Attachment 3 Geotech Report.pdf

ECS Southwest, LLP Geotechnical Engineering Report IHS Modular Building

1515 NE Lawrie Tatum Road Lawton, Oklahoma

ECS Project Number 58:1771

January 2, 2024

IHS Modular Building January 2, 2024 ECS Project No. 58:1771 Page i

TABLE OF CONTENTS

EXECUTIVE SUMMARY

1.0 INTRODUCTION

2.0 PROJECT INFORMATION

2.1 Project Location/Current Site Use

2.2 Proposed Construction

3.0 FIELD EXPLORATION AND LABORATORY TESTING

3.1 Subsurface Characterization

3.2 Groundwater Observations

3.3 Laboratory Testing

4.0 DESIGN RECOMMENDATIONS

4.1 Potential Vertical Movements

4.2 Subgrade Improvements

4.3 Shallow Foundations

4.4 Slab on Grade

4.5 Building Perimeter Conditions

4.6 Seismic Design Considerations

5.0 SITE CONSTRUCTION RECOMMENDATIONS

5.1 Subgrade Preparation

5.1.1 Stripping and Grubbing

5.1.2 Proofrolling

5.2 Earthwork Operations

5.2.2 Fill Placement

5.2.3 Earthwork Testing

5.3 Material Specifications

5.3.1 Select Fill

5.3.2 Moisture Conditioning

5.3.3 Lime Stabilized On Site Clay ........................................... Error! Bookmark not defined.

5.4 Foundation and Slab Observations

5.5 Utility Installations

6.0 CLOSING

ECS Project No. 58:1771 Page ii

APPENDICES

Appendix A – Drawings & Reports

• Site Location Diagram

• Boring Location Diagram

• Generalized Subsurface Soil Profile A-A’

Appendix B – Field Operations

• Reference Notes for Boring Logs

• Subsurface Exploration Procedures: Standard Penetration Testing (SPT)

• Boring Logs B-01 to B-02

Appendix C – Laboratory Testing

• Laboratory Testing Summary

ECS Project No. 58:1771 Page 1

EXECUTIVE SUMMARY

This Executive Summary is intended as a very brief overview of the primary geotechnical conditions that are expected to affect design and construction. The following summarizes the main findings of the exploration, particularly those that may have a cost impact on the planned development.

Further, our principal foundation recommendations are summarized. Information gleaned from the executive summary should not be utilized in lieu of reading the entire geotechnical report.

• The planned structure is understood to be an approximately 9,350 square feet modular building. We have assumed the structure will be single story, entirely above grade and have maximum column and wall loads of approximately 60 kips and 4 kips/foot, respectively. We have also assumed the structure will have a finished floor elevation at or near the existing grade.

• The planned structures may be supported on a shallow foundation system consisting of spread footings with conventional slab on grade (if planned), provided the subgrade is improved and is prepared as outlined in this report.

• Subgrade improvements of the moderately plastic clay soils are necessary below the planned structure to reduce the potential for vertical movements. Specific details on addressing these moderately plastic clay soils are presented in the body of the report.

• It is recommended that ECS conduct a geotechnical review of the project plans (prior to issuance for construction) to check to see that ECS’ geotechnical recommendations have been properly interpreted and implemented.

• To prevent misinterpretation of ECS recommendations, ECS should be retained to perform quality control testing and documentation during construction of the earthwork and foundations for the project.

ECS Project No. 58:1771 Page 2

1.0 INTRODUCTION

The purpose of this study was to provide geotechnical information for the design and construction of the foundations and floor slabs (if planned) for the planned IHS Modular Building project located at 1515 NE Lawrie Tatum in Lawton, Oklahoma. The recommendations developed for this report are based on project information provided by the client.

Our services were provided in accordance with our Proposal No. 58:3031-GP, dated September 25, 2023, and authorized by the client by providing the signed contact on October 14, 2023, which includes our Terms and Conditions of Service.

This report contains the procedures and results of our subsurface exploration and laboratory testing programs, review of existing site conditions, engineering analyses, and recommendations for the design and construction of the project.

The report includes the following items.

• A brief review and description of our field and laboratory test procedures and the results of testing conducted.

• A review of surface topographical features and site conditions.

• A review of area and site geologic conditions.

• A review of subsurface soil stratigraphy with pertinent available physical properties.

• A final copy of our soil test borings.

• Recommendations for site preparation and construction of compacted fills, including an evaluation of on-site soils for use as compacted fills.

• Recommended foundation type.

2.0 PROJECT INFORMATION

2.1 PROJECT LOCATION/CURRENT SITE USE

The project is located at 1515 NE Lawrie Tatum in Lawton, Oklahoma. The location is depicted in Figure 2.1.1 as shown below.

ECS Project No. 58:1771 Page 3

Figure 2.1.1. Site Location

ECS reviewed aerial photographs of the subject site dated 1995 through 2023. Since February 1995, the site appears to consist of two single-family residential buildings. At some time between February 1995 and August 2003, additional single-family buildings appear to have been constructed. At some time between July 2005 and October 2006, a gravel access road was constructed to the south. At some time between October 2011 and October 2013, it appears the single-family residential homes were demolished and removed from the site while the gravel drive areas to the south remained. At some time between October 2013 and October 2015, the site was stripped of vegetation and used as a construction staging area. At some time between October 2015 and June 2016, the construction staging was cleared and the area was a vacant, grassed property. Since that time, the site has remained relatively unchanged.

