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Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition
Fort Collins, Colorado
September 28, 2017
Terracon Project No. 20175063
Prepared for:
St. Elizabeth Ann Seton Catholic Church
Fort Collins, Colorado
Prepared by:
Terracon Consultants, Inc.
Fort Collins, Colorado
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
Responsive ■ Resourceful ■ Reliable
REPORT SUMMARY
Topic
1 Overview Statement
2
Project
Description
About 6,000 square foot structure
Max. Column loads: 200 kips, Max. Wall loads: 6 kips per linear foot, Max. Slabs
loads, 150 pounds per square foot
Up to 5 feet of fill to achieve final grade
Little excavation other than foundation construction
Expected traffic for pavement areas:
■ 200 autos/light trucks per day
■ Up to 20 medium-duty delivery/trash trucks per week
Geotechnical
Characterization
Lean clays to depths of about 9 to 19 feet
Partially weathered claystone to about below 9 feet to 22 feet
Claystone bedrock to maximum depths of exploration of 35½ feet
Groundwater encountered in Boring B1 at a depth about 5 feet
Earthwork
On-site soils are suitable for ill materials. Deep fills are planned below the proposed
floor for the addition. Recommendations for a structurally supported floor system
or increased compactive effort for imported granular fills placed below a floor slab
are presented in the report.
Deep
Foundations
Based on design recommendations from previous reports, the church is assumed
to have a slab-on-grade floor system supported by a drilled pier foundation system.
To minimize the difference between the existing and the addition, the addition
should be supported on a drilled pier foundation system.
Below-grade
Structures
The building will have a partial basement extending about 14 feet below the first
floor level.
Pavements for
fire access road
With subgrade prepared as noted in Earthwork
Portland Cement Concrete (PCC):
■ 6” PCC in fire access road
Asphaltic Cement Concrete (ACC):
■ 6” ACC over 4” aggregate base course in fire access road
Gravel-surface Roadway:
■ 18” Gravel-surfacing in fire access road
General
Comments
This section contains important information about the limitations of this geotechnical
engineering report.
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REPORT TOPICS
REPORT TOPICS
REPORT SUMMARY ...................................................................................................... 1
INTRODUCTION ............................................................................................................. 1
SITE CONDITIONS ......................................................................................................... 1
PROJECT DESCRIPTION .............................................................................................. 2
GEOTECHNICAL CHARACTERIZATION ...................................................................... 3
GEOTECHNICAL OVERVIEW ....................................................................................... 5
EARTHWORK................................................................................................................. 6
DEEP FOUNDATIONS ................................................................................................. 10
SEISMIC CONSIDERATIONS ...................................................................................... 12
FLOOR SYSTEMS........................................................................................................ 13
LATERAL EARTH PRESSURES ................................................................................. 16
PAVEMENTS ................................................................................................................ 17
CORROSIVITY.............................................................................................................. 21
GENERAL COMMENTS ............................................................................................... 21
Note: This report was originally delivered in a web-based format. Orange Bold text in the report indicates a referenced
section heading. The PDF version also includes hyperlinks which direct the reader to that section, and clicking on the
logo in the top right corner will bring you back to this page. For more interactive features, please view your project
online at client.terracon.com.
ATTACHMENTS
EXPLORATION AND TESTING PROCEDURES
SITE LOCATION AND EXPLORATION PLAN
EXPLORATION RESULTS (Boring Logs and Laboratory Data)
SUPPORTING INFORMATION (General Notes)
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INTRODUCTION
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition
5450 South Lemay Avenue
Fort Collins, Colorado
Terracon Project No. 20175063
September 28, 2017
INTRODUCTION
This report presents the results of our subsurface exploration and geotechnical engineering
services performed for the proposed St. Elizabeth Ann Seton Catholic Parish Addition to be
located at 5450 South Lemay Avenue in Fort Collins, Colorado. Previously, Terracon prepared
multiple Geotechnical Engineering Reports (Project No. 20035083; report dated August 26, 2003)
for the northwest addition and (Project No. 20985150; report dated October 5, 1998) for proposed
additions on this site. The purpose of these services is to provide information and geotechnical
engineering recommendations relative to:
■ Subsurface soil (and rock) conditions ■ Floor slab design and construction
■ Groundwater conditions ■ Lateral earth pressures
■ Site preparation and earthwork ■ Seismic site classification per IBC
■ Excavation considerations
■ Foundation design and construction
■ Pavement recommendations for a fire
access road to the south of the existing
building
The geotechnical engineering scope of services for this project included the advancement of 5
test borings to depths ranging from approximately 10½ to 35½ feet below existing site grades.
Maps showing the site and boring locations are shown in the Site Location and Exploration
Plan sections, respectively. The results of the laboratory testing performed on soil samples
obtained from the site during the field exploration are included on the boring logs in the
Exploration Results section of this report.
SITE CONDITIONS
The following description of site conditions is derived from our site visit in association with the
field exploration and our review of publicly available geologic and topographic maps.
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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Item Description
Parcel Information
The site is located at 5450 South Lemay Avenue Fort Collins, Colorado. The
approximate Latitude/Longitude of the center of the site is 40.5101°
N/105.0565° W.
See Site Location
Existing
Improvements
St. Elizabeth Ann Seton Catholic Church is an existing two-story church with
a walkout basement, surrounding landscaping, exterior concrete flatwork,
and asphalt pavements. Based on design recommendations from previous
reports, the church is assumed to have a slab-on-grade floor system
supported by a drilled pier foundation system.
Current Ground
Cover
Various landscaping, existing building, parking and drive areas and
sidewalks.
Existing Topography
The building addition site slopes away from the building towards a detention
pond area in the southwest corner of the property. A total elevation
difference of about 17 feet is present across the addition footprint with an
additional drop in elevation of about 12 feet to the base of the detention
pond.
Geology
The proposed area is located within the Colorado Piedmont section of the
Great Plains physiographic province. The site is underlain by the Cretaceous
Pierre Formation. The Pierre shale underlies the site at depths of 3½ feet to
greater than 10 feet. The bedrock is anticipated to overlain by residual and
alluvial clays of Pleistocene and/or Recent Age.
PROJECT DESCRIPTION
Our initial understanding of the project was provided in our proposal and was discussed in the
project planning stage. A period of collaboration has transpired since the project was initiated,
and our final understanding of the project conditions is as follows:
Item Description
Information Provided
A provided drawing showing the grading plan and building location
developed by CCG Engineering Consultants, dated June 7, 2017.
Project Description
The project will include a 1-story building addition containing a worship
room with a footprint of about 6,000 square feet. There will be a small
section for a basement at the southwest side and a crawl space under the
majority of the addition (non-basement).
Building Construction The proposed building will be steel-framed with concrete exterior walls.
Finished Floor Elevation
Finished floor elevation is expected to be at 4964.7 and 4950.7 for the
partial basement, MSL.
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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Item Description
Maximum Loads
Columns: 200 kips maximum (assumed)
Walls: 6 kips per linear maximum (assumed)
Slabs: 150 pounds per square foot maximum (assumed)
Anticipated conceptual loads were confirmed with the structural engineer.
Grading/Slopes
Up to 5 feet of cut will be required to develop final grade for the basement.
Grading plans indicate final slope angles of as steep as 3(H): 1(V) are
planned.
Below-grade Areas A small section of the addition will have a basement at the southwest
side.
Pavements
Determine appropriate roadway surfacing design sections for the fire
access road
GEOTECHNICAL CHARACTERIZATION
Subsurface Profile
We have developed a general characterization of the subsurface soil, bedrock and groundwater
conditions based upon our review of the data and our understanding of the geologic setting. The
following page provides a graphical representation of characterization. A statistical summary of
field and laboratory data is also included.
The geotechnical characterization as illustrated below forms the basis of our geotechnical
calculations and evaluation of site preparation, foundation options and pavement options. As
noted in General Comments, the characterization is based upon widely spaced exploration
points across the site, and variations are likely.
Subsurface conditions at the boring locations can be generalized as follows:
Stratum Approximate Depth to Bottom
of Stratum (feet) Material Description
Consistency/Density/
Hardness
Surface 0 to 0.5
Topsoil: brown, friable and
contained significant organic
matter
N/A
1 About 9 to 19 Lean clay with varying
amounts of sand and silt
Soft to very stiff
2 About 10.5
1
to 22 Weathered claystone Firm
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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Stratum Approximate Depth to Bottom
of Stratum (feet) Material Description
Consistency/Density/
Hardness
3
Undetermined: Borings terminated
within this stratum at the planned
depths of approximately 30½ to
35½ feet
Claystone bedrock Hard to very hard
1. The planned terminated depths of Borings B1 and B2 within the fire access road were 10½ feet.
Conditions encountered at each boring location are indicated on the individual boring logs shown
in the Exploration Results section and are attached to this report. Stratification boundaries on
the boring logs represent the approximate location of changes in native soil types; in situ, the
transition between materials may be gradual.
Groundwater Conditions
The boreholes were observed while drilling and after completion for the presence and level of
groundwater. In addition, delayed water levels were also obtained in some borings. The water levels
observed in the boreholes can be found on the boring logs in Exploration Results, and are
summarized below.
Boring Number
Approximate Depth to
Groundwater while Drilling
(feet)
1
Approximate Depth to
Groundwater after Drilling
(feet)
1
B1 5 5
B2 Not encountered Not encountered
B3 Not encountered Not encountered
B4 Not encountered Not encountered
B5 Not encountered Not encountered
1. Below ground surface
Groundwater was not observed in the remaining borings while drilling, or for the short duration the
borings could remain open.
Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall, runoff
and other factors not evident at the time the borings were performed. Therefore, groundwater
levels during construction or at other times in the life of the structure may be higher or lower than
the levels indicated on the boring logs. The possibility of groundwater level fluctuations should be
considered when developing the design and construction plans for the project.
