HomeMy WebLinkAboutFORTY THREE PRIME - PDP - PDP180014 - SUBMITTAL DOCUMENTS - ROUND 1 - GEOTECHNICAL (SOILS) REPORTGeotechnical Engineering Report
St. Peter's Anglican Church
6608 Autumn Ridge Road
Fort Collins, Colorado
November 6, 2015
Terracon Project No. 20155045
Prepared for:
St. Peter's Anglican Church
Fort Collins, Colorado
Prepared by:
Terracon Consultants, Inc.
Fort Collins, Colorado
TABLE OF CONTENTS
Page
EXECUTIVE SUMMARY ............................................................................................................ i
1.0 INTRODUCTION .............................................................................................................1
2.0 PROJECT INFORMATION .............................................................................................2
2.1 Project Description ...............................................................................................2
2.2 Site Location and Description...............................................................................2
3.0 SUBSURFACE CONDITIONS ........................................................................................3
3.1 Typical Subsurface Profile ...................................................................................3
3.2 Laboratory Testing ...............................................................................................3
3.3 Corrosion Protection (Water-Soluble Sulfates) .....................................................3
3.4 Groundwater ........................................................................................................4
4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION ......................................4
4.1 Geotechnical Considerations ...............................................................................4
4.1.1 Expansive Soils and Bedrock ...................................................................4
4.1.2 Shallow Bedrock .......................................................................................5
4.1.3 Foundation and Floor Slab Recommendations .........................................5
4.2 Earthwork.............................................................................................................5
4.2.1 Site Preparation ........................................................................................6
4.2.2 Excavation ................................................................................................6
4.2.3 Subgrade Preparation ...............................................................................7
4.2.4 Fill Materials and Placement ......................................................................7
4.2.5 Compaction Requirements ........................................................................8
4.2.6 Utility Trench Backfill ................................................................................9
4.2.7 Grading and Drainage ...............................................................................9
4.2.8 Exterior Slab Design and Construction ...................................................10
4.3 Foundations .......................................................................................................10
4.3.1 Spread Footings - Design Recommendations .........................................11
4.3.2 Spread Footings - Construction Considerations ......................................12
4.4 Seismic Considerations......................................................................................12
4.5 Floor Systems ....................................................................................................13
4.5.1 Floor System - Design Recommendations ..............................................13
4.5.2 Floor Systems - Construction Considerations .........................................14
4.6 Pavements .........................................................................................................14
4.6.1 Pavements – Subgrade Preparation .......................................................14
4.6.2 Pavements – Design Recommendations ................................................14
4.6.3 Pavements – Construction Considerations .............................................17
4.6.4 Pavements – Maintenance .....................................................................17
5.0 GENERAL COMMENTS ...............................................................................................18
TABLE OF CONTENTS (continued)
Appendix A – FIELD EXPLORATION
Exhibit A-1 Site Location Map
Exhibit A-2 Exploration Plan
Exhibit A-3 Field Exploration Description
Exhibits A-4 to A-12 Boring Logs
Appendix B – LABORATORY TESTING
Exhibit B-1 Laboratory Testing Description
Exhibit B-2 Atterberg Limits Test Results
Exhibit B-3 Grain-size Distribution Test Results
Exhibits B-4 to B-10 Swell-consolidation Test Results
Exhibit B-11 Water-soluble Sulfate Test Results
Appendix C – SUPPORTING DOCUMENTS
Exhibit C-1 General Notes
Exhibit C-2 Unified Soil Classification System
Exhibit C-3 Description of Rock Properties
Exhibit C-4 Laboratory Test Significance and Purpose
Exhibits C-5 and C-6 Report Terminology
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St. Peter's Anglican Church ■ Fort Collins, Colorado
November 6, 2015 ■ Terracon Project No. 20155045
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EXECUTIVE SUMMARY
A geotechnical investigation has been performed for the proposed St. Peter's Anglican Church to
be constructed at 6608 Autumn Ridge Road in Fort Collins, Colorado. Nine (9) borings,
presented as Exhibits A-4 through A-12 and designated as Boring No. 1 through Boring No. P4,
were performed to depths of approximately 5 to 30 feet below existing site grades. This report
specifically addresses the recommendations for the proposed church and associated pavements.
Borings performed in these areas are for informational purposes and will be utilized by others.
Based on the information obtained from our subsurface exploration, the site can be developed for
the proposed project. However, the following geotechnical considerations were identified and will
need to be considered:
The proposed church may be supported on shallow foundations bearing on a minimum
of 4 feet of over-excavated properly prepared on-site soils and/or bedrock or on newly
placed engineered fill. We recommend the footing foundations be designed to maintain
a minimum dead load pressure of 500 psf.
A slab-on-grade floor system is recommended for the proposed building provided the
subgrade soils and/or bedrock are over-excavated a minimum of 2 feet, scarified, moisture
conditioned, and recompacted as presented is the 4.2 Earthwork section of this report.
Proposed pavements should not bear directly on the bedrock below this site. In areas
where bedrock is encountered in excavations below pavements, we recommend over-
excavating a minimum of 1 foot below the pavement subgrade, moisture conditioning and
recompacting as presented is the 4.2 Earthwork section of this report.
The amount of movement of foundations, floor slabs, pavements, etc. will be related to the
wetting of underlying supporting soils. Therefore, it is imperative the recommendations
discussed in the 4.2.7 Grading and Drainage section of this report be followed to reduce
potential movement.
The 2012 International Building Code, Table 1613.5.2 IBC seismic site classification for this
site is C.
Close monitoring of the construction operations discussed herein will be critical in
achieving the design subgrade support. We therefore recommend that Terracon be
retained to monitor this portion of the work.
This summary should be used in conjunction with the entire report for design purposes. It
should be recognized that details were not included or fully developed in this section, and the
report must be read in its entirety for a comprehensive understanding of the items contained
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herein. The section titled GENERAL COMMENTS should be read for an understanding of the
report limitations.
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GEOTECHNICAL ENGINEERING REPORT
St. Peter's Anglican Church
6608 Autumn Ridge Road
Fort Collins, Colorado
Terracon Project No. 20155045
November 6, 2015
1.0 INTRODUCTION
This report presents the results of our geotechnical engineering services performed for the
proposed St. Peter's Anglican Church to be located at 6608 Autumn Ridge Road in Fort Collins,
Colorado. The purpose of these services is to provide information and geotechnical engineering
recommendations relative to:
subsurface soil and bedrock conditions foundation design and construction
groundwater conditions floor slab design and construction
grading and drainage pavement construction
seismic considerations earthwork
Our geotechnical engineering scope of work for this project included the initial site visit, the
advancement of 9 test borings to depths ranging from approximately 5 to 30 feet below existing
site grades, laboratory testing for soil engineering properties and engineering analyses to
provide foundation, floor system and pavement design and construction recommendations.
Logs of the borings along with an Exploration Plan (Exhibit A-2) are included in Appendix A.
The results of the laboratory testing performed on soil and bedrock samples obtained from the
site during the field exploration are included in Appendix B.
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2.0 PROJECT INFORMATION
2.1 Project Description
Item Description
Site layout Refer to the Exploration Plan (Exhibit A-2 in Appendix A)
Proposed construction
Preliminary plans indicate the proposed construction will likely
include an approximately 10,400 square foot, single-story building
with paved access drives and parking areas. The church will be
located in the northwest corner of the property with parking in the
southwest portion of the lot. Irrigated playfield will be located
through the central portion of the property with storm water
detention areas and an outdoor theatre shown in the eastern
portion of the property. A bell tower with cross is shown on the
southeast corner of the proposed church and will likely be about 69
feet tall with a footprint of 10 feet by 10 feet.
Finished floor elevation
According to the preliminary plans, the finished floor elevation for
the church will be 4967.0 feet.
Maximum loads
Columns: 100 kips max. (assumed)
Walls: 1 to 3 klf (assumed)
Slabs: 100 to 200 psf max (assumed)
Grading
We estimate minor cuts and fills on the order of 5 feet or less will
be required.
Cut and fill slopes Assumed to be no steeper than 3H:1V (Horizontal to Vertical)
Below-grade areas No below-grade areas are planned.
Traffic loading (assumed)
NAPA Traffic Class:
Automobile Parking Areas: Class I
Truck traffic and main drives Class II
2.2 Site Location and Description
Item Description
Location
The site is located at 6608 Autumn Ridge Road in Fort Collins,
Colorado. We understand the church is in the process of changing
the address for the property to 812 Candlewood Drive, Fort Collins,
Colorado; however, this may occur at a later date.
Existing improvements
The site is currently undeveloped with surrounding roadways
paved with curb, gutter, and asphalt pavement.
Current ground cover The ground surface is covered with native grasses and weeds.
Existing topography The site is relatively flat.
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3.0 SUBSURFACE CONDITIONS
3.1 Typical Subsurface Profile
Specific conditions encountered at each boring location are indicated on the individual boring
logs included in Appendix A. Stratification boundaries on the boring logs represent the
approximate location of changes in soil types; in-situ, the transition between materials may be
gradual. Based on the results of the borings, subsurface conditions on the project site can be
generalized as follows:
Material Description
Approximate Depth to
Bottom of Stratum (feet)
Consistency/Density/Hardness
Topsoil About 6 inches thick. --
Lean to fat clay with varying
amounts of sand
About 2 to 14½ feet below
existing site grades except in
Boring No. P1.
Medium stiff to very stiff
Silt with sand
About 2 ½ feet below the
existing site graded in Boring
No. P1 only.
Very stiff
Claystone and sandstone bedrock
To the maximum depth of
exploration of about 30 feet.
