Attachment 3_Shorthorn Geo. Tech. Report_FHTX_16JUL20.pdf

North Fort Hood Drainage Improvements- Shorthorn Fort Hood, Texas

100 Percent Submittal

100 Percent Design Submittal January 22, 2020

APPENDIX VIII

GEOTECHNICAL REPORT

6200 Savoy Drive, Suite 600, Houston, TX 77063 Phone 832.251.8200 Fax 832.251.8201 info@kenallinc.com

November 18, 2019

US Army Corps of Engineers Fort Worth District, South Western Division 819 Taylor Street, Fort Worth, Texas, 76102

Attention: Mr. Cameron Cornett, P.G.

Project Design Manager

Re: Geotechnical Investigation Report NFH OPTION 1 Drainage Improvements Shorthorn and Longhorn Airstrips, Fort Hood, TX Contract No.: W9126G-17-D-0017 Task Order No.: W9126G18F0396 Kenall Project No. 8030-ii

Dear Mr. Cornett:

Kenall is pleased to submit this geotechnical investigation report for the above referenced project. The geotechnical investigation was conducted in accordance with the referenced NFH task orders.

This report briefly describes the testing procedures employed in our investigation, presents the field exploration and laboratory testing results, and provides the conclusions and recommendations of our studies. Engineering analyses were performed to develop geotechnical design recommendations for this project, and to provide guidelines for the earthworks during construction.

We appreciate the opportunity to work with you on this phase of the project. If you have any question concerning the report or require additional information, please do not hesitate to contact the either of the undersigned.

Very Truly Yours, Kenall (TBPE Registration # F-5366)

DRAFT

Rajesh Tolikonda, P.E.

Project Manager

Srujan Chikyala, P.E.

Project Engineer Copies Submitted: (1)

Project No.8030-ii

TABLE OF CONTENTS

1.0 INTRODUCTION

2.0 PROJECT DESCRIPTION

3.0 PURPOSE AND SCOPE

4.0 FIELD EXPLORATION

5.0 LABORATORY TESTING

6.0 GENERAL SUBSURFACE CONDITIONS

6.1 General Geology

6.2 Soil Conditions- Shorthorn Airstrip

6.3 Soil Conditions- Longhorn Airstrip

7.0 Groundwater Conditions

8.0 RECOMMENDATIONS AND REQUIREMENTS

8.1 Earthwork Materials

8.2 Erosion Control Recommendations for Open Channel

8.3 Site Drainage

8.4 Design Review

9.0 LIMITATIONS

LIST OF ATTACHMENTS

1.0 INTRODUCTION

This report presents the results and analysis of the geotechnical investigation performed by Kenall for the proposed drainage improvements for Shorthorn and Longhorn Airstrips in North Fort Hood (NFH) at Fort Hood, TX. The proposed project consists of various drainage improvements on NFH base.

2.0 PROJECT DESCRIPTION

The project consisted of the repair of various drainage components and proposing required improvements for NFH at Fort Hood, TX. The proposed project components include installing larger culverts at runways, taxiways, driveway and roadway crossings, constructing trapezoidal earthen ditches, and installation of new storm drain lines.

3.0 PURPOSE AND SCOPE

The purpose of this geotechnical study is to explore soil and groundwater conditions at the subject site, as well as performing field and laboratory tests to aid in engineering analyses for developing geotechnical design recommendations for NFH drainage improvements at Fort Hood, Texas.

The scope of services for this project includes, but is not necessarily limited to:

Drilling Seventeen (17) soil borings up to a depth of 10 feet within the project area to evaluate the subsurface stratigraphy and groundwater conditions.

Performing pertinent laboratory tests pursuant to prescribed American Society of Testing and Materials (ASTM) standards and local practices to evaluate the physical and engineering properties of subsurface soils.

Reviewing the field and laboratory data and conducting engineering analyses to develop guidelines for design and construction recommendations.

The scope of services did not include an environmental assessment for determining the presence or absence of wetlands, or hazardous or toxic materials in the soil, surface water, groundwater, or air that is on, below, or around the site. Any statements in this report or on the boring logs regarding odors, colors, and unusual or suspicious items or conditions are strictly for informational purposes. Prior to development of this site, an environmental assessment is advisable.

A geologic fault study to evaluate the possibility of surface faulting at this site was beyond the scope of this investigation.

