HomeMy WebLinkAboutALPINE BANK - PDP200020 - - GEOTECHNICAL (SOILS) REPORT
Corporate Office: 7108 South Alton Way, Building B • Centennial, CO 80112
Locations: Centennial • Frederick • Silverthorne • Salida/Crested Butte
Phone 303-220-0300 • www.cesareinc.com
GEOTECHNICAL STUDY
Alpine Bank
Fort Collins, Colorado
Report Prepared for:
Mr. Todd Goulding
Goulding Development Advisors, LLC
PO Box 2308
Edwards, CO 81632
Project No. 20.3059
December 1, 2020
20.3059 Alpine Bank Report 12.01.20 i
GEOTECHNICAL STUDY
Alpine Bank
Fort Collins, Colorado
Report Prepared for:
Mr. Todd Goulding
Goulding Development Advisors, LLC
PO Box 2308
Edwards, CO 81632
Project No. 20.3059
December 1, 2020
Report Prepared by:
Yvonne “Bonnie” E. Schimmel, P.E.
Project Engineer
12.01.2020
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20.3059 Alpine Bank Report 12.01.20 ii
TABLE OF CONTENTS
1. PURPOSE ..................................................................................................................................... 1
1.1 GENERAL .................................................................................................................................... 1
1.2 SCOPE OF SERVICES ................................................................................................................... 1
2. SUMMARY OF FINDINGS AND CONCLUSIONS ............................................................................ 1
3. SITE CONDITIONS ...................................................................................................................... 1
4. PROPOSED CONSTRUCTION ....................................................................................................... 3
5. GEOLOGIC CONDITIONS ............................................................................................................. 3
5.1 SURFICIAL DEPOSITS .................................................................................................................. 3
5.2 BEDROCK ................................................................................................................................... 4
6. FIELD EXPLORATION .................................................................................................................. 4
7. LABORATORY TESTING ............................................................................................................... 4
8. SUBSURFACE CONDITIONS ........................................................................................................ 4
9. GEOLOGIC HAZARDS .................................................................................................................. 5
9.1 EXPANSIVE SOIL ......................................................................................................................... 5
9.2 SEISMIC CONSIDERATIONS ......................................................................................................... 5
10. GEOTECHNICAL CONSIDERATIONS .......................................................................................... 6
11. FOUNDATION RECOMMENDATIONS ......................................................................................... 6
11.1 SPREAD FOOTINGS ................................................................................................................... 6
11.2 DRILLED PIERS ......................................................................................................................... 7
12. LATERAL EARTH PRESSURES .................................................................................................... 8
13. INTERIOR FLOORS .................................................................................................................... 9
13.1 OVEREXCAVATION CONSIDERATIONS ........................................................................................ 9
13.2 SLAB-ON-GRADE CONSTRUCTION DETAILS ................................................................................. 9
13.3 STRUCTURALLY SUPPORTED FLOORS ....................................................................................... 11
14. EXTERIOR FLATWORK ............................................................................................................ 11
14.1 OVERHANGING ROOFS ............................................................................................................ 12
15. EXCAVATIONS ......................................................................................................................... 12
16. STRUCTURAL FILL/BACKFILL SOIL ........................................................................................ 13
16.1 IMPORT FILL ........................................................................................................................... 14
17. SUBSURFACE DRAINAGE ........................................................................................................ 15
18. SURFACE DRAINAGE ............................................................................................................... 15
19. PAVEMENT RECOMMENDATIONS ........................................................................................... 16
19.1 DESIGN CRITERIA ................................................................................................................... 16
19.2 SPECIAL CONCERNS ................................................................................................................ 16
19.2.1 FROST HEAVE .................................................................................................................. 16
19.3 PAVEMENT THICKNESSES ........................................................................................................ 17
19.4 TRASH DUMPSTER APPROACHES .............................................................................................. 17
19.5 SUBGRADE PREPARATION AND PAVEMENT CONSTRUCTION ...................................................... 17
19.5.1 PAVEMENT SUBGRADE ..................................................................................................... 17
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20.3059 Alpine Bank Report 12.01.20 iii
19.5.2 SUBBASE AND AGGREGATE BASE COURSE ......................................................................... 18
19.5.3 PAVEMENT ...................................................................................................................... 18
20. SOIL CHEMICAL TESTING ....................................................................................................... 19
20.1 SULFATE EXPOSURE ................................................................................................................ 19
21. GEOTECHNICAL RISK .............................................................................................................. 19
22. LIMITATIONS .......................................................................................................................... 20
TABLES
TABLE 7.1. Laboratory Testing Performed ...................................................................................... 4
TABLE 8.1. Groundwater Depths .................................................................................................... 5
TABLE 10.1. Summary of Swell/Consolidation Laboratory Testing ................................................ 6
TABLE 12.1. Lateral Earth Pressures and Coefficients of Sliding Resistance for Onsite Material .. 9
TABLE 15.1. Allowable Slope Configuration for Onsite Material .................................................. 13
TABLE 16.1. Compaction Specifications ........................................................................................ 14
TABLE 16.2. Import Fill Specifications .......................................................................................... 14
TABLE 19.1. Pavement Design Parameters .................................................................................. 16
TABLE 19.2. Recommended Pavement Section Thicknesses ........................................................ 17
TABLE 19.3. Pavement Section Lift Thickness Recommendations ............................................... 18
TABLE 20.1 Information from ACI 318-08 - Table 4.3.1 ............................................................... 19
FIGURES
VICINITY MAP ................................................................................................................... FIGURE 1
BORING LOCATION PLAN ................................................................................................. FIGURE 2
APPENDICES
FIELD EXPLORATION ................................................................................................... APPENDIX A
LABORATORY TESTING ................................................................................................ APPENDIX B
VAPOR BARRIERS ........................................................................................................ APPENDIX C
PAVEMENT DESIGN CALCULATIONS ............................................................................ APPENDIX D
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20.3059 Alpine Bank Report 12.01.20 iv
COMMON ABBREVIATIONS
AASHTO ......... American Association of State Highway and Transportation Officials
ABC ................ aggregate base course
ACI ................ American Concrete Institute
ADA ............... Americans with Disabilities Act
ADSC ............. Association of Drilled Contractors
AI .................. Asphalt Institute
APM .............. asphalt paving material
ASCE .............. American Society of Civil Engineers
ASTM ............. American Society for Testing and Materials
AWWA ........... American Water Works Association
bgs................. below ground surface
CDOT ............. Colorado Department of Transportation
CBR ................ California Bearing Ratio
CFR ................ Code of Federal Regulations
CGS ................ Colorado Geological Survey
CKD ............... cement of kiln dust stabilized subgrade
CMU ............... concrete masonry unit
CTB ................ cement treated base course
deg ................ degree
EDLA .............. equivalent daily load application
em .................. edge moisture variation distance
EPS ................ expanded polystyrene
ESAL .............. equivalent single axle loads
f’c .................. specified compressive strength of concrete at the age of 28 days
Fa ................... seismic site coefficient
FHWA ............ Federal Highway Administration
FS .................. factor of safety
FV ................... seismic site coefficient
GSA ................ global stability analysis
GVW .............. gross vehicle weight
IBC ................ International Building Code
ICC-ES ........... International Code Council Evaluation Services, Inc.
IRC ................ International Residential Code
kip ................. 1,000 pounds-force
km ................. kilometer
LTS ................ lime treated subgrade
MDD .............. maximum dry density
mg/L ............. milligrams per liter
MGPEC ........... Metropolitan Government Pavement Engineers Council
mm ................ millimeter
Mr .................. resilient modulus
MSE ............... mechanically stabilized earth
mV ................. millivolts
NAPA ............. National Asphalt Pavement Association
NDESIGN ........... design gyrations
OSHA ............. Occupational Safety and Health Administration
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OMC ............... optimum moisture content
OWTS ............ onsite wastewater treatment system
PCA ................ Portland Cement Association
PCC ................ portland cement concrete
pcf ................. pounds per cubic foot
pci .................. pounds per cubic inch
pH .................. power of hydrogen
psf ................. pounds per square foot
psi .................. pounds per square inch
PT .................. post-tension
RAP ................ recycled asphalt pavement
Ss ..................... mapped spectral accelerations for short periods
UBC ............... Uniform Building Code
USGS ............. United States Geological Survey
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20.3059 Alpine Bank Report 12.01.20 1
1. PURPOSE
1.1 GENERAL
Cesare, Inc. (Cesare) performed a geotechnical study for the proposed Alpine Bank structures to be
located at the existing 1608, 1610, and 1618 South College Avenue in Fort Collins, Colorado. The
study was made to characterize existing subsurface conditions at the site and assist in determining
design criteria for planning, site development, foundation systems, interior floor systems, exterior
flatwork, surface and subsurface drainage adjacent to structures, pavement, and to present other
pertinent geotechnical issues. Information gathered during the field exploration and laboratory
testing is summarized in Figures 1 and 2 and Appendices A through D. Cesare’s opinions and
recommendations presented in this report are based on data generated during this field exploration,
laboratory testing, and its experience.
1.2 SCOPE OF SERVICES
The scope of services performed is detailed in Cesare’s Proposal Agreement No. 200706A.geo which
was executed on October 21, 2020.
2. SUMMARY OF FINDINGS AND CONCLUSIONS
This section is intended as a summary only and does not include design details. The report should
be read in its entirety and utilized for design.
In Boring B-1, 4 inches of asphalt pavement was underlain by gravel and sand fill to a
depth of 11 feet, clay to a depth of 17 feet, and sand to a depth of 20 feet. Drilling was
stopped at 20 feet when a gasoline odor was observed at depths of 14 to 19 feet. In
Boring B-2, clay fill was encountered to a depth of 4 feet and underlain by sandy clay to
clayey sand to a depth of 12 feet, weathered sandstone to a depth of 15 feet, and
claystone to a depth of 29 feet. In Boring B-3, 3 inches of asp halt pavement was underlain
by clay fill to a depth of 11 feet, silty sand to a depth of 14.5 feet, and claystone to a
depth of 29.25 feet. In Boring B-4, 3 inches of asphalt pavement was underlain by clay
fill to a depth of 6 feet, sandy clay to a depth of 14 feet, and claystone to a depth of 29
feet.
“Potentially Swelling Soil and Rock in the Front Range Urban Corridor, Colorado”, prepared
by Hart for the Colorado Geological Survey, dated 1972, indicates that onsite material has
low swell potential. Seismically, the site classifies as Type D according to the 2018 IBC.
