9--9- Specifications- PAR123757 Butterfield Canyon Trailhead Maintenance Building.pdf

THINK PROJECT NUMBER: 25034

PROJECT MANUAL

& SPECIFICATIONS

Specification Divisions 0-33

Butterfield Trailhead

Maintenance Buildings

8300 West U-111

Herriman, Utah

PERMIT SET

October 22, 2025

BUTTERFIELD MAINTENANCE BUILDING PROJECT NUMBER: 20-034

INSTRUCTIONS TO BIDDERS

00 2113 - 1

DOCUMENT 00 2113 - INSTRUCTIONS TO BIDDERS

PART 1 - GENERAL

1.1 INSTRUCTIONS TO BIDDERS

A. The following Documents are bound in the Project Manual for reference

1. A copy of AIA Document A201- 2007 General Conditions of the Contract for Construction.

2. A copy of AIA Document E203-2013, "Building Information Modeling and Digital Data Exhibit", is bound in this Project Manual as Document 002113.4.

3. A copy of "Think Architecture Digital Data Agreement" is bound in this Project Manual as Document 00 2113.5 Exhibit A - Digital Data Agreement.

PART 2 - PRODUCTS (Not Used) PART 3 - EXECUTION (Not Used)

END OF DOCUMENT 00 2113

BUTTERFIELD MAINTENANCE BUILDING PROJECT NUMBER: 20-034

GEOTECHNICAL DATA

003132 - 1

DOCUMENT 003132 - GEOTECHNICAL DATA

PART 1 - GENERAL

1.1 GEOTECHNICAL DATA

A. This Document, with its referenced attachments, is part of the Procurement and Contracting Requirements for the Project. They provide Owner's information for Bidders' convenience and are intended to supplement rather than serve in lieu of Bidders' own investigations. They are made available for Bidders' convenience and information. This Document and its attachments are not part of the Contract Documents.

B. Because subsurface conditions indicated by the soil borings are a sampling in relation to the entire construction area, and for other reasons, Owner, Architect, Architect's consultants, and the firm reporting the subsurface conditions do not warranty the conditions below the depths of the borings or that the strata logged from the borings are necessarily typical of the entire site.

Any party using the information described in the soil borings and geotechnical report accepts full responsibility for its use.

C. A Geotechnical Investigation Report for Project No. 20235619.001A, prepared by Klienfelder dated July 11, 2025, is available for viewing within this Project Manual.

1. The opinions expressed in this report are those of a geotechnical engineer and represent interpretations of subsoil conditions, tests, and results of analyses conducted by a geotechnical engineer. Owner is not responsible for interpretations or conclusions drawn from the data.

2. Any party using information described in the geotechnical report will make additional test borings and conduct other exploratory operations that may be required to determine the character of subsurface materials that may be encountered.

PART 2 - PRODUCTS (Not Used) PART 3 - EXECUTION (Not Used)

END OF DOCUMENT 003132

20235619.001A/SLC25R184298 Page 1 of 1 July 11, 2025 © 2025 Kleinfelder www.kleinfelder.com

KLEINFELDER 849 West Levoy Drive, Suite 200 Salt Lake City, UT 84123-2964 p | 801.261.3336 f | 801.261.3306

July 11, 2025 Kleinfelder Project No: 20235619.001A

Mr. Angelo Calacino, AICP Park Development Project Manager Salt Lake County 2001 South State Street, Suite S4-7000 Salt Lake City, UT 84190

SUBJECT: GEOTECHNICAL ENGINEERING REPORT

PROPOSED MAINTENANCE BUILDING

BUTTERFIELD CANYON TRAILHEAD REGIONAL PARK

8307 WEST HERRIMAN HIGHWAY, EAST OF BACCHUS HIGHWAY (SR-111)

HERRIMAN, UTAH

Dear Mr. Calacino:

We are pleased to submit our geotechnical engineering report for the proposed maintenance building located at approximately 8307 West Herriman Highway in Herriman, Utah. Our geotechnical engineering services are for the proposed building and associated site improvements located at the project site. The geotechnical scope of services for this project were performed in general accordance with our agreement dated May 23, 2025 (County Project Contract Number 0000004454).

This report includes our recommendations relating to the geotechnical aspects of project design and construction. The conclusions and recommendations stated in this report are based on the subsurface conditions encountered in our exploratory boring at the time they were performed. They also are subject to the limitations and provisions stated in the Limitations section of this report.

We appreciate the opportunity to provide continued geotechnical services to you on this project. Please contact Mr. Spencer Davis at 801.261.3336, if you have any questions regarding this report or if we can provide assistance with other aspects of the project.

Respectfully submitted, KLEINFELDER

Joe Potter, PE Spencer Davis, PE Staff Geotechnical Engineer Principal Geotechnical Engineer http://www.kleinfelder.com/

20235619.001A/SLC25R18498 Page i of iv July 11, 2025

GEOTECHNICAL ENGINEERING REPORT

PROPOSED MAINTENANCE BUILDING

BUTTERFIELD CANYON TRAILHEAD REGIONAL PARK

8307 WEST HERRIMAN HIGHWAY, EAST OF BACCHUS

HIGHWAY (SR-111)

JULY 11, 2025

Copyright 2025 Kleinfelder All Rights Reserved

ONLY THE CLIENT OR ITS DESIGNATED REPRESENTATIVES MAY USE THIS DOCUMENT AND ONLY FOR THE SPECIFIC PROJECT FOR WHICH THIS

REPORT WAS PREPARED.

