03215238 Replace Friendship GEO TECH Report.pdf

Geotechnical Engineering Report

Replace Friendship House Oklahoma City, Oklahoma

December 3, 2021 Terracon Project No. 03215238

Prepared for:

Spur Design

Oklahoma City, Oklahoma

Prepared by:

Terracon Consultants, Inc.

Oklahoma City, Oklahoma

December 3, 2021

Spur Design 312 SW 25th Street Oklahoma City, Oklahoma 73109

Attn: Ms. Jennifer Knight Project Manager/Senior Architect P: (405) 842 6100 E: Jennifer.Knight@spur-design.com

Re: Geotechnical Engineering Report Replace Friendship House NW 32nd Street and N Military Avenue Oklahoma City, Oklahoma Terracon Project No. 03215238

Dear Ms. Knight:

We have completed a subsurface exploration and Geotechnical Engineering evaluation for the above referenced project. This study was performed in general accordance with Terracon Proposal No. P03215238 dated September 21, 2021. This report presents the findings of the subsurface exploration and provides geotechnical recommendations concerning earthwork and the design and construction of foundations, floor slabs, and pavements for the proposed project.

We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this report or if we may be of further service, please contact us.

Sincerely, Terracon Consultants, Inc.

Cert. Of Auth. #CA-4531 exp. 6/30/23

Colette Nelson Norman Tan, P.E.

Engineering Assistant Oklahoma No. 23083

Responsive Resourceful Reliable 1

INTRODUCTION

SITE CONDITIONS

PROJECT DESCRIPTION

GEOTECHNICAL CHARACTERIZATION

GEOTECHNICAL OVERVIEW

EARTHWORK

SHALLOW FOUNDATIONS

SEISMIC CONSIDERATIONS

FLOOR SLABS

LATERAL EARTH PRESSURES

PAVEMENTS

GENERAL COMMENTS

ATTACHMENTS

Note: This report was originally delivered in a web-based format. Orange Bold text in the report indicates a referenced section heading. The PDF version also includes hyperlinks which direct the reader to that section and clicking on the GeoReport logo will bring you back to this page. For more interactive features, please view your project online at client.terracon.com.

ATTACHMENTS

EXPLORATION AND TESTING PROCEDURES

SITE LOCATION AND EXPLORATION PLANS

EXPLORATION RESULTS

SUPPORTING INFORMATION

Note: Refer to each individual Attachment for a listing of contents.

Responsive Resourceful Reliable 1

Replace Friendship House

NW 32nd Street and N Military Avenue Oklahoma City, Oklahoma

Terracon Project No. 03215238 December 3, 2021

This report presents the results of our subsurface exploration and geotechnical engineering services performed for the proposed new Friendship House to be located at NW 32nd Street and N Military Avenue in Oklahoma City, Oklahoma. The purpose of these services is to provide information and geotechnical engineering recommendations relative to:

Subsurface soil and rock conditions Foundation design and construction

Groundwater conditions Floor slab design and construction

Site preparation and earthwork Seismic site classification per IBC

Demolition considerations Lateral earth pressures

Excavation considerations Pavement design and construction

The geotechnical engineering Scope of Services for this project included the advancement of three test borings to a depth of approximately 29 feet below existing site grades.

Maps showing the site and boring locations are shown in the Site Location and Exploration Plan sections, respectively. The results of the laboratory testing performed on soil samples obtained from the site during the field exploration are included on the boring logs in the Exploration Results section.

The following description of site conditions is derived from our site visit in association with the field exploration.

Item Description

Parcel Information

The project is located at NW 32nd Street and N Military Avenue in Oklahoma City, Oklahoma.

See Site Location Latitude/Longitude: 35.50267, -97.5319 (approximate)

Replace Friendship House Oklahoma City, Oklahoma December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable 2

Item Description Current Ground Cover and Existing Improvements

Existing buildings, sidewalks, fences, light poles, trees, grass, stairs, overhead power lines, parking and drive areas

Existing Topography Relatively flat to gently sloping with about 5 feet of maximum elevation difference between the borings throughout the site.

Our initial understanding of the project was provided in our proposal and was discussed during project planning. Our final understanding of the project conditions is as follows:

Item Description

Information Provided Preliminary design plans, project location plans, a statement of work and other supporting documents were provided by Spur Design on September 17, 2021.

Proposed Structure The project includes a two-story building with a basement with a footprint of about 11,566 square feet. Work also includes site landscaping, site preparation, and a parking lot for ten cars with one handicap spot.

Maximum Loads Columns: 60 kips Walls: 2 to 3 kips per linear foot (klf) Slabs: 125 pounds per square foot (psf)

Grading/Slopes A grading plan was not provided at the time of this proposal.