In Cesare’s opinion, footings bearing on replaced structural fi ll or piers drilled into bedrock
are appropriate for the proposed structure. Foundations and slabs-on-grade bearing on
preexisting fill are not acceptable. Structural floors are an acceptable alternative for floor
construction.
Good surface drainage should be established and positive drainage away from the
structures, pavement, and other site improvements should be provided during
construction and maintained throughout the life of the proposed structures.
Acceptable pavement types are full depth APM or APM over ABC. Cesare recommends
that trash dumpster approaches be paved with portland cement concrete.
3. SITE CONDITIONS
The site is located at the southeastern corner of South College Avenue and East Prospect Road in
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Fort Collins, Colorado. A vicinity map is shown in Figure 1. The site is currently developed with existing
buildings and associated flatwork and pavement. The existing buildings onsite are located at 1608,
1610, and 1618 South College Avenue. Cesare understands that at least some of the existing
buildings have basements. The foundation types of the existing buildings are unknown to Cesare at
the time of this report. Cesare is not aware of distress to the existing buildings that was caused by
soil movement. The site is bound by South College Avenue and commercial development to the west,
East Prospect Road and commercial development to the north, an alley and single-family residences
to the east, and a commercial development to the south. The top ography of the site is gently sloping
with a grade change of about 10 feet down to the south and east. The topography adjacent to the
site also slopes gently down to the south and east.
Vegetation onsite consists of maintained turf grass, bushes, and trees. No bodies of water or bedrock
outcrops were observed onsite.
Photo 1. View looking west from the north side of the site.
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20.3059 Alpine Bank Report 12.01.20 3
Photo 2. View looking north from the southeast corner of the site.
4. PROPOSED CONSTRUCTION
The proposed improvements will consist of a newly constructed bank building and a historical building
that will be moved onsite. The proposed newly constructed bank has a footprint of about 7,600
square feet and the historical building has a footprint of about 1,100 square feet. Cesare understands
that while at least some of the existing buildings have basements, the proposed structures will not.
The locations of Cesare’s borings are shown in Figure 2 and the assumed first floor level is shown in
the Boring Logs in Appendix A. If the actual first floor level varies by more than 2 feet from that
shown, Cesare should be notified and the recommendations of this report reviewed and revised, if
appropriate.
The site plans indicate pavement will consist of a fire access easement, a drive through ATM lane,
and parking spaces. Thirty-one parking spaces, with associated drive lanes, are planned. Cesare
assumes some minor cuts and fills will be required (less than 3 feet), and onsite soil or similar quality
offsite soil will be used for fill.
5. GEOLOGIC CONDITIONS
5.1 SURFICIAL DEPOSITS
The “Geologic Map of the Boulder-Fort Collins-Greeley Area, Colorado” prepared for the USGS by
Colton, dated 1978, indicates that surficial deposits onsite likely consist of:
“Slocum Alluvium (Sangamon Interglaciation or Illinoian Glaciation, Pleistocene) –
Brown to white cobble and boulder gravel as much as 20 feet (6 m) thick. Most
clasts are well-rounded igneous and metamorphic rock, some are sedimentary;
most are weathered and have thin rinds of calcium carbonate. Well-developed soil
profile consists of a thin A horizon, 6 to 12 inches (15 to 30 cm) thick; a clayey,
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reddish brown B horizon, 2 feet (0.6 m) thick; and a Cca or caliche horizon, 3 feet
(1 m) thick. Upper surface of deposits is generally 100 to 130 feet (30 to 40 m)
above major stream-less in northeast corner of area”.
5.2 BEDROCK
The “Geologic Map of the Boulder-Fort Collins-Greeley Area, Colorado” prepared for the USGS by
Colton, dated 1978, indicates that bedrock onsite likely consist of:
Pierre Shale “Lower shale member-Consists of Mitten Black Shale Member, Shar on
Springs Member, and Gammon Ferruginous Member, these three members are
mostly dark olive gray bentonithic shale. Thickness about 1,220 to 1,650 ft (500
m)”.
6. FIELD EXPLORATION
Subsurface conditions were explored on November 2, 2020 by drilling four borings at the locations
indicated in Figure 2. Boring B-1 was drilled to a depth of about 20 feet and drilling was stopped
when a gasoline odor was observed at depths of 14 to 19 feet. A sample of the soil was tested for
BTEX contamination and was found to contain contaminates at lower than regulatory levels. Borings
B-2 through B-4 were drilled to a depth of about 29 feet. Graphical logs of the subsurface conditions
observed, locations of sampling, and further explanation of the exploration performed are presented
in the Boring Logs and accompanying Key to Symbols contained in Appendix A.
7. LABORATORY TESTING
Cesare personnel returned samples obtained during field exploration to its laboratory where
professional staff visually classified them and assigned testing to selected samples to evaluate
pertinent engineering properties. Laboratory tests performed are listed in Table 7.1. Further
discussion of laboratory testing and the laboratory test results are presented in Appendix B.
TABLE 7.1. Laboratory Testing Performed
Laboratory Test To Evaluate
Grain size analysis Grain size distribution for classification purposes.
Atterberg limits Soil plasticity for classification purposes.
Swell/consolidation Effect of wetting and loading on the soil.
R-value Strength of subgrade soil for the design of pavement systems.
Water soluble sulfate content Potential corrosivity of the soil on cementitious material.
8. SUBSURFACE CONDITIONS
Cesare’s borings encountered the following conditions.
In Boring B-1, 4 inches of asphalt pavement was underlain by gravel and sand fill to a
depth of 11 feet, clay to a depth of 17 feet, and sand to a depth of 20 feet. Drilling was
stopped at 20 feet when a gasoline odor was observed at depths of 14 to 19 feet.
In Boring B-2, clay fill was encountered to a depth of 4 feet and underlain by sandy clay
to clayey sand to a depth of 12 feet, weathered sandstone to a depth of 15 feet, and
claystone to a depth of 29 feet.
In Boring B-3, 3 inches of asphalt pavement was underlain by clay fill to a depth of 11
feet, silty sand to a depth of 14.5 feet, and claystone to a depth of 29.25 feet.
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In Boring B-4, 3 inches of asphalt pavement was underlain by cl ay fill to a depth of 6 feet,
sandy clay to a depth of 14 feet, and claystone to a depth of 29 feet.
Borings were checked for the presence of groundwater during drilling. Borings were temporarily
covered and checked for water 7 days after drilling. Measurements are summarized in Table 8.1.
TABLE 8.1. Groundwater Depths
Boring
Groundwater Depth
(ft)
Depth to
Caving 7
Days After
Drilling
(ft)
Depth to
Bedrock
(ft)
During
Drilling
7 Days
After
Drilling
B-1 17 14.8 16
Not
encountered
B-2 13 10.6 14.5 12*
B-3 12 9.4 13.5 14.5
B-4 16 8.4 15.9 14
*Weathered sandstone was encountered at a depth of 12 feet and competent claystone was
encountered at a depth of 15 feet.
The subsurface conditions encountered in Cesare’s borings are reasonably consistent with those
described in Section 5. GEOLOGIC CONDITIONS. These observations represent conditions at the
time of field exploration and may not be indicative of other times or other locations. Groundwater
can be expected to fluctuate and can be influenced by variations in seasons, weather, precipitation,
drainage, vegetation, landscaping, irrigation, leakage of water and/or wastewater systems, etc., both
onsite and offsite. Discontinuous zones of perched water may ex ist or develop within the overburden
material and/or upper zones of the bedrock. Groundwater levels may be higher in the spring and
early summer.
9. GEOLOGIC HAZARDS
The following subsections present a cursory review of geologic publications. A detailed geologic
hazards assessment is not the focus of these scope of services, nor was it requested.
9.1 EXPANSIVE SOIL
The publication titled, “Potentially Swelling Soil and Rock in the Front Range Urban Corridor,
Colorado”, prepared by Hart for the Colorado Geological Survey, dated 1972, indicates that onsite
material has low swell potential and are defined in the publication as follows:
“Low swell potential: This category includes several bedrock formations and many
surficial deposits. The thickness of the surficial deposits may be variable, therefore,
bedrock with a higher swell potential may locally be less than 10 ft below the
surface”.
9.2 SEISMIC CONSIDERATIONS
The soil types present onsite, based on penetration tests and Cesare’s experience, classify as Type
D according to the 2018 IBC (ASCE 7, Chapter 20), as adopted by the City of Fort Collins at the time
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of this report. Additional geophysical studies are necessary to justify a different site classification.
10. GEOTECHNICAL CONSIDERATIONS
Preexisting fill was encountered at the time of Cesare’s field exploration. The history and nature of
the fill is unknown and should not be relied on for support of foundations or floor slabs. While most
of the potential settlement of the fill has probably occurred, there is a risk of additional settlement
after the proposed construction due to changes in subsurface stress conditions.
Results of swell/consolidation testing performed on samples obtained from the site is summarized in
Table 10.1.
TABLE 10.1. Summary of Swell/Consolidation Laboratory Testing
Material
Type
Swell (+) or
Compression (-)
Upon Wetting
(%)
Inundation
Pressure
(psf)
Generalized
Volume
Change
Category
Clay 0.3 1,000 Low
Clay 0.6 500 Low
Claystone -0.3 1,000 Low
In Cesare’s opinion, footings bearing on structural fill or piers drilled into bedrock are appropriate for
the proposed structure. Cesare understands that at least some of the existing buildings have
basements, while the proposed buildings will not. If spread footings are selected, the depth of the
controlled structural fill should extend to the base of the existing fill or to a depth of three times the
footing width below the bottom of the lowest foundations elemen t, whichever is greater. Foundations
and slabs-on-grade bearing on preexisting fill are not acceptable. Structural floors are an acceptable
alternative for floor construction. Recommendations are discuss ed in more detail in following sections
of this report.