Firm to very hard
3.2 Laboratory Testing
Representative soil and bedrock samples were selected for swell-consolidation testing and
exhibited no movement to 2.1 percent swell when wetted. Samples of site soils and bedrock
selected for plasticity testing exhibited non-plastic to high plasticity with liquid limits ranging from
non-plastic to 69 and plasticity indices ranging from 12 to 54. Laboratory test results are
presented in Appendix B.
3.3 Corrosion Protection (Water-Soluble Sulfates)
Results of water-soluble sulfate testing indicate that ASTM Type V or equivalent portland
cement should be specified for all project concrete on and below grade. As an alternative, ACI
allows the use of cement that conforms to ASTM C150 Type II requirements, if it meets the
Type V performance requirements (ASTM C452) of ASTM C150 Table 4. ACI 201 also allows a
blend of any type of portland cement and fly ash with an expansion of less than 0.05 percent at
6 months when tested in accordance with ASTM C1012. Foundation concrete should be
designed for severe sulfate exposure in accordance with the provisions of the ACI Design
Manual, Section 318, Chapter 4.
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3.4 Groundwater
The boreholes were observed while drilling and after completion for the presence and level of
groundwater. Delayed water levels were obtained in some borings. The water levels observed in
the boreholes are noted on the attached boring logs, and are summarized below:
Boring Number
Depth to groundwater several
days after drilling, ft.
Elevation of groundwater 8
days after drilling, ft.
1 16.3 78.7
2 20.8 78.5
3 13.9 86.3
4 23.3 77.5
5 21.5 78.3
These observations represent groundwater conditions at the time of the field exploration, and
may not be indicative of other times or at other locations. Groundwater levels can be expected
to fluctuate with varying seasonal and weather conditions, and other factors.
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.
4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION
4.1 Geotechnical Considerations
Based on subsurface conditions encountered in the borings, the site appears suitable for the
proposed construction from a geotechnical point of view provided certain precautions and
design and construction recommendations described in this report are followed. We have
identified geotechnical conditions that could impact design and construction of the proposed
structure, pavements, and other site improvements.
4.1.1 Expansive Soils and Bedrock
Laboratory testing indicates the native clay soils and claystone bedrock exhibited no movement
to 2.1 percent expansive potential at the samples in-situ moisture content. However, it is our
opinion these materials will exhibit a higher expansive potential if the clays and claystone
undergo a significant loss of moisture.
This report provides recommendations to help mitigate the effects of soil shrinkage and
expansion. However, even if these procedures are followed, some movement and cracking in
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St. Peter's Anglican Church ■ Fort Collins, Colorado
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the structure, pavements, and flatwork should be anticipated. The severity of cracking and
other damage such as uneven floor slabs will probably increase if any modification of the site
results in excessive wetting or drying of the expansive clays and/or claystone bedrock.
Eliminating the risk of movement and distress is generally not feasible, but it may be possible to
further reduce the risk of movement if significantly more expensive measures are used during
construction. It is imperative the recommendations described in section 4.2.7 Grading and
Drainage of this report be followed to reduce movement.
4.1.2 Shallow Bedrock
Firm to very hard bedrock was encountered at depths ranging from less than 2 feet to 14½ feet
below the existing ground surface. Shallow foundations, pavements, floor slabs, and other slab-
on-grade features should not bear directly on bedrock. Recommendations for over-excavation
of bedrock below these improvements are discussed in subsequent section of this report.
Excavation penetrating the bedrock may require the use of specialized heavy-duty equipment,
together with ripping or jack-hammering to advance the excavation and facilitate rock break-up
and removal. Consideration should be given to obtaining a unit price for difficult excavation in
the contract documents for the project. Shallow bedrock will also impact the installation of
buried utilities at this site.
4.1.3 Foundation and Floor Slab Recommendations
The proposed building may be supported on a spread footing foundation system bearing on
properly prepared on-site soils or properly placed imported fill. We recommend a slab-on-grade
for the interior floor system of the proposed building. Even when bearing on properly prepared
soils, movement of the slab-on-grade floor system is possible should the subgrade soils
undergo an increase in moisture content. We estimate movement of about 1 inch is possible. If
the owner cannot accept the risk of slab movement, a structural floor should be used.
The proposed church may be supported on shallow foundations bearing on a minimum of 4 feet
of over-excavated properly prepared on-site soils and/or bedrock or on newly placed engineered
fill. We recommend the footing foundations be designed to maintain a minimum dead load
pressure of 500 psf.
A slab-on-grade floor system is recommended for the proposed building provided the subgrade
soils and/or bedrock are over-excavated a minimum of 2 feet, scarified, moisture conditioned, and
recompacted as presented is the 4.2 Earthwork section of this report.
4.2 Earthwork
The following presents recommendations for site preparation, excavation, subgrade preparation
and placement of engineered fills on the project. All earthwork on the project should be
observed and evaluated by Terracon on a full-time basis. The evaluation of earthwork should
include observation of over-excavation operations, testing of engineered fills, subgrade
preparation, subgrade stabilization, and other geotechnical conditions exposed during the
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St. Peter's Anglican Church ■ Fort Collins, Colorado
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construction of the project.
4.2.1 Site Preparation
Prior to placing any fill, strip and remove existing vegetation, the recommended depth of over-
excavation, and any other deleterious materials from the proposed construction areas.
Stripped organic materials should be wasted from the site or used to re-vegetate landscaped
areas after completion of grading operations. Prior to the placement of fills, the site should be
graded to create a relatively level surface to receive fill, and to provide for a relatively uniform
thickness of fill beneath proposed structures.
4.2.2 Excavation
It is anticipated that excavations into on-site soils for the proposed construction can be
accomplished with conventional earthmoving equipment.
Excavation penetrating the bedrock may require the use of specialized heavy-duty equipment,
together with ripping or jack-hammering to advance the excavation and facilitate rock break-up
and removal. Consideration should be given to obtaining a unit price for difficult excavation in the
contract documents for the project.
The soils to be excavated can vary significantly across the site as their classifications are based
solely on the materials encountered in widely-spaced exploratory test borings. The contractor
should verify that similar conditions exist throughout the proposed area of excavation. If different
subsurface conditions are encountered at the time of construction, the actual conditions should be
evaluated to determine any excavation modifications necessary to maintain safe conditions.
Although evidence of fills or underground facilities such as septic tanks, vaults, basements, and
utilities was not observed during the site reconnaissance, such features could be encountered
during construction. If unexpected fills or underground facilities are encountered, such features
should be removed and the excavation thoroughly cleaned prior to backfill placement and/or
construction.
Any over-excavation that extends below the bottom of foundation elevation should extend laterally
beyond all edges of the foundations at least 8 inches per foot of over-excavation depth below the
foundation base elevation. The over-excavation should be backfilled to the foundation base
elevation in accordance with the recommendations presented in this report.
Depending upon depth of excavation and seasonal conditions, surface water infiltration and/or
groundwater may be encountered in excavations on the site. It is anticipated that pumping from
sumps may be utilized to control water within excavations.
The subgrade soil conditions should be evaluated during the excavation process and the stability
of the soils determined at that time by the contractors’ Competent Person. Slope inclinations
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flatter than the OSHA maximum values may have to be used. The individual contractor(s) should
be made responsible for designing and constructing stable, temporary excavations as required to
maintain stability of both the excavation sides and bottom. All excavations should be sloped or
shored in the interest of safety following local, and federal regulations, including current OSHA
excavation and trench safety standards.
As a safety measure, it is recommended that all vehicles and soil piles be kept a minimum lateral
distance from the crest of the slope equal to the slope height. The exposed slope face should be
protected against the elements
4.2.3 Subgrade Preparation
After the recommended depth of over-excavation and any deleterious materials have been
removed from the construction area, the top 8 inches of the exposed ground surface should be
scarified, moisture conditioned, and recompacted to at least 95 percent of the maximum dry unit
weight as determined by ASTM D698 before any new fill, foundation, or pavement is placed.
If pockets of soft, loose, or otherwise unsuitable materials are encountered at the bottom of the
foundation excavations and it is inconvenient to lower the foundations, the proposed foundation
elevations may be reestablished by over-excavating the unsuitable soils and backfilling with
compacted engineered fill or lean concrete.
After the bottom of the excavation has been compacted, engineered fill can be placed to bring
the building pad and pavement subgrade to the desired grade. Engineered fill should be placed
in accordance with the recommendations presented in subsequent sections of this report.
The stability of the subgrade may be affected by precipitation, repetitive construction traffic or
other factors. If unstable conditions develop, workability may be improved by scarifying and
drying. Alternatively, over-excavation of wet zones and replacement with granular materials
may be used, or crushed gravel and/or rock can be tracked or “crowded” into the unstable
surface soil until a stable working surface is attained. Use of lime, fly ash, or geotextiles could
also be considered as a stabilization technique. Laboratory evaluation is recommended to
determine the effect of chemical stabilization on subgrade soils prior to construction.
Lightweight excavation equipment may also be used to reduce subgrade pumping.
4.2.4 Fill Materials and Placement
The on-site soils or approved granular and low plasticity cohesive imported materials may be used
as fill material. The soil removed from this site that is free of organic or objectionable materials,
as defined by a Terracon representative who is qualified in soil material identification and
compaction procedures, can be re-used as fill for the building pad and pavement subgrade. It
should be noted that on-site soils will require reworking to adjust the moisture content to meet
the compaction criteria. Where bedrock is excavated from the site and used as fill, we
recommend the bedrock be thoroughly processed and broken down prior to placement as fill.