20235619.001A/SLC25R18498 Page ii of iv July 11, 2025

Report prepared for:

Mr. Angelo Calacino, AICP Park Development Project Manager Salt Lake County 2001 South State Street, Suite S4-7000 Salt Lake City, UT 84190

GEOTECHNICAL ENGINEERING REPORT

PROPOSED MAINTENANCE BUILDING

BUTTERFIELD CANYON TRAILHEAD REGIONAL PARK

8307 WEST HERRIMAN HIGHWAY, EAST OF BACCHUS HIGHWAY (SR-111)

Prepared by:

Joe Potter, PE Staff Geotechnical Engineer

Reviewed by:

Spencer Davis, PE Principal Geotechnical Engineer

Kraig Huffaker, PE Senior Geotechnical Engineer

KLEINFELDER

849 W. Levoy Drive, Suite 200 Salt Lake City, Utah 84123 Phone: 801.261.3336

July 11, 2025 Kleinfelder Project No. 20235619.001A

07/11/2025

20235619.001A/SLC25R18498 Page iii of iv July 11, 2025

TABLE OF CONTENTS

Section Page

1 INTRODUCTION

GENERAL

PROJECT DESCRIPTION

PURPOSE AND SCOPE OF SERVICES

2 FIELD EXPLORATION AND LABORATORY TESTING

FIELD EXPLORATION

GEOTECHNICAL LABORATORY TESTING

ANALYTICAL LABORATORY TESTING

3 SITE CONDITIONS

SITE DESCRIPTION

SUBSURFACE CONDITIONS

GEOLOGIC SETTING

GEOLOGIC HAZARDS

Seismicity and Faulting Liquefaction and Lateral Spread

GROUNDWATER

4 CONCLUSIONS AND RECOMMENDATIONS

GENERAL CONCLUSIONS

EARTHWORK

General Site Preparation Wet Weather Construction Temporary Excavation Stability Excavatability Structural Fill and Compaction Utility Trench Backfilling

FOUNDATION RECOMMENDATIONS

Foundation Bearing Soil Preparation Footings and Utilities

LATERAL EARTH PRESSURES

CONCRETE SLABS-ON-GRADE

PAVEMENT DESIGN

SOIL CORROSION AND REACTIVITY

GEOTECHNICAL SERVICES DURING CONSTRUCTION

5 LIMITATIONS

6 REFERENCES

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TABLE OF CONTENTS (Continued)

TABLES

Table 2-1 Analytical Laboratory Test Results Table 3-1 Generalized Soil Profile Table 3-2 General Ground Motion Parameters Based on ASCE 7-16 Table 4-1 Criteria for Structural Fill Table 4-2 Criteria for General Borrow Fill Table 4-3 Criteria for Untreated Base Course Table 4-4 Structural Fill Placement and Compaction Criteria Table 4-5 Allowable Soil Bearing Pressure Table 4-6 Recommended Equivalent Fluid Pressures (EFP)

FIGURES

Figure 4-1 Foundation Zone of Influence

APPENDICES

A Exploration Location & Site Vicinity Map B Exploration Log C Laboratory Test Results D Important Information about your Geotechnical Engineering Report

20235619.001A/SLC25R18498 Page 1 of 23 July 11, 2025

1 INTRODUCTION

GENERAL

This report presents the results of Kleinfelder’s geotechnical exploration for the design and construction of the proposed Butterfield Canyon Trailhead Maintenance Building project and supporting improvements located at approximately 8307 West Herriman Highway, Herriman, Utah. The location of the project site is shown on the Exploration Location and Site Vicinity Map in Appendix A. Our services for this study were performed in general accordance with the scope of work outlined in our purchase order agreement dated

May 23, 2025.

This report includes our recommendations relating to the geotechnical aspects of project design and construction. The conclusions and recommendations stated in this report are based on the subsurface conditions encountered in our exploratory boring at the time it was performed. The conclusions and recommendations stated in this report are subject to the limitations and provisions stated in Section 5 of this report.

PROJECT DESCRIPTION

We understand that Salt Lake County proposes constructing a new maintenance building with a footprint of approximately 1,200 sq. ft. and associated equipment yard. The building is to be a 1-story building (assumed masonry construction). Based on preliminary site concept plans by Think Architecture dated April 25, 2025, we understand proposed site grades will include up to approximately seven feet of fill.

If the project plans vary from these understandings or assumptions, Kleinfelder should be notified immediately to reevaluate our recommendations.

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PURPOSE AND SCOPE OF SERVICES

The purpose of our geotechnical scope was to explore and evaluate subsurface conditions at the proposed site and develop geotechnical recommendations based on the conditions observed at the site. Our geotechnical scope of services included:

• Performing subsurface exploration and soil sampling to characterize the subsurface soil profile throughout the site.

• Performing laboratory testing of selected soil samples to evaluate the engineering properties of the soils.

• Performing engineering analyses and developing geotechnical conclusions and recommendations for design and construction of the planned development.

• Preparation of this report, which includes a description of the proposed project, a description of the surface and subsurface site conditions found during our exploration and laboratory testing programs, and a summary of our conclusions and recommendations for site preparation and grading, structural fill placement, foundation design, and related geotechnical issues.

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2 FIELD EXPLORATION AND LABORATORY TESTING

FIELD EXPLORATION

Kleinfelder subcontracted with Davis Drilling to advance one (1) exploratory boring on June 10, 2025. The approximate location of the exploration is presented in Appendix A.

