Revised Geotech Report - VA Renovation and Additions.pdf

Prepared by:

GSI Engineering, LLC A UES Company (UES) 4503 East 47th Street South Wichita, Kansas 67210

(316) 554-0725

Prepared for:

H2B, Inc.

1225 North Loop West, Suite 800 Houston, Texas 77008

GEOTECHNICAL EXPLORATION REPORT

VA Renovation and Additions 5500 East Kellogg Avenue

Wichita, Kansas

UES Project No. 23W1339.01 June 3, 2024

I hereby certify that this engineering document was prepared by me or under my direct personal supervision and that I am a duly licensed Professional Engineer under the laws of the State of Kansas.

Colin D. Parker, P.E. Date

My license renewal date is April 30, 2025.

Sections covered by this seal: Sections 1 through 6 and all pages included as appendices within this bound document.

6/3/2024 June 3, 2024

CPARKER

Kansas PE Stamp

Geotechnical-Engineering Report

Geotechnical Services Are Performed for Specific Purposes, Persons, and Projects Geotechnical engineers structure their services to meet the specific needs of their clients. A geotechnical-engineering study conducted for a civil engineer may not fulfill the needs of a constructor — a construction contractor — or even another civil engineer. Because each geotechnical- engineering study is unique, each geotechnical-engineering report is unique, prepared solely for the client. No one except you should rely on this geotechnical-engineering report without first conferring with the geotechnical engineer who prepared it. And no one

— not even you — should apply this report for any purpose or project except the one originally contemplated.

Read the Full Report Serious problems have occurred because those relying on a geotechnical-engineering report did not read it all. Do not rely on an executive summary. Do not read selected elements only.

Geotechnical Engineers Base Each Report on a Unique Set of Project-Specific Factors Geotechnical engineers consider many unique, project-specific factors when establishing the scope of a study. Typical factors include: the client’s goals, objectives, and risk-management preferences; the general nature of the structure involved, its size, and configuration; the location of the structure on the site; and other planned or existing site improvements, such as access roads, parking lots, and underground utilities. Unless the geotechnical engineer who conducted the study specifically indicates otherwise, do not rely on a geotechnical-engineering report that was:

Typical changes that can erode the reliability of an existing geotechnical-engineering report include those that affect:

• the function of the proposed structure, as when it’s changed from a parking garage to an office building, or from a light-industrial plant to a refrigerated warehouse;

• the elevation, configuration, location, orientation, or weight of the proposed structure;

As a general rule, always inform your geotechnical engineer of project changes—even minor ones—and request an assessment of their impact. Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not consider developments of which they were not informed.

Subsurface Conditions Can Change A geotechnical-engineering report is based on conditions that existed at the time the geotechnical engineer performed the study. Do not rely on a geotechnical-engineering report whose adequacy may have been affected by: the passage of time;

man-made events, such as construction on or adjacent to the site; or natural events, such as floods, droughts, earthquakes, or groundwater fluctuations. Contact the geotechnical engineer before applying this report to determine if it is still reliable. A minor amount of additional testing or analysis could prevent major problems.

Most Geotechnical Findings Are Professional Opinions Site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. Geotechnical engineers review field and laboratory data and then apply their professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ — sometimes significantly — from those indicated in your report. Retaining the geotechnical engineer who developed your report to provide geotechnical-construction observation is the most effective method of managing the risks associated with unanticipated conditions.

A Report’s Recommendations Are Not Final Do not overrely on the confirmation-dependent recommendations included in your report. Confirmation-dependent recommendations are not final, because geotechnical engineers develop them principally from judgment and opinion. Geotechnical engineers can finalize their recommendations only by observing actual subsurface conditions revealed during construction. The geotechnical engineer who developed your report cannot assume responsibility or liability for the report’s confirmation-dependent recommendations if that engineer does not perform the geotechnical-construction observation required to confirm the recommendations’ applicability.

A Geotechnical-Engineering Report Is Subject to Misinterpretation Other design-team members’ misinterpretation of geotechnical-engineering reports has resulted in costly

Important Information about This

Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes.

While you cannot eliminate all such risks, you can manage them. The following information is provided to help.

problems. Confront that risk by having your geotechnical engineer confer with appropriate members of the design team after submitting the report. Also retain your geotechnical engineer to review pertinent elements of the design team’s plans and specifications. Constructors can also misinterpret a geotechnical-engineering report. Confront that risk by having your geotechnical engineer participate in prebid and preconstruction conferences, and by providing geotechnical construction observation.

Do Not Redraw the Engineer’s Logs Geotechnical engineers prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical-engineering report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable, but recognize that separating logs from the report can elevate risk.

Give Constructors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can make constructors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation.

To help prevent costly problems, give constructors the complete geotechnical-engineering report, but preface it with a clearly written letter of transmittal. In that letter, advise constructors that the report was not prepared for purposes of bid development and that the report’s accuracy is limited;

encourage them to confer with the geotechnical engineer who prepared the report (a modest fee may be required) and/ or to conduct additional study to obtain the specific types of information they need or prefer. A prebid conference can also be valuable. Be sure constructors have sufficient time to perform additional study. Only then might you be in a position to give constructors the best information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions.