4.0 FIELD EXPLORATION

The field portion of this study was conducted on August 27 and 28, 2019 at the project location, Fort Hood, TX. The subsurface soil conditions were explored by advancing and sampling seventeen (17) soil borings. All the borings were drilled to a depth of ten (10) feet. Borings S-1 through S-10 were drilled in Shorthorn Airstrip; borings L-1 through L-7 were drilled in Longhorn Airstrip. The approximate boring location is shown on the Boring Location Plan, Plate No. 1, attached to the end of this report.

Sample depths, soil stratum descriptions, and soil classifications (Based on the ASTM Unified Soil Classification System) are presented on the attached Boring Logs, in Appendix A. A key to the terms and symbols used on the boring logs are also shown in Appendix A.

Disturbed samples of subsurface soils were obtained by using the split spoon sampling procedure in general accordance with ASTM D1586, Standard Test Method for Standard Penetration Test (SPT) and Split-Barrel Sampling of Soils. The samples of subsurface materials were obtained by using a split spoon sampler with a two-inch outside diameter, 1.375-inch inside diameter, and a 21-inch barrel, as a part of standard penetration test. The test was performed by driving the sampler into the soil by repeated blows on a 140-pound hammer dropped thirty (30) inches. The number of hammer blows required to advance the sampler twelve (12) inches (after seating) was recorded for each standard penetration test on the appropriate boring log.

Undisturbed samples of the soil were obtained at two-foot intervals continuously to a depth ten (10) feet. Samples of the soil were obtained by means of three-inch outer diameter Shelby tube sampler. All undisturbed samples were extruded mechanically from the Shelby tubes in the field, wrapped in aluminum foil, and sealed in a plastic bag to prevent moisture loss and disturbance. All the samples were transported to our geotechnical laboratory for examination, testing, and analysis.

5.0 LABORATORY TESTING

The soil samples retained from the soil borings were examined and classified by either a geotechnical engineer or a senior technician in our laboratory. Laboratory tests were then performed on selected soil samples as directed by the geotechnical engineer in accordance with prescribed ASTM standards. Representative soil samples recovered from the borings were subjected to laboratory testing for identification, moisture content, grain-size distribution, and Atterberg limits. The accumulative test results are presented in Appendix C. The laboratory test results are also presented graphically in Appendix B which include: Plasticity Chart, Moisture content values are shown with respect to depth, Atterberg limits test results respect to depth.

The tests results were then used to evaluate physical and engineering properties of the soils so that recommendations for the engineering design and earthwork construction could be developed. Detailed test results for each boring are shown on the attached Boring Logs in Appendix A.

6.0 GENERAL SUBSURFACE CONDITIONS

6.1 General Geology

Fort Hood lies within the Central Texas Section of the Great Plains physiographic province. The topographic features of the area are those of a dissected plateau characterized by buttes and mesas. Approximately 30 miles southeast of Fort Hood, the dissected plateau topography gives way to the moderate or rolling relief of the Gulf Coastal Plain. The Balcones fault zone is, roughly, the dividing line of the two physiographic provinces. The uppermost primary stratum underlying Fort Hood is the Walnut Formation of the Comanche Series, Cretaceous age. The Walnut Formation is composed of gray-black, calcareous clay shales alternating with beds of chalky, nodular limestone and shell conglomerates.

6.2 Soil Conditions- Shorthorn Airstrip

The site is fairly level. The surface consisted of grass at the time of our investigation.

The specific subsurface stratigraphy determined by our field exploration is shown in detail on the attached boring logs. However, Shorthorn Airstrip stratigraphy can be generalized as follows:

S:1 (Along Longhorn Road outside Shorthorn Airstrip) From ground level to a depth of 10 feet in boring S:1, the soil consists of tan, very stiff to very stiff low plasticity Sandy Lean Clay with embedded limestone fragments.

S:2 (South End of West Taxiway) From ground level to a depth of 8 feet in boring S:2, the soil consisted of dark brown and brown, stiff to very stiff low plasticity Sandy Lean Clay with limestone fragments.

From the depth of 8 feet to 10 feet, a layer of tan, medium dense Silty Sand with clay pockets is encountered.

S:3 (Between East Taxiway and Runway, at the North End) From ground level to a depth of 2 feet in boring S:3, the soil consisted of dark brown, stiff high plasticity Sandy Fat Clay with some organics. From 2 feet to a depth of 8 feet, the soil consisted of dark brown, stiff to very stiff high plasticity Sandy Fat Clay with limestone fragments and calcareous nodules.