Below-Grade Structures A basement is planned for the project.

Free-Standing Retaining Walls None

Pavements

Paved driveway and parking will be constructed on the parcel.

We assume both rigid (concrete) and flexible (asphalt) pavement sections should be considered.

Anticipated traffic is as follows:

Light Duty:

Autos/light trucks: 20 vehicles per day Heavy Duty: (in addition to autos/light trucks) Light delivery and trash collection vehicles: 10 vehicles per week

We have developed a general characterization of the subsurface conditions based upon our review of the subsurface exploration, laboratory data, geologic setting and our understanding of

December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable 3 the project. This characterization, termed GeoModel, forms the basis of our geotechnical calculations and evaluation of site preparation and foundation options. Conditions encountered at each exploration point are indicated on the individual logs. The individual logs can be found in the Exploration Results section and the GeoModel can be found in the Figures section of this report.

As part of our analyses, we identified the following model layers within the subsurface profile. For a more detailed view of the model layer depths at each boring location, refer to the GeoModel.

Model Layer Layer Name General Description 1 Fat Clay Fat Clay (CH)

2 Lean Clay Lean Clay (CL), Lean Clay with Sand (CL) 3 Bedrock 1 Weathered Sandstone

4 Bedrock 2 Weathered Shale

The boreholes were observed while drilling and after completion for the presence and level of groundwater. The water levels observed in the boreholes can be found on the boring logs in Exploration Results, and are summarized below.

Boring Number Approximate Depth to

Groundwater While Drilling (feet) Approximate Depth to

Groundwater After Drilling (feet)

B-1 28.5 ---

1. Below ground surface

Groundwater was not observed in the remaining borings while drilling, or for the short duration the borings could remain open. However, this does not necessarily mean the borings terminated above groundwater, or the water levels summarized above are stable groundwater levels. Due to the low permeability of the soils encountered in the borings, a relatively long period may be necessary for a groundwater level to develop and 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.

Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall, runoff and other factors not evident at the time the borings were performed. Therefore, groundwater levels during construction or at other times in the life of the structure may be higher or lower than the levels indicated on the boring logs. The possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project.

December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable 4

Moderate to high plasticity clay soils were encountered on site. These soils will have a relatively high shrink/swell potential that can adversely affect lightly loaded on-grade floor slabs.

Recommendations are provided to reduce slab-on-grade heaving due to potential volume changes in the clays during cycles of wetting and drying. The Floor Slabs section addresses slab-on-grade support of the building. Additional site preparation recommendations, including subgrade improvement and fill placement, are provided in the Earthwork section. The Shallow Foundations section addresses support of the building bearing on undisturbed native soils or tested and approved engineered fill.

The Pavements section contains recommendations for both rigid (PCC) and flexible (AC) pavement sections for the paved sections. Subgrade modification of the on-site soils with hydrated lime or placing a layer of aggregate beneath the pavements is recommended to improve long-term support for new pavements.

Expansive soils are present on this site. This report provides recommendations to help mitigate the effects of soil shrinkage and expansion. However, even if these procedures are followed, some movement and (at least minor) cracking in the structure should be anticipated. The severity of cracking and other damage such as uneven floor slabs will probably increase if modification of the site results in excessive wetting or drying of the expansive soils. Eliminating the risk of movement and distress may not be feasible, but it may be possible to further reduce the risk of movement if significantly more expensive measures are used during construction. Some of these options are discussed in this report such as complete replacement of expansive soils or a structural slab.

The General Comments section provides an understanding of the report limitations.

The following sections provide recommendations for use in the preparation of specifications for the work. Recommendations include critical quality criteria, as necessary, to render the site in the state considered in our geotechnical engineering evaluation for foundations, floor slabs, and pavements.

Site preparation should include removing any remaining trees, vegetation, topsoil, remaining foundations, floor slabs and any other unsuitable surface materials from the areas of new construction. The depressions or excavations created during demolition of the existing buildings should be cleaned of loose material and backfilled as outlined in the following paragraphs. Actual

December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable 5 removal depths should be determined at the time of construction by a representative of the geotechnical engineer.

After removing the vegetation, topsoil and performing any required cuts, but before placing any fill or constructing the floor slab, we recommend undercutting the building area to allow construction of a minimum 2.5 feet thickness of low plasticity cohesive fill below the design finish subgrade elevation. The zone of fill compacted to meet this criteria should extend beyond the building footprint at least 1 foot laterally for each foot of fill required to develop design grade.

After performing any required undercut, but before placing any fill, we recommend the exposed soils 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 plasticity cohesive soil as described in the following sections if it cannot be effectively compacted in-place.

After a successful proofroll, we recommend scarifying the exposed subgrade soils to a minimum depth of 8 inches in the building area, and in the pavement area 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.

