CAMI - WiWAVES - Geotechnical Report - REV1 2020-03-18.pdf

Geotechnical Engineering Report New FAA Building

S.W. 68th Street and Denning Avenue Oklahoma City, Oklahoma

March 18, 2020 Terracon Project No. 03155230

Revision 1

Prepared for:

Guernsey

Oklahoma City, Oklahoma

Prepared by:

Terracon Consultants, Inc.

Oklahoma City, Oklahoma

New FAA Building ■ Oklahoma City, Oklahoma March 18, 2020 ■ Terracon Project No. 03155230 Revision 1

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TABLE OF CONTENTS

Page

1.0 INTRODUCTION

2.0 PROJECT INFORMATION

2.1 Project Description

2.2 Site Location and Description

3.0 SUBSURFACE CONDITIONS

3.1 Typical Subsurface Profile

3.2 Groundwater

4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION

4.1 Geotechnical Considerations

4.2 Earthwork

4.2.1 Site Preparation

4.2.2 Excavation

4.2.3 Subgrade Preparation

4.2.4 Fill Material Requirements

4.2.5 Fill Placement and Compaction Requirements

4.2.6 Grading and Drainage

4.2.7 Utility Trench Backfill

4.2.8 Corrosion Potential

4.3 Foundations

4.3.1 Shallow Foundation Design Recommendations

4.3.2 Shallow Foundation Construction Considerations

4.3.3 Drilled Pier Foundation Design Recommendations

4.3.4 Drilled Pier Foundation Construction Considerations

4.4 Seismic Considerations

4.5 Floor Slab Design Recommendations

4.6 Lateral Earth Pressures

4.7 Pavements

4.7.1 Pavement Design Recommendations

4.7.2 Pavement Construction Considerations

5.0 GENERAL COMMENTS

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TABLE OF CONTENTS - (Cont’d.)

APPENDIX A - FIELD EXPLORATION

Exhibit A-1 Site Location Plan Exhibit A-2 Boring Location Plan Exhibit A-3 Field Exploration Description Exhibits A-4 to A-30 Borings B-1 to B-27 Exhibit A-31 Subsurface Profile

APPENDIX B - LABORATORY TESTING

Exhibit B-1 Laboratory Test Description

APPENDIX C - SUPPORTING DOCUMENTS

Exhibit C-1 General Notes Exhibit C-2 Unified Soil Classification Exhibit C-3 Sedimentary Rock Classification

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GEOTECHNICAL ENGINEERING REPORT

NEW FAA BUILDING

S.W. 68TH STREET AND DENNING AVENUE

OKLAHOMA CITY, OKLAHOMA

Terracon Project No. 03155230 March 18, 2020

Revision 1

1.0 INTRODUCTION

This report presents the results of our geotechnical engineering services performed for the new FAA building to be located northeast of the S.W. 68th Street and Denning Avenue intersection in Oklahoma City, Oklahoma. Terracon’s geotechnical scope of work included the advancement of 27 test borings to approximate depths of about 5 to 40 feet below existing site grades. Boring B-1 through B-23 were performed in November of 2015. Supplemental borings B-24 through B- 27 were completed in February of 2020. The purpose of these services is to provide information and geotechnical engineering recommendations relative to:

n subsurface soil/rock conditions n groundwater conditions n earthwork n foundation design and construction n seismic considerations n floor slab design and construction n lateral earth pressures n pavement design and construction n seismic site classification per IBC

2.0 PROJECT INFORMATION

2.1 Project Description

Item Description

Site layout See Appendix A, Exhibit A-2, Boring Location Plan.

Structures

The project includes the construction of a building with a planned finished floor elevation of 1276 feet. The building will have a water research tank (approximately 24 feet deep and with a planned finished floor elevation of 1,252 feet) and a partial basement (approximately 17.5 feet deep and with a planned finished floor elevation of 1258.5 feet).

Guernsey intends to support the on-grade portion of the building on drilled pier foundations and the basement and water research tank on shallow foundations.

Maximum loads Unknown

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Item Description

Grading

Based on a planned building finished floor elevation of 1276 feet, we anticipate less than about 3 feet of fill is needed to grade the site, except in the basement and water research tank areas where up to about 18 and 25 feet of excavation will be needed.

Traffic loading

Parking and drive area pavements will also be constructed. We understand that traffic loads will consist of some medium sized service trucks, forklifts for moving heavy equipment, and passenger vehicles. We also understand the light parking and drive area section is for areas expected to receive only car traffic and the heavy parking and drive area section will receive up to 10 full-loaded medium sized service/deliver trucks and/or forklifts per day.

2.2 Site Location and Description

Item Description

Location The proposed project will be located between S.W. 68th and S.W. 66th between Denning and Christian Avenues in Oklahoma City, Oklahoma.