The boring was drilled with a CME-75 truck-mounted drill rig equipped with 8 -inch outside diameter (O.D.)

hollow-stem augers. Soil samples were obtained intermittently during drilling using a standard penetration test, split spoon samplers (SPT) and thin-walled Shelby tube samplers. The split spoon samplers (2-inch O.D) were driven with a hydraulically actuated 140-pound hammer (auto-hammer) free falling a distance of 30 inches. The number of blows required to drive the sampler 18 inches into the soil were recorded for each 6-inch increment of penetration on the boring logs. Where blow counts exceeded 50 in 6 inches or less, the depth of penetration was recorded upon reaching 50 blows (example: 50/4”). Relatively undisturbed samples of fine-grained soils were collected using a standard Shelby tube sampler (3-inch O.D). Shelby tube samples were obtained by pushing the sampler using the drill rig hydraulics. Portions of the soil samples were packaged in the field and returned to our laboratory for additional testing.

Logs of the subsurface conditions encountered in the boring were maintained in the field by a Kleinfelder geoprofessional. The logs of the conditions encountered by Kleinfelder are presented in Appendix B. A key to the boring logs and a summary of the Unified Soil Classification System (USCS) soil descriptions are also contained in Appendix B. The lines defining boundaries between soil types on the logs are based on

Kleinfelder’s field observations and are therefore approximate. Transition between soil types may be abrupt or may be gradual. Samples will be retained for a period of 90 days from the date of this geotechnical report, after which time the samples will be discarded unless otherwise requested.

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GEOTECHNICAL LABORATORY TESTING

Geotechnical laboratory tests were performed on select soil samples to classify and characterize the soil and estimate geotechnical engineering properties. The following tests were performed in general accordance with ASTM or other recognized standards:

• Water Content

• Soil Unit Weight

• Percent passing the #200 sieve

• Atterberg Limits

• One-Dimensional Consolidation

• Unconsolidated Undrained Triaxial Compression

Results of the geotechnical laboratory tests are included in Appendix C of this report. Sample test locations and selected geotechnical test results are also shown on the boring log presented in Appendix B.

ANALYTICAL LABORATORY TESTING

The following analytical laboratory testing was performed on soil samples by an independent analytical laboratory:

• pH,

• Resistivity,

• Soluble sulfate, and

• Soluble chloride.

The analytical laboratory test results are presented in Appendix C and are summarized below:

Table 2-1: Analytical Laboratory Test Results

Sample Location and Depth (ft) pH Resistivity

(ohms-cm) Soluble Sulfate

(mg/kg dry) Soluble Chloride

(mg/kg dry)

25-B-01 at 5.0’ 8.5 1,320 40 < 12

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3 SITE CONDITIONS

SITE DESCRIPTION

At the time of our field exploration, the site consisted of sparse vegetation and the ground surface sloped gently to the east. Existing development associated with the Butterfield Canyon trailhead is present west of the proposed maintenance building. Existing development consisted of Portland Cement Concrete pavement and aggregate-surfaced parking areas.

SUBSURFACE CONDITIONS

The subsurface conditions observed in the boring are generally as shown in Table 3-1. The boring log presented in Appendix B and the laboratory test results presented in Appendix C should be referred to for more detailed information regarding the subsurface soil conditions at this site.

Table 3-1: Generalized Soil Profile

Generalized Soil Type Approximate Depth to Bottom of Stratum Below Existing Grade

Sandy Lean CLAY 13 feet

GRAVEL with varying amounts of silt, sand and clay 23 feet

Silty SAND with varying amounts of gravel 46.5 feet1

Note 1. Maximum explored depth

GEOLOGIC SETTING

The site is located within Salt Lake Valley, on the east bench of the Oquirrh Mountains. The valley is within the Basin and Range Physiographic Province, which is characterized by approximately north-trending valleys and mountain ranges which have been formed by extensional tectonics and displacement along normal faults

(Hunt, 1967). The near-surface geology at the site location, as mapped by Biek (2018), is modern stream deposits, consisting of moderately to well-sorted sand, silt, clay, and gravel. The subsurface soils encountered in our explorations are generally consistent with the published mapping.

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GEOLOGIC HAZARDS

Seismicity and Faulting

Active faults in the region are potential sources for seismic shaking hazards. Active earthquake faults are typically considered as faults that have moved during the past 10,000 years. The nearest active fault is the

Oquirrh Fault Zone, located approximately 6.3 miles west of the site (USGS, 2025). Other active faults in the region include the Salt Lake City segment of the Wasatch fault zone, located approximately 13.4 miles east of the site (USGS, 2025).

Seismic design parameters consistent with the 2021 International Building Code (IBC) are based on the

American Society of Civil Engineers (ASCE) 7-16 Minimum Design Loads and Associated Criteria for Buildings and Other Structures. Based on our subsurface investigation the underlying soil at the site corresponds with a

Site Class D per Table 20.3-1 of ASCE 7-16. The general, non-site-specific, seismic design parameters were obtained per 2021 IBC/ASCE 7-16 based on the site class, site coordinates and the risk category of the structure using the online tool (https:/seismicmaps.org). These values are summarized in Table 3-2.

