Geotechnical Report - Duct Bank Loop and Pavement.pdf

REPORT C OVER PAGE

Geotechnical Engineering Report

21-313 – Houston VAMC EHRM: Duct Bank Loop and Pavements

Houston, Texas

November 2, 2023

Terracon Project No. 92235353

Prepared for:

Apogee Consultant Group, P.A.

Cary, North Carolina

Prepared by:

Terracon Consultants, Inc.

Houston, Texas

Deaderick D. Hollaway

Responsive ■ Resourceful ■ Reliable i

REPORT TOPICS

INTRODUCTION

SITE CONDITIONS

PROJECT DESCRIPTION

GEOTECHNICAL CHARACTERIZATION

GEOTECHNICAL OVERVIEW

RECOMMENDATIONS FOR OPEN-CUT CONSTRUCTION

PAVEMENTS

GENERAL COMMENTS

FIGURES

Note: This report was originally delivered in a web-based format. For more interactive features, please view your project online at client.terracon.com.

ATTACHMENTS

EXPLORATION AND TESTING PROCEDURES

SITE LOCATION AND EXPLORATION PLAN

EXPLORATION RESULTS (Boring Logs and Laboratory Data)

SUPPORTING INFORMATION (General Notes and Unified Soil Classification System)

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

http://client.terracon.com/

Responsive ■ Resourceful ■ Reliable 1

INTRODUCTION

Geotechnical Engineering Report

21-313 – Houston VAMC EHRM: Duct Bank Loop and Pavements

2002 Holcombe Boulevard

Houston, Texas

November 2, 2023

INTRODUCTION

This report presents the results of our subsurface exploration and geotechnical engineering services performed for the proposed duct bank and concrete pavements within the existing

Micheal E. De Bakey Veterans Affairs campus located at 2002 Holcombe Boulevard in Houston, Texas. This project was authorized by Mr. John Michael Beezley, P.E., LEED, AP, President with

Apogee Consulting Group, P.A. (Apogee) under the existing “Master Subcontract Agreement for

Professional Services” between Apogee and Terracon, and through signature of Apogee’s Project

No. 21-313, Client Project No. 580-22-700, Work Order No. 01, dated August 21, 2023 and Work

Order No. 01-R1, dated October 31, 2023. This project was performed in general accordance with

Terracon Document No. P92235353, dated July 7, 2023, and Terracon Document No.

92225353.Supplement1, dated September 19, 2023.

The purpose of these services is to provide information and geotechnical engineering recommendations relative to:

■ Earthwork including site and subgrade preparation

■ Excavation and temporary groundwater control considerations

■ Utility construction considerations

■ Bedding and backfill guidelines

■ Pavement design guidelines

The geotechnical engineering Scope of Services for this project included the advancement of ten test borings to a depth of approximately 10 feet below existing grade.

Terracon utilized the available field and laboratory information obtained from a previous geotechnical investigation performed by Terracon at this site (Terracon Project No. 92225371, dated December 16, 2023) to aid in providing our recommendations.

Maps showing the site and boring locations are shown in the Site Location and Exploration

Plan sections, respectively. The results of the laboratory testing performed on soil samples obtained from the site during the field exploration are included on the boring logs in the

Exploration Results section.

Houston, Texas ■ November 2, 2023 ■ Terracon Project No. 92235353

Responsive ■ Resourceful ■ Reliable 2

SITE CONDITIONS

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

Item Description

Project location

The project is within the existing Michael E. De Bakey Veterans Affairs campus located at 2002 Holcombe Boulevard in Houston, Texas.

See Site Location

Existing improvements The site was occupied by multiple single-story and multi-story buildings and associated concrete pavements at the time of our field program.

Current ground cover Grass, weeds, scattered trees, and concrete pavements

Existing topography Relatively level

PROJECT DESCRIPTION

Our initial understanding of the project was provided in our cost estimate and was discussed during project planning. A period of collaboration has transpired since the project was initiated, and our final understanding of the project conditions is as follows:

Item Description

Proposed improvements

Improvements associated with the project include:

■ Installation of a shallow duct bank. The duct bank will be installed with open-cut construction methods and will contain fiber optic cabling. We understand the duct bank will have a maximum depth of 3 feet.

■ Concrete pavements.

Pavements

We understand a rigid (concrete) pavement section is being considered.

We anticipate that traffic will consist primarily of passenger vehicles in the parking areas and passenger vehicles combined with garbage trucks and large multi-axle delivery trucks from time-to-time in driveway areas.

GEOTECHNICAL CHARACTERIZATION

Geology

Based on the geologic maps published by the Bureau of Economic Geology, the site for the proposed construction is located on the Beaumont formation, a deltaic nonmarine Pleistocene deposit. The Beaumont formation is heterogeneous containing thick interbedded layers of clay, fine sand, and silt.

Responsive ■ Resourceful ■ Reliable 3

The clay fraction is primarily composed of montmorillonite, illite, kaolinite, and finely ground quartz. The clay present in the formation has been preconsolidated by a process of desiccation.

Numerous wetting and drying cycles have produced a network of small randomly oriented, closely-spaced joints within some depth zones. These small joints frequently have a shiny appearance and the clays are called slickensided in these cases. The joint pattern may have an influence on the construction and engineering behavior of the soil.