Current ground cover

Vegetation and some concrete sidewalks. Chain link fence, an existing communication tower, and some trees were present during our February 2020 subsurface exploration. The old building and associated gravel surfacing and pavements that once occupied the site and were present during our November 2015 subsurface exploration have since been demolished.

Existing topography Sloped gently downward from west to east

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 and rock 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:

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Description Approximate Depth to Bottom of Stratum Material Encountered Consistency/Density

Stratum 1 13.5 to 23.5 feet Lean clay, fat clay, and shaley lean clay Medium stiff to hard

Stratum 2 Not determined Highly weathered to weathered shale Soft to hard

Note: Existing fill materials with varying amounts of debris were encountered to depths of approximately 1 to 3.5 feet in borings B-7, B-9, B-10, and B-13.

Laboratory tests were conducted on selected soil and bedrock samples and the test results are presented on the boring logs in Appendix A.

3.2 Groundwater

The borings were monitored while drilling and immediately after completing the drilling activities for the presence and level of groundwater. At these times, groundwater was observed at the following depths:

Boring Number Water Level While Drilling Depth (ft.)

Water Level After Drilling Depth (ft.)

B-1 21 21

B-2 None None

B-3 20.5 20.5

B-4 None None B-5 21 20.5

B-6 17 17

B-7 22 22

B-8 None None

B-9 16.5 16.5

B-10 None None

B-11 23 23

B-12 None None

B-13 21 20

B-14 None None

B-15 None None

B-16 None None

B-17 None None

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Boring Number Water Level While Drilling Depth (ft.)

Water Level After Drilling Depth (ft.)

B-18 None None

B-19 None None

B-20 None None

B-21 None None

B-22 None None

B-23 None None

B-24 33.5 20

B-25 28.5 23.5

B-26 25 25

B-27 25 18

Groundwater was not observed in borings B-2, B-4, B-8, B-10, B-12, and B-14 through B-23 for the short duration the borings remained open. This does not necessarily mean borings B-2, B-4, B-8, B-10, B-12, and B-14 through B-23 terminated above the groundwater table or the water levels measured in the remainder of the borings are the actual groundwater levels. Due to the low permeability of the materials encountered in the borings, a relatively long period may be necessary for a groundwater level to stabilize in a borehole. Long term observations in piezometers or observation wells sealed from the influence of surface water are often required to define groundwater levels in materials of this type.

4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION

4.1 Geotechnical Considerations

The borings generally encountered moderately high to high plasticity clays underlain by highly weathered shale and weathered shale bedrock below depths ranging from about 13.5 to 23.5 feet to the boring termination depths.

Based on a planned building finished floor elevation of 1276 feet, we anticipate less than about 3 feet of fill is needed to grade the site, except in the basement and water research tank areas where up to about 18 and 25 feet of excavation will be needed.

Based on the subsurface conditions encountered and the planned finished floor elevations provided, the following foundation recommendations can be made:

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Responsive ■ Resourceful ■ Reliable 5 n The on-grade portion of the building (where there is no basement) can be supported on drilled pier foundations extending into highly weathered shale and/or weathered shale bedrock.

n The water research tank which is approximately 24 feet below grade can be supported on a mat slab foundation bearing on highly weathered shale and/or weathered shale bedrock.

n The basement which is approximately 17.5 feet below grade can be supported either on shallow foundations bearing on highly weathered shale and/or weathered shale bedrock or on shallow foundations bearing on lean concrete backfill extending to highly weathered shale and/or weathered shale bedrock. Alternatively, the basement can be supported on drilled pier foundations extending into highly weathered shale and/or weathered shale bedrock.

The moderately high to high plasticity clays encountered at the site could experience volume changes with variation in subgrade moisture content. To reduce the potential floor slab movement to less than 1 inch, a minimum of 3.5 feet of low volume change soil fill is recommended beneath the floor slab on the on-grade portion of the building (but not needed in the basement and water research tank areas).

To improve long-term support for the proposed pavements, we recommend that the top 8 inches of the pavement subgrade be treated with hydrated lime.

Groundwater was encountered at depths ranging from approximately 16.5 to 33.5 feet at selected boring locations. We recommend installing a groundwater collection system beneath the basement and water research tank slabs to collect and dispose of the water.

Existing fill materials with varying amounts of debris were encountered to depths of approximately 1 to 3.5 feet in borings B-7, B-9, B-10, and B-13. We are not aware that compaction testing was performed during placement of the fill. The depth, composition and compaction of the existing fill materials can vary greatly over relatively small lateral and vertical distances. Because of the potential variability of fill, it will not be possible to accurately predict the amount of fill that may need to be removed and replaced to develop suitable support for the proposed improvements until site grading is underway. The depth and composition of the fill, observed at the discrete boring locations, should only be used for estimating purposes. We encourage the owner to secure a base bid for removing and replacing a specified quantity of the existing fill. The owner should also secure unit rates for adding or deducting quantities from the base bid that includes costs for exporting unsuitable materials and importing approved replacement materials, if required.