All fill required to develop the design subgrade elevation should be an approved cohesive material that is free of organic matter and debris. Earthen materials used for fill should meet the following material property requirements:

Soil Type USCS Classification Acceptable Location for Placement

Low Plasticity Cohesive Soils- Liquid Limit less than 40 Plasticity index between 5 and 15 With at least 60% passing #200 sieve

CL, CL-ML All locations and elevations

On-Site Soils CH, CL Pavement and non-structure areas meeting the requirements of Section 703.01 GW, GP All locations and elevations

December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable 6

Soil Type USCS Classification Acceptable Location for Placement

1. Fill should consist of approved materials free of organic matter and debris. Frozen material should not be used, and fill should not be placed on a frozen subgrade. A sample of each material type should be submitted to the Geotechnical Engineer for evaluation prior to use on this site.

2. CH soils should not be used within 2.5 feet of finished grade in building area. Some of the on-site soils appear suitable for use as low plasticity cohesive soil. However, this should be verified during construction by further testing.

3. Provided the top 8 inches of the pavement subgrade is modified with hydrated lime or at least 6 inches of ODOT Type A Aggregate is placed, as noted in Pavements.

4. Recycled aggregate is not recommended.

Structural and general fill should meet the following compaction requirements.

Item Description

Maximum Lift Thickness

8 inches or less in loose thickness when heavy, self-propelled compaction equipment is used 4 to 6 inches in loose thickness when hand-guided equipment (i.e.

jumping jack or plate compactor) is used

Minimum Compaction Requirements At least 95%

Water Content Range Low Plasticity Cohesive Soil: Workable moisture content that is at or above its optimum value ODOT Type A Aggregate: Workable moisture content

1. Maximum density and optimum water content as determined by the standard Proctor test (ASTM D 698).

For low permeability subgrades, utility trenches are a common source of water infiltration and migration. 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

Proctor dry density, ASTM 698, at a minimum moisture content that is above its optimum value.

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

December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable 7 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 5 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 5 feet of foundation walls. Landscape irrigation adjacent to the foundation systems should be minimized or eliminated.

Upon completion of filling and grading, care should be taken to maintain the subgrade water content prior to construction of floor slabs. Construction traffic over the completed subgrades should be avoided. The site should also be graded to prevent ponding of surface water on the prepared subgrades or in excavations. Water collecting over or adjacent to construction areas should be removed. If the subgrade freezes, desiccates, saturates, or is disturbed, the affected material should be removed, or the materials should be scarified, moisture conditioned, and recompacted prior to floor slab construction.

As a minimum, excavations should be performed in accordance with OSHA 29 CFR, Part 1926, dices, and in accordance with any applicable local, and/or state regulations.

Construction site safety is the sole responsibility of the contractor who controls the means, methods, and sequencing of construction operations. Under no circumstances shall the information provided herein be interpreted to mean Terracon is assuming responsibility for construction site safety, or the contractor's activities; such responsibility shall neither be implied nor inferred.

We anticipate that excavations for the basement 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 can occur with depth and distance from the borings.

Grading in the form of ditches or berms should be provided around the perimeter of the excavations to divert surface runoff and soil from entering into the excavated areas.

December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable 8

The earthwork efforts should be monitored under the direction of the Geotechnical Engineer.

Monitoring should include documentation of adequate removal of vegetation and topsoil, proofrolling, and mitigation of areas delineated by the proofroll to require mitigation.

Each lift of compacted fill should be tested, evaluated, and reworked, as necessary, until approved by the Geotechnical Engineer prior to placement of additional lifts. Each lift of fill should be tested for density and water content at a frequency of at least one test for every 2,500 square feet of compacted fill in the building areas and 5,000 square feet in pavement areas. One density and water content test should be performed for every 50 linear feet of compacted utility trench backfill.

In areas of foundation excavations, the bearing subgrade should be evaluated under the direction of the Geotechnical Engineer. If unanticipated conditions are encountered, the Geotechnical Engineer should prescribe mitigation options.

In addition to the documentation of the essential parameters necessary for construction, the continuation of the Geotechnical Engineer into the construction phase of the project provides the continuity to maintain the Geotechnical Engineer assessing variations and associated design changes.

If the site has been prepared in accordance with the requirements noted in Earthwork, the following design parameters are applicable for shallow foundations.

