P01 - Terracon Geotechnical Engineering Report No. 94225110-S.pdf

REPORT COVER PAGE

Geotechnical Engineering Report

VA Outpatient Expansion Grand Prairie Grand Prairie, Texas

May 20, 2022 Terracon Project No.94225110-R1

Prepared for:

Valiant Construction LLC

Louisville, Kentucky

Prepared by:

Terracon Consultants, Inc.

Dallas, Texas

Terracon Consultants, Inc. 8901 John W Carpenter Freeway Dal las, Texas 75247 Regist rat ion No. F-3272 P (214) 630-1010 F (214) 630-7070 terracon.com

REPORT COVER LETTER TO SIGN

May 20, 2022

Valiant Construction LLC 4124 Wahl Street Blvd Louisville, Kentucky 40218

Attn: Ms. Meredith McCoy P: (423) 300 8137 E: mmccoy@valiantconstruct.com

Re: Geotechnical Engineering Report VA Outpatient Expansion Grand Prairie 2737 Sherman Street Grand Prairie, Texas Terracon Project No.94225110-R1

Dear Ms. McCoy:

This report provides geotechnical recommendations for the planned VA Outpatient Clinic expansion. The report has been updated to include recommendations for pavement drive ways.

This study was performed in general accordance with Terracon Proposal No. P95225110-R1 dated March 17, 2022.

We appreciate the opportunity to be of service to you on this project. If you have any questions concerning this report or if we may be of further service, please contact us.

Sincerely, Terracon Consultants, Inc.

Ali Q. Abdullah, Ph.D., P.E. Tim G. Abrams, P.E.

Project Manager Senior Principal

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REPORT TOPICS

INTRODUCTION

SITE CONDITIONS

PROJECT DESCRIPTION

GEOTECHNICAL CHARACTERIZATION

EARTHWORK

DEEP FOUNDATIONS

FLOOR SLABS

SEISMIC CONSIDERATIONS

PAVEMENTS

GENERAL COMMENTS

Note: This report was originally delivered in a web-based format. Orange Bold text in the report indicates a referenced section heading. The PDF version also includes hyperlinks which direct the reader to that section and clicking on the GeoReport logo will bring you back to this page. For more interactive features, please view your project online at client.terracon.com.

ATTACHMENTS

EXPLORATION AND TESTING PROCEDURES

SITE LOCATION AND EXPLORATION PLANS

EXPLORATION RESULTS

SUPPORTING INFORMATION

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

http://client.terracon.com/

VA Outpatient Expansion Grand Prairie ■ Grand Prairie, Texas May 20, 2022 ■ Terracon Project No.94225110-R1

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REPORT SUMMARY

Topic Overview Statement 1

Project Description ■ The existing one-story clinic will be expanded by about 14,000 sq. ft.

■ A new entrance canopy is planned

Geotechnical Characterization

■ Expansive clays were encountered to depths of 44 feet

■ Groundwater encountered in all the borings at depths of 30 to 34 feet

Deep Foundations

■ Auger-Cast-Piles are planned to support the building expansion areas and planned canopy

■ Deep foundations system should consist the followings:

· Grade beams should be supported on foundation auger-cast-piles

· A void space should be provided between the grade beams and the underlying clay soils

Floor Slabs Structural slab in conjunction with an auger-cast-pile foundation system is recommended to match the existing building structural slab

Seismic Considerations

Based on the 2012/2015 International Building Code (IBC) and ASCE/SEI 7- 10, the seismic site classification for this site is C.

Pavement

Portland cement concrete pavement is planned to replace a section of asphaltic concrete at the entrance to the building. Subgrade modification recommendations are provided for reduction in potential pavement movements.

General Comments This section contains important information about the limitations of this geotechnical engineering report.

1. This summary is for convenience only. It should be used in conjunction with the entire report for design purposes.

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INTRODUC TION

Geotechnical Engineering Report VA Outpatient Expansion

2737 Sherman Street Grand Prairie, Texas

Terracon Project No.94225110-R1 May 20, 2022

INTRODUCTION

This report presents geotechnical recommendations for design of foundations for the additions to planned to the Out-Patient Building and replacement pavement. The VA Out-Patient building is located at 2737 Sherman Street in Grand Prairie, Texas. This report includes the following information and geotechnical engineering recommendations:

■ Soil, rock, and groundwater conditions ■ Foundation design and construction

■ Site preparation and earthwork ■ Replacement pavement

■ Floor slab recommendations ■ Seismic site classification per IBC

The geotechnical engineering Scope of Services for this project included four borings to depths of 50 feet, laboratory tests, and engineering analyses. Maps showing the site and boring locations are shown in this report Site Location and Exploration Plan sections, respectively. The results of the laboratory tests are included on the boring logs in the Exploration Results section.