Table 3-2: General Ground Motion Parameters Based on ASCE 7-16 Parameter Value ASCE 7-16 Reference

Latitude (degrees) 40.5130 N/A Longitude (degrees) -112.0877 N/A

Assumed Building Risk Category II N/A

SS 0.866 g Fig 22-1 S1 0.313 g Fig 22-2

Site Class D – Stiff Soil Table 20.3-1 Fa 1.154 Table 11.4-1 Fv N/A (Note 1) Table 11.4-2 CRS 0.884 Fig 22-18A CR1 0.888 Fig 22-19A SMS 0.999 Eq. 11.4-1 SM1 N/A (Note 2) Eq. 11.4-2 SDS 0.666 Eq. 11.4-3 SD1 N/A (Note 2) Eq. 11.4-4

PGA 0.378 Fig 22-9 Fpga 1.222 Table 11.8-1

PGAM 0.462 g Eq. 11.8-1

Note 1. See Section 11.4.8 of ASCE 7-16. Since the S1 > 0.2 g and site is Site Class D, site specific analysis is needed unless exception is taken per Section 11.4.8.

Note 2. See requirements for site-specific ground motions in Section 11.4.8

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Liquefaction and Lateral Spread

Liquefaction is a phenomenon whereby loose, saturated, soil deposits lose a significant portion of their shear strength due to excess pore water pressure buildup resulting from dynamic loading, such as that caused by an earthquake. Among other effects, liquefaction can result in densification of such deposits causing settlements of overlying layers after an earthquake, as excess pore water pressures are dissipated.

Horizontally continuous liquefied layers may also have a potential to spread laterally where sufficient slope or free-face conditions exist. The primary factors affecting liquefaction potential of a soil deposit are: (1) level and duration of seismic ground motions; (2) soil type and consistency; and (3) depth of groundwater.

Based on the soil conditions encountered during our field investigation, including the relatively high density of the submerged granular soils as indicated by blow count values, the plasticity of the fine-grained soils, and the depth of groundwater, it is our opinion that the potential for liquefaction at this site is low and does not warrant further consideration.

GROUNDWATER

Groundwater was observed at approximately 41 feet below existing grade during drilling. Groundwater levels are dependent on seasonal precipitation and groundwater fluctuations, irrigation practices, land use, and runoff conditions. A detailed study of site hydrogeologic conditions was beyond the scope of work for this investigation; as a result, we have not characterized potential groundwater fluctuations at the site.

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4 CONCLUSIONS AND RECOMMENDATIONS

GENERAL CONCLUSIONS

Based on the results of our field exploration and laboratory testing, it is our opinion that the site is suitable for the planned building provided that the recommendations contained in this report are followed.

These opinions, conclusions, and recommendations are based on our field exploration, engineering analyses, the properties of the materials encountered in our boring, the results of the laboratory testing program, and our understanding of the proposed development of the site.

EARTHWORK

General Site Preparation

Prior to commencing site-grading operations, the planned fill area, including building, flatwork, and equipment yard areas should be stripped of all vegetation, topsoil, and debris. The required stripping depth will vary across the site depending on the amount of fill, and debris present. Based on observations made at the site, we anticipate required stripping depths will be approximately 6 inches; however, locally deeper stripping depths may be required in areas where larger vegetation is present or unstable, soft or loose soil is encountered.

After stripping has been completed, exposed native soils should be proof-rolled with either a fully loaded tandem-axle dump truck or a fully loaded water truck, and observed by the geotechnical engineer or their representative or hand probed at regular, frequent intervals to identify soft or unstable areas.

If exposed to excess moisture and/or repeated construction traffic, native fine-grained near surface soils will become unstable, especially during wet weather. The use of track-mounted equipment with low ground pressure tracks and/or the use of dump and spread techniques to place material should be considered, particularly if construction occurs during the wet seasons of the year. Conventional wet weather earthwork practices should be employed, and the construction schedule should account for weather related delays associated with rain and snow if earthwork is planned for late fall, winter, or early spring. Subgrade soils that

20235619.001A/SLC25R18498 Page 9 of 23 July 11, 2025 become unstable or disturbed due to exposure to excess moisture will require replacement or remedial measures, such as:

• Removal and Replacement with Structural Fill and Geotextile Fabric and/or Geogrid: Where encountered during proof-rolling, unstable subgrade could be over-excavated below existing grade and replaced with approved structural fill underlain by geotextile fabric and/or geogrid, overexcavation depth will depend on the severity of the instability. The overexcavated areas should be backfilled with structural fill in accordance with Section 4.2.5. Geotextile fabric and/or geogrid should be placed in accordance with the manufacturer’s recommendations.

o The geotextile fabric should consist of a woven geotextile, such as Mirafi 600X or equivalent and, as needed, combined with a geogrid, such as Mirafi BXG120 or equivalent. Alternatively, a combined separation/reinforcing fabric may be used, such as Mirafi RS-380i or equivalent.

o Overexcavation depth of between 12 to 18 inches may be needed, but the final depth of removal will depend upon conditions observed in the field once overexcavation begins and should be assessed by the geotechnical engineer.

• Drying: Drying of subgrade soils that are unstable due to excess moisture involves discing or ripping wet subgrade to a depth of approximately 12 to 18 inches and allowing the exposed soil to dry. Multiple passes of the equipment (likely on a daily basis) will be needed because as the surface of the soil dries, a crust forms that reduces further evaporation. Frequent discing will help prevent the formation of a crust and will promote drying. This process could take several days to several weeks depending on the depth of ripping, the number of passes, and the weather. The material should be recompacted in accordance with Section 4.2.5.

Following any stabilization activities, the stabilized areas should be proof-rolled with similar equipment used during the initial proof-rolling to confirm that the stabilization methods have repaired the unstable areas.

4.2.1.1 Site Grading Fill

We understand a grade raise of approximately 7 feet is planned as a part of this project. Following native soil preparation as described above, the grade raise should be constructed using properly prepared and compacted fill.

