construction of Post-Tensioned Slabs-on-Ground, 3
rd
Edition.
4 Post-Tensioning Institute, 2007, Addendum No. 1 to the 3
rd
Edition of the Design of Post-Tensioned Slabs-
on-Ground.
5 Post-Tensioning Institute, 2008, Addendum No. 2 to the 3
rd
Edition of the Design of Post-Tensioned Slabs-
on-Ground.
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New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 15 of 46
Slab Subgrade Friction Coefficient ()
0.75 for a ribbed or uniform thickness slab on polyethylene
1.00 for a slab cast directly on a sand base
WATER-SOLUBLE SULFATES
The concentrations of water-soluble sulfates measured in selected samples retrieved
from the test holes ranged from less than 0.01 percent to 0.05 percent by weight. (See
Table 2.) Such concentrations of water-soluble sulfates represent a negligible degree of
sulfate attack on concrete exposed to these materials. Degrees of attack are based on
the scale of 'negligible,' 'moderate,' 'severe' and 'very severe' as described in the “Design
and Control of Concrete Mixtures,” published by the Portland Cement Association
(PCA). The Colorado Department of Transportation (CDOT) utilizes a corresponding
scale with 4 classes of severity of sulfate exposure (Class 0 to Class 3) as described in
the published table below.
REQUIREMENTS TO PROTECT AGAINST DAMAGE TO
CONCRETE BY SULFATE ATTACK FROM EXTERNAL SOURCES OF SULFATE
Severity of
Sulfate
Exposure
Water-Soluble
Sulfate (SO4)
In Dry Soil
(%)
Sulfate (SO4)
In Water
(ppm)
Water
Cementitious
Ratio
(maximum)
Cementitious
Material
Requirements
Class 0 0.00 to 0.10 0 to 150 0.45 Class 0
Class 1 0.11 to 0.20 151 to 1500 0.45 Class 1
Class 2 0.21 to 2.00 1501 to 10,000 0.45 Class 2
Class 3 2.01 or greater 10,001 or greater 0.40 Class 3
Based on these data no use of special, sulfate-resistant cement appears necessary in
project concrete.
SOIL CORROSIVITY
The degree of risk for corrosion of metals in soils commonly is considered to be in two
categories: corrosion in undisturbed soils and corrosion in disturbed soils. The potential
for corrosion in undisturbed soil is generally low, regardless of soil types and conditions,
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 16 of 46
because it is limited by the amount of oxygen that is available to create an electrolytic
cell. In disturbed soils, the potential for corrosion typically is higher, but is strongly
affected by soil chemistry and other factors.
A preliminary corrosivity analysis was performed to provide a general assessment of the
potential for corrosion of ferrous metals installed in contact with earth materials at the
site, based on the conditions existing at the time of GROUND’s evaluation. Soil
chemistry and physical property data including pH, and sulfides content were obtained.
Test results are summarized on Table 2.
pH Where pH is less than 4.0, soil serves as an electrolyte; the pH range of about 6.5 to
7.5 indicates soil conditions that are optimum for sulfate reduction. In the pH range
above 8.5, soils are generally high in dissolved salts, yielding a low soil resistivity
AWWA, 2010). Testing indicated pH values ranging from approximately 8.3 to 8.7.
Reduction-Oxidation testing indicated negative potentials ranging from approximately
-95 to -69 millivolts. Such a low potential typically creates a more corrosive environment.
Sulfide Reactivity testing for the presence of sulfides indicated ‘positive’ results. The
presence of sulfides in the site soils also suggests a more corrosive environment.
Soil Resistivity In order to assess the “worst case” for mitigation planning, samples of
materials retrieved from the test holes were tested for resistivity in the in the laboratory,
after being saturated with water, rather than in the field. Resistivity also varies inversely
with temperature. Therefore, the laboratory measurements were made at a controlled
temperature.
A measurement of electrical resistivity indicated values of approximately 2,287 to 10,790
ohm-centimeters in respective samples of the site earth materials.
Corrosivity Assessment The American Water Works Association (AWWA, 20106) has
developed a point system scale used to predict corrosivity. The scale is intended for
protection of ductile iron pipe but is valuable for project steel selection. When the scale
equals 10 points or higher, protective measures for ductile iron pipe are suggested. The
6 American Water Works Association ANSI/AWWA C105/A21.5-05 Standard.
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 17 of 46
AWWA scale (Table A.1 Soil-test Evaluation) is presented below. The soil characteristics
refer to the conditions at and above pipe installation depth.
Table A.1 Soil-test Evaluation
Soil Characteristic / Value Points
Resistivity
<1,500 ohm-cm ..........................................................................................… 10
1,500 to 1,800 ohm-cm ................................................................……......…. 8
1,800 to 2,100 ohm-cm .............................................................................…. 5
2,100 to 2,500 ohm-cm ...............................................................................… 2
2,500 to 3,000 ohm-cm .................................................................................. 1
>3,000 ohm-cm ................................................................................… 0
pH
0 to 2.0 ............................................................................................................ 5
2.0 to 4.0 ......................................................................................................... 3
4.0 to 6.5 ......................................................................................................... 0
6.5 to 7.5 ......................................................................................................... 0 *
7.5 to 8.5 ......................................................................................................... 0
>8.5 ..................................................................................................... 3
Redox Potential
< 0 (negative values) ....................................................................................... 5
0 to +50 mV ................................................................................................…. 4
+50 to +100 mV ............................................................................................… 3½
> +100 mV ............................................................................................... 0
Sulfide Reactivity
Positive ........................................................................................................…. 3½
Trace .............................................................................................................… 2
Negative .......................................................................................................…. 0
Moisture
Poor drainage, continuously wet ..................................................................…. 2
Fair drainage, generally moist ....................................................................… 1
Good drainage, generally dry .................................................................... 0
* If sulfides are present and low or negative redox-potential results (< 50 mV) are
obtained, add three points for this range.
We anticipate that drainage at the site after construction will be effective. Based on the
values obtained for the soil parameters, the overburden soils appear to comprise a
highly corrosive environment for metals. (8.5 to 10.5 points)
If additional information are needed regarding soil corrosivity, the American Water Works
Association or a Corrosion Engineer should be contacted. It should be noted, however,
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 18 of 46
that changes to the site conditions during construction, such as the import of other soils,
or the intended or unintended introduction of off-site water, may significantly alter
corrosion potential.
LATERAL EARTH PRESSURES
Structures which are laterally supported and can be expected to undergo only a limited
amount of deflection should be designed for “at-rest” lateral earth pressures. The
cantilevered retaining structures will be designed to deflect sufficiently to mobilize the full
active earth pressure condition, and may be designed for “active” lateral earth pressures.
“Passive” earth pressures may be applied in front of the structural embedment to resist
driving forces.
The at-rest, active, and passive earth pressures in terms of equivalent fluid unit weight
for the on-site backfill is summarized on the table below. Base friction may be combined
with passive earth pressure if the foundation is in a drained condition. The values for the
on-site material in the upper 10 feet provided in the table below were approximated
utilizing a unit weight of 125 pcf and a phi angle of 30 degrees, and are un-factored.
Appropriate factors of safety should be included in design calculations.
Lateral Earth Pressures (Equivalent Fluid Unit Weights)
Material Type
Water
Condition
At-Rest
(pcf)
Active
(pcf)
Passive (pcf)
Friction
Coefficient
On-Site Backfill Drained 63 42 335 (max. 3,350 psf) 0.38
The lateral earth pressures indicated above are for a horizontal upper backfill slope. The
additional loading of an upward sloping backfill as well as loads from traffic, stockpiled
materials, etc., should be included in the wall/shoring design.
Project Retaining Walls We are not aware of any significant retaining structures
proposed as part of the facility improvements. Therefore, the above parameters should
be considered preliminary with regard to design of walls, etc. In the event that retaining
walls are added once project design begins, a geotechnical engineer should be retained
to develop parameters for retaining wall parameter design. Global stability analysis may
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 19 of 46
be needed, as well. The Poudre School District should realize that additional subsurface
exploration may be necessary.
IRRIGATION POND LINER Either a compacted clay liner or a synthetic (HDPE
membrane) liner appears feasible for the proposed storage pond. Criteria for fill
placement and compaction are provided in the Project Earthwork section of this report.
Parameters for an earth material-derived pond liner, specified by the State of Colorado
regarding plasticity, permeability(hydraulic conductivity), and gradation (Humphries,
20007), should be adhered to. The maximum permeability(hydraulic conductivity) for
such liner material is 1 x 10-6 cm/s.
It is our understanding that the proposed cross-section of the irrigation pond consists of
a 4:1 (horizontal:vertical) slope for the first approximately 12 lateral feet of the pond
transitioning to a 2:1 (h:v) slope to the bottom of the pond. Based on these proposed
slopes the following clay liner / cover parameters are provided below.
4:1 slope: The clay liner should consist of at least 2 feet of clay with an in-place
hydraulic conductivity of 10-6 cm/s or lower. Typically, local claystone-derived fills meet
that criterion when moisture-conditioned and compacted properly. We suggest that a
test section using the proposed liner soil be constructed so that the as-placed hydraulic
conductivity may be evaluated. This clay liner should be protected with at least 2 feet of
on-site native material.
2:1 slope: The clay liner should consist of at least 2 feet of clay with an in-place
hydraulic conductivity of 10-6 cm/s or lower. This clay liner should be protected with at
least 2 feet of a rip-rap soil mixture to protect the liner and stabilize the slope.
Alternatively a synthetic HDPE liner should be placed, lapped and sealed in accordance
with the manufacturer’s specifications. This alternative liner should be protected with at
least 18 inches of common fill derived from the project site.
If the pond liner is placed below the anticipated groundwater table elevation, then it
should be designed to resist buoyancy. We anticipate that this will entail lowering the
liner elevation and placing additional fill above it.
7
Humphries, Bruce, 2000, Guide to Specification Preparation for Slurry Walls and Clay Liners as a
Component of a Colorado Mined Land Reclamation Permit, Colorado Department of Natural Resources,
Division of Minerals and Geology, State of Colorado.
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 20 of 46
The Poudre School District should comply with applicable state requirements regarding
dam construction and water storage rights associated with this pond. Due to the
complexities of groundwater law in Colorado, Poudre School District should consider
retaining a design professional with local experience with this type of structure.
Minor raveling or surficial sloughing should be anticipated on slopes cut at the proposed
angles until vegetation is well re-established. Surface drainage should be designed to
direct water away from slope faces.
PROJECT EARTHWORK
The following information is for private improvements; public roadways or utilities
should be constructed in accordance with applicable municipal / agency
standards.
General Considerations Site grading should be performed as early as possible in the
construction sequence to allow settlement of fills and surcharged ground to be realized
to the greatest extent prior to subsequent construction.
Prior to earthwork construction, vegetation and other deleterious materials should be
removed and disposed of off-site. Relic underground utilities should be abandoned in
accordance with applicable regulations, removed as necessary, and properly capped. All
relic floor slab and footing foundation shall also be removed.
Topsoil present on-site should not be incorporated into ordinary fills. Instead, topsoil
should be stockpiled during initial grading operations for placement in areas to be
landscaped or for other approved uses. Due to the presence of large trees at the project
site, significant root systems associate with those trees will also require removal to
mitigate the risk of settlement caused by the breakdown of theses organic materials
overtime.