Read Responsibility Provisions Closely Some clients, design professionals, and constructors fail to recognize that geotechnical engineering is far less exact than other engineering disciplines. This lack of understanding has created unrealistic expectations that have led to disappointments, claims, and disputes. To help reduce the risk of such outcomes, geotechnical engineers commonly include a variety of explanatory provisions in their reports. Sometimes labeled “limitations,” many of these provisions indicate where geotechnical engineers’ responsibilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly.

Environmental Concerns Are Not Covered The equipment, techniques, and personnel used to perform an environmental study differ significantly from those used to perform a geotechnical study. For that reason, a geotechnical-engineering report does not usually relate any environmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated environmental problems have led to numerous project failures. If you have not yet obtained your own environmental information, ask your geotechnical consultant for risk-management guidance. Do not rely on an environmental report prepared for someone else.

Obtain Professional Assistance To Deal with Mold Diverse strategies can be applied during building design, construction, operation, and maintenance to prevent significant amounts of mold from growing on indoor surfaces.

To be effective, all such strategies should be devised for the express purpose of mold prevention, integrated into a comprehensive plan, and executed with diligent oversight by a professional mold-prevention consultant. Because just a small amount of water or moisture can lead to the development of severe mold infestations, many mold- prevention strategies focus on keeping building surfaces dry. While groundwater, water infiltration, and similar issues may have been addressed as part of the geotechnical- engineering study whose findings are conveyed in this report, the geotechnical engineer in charge of this project is not a mold prevention consultant;

none of the services performed in connection with the geotechnical engineer’s study were designed or conducted for the purpose of mold prevention. Proper implementation of the recommendations conveyed in this report will not of itself be sufficient to prevent mold from growing in or on the structure involved.

Rely, on Your GBC-Member Geotechnical Engineer for Additional Assistance Membership in the Geotechnical Business Council of the Geoprofessional Business Association exposes geotechnical engineers to a wide array of risk-confrontation techniques that can be of genuine benefit for everyone involved with a construction project. Confer with you GBC-Member geotechnical engineer for more information.

8811 Colesville Road/Suite G106, Silver Spring, MD 20910 Telephone: 301/565-2733 Facsimile: 301/589-2017 e-mail: info@geoprofessional.org www.geoprofessional.org

Copyright 2015 by Geoprofessional Business Association (GBA). Duplication, reproduction, or copying of this document, or its contents, in whole or in part, by any means whatsoever, is strictly prohibited, except with GBA’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document as a complement to or as an element of a geotechnical-engineering report. Any other firm, individual, or other entity that so uses this document without being a GBA member could be commiting negligent or intentional (fraudulent) misrepresentation.

TABLE OF CONTENTS

Page No.

1. INTRODUCTION

1.1 General

1.2 Project Description

2. FIELD EXPLORATION

3. SITE CONDITIONS

3.1 Regional Geology

3.2 Surface Conditions

3.3 Subsurface Conditions

3.4 Groundwater Conditions

3.5 Seismic Site Classification and Seismic Design Parameters

4. LABORATORY TESTING

5. CONCLUSIONS AND RECOMMENDATIONS

5.1 General Geotechnical Considerations

5.2 Earthwork

5.2.1 Site Preparation

5.2.2 General Structural Fill

5.2.3 Low Volume Change Material (LVC)

5.2.4 Chemical Stabilization of Soil

5.2.5 Compaction of Engineered Structural Fills

5.2.6 Utility Trench Backfill

5.2.7 Foundation Backfill

5.2.8 Correction of Unsuitable Foundation Soils

5.2.9 Excavation Slopes

5.2.10 Rock Excavation

5.3 Foundations

5.3.1 Shallow Foundations

5.4 Floor Slabs

5.4.1 Slab-on-Grade Floors

5.4.2 Basement Level Floor Slabs

5.5 Pavement Recommendations

5.5.1 Pavement Subgrade Preparation

5.5.2 Recommended Design Sections

5.5.3 Asphaltic Cement Concrete Pavement Construction

5.5.4 General Pavement Considerations

5.6 Below Grade Walls

5.6.1 Lateral Earth Pressures

5.6.2 Perimeter Drainage

5.7 Surface Drainage and Landscaping

5.8 Construction Considerations

5.9 Construction Observation and Quality Assurance

6. CLOSING REMARKS AND LIMITATIONS

APPENDICES

Appendix A - General Vicinity Map

Boring Location Plan Appendix B - Boring Logs

Key to Symbols Legend & Nomenclature Unified Soil Classification System (USCS) Rock Descriptors CPT Soundings CPT Description

Appendix C - Field & Laboratory Test Results Appendix D - Chemical Corrosivity Test Results

Wichita, Kansas

UES Project No. 23W1339.01 – Revision 1 June 3, 2024

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1. INTRODUCTION

1.1 General

This report summarizes the findings of our geotechnical exploration for the proposed additions and renovations at the Robert J. Dole VA Medical Center in Wichita, Kansas. The scope of work was outlined in our proposal dated January 23, 2024. Mr. Jame Alexander, Ph.D., P.E. of H2B, Inc.

authorized this exploration on January 30, 2024.