11. FOUNDATION RECOMMENDATIONS
11.1 SPREAD FOOTINGS
The proposed structure may be founded on conventional spread footings or pad type footings bearing
on newly placed controlled, structural fill below frost depth and below any existing manmade fill. At
least some of the existing buildings have basements, while the proposed buildings will not. If spread
footings are selected, the depth of controlled structural fill should extend to the base of the existing
fill or to a depth of three times the footing width below the bottom of the lowest foundations element,
whichever is greater. Footings should be designed in accordance with the following design
recommendations:
a) A frost depth of 30 inches should be assumed for this area (2018 IBC, as adopted by the
City of Fort Collins at the time of this study).
b) The footings should be designed for a maximum allowable soil bearing pressure of 2,500
psf based on dead load plus full live load.
c) A 4 inch minimum void space should be provided below the grade beams between pad
type footings. Void forms should be protected before and during concrete placement.
d) Continuous footings should have a minimum width of 18 inches and isolated pad type
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footings should have a minimum dimension of 24 inches. Using the soil pressure
recommended above, Cesare estimates the maximum settlement for the structure will be
on the order of 1 inch, with differential settlement potentially on the order of 0.5 inches.
Footings should be proportioned as much as practicable to reduce differential settlement.
e) Steel reinforcement for continuous concrete foundation walls should be designed to span
localized settlements over a distance of 10 feet.
f) All soft or loose soil beneath footing areas should be redensified in place, or removed and
replaced with properly compacted structural fill, suitable flow fill, or concrete prior to
placement of footing concrete. All footing excavations should be observed by a Cesare
representative prior to placement of concrete to determine if bearing conditions are
consistent with those assumed to develop its recommendations.
11.2 DRILLED PIERS
As an alternative, the proposed structure may be founded on straight shaft drilled piers designed in
accordance with the following recommendations:
a) Dead load plus full live load of the structure should be used for pier sizing.
b) Piers shall be designed so that dead loads are as high as reasonably practicable.
c) Depth of wetting zone below ground surface assumed for design is 20 feet.
d) Maximum allowable end bearing pressure of 25,000 psf may be used for piers bottomed
in bedrock.
e) No side shear shall be used to resist downward axial load (compression load) for any
portion of the pier in natural soil or manplaced fill. No side shear shall be used to resist
upward forces (tensile load) within the top 10 feet of the pier shaft.
f) Allowable side shear of 2,500 psf for the portion of pier in competent bedrock (blow counts
of 50/12 or harder).
g) Minimum dead load pressure is assumed to be zero.
h) Piers should be reinforced their full length to resist tension forces and shall be capable of
resisting uplift due to a uniform swelling pressure of 1,500 psf applied over an 8 foot
length of each pier.
i) Piers should have a center-to-center spacing of at least 3 pier diameters when designing
for vertical loading conditions, or be designed as a group.
j) Piers aligned in the direction of lateral forces should have center-to-center spacing of at
least 6 pier diameters.
k) Piers should have a maximum length to diameter ratio of about 30 for constructability and
observation purposes.
l) Piers shall have a minimum diameter of 12 inches.
m) Piers shall have a minimum length of 25 feet below the foundation grade beam/wall. The
minimum pier shaft length is based on piers at the lowest portion of the basements’
foundation. Piers originating from upper floor levels shall extend to the same bottom
elevation as the piers in the basement.
n) Piers shall have a minimum penetration of 5 feet into competent bedrock (blow counts of
50/12 or harder).
o) A 4 inch minimum void space shall be provided beneath the grade beams spanning
between the piers and below all pier caps to achieve effective concentration of loads on
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the piers. Void forms should be protected before and during concrete placement.
p) Casing of a portion of the drilled shafts may be necessary to permit proper cleaning and
observation prior to placement of concrete. Casing may be necessary because of
groundwater conditions and caving through more than 3 inches of water, unless proper
tremie techniques are utilized to place concrete from the bottom of the shaft or the water
is removed. Drilled shafts shall not be allowed to remain open overnight.
q) Difficult drilling may be encountered in the very hard bedrock. Coring equipment may be
required. Pier penetration may not be decreased unless acceptable by the geotechnical
engineer.
r) Concrete for each pier should be formed at the top of the pier, if necessary, to achieve a
uniform diameter at the top of the pier and avoid “mushrooming”. Excess concrete or
overpour resulting in enlargement of the pier shall be removed.
s) Soil retainers, such as Sure Retainer, are recommended to keep backfill soil from entering
the void space beneath the foundation walls/grade beams.
t) Proper concrete mixture design for drilled shafts varies with the design stress intensity,
anticipated concrete placement procedures, and spacing of the reinforcement. It is
recommended that current design and construction procedures outlined by the ACI and
the International ADSC be followed. Per these guidelines, current practice is to use a
concrete mixture design slump in the range of 5 to 7 inches if casing is to be utilized or
the shaft is heavily reinforced. A design slump in the range of 7 to 9 inches with 3/4 inch
maximum size aggregate is recommended if concrete is to be plac ed by tremie or pumping
methods. Additional recommendations as outlined by ACI and ADCS should also be
followed.
u) Pier drilling should be observed by a Cesare representative in an effort to confirm that
actual subsurface conditions are consistent with those presented in this study. If
conditions deviate significantly, recommendations may need to be modified.
12. LATERAL EARTH PRESSURES
Lateral pressures on walls depend on the type of wall, hydrostatic pressure behind the wall, type of
backfill material, and allowable wall movements. Cesare recommends drain systems be constructed
behind walls to reduce the potential for hydrostatic pressures to develop. Where
anticipated/permissible wall movements are greater than 0.5% of the wall height, lateral earth
pressures can be estimated for an "active" condition. Where anticipated/permissible wall movement
is less than approximately 0.5% of the wall height or wall movement is constrained, lateral earth
pressures should be estimated for an "at rest" condition. Recommended lateral earth pressures for
onsite material are provided in Table 12.1.
The recommended values for lateral earth pressures provided in Table 12.1 are given in terms of an
equivalent fluid unit weight. The equivalent fluid unit weight multiplied by the depth below the top
of the ground surface is the horizontal pressure against the wa ll at that depth. The resulting pressure
distribution is a triangular shape. These soil pressures are for horizontal backfill with no surcharge
loading and no hydrostatic pressures. If these criteria cannot be met, Cesare should be contacted for
additional criteria.
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20.3059 Alpine Bank Report 12.01.20 9
Cesare understands that resistance to lateral loading for footing foundations may be a concern. The
recommended coefficients of sliding resistance between concrete and bearing soil are provided in
Table 12.1.
TABLE 12.1. Lateral Earth Pressures and Coefficients of Sliding Resistance for Onsite
Material
Backfill
Material Type
Equivalent Fluid Unit Weight
(pcf) Coefficient
of Sliding
Resistance Active At Rest Passive
Clay 50 70 305 0.35
Sand and gravel 45 65 395 0.4
13. INTERIOR FLOORS
The preexisting fill was likely placed at the same time the structure was built. Potential settlement of
the fill has likely been realized to a significant degree, but it is unknown if there is potential for
additional settlement after new construction is complete. To reduce the potential for movement of
the slabs-on-grade, all existing fill should be removed. Acceptable existing fill material or a suitable,
offsite material should be moisture conditioned and compacted in accordance with Section 16.
STRUCTURAL FILL/BACKFILL SOIL. To reduce the potential for slab movement, a structural floor
with an air space beneath is recommended.
If the existing fill is not removed and recompacted as recommended herein, there is a risk for slab
movement to occur. Movement can result in damage to the slab, as well as items supported on the
slab or partially on the slab and partially on foundation walls . Damage can consist of cracking, vertical
offsets, horizontal separation, tilting, or racking, etc. If the potential for slab movement cannot be
tolerated, a floor that is separated from the existing fill and structurally supported shall be
constructed.
If the owner chooses to construct a slab without removal of existing fill, at a minimum, the slab-on-
grade shall be properly jointed and separated from bearing members and utilities. In addition, the
exposed slab subgrade soil should be proof rolled and any soft areas redensified or stabilized with
structurally controlled fill.
13.1 OVEREXCAVATION CONSIDERATIONS
The overexcavation and recompaction to remove the existing fill should extend laterally at least 5
feet beyond the exterior footings and counterforts/building lines.
13.2 SLAB-ON-GRADE CONSTRUCTION DETAILS
Cracking of slabs-on-grade can occur as a result of heaving or compressing of the supporting soil but
also as a result of concrete curing stresses. If slab-on-grade floors are chosen, Cesare recommends
that design and construction of all interior slab-on-grade floors incorporate the following
considerations and precautions. These details will not reduce the amount of movement but are
intended to reduce potential damage should some settlement or heave of the supporting subgrade
take place. The ACI Committee 302, “Guide for Concrete Floor and Slab Construction (ACI 302.R-
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20.3059 Alpine Bank Report 12.01.20 10
96)” should be consulted regarding methods/techniques to reduce the occurrence of concrete
shrinkage cracks and other potential issues associated with concrete finishing and curing.
a) A vapor barrier is recommended beneath concrete slabs-on-grade that will support
equipment sensitive to moisture or will be covered with wood, tile, carpet, linoleum, or
other moisture sensitive or impervious coverings. Location of the vapor barrier should be
in accordance with recommendations provided by ACI 302.2R-06, “Guide for Concrete
Slabs that Receive Moisture-Sensitive Flooring Materials.” Further discussion of vapor
barriers is presented in Appendix C.
b) Plumbing beneath slabs should be eliminated, where practicable. Where such plumbing is
unavoidable, it should be thoroughly pressure tested during construction for leaks prior
to slab placement.
c) Conduits that are supported on the ground and extend under or through walls should
have a minimum void space of 3 inches above or below the conduit where it passes
through or under the wall to avoid pinching or collapsing of the conduit via ground heave.
d) Backfill in the utility trenches beneath slabs should be compacted as specified in Section
16. STRUCTURAL FILL/BACKFILL SOIL.
e) Plumbing and utilities that pass through the slab should be isolated from the slabs and
should be provided with flexible couplings above the floor that can be observed and
maintained, as necessary, to accommodate potential ground/slab movement.
f) Mechanical equipment or systems supported by slabs should be provided with flexible
connections or void space that allows for a minimum of 2 inches of movement between
the equipment on the slab and associated overhead ductwork, piping, or structural
members.
g) Where slab bearing partitions or stairs are necessary, a slip joint (i.e., partition framing
void or float) allowing at least 2 inches of vertical slab move ment should be used. Partition
framing voids constructed at the base of the wall can in some cases be more effective
than joints above the wall, particularly on long walls. The void space can be covered with
a molding strip. If finished, all furring strips, drywall, and paneling should stop at least 2
inches from the top of the slab if the slip joint is constructed at the bottom of the wall. In
the event of slab heave, the movement should not be transmitted directly though the
partitions or stairwells to the remainder of the structure.
h) Interior slab-supported partition walls should be isolated from foundation-supported
perimeter walls to accommodate slab movement.
i) Doorways should be constructed to allow vertical movement of slabs. Allowance for
vertical movement is typically accomplished by providing a gap below doorjambs.
j) CMU partition walls should be constructed with a minimum clearance of 2 inches between
the top of wall and the bottom of roof or ceiling elements.
k) Separate slabs from foundation walls, interior columns, and utilities with a joint which
allows/provides free vertical movement of the slab (i.e., floating slab construction).
l) Provide frequent control joints in the slab. Refer to ACI 302.1R-15.
m) Use of load transfer devices at construction and contraction joints is recommended when
positive load transfer is required (See ACI 302.1R).