Wet, Soft, or Unstable Subgrades Where wet, soft, or unstable subgrades are
encountered, the contractor must establish a stable platform for fill placement and
achieving compaction in the overlying fill soils. Therefore, excavation of the unstable
soils and replacing them with relatively dry or granular material, possibly together with
the use of stabilization geo-textile or geo-grid, may be necessary to achieve stability. A
Geotechnical engineer should be retained to provide appropriate stabilization criteria
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 21 of 46
based on conditions encountered. Stabilization methods should be verified using a test
section to evaluate the effectiveness prior to use over a larger area.
Drainage During Construction The contractor should take pro-active measures to
control surface waters during construction, to direct them away from excavations and
into appropriate drainage structures. Wetting of foundation soils during construction can
have adverse effects on the performance of the proposed facility.
Filled areas should be graded to drain effectively at the end of each work day.
Use of Existing Native Soils Overburden soils that are free of trash, organic material,
construction debris, and other deleterious materials are suitable, in general, for
placement as compacted fill. Organic materials, including excavated coal if encountered,
should not be incorporated into project fills.
Fragments of rock, cobbles, and inert construction debris (e.g., concrete or asphalt)
larger than 3 inches in maximum dimension will require special handling and/or
placement to be incorporated into project fills. In general, such materials should be
placed as deeply as possible in the project fills. A geotechnical engineer should be
consulted regarding appropriate guidance for usage of such materials on a case-by-case
basis when such materials have been identified during earthwork. Standard
recommendations that likely will be generally applicable can be found in Section 203 of
the current CDOT Standard Specifications for Road and Bridge Construction.
Where excavated bedrock materials are placed as fill, the contractor should anticipate
significantly more than typical efforts to moisture condition and compact the fill properly.
The excavated material should be disked or otherwise processed until it is broken down
into fragments no larger than 3 inches in maximum dimension and moisture-conditioned
prior to compaction.
Imported Fill Materials If it is necessary to import material to the site other than the
CDOT Class 1 Structure backfill for the basement fills and slab-on-grade construction,
the imported soils should be free of organic material, and other deleterious materials.
Imported material should consist of materials that have 50 percent or less passing
the No. 200 Sieve and should have a plasticity index 15 or less. Representative
samples of the materials proposed for import should be tested and approved prior to
transport to the site.
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 22 of 46
Fill Platform Preparation Prior to filling, the top 12 inches of in-place materials on
which fill soils will be placed should be scarified, moisture conditioned and properly
compacted in accordance with the parameters below to provide a uniform base for fill
placement. If over-excavation is to be performed, then these parameters for subgrade
preparation are for the subgrade below the bottom of the specified over-excavation
depth.
If surfaces to receive fill expose loose, wet, soft or otherwise deleterious material,
additional material should be excavated, or other measures taken to establish a firm
platform for filling. The surfaces to receive fill must be effectively stable prior to
placement of fill.
GROUND’s experience within the project area suggests the frost depth to be
approximately 3 feet below ground surface.
Fill Placement Fill materials should be thoroughly mixed to achieve a uniform moisture
content, placed in uniform lifts not exceeding 8 inches in loose thickness, and properly
compacted.
Soils that classify as GP, GW, GM, GC, SP, SW, SM, or SC in accordance with the
USCS classification system (granular materials) should be compacted to 95 or more
percent of the maximum modified Proctor dry density at moisture contents within 2
percent of optimum moisture content as determined by ASTM D1557.
Soils that classify as ML or CL should be compacted to 95 or more percent of the
maximum standard Proctor density at moisture contents within 2 percent of the optimum
moisture content as determined by ASTM D698. Soils that classify as MH or CH fine
grained soils should be avoided for use under structures, flatwork, or pavements.
GROUND Engineering should be contacted prior to using these materials for these
potential uses.
It may be necessary to rework the fill materials more than once by adjusting moisture
and replacing the materials, in order to achieve the recommended compaction and
moisture criteria.
No fill materials should be placed, worked, or rolled while they are frozen, thawing, or
during poor/inclement weather conditions.
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 23 of 46
Care should be taken with regard to achieving and maintaining proper moisture contents
during placement and compaction. Materials that are not properly moisture conditioned
may exhibit significant pumping, rutting, and deflection at moisture contents near
optimum and above. The contractor should be prepared to handle soils of this type,
including the use of chemical stabilization, if necessary.
Compaction areas should be kept separate, and no lift should be covered by another
until relative compaction and moisture content within the suggested ranges are obtained.
Use of Squeegee Relatively uniformly graded fine gravel or coarse sand, i.e.,
“squeegee,” or similar materials commonly are proposed for backfilling foundation
excavations, utility trenches (excluding approved pipe bedding), and other areas where
employing compaction equipment is difficult. In general, GROUND does not suggest
this procedure for the following reasons:
Although commonly considered “self-compacting,” uniformly graded granular materials
require densification after placement, typically by vibration. The equipment to densify
these materials is not available on many job-sites.
Even when properly densified, granular materials are permeable and allow water to
reach and collect in the lower portions of the excavations backfilled with those materials.
This leads to wetting of the underlying soils and resultant potential loss of bearing
support as well as increased local heave or settlement.
It is GROUND’s opinion that wherever possible, excavations be backfilled with approved,
on-site soils placed as properly compacted fill. Where this is not feasible, use of
“Controlled Low Strength Material” (CLSM), i.e., a lean, sand-cement slurry (“flowable
fill”) or a similar material for backfilling should be considered.
Where “squeegee” or similar materials are proposed for use by the contractor, the
design team should be notified by means of a Request for Information (RFI), so that the
proposed use can be considered on a case-by-case basis. “Squeegee” can be used
where deemed acceptable by the project documents.
Settlements Settlements will occur in filled ground, typically on the order of 1 to 2
percent of the fill depth. For a 6-foot fill, for example, this corresponds to a settlement of
about 1 inch. If fill placement is performed properly and is tightly controlled, in
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 24 of 46
GROUND’s experience the majority (on the order of 60 to 80 percent) of that settlement
will typically take place during earthwork construction, provided the contractor achieves
the compaction levels herein. The remaining potential settlements likely will take several
months or longer to be realized, and may be exacerbated if these fills are subjected to
changes in moisture content.
Cut and Filled Slopes Permanent site slopes supported by on-site soils up to 10 feet in
height may be constructed no steeper than 3:1 (horizontal : vertical). Minor raveling or
surficial sloughing should be anticipated on slopes cut at this angle until vegetation is
well re-established. Surface drainage should be designed to direct water away from
slope faces.
EXCAVATION CONSIDERATIONS
Excavation Difficulty The test holes for the subsurface exploration were advanced to
the depths indicated on the test hole logs by means of a conventional truck-mounted drill
rig advancing 4-inch diameter continuous flight auger at 8-inch hollow stem auger
equipment. We anticipate no significant excavation difficulties in the majority of the site
with conventional heavy-duty excavation equipment in good working condition.
Temporary Excavations and Personnel Safety Excavations in which personnel will
be working must comply with all applicable OSHA Standards and Regulations,
particularly CFR 29 Part 1926, OSHA Standards-Excavations, adopted March 5, 1990.
The contractor’s “responsible person” should evaluate the soil exposed in the
excavations as part of the contractor’s safety procedures. GROUND has provided the
information in this report solely as a service to the Poudre School District and is not
assuming responsibility for construction site safety or the contractor’s activities.
The contractor should take care when making excavations not to compromise the
bearing or lateral support for any adjacent, existing improvements.
In general, temporary, un-shored excavation slopes up to 10 feet in height may be cut no
steeper than 1 1/2 : 1 (horizontal : vertical) in the on-site soils in the absence of seepage.
Some surface sloughing may occur on the slope faces at these angles. Should site
constraints prohibit the use of the recommended slope angle, temporary shoring should
be used. GROUND can be retained to perform shoring design upon request.
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 25 of 46
Groundwater and Surface Water Groundwater was observed as at depths ranging
from 8.5 to 16 feet below existing grades at the time of drilling and as shallowly as 6.5
feet at the time of the preliminary exploration performed at this site. Therefore, wet soils,
seepage or groundwater could be encountered as shallow as about 5 feet seasonally.
If seepage or groundwater is encountered in shallow project excavations, a geotechnical
engineer should evaluate the conditions and provided additional direction, as
appropriate.
Good surface drainage should be provided around temporary excavation slopes to direct
surface runoff away from the slope faces. A properly designed drainage swale should
be provided at the top of the excavations. In no case should water be allowed to pond at
the site. Slopes should also be protected against erosion. Erosion along the slopes will
result in sloughing and could lead to a slope failure.
EXTERIOR FLATWORK
Proper design, drainage, construction and maintenance of the areas between individual
buildings and parking/driveway areas are critical to the satisfactory performance of the
project. Sidewalks, entranceway slabs and roofs, fountains, raised planters and other
highly visible improvements commonly are installed within these zones, and distress in
or near these improvements is common. Commonly, soil preparation in these areas
receives little attention because they fall between the building and pavement (which are
typically built with heavy equipment). Subsequent landscaping and hardscape
installation often is performed by multiple sub-contractors with light or hand equipment,
and over-excavation / soil processing is not performed. Therefore, GROUND
recommends that the contractor take particular care with regard to proper subgrade
preparation around the structure exteriors.
Similar to slab-on-grade floors, exterior flatwork and other hardscaping placed on the
soils encountered on-site may experience post-construction movements due to volume
change of the subsurface soils. Both vertical and lateral soil movements can be
anticipated as the soils experience volume change as their moisture contents vary.
Distress to rigid hardscaping likely will result. The measures outlined below will help to
reduce damages to these improvements.
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 26 of 46
Provided the owner understands the risks identified above, we believe that subgrade
under exterior flatwork and other hardscaping should be excavated and/or scarified to a
depth of at least 12 inches. The excavated soil should be replaced as properly
moisture-conditioned and compacted fill as recommended in the Project Earthwork
section of this report. Prior to placement of flatwork, a proof roll should be performed to
identify areas that exhibit instability and deflection. The soils in these areas should be
removed and replaced with properly compacted fill or stabilized.
Flatwork should be provided with effective control joints. Increasing the frequency of
joints may improve performance. ACI recommendations should be followed regarding
construction and/or control joints.
Exterior flatwork in contact with brick, rock facades, or any other element of the building
can cause damage to the structure if the flatwork experiences movements. In no case
should exterior flatwork extend to under any portion of the building where there is less
than 3 inches of vertical clearance between the flatwork and any element of the building.
As expansive soils heave is realized at the site over time, flatwork may need to be
removed and reconstructed to prevent distress to exterior building finishes, etc. The
need or frequency of reconstruction can be reduced by constructing an initial gap
between flatwork and building elements greater than 3 inches.
Effective drainage should be maintained after completion of the project, and re-
established as necessary. In no case should water be allowed to pond on or near any of
the site improvements. Where water is allowed to pond, a reduction in performance
should be anticipated. The owner should understand that anticipated maintenance likely
will include removal and replacement of flatwork panels, reaches of curb and/or other
project elements to re-establish effective surface drainage.
Concrete Scaling Climatic conditions in the project area including relatively low
humidity, large temperature changes and repeated freeze – thaw cycles, make it likely
that project sidewalks and other exterior concrete will experience surficial scaling or
spalling. The likelihood of concrete scaling can be increased by poor workmanship
during construction, such as ‘over-finishing’ the surfaces. In addition, the use of de-icing
salts on exterior concrete flatwork, particularly during the first winter after construction,
will increase the likelihood of scaling. Even use of de-icing salts on nearby roadways,
from where vehicle traffic can transfer them to newly placed concrete, can be sufficient
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 27 of 46
to induce scaling. Typical quality control / quality assurance tests that are performed
during construction for concrete strength, air content, etc., do not provide information
with regard to the properties and conditions that give rise to scaling.