The purpose of this geotechnical study is to explore the subsurface conditions at the proposed site with exploratory borings, evaluate the engineering properties of the subsurface materials with appropriate field and laboratory tests, and perform engineering analyses for developing design and construction recommendations for the proposed project.

1.2 Project Description

The proposed project will be located at the existing Robert J. Dole VA Medical Center in Wichita, Kansas. We understand the development will consist of renovation efforts to several existing buildings, the expansion and reconfiguration of two existing parking lots, and the construction of a new three-story building addition. We understand that the new three-story building will be of steel construction with CMU non-load bearing walls and a concrete slab-on-grade floor and will be supported on shallow foundations. We understand that the structure will have maximum column and continuous wall loads on the order of 85 kips and 6 kips per linear foot, respectively.

We also understand that an interior vault structure within the existing Building 3 will be expanded, and that foundation recommendations are required.

We anticipate that the pavements will support predominately light passenger cars with less frequent medical emergency vehicles, panel delivery vans, passenger vans, and trash trucks.

We assume site grading required to bring the building pad, solar arrays, and new parking lots to the desired elevations may include fills up to 2 feet and cuts of up to 5 feet. Please contact us if site

2024 ©GSI Engineering, LLC a UES™ Company (UES) Page | 2 grading will vary from this estimate so that we may evaluate and adjust our recommendations if necessary.

A site plan is included in Appendix A for reference.

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2. FIELD EXPLORATION

We drilled nine borings for this geotechnical exploration between February 15 and February 23, 2024, with a CME-45 and CME-75 truck-mounted drilling rig using 4-inch diameter continuous flight augers and 2.25/3.25-inch inside diameter hollow stem augers. We drilled two borings in the proposed solar array/northern parking lot area and two borings within the new building footprint to depths of approximately 30 feet below the site grade at the time of our exploration. We drilled one boring near the existing Building 3 to a depth of approximately 50 feet below the current site grade. We drilled four borings in the southern parking/drive areas to a depth of approximately 5 feet below the site grade at the time of our exploration.

We selected boring locations based on a preliminary boring location plan provided by Mr. Alexander in his request for proposal, as well as a site visit by Kaleb Meyer, I.G. Our boring locations were selected, marked, and cleared of utilities using Ground Penetrating Radar (GPR) prior to the commencement of drilling.

Boring locations in relation to existing and proposed features are indicated on the Boring Location

Plan included in Appendix A. The boring locations should be considered accurate only to the degree implied by the methods used in their determination.

We interpolated ground surface elevations at the boring locations using elevations obtained from ground surface profiling provided by Google Earth. The ground surface elevations at the borings are shown on the boring logs included in Appendix B. The boring elevations should be considered accurate only to the degree implied by the methods used in their determination.

Our drill crew obtained soil samples at the intervals shown on the boring logs in Appendix B.

Recovered samples were sealed in plastic containers, labeled, and protected for transportation to the laboratory for further examination, testing, and classification.

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We obtained split-barrel samples (designated “Split Spoon” or “S” samples) while performing

Standard Penetration Tests (SPT) with a 1-3/8 inch I.D. thick-walled sampler, driven using an automatic hammer in general accordance with ASTM D1586, “Penetration Test and Split-Barrel

Sampling of Soils.” The “N” value, reported in blows per foot (bpf), equals the number of blows required to drive the sampler through the last 12 inches of the 18-inch sample interval using a 140-pound hammer falling 30 inches.

We obtained undisturbed samples (designated “Shelby Tube” or “U” samples) with 3-inch O.D. thin-walled tube samplers, hydraulically pushed in general accordance with ASTM D1587, “Thin-Walled

Tube Sampling of Soils for Geotechnical Purposes.”

In addition to our auger borings, we also performed Cone Penetration Testing (CPTu) at two locations near the existing Building 4 to depths of approximately 20 feet below the current site grade. The

CPTu testing was performed in general accordance with ASTM D5778, "Performing Electric Friction

Cone and Piezocone Penetration Testing of Soils". The termination depth is measured to the center of the friction sleeve because the sleeve friction is needed for soil behavior type estimates and the pore pressure dissipation depths are measured to the tip. The tip stress, sleeve friction, and pore pressure readings are provided with the CPT results in Appendix B.

Our drilling personnel prepared field boring logs during drilling operations. These field logs report drilling and sampling methods, sampling intervals, groundwater measurements and the subsurface conditions we encountered. At the conclusion of drilling, our drill crew made groundwater measurements, backfilled the borings and CPT voids in accordance with Kansas state regulations, and patched the surface of the concrete and asphalt borings with quick-set concrete and asphalt cold patch, respectively.