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Imported soils (if required) should meet the following material property requirements:
Gradation Percent finer by weight (ASTM C136)
4” 100
3” 70-100
No. 4 Sieve 50-100
No. 200 Sieve 10-50
Soil Properties Value
Liquid Limit 30 (max.)
Plastic Limit 15 (max.)
Maximum Expansive Potential (%) Non-expansive1
1. Measured on a sample compacted to approximately 95 percent of the maximum dry unit weight as
determined by ASTM D698 at optimum moisture content. The sample is confined under a 100 psf
surcharge and submerged.
4.2.5 Compaction Requirements
Engineered fill should be placed and compacted in horizontal lifts, using equipment and
procedures that will produce recommended moisture contents and densities throughout the lift.
Item Description
Fill lift thickness
9 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 or plate compactor) is used
Minimum compaction requirements
95 percent of the maximum dry unit weight as determined
by ASTM D698
Moisture content cohesive soil (clay) -1 to +3 % of the optimum moisture content
Moisture content cohesionless soil
(sand)
-3 to +2 % of the optimum moisture content
1. We recommend engineered fill be tested for moisture content and compaction during placement.
Should the results of the in-place density tests indicate the specified moisture or compaction limits
have not been met, the area represented by the test should be reworked and retested as required
until the specified moisture and compaction requirements are achieved.
2. Specifically, moisture levels should be maintained low enough to allow for satisfactory compaction
to be achieved without the fill material pumping when proofrolled.
3. Moisture conditioned clay materials should not be allowed to dry out. A loss of moisture within
these materials could result in an increase in the material’s expansive potential. Subsequent
wetting of these materials could result in undesirable movement.
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St. Peter's Anglican Church ■ Fort Collins, Colorado
November 6, 2015 ■ Terracon Project No. 20155045
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4.2.6 Utility Trench Backfill
All trench excavations should be made with sufficient working space to permit construction
including backfill placement and compaction.
All underground piping within or near the proposed structure should be designed with flexible
couplings, so minor deviations in alignment do not result in breakage or distress. Utility knockouts
in foundation walls should be oversized to accommodate differential movements. It is imperative
that utility trenches be properly backfilled with relatively clean materials. If utility trenches are
backfilled with relatively clean granular material, they should be capped with at least 18 inches of
cohesive fill in non-pavement areas to reduce the infiltration and conveyance of surface water
through the trench backfill.
Utility trenches are a common source of water infiltration and migration. All utility trenches that
penetrate beneath the structure should be effectively sealed to restrict water intrusion and flow
through the trenches that could migrate below the structure. We recommend constructing an
effective clay “trench plug” that extends at least 5 feet out from the face of the building exteriors.
The plug material should consist of clay compacted at a water content at or above the soil’s
optimum water content. The clay fill should be placed to completely surround the utility line and be
compacted in accordance with recommendations in this report.
It is strongly recommended that a representative of Terracon provide full-time observation and
compaction testing of trench backfill within building and pavement areas.
4.2.7 Grading and Drainage
All grades must be adjusted to provide effective drainage away from the proposed structure
during construction and maintained throughout the life of the proposed project. Infiltration of
water into foundation excavations must be prevented during construction. Landscape irrigation
adjacent to foundations should be minimized or eliminated. Water permitted to pond near or
adjacent to the perimeter of the structure (either during or post-construction) can result in
significantly higher soil movements than those discussed in this report. As a result, any
estimations of potential movement described in this report cannot be relied upon if positive
drainage is not obtained and maintained, and water is allowed to infiltrate the fill and/or
subgrade.
Exposed ground (if any) should be sloped at a minimum of 10 percent grade for at least 10 feet
beyond the perimeter of the proposed structure, where possible. The use of swales, chases
and/or area drains may be required to facilitate drainage in unpaved areas around the perimeter
of the structure. Backfill against foundations and exterior walls should be properly compacted
and free of all construction debris to reduce the possibility of moisture infiltration. After
construction of the proposed structure, and prior to project completion, we recommend
verification of final grading be performed to document positive drainage, as described above,
has been achieved.
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St. Peter's Anglican Church ■ Fort Collins, Colorado
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Flatwork and pavements will be subject to post-construction movement. Maximum grades
practical should be used for paving and flatwork to prevent areas where water can pond. In
addition, allowances in final grades should take into consideration post-construction movement
of flatwork, particularly if such movement would be critical. Where paving or flatwork abuts the
structure, care should be taken that joints are properly sealed and maintained to prevent the
infiltration of surface water.
Planters located adjacent to the structure should preferably be self-contained. Sprinkler mains
and spray heads should be located a minimum of 5 feet away from the building line(s). Low-
volume, drip style landscaped irrigation should not be used near the building. Roof drains
should discharge on to pavements or be extended away from the structure a minimum of 10 feet
through the use of splash blocks or downspout extensions. A preferred alternative is to have
the roof drains discharge by solid pipe to storm sewers or to a detention pond or other
appropriate outfall.
4.2.8 Exterior Slab Design and Construction
Exterior slabs on-grade, exterior architectural features, and utilities founded on, or in backfill or
the site soils will likely experience some movement due to the volume change of the material.
Potential movement could be reduced by:
Minimizing moisture increases in the backfill;
Controlling moisture-density during placement of the backfill;
Using designs which allow vertical movement between the exterior features
and adjoining structural elements; and
Placing control joints on relatively close centers.
4.3 Foundations
The proposed church may be supported on shallow spread footing foundations bearing on a
minimum of 4 feet of over-excavated properly prepared on-site soils and/or bedrock or on newly
placed engineered fill. We recommend the footing foundations be designed to maintain a
minimum dead load pressure of 500 psf.
Design recommendations for foundations for the proposed structures and related structural
elements are presented in the following sections.
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4.3.1 Spread Footings - Design Recommendations
Description Value
Maximum allowable bearing pressure 1 2,500 psf
Lateral earth pressure coefficients 2
Lean clay:
Active, Ka = 0.41
Passive, Kp = 2.46
At-rest, Ko = 0.58
Granular soil:
Active, Ka = 0.27
Passive, Kp = 3.69
At-rest, Ko = 0.43
Sliding coefficient 2
Lean clay:
µ = 0.37
Granular soil:
µ = 0.56
Moist soil unit weight
Lean clay:
ɣ = 120 pcf
Granular soil:
ɣ = 130 pcf
Minimum embedment depth below finished
grade 3
30 inches
Estimated total movement 4 About 1 inch
Estimated differential movement 4 About ½ to ¾ of total movement
1. The recommended maximum allowable bearing pressure assumes any unsuitable fill or soft soils,
if encountered, will be over-excavated and replaced with properly compacted engineered fill.
The design bearing pressure applies to a dead load plus design live load condition. The design
bearing pressure may be increased by one-third when considering total loads that include wind or
seismic conditions.
2. The lateral earth pressure coefficients and sliding coefficients are ultimate values and do not
include a factor of safety. The foundation designer should include the appropriate factors of
safety.
3. For frost protection and to reduce the effects of seasonal moisture variations in the subgrade
soils. The minimum embedment depth is for perimeter footings beneath unheated areas and is
relative to lowest adjacent finished grade, typically exterior grade.
4. The estimated movements presented above are based on the assumption that the maximum
footing size is 9 feet for column footings and 4 feet for continuous footings.
Footings should be proportioned to reduce differential foundation movement. As discussed,
total movement resulting from the assumed structural loads is estimated to be on the order of
about 1 inch. Additional foundation movements could occur if water from any source infiltrates
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the foundation soils; therefore, proper drainage should be provided in the final design and
during construction and throughout the life of the structure. Failure to maintain the proper
drainage as recommended in the 4.2.7 Grading and Drainage section of this report will nullify
the movement estimates provided above.
4.3.2 Spread Footings - Construction Considerations
Spread footing construction should only be considered if the estimated foundation movement
can be tolerated. Subgrade soils beneath footings should be moisture conditioned and
compacted as described in the 4.2 Earthwork section of this report. The moisture content and
compaction of subgrade soils should be maintained until foundation construction.
Footings and foundation walls should be reinforced as necessary to reduce the potential for
distress caused by differential foundation movement.
Unstable surfaces will need to be stabilized prior to backfilling excavations and/or constructing
the building foundation, floor slab and/or project pavements. The use of angular rock, recycled
concrete and/or gravel pushed or “crowded” into the yielding subgrade is considered suitable
means of stabilizing the subgrade. The use of geogrid materials in conjunction with gravel could
also be considered and could be more cost effective.
Unstable subgrade conditions should be observed by Terracon to assess the subgrade and
provide suitable alternatives for stabilization. Stabilized areas should be proof-rolled prior to
continuing construction to assess the stability of the subgrade.
Foundation excavations should be observed by Terracon. If the soil conditions encountered
differ significantly from those presented in this report, supplemental recommendations will be
required.
4.4 Seismic Considerations
Code Used Site Classification
2012 International Building Code (IBC) 1 C 2
1. In general accordance with the 2012 International Building Code, Table 1613.5.2.
2. The 2012 International Building Code (IBC) requires a site soil profile determination extending a
depth of 100 feet for seismic site classification. The current scope requested does not include the
required 100 foot soil profile determination. The borings completed for this project extended to a
maximum depth of about 30 feet and this seismic site class definition considers that similar soil and
bedrock conditions exist below the maximum depth of the subsurface exploration. Additional
exploration to deeper depths could be performed to confirm the conditions below the current depth of
exploration. Alternatively, a geophysical exploration could be utilized in order to attempt to justify a
more favorable seismic site class. However, we believe a higher seismic site class for this site is
unlikely.
