4-Geotech Report - Ben Taub Loading Dock Expansion.pdf

GEOTECHNICAL ENGINEERING REPORT

BEN TAUB LOADING DOCK EXPANSION

1504 Ben Taub Loop

Houston, Texas 77030 UES Project No. H251113

September 10, 2025

Prepared for:

POWERS BROWN ARCHITECTURE - HOUSTON

2100 Travis Street, Suite 501

Houston, Texas 77002 Attention: Ms. A.J. Breneman

Prepared by:

4667 Kennedy Commerce Drive Houston, Texas 77032 Ph. (281) 469-3347 Texas Engineering Firm Registration No. F-813

Environmental Geotechnical Engineering

Materials Testing Field Inspections & Code Compliance

Geophysical Technologies

Ms. AJ Breneman Powers Brown Architecture - Houston 2100 Travis Street, Suite 501 Houston, Texas 77002

Re: GEOTECHNICAL ENGINEERING REPORT Ben Taub Loading Dock Expansion 1504 Ben Taub Loop Houston, Texas 77030 UES Project No.H251113

Dear Ms. Breneman:

UES Professional Solutions 44, LLC (hereinafter “UES”), is pleased to submit this Geotechnical Engineering Report for the referenced project. The results of this exploration, together with our recommendations, are presented in the accompanying report, an electronic copy of which is being transmitted herewith. This geotechnical study was authorized by Ms. A.J. Breneman with Powers Brown Architecture and performed in accordance with UES Proposal No. 111270 Revision 2 and change order CO1 dated March 31 and July 1, 2025, respectively.

UES appreciates the opportunity to be of service on this project. If we can be of further assistance, such as providing materials testing services during construction, please contact our office.

Respectfully submitted, UES Professional Solutions 44, LLC

Jumanah A. Hajjat, Ph.D., P.E., PMP® Geotechnical Engineer

Hamed Ardalan, Ph.D., P.E.

Geotechnical Department Manager – Houston Area

TTTA

TABLE OF CONTENTS

Page

1.0 INTRODUCTION

2.0 FIELD EXPLORATION

3.0 LABORATORY TESTING

4.0 SITE CONDITIONS

4.1 General

4.2 Geology

4.3 Soil Conditions

4.4 Groundwater

5.0 ANALYSIS AND RECOMMENDATIONS

5.1 Seismic Site Classification

5.2 Potential Vertical Rise (PVR)

5.3 Construction Excavations

5.4 Groundwater Control

5.5 Earthwork

5.5.1 Site Preparation

5.5.2 Proofroll

5.5.3 Construction Considerations

5.5.4 Grading and Drainage

5.5.5 Wet Weather/Soft Subgrade

5.5.6 Fill

5.5.7 Testing

5.6 Loading on Buried Structures

5.7 Retaining Structures

5.8 Buried Pipe

5.9 Existing Fill

5.10 Existing Abandoned Foundations

5.11 Structural Slab

5.12 Foundation System

5.12.1 Helical Pile Foundation System

5.12.2 Straight Shaft Drilled Piers

5.13 Pavement

5.13.1 Rigid Pavement

5.13.2 Pavement Subgrade

6.0 General Comments

TTTA

APPENDICES

Appendix A - Project Location Diagrams Appendix B - Boring Location Diagram Appendix C - Boring Logs and Laboratory Results Appendix D - Aerial Photographs Appendix E - USGS Topographic Map Appendix F - Site Photographs Appendix G - Geologic Information Appendix H - Unified Soil Classification System

Geotechnical Engineering Report Ben Taub Loading Dock Expansion, Houston, Texas

1.0 INTRODUCTION

Purpose and Scope. The purpose of this geotechnical study was to evaluate some of the physical and engineering properties of subsurface materials at selected locations on the subject site to develop geotechnical engineering design parameters and recommendations for the proposed project. To accomplish this, the scope of this study included field exploration consisting of drilling test borings and collecting samples of the subsurface materials, performing laboratory testing on selected samples obtained during the field exploration, performing engineering analysis and evaluation of the subsurface conditions with respect to the project characteristics, and development of foundation and pavement recommendations suitable for the proposed project. The scope of services did not include an environmental assessment of the site.

Project Location. The project is located at 1504 Ben Taub Loop in Houston, Texas. The general location and orientation of the site are provided in Appendix A - Project Location Diagrams.

Project Description. The project consists of a proposed building addition (footprint ±2,800-square feet), with a canopy structure and private concrete paving areas. Based on the information provided by the structural engineer, we understand that the proposed building addition will utilize a structural slab supported by either helical piles or straight shaft drilled piers.

Site Grading Plan. The site grading plan was unavailable at the time this report was prepared.

Our recommendations provided herein are on the basis that cuts and fills of less than 1 foot will be required to bring the site to grade. In the event cut/fill in the building pad exceeds 1-foot, we should be notified and allowed to review the site grading plan to assess and modify our recommendations, as necessary.

Cautionary Statement Regarding Use of this Report. As with any geotechnical engineering report, this report presents technical information and provides detailed technical recommendations for civil and structural engineering design and construction purposes. UES, by necessity, has assumed the user of this document possesses the technical acumen to understand and properly utilize the information and recommendations provided herein. UES strives to be clear in its presentation and, like the user, does not want potentially detrimental misinterpretation or misunderstanding of this report. Therefore, we encourage any user of this report with questions regarding its content to contact UES for clarification. Clarification will be provided verbally and/or issued by UES in the form of a report addendum, as appropriate.