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3. SITE CONDITIONS

3.1 Regional Geology

The project site lies within the Wellington-McPherson Lowlands region of south-central Kansas. The topography in this region is typified by flat alluvial plains. Soil stratigraphy generally comprises

Pleistocene Age sand, silt and gravel transported by runoff from the High Plains to the north. The upper portions of the soil profile, to depths of up to 100 feet, typically contain more clay than the adjacent Arkansas River Lowlands and are loess-mantled in some areas. In the project area, the surficial soils are underlain by the Wellington Shale of the Permian bedrock system.

3.2 Surface Conditions

The project site comprises the areas immediately surrounding the existing Building 3 and Building 4 on the VA Medical Center campus, as well as the northwestern and southern parking/drive areas. The northwestern-most portion of the site is currently occupied by a contractor’s lot. The construction areas immediately adjacent to Building 3 and Building 4 exhibit minimal elevation change, with less than 1 foot of difference across the proposed building footprints. The northwestern parking lot slopes gently downgradient from southeast to northwest away from the hospital buildings, with a total difference in elevation of approximately 3 feet. The southern parking areas exhibit significant elevation change, sloping downgradient to the east, west, and south from the crest near Building 3, with a total difference of approximately 14 feet.

3.3 Subsurface Conditions

Although we observed some variability, the subsurface materials we encountered within the depths of exploration generally comprised 6 inches of topsoil or asphalt, gravel, or concrete pavement overlying fill materials consisting of lean to fat clay with varying amounts of sand and clayey sand, which in turn are underlain by weathered shale bedrock. General descriptions of the strata we encountered are presented below, while more detailed subsurface information is presented on the boring logs located in Appendix B. Please note that the indicated depths are relative to the site grade at the time of our exploration.

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Stratum 1

We encountered fill materials consisting of lean to fat clay with varying amounts of sand and clayey sand in each of our soil borings except B-2, underlying the surficial pavements and topsoil, and extending to depths between approximately 3.5 and 8.5 feet below the site grade at the time of our exploration.

The lean to fat clay with varying amounts of sand fill materials (lean clay, lean clay with sand, sandy lean clay, fat clay, and fat clay with sand) were generally described as shades of brown, yellowish brown, and grayish brown to gray and moist. We measured Standard Penetration Test (SPT) N-values between 6 and 19 blows per foot (bpf) in the clay fill materials, indicating a medium stiff to very stiff condition.

The clayey sand fill materials were generally described as brown and dark brown to dark grayish brown and moist to very moist. We measured an SPT N-value of 7 bpf in the clayey sand fill materials, indicating a loose condition.

Stratum 2

We encountered shale bedrock in each of our soil borings, except B-7, underlying the fill materials and extending to the termination depths of the borings at approximately 5, 30, and 50 feet below the site grade at the time of our exploration. This material was generally described as shades of olive and dark gray, decomposed to highly weathered, very soft to soft rock. We measured SPT N-values between 7 bpf and 84 blows for 10 inches of sampler penetration (84/10”) and an unconfined compressive strength of 3.61 kips per square foot (ksf), indicating the shale bedrock within the depths of expected excavation will likely exhibit characteristics similar to that of a medium stiff to hard, highly plastic clay material.

3.4 Groundwater Conditions

Our drill crew made water level observations during drilling, after drilling, and after the advancement of our soundings to evaluate groundwater conditions. We also extrapolated apparent groundwater

2024 ©GSI Engineering, LLC a UES™ Company (UES) Page | 7 levels from pore pressures generated during CPT soundings. Based on these observations, we anticipate an average groundwater depth between 9.5 and 23.5 feet below site grade.

The variation in groundwater is likely due to the presence of sand lenses and/or desiccation cracks in portions of the softer shale material that can transport water laterally. Additionally, the slow percolation rate of the on-site fat clay and shale can cause water to pond or become perched for extended time periods. Excavations that encounter the sand seams or desiccation cracks may flood and require dewatering.

The groundwater conditions we observed during our exploration program should not be construed to represent an absolute or permanent condition. Uncertainty is involved with short-term water level observations in boreholes.

The free groundwater surface or groundwater table within unconfined aquifers is generally a subdued reflection of surface topography. Water generally flows downward from upland positions (recharge zones) to low lying areas or surface water bodies (discharge zones). As such, the groundwater level and the amount and level of any perched water on the site may be expected to fluctuate with variations in precipitation, site grading, drainage and adjacent land use. Long-term monitoring utilizing piezometers or observation wells is required to evaluate the potential range of groundwater conditions.

3.5 Seismic Site Classification and Seismic Design Parameters

We understand that seismic site classification and seismic design parameters are required for this project and that the determination of these classifications and design parameters is to be performed in accordance with the VA Handbook H-18-8, Seismic Design Requirements.