Geotechnical Engineering Report
St. Peter's Anglican Church ■ Fort Collins, Colorado
November 6, 2015 ■ Terracon Project No. 20155045
Responsive ■ Resourceful ■ Reliable 13
4.5 Floor Systems
A slab-on-grade floor system is recommended for the proposed building provided the subgrade
soils and/or bedrock are over-excavated a minimum of 2 feet, scarified, moisture conditioned, and
recompacted as presented is the 4.2 Earthwork section of this report. If the estimated movement
cannot be tolerated, a structurally-supported floor system, supported independent of the
subgrade materials, is recommended.
Subgrade soils beneath interior and exterior slabs and at the base of the over-excavation for
should be scarified to a depth of at least 8 inches, moisture conditioned and compacted. The
moisture content and compaction of subgrade soils should be maintained until slab construction.
4.5.1 Floor System - Design Recommendations
Even when bearing on properly prepared soils, movement of the slab-on-grade floor system is
possible should the subgrade soils undergo an increase in moisture content. We estimate
movement of about 1 inch is possible.
For structural design of concrete slabs-on-grade subjected to point loadings, a modulus of
subgrade reaction of 100 pounds per cubic inch (pci) may be used for floors supported on re-
compacted existing soils at the site. A modulus of 200 pci may be used for floors supported on
at least 1 foot of non-expansive, imported granular fill.
Additional floor slab design and construction recommendations are as follows:
Positive separations and/or isolation joints should be provided between slabs and all
foundations, columns, or utility lines to allow independent movement.
Control joints should be saw-cut in slabs in accordance with ACI Design Manual,
Section 302.1R-37 8.3.12 (tooled control joints are not recommended) to control the
location and extent of cracking.
Interior utility trench backfill placed beneath slabs should be compacted in accordance
with the recommendations presented in the 4.2 Earthwork section of this report.
Floor slabs should not be constructed on frozen subgrade.
A minimum 1½-inch void space should be constructed below non-bearing partition
walls placed on the floor slab. Special framing details should be provided at
doorjambs and frames within partition walls to avoid potential distortion. Partition walls
should be isolated from suspended ceilings.
The use of a vapor retarder should be considered beneath concrete slabs that will be
covered with wood, tile, carpet or other moisture sensitive or impervious floor
Geotechnical Engineering Report
St. Peter's Anglican Church ■ Fort Collins, Colorado
November 6, 2015 ■ Terracon Project No. 20155045
Responsive ■ Resourceful ■ Reliable 14
coverings, or when the slab will support equipment sensitive to moisture. When
conditions warrant the use of a vapor retarder, the slab designer and slab contractor
should refer to ACI 302 for procedures and cautions regarding the use and placement
of a vapor retarder.
Other design and construction considerations, as outlined in the ACI Design Manual,
Section 302.1R are recommended.
4.5.2 Floor Systems - 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 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.
4.6 Pavements
4.6.1 Pavements – Subgrade Preparation
On most project sites, the site grading is accomplished relatively early in the construction phase.
Fills are typically placed and compacted in a uniform manner. However as construction
proceeds, the subgrade may be disturbed due to utility excavations, construction traffic,
desiccation, or rainfall/snow melt. As a result, the pavement subgrade may not be suitable for
pavement construction and corrective action will be required. The subgrade should be carefully
evaluated at the time of pavement construction for signs of disturbance or instability. We
recommend the pavement subgrade be thoroughly proofrolled with a loaded tandem-axle dump
truck prior to final grading and paving. All pavement areas should be moisture conditioned and
properly compacted to the recommendations in this report immediately prior to paving.
4.6.2 Pavements – Design Recommendations
Design of new privately-maintained pavements for the project has been based on the
procedures described by the National Asphalt Pavement Associations (NAPA) and the
American Concrete Institute (ACI).
A sample of the fill materials selected for swell-consolidation testing swelled approximately 2.1
percent when wetted. Therefore, we believe swell-mitigation of the subgrade materials prior to
pavement operations should be required. Swell mitigation below pavements should consist of
scarification to a minimum depth of 1 foot below the aggregate base course elevation, moisture
conditioning, and recompacting as presented in the 4.2 Earthwork section of this report. Where
bedrock is exposed as subgrade below proposed pavement materials, we recommend over-
excavating the bedrock to a depth of at least 12 inches and replacing as properly moisture
Geotechnical Engineering Report
St. Peter's Anglican Church ■ Fort Collins, Colorado
November 6, 2015 ■ Terracon Project No. 20155045
Responsive ■ Resourceful ■ Reliable 15
conditioned, compacted fill prior to construction of pavement. The subgrade at the base of the
over-excavation below pavements should be prepared as described in the 4.2 Earthwork section
of this report.
We assumed the following design parameters for NAPA flexible pavement thickness design:
Automobile Parking Areas
Class I - Parking stalls and parking lots for cars and pick-up trucks, with
Equivalent Single Axle Load (ESAL) up to 7,000 over 20 years
Main Traffic Corridors
Class II – Parking lots with a maximum of 10 trucks per day with Equivalent
Single Axle Load (ESAL) up to 27,000 over 20 years (Including trash trucks)
Subgrade Soil Characteristics
USCS Classification – CL, classified by NAPA as poor
We assumed the following design parameters for ACI rigid pavement thickness design based
upon the average daily truck traffic (ADTT):
Automobile Parking Areas
ACI Category A: Automobile parking with an ADTT of 1 over 20 years
Main Traffic Corridors
ACI Category A: Automobile parking area and service lanes with an ADTT of
up to 10 over 20 years
Subgrade Soil Characteristics
USCS Classification – CL
Concrete modulus of rupture value of 600 psi
We should be contacted to confirm and/or modify the recommendations contained herein if
actual traffic volumes differ from the assumed values shown above.
Recommended alternatives for flexible and rigid pavements are summarized for each traffic
area as follows:
Geotechnical Engineering Report
St. Peter's Anglican Church ■ Fort Collins, Colorado
November 6, 2015 ■ Terracon Project No. 20155045
Responsive ■ Resourceful ■ Reliable 16
Traffic Area
Alternative
Recommended Pavement Thickness (Inches)
Asphaltic
Concrete
Surface
Aggregate
Base
Course
Portland
Cement
Concrete
Total
Automobile Parking
(NAPA Class I and ACI Category A)
A 3 6 -- 9
B -- -- 5½ 5½
Service Lanes
(NAPA Class II and ACI Category A)
A 4½ 6 -- 10½
B -- -- 6 6
Aggregate base course (if used on the site) should consist of a blend of sand and gravel which
meets strict specifications for quality and gradation. Use of materials meeting Colorado
Department of Transportation (CDOT) Class 5 or 6 specifications is recommended for
aggregate base course. Aggregate base course should be placed in lifts not exceeding 6
inches and compacted to a minimum of 95 percent of the maximum dry unit weight as
determined by ASTM D698.
Asphaltic 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 Superpave properties, optimum asphalt content, job mix formula and
recommended mixing and placing temperatures. Aggregate used in asphalt concrete should
meet particular gradations. Material meeting CDOT Grading S specifications or equivalent is
recommended for asphalt concrete. Mix designs should be submitted prior to construction to
verify their adequacy. Asphalt material should be placed in maximum 3-inch lifts and
compacted within a range of 92 to 96 percent of the theoretical maximum (Rice) density (ASTM
D2041).
Where rigid pavements are used, the concrete should be produced from an approved mix
design with the following minimum properties:
Properties Value
Compressive strength 4,000 psi
Cement type Type I or II portland cement
Entrained air content (%) 5 to 8
Concrete aggregate ASTM C33 and CDOT Section 703
Concrete should be deposited by truck mixers or agitators and placed a maximum of 90 minutes
from the time the water is added to the mix. Longitudinal and transverse joints should be
provided as needed in concrete pavements for expansion/contraction and isolation per ACI 325.
The location and extent of joints should be based upon the final pavement geometry.
Geotechnical Engineering Report
St. Peter's Anglican Church ■ Fort Collins, Colorado
November 6, 2015 ■ Terracon Project No. 20155045
Responsive ■ Resourceful ■ Reliable 17
Although not required for structural support, a minimum 4-inch thick aggregate base course
layer is recommended for the PCC pavements to help reduce the potential for slab curl,
shrinkage cracking, and subgrade “pumping” through joints. Proper joint spacing will also be
required for PCC pavements to prevent excessive slab curling and shrinkage cracking. All joints
should be sealed to prevent entry of foreign material and dowelled where necessary for load
transfer.
For areas subject to concentrated and repetitive loading conditions (if any) such as dumpster
pads, truck delivery docks and ingress/egress aprons, we recommend using a portland cement
concrete pavement with a thickness of at least 6 inches underlain by at least 4 inches of
granular base. Prior to placement of the granular base, the areas should be thoroughly
proofrolled. For dumpster pads, the concrete pavement area should be large enough to support
the container and tipping axle of the refuse truck.
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:
Site grades should slope a minimum of 2 percent away from the pavements;
The subgrade and the pavement surface have a minimum 2 percent slope to promote proper
surface drainage;
Consider appropriate edge drainage and pavement under drain systems;
Install pavement drainage 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; and
Placing compacted, low permeability backfill against the exterior side of curb and gutter.
4.6.3 Pavements – Construction Considerations
Openings in pavement, such as landscape islands, are sources for water infiltration into
surrounding pavements. Water collects in the islands and migrates into the surrounding
subgrade soils thereby degrading support of the pavement. This is especially applicable for
islands with raised concrete curbs, irrigated foliage, and low permeability near-surface soils. The
civil design for the pavements with these conditions should include features to restrict or to
collect and discharge excess water from the islands. Examples of features are edge drains
connected to the storm water collection system or other suitable outlet and impermeable
barriers preventing lateral migration of water such as a cutoff wall installed to a depth below the
pavement structure.