Following the preceding recommendations will not completely eliminate the potential for movement
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20.3059 Alpine Bank Report 12.01.20 11
of the floor slab but should reduce damage caused by slab movement. The void spaces and flexible
joints recommended may not accommodate total potential slab movement. Care must be taken to
monitor and reestablish partition voids and flexible connections, when necessary.
13.3 STRUCTURALLY SUPPORTED FLOORS
A floor system that is supported by the foundation system and has an air or void space (typically a
crawlspace) below the floor so that it is not in contact with the underlying soil/bedrock material is
considered a structurally supported or structurally suspended floor. If potential movement of slab-
on-grade floors and associated cracking/distress are not considered tolerable by the owner,
developer, architect, or structural engineer for any reason, a structurally supported floor should be
provided.
There are design and construction issues associated with structurally supported floors that must be
considered, such as ventilation and lateral loads. Where structurally supported floors are installed,
the minimum required air space depends on the material used to construct the floor and the
expansion potential of the underlying soil. Building codes require a clearance space of at least 18
inches above exposed soil if untreated wood floor components are used. Where other support
material is used, a minimum clearance space of 8 inches is recommended. This minimum clearance
space should be maintained between any point on the underside of the floor system (including beams
and plumbing) and the surface of the exposed earth. The minimum clearance between the crawlspace
ground surface and the structural floor members and suspended plumbing should be constructed to
meet minimum code or recommended clearances, plus the recommended void space.
Where structurally supported floors are used, utility connections, including water, gas, air duct, and
exhaust stack connections to floor supported appliances should be capable of absorbing some
deflection of the floor. Plumbing that passes through the floor should ideally be hung from the
underside of structural floor and not lay on the bottom of the excavation. This configuration may not
be achievable for some parts of the installation. It is prudent to maintain the minimum clearance
space below all plumbing lines. If trenching below the lines is necessary, Cesare recommends sloping
these trenches so they discharge to the foundation drain. Penetrations through the foundation wall
should allow for at least 3 inches of clearance and/or be provided with flexible connections. The
ground surface below the structurally supported floor should be sloped to the perimeter drain.
Control of humidity in crawlspaces is important for indoor air quality and performance of wood floor
systems. The Moisture Management Task Force of Metro Denver has compiled additional discussion
and recommendations regarding best practices for control of humidity in below grade, underfloor
spaces. An engineering professional with expertise in the design and construction of crawlspace
humidity control should be contacted.
14. EXTERIOR FLATWORK
Exterior flatwork is susceptible to movement resulting from moisture sensitive soil and existing fill
onsite, as discussed for interior floor slabs in Section 13. INTERIOR FLOORS. Flatwork supported
on foundation wall backfill may settle and crack if the backfill is not properly moisture conditioned
and compacted. To reduce potential movement of exterior flatwork, Cesare recommends removing,
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20.3059 Alpine Bank Report 12.01.20 12
moisture conditioning, and replacing the upper 12 inches of soil beneath the exterior flatwork.
Overexcavating and moisture conditioning will reduce movement potential, create a relatively
impervious surface over moisture sensitive material, and retard wetting of the deeper unconditioned
moisture sensitive material. This conditioning will reduce potential slab-on-grade movement but will
not eliminate it.
Exterior flatwork should be isolated from the structures. Exterior flatwork should be expected to
move, although measures can be incorporated into construction to limit the movement or effects of
the movement. Cesare recommends flatwork not be doweled into structure foundations, but rather
supported on a haunch to limit settlement. The haunch should extend the full length of the slab. To
reduce potential movement, the soil below the planned flatwork can be moisture conditioned or
chemically treated. A lower risk approach is to construct a slab over void forming material and/or
support the slab with a foundation meeting the same criteria as the structure.
Exterior flatwork, such as driveways and sidewalks, are normally constructed as slabs-on-grade.
Porches and patios are increasingly constructed as structurally supported slabs, which in Cesare’s
opinion, is the most positive means of keeping slabs from moving and adversely affecting the
operation of doors or means of egress. Cesare recommends that landings and slabs at egress doors,
as well as porches and patios, be constructed as structurally supported elements if potential
movement cannot be tolerated.
Simple decks that are not integral to the structure and can tolerate foundation movement can be
constructed with less substantial foundations. A short pier or footing bottomed below frost depth can
be used if movement is acceptable and if acceptable by local building requirements. Use of deeper
foundation elements can reduce potential movement. Footings or short piers should not be underlain
by wall backfill, due to risk of settlement. Inner edges of decks may be constructed on haunches and
detailed such that movement of the deck foundations will not cause distress to the structure.
Cesare recommends use of connections or other details between foundations and deck posts, so the
posts can be trimmed or adjusted if movement occurs.
14.1 OVERHANGING ROOFS
Porches, patios, or decks with overhanging roofs that are integral to the structure, such that
foundation movement cannot be tolerated, should be constructed with the same foundation type as
the structure.
15. EXCAVATIONS
Conventional earthmoving equipment should be adequate to excavate the onsite soil/and bedrock.
All excavations should be properly sloped and/or braced, and local and federal safety codes should
be observed. Slopes and other areas void of vegetation should be protected against erosion.
It is the contractor’s responsibility to provide safe working conditions and comply with the regulations
in OSHA Standards-Excavations, 29 CFR Part 1926. The following guidelines are provided for planning
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20.3059 Alpine Bank Report 12.01.20 13
purposes. Sloping and shoring requirements must be evaluated at the time of construction by the
contractor’s competent person as defined by OSHA. OSHA classifications for various material types
and the steepest allowable slope configuration corresponding to those classifications are shown in
Table 15.1.
TABLE 15.1. Allowable Slope Configuration for Onsite Material
Material Type
OSHA
Classification
Steepest Allowable
Slope Configuration*
Claystone Type A 3/4:1
Clay Type B 1:1
Fill, sand, weathered sandstone Type C 1-1/2:1
* Units horizontal to units vertical. The values shown apply to excavation less than 20 feet in height. Conditions can
change and evaluation is the contractor’s responsibility.
The preceding classifications and slope configurations assume that excavations are above the
groundwater table, there is no standing water in the excavations, and there is no seepage from the
slope into the excavations, unless otherwise specified. The preceding classifications and slope
configurations assume that the material in the excavations is not fractured, adversely bedded,
jointed, nor left open to desiccate, crack, or slough, and is protected from surface runoff. There are
other considerations regarding allowable slope configurations that the contractor is responsible for,
including proximity of equipment, stockpiles, and other surcharge loads to the excavation. The
contractor’s competent person is responsible for all decisions regarding slope configuration and safety
conditions for excavations.
Excavations should not undermine existing foundation systems of structures or infrastructure unless
they are adequately protected. At a minimum, new excavations should not intersect a line drawn on
a 45 degree angle down and away from the bottom edge of the existing foundation systems or
bottom edge of infrastructure. If this condition cannot be met, shoring or staged excavations may be
required. If shoring is required, a condition survey of the adjacent structures is recommended before
construction starts and upon completion of construction. In Cesare’s experience, condition surveys
include, but may not be limited to photographs of any distress to adjacent structures.
Permanent slopes should be no steeper than 3:1 and should be revegetated or otherwise protected
from erosion.
16. STRUCTURAL FILL/BACKFILL SOIL
Where fill/backfill soil is necessary, the suitable onsite inorganic soil may be used below, around, and
above the structure. At this site, unsuitable material is defined as topsoil, organics, trash, ash, frozen
material, hard lumps, and clods, claystone, and particles larger than 3 inches. Existing onsite fill
material can be reused for structural fill/backfill, provided it is free of unsuitable material. If unsuitable
material is encountered in the existing fill, it cannot be reused as fill/backfill. Recommendations for
fill/backfill placement are:
a) Clods, lumps, or hard pieces of clay or claystone shall be broken down to a maximum size
of 3 inches. Pieces larger than 3 inches shall be removed from the fill/backfill.
b) Fill/backfill material should be placed in loose lifts and compacted in accordance with
Table 16.1.
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20.3059 Alpine Bank Report 12.01.20 14
c) Maximum loose lift thickness shall be 6 inches, depending on the type of equipment used
to apply compactive effort, and shall be reduced if the specified compaction cannot be
obtained with the equipment used.
d) Fill/backfill should not be placed if material is frozen or if the surface upon which fill/backfill
is to be placed is frozen.
e) Fill/backfill material should be placed and spread in horizontal lifts of uniform thickness in
a manner that avoids segregation.
f) Placement surface should be kept free of standing water, debris, and unsuitable material
during placement and compaction of fill/backfill material.
g) Fill/backfill maximum allowable particle size is 3 inches. Do not incorporate oversize
material in the fill/backfill that is incapable of being broken down by the equipment and
methods being employed to process and compact the fill/backfill. Process and compact
material in the lift, as necessary, to produce the specified fill/backfill characteristics. If
oversize particles remain in the lift after processing and compacting, remove oversize
material to produce a fill/backfill within specified requirements.
h) Overlot fill placement and compaction should be observed and tested on a full-time basis
by a representative of Cesare. At a minimum, utility trench backfill should be tested in
accordance with jurisdictional requirements.
TABLE 16.1. Compaction Specifications
Material Type
(General)
AASHTO
Classification
Material
Thickness
(ft)
Moisture
Content
(%)
Relative
Compaction
(%)
Compaction
Standard
Granular material
that is clean to
silty
A-1, A-2-4,
A-2-5,
A-3, A-4, A-5
<15 + 2% of
OMC >95%
Standard
Proctor
(ASTM D698)
Fine grained
material and
granular material
with plastic fines
A-2-6, A-2-7
A-6
A-7
<15
0% to
+3% of
OMC
>95%
Standard
Proctor
(ASTM D698)
* If fill thickness greater than 20 feet is planned, additional requirements may apply.