The coastal plain in this region has a complex tectonic geology, several major features of which are: Gulf Coastal geosyncline, salt domes, and major sea level fluctuations during the glacial stages, subsidence and geologic faulting activities. Most of these geologic faulting activities have ceased for millions of years, but some are still active. A detailed geologic fault investigation and study of the site geology are beyond the scope of this report.

Subsurface Profile

We have developed a general characterization of the subsurface conditions based upon our review of the subsurface exploration, laboratory data, geologic setting, and our understanding of the project. This characterization, termed GeoModel, forms the basis of our geotechnical calculations and evaluation of site preparation and pavements. Conditions observed at each exploration point are indicated on the individual logs. The individual logs can be found in the

Exploration Results section and the GeoModel can be found in the Figures section of this report.

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

Model Layer Layer Name General Description

Fill: Fat Clay, Lean Clay, and Sandy Lean Clay gray, reddish brown, and tan, with sand and silt pockets, sand seams, scattered gravel, ferrous stains and nodules, and calcareous nodules

Fat Clay and Sandy Fat

Clay gray, tan, and reddish brown, soft to hard, with sand and silt pockets, sand seams, calcareous nodules, and ferrous stains and nodules

Groundwater Conditions

Borings B-1 through B-10 were advanced using dry drilling techniques to their termination depth

(approximately 10 feet) in an effort to evaluate groundwater conditions at the time of the field program. Groundwater was not observed at borings B-1 through B-10 during or upon completion of drilling.

Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall, runoff and other factors not evident at the time the borings were performed. Therefore, groundwater levels during construction or at other times in the life of the structure may vary and be present

Responsive ■ Resourceful ■ Reliable 4 within the depths explored. The possibility of groundwater level fluctuations should be considered when developing the design and construction plans for the project and should be evaluated prior to construction.

GEOTECHNICAL OVERVIEW

Based on the information obtained from our subsurface exploration, the site can be developed for the proposed project. A summary of our findings and recommendations is provided below.

■ Concrete pavement with thicknesses of approximately 5¾ to 12 inches were observed at the ground surface at borings B-1 and B-3 through B-10. Crushed stone material with a thickness of about 6 inches was observed beneath the existing pavement at boring B-1.

Fill soils were observed at the ground surface at boring B-2 and beneath the existing pavement at borings B-1 and B-3 through B-10 and extended approximately 2 to 8 feet below existing grade. Fill soils may be observed at varying depths at other locations within the site not explored during our field program. Support of the pavements on or above existing fill materials is discussed in this report.

■ Pavement areas placed upon deep fill soils, such as those observed at borings B-8 and

B-10, will be subject to future settlement of the fill. Complete excavation, removal, and recompaction of the fill soils in the pavement areas would reduce the potential for future settlement; however, complete excavation and removal of the fill soils within the proposed pavement areas would likely not be feasible. As an alternative, the settlement potential can be reduced by reworking the upper four feet of fill below the pavement areas (or up to the underlying native soils, whichever occurs first) to reduce differential settlements, with the understanding that some settlement (which will likely result in increased maintenance of pavements) will likely occur.

■ Based on the soil and groundwater conditions observed at the site, groundwater is not expected to be a major concern during construction. We anticipate that excavations within the clay soils may occur without advance dewatering. Seepage, should it occur, is expected to be minor and can be handled with sumps and pumps positioned in the bottom of the excavations.

■ Rigid pavement sections vary from 5.0 to 7.0 inches of reinforced concrete with chemically treated subgrade.

■ Based on the subsurface conditions observed at the site, we anticipate the pavement subgrade will generally consist of medium to high plasticity clay soils. The top 6 inches of the finished subgrade soils should be chemically treated with lime.

Responsive ■ Resourceful ■ Reliable 5

This summary should be used in conjunction with the entire report for design purposes. Details were not included or fully developed in this section, and the report must be read in its entirety for a comprehensive understanding of the items contained herein. The General Comments section provides an understanding of the report limitations.

RECOMMENDATIONS FOR OPEN-CUT CONSTRUCTION

We understand open-cut construction methods are planned for the proposed duct banks and that the maximum embedment depth is planned to be 3 feet below the existing grade. The utility construction considerations provided below are based on the soils and groundwater conditions observed during our field and laboratory programs.

Uplift Pressures

Uplift forces on below-grade structures are caused by a difference in water level in the soil adjacent to the structure and inside the structure. The effective static water level should be assumed to be at the surface for calculations of buoyant forces. The uplift pressures will be resisted by adhesion or skin friction of the soil to the wall and by the dead weight of the structure.

The value of allowable skin friction for an engineered clay fill compacted to a minimum of 95 percent of the maximum dry density as determined by the Standard Effort (ASTM D 698) may be considered to be 300 psf. We recommend that the upper 4 feet of skin friction be neglected for a clay backfill due to potential soil shrinkage away from the structure. Sand backfill, compacted to

70 percent of the maximum relative density (ASTM D 4253 and 4254), may be considered to have a value for allowable skin friction of zero at the surface varying linearly to 45 psf at a depth of 3 feet below existing grade.