Currently the site is an undeveloped, grassed property within the boundaries of the Lawton Indian Hospital. The topography of the site is generally flat with a boring elevations of approximately EL 1122 feet. The ground surface elevations noted in this report were obtained from Google Earth and have been rounded to the nearest foot.

2.2 PROPOSED CONSTRUCTION

The following information explains our understanding of the planned development including the proposed building and related infrastructure.

SUBJECT DESIGN INFORMATION / ASSUMPTIONS

Building Footprint Approximately 9,350 square feet in plan view based on site plan provided # of Stories (assumed) Single-story, entirely above grade Usage (assumed) Modular Building Framing (assumed) Unknown

ECS Project No. 58:1771 Page 4

SUBJECT DESIGN INFORMATION / ASSUMPTIONS

Column Loads (assumed) 60 kips (Full Dead and Live Load) maximum Wall Loads (assumed) 4 kips per linear foot (klf) maximum Lowest Finish Floor Elevation Unknown, assumed no more than 2 feet below or above existing grades

We also understand that associated parking and drive areas will be constructed. If ECS’ understanding of the project is not correct, especially if the structural loads are different, please contact ECS so that we may review these changes and revise our recommendations, as appropriate.

3.0 FIELD EXPLORATION AND LABORATORY TESTING

Our exploration procedures are explained in greater detail in Appendix B including the insert titled Subsurface Exploration Procedures. Our scope of work included drilling two (2) borings. The boring locations were selected by ECS based on information provided by the client and identified in the field by the drilling crew using boring GPS coordinates generated by ECS. The approximate as-drilled boring locations are shown on the Boring Location Diagram in Appendix A.

3.1 SUBSURFACE CHARACTERIZATION

The subsurface conditions encountered were generally consistent with published geological mapping. The following sections provide generalized characterizations of the soil strata encountered during our subsurface exploration. For specific subsurface information refer to the boring logs in Appendix B.

Approximate Depth of Bottom of Strata

Below Grade Elevation(1) (ft) Stratum Material Description Consistency /

Density

6 inches --- Cover Topsoil --

15 feet(2) Elevation 1107 I (CL) LEAN CLAY, various shades of red and brown Stiff to Very Stiff

Notes:

(1) Elevations are approximate.

(2) Depth to deepest boring termination depth.

Please refer to the attached boring logs and laboratory data summary for this field exploration for a more detailed description of the subsurface conditions encountered in the borings as the stratification descriptions above are generalized for presentation purposes.

3.2 GROUNDWATER OBSERVATIONS

Water levels were measured in our boring logs in Appendix B. Groundwater was not observed in the borings at the time of our exploration and is indicated on the boring logs as “dry”.

Variations in the long-term water table may occur as a result of changes in precipitation, evaporation, surface water runoff, construction activities, and other factors.

ECS Project No. 58:1771 Page 5

3.3 LABORATORY TESTING

The laboratory testing consisted of selected tests performed on samples obtained during our field exploration operations. Classification and index property tests were performed on representative soil samples. Testing performed include moisture content, Atterberg Limits, and percent passing the No. 200 sieve.

Samples were visually classified on the basis of texture and plasticity in accordance with ASTM D2488 Standard Practice for Description and Identification of Soils (Visual-Manual Procedures) and including USCS classification symbols, and ASTM D2487 Standard Practice for Classification for Engineering Purposes (Unified Soil Classification System (USCS). After classification, the samples were grouped in the major zones noted on the boring logs in Appendix B. The group symbols for each soil type are indicated in parentheses along with the soil descriptions. The stratification lines between strata on the logs are approximate; in situ, the transitions may be gradual.

4.0 DESIGN RECOMMENDATIONS

The following recommendations have been developed on the basis of the previously described project characteristics and subsurface conditions. If there are any changes to the project characteristics or if different subsurface conditions are encountered during construction, ECS should be consulted so that the recommendations of this report can be reviewed. No below-grade levels are planned, and we have assumed a finished floor elevation at no more than 2 feet below or above existing grades. If the finished floor elevations deviate from this assumed grade, the recommendations provided below should be evaluated by our office.

4.1 POTENTIAL VERTICAL MOVEMENTS

The intent of recommendations contained in the Subgrade Improvements section of this report are provided in order to reduce the potential risk associated with the shrink/swell tendencies of the on-site expansive soil.

The majority of clay soils encountered in the borings have a moderate expansion potential. Based on our Atterberg limits laboratory test results and experience with similar soils, we estimate potential vertical soil movements (PVM) of the expansive soils encountered in the borings of up to about 1 ½ inches, based on dry conditions. These potential movements reflect moisture changes in the soil that can occur over the life of the structure and after construction is complete. The actual movements could be greater if poor drainage, ponded water, and/or other unusual sources of moisture are allowed to saturate the soils beneath the structure after construction.

4.2 SUBGRADE IMPROVEMENTS

In order to reduce the risk associated with future movements due to expansion potential, we recommend the following general building pad subgrade improvements to reduce the PVM to approximately 1 inch. Please note, these recommendations are the minimum requirements to reduce potential movements due to expansion potential.

ECS Project No. 58:1771 Page 6

Options Depth of Select Fill (feet)

Depth of Moisture Conditioning (feet)

Total Depth of Improved Zone (feet)

Estimated

PVM

(inch)

Option 1 3 --- 3 1

Option 2 --- 5 5 1

The subgrade improvements should extend at least 5 feet beyond the edge of the building pads and/or foundation area and include any flatwork sensitive to movements such as sidewalks or pavements. Exterior perimeter footing/grade beam backfill should consist of moisture conditioned clay soil. Please refer to the “Material Specifications” section of this report for more details.