Expansive soils are present at this site. This report provides recommendations to help mitigate the effects of soil shrinkage and expansion within the planned building area. However, even if these procedures are followed, some movement and at least minor cracking in the structure

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Geotechnical engineering recommendations for foundations and other earth connected phases of the project are outlined below. The recommendations contained in this report are based upon the results of field and laboratory testing (which are presented in Appendix A), engineering analyses, and our current understanding of the proposed project.

4.2 Earthwork

The following subsections present recommendations for site preparation, subgrade preparation and construction of engineered fill on the project. The recommendations presented for design and construction of earth supported elements including foundations, slabs, and pavements are contingent upon following the recommendations outlined in this section. Grading should extend an appropriate distance beyond the limits of the proposed structure.

Earthwork on the project should be observed and evaluated by Terracon. The evaluation of earthwork should include observation and testing of engineered fill, subgrade preparation, and other geotechnical conditions exposed during the construction of the project.

4.2.1 Site Preparation

Site preparation for the proposed project should include removing vegetation, topsoil, tree stumps, existing slabs/foundations, and other unsuitable materials encountered on-site. The depressions or excavations created during demolition of tree stumps and existing slabs/foundations should be cleaned of loose material and backfilled as outlined in the following paragraphs. Based on our boring information, we anticipate removing approximately 3 to 6 inches of topsoil. Actual removal depths should be determined at the time of construction by a representative of the geotechnical engineer.

4.2.2 Excavation

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 flatter than the OSHA maximum values may be used. As a safety measure, it is recommended that all vehicles and soil piles be kept to a minimum lateral distance from the crest of the slope equal to no less than the slope height. The exposed slope face should be protected against the elements.

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In the upper 20 feet at the site, the overburden soils were generally classified as Soil Type A or Soil Type B and the highly weathered shale and weathered shale were generally classified as stable rock per OSHA guidelines. Sloped excavations greater than 20 feet should be designed by a Professional Engineer. The contractor is solely responsible for designing and constructing stable construction excavations and all excavations should comply with applicable local, state and OSHA excavation standards. Individual borings should be consulted for additional information on the material that could be anticipated in the excavation. Additional soil borings could be performed in areas where more defined soil classification is required. The soils to be penetrated by the proposed excavations may vary significantly across the site. 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.

Based on the groundwater conditions encountered during our subsurface exploration, excavations for the basement and water research tank may encounter groundwater.

Dewatering of the excavations for the basement and water research tank could be accomplished using sumps with pumps.

Groundwater was encountered at depths ranging from approximately 16.5 to 33.5 feet at selected boring locations. We recommend installing a groundwater collection system beneath the basement and water research tank slabs to collect and dispose of the water.

We anticipate that excavations for the basement and water research tank will extend into weathered bedrock. Rock formations that have standard penetration test results of 4 or more inches per 50 blows can usually be excavated with heavy excavation equipment equipped with ripping teeth. Rock formations that have standard penetration test results of 3 inches or less per 50 blows usually require either pneumatic breaking equipment or blasting to remove.

Variations in hardness of rock will likely occur with depth and distance from the borings.

4.2.3 Subgrade Preparation

After site striping and performing any required cuts, but before placing any fill, we recommend the building slab and pavement areas be proofrolled with a loaded, tandem-axle dump truck weighing at least 25 tons (under the observation of Terracon personnel) to locate any soft or unstable zones. The proofrolling should involve overlapping passes in mutually perpendicular directions. Where rutting or pumping is observed during proofrolling, the unstable soils should be overexcavated and replaced with an approved low volume change soil as described in the following sections if it cannot be effectively compacted in-place. Proof-rolling will not be required in areas where highly weathered shale or weathered shale bedrock is exposed. We anticipate isolated unstable areas may be encountered during proofrolling. The amount of unstable soil cannot be determined at this time.

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After a successful proofroll, we recommend scarifying the exposed subgrade soils to a minimum depth of 8 inches in the building slab and pavement areas if fill is required. The scarified soil should be adjusted to a workable moisture content that is at or above its optimum value, as determined by test method ASTM D698 (standard Proctor), prior to being compacted to at least 95 percent of its maximum dry density. The scarification and moisture conditioning process is important to reducing the future subgrade volume change and should be observed and documented during construction. Scarification and moisture conditioning will not be required in the basement and water research tank areas.

4.2.4 Fill Material Requirements

All fill required to develop the design subgrade elevation should be an approved material that is free of organic matter and debris as outlined in the following table.