Lateral Earth Pressures

Backfill around embedded structures will impose active to at-rest earth pressures against the embedded walls. The backfill should be compacted to 95 percent of the Standard Effort (ASTM

D698) maximum dry density. Design lateral earth pressures may be computed using an equivalent fluid weight of 90 pounds per cubic foot (pcf) for clean sand backfill and 110 pcf for on-site clay soils. This pressure includes hydrostatic pressures but does not include surcharge forces imposed by construction or vehicular loading. The lateral pressure produced by surcharge may be computed as 50 percent of the vertical surcharge pressure applied as a constant pressure over the full depth of the wall. A 2-foot layer of compacted clay soil should be placed at the top of sand backfill to reduce the amount of infiltration of surface water.

Temporary Groundwater Control

Based on groundwater information presented in the Groundwater Conditions section, groundwater is not expected to be a major concern during construction. We anticipate that

Responsive ■ Resourceful ■ Reliable 6 excavations within the clay soils may occur without advance dewatering. However, depending on climatic conditions, groundwater levels may vary from the level observed during our field program and minor seepage could be observed within the excavation depth. We anticipate that the minor seepage, should it occur, can be handled with sumps and pumps positioned in the bottom of the excavation.

The suggested method given above serves as a guideline for groundwater control; other appropriate means may be required for groundwater control during construction. Control of groundwater should be accomplished in a manner that will preserve the strength of the soils, will not cause instability of the excavation, and will not result in damage to existing structures, if any.

Excavation Considerations

Based on our understanding of the project, excavations up to 3 feet below existing grade are planned for this project. The sides of the excavations may either be sloped or formed with vertical cuts. For vertical sided excavations greater than 5 feet in depth, the excavations will require the use of shoring, bracing or some form of retention to prevent sloughing and caving of the soil into the excavation.

Occupational Safety and Health Administration (OSHA) standards provide recommendations for the design of temporary sloped excavations with a depth more than 5 feet and less than 20 feet.

The OSHA standards provide maximum allowable slopes contingent on three designated soil types: Type A, Type B, and Type C. According to OSHA standards, temporary sloped excavations should be no steeper than 0.75-horizontal on 1-vertical (0.75H:1V) for Type A soils, 1H:1V for

Type B soils, and 1.5H:1V for Type C soils. The soils type should be evaluated by a contractor designated Competent Person at the time of construction. The surface soils should be protected from deterioration and weathering if they are left open for significant periods of time.

Excavations should be performed with equipment capable of providing a relatively clean bearing area. Excavating equipment should not disturb the soil beneath the design excavation bottom and should not leave large amounts of loose soil in the excavation. The excavation bottom should be properly sloped to allow any water infiltrating into the excavation to be collected at a convenient location along the edge of the excavation. Water should not be allowed to stand on the bearing area.

Excavations must be performed and inspected under the supervision of a contractor designated

Competent Person. The Competent Person, as defined by the OSHA Standard, 29 CFR Part

1926.650 to .652, Subpart P – Excavations, must evaluate the excavations at the time of construction activity to safeguard workers.

As a safety measure, no equipment should be operated within 5 feet of the edge of the excavation and no materials should be stockpiled within 10 feet of the excavation. Excavations should not

Responsive ■ Resourceful ■ Reliable 7 approach closer than 10 feet from existing structures/facilities without some form of protection for the facilities.

Utility Bedding

The subgrade and bedding for the proposed duct bank should conform to the City of Houston (COH) standard on pipeline bedding details. In general, the pipe should be installed in continuous envelopes of cement stabilized sand our any other suitable material.

The soil observed in the borings at the estimated utility bedding depth generally consisted of fat clay and lean clay fill soils and soft to very stiff native fat clay soils. The excavations should be inspected to detect any variation in soil conditions from that found in our field and laboratory programs. Any changes noted in the soil stratigraphy should be brought to the attention of

Terracon so they can then be assessed and changes to the required bedding details can be made.

Utility Backfill

The type of fill placed above the utility bedding will depend on whether the surface above the utilities is paved or unpaved ground. If the surface is outside of the pavement areas, then the backfill may consist of the excavated, native soils provided they are free of debris and organics.

The in-situ soils used as backfill should be placed in thin lifts not exceeding 8 inches loose measure, moisture conditioned to within 2 percent of the optimum moisture content and compacted to at least 95 percent of the Standard Effort (ASTM D 698) maximum dry density.

Within pavement areas or within 3 horizontal feet of pavement, the backfill should consist of cement stabilized sand to within 12 inches of the top of the subgrade compacted to at least 95 percent of the Standard Effort (ASTM D 558) maximum dry density. On-site clean soils compacted to at least 95 percent of the Standard Effort (ASTM D 698) maximum dry density should be placed above the cement stabilized sand. The cement stabilized sand should develop 100 psi minimum compression at 48 hours as described in City of Houston Standard Specification 02321 – Cement

Stabilized Sand.

Prior to any filling operations, samples of the proposed borrow materials should be obtained for laboratory moisture-density testing. The tests will provide a basis for evaluation of fill compaction by in-place density testing. A qualified soil technician should perform sufficient in-place density tests during the filling operations to evaluate that proper levels of compaction are being attained.

PAVEMENTS

We understand existing pavement sections will be demolished and removed from the site.

Finished grade elevations were not available at the time of this report. However, we understand

Responsive ■ Resourceful ■ Reliable 8 new pavement surface elevations will be designed to match the existing pavement surface elevations. Pavement design grades are expected to require minimum cut and fill.

Subgrade Preparation

Pavement construction areas should be stripped of existing pavements (including crushed stone material), vegetation, topsoil, and other debris/unsuitable surface materials. Proper site drainage should be maintained during construction so that ponding of surface runoff does not occur and cause construction delays and/or inhibit site access.