Item Description

Maximum Net Allowable Bearing Pressure 2,500 psf (foundations bearing within native undisturbed soils or tested and approved new fill)

Required Bearing Stratum Native undisturbed soils or tested and approved new fill

Minimum Foundation Width Columns: 30 inches Continuous: 18 inches

Allowable Passive Resistance

(equivalent fluid pressures) 150 pcf

Allowable Coefficient of Sliding Friction 0.2

Minimum Embedment below

Finished Grade

Exterior footings in unheated areas: 30 inches

Interior footings in heated areas: 12 inches

December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable 9

Item Description Estimated Total Settlement from Structural Loads Less than 1 inch

Estimated Differential Settlement About 1/2 of total settlement

1. The maximum net allowable bearing pressure is the pressure in excess of the minimum surrounding overburden pressure at the footing base elevation. An appropriate factor of safety has been applied. These bearing pressures can be increased by 1/3 for transient loads unless those loads have been factored to account for transient conditions. Values assume that exterior grades are no steeper than 20% within 10 feet of structure.

2. Values provided are for maximum loads noted in Project Description.

3. Unsuitable or soft soils should be over-excavated and replaced per the recommendations presented in the

Earthwork.

4. With an applied safety factor of 2. Use of passive earth pressures require the sides of the excavation for the spread footing foundation to be nearly vertical and the concrete placed neat against these vertical faces or that the footing forms be removed and compacted structural fill be placed against the vertical footing face. Unless pavements or on-grade slabs are provided up to and above the footings, the allowable passive pressure should be disregarded to a depth of 2.5 feet below the final grade.

5. With an applied safety factor of 2. Can be used to compute sliding resistance where foundations are placed on suitable soil/materials. Should be neglected for foundations subject to net uplift conditions.

6. Embedment necessary to minimize the effects of frost and/or seasonal water content variations. For sloping ground, maintain depth below the lowest adjacent exterior grade within 5 horizontal feet of the structure.

7. It appears that the shallow footings may bear in a combination of native undisturbed soils, new fill and/or weathered sandstone/shale. To reduce the concentration of stress due to non-uniform support beneath the structure and to reduce differential settlement, we recommend undercutting the areas where weathered sandstone/shale is encountered 2 feet beneath the footings to allow placement of moisture conditioned and compacted low volume change soil. The excavation beneath the footings should extend laterally at least 1 foot beyond the sides of the footings.

As noted in Earthwork, the footing excavations should be evaluated under the direction of the Geotechnical Engineer. The base of all foundation excavations should be free of water and loose soil, prior to placing concrete. Concrete should be placed soon after excavating to reduce bearing soil disturbance. Care should be taken to prevent wetting or drying of the bearing materials during construction. Excessively wet or dry material or any loose/disturbed material in the bottom of the footing excavations should be removed/reconditioned before foundation concrete is placed.

If unsuitable bearing soils are encountered at the base of the planned footing excavation, the excavation should be extended deeper to suitable soils, and the footings could bear directly on these soils at the lower level or on lean concrete backfill placed in the excavations. This is illustrated on the sketch below.

December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable 10

Over-excavation for structural fill placement below footings should be conducted as shown below.

The over-excavation should be backfilled up to the footing base elevation, with low plasticity cohesive material placed, as recommended in the Earthwork section.

The seismic design requirements for buildings and other structures are based on Seismic Design Category. Site Classification is required to determine the Seismic Design Category for a structure.

The Site Classification is based on the upper 100 feet of the site profile defined by a weighted average value of either shear wave velocity, standard penetration resistance, or undrained shear strength in accordance with Section 20.4 of ASCE 7 and the International Building Code (IBC).

Based on the soil/bedrock properties encountered at the site and as described on the exploration logs and results, it is our professional opinion that the Seismic Site Classification is C.

Subsurface explorations at this site were extended to a maximum depth of 29 feet. The site properties below the boring depth to 100 feet were estimated based on our experience and knowledge of geologic conditions of the general area. Additional deeper borings or geophysical testing may be performed to confirm the conditions below the current boring depth.

December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable 11

The subgrade soils are comprised of moderate to high plasticity clays exhibiting the potential to swell with increased water content. Construction of the floor slab creates the potential for gradual increased water contents within the clays. Increases in water content will cause the clays to swell and damage the floor slab. To reduce the swell potential to less than about 1 inch, at least the upper

2.5 feet of subgrade soils below the floor slab (excluding the floor slab support course) should be an approved Low Volume Change (LVC) material consisting of lean clays as described in Fill Material Types of the Earthwork section.

Item Description

Floor Slab Support At least 2.5 feet of low plasticity cohesive soils with at least 60% passing the U.S. No. 200 sieve material should be present below floor slabs and prepared in accordance with Earthwork.

Estimated Modulus of Subgrade Reaction

100 pounds per square inch per inch (psi/in) for point loads

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

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

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

Saw-cut control joints should be placed in the slab to help control the location and extent of cracking. For additional recommendations refer to the ACI Design Manual. Joints or cracks should be sealed with a water-proof, non-extruding compressible compound specifically recommended for heavy duty concrete pavement and wet environments.