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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GEOTECHNICAL OVERVIEW
The near surface, stiff to hard lean clay could become unstable with typical earthwork and
construction traffic, especially after precipitation events. The effective drainage should be
completed early in the construction sequence and maintained after construction to avoid potential
issues. If possible, the grading should be performed during the warmer and drier time of the year.
If grading is performed during the winter months, an increased risk for possible undercutting and
replacement of unstable subgrade will persist. Additional site preparation recommendations
including subgrade improvement and fill placement are provided in the Site Preparation section.
Based on the foundation system of the existing building, proposed construction of the addition,
and the subsurface conditions encountered, we recommend the proposed addition be supported
by a drilled pier foundation bottomed in bedrock. Additional loads if placed on the existing
foundation should be evaluated by the structural engineer to determine if they meet or exceed
design criteria of the foundation.
Grading plans indicate comparatively deep fills up to about 14 feet in total thickness are planned
below the proposed floor slab for the southern portion of the building addition. We believe there
is a significant risk for floor slab settlement due to settlement of the fill materials. Even properly
compacted fill settles. Our experience suggests properly compacted fill could settle about ½ to 1
percent of the total fill thickness which corresponds to up to about 2 inches. The amount and rate
of settlement will be increased if water is introduced into the fill. It is noted that settlement of the
fill material due to self-weight is in addition to settlements due to floor slab and/or structural
induced loads. The lowest risk alternative is to utilize a structurally supported floor system for the
proposed addition. However, if a slab-on-grade floor system is desired, we recommend utilizing
imported granular fill as the backfill below the proposed floor and increasing the compactive effort
to achieve at least 99 percent of the maximum dry unit weight as determined by ASTM D 698. Use
of a light-weight controlled low strength material (CLSM) such as cellular concrete (a.k.a. flashfill)
or other similar backfill can also be considered to reduce risk for settlement.
Expansive soils and/or bedrock will be present beneath slabs-on-grade at the basement elevation
on this site. This report provides recommendations to help mitigate the effects of soil shrinkage
and expansion on these slabs-on grade. However, even if these procedures are followed, some
movement and (at least minor) cracking in the structure should be anticipated. The severity of
cracking and other damage such as uneven floor slabs will probably increase if modification of
the site results in excessive wetting or drying of the expansive soils. Eliminating the risk of
movement and distress may not be feasible, but it may be possible to further reduce the risk of
movement if certain measures discussed in this report are used during construction. The Floor
Slabs section addresses slab-on-grade support of the building.
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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Gravel-surfacing, asphalt, and rigid pavement systems are recommended alternatives for the fire
access lane. The Pavements section addresses the design of pavement systems.
The General Comments section provides an understanding of the report limitations.
EARTHWORK
Earthwork will include clearing and grubbing, excavations and fill placement. The following
sections provide recommendations for use in the preparation of specifications for the work.
Recommendations include critical quality criteria as necessary to render the site in the state
considered in our geotechnical engineering evaluation for foundations, floor systems, and
pavements.
Site Preparation
Prior to placing fill, existing vegetation and topsoil should be removed from the proposed
construction areas. After the removal of topsoil, the top 10 inches of the ground surface should
be scarified, moisture conditioned and compacted to at least 95 percent of the maximum dry unit
weight as determined by ASTM D698.
The fire access road subgrade should be proof-rolled with an adequately loaded vehicle such as
a fully loaded tandem axle dump truck. The proof-rolling should be performed under the direction
of the Geotechnical Engineer. Areas excessively deflecting under the proof-roll should be
delineated and subsequently addressed by the Geotechnical Engineer. Excessively wet or dry
material should either be removed or moisture conditioned and recompacted.
Fill Material Types
Fill required to achieve design grade should be classified as structural fill and general fill.
Structural fill is material used below pavements or constructed slopes. General fill is material used
to achieve grade outside of these areas. Earthen materials used for structural and general fill
should meet the following material property requirements:
Soil Type
1 USCS Classification Acceptable Locations for Placement
On-site Clay Soils CL
The on-site clay soils can be reused as compacted
fill for all fills placed on-site. However, if a slab-on-
grade floor system is selected for the addition, we
recommend placing granular fill below this area of
the building to reduce risk for potential settlement.
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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Soil Type
1 USCS Classification Acceptable Locations for Placement
High Plasticity
Cohesive
2
Weathered Claystone,
Claystone
The on-site weathered claystone and claystone can
be reused as compacted fill outside of the building
area provided the materials are broken down to a
soil-like consistency and properly moisture
conditioned prior to placement.
Imported Soils Varies
Imported granular soils meeting the gradation
requirements presented herein can be considered
acceptable for use as engineered fill beneath
foundations, slabs, and pavements.
1. Structural and general fill should consist of approved materials free of organic matter and debris. Frozen
material should not be used, and fill should not be placed on a frozen subgrade. A sample of each material
type should be submitted to the Geotechnical Engineer for evaluation prior to use on this site.
Imported soils should conform to the following:
Gradation Percent finer by weight (ASTM C136)
3” 100
No. 4 Sieve 50-100
No. 200 Sieve 35 (max.)
■ Liquid Limit…………………………………………………....35 (max.)
■ Plastic Index…………………………………………………..20 (max.)
■ Maximum Expansive Potential (%)………………………...1.0*
*Measured on a sample compacted to approximately 95 percent of the ASTM D698 maximum dry density at
optimum water content. The sample is confined under a 150 psf surcharge and submerged.
Fill Compaction Requirements
Structural and general fill should meet the following compaction requirements.
Item Structural Fill
Maximum individual
lift thickness
8 inches or less in loose thickness when heavy, self-propelled compaction
equipment is used
4 to 6 inches in loose thickness when hand-guided equipment (i.e. jumping
jack, plate compactor) is used
Minimum
compaction
requirements
1
95% of the material’s maximum dry density (ASTM D698) for total fill
thicknesses of 8 feet or less
99% of the material’s maximum dry density (ASTM D698) for total fill
thicknesses greater than 8 feet and for the fill placed below a floor slab (if
selected for the addition floor system)
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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Item Structural Fill
Water content
range
2
Within 3 percent of optimum water content (imported cohesionless and cohesive
granular soils)
1 percent below to 3 percent above optimum water content (cohesive non-
granular soils)
1. We recommend that engineered fill be tested for water content and compaction during placement. Should
the results of the in-place density tests indicate the specified water or compaction limits have not been met,
the area represented by the test should be reworked and retested as required until the specified water and
compaction requirements are achieved.
2. Specifically, water levels should be maintained low enough to allow for satisfactory compaction to be
achieved without the compacted fill material pumping when proof-rolled.
Utility Trench Backfill
For low permeability subgrades like clay, utility trenches are a common source of water infiltration
and migration. Utility trenches penetrating beneath the existing building and proposed addition
should be effectively sealed to restrict water intrusion and flow through the trenches, which could
migrate below the building. The trench should provide an effective trench plug that extends at
least 5 feet from the face of the building exterior. The plug material should consist of cementitious
flowable fill or low permeability clay. The trench plug material should be placed to surround the
utility line. If used, the clay trench plug material should be placed and compacted to comply with
the water content and compaction recommendations for structural fill stated previously in this
report.
Grading and Drainage
All grades must provide effective drainage away from the existing building and proposed addition
during and after construction and should be maintained throughout the life of the structure. Water
retained next to the building can result in soil movements greater than those discussed in this
report. Greater movements can result in unacceptable differential floor slab and/or foundation
movements, cracked slabs and walls, and roof leaks. The roof should have gutters/drains with
downspouts that discharge onto splash blocks at a distance of at least 10 feet from the building.
Exposed ground should be sloped and maintained at a minimum 5 percent away from the building
for at least 10 feet beyond the perimeter of the building. Locally, flatter grades may be necessary
to transition ADA access requirements for flatwork. After building construction and landscaping,
final grades should be verified to document effective drainage has been achieved. Grades around
the structure should also be periodically inspected and adjusted as necessary as part of the
structure’s maintenance program. Where paving or flatwork abuts the structure a maintenance
program should be established to effectively seal and maintain joints and prevent surface water
infiltration.
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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Earthwork Construction Considerations
Shallow excavations, for the proposed structure, are anticipated to be accomplished with
conventional construction equipment. Upon completion of filling and grading, care should be taken
to maintain the subgrade water content prior to construction of floor slabs. Construction traffic
over the completed subgrades should be avoided. The site should also be graded to prevent
ponding of surface water on the prepared subgrades or in excavations. Water collecting over, or
adjacent to, construction areas should be removed. If the subgrade freezes, desiccates,
saturates, or is disturbed, the affected material should be removed, or the materials should be
scarified, moisture conditioned, and recompacted, prior to floor slab construction.
As a minimum, excavations should be performed in accordance with OSHA 29 CFR, Part 1926,
Subpart P, “Excavations” and its appendices, and in accordance with any applicable local, and/or
state regulations.
Construction site safety is the sole responsibility of the contractor who controls the means,
methods, and sequencing of construction operations. Under no circumstances shall the
information provided herein be interpreted to mean Terracon is assuming responsibility for
construction site safety, or the contractor's activities; such responsibility shall neither be implied
nor inferred.
Construction Observation and Testing
The earthwork efforts should be monitored under the direction of the Geotechnical Engineer.
Monitoring should include documentation of adequate removal of vegetation and top soil, proof-
rolling and mitigation of areas delineated by the proof-roll to require mitigation.
Each lift of compacted fill should be tested, evaluated, and reworked as necessary until approved
by the Geotechnical Engineer prior to placement of additional lifts. Each lift of fill should be tested
for density and water content at a frequency of at least one test for every 2,500 square feet of
compacted fill in the building areas and 5,000 square feet in pavement areas. One density and
water content test for every 50 linear feet of compacted utility trench backfill.
In areas of foundation excavations, the bearing subgrade should be evaluated under the direction
of the Geotechnical Engineer. In the event unanticipated conditions are encountered, the
Geotechnical Engineer should prescribe mitigation options.