Pavement areas placed upon deep fill soils, such as those observed at borings B-8 and B-10, will be subject to future settlement of the fill. Complete excavation, removal, and decompaction of the fill soils in the pavement areas would reduce the potential for future settlement; however, complete excavation and removal of the fill soil within the proposed pavement areas would likely not be feasible. As an alternative, the settlement potential can be reduced by reworking the upper four feet of fill below the pavement areas (or up to the underlying native soils, whichever occurs first) to reduce differential settlements, with the understanding that some settlement (which will likely result in increased maintenance of pavements) will likely occur.

Once final subgrade elevations have been achieved, the exposed soil subgrade areas should be carefully proofrolled with a 20-ton pneumatic roller or equivalent equipment, such as a fully loaded dump truck, to detect weak zones in the subgrade. Special care should be exercised when proofrolling areas containing fill soils in an attempt to observe soft/weak zones within the fill soils.

Weak areas detected during proofrolling, as well as zones of fill containing organic matter and/or debris, should be removed to expose firm subgrade and replaced with soils exhibiting similar classification, moisture content, and density as the adjacent in-situ soils. Proofrolling should be performed under the direct observation of the geotechnical engineer or his/her representative.

Subsequent to proofrolling, and just prior to placement of fill (if any), the exposed subgrade within the pavement areas should be evaluated for moisture and density. The subgrade should be between optimum moisture content and 4 percent wet of optimum moisture content, and have an in-place dry density of at least 95 percent of the Standard Effort (ASTM D 698) maximum dry density. If the moisture or density does not meet the above criteria, the subgrade should be scarified to a minimum depth of 6 inches, moisture conditioned to between optimum and 4 percent wet of optimum moisture content, and compacted to at least 95 percent of the Standard Effort

(ASTM D 698) maximum dry density.

Any fill soils used for grade adjustments in the new pavement areas should consist of clean soils that are free of organics/debris with similar characteristics as the on-site soils and should be compacted to a minimum of 95 percent of the maximum dry density as determined by the

Standard Effort (ASTM D 698) at a moisture content within 4 percent wet of the optimum moisture content in lifts not exceeding 8 inches loose measure.

Responsive ■ Resourceful ■ Reliable 9

Prior to any filling operations, samples of the proposed borrow materials should be obtained for laboratory moisture-density testing. The tests will provide a basis for evaluation of fill compaction by in-place density testing. A qualified soil technician should perform sufficient in-place density tests during the filling operations to evaluate that proper levels of compaction, including dry unit weight and moisture content, are being attained.

Construction operations may encounter difficulties due to wet or soft surface soils becoming a general hindrance to equipment, especially following periods of wet weather. If the subgrade cannot be adequately compacted to the minimum densities as described previously, one of the following measures will be required: 1) removal and replacement with select fill, 2) chemical treatment of the soil to dry and improve the condition of the subgrade, or 3) drying by natural means if the schedule allows. Based on our experience with similar soils in this area, chemical treatment is generally an efficient and effective method to improve the condition of wet and weak subgrade. Terracon should be contacted for additional recommendations if chemical treatment is planned to be utilized due to soft and wet subgrade.

Pavement Section

Once the subgrade is properly prepared, rigid pavement systems may be considered for this project. Detailed traffic loads and frequencies were not available at the time of this report.

However, we anticipate that traffic will consist primarily of passenger vehicles in the parking areas and passenger vehicles combined with garbage trucks and large multi-axle delivery trucks from time-to-time in driveway areas.

Tabulated in the following table are the assumed traffic frequencies and loads used to design pavement sections for this project. When actual traffic conditions have been determined, Terracon should be contacted to review the information to consider a need for revision of the pavement designs and related recommendations.

Pavement

Area

Traffic

Design Index 1 Description

Automobile Parking

Areas

DI-1

Light traffic (Few vehicles heavier than passenger cars, no regular use by heavily loaded two axle trucks.) (EAL 2 < 6)

Driveways

(Light Duty)

DI-2

Medium to light traffic (Similar to DI-1 including not over 50 loaded two axle trucks or lightly loaded larger vehicles per day. No regular use by heavily loaded trucks with three or more axles.) (EAL2 = 6-20)

Driveways and Truck Traffic

Areas (Medium

Duty)

DI-3

Medium traffic (Including not over 300 heavily loaded two axle trucks plus lightly loaded trucks with three or more axles and no more than 30 heavily loaded trucks with more than three axles per day.) (EAL2 = 21-75)

1. Based on NSSGA traffic design indices.

Responsive ■ Resourceful ■ Reliable 10

Pavement

Area

Traffic

Design Index 1 Description

2. Equivalent daily 18-kip single-axle load applications.

The top 6 inches of the finished subgrade soils directly beneath the pavement systems should be chemically treated with lime. Chemical treatment will increase the supporting value of the subgrade and decrease the effect of moisture on subgrade soils. These 6 inches of treatment is a required part of the pavement design and is not a part of site and subgrade preparation for wet/soft subgrade conditions.

Listed in the following table are rigid pavement component thicknesses, which may be used as a guide for pavement systems at the site for the traffic classifications stated herein. These systems were derived based on general characterization of the subgrade. Specific testing (such as CBR's, resilient modulus tests, etc.) was not performed for this project to evaluate the support characteristics of the subgrade.