In place of a full seismic survey, which includes drilling at least one boring to a depth of 100 feet below site grade and the subsequent collection of downhole seismic data, we performed one boring

2024 ©GSI Engineering, LLC a UES™ Company (UES) Page | 8 to a depth of 50 feet to facilitate seismic hazard estimations and design analysis for the site, as well as utilizing CPT data from the top 20 feet of the on-site materials.

In conjunction with our analysis of the boring logs, CPT correlations, and laboratory test data for this project, we have also reviewed other geologic data from the general area available to us for further information on the soils extending to a depth of 100 feet below the existing grade.

Based on the above resources, we estimate that the weighted average N-value for soil and rock across this depth is greater than 15 but less than 50 blows per foot (bpf). As defined in Chapter 20 and 21 of ASCE 7-22 as well as the 2021 version of the International Building Code, this building site is assigned a Site Class of D. We have also, reviewed the IBC 2021 and the ASCE 7 Hazard Tool resources for information regarding ground motion and seismic site coefficients.

Based on these resources, the following site classifications, spectral response accelerations, seismic site coefficients, design response accelerations, and seismic design categories have been tabulated below and may be used for seismic design.

Table 3.5-1 Seismic Design Parameters

It is possible that more a detailed seismic site survey, including directly measuring the shear wave velocity of the subsurface soils, may yield a higher seismic site classification for structural design.

Please contact UES for additional information regarding shear wave velocity profiling.

Structure Risk Category

Seismic Site Class

Spectral Response

Acceleration, Short Period

(Ss)

Spectral Response

Acceleration, at Period of 1 s (S1)

Spectral Response

Acceleration, Short Period, 5% Damped

(SDS)

Spectral Response

Acceleration, at Period of

1s, 5% Damped

(SD1)

3-Story Building IV D 0.120 0.061 0.110 0.087

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4. LABORATORY TESTING

Our engineering staff reviewed the field boring logs to outline the depth, thickness and extent of the soil strata. The samples taken from the borings were examined in our laboratory and visually classified in general accordance with ASTM D2488, “Description and Identification of Soils (Visual-

Manual Procedure).” We established a testing program to evaluate the engineering properties of the recovered samples. A UES technician performed laboratory testing in general accordance with the following current ASTM test methods:

• Moisture Content (ASTM D2216, “Laboratory Determination of Water (Moisture) Content of Soil and Rock”)

• Unit Weight (ASTM D7263, “Laboratory Determination of Density (Unit Weight) of Soil

Specimens”)

• Atterberg Limits (ASTM D4318, “Liquid Limit, Plastic Limit, and Plasticity Index of Soils”)

• Minus No. 200 Sieve Wash (ASTM D1140, “Amount of Material in Soils Finer Than the No.

200 (75-μm) Sieve”)

• Unconfined Compressive Strength (ASTM D2166, “Unconfined Compressive Strength of

Cohesive Soil”)

• One-Dimensional Consolidation (ASTM D2435, “One-Dimensional Consolidation

Properties of Soils”)

Laboratory test results are presented on the boring logs in Appendix B and tabulated in Appendix C.

Moisture content and unit weight tests were used to evaluate the existing moisture-density condition of the soils. The Atterberg limits and Minus No. 200 sieve tests were used to help classify the soils under the Unified Soils Classification System. The Atterberg limits were also used to evaluate the plasticity characteristics of the soils. Unconfined compression tests were used to define the stress-strain characteristics and related shear strength of the soils. The one-dimensional consolidation tests assessed the load-settlement relationship of the soil.

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The following data summarize our laboratory test results. We used these data to develop the allowable bearing values, anticipated settlements, and other geotechnical design criteria for the project.

• Natural Moisture Content ............................................................................. 10.3 to 34.3%

• Wet Density.............................................................................................................. 129.7 lb/ft3

• Dry Density ............................................................................................................... 111.7 lb/ft3

• Unconfined Compressive Strength ............................................................... 3.61 kips/ft2

• Liquid Limit..................................................................................................................... 28 to 74

• Plastic Limit .................................................................................................................... 13 to 22

• Plasticity Index .............................................................................................................. 15 to 53

• Percent Passing the No. 200 Sieve ............................................................. 40.2 to 69.2%

• Standard Penetration Test (SPT ’N’ blows per foot) ................................. 6 to 84/10”

Based on the results of this testing program, we reviewed and supplemented the field logs to arrive at the final logs as presented in Appendix B. The final logs represent our interpretation of the field logs and reflect the additional information obtained from the laboratory testing. Stratification boundaries indicated on the boring logs were based on observations made during drilling, an extrapolation of information obtained by evaluating samples from the borings, and comparisons of similar engineering characteristics. Locations of these boundaries are approximate and the transitions between soil types may be gradual rather than clearly defined.

We also selected samples at various depths and at various locations throughout the project site for corrosivity and chemical attack analyses. The results of the chloride content, sulfate content, pH, electrical resistivity, and oxidation-reduction potential tests performed are tabulated in Appendix D.