Ben Taub Loading Dock Expansion, Houston, Texas

Report Specificity. This report was prepared to meet the specific needs of the client for the specific project identified. Recommendations contained herein should not be applied to any other project at this site by the client or anyone else without the explicit approval of UES.

This Report is NOT a Specification. Recommendations in this report are not specifications.

Geotechnical engineering requires significant experience and professional judgment.

Conditions vary in the field which require and/or allow modification to recommendations provided herein at the discretion of the Geotechnical Engineer of Record.

2.0 FIELD EXPLORATION

Subsurface study. The subsurface study for this project is summarized in the following table.

Boring locations are provided in Appendix B - Boring Location Diagram.

Boring Nos. Depth, feet bgs1 Date Drilled Location 3

B-01 and B-02 2 11 4/29/2025 Proposed Addition Area

B-03 and B-04 2 11 and 12 7/23/2025 B-05 and B-06 3 30 7/23/2025 Spaced Across the Site

Notes:

1. bgs = below ground surface.

2. Borings B-01 through B-04 were terminated at depths of approximately 11 to 12 feet below ground surface (bgs) due to auger refusal. Based on information provided by the structural engineer, we understand that the refusal is likely associated with abandoned foundations.

3. Borings B-05 and B-06 were offset to the south due to site accessibility issues.

4. Boring locations provided in Appendix B - Boring Location Diagram were not surveyed and should be considered approximate. Borings were located by recreational hand-held GPS unit. Horizontal accuracy of such units is typically on the order of 20-feet.

Boring Logs. Subsurface conditions were defined using the sample borings. Boring logs generated during this study are included in Appendix C - Boring Logs and Laboratory Results.

Borings were advanced between sample intervals using continuous flight auger drilling procedures.

Cohesive Soil Sampling. Cohesive soil samples were generally obtained using Shelby tube samplers in general accordance with American Society for Testing and Materials (ASTM) D1587. The Shelby tube sampler consists of a thin-walled steel tube with a sharp cutting edge connected to a head equipped with a ball valve threaded for rod connection. The tube is pushed into the undisturbed soil by the hydraulic pulldown of the drilling rig. The soil specimens were extruded from the tube in the field, logged, tested for consistency using a hand penetrometer, sealed, and packaged to maintain "in situ" moisture content.

Consistency of Cohesive Soils. The consistency of cohesive soil samples was evaluated in the field using a calibrated hand penetrometer. In this test a 0.25-inch diameter piston is pushed

Ben Taub Loading Dock Expansion, Houston, Texas into the undisturbed sample at a constant rate to a depth of 0.25-inch. The results of these tests are tabulated at the respective sample depths on the boring logs. When the capacity of the penetrometer is exceeded, the value is tabulated as 4.5+.

Granular Soil Sampling. Granular soil samples were generally obtained using split-barrel sampling procedures in general accordance with ASTM D1586. In the split-barrel procedure, a disturbed sample is obtained in a standard 2-inch outside diameter (OD) split barrel sampling spoon driven 18-inches into the ground using a 140-pound (lb) hammer falling freely 30 inches. The number of blows for the last 12-inches of a standard 18-inch penetration is recorded as the Standard Penetration Test resistance (N-value). The N-values are recorded on the boring logs at the depth of sampling. Samples were sealed and returned to our laboratory for further examination and testing.

Groundwater Observations. Groundwater observations are shown on the boring logs.

Borehole Plugging. Upon completion of the borings, the boreholes were backfilled with onsite soil cuttings from the top and plugged at the surface.

3.0 LABORATORY TESTING

UES performs visual classification and any of several laboratory tests, as appropriate, to define pertinent engineering characteristics of the soils encountered. Tests are performed in general accordance with ASTM or other standards and the results included at the respective sample depths on the boring logs or separately tabulated, as appropriate, and included in Appendix C

- Boring Logs and Laboratory Results. Laboratory tests and procedures routinely utilized, as appropriate, for geotechnical studies are tabulated in the following table.

Test Procedure Description ASTM D1140 Standard Test Methods for Amount of Material in Soils Finer than the No. 200 (75-μm)

Sieve ASTM D1557 Standard Test Methods for Laboratory Compaction Characteristics of Soil Using

Modified Effort ASTM D2166 Standard Test Method for Unconfined Compressive Strength of Cohesive Soil ASTM D2216 Standard Test Method for Laboratory Determination of Water (Moisture) Content of

Soil and Rock by Mass ASTM D2217 Standard Practice for Wet Preparation of Soil Samples for Particle-Size Analysis and

Determination of Soil Constants ASTM D2487 Standard Classification of Soils for Engineering Purposes (Unified Soil Classification

System) ASTM D2488 Standard Practice for Description and Identification of Soils (Visual-Manual Procedure) ASTM D2937 Standard Test Method for Density of Soil in Place by the Drive-Cylinder Method ASTM D4220 Standard Practices for Preserving and Transporting Soil Samples ASTM D4318 Standard Test Methods for Liquid Limit, Plastic Limit and Plasticity Index of Soils

Ben Taub Loading Dock Expansion, Houston, Texas

Test Procedure Description ASTM D4546 Standard Test Methods for One-Dimensional Swell or Settlement Potential of

Cohesive Soils

4.0 SITE CONDITIONS

4.1 General

Review of Aerial Photographs. Historical aerial photographs of the site were reviewed for potential past alterations to the site which could impact geotechnical design conditions.