These design parameters assume that positive drainage will be provided away from the structures and with moderate irrigation of surrounding lawn and planter areas with no excessive wetting or drying of soils adjacent to the foundations. Greater potential movements could occur with extreme wetting or drying of the soils due to ponding of water, plumbing leaks or lack of irrigation. Recommendations for earthwork operations are found in the “Site Construction Recommendations” portion of this report.

4.3 SHALLOW FOUNDATIONS

Provided the subgrades are improved and structural fills are prepared as recommended in this report, the proposed structures can be supported by shallow foundations including column footings and continuous wall footings. We recommend the foundation design use the following parameters:

Design Parameter Column Footing Wall Footing

Net Allowable Bearing Pressure(1) 2,500 psf 2,500 psf

Bearing Soil Material Improved Subgrades Improved Subgrades

Minimum Width 24 inches 18 inches

Minimum Footing/Grade Beam Embedment Depth (below slab or finished grade) (2) 24 inches 24 inches

Estimated Total Settlement (3) Less than 1- inch Less than 1- inch

Estimated Differential Settlement (4) Less than ¾ inches between columns

Less than ¾ inches per 30 linear feet

Notes:

(1) Net allowable bearing pressure is the applied pressure in excess of the surrounding overburden soils above the base of the foundation.

(2) For bearing considerations and frost penetration requirements.

(3) Based on our assumed structural loads. If final loads are different, ECS must be contacted to update foundation recommendations and settlement calculations.

(4) Based on maximum loads and variability in borings.

Differential settlement can be re-evaluated once the foundation plans are more complete.

ECS Project No. 58:1771 Page 7

Potential Undercuts: DCP testing of the bearing soils by ECS representatives should be incorporated during construction to verify their suitability for supporting shallow foundations. If soft or inadequate soils are observed at the footing bearing elevations, these soils should be undercut and removed. Any undercut should be backfilled with lean concrete (f’c ≥ 1,000 psi at 28 days) up to the original design bottom of footing elevation; the original footing shall be constructed on top of the hardened lean concrete.

4.4 SLAB ON GRADE (IF PLANNED)

A slab on grade, if planned, may be used provided the subgrades are improved and prepared as recommended in this report.

The following graphic depicts our soil-supported slab recommendations:

1.

2.

3.

Concrete Slab Thickness: 4 inches minimum Concrete Slab Strength: 3,000 psi minimum Drainage Layer Thickness: 4 inches minimum

4. Drainage Layer Material: GRAVEL (GP, GW)

5. Subgrade compacted per the earthwork recommendations provided.

Subgrade Modulus: Provided subgrades are prepared as, discussed herein, the slab may be designed assuming a modulus of subgrade reaction, k1 of 125 pci (lbs/cu. inch).

Vapor Retarder: Before the placement of concrete, a vapor retarder may be placed on top of the granular drainage layer to provide additional protection against moisture penetration through the floor slab. When a vapor retarder is used, special attention should be given to surface curing of the slab to reduce the potential for uneven drying, curling and/or cracking of the slab. Depending on proposed flooring material types, the structural engineer and/or the architect may choose to eliminate the vapor retarder.

Slab Isolation: Soil-supported slabs should be isolated from the foundations and foundation-supported elements of the structure so that differential movement between the foundations and slab will not induce excessive shear and bending stresses in the floor slab. Where the structural configuration prevents the use of a free-floating slab such as in a drop down footing/monolithic slab configuration, the slab should be designed with suitable reinforcement and load transfer devices to reduce the risk of overstressing of the slab.

4.5 BUILDING PERIMETER CONDITIONS

Soils placed along the exterior of the foundations should consist of fine-grained soils encountered on site, placed and compacted in accordance with the “Fill Placement” section of this report. The purpose of this clay backfill is to reduce the opportunity for surface or subsurface water infiltration

Concrete Slab

Improved Subgrade (as recommended)

Vapor Retarder

Granular Base Layer (optional at owner’s discretion)

ECS Project No. 58:1771 Page 8 beneath the structure. Additionally, where lateral penetrations (for utilities) into or below the structure occur, a clay plug (or suitable synthetic alternative) should be placed at the building line to reduce the opportunity for infiltrating water, regardless of the backfill material. A clay plug detail is included in Appendix D.

Positive drainage should be provided around the perimeter of the structures to minimize the potential for moisture infiltration into the foundation and slab subgrade soils. We recommend that landscaped areas adjacent to the structures and pavements be sloped away from the construction and maintain a fall of at least 6 inches for the first 10 feet outward from the structure. Roof drains should discharge at least 5 feet from the building perimeter or directly into below grade discharge piping. The parking lots, sidewalks, and any other paved areas should also be sloped to divert surface water away from the proposed building. Site drainage shall be the sole responsibility of the project civil engineer. Where flatwork is placed against or near the structure, a positive seal must be installed and adequately maintained to limit water intrusion.

Routine maintenance of the building perimeter condition is necessary so that the recommendations contained in this report are followed and maintained. Greater potential vertical movements could occur with extreme wetting or drying of the soils due to poor drainage, ponding of water, plumbing leaks, lack of irrigation, and/or lack of routine maintenance, etc.

4.6 SEISMIC DESIGN CONSIDERATIONS

Seismic Site Classification: The International Building Code (IBC) 2015/2018 requires site classification for seismic design based on the upper 100 feet of a soil profile. At least two methods are utilized in classifying sites, namely the shear wave velocity (vs) method and the Standard Penetration Resistance (N-value) method. The Standard Penetration Resistance (N-value) method was used in classifying this site.