Fill Type1 Acceptable Location for Placement Imported Low Volume Change Soils

(Cohesive Clay Materials with LL≤40 and 5≤PI≤15) All locations and elevations

On-Site Soils (with 5≤PI≤35) Pavement and non-structure areas2

1. Prior to any filling operations, samples of the proposed borrow and on-site materials should be obtained for laboratory Atterberg Limits and moisture-density testing. The tests will provide a basis for material acceptance and evaluation of fill compaction by in-place density testing. A qualified soil technician should perform sufficient in-place density tests during the filling operations to evaluate that proper levels of compaction, including dry unit weight and moisture content, are being attained. Controlled, compacted fill should consist of approved materials free of organic matter and debris and contain a maximum rock size of 3 inches. The proposed fill materials should be approved by the geotechnical engineer prior to placement.

2. Provided the top 8 inches of the pavement subgrade is modified with hydrated lime as discussed in section 4.7 Pavements.

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.

4.2.5 Fill Placement and Compaction Requirements

Recommended compaction and moisture content criteria for engineered fill materials are as follows:

Item Description

Fill Lift Thickness 8-inches or less in loose thickness.

Compaction Requirements1

■ At least 95% for fill placed from finished grade to a depth of 5 feet below finished grade.

■ At least 100% for fill placed at a depth greater than 5

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Item Description feet below finished grade.

■ At least 98% for modified depth of pavement subgrade

Moisture Content1

■ Workable water content that is at or above its optimum value for fill placed from finished grade to a depth of 5 feet below finished grade.

■ Within 2% of its optimum value for fill placed at a depth greater than 5 feet below finished grade.

■ Within 2% of its optimum value

1. Maximum dry density and optimum water content as determined by test method ASTM D698

(standard Proctor).

4.2.6 Grading and Drainage

Effective drainage should be developed during construction and maintained throughout the life of the development. Infiltration of water into utility trenches or foundation excavations should be prevented during construction. Planters and other surface features that could retain water in areas adjacent to the building or pavements should be sealed or eliminated. In areas where sidewalks or paving do not immediately adjoin the structure, we recommend that protective slopes be provided with a minimum grade of approximately five percent for at least 10 feet from perimeter walls. Backfill against footings, exterior walls, and in utility and sprinkler line trenches should be well compacted and free of all construction debris to reduce moisture infiltration.

Downspouts, roof drains or scuppers should discharge in a manner that carries the water several feet away from the building when the ground surface adjacent to the structure is not protected by exterior slabs or paving. Sprinkler systems should not be installed within five feet of foundation walls. Landscape irrigation adjacent to the foundation systems should be minimized or eliminated.

4.2.7 Utility Trench Backfill

All trenches created for utility access under the building should be effectively sealed to restrict water intrusion and flow along the trenches. We recommend using a clay soil to construct an effective clay trench plug that extends at least 5 feet out from the face of the building. The clay should have a minimum plasticity index (PI) of 15 and be placed in controlled lifts not exceeding 9 inches in loose thickness so as to surround the utility line and fill the trench. Each lift of clay backfill should be compacted following recommendations provided in section 4.2.5 Fill Placement and Compaction Requirements.

4.2.8 Corrosion Potential

The table below lists the results of laboratory pH and/or soluble sulfate testing. The values may be used to estimate potential corrosive characteristics of the on-site materials with respect to contact with the various underground materials which will be used for project construction.

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Boring Sample Depth (feet) pH Soluble Sulfate (mg/kg)

B-1, B-3 & B-5 23.5 – 30 N/A <200

B-7, B-9 & B-11 13.5 – 20 N/A <200

B-13, B-15 & B-16 6 – 10 N/A <200

B-21, B-22 & B-23 1 – 5 N/A <200

B-24 1 – 10 8.93 39

B-25 1 – 10 8.18 30

B-27 13.5 – 35 8.82 58

The measured soluble sulfate contents of the samples were less than 200 mg/kg. These levels should have negligible effect on exposed concrete according to ACI guidelines. Type I portland cement concrete may be used.

4.3 Foundations

4.3.1 Shallow Foundation Design Recommendations

The basement which is approximately 17.5 feet below grade can be supported either on shallow foundations bearing on highly weathered shale and/or weathered shale bedrock or on shallow foundations bearing on lean concrete backfill extending to highly weathered shale and/or weathered shale bedrock. The water research tank which is approximately 24 feet below grade can be supported on a mat slab foundation bearing on highly weathered shale and/or weathered shale bedrock.