Specifically, aerial photographs were reviewed to visually assess obvious areas of significant past fill on site. Aerial photographs reviewed for this study are identified in the following table and are included in Appendix D - Aerial Photographs.

Aerial Photographs Reviewed Year Observations Since Prior Aerial Photograph 1953 The site was undeveloped.

2002 The site was developed with paved area.

2006 No visible changes were noted.

2013 No visible changes were noted.

2017 No visible changes were noted.

2021 No visible changes were noted.

2025 No visible changes were noted.

Site Fills Based on Aerial photographs. Aerial photographs indicate that the site was previously developed as paved area, therefore, the presence of fill soil is anticipated. Existing fill recommendations are provided in Section 5.9.

Limitations. Due to the intermittent nature and relatively low resolution of aerial photographs, as well as our lack of detailed information regarding the past land use of the site, our review should not be interpreted as eliminating the possibility of cuts and/or fills on site which could detrimentally affect future construction.

Topography. A United States Geological Survey (USGS) topographic map of the site is provided in Appendix E - USGS Topographic Map. The map indicates that the site is relatively flat.

Site Photographs. Representative photographs of the site at the time of this study are provided in “Appendix F - Site Photographs”. Photographed conditions are consistent with the aerial photographs and topographic map.

Ben Taub Loading Dock Expansion, Houston, Texas

4.2 Geology

Geologic Formation. Based on available surface geology maps and our experience, it appears this site is in the Beaumont Formation, areas predominantly clay, near mapped contact with the Beaumont Formation, areas predominantly sand. A geologic atlas and USGS formation description are provided in “Appendix G - Geologic Information”. Soil within the Beaumont Formation can generally be characterized as clay, silt, and sand and a minor amount of gravel.

Geologic Faults. A review of the attached geologic map indicates the nearest geologic fault is about 4-miles south of the project site. A geologic fault study was beyond the scope of this study.

4.3 Soil Conditions

Stratigraphy. Descriptions of the various strata and their approximate depths and thickness per the Unified Soil Classification System (USCS) are provided on the boring logs included in “Appendix C - Boring Logs and Laboratory Results”. Terms and symbols used in the USCS are presented in “Appendix H - Unified Soil Classification System”. A summary of the stratigraphy indicated by the borings is provided in the following table.

Generalized Subsurface Conditions at Proposed Addition Location (Borings B-01 to B-04)1

Nominal Depth, feet bgs (Except as Noted) General

Description Detailed Description of

Soils/Materials Encountered Top of Layer Bottom of Layer

0 14 to 15 inches

PAVEMENT 8- to 9 inches CONCERTE over STABILIZED SOIL/SILTY

SAND.

14 to 15 inches

11 to 12 FILL Soft to hard FAT CLAY WITH SAND (CH) FILL, and stiff

LEAN CLAY WITH SAND (CL) FILL.

Notes:

1. Boring Termination Depth = 11 and 12 feet bgs.

2. Borings B-01 through B-04 were terminated at 11 to 12 feet below ground surface due to auger refusal.

Ben Taub Loading Dock Expansion, Houston, Texas

Generalized Subsurface Conditions Spaced Across the Site

(Borings B-05 and B-06)1

Nominal Depth, feet bgs (Except as Noted) General

Description Detailed Description of

Soils/Materials Encountered Top of Layer Bottom of Layer

0 13.5 to 14.5 inches

PAVEMENT 7.5- to 8.5 inches CONCERTE over 6-inch SATBILIZED SOIL and SILTY SAND.

13.5 to 14.5 inches

13 to 16 FILL Soft to stiff FAT CLAY WITH SAND (CH) FILL TO LEAN

CLAY WITH SAND (CL) FILL.

13 to 16 30 LEAN CLAY Stiff to very stiff LEAN CLAY WITH SAND (CL).

Note:

1. Boring Termination Depth = 30 feet bgs.

Swell Tests. Swell tests were performed on selected clay soil samples. Swell test details are provided in “Appendix C - Boring Logs and Laboratory Results”. The results of the tests are summarized in the following table.

Boring No.

Avg.

Depth

(ft.)

Initial Moisture

Content, w, Liquid Limit, LL

Plasticity Index, PI

Applied Overburden Stress (psi)

Swell

B-01 7 21 50 31 6.1 0.00 B-02 3 21 53 34 2.6 0.63 B-03 3 24 Not Tested 2.6 0.13 B-03 5 24 45 27 4.3 0.38 B-03 11 24 42 24 9.5 0.00 B-04 7 29 57 36 6.1 0.00

4.4 Groundwater

Groundwater Levels. The test borings were advanced using continuous flight augers and air-rotary drilling methods, with intermittent sampling methods. These dry drilling techniques enable observation of potential groundwater seepage levels. Groundwater levels encountered in the borings during this study are identified in the table below. Depths referenced in this report and in the table below are measured from the existing ground surface at the respective boring location at time of the field exploration.

Boring No. Depth Groundwater Initially Encountered (feet, bgs)

Groundwater Depth after 15 Minutes (feet, bgs)

All Borings (B-01 to B-104) Not Encountered Not Measured

Ben Taub Loading Dock Expansion, Houston, Texas

Long-term Groundwater Monitoring. These groundwater observations are indicative of the groundwater conditions present at the time the borings were drilled. The amount of water in an open borehole largely depends on the permeability of the soil encountered at the boring location. In relatively impervious soils, such as clayey soils, a suitable estimate of the groundwater depth may not be possible, even after several days of observation. Long-term monitoring of groundwater conditions via piezometers or groundwater monitoring wells was not performed during this study and was beyond the scope of this study. Long-term monitoring can reveal groundwater levels materially different than those encountered during measurements taken while drilling the borings.