16.1 IMPORT FILL
Material imported for structural fill should be tested and approved for use onsite by the project
geotechnical engineer prior to hauling to the site. Proctor, remolded swell, and classification tests
should be conducted to determine if the fill meets required specifications. Fill material should be well
graded, low permeable material meeting the specifications in Table 16.2.
TABLE 16.2. Import Fill Specifications
Soil Parameter Specification
Maximum particle size 1 inch
Percent finer than No. 200 sieve 20% to 40%
Liquid limit 20% to 40%
Plasticity index 8% to 15%
Swell potential under anticipated loads less than 1%*
* Upon inundation, when remolded to 97% maximum dry density at 1% below the
optimum moisture content per ASTM D698 at a surcharge pressure of 100 psf.
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20.3059 Alpine Bank Report 12.01.20 15
17. SUBSURFACE DRAINAGE
Groundwater was encountered at depths of 8.4 feet to 17 feet during this study. Since the structure
has no basement, crawlspace, or other below grade space, a subsurface drain is not considered
necessary for this structure. If below grade construction, such as a crawlspace or basement, is
considered for this structure, Cesare should be notified to review this recommendation. If a structural
floor is selected, consideration should be given to installing a sump pump at the lowest portion of
the voided area.
18. SURFACE DRAINAGE
Good drainage and surface water management is important. Performance of site improvements, such
as foundations, floors, hardscape, and pavement is often adversely affected by failing to establish
and/or maintain good site drainage. Grades must be adjusted to provide positive drainage away from
the structure, pavement, and other site improvements during construction and maintained
throughout the life of the proposed facility. The following drainage precautions are recommended:
a) The ground surface around the perimeter foundation walls should be sloped to drain away
from the structure in all directions. Current building codes require a minimum slope of 6
inches in the first 10 feet of the structure (5%). At the completion of construction, Cesare
recommends a continuous slope away from foundations of 12 inches in the first 10 feet
(10%), where site constraints permit. Cesare recommends that concrete and pavement
adjacent to structures slope at a rate of at least 2% away from the structure or as
otherwise required by ADA criteria. Maximum grades practical should be used for paving
and flatwork to prevent areas where water can pond.
b) Joints that occur at locations where paving or flatwork abuts the structure should be
properly sealed with flexible sealants and maintained.
c) The ground surface should be sloped so that water will not pond between or adjacent to
structures and other site improvements. Curbs, sidewalks, paths, plants, or other
improvements should not block, impede, or otherwise disrupt surface runoff. Use of
chases and weep holes to promote drainage is encouraged. Landscape edging should be
perforated or otherwise constructed in a manner to prevent ponding of surface water,
especially in the vicinity of the backfill soil.
d) Drainage swales should be located as far away from the foundation as practicable.
e) If site constraints do not allow for the recommended slopes, the project civil engineer
shall provide a method for drainage that is equivalent to the recommendations herein.
Water should not be allowed to pond adjacent to or near foundations, flatwork, or other
improvements.
f) Roof downspouts and other water collection systems should discharge onto pavements or
extend away from the structure well beyond the limits of the backfill zone using
downspout extensions, appropriately sized splash blocks, or other means. Buried
downspout extensions are discouraged as they can be difficult to monitor and maintain.
g) Irrigation directly adjacent to the structure is discouraged and should be minimized.
Sprinkler lines, zone control boxes, and sprinkler drains shall be located outside the limits
of the foundation backfill. Sprinkler systems should be placed so that the spray from the
heads, under full pressure, does not fall within 5 feet of the foundation walls.
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20.3059 Alpine Bank Report 12.01.20 16
h) Plants, vegetation, and trees that require moderate to high water usage are discouraged
and should not be located within 5 feet of foundation walls.
i) Plantings that are desired within 10 feet of the foundation should be placed in watertight
planters/containers.
j) The project civil engineer shall perform measurements to document that positive
drainage, as described in this section or as otherwise designed by the project civil
engineer, is achieved. Maintenance of surface drainage is imperative subsequent to
construction and is the responsibility of the owner and/or tenant.
19. PAVEMENT RECOMMENDATIONS
19.1 DESIGN CRITERIA
The pavement recommendations contained in this report are based on Larimer County Urban Area
Street Standards and the design parameters indicated in Table 19.1.
TABLE 19.1. Pavement Design Parameters
Design Parameter Value
Design period (years) 20
Initial serviceability (s) 4.5
Terminal serviceability (t) 2.0
Serviceability loss, (s-t) 2.5
Reliability, Zr (%) 75
Overall standard deviation, So 0.44
Total 18 kip ESAL’s
Automobile parking
Drive lanes and entry drives
73,000
365,000
Subgrade strength
R-value (measured)
Resilient modulus, Mr (psi) (by correlation to R-value per CDOT)
9
3,400
Strength coefficients for:
a. APM
b. ABC (R-value>72)
0.44
0.11
Deviation from the preceding parameters will require a revision to the recommended pavement
section thicknesses. If the subgrade becomes saturated, the pavement is not properly maintained,
and/or the actual traffic is greater than the values used in the design, the design service life will be
reduced.
19.2 SPECIAL CONCERNS
19.2.1 Frost Heave
The gravel, sand, and clay soil encountered onsite has low to high susceptibility to frost heave. The
presence of water is required for frost heave to occur. Groundwater was not encountered during this
study to depths of 8.4 feet below existing grade. In Cesare’s opinion, infiltration of surface water is
the most likely source for moisture in the pavement section. Maintaining surface drainage and
regularly sealing cracks will keep the potential for distress due to frost heave low and will help
increase longevity of pavement.
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20.3059 Alpine Bank Report 12.01.20 17
19.3 PAVEMENT THICKNESSES
Most of the shallow subgrade soil consists of clay, sand, and gravel. According to FHWA-RD-97-083
Design Pamphlet for the Determination of Design Subgrade in Support of the 1993 AASHTO Guide
for the Design of Pavement Structures, dated September 1997, this material is considered poor to
excellent for pavement subgrade. Fort Collins typically does not allow full depth pavement sections
on its right-of-way, however; Cesare understands that the parking lot will be private. The
recommended pavement sections are shown on Table 19.2.
TABLE 19.2. Recommended Pavement Section Thicknesses
Traffic Area Alternate
APM
(in)
ABC
(in)
PCC
(in)
Prepared
Subgrade
(in)
Total
Thickness
(in)
Light duty (car and
pickup parking only)
APM 6.5 -- -- 12.0 18.5
APM+ABC 4.5 8.0 -- 12.0 24.5
Standard duty (drive
lanes, fire lanes, and
truck access)
APM 8.0 -- -- 12.0 20.0
APM+ABC 5.0 12.0 -- 12.0 29.0
Trash dumpster
approaches and other
areas subject to
concentrated and
repetitive loading
conditions
PCC -- -- 12.0 12.0 24.0
19.4 TRASH DUMPSTER APPROACHES
The approaches to trash dumpsters typically experience a greater frequency of distress due to higher
loading conditions. To reduce the risk of increased maintenance, Cesare recommends paving these
areas with concrete. CDOT Class P portland cement concrete is recommended. Cesare recommends
control joints spaced at a maximum spacing of 12 feet, and at least one control joint transverse and
longitudinal to each approach. The approach to the trash dumpst er should be large enough to include
the collection truck’s runup braking distance and its front wheels should fully bear on the slab when
positioning and emptying the dumpster.
19.5 SUBGRADE PREPARATION AND PAVEMENT CONSTRUCTION
19.5.1 Pavement Subgrade
At least the top 12 inches of the subgrade should be uniformly moisture conditioned in accordance
with Table 16.1. Blading, tilling, windrowing, watering, or drying shall be performed, as needed, to
achieve the moisture/density specification to the required depth. It is Cesare’s experience that
scarifying to a depth of 12 inches in-place and attempting to compact 12 inches of scarified material
in one lift is usually not successful in achieving a uniformly moisture conditioned and adequately
compacted subgrade.
The entire subgrade should be proof rolled a maximum of 24 hours prior to paving with a loaded 988
front end loader or similar heavy rubber tired vehicle (GVW of 50,000 pounds with 18 kip per axle at
tire pressures of 90 psi) to detect any soft or loose areas. All areas exhibiting unstable subgrade
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20.3059 Alpine Bank Report 12.01.20 18
conditions, such as rutting, pumping, or excessive movement should be overexcavated to a firm soil
layer or to a maximum depth of 2 feet, whichever is shallowest, and replaced with suitable compacted
fill. If unstable subgrade conditions persist, Cesare should be contacted for consultation. Soft spots
should be stabilized prior to placement of pavement sections. Positive drainage off paved surfaces
should be provided.
Very moist to wet subgrade conditions should be anticipated in areas where existing pavement,
especially cracked and distress pavement, will be removed. These areas typically require additional
subgrade preparation in the form of drying and/or overexcavating to provide a subgrade that will
support paving operations. If unstable subgrade conditions are encountered, Cesare should be
contacted for recommended mitigation procedures.
19.5.2 Subbase and Aggregate Base Course
Subbase and ABC should meet the following requirements:
ABC material should be approved prior to construction and should subsequently be tested
as the material is being placed.
ABC should have an R-value greater than 72.
ABC material should be compacted to a minimum of 95% of the MDD as determined by
the modified Proctor test, ASTM D1557.
19.5.3 Pavement
Pavement construction shall be in accordance with the following recommendations and criteria:
APM shall meet the requirements in the Larimer County Urban Area Street Standards.
Asphalt binder grade shall be PG 64-22 or PG 58-28, NDesign of 50 or 75.
Approved APM should be placed in the lifts indicated on Table 19.3.
TABLE 19.3. Pavement Section Lift Thickness Recommendations
Grade Lift Thickness
(in)
S 2 to 4-1/4
SX 1-1/2 to 2-1/2
Per MGPEC 2019.
APM shall be compacted to 92% to 96% of the maximum theoretical density within 0.3%
of the optimum asphalt content as determined by ASTM D2041.
APM placement specifications should follow Larimer County specifications and industry
standards as recommended by the NAPA and the AI.
Portland cement concrete should be obtained from an approved mixture design with
minimum properties meeting a CDOT Class P mixture.
Portland cement concrete placement specifications should follow industry standards as
recommended by the ACI and the PCA.
Positive drainage off paved surfaces should be provided.