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Site grading fill should consist of structural fill meeting the gradation presented in Table 4-1 within a

1Horizontal to 1Vertical (1H:1V) zone extending from the outer edge of the concrete apron proposed around the maintenance building (or a minimum of 7-foot setback from the edge of footing as shown in Figure 4-1).

Outside of this zone, fill may consist of general borrow fill meeting the gradation presented in Table 4-2.

Where fills are placed on slopes steeper than 5H:1V and along the interface of structural fill and general borrow, soils should be benched. Benching of the slope is essential to the long-term stability of the final slope/bench configuration as it serves to “key in” the fill material to the slope and facilitates proper compaction of fill soils. Each bench should be level and extend into the slope a minimum of 5 to 6 feet to accommodate conventional grading and compaction equipment. The height of each bench should not exceed

3 feet.

Wet Weather Construction

Precautions should be taken during and after construction to eliminate the potential for saturation of soils beneath foundations and pavements. Over-wetting of the native soils prior to or during construction may result in softening and pumping, causing equipment mobility problems and difficulty in achieving compaction. Over-wetting of the native soils after construction may result in softening of foundation soils leading to additional settlements that may negatively affect the performance of the structure. Positive drainage should be established away from the structure and pavements. Subgrade soils that become unstable or disturbed due to exposure to excess moisture will require replacement or remedial measures as outlined in Section 4.2.1.

Temporary Excavation Stability

Stability of construction excavations is the contractor’s responsibility. If stability of an excavation becomes questionable, the excavation should be evaluated promptly by Kleinfelder. The soils classification and strength properties presented in this report may be used for the planning of excavations and trench slopes in accordance with OSHA requirements or for the design of excavation slopes, shoring and/or the use of trench boxes. Construction personnel should be aware that soil conditions may change rapidly if soil moisture conditions change or if soils that have been disturbed by previous excavations are encountered. Measures should be taken to protect construction personnel from raveling of trench sidewalls. If sloughing or free water is encountered, it may be necessary to reduce trench slopes beyond Occupational Safety and Health

Administration (OSHA) requirements or provide shoring. Although not anticipated, if groundwater is

20235619.001A/SLC25R18498 Page 11 of 23 July 11, 2025 encountered in excavations precautions should be taken to mitigate buoyancy of tanks or utilities placed in the excavations. All excavations should comply with current OSHA safety requirements. Backfill of excavations should be structural fill in compliance with Section 4.2.6. If conditions other than those encountered in the geotechnical explorations are present, excavation slopes should immediately be re-evaluated.

Excavatability

Based on the excavation of our soil boring, which utilized standard soil auger-drilling methods, we anticipate that excavation of the on-site materials can be performed using conventional earth-moving equipment.

However, the contractor should satisfy themselves as to the difficulty involved and the type of equipment needed.

Structural Fill and Compaction

Structural fill placed within a zone extending at 1H:1V from the building and flatwork footprint should be granular material as detailed in Table 4-1, or untreated base course. We anticipate that the native soils will not be suitable for re-use as structural fill. Soils with greater than 15% fines (i.e. > 15% passing the No. 200 sieve) can be placed in a potentially collapsible or expansive state if proper construction procedures are not followed. Fill placed outside of the structural fill zone described in section 4.2.1.1 may consist of general borrow fill as detailed in Table 4-2. Kleinfelder should be contacted if these soils are desired for reuse below pavement and concrete flatwork.

Table 4-1: Criteria for Structural Fill

Gradation Requirements

Standard Sieve Size Percent Passing 4 inch 100 ¾ inch 100-70 No. 40 10-60

No. 200 0-15*

Plasticity Requirements of Fines (Atterberg Limits)

Plasticity Index 6 or less

*Fill with more than 15 percent fines may be acceptable as approved by Kleinfelder; contingent on comments and limitations listed above.

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Table 4-2: Criteria for General Borrow Fill

Gradation Requirements

Standard Sieve Size Percent Passing 6 inch 100 ¾ inch 100-70

No. 200 0-35

Plasticity Requirements of Fines (Atterberg Limits)

Plasticity Index 10 or less

Table 4-3: Criteria for Untreated Base Course

Gradation Requirements

Standard Sieve Size Percent Passing 1-1/2 inch 100

1 inch 90-100 ¾ inch 70-851 ½ inch 65-80

3/8 inch 55-75 No. 4 40-65

No. 16 25-40 No. 200 7-11

Plasticity Requirements of Fines (Atterberg Limits)

Plasticity Index 6 or less2

Note 1: For improved performance and maintenance of aggregate- surfaced pavements, this value may be increased to 100.

Note 2: For improved performance and maintenance of aggregate- surfaced pavements, this value may be increased to 12 or less.

Untreated base course material should be comprised of Untreated Base Course Aggregate Class “C” per

Section 02721 of the latest UDOT Standard Specifications for Untreated Base Course. Imported fill materials should be approved by the geotechnical engineer or their representative prior to importing. Also, prior to placing structural fill, the excavation should be observed by the geotechnical engineer or their representative to note that unsuitable material has been removed and the exposed soil is in a firm and unyielding condition.

Structural fill and General Borrow fill should be placed in maximum 8-inch-thick loose lifts and compacted to at least 95 percent of the maximum dry density (ASTM D1557 - Modified Proctor). The contractor will need to moisture condition the soils to be within the range outlined in Table 4-4 at the time of compaction.