SITE CONDITIONS

The following description of site conditions is derived from our site visit, borings and our review of publicly available geologic and topographic maps.

Item Description

Project Location The project is located at 2737 Sherman Street in Grand Prairie, Texas.

Approximate GPS Coordinates: 32.7343622°N/-97.0498188°W See Site Location

Existing Improvements

An existing one-story clinic building, driveways, and surface parking. The building has a crawl space and is supported on drilled shafts bearing in shale

Current Ground Cover Grass covered, concrete paved driveways and asphalt parking lo

Existing Topography Based on the NCTCOG DFW Map, the ground surface is sloping up towards the north west corner. The total relief is 2 feet

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PROJECT DESCRIPTION

Item Description

Project Description

■ The existing one-story clinic will be expanded by about 14,000 sq. ft.

The building expansion is planned on the north, east, and south sides of the building

■ A new entrance canopy is planned

■ A portion of the entrance driveway and the patient drop of lane will replaced with Portland cement concrete.

Structural Loads ■ The maximum column loads are expected to be about 175 kips

■ Wall loads are expected to be about 5,500 plf

Anticipated Deep Foundations

■ Auger-Cast Piles for building and canopy

■ Underream Drilled Shafts could be used for the canopy

Floor Slab Structural floor slab

Grading Cuts and fills up to 2 feet may be required to develop final grades

GEOTECHNICAL CHARACTERIZATION

We have developed a general characterization of the subsurface conditions termed GeoModel.

The GeoModel forms the basis of our geotechnical calculations and evaluation of site preparation and foundation options. Conditions encountered at each boring are indicated on the boring logs.

The boring logs and GeoModel can be found in the Exploration Results section this report.

The GeoModel has been divided into four layers listed in the following table. The model layer numbers are also included on the boring logs.

Model Layer Layer Name General Description

1 Topsoil About 6 inches encountered in all the borings

2 Fat Clay

Encountered below Topsoil and extended to weathered shale/gray shale.

Liquid limits ranged from 59 to 79. Plasticity indices ranged from 41 to 59.

The consistency ranged from very stiff to hard. The color ranged from light gray and tan to dark brown

3 Weathered Shale

Encountered in borings B-1 and B-3 about 44 feet below the ground surface and continued to the termination depths

4 Gray Shale Encountered in boring B-2 only and extended to the termination depth

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Groundwater observations were made while drilling and after completion. The water levels observed in the boreholes are shown on the boring logs in Exploration Results and are summarized in the following table.

Boring Number

Approximate Depth to

Groundwater while Drilling (feet)

Approximate Elevation of

Groundwater while Drilling (feet)

Approximate Depth to

Groundwater after Drilling (feet)

Approximate Elevation of

Groundwater after Drilling (feet)

B-1 34 549 30 553

B-2 34 549 30 553

B-3 34 547 30 551

B-4 34 546 30 550

1. Groundwater measurements are below the ground surface

Due to the low permeability of the soils encountered in the borings, a relatively long period may be necessary for a groundwater level to develop and stabilize in a borehole. Long term observations in piezometers or observation wells sealed from the influence of surface water are often required to define groundwater levels in materials of this type.

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 be higher or lower than the levels indicated on the boring logs. The possibility of groundwater level fluctuations should be considered when developing the construction plans for the project.

EARTHWORK

Site Preparation The site should be stripped and grubbed to remove all vegetation, root balls, deleterious material, and debris. Over excavation required to remove the root balls should be backfilled with properly placed and compacted fill as discussed in Compaction Requirements.

Fill Material Types Fill materials should meet the following requirements.

Material Type Description Appropriate Use

On-Site Soils Free of vegetation, organic material, debris

■ General site grading

■ Utility trench backfill

■ Moisture conditioned soils

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Material Type Description Appropriate Use

Imported Fill

Clay soil free of hazardous chemicals, vegetation, organic material, debris, and rocks greater than 4 inches in maximum dimension, with a liquid limit (LL) of 50 or less

■ General site grading

■ Utility trench backfill

■ Moisture conditioned soils

Flexible Base TxDOT Item 247, Type A or D, Grade 1-2.

Recycled concrete meeting this gradation is acceptable.

■ Pavement subgrade

Compaction Requirements

We recommend that all fill be observed and tested for moisture content and compaction during placement. Should the results of the in-place density tests indicate the specified moisture or compaction limits have not been met, the area represented by the test must be reworked and retested as required until the specified moisture and compaction requirements are achieved.

Recommendations for compaction are presented in the following table. All fills should be placed at a maximum loose lift thickness of nine inches.