Construction material should be approved prior to use and subsequently tested as this
material is being placed.
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20.3059 Alpine Bank Report 12.01.20 19
20. SOIL CHEMICAL TESTING
20.1 SULFATE EXPOSURE
A water soluble sulfate content of 0.00% was measured on a sample from Boring B-3. Results are
summarized in Appendix B. The PCA publication titled Design and Control of Concrete Mixtures 2002
and the ACI publication titled Building Code Requirements for Structural Concrete and Commentary
consider this range nil for water soluble sulfate exposure. Recommendations for all concrete which
will be in contact with or within 6 inches of the soil are shown in Table 20.1.
TABLE 20.1 Information from ACI 318-08 - Table 4.3.1
Refer to ACI 318-08 R4.3.1 for further interpretation of this table.
21. GEOTECHNICAL RISK
The concept of risk is an important aspect of any geotechnical study. The primary reason for this is
that the analytical methods used by geotechnical engineers are generally empirical and must be
tempered by engineering judgment and experience, therefore, the solutions or recommendations
presented in any geotechnical study should not be considered risk free, and more importantly, are
not a guarantee that the interaction between the soil and the proposed construction will perform as
predicted, desired, or intended. The engineering recommendations presented in the preceding
sections constitute Cesare’s best estimate of those measures that are necessary to help the
structure/pavement perform in a satisfactory manner based on the information generated during this
study, training, and experience in working with these conditions.
Water
Soluble
Sulfates
(%)
Exposure
Class
Maximum
(w/cm)*
Minimum
f’c,
(psi)
Cementitious materials† (types)
Calcium
Chloride
Admixture
ASTM
C150 ASTM C595
ASTM
C1157
<0.10 S0 N/A 2,500 No type
restriction No type restriction No type
restriction
No
restriction
0.10≤ to
<0.20
S1
Moderate 0.50 4,000 II‡
IP (MS)
IS (<70)
(MS)
MS No
restriction
≤0.20 to
≤2.00
S2
Severe 0.45 4,500 V§
IP (HS)
IS (<70)
(HS)
HS Not
permitted
>2.00
S3
Very
Severe
0.45 4,500
V +
pozzolan or
slagII
IP (HS)+pozzolan
or slagII or
IS (<70)
(HS)+pozzolan or
slagII
HS+pozzolan
or slagII
Not
permitted
*For lightweight concrete, see ACI 318-08 4.1.2.
†Alternative combinations of cementitious materials of those listed in Table 4.3.1 shall be permitted when tested for sulfate resistance and meeting
the criteria in ACI 318-08 4.5.1.
‡For seawater exposure, other types of Portland cements with tricalcium aluminate (C3A) contents up to 10 percent are permitted if the w/cm does
not exceed 0.40.
§Other available types of cement such as Type III or Type I are permitted in Exposure Classes S1 or S2 if the C3A contents are less than 8 or 5
percent, respectively.
II The amount of the specific source of the pozzolan or slag to be used shall not be less than the amount that has been determined by service
record to improve sulfate resistance when used in concrete containing Type V cement. Alternatively, the amount of the specific source of the
pozzolan or slag to be used shall not be less than the amount tested in accordance with ASTM C1012 and meeting the criteria in ACI 318-08
4.5.1.
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22. LIMITATIONS
This document has been prepared as an instrument of service for the exclusive use of Goulding
Development Advisors, LLC for the specific application to the project as discussed herein and has
been prepared in accordance with geotechnical engineering practices generally accepted in the state
of Colorado at the date of its preparation. No warranties, either expressed or implied, are intended
or made. This document should not be assumed to contain information for other parties or other
purposes.
The findings of this study are valid as of the date its preparation. Changes in the conditions of a
property can occur with the passage of time, whether due to natural processes or the works of people
on this or adjacent properties. Standards of practice evolve in engineering and changes in applicable
or appropriate standards may occur, whether they result from legislation or the broadening of
knowledge. Accordingly, the findings of this study may be invalidated wholly or partially by changes
outside of Cesare’s control, therefore, this study is subject to review and should not be relied upon
without such review after a period of 3 years.
In the event that changes, including but not limited to, the nature, type, design, size, elevation, or
location of the project or project elements as outlined in this report are made, the conclusions and
recommendations contained in this report shall not be considered valid unless Cesare reviews the
changes and either confirms or modifies the conclusions of this report in writing.
Cesare should be retained to review final plans and specifications that are developed for proposed
construction to judge whether the recommendations presented in this report and any addenda have
been appropriately interpreted and incorporated in the project plans and specifications as intended.
The exploration locations for this study were selected to obtain a reasonably accurate depiction of
underground conditions for design purposes and these locations are often modified based on
accessibility and the presence of underground or overhead utility conflicts. Variations from the soil
conditions encountered are possible. These variations may necessitate modifications to Cesare’s
design recommendations, therefore, Cesare should be retained to observe subsurface conditions,
once exposed, to evaluate whether they are consistent with the conditions encountered during
Cesare’s exploration and that the recommendations of this study remain valid. If parties other than
Cesare perform these observations and judgements, they must accept responsibility to judge whether
the recommendations in this report remain appropriate.
Cesare’s scope of services for this report did not include either specifically, or by implication, any
environmental assessment of the site or identification of contaminated or hazardous material or
conditions. Additionally, none of the services performed in connection with this study were designed
or conducted for the purpose of mold prevention. Proper implementation of the recommendations
conveyed in this report will not, of itself, be enough to prevent mold from growing in or on the
structures involved.
CESARE, INC.
20.3059 Alpine Bank Report 12.01.20 21
At a minimum, Cesare should be retained during construction to observe and/or test the following:
completed excavations.
placement and compaction of fill.
pier drilling operations.
proposed import or onsite fill material.
placement and compaction of pavement subgrade, subbase, base course and asphalt.
Cesare offers many other construction observations, materials engineering, and testing services and
can be contacted to discuss further.
FIGURE 1
Vicinity Map
PROJECT NO:
PROJECT NAME:
20.3059
Alpine Bank
--
DRAWN BY:CHECKED BY:JBE YES
DWG DATE:11.13.20 REV. DATE:
0 2,500'5,000'
APPROXIMATE SCALE: 1 INCH = 5,000 FEET
NW:\2020\Frederick\20.3059.A Alpine Bank\ACAD\Boring Location Map.dwg 11/13/2020 2:59 PMBACKGROUND IMAGE FROM GOOGLE EARTH
FIGURE 2
Boring Location Plan
PROJECT NO:
PROJECT NAME:
20.3059
Alpine Bank
--
DRAWN BY:CHECKED BY:JBE YES
DWG DATE:11.06.20 REV. DATE:
0 60'120'
APPROXIMATE SCALE: 1 INCH = 60 FEET
NW:\2020\Frederick\20.3059.A Alpine Bank\ACAD\Boring Location Map.dwg 11/13/2020 2:43 PMSITE PLAN PROVIDED BY CLIENT
LEGEND:
B-1 BORING NUMBER AND
APPROXIMATE LOCATION
B-1
B-3
B-2
B-4
APPENDIX A
Field Exploration
CESARE, INC.
20.3059 Alpine Bank Field Exploration Appendix A 1
FIELD EXPLORATION DRILLING
Samples of the subsoil were obta ined at this site using a modified California sampler which was driven
into the soil by dropping a 140 pound hammer through a free fal l of 30 inches. The modified California
sampler is a 2-1/2 inch outside diameter by 2 inch inside diameter device lined with brass tubes. The
procedure to drive the modified California sampler into the soil and to record the number of blows
required to drive the sampler into the soil is known as a penetration test. The number of blows
required for the sampler to penetrate 12 inches gives an indication of the relative stiffness of cohesive
soil, relative density of non-cohesive soil, and relative hardness of sedimentary bedrock material
encountered. Bulk samples were collected from cuttings generated during drilling. Locations of
sampling and penetration test results are presented on the boring logs contained in this Appendix.
0.33
11
17
20
7
7
109.67
99
93
90
Asphalt
FILL: GRAVEL, with silt and sand, to SAND, with gravel, silt, and clay, dense, moist, mottled, brown, (GP-GM) to (SP-SM).
CLAY, with sand to sandy, stiff, moist, reddish brown to brown to gray, (CL). Gasoline odor at 14' and 19' samples.
SAND, well-graded, medium dense, wet, brown, (SW).
Boring terminated at 20 feet
39/12
36/12
45/12
13/12
22/12DEPTH (ft)MODIFIED CALIFORNIA SAMPLER
DEPTH OF REFUSAL
#
#
WATER LEVEL AT TIME OF DRILLING
LEGEND
WATER LEVEL # DAYS AFTER DRILLING
DEPTH OF CAVE # DAYS AFTER DRILLING
PROJECT NAME
BORING LOCATION
DRILLING COMPANY/RIG
Alpine Bank
See Figure 1
Odell Drilling/CME-45
DRILLING METHOD
HAMMER SYSTEM
4in. Diameter SSA
Automatic Hammer
PROJECT NUMBER 20.3059
BORING ELEVATION
CESARE REP.
DATE STARTED
DATE COMPLETED
J. Edwards
11/2/2020
11/2/2020 Page 1 of 1
B-1110ft.
DEPTH (ft)DEPTH (ft)ELEVATION (ft)MATERIAL DESCRIPTIONSAMPLEGRAPHIC LOGBLOW COUNT5
10
15
20
4
12
15
29
7
7
97
89
86
72
FILL: CLAY, sandy, stiff, moist, slightly calcareous, mottled red to brown, (CL).
CLAY, sandy, stiff to very stiff to SAND, clayey, medium dense, moist to very moist, brown, (CL) to (SC).
WEATHERED SANDSTONE, silty, firm, wet, brown, (SM).
CLAYSTONE, with sand to sandy, with lenses of fine-grained sandstone, very hard, moist, gray to brown, (CL).
Boring terminated at 29 feet
50/2
50/2
50/0DEPTH (ft)MODIFIED CALIFORNIA SAMPLER
DEPTH OF REFUSAL
#
#
WATER LEVEL AT TIME OF DRILLING
LEGEND
WATER LEVEL # DAYS AFTER DRILLING
DEPTH OF CAVE # DAYS AFTER DRILLING
PROJECT NAME
BORING LOCATION
DRILLING COMPANY/RIG
Alpine Bank
Odell Drilling/CME-45
DRILLING METHOD
HAMMER SYSTEM
4in. Diameter SSA
Automatic Hammer
PROJECT NUMBER 20.3059
BORING ELEVATION
CESARE REP.