Where floor slabs are tied to perimeter walls or turn-down slabs to meet structural or other construction objectives, our experience indicates differential movement between the walls and slabs will likely be observed in adjacent slab expansion joints or floor slab cracks beyond the length of the structural dowels. The Structural Engineer should account for potential differential settlement through use of sufficient control joints, appropriate reinforcing or other means.

December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable 12

Finished subgrade, within and for at least 10 feet beyond the floor slab, should be protected from traffic, rutting, or other disturbance and maintained in a relatively moist condition until floor slabs are constructed. If the subgrade should become damaged or desiccated prior to construction of floor slabs, the affected material should be removed and structural fill should be added to replace the resulting excavation. Final conditioning of the finished subgrade should be performed immediately prior to placement of the floor slab support course.

The Geotechnical Engineer should approve the condition of the floor slab subgrades immediately prior to placement of the floor slab support course, reinforcing steel, and concrete. Attention should be paid to high traffic areas that were rutted and disturbed earlier, and to areas where backfilled trenches are located.

Reinforced concrete 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 movement.

The recommended design lateral earth pressures do not include a factor of safety and do not provide for possible hydrostatic pressure on the walls.

December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable 13

Lateral Earth Pressure Design Parameters

Earth Pressure Condition

Coefficient for Backfill Type

Surcharge Pressure p1

(psf)

Earth Pressure p2

(psf) Equivalent Fluid Pressure (pcf)

Active (Ka) Granular - 0.33 Lean Clay - 0.42

(0.33)S (0.42)S

(40)H (50)H

At-Rest (Ko) Granular - 0.46 Lean Clay - 0.58

(0.46)S (0.58)S

(55)H (70)H

Passive (Kp) Granular - 3.0 Lean Clay - 2.4

Conditions applicable to the above table include:

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.

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

Uniform surcharge, where S is surcharge pressure.

In-situ soil backfill weight a maximum of 120 pcf.

Horizontal backfill, compacted to at least 95 percent of standard Proctor (ASTM D-698) maximum dry density.

Loading from heavy compaction equipment not included.

No groundwater acting on wall.

No safety factor included.

Ignore passive pressure in frost zone (18 inches).

Backfill placed against structures should consist of granular soils or low plasticity cohesive soils For the granular values to be valid, the granular backfill must extend out and up from the base of the wall at an angle of at least 45 and 60 degrees from vertical for the at-rest and passive cases, respectively. Additionally, the granular backfill must extend out from the base of the wall at an angle of at least 30 degrees from vertical for the active case. To calculate the resistance to sliding, a values of 0.2 and 0.4 should be used as the allowable coefficients of friction between the footing and the underlying soil or weathered bedrock, respectively.

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.

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

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

December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable 14

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.

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 90 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 retaining walls to prevent imposing lateral pressures larger than those provided.

Pavement designs are provided for the traffic conditions and pavement life conditions as noted in Project Description and in the following sections of this report. A critical aspect of pavement performance is site preparation. Pavement designs noted in this section are considered appropriate for this project provided the subgrade has been prepared as recommended in the Earthwork section and in the following sections of this report.

Expansive soils are present at this site. This report provides recommendations to help mitigate the effects of soil shrinkage and expansion. However, even if these recommendations are followed some pavement distress could still occur. It is, therefore, important to minimize moisture changes

December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable 15 in the subgrade both during construction and during the life of the pavement to reduce shrink/swell movements.

To reduce potential trafficability problems and strength loss, we recommend 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 thoroughly blended into the subgrade and allowed to cure for 48 to 72 hours before being remixed and compacted. Before compaction, the modifi optimum moisture as determined by the standard Proctor test method ASTM D698. After conditioning the soil to the required moisture content, the modified subgrade should be compacted

As an alternative to subgrade modification, we recommend placing at least 6 inches of ODOT by the standard Proctor test method ASTM D698.

The following table provides options for Asphaltic Concrete and Portland Cement Concrete sections:

Minimum Pavement Recommendations

Layer Thickness (inches)

Light Duty Heavy Duty

Portland Cement Concrete (3,500 psi, Air Entrained)

Modified Subgrade

OR

Modified Subgrade

OR

Asphaltic Concrete haltic Concrete Modified Subgrade

OR

Modified Subgrade

OR

Concrete

December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable 16

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 1988 Specifications.

2. See Project Description for more specifics regarding Light Duty and Heavy Duty traffic.

3.

be spread and densified to at least 98 percent e standard Proctor test method ASTM D698.

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

The pavement surfacing and adjacent sidewalks 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.