In addition to the documentation of the essential parameters necessary for construction, the
continuation of the Geotechnical Engineer into the construction phase of the project provides the
continuity to maintain the Geotechnical Engineer’s evaluation of subsurface conditions, including
assessing variations and associated design changes.
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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DEEP FOUNDATIONS
Based on design recommendations from previous reports, the existing church building is assumed
to be supported by a drilled pier foundation system. We recommend a similar deep foundation
system bottomed in bedrock to support the addition to reduce risk for different movements
between the existing building and the addition.
Drilled Pier Design Parameters
Drilled piers are considered suitable for support of the proposed addition. Design parameters
based on the subsurface information from Borings B3 to B5 are provided below in the Drilled
Shaft Design Summary table for the design of drilled shaft foundations.
Description Straight Shaft Piers
Minimum pier diameter 18 inches
Pier concrete slump (uncased piers) 5 to 7 inches
Pier concrete slump (cased piers) 7 to 9 inches
Approximate total movement
1 1 inch
1. The foundation movement will depend upon the variations within the subsurface soil profile, the
structural loading conditions, the quality of the earthwork operations, and maintaining uniform soil
water content throughout the life of the structure. The estimated movements are based on maintaining
uniform soil water content during the life of the structure. Additional foundation movements could
occur if water from any source infiltrates the foundation soils; therefore, proper drainage and irrigation
practices should be incorporated into the design and operation of the facility. Failure to maintain soil
water content and positive drainage will nullify the movement estimates provided above.
A summary of the drilled pier foundation design recommendations is shown on the following
pages. The maximum allowable end bearing pressures given in the table is based on the cross-
sectional area of the tip of the drilled shaft. Skin friction (Sd) should be applied to the surface area
of the drilled shaft for that given length interval below a depth of 30 inches. The combination of
skin friction and end bearing pressure can be used to determine the vertical compression
capacity. The skin friction value should be used to determine the uplift capacity of the soil.
For lateral load and overturning design, we have included beam on elastic foundation spring
constants, lateral equivalent earth pressures, and more commonly used LPILE parameters. For
calculation of lateral deflection using the beam on elastic foundation method, a coefficient of
subgrade reaction listed on the following table may be used for the analysis. Lateral load design
parameters are valid for maximum soil strain of 1 percent for the native soils acting over a distance
of one shaft diameter. All shafts should be reinforced full-depth for the applied axial, lateral and
uplift stresses imposed.
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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Description
Material type
Clay
(3 feet and below)
Weathered Claystone Claystone
Allowable Vertical Parameters:
-- -- 25,000 psf
End Bearing
Skin Friction -- 1,000 psf/ft 2,000 psf/ft
Lateral Parameters
Beam on Elastic Foundation:
1
Passive, EFP,psf/ft
280 280 600
Soil Code Stiff clay Stiff clay Very stiff clay
Unit Weight (pcf) 120 120 130
Cohesion (psf) 900 1,500 3,000
Angle of internal Friction,
f (degrees) 0 0 0
Horizontal Modulus of
Subgrade Reaction:
k (static) pci
k (cyclic) pci
500
200
500
200
2,000
800
Strain at 50% of Maximum
Stress, e50
0.010 0.005 0.004
1. Ultimate value, a factor of safety of 3 should be applied for design.
A reduction factor of 0.75 should be applied to the allowable skin friction values when used for
calculating uplift capacities.
We recommend neglecting skin friction and lateral resistance for the upper 30 inches of drilled
piers because of the effects of frost penetration. The capacity of individual piers must be reduced
when considering the effects of group action. Piers should be considered to work in group action
if the horizontal center-to-center spacing is less than 3 pier diameters. A capacity reduction factor
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
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of 0.85 should be applied to piers spaced between 2½ to 3 horizontal center-to-center pier
diameters. We recommend horizontal center-to-center spacing of piers no closer than 2½ pier
diameters.
Drilled Shaft Construction Considerations
Drilling to design depths should be possible with single-flight power augers. Concrete should be
placed as soon as possible after the foundation excavation is completed, to reduce potential
disturbance of the bearing surface. If concrete cannot be placed in dry conditions, a tremie or
casing should be used for concrete placement. If casing is used for pier construction, it should
be withdrawn in a slow, continuous manner maintaining a sufficient head of concrete to prevent
infiltration of water or the creation of voids in pier concrete. Pier concrete should have a relatively
high fluidity when placed in cased pier holes or through a tremie. Concrete for "dry" drilled shaft
construction should have a slump of about 5 to 7 inches. Concrete should be directed into the
shaft utilizing a centering chute. Concrete for "wet" shaft construction would require higher slump
concrete.
Tensile reinforcement should extend to the bottom of shafts subjected to uplift loading. Buoyant
unit weights of the soil and concrete should be used in the calculations below the highest
anticipated groundwater elevation.
The drilled shaft installation process should be performed under the direction of the Geotechnical
Engineer. The Geotechnical Engineer should document the shaft installation process including
soil/rock and groundwater conditions encountered, consistency with expected conditions, and
details of the installed shaft.
SEISMIC CONSIDERATIONS
The seismic design requirements for buildings and other structures are based on Seismic Design
Category. Site Classification is required to determine the Seismic Design Category for a structure.
The Site Classification is based on the upper 100 feet of the site profile defined by a weighted
average value of either shear wave velocity, standard penetration resistance, or undrained shear
strength in accordance with Section 20.4 of ASCE 7-10.
Description Value
Table 20.3-1 of ASCE 7-10
1
C
2
Site Latitude 40.5101
Site Longitude -105.0565
SDS Spectral Acceleration for a Short Period
3 0.195g
SD1 Spectral Acceleration for a 1-Second Period
3 0.093g
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
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Description Value
1. Seismic site classification in general accordance with the Table 20.3-1 of ASCE 7-10.
2. The 2015 International Building Code (IBC) uses a site profile extending to a depth of 100 feet for seismic
site classification. Borings at this site were extended to a maximum depth of 35½ feet. The site properties
below the boring depth to 100 feet were estimated based on our experience and knowledge of geologic
conditions of the general area. Additional deeper borings or geophysical testing may be performed to confirm
the conditions below the current boring depth.
3. These values were obtained using online seismic design maps and tools provided by the USGS
(http://earthquake.usgs.gov/hazards/designmaps/).
FLOOR SYSTEMS
Grading plans indicate comparatively deep fills up to about 14 feet in total thickness are planned
below the proposed floor slab for the southern portion of the building addition. We believe there
is a significant risk for floor slab settlement due to settlement of the fill materials. Even properly
compacted fill settles. Our experience suggests properly compacted fill could settle about ½ to 1
percent of the total fill thickness which corresponds to up to about 2 inches. The amount and rate
of settlement will be increased if water is introduced into the fill. It is noted that settlement of the
fill material due to self-weight is in addition to settlements due to floor slab and/or structural
induced loads. The lowest risk alternative is to utilize a structurally supported floor system for the
proposed addition. However, if a slab-on-grade floor system is desired, we recommend utilizing
imported granular fill as the backfill below the proposed floor and increasing the compactive effort
to achieve at least 99 percent of the maximum dry unit weight as determined by ASTM D 698. Use
of a light-weight controlled low strength material (CLSM) such as cellular concrete (a.k.a. flashfill)
or other similar backfill can also be considered to reduce risk for settlement.
Structurally Supported Floor/Crawl Space
Building codes should be followed for clear space requirements below structurally supported floors
with crawl space areas and will depend, in part, upon the type of materials used to construct the
floor as well as the volumetric expansion potential of the underlying soil/bedrock. Clear spaces for
these types of floors normally range from about 18 to 24 inches.
Where other structural floor support systems and materials are used, we recommend a minimum
clear space/void of 10 inches be maintained between the underside of the structural floor system
and the surface of the subgrade/exposed earth. It is prudent to maintain the minimum clear space
below all plumbing lines and other conduits. This can be accomplished by hanging
plumbing/conduits on the underside of the structural floor or by trenching below lines.
Irrigation and surface water can penetrate backfill adjacent to the building addition and collect at
the bottom of crawl space excavations resulting in a perched groundwater condition. Experience
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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indicates over a period of time, moist conditions, soft soils and possibly standing water can develop
in crawl space areas, particularly if proper surface drainage away from the foundation is not provided
and maintained or if over-watering of lawns and other landscape plantings adjacent to the
foundation occurs. As a precautionary measure, we recommend the provision of a drain where a
suspended structural floor with a crawl space area is used.
At a minimum, the drain trench and pipe should be constructed around the interior perimeter of
the building addition foundation, and should be sloped at a minimum ½ percent to a suitable outlet,
such as a sump and pump system or to a positive gravity outfall. The drainage system should
consist of a minimum 4-inch diameter rigid perforated pipe, embedded in free-draining gravel,
placed in a trench at least 12-inches in width. The invert of the drain pipe should be at least 4
inches below the bottom of the grade beam void or the crawl space subgrade at the highest point.
The pipe should be encased with washed gravel and the gravel should extend laterally to the
grade beam void and at least ½ the height of the void. The gravel should be covered with drainage
fabric to reduce infiltration of fines into and clogging of the gravel media and pipe. The drain layout
could be located exterior to the foundation walls; however, an interior location is preferred. If an
exterior drain is desired, we should be contacted to discuss possible implications and to provide
supplemental recommendations.
Crawl space areas (if used) should be well ventilated for indoor air quality to help manage humidity
and to facilitate moisture release. This will likely require active ventilation using fans or other
appropriate methods. A mechanical engineer experienced in these issues should be consulted to
evaluate and properly design a ventilation system. To help promote drainage towards the
perimeter of the structure, the crawl space subgrade should be excavated to a minimum 1 percent
slope from the high point at the center of crawl space areas to the perimeter of the building
addition foundation. To further manage humidity, we believe best current practices involve placing
a vapor retarder (10 mil polyethylene membrane material, or equivalent) on the exposed soil in
the crawl space. The vapor retarder should be sealed at joints and attached to concrete foundation
walls and other elements.