S:4 (Right Side of East Taxiway, at the North End) From ground level to a depth of 10 feet in boring S:4, the soil consisted of dark gray and brown, hard high plasticity Fat Clay with Sand. Some organics were encountered at a depth of 2 feet and limestone fragments were encountered at a depth of around 8 feet.

S:5 (Between East Taxiway and Runway) From ground level to a depth of 10 feet in boring S:5, the soil consisted of dark gray and brown, hard high plasticity Fat Clay with Sand with some organics. Limestone fragments were encountered at a depth of around 8 feet.

S:6 (South End of East Taxiway and Runway) From ground level to a depth of 6 feet in boring S:6, the soil consisted of brown, hard low plasticity Sandy Lean Clay with limestone fragments. From depth of 6 feet to a depth of 10 feet, reddish and light tan, loose to medium dense Sand was encountered.

S:7 (Between East Taxiway and Runway) From ground level to a depth of 6 feet in boring S:7, the soil consisted of brown, hard low plasticity Sandy Lean Clay with limestone fragments. From depth of 6 feet to a depth of 10 feet, reddish and light tan, loose to medium dense Sand with some clay was encountered.

S:8 (West side of West Taxiway, North End) From ground level to a depth of 6 feet in boring S:8, the soil consisted of brown, hard high plasticity Sandy Fat Clay and Fat Clay with Sand, with limestone fragments. From depth of 6 feet to a depth of 10 feet, dark brown, hard Lean Clay with limestone fragments was encountered.

S:9 (Between West Taxiway and Runway, North End) From ground level to a depth of 2 feet in boring S:9, the soil consisted of dark gray, hard low plasticity Sandy Lean Clay with organics. From depth of 2 feet to a depth of 10 feet, a layer of dark brown, hard Fat Clay with Sand with limestone fragments.

Some Sand material is encountered at a depth of 9 feet.

S:10 (Between West Taxiway and Runway, South End) From ground level to a depth of 8 feet in boring S:8, the soil consisted of dark brown and brown, stiff to very stiff low plasticity Sandy Lean Clay with limestone fragments.

From the depth of 8 feet to 10 feet, a layer of tan, medium dense Sand with clay pockets is encountered.

6.3 Soil Conditions- Longhorn Airstrip

The site is relatively level. The surface consisted of grass at the time of our investigation. The specific subsurface stratigraphy determined by our field exploration is shown in detail on the attached boring logs. However, Longhorn Airstrip stratigraphy can be generalized as follows:

L:1 (Along the Entrance Road) From ground level to a depth of 2 feet in boring L:1, the soil consisted of brown, medium dense Clayey Sand with organics. From 2 feet to a depth of 8 feet, soil consisted of stiff to hard low plasticity Sandy Lean Clay with some organics. From 8 feet to a depth of 10 feet, reddish brown, medium dense Clayey Sand is encountered.

L:2 (Along the Entrance Road) From ground level to a depth of 2 feet in boring L:2, the soil consisted of brown, medium dense Silty Clayey Sand with some clay pockets. From 2 feet to a depth of 8 feet, the soil consisted of reddish brown, loose to medium dense Silty Sand. From 8 feet to a depth of 10 feet, the soil consisted of reddish brown, stiff low plasticity Sandy Lean Clay.

L:3 (Along the Entrance Road) From ground level to a depth of 10 feet in boring L:3, the soil consisted of brown, stiff to very stiff Sandy Lean Clay.

L:4 (Along the Entrance Road) From ground level to a depth of 2 feet in boring L:4, the soil consisted of brown, medium dense Silty Sand. From 2 feet to a depth of 10 feet, the soils consisted of brown and gray, stiff to very stiff, low plasticity Sandy Lean Clay.

L:5 (Along the Entrance Road) From ground level to a depth of 4 feet in boring L:5, the soil consisted of brown, medium dense Silty Sand. From 4 feet to a depth of 10 feet, the soils consisted of brown and gray, stiff to very stiff, low plasticity Sandy Lean Clay.

L:6 From ground level to a depth of 2 feet in boring L:6, the soil consisted of brown, medium dense Silty Sand. From 2 feet to a depth of 10 feet, the soils consisted of brown and gray, stiff to very stiff, low plasticity Sandy Lean Clay.