The following table presents our evaluation of the sulfate contents of the subsurface soils and the corresponding exposure levels and cement types as specified by ACI.

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Table 4-1: Summary of Cement Required for Concrete Exposure to Sulfates in Soils

Based on the results of our chemical analysis of the on-site soils within the project area, the soils generally exhibit a negligible to moderate amount of sulfate exposure to concrete. The most prominent sulfate exposure was observed south of the existing building 3 (boring B-5).

Sample Identification

Water-Soluble Sulfate in Soil

(PPM)

Sulfate Exposure

Level Cement Type

Maximum Water- Cementitious

Material Ratio, by Mass

Minimum Design Compressive

Strength (psi)

B-1, S-3 107.0 Negligible No Spec. No Spec. No Spec.

B-2, S-4 162.0 Negligible No Spec. No Spec. No Spec.

B-4, S-4 270.0 Negligible No Spec. No Spec. No Spec.

B-5, S-2/S-3 1095.0 Moderate Type II 0.50 4,000

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5. CONCLUSIONS AND RECOMMENDATIONS

5.1 General Geotechnical Considerations

The soils we encountered in the test borings are generally capable of supporting the anticipated loads of the proposed building additions on shallow foundations. We did not encounter groundwater within the depth of expected excavation near the building footprint areas.

The near-surface clay fill materials we encountered at the site vary in plasticity and sand content, but generally classify as moderately to highly plastic and may be susceptible to changes in strength and volume (shrink/swell) with changes in moisture content. These soils are not recommended for direct support of floor slabs or pavements, unless chemically stabilized as outlined later in this report.

5.2 Earthwork

5.2.1 Site Preparation

Adjacent foundations and structures that will remain must be protected (where applicable) while performing excavations and soil improvement programs. Roof drains and stormwater drainage from these structures as well as the surrounding area should be directed away from the proposed construction area.

We recommend that any existing utilities within the proposed building area be relocated to avoid passing beneath the new structure. Abandoned utility pipes that cannot be removed must be plugged with grout to reduce the potential for future collapse or moisture migration into the subgrade soils. Excavations resulting from utility removal must be replaced with engineered structural fill as outlined in Section 5.2.6.

Any trees within the areas to be prepared for development must be removed. The root-balls and surrounding soils containing observable organic material must also be removed. We expect the root-balls will extend to substantially greater depths than the topsoil stripping depth. The root-ball excavations must be filled with an engineered structural fill that is placed, moisture conditioned and compacted in accordance with Section 5.2.5.

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In preparing the site for construction, existing pavements, surface vegetation and topsoil containing a significant percentage of organic matter should be removed from the areas beneath structures and any other areas that are to be paved, cut or receive fill. The removal depth for this site is expected to be approximately 6 inches. However, the removal depth should be monitored during stripping and adjusted as required. This material should either be removed from the site or stockpiled for later use in landscaping of unpaved or non-structural areas.

Prior to fill placement, the top 9 inches of the ground surface in fill areas should be scarified, moisture conditioned and recompacted in accordance with Section 5.2.5 to eliminate a plane of weakness along the contact surface.

The subgrade should be proof rolled with a loaded tandem axle dump truck or equivalent (loaded water truck, loaded concrete mixer or motor grader with a minimum weight of 20 tons). A proof-roll is considered acceptable if no ruts greater than one inch deep appear behind the loaded vehicle, and no pumping or weaving is observed as the wheels pass over the area. Any soft or unsuitable areas should be compacted or removed and replaced with stable fill material similar in composition to the surrounding soils. If necessary, clean materials such as crushed concrete or crushed stone may be used to stabilize areas where wet soil or water is present. Geogrid or structural geotextile may be used in conjunction with crushed concrete or stone to provide additional stabilization.

Subgrade areas immediately adjacent to existing foundations, inside of existing structures, or in otherwise difficult to access areas for proof-rolling equipment may be evaluated using bearing probe testing. We recommend that bearing probe tests be performed by a quality assurance technician from UES under the direction of a registered professional engineer.

Whether in cut or fill, the final subgrade surface must be maintained in a stable condition at the moisture content and level of compaction identified in Section 5.2.5. Verification and maintenance of the completed subgrade may require scarification, moisture conditioning, recompaction, and proof rolling.

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Excavations performed near existing structures must not compromise the integrity or support of the existing foundation elements. Shoring, bracing, underpinning or other methods of maintaining foundation integrity may be required.

5.2.2 General Structural Fill

General structural fill may be used for mass site grading, landscaping applications or as utility trench backfill outside of building areas. General structural fill may also be used to within 12 inches of the base of any granular cushion beneath floor slabs and to within 12 inches of the base of any vehicular or pedestrian pavements. In the former applications, low volume change materials are required immediately below the floor slabs or pavements (low volume change material is discussed in the following section).