Groundwater Fluctuations. It is difficult to accurately predict the magnitude of subsurface water fluctuations that might occur based upon short-term observations. Future construction activities may alter the surface and subsurface drainage characteristics of this site. Seasonal variations, temperature, land-use, proximity to water bodies, and recent rainfall conditions may influence the depth to the groundwater. With these considerations UES recommends that the contractor verifies the groundwater elevation before construction starts.

5.0 ANALYSIS AND RECOMMENDATIONS

5.1 Seismic Site Classification

The Site Class assigned for seismic design considers various factors, such as the soil profile (whether it's soil or rock), shear wave velocity, and strength, averaged over a depth of 100 feet. As our borings didn't reach depths of 100 feet, we made determinations under the assumption that the subsurface materials beneath the borehole bottoms resembled those encountered at the termination depth. Following the guidelines outlined in Section 1613.3.2 of the 2018 International Building Code and Table 20.3-1 in the 2010 ASCE-7, we recommend utilizing Site Class D for seismic design purposes at this location.

5.2 Potential Vertical Rise (PVR)

Potential Vertical Rise. Potential Vertical Rise, PVR, is the calculated upward heave of the ground surface due to expansive soils related to weather-related changes in soil moisture in the active zone. PVR only applies to upward movement. The term settlement applies to downward movement related to loads on the soil.

Maintaining consistent moisture content in the soil is the key to minimizing both heave and shrinkage related structural problems. Therefore, building maintenance and control of water are paramount in the performance of a slab-on-grade and shallow foundations.

Please see our recommendations in “Section 5.5.4 - Grading and Drainage” for water control and limit the extreme wetting or drying of the subsurface soils.

Ben Taub Loading Dock Expansion, Houston, Texas

PVR or Equivalent Calculations. The PVR or its equivalent can be estimated in several ways.

UES utilizes the TxDOT method and swell tests to provide the best possible understanding of expected PVR and its variability.

Calculated PVR using TxDOT Method Tex-124-E. PVR calculations were performed in general accordance with the Texas Department of Transportation (TxDOT) Method Tex-124-E. The Tex-124-E method is empirical and is based on the Atterberg limits and moisture content of the subsurface soils. The calculated PVR is an empirical estimate of a soil’s potential for swell based upon the soil’s plasticity index, applied loading (due to structures or overburden), and antecedent moisture condition. The PVR calculated using TxDOT Method Tex-124-E is about 1.5-inches, assuming an average antecedent moisture condition. The calculated PVR is consistent with soil moisture conditions at the time this study was conducted. An 8-feet zone of seasonal moisture variation was used in our analysis based on local experience.

Calculated PVR using Swell Test Results. The equivalent PVR based on the swell test results is about 1-inch. The PVR based on swell test results is dependent on the moisture conditions at the time of testing. An 8-feet zone of seasonal moisture variation was used in our analysis based on local experience.

Soil Moisture Confirmation Prior to Construction. The calculated PVR can vary considerably with prolonged wet or dry periods. We recommend the moisture content for the upper 8- feet (active zone) of soils within the building pad be assessed for consistency with this report prior to construction if:

1. An extended period has elapsed between the performance of this study and construction of the foundation, or

2. Unusually wet or dry weather is experienced between the performance of this study and construction of the foundation.

5.3 Construction Excavations

Applicability. Recommendations in this section apply to short-term construction-related excavations for this project with excavation depths of less than 15 feet. Recommendations provided herein are not valid for any long-term or permanent slopes on-site. Stability of long-term unprotected slopes will require much flatter slopes. Slope protection for excavations greater than 15 feet needs to be designed and sealed by a professional engineer registered in the State of Texas.

Sloped Excavations. All sloped short-term construction excavations on-site should be designed in accordance with Occupational Safety and Health Administration (OSHA) excavation standards. Borings from this study indicated that the soils may be classified per OSHA regulations as Type B from the ground surface to a depth of 15-feet bgs. Short-term

Ben Taub Loading Dock Expansion, Houston, Texas construction excavations may be constructed with a maximum slope of 1:1, horizontal to vertical (H:V), to a depth of 10-feet bgs. If excavations are to be deeper than 15-feet, we should be contacted to evaluate the excavation. Recommendations provided herein are not valid for any long-term or permanent slopes on-site.

Shored Excavations. As an alternative to sloped excavations, vertical short-term construction excavations may be used in conjunction with trench boxes or other shoring systems. Shoring systems should be designed using an equivalent fluid weight of 85 pounds per cubic foot (pcf) above the groundwater table and 105 pcf below the groundwater table. Surcharge pressures at the ground surface due to dead and live loads should be added to the lateral earth pressures where they may occur. Lateral surcharge pressures should be assumed to act as a uniform pressure along the upper 10-feet of the excavation based on a lateral earth coefficient of 0.5.

Surcharge loads set back behind the excavation at a horizontal distance equal to or greater than the excavation depth may be ignored. We recommend that no more than 200-feet of unshored excavation should be open at any one time to prevent the possibility of failure and excessive ground movement to occur. We also recommend that unshored excavations do not remain open for a period of time longer than 24-hours.

Limitations. Recommendations provided herein assume there are no nearby structures or other improvements which might be detrimentally affected by the construction excavation.