4.6.4 Pavements – Maintenance
Preventative maintenance should be planned and provided for an ongoing pavement
management program in order to enhance future pavement performance. Preventive
maintenance consists of both localized maintenance (e.g. crack and joint sealing and patching)
Geotechnical Engineering Report
St. Peter's Anglican Church ■ Fort Collins, Colorado
November 6, 2015 ■ Terracon Project No. 20155045
Responsive ■ Resourceful ■ Reliable 18
and global maintenance (e.g. surface sealing). Preventative maintenance is usually the first
priority when implementing a planned pavement maintenance program and provides the highest
return on investment for pavements.
5.0 GENERAL COMMENTS
Terracon should be retained to review the final design plans and specifications so comments
can be made regarding interpretation and implementation of our geotechnical recommendations
in the design and specifications. Terracon also should be retained to provide observation and
testing services during grading, excavation, foundation construction and other earth-related
construction phases of the project.
The analysis and recommendations presented in this report are based upon the data obtained
from the borings performed at the indicated locations and from other information discussed in
this report. This report does not reflect variations that may occur between borings, 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. If variations appear, we
should be immediately notified so that further evaluation and supplemental recommendations
can be provided.
The scope of services for this project does not include either specifically or by implication any
environmental or biological (e.g., mold, fungi, and 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.
This report has been prepared for the exclusive use of our client for specific application to the
project discussed and has been prepared in accordance with generally accepted geotechnical
engineering practices. No warranties, either express or implied, are intended or made. Site
safety, excavation support, and dewatering requirements are the responsibility of others. In the
event that changes in the nature, design, or location of the project as described in this report are
planned, the conclusions and recommendations contained in this report shall not be considered
valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this
report in writing.
APPENDIX A
FIELD EXPLORATION
SITE LOCATION MAP
St. Peter's Anglican Church
6608 Autumn Ridge Road
Fort Collins, CO
TOPOGRAPHIC MAP IMAGE COURTESY OF THE U.S. GEOLOGICAL SURVEY
QUADRANGLES INCLUDE: FORT COLLINS, CO (1/1/1984) and LOVELAND, CO (1/1/1984).
1901 Sharp Point Dr Suite C
Ft. Collins, CO 80525
20155045
Project Manager:
Drawn by:
Checked by:
Approved by:
BCR
EDB
EDB
1”=24,000 SF
11/5/2015
Project No.
Scale:
File Name:
Date: A-1
EDB Exhibit
A-2
20155045
11/6/2015
EDB
BCR
EDB
EDB
1” = 100’
Project Manager:
Drawn by:
Checked by:
Approved by:
Project No.
Scale:
File Name:
Date:
Exhibit
DIAGRAM IS FOR GENERAL LOCATION
ONLY, AND IS NOT INTENDED FOR
CONSTRUCTION PURPOSES
0’ 50’ 100’
APPROXIMATE SCALE
Approximate Boring Location
1
Approximate Location of
Temporary Benchmark (Top
Nut of Fire Hydrant– Assumed
Elevation 100.0’)
LEGEND
1901 Sharp Point Dr Suite C
Ft. Collins, CO
EXPLORATION PLAN
St. Peter’s Anglican Church
6608 Autumn Ridge Road
Fort Collins, CO
1
2
3
4
5
P-1
P-2
P-3
P-4
Geotechnical Engineering Report
St. Peter's Anglican Church ■ Fort Collins, Colorado
November 6, 2015 ■ Terracon Project No. 20155045
Responsive ■ Resourceful ■ Reliable Exhibit A-3
Field Exploration Description
The locations of borings were based upon the proposed development. The borings were
located in the field using a hand-held GPS device accurate to within 15 feet. The ground
surface elevation was surveyed at each boring location using an engineer’s level referencing the
temporary benchmark shown on Exhibit A-2.
The borings were drilled with a CME-55 truck-mounted rotary drill rig with solid-stem augers.
During the drilling operations, lithologic logs of the borings were recorded by the field engineer.
Disturbed samples were obtained at selected intervals utilizing a 2-inch outside diameter split-
spoon sampler and a 3-inch outside diameter ring-barrel sampler. Penetration resistance
values were recorded in a manner similar to the standard penetration test (SPT). This test
consists of driving the sampler into the ground with a 140-pound hammer free-falling through a
distance of 30 inches. The number of blows required to advance the ring-barrel sampler 12
inches (18 inches for standard split-spoon samplers, final 12 inches are recorded) or the interval
indicated, is recorded as a standard penetration resistance value (N-value). The blow count
values are indicated on the boring logs at the respective sample depths. Ring-barrel sample
blow counts are not considered N-values.
A CME automatic SPT hammer was used to advance the samplers in the borings performed on
this site. A greater efficiency is typically achieved with the automatic hammer compared to the
conventional safety hammer operated with a cathead and rope. Published correlations between
the SPT values and soil properties are based on the lower efficiency cathead and rope method.
This higher efficiency affects the standard penetration resistance blow count value by increasing
the penetration per hammer blow over what would be obtained using the cathead and rope
method. The effect of the automatic hammer's efficiency has been considered in the interpretation
and analysis of the subsurface information for this report.
The standard penetration test provides a reasonable indication of the in-place density of sandy
type materials, but only provides an indication of the relative stiffness of cohesive materials
since the blow count in these soils may be affected by the moisture content of the soil. In
addition, considerable care should be exercised in interpreting the N-values in gravelly soils,
particularly where the size of the gravel particle exceeds the inside diameter of the sampler.
Groundwater measurements were obtained in the borings at the time of site exploration and
several days after drilling. After subsequent groundwater measurements were obtained, the
borings were backfilled with auger cuttings and sand (if needed). Some settlement of the
backfill may occur and should be repaired as soon as possible.
12 82
13
15
13
14
14
116
110
37-22-15
94.5
86
76
70.5
15-28
11-19-27
N=46
21-50/5"
18-27-50/5"
20-41-50/4"
33-50/3"
0.5
9.0
19.0
24.7
VEGETATIVE LAYER - 6 inches
LEAN CLAY WITH SAND (CL), light brown, very stiff
SEDIMENTARY BEDROCK - SANDSTONE, light brown to gray, hard
SEDIMENTARY BEDROCK - CLAYSTONE, gray, very hard
Boring Terminated at 24.7 Feet
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
GRAPHIC LOG
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20155045.GPJ TERRACON2015.GDT 11/6/15
6608 Autmn Ridge Road
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4-inch solid stem auger
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20155045
Drill Rig: CME-55
Boring Started: 9/28/2015
BORING LOG NO. 1
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
Driller: Drilling Engineers, Inc.
Boring Completed: 9/28/2015
Exhibit: A-4
See Exhibit A-3 for description of field procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: St. Peter's Anglican Church
PERCENT FINES
WATER
89
13
16
14
14
13
13
116 43-19-24
99
94.5
74.5
8-18-24
N=42
18-28
18-50/6"
26-50/6"
22-50/6"
21-50/6"
0.5
5.0
25.0
VEGETATIVE LAYER - 6 inches
LEAN CLAY (CL), light brown, stiff
SEDIMENTARY BEDROCK - SANDSTONE, light brown to gray, very
hard
Boring Terminated at 25 Feet
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
GRAPHIC LOG
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20155045.GPJ TERRACON2015.GDT 11/6/15
6608 Autmn Ridge Road
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4-inch solid stem auger
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20155045
Drill Rig: CME-55
Boring Started: 9/28/2015
BORING LOG NO. 2
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
Driller: Drilling Engineers, Inc.
Boring Completed: 9/28/2015
Exhibit: A-5
See Exhibit A-3 for description of field procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: St. Peter's Anglican Church
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
88
8
14
14
14
12
12
105
113 42-17-25
99.5
98
80
75.5
12-21
13-27
12-25-37
N=62
17-30-44
N=74
19-50/6"
34-50/4"
0.5
2.0
20.0
24.8
VEGETATIVE LAYER - 6 inches
LEAN CLAY WITH SAND, light brown, stiff to very stiff
SEDIMENTARY BEDROCK - CLAYSTONE (CL), light brown, firm to
very hard
SEDIMENTARY BEDROCK - CLAYSTONE, gray to light brown, very
hard
Boring Terminated at 24.8 Feet
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
GRAPHIC LOG
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20155045.GPJ TERRACON2015.GDT 11/6/15
6608 Autmn Ridge Road
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4-inch solid stem auger
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20155045
Drill Rig: CME-55
Boring Started: 9/28/2015
BORING LOG NO. 3
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
Driller: Drilling Engineers, Inc.
Boring Completed: 9/28/2015
Exhibit: A-6
See Exhibit A-3 for description of field procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
78
7
15
14
12
12
12
12
120
118 39-19-20
100.5
98
88
71.5
12-25
15-24-40
N=64
31-50/4"
23-50/6"
24-50/5"
50-6"
50/6"
0.5
3.0
13.0
29.5
VEGETATIVE LAYER - 6 inches
LEAN CLAY WITH SAND, light brown, stiff
SEDIMENTARY BEDROCK - CLAYSTONE (CL), light brown to gray,
very hard
SEDIMENTARY BEDROCK - CLAYSTONE, gray to orange-brown, very
hard
Boring Terminated at 29.5 Feet
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
GRAPHIC LOG
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20155045.GPJ TERRACON2015.GDT 11/6/15
6608 Autmn Ridge Road
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4-inch solid stem auger
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20155045
Drill Rig: CME-55
Boring Started: 9/28/2015
BORING LOG NO. 4
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
Driller: Drilling Engineers, Inc.