We understand that some municipalities require removal and replacement of concrete
that exhibits scaling, even if the material was within specification and placed correctly.
The contractor should be aware of the local requirements and be prepared to take
measures to reduce the potential for scaling and/or replace concrete that scales.
In GROUND’s experience, the measures below can be beneficial for reducing the
likelihood of concrete scaling. Which measures are implemented may depend on the
project schedule and other factors. It must be understood, however, that because of the
other factors involved, including weather conditions and workmanship, surface damage
to concrete can develop even where all of these measures were followed. Also, the mix
design criteria should be coordinated with other project requirements including the
criteria for sulfate resistance presented in the Water-Soluble Sulfates section of this
report.
1) Maintaining a maximum water/cement ratio of 0.45 by weight for exterior
concrete mixes.
2) Include Type F fly ash in exterior concrete mixes as 20 percent of the
cementitious material.
3) Specify a minimum, 28-day, compressive strength of 4,500 psi for all exterior
concrete.
4) Include ‘fibermesh’ in the concrete mix may be beneficial for reducing surficial
scaling.
5) Cure the concrete effectively at uniform temperature and humidity. This
commonly will require fogging, blanketing and/or tenting, depending on the
weather conditions. As long as 3 to 4 weeks of curing may be required, and
possibly more.
6) Avoid placement of concrete during cold weather so that it is exposed to freeze-
thaw cycling before it is fully cured.
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 28 of 46
7) Avoid the use of de-icing salts on given reaches of flatwork through the first
winter after construction.
We understand that commonly it may not be practical to implement some of these
measures for reducing scaling due to safety considerations, project scheduling, etc. In
such cases, additional costs for flatwork maintenance or reconstruction should be
incorporated into project budgets.
Frost and Ice Considerations Nearly all soils other than relatively coarse, clean,
granular materials are susceptible to loss of density if allowed to become saturated and
exposed to freezing temperatures and repeated freeze – thaw cycling. The formation of
ice in the underlying soils can result in heaving of pavements, flatwork and other
hardscaping (“ice jacking”) in sustained cold weather up to 2 inches or more – in
additional to any movements from expansive soils heave. Ice jacking can develop
relatively rapidly. A portion of this movement typically is recovered when the soils thaw,
but due to loss of soil density, some degree of displacement will remain. This can result
even where the subgrade soils were prepared properly.
Where hardscape movements are a design concern, e.g., at doorways, replacement of
the subgrade soils with 3 or more feet of clean, coarse sand or gravel should be
considered or supporting the element on foundations similar to the building and
spanning over a void. A detailed discussion in this regard can be provided upon
request. It should be noted that where such open graded granular soils are placed,
water can infiltrate and accumulate in the subsurface relatively easily, which can lead to
increased settlement or heave from factors unrelated to ice formation. Therefore, where
a section of open graded granular soils are placed, a local underdrain system should be
provided to discharge collected water. GROUND will be available to discuss these
concerns upon request.
UTILITY PIPE INSTALLATION AND BACKFILLING
The parameters and opinions below are based on GROUND’s evaluation of the local,
geotechnical conditions. Where our parameters or opinions differ from applicable
municipal or agency standards for public utilities, the latter should be considered to take
precedence.
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 29 of 46
Pipe Support The bearing capacity of the site soils appeared adequate, in general, for
support of anticipated water lines. The pipe + water are less dense than the soils which
will be displaced for installation. Therefore, GROUND anticipates no significant pipe
settlements in these materials where properly bedded.
Excavation bottoms may expose soft, loose or otherwise deleterious materials, including
debris. Firm materials may be disturbed by the excavation process. All such unsuitable
materials should be excavated and replaced with properly compacted fill. Areas allowed
to pond water will require excavation and replacement with properly compacted fill. The
contractor should take particular care to ensure adequate support near pipe joints which
are less tolerant of extensional strains.
Where thrust blocks are needed, they may be designed utilizing the values provided in
the Lateral Loads section of this report.
Trench Backfilling Some settlement of compacted soil trench backfill materials should
be anticipated, even where all the backfill is placed and compacted correctly. Typical
settlements are on the order of 1 to 2 percent of fill thickness. However, the need to
compact to the lowest portion of the backfill must be balanced against the need to
protect the pipe from damage from the compaction process. Some thickness of backfill
may need to be placed at compaction levels lower than specified (or smaller compaction
equipment used together with thinner lifts) to avoid damaging the pipe. Protecting the
pipe in this manner can result in somewhat greater surface settlements. Therefore,
although other alternatives may be available, the following options are presented for
consideration:
Controlled Low Strength Material: Because of these limitations, we suggest backfilling
the entire depth of the trench (both bedding and common backfill zones) with “controlled
low strength material” (CLSM), i.e., a lean, sand-cement slurry, “flowable fill,” or similar
material along all trench alignment reaches with low tolerances for surface settlements.
We suggest that CLSM used as pipe bedding and trench backfill exhibit a 28-day
unconfined compressive strength between 50 to 150 psi so that re-excavation is not
unusually difficult.
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 30 of 46
Placement of the CLSM in several lifts or other measures likely will be necessary to
avoid ‘floating’ the pipe. Measures also should be taken to maintain pipe alignment
during CLSM placement.
Compacted Soil Backfilling: Where compacted soil backfilling is employed, using the
site soils or similar materials as backfill, the risk of backfill settlements entailed in the
selection of this higher risk alternative must be anticipated and accepted by the
Client/Owner.
We anticipate that the on-site soils excavated from trenches will be suitable, in general,
for use as common trench backfill within the above-described limitations. Backfill soils
should be free of vegetation, organic debris and other deleterious materials. Fragments
of rock, cobbles, and inert construction debris (e.g., concrete or asphalt) coarser than 3
inches in maximum dimension should not be incorporated into trench backfills.
If it is necessary to import material for use as backfill, the imported soils should conform
to the characteristics set forth in the Project Earthworks section of this report.
Representative samples of the materials proposed for import should be tested and
approved prior to transport to the site.
Soils placed for compaction as trench backfill should be conditioned to a relatively
uniform moisture content, placed and compacted in accordance with the Project
Earthwork section of this report.
Pipe Bedding Pipe bedding materials, placement and compaction should meet the
specifications of the pipe manufacturer and applicable municipal standards. Bedding
should be brought up uniformly on both sides of the pipe to reduce differential loadings.
As discussed above, we suggest the use of CLSM or similar material in lieu of granular
bedding and compacted soil backfill where the tolerance for surface settlement is low.
(Placement of CLSM as bedding to at least 12 inches above the pipe can protect the
pipe and assist construction of a well-compacted conventional backfill although possibly
at an increased cost relative to the use of conventional bedding.)
If a granular bedding material is specified, it is our opinion that with regard to potential
migration of fines into the pipe bedding, design and installation follow ASTM D2321. If
the granular bedding does not meet filter criteria for the enclosing soils, then non-woven
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 31 of 46
filter fabric (e.g., Mirafi® 140N, or the equivalent) should be placed around the bedding to
reduce migration of fines into the bedding which can result in severe, local surface
settlements. Where this protection is not provided, settlements can develop/continue
several months or years after completion of the project. In addition, clay or concrete cut-
off walls should be installed to interrupt the granular bedding section to reduce the rates
and volumes of water transmitted along the sewer alignment which can contribute to
migration of fines.
If granular bedding is specified, some volume of native materials may be suitable for that
use. Materials proposed for use as pipe bedding should be approved prior to use.
Imported materials should be approved prior to transport to the site.
SURFACE DRAINAGE
The site soils are relatively stable with regard to moisture content – volume relationships
at their existing moisture contents. Other than the anticipated, post-placement
settlement of fills, post-construction soil movement will result primarily from the
introduction of water into the soil underlying the proposed structure, hardscaping, and
pavements. Based on the site surface and subsurface conditions encountered in this
study, we do not anticipate a rise in the local water table sufficient to approach grade
beam or floor elevations. Therefore, wetting of the site soils likely will result from
infiltrating surface waters (precipitation, irrigation, etc.), and water flowing along
constructed pathways such as bedding in utility pipe trenches.
The following drainage measures should be incorporated as part of project design and
during construction. The facility should be observed periodically to evaluate the surface
drainage and identify areas where drainage is ineffective. Routine maintenance of site
drainage should be undertaken throughout the design life of the project. If these
measures are not implemented and maintained effectively, the movement estimates
provided in this report could be exceeded.
1) Wetting or drying of the foundation excavations and underslab areas should be
avoided during and after construction as well as throughout the improvements’
design life. Permitting increases/variations in moisture to the adjacent or
supporting soils may result in a decrease in bearing capacity and an increase in
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 32 of 46
volume change of the underlying soils, and increased total and/or differential
movements.
2) Positive surface drainage measures should be provided and maintained to
reduce water infiltration into foundation soils.
The ground surface surrounding the exterior of each building should be sloped to
drain away from the foundation in all directions. A minimum slope of 12 inches in
the first 10 feet should be incorporated in the areas not covered with pavement or
concrete slabs, or a minimum 2 percent in the first 10 feet in the areas covered
with pavement or concrete slabs to comply with ADA requirements. Increasing
slopes to 3 percent where possible will reduce the risks associated with moisture
infiltration.
In no case should water be allowed to pond near or adjacent to foundation
elements, hardscaping, utility trench alignments, etc.
3) Drainage should be established and maintained to direct water away from
sidewalks and other hardscaping as well as utility trench alignments. Where the
ground surface does not convey water away readily, additional post-construction
movements and distress should be anticipated.
4) In GROUND’s experience, it is common during construction that in areas of
partially completed paving or hardscaping, bare soil behind curbs and gutters,
and utility trenches, water is allowed to pond after rain or snow-melt events.
Wetting of the subgrade can result in loss of subgrade support and increased
settlements / increased heave. By the time final grading has been completed,
significant volumes of water can already have entered the subgrade, leading to
subsequent distress and failures. The contractor should maintain effective site
drainage throughout construction so that water is directed into appropriate
drainage structures.
5) On some sites, slopes may descend toward buildings locally. Such slopes can
be created during grading even on comparatively flat sites. In such cases, even
where the slopes as described above are implemented effectively, water may
flow toward and beneath a structure or other site improvements with resultant
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 33 of 46
additional, post-construction movements. Where the final site configuration
includes graded or retained slopes descending toward the improvements,
surface drainage swales and/or interceptor drains should be installed between
the improvements and the slope.
In addition, where site slopes, including retained slopes, descend toward a
building, and the toe-of-slope (-wall) is less than 3 times the total slope (wall)
height from the building, then an interceptor drain should be installed between
the building and the slope. Ideally, the interceptor drain should be installed at
least 10 feet from the building or along the axis of the swale between the building
and the toe-of-slope (-wall). Geotechnical parameters for an interceptor drain
system are provided in the Subsurface Drainage section of this report.
Where irrigation is applied on or above slopes, drainage structures commonly are
needed near the toe-of-slope to prevent on-going or recurrent wet conditions.
6) Roof downspouts and drains should discharge well beyond the perimeter of the
structure foundations (minimum 10 feet) and backfill zones and be provided with
positive conveyance off-site for collected waters.