Before proceeding, we should be contacted to evaluate construction excavations with the potential to affect nearby structures or other improvements.

Excavation Monitoring. Construction excavations and their related safety are the responsibility of the Contractor. Excavations should be monitored and documented by a competent professional to confirm site soil conditions consistent with those encountered in the borings drilled as part of this study. Discrepancies in soil conditions should be brought to the attention of UES for review and revision of recommendations, as appropriate.

5.4 Groundwater Control

Groundwater was not encountered in the borings during the subsurface study. If groundwater is encountered during excavation, dewatering to bring the groundwater below the bottom of excavations may be required. Dewatering could consist of standard sump pits and pumping procedures, which may be adequate to control seepage on a local basis during excavation.

Supplemental dewatering will be required in areas where standard sump pits and pumping is not effective. Supplemental dewatering could include submersible pumps in slotted casings, well points, or eductors. The contractor should submit a groundwater control plan, prepared by a licensed engineer experienced in that type of work.

Ben Taub Loading Dock Expansion, Houston, Texas

5.5 Earthwork

5.5.1 Site Preparation

In the area of improvements, all concrete, trees, stumps, brush, debris, septic tanks, abandoned structures, roots, vegetation, rubbish, and any other undesirable matter should be removed and properly disposed. All vegetation should be removed, and the exposed surface should be scarified to an additional depth of at least 6 inches. It is the intent of these recommendations to provide a loose surface with no features that would tend to prevent uniform compaction by the equipment to be used.

5.5.2 Proofroll

Building pad and pavement subgrades should be proofrolled with a fully loaded tandem axle dump truck or similar pneumatic-tire equipment to locate areas of loose subgrade. In areas to be cut, the proofroll should be performed after the final grade is established. In areas to be filled, the proofroll should be performed prior to fill placement. Areas of loose or soft subgrade encountered in the proofroll should be removed and replaced with engineered fill, moisture conditioned (dried or wetted, as needed) and compacted in place.

5.5.3 Construction Considerations

Surface Sandier/Siltier Soils. The sandier/siltier soils encountered at and near the ground surface at this site are very susceptible to changes in moisture. The presence of surface water due to precipitation or groundwater may result in a decrease in the ability to compact and work with the soil. It is common for these soils to pump when subjected to high levels of moisture. In addition, these soils located at and near the ground surface will allow surface water to infiltrate until the water becomes perched on a less permeable layer at depth. As such, construction difficulties should be anticipated, especially during the wet season or immediately after rain events. Although having a thin layer of non-plastic or low plasticity soils overlying cohesive soils is typical of this geologic region, our experience suggests that the local contractors find these materials troublesome and can often be the source of change orders, construction delays, and budget over runs. Soils of this type are especially prone to requiring the implementation of wet weather/soft subgrade recommendations provided in this report.

Maintenance of Subgrade during Construction. While the exposed subgrade is expected to remain relatively stable initially, unstable conditions may arise during general construction activities, particularly if the soil is exposed to wet weather conditions and repetitive construction traffic. The use of lighter construction equipment can help minimize disturbance to the subgrade. In the event of unstable conditions, stabilization measures will be necessary.

Ben Taub Loading Dock Expansion, Houston, Texas

After grading is completed, it's crucial to maintain the moisture content of the subgrade before proceeding with the pavement/building slab construction. Minimizing construction traffic over the finished subgrade is advisable. If the subgrade becomes frozen, desiccated, saturated, or disturbed, the affected material should either be removed or treated by scarification, moisture conditioning, and recompaction before the pavement/building slab construction begins. UES should be retained to observe earthwork and to perform necessary tests and observations during subgrade preparation.

5.5.4 Grading and Drainage

Every attempt should be made to limit the extreme wetting or drying of the subsurface soils because swelling and shrinkage of these soils will result. Standard construction practices for providing good surface water drainage should be used. A positive slope of the ground away from any foundation should be provided. Ditches or swales should be provided to carry the run-off water both during and after construction. Stormwater runoff should be collected by gutters and downspouts and should be discharged away from the buildings.

Root systems from trees and shrubs can draw a substantial amount of water from the clay soil at this site, causing the clays to dry and shrink. This could cause settlement beneath grade-supported slabs such as floors, walks and paving. Trees and large bushes should be located a distance equal to at least one-half their anticipated mature height away from grade slabs.

Lawn areas should be watered moderately, without allowing the clay soil to become too dry or too wet.

5.5.5 Wet Weather/Soft Subgrade

Soft and/or wet surface soils may be encountered during construction, especially following periods of wet weather. Wet or soft surface soil can present difficulties for compaction and other construction equipment. If specified compaction cannot be achieved due to soft or wet surface soils, one of the following corrective measures will be required:

1. Removal of the wet and/or soft soil and replacement with select fill,

2. Chemical treatment of the wet and/or soft soil to improve the subgrade stability, or

3. If allowed by the schedule, drying by natural means.

Chemical treatment is usually the most effective way to improve soft and/or wet surface soils.

UES should be contacted for additional recommendations if chemical treatment is planned due to wet and/or soft soils during construction. The treatment depth and chemical reagent type and application rate depend on the site condition during construction.

Ben Taub Loading Dock Expansion, Houston, Texas

5.5.6 Fill

Select Fill. Select fill should consist of soil with a liquid limit of less than 40 and a Plasticity Index between 8 and 20. The select fill should be placed in loose lifts not exceeding 8-inches and should be compacted to at least 95 percent maximum dry density (per ASTM D-698) and at a moisture content between optimum and 4 percent above optimum moisture content.