Boring Completed: 9/28/2015
Exhibit: A-7
See Exhibit A-3 for description of field procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
69
59
8
8
12
11
11
13
108
69-15-54
32-17-15
99.5
85.5
75
11-19
6-9-13
N=22
6-9-12
N=21
9-17-20
N=37
50/6"
29-50/3"
0.5
14.5
24.7
VEGETATIVE LAYER - 6 inches
SANDY FAT CLAY (CH), light brown, medium stiff to stiff
SEDIMENTARY BEDROCK - SANDSTONE, light brown, very hard
Boring Terminated at 24.7 Feet
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
GRAPHIC LOG
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20155045.GPJ TERRACON2015.GDT 11/6/15
6608 Autmn Ridge Road
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4-inch solid stem auger
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20155045
Drill Rig: CME-55
Boring Started: 9/28/2015
BORING LOG NO. 5
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
Driller: Drilling Engineers, Inc.
Boring Completed: 9/28/2015
Exhibit: A-8
See Exhibit A-3 for description of field procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: St. Peter's Anglican Church
PERCENT FINES
12 74
12
112 NP
99.5
97.5
95
18-50/5"
17-50/6"
0.5
2.5
5.0
VEGETATIVE LAYER - 6 inches
SILT WITH SAND (ML), light brown, very stiff
SEDIMENTARY BEDROCK - SANDSTONE, light brown, very hard
Boring Terminated at 5 Feet
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
GRAPHIC LOG
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20155045.GPJ TERRACON2015.GDT 11/6/15
6608 Autmn Ridge Road
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4-inch solid stem auger
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20155045
Drill Rig: CME-55
Boring Started: 9/28/2015
BORING LOG NO. P1
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
Driller: Drilling Engineers, Inc.
Boring Completed: 9/28/2015
Exhibit: A-9
See Exhibit A-3 for description of field procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: St. Peter's Anglican Church
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 99.8 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
FIELD TEST
12
8 128
101.5
100
97
12-24-50/5"
21-50/5"
0.5
2.0
5.0
VEGETATIVE LAYER - 6 inches
LEAN CLAY WITH SAND, light brown, very stiff
SEDIMENTARY BEDROCK - SANDSTONE, light brown to gray, very
hard
Boring Terminated at 5 Feet
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
GRAPHIC LOG
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20155045.GPJ TERRACON2015.GDT 11/6/15
6608 Autmn Ridge Road
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4-inch solid stem auger
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20155045
Drill Rig: CME-55
Boring Started: 9/28/2015
BORING LOG NO. P2
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
Driller: Drilling Engineers, Inc.
Boring Completed: 9/28/2015
Exhibit: A-10
See Exhibit A-3 for description of field procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: St. Peter's Anglican Church
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 102.1 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
FIELD TEST
12 79
13
119 36-17-19
102.5
100.5
98
15-50/5"
21-50/5"
0.5
2.5
5.0
VEGETATIVE LAYER - 6 inches
LEAN CLAY WITH SAND (CL), light brown, very stiff
SEDIMENTARY BEDROCK - SANDSTONE, light brown to gray, very
hard
Boring Terminated at 5 Feet
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
GRAPHIC LOG
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20155045.GPJ TERRACON2015.GDT 11/6/15
6608 Autmn Ridge Road
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4-inch solid stem auger
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20155045
Drill Rig: CME-55
Boring Started: 9/28/2015
BORING LOG NO. P3
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
Driller: Drilling Engineers, Inc.
Boring Completed: 9/28/2015
Exhibit: A-11
See Exhibit A-3 for description of field procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: St. Peter's Anglican Church
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 103.2 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
14 71
10 109
35-23-12
101
98
97
12-50/6"
50/6"
0.5
3.5
4.5
VEGETATIVE LAYER - 6 inches
LEAN CLAY WITH SAND (CL), light brown, very stiff
SEDIMENTARY BEDROCK - CLAYSTONE, gray to light brown, very
hard
Boring Terminated at 4.5 Feet
Stratification lines are approximate. In-situ, the transition may be gradual. Hammer Type: Automatic
GRAPHIC LOG
THIS BORING LOG IS NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GEO SMART LOG-NO WELL 20155045.GPJ TERRACON2015.GDT 11/6/15
6608 Autmn Ridge Road
Fort Collins, Colorado
SITE:
Page 1 of 1
Advancement Method:
4-inch solid stem auger
Abandonment Method:
Borings backfilled with soil cuttings upon completion.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
Notes:
Project No.: 20155045
Drill Rig: CME-55
Boring Started: 9/28/2015
BORING LOG NO. P4
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
Driller: Drilling Engineers, Inc.
Boring Completed: 9/28/2015
Exhibit: A-12
See Exhibit A-3 for description of field procedures.
See Appendix B for description of laboratory
procedures and additional data (if any).
See Appendix C for explanation of symbols and
abbreviations.
PROJECT: St. Peter's Anglican Church
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 101.6 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
FIELD TEST
APPENDIX B
LABORATORY TESTING
Geotechnical Engineering Report
St. Peter's Anglican Church ■ Fort Collins, Colorado
November 6, 2015 ■ Terracon Project No. 20155045
Responsive ■ Resourceful ■ Reliable Exhibit B-1
Laboratory Testing Description
The soil and bedrock samples retrieved during the field exploration were returned to the
laboratory for observation by the project geotechnical engineer. At that time, the field
descriptions were reviewed and an applicable laboratory testing program was formulated to
determine engineering properties of the subsurface materials.
Laboratory tests were conducted on selected soil and bedrock samples. The results of these
tests are presented on the boring logs and in this appendix. The test results were used for the
geotechnical engineering analyses, and the development of foundation and earthwork
recommendations. The laboratory tests were performed in general accordance with applicable
locally accepted standards. Soil samples were classified in general accordance with the Unified
Soil Classification System described in Appendix C. Rock samples were visually classified in
general accordance with the description of rock properties presented in Appendix C. Procedural
standards noted in this report are for reference to methodology in general. In some cases
variations to methods are applied as a result of local practice or professional judgment.
Water content Plasticity index
Grain-size distribution
Consolidation/swell
Dry density
Water-soluble sulfate content
v
0 v
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
LEAN CLAY with SAND
LEAN CLAY
LEAN CLAY
LEAN CLAY with SAND
SANDY FAT CLAY
SANDY LEAN CLAY
SILT with SAND
LEAN CLAY with SAND
LEAN CLAY with SAND
CL
CL
CL
CL
CH
CL
ML
CL
CL
"U" Line
"A" Line
37
43
42
39
69
32
35
36
35
22
19
17
19
15
17
57
17
23
15
24
25
20
54
15
NP
19
12
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
82.4
88.7
87.8
78.2
69.5
%Fines
LL PL PI
1 4
3/4 1/2
60
fine
1
2
3
4
5
GRAIN SIZE IN MILLIMETERS
PERCENT FINER BY WEIGHT
coarse fine
U.HYDROMETERS. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
22
19
17
19
15
15
24
25
20
54
D100
Cc Cu
SILT OR CLAY
4
D30 D10 %Gravel %Sand
1
2
3
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
59.1
74.1
79.5
71.1
%Fines
LL PL PI
1 4
3/4 1/2
60
fine
5
P1
P3
P4
GRAIN SIZE IN MILLIMETERS
PERCENT FINER BY WEIGHT
coarse fine
U.HYDROMETERS. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
17
57
17
23
15
NP
19
12
D100
Cc Cu
SILT OR CLAY
4
D30 D10 %Gravel %Sand
5
P1
P3
P4
SANDY LEAN CLAY(CL)
SILT with SAND(ML)
LEAN CLAY with SAND(CL)
-4
-3
-2
-1
0
1
2
3
4
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited 1.3 percent swell upon wetting under an applied pressure of 500 psf.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
PROJECT: St. Peter's Anglican PROJECT NUMBER: 20155045
Church
SITE: 6608 Autmn Ridge Road
Fort Collins, Colorado
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
EXHIBIT: B-5
Specimen Identification Classification , pcf
1 116 12
WC, %
2 - 3 ft LEAN CLAY with SAND(CL)
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20155045.GPJ TERRACON2012.GDT 11/5/15
-4
-3
-2
-1
0
1
2
3
4
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited 2.1 percent swell upon wetting under an applied pressure of 500 psf.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
PROJECT: St. Peter's Anglican PROJECT NUMBER: 20155045
Church
SITE: 6608 Autmn Ridge Road
Fort Collins, Colorado
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
EXHIBIT: B-6
Specimen Identification Classification , pcf
2 116 16
WC, %
4 - 5 ft LEAN CLAY(CL)
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20155045.GPJ TERRACON2012.GDT 11/5/15
-4
-3
-2
-1
0
1
2
3
4
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited 1.0 percent swell upon wetting under an applied pressure of 500 psf.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
PROJECT: St. Peter's Anglican PROJECT NUMBER: 20155045
Church
SITE: 6608 Autmn Ridge Road
Fort Collins, Colorado
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
EXHIBIT: B-7
Specimen Identification Classification , pcf
3 113 14
WC, %
4 - 5 ft LEAN CLAY(CL)
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20155045.GPJ TERRACON2012.GDT 11/5/15
-4
-3
-2
-1
0
1
2
3
4
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited 1.6 percent swell upon wetting under an applied pressure of 1000 psf.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
PROJECT: St. Peter's Anglican PROJECT NUMBER: 20155045
Church
SITE: 6608 Autmn Ridge Road
Fort Collins, Colorado
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
EXHIBIT: B-8
Specimen Identification Classification , pcf
4 118 14
WC, %
9 - 9.8 ft LEAN CLAY with SAND(CL)
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20155045.GPJ TERRACON2012.GDT 11/5/15
-4
-3
-2
-1
0
1
2
3
4
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited 1.1 percent swell upon wetting under an applied pressure of 150 psf.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
PROJECT: St. Peter's Anglican PROJECT NUMBER: 20155045
Church
SITE: 6608 Autmn Ridge Road
Fort Collins, Colorado
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
EXHIBIT: B-9
Specimen Identification Classification , pcf
P1 112 12
WC, %
2 - 2.9 ft SILT with SAND(ML)
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20155045.GPJ TERRACON2012.GDT 11/5/15
-4
-3
-2
-1
0
1
2
3
4
100 1,000 10,000
AXIAL STRAIN, %
PRESSURE, psf
SWELL CONSOLIDATION TEST
ASTM D4546
NOTES: Sample exhibited no movement upon wetting under an applied pressure of 150 psf.