Description Value

Foundation Type

■ Shallow spread footings for the basement

■ Mat slab for the water research tank

Bearing Material1, 2 Undisturbed, highly weathered shale and/or weathered shale

Net Allowable Bearing Pressure3 4,000 psf

Uplift Resistance

The buoyant force could be counteracted by a thicker mat slab foundation and/or widening the mat slab foundation laterally beyond the edge of the walls and assuming a total soil density not exceeding 125 pcf and a submerged soil density not exceeding 62 pcf for engineered backfill placed above the mat slab foundation

Estimated Modulus of Subgrade Reaction4 150 pci

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Minimum Width Columns: 30 inches Walls: 16 inches

Minimum Embedment Depth Below Finished Grade5 30 inches

Frost Depth Approximately 18 inches

Estimated Total Settlement Approximately 1/2 inch

Estimated Differential Settlement Less than 1/2 inch

Allowable Passive Pressure6 150 pcf (equivalent fluid pressure)

Allowable Coefficient of Sliding Friction7 0.25

1. In areas where highly weathered shale and/or weathered shale bedrock are not present at the base of the planned foundation excavation, the excavation should be extended deeper to suitable highly weathered shale and/or weathered shale, and the foundation could bear at the lower level or at a higher elevation on lean concrete backfill placed in the excavation. This is illustrated on the sketch below.

2. Unsuitable or soft soils should be over-excavated and replaced. We recommend evaluating the bearing materials by performing dynamic cone penetrometer (DCP) tests in the foundation excavations. When DCP tests are used to evaluate the suitability of the bearing materials, they should be performed at the base of the footing excavation and at every 12 inches to a depth equal to the width of isolated footings or two times the width of continuous footings. However, in no case should the suitability of the bearing materials be evaluated to a depth that is less than 3 feet below the base of foundations. If unsuitable soil is present, the excavation should be extended until suitable material is encountered. Foundations could bear on lean concrete backfill in the excavations as outlined above.

3. The recommended net allowable bearing pressure is the pressure at the base of the foundation in excess of the adjacent overburden pressure.

4. Modulus of subgrade reaction is an estimated value based upon our experience with the subgrade condition. This value is based on a 30-inch diameter plate. For large area loads, the modulus of subgrade reaction would be lower.

5. Minimum depth applies to foundations along the building perimeter and in unheated areas.

Minimum depth will provide frost protection and reduce the potential for moisture variation

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6. With an applied safety factor of 2. This value assumes that the foundations are poured directly against undisturbed native materials or that backfills placed around formed foundations are compacted following the recommendations provided in this report. Unless pavements or on-grade slabs are provided up to and above the foundations, the allowable passive pressure should be disregarded to a depth of 2.5 feet below the final grade.

7. With an applied safety factor of 2.

4.3.2 Shallow Foundation Construction Considerations

Care should be taken to prevent wetting or drying of the exposed bearing materials during construction. Any extremely wet or dry material, or any loose or disturbed material in the bottom of the foundation excavations, should be removed prior to placing concrete. The potential for wetting or drying of the bearing materials can be reduced by placing concrete as soon as possible after completing the foundation excavation and evaluating the bearing strata.

To protect the subgrade from excessive wetting and disturbance by construction equipment and to provide a stable working surface for construction, we recommend installing a granular working base consisting of at least 6 inches of ODOT Type “A” aggregate base on the bottom of the excavation for water research tank. The excavation bottom should be sloped to drain surface water to the excavation perimeter where it can be collected and removed.

Foundation excavations should be observed by the geotechnical engineer. If the soil conditions encountered differ significantly from those presented in this report, supplemental recommendations will be required.

4.3.3 Drilled Pier Foundation Design Recommendations

The on-grade portion of the building (where there is no basement) and the basement (which is approximately 17.5 feet below grade) can be supported on drilled pier foundations extending into highly weathered shale and/or weathered shale bedrock.

Description Value

Foundation Type Drilled piers

Bearing Material1 Highly weathered shale and/or weathered shale that were encountered at depths of approximately 13.5 to

23.5 feet below the existing grade

Minimum Embedment

■ 2 feet into approved highly weathered shale and/or weathered shale

■ Drilled piers located near the excavations for the basement or water research tank should bear at least 2 feet below the bottom of the excavations for the basement or water research tank

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Description Value

Net Allowable Bearing Pressure 15,000 psf

Maximum Allowable Skin Friction2 1,500 psf

Minimum Shaft Diameter3 24 inches

Minimum Grade Beam Embedment Depth Below Finished Grade4 30 inches

Minimum Void Space Beneath Grade Beam5 4 inches

Estimated Total Settlement Approximately 1/2 inch

Estimated Differential Settlement Less than 1/2 inch

1. Due to the variations in the quality and depth of the highly weathered shale and weathered shale bearing strata between borings, the geotechnical engineer or his representative should be present during pier drilling to verify that suitable highly weathered shale and/or weathered shale are adequately penetrated.