Rigid Pavement System

Component Material Thickness, Inches

DI-1 DI-2 DI-3

Reinforced Concrete 5.0 6.0 7.0

Treated Subgrade 6.0 6.0 6.0

We recommend that waste dumpster areas be constructed of at least 7 inches of reinforced concrete pavement. The concrete pad areas should be designed so that the vehicle wheels of the collection truck are supported on the concrete while the dumpster is being lifted to support the large wheel loading imposed during waste collection.

Material Requirements

Presented below are our recommended material requirements for the various pavement section components.

Reinforced Concrete Pavement – The materials and properties of reinforced concrete pavement should meet applicable requirements in the ACI Manual of Concrete Practice. The Portland cement concrete mix should have a minimum 28-day compressive strength of 3,500 psi.

If river gravel is planned to be utilized in the Portland cement concrete mix, Terracon should be contacted for additional services. The presence of river gravel in the Portland cement concrete mix can result in excessive cracking and distress to the concrete pavement as a result of differing thermal expansion properties between the river gravel and cement paste. Special care should be taken in developing the project’s Portland cement concrete mix design, joint layout, and

Responsive ■ Resourceful ■ Reliable 11 placement to help reduce the potential for excessive cracking and distress if river gravel is planned to be utilized for the project.

Reinforcing Steel – ACI recommendations indicate that distributed steel reinforcement is not necessary when the pavement is properly jointed to form short panel lengths that will help reduce intermediate cracking. Provided the concrete pavement is designed and constructed as stated herein, the installation of reinforcing steel is optional and should be evaluated by the design team.

Proper layout and installation of the joints within the pavement is critical to help control intermediate cracking.

If reinforcing steel is planned to be utilized in the concrete pavement by the design team, the following amount of reinforcing steel should be used as a guideline:

DI-1: #3 bars spaced at 18 inches or #4 bars spaced at 24 inches on centers in both directions.

DI-2: #3 bars spaced at 12 inches or #4 bars spaced at 18 inches on centers in both directions.

DI-3: #4 bars spaced at 18 inches on centers in both directions.

Control Joint Spacing – ACI recommendations indicate that control joints should be spaced at a maximum spacing of 30 times the thickness of the pavement for unreinforced parking lot pavements. Furthermore, ACI recommends a maximum control joint spacing of 12.5 feet for 5-inch pavements and a maximum control joint spacing of 15 feet for 6-inch or thicker pavements.

Sawcut control joints should be cut within 4 to 12 hours of concrete placement to help control the formation of plastic shrinkage cracks as the concrete cures. The depth of the joint should be at least one-quarter of the slab depth when using a conventional saw or one inch when using early entry saws. The width of the cut should be in accordance with the joint sealant manufacturer recommendations.

Expansion Joint Spacing – ACI recommendations indicate that regularly spaced expansion joints may be deleted from concrete pavements. Therefore, the installation of expansion joints is optional and should be evaluated by the design team.

Construction Joints – When concrete is planned to be placed at different times, we recommend the use of a construction joint between paving areas. The construction joint should consist of a butt joint (not a keyway joint).

Concrete Curing Compound – A concrete curing compound, such as a Type 2 membrane curing compound conforming to TxDOT DMS-4650, “Hydraulic Cement Concrete Curing Materials and

Evaporation Retardants” or equivalent, should be applied to the concrete surface immediately after placement of the concrete in accordance with TxDOT 2014 Standard Specifications Item

360.

Dowels at Expansion/Construction Joints – The dowels at expansion/construction joints should be spaced at 12-inch centers and consist of the following:

Responsive ■ Resourceful ■ Reliable 12

DI-1: 5/8-inch diameter, 12-inches long with 5-inch embedment.

DI-2: 3/4-inch diameter, 14-inches long with 6-inch embedment.

DI-3: 7/8-inch diameter, 14-inches long with 6-inch embedment.

One end of the dowels should either be greased or sleeved to allow for lateral movement to occur.

Lime Treated Subgrade – We anticipate that the pavement subgrade will generally consist of on-site medium to high plasticity clay soils. The pavement subgrade should be treated with lime in accordance with the TXDOT 2014 Standard Specifications Item 260. Based on the classification test results, we recommend that about 6 to 8 percent lime by dry weight be used for estimating and planning. The percentages are given as application by dry weight and are typically equivalent to about 30 to 40 pounds of lime per square yard per 6-inch depth. The actual quantity of lime should be determined at the time of construction based on lime determination tests conducted using bulk samples of the subgrade soils. The pulverization, mixing and curing of the lime treated subgrade is of particular importance in these clays. The subgrade should be compacted to a minimum of 95 percent of the Standard Effort (ASTM D 698) maximum dry density at a moisture content between optimum and 4 percent wet of the optimum moisture content.

Preferably, traffic should be kept off the treated subgrade for about 7 days to facilitate curing of the soil-lime mixture; in addition, the subgrade is not suitable for heavy construction traffic prior to paving.