DATE STARTED
DATE COMPLETED
J. Edwards
11/2/2020
11/2/2020 Page 1 of 1
B-2101ft.
DEPTH (ft)DEPTH (ft)ELEVATION (ft)MATERIAL DESCRIPTIONSAMPLEGRAPHIC LOGBLOW COUNT5
10
15
20
25
0.25
11
14.5
29.25
7
7
99.75
89
85.5
70.75
Asphalt
FILL: CLAY, sandy, stiff, moist, mottled, reddish brown to brown, (CL).
SAND, silty, medium dense, wet, brown, (SM).
CLAYSTONE, with sand to sandy, with lenses of fine-grained sandstone, very hard, moist, gray to brown, (CL).
Boring terminated at 29.25 feet
50/3
50/2
50/3DEPTH (ft)MODIFIED CALIFORNIA SAMPLER
DEPTH OF REFUSAL
#
#
WATER LEVEL AT TIME OF DRILLING
LEGEND
WATER LEVEL # DAYS AFTER DRILLING
DEPTH OF CAVE # DAYS AFTER DRILLING
PROJECT NAME
BORING LOCATION
DRILLING COMPANY/RIG
Alpine Bank
Odell Drilling/CME-45
DRILLING METHOD
HAMMER SYSTEM
4in. Diameter SSA
Automatic Hammer
PROJECT NUMBER 20.3059
BORING ELEVATION
CESARE REP.
DATE STARTED
DATE COMPLETED
J. Edwards
11/2/2020
11/2/2020 Page 1 of 1
B-3100ft.
DEPTH (ft)DEPTH (ft)ELEVATION (ft)MATERIAL DESCRIPTIONSAMPLEGRAPHIC LOGBLOW COUNT5
10
15
20
25
0.25
6
14
29
7
7
103.75
98
90
75
Asphalt
FILL: CLAY, sandy, stiff, moist, mottled, reddish brown to brown, (CL).
CLAY, sandy, stiff, moist, calcareous, reddish brown, (CL).
CLAYSTONE, with sand to sandy, with lenses of fine-grained sandstone, very hard, moist, gray to brown, (CL).
Boring terminated at 29 feet
50/2
50/4
50/0DEPTH (ft)MODIFIED CALIFORNIA SAMPLER
DEPTH OF REFUSAL
#
#
WATER LEVEL AT TIME OF DRILLING
LEGEND
WATER LEVEL # DAYS AFTER DRILLING
DEPTH OF CAVE # DAYS AFTER DRILLING
PROJECT NAME
BORING LOCATION
DRILLING COMPANY/RIG
Alpine Bank
Odell Drilling/CME-45
DRILLING METHOD
HAMMER SYSTEM
4in. Diameter SSA
Automatic Hammer
PROJECT NUMBER 20.3059
BORING ELEVATION
CESARE REP.
DATE STARTED
DATE COMPLETED
J. Edwards
11/2/2020
11/2/2020 Page 1 of 1
B-4104ft.
DEPTH (ft)DEPTH (ft)ELEVATION (ft)MATERIAL DESCRIPTIONSAMPLEGRAPHIC LOGBLOW COUNT5
10
15
20
25
APPENDIX B
Laboratory Testing
CESARE, INC.
20.3059 Alpine Bank Laboratory Testing Appendix B 1
LABORATORY TESTING
Swell/consolidation testing was performed on samples collected using a modified California sampler
to evaluate the effect of wetting and loading on the soil. The samples were loaded to either 500 or
1,000 psf and then inundated with water.
BoringDepth (feet)Gravel (%)Sand (%)Silt/Clay (%)Liquid Limit (%)Plasticity Index (%)Inundation Pressure (psf)Volume Change (%)Swell Pressure (psf)B-1 4 1.5 56 39 5 NV NPFILL; GRAVEL, with silt and sand, brown, (GP-GM), A-1-a(0)B-2 9 110.5 18.61,000 0.3 1,550CLAY, sandy, brownB-2 19 102.8 15.81,000 -0.3 NACLAYSTONE, sandy, brownB-3 0.5 to 5 0.00 9 1 33 66 38 21FILL; CLAY, sandy, brown, (CL), A-6(11)B-3 4 99.5 22.2500 0.6 1,575CLAY, sandy, reddish brownB-3 14 17.8 0 60 40 NV NPSAND, silty, brown, (SM), A-4(0)NA = not applicableNP = non plasticNV = no valueSUMMARY OF LABORATORY TEST RESULTSSample Location GradationAlpine BankProject No. 20.3059Natural Dry Density (pcf)Natural Moisture Content (%)Material TypeSwell/ConsolidationAtterberg LimitsWater Soluble Sulfates(%) R-value20.3059 Alpine Bank Summary of Lab Test ResultsPage 1 of 1
Project Number:Date:
Project Name:Technician:
Lab ID Number:Reviewer:
Sample Location:
Visual Description:
AASHTO M 145 Classification:A-6 Group Index: 11
(CL)Sieve Size% Passing2"
1.5"
1"
3/4"
1/2"
3/8" 100
#4 99
#8
#10 94
#16 91
#30
#40 83
#50 79
#100 73
#200 65.5
M, %: 19.0
D, pcf:
LL 38
PL 17
PI 21
D60
D30
D10
Cu
Cc
GRADATION PLOT - SOIL & AGGREGATE
4-Nov-20
G. Hoyos
B-3 at 0.5' to 5'
2021310 Y. Schimmel
20.3059, Goulding Development
Alpine Bank
FILL; CLAY, sandy, brown
Moisture (M) &
Density (D)
Sandy lean clay
Unified Soil Classification System
(ASTM D 2487):37.51.5"25.41"19.13/4"12.71/2"3/8"4.75No. 42.00No. 101.18No. 160.43No. 400.30No. 500.15No. 1000.075No. 2002.36No. 80.60No. 3050.82"0
10
20
30
40
50
60
70
80
90
100
0.010.101.0010.00100.00% PASSING (by dry mass)SIEVE SIZE, mm
Gradation 2021310
Corporate: 7108 South Alton Way, Building B • Centennial, Colorado 80112
Phone 303-220-0300 • www.cesareinc.com Rev. 3/30/12
Project Number:Date:
Project Name:Technician:
Lab ID Number:Reviewer:
Sample Location:
Visual Description:
AASHTO M 145 Classification:A-1-a Group Index: 0
(GP-GM)Sieve Size% Passing2"
1.5" 100
1" 82
3/4" 72
1/2" 60
3/8" 54
#4 44
#8
#10 34
#16 28
#30
#40 17
#50 13
#100 8
#200 4.8
M, %: 1.5
D, pcf:
LL NV
PL NP
PI NP
D60 12.70
D30 1.40
D10 0.21
Cu 60.48
Cc 0.74
FILL; GRAVEL, with silt and sand, brown
Moisture (M) &
Density (D)
Poorly graded gravel with silt and sand
Unified Soil Classification System
(ASTM D 2487):
GRADATION PLOT - SOIL & AGGREGATE
4-Nov-20
G. Hoyos
B-1 at 4'
2021311 Y. Schimmel
20.3059, Goulding Development
Alpine Bank
37.51.5"25.41"19.13/4"12.71/2"3/8"4.75No. 42.00No. 101.18No. 160.43No. 400.30No. 500.15No. 1000.075No. 2002.36No. 80.60No. 3050.82"12.70 1.40 0.21
0
10
20
30
40
50
60
70
80
90
100
0.010.101.0010.00100.00% PASSING (by dry mass)SIEVE SIZE, mm
Gradation 2021311
Corporate: 7108 South Alton Way, Building B • Centennial, Colorado 80112
Phone 303-220-0300 • www.cesareinc.com Rev. 3/30/12
Project Number:Date:
Project Name:Technician:
Lab ID Number:Reviewer:
Sample Location:
Visual Description:
AASHTO M 145 Classification:A-4 Group Index: 0
(SM)Sieve Size% Passing2"
1.5"
1"
3/4"
1/2"
3/8"
#4 100
#8
#10 100
#16 100
#30
#40 100
#50 97
#100 91
#200 39.6
M, %: 17.8
D, pcf:
LL NV
PL NP
PI NP
D60
D30
D10
Cu
Cc
SAND, silty, brown
Moisture (M) &
Density (D)
Silty sand
Unified Soil Classification System
(ASTM D 2487):
GRADATION PLOT - SOIL & AGGREGATE
4-Nov-20
G. Hoyos
B-3 at 14'
2021314 Y. Schimmel
20.3059, Goulding Development
Alpine Bank
37.51.5"25.41"19.13/4"12.71/2"3/8"4.75No. 42.00No. 101.18No. 160.43No. 400.30No. 500.15No. 1000.075No. 2002.36No. 80.60No. 3050.82"0
10
20
30
40
50
60
70
80
90
100
0.010.101.0010.00100.00% PASSING (by dry mass)SIEVE SIZE, mm
Gradation 2021314
Corporate: 7108 South Alton Way, Building B • Centennial, Colorado 80112
Phone 303-220-0300 • www.cesareinc.com Rev. 3/30/12
Project Number:Date: 16-Nov-20
Project Name:Technician: G. Hoyos
Lab ID Number:Reviewer:Y. Schimmel
Sample Location:
Visual Description:
R-Value @ Exudation Pressure 300 psi:
Specification:
Test Specimen:1 2 3
S1 =[(R-5)/11.29]+3 S1=3.35 Moisture Content, %: 16.1 16.7 19.7
MR =10[(S1+18.72)/6.24]MR=3,448 Expansion Pressure, psi: -0.03 -0.09 -0.27
MR = Resilient Modulus, psi Dry Density, pcf: 115.7 114.9 107.2
S1 = the Soil Support Value R-Value: 15 10 4
R = the R-Value obtained Exudation Pressure, psi: 453 324 152
Note: The R-Value is measured; the MR is an approximation from correlation formulas.
FILL; CLAY, sandy, brown
Alpine Bank
B-3 at 0.5' to 5'
2021310
CDOT Pavement Design Manual, 2011.
Eq. 2.1 & 2.2, page 2-3.