7) Based on our experience with similar facilities, the project may include
landscaping/watering near site improvements. Irrigation water – both that
applied to landscaped areas and over-spray – is a significant cause of distress to
improvements. To reduce the potential for such distress, vegetation requiring
watering should be located 10 or more feet from building perimeters, flatwork, or
other improvements. Irrigation sprinkler heads should be deployed so that
applied water is not introduced near or into foundation/subgrade soils.
Landscape irrigation should be limited to the minimum quantities necessary to
sustain healthy plant growth.
8) Use of drip irrigation systems can be beneficial for reducing over-spray beyond
planters. Drip irrigation can also be beneficial for reducing the amounts of water
introduced to foundation/subgrade soils, but only if the total volumes of applied
water are controlled with regard to limiting that introduction. Controlling rates of
moisture increase beneath the foundations, floors, and other improvements
should take higher priority than minimizing landscape plant losses.
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 34 of 46
Where plantings are desired within 10 feet of a building, it is GROUND’s opinion
that the plants be placed in water-tight planters, constructed either in-ground or
above-grade, to reduce moisture infiltration in the surrounding subgrade soils.
Planters should be provided with positive drainage and landscape underdrains.
As an alternative involving a limited increase in risk, the use of water-tight
planters may be replaced by local shallow underdrains beneath the planter beds.
Colorado Geological Survey – Special Publication 43 provides additional
guidelines for landscaping and reducing the amount of water that infiltrates into
the ground.
GROUND understands many municipalities and or developments require
landscaping within 10 feet of building perimeters. Provided that positive,
effective surface drainage is initially implemented and maintained throughout the
life of the facility and the Owner understands and accepts the risks associated
with this requirement, vegetation that requires controlled minimal amounts of
irrigation may be located within 10 feet of the building perimeter.
9) Regular inspections should be made by facility representatives to make sure that
the landscape irrigation is functioning properly throughout operation and that
excess moisture is not applied.
10) Maintenance as described herein may include complete removal and
replacement of site improvements in order to maintain effective surface drainage.
11) Detention ponds commonly are incorporated into drainage design. When a
detention ponds fills, the rate of release of the water is controlled and water is
retained in the pond for a period of time. Where in-ground storm sewers direct
surface water to the pond, the granular pipe bedding also can direct shallow
groundwater or infiltrating surface water toward the pond. Thus, detention ponds
can become locations of enhanced and concentrated infiltration into the
subsurface, leading to wetting of foundation soils in the vicinity with consequent
heave or settlement. Therefore, unless the pond is clearly down-gradient from
the proposed buildings and other structures that would be adversely affected by
wetting of the subgrade soils, including off-site improvements, GROUND
recommends that the detention pond should be provided with an effective, low
permeability liner. In addition, cut-off walls and/or drainage provisions should be
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 35 of 46
provided for the bedding materials surrounding storm sewer lines flowing to the
pond.
SUBSURFACE DRAINAGE
Building Perimeter Foundation Drains and Laterals As a component of project civil
design, properly functioning, subsurface drain systems (underdrains) can be beneficial
for collecting and discharging subsurface waters where the soil is saturated. In
GROUND’s opinion the proposed building does not specifically need to be protected with
a perimeter underdrain system in the absence of below-grade / basement levels.
However, if a below-grade or partially below-grade level is added to the building, then a
local underdrain system should be included to protect that area. Damp-proofing should
be applied to the exteriors of below-grade elements. The provision of Tencate MiraFi®
G-Series backing (or comparable wall drain provisions) on the exteriors of (some) below-
grade elements may be appropriate, depending on the intended use.
Collected surface waters should not be routed into an underdrain.
Each underdrain system should be tested by the contractor after installation and after
placement and compaction of the overlying backfill to verify that the system functions
properly. Like other components of the structure, periodic maintenance of an underdrain
system after completion should be anticipated to keep it functioning as intended.
Geotechnical Parameters for Underdrain Design Where an underdrain system is
included in project drainage design, it should be designed in accordance with the
recommendations below. The actual underdrain layout, outlets, and locations should be
developed by a civil engineer.
1) An underdrain system for a building should consist of perforated, rigid, PVC
collection pipe at least 4 inches in diameter, non-perforated, rigid, PVC discharge
pipe at least 4 inches in diameter, free-draining gravel, and filter fabric, as well as
a waterproof membrane or drain board product.
2) The free-draining gravel should contain less than 5 percent passing the No. 200
Sieve and more than 50 percent retained on the No. 4 Sieve, and have a
maximum particle size of 2 inches.
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 36 of 46
Each collection pipe should be surrounded on the sides and top (only) with 6 or
more inches of free-draining gravel.
3) The gravel surrounding the collection pipe(s) should be wrapped with filter fabric
(Tencate MiraFi 140N® or the equivalent) to reduce the migration of fines into the
drain system.
4) The collection and discharge pipes should be 12 or more inches from grade
beam margin and 6 or more inches below the bottom of the grade beam
5) The underdrain system should be designed to discharge at least 10 gallons per
minute of collected water.
6) The high point(s) for the collection pipe flow lines should be below the foundation
or grade beam bearing elevation. Multiple high points can be beneficial to
reducing the depths to which the system would be installed.
Pipe gradients also should be designed to accommodate at least 1 inch of
differential movement after installation along a 50-foot run.
7) Underdrain ‘clean-outs’ should be provided at intervals of no more than 200 feet
to facilitate maintenance of the underdrains. Clean-outs also should be provided
at collection and discharge pipe elbows of 60 degrees or more.
8) The underdrain discharge pipes should be connected to one or more sumps from
which water can be removed by pumping, or to outlet(s) for gravity discharge.
We suggest that collected waters be discharged directly into the storm sewer
system, if possible.
PAVEMENT SECTIONS
A pavement section is a layered system designed to distribute concentrated traffic loads
to the subgrade. Performance of the pavement structure is directly related to the
physical properties of the subgrade soils and traffic loadings. The standard care of
practice in pavement design describes the flexible pavement section as a “20-year”
design pavement: however, most flexible pavements will not remain in satisfactory
condition without routine maintenance and rehabilitation procedures performed
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 37 of 46
throughout the life of the pavement. Pavement designs for the private pavements were
developed in general accordance with the design guidelines and procedures of the
American Association of State Highway and Transportation Officials (AASHTO). The
pavement designs for the public roadways (Prospect Road and County Road 5) were
developed in general accordance with the Larimer Count Urban Area Street Standards
(LCUASS).
Subgrade Materials Based on the results of our field exploration and laboratory testing,
the likely pavement subgrade materials vary from A-1-a to A-6 soil in accordance with
the American Association of State Highway and Transportation Officials (AASHTO)
classification system. These materials are anticipated to have elevated moisture content
and be unstable based on the existing condition of the pavement. These materials will
need to be stabilized prior to placing asphalt.
Laboratory results indicated an R-value of 36 for the materials obtained from the public
roadways adjacent to the project site. Due to the inclusion of some amounts of asphalt
and road base within the bulk sample utilized for testing, an R-Value of 20 was utilized
for design of the project pavements. An R-Value of 20 converts to a resilient modulus of
4,940 psi based on CDOT correlation tables. It is important to note that significant
decreases in soil support have been observed as the moisture content increases above
the optimum. Pavements that are not properly drained may experience a loss of the soil
support and subsequent reduction in pavement life.
Anticipated Traffic Based on our experience with similar projects and conversations
with the client equivalent 18-kip daily load application (EDLA) values of 5, 10, and 30
were assumed for the general parking lots, vehicle drive lanes, and heavy vehicle drive
paths/bus lanes, respectively. The EDLA values of 5, 10, and 30 were converted to
equivalent 18-kip single axle load (ESAL) values of 36,500; 73,000; and 219,000
respectively for a 20-year design life.
The Fort Collins Master Street Plan labels the portion of Prospect and County Road 5 as
4-lane Arterial Roadways. These roadways are currently constructed as 2-lay roadways
therefore, pavement designs for a 2-lane and 4-lane Arterial Roadway are provided
below. The EDLA values provided by LUCASS for a 2-lane and 4-lane arterial are 100
and 200 respectively. These EDLA values convert to 730,000 and 1,460,000 ESAL’s. If
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 38 of 46
anticipated traffic loadings differ significantly from these assumed values, GROUND
should be notified to re-evaluate the pavement thicknesses provided below.
Pavement Sections The soil resilient modulus and the ESAL values were used to
determine the required design structural number for the project pavements. The
required structural number was then used to develop the pavement sections. Pavement
designs were based on the DARWin™ computer program that solves the 1993 AASHTO
pavement design equations. A Reliability Level of 80 percent was utilized to develop the
private pavement sections, together with a Serviceability index loss of 2.5. An overall
standard of deviation of 0.44 also was used.
A structural coefficient of 0.44 was used for hot bituminous asphalt and 0.11 for
aggregate base course, respectively. The resultant minimum pavement sections that
should be used at the facility are tabulated below.
Minimum Private Pavement Sections
Location
Composite Asphalt
Section
Full Depth Asphalt
Section
Rigid Pavement
(inches Asphalt / inches
ABC)
(inches Asphalt)
(inches PCCP /
inches ABC)
Parking Areas 4.0 / 4 5.0 -
Light Vehicle Drive
Lanes
4.0 / 6 5.5 -
Heavy Vehicle /
Bus Lane
5.0 / 6 6.5 6.5 / 6
ABC = Aggregate Base Course, PCCP= Portland Cement Concrete Pavement
Minimum Public Pavement Sections
Location
Roadway
Classification
Composite Asphalt
Section
(inches Asphalt / inches
ABC)
Prospect Rd and
County Road 5
2-Lane Arterial 7.0 / 6.0
Prospect Rd and
County Road 5
4-Lane Arterial 7.5 / 8.0
ABC = Aggregate Base Course, PCCP= Portland Cement Concrete Pavement
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 39 of 46
Heavy traffic areas/routes serving the facility that impose high stress on the pavement
such as trash collection areas and trash truck turn arounds should be provided with rigid
pavements consisting of 6.5 or more inches of Portland cement concrete underlain
by at least 6 inches of Aggregate Base Course materials. (An equivalent flexible
section for these areas would not perform as well as the concrete section where heavy
vehicles are parked, stop suddenly, turn repeatedly, etc.)
Pavement Materials Asphalt pavement should consist of a bituminous plant mix
composed of a mixture of aggregate and bituminous material. Asphalt mixture(s) should
meet the requirements of a job-mix formula established by a qualified engineer and
applicable municipality design requirements.
Aggregate base material should meet the criteria of CDOT Class 5 or 6 Aggregate Base
Course. Base course should be placed in and compacted in accordance with the
standards in the Project Earthwork section of this report.
Concrete pavements should consist of a plant mix composed of a mixture of aggregate,
Portland cement and appropriate admixtures meeting the requirements of a job-mix
formula established by a qualified engineer and applicable municipality design
requirements. Concrete should have a minimum modulus of rupture of third point
loading of 650 psi. Normally, concrete with a 28-day compressive strength of 4,500 psi
should develop this modulus of rupture value. The concrete should be air-entrained with
approximately 6 percent air and should have a minimum cement content of 6 sacks per
cubic yard. Maximum allowable slump should be 4 inches for hand-placed concrete.
Machine-placed concrete may require a lower slump.
These concrete mix design criteria should be coordinated with other project
requirements including any criteria for sulfate resistance presented in the Water-Soluble
Sulfates section of this report. To reduce surficial spalling resulting from freeze-thaw
cycling, we suggest that pavement concrete meet the requirements of CDOT Class P
concrete. In addition, the use of de-icing salts on concrete pavements during the first
winter after construction will increase the likelihood of the development of scaling.