SEISMIC SITE CLASSIFICATION

Site

Class Soil Profile Name Shear Wave Velocity, Vs, (ft./s)

N value (bpf)

A Hard Rock Vs > 5,000 fps N/A

B Rock 2,500 < Vs ≤ 5,000 fps N/A

C Very dense soil and soft rock 1,200 < Vs ≤ 2,500 fps >50

D Stiff Soil Profile 600 ≤ Vs ≤ 1,200 fps 15 to 60

E Soft Soil Profile Vs < 600 fps <15

Based upon our interpretation of the subsurface conditions, the appropriate Seismic Site Classification is “D” as shown in the preceding table.

Ground Motion Parameters: In addition to the seismic site classification, ECS has determined the design spectral response acceleration parameters following the IBC methodology. The Mapped Reponses were estimated from the U.S. Seismic Design Maps website www.seismicmaps.org. The design responses for the short (0.2 sec, SDS) and 1-second period (SD1) are noted in bold at the far-right end of the following table.

http://www.seismicmaps.org/

ECS Project No. 58:1771 Page 9

GROUND MOTION PARAMETERS [IBC 2015/2018 Method]

Period (sec)

Mapped Spectral Response

Accelerations (g)

Values of Site Coefficient for Site Class

Maximum Spectral Response Acceleration

Adjusted for Site Class (g)

Design Spectral Response

Acceleration (g)

Reference Figures 1613.3.1

(1) & (2)

Tables 1613.3.3

(1) & (2)

Eqs. 16-37 & 16-38

Eqs. 16-39 & 16-40

0.2 SS 0.377 Fa 1.499 SMS=FaSs 0.565 SDS=2/3

SMS

0.376

1.0 S1 0.109 Fv 2.364 SM1=FvS1 0.257 SD1=2/3

SM1

0.172

The Site Class definition should not be confused with the Seismic Design Category designation which the Structural Engineer typically assesses. If a higher site classification is beneficial to the project, we can provide additional testing methods that may yield more favorable results.

5.0 SITE CONSTRUCTION RECOMMENDATIONS

5.1 SUBGRADE PREPARATION

In a dry and undisturbed state, the upper 1-foot of the majority of the soil at the site should provide good subgrade support for fill placement and construction operations. However, when wet, this soil will degrade quickly with disturbance from contractor operations. Therefore, good site drainage should be maintained during earthwork operations, which should help maintain the integrity of the soil.

The surface of the site should be kept properly graded in order to enhance drainage of the surface water away from the proposed structures during the construction phase. We recommend that an attempt be made to enhance the natural drainage without interrupting its pattern, where possible.

The soils at the site are moisture and disturbance sensitive, and contain fines which are considered moderately erodible. Therefore, the contractor should carefully plan his operation to limit exposure of the subgrade to weather and construction equipment traffic, and provide and maintain good site drainage during earthwork operations. All erosion and sedimentation shall be controlled in accordance with sound engineering practice and current jurisdictional requirements.

5.1.1 Stripping and Grubbing

The subgrade preparation should consist of stripping all existing gravels/pavements, vegetation, topsoil, or any soft or yielding materials from the 5-foot expanded building area, and any areas receiving new fill. Deeper topsoil or organic laden soils may be present in wet, low-lying, and poorly drained areas. ECS should be retained to verify that topsoil and yielding surficial materials have been removed prior to the placement of structural fill or construction of structures.

5.1.2 Proofrolling

Prior to fill placement or other construction on subgrades, the subgrades should be evaluated by an ECS field technician. The exposed subgrade should be comprehensively proofrolled with construction equipment having a minimum axle load of 10 tons [e.g. fully loaded tandem-axle dump

ECS Project No. 58:1771 Page 10 truck]. Proofrolling should be traversed in two perpendicular directions with overlapping passes of the vehicle under the observation of an ECS technician. This procedure is intended to assist in identifying any localized yielding materials.

Where proofrolling identifies areas that are yielding or “pumping” subgrade those areas should be repaired prior to the placement of any subsequent Structural Fill or other construction materials.

Methods of stabilization include undercutting, moisture conditioning, or chemical stabilization. The situation should be discussed with ECS to determine the appropriate procedure. Test pits may be excavated to explore the shallow subsurface materials to help in determining the cause of the observed yielding materials, and to assist in the evaluation of appropriate remedial actions to repair the subgrade.

5.2 EARTHWORK OPERATIONS

The following sections describe requirements for fill placement, and earthwork testing.

5.2.2 Fill Placement

Prior to placement of any new fill or other construction material, subgrades should be scarified to a minimum depth of 8 inches, moisture conditioned to a workable moisture content at or above the optimum value and compacted to at least 95% of Maximum Dry Density as obtained by the Standard Proctor Method (ASTM D-698).

Fill material in the building pad areas should consist of select fill. Details regarding select fill are presented in the “Materials Specifications” section of this report. Fill material should be moisture conditioned at or above the optimum moisture content and compacted to at least 95% of the Maximum Dry Density as obtained by the Standard Proctor Method (ASTM D-698).

Soil moisture levels should be preserved (by various methods that can include covering with plastic, watering, etc.) until new fill, pavements, or slabs are placed. Fill soils should be placed in maximum 8 inch loose lifts for mass grading operations and maximum 4 inches for trench type excavations where walk behind or “jumping jack” compaction equipment is used.