Maintenance Considerations

The pavement design methods described above are intended to provide structural sections with adequate thickness over a particular subgrade such that wheel loads are reduced to a level the subgrade can support. The support characteristics of the subgrade for pavement design do not account for shrink/swell movements of an expansive clay subgrade such as the soils encountered at this site. Thus, the pavement may be adequate from a structural standpoint, yet still experience cracking and deformation due to shrink/swell related movement of the subgrade. Post-construction subgrade movements and some cracking of pavements are not uncommon for clay subgrade conditions such as those observed at this site. Reducing moisture changes in the subgrade is important to reduce shrink/swell movements. Although chemical treatment will help to reduce such movement/cracking, this movement/cracking cannot be feasibly eliminated.

Related civil design factors such as subgrade drainage, shoulder support, cross-sectional configurations, surface elevations and environmental factors which will significantly affect the service life must be included in the preparation of the construction drawings and specifications.

Normal periodic maintenance will be required.

Long-term pavement performance will be dependent upon several factors, including maintaining subgrade moisture levels and providing for preventative maintenance. The following recommendations should be implemented to help promote long-term pavement performance:

Responsive ■ Resourceful ■ Reliable 13

■ The subgrade and the pavement surface should be designed to promote proper surface drainage, preferably at a minimum grade of 2 percent;

■ Install joint sealant and seal cracks immediately;

■ Extend curbs into the treated subgrade for a depth of at least 4 inches to help reduce moisture migration into the subgrade soils beneath the pavement section; and

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

Preventative maintenance should be planned and provided for the pavements at this site.

Preventative maintenance activities are intended to slow the rate of pavement deterioration, and consist of both localized maintenance (e.g. crack and joint sealing and patching) and global maintenance (e.g. surface sealing). Prior to implementing any maintenance, additional engineering observations are recommended to determine the type and extent of preventative maintenance.

GENERAL COMMENTS

Our work is conducted with the understanding of the project as described in the cost estimate, and incorporated collaboration with the design team as we completed our services to verify assumptions. Revision of our understanding to reflect actual conditions important to our work was based on these verifications and it is reflected in this report. The design team should collaborate with Terracon to confirm these assumptions and to prepare the final design plans and specifications. This facilitates the incorporation of our opinions related to implementation of our geotechnical recommendations. Any information conveyed prior to the final report is for informational purposes only and should not be considered or used for decision-making purposes.

Our analysis and opinions are based upon our understanding of the geotechnical conditions in the area, the data obtained from our site exploration and from our understanding of the project.

Variations will occur between exploration point locations, across the site, or due to the modifying effects of construction or weather. The nature and extent of such variations may not become evident until during or after construction. Terracon should be retained as the Geotechnical

Engineer, where noted in this report, to provide observation and testing services during grading, excavation, foundation construction and other earth-related construction phases of the project. If variations appear, we can provide further evaluation and supplemental recommendations. If variations are noted in the absence of our observation and testing services on-site, we should be immediately notified so that we can provide evaluation and supplemental recommendations.

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

Responsive ■ Resourceful ■ Reliable 14

Our services and any correspondence are intended for the sole benefit and exclusive use of our client for specific application to the project discussed and are accomplished in accordance with generally accepted geotechnical engineering practices with no third party beneficiaries intended.

Any third party access to services or correspondence is solely for information purposes only.

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

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

Responsive ■ Resourceful ■ Reliable

FIGURES

Contents:

GeoModel

D E P

T H

B E

L O

W E

X

IS

T

IN

G G

R A

D E

F e e t)

Layering shown on this figure has been developed by the geotechnical engineer for purposes of modeling the subsurface conditions as required for the subsequent geotechnical engineering for this project.

Numbers adjacent to soil column indicate depth below ground surface.

NOTES:

B-1 B-2 B-3 B-4 B-5 B-6 B-7 B-8 B-9 B-10 PB-1 PB-2 PB-3

This is not a cross section. This is intended to display the Geotechnical Model only. See individual logs for more detailed conditions.

Houston, TX

GeoModel

2002 Holcombe Boulevard | Houston, Texas

Terracon Project No. 92235353 11555 Clay Rd, Ste 100

Concrete Fill

Fat Clay Fat Clay with Sand

Sandy Fat Clay

Model Layer LegendLayer Name General Description gray, reddish brown, and tan, with sand and silt pockets, sand seams, scattered gravel, ferrous stains and nodules, and calcareous nodules gray, tan, and reddish brown, soft to hard, with sand and silt pockets, sand seams, calcareous nodules, and ferrous stains and nodules

Fill: Fat Clay, Lean Clay, and Sandy

Lean Clay

Fat Clay and Sandy Fat Clay

21-313 - Houston VAMC EHRM- Duct Bank Loop and Pavements

2002 Holcombe Boulevard | Houston, Texas

Responsive ■ Resourceful ■ Reliable

ATTACHMENTS

Responsive ■ Resourceful ■ Reliable EXPLORATION AND TESTING PROCEDURES 1 of 2

EXPLORATION AND TESTING PROCEDURES

Field Exploration

Boring Location Number of Borings Approximate Boring Depth1

(feet)

Proposed duct bank and pavement areas 10 (B-1 through B-10) 10

1. Below grade at the time of our field program.

Boring Layout and Elevations: We used handheld Global Positioning System (GPS) equipment to locate the approximate latitude and longitude of the borings with an accuracy of +/-25 feet. The boring depths were measured from the existing ground surface at the time of our field activities.

Subsurface Exploration Procedures: We advanced soil borings with a standard truck-mounted mounted drill rig using solid stem auger drilling techniques. Samples were obtained at 2-foot intervals to the termination depth of each boring (10 feet).