The subgrade to receive select fill should be scarified to a depth of 6 inches and compacted to 92 to 96 percent of the material’s maximum standard Proctor dry density (ASTM D-698) at a workable moisture level at least 4 percentage points above optimum.

Lime-treated Native Clay Soil. Based on the laboratory testing conducted for this study, the native clay on-site soils will not meet requirements for select fill. As an alternative to importing select fill, the native clay soil may be blended with lime to reduce the plasticity index to meet select fill requirements. Based on our experience, we expect that it will require between 4- and 6-percent lime (by dry unit weight) to reduce the plasticity index of the native clay soils to select fill requirements. Prior to selecting this alternative, lime series tests should be performed to assess the amount of lime required.

General Fill. General fill may be placed in improved areas outside of building pad areas.

General fill should consist of material approved by the Geotechnical Engineer with a liquid limit less than 50. General fill should be placed in loose lifts not exceeding 8-inches and should be uniformly compacted to a minimum of 95 percent maximum dry density (per ASTM D-698) and within ±2 percent of the optimum moisture content.

Fill Restrictions. Select fill and general fill should consist of those materials meeting the requirements stated. Select fill and general fill should not contain material greater than 4-inches in any direction, debris, vegetation, waste material, environmentally contaminated material, or any other unsuitable material.

Unsuitable Materials. Materials considered unsuitable for use as select fill or general fill include low and high plasticity silt (ML and MH), silty clay (CL-ML), organic clay and silt (OH and OL) and highly organic soils such as peat (Pt). These soils may be used for site grading and restoration in unimproved areas as approved by the Geotechnical Engineer. Soil placed in unimproved areas should be placed in loose lifts not exceeding 10-inches and should be compacted to at least 92 percent maximum dry density (per ASTM D-698) and at a moisture content within ±4 percentage points of optimum.

Cautionary Note. It is extremely important that select fill placed within building pad be properly characterized using one or more representative proctor samples. The use of a proctor sample which does not adequately represent the select fill being placed can lead to erroneous compaction (moisture and density) results which can significantly increase the potential for swelling of the select fill. The plasticity index of select fill soils placed during

Ben Taub Loading Dock Expansion, Houston, Texas construction should be checked every day to confirm conformance to the project requirements and consistency with the proctor being utilized.

5.5.7 Testing

Required Testing and Inspections. Field compaction and classification tests should be performed by UES. Compaction tests should be performed in each lift of the compacted material. We recommend the following minimum soil compaction testing be performed: one test per lift per 2,500 square feet (SF) in the area of the building addition, one test per lift per 5,000 SF outside the building, and one test per lift per 100 linear feet of utility backfill. If the materials fail to meet the density or moisture content specified, the course should be reworked as necessary to obtain the specified compaction. Classification confirmation inspection/testing should be performed daily on select fill materials (whether on-site or imported) to confirm consistency with the project requirements. The testing frequency recommended herein can be altered (increased or decreased) at the discretion of the geotechnical engineer of record.

Liability Limitations. Since proper field inspection and testing are critical to the design recommendations provided herein, UES cannot assume responsibility or liability for recommendations provided in this report if construction inspection and/or testing is performed by another party.

5.6 Loading on Buried Structures

Uplift. Buried water-tight structures are subjected to uplift forces caused by differential water levels adjacent to and within the structure. Soils with any appreciable silt or sand content will likely become saturated during periods of heavy rainfall and the effective static water level will be at the ground surface. For design purposes, we recommend the groundwater level be assumed at the ground surface. Resistance to uplift pressure is provided by soil skin friction and the dead weight of the structure. Skin friction should be neglected for the upper 3 feet of soil. A skin friction of 200 pounds per square foot (psf) may be used below a depth of 3 feet.

Lateral Pressure. Lateral pressures on buried structures due to soil loading can be determined using an equivalent fluid weight of 105 pcf. This includes hydrostatic pressure but does not include surcharge loads. The lateral load produced by a surcharge may be computed as 50 percent of the vertical surcharge pressure applied as a constant pressure over the full depth of the buried structure. Surcharge loads located a horizontal distance equal to or greater than the buried structure depth may be ignored.

Vertical Pressure. Vertical pressures on buried structures due to soil loading can be determined using an equivalent fluid weight of 125 pcf. This does not include surcharge loads.

Ben Taub Loading Dock Expansion, Houston, Texas

The vertical load produced by a surcharge may be computed as 100 percent of the vertical surcharge pressure applied as a constant pressure over the full width of the buried structure.

5.7 Retaining Structures

Applicability. UES was not notified of any specific retaining structures in conjunction with this project. Recommendations provided in this section are applicable to structures 5-feet or less in height. Retaining structures more than 5-feet should be brought to the attention of UES for a more detailed assessment. It is imperative that global stability be reviewed by UES on any retaining structure more than 5-feet in height.

At-Rest Lateral Pressure. Lateral pressures on retaining structures due to soil loading can be determined using an equivalent fluid weight of 85 pcf if fill behind the wall is free-draining and above the groundwater table and 105 pcf if fill behind the wall is not free draining or is below the groundwater table. This does not include surcharge loads. This also assumes a horizontal ground surface behind the structure. The lateral load produced by a surcharge may be computed as 50 percent of the vertical surcharge pressure applied as a constant pressure over the full depth of the buried structure. Surcharge loads set back behind the retaining structure at a horizontal distance equal to or greater than the structure height may be ignored.