Placement of flatwork concrete during cold weather so that it is exposed to freeze-thaw
cycling before it is fully cured also increases its vulnerability to scaling. Concrete placing
during cold weather conditions should be blanketed or tented to allow full curing.
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 40 of 46
Depending on the weather conditions, this may result in 3 to 4 weeks of curing, and
possibly more.
Concrete pavements should contain sawed or formed joints. CDOT and various industry
groups provide guidelines for proper design and concrete construction and associated
jointing. In areas of repeated turning stresses the concrete pavement joints should be
fully tied and doweled. Example layouts for joints, as well as ties and dowels, that may
be applicable can be found in CDOT’s M standards, found at the CDOT website:
http://www.dot.state.co.us/DesignSupport/. PCA, ACI and ACPA publications also
provide useful guidance in these regards.
Subgrade Preparation Shortly before paving, the pavement subgrade should be
excavated and/or scarified to a minimum depth of 12 inches, moisture-conditioned and
properly re-compacted. Although subgrade preparation to a depth of 12 inches is typical
in the project area, pavement performance commonly can be improved by a greater
depth of moisture-density conditioning of the soils.
Based on samples taken from the test holes man-made fill exists onsite. Over-
excavation to greater depths may need to be performed on localized areas depending
on the conditions exposed during construction.
Subgrade preparation should extend the full width of the pavement. The subgrade for
sidewalks and other project hardscaping also should be prepared in the same manner
(moisture density treatment to a depth of 12-inches).
Criteria and standards for fill placement and compaction are provided in the Project
Earthwork section of this report. The contractor should be prepared either dry the
subgrade materials or moisten them, as needed, prior to compaction.
Where adequate drainage cannot be achieved or maintained, excavation and
replacement should be undertaken to a greater depth, in addition to the edge drains
discussed below.
Proof Rolling Immediately prior to paving, the subgrade should be proof rolled with a
heavily loaded, pneumatic tired vehicle. Areas that show excessive deflection during
proof rolling should be excavated and replaced and/or stabilized as discussed above.
Areas allowed to pond prior to paving will require significant re-working prior to proof-
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 41 of 46
rolling. Establishment of a firm paving platform (as indicated by proof rolling) is an
additional requirement beyond proper fill placement and compaction. It is possible for
soils to be compacted within the limits indicated in the Project Earthwork section of this
report and fail proof rolling, particularly in the upper range of specified moisture contents.
Temporary Fire Access Routes Commonly, construction sites are required by local fire
departments to provide temporary access for emergency response. It has been
GROUND’s experience these access drives are to provide support for trucks weighing
up to 90,000 pounds and are typically desired to be gravel/aggregate-surfaced.
Based on our experience, a temporary section consisting of at least 12 inches of
material meeting the requirements of CDOT Class 5 or Class 6 Aggregate Base Course
or at least 8 inches of CDOT Class 5 or Class 6 Aggregate Base Course over a layer of
stabilization geotextile/geofabric, such as Mirafi® RS380i or the equivalent, could be
utilized provided the Owner understands that this section is for temporary access during
construction only and is not a replacement or an equal alternate to the pavement
section(s) that were indicated previously. The aggregate base course placed for this
purpose should be compacted to at least 95 percent of the maximum modified Proctor
dry density. It should be noted that the aggregate base course sections indicated above
are not intended to support fire truck outriggers without cribbing or similar measures.
It should be understood that with any aggregate surface, shoving and displacement of
the granular materials should be expected during repetitive vehicular/equipment loading.
Therefore, regular maintenance should be implemented to ensure proper surface and
subsurface drainage, repair distressed/damaged areas, and re-establish grades.
Application of additional aggregate may be required in this regard. Additionally, the
ability of the aggregate temporary access drive to accommodate loads as indicated
above is directly related to the quality of the subgrade materials on which the aggregate
is placed, not only on the aggregate section. If water infiltrates these areas, additional
rutting and other distress, including a reduction in capacity, will result, requiring
additional maintenance.
Additional Considerations The collection and diversion of surface drainage away from
paved areas is extremely important to satisfactory performance of the pavements. The
subsurface and surface drainage systems should be carefully designed to ensure
removal of the water from paved areas and subgrade soils. Allowing surface waters to
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 42 of 46
pond on pavements will cause premature pavement deterioration. Where topography,
site constraints or other factors limit or preclude adequate surface drainage, pavements
should be provided with edge drains to reduce loss of subgrade support. The long-term
performance of the pavement also can be improved greatly by proper backfilling and
compaction behind curbs, gutters, and sidewalks so that ponding is not permitted and
water infiltration is reduced.
Landscape irrigation in planters adjacent to pavements and in “island” planters within
paved areas should be carefully controlled or differential heave and/or rutting of the
nearby pavements will result. Drip irrigation systems are recommended for such
planters to reduce over-spray and water infiltration beyond the planters. Enclosing the
soil in the planters with plastic liners and providing them with positive drainage also will
reduce differential moisture increases in the surrounding subgrade soils.
In our experience, infiltration from planters adjacent to pavements is a principal source of
moisture increase beneath those pavements. This wetting of the subgrade soils from
infiltrating irrigation commonly leads to loss of subgrade support for the pavement with
resultant accelerating distress, loss of pavement life and increased maintenance costs.
This is particularly the case in the later stages of project construction after landscaping
has been emplaced but heavy construction traffic has not ended. Heavy vehicle traffic
over wetted subgrade commonly results in rutting and pushing of flexible pavements,
and cracking of rigid pavements. Where the subgrade soils are expansive, wetting also
typically results in increased pavement heave. In relatively flat areas where design
drainage gradients necessarily are small, subgrade settlement or heave can obstruct
proper drainage and yield increased infiltration, exaggerated distress, etc. (These
considerations apply to project flatwork, as well.)
Also, GROUND’s experience indicates that longitudinal cracking is common in asphalt-
pavements generally parallel to the interface between the asphalt and concrete
structures such as curbs, gutters or drain pans. This of this type is likely to occur even
where the subgrade has been prepared properly and the asphalt has been compacted
properly.
The anticipated traffic loading does not include excess loading conditions imposed by
heavy construction vehicles. Consequently, heavily loaded concrete, lumber, and
building material trucks can have a detrimental effect on the pavement. GROUND
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 43 of 46
recommends that an effective program of regular maintenance be developed and
implemented to seal cracks, repair distressed areas, and perform thin overlays
throughout the life of the pavements.
Most pavements will not remain in satisfactory condition and achieve their “design lives”
without regular maintenance and rehabilitation procedures performed throughout the life
of the pavement. Maintenance and rehabilitation measures preserve, rather than
improve, the structural capacity of the pavement structure. Therefore, GROUND
recommends that an effective program of regular maintenance be developed and
implemented to seal cracks, repair distressed areas, and perform thin overlays
throughout the lives of the pavements. The greatest benefit of pavement overlaying will
be achieved by overlaying sound pavements that exhibit little or no distress.
Crack sealing should be performed at least annually and a fog seal/chip seal program
should be performed on the pavements every 3 to 4 years. After approximately 8 to 10
years after construction, patching, additional crack sealing, and asphalt overlay may be
required. Prior to overlays, it is important that all cracks be sealed with a flexible,
rubberized crack sealant in order to reduce the potential for propagation of the crack
through the overlay. If actual traffic loadings exceed the values used for development of
the pavement sections, however, pavement maintenance measures will be needed on
an accelerated schedule.
CLOSURE AND LIMITATIONS
Geotechnical Review The author of this report or a GROUND principal should be
retained to review project plans and specifications to evaluate whether they comply with
the intent of the measures discussed in this report. The review should be requested in
writing. GROUND should be provided preliminary grading plans, building layout, and
foundation elevation details as soon as practical so that the criteria in this document can
be verified and any required adjustments be addressed and documented.
The geotechnical conclusions and parameters presented in this report are contingent
upon observation and testing of project earthwork by representatives of GROUND. If
another geotechnical consultant is selected to provide materials testing, then that
consultant must assume all responsibility for the geotechnical aspects of the project by
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 44 of 46
concurring in writing with the parameters in this report, or by providing alternative
parameters.
Materials Testing Poudre School District should consider retaining a geotechnical
engineer to perform materials testing during construction. The performance of such
testing or lack thereof, however, in no way alleviates the burden of the contractor or
subcontractor from constructing in a manner that conforms to applicable project
documents and industry standards. The contractor or pertinent subcontractor is
ultimately responsible for managing the quality of his work; furthermore, testing by the
geotechnical engineer does not preclude the contractor from obtaining or providing
whatever services that he deems necessary to complete the project in accordance with
applicable documents.
Limitations This report has been prepared for the Poudre School District as it pertains
to design of the proposed New Prospect 6-12 School as described herein. It should not
be assumed to contain sufficient information for other parties or other purposes. The
Client has agreed to the terms, conditions, and liability limitations outlined in our
agreement between Poudre School District and GROUND. Reliance upon our report is
not granted to any other potential owner, contractor, or lender. Requests for third-party
reliance should be directed to GROUND in writing; granting reliance by GROUND is not
guaranteed.
In addition, GROUND has assumed that project construction will commence by
Spring/Summer of 2020. Any changes in project plans or schedule should be brought to
the attention of a geotechnical engineer, in order that the geotechnical conclusions in
this report may be re-evaluated and, as necessary, modified.
The geotechnical conclusions in this report were based on subsurface information from a
limited number of exploration points, as shown in Figure 1, as well as the means and
methods described herein. Subsurface conditions were interpolated between and
extrapolated beyond these locations. It is not possible to guarantee the subsurface
conditions are as indicated in this report. Actual conditions exposed during construction
may differ from those encountered during site exploration. In addition, a contractor who
obtains information from this report for development of his scope of work or cost
estimates does so solely at his own risk and may find the geotechnical information in this
report to be inadequate for his purposes or find the geotechnical conditions described
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 45 of 46
herein to be at variance with his experience in the greater project area. The contractor
should obtain the additional geotechnical information that is necessary to develop his
workscope and cost estimates with sufficient precision. This includes, but is not limited
to, information regarding excavation conditions, earth material usage, current depths to
groundwater, etc.
If during construction, surface, soil, bedrock, or groundwater conditions appear to be at
variance with those described herein, a geotechnical engineer should be retained at
once, so that our conclusions for this site may be re-evaluated in a timely manner and
dependent aspects of project design can be modified, as necessary.
The materials present on-site are stable at their natural moisture content, but may
change volume or lose bearing capacity or stability with changes in moisture content.
Performance of the proposed structure and pavement will depend on implementation of
the conclusions and information in this report and on proper maintenance after
construction is completed. Because water is a significant cause of volume change in
soils and rock, allowing moisture infiltration may result in movements, some of which will
exceed estimates provided herein and should therefore be expected by the Poudre
School District.
ALL DEVELOPMENT CONTAINS INHERENT RISKS. It is important that ALL aspects
of this report, as well as the estimated performance (and limitations with any such
estimations) of proposed improvements are understood by Poudre School District.
Utilizing the geotechnical parameters and measures herein for planning, design, and/or
construction constitutes understanding and acceptance of the conclusions with regard to
risk and other information provided herein, associated improvement performance, as
well as the limitations inherent within such estimates. Ensuring correct interpretation of
the contents of this report by others is not the responsibility of GROUND. If any
information referred to herein is not well understood, it is imperative that the Poudre
School District contact the author or a GROUND principal immediately. We will be
available to meet to discuss the risks and remedial approaches presented in this report,
as well as other potential approaches, upon request.