Slabs-on-grade
The partial basement will likely have a slab-on-grade floor system. The subgrade soils are comprised
of clays exhibiting the potential to swell with increased water content. Construction of the slab-on-
grade and revising site drainage creates the potential for gradual increased water contents within the
clays. Increases in water content will cause the clays to swell and damage the floor slab. To reduce
the swell potential to less than about 1 inch, we recommend over-excavating the soils below the
basement floor slab to a depth of at least 12 inches and preplacing the soils with moisture
conditioned, properly compacted imported granular fill.
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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Design parameters for floor slabs assume the requirements for Earthwork have been followed.
Specific attention should be given to positive drainage away from the structure and positive drainage
of the granular fill placed beneath the floor slab.
Floor Slab Design Parameters
Item Description
Floor Slab Support
1 At least 12 inches of over-excavation backfill consisting of imported granular
fill.
Estimated Modulus of
Subgrade Reaction
2 100 pounds per square inch per inch (psi/in) for point loads
1. Floor slabs should be structurally independent of building footings or walls to reduce the possibility of floor
slab cracking caused by differential movements between the slab and foundation.
2. Modulus of subgrade reaction is an estimated value based upon our experience with the subgrade
condition, the requirements noted in Earthwork, and the floor slab support as noted in this table. It is
provided for point loads. For large area loads, the modulus of subgrade reaction would be lower.
The use of a vapor retarder should be considered beneath concrete slabs on grade covered with
wood, tile, carpet, or other moisture sensitive or impervious coverings, or when the slab will
support equipment sensitive to moisture. When conditions warrant the use of a vapor retarder,
the slab designer should refer to ACI 302 and/or ACI 360 for procedures and cautions regarding
the use and placement of a vapor retarder.
Saw-cut control joints should be placed in the slab to help control the location and extent of
cracking. For additional recommendations refer to the ACI Design Manual. Joints or cracks should
be sealed with a water-proof, non-extruding compressible compound specifically recommended
for heavy duty concrete pavement and wet environments.
Where floor slabs are tied to perimeter walls or turn-down slabs to meet structural or other
construction objectives, our experience indicates differential movement between the walls and
slabs will likely be observed in adjacent slab expansion joints or floor slab cracks beyond the
length of the structural dowels. The Structural Engineer should account for potential differential
settlement through use of sufficient control joints, appropriate reinforcing or other means.
Floor Slab Construction Considerations
Movements of slabs-on-grade using the recommendations discussed in previous sections of this
report will likely be reduced and tend to be more uniform. The estimates discussed above assume
that the other recommendations in this report are followed. Additional movement could occur
should the subsurface soils become wetted to significant depths, which could result in potential
excessive movement causing uneven floor slabs and severe cracking. This could be due to over
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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watering of landscaping, poor drainage, improperly functioning drain systems, and/or broken utility
lines. Therefore, it is imperative that the recommendations presented in this report be followed.
The Geotechnical Engineer should approve the condition of the floor slab subgrades immediately
prior to placement of the floor slab support course, reinforcing steel and concrete. Attention should
be paid to high traffic areas that were rutted and disturbed earlier, and to areas where backfilled
trenches are located.
LATERAL EARTH PRESSURES
Design Parameters
Structures with unbalanced backfill
levels on opposite sides should be
designed for earth pressures at least
equal to values indicated in the
following table. Earth pressures will be
influenced by structural design of the
walls, conditions of wall restraint,
methods of construction and/or
compaction and the strength of the
materials being restrained. Two wall
restraint conditions are shown. Active
earth pressure is commonly used for design of free-standing cantilever retaining walls and
assumes wall movement. The "at-rest" condition assumes no wall movement and is commonly
used for basement walls, loading dock walls, or other walls restrained at the top. The
recommended design lateral earth pressures do not include a factor of safety and do not provide
for possible hydrostatic pressure on the walls (unless stated).
Lateral Earth Pressure Design Parameters
Earth
Pressure
Condition
1
Coefficient for Backfill
Type
2
Surcharge Pressure
3, 4, 5
p1 (psf)
Effective Fluid Pressures
(psf)
2, 4, 5
Unsaturated
6
Active (Ka)
Granular - 0.31
Fine Grained - 0.41
(0.31)S
(0.41)S
(40)H
(50)H
At-Rest (Ko)
Granular - 0.47
Fine Grained - 0.58
0.47)S
(0.58)S
(55)H
(70)H
Passive (Kp)
Granular - 3.25
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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Lateral Earth Pressure Design Parameters
Earth
Pressure
Condition
1
Coefficient for Backfill
Type
2
Surcharge Pressure
3, 4, 5
p1 (psf)
Effective Fluid Pressures
(psf)
2, 4, 5
Unsaturated
6
1. For active earth pressure, wall must rotate about base, with top lateral movements 0.002 H to
0.004 H, where H is wall height. For passive earth pressure, wall must move horizontally to
mobilize resistance.
2. Uniform, horizontal backfill, compacted to at least 95 percent of the ASTM D 698 maximum dry
density, rendering a maximum unit weight of 120 pcf.
3. Uniform surcharge, where S is surcharge pressure.
4. Loading from heavy compaction equipment is not included.
5. No safety factor is included in these values.
Backfill placed against structures should consist of granular soils or low plasticity cohesive soils.
For the granular values to be valid, the granular backfill must extend out and up from the base of
the wall at an angle of at least 45 and 60 degrees from vertical for the active and passive cases,
respectively.
Subsurface Drainage for Below Grade Walls
A perforated rigid plastic drain line installed behind the base of walls and extends below adjacent
grade is recommended to prevent hydrostatic loading on the walls. The invert of a drain line
around a below-grade building area or exterior retaining wall should be placed near foundation
bearing level. The drain line should be sloped to provide positive gravity drainage to daylight or
to a sump pit and pump. The drain line should be surrounded by clean, free-draining granular
material having less than 5 percent passing the No. 200 sieve. The free-draining aggregate should
be encapsulated in a filter fabric. The granular fill should extend to within 2 feet of final grade,
where it should be capped with compacted cohesive fill to reduce infiltration of surface water into
the drain system.
As an alternative to free-draining granular fill, a pre-fabricated drainage structure may be used. A
pre-fabricated drainage structure is a plastic drainage core or mesh which is covered with filter
fabric to prevent soil intrusion, and is fastened to the wall prior to placing backfill.
PAVEMENTS
General Pavement Comments
Pavement designs are provided for the traffic conditions and pavement life conditions as noted in
Project Description and in the following sections of this report. A critical aspect of pavement
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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performance is site preparation. Pavement designs, noted in this section, must be applied to the
site, which has been prepared as recommended in the Site Preparation section.
Preliminary Pavement Design Parameters
Design of Asphaltic Concrete (AC) pavements are based on the procedures outlined in the
National Asphalt Pavement Association (NAPA) Information Series 109 (IS-109). Design of
Portland Cement Concrete (PCC) pavements are based upon American Concrete Institute (ACI)
330R-01; Guide for Design and Construction of Concrete Parking Lots. Pavement thickness
design has been based assumed ESALs of 110,000 for the proposed Light Duty and Heavy Duty
pavement areas, respectively, over a 20-year design life.
We have based our preliminary pavement thickness design on the NAPA design traffic classes
presented below:
■ Traffic Class III – Up to 10 single-unit or 3-axle semi-trailer trucks per day or equivalents:
average gross vehicle weight should be less than the legal limit. Considered for ESAL’s up
to 110,000.
Traffic classifications and/or design ESAL’s should be reviewed and approved by the owner prior
to commencement of pavement operations. In addition to the flexible pavement design analyses,
a rigid pavement design analysis was completed, based upon American Concrete Institute (ACI)
330R-01; Guide for Design and Construction of Concrete Parking Lots. Based on an R-Value of
9 from our experience on the previous project, a modulus of rupture of 13,500 psi was used for
pavement concrete.
Preliminary Pavement Section Thicknesses
The following table provides options for Asphaltic Concrete, Portland Concrete Cement, and
Gravel Surfaced Sections for the fire access road:
Traffic
Classification Alternative
Asphaltic
Cement
Concrete
(in.)
Portland
Cement
Concrete
(in.)
Gravel
Surface
(in.)
Aggregate
Base
Course
(in.)
Fire Access Road
A 6 --- --- 4
B --- 6 --- ---
C --- --- 18 ---
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
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Pavement Construction Considerations
Asphalt concrete should be composed of a mixture of aggregate, filler and additives, if required,
and approved bituminous material. The asphalt concrete should conform to approved mix designs
stating the Hveem properties, optimum asphalt content, job mix formula and recommended mixing
and placing temperatures and designed to a minimum 50 gyrations as determined by CDOT
Superpave. Aggregate used in plant-mixed asphalt concrete should meet Colorado Department of
Transportation Grading S or SX specifications. Mix designs should be submitted prior to
construction to verify their adequacy. Asphalt material should be placed in maximum 3-inch lifts
and should be compacted to a minimum of 92 to 96 percent of the maximum theoretical density as
determined by CP 51.
Where rigid pavements are used, the concrete should be based on an approved CDOT mix
design.
Sealing of construction joints is essential to protect the subgrade and promote long term
performance of concrete pavement. Joints should be sealed with a sealant designed especially
for pavements subject to truck and car traffic. The joints should be sealed as soon as possible
(in accordance with sealant manufacturer’s instructions) to minimize infiltration of water into the
soil.
The performance of all pavements can be enhanced by reducing excess water, which can reach
the subgrade soils. The following recommendations should be considered at minimum:
n Site grading at a minimum 2 percent grade away from the pavements;
n Compaction of any utility trenches for landscaped areas to the same criteria as the
pavement subgrade;
n Snow management plans should be developed designating areas outside pavement and
planter areas for stockpiling of snow;
n Sealing or providing area drains and curb cuts in all landscaped areas in, or adjacent to
pavements to reduce or prevent water migration to subgrade soils;
n Installation of edge drains around areas of landscaping
n Placing compacted backfill against the exterior side of curb and gutter; and,
n Placing curb, gutter and/or sidewalk directly on subgrade soils without the use of base
course materials.