Cohesive soil samples were recovered using open-tube samplers. Hand penetrometer tests were performed on samples of cohesive soils in the field to serve as a general measure of consistency.

The samples were placed in appropriate containers, taken to our soil laboratory for testing, and classified by a geotechnical engineer. In addition, we observed and recorded groundwater levels during drilling and sampling. We backfilled the borings with auger cuttings upon completion and patched at the surface with ready-mixed concrete. Our services did not include repair of the site beyond backfilling our borings and cold patching existing pavements.

Our exploration team prepared field boring logs as part of standard drilling operations including sampling depths, penetration distances, and other relevant sampling information. Field logs include visual classifications of materials observed during drilling, and our interpretation of subsurface conditions between samples. Final boring logs, prepared from field logs, represent an interpretation of the field logs by a geotechnical engineer and include modifications based on laboratory observation and tests on select samples.

Laboratory Testing

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

Procedural standards noted below are for reference to methodology in general. In some cases, variations to methods were applied because of local practice or professional judgment. Standards noted below include reference to other, related standards. Such references are not necessarily applicable to describe the specific test performed.

Responsive ■ Resourceful ■ Reliable EXPLORATION AND TESTING PROCEDURES 2 of 2

■ ASTM D2216 Standard Test Methods for Laboratory Determination of Water (Moisture)

Content of Soil and Rock by Mass

■ ASTM D4318 Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of

Soils

■ ASTM D1140 Standard Test Methods for Determining the Amount of Material Finer than

No. 200 Sieve in Soils by Washing

■ ASTM D2166/D2166M Standard Test Method for Unconfined Compressive Strength of

Cohesive Soil

■ ASTM D7263-21 Standard Test Method for Determination of Density and Unit Weight of

Soil Specimens

Our laboratory testing program included observation of soil samples by an engineer. Based on the results of our field and laboratory programs, we described and classified the soil samples in accordance with the Unified Soil Classification System (USCS).

Samples not tested in the laboratory will be stored for a period of 30 days subsequent to submittal of this report and will be discarded after this period, unless we are notified otherwise.

SITE LOCATION AND EXPLORATION PLAN

Site Location

Exploration Plan

SITE LOCATION

21-313 – Houston VAMC EHRM: Duct Bank Loop and Pavements ■ Houston, Texas

November 2, 2023 ■ Terracon Project No. 92235353

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

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

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

MAP 1 PORTRAIT

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

EXPLORATION PLAN

21-313 – Houston VAMC EHRM: Duct Bank Loop and Pavements ■ Houston, Texas

November 2, 2023 ■ Terracon Project No. 92235353

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

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

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

MAP 2 PORTRAIT

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

EXPLORATION RESULTS

Boring Logs (B-1 through B-10)

Previously Drilled Borings Terracon Project 92225371, dated December

16, 2022 (PB-1 through PB-3)

PAVEMENT, approximately 7¼ inches of concrete overlaying about 6 inches of crushed stone material FILL - FAT CLAY WITH SAND (CH), reddish brown, with sand seams, and ferrous stains and nodules

FAT CLAY (CH), dark gray, stiff, with ferrous nodules

Boring Terminated at 10 Feet

Boring Log No. B-1

W at er L ev el

O bs er va tio ns

D ep th

Ft

Facilities | Environmental | Geotechnical | Materials

G ra p h ic

L o g

M o d el

L ay er

8124.8

20.6 1034.60.74UC

53-17-36

0.6

4.0

10.0

1.0 (HP)

0.5 (HP)

2.0 (HP)

2.0 (HP)

1.5 (HP)

Abandonment Method Boring backfilled with auger cuttings upon completion and patched at the surface with ready mix concrete.

Advancement Method Dry augered to 10 feet.

Driller EG Drilling

Logged by M. Hall

Boring Started 09-30-2023

Boring Completed 09-30-2023

11555 Clay Rd, Ste 100

Drill Rig Truck

21-313 - Houston VAMC EHRM- Duct Bank Loop and Pavements

Houston, TX

2002 Holcombe Boulevard | Houston, Texas

Terracon Project No. 92235353

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

See Supporting Information for explanation of symbols and abbreviations.

Notes

Water Level Observations No free water observed.

S am pl e

T yp e

Pe rc en t

Fi n es

W at er C o n te n t

D ry

U n it

W ei g h t

(p cf

S tr ai n

C om p re ss iv e S tr e n g th

(t sf

T es t T y p e

Atterberg Limits

LL-PL-PI

See Exploration PlanLocation:

Latitude: 29.6990° Longitude: -95.3897°

Depth (Ft.)

Strength Test

Fi el d T es t

R es u lt s

FILL - SANDY LEAN CLAY (CL), gray and reddish brown, with sand seams, scattered gravel, and calcareous nodules

- with scattered roots 0 to 2 feet

FAT CLAY (CH), dark gray, very stiff to hard, with sand pockets, and calcareous nodules

- with ferrous stains below 8 feet

Boring Terminated at 10 Feet

Boring Log No. B-2

W at er L ev el

O bs er va tio ns

D ep th

Ft

Facilities | Environmental | Geotechnical | Materials

G ra p h ic

L o g

M o d el

L ay er

13.2

21.6 10258.90UC

29-14-15

4.0

10.0

3.0 (HP)

4.5 (HP)

4.5 (HP)

4.5 (HP)

3.0 (HP)

Abandonment Method Boring backfilled with auger cuttings upon completion.