Lateral Resistance. Resistance to lateral loads may be provided by the soil adjacent to the structure. We recommend using an equivalent fluid weight of 180 pcf for lateral resistance.

The passive resistance should be ignored if the material in front of the wall will be excavated at any time in the future. A coefficient of sliding friction of 0.25 between the retaining structure concrete footings and underlying soil may be combined with the passive lateral resistance. Appropriate safety factors should be utilized by the structural engineer for external stability analyses of the retaining structures.

Bearing Capacity. Assuming a minimum embedment depth of 24-inches into competent undisturbed native soil, an allowable bearing capacity of 1,000 psf may be used for retaining structure footings (using a Factor of Safety of 3).

5.8 Buried Pipe

Applicability. Recommendations in this section are applicable to the design of buried piping placed by open cut methods associated with this project.

Pressure on Buried Pipe. Design recommendations provided in the “Loading on Buried Structures” section of this report apply to buried piping.

Ben Taub Loading Dock Expansion, Houston, Texas

Thrust Restraints. Resistance to lateral forces at thrust blocks will be developed by friction developed along the base of the thrust block and passive earth pressure acting on the vertical face of the block. We recommend a coefficient of base friction of 0.25 along the base of the thrust block. Passive resistance on the vertical face of the thrust block may be calculated using the allowable passive earth pressures presented in the following table.

Allowable Passive Earth Pressure by Material Type Material Allowable Passive Pressure (psf)

Sand 100 x Depth in Feet Native Clay 2,000

Compacted Clay Fill 1,500 Note:

1. Passive resistance should be neglected for any portion of the thrust block within 3 feet of the final site grade. The allowable passive resistance for native clays is based on the thrust block bearing directly against vertical, undisturbed cuts in these materials.

Bedding and Backfill. Pipe bedding and pipe-zone backfill for the water and storm/sanitary sewer piping should be at a minimum meet the requirements of the pipe manufacturer and if applicable in accordance with TxDOT standard specification Item 400 or the local equivalent.

Typical pipe-zone consists of all materials surrounding the pipe in the trench from six (6) inches below the pipe to 12 inches above the pipe.

Trench Backfill. Excavated site soil can be utilized to backfill the trenches above the pipe-zone provided it is not saturated and does not contain organic matter, debris, or other deleterious material. Backfilled soil should be placed in loose lifts not exceeding 8-inches and should be compacted to at least 95 percent maximum dry density (per ASTM D-698) and at a moisture content between optimum and 4 percent above optimum moisture content.

Trench Backfill Settlement. Settlement of backfill should be anticipated. Even for properly compacted backfill, fills in excess of about 10 feet are still subject to settlements over time of up to about 1 to 2 percent of the total fill thickness. This level of settlement can be significant for fills beneath streets and buildings. Therefore, close coordination and monitoring should be performed to reduce the potential for future movement. Increasing the level of compaction will reduce the risk of settlement (but not eliminate). If this risk of backfill settlement is not acceptable, consideration could be given to backfilling portions of the excavation with flexible base material, cement-stabilized sand, or flowable fill. We would be happy to discuss these settlement mitigation alternatives upon request.

Ben Taub Loading Dock Expansion, Houston, Texas

5.9 Existing Fill

Existing fill was encountered at all boring locations, extending to depths of approximately 11 to 16 feet below ground surface (bgs). Auger refusal was encountered in Borings B-01 through B-04 at depths of about 11 to 12 feet bgs. Based on information provided by the structural engineer, we understand that the proposed building addition will be supported on helical piles or straight-shaft drilled piers. Therefore, the existing fill may remain in place.

If a conventional slab-on-grade is selected, UES should be notified so that we can provide additional recommendations for subgrade preparation, fill compaction, and any required stabilization beneath the slab-on-grade.

5.10 Existing Abandoned Foundations

During our field investigation, auger refusal was encountered in Borings B-01 through B-04 at depths of approximately 11 and 12 feet bgs. Based on information from the structural engineer, we understand that the refusal is likely associated with abandoned foundations.

We recommend removing any existing foundations within the planned piles/piers areas to avoid obstructions during installation. Otherwise, foundation elements to remain in place should be surveyed and superimposed on the proposed development plans to determine the potential for obstructions to the planned construction.

5.11 Structural Slab

Based on information from the structural engineer, we understand that the building addition will utilize a structural slab supported on either helical piles or straight drilled shaft piers.

structural floor slab is to be installed, a minimum 8-inch void space between the bottom of the slab or grade beams and the underlying ground surface should be maintained. Utilities and other fixtures below the building should be suspended from the floor and isolated from the active clay soils, and a minimum 8-inch void space should also be provided below the bottom of the utility or fixture. Any fill placed beneath the structural slab for grading purposes may consist of general fill.

5.12 Foundation System

Appropriate Foundation Types. Helical Piles or straight shaft drilled piers are appropriate to the site based on the geotechnical conditions encountered.

Ben Taub Loading Dock Expansion, Houston, Texas

Foundation Determination. We assume that structural loads will be typical for the type and size of proposed building addition/canopy structure. Recommendations for the foundation types are presented below. Final determination of the foundation type to be utilized for this project should be made by the Structural Engineer based on loading, economic factors and risk tolerance.

Foundations Adjacent to Existing Building. Differential movements can occur between the existing building and the proposed addition. Methods should be implemented to allow for differential movement between the foundation system of the existing building and the proposed addition. Further, preventative measures should be taken to avoid damaging or adversely affecting the integrity of the existing foundation system during construction.