Current applicable codes may contain criteria regarding performance of structures
and/or site improvements which may differ from those provided herein. Our office should
be contacted regarding any apparent disparity.
Poudre School District
New Prospect 6-12 School
Fort Collins, Colorado
Job No. 19-0013 Ground Engineering Consultants, Inc. Page 46 of 46
GROUND makes no warranties, either expressed or implied, as to the professional data,
opinions or conclusions contained herein. Because of numerous considerations that are
beyond GROUND’s control, the economic or technical performance of the project cannot
be guaranteed in any respect.
This document, together with the concepts and conclusions presented herein, as an
instrument of service, is intended only for the specific purpose and client for which it was
prepared. Re-use of, or improper reliance on this document without written authorization
and adaption by GROUND Engineering Consultants, Inc., shall be without liability to
GROUND Engineering Consultants, Inc.
GROUND appreciates the opportunity to complete this portion of the project.
Sincerely,
GROUND Engineering Consultants, Inc.
Kelsey Van Bemmel, P.E. Reviewed by Brian H. Reck, P.G., C.E.G., P.E.
Indicates test hole number and approximate location. (Not to Scale)
LOCATION OF TEST HOLES
CADFILE NAME: 0013SITE.DWG
JOB NO.: 19-0013 FIGURE: 1
1
GOOGLE EARTH AERIAL IMAGE (DATE UNKNOWN)
D-03
D-04
D-01
E Prospect Rd
D-05
D-02
C-03
E-01
A-03
B-05
C-04
E-02
A-04
B-06
C-05
B-01
A-05
C-06
B-02
A-06
S Co Rd 5
C-01
C-07
B-03
A-07
C-08
B-04
A-08
C-09
A-01
A-09
C-02
C-10
A-02
A-10
55
60
65
70
75
80
85
90
95
100
105
55
60
65
70
75
80
85
90
95
100
105
- 25/12
- 14/12
- 22/12
- 20/12
- 14/12
- 11/12
- 12/12
- 30/12
- 15/12
- 10/12
- 14/12
- 4/12
- 6/12
- 6/12
- 7/12
- 20/12
- 6/12
- 11/12
- 19/12
- 20/12
- 10/12
- 12/12
- 8/12
- 7/12
- 13/12
- 16/12
- 11/12
- 17/12
- 9/12
- 18/12
- 16/12
- 15/12
- 12/12
- 17/12
- 10/12
- 14/12
- 16/12
- 22/12
55
60
65
70
75
80
85
90
95
100
105
55
60
65
70
75
80
85
90
95
100
105
- 5/12
- 9-12-15
- 11-10-14
- 1-2-3
- 9/12
- 12-14-18
- 6-3-2
- 2-2-1
- 5-4-8
- 1-2-5
- 15/12
- 19/12
- 5/12
- 3-4-6
- 12/12
- 26/12
- 4-5-4
- 4-4-5
- 12/12
- 13/12
- 13/12
- 8/12
- 13/12
- 20/12
SUBSURFACE DIAGRAM
Elevation (ft)
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
B-01
ELEV. 100
B-02
ELEV. 100
B-03
ELEV. 100
B-04
ELEV. 100
84
86
88
90
92
94
96
98
100
102
84
86
88
90
92
94
96
98
100
102
- 10/12
- 24/12
- 5/12
- 7/12
- 7/12
- 28/12
- 12/12
- 29/12
- 13/12
- 4/12
- 36/12
- 4/12
- 25/12
- 10/12
- 15/12
- 4/12
- 38/12
- 7/12
- 10/12
- 13/12
- 18/12
SUBSURFACE DIAGRAM
Elevation (ft)
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
C-01
ELEV. 100
C-02
ELEV. 100
C-03
ELEV. 100
C-04
ELEV. 100
C-05
ELEV. 100
C-06
ELEV. 100
C-07
88
89
90
91
92
93
94
95
96
97
98
99
100
101
88
89
90
91
92
93
94
95
96
97
98
99
100
101
- 23/12
- 31/12
- 5/12
- 6/12
- 22/12
SUBSURFACE DIAGRAM
Elevation (ft)
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
E-01
ELEV. 100
E-02
ELEV. 100
89
90
91
92
93
94
95
96
97
98
99
100
101
89
90
91
92
93
94
95
96
97
98
99
100
101
- 32/12
- 19/12
- 18/12
- 6/12
-
- 14/12
- 23/12
SUBSURFACE DIAGRAM
Elevation (ft)
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
P-01
ELEV. 100
P-02
ELEV. 100
P-04
ELEV. 100
P-05
ELEV. 100
NOTES:
1. Test holes were drilled on 5/6/2019, 5/7/2019, 5/13/2019, 5/14/2019
and 5/29/2019 with 4-inch, 5-inch and 8-inch Diameter Continuous Flight
Auger.
2. Locations of the test holes were measured approximately by pacing from
features shown on the site plan provided.
3. Elevations of the test holes were not measured and the logs of the test
holes are drawn to depth.
4. The test hole locations and elevations should be considered accurate
only to the degree implied by the method used.
5. The lines between materials shown on the test hole logs represent the
approximate boundaries between material types and the transitions may be
gradual.
6. Groundwater level readings shown on the logs were made at the time
and under the conditions indicated. Fluctuations in the water level may
occur with time.
7. The material descriptions on these logs are for general classification
purposes only. See full text of this report for descriptions of the site
materials & related information.
8. All test holes were immediately backfilled upon completion of drilling,
unless otherwise specified in this report.
CLIENT: Poudre School District PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
LITHOLOGIC SYMBOLS SAMPLER SYMBOLS
KEY TO SYMBOLS
Water Level at End of Drilling, or as Shown
Water Level After 24 Hours, or as Shown
NV
NP
No Value
Non Plastic
ABBREVIATIONS
California Sampler
23 / 12 Drive sample blow count indicates 23 blows of a
140 pound hammer falling 30 inches were required to drive
the sampler 12 inches.
Small Disturbed Sample
Split Spoon
ASPHALT
ROAD BASE
TOPSOIL
SAND AND CLAY
SAND AND GRAVEL
Water Level at Time of Drilling, or as Shown
NOTE: See Detailed Logs for Material descriptions.
JOB NO.: 19-0013
Client: Poudre School District
Project No.: 19-0013
Method Hammer
Method B Manual
127.0 8.0 - -
Oversize Sieve: 3/8 in
Coarse Fraction (%): -
Fine Fraction (%): -
Coarse Specific Gravity: -
Coarse Absorption (%): -
Fine Specific Gravity: 2.65 Estimated
Location: D-1 to D- 5, 1 to 5', Bulk Classification: SC/A-2-4 (0) < No. 200 (%): 30.0
Description: Light brown, clayey SAND Liquid Limit: 27
Plasticity Index: 9
5/2019 Figure #8
Results apply only to the specific items and locations referenced and at the time of testing. This report should not be reproduced, except in full, without the written permission of
GROUND Engineering
Consultants, Inc.
New Prospect 6-12 School
Standard Proctor (ASTM D698)
Preparation
Moist
Maximum Dry
Density (pcf)
Optimum
Moisture
(%)
Oversize Corrected
Maximum Dry
Density (pcf)
Optimum
Moisture
(%)
80
85
90
95
100
105
110
115
120
125
130
135
140
0 5 10 15 20 25 30 35
Dry Density (pcf)
Moisture (%)
www.groundeng.com
Englewood, Commerce City, Loveland, Granby, Gypsum
Client: Poudre School District
Project No.: 19-0013
A-1 4 0.05 8.3 -69.0 Positive 10790 SC-SM A-4 (0)
A-8 4 < 0.01 8.5 -95.0 Positive 2287 SC A-6 (5)
B-5 3 < 0.01 - - - - SW A-1-a(0
C-1 3 0.01 - - - - SM A-2-4(0)
*Performed by eAnalytics Laboratory.
New Prospect 6-12 School
TABLE 2: SUMMARY OF SOIL CORROSION TEST RESULTS
AASHTO
Equivalent
Classification
(Group Index)
Water
Soluble
Sulfates
(%)
Sulfide
Reactivity*
pH
Redox
Potential
(mV)
Resistivity
(ohm-cm)
USCS
Equivalent
Classification
Test Sample Description
Hole
No.
Depth
(feet)
Sample Location
Silty Clayey SAND
Clayey SAND
Silty SAND
Well graded SAND
Sample Location Natural Natural Percent Atterberg Limits Percent USCS AASHTO
Test Moisture Dry Passing Liquid Plasticity Swell Classifi- Classifi- Soil or
Hole Depth Content Density Gravel Sand No. 200 Limit Index (Surcharge cation cation Bedrock Type
No. (feet) (%) (pcf) (%) (%) Sieve Pressure) (GI)
A-1 4 9.9 113.0 47 24 6 SC-SM A-4 (0) Silty Clayey SAND
A-2 9 15.2 106.5 56 34 20 SC-CL A-6(8) SAND and CLAY
A-3 10 3.2 118.1 14 - NP (SM) A-2-4(0) Silty SAND
A-3 15 20.9 103.5 19 - NP (SM) A-2-4(0) Silty SAND
A-4 4 1.0 SD 39 57 4 - NP (SW) A-1-a(0) Well graded SAND
A-4 19 24.0 101.9 83 29 12 (CL)s A-6(8) CLAY with sand
A-5 8 25.2 96.8 89 14 34 (CL) A-6(17) CLAY
A-5 13 12.7 114.5 13 - NP (SM) A-2-4(0) Silty SAND
A-6 4 2.1 SD 39 55 6 - NP (SW-SM) A-1-a(0) Well graded silty SAND and GRAVEL
A-6 34 15.9 104.8 0 97 3 - NP (SP) A-1-b(0) Poorly graded SAND
A-7 13 7.7 110.0 25 68 7 - NP (SW-SM) A-1-a(0) Well graded silty SAND
A-7 23 23.6 SD 85 38 21 A-6(17) (CL)s CLAY with sand
A-8 4 14.7 109.8 48 34 18 SC A-6 (5) Clayey SAND
A-9 13 9.3 123.6 38 - NP (SM) A-4(0) Silty Sand
A-10 4 5.6 117.1 16 - NP (SM) A-2-4(0) Silty Sand
B-1 3 6.2 120.9 28 22 6 (SC-SM) A-2-4(0) Clayey Silty SAND
B-2 4 12.8 112.7 55 21 3 s(ML) A-4(0) Sandy SILT
B-3 10 5.3 SD 4 - NP (SP) A-2-4(0) Poorly Graded SAND
B-4 7 1.6 SD 14 71 15 - NP (SM) A-1-b(0) Silty SAND with gravel
Gradation
SUMMARY OF LABORATORY TEST RESULTS
TABLE 1
Sample Location Natural Natural Percent Atterberg Limits Percent USCS AASHTO
Test Moisture Dry Passing Liquid Plasticity Swell Classifi- Classifi- Soil or
Hole Depth Content Density Gravel Sand No. 200 Limit Index (Surcharge cation cation Bedrock Type
No. (feet) (%) (pcf) (%) (%) Sieve Pressure) (GI)
Gradation
SUMMARY OF LABORATORY TEST RESULTS
TABLE 1
B-5 3 1.0 SD 31 62 7 - NP (SW) A-1-a(0) Well graded SAND
B-5 8 5.6 SD 15 - NP (SM) A-2-4(0) Silty SAND
B-6 5 1.6 SD 9 - NP (SP-SM) A-2-4(0) Poorly graded Silty SAND
C-1 3 7.2 115.8 35 - NP (SM) A-2-4(0) Silty SAND
C-2 9 22.8 98.7 94 33 17 (CL) A-6(15) CLAY
C-3 5 4.2 SD 34 56 10 - NP (SP-SM) A-1-b(0) Poorly graded Silty SAND
C-4 2 2.8 SD 9 - NP (SM) A-2-4(0) Silty SAND
C-5 1 11.1 118.6 55 27 13 s(CL) A-6(4) Sandy CLAY
C-6 2 5.7 111.2 4 68 28 24 6 (SC-SM) A-2-4(0) Clayey Silty SAND
C-8 2 5.9 113.1 3 73 24 - NP (SM) A-2-4(0) Silty SAND
C-10 4 5.2 SD 21 - NP (SM) A-2-4(0) Silty SAND
E-1 5 3.4 SD 55 - NP s(ML) A-4(0) Sandy SILT
E-2 1 6.7 119.6 31 20 3 (SM) A-2-4(0) Silty SAND
D-1 3 7.0 41 26 10 (SC) A-4(1) Clayey SAND
D-2 2.5 14.2 115.0 48 29 12 0.0 ( 150 psf) (SC) A-6(3) Clayey SAND
D-4 3 8.6 112.5 53 25 9 s(CL) A-4(2) Sandy CLAY
P-5 2 2.7 122.0 15 NP - (SM) A-2-4(0) Silty SAND
SD = Sample Disturbed, NV = Non-Viscous, NP = Non-Plastic Job No. 19-0013
Client: Poudre School District
Project No.: 19-0013
1 8.8 299 36
2 9.4 170 24
3 7.5 404 50
4 - - -
Location: D-1 to D- 5, 1 to 5', Bulk Classification: SC/A-2-4 (0) < No. 200 (%): 30.0
Description: Light brown, clayey SAND Liquid Limit: 27
Plasticity Index: 9
5/2019 Figure #9
New Prospect 6-12 School
R-Value (ASTM D2844 / AASHTO T190)
Test Point Moisture (%)
Exudation
Pressure (psi)
R-Value
R-Value at 300 psi Exudation Pressure
36
Results apply only to the specific items and locations referenced and at the time of testing. This report should not be reproduced, except in full, without the written permission of
GROUND Engineering
Consultants, Inc.