2. Use skin friction for the portion of the drilled pier that penetrates the highly weathered shale and/or weathered shale. Skin friction may be used to resist both upward and downward axial forces.

3. Assume that enough steel reinforcement is used to provide adequate structural integrity.

4. Grade beams should be structurally connected to the top of the piers.

5. Excavation for grade beams should be free of loose material and protection should be provided to prevent future filling of the void by sloughing soils.

4.3.4 Drilled Pier Foundation Construction Considerations

The drilling contractor should anticipate the need for a heavy-duty rig equipped with a rock auger to penetrate the highly weathered shale and weathered shale bedrock. We do not expect temporary casing will be needed to prevent caving of the excavation sides; however, the final determination should be made at the time of construction.

Groundwater was encountered in borings B-1, B-3, B-5, B-6, B-7, B-9, B-11, B-13, and B-24 through B-27 at depths ranging from approximately 16.5 to 33.5 feet at the time of this investigation; therefore, we expect dewatering could be needed to facilitate drilled pier construction. However, the need for dewatering will depend on the pier length and actual groundwater conditions at the time of construction. Prior to placing concrete, water or sloughed material should be removed from the base of the drilled piers. If water is encountered and it cannot be removed, the concrete should be placed using a tremie pipe or pumped from the bottom of the pier excavation to the top, displacing the water to the surface. To facilitate pier construction, concrete should be on-site and ready for placement as pier excavations are completed. In no event should a pier excavation be allowed to remain open overnight.

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4.4 Seismic Considerations

Description Value 2009 International Building Code Site Classification (IBC) C Note: In general accordance with the 2009 International Building Code, Table 1613.5.2. The 2009 International Building Code (IBC) uses a site soil profile determination extending to a depth of 100 feet for seismic site classification. The current scope does not include the 100 foot soil profile determination. Borings extended to a maximum depth of 40 feet. This seismic site class definition considers that similar material continues below the maximum depth of the subsurface exploration. Additional exploration to deeper depths would be necessary to confirm the conditions below the current depth of exploration.

4.5 Floor Slab Design Recommendations

The moderately high to high plasticity clays encountered at the site could experience volume changes with variation in subgrade moisture content. To reduce the potential floor slab movement to less than 1 inch, a minimum of 3.5 feet of low volume change soil fill is recommended beneath the floor slab on the on-grade portion of the building (but not needed in the basement and water research tank areas). To further reduce the potential for slab movements, a greater thickness of low volume change fill could be placed beneath the slab.

Description Value

Interior floor system Slab-on-grade

Floor slab support1

■ At least 3.5 feet of low volume change soils placed and compacted in accordance with section 4.2 Earthwork beneath the floor slab on the on-grade portion of the building

■ Overexcavation of the on-site soils and replacement with low volume change soils are not required in the basement and water research tank areas

Estimated Modulus of Subgrade Reaction2, 3

■ 100 pci on soil subgrade (on-grade portion of the building and basement)

■ 125 pci on a 6-inch thickness of ODOT Type “A” aggregate over soil subgrade (on-grade portion of the building and basement)

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Description Value

1. Floor slabs should be structurally independent of building foundations and walls to reduce the possibility of floor slab cracking caused by differential movements between the slab and foundations.

2. Modulus of subgrade reaction is an estimated value based upon our experience with the subgrade condition, the requirements noted in section 4.2 Earthwork, and the floor slab support as noted in this table. It is provided for point loads. For large area loads the modulus of subgrade reaction would be lower.

3. We recommend the floor slab in areas where heavy loads are expected be supported on a 6-inch thickness of ODOT Type “A” aggregate base meeting the requirements of Section 703.01.

The purpose of this layer is to help distribute concentrated heavy loads and provide a stable working surface for casting the floor slab. The aggregate base should be adjusted to a workable moisture content prior to being compacted to at least 98 percent of its maximum dry density as determined by test method ASTM D698 (standard Proctor). The aggregate base layer could be considered part of the low volume change soil zone.

In areas of exposed concrete, control joints should be saw cut into the slab after concrete placement in accordance with ACI Design Manual, Section 302.1R-37 8.3.12 (tooled control joints are not recommended). Additionally, dowels should be placed at the location of proposed construction joints. To control the width of cracking (should it occur) continuous slab reinforcement should be considered in exposed concrete slabs.

Positive separations and/or isolation joints should be provided between slabs and all foundations, columns or utility lines penetrating the slab to allow independent movement.

Interior trench backfill placed beneath slabs should be compacted in accordance with recommendations outlined in section 4.2 Earthwork. Other design and construction considerations, as outlined in the ACI Design Manual, Section 302.1R are recommended.