Advancement Method Dry augered to 10 feet.

Driller EG Drilling

Logged by M. Hall

Boring Started 09-30-2023

Boring Completed 09-30-2023

11555 Clay Rd, Ste 100

Drill Rig Truck

Houston, TX

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

See Supporting Information for explanation of symbols and abbreviations.

Notes

Water Level Observations No free water observed.

S am pl e

T yp e

Pe rc en t

Fi n es

W at er C o n te n t

D ry

U n it

W ei g h t

(p cf

S tr ai n

C om p re ss iv e S tr e n g th

(t sf

T es t T y p e

Atterberg Limits

LL-PL-PI

See Exploration PlanLocation:

Latitude: 29.6988° Longitude: -95.3913°

Depth (Ft.)

Strength Test

Fi el d T es t

R es u lt s

21-313 - Houston VAMC EHRM- Duct Bank Loop and Pavements

PAVEMENT, approximately 12 inches of concrete

FILL - FAT CLAY WITH SAND (CH), gray, with scattered gravel and ferrous nodules

- with ferrous stains and calcareous nodules 2 to 4 feet

FAT CLAY (CH), gray and reddish brown, medium stiff to stiff

- with calcareous nodules below 8 feet

Boring Terminated at 10 Feet

Boring Log No. B-3

W at er L ev el

O bs er va tio ns

D ep th

Ft

Facilities | Environmental | Geotechnical | Materials

G ra p h ic

L o g

M o d el

L ay er

24.4 76-22-54

1.0

4.0

10.0

0.5 (HP)

2.0 (HP)

1.0 (HP)

1.5 (HP)

1.5 (HP)

Abandonment Method Boring backfilled with auger cuttings upon completion and patched at the surface with ready mix concrete.

Advancement Method Dry augered to 10 feet.

Driller EG Drilling

Logged by M. Hall

Boring Started 09-14-2023

Boring Completed 09-14-2023

11555 Clay Rd, Ste 100

Drill Rig Truck

Houston, TX

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

See Supporting Information for explanation of symbols and abbreviations.

Notes

Water Level Observations No free water observed.

S am pl e

T yp e

Pe rc en t

Fi n es

W at er C o n te n t

D ry

U n it

W ei g h t

(p cf

S tr ai n

C om p re ss iv e S tr e n g th

(t sf

T es t T y p e

Atterberg Limits

LL-PL-PI

See Exploration PlanLocation:

Latitude: 29.7001° Longitude: -95.3912°

Depth (Ft.)

Strength Test

Fi el d T es t

R es u lt s

21-313 - Houston VAMC EHRM- Duct Bank Loop and Pavements

PAVEMENT, approximately 5¾ inches of concrete FILL - LEAN CLAY WITH SAND (CL), dark gray and tan, with sand pockets, and scattered gravel

FAT CLAY (CH), dark gray, very stiff, with sand and silt pockets, calcareous nodules, and ferrous stains

Boring Terminated at 10 Feet

Boring Log No. B-4

W at er L ev el

O bs er va tio ns

D ep th

Ft

Facilities | Environmental | Geotechnical | Materials

G ra p h ic

L o g

M o d el

L ay er

19.0 44-21-23

0.3

6.0

10.0

4.5 (HP)

4.5 (HP)

4.5 (HP)

4.5 (HP)

4.5 (HP)

Abandonment Method Boring backfilled with auger cuttings upon completion and patched at the surface with ready mix concrete.

Advancement Method Dry augered to 10 feet.

Driller EG Drilling

Logged by M. Hall

Boring Started 09-30-2023

Boring Completed 09-30-2023

11555 Clay Rd, Ste 100

Drill Rig Truck

Houston, TX

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

See Supporting Information for explanation of symbols and abbreviations.

Notes

Water Level Observations No free water observed.

S am pl e

T yp e

Pe rc en t

Fi n es

W at er C o n te n t

D ry

U n it

W ei g h t

(p cf

S tr ai n

C om p re ss iv e S tr e n g th

(t sf

T es t T y p e

Atterberg Limits

LL-PL-PI

See Exploration PlanLocation:

Latitude: 29.7015° Longitude: -95.3910°

Depth (Ft.)

Strength Test

Fi el d T es t

R es u lt s

21-313 - Houston VAMC EHRM- Duct Bank Loop and Pavements

PAVEMENT, approximately 7 inches of concrete

FILL - LEAN CLAY WITH SAND (CL), tan, with scattered gravel

FAT CLAY WITH SAND (CH), dark gray and tan, stiff, with sand seams

FAT CLAY (CH), dark gray, stiff

- tan 6 to 8 feet

- with ferrous stains and nodules below 6 feet

- reddish brown, with sand pockets below 8 feet

Boring Terminated at 10 Feet

Boring Log No. B-5

W at er L ev el

O bs er va tio ns

D ep th

Ft

Facilities | Environmental | Geotechnical | Materials

G ra p h ic

L o g

M o d el

L ay er

24.8

27.8 913.31.17UC

41-23-18

0.6

2.0

4.0

10.0

1.5 (HP)

1.5 (HP)

1.5 (HP)

1.5 (HP)

Abandonment Method Boring backfilled with auger cuttings upon completion and patched at the surface with ready mix concrete.

Advancement Method Dry augered…