Preventative maintenance should be planned and provided for through an on-going pavement
management program in order to enhance future pavement performance. Preventative
maintenance activities are intended to slow the rate of pavement deterioration.
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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Preventive maintenance consists of both localized maintenance (e.g. crack sealing and patching)
and global maintenance (e.g. surface sealing). Preventative maintenance is usually the first
priority when implementing a planned pavement maintenance program.
Recommended preventative maintenance policies for asphalt concrete pavements, based upon
type and severity of distress, can be provided. Prior to implementing any maintenance additional
engineering observation is recommended to determine the type and extent of preventative
maintenance.
Pavement Maintenance
The pavement sections represent minimum recommended thicknesses and, as such, periodic
maintenance should be anticipated. Therefore, preventive maintenance should be planned and
provided for through an on-going pavement management program. Maintenance activities are
intended to slow the rate of pavement deterioration and to preserve the pavement investment.
Maintenance consists of both localized maintenance (e.g. crack and joint sealing and patching)
and global maintenance (e.g. surface sealing). Preventive maintenance is usually the priority
when implementing a pavement maintenance program. Additional engineering observation is
recommended to determine the type and extent of a cost-effective program. Even with periodic
maintenance, some movements and related cracking may still occur and repairs may be required.
Pavement performance is affected by its surroundings. In addition to providing preventive
maintenance, the civil engineer should consider the following recommendations in the design and
layout of pavements:
■ Final grade adjacent to paved areas should slope down from the edges at a minimum 2%
■ Subgrade and pavement surfaces should have a minimum 2% slope to promote proper
surface drainage
■ Install below pavement drainage systems surrounding areas anticipated for frequent
wetting
■ Install joint sealant and seal cracks immediately
■ Seal all landscaped areas in or adjacent to pavements to reduce moisture migration to
subgrade soils
■ Place compacted, low permeability backfill against the exterior side of curb and gutter;
and
■ Place curb, gutter and/or sidewalk directly on clay subgrade soils rather than on
unbound granular base course materials
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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CORROSIVITY
Results of water-soluble sulfate testing indicate that ASTM Type I or II portland cement should be
specified for all project concrete on and below grade. Foundation concrete should be designed
for low sulfate exposure in accordance with the provisions of the ACI Design Manual, Section
318, Chapter 4.
GENERAL COMMENTS
Our services are conducted with the understanding of the project as described in the proposal,
and will incorporate collaboration with the design team as we complete our services to verify
assumptions. Revision of our understanding to reflect actual conditions important to our services
will be based on these verifications and will be reflected in the final report. The design team should
collaborate with Terracon to confirm these assumptions and to prepare the final design plans and
specifications. This facilitates the incorporation of our opinions related to implementation of our
geotechnical recommendations. Any information conveyed prior to the final report is for
informational purposes only and should not be considered or used for decision-making purposes.
Our analysis and opinions are based upon our understanding of the geotechnical conditions in
the area, the data obtained from our site exploration and from our understanding of the project.
Variations will occur between exploration point locations, across the site, or due to the modifying
effects of construction or weather. The nature and extent of such variations may not become
evident until during or after construction. Terracon should be retained as the Geotechnical
Engineer, where noted in the final report, to provide observation and testing services during
grading, excavation, foundation construction and other earth-related construction phases of the
project. If variations appear, we can provide further evaluation and supplemental
recommendations. If variations are noted in the absence of our observation and testing services
on-site, we should be immediately notified so that we can provide evaluation and supplemental
recommendations.
Our scope of services does not include either specifically or by implication any environmental or
biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of
pollutants, hazardous materials or conditions. If the owner is concerned about the potential for
such contamination or pollution, other studies should be undertaken.
Our services and any correspondence are intended for the sole benefit and exclusive use of our
client for specific application to the project discussed and are accomplished in accordance with
generally accepted geotechnical engineering practices with no third party beneficiaries intended.
Any third party access to services or correspondence is solely for information purposes only.
Reliance upon the services and any work product is limited to our client, and is not intended for
third parties. Any use or reliance of the provided information by third parties is done solely at their
own risk. No warranties, either express or implied, are intended or made.
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
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Site characteristics as provided are for design purposes and not to estimate excavation cost. Any
use of our report in that regard is done at the sole risk of the excavating cost estimator as there
may be variations on the site that are not apparent in the data that could significantly impact
excavation cost. Any parties charged with estimating excavation costs should seek their own site
characterization for specific purposes to obtain the specific level of detail necessary for costing.
Site safety, and cost estimating including, excavation support, and dewatering
requirements/design are the responsibility of others. If changes in the nature, design, or location
of the project are planned, our conclusions and recommendations shall not be considered valid
unless we review the changes and either verify or modify our conclusions in writing.
ATTACH MENTS
ATTACHMENTS
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
Responsive ■ Resourceful ■ Reliable
EXPLORATION AND TESTING PROCEDURES
Field Exploration
Number of Borings Boring Depth (feet) Planned Location
2 10½ Fire Access Road
3 34¾ to 35½ Building Addition Areas
Boring Layout and Elevations: We use handheld GPS equipment to locate borings with an
estimated horizontal accuracy of +/-20 feet. Field measurements from existing site features may
be utilized. If available, approximate elevations are obtained by interpolation from a site specific,
surveyed topographic map. It should be noted that original locations of Borings B4 to B5 were
moved up to about 50 feet to the south due to site access with conventional truck-mounted drill
rig equipment and avoid drilling on the slope.
Subsurface Exploration Procedures: We advance the borings with a truck-mounted drill rig
using continuous flight augers (solid stem and/or hollow stem as necessary depending on soil
conditions). Three samples are obtained in the upper 10 feet of each boring and at intervals of 5
feet thereafter. In the split-barrel sampling procedure, a standard 2-inch outer diameter split-barrel
sampling spoon is driven into the ground by a 140-pound automatic hammer falling a distance of 30
inches. The number of blows required to advance the sampling spoon the last 12 inches of a normal
18-inch penetration is recorded as the Standard Penetration Test (SPT) resistance value. The SPT
resistance values, also referred to as N-values, are indicated on the boring logs at the test depths. A
3-inch O.D. split-barrel sampling spoon with 2.5-inch I.D. ring lined sampler is used for sampling
at various depths within the upper 14 feet. Ring-lined, split-barrel sampling procedures are similar
to standard split spoon sampling procedure; however, blow counts are typically recorded for 6-
inch intervals for a total of 12 inches of penetration. We observe and record groundwater levels
during drilling and sampling. For safety purposes, all borings are backfilled with auger cuttings
after their completion.
Our exploration team prepares field boring logs as part of standard drilling operations including
sampling depths, penetration distances, and other relevant sampling information. Field logs include
visual classifications of materials encountered during drilling, and our interpretation of subsurface
conditions between samples. Final boring logs, prepared from field logs, represent the
geotechnical engineer's interpretation, and include modifications based on observations and
laboratory tests.
The sampling depths, penetration distances, and other sampling information are recorded on the
field boring logs. The samples are placed in appropriate containers and taken to our soil laboratory
for testing and classification by a geotechnical engineer. Our exploration team prepares field boring
Geotechnical Engineering Report
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
Responsive ■ Resourceful ■ Reliable
logs as part of the drilling operations. These field logs include visual classifications of the materials
encountered during drilling and our interpretation of the subsurface conditions between samples.
Final boring logs are prepared from the field logs. The final boring logs represent the geotechnical
engineer's interpretation of the field logs and include modifications based on observations and
tests of the samples in our laboratory.
Laboratory Testing
The project engineer reviews the field data and assigns various laboratory tests to better
understand the engineering properties of the various soil and rock strata as necessary for this
project. Procedural standards noted in this report are for reference to methodology in general. In
some cases, variations to methods are applied because of local practice or professional judgment.
Testing was performed under the direction of a geotechnical engineer and included the following:
n Visual classification n Atterberg limits
n Grain-size distribution
n Consolidation/swell
n Water-soluble sulfate content
n Dry density
n Unconfined compression
n Moisture content
The laboratory testing program often includes examination of soil samples by an engineer. Based
on the material’s texture and plasticity, we describe and classify the soil samples in accordance
with the Unified Soil Classification System.
If bedrock samples are obtained, rock classification is conducted using locally accepted practices
for engineering purposes. Boring log rock classification is determined using the Description of
Rock Properties.
SITE LOCA TION AND EXPLORATION PLANS
SITE LOCATION AND EXPLORATION PLANS
SITE LOCATION
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, CO
October 18, 2017 ■ Terracon Project No. 20175063
TOPOGRAPHIC MAP IMAGE COURTESY OF THE U.S. GEOLOGICAL SURVEY
QUADRANGLES INCLUDE: FORT COLLINS, CO (1984) and LOVELAND, CO (1984).
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS
NOT INTENDED FOR CONSTRUCTION PURPOSES
SITE
EXPLORATION PLAN
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, CO
October 18, 2017 ■ Terracon Project No. 20175063
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS
NOT INTENDED FOR CONSTRUCTION PURPOSES
AERIAL PHOTOGRAPHY PROVIDED
BY MICROSOFT BING MAPS
Southridge Green Boulevard
South Lemay Avenue
Original proposed boring
locations were moved
due to site access.
Proposed
Building
Addition
EXPLORATION RESULTS
EXPLORATION RESULTS
15 66
23
18
106 30-15-15
4962
4952
4951.5
4-5
1-1-2
N=3
7-13-18
N=31
-0.04%
@ 150
psf
0.3
10.0
10.5
TOPSOIL, lean clay with vegetation, about 4 inches
thick
SANDY LEAN CLAY (CL), trace silt, light brown, soft
to medium stiff
WEATHERED CLAYSTONE, brown gray with orange,
medium hard
Boring Terminated at 10.5 Feet
GRAPHIC LOG
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20175063 ST. ELIZABETH ANN.GPJ TERRACON_DATATEMPLATE.GDT 10/10/17
UNCONFINED
COMPRESSIVE
STRENGTH (psf)
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
LL-PL-PI
ATTERBERG
LIMITS
ELEVATION (Ft.)