20.3059, Goulding Development
R-VALUE TEST GRAPH (ASTM D2844)
9
9
0
20
40
60
80
100
100200300400500600700800 R-ValueExudation Pressure (psi)
R-Value 2021310
Corporate: 7108 South Alton Way, Building B • Centennial, Colorado 80112
Phone 303-220-0300 • www.cesareinc.com Rev. 3/30/12
20.3059 Goulding Development Alpine Bank 2021312
-0.3 N/A
Project
Number Client Project Name
Lab ID
Number
B-2 19 CLAYSTONE, sandy, brown 102.8 15.8 1,000
Sample
Location
Sample
Depth
(ft) Visual Description of Sample
Dry
Density
(pcf)
Moisture
Content
(%)
Inundation
Pressure
(psf)
Volume
Change
(%)
Swell
Pressure
(psf)
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
10 100 1,000 10,000 100,000Swell/Consolidation (%)Applied Pressure (psf)
SWELL/CONSOLIDATION PLOT
Consolidation Upon Wetting
Sample Inundated
SwellPlot Primary 2021312
Corporate: 7108 South Alton Way, Building B • Centennial, Colorado 80112
Phone 303-220-0300 • www.cesareinc.com Rev. 06/07/19
20.3059 Goulding Development Alpine Bank 2021313
0.6 1,575
Project
Number Client Project Name
Lab ID
Number
B-3 4 CLAY, sandy, reddish brown 99.5 22.2 500
Sample
Location
Sample
Depth
(ft) Visual Description of Sample
Dry
Density
(pcf)
Moisture
Content
(%)
Inundation
Pressure
(psf)
Volume
Change
(%)
Swell
Pressure
(psf)
1,575
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
10 100 1,000 10,000 100,000Swell/Consolidation (%)Applied Pressure (psf)
SWELL/CONSOLIDATION PLOT
Swell Upon Wetting
Sample Inundated
SwellPlot Primary 2021313
Corporate: 7108 South Alton Way, Building B • Centennial, Colorado 80112
Phone 303-220-0300 • www.cesareinc.com Rev. 06/07/19
20.3059 Goulding Development Alpine Bank 2021315
0.3 1,550
Project
Number Client Project Name
Lab ID
Number
B-2 9 CLAY, sandy, brown 110.5 18.6 1,000
Sample
Location
Sample
Depth
(ft) Visual Description of Sample
Dry
Density
(pcf)
Moisture
Content
(%)
Inundation
Pressure
(psf)
Volume
Change
(%)
Swell
Pressure
(psf)
1,550
-7
-6
-5
-4
-3
-2
-1
0
1
2
3
10 100 1,000 10,000 100,000Swell/Consolidation (%)Applied Pressure (psf)
SWELL/CONSOLIDATION PLOT
Swell Upon Wetting
Sample Inundated
SwellPlot Primary 2021315
Corporate: 7108 South Alton Way, Building B • Centennial, Colorado 80112
Phone 303-220-0300 • www.cesareinc.com Rev. 06/07/19
APPENDIX C
Vapor Barriers
CESARE, INC.
20.3059 Alpine Bank Vapor Barriers Appendix C 1
VAPOR BARRIERS
If it is determined that a vapor retarder/barrier is warranted, Cesare recommends the vapor barrier
comply with ASTM E1745, and if moisture sensitive flooring will be utilized, have a permeance below
0.01 perms before and after mandatory conditioning testing. The vapor retarder/barrier should be
installed per ASTM E1643 and the design professional should consider project specific requirements
in specification verbiage. See the ACI Committee 302, “Guide for Concrete Floor and Slab
Construction (ACI 302.R-96)” for additional discussion and guidance regarding the use of vapor
retarders/barriers beneath floor slabs.
The 2018 IBC, Section 1805.2 Dampproofing states that where hydrostatic pressure will not occur,
as determined by Section 18-03.5.4, floors shall be dampproofed in accordance with this section.
Section 1805.2 Floors, states,
“Dampproofing materials for floors shall be installed between the floor and the base
course required by Section 1805.4.1, except where a separate floor is provided above
a concrete slab. Where installed beneath the slab, dampproofing shall consist of not
less than 6-mil (0.006 inch; 0.152 mm) polyethylene with joints lapped not less than 6
inches (152 mm), or other approved methods or materials. Where permitted to be
installed on top of the slab, damp proofing shall consist of mopped-on bitumen, not
less than 4-mil; (0.004 inch; 0.102 mm) polyethylene, or other approved methods or
materials. Joints in the membrane shall be lapped and sealed in accordance with the
manufacturer’s installation instructions”.
Section 1805.4.1 Floor Base Course, states,
“Floors of basements, except as provided for in Section 1805.1.1 shall be placed over
a floor base course not less than 4 inches (102 mm) in thickness that consists of gravel
or crushed stone containing no more than 10 percent of material that passes through
a No. 4 (4.75mm ) sieve. Exception: Where a site is in well-drained gravel or
sand/gravel mixture soils, a floor base course is not required.”
Historically, when considering basement construction at sites with expansive soil, most of the
geotechnical community local to the Front Range have recommended against placing a layer of base
course material below basement slabs, except in shallow groundwater situations. A primary reason
has been the concern that installation of a free draining granular material below the slab could allow
or promote wetting of the underlying expansive soil from an isolated source of water.
Cesare recommends that basement slabs be constructed directly on the existing subgrade soil without
the addition of a layer of base course material and that the architect be consulted regarding the need
for a vapor retarder or vapor barrier. Decision to include a vapor retarder/barrier beneath the slab is
dependent on the sensitivity of floor coverings and building use to moisture.
APPENDIX D
Pavement Design Calculations
Project Information
Design Parameters
Traffic Data
Scenario Name Parking
Scenario Description
Estimated Completion
Year
2021
State Colorado
Roadway
Classification
Local
Pavement Type New - Asphalt
Design Period (Years)20 years
Reliability Level (R)75 Z =-0.674R
Combined Standard
Error (S0)
0.44
Initial Serviceability
Index (pi)
4.5
Terminal
Serviceability Index
(pt)
2
Change in
Serviceability (ΔPSI)
2.5
Completion Year
Traffic
N/A
Load Equivalency
Factor
N/A
Completion Year
ESALs
N/A
Design Period N/A
Future Traffic Growth
Rate (%)
N/A
N/A
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Pavement Structure
Design Guidance
Design Notes
ESAL Growth Rate
(%)
Total Design ESALs
(W18)
73,000
Surface Lifts None
Base Layers Type Layer Coef Drainage Thickness
Resilient Modulus
(MR)
3400 psi
Surface
Subgrade
Required minimum design SN: 2.70
Layer Thicknesses (in)
Surface:6.50
Total SN: 2.86
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Project Information
Design Parameters
Traffic Data
Scenario Name Drive Lanes
Scenario Description
Estimated Completion
Year
2021
State Colorado
Roadway
Classification
Local
Pavement Type New - Asphalt
Design Period (Years)20 years
Reliability Level (R)75 Z =-0.674R
Combined Standard
Error (S0)
0.44
Initial Serviceability
Index (pi)
4.5
Terminal
Serviceability Index
(pt)
2
Change in
Serviceability (ΔPSI)
2.5
Completion Year
Traffic
N/A
Load Equivalency
Factor
N/A
Completion Year
ESALs
N/A
Design Period N/A
Future Traffic Growth
Rate (%)
N/A
N/A
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Pavement Structure
Design Guidance
Design Notes
ESAL Growth Rate
(%)
Total Design ESALs
(W18)
365,000
Surface Lifts None
Base Layers Type Layer Coef Drainage Thickness
Resilient Modulus
(MR)
3400 psi
Surface
Subgrade
Required minimum design SN: 3.45
Layer Thicknesses (in)
Surface:8.00
Total SN: 3.52
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Project Information
Design Parameters
Traffic Data
Scenario Name Parking
Scenario Description
Estimated Completion
Year
2021
State Colorado
Roadway
Classification
Local
Pavement Type New - Asphalt
Design Period (Years)20 years
Reliability Level (R)75 Z =-0.674R
Combined Standard
Error (S0)
0.44
Initial Serviceability
Index (pi)
4.5
Terminal
Serviceability Index
(pt)
2
Change in
Serviceability (ΔPSI)
2.5
Completion Year
Traffic
N/A
Load Equivalency
Factor
N/A
Completion Year
ESALs
N/A
Design Period N/A
Future Traffic Growth
Rate (%)
N/A
N/A
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Pavement Structure
Design Guidance
Design Notes
ESAL Growth Rate
(%)
Total Design ESALs
(W18)
73,000
Surface Lifts Layer Layer
Coef Drainage Thickness
Surface 0.44 1 1
Binder/Intermediate 0.44 1 2
Base 0.44 1 ?
Base Layers Type Layer Coef Drainage Thickness
Aggregate Base .11 1 8
Resilient Modulus
(MR)
3400 psi
Surface
Aggregate Base
Subgrade
Required minimum design SN: 2.70
Layer Thicknesses (in)
Surface:4.50
Aggregate Base:8.00
Total SN: 2.86
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Project Information
Design Parameters
Traffic Data
Scenario Name Drive Lanes
Scenario Description
Estimated Completion
Year
2021
State Colorado
Roadway
Classification
Local
Pavement Type New - Asphalt
Design Period (Years)20 years
Reliability Level (R)75 Z =-0.674R
Combined Standard
Error (S0)
0.44
Initial Serviceability
Index (pi)
4.5
Terminal
Serviceability Index
(pt)
2
Change in
Serviceability (ΔPSI)
2.5
Completion Year
Traffic
N/A
Load Equivalency
Factor
N/A
Completion Year
ESALs
N/A
Design Period N/A
Future Traffic Growth
Rate (%)
N/A
N/A
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Pavement Structure
Design Guidance
Design Notes
ESAL Growth Rate
(%)
Total Design ESALs
(W18)
365,000
Surface Lifts Layer Layer
Coef Drainage Thickness
Surface 0.44 1 1
Binder/Intermediate 0.44 1 2
Base 0.44 1 ?
Base Layers Type Layer Coef Drainage Thickness
Aggregate Base 0.11 1 12
Resilient Modulus
(MR)
3400 psi
Surface
Aggregate Base
Subgrade
Required minimum design SN: 3.45
Layer Thicknesses (in)
Surface:5.00
Aggregate Base:12.00
Total SN: 3.52
Page 2 of 2PaveXpress: A Simplified Pavement Design Tool
11/17/2020http://app.pavexpressdesign.com/?username=bschimmel@cesareinc.com&payload=%7B...