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Table 4-4: Structural Fill Placement and Compaction Criteria

Fill Location Material Type Percent Compaction

(ASTM D1557)

Moisture Content

Minimum Compaction Testing Frequency Per Lift

Top 12 inches below interior and exterior concrete slabs

Imported Gravel or Aggregate Base 95 minimum -2% to +2% of optimum 5,000 Square Feet

Below foundation bearing level Granular Structural Fill 95 minimum -2% to +2% of optimum 5,000 Square Feet

Site grading fills placed below building areas (extending 1H:1V beyond 7-foot setback zone) Granular Structural Fill 95 minimum -2% to +2% of optimum 5,000 Square Feet

Site grading fills placed outside building areas (extending 1H:1V beyond 7-foot setback zone) General Borrow Fill 95 minimum -2% to +2% of optimum 5,000 Square Feet

Foundation wall backfill Granular Structural Fill 95 minimum -2% to +2% of optimum 500 Square Feet

Utility trench backfill Granular Structural Fill or Approved Trench Backfill Material

95 minimum -2% to +2% of optimum 100 Linear Feet

Subgrade Stabilization / Landscape/Undeveloped Areas

On-site soil / Granular Structural Fill / General

Borrow Fill 90 minimum -2% to +3% of optimum 15,000 Square Feet

Utility Trench Backfilling

Pipe bedding and pipe zone (haunching) material should consist of granular fill materials. Bedding material should consist of sand, gravel, crushed aggregate, or select free-draining granular material with a maximum particle size of ¾ inch. Bedding materials should also conform to the pipe manufacturer's specifications, if available. The bedding material should be compacted to at least 90 percent of the maximum dry density within 2 percentage points from the optimum moisture content or to the satisfaction of the project geotechnical engineer's representative observing the compaction of the bedding material.

The haunching material should consist of either structural fill, sand, gravel, crushed aggregate, or select free-draining materials conforming with the pipe manufacturer’s specifications, if available. If free-draining soils

(i.e. soils with large voids, such as crushed gravel), the utility trench and haunching material should be wrapped with filter fabric to limit the migration of fines into the gravel. The haunching material should be compacted to at least 95 percent of the maximum dry density within 2 percentage points from the optimum moisture content or to the satisfaction of the project geotechnical engineer's representative observing the compaction of the material.

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Trench backfill above bedding and pipe zone materials may consist of approved import soils placed in lifts no greater than 8 inches loose thickness and compacted to 95 percent of the maximum dry density within 2 percentage points from the optimum moisture content (ASTM D1557). Mechanical compaction is recommended; ponding or jetting should be avoided, especially in areas supporting structural loads or beneath concrete slabs supported on grade, pavements, or other improvements.

FOUNDATION RECOMMENDATIONS

Exterior footings, or footings in unheated areas, should be established a minimum of 30 inches below the lowest adjacent final grade for frost protection and confinement. Interior footings should likewise be established a minimum of 24 inches below the adjacent grade for frost protection and confinement.

Structural fill should be placed within the zone of influence of the foundation defined by a

1Horizontal:1Vertical (1H:1V) plane extending downward from the edge of the foundations, schematically shown in Figure 4-1. This will facilitate proper distribution of the applied foundation pressures within the structural fill and meet the requirements for bearing capacity.

Figure 4-1:

Foundation Zone Influence

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Footings placed on twelve inches of properly prepared and compacted granular structural fill may be proportioned for maximum net allowable soil bearing pressures in accordance with Table 4-5. The minimum and maximum footing sizes should be limited to those listed in Table 4-5. If other sizes or additional wall or column capacity is needed, then Kleinfelder should be contacted to provide additional recommendations. A one-third increase may be applied for transient wind or seismic loads. Total, static settlement of footings should be on the order of 1-inch or less with maximum static differential settlements of ½-inch or less for similar sized footings. Prior to placing structural fill, the footing excavations should be observed by the geotechnical engineer or their representative to evaluate whether suitable bearing soils have been exposed and whether the excavation bottoms are free of loose or disturbed soils.

Table 4-5: Allowable Soil Bearing Pressure

Item Isolated Footing Continuous Footing

Bearing Capacity 2,000 psf

Bearing Depth 30 inches below final grade for exterior footings

Required Bearing Stratum 12 inches of properly prepared Granular Structural Fill

Maximum Footing Dimensions1 5 x 5 ft 3 ft

Minimum Footing Dimensions1 2 x 2 ft 1 ft

Note 1. Maximum and minimum dimensions to limit total settlement to 1 inch and differential settlement to less than 1/2 inch.

Foundation Bearing Soil Preparation

Soils below planned footings should be prepared as shown in Figure 4-1 and described in Section 4.2.1.

Structural fill should be placed within the zone of influence of the foundation defined by a

1Horizontal:1Vertical (1H:1V) plane extending downward from the edge of the foundations, schematically shown in Figure 4-1. This will facilitate proper distribution of the applied foundation pressures within the structural fill and meet the requirements for bearing capacity.

Prior to construction of the foundations, the geotechnical engineer or his representative should observe the excavations and review documentation of structural fill placement and compaction to evaluate whether suitable bearing soils have been provided and whether the excavation bottoms are free of undocumented fill, soft, loose, unstable or disturbed soils, rock, mud, water or frost. Concrete should never be placed on frozen subgrades.

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Footings and Utilities

We recommend the civil engineer design the utilities to be constructed outside the zone of influence of foundations. If utilities are to be installed under the wall footings after placement of the footing, the excavation should be checked by the geotechnical engineer or their representative and backfilled with flowable fill.

The design team should exercise caution when designing utilities and irrigation systems. Care should be exercised to avoid saturating on-site soils by leaking utility or irrigation lines. Irrigation systems should be installed and routed to avoid saturating soils near footings, flatwork, and pavement areas. The contractor should take care during construction of gravity feed utility sewer and storm drain and irrigation lines to reduce the potential for leaks, as these lines are not typically pressure tested.