Foundations Adjacent to Slopes. Foundations placed too close to adjacent slopes steeper than 5H:1V may experience reduced bearing capacities and/or excessive settlement.

Recommendations provided herein assume foundations are not close enough to adjacent slopes in excess of 5H:1V to be detrimentally affected. Therefore, foundations closer than 5 times the depth of adjacent slopes, pits, or excavations in excess of 5H:1V should be brought to our attention in order that we may review the appropriateness of our recommendations.

Foundation Plans Review. Our office should be contacted to review the foundation plans, details and related structural loads, prior to finalizing the design to check conformance with our geotechnical recommendations.

5.12.1 Helical Pile Foundation System

Applicability. Helical piles may be utilized to stabilize and support the proposed building addition and canopy structure.

Foundation Depth. Due to the extent and depth of nearby excavation, we recommend Helical piles should bear in native soil and should be installed such that the uppermost helix is situated in competent native soil at a depth of at least 18 feet below existing grade.

Bearing Capacity. The helical pile capacity should be determined through a combination of typical bearing capacity analysis, and results of the load tests correlated to helical pile installation torque. We recommend the design capacity of the helical piles be determined by a design-build contractor that specializes in the design and installation of helical piles. The actual design of helical piles including the pile capacity, spacing, helix diameter(s), shaft length, and shaft diameter should be performed by an experienced helical pile contractor or structural engineer. An experienced helical pile contractor should review the data from this report to assess the equipment required to achieve the minimum length and capacity. We do not recommend using vertically installed helical piles to resist lateral loads without approved lateral load test data, as these types of foundations are typically designed to resist axial loads.

Only the horizontal component of the allowable axial load should be considered to resist the

Ben Taub Loading Dock Expansion, Houston, Texas lateral loading and only in the direction of the batter. UES should be retained to observe helical pile installation to verify that proper bearing materials have been encountered during installation.

Design Soil Parameters. We recommend the following soil parameters for the helical pile design based on the subsurface condition encountered at boring locations.

Depth (feet) Soil Type Effective Soil Unit

Weight (pcf) Cohesion

(psf) 0 - 10 FILL/CLAY SOIL 125 Ignore

10 - 18 FILL/CLAY SOIL 65 Ignore

18 - 30 CLAY SOIL 65 1,200

Note.

1. Assumed groundwater depth greater than 10-feet.

5.12.2 Straight Shaft Drilled Piers

Applicability. Straight shaft drilled pier foundations as described in this section are appropriate for the proposed building addition and canopy structure. Straight shaft drilled piers should have adequate length to resist axial, lateral, and uplift forces.

Axial Resistance. For the design of the drilled shaft foundations, we recommend the following geotechnical parameters:

Axial Capacities of Straight Shaft Drilled Piers

Depth (feet) 1 Soil Type Effective Soil Unit

Weight (pcf) 2

Allowable Skin Friction

(psf) 3

Allowable End Bearing Capacity

(psf) 4 & 5 0 - 8 FILL SOIL 125 Ignore Ignore

8 - 18 FILL/CLAY SOIL 65 Ignore Ignore

18 - 25 CLAY 65 500 4,000

Notes:

1. Depth below existing ground surface.

2. Effective soil unit weight based on assumed groundwater depth of 8 feet bgs.

3. Allowable Skin Friction based on a factor of safety = 2.

4. Allowable End Bearing Capacity based on a factor of safety = 3

5. Recommendations assume the foundation depth is greater than or equal to 4 times the foundation width.

6. Axial resistance of straight shaft drilled piers should be ignored up to 5 feet below the top of the drilled piers (bottom of the pier caps).

Ben Taub Loading Dock Expansion, Houston, Texas

Lateral Resistance. For resistance of lateral loads on straight shaft drilled piers, we recommend the following LPILE design parameters.

Depth (feet bgs) 1 LPILE Parameters 2 0 - 5 LPILE Material Type: Clay

Effective Soil Unit Weight: 125 pcf Undrained Cohesion: Ignore Strain @ ½ Peak Strength (ε50): Ignore p-y Modulus (k): Ignore

5 - 8 Soil Type: Medium Clay Effective Soil Unit Weight: 125 pcf Undrained Cohesion: 500 psf Strain @ ½ Peak Strength (ε50): 0.01 p-y Modulus (k): 100 pci (static)

8 - 18 Soil Type: Submerged Medium Clay Effective Soil Unit Weight: 65 pcf Undrained Cohesion: 500 psf Strain @ ½ Peak Strength (ε50): 0.01 p-y Modulus (k): 100 pci (static)

18 - 30 Soil Type: Submerged Stiff Clay Effective Soil Unit Weight: 65 pcf Undrained Cohesion: 1,500 psf Strain @ ½ Peak Strength (ε50): 0.005 p-y Modulus (k): 500 pci (static)

Notes:

1. Depth below existing ground surface.

2. Effective soil unit weight based on assumed groundwater depth of 8 feet bgs.

3. Lateral resistance of straight shaft drilled pier should be ignored up to 5-feet below the top of the piers (bottom of the pier caps).

Uplift. The uplift force on the piers due to swelling of the active clays can be approximated by assuming a uniform uplift pressure of 1,000 psf acting over the perimeter of the shaft to a depth of 8 feet. The shafts should contain enough full-length reinforcing steel to resist uplift forces.

Pier Spacing. Piers should not be spaced closer than three shaft diameters center to center to use the above-recommended bearing capacities (diameter of larger shaft).