Granular materials could be used as general structural fill but may present a higher potential for shrink/swell of the underlying expansive clay. If granular material is selected, it should be well graded, have a maximum particle size of 1.5 inches, and meet KDOT freeze/thaw durability and sulfate soundness requirements.

Where granular materials are placed over less permeable or expansive soils, they should be constructed with edge drains or other drainage methods to prevent the ponding or collection of water in the granular layer. Off-site material used as general structural fill should have a liquid limit

(LL) of less than 50 and a plastic index (PI) of less than 30.

If free of organic matter or debris, the on-site clay soils may be reused as general structural fill within the areas outlined above. The shale bedrock material should not be used as general structural fill.

5.2.3 Low Volume Change Material (LVC)

Low volume change (LVC) material as specified for use below floor slabs and pavements must consist of granular material or cohesive soil with a liquid limit (LL) less than 40 and a plasticity index (PI) between 10 and 20.

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Granular material could be used as LVC but may retain or pond water on the underlying expansive clay and present a higher potential for volume changes due to shrink and swell. If granular material is selected as LVC, the material must have sufficient cohesion to form a compactable, uniform, and stable subgrade. This typically translates to a material with greater than 15 percent fines (percent passing the No. 200 sieve) and a maximum particle size of 1.5 inches. Silty gravel (such as KDOT AB-

3), crushed concrete with a maximum particle size of 1.5 inches, or limestone screenings are also acceptable LVC materials. Granular materials with less than 15 percent fines may be used within confined areas such as within foundation stem walls. LVC materials should be free of organic matter or debris.

If granular materials are used as LVC and are placed over less permeable or expansive soils, they should be constructed with edge drains or other drainage methods to prevent the ponding or collection of water in the granular layer.

The on-site soils we encountered within the depths of our exploration are not considered LVC material as defined in this section, unless chemically stabilized as outlined below.

5.2.4 Chemical Stabilization of Soil

The moderately to highly plastic clay soils and decomposed shale materials we encountered in this exploration are considered moisture sensitive and may lose strength and undergo volume changes with fluctuations in moisture content. The on-site plastic clay soils and shale are not suitable for use as LVC material without chemical stabilization. Chemical stabilization may be achieved by amending the soil with 14 to 16 percent class “C” fly ash, 6 to 8 percent cement kiln dust (CKD), or 3 to 5 percent

Portland cement.

We recommend a laboratory standard Proctor Moisture-Density Relationship (ASTM D698, “Laboratory Compaction Characteristics of Soil Using Standard Effort”) be performed prior to field mixing using a sample of the soil to be stabilized and the proposed amendment (fly ash, CKD or

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Portland cement). The sample should be prepared in advance to match the intended field mix proportions, using the same amendment source as will be utilized in the field.

Fly Ash Stabilization Prior to the introduction of fly ash, the soil material should be thoroughly pulverized to reduce clods to ½ inch or less. During the pulverization process, we recommend that water be added to reach a moisture content at or above the optimum moisture content as determined by ASTM D698 for the proposed fly ash-soil mixture. The fly ash should remain dry and be protected from external sources of moisture during transportation and storage. Fly ash material that is introduced to moisture prior to incorporation with the soil must be discarded.

The fly ash and soil should be thoroughly mixed within ½ hour after introduction. The moisture content should be field tested immediately following mixing and adjusted as needed to maintain a range between optimum and 4 percent above optimum. The fly ash-soil mixture should not be allowed to air dry. If the moisture content is determined to be in excess of 4 percent of optimum, additional fly ash should be applied to achieve the specified moisture content. Compaction of the fly ash supplemented soil should be completed within 2 hours after incorporation. Additional compaction after 2 hours may cause degradation of the soil strength. The fly ash-soil mixture should be compacted as noted in Section 5.2.5.

Fly ash mixing should not be performed at ambient air temperatures below 50 degrees Fahrenheit.

Cement Kiln Dust Cement kiln dust can also be used as a soil stabilization agent and should be incorporated into the soils using the procedures outlined for fly ash stabilization. Cement kiln dust may be used at temperatures below 50 degrees Fahrenheit, provided the soil to be amended is frost-free.

Portland Cement Type I/II Portland cement can be used as a soil stabilization agent using dry application methods as outlined above, or by injection of a liquefied cementitious mixture (A.K.A. Super Slurry) into the soil

2024 ©GSI Engineering, LLC a UES™ Company (UES) Page | 17 to be treated. Cement treatment and mixing can be performed at temperatures below 50 degrees

Fahrenheit, provided the soil to be amended is frost-free.

Stabilized Subgrade Maintenance Stabilized soil that will be utilized as floor slab subgrade should not be allowed to freeze prior to floor slab placement. Stabilized soil that will be utilized as pavement subgrade should be covered with a minimum of 3.5 inches of asphalt or the full Portland cement concrete pavement section prior to being subjected to freezing conditions. If paving/slab placement does not immediately follow soil stabilization, the supplemented soil should be protected from extreme weather, kept moist, and minimally trafficked until slab placement occurs. In areas that are to be paved, an asphalt prime coat could be applied over the stabilized material surface as an alternative to periodic moisture additions to maintain acceptable moisture throughout curing.