LATERAL EARTH PRESSURES

Horizontal loads acting on foundations formed in open excavations will be resisted by friction acting at the base of foundations and by passive earth pressures acting on the embedded face of the foundation. If design makes use of passive earth pressures, it is important that any backfill around footings is properly placed and compacted structural fill as described in Section 4.2.5. In this case, we recommend the geotechnical engineer, or his representative be present during any footing backfill placement.

Lateral earth pressures may be proportioned according to Table 4-6. The friction acting along the base of footings, founded on granular structural fill, may be computed by using a nominal/ultimate coefficient of friction of 0.45 with the normal dead load. A nominal/ultimate lateral passive earth pressure may be computed by using an equivalent lateral fluid weighing 450 pounds per cubic feet (pcf) for the side of footings placed against properly compacted granular structural fill. The structural designer should refer to

Section 1807.2.3 of IBC 2021 for appropriate factors of safety for use in the foundation sliding analysis.

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Table 4-6: Recommended Equivalent Fluid Pressures (EFP)

Unit Active1,2,4

(EFPA)

At-rest1

(EFPo) Seismic1,3,4

(EFPAE)

Pounds per cubic foot (pcf) Granular Fill φ’=34°, γ’=130 pcf Ka=0.28, k0=0.44, Kae=0.44

37 57 57

Native Clay Soils φ’=26°, γ’=120 pcf

Ka=0.39, k0=0.56, Kae=0.58 47 67 69

Note 1: Assumes fully drained soil, level conditions at toe and crest of wall, and a vertical wall back face.

Note 2: Assumes deflection at crest of wall is 0.001H for active condition, where H is the wall height.

Note 3: Seismic combines the active and dynamic increment earth pressures and is distributed analogous to the active earth pressure. PGAM = 0.462 g, kh = ½ PGA Note 4: Neglects soil-wall interface friction.

CONCRETE SLABS-ON-GRADE

Concrete slabs on grade should be designed with a minimum of 12 inches of structural fill, of which the upper

4 inches is free-draining gravel below the slab, where required by IBC Chapter 18 requirements.

As a basis for designing concrete slab thickness, the structural fill soils used to support the slab may be considered to possess a subgrade modulus (kv1) of 135 pounds per cubic inch (pci). These values correspond to a 1-foot square plate and should be adjusted for the designed slab geometry.

All concrete slabs should be designed to minimize cracking as a result of shrinkage. Special precautions must be taken during the placement and curing of all concrete slabs. Excessive slump (high water-cement ratio) of the concrete and/or improper curing procedures used during either hot or cold weather conditions could lead to excessive shrinkage, cracking, or curling in the slabs. We recommend that all concrete placement and curing operations be performed in accordance with the American Concrete Institute Manual (ACI, 2014).

PAVEMENT DESIGN

We understand new pavements associated with the project will consist of Portland Cement Concrete (PCC) and aggregate-surfaced sections. Recommended pavement sections are based upon an assumed 50,000

Equivalent-Single-Axle-Load with no traffic data being provided for this facility at the time of our report. We anticipate the proposed use of the building will bring traffic consisting of primarily light duty pickups and

20235619.001A/SLC25R18498 Page 18 of 23 July 11, 2025 service trucks. The pavement and base course thicknesses were determined following the procedures in

American Association of Highway and Transportation Officials Guide for Design of Pavement Structures

(AASHTO, 1993) and Utah Department of Transportation’s Pavement Management and Pavement Design

Manual (UDOT, 2008). A CBR of 5 percent was selected for design based upon laboratory testing and soil conditions observed during our field exploration.

We anticipate traffic loading conditions will be relatively consistent across the paved surfaces for the site.

These recommended sections are a combination of designed thicknesses and recommendations for the ease of construction (UDOT, 2008). The minimum pavement sections are presented in Table 4-7. We recommend the minimum Portland cement concrete pavement sections be used in areas of anticipated heavy, repeated, and sustained loading (i.e. dumpster pads/garbage pickup and truck unloading). If the actual traffic conditions are different than those assumed, Kleinfelder should be notified so that our recommendations can be reviewed and modified as appropriate. UTBC or structural fill meeting the criteria contained in Section

4.2.6 should be used for the construction of base course below concrete pavements. We recommend aggregate-surfaced pavements consist of UTBC meeting the modified gradation presented in Table 4-3.

Exposed soils should be proof-rolled with either a fully loaded tandem-axle dump truck or a fully loaded water truck and observed by the geotechnical engineer or their representative or hand probed at regular, frequent intervals to identify soft or unstable areas.

Table 4-7: Recommended Pavement Sections (CBR = 5%)

Pavement Type PCC Thickness (in)

UTBC Thickness (in)

Portland Cement Concrete 5.5 6

Aggregate-Surface - 8

SOIL CORROSION AND REACTIVITY

Kleinfelder has completed preliminary laboratory testing to provide data regarding corrosivity of onsite soils.

Our services do not include corrosion engineering and therefore, a detailed analysis of corrosion test results is not included in this report. A qualified corrosion engineer should be retained to review the test results, perform additional testing as required, and design protective systems that may be required.

Laboratory resistivity, water-soluble sulfate, water-soluble chloride, and pH tests were performed on a representative sample of the near-surface soil in the building area. Results of these tests are listed in

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Appendix C and summarized in Table 2-1. If fill materials are imported to the project site, similar corrosion potential laboratory testing should be completed on the imported material.