Upon completion of the filling operations, care should be taken to maintain the soil moisture content prior to construction of floor slabs and/or pavements. If the soil becomes desiccated, the affected material should be removed and replaced, or these materials should be scarified, moisture conditioned and recompacted.

5.2.3 Earthwork Testing

Field density and moisture tests should be performed by ECS on each lift as necessary to verify that adequate compaction is achieved. One test per 2,500 square feet per lift is recommended in the future building and pavement areas (two tests minimum per lift). Utility trench backfill should be tested at a rate of one test per lift per each 150 linear feet of trench (two tests minimum per lift).

Certain jurisdictional requirements may require testing in addition to that noted previously.

Therefore, these recommendations should be reviewed and the more stringent specifications should be followed.

ECS Project No. 58:1771 Page 11

5.3 MATERIAL SPECIFICATIONS

The recommendations provided in the “Subgrade Improvements” portion of this report outline the subgrade improvement options required in order to achieve the desired PVM. This section is intended to outline the material requirements of those recommendations.

5.3.1 Select Fill

For the purposes of this report, select fill may consist of imported material that is free of debris and organic matter, has a Plasticity Index (PI) less than 15, more than 60% passing the No. 200 sieve, and a maximum particle size of 2 inches. The PI and gradation of this material should be evaluated by ECS at the time of construction.

This material should be placed and compacted at workable moisture contents at or above the optimum moisture content and compacted to at least 95% of the Maximum Dry Density as obtained using the Standard Proctor Method (ASTM D-698).

5.3.2 Moisture Conditioning

Within the planned pads and flatwork sensitive to movements, moisture conditioning should be performed as outlined in this report. Reworking of the existing clays, and new clayey fill, is performed to increase the moisture of the clays to a level that reduces their ability to absorb additional water that could result in post-construction heave in these soils.

The moisture conditioning should consist of undercutting, scarifying and/or reworking, as required to achieve the required subgrade improvement. During this process, the clay should receive adequate amounts of water to attain an even moisture content of at least +2% or higher above the optimum moisture content. During the addition of water, the soils should be adequately mixed, and re-mixed, to achieve an even distribution of the moisture throughout the soil mass. Once appropriately mixed, the material should be compacted to at least 95% of the Maximum Dry Density as obtained using the Standard Proctor Method (ASTM D-698).

Outside of the moisture conditioned zone and where clay is used to establish site grades, we recommend that this material be placed and compacted to at least 95% of the Maximum Dry Density as obtained using the Standard Proctor Method (ASTM D-698). These soils should be free of deleterious materials, and be reworked to achieve an even distribution of water in order to achieve a moisture content of ±2% of the material optimum moisture content.

Care should be taken to verify and preserve the specified moisture levels in the reworked clays prior to placement of non-expansive fill.

5.4 FOUNDATION AND SLAB OBSERVATIONS

Protection of Foundation Excavations: Exposure to the environment may weaken the soils at the footing bearing level if the foundation excavations remain open for too long a time. Therefore, foundation concrete should be placed the same day that excavations are made. If the bearing soils are softened by surface water intrusion or exposure, the softened soils must be removed from the foundation excavation bottom immediately prior to placement of concrete. If the excavation must remain open overnight, or if rainfall becomes imminent while the bearing soils are exposed, a 1 to

ECS Project No. 58:1771 Page 12

3-inch thick “mud mat” of “lean” concrete should be placed on the bearing soils before the placement of reinforcing steel.

Footing Subgrade Observations: Most of the soils at the foundation bearing elevation are anticipated to be suitable for support of the proposed structure. It is important to have ECS observe the foundation subgrade prior to placing foundation concrete, to confirm the bearing soils are what was anticipated.

Slab Subgrade Verification: Prior to placement of a granular base/drainage layer, the subgrade should be improved/prepared in accordance with recommendations provided in this report.

5.5 UTILITY INSTALLATIONS

Utility Subgrades: The soils encountered in our exploration are expected to be generally suitable for support of utility pipes. The pipe subgrades should be observed and probed for stability by ECS.

Any loose or unsuitable materials encountered should be removed and replaced with suitable compacted Structural Fill, or pipe stone bedding material.

Utility Cuts/Backfilling: Utility cuts should not be left open for more than 24 hours or during times when precipitation is anticipated. The granular bedding material should be at least 4 inches thick, but not less than that specified by the civil engineer’s project drawings and specifications. We recommend that the bedding materials be placed up to the springline of the pipe. Fill placed for support of the utilities, as well as backfill over the utilities, should satisfy the requirements for Structural Fill and Fill Placement.

Excavation Safety: All excavations and slopes should be constructed and maintained in accordance with OSHA excavation safety standards. The contractor is solely responsible for designing, constructing, and maintaining stable temporary excavations and slopes. The contractor’s responsible person, as defined in 29 CFR Part 1926, should evaluate the soil exposed in the excavations as part of the contractor’s safety procedures. In no case should slope height, slope inclination, or excavation depth, including utility trench excavation depth, exceed those specified in local, state, and federal safety regulations. ECS is providing this information solely as a service to our client. ECS is not assuming responsibility for construction site safety or the contractor’s activities; such responsibility is not being implied and should not be inferred.

6.0 CLOSING

ECS has prepared this report of findings, evaluations, and recommendations to guide geotechnical-related design and construction aspects of the project. In fulfilling our obligations and responsibilities, as listed in the proposal, we performed these services in accordance with the standard of care expected of professionals in the industry performing similar services on projects of like size and complexity at this time in the region. No other representation, expressed or implied, and no warranty or guarantee is included or intended in this report. ECS is not responsible for the conclusions, opinions, or recommendations of others based on the data in this report.