If the stabilized subgrade deteriorates prior to paving or slab placement, we recommend any unstable areas be scarified and recompacted. We recommend an additional 3 percent class “C” fly ash be incorporated in areas that are to be scarified and recompacted. Expansive soils stabilized with cement kiln dust or Portland cement may be reworked without additional amendment. Other soil types may require the incorporation of additional cement kiln dust or Portland cement to restore the desired strength characteristics.

5.2.5 Compaction of Engineered Structural Fills

Unless otherwise noted, fill materials should be placed in loose lifts not to exceed 9 inches and be compacted to a minimum of 95 percent of the maximum dry unit weight obtained from ASTM D698

(Standard Proctor). Moisture content at the time of compaction should be controlled to between optimum and 4 percent above optimum moisture content.

Granular fill materials which produce a definable moisture-density curve when tested according to

ASTM D698 should be compacted to a minimum of 95 percent of the maximum dry unit weight obtained from ASTM D698. Granular fill materials which do not produce a definable moisture-density

2024 ©GSI Engineering, LLC a UES™ Company (UES) Page | 18 curve should be compacted to a minimum of 75 percent relative density (ASTM D4253, “Maximum

Index Density and Unit Weight of Soils Using a Vibratory Table” and ASTM D4254, “Minimum Index

Density and Unit Weight of Soils and Calculation of Relative Density”). Granular materials should be placed at a moisture content that will achieve the desired densities. Please note that relative density and standard Proctor tests measure different parameters and are not interchangeable.

In general, proper compaction of cohesive soils can be achieved with sheepsfoot or pneumatic-type compactors, while compaction of granular soils can be achieved with smooth-drum or smooth-plate vibratory compactors. Water flooding is not an acceptable compaction method for any soil type.

5.2.6 Utility Trench Backfill

As a minimum, utility trench backfill material should meet the requirements of general structural fill as defined in Section 5.2.2. Where utility trenches pass beneath the structures, pavements or flatwork, the upper foot of utility backfill should meet the requirements of LVC material as defined in Section

5.2.3. Backfill soils in utility trenches must be placed in lifts of 6 inches or less in loose thickness and be compacted in accordance with Section 5.2.5.

Granular material could be used as utility trench backfill but may retain or pond water on the underlying expansive clay and present a higher potential for volume changes due to shrink and swell.

We recommend that where utility trenches pass beneath the structures, that the use of granular backfill be limited to avoid creating a preferential pathway to the underlying expansive soils. We recommend that clay materials meeting the specifications of LVC material as specified in Section

5.2.3 or flowable fill as described in the following paragraph be used to backfill or plug utility penetrations beneath the structure.

Controlled low strength material (CLSM) or flowable fill may also be used for utility backfills. We recommend designing flowable fill with a compressive strength between 50 and 300 pounds per square inch (psi). CLSM with a maximum compressive strength less than 300 psi can be readily excavated with a backhoe. The intent for the CLSM is to provide a backfill that can be placed in a

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Where used beneath pavements, flatwork or the structures, CLSM should be terminated a minimum of one foot below the structure, floor slab or pavement subgrade elevation. To provide uniform support beneath pavements, flatwork, and the structures, the fill placed over the CLSM should be of similar composition as the surrounding bearing materials and be constructed as moisture-conditioned and compacted engineered structural fill in accordance with Section 5.2.5.

5.2.7 Foundation Backfill

As a minimum, backfill soils for formed foundations should meet the requirements of general structural fill as defined in Section 5.2.2. However, we recommend fill around foundations meet the requirements of LVC material as defined in Section 5.2.3. The use of LVC material to backfill foundations is intended to help reduce lateral swell pressures on the foundation wall and reduce desiccation cracking adjacent to the structure, which can provide a pathway for water to infiltrate the foundation subgrade. If other cohesive materials are used to backfill foundations, the risk of differential movements caused by water infiltration into the foundation subgrade may be increased.

We also recommend the upper 18 inches of exterior foundation backfill have sufficient cohesion to direct surface water away from the structure. Granular materials such as sand and gravel are not suitable for use as exterior foundation backfill in the surficial 18 inches.

Backfill soils around formed foundations must be placed in lifts of 6 inches or less in loose thickness and be moisture conditioned and compacted in accordance with Section 5.2.5. Care should be exercised during compaction to avoid applying excessive stress to the foundation surfaces. Where both sides of a foundation wall are backfilled, the fill should be placed simultaneously in uniform lifts on both sides of the wall to reduce unbalanced lateral loads.

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Any below-grade walls must have sufficient strength and rigidity to resist lateral loads induced during construction and backfill placement. Please refer to Section 5.6.2 for additional information regarding basement wall backfill.

5.2.8 Correction of Unsuitable Foundation Soils

If soft, loose, or otherwise unsuitable soils are encountered at the base of any foundations, an…