The use of a vapor retarder or barrier should be considered beneath concrete slabs on grade that will be covered with wood, tile, carpet or other moisture sensitive or impervious coverings, or when the slab will support equipment sensitive to moisture. When conditions warrant the use of a vapor retarder, the slab designer and slab contractor should refer to ACI 302 and ACI 360 for procedures and cautions regarding the use and placement of a vapor retarder/barrier.

4.6 Lateral Earth Pressures

Walls with unbalanced backfill levels on opposite sides should be designed for earth pressures at least equal to those indicated in the following table. Earth pressures will be influenced by structural design of the walls, conditions of wall restraint, methods of construction and/or compaction and the strength of the materials being restrained. Two wall restraint conditions are shown. Active earth pressure is commonly used for design of free-standing cantilever retaining walls and assumes wall movement. The "at-rest" condition assumes no wall rotation. The

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Responsive ■ Resourceful ■ Reliable 16 recommended design lateral earth pressures do not include a factor of safety and do not provide for possible hydrostatic pressure on the walls.

EARTH PRESSURE COEFFICIENTS

EARTH

PRESSURE

CONDITIONS

COEFFICIENT FOR

BACKFILL TYPE

EQUIVALENT

FLUID PRESSURE

(pcf)

SURCHARGE

PRESSURE, P1

(psf)

EARTH

PRESSURE, P2

(psf)

Active (Ka) Granular - 0.33 Lean Clay - 0.42

(0.33)S (0.42)S

(45)H (55)H

At-Rest (Ko) Granular - 0.50 Lean Clay - 0.59

(0.50)S (0.59)S

(65)H (75)H

Passive (Kp) Granular - 3.0 Lean Clay - 2.4

Conditions applicable to the above table include:

n For active earth pressure, wall must rotate about base, with top lateral movements

0.002 Z to 0.004 Z, where Z is wall height.

n For passive earth pressure, wall must move horizontally to mobilize resistance.

n Uniform surcharge, where S is surcharge pressure.

n In-situ soil backfill weight a maximum of 125 pcf.

n Horizontal backfill, compacted following recommendations provided in this report.

n Loading from heavy compaction equipment not included.

n No groundwater acting on wall.

For active pressure - Movement (0.002 Z to 0.004 Z)

Finished Grade S For at-res t pressure - No

Movement Assumed

H (ft)

Z P2

P1

Finished Grade

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n Ignore passive pressure in frost zone (18 inches).

Backfill placed against structures should consist of granular soils or low plasticity cohesive soils (PI≤15). For values in the above table to be valid, the backfill must extend out and up from the base of the wall at an angle of at least 45 and 60 degrees from vertical for the at-rest and passive cases, respectively. Additionally, the backfill must extend out from the base of the wall at an angle of at least 30 degrees from vertical for the active case.

We recommend installing an exterior perimeter drain system along below-grade walls. The exterior perimeter drains should be installed at the foundation level as shown on the adjacent figure and described in the following notes.

n Granular backfill should be clean, free-draining sand or crushed stone.

n Perforated pipe should be rigid PVC, sized to transport the expected water.

n Perforated pipe should be surrounded by at least 4 inches of ASTM C-33 No.

57 stone or equivalent with the stone and pipe encased in an approved filter fabric to restrict the migration of fines into the drain system.

n Exterior ground surface should consist of a 12-inch compacted clay cap or pavement section sloped to drain from building.

If adequate drainage is not possible, then combined hydrostatic and lateral earth pressures should be calculated for lean clay backfill using an equivalent fluid weighing 90 and 100 pcf for active and at-rest conditions, respectively. For granular backfill, an equivalent fluid weighing 85 and 95 pcf should be used for active and at-rest, respectively. These pressures do not include the influence of surcharge, equipment or floor loading, which should be added. Heavy equipment should not operate within a distance closer than the exposed height of below-grade walls to prevent imposing lateral pressures larger than those provided.

4.7 Pavements

The subgrade and any fill required in the pavement areas should be prepared and placed in accordance with section 4.2 Earthwork.

We expect the subgrade soils in the pavement areas will generally consist of moderately high to

Gra n u la r Ba c kf ill

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Responsive ■ Resourceful ■ Reliable 18 high plasticity cohesive soils. These soils will tend to cause trafficability problems during construction when the subgrade gets wet and, in their existing condition, do not appear suitable for the long-term support of pavements. To reduce potential trafficability problems and strength loss, and to improve the long-term subgrade support, we recommend that the top 8 inches of the subgrade be modified with hydrated lime. Based on past experience with soils similar to those present at the site, we estimate 5 to 7 percent hydrated lime will be needed to adequately modify the on-site soils. The actual percentage of additive should be determined at the time of construction by the geotechnical engineer. The lime should be blended into the subgrade and allowed to cure for 48 to 72 hours before being remixed and compacted. Before compaction, the modified soil zone should be adjusted to within 2 percent of the material’s optimum moisture as determined by test method ASTM D698. After conditioning the soil to the required moisture content, the modified subgrade should be compacted to at least 98 percent of the material’s maximum dry density as determined by test method ASTM D698.