The description of the proposed project is based on information provided to ECS by the project design team. If any of this information is inaccurate, either due to our interpretation of the documents provided or site or design changes that may occur later, ECS should be contacted so

ECS Project No. 58:1771 Page 13 that we can review the report in light of the changes and provide additional or alternate recommendations as may be required.

We recommend that ECS review the project’s plans and specifications so that we may evaluate those plans/specifications with the intent of the geotechnical report. Field observations, monitoring, and quality assurance testing during earthwork and foundation installation are an extension of and integral to the geotechnical design recommendations. We recommend that the Owner retain ECS throughout construction.

ECS is not responsible for the conclusions, opinions, or recommendations of others based on the data in this report.

APPENDIX A – Drawings & Reports

Site Location Diagram Boring Location Diagram Generalized Subsurface Soil Profile A-A’

12/1/2023

Service Layer Credits: Esri, HERE, Garmin, (c) OpenStreetMap contributors

²

ENGINEER

SCALE

58:1771

PROJECT NO.

FIGURE

DATE

AW

INDIAN HEALTH SERVICE

IHS MODULAR BUILDING

1515 NE LAWRIE TATUM ROAD, LAWTON, OKLAHOMA

SITE LOCATION DIAGRAM

0 500250

Feet

AS NOTED

B-01

B-02 A

A'

12/27/2023

Service Layer Credits: Esri, HERE, Garmin, (c) OpenStreetMap contributors

²

ENGINEER

SCALE

58:1771

PROJECT NO.

FIGURE

DATE

AW

Legend Approximate Boring Locations -

Approximate Cross-Section Locations -

INDIAN HEALTH SERVICE

IHS MODULAR BUILDING

1515 NE LAWRIE TATUM ROAD, LAWTON, OKLAHOMA

BORING LOCATION DIAGRAM

0 12060

Feet

AS NOTED

1123 1123

1122 1122

1121 1121

1120 1120

1119 1119

1118 1118

1117 1117

1116 1116

1115 1115

1114 1114

1113 1113

1112 1112

1111 1111

1110 1110

1109 1109

1108 1108

1107 1107

Legend Key Topsoil

Lean

CLAY

Notes:

1- EOB: END OF BORING AR: AUGER REFUSAL SR: SAMPLER REFUSAL.

2- THE NUMBER BELOW THE STRIPS IS THE DISTANCE ALONG THE BASELINE.

3- SEE INDIVIDUAL BORING LOG AND GEOTECHNICAL INFORMATION.

4- STANDARD PENETRATION TEST RESISTANCE (LEFT OF BORING) IN BLOWS PER

FOOT (ASTM D1586).

Plastic Limit Water Content Liquid Limit X─────────⚫─────────△

[FINES CONTENT %]

BOTTOM OF CASING

LOSS OF CIRCULATION

CALIBRATED PENETROMETER

WL (First Encountered)

WL (Completion)

WL (Estimated Seasonal High Water)

WL (Stabilized)

Fill

Possible Fill

Probable Fill

Rock

GENERALIZED SUBSURFACE PROFILE

Section line A-A'

IHS Modular Building Indian Health Service

1515 NE Lawrie Tatum Road, lawton, Oklahoma, 73507 Project No: 58:1771 Date: 12/27/2023

*B -0

EOB @ 15.00

Topsoil

CL

*B -0

EOB @ 15.00

Topsoil

CL

TYPICAL DETAIL

DIAGRAM

REFER TO MEP AND/OR CIVIL

DRAWINGS FOR TYPICAL BEDDING

MATERIALS AT EXTERIOR FACE OF

BUILDING. REPLACE BEDDING

MATERIALS WITH SITE CLAY SOIL.

EXTEND CLAY 2 FEET FROM BUILDING.

PLACE IN 8" MAX. LOOSE LIFTS.

COMPACT TO 92% OF STANDARD

PROCTOR (ASTM D-698), ABOVE

OPTIMUM MOISTURE CONTENT.

UTILITY TRENCH

UNDERGROUND UTILITY

ENGINEER SCALE

CLAY PLUG AT DRAFTSMAN PROJECT NO.

UTILITY TRENCH

CLL

REVISIONS SHEET

DATE

NTS

11/7/08

APPENDIX B – Field Operations

Reference Notes for Boring Logs

Subsurface Exploration Procedure: Standard Penetration Testing (SPT) Boring Logs B-01 to B-02

REFERENCE NOTES FOR BORING LOGS

MATERIAL1,2

1Classifications and symbols per ASTM D 2488-17 (Visual-Manual Procedure) unless noted otherwise.

2To be consistent with general practice, “POORLY GRADED” has been removed from GP, GP-GM, GP-GC, SP, SP-SM, SP-SC soil types on the boring logs.

3Non-ASTM designations are included in soil descriptions and symbols along with ASTM symbol [Ex: (SM-FILL)].

4Typically estimated via pocket penetrometer or Torvane shear test and expressed in tons per square foot (tsf).

5Standard Penetration Test (SPT) refers to the number of hammer blows (blow count) of a 140 lb. hammer falling 30 inches on a 2 inch OD split spoon sampler required to drive the sampler 12 inches (ASTM D 1586). “N-value” is another term for “blow count” and is expressed in blows per foot (bpf). SPT correlations per 7.4.2 Method B and need to be corrected if using an auto hammer.