Surface Elev.: 4962.2 (Ft.)
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
SAMPLE TYPE
FIELD TEST
RESULTS
SWELL (%)
DEPTH
LOCATION
Latitude: 40.51069° Longitude: -105.05748°
See Exploration Plan
Page 1 of 1
Advancement Method:
4-inch solid stem auger
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Dr Ste C
20 59
22
20
105 33-14-19
4953
4944
4942.5
5-5
2-3-3
N=6
3-5-8
N=13
0.3
9.0
10.5
TOPSOIL, lean clay with vegetation, about 4 inches
thick
SANDY LEAN CLAY (CL), trace silt, light brown,
medium stiff
WEATHERED CLAYSTONE, with silt, brown gray with
orange, weathered
Boring Terminated at 10.5 Feet
GRAPHIC LOG
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20175063 ST. ELIZABETH ANN.GPJ TERRACON_DATATEMPLATE.GDT 10/10/17
UNCONFINED
COMPRESSIVE
STRENGTH (psf)
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
LL-PL-PI
ATTERBERG
LIMITS
ELEVATION (Ft.)
Surface Elev.: 4953.1 (Ft.)
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
SAMPLE TYPE
FIELD TEST
RESULTS
SWELL (%)
DEPTH
LOCATION
Latitude: 40.5102° Longitude: -105.05734°
See Exploration Plan
Page 1 of 1
Advancement Method:
4-inch solid stem auger
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Dr Ste C
Fort Collins, CO
Notes:
Project No.: 20175063
9180
70
19
20
18
18
17
15
22
104
106
108
35-15-20
43-18-25
4935.5
4929.5
4913
4-4
2-3-3
N=6
5-6
7-9-13
N=22
50/9"
14-23-29
N=52
16-23-33
N=56
20-21-24
N=45
-1.0% @
1,000
psf
13.0
19.0
35.5
SANDY LEAN CLAY (CL), trace silt, light brown,
medium stiff to stiff
WEATHERED CLAYSTONE, with silt, brown gray with
orange, firm
SEDIMENTARY BEDROCK - CLAYSTONE, with silt,
grayish-brown with orange, hard
Boring Terminated at 35.5 Feet
GRAPHIC LOG
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20175063 ST. ELIZABETH ANN.GPJ TERRACON_DATATEMPLATE.GDT 10/10/17
UNCONFINED
COMPRESSIVE
STRENGTH (psf)
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
LL-PL-PI
ATTERBERG
LIMITS
ELEVATION (Ft.)
Surface Elev.: 4948.6 (Ft.)
WATER LEVEL
8
9
18
19
19
17
16
16
108
103
4947.5
4929
4926
4913.5
6-6-6
N=12
13-15
4-6-7
N=13
6-7
6-9-15
N=24
15-22-34
N=56
50/9"
N=50/9"
50/9"
N=50/9"
+0.7%
@ 1,000
psf
0.5
19.0
22.0
34.8
TOPSOIL, lean clay with vegetation, about 6 inches
LEAN CLAY (CL), trace silt, light brown, stiff to very
stiff
WEATHERED CLAYSTONE, with silt, brown gray with
orange, very stiff
SEDIMENTARY BEDROCK - CLAYSTONE, with silt,
grayish-brown with orange, hard to very hard
Boring Terminated at 34.8 Feet
GRAPHIC LOG
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20175063 ST. ELIZABETH ANN.GPJ TERRACON_DATATEMPLATE.GDT 10/10/17
UNCONFINED
COMPRESSIVE
STRENGTH (psf)
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
LL-PL-PI
ATTERBERG
LIMITS
ELEVATION (Ft.)
Surface Elev.: 4948.1 (Ft.)
WATER LEVEL
19
21
17
18
17
16
17
109
113 52-19-33
4963
4949.5
4944.5
4933
1-1-2
N=3
1-2-2
N=4
4-7
9-11-15
N=26
50/5"
17-28-42
N=70
21-26-39
N=65
+4.2%
@ 1,000
psf
0.5
14.0
19.0
30.5
TOPSOIL, lean clay with vegetation, about 6 inches
LEAN CLAY (CL), trace silt, light brown, soft to stiff
WEATHERED CLAYSTONE, with silt, brown gray with
orange, firm to very hard
SEDIMENTARY BEDROCK - CLAYSTONE, with
sand, grayish-brown with orange, hard
Boring Terminated at 30.5 Feet
GRAPHIC LOG
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20175063 ST. ELIZABETH ANN.GPJ TERRACON_DATATEMPLATE.GDT 10/10/17
UNCONFINED
COMPRESSIVE
STRENGTH (psf)
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
LL-PL-PI
ATTERBERG
LIMITS
ELEVATION (Ft.)
Surface Elev.: 4963.7 (Ft.)
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
4,910
4,915
4,920
4,925
4,930
4,935
4,940
4,945
4,950
4,955
4,960
4,965
4,970
0 5 10 15 20 25 30
4,910
4,915
4,920
4,925
4,930
4,935
4,940
4,945
4,950
4,955
4,960
4,965
4,970
0 5 10 15 20 25 30
Borehole
Termination Type
Borehole
Lithology
Explanation
Distance Along Baseline - Feet
Elevation - Feet
NOTES:
Topsoil Lean Clay Weathered
Rock
Sampling
(See General Notes)
See Exhibit Exploration Plan for orientation of soil profile.
See General Notes in Appendix for symbols and soil classifications.
Soils profile provided for illustration purposes only.
Soils between borings may differ
AR - Auger Refusal
BT - Boring Termination
SouthwestNortheast
Water Level Reading
after drilling.
Water Level Reading
at time of drilling.
B4
Moisture %w
Content
LL PL
AR
BT
Liquid and Plastic Limits
Borehole
Number
0
10
20
30
40
50
60
0 20 40 60 80 100
CL or OL CH or OH
ML or OL
MH or OH
Boring ID Depth PL PI Description
SANDY LEAN CLAY
SANDY LEAN CLAY
SANDY LEAN CLAY
CLAYSTONE
CLAYSTONE
CL
CL
CL
Fines
P
L
A
S
T
I
C
I
T
Y
I
N
D
E
X
LIQUID LIMIT
"U" Line
"A" Line
30
33
35
43
52
15
14
15
18
19
15
19
20
25
33
66
59
70
LL USCS
B1
B2
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
100 10 1 0.1 0.01 0.001
B1
B2
B3
30
33
35
0.078
19
19
19
6 16
20 30
40 50
1.5 6 200
810
0.1
0.0
0.0
14
66.1
59.0
70.0
%Fines
LL PL PI
1 4
3/4 1/2
60
fine
B1
B2
B3
GRAIN SIZE IN MILLIMETERS
PERCENT FINER BY WEIGHT
coarse fine
U.HYDROMETERS. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
15
14
15
-5
-4
-3
-2
-1
0
1
2
3
4
5
100 1,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited 0.04% collapse when inundated at the pressure of 150 psf.
PROJECT: St. Elizabeth Ann Seton PROJECT NUMBER: 20175063
Catholic Parish Addition
SITE: 5450 South Lemay Avenue
Fort Collins, CO
CLIENT: St. Elizabeth Ann Seton
Catholic Church
1901 Sharp Point Dr Ste C Fort Collins, CO
Fort Collins, CO
Specimen Identification Classification , pcf
106 15
WC, %
B1 2 - 3 ft LEAN CLAY
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. 65155045-SWELL/CONSOL 20175063 ST. ELIZABETH ANN.GPJ TERRACON_DATATEMPLATE.GDT 10/10/17
-5
-4
-3
-2
-1
0
1
2
3
4
5
100 1,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited 1.0% collapse when inundated at the pressure of 1,000 psf.
PROJECT: St. Elizabeth Ann Seton PROJECT NUMBER: 20175063
Catholic Parish Addition
SITE: 5450 South Lemay Avenue
Fort Collins, CO
CLIENT: St. Elizabeth Ann Seton
Catholic Church
1901 Sharp Point Dr Ste C Fort Collins, CO
Fort Collins, CO
Specimen Identification Classification , pcf
106 20
WC, %
B3 9 - 10 ft LEAN CLAY
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. 65155045-SWELL/CONSOL 20175063 ST. ELIZABETH ANN.GPJ TERRACON_DATATEMPLATE.GDT 10/10/17
-5
-4
-3
-2
-1
0
1
2
3
4
5
100 1,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited 0.7% swell when inundated at the pressure of 1,000 psf.
PROJECT: St. Elizabeth Ann Seton PROJECT NUMBER: 20175063
Catholic Parish Addition
SITE: 5450 South Lemay Avenue
Fort Collins, CO
CLIENT: St. Elizabeth Ann Seton
Catholic Church
1901 Sharp Point Dr Ste C Fort Collins, CO
Fort Collins, CO
Specimen Identification Classification , pcf
108 9
WC, %
B4 4 - 5 ft LEAN CLAY
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. 65155045-SWELL/CONSOL 20175063 ST. ELIZABETH ANN.GPJ TERRACON_DATATEMPLATE.GDT 10/10/17
-5
-4
-3
-2
-1
0
1
2
3
4
5
100 1,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited 4.2% swell when inundated at the pressure of 1,000 psf.