We understand that traffic loads will consist of some medium sized service trucks, forklifts for moving heavy equipment, and passenger vehicles. Two pavement section alternatives have been provided. We also understand the light parking and drive area section is for areas expected to receive only car traffic and the heavy parking and drive area section will receive up to 10 full-loaded medium sized service/deliver trucks and/or forklifts per day. The heavy truck drive loading conditions were converted to the corresponding 18-kip equivalent single-axle loads (ESAL) and were used in the design of the recommended pavement sections. If the traffic loading expected is different than presented, we should be provided the traffic information and allowed to review these pavement sections. The owner/user should consider placing signs at entryways to deter heavy trucks from light duty pavement areas.

4.7.1 Pavement Design Recommendations

Minimum Pavement Recommendations 1

Light-Duty Parking Heavy-Duty Parking and Drive Section I Portland Cement Concrete (3,500 psi, Air Entrained)

5.0” Concrete 8.0” Modified Subgrade

7.0” Dowel Jointed Concrete2

8.0” Modified Subgrade

Section II Full Depth Asphaltic Concrete

2.0” Type “B” Asphaltic Concrete 3.0” Type “A” Asphaltic Concrete 8.0” Modified Subgrade

1. All materials should meet the current Oklahoma Department of Transportation (ODOT) Standard Specifications for Highway and Bridge Construction. For asphaltic concrete, refer to ODOT 1999 Specifications.

2. Appropriately sized and spaced dowel bars should be installed at all expansion and construction joints.

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Minimum Pavement Recommendations 1

Light-Duty Parking Heavy-Duty Parking and Drive NOTE: We recommend that reinforced concrete pads be provided in front of and beneath trash receptacles. The dumpster trucks should be parked on the rigid concrete pavement when the trash receptacles are lifted. The concrete pads should be a minimum of 7 inches thick and properly reinforced.

4.7.2 Pavement Construction Considerations

The pavement surfacing should be sloped to provide rapid drainage of surface water. Water should not be allowed to pond on or adjacent to these grade-supported slabs, since this could saturate the subgrade and contribute to premature pavement or slab deterioration.

The pavement sections represent minimum recommended thicknesses and, as such, periodic maintenance should be anticipated. Therefore, preventive maintenance should be planned and provided for through an on-going pavement management program. Maintenance activities are intended to slow the rate of pavement deterioration and to preserve the pavement investment.

Maintenance consists of both localized maintenance (e.g. crack and joint sealing and patching) and global maintenance (e.g. surface sealing). Preventive maintenance is usually the priority when implementing a pavement maintenance program. Additional engineering observation is recommended to determine the type and extent of a cost-effective program. Even with periodic maintenance, some movements and related cracking may still occur and repairs may be required.

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

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Responsive ■ Resourceful ■ Reliable 20 environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken.

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 outlined 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

EXHIBIT A-2: BORING LOCATION PLAN

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MAP 2 1 1X17 LANDSCAPE

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES

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Field Exploration Description

Twenty-three test borings were drilled at the site between November 18 and 20, 2015. Four supplemental test borings were drilled on February 19 and 20, 2020. The borings were drilled to depths ranging from approximately 5 to 40 feet below the ground surface at the approximate locations shown on the attached Boring Location Plan, Exhibit A-2.

Terracon personnel provided the boring layout. Coordinates were obtained with a handheld GPS unit and approximate elevations were estimated from the plan contours provided by Guernsey (where possible). The ground surface elevations at the boring locations ranged from approximately 1,274 to 1,277 feet. We rounded the elevations on the boring logs to the nearest foot. Consider the location and elevation of the borings accurate only to the degree implied by the methods used to make these measurements.

All-terrain, rotary drill rigs equipped with continuous flight augers were used to advance the boreholes. Representative samples were obtained by the split-barrel sampling procedure.

The split-barrel sampling procedure uses a standard 2-inch O.D. split-barrel sampling spoon that is driven into the bottom of the boring with a 140-pound drive hammer falling 30 inches.

The number of blows required to advance the sampling spoon the last 12 inches, or less, of a typical 18-inch sampling interval or portion thereof, is recorded as the standard penetration resistance value, N. The N value is used to estimate the consistency of cohesive soils and the hardness of sedimentary bedrock. The sampling depths, penetration distances, and the N values are reported on the boring logs. The samples were tagged for identification, sealed to reduce moisture loss and returned to the laboratory for further examination, testing and classification.

An automatic Standard Penetration Test (SPT) drive hammer was used to advance the split-barrel sampler.