6The water levels are those levels actually measured in the borehole at the times indicated by the symbol. The measurements are relatively reliable when augering, without adding fluids, in granular soils. In clay and cohesive silts, the determination of water levels may require several days for the water level to stabilize. In such cases, additional methods of measurement are generally employed.

7Minor deviation from ASTM D 2488-17 Note 14.

8Percentages are estimated to the nearest 5% per ASTM D 2488-17.

Reference Notes for Boring Logs (09-02-2021).doc © 2021 ECS Corporate Services, LLC. All Rights Reserved

COHESIVE SILTS & CLAYS

UNCONFINED

COMPRESSIVE

STRENGTH, QP4

<0.25

0.25 - <0.50

0.50 - <1.00

1.00 - <2.00

2.00 - <4.00

4.00 - 8.00

>8.00

SPT5

(BPF)

CONSISTENCY7

(COHESIVE)

GRAVELS, SANDS & NON-COHESIVE SILTS

SPT5

DENSITY

<5 5 - 10

11 - 30 31 - 50

>50

Very Loose Loose

Medium Dense Dense

Very Dense

WATER LEVELS6

RELATIVE

AMOUNT7

Trace

With

Adjective (ex: “Silty”)

COARSE

GRAINED

(%)8

<5

FINE

GRAINED

(%)8

<5

DRILLING SAMPLING SYMBOLS & ABBREVIATIONS

PARTICLE SIZE IDENTIFICATION

DESIGNATION PARTICLE SIZES

Hollow Stem Auger Power Auger (no sample) Bulk Sample of Cuttings Wash Sample Shelby Tube Sampler Split Spoon Sampler

Rock Quality Designation % Rock Sample Recovery % Rock Core, NX, BX, AX Rock Bit Drilling Pressuremeter TestSS

ST

WS

BS

PA

HSA

RQD

PM

RD

RC

REC

Boulders Cobbles

Gravel:

Sand:

Silt & Clay (“Fines”) Fine Medium

Coarse Fine Coarse

0.074 mm to 0.425 mm (No. 200 to No. 40 sieve) <0.074 mm (smaller than a No. 200 sieve)

0.425 mm to 2.00 mm (No. 40 to No. 10 sieve)

2.00 mm to 4.75 mm (No. 10 to No. 4 sieve)

4.75 mm to 19 mm (No. 4 sieve to ¾ inch) ¾ inch to 3 inches (19 mm to 75 mm) 3 inches to 12 inches (75 mm to 300 mm) 12 inches (300 mm) or larger

>50 31 - 50 16 - 30

9 - 15 5 - 8 2 - 4 <2

Very Hard Hard

Very Stiff

Stiff Firm Soft

Very Soft

ASPHALT

CONCRETE

GRAVEL

TOPSOIL

VOID

BRICK

AGGREGATE BASE COURSE

GW

GP

GM

GC

SW

SP

SM

SC

ML

MH

CL

CH

OL

OH

PT

WELL-GRADED GRAVEL

gravel-sand mixtures, little or no fines

POORLY-GRADED GRAVEL

gravel-sand mixtures, little or no fines

SILTY GRAVEL

gravel-sand-silt mixtures

CLAYEY GRAVEL

gravel-sand-clay mixtures

WELL-GRADED SAND

gravelly sand, little or no fines

POORLY-GRADED SAND

gravelly sand, little or no fines

SILTY SAND

sand-silt mixtures

CLAYEY SAND

sand-clay mixtures

SILT

non-plastic to medium plasticity

ELASTIC SILT

high plasticity

LEAN CLAY

low to medium plasticity

FAT CLAY

high plasticity

ORGANIC SILT or CLAY non-plastic to low plasticity

ORGANIC SILT or CLAY high plasticity

PEAT

highly organic soils

WL (First Encountered)

WL (Completion)

WL (Seasonal High Water)

WL (Stabilized)

FILL POSSIBLE FILL PROBABLE FILL ROCK

FILL AND ROCK

25 - 45

10 - 20

30 - 45

10 - 25

SUBSURFACE EXPLORATION PROCEDURE:

STANDARD PENETRATION TESTING (SPT)

ASTM D 1586

Split-Barrel Sampling

Standard Penetra on Tes ng, or SPT, is the most frequently used subsurface explora on test performed worldwide. This test provides samples for iden fica on purposes, as well as a measure of penetra on resistance, or N-value. The N-Value, or blow counts, when corrected and correlated, can approximate engineering proper es of soils used for geotechnical design and engineering purposes.

• Involves driving a hollow tube (split-spoon) into the ground by dropping a 140-lb hammer a height of 30-inches at desired depth

• Recording the number of hammer blows required to drive split-spoon a distance of 18-24 inches (in 3 or 4 Increments of 6 inches each)

• Auger is advanced* and an addi onal SPT is per-formed

• One SPT typically performed for every two to five feet. An approximate 1.5 inch diameter soil sam-ple is recovered.

*Drilling Methods May Vary— The predominant drilling methods used for SPT are open hole fluid rotary drilling and hollow-stem auger drilling.