Pavement performance is affected by its surroundings. In addition to providing preventive maintenance, the civil engineer should consider the following recommendations in the design and layout of pavements:

Final grade adjacent to paved areas should slope down from the edges at a minimum 2%.

Subgrade and pavement surfaces should have a minimum 2% slope to promote proper surface drainage.

Install below pavement drainage systems surrounding areas anticipated for frequent wetting.

Install joint sealant and seal cracks immediately.

Seal all landscaped areas in or adjacent to pavements to reduce moisture migration to subgrade soils.

Place compacted, low permeability backfill against the exterior side of curb and gutter.

December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable 17

Place curb, gutter and/or sidewalk directly on clay subgrade soils rather than on unbound granular base course materials.

Our analysis and opinions are based upon our understanding of the project, the geotechnical conditions in the area, and the data obtained from our site exploration. Natural variations will occur between exploration point locations or due to the modifying effects of construction or weather.

The nature and extent of such variations may not become evident until during or after construction.

Terracon should be retained as the Geotechnical Engineer, where noted in this report, to provide observation and testing services during pertinent construction phases. If variations appear, we can provide further evaluation and supplemental recommendations. If variations are noted in the absence of our observation and testing services on-site, we should be immediately notified so that we can provide evaluation and supplemental recommendations.

Our Scope of Services does not include either specifically or by implication any environmental or biological (e.g., mold, fungi, bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions. If the owner is concerned about the potential for such contamination or pollution, other studies should be undertaken.

Our services and any correspondence or collaboration through this system are intended for the sole benefit and exclusive use of our client for specific application to the project discussed and are accomplished in accordance with generally accepted geotechnical engineering practices with no third-party beneficiaries intended. Any third-party access to services or correspondence is solely for information purposes to support the services provided by Terracon to our client.

Reliance upon the services and any work product is limited to our client, and is not intended for third parties. Any use or reliance of the provided information by third parties is done solely at their own risk. No warranties, either express or implied, are intended or made.

Site characteristics as provided are for design purposes and not to estimate excavation cost. Any use of our report in that regard is done at the sole risk of the excavating cost estimator as there may be variations on the site that are not apparent in the data that could significantly impact excavation cost. Any parties charged with estimating excavation costs should seek their own site characterization for specific purposes to obtain the specific level of detail necessary for costing.

Site safety, and cost estimating including, excavation support, and dewatering requirements/design are the responsibility of others. If changes in the nature, design, or location of the project are planned, our conclusions and recommendations shall not be considered valid unless we review the changes and either verify or modify our conclusions in writing.

Responsive Resourceful Reliable

December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable

Number of Borings Boring Depth (feet) Location

3 29 Planned building area

Boring Layout and Elevations: Terracon personnel provided the boring layout. Coordinates were obtained with a handheld GPS unit and approximate elevations were obtained using a

. The elevations were referenced to the finished floor of the existing building located approximately as shown on the exploration plan. We assigned this reference point an arbitrary elevation of 100.0 feet. Based on this benchmark, the ground surface elevations at the boring locations ranged from 97 to 100 feet. We rounded the elevations on the boring log to the nearest one-half foot. Consider the location and elevation of the boring accurate only to the degree implied by the methods used to make these measurements.

Subsurface Exploration Procedures: We advanced the borings with a truck-mounted, rotary drill rig using continuous flight augers (solid stem and/or hollow stem as necessary depending on soil conditions). Four samples were obtained in the upper 10 feet of each boring and at intervals of 5 feet thereafter. In the thin-walled tube sampling procedure, a thin-walled, seamless steel tube with a sharp cutting edge is pushed hydraulically into the soil to obtain a relatively undisturbed sample. In the split-barrel sampling procedure, a standard 2-inch outer diameter split-barrel sampling spoon is driven into the ground by a 140-pound automatic hammer falling a distance of 30 inches. The number of blows required to advance the sampling spoon the last 12 inches of a normal 18-inch penetration is recorded as the Standard Penetration Test (SPT) resistance value. The SPT resistance values, also referred to as N-values, are indicated on the boring logs at the test depths. We observed and recorded groundwater levels during drilling and sampling. For safety purposes, all borings are backfilled with auger cuttings after their completion. As required by the State of Oklahoma, any borings deeper than 20 feet, or borings which encounter groundwater or contaminated materials must be grouted or plugged in accordance with Oklahoma State statutes. One boring log must also be submitted to the Oklahoma Water Resources Board for each 10 acres of project site area.

Terracon grouted the borings and submitted logs in order to comply with the Oklahoma Water Resources Board requirements. Pavements were patched with cold-mix asphalt and/or pre-mixed concrete, as appropriate.