L:7 (West of Runway) From ground level to a depth of 2 feet in boring L:7, the soil consisted of brown, medium dense Clayey Sand. From 2 feet to a depth of 10 feet, the soils consisted of brown and gray, stiff to very stiff, low plasticity Sandy Lean Clay.

7.0 Groundwater Conditions

Ground water was not encountered in all soil borings during the drilling operation. It should be noted that the groundwater table may be expected to fluctuate with environmental variations, such as frequency and magnitude of rainfall, and at the time of year when construction begins.

Since groundwater level variations are anticipated, design drawings and specifications should incorporate such possibilities and provide for dewatering, as required, during construction.

8.0 RECOMMENDATIONS AND REQUIREMENTS

The recommendations in this report are based on the subsoil conditions encountered in the field exploration and laboratory testing.

8.1 Earthwork Materials

Satisfactory Materials Satisfactory materials include materials classified in ASTM D 2487 as GW, GM, GC, SW, SP, SM, SC and shall be free of trash, debris, roots or organic matter or stones larger than 3 inches in any dimension.

Unsatisfactory Materials Unsatisfactory materials include materials classified in ASTM D 2487 as PT, OH, CL, CH, ML, and MH and any other materials not defined as satisfactory.

Cohesionless and Cohesive Materials Cohesionless materials include materials classified in ASTM D 2487 as GW, GP, SW, and SP. Cohesive materials include materials classified as GC, SC, ML, CL, MH, and CH. Materials classified as GM and SM will be identified as cohesionless only when fines are nonplastic.

Compaction Method Compaction for all fill and subgrade materials specified herein shall be in accordance with modified proctor compaction method, ASTM D 1557.

8.2 Erosion Control Recommendations for Open Channel

If any sandy, silty and loose soils are encountered, these soils may trigger slope failures. Therefore, we recommend that proper erosion control measures be provided.

The following recommendations should be used for erosion control of exposed sandy/silty or loose soils on the slopes.

Over-excavate any unsatisfactory soil if present and replace them with lean clays (PI > 20) and fat clays (measured perpendicular to the exposed surface), placed under controlled conditions i.e., in 6-inch compacted lifts at a minimum of 95% of the maximum dry density of the soil, in accordance ASTM D1557.

Provide erosion control measures by immediately initiating vegetative growth.

8.3 Site Drainage

It is recommended that site drainage be well developed. Drainage is important from the standpoint of soil stability.

8.4 Design Review

Review of the design and construction plans, as well as the specifications, should be performed by Kenall before release. The review is aimed at ensuring that the geotechnical design recommendations and construction criteria presented in this report have been properly interpreted. Design review is not within the scope of work authorized in this study. Should you elect to retain Kenall to perform a design review, additional fees would be applicable.

9.0 LIMITATIONS

This report is prepared for the exclusive use of USACE, and the design team for the specific application to the improvements of Shorthorn Airstrip and Longhorn Airstrip drainage in North Fort Hood at Fort Hood, TX. Our report was prepared in accordance with generally accepted geotechnical engineering practice common to the local area.

No other warranty, express or implied, is made.

The analyses and recommendations contained in this report are based on the data obtained from our subsurface exploration. The borings indicate subsurface conditions only at the specific locations and time, and only to the depths penetrated. The borings do not necessarily reflect strata variations that may exist in subsurface conditions within the site. The validity of the recommendations is based in part on assumptions about the stratigraphy made by the Geotechnical Engineer. Such assumptions may be confirmed only during earthwork and construction. If subsurface conditions during construction differ from those described here, the recommendations in this report must be reevaluated.

If any changes in the nature, design, or location of the project are planned, the conclusions and recommendations contained in this report should not be considered valid unless the changes are reviewed, and the conclusions of this report are modified or verified in writing by Kenall. Kenall is not responsible for any claims, damages, or liability associated with subsequent interpretation of subsurface data, or reuse of the subsurface data or engineering analyses without expressed written authorization of Kenall.

LIST OF ATTACHMENTS

The following illustrations are attached to this report:

Appendix # Illustrations

Appendix A Boring Locations

Log of Borings Key to Terms and Symbols on Boring Logs

Appendix B Plasticity Chart Moisture Content vs Depth Chart Moisture Content vs Atterberg Limits Chart

Appendix C Laboratory Test Results Table