SPT Procedure:

DE

PT

H (F

T)

SA

M

PL

E

N U

M

BE

R

S-1

S-2

S-3

S-4

S-5

SA

M

PL

E

TY

PE

SS

SS

SS

SS

SS

SA

M

PL

E

DI

ST

IN

RE

CO

VE

RY

(I N

DESCRIPTION OF MATERIAL

Topsoil Thickness[6"] (CL) LEAN CLAY, dark brown to reddish brown, moist, s to very s to s

END OF BORING AT 15.00 FT

W

AT

ER

L

EV

EL

S

EL

EV

AT

IO

N (F

T)

BL

O

W S/

6" (N

Va lu e)

5-7-7 (14)

8-9-13 (22)

6-7-9 (16)

4-6-8 (14)

4-5-7 (12)

186.9

16.4

18.5

[87.3%]

CLIENT:

Indian Health Service

PROJECT NAME:

IHS Modular Building

PROJECT NO.: BORING NO.: SHEET:

58:1771 B-01

1122.00

DRILLER/CONTRACTOR:

Drilling Services of Oklahoma

SITE LOCATION:

1515 NE Lawrie Tatum Road, lawton, Oklahoma, 73507

LOSS OF CIRCULATION

LATITUDE:

34.626735

LONGITUDE:

-98.383979

STATION: SURFACE ELEVATION:

BOTTOM OF CASING

THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL

WL (First Encountered)

WL (Comple on)

WL (Seasonal High Water)

WL (Stabilized)

Dry

Dry

BORING STARTED:

BORING

COMPLETED:

EQUIPMENT:

CME 750

Nov 13 2023

Nov 13 2023

LOGGED BY:

MOY

CAVE IN DEPTH:

HAMMER TYPE:

DRILLING METHOD:

Auto

Solid Stem Auger

GEOTECHNICAL BOREHOLE LOG

STANDARD PENETRATION

BLOWS/FT

20 40 60 80 100

ROCK QUALITY DESIGNATION &

RECOVERY

RQD

REC

LIQUID LIMIT

PLASTIC LIMIT

CALIBRATED PENETROMETER

TSF

1 2 3 4 5

WATER CONTENT %

[FINES CONTENT] %

10 20 30 40 50

DE

PT

H (F

T)

SA

M

PL

E

N U

M

BE

R

S-1

S-2

S-3

S-4

S-5

SA

M

PL

E

TY

PE

SS

SS

SS

SS

SS

SA

M

PL

E

DI

ST

IN

RE

CO

VE

RY

(I N

DESCRIPTION OF MATERIAL

Topsoil Thickness[6"] (CL) LEAN CLAY, dark brown to reddish brown, moist, s to very s to s

END OF BORING AT 15.00 FT

W

AT

ER

L

EV

EL

S

EL

EV

AT

IO

N (F

T)

BL

O

W S/

6" (N

Va lu e)

4-4-5 (9)

8-11-12 (23)

7-9-13 (22)

5-7-10 (17)

4-6-8 (14)

14.6

11.5

16.4

[93.6%]

CLIENT:

Indian Health Service

PROJECT NAME:

IHS Modular Building

PROJECT NO.: BORING NO.: SHEET:

58:1771 B-02

1122.00

DRILLER/CONTRACTOR:

Drilling Services of Oklahoma

SITE LOCATION:

1515 NE Lawrie Tatum Road, lawton, Oklahoma, 73507

LOSS OF CIRCULATION

LATITUDE:

34.626610

LONGITUDE:

-98.384213

STATION: SURFACE ELEVATION:

BOTTOM OF CASING

THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL

WL (First Encountered)

WL (Comple on)

WL (Seasonal High Water)

WL (Stabilized)

Dry

Dry

BORING STARTED:

BORING

COMPLETED:

EQUIPMENT:

CME 750

Nov 13 2023

Nov 13 2023

LOGGED BY:

MOY

CAVE IN DEPTH:

HAMMER TYPE:

DRILLING METHOD:

Auto

Solid Stem Auger

GEOTECHNICAL BOREHOLE LOG

STANDARD PENETRATION

BLOWS/FT

20 40 60 80 100

ROCK QUALITY DESIGNATION &

RECOVERY

RQD

REC

LIQUID LIMIT

PLASTIC LIMIT

CALIBRATED PENETROMETER

TSF

1 2 3 4 5

WATER CONTENT %

[FINES CONTENT] %

10 20 30 40 50

219.0

APPENDIX C – Laboratory Testing

Laboratory Testing Summary

LL PL PI

Maximum

Density (pcf)

Optimum Moisture

B-01 S-1 1.0 2.5 1.5 6.9 CL 36 18 18 87.3

B-01 S-3 6.0 7.5 1.5 16.4 B-01 S-5 13.5 15.0 1.5 18.5 B-02 S-1 1.0 2.5 1.5 14.6 B-02 S-2 3.5 5.0 1.5 11.5 B-02 S-3 6.0 7.5 1.5 9.0

Notes:

Definitions:

Project No.:

Project Name:

PM:

PE:

Phone:

Printed On:

ECS Southwest, LLP - Oklahoma City 7801 N Robinson Ave, Suite D-8, Oklahoma City, OK 73116

58:1771 IHS Modular Building Mercy Osayomore Young Andy Wilshire December 27, 2023 405-265-5501

Percent Passing No. 200 Sieve4

Moisture - Density (Corr.)5

CBR

Value6

Organic Content

1. ASTM D 2216, 2. ASTM D 2487, 3. ASTM D 4318, 4. ASTM D 1140, 5. See test reports for test method, 6. See test reports for test method

MC: Moisture Content, Soil Type: USCS (Unified Soil Classification System), LL: Liquid Limit, PL: Plastic Limit, PI: Plasticity Index, CBR: California Bearing Ration, OC: Organic Content (ASTM D 2974)

Laboratory Testing Summary

Sample Source

Sample Number

Start Depth (feet)

End Depth (feet)

Sample Distance

(feet)

MC1

Soil

Type2

Atterberg Limits3

B-02 S-4 8.5 10.0 1.5 16.4

CL 46 21 25 93.6