PROJECT: St. Elizabeth Ann Seton PROJECT NUMBER: 20175063
Catholic Parish Addition
SITE: 5450 South Lemay Avenue
Fort Collins, CO
CLIENT: St. Elizabeth Ann Seton
Catholic Church
1901 Sharp Point Dr Ste C Fort Collins, CO
Fort Collins, CO
Specimen Identification Classification , pcf
113 17
WC, %
B5 19 - 19.9 ft CLAYSTONE
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. 65155045-SWELL/CONSOL 20175063 ST. ELIZABETH ANN.GPJ TERRACON_DATATEMPLATE.GDT 10/10/17
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
10,000
0 1.0 2.0 3.0 4.0
COMPRESSIVE STRESS - psf
AXIAL STRAIN - %
ASTM D2166
UNCONFINED COMPRESSION TEST
1901 Sharp Point Dr Ste C
Fort Collins, CO
PROJECT NUMBER: 20175063
SITE: 5450 South Lemay Avenue
Fort Collins, CO
CLIENT: St. Elizabeth Ann Seton Catholic
Church
Fort Collins, CO
PROJECT: St. Elizabeth Ann Seton Catholic
Parish Addition
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. UNCONFINED 20175063 ST. ELIZABETH ANN.GPJ TERRACON_DATATEMPLATE.GDT 10/10/17
SAMPLEfeet TYPE: D&M RING SAMPLE LOCATION: B3 @ 19 - 19.75
108
Strain Rate: in/min
Failure Strain: %
SPECIMEN FAILURE MODE
Calculated Saturation: %
Height: in.
Diameter: in.
Failure Mode: Bulge (dashed)
Remarks:
LL PL PI Percent < #200 Sieve
4591
18
DESCRIPTION: CLAYSTONE BEDROCK
Dry Density: pcf
Moisture Content: %
3.74
Height / Diameter Ratio: 2.44
Calculated Void Ratio:
Undrained Shear Strength: (psf)
Unconfined Compressive Strength (psf)
Assumed Specific Gravity:
9181
5.89
2.41
SPECIMEN TEST DATA
SUPPORTING INFORMATION
SUPPORTING INFORMATION
UNIFIED SOIL CLASSIFICATION SYSTEM
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
UNIFIED SOI L CLASSI FICATI ON SYSTEM
Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A
Soil Classification
Group
Symbol Group Name
B
Coarse-Grained Soils:
More than 50% retained
on No. 200 sieve
Gravels:
More than 50% of
coarse fraction
retained on No. 4 sieve
Clean Gravels:
Less than 5% fines C
Cu ‡ 4 and 1 £ Cc £ 3 E GW Well-graded gravel
F
Cu < 4 and/or 1 > Cc > 3 E GP Poorly graded gravel
F
Gravels with Fines:
More than 12% fines C
Fines classify as ML or MH GM Silty gravel F,G,H
Fines classify as CL or CH GC Clayey gravel F,G,H
Sands:
50% or more of coarse
fraction passes No. 4
sieve
Clean Sands:
Less than 5% fines D
Cu ‡ 6 and 1 £ Cc £ 3 E SW Well-graded sand
I
Cu < 6 and/or 1 > Cc > 3 E SP Poorly graded sand
I
Sands with Fines:
More than 12% fines D
Fines classify as ML or MH SM Silty sandG,H,I
Fines classify as CL or CH SC Clayey sandG,H,I
Fine-Grained Soils:
50% or more passes the
No. 200 sieve
Silts and Clays:
Liquid limit less than 50
Inorganic:
PI > 7 and plots on or above “A”
line J
CL Lean clayK,L,M
PI < 4 or plots below “A” lineJ ML Silt
K,L,M
Organic:
Liquid limit - oven dried
< 0.75 OL Organic clay
K,L,M,N
Liquid limit - not dried Organic silt K,L,M,O
Silts and Clays:
Liquid limit 50 or more
Inorganic:
PI plots on or above “A” line CH Fat clayK,L,M
DESCRIPTION OF ROCK PROPERTIES
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
ROCK VERSION 1
WEATHERING
Term Description
Unweathered No visible sign of rock material weathering, perhaps slight discoloration on major discontinuity surfaces.
Slightly
Weathered
Discoloration indicates weathering of rock material and discontinuity surfaces. All the rock material may be
discolored by weathering and may be somewhat weaker externally than in its fresh condition.
Moderately
Weathered
Less than half of the rock material is decomposed and/or disintegrated to a soil. Fresh or discolored rock is
present either as a continuous framework or as corestones.
Highly
Weathered
More than half of the rock material is decomposed and/or disintegrated to a soil. Fresh or discolored rock is
present either as a discontinuous framework or as corestones.
Completely
Weathered All rock material is decomposed and/or disintegrated to soil. The original mass structure is still largely intact.
Residual Soil All rock material is converted to soil. The mass structure and material fabric are destroyed. There is a large
change in volume, but the soil has not been significantly transported.
STRENGTH OR HARDNESS
Description Field Identification Uniaxial Compressive
Strength, psi (MPa)
Extremely Weak Indented by thumbnail 40-150 (0.3-1)
Very Weak Crumbles under firm blows with point of geological hammer, can be
peeled by a pocket knife 150-700 (1-5)
Weak Rock Can be peeled by a pocket knife with difficulty, shallow indentations
made by firm blow with point of geological hammer 700-4,000 (5-30)
Medium Strong Cannot be scraped or peeled with a pocket knife, specimen can be
fractured with single firm blow of geological hammer 4,000-7,000 (30-50)
Strong Rock Specimen requires more than one blow of geological hammer to
fracture it 7,000-15,000 (50-100)
Very Strong Specimen requires many blows of geological hammer to fracture it 15,000-36,000 (100-250)
Extremely Strong Specimen can only be chipped with geological hammer >36,000 (>250)
DISCONTINUITY DESCRIPTION
Fracture Spacing (Joints, Faults, Other Fractures) Bedding Spacing (May Include Foliation or Banding)
Description Spacing Description Spacing
Extremely Close < ¾ in (<19 mm) Laminated < ½ in (<12 mm)
Very Close ¾ in – 2-1/2 in (19 - 60 mm) Very thin ½ in – 2 in (12 – 50 mm)
Close 2-1/2 in – 8 in (60 – 200 mm) Thin 2 in – 1 ft. (50 – 300 mm)
Moderate 8 in – 2 ft. (200 – 600 mm) Medium 1 ft. – 3 ft. (300 – 900 mm)
Wide 2 ft. – 6 ft. (600 mm – 2.0 m) Thick 3 ft. – 10 ft. (900 mm – 3 m)
Very Wide 6 ft. – 20 ft. (2.0 – 6 m) Massive > 10 ft. (3 m)
Discontinuity Orientation (Angle): Measure the angle of discontinuity relative to a plane perpendicular to the longitudinal axis of the
core. (For most cases, the core axis is vertical; therefore, the plane perpendicular to the core axis is horizontal.) For example, a
horizontal bedding plane would have a 0-degree angle.
ROCK QUALITY DESIGNATION (RQD) 1
Description RQD Value (%)
Very Poor 0 - 25
Poor 25 – 50
Fair 50 – 75
Good 75 – 90
Excellent 90 - 100
1. The combined length of all sound and intact core segments equal to or greater than 4 inches in length, expressed as a
percentage of the total core run length.
Reference: U.S. Department of Transportation, Federal Highway Administration, Publication No FHWA-NHI-10-034, December 2009
Technical Manual for Design and Construction of Road Tunnels – Civil Elements
DESCRIPTION OF ROCK PROPERTIES
St. Elizabeth Ann Seton Catholic Parish Addition ■ Fort Collins, Colorado
September 28, 2017 ■ Terracon Project No. 20175063
ROCK VERSION 2
WEATHERING
Fresh Rock fresh, crystals bright, few joints may show slight staining. Rock rings under hammer if crystalline.
Very Slight Rock generally fresh, joints stained, some joints may show thin clay coatings, crystals in broken face show
bright. Rock rings under hammer if crystalline.
Slight Rock generally fresh, joints stained, and discoloration extends into rock up to 1 in. Joints may contain clay. In
granitoid rocks some occasional feldspar crystals are dull and discolored. Crystalline rocks ring under hammer.
Moderate
Significant portions of rock show discoloration and weathering effects. In granitoid rocks, most feldspars are
dull and discolored; some show clayey. Rock has dull sound under hammer and shows significant loss of
strength as compared with fresh rock.
Moderately Severe All rock except quartz discolored or stained. In granitoid rocks, all feldspars dull and discolored and majority
show kaolinization. Rock shows severe loss of strength and can be excavated with geologist’s pick.
Severe All rock except quartz discolored or stained. Rock “fabric” clear and evident, but reduced in strength to strong
soil. In granitoid rocks, all feldspars kaolinized to some extent. Some fragments of strong rock usually left.
Very Severe All rock except quartz discolored or stained. Rock “fabric” discernible, but mass effectively reduced to “soil”
with only fragments of strong rock remaining.
Complete Rock reduced to “soil”. Rock “fabric” no discernible or discernible only in small, scattered locations. Quartz
may be present as dikes or stringers.
HARDNESS (for engineering description of rock – not to be confused with Moh’s scale for minerals)
Very Hard Cannot be scratched with knife or sharp pick. Breaking of hand specimens requires several hard blows of
geologist’s pick.
Hard Can be scratched with knife or pick only with difficulty. Hard blow of hammer required to detach hand specimen.
Moderately Hard Can be scratched with knife or pick. Gouges or grooves to ¼ in. deep can be excavated by hard blow of point
of a geologist’s pick. Hand specimens can be detached by moderate blow.
Medium Can be grooved or gouged 1/16 in. deep by firm pressure on knife or pick point. Can be excavated in small
chips to pieces about 1-in. maximum size by hard blows of the point of a geologist’s pick.
Soft Can be gouged or grooved readily with knife or pick point. Can be excavated in chips to pieces several inches
in size by moderate blows of a pick point. Small thin pieces can be broken by finger pressure.
Very Soft Can be carved with knife. Can be excavated readily with point of pick. Pieces 1-in. or more in thickness can
be broken with finger pressure. Can be scratched readily by fingernail.