0
10
20
30
40
50
60
70
80
90
100
800 700 600 500 400 300 200 100 0
R-Value
Exudation Pressure (psi)
0
5
10
15
20
25
30
35
40
800 700 600 500 400 300 200 100 0
Moisture Content (%)
Exudation Pressure (psi)
www.groundeng.com
Englewood, Commerce City, Loveland, Granby, Gypsum
APPENDIX A
Detailed Drilling Logs
25/12
14/12
22/12
20/12
14/12
11/12
12/12
9.9 113.0 47 24 6 SC-SM
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
(Continued Next Page)
Elevation
(ft)
100
95
90
85
80
75
70
65
Depth
(ft)
0
5
10
15
20
25
30
35
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 2
TEST HOLE A-01
CLIENT: Poudre School District
30/12
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color. (continued)
Bottom of borehole at Approx. 40 feet.
Elevation
(ft)
65
60
Depth
(ft)
35
40
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 2 OF 2
TEST HOLE A-01
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
15/12
10/12
14/12
4/12
6/12
15.2 106.5 56 34 20 SC
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
Test hole caved at 18 feet.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 30 feet.
Elevation
(ft)
100
95
90
85
80
75
70
Depth
(ft)
0
5
10
15
20
25
30
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE A-02
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
6/12
7/12
20/12
6/12
3.2
20.9
118.1
103.5
14
19
NP
NP
SM
SM
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Test hole caved at 18 feet.
Bottom of borehole at Approx. 31 feet.
Elevation
(ft)
100
95
90
85
80
75
70
Depth
(ft)
0
5
10
15
20
25
30
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
11/12
19/12
20/12
10/12
12/12
8/12
7/12
1.0
24.0
SD
101.9
4
83 29
NP
12
SW
CL
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
(Continued Next Page)
Elevation
(ft)
100
95
90
85
80
75
70
65
Depth
(ft)
0
5
10
15
20
25
30
35
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
13/12
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color. (continued)
Bottom of borehole at Approx. 40 feet.
Elevation
(ft)
65
60
Depth
(ft)
35
40
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 2 OF 2
TEST HOLE A-04
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
16/12
11/12
17/12
9/12
18/12
16/12
25.2
12.7
96.8
114.5
89
13
14 34
NP
CL
SM
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 30 feet.
Elevation
(ft)
100
95
90
85
80
75
70
Depth
(ft)
0
5
10
15
20
25
30
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
15/12
12/12
17/12
10/12
14/12
16/12
22/12
2.1
15.9
SD
104.8
6
3
NP
NP
SW-SM
SP
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
(Continued Next Page)
Elevation
(ft)
100
95
90
85
80
75
70
65
Depth
(ft)
0
5
10
15
20
25
30
35
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
38/12
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color. (continued)
Bottom of borehole at Approx. 40 feet.
Elevation
(ft)
65
60
Depth
(ft)
35
40
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 2 OF 2
TEST HOLE A-06
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
18/12
8/12
28/12
2-2-3
3-3-4
7.7
23.6
110.0
SD
7
85 38
NP
21
SW-SM
CL
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Test hole caved at 15 feet.
Bottom of borehole at Approx. 30 feet.
Elevation
(ft)
100
95
90
85
80
75
Depth
(ft)
0
5
10
15
20
25
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
22/12
28/12
39/12
17/12
8/12
11/12
9-14-
14.7 109.8 48 34 18 SC
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
(Continued Next Page)
Elevation
(ft)
100
95
90
85
80
75
70
65
Depth
(ft)
0
5
10
15
20
25
30
35
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 2
TEST HOLE A-08
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
18
5-5-10
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color. (continued)
Bottom of borehole at Approx. 41 feet.
Elevation
(ft)
65
60
Depth
(ft)
35
40
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 2 OF 2
TEST HOLE A-08
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
7/12
28/12
32/12
7/12
2/12
9.3 123.6 38 NP SM
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
Test hole caved at 16 feet.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 29 feet.
Elevation
(ft)
100
95
90
85
80
75
Depth
(ft)
0
5
10
15
20
25
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE A-09
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
8/12
26/12
16/12
6/12
8-9-7
5.6 117.1 16 NP SM
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 31 feet.
Elevation
(ft)
100
95
90
85
80
75
70
Depth
(ft)
0
5
10
15
20
25
30
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE A-10
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
5/12
9-12-
15
11-10-
14
1-2-3
6.2 120.9 28 22 6 SC-SM
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Test hole caved at 19 feet.
Bottom of borehole at Approx. 30 feet.
Elevation
(ft)
100
95
90
85
80
75
70
Depth
(ft)
0
5
10
15
20
25
30
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE B-01
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
9/12
12-14-
18
6-3-2
2-2-1
5-4-8
1-2-5
12.8 112.7 55 21 3 ML
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
Test hole caved at 16 feet.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 31 feet.
Elevation
(ft)
100
95
90
85
80
75
70
Depth
(ft)
0
5
10
15
20
25
30
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE B-02
CLIENT: Poudre School District
JOB NO.: 19-0013
15/12
19/12
5/12
3-4-6
5.3 SD 4 NP SP
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 32 feet.
Elevation
(ft)
100
95
90
85
80
75
70
Depth
(ft)
0
5
10
15
20
25
30
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE B-03
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
12/12
26/12
4-5-4
1.6 SD 15 NP SM
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Test hole caved at 14 feet.
(Continued Next Page)
Elevation
(ft)
100
95
90
85
80
75
70
65
Depth
(ft)
0
5
10
15
20
25
30
35
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 2
TEST HOLE B-04
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
4-4-5
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color. (continued)
Bottom of borehole at Approx. 42 feet.
Elevation
(ft)
65
60
Depth
(ft)
35
40
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 2 OF 2
TEST HOLE B-04
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
12/12
13/12
13/12
1.0
5.6
SD
SD
7
15
NP
NP
SW
SM
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 15 feet.
Elevation
(ft)
100
95
90
85
Depth
(ft)
0
5
10
15
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE B-05
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
8/12
13/12
20/12
1.6 SD 9 NP SP-SM
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 16 feet.
Elevation
(ft)
100
95
90
85
Depth
(ft)
0
5
10
15
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE B-06
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
10/12
24/12
7.2 115.8 35 NP SM
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 10 feet.
Elevation
(ft)
100
95
90
Depth
(ft)
0
5
10
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE C-01
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
5/12
7/12 22.8 98.7 94 33 17 CL
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 10 feet.
Elevation
(ft)
100
95
90
Depth
(ft)
0
5
10
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE C-02
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
7/12
28/12
4.2 SD 10 NP SP-SM
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 11 feet.
Elevation
(ft)
100
95
90
Depth
(ft)
0
5
10
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE C-03
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
12/12
29/12
2.8 SD 9 NP SM
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 10 feet.
Elevation
(ft)
100
95
90
Depth
(ft)
0
5
10
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE C-04
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
13/12
4/12
36/12
11.1 118.6 55 27 13 CL
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 11 feet.
Elevation
(ft)
100
95
90
Depth
(ft)
0
5
10
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE C-05
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
4/12
25/12
5.7 111.2 28 24 6 SC-SM
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 10 feet.
Elevation
(ft)
100
95
90
Depth
(ft)
0
5
10
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE C-06
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
10/12
15/12
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
Bottom of borehole at Approx. 10 feet.
Elevation
(ft)
100
95
90
Depth
(ft)
0
5
10
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE C-07
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
4/12
38/12
5.9 113.1 24 NP SM
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
Bottom of borehole at Approx. 8 feet.
Elevation
(ft)
100
95
Depth
(ft)
0
5
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE C-08
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
7/12
10/12
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 10 feet.
Elevation
(ft)
100
95
90
Depth
(ft)
0
5
10
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE C-09
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
13/12
18/12
5.2 SD 21 NP SM
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 10 feet.
Elevation
(ft)
100
95
90
Depth
(ft)
0
5
10
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE C-10
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
23/12
31/12
3.4 SD 55 NP ML
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
Bottom of borehole at Approx. 11 feet.
Elevation
(ft)
100
95
90
Depth
(ft)
0
5
10
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE E-01
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
5/12
6/12
22/12
6.7 119.6 31 20 3 SM
TOPSOIL
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 10 feet.
Elevation
(ft)
100
95
90
Depth
(ft)
0
5
10
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE E-02
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
32/12
19/12
Approximately 4 1/2 inches of asphalt.
Approximately 6 inches of road base.
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 10 feet.
Elevation
(ft)
100
95
90
Depth
(ft)
0
5
10
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE P-01
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
18/12
Approximately 4 1/2 inches of asphalt.
Approximately 6 inches of road base.
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
CLAY and SAND: Moderately plastic, fine to coarse
grained, moist, medium to very stiff, and light brown
to brown in color.
Bottom of borehole at Approx. 10 feet.
Elevation
(ft)
100
95
90
Depth
(ft)
0
5
10
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE P-02
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
Test hole not drilled due to utility conflict.
Bottom of borehole at Approx. 1 feet.
Elevation
(ft)
100
Depth
(ft)
0
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE P-03
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
6/12
Approximately 5 1/2 inches of asphalt.
Approximately 6 inches of road base.
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
Test hole caved at 3 feet.
Test hole caving from 7-9 feet.