The sampling depths, penetration distances, and other sampling information was recorded on the field boring logs. The samples were placed in appropriate containers and taken to our soil laboratory for testing and classification by a Geotechnical Engineer representative. Our exploration team prepared field boring logs as part of the drilling operations. These field logs included visual classifications of the materials encountered during drilling and our interpretation of the subsurface

December 3, 2021 Terracon Project No. 03215238

Responsive Resourceful Reliable conditions between samples. Final boring logs were prepared from the field logs. The final boring logs represent the Geotechnical Engineer's interpretation of the field logs and include modifications based on observations and tests of the samples in our laboratory.

The project engineer reviewed the field data and assigned laboratory tests to understand the engineering properties of the various soil and rock strata, as necessary, for this project.

Water content Dry unit weight Atterberg limits Percent finer than No. 200 sieve Unconfined compressive strength

The laboratory testing program often included examination of soil samples by an engineer. Based on the mate d and classified the soil samples in accordance with the Unified Soil Classification System.

Rock classification was conducted using locally accepted practices for engineering purposes;

petrographic analysis may reveal other rock types. Boring log rock classification was determined using the Description of Rock Properties.

Contents:

Site Location Plan Exploration Plan

Note: All attachments are one page unless noted above.

SITE LOCATION

December 3, 2021 Terracon Project No. 03215238

Note to Preparer: This is a large table with outside borders. Just click inside the table above this text box, then paste your GIS Toolbox image.

When paragraph markers are turned on you may notice a line of hidden text above and outside the table please leave that alone. Limit editing to inside the table.

The line at the bottom about the general location is a separate table line. You can edit it as desired, but try to keep to a single line of text to avoid reformatting the page.

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS

EXPLORATION PLAN

December 3, 2021 Terracon Project No. 03215238

Note to Preparer: This is a large table with outside borders. Just click inside the table above this text box, then paste your GIS Toolbox image.

When paragraph markers are turned on you may notice a line of hidden text above and outside the table please leave that alone. Limit editing to inside the table.

The line at the bottom about the general location is a separate table line. You can edit it as desired, but try to keep to a single line of text to avoid reformatting the page.

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS

Boring Logs (B-1 through B-3)

5-7-9 N=16

3-4-8 N=12

15-50/6"

50/3"

50/1"

50/6"

31-50/6"

50/1"

15.2

15.2

16.0

12.2

11.2

10.3

11.4

12.9

18.4

56-19-37

FAT CLAY (CH), dark brown, very stiff

-hard below 2.5'

LEAN CLAY WITH SAND (CL), red, stiff

WEATHERED SANDSTONE, red, poorly cemented

WEATHERED SHALE, with sandstone seams to 13.5', red, moderately hard

-hard below 13.5'

-soft below 18.5'

-hard below 28.5' Boring Terminated at 29 Feet

3.5

6.5

8.5

29.0

96.5+/-

93.5+/-

91.5+/-

71+/-

Surface Cover: Vegetation

17230

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

Classification of rock estimated from disturbed samples. Core samples and petrographic analysis may reveal other rock types.

TH

IS

BO

R

IN

G

LO

G

IS

N

O T

VA

LI

D

IF

SE

PA

R

AT

ED

FR

O M

O R

IG

IN

AL

R

EP

O

R T.

G

EO

SM

AR

T

LO

G -N

O W

EL

L

R

EP

LA

C

E

FR

IE

N

D

SH

IP

H

O U

SE

.G

PJ

TE

R R

AC

O

N _D

AT

AT

EM

PL

AT

E.

G D

T

/3 /2

D

EP

TH

(F t.)

W

AT

ER

LE

VE

L

O

BS

ER

VA

TI

O

N S

FI

EL

D

TE

ST

R

ES

U

LT

S

W

AT

ER

C

O N

TE

N

T

D R

Y U

N

IT

W

EI

G H

T (p cf

LL-PL-PI

ATTERBERG

LIMITSLOCATION See Exploration Plan

Latitude: 35.5029° Longitude: -97.5320°

G R

AP

H

IC

LO

G

M O

D

EL

LA

YE

R

DEPTH ELEVATION (Ft.)

Approximate Surface Elev.: 100.0 (Ft.) +/-

Advancement Method:

Power Auger

Abandonment Method:

Boring backfilled with cuttings above 4’; grouted 4’ to 14’;

backfilled with cuttings from 14’ to termination depth.

Notes:

Project No.: 03215238

Drill Rig: 747

BORING LOG NO. B-1

Spur Design LLCCLIENT:

Oklahoma, Oklahoma

Driller: RP

Boring Completed: 11-18-2021

PROJECT: Replace Friendship House

See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any).

See Supporting Information for explanation of symbols and abbreviations.