Joint, Bedding, and Foliation Spacing in Rock 1
Spacing Joints Bedding/Foliation
Less than 2 in. Very close Very thin
2 in. – 1 ft. Close Thin
1 ft. – 3 ft. Moderately close Medium
3 ft. – 10 ft. Wide Thick
More than 10 ft. Very wide Very thick
1. Spacing refers to the distance normal to the planes, of the described feature, which are parallel to each other or nearly so.
Rock Quality Designator (RQD) 1 Joint Openness Descriptors
RQD, as a percentage Diagnostic description Openness Descriptor
Exceeding 90 Excellent No Visible Separation Tight
90 – 75 Good Less than 1/32 in. Slightly Open
75 – 50 Fair 1/32 to 1/8 in. Moderately Open
50 – 25 Poor 1/8 to 3/8 in. Open
Less than 25 Very poor 3/8 in. to 0.1 ft. Moderately Wide
1. RQD (given as a percentage) = length of core in pieces 4
inches and longer / length of run
Greater than 0.1 ft. Wide
References: American Society of Civil Engineers. Manuals and Reports on Engineering Practice - No. 56. Subsurface Investigation for
Design and Construction of Foundations of Buildings. New York: American Society of Civil Engineers, 1976. U.S.
Department of the Interior, Bureau of Reclamation, Engineering Geology Field Manual.
PI plots below “A” line MH Elastic Silt K,L,M
Organic:
Liquid limit - oven dried
< 0.75 OH Organic clay
K,L,M,P
Liquid limit - not dried Organic silt K,L,M,Q
Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat
A Based on the material passing the 3-inch (75-mm) sieve
B If field sample contained cobbles or boulders, or both, add “with cobbles
or boulders, or both” to group name.
C Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded
gravel with silt, GW-GC well-graded gravel with clay, GP-GM poorly
graded gravel with silt, GP-GC poorly graded gravel with clay.
D Sands with 5 to 12% fines require dual symbols: SW-SM well-graded
sand with silt, SW-SC well-graded sand with clay, SP-SM poorly graded
sand with silt, SP-SC poorly graded sand with clay
E Cu = D60/D10 Cc =
10 60
2
30
D x D
(D )
F If soil contains ‡ 15% sand, add “with sand” to group name.
G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.
H If fines are organic, add “with organic fines” to group name.
I If soil contains ‡ 15% gravel, add “with gravel” to group name.
J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay.
K If soil contains 15 to 29% plus No. 200, add “with sand” or “with
gravel,” whichever is predominant.
L If soil contains ‡ 30% plus No. 200 predominantly sand, add
“sandy” to group name.
MIf soil contains ‡ 30% plus No. 200, predominantly gravel, add
“gravelly” to group name.
NPI‡ 4 and plots on or above “A” line.
OPI< 4 or plots below “A” line.
P PI plots on or above “A” line.
QPI plots below “A” line.
15
19
20
D100
Cc Cu
SILT OR CLAY
4
D30 D10 %Gravel %Sand
2 - 3
2 - 3
4 - 5.5
3/8 3 100
3 2 140
COBBLES
GRAVEL SAND
USCS Classification
33.5
40.6
28.4
D60
coarse medium
Boring ID Depth
Boring ID Depth
GRAIN SIZE DISTRIBUTION
2 - 3
2 - 3
4 - 5.5
SANDY LEAN CLAY (CL)
SANDY LEAN CLAY (CL)
SANDY LEAN CLAY (CL)
ASTM D422 / ASTM C136
PROJECT NUMBER: 20175063
PROJECT: St. Elizabeth Ann Seton Catholic
Parish Addition
SITE: 5450 South Lemay Avenue
Fort Collins, CO
CLIENT: St. Elizabeth Ann Seton Catholic
Church
Fort Collins, CO
EXHIBIT: B-1
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS-2 20175063 ST. ELIZABETH ANN.GPJ 35159097 - ATTERBERG ISSUE.GPJ 9/18/17
B3
B3
B5
ATTERBERG LIMITS RESULTS
ASTM D4318
2 - 3
2 - 3
4 - 5.5
24 - 25.5
19 - 19.9
PROJECT NUMBER: 20175063
PROJECT: St. Elizabeth Ann Seton Catholic
Parish Addition
SITE: 5450 South Lemay Avenue
Fort Collins, CO
CLIENT: St. Elizabeth Ann Seton Catholic
Church
Fort Collins, CO
EXHIBIT: B-1
1901 Sharp Point Dr Ste C
Fort Collins, CO
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. ATTERBERG LIMITS 20175063 ST. ELIZABETH ANN.GPJ TERRACON2015.GDT 9/18/17
CL-ML
1901 Sharp Point Dr Ste C
Fort Collins, CO
PH. 970-484-0359 FAX. 970-484-0454
Project Manager: EDB SUBSURFACE PROFILE EXHIBIT
SW to NE Soil Profile
ST. ELIZABETH ANN SETON CATHOLIC PARISH ADDITION
5450 SOUTH LEMAY AVENUE
FORT COLLINS, CO
File Name: 20175063
Scale: N.T.S
Project No.: 20175063
Drawn by: RSG
Date: 10/10/2017
Approved by: EDB
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. SMART FENCE 20175063 ST. ELIZABETH ANN.GPJ TERRACON_DATATEMPLATE.GDT 10/10/17
8
9
18
19
19
17
16
16
50/9"
N=50/9"
50/9"
N=50/9" BT-34.8 Ft.
6-6-6
N=12
13-15
4-6-7
N=13
6-7
6-9-15
N=24
15-22-34
N=56
%w
B4
19
21
17
18
17
16
17
50/5" 52 19
BT-30.5 Ft.
1-1-2
N=3
1-2-2
N=4
4-7
9-11-15
N=26
17-28-42
N=70
21-26-39
N=65
%w LL PL
B5
Claystone
Bedrock
15
20
25
30
SAMPLE TYPE
FIELD TEST
RESULTS
SWELL (%)
DEPTH
LOCATION
Latitude: 40.50963° Longitude: -105.05644°
See Exploration Plan
Page 1 of 1
Advancement Method:
4-inch solid stem auger
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Dr Ste C
Fort Collins, CO
Notes:
Project No.: 20175063
Drill Rig: CME 75
Boring Started: 08-10-2017
BORING LOG NO. B5
CLIENT: St. Elizabeth Ann Seton Catholic Church
Fort Collins, CO
Driller: Dakota Drilling, Inc.
Boring Completed: 08-10-2017
PROJECT: St. Elizabeth Ann Seton Catholic Parish
Addition
See Exploration and Testing Procedures for a
description of field and laboratory procedures used
and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
5450 South Lemay Avenue
Fort Collins, CO
SITE:
No water encountered during exploration
WATER LEVEL OBSERVATIONS
OBSERVATIONS
DEPTH (Ft.)
5
10
15
20
25
30
SAMPLE TYPE
FIELD TEST
RESULTS
SWELL (%)
DEPTH
LOCATION
Latitude: 40.50948° Longitude: -105.05673°
See Exploration Plan
Page 1 of 1
Advancement Method:
4-inch solid stem auger
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Dr Ste C
Fort Collins, CO
Notes:
Project No.: 20175063
Drill Rig: CME 45
Boring Started: 08-25-2017
BORING LOG NO. B4
CLIENT: St. Elizabeth Ann Seton Catholic Church
Fort Collins, CO
Driller: Odell Drilling, Inc.
Boring Completed: 08-25-2017
PROJECT: St. Elizabeth Ann Seton Catholic Parish
Addition
See Exploration and Testing Procedures for a
description of field and laboratory procedures used
and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
5450 South Lemay Avenue
Fort Collins, CO
SITE:
No water encountered during exploration
WATER LEVEL OBSERVATIONS
OBSERVATIONS
DEPTH (Ft.)
5
10
15
20
25
30
35
SAMPLE TYPE
FIELD TEST
RESULTS
SWELL (%)
DEPTH
LOCATION
Latitude: 40.50961° Longitude: -105.05697°
See Exploration Plan
Page 1 of 1
Advancement Method:
4-inch solid stem auger
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Dr Ste C
Fort Collins, CO
Notes:
Project No.: 20175063
Drill Rig: CME 45
Boring Started: 08-25-2017
BORING LOG NO. B3
CLIENT: St. Elizabeth Ann Seton Catholic Church
Fort Collins, CO
Driller: Odell Drilling, Inc.
Boring Completed: 08-25-2017
PROJECT: St. Elizabeth Ann Seton Catholic Parish
Addition
See Exploration and Testing Procedures for a
description of field and laboratory procedures used
and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
5450 South Lemay Avenue
Fort Collins, CO
SITE:
No water encountered during exploration
WATER LEVEL OBSERVATIONS
Drill Rig: CME 45
Boring Started: 08-25-2017
BORING LOG NO. B2
CLIENT: St. Elizabeth Ann Seton Catholic Church
Fort Collins, CO
Driller: Odell Drilling, Inc.
Boring Completed: 08-25-2017
PROJECT: St. Elizabeth Ann Seton Catholic Parish
Addition
See Exploration and Testing Procedures for a
description of field and laboratory procedures used
and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
5450 South Lemay Avenue
Fort Collins, CO
SITE:
No water encountered during exploration
WATER LEVEL OBSERVATIONS
Fort Collins, CO
Notes:
Project No.: 20175063
Drill Rig: CME 45
Boring Started: 08-25-2017
BORING LOG NO. B1
CLIENT: St. Elizabeth Ann Seton Catholic Church
Fort Collins, CO
Driller: Odell Drilling, Inc.
Boring Completed: 08-25-2017
PROJECT: St. Elizabeth Ann Seton Catholic Parish
Addition
See Exploration and Testing Procedures for a
description of field and laboratory procedures used
and additional data (If any).
See Supporting Information for explanation of
symbols and abbreviations.
5450 South Lemay Avenue
Fort Collins, CO
SITE:
5' at completion of drilling
WATER LEVEL OBSERVATIONS
Fine Grained - 2.46
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(390)H
(295)H