Bottom of borehole at Approx. 9 feet.
Elevation
(ft)
100
95
Depth
(ft)
0
5
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE P-04
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
14/12
23/12
Approximately 6 1/2 inches of asphalt.
Approximately 8 inches of road base.
SAND and GRAVEL: Silty to clayey, non- to low
plastic, fine to coarse grained with gravel, moist to
wet, loose to dense, and light brown to pink to dark
brown in color.
Test hole caved at 5 feet.
Bottom of borehole at Approx. 8 feet.
Elevation
(ft)
100
95
Depth
(ft)
0
5
Graphic Log
Sample Type
Blow Count
Natural Moisture
Content (%)
Natural Dry
Density (pcf)
Percent Passing
No. 200 Sieve
Liquid Limit
Plasticity
Index
ATTERBERG
LIMITS
% Swell at
Surcharge (psf)
USCS
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE P-05
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
APPENDIX B
Pavement Section Calculations
Page 1
1993 AASHTO Pavement Design
DARWin Pavement Design and Analysis System
A Proprietary AASHTOWare
Computer Software Product
Network Administrator
Rigid Structural Design Module
Poudre School District
Prospect 6-12 School
Prospect Rd and County Rd 5
Fort Collins, Colorado
Concrete Apron
Rigid Structural Design
Pavement Type JPCP
18-kip ESALs Over Initial Performance Period 219,000
Initial Serviceability 4.5
Terminal Serviceability 2
28-day Mean PCC Modulus of Rupture 650 psi
28-day Mean Elastic Modulus of Slab 3,400,000 psi
Mean Effective k-value 15 psi/in
Reliability Level 80 %
Overall Standard Deviation 0.34
Load Transfer Coefficient, J 4.2
Overall Drainage Coefficient, Cd 1
Calculated Design Thickness 6.42 in
Page 1
1993 AASHTO Pavement Design
DARWin Pavement Design and Analysis System
A Proprietary AASHTOWare
Computer Software Product
Network Administrator
Flexible Structural Design Module
Poudre School District
Prospect 6-12 School
Prospect Rd and County Rd 5
Fort Collins, Colorado
General Parking Full Depth Asphalt Section
Flexible Structural Design
18-kip ESALs Over Initial Performance Period 36,500
Initial Serviceability 4.5
Terminal Serviceability 2
Reliability Level 80 %
Overall Standard Deviation 0.44
Roadbed Soil Resilient Modulus 4,940 psi
Stage Construction 1
Calculated Design Structural Number 2.13 in
Specified Layer Design
Layer
Material Description
Struct
Coef.
(Ai)
Drain
Coef.
(Mi)
Thickness
(Di)(in)
Width
(ft)
Calculated
SN (in)
1 Hot Mix Asphalt 0.44 1 5 - 2.20
Total - - - 5.00 - 2.20
Page 1
1993 AASHTO Pavement Design
DARWin Pavement Design and Analysis System
A Proprietary AASHTOWare
Computer Software Product
Network Administrator
Flexible Structural Design Module
Poudre School District
Prospect 6-12 School
Prospect Rd and County Rd 5
Fort Collins, Colorado
General Parking Composite Asphalt Section
Flexible Structural Design
18-kip ESALs Over Initial Performance Period 36,500
Initial Serviceability 4.5
Terminal Serviceability 2
Reliability Level 80 %
Overall Standard Deviation 0.44
Roadbed Soil Resilient Modulus 4,940 psi
Stage Construction 1
Calculated Design Structural Number 2.13 in
Specified Layer Design
Layer
Material Description
Struct
Coef.
(Ai)
Drain
Coef.
(Mi)
Thickness
(Di)(in)
Width
(ft)
Calculated
SN (in)
1 Hot Mix Asphalt 0.44 1 4 - 1.76
2 Aggregate Base Course 0.11 1 4 - 0.44
Total - - - 8.00 - 2.20
Page 1
1993 AASHTO Pavement Design
DARWin Pavement Design and Analysis System
A Proprietary AASHTOWare
Computer Software Product
Network Administrator
Flexible Structural Design Module
Poudre School District
Prospect 6-12 School
Prospect Rd and County Rd 5
Fort Collins, Colorado
Private Drive Composite Asphalt Section
Flexible Structural Design
18-kip ESALs Over Initial Performance Period 219,000
Initial Serviceability 4.5
Terminal Serviceability 2
Reliability Level 80 %
Overall Standard Deviation 0.44
Roadbed Soil Resilient Modulus 4,940 psi
Stage Construction 1
Calculated Design Structural Number 2.81 in
Specified Layer Design
Layer
Material Description
Struct
Coef.
(Ai)
Drain
Coef.
(Mi)
Thickness
(Di)(in)
Width
(ft)
Calculated
SN (in)
1 Hot Mix Asphalt 0.44 1 6.5 - 2.86
Total - - - 6.50 - 2.86
Page 1
1993 AASHTO Pavement Design
DARWin Pavement Design and Analysis System
A Proprietary AASHTOWare
Computer Software Product
Network Administrator
Flexible Structural Design Module
Poudre School District
Prospect 6-12 School
Prospect Rd and County Rd 5
Fort Collins, Colorado
Private Drive Composite Asphalt Section
Flexible Structural Design
18-kip ESALs Over Initial Performance Period 219,000
Initial Serviceability 4.5
Terminal Serviceability 2
Reliability Level 80 %
Overall Standard Deviation 0.44
Roadbed Soil Resilient Modulus 4,940 psi
Stage Construction 1
Calculated Design Structural Number 2.81 in
Specified Layer Design
Layer
Material Description
Struct
Coef.
(Ai)
Drain
Coef.
(Mi)
Thickness
(Di)(in)
Width
(ft)
Calculated
SN (in)
1 Hot Mix Asphalt 0.44 1 5 - 2.20
2 Aggregate Base Course 0.11 1 6 - 0.66
Total - - - 11.00 - 2.86
Page 1
1993 AASHTO Pavement Design
DARWin Pavement Design and Analysis System
A Proprietary AASHTOWare
Computer Software Product
Network Administrator
Flexible Structural Design Module
Poudre School District
Prospect 6-12 School
Prospect Rd and County Rd 5
Fort Collins, Colorado
Private Drive Full Depth Asphalt Section
Flexible Structural Design
18-kip ESALs Over Initial Performance Period 73,000
Initial Serviceability 4.5
Terminal Serviceability 2
Reliability Level 80 %
Overall Standard Deviation 0.44
Roadbed Soil Resilient Modulus 4,940 psi
Stage Construction 1
Calculated Design Structural Number 2.38 in
Specified Layer Design
Layer
Material Description
Struct
Coef.
(Ai)
Drain
Coef.
(Mi)
Thickness
(Di)(in)
Width
(ft)
Calculated
SN (in)
1 Hot Mix Asphalt 0.44 1 5.5 - 2.42
Total - - - 5.50 - 2.42
Page 1
1993 AASHTO Pavement Design
DARWin Pavement Design and Analysis System
A Proprietary AASHTOWare
Computer Software Product
Network Administrator
Flexible Structural Design Module
Poudre School District
Prospect 6-12 School
Prospect Rd and County Rd 5
Fort Collins, Colorado
Private Drive Composite Asphalt Section
Flexible Structural Design
18-kip ESALs Over Initial Performance Period 73,000
Initial Serviceability 4.5
Terminal Serviceability 2
Reliability Level 80 %
Overall Standard Deviation 0.44
Roadbed Soil Resilient Modulus 4,940 psi
Stage Construction 1
Calculated Design Structural Number 2.38 in
Specified Layer Design
Layer
Material Description
Struct
Coef.
(Ai)
Drain
Coef.
(Mi)
Thickness
(Di)(in)
Width
(ft)
Calculated
SN (in)
1 Hot Mix Asphalt 0.44 1 4 - 1.76
2 Aggregate Base Course 0.11 1 6 - 0.66
Total - - - 10.00 - 2.42
Page 1
1993 AASHTO Pavement Design
DARWin Pavement Design and Analysis System
A Proprietary AASHTOWare
Computer Software Product
Network Administrator
Flexible Structural Design Module
Poudre School District
Prospect 6-12 School
Prospect Rd and County Rd 5
Fort Collins, Colorado
Public Rigth of Way Composite Asphalt Section
Flexible Structural Design
18-kip ESALs Over Initial Performance Period 1,460,000
Initial Serviceability 4.5
Terminal Serviceability 2.5
Reliability Level 90 %
Overall Standard Deviation 0.44
Roadbed Soil Resilient Modulus 4,940 psi
Stage Construction 1
Calculated Design Structural Number 4.12 in
Specified Layer Design
Layer
Material Description
Struct
Coef.
(Ai)
Drain
Coef.
(Mi)
Thickness
(Di)(in)
Width
(ft)
Calculated
SN (in)
1 Hot Mix Asphalt 0.44 1 7.5 - 3.30
2 Aggregate Base Course 0.11 1 8 - 0.88
Total - - - 15.50 - 4.18
Page 1
1993 AASHTO Pavement Design
DARWin Pavement Design and Analysis System
A Proprietary AASHTOWare
Computer Software Product
Network Administrator
Flexible Structural Design Module
Poudre School District
Prospect 6-12 School
Prospect Rd and County Rd 5
Fort Collins, Colorado
Public Right of Way Composite Asphalt Section
Flexible Structural Design
18-kip ESALs Over Initial Performance Period 730,000
Initial Serviceability 4.5
Terminal Serviceability 2.5
Reliability Level 90 %
Overall Standard Deviation 0.44
Roadbed Soil Resilient Modulus 4,940 psi
Stage Construction 1
Calculated Design Structural Number 3.71 in
Specified Layer Design
Layer
Material Description
Struct
Coef.
(Ai)
Drain
Coef.
(Mi)
Thickness
(Di)(in)
Width
(ft)
Calculated
SN (in)
1 Hot Mix Asphalt 0.44 1 7 - 3.08
2 Aggregate Base Course 0.11 1 6 - 0.66
Total - - - 13.00 - 3.74
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
PROJECT LOCATION: Fort Collins, CO
Strength (ksf)
PAGE 1 OF 1
TEST HOLE A-07
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 2
TEST HOLE A-06
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE A-05
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
MATERIAL DESCRIPTION
Unconfined
Strength (ksf)
PAGE 1 OF 2
TEST HOLE A-04
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
Unconfined
Strength (ksf)
PAGE 1 OF 1
TEST HOLE A-03
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
ELEV. 100
C-08
ELEV. 100
C-09
ELEV. 100
C-10
ELEV. 100
B-05
ELEV. 100
B-06
ELEV. 100
- 38/12
- 18/12
- 8/12
- 28/12
- 2-2-3
- 3-3-4
- 22/12
- 28/12
- 39/12
- 17/12
- 8/12
- 11/12
- 9-14-18
- 5-5-10
- 7/12
- 28/12
- 32/12
- 7/12
- 2/12
- 8/12
- 26/12
- 16/12
- 6/12
- 8-9-7
SUBSURFACE DIAGRAM
Elevation (ft)
CLIENT: Poudre School District
JOB NO.: 19-0013
PROJECT NAME: PSD: New Prospect 6-12 School - Final
PROJECT LOCATION: Fort Collins, CO
A-01
ELEV. 100
A-02
ELEV. 100
A-03
ELEV. 100
A-04
ELEV. 100
A-05
ELEV. 100
A-06
ELEV. 100
A-07
ELEV. 100
A-08
ELEV. 100
A-09
ELEV. 100
A-10
ELEV. 100