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
PROJECT: St. Peter's Anglican PROJECT NUMBER: 20155045
Church
SITE: 6608 Autmn Ridge Road
Fort Collins, Colorado
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
EXHIBIT: B-10
Specimen Identification Classification , pcf
P3 119 12
WC, %
2 - 2.9 ft LEAN CLAY with SAND(CL)
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. TC_CONSOL_STRAIN-USCS 20155045.GPJ TERRACON2012.GDT 11/5/15
TASK NO: 151008041
Analytical Results
Terracon, Inc. - Fort Collins
Eric D. Bernhardt
Company:
Report To:
Company:
Bill To:
1901 Sharp Point Drive
Suite C
Fort Collins CO 80525
Accounts Payable
Terracon, Inc. - Lenexa
13910 W. 96th Terrace
Lenexa KS 66215
20155045
Date Reported: 10/14/15
Task No.: 151008041
Matrix: Soil - Geotech
Date Received: 10/8/15
Client Project:
Client PO:
Customer Sample ID Boring 2 @ 4
Test Method
Lab Number: 151008041-01
Result
Sulfate - Water Soluble 0.097 % AASHTO T290-91/ ASTM D4327
Customer Sample ID Boring 5 @ 4
Test Method
Lab Number: 151008041-02
Result
Sulfate - Water Soluble 0.417 % AASHTO T290-91/ ASTM D4327
Customer2 Sample ID Boring P2 @
Test Method
Lab Number: 151008041-03
Result
Sulfate - Water Soluble 0.058 % AASHTO T290-91/ ASTM D4327
240 South Main Street / Brighton, CO 80601-0507 / 303-659-2313
Mailing Address: P.O. Box 507 / Brighton, CO 80601-0507 / Fax: 303-659-2315
DATA APPROVED FOR RELEASE BY
Abbreviations/ References:
151008041
AASHTO - American Association of State Highway and Transportation Officials.
ASTM - American Society for Testing and Materials.
ASA - American Society of Agronomy.
DIPRA - Ductile Iron Pipe Research Association Handbook of Ductile Iron Pipe.
Exhibit B-11
APPENDIX C
SUPPORTING DOCUMENTS
Exhibit: C-1
Unconfined
Compressive
Strength
Qu, (psf)
500 to 1,000
2,000 to 4,000
> 8,000
less than 500
1,000 to 2,000
4,000 to 8,000
Non-plastic
Low
Medium
High
DESCRIPTION OF SYMBOLS AND ABBREVIATIONS
SAMPLING
WATER LEVEL
FIELD TESTS
GENERAL NOTES
Over 12 in. (300 mm)
12 in. to 3 in. (300mm to 75mm)
3 in. to #4 sieve (75mm to 4.75 mm)
#4 to #200 sieve (4.75mm to 0.075mm
Passing #200 sieve (0.075mm)
Particle Size
< 5
5 - 12
> 12
Percent of
Dry Weight
Descriptive Term(s)
of other constituents
RELATIVE PROPORTIONS OF FINES
0
1 - 10
11 - 30
> 30
Plasticity Index
Soil classification is based on the Unified Soil Classification System. Coarse Grained Soils have more than 50% of their dry
weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand. Fine Grained Soils have
less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and
silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be
added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined
on the basis of their in-place relative density and fine-grained soils on the basis of their consistency.
LOCATION AND ELEVATION NOTES
Percent of
Dry Weight
Major Component
of Sample
Trace
With
Modifier
RELATIVE PROPORTIONS OF SAND AND GRAVEL GRAIN SIZE TERMINOLOGY
Trace
With
Modifier
DESCRIPTIVE SOIL CLASSIFICATION
Boulders
Cobbles
UNIFIED SOIL CLASSIFICATION SYSTEM
Exhibit C-2
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 sand G,H,I
Fines classify as CL or CH SC Clayey sand G,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 clay K,L,M
PI 4 or plots below “A” line J 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 clay K,L,M
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.
DESCRIPTION OF ROCK PROPERTIES
Exhibit C-3
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” not 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
a
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
a. 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) a 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
a. RQD (given as a percentage) = length of core in pieces Greater than 0.1 ft. Wide
4 in. and longer/length of run.
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.
Exhibit C-4
LABORATORY TEST
SIGNIFICANCE AND PURPOSE
Test Significance Purpose
California Bearing
Ratio
Used to evaluate the potential strength of subgrade soil,
subbase, and base course material, including recycled
materials for use in road and airfield pavements.
Pavement Thickness
Design
Consolidation
Used to develop an estimate of both the rate and amount of
both differential and total settlement of a structure.
Foundation Design
Direct Shear
Used to determine the consolidated drained shear strength
of soil or rock.
Bearing Capacity,
Foundation Design,
and Slope Stability
Dry Density
Used to determine the in-place density of natural, inorganic,
fine-grained soils.
Index Property Soil
Behavior
Expansion
Used to measure the expansive potential of fine-grained
soil and to provide a basis for swell potential classification.
Foundation and Slab
Design
Gradation
Used for the quantitative determination of the distribution of
particle sizes in soil.
Soil Classification
Liquid & Plastic Limit,
Plasticity Index
Used as an integral part of engineering classification
systems to characterize the fine-grained fraction of soils,
and to specify the fine-grained fraction of construction
materials.
Soil Classification
Permeability
Used to determine the capacity of soil or rock to conduct a
liquid or gas.
Groundwater Flow
Analysis
pH
Used to determine the degree of acidity or alkalinity of a
soil.
Corrosion Potential
Resistivity
Used to indicate the relative ability of a soil medium to carry
electrical currents.
Corrosion Potential
R-Value
Used to evaluate the potential strength of subgrade soil,
subbase, and base course material, including recycled
materials for use in road and airfield pavements.
Pavement Thickness
Exhibit C-5
REPORT TERMINOLOGY
(Based on ASTM D653)
Allowable Soil
Bearing Capacity
The recommended maximum contact stress developed at the interface of the foundation
element and the supporting material.
Alluvium
Soil, the constituents of which have been transported in suspension by flowing water and
subsequently deposited by sedimentation.
Aggregate Base
Course
A layer of specified material placed on a subgrade or subbase usually beneath slabs or
pavements.
Backfill A specified material placed and compacted in a confined area.
Bedrock
A natural aggregate of mineral grains connected by strong and permanent cohesive forces.
Usually requires drilling, wedging, blasting or other methods of extraordinary force for
excavation.
Bench A horizontal surface in a sloped deposit.
Caisson (Drilled
Pier or Shaft)
A concrete foundation element cast in a circular excavation which may have an enlarged
base. Sometimes referred to as a cast-in-place pier or drilled shaft.
Coefficient of
Friction
A constant proportionality factor relating normal stress and the corresponding shear stress
at which sliding starts between the two surfaces.
Colluvium
Soil, the constituents of which have been deposited chiefly by gravity such as at the foot of a
slope or cliff.
Compaction The densification of a soil by means of mechanical manipulation
Concrete Slab-on-
Grade
A concrete surface layer cast directly upon a base, subbase or subgrade, and typically used
as a floor system.
Differential
Movement
Unequal settlement or heave between, or within foundation elements of structure.
Earth Pressure The pressure exerted by soil on any boundary such as a foundation wall.
ESAL
Equivalent Single Axle Load, a criteria used to convert traffic to a uniform standard, (18,000
pound axle loads).
Engineered Fill
Specified material placed and compacted to specified density and/or moisture conditions
under observations of a representative of a geotechnical engineer.
Equivalent Fluid
A hypothetical fluid having a unit weight such that it will produce a pressure against a lateral
support presumed to be equivalent to that produced by the actual soil. This simplified
approach is valid only when deformation conditions are such that the pressure increases
linearly with depth and the wall friction is neglected.
Existing Fill (or
Man-Made Fill)
Materials deposited throughout the action of man prior to exploration of the site.
Existing Grade The ground surface at the time of field exploration.
Exhibit C-6
REPORT TERMINOLOGY
(Based on ASTM D653)
Expansive Potential The potential of a soil to expand (increase in volume) due to absorption of moisture.
Finished Grade The final grade created as a part of the project.
Footing A portion of the foundation of a structure that transmits loads directly to the soil.
Foundation The lower part of a structure that transmits the loads to the soil or bedrock.
Frost Depth The depth at which the ground becomes frozen during the winter season.
Grade Beam
A foundation element or wall, typically constructed of reinforced concrete, used to span
between other foundation elements such as drilled piers.
Groundwater Subsurface water found in the zone of saturation of soils or within fractures in bedrock.
Heave Upward movement.
Lithologic
The characteristics which describe the composition and texture of soil and rock by
observation.