Metal and concrete elements in contact with soil are subject to degradation due to corrosion or chemical attack. Therefore, buried metal and concrete elements should be designed to resist corrosion and degradation based on accepted practices.

The near-surface native soils are considered to be non-corrosive for buried ferrous metal piping, cast iron pipes, or other objects made of these materials.

The degradation of concrete or cement grout can be caused by chemical agents in the soil or groundwater that react with concrete to either dissolve the cement paste or precipitate larger compounds within the concrete, causing cracking and flaking. The concentration of water-soluble sulfates in the soils is a good indicator of the potential for chemical attack of concrete or cement grout. The American Concrete Institute

(ACI) in their publication Guide to Durable Concrete (ACI 201.2R-08) provides guidelines for this assessment.

Based on the results of the tests performed at the site, the risk of attack to concrete from water-soluble sulfates appears to be “low” according to American Concrete Institute standards (ACI 318); therefore, Type II

Portland cement may be used for concrete placed on native soils.

GEOTECHNICAL SERVICES DURING CONSTRUCTION

As the geotechnical engineering firm that performed the geotechnical evaluation for this project, we recommend that Kleinfelder be retained to verify the design assumptions and confirm the recommendations of this report are properly incorporated in the design of this project, and properly implemented during construction. This may avoid misinterpretation of the information by other parties and will allow us to review and modify our recommendations if variations in subsurface conditions are encountered that differ from those considered in our geotechnical engineering analyses and design. It is our recommendation Kleinfelder be retained to provide the following continuing services for the project:

• Review the project plans and specifications, including any revisions or modifications;

• Observe and evaluate the site earthwork operations to confirm subgrade soils are suitable for construction of foundations, slabs-on-grade, pavements, and placement of engineered fill;

• Confirm engineered fill for the structure and other improvements is placed and compacted per the project specifications; and

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• Observe foundation bearing soils to confirm conditions are as anticipated.

If a third party is retained to provide the above activities, they are responsible to notify Kleinfelder of any changed site conditions that affect the recommendations presented herein. Kleinfelder must also be retained to perform a supplemental evaluation and to issue a revision to our original report. If notification is not provided, the testing company will assume responsibility associated with the changed site conditions.

Kleinfelder cannot be responsible for interpretation by others of this report, or the conditions encountered in the field.

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5 LIMITATIONS

This work was performed in a manner consistent with that level of care and skill ordinarily exercised by other members of Kleinfelder’s profession practicing in the same locality, under similar conditions and at the date the services are provided. Our conclusions, opinions and recommendations are based on a limited number of observations and data. It is possible that conditions could vary between or beyond the data evaluated.

Kleinfelder makes no other representation, guarantee or warranty, express or implied, regarding the services, communication (oral or written), report, opinion, or instrument of service provided.

This report may be used only by the Client and the registered design professional in responsible charge and only for the purposes stated for this specific engagement within a reasonable time from its issuance, but in no event later than three years from the date of the report.

The work performed was based on project information provided by Client. Any changes in the project information listed herein that will have an impact on recommendations in this report must be approved by

Kleinfelder’s engineer.

It should be recognized that definition and evaluation of subsurface conditions are difficult. Judgments leading to conclusions and recommendations are generally made with incomplete knowledge of the subsurface conditions present due to the limitations of data from field studies.

Kleinfelder offers various levels of investigative and engineering services to suit the varying needs of different clients. Although risk can never be eliminated, more detailed and extensive studies yield more information, which may help understand and manage the level of risk. Since detailed study and analysis involves greater expense, our clients participate in determining levels of service, which provide information for their purposes at acceptable levels of risk. The client and key members of the design team should discuss the issues covered in this report with Kleinfelder, so that the issues are understood and applied in a manner consistent with the owner’s budget, tolerance of risk and expectations for future performance and maintenance.

Recommendations contained in this report are based on our field observations and subsurface explorations, limited laboratory tests, and our present knowledge of the proposed construction. If soil, rock, or groundwater conditions are encountered during construction that differ from those described herein, the client is responsible for ensuring that Kleinfelder is notified immediately so that we may reevaluate the

20235619.001A/SLC25R18498 Page 22 of 23 July 11, 2025 recommendations of this report. If the scope of the proposed construction, including the estimated building loads, and the design depths or locations of the foundations, changes from that described in this report, the conclusions and recommendations contained in this report are not considered valid unless the changes are reviewed, and the conclusions of this report are modified or approved in writing, by Kleinfelder.

The scope of services for this subsurface exploration and geotechnical report did not include environmental assessments or evaluations regarding the presence or absence of wetlands or hazardous substances in the soil, surface water, or groundwater at this site.

This report, and any future addenda or reports regarding this site, may be made available to bidders to supply them with only the data contained in the report regarding subsurface conditions and laboratory test results at the point and time noted. Because of the limited nature of any subsurface study, the contractor may encounter conditions during construction which differ from those presented in this report. In such event, the contractor should promptly notify the owner so that Kleinfelder’s geotechnical engineer can be contacted to confirm those conditions. We recommend the contractor describe the nature and extent of the differing conditions in writing and that the construction contract include provisions for dealing with differing conditions. Contingency funds should be reserved for potential problems during earthwork and foundation construction. Furthermore, the contractor should be prepared to handle contamination conditions encountered at this site, which may affect the excavation, removal, or disposal of soil; dewatering of excavations; and health and safety of workers.

Kleinfelder does not practice corrosion engineering and, therefore, detailed analysis of corrosion is not…