N Military Avenue and NW 32nd Street Oklahoma City, Oklahoma

SITE:

Boring Started: 11-18-2021

4701 N Stiles Ave Oklahoma City, OK

28.5' While drilling

WATER LEVEL OBSERVATIONS

R

EC

O

VE

R Y

(In

U N

C O

N

FI

N

ED

C O

M

PR

ES

SI

VE

ST

R

EN

G

TH

(p sf

PE

R

C

EN

T

FI

N

ES

SA

M

PL

E

TY

PE

4-5-7 N=12

20-50/5"

50/3"

50/4"

50/2"

26-50/6"

25-50/6"

50/1"

20.2

15.2

11.7

12.0

12.1

11.3

13.6

14.2

7.8

112 30-15-15

APPROX. 4'' OF CONCRETE

FAT CLAY (CH), dark brown, stiff

LEAN CLAY (CL), red, stiff

WEATHERED SANDSTONE, red, poorly cemented

-cemented below 6'

-well cemented below 13.5'

WEATHERED SHALE, red, soft

-hard below 28.5' Boring Terminated at 29 Feet

0.3

2.5

4.0

18.5

29.0

96.5+/-

94.5+/-

93+/-

78.5+/-

68+/-

3310 88

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

Classification of rock estimated from disturbed samples. Core samples and petrographic analysis may reveal other rock types.

TH

IS

BO

R

IN

G

LO

G

IS

N

O T

VA

LI

D

IF

SE

PA

R

AT

ED

FR

O M

O R

IG

IN

AL

R

EP

O

R T.

G

EO

SM

AR

T

LO

G -N

O W

EL

L

R

EP

LA

C

E

FR

IE

N

D

SH

IP

H

O U

SE

.G

PJ

TE

R R

AC

O

N _D

AT

AT

EM

PL

AT

E.

G D

T

/3 /2

D

EP

TH

(F t.)

W

AT

ER

LE

VE

L

O

BS

ER

VA

TI

O

N S

FI

EL

D

TE

ST

R

ES

U

LT

S

W

AT

ER

C

O N

TE

N

T

D R

Y U

N

IT

W

EI

G H

T (p cf

LL-PL-PI

ATTERBERG

LIMITSLOCATION See Exploration Plan

Latitude: 35.5024° Longitude: -97.5321°

G R

AP

H

IC

LO

G

M O

D

EL

LA

YE

R

DEPTH ELEVATION (Ft.)

Approximate Surface Elev.: 97.0 (Ft.) +/-

Advancement Method:

Power Auger

Abandonment Method:

Boring backfilled with cuttings above 4’; grouted 4’ to 14’;

backfilled with cuttings from 14’ to termination depth. Surface capped with asphalt.

Notes:

Project No.: 03215238

Drill Rig: 747

BORING LOG NO. B-2

Spur Design LLCCLIENT:

Oklahoma, Oklahoma

Driller: RP

Boring Completed: 11-18-2021

PROJECT: Replace Friendship House

See Exploration and Testing Procedures for a description of field and laboratory procedures used and additional data (If any).

See Supporting Information for explanation of symbols and abbreviations.

N Military Avenue and NW 32nd Street Oklahoma City, Oklahoma

SITE:

Boring Started: 11-18-2021

4701 N Stiles Ave Oklahoma City, OK

WATER LEVEL OBSERVATIONS

No free water observed

R

EC

O

VE

R Y

(In

U N

C O

N

FI

N

ED

C O

M

PR

ES

SI

VE

ST

R

EN

G

TH

(p sf

PE

R

C

EN

T

FI

N

ES

SA

M

PL

E

3-6-8 N=14

3-4-6 N=10

50/5"

50/1"

50/6"

50/5"

50/6"

50/6"

18.3

20.4

16.9

14.2

14.2

10.8

11.8

11.4

12.0

55-20-35

44-15-29

APPROX. 4'' OF CONCRETE

FAT CLAY (CH), dark brown, stiff

-very stiff below 2.5'

LEAN CLAY WITH SAND (CL), red, stiff

WEATHERED SANDSTONE, red, poorly cemented

-well cemented below 8.5'

WEATHERED SHALE, red and gray, soft

-red below 18.5'

Boring Terminated at 29 Feet

0.3

3.5

6.0

13.5

29.0

99+/-

96+/-

93.5+/-

86+/-

70.5+/-

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

Classification of rock estimated from disturbed samples. Core samples and petrographic analysis may reveal other rock types.

TH

IS

BO

R

IN

G

LO

G

IS

N

O T

VA

LI

D

IF

SE

PA

R

AT

ED

FR

O M

O R

IG

IN

AL

R

EP

O

R T.

G

EO

SM

AR

T

LO

G -N

O W

EL

L

R

EP

LA

C

E

F…