Native Grade The naturally occurring ground surface.
Native Soil Naturally occurring on-site soil, sometimes referred to as natural soil.
Optimum Moisture
Content
The water content at which a soil can be compacted to a maximum dry unit weight by a given
compactive effort.
Perched Water
Groundwater, usually of limited area maintained above a normal water elevation by the
presence of an intervening relatively impervious continuous stratum.
Scarify To mechanically loosen soil or break down existing soil structure.
Settlement Downward movement.
Skin Friction (Side
Shear)
The frictional resistance developed between soil and an element of the structure such as a
drilled pier.
Soil (Earth)
Sediments or other unconsolidated accumulations of solid particles produced by the physical
and chemical disintegration of rocks, and which may or may not contain organic matter.
Strain The change in length per unit of length in a given direction.
Stress The force per unit area acting within a soil mass.
Strip To remove from present location.
Subbase A layer of specified material in a pavement system between the subgrade and base course.
Subgrade The soil prepared and compacted to support a structure, slab or pavement system.
Design
Soluble Sulfate
Used to determine the quantitative amount of soluble
sulfates within a soil mass.
Corrosion Potential
Unconfined
Compression
To obtain the approximate compressive strength of soils
that possess sufficient cohesion to permit testing in the
unconfined state.
Bearing Capacity
Analysis for
Foundations
Water Content
Used to determine the quantitative amount of water in a soil
mass.
Index Property Soil
Behavior
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.
M If soil contains 30% plus No. 200, predominantly gravel, add
“gravelly” to group name.
N PI 4 and plots on or above “A” line.
O PI 4 or plots below “A” line.
P PI plots on or above “A” line.
Q PI plots below “A” line.
Gravel
Sand
Silt or Clay
Descriptive Term(s)
of other constituents
N
(HP)
(T)
(DCP)
(PID)
(OVA)
< 15
15 - 29
> 30
Term
PLASTICITY DESCRIPTION
Water levels indicated on the soil boring
logs are the levels measured in the
borehole at the times indicated.
Groundwater level variations will occur
over time. In low permeability soils,
accurate determination of groundwater
levels is not possible with short term
water level observations.
Water Level After
a Specified Period of Time
Water Level After a
Specified Period of Time
Water Initially
Encountered
Modified
Dames &
Moore Ring
Sampler
Standard
Penetration
Test
Unless otherwise noted, Latitude and Longitude are approximately determined using a hand-held GPS device. The accuracy
of such devices is variable. Surface elevation data annotated with +/- indicates that no actual topographical survey was
conducted to confirm the surface elevation. Instead, the surface elevation was approximately determined from topographic
maps of the area.
Standard Penetration Test
Resistance (Blows/Ft.)
Hand Penetrometer
Torvane
Dynamic Cone Penetrometer
Photo-Ionization Detector
Organic Vapor Analyzer
STRENGTH TERMS
BEDROCK
Loose
Medium Dense
Dense
0 - 3
4 - 9
10 - 29
30 - 50
7 - 18
19 - 58
Very Soft
Soft
Medium-Stiff
Stiff
Very Stiff
Standard
Penetration or
N-Value
Blows/Ft.
2 - 4
4 - 8
8 - 15
< 3
5 - 9
19 - 42
> 42
30 - 49
50 - 89
20 - 29
Medium Hard
Very Dense
RELATIVE DENSITY OF COARSE-GRAINED
SOILS
Descriptive
Term
(Density)
Very Loose
> 50
Ring
Sampler
Blows/Ft.
0 - 6
59 - 98
> 99
Descriptive
Term
(Consistency)
Hard
0 - 1
Ring
Sampler
Blows/Ft.
3 - 4
10 - 18
Ring
Sampler
Blows/Ft.
< 30
90 - 119
Standard
Penetration or
N-Value
Blows/Ft.
Descriptive
Term
(Consistency)
Weathered
Firm
Very Hard
CONSISTENCY OF FINE-GRAINED SOILS
(More than 50% retained on No. 200 sieve.)
Density determined by
Standard Penetration Resistance
(50% or more passing the No. 200 sieve.)
Consistency determined by laboratory shear strength testing, field
visual-manual procedures or standard penetration resistance
Standard
Penetration or
N-Value
Blows/Ft.
_ 15 - 30
> 30
> 119
< 20
30 - 49
50 - 79
>79
Hard
LEAN CLAY with SAND(CL)
32
35
36
35
9.5 0.076
4.75
4.75
4.75
6 16
20 30
40 50
1.5 6 200
810
1.5
0.0
0.0
0.0
14
14 - 15.5
2 - 2.9
2 - 2.9
2 - 3
3/8 3 100
3 2 140
COBBLES
GRAVEL SAND
USCS Classification
39.4
25.9
20.5
28.9
D60
coarse medium
Boring ID Depth
Boring ID Depth
GRAIN SIZE DISTRIBUTION
ASTM D422
14 - 15.5
2 - 2.9
2 - 2.9
2 - 3
PROJECT NUMBER: 20155045
PROJECT: St. Peter's Anglican Church
SITE: 6608 Autmn Ridge Road
Fort Collins, Colorado
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
EXHIBIT: B-4
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS-2 20155045.GPJ TERRACON2012.GDT 11/5/15
4
5
LEAN CLAY with SAND(CL)
LEAN CLAY(CL)
LEAN CLAY(CL)
LEAN CLAY with SAND(CL)
SANDY FAT CLAY(CH)
37
43
42
39
69
4.75
9.5
4.75
4.75
9.5
6 16
20 30
40 50
1.5 6 200
810
0.0
0.3
0.0
0.0
0.7
14
2 - 3
4 - 5
4 - 5
9 - 9.8
4 - 5.5
3/8 3 100
3 2 140
COBBLES
GRAVEL SAND
USCS Classification
17.6
11.0
12.2
21.8
29.8
D60
coarse medium
Boring ID Depth
Boring ID Depth
GRAIN SIZE DISTRIBUTION
ASTM D422
2 - 3
4 - 5
4 - 5
9 - 9.8
4 - 5.5
PROJECT NUMBER: 20155045
PROJECT: St. Peter's Anglican Church
SITE: 6608 Autmn Ridge Road
Fort Collins, Colorado
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
EXHIBIT: B-3
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. GRAIN SIZE: USCS-2 20155045.GPJ TERRACON2012.GDT 11/5/15
82
89
88
78
69
59
74
79
71
LL USCS
1
2
3
4
5
5
P1
P3
P4
ATTERBERG LIMITS RESULTS
ASTM D4318
2 - 3
4 - 5
4 - 5
9 - 9.8
4 - 5.5
14 - 15.5
2 - 2.9
2 - 2.9
2 - 3
Fines
P
L
A
S
T
I
C
I
T
Y
I
N
D
E
X
LIQUID LIMIT
PROJECT NUMBER: 20155045
PROJECT: St. Peter's Anglican Church
SITE: 6608 Autmn Ridge Road
Fort Collins, Colorado
CLIENT: St. Peter's Anglican Church
Fort Collins, Colorado
EXHIBIT: B-2
1901 Sharp Point Drive, Suite C
Fort Collins, Colorado
LABORATORY TESTS ARE NOT VALID IF SEPARATED FROM ORIGINAL REPORT. ATTERBERG LIMITS 20155045.GPJ TERRACON2015.GDT 11/5/15
CL-ML
RESULTS
DEPTH
LOCATION See Exhibit A-2
Latitude: 40.49363° Longitude: -105.06322°
WATER LEVEL OBSERVATIONS
FIELD TEST
RESULTS
DEPTH
LOCATION See Exhibit A-2
Latitude: 40.49357° Longitude: -105.06358°
WATER LEVEL OBSERVATIONS
RESULTS
DEPTH
LOCATION See Exhibit A-2
Latitude: 40.49377° Longitude: -105.0638°
WATER LEVEL OBSERVATIONS
RESULTS
DEPTH
LOCATION See Exhibit A-2
Latitude: 40.49411° Longitude: -105.06333°
WATER LEVEL OBSERVATIONS
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 99.8 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
20
FIELD TEST
RESULTS
DEPTH
LOCATION See Exhibit A-2
Latitude: 40.493932° Longitude: -105.06257°
Delayed water level reading
WATER LEVEL OBSERVATIONS
abbreviations.
PROJECT: St. Peter's Anglican Church
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 100.8 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
20
25
FIELD TEST
RESULTS
DEPTH
LOCATION See Exhibit A-2
Latitude: 40.49405° Longitude: -105.06355°
Delayed water level reading
WATER LEVEL OBSERVATIONS
PROJECT: St. Peter's Anglican Church
PERCENT FINES
WATER
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 100.2 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
20
FIELD TEST
RESULTS
DEPTH
LOCATION See Exhibit A-2
Latitude: 40.49397° Longitude: -105.06393°
Delayed water level reading
WATER LEVEL OBSERVATIONS
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 99.3 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
20
25
FIELD TEST
RESULTS
DEPTH
LOCATION See Exhibit A-2
Latitude: 40.49408° Longitude: -105.06374°
Delayed water level reading
WATER LEVEL OBSERVATIONS
CONTENT (%)
DRY UNIT
WEIGHT (pcf)
ATTERBERG
LIMITS
LL-PL-PI
Surface Elev.: 95.0 (Ft.)
ELEVATION (Ft.)
SAMPLE TYPE
WATER LEVEL
OBSERVATIONS
DEPTH (Ft.)
5
10
15
20
FIELD TEST
RESULTS
DEPTH
LOCATION See Exhibit A-2
Latitude: 40.49428° Longitude: -105.06401°
Delayed water level reading
WATER LEVEL OBSERVATIONS