Item Compaction Moisture Content

On-site soils or imported fills

A minimum of 95% maximum standard Proctor dry density (ASTM D 698)

At a -2 to +3 percentage points of optimum moisture content

Flexible base A minimum of 95% maximum TxDOT

TEX-113E.

In the range of -2 to 3 percentage points of optimum moisture content

Utility Trenches Utility trenches are a common source of water infiltration and migration. All utility trenches that penetrate beneath the expansion building areas should be sealed to restrict water intrusion and flow through the trenches that could migrate below the building. We recommend constructing a clay or flowable fill “trench plug” that extends at least two feet out from the face of the building exterior. The clay fill/flowable fill should be placed to surround the utility line and it should fill the utility trench completely in width and height. If clay plug is used, it should be a fat clay material with a minimum Plasticity Index (PI) of 30 and should be compacted in accordance with recommendations for General Site Fill materials as noted in Compaction Requirements. If flowable fill is used, it should be in accordance with TxDOT Item 401.

Utility lines will be placed in backfilled trenches surrounded by expansive clays capable of moving several inches cyclically throughout the year. This level of movement can lead to bending, cracking, or separation of utility connections. Utility trenches should be backfilled with on-site soils. Joints and connections to the building should be designed by the MEP as flexible.

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Earthwork Construction Considerations It is anticipated that excavations in the overburden soils for the proposed construction can be accomplished with conventional earthmoving equipment. The subgrade soils exposed during construction are anticipated to be relatively stable to construction traffic. However, the stability of the subgrade may be affected by rain, repetitive construction traffic, or other factors. If unstable conditions develop, workability may be improved by scarifying and drying.

The site should also be graded to prevent ponding of surface water on the prepared subgrades or in excavations. If the subgrade should become frozen, desiccated, saturated, or disturbed, the affected material should be removed or these materials should be scarified, moisture conditioned, and compacted again prior to floor slab construction.

As a minimum, all temporary excavations should be sloped or braced as required by Occupational Health and Safety Administration (OSHA) regulations to provide stability and safe working conditions. Temporary excavations will probably be required during grading operations. The grading contractor, by his contract, is usually responsible for designing and constructing stable, temporary excavations and should shore, slope or bench the sides of the excavations as required, to maintain stability of both the excavation sides and bottom. All excavations should comply with applicable local, state and federal safety regulations, including the current OSHA Excavation and Trench Safety Standards.

The geotechnical engineer or a representative should be retained during the construction phase of the project to observe earthwork and to perform necessary tests and observations during subgrade preparation; proof rolling; placement and compaction of controlled compacted fills;

backfilling of excavations into the completed subgrade, and just prior to construction of building floor slabs.

Construction site safety is the sole responsibility of the contractor who controls the means, methods, and sequencing of construction operations. Under no circumstances shall the information provided herein be interpreted to mean Terracon is assuming responsibility for construction site safety, or the contractor's activities; such responsibility shall neither be implied nor inferred.

Construction Observation and Testing

The earthwork should be monitored under the direction of the Geotechnical Engineer. Monitoring should include documentation of adequate removal of vegetation and topsoil, proof-rolling and mitigation of areas delineated by the proof-roll to require mitigation.

Each lift of compacted fill should be tested, evaluated, and reworked as necessary until approved by the Geotechnical Engineer prior to placement of additional lifts. Each lift of fill should be tested for density and water content at a frequency of at least three tests per lift in the building expansion

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In addition to the documentation of the essential parameters necessary for construction, the continuation of the Geotechnical Engineer into the construction phase of the project provides the continuity to maintain the Geotechnical Engineer’s evaluation of subsurface conditions, including assessing variations and associated design changes.

Site Grades and Drainage All grades must be adjusted to provide positive drainage away from the building expansion areas.

Water permitted to pond adjacent to the building can result in ground movements that exceed those discussed in this report. Open ground should preferably be sloped at a minimum of 5 percent grade for at least 10 feet beyond the perimeter of the building.

Flatwork will be subject to post construction movement. Maximum grades practical should be used for flatwork to prevent areas where water can pond. In addition, allowances in final grades should take into consideration post-construction movement of flatwork, particularly if such movement would be critical. Consideration should be given to preparing the subgrade as discussed in Floor Slabs in movement sensitive areas. Where flatwork abuts the structure, care should be taken that joints are properly sealed and maintained to prevent the infiltration of surface water.

Any planters located adjacent to the structure should preferably be self-contained, or at least designed to drain away from the building. Sprinkler mains should be located a minimum of five feet away from the building lines. If heads must be located adjacent to the structure, then service lines off the main should be provided. Roof drains should discharge on pavement or be extended away from the structure. Ideally, roof drains should discharge by closed pipe to the storm drainage system.

Care should be taken that utility trenches are not left open for extended periods and they are properly backfilled. Backfilling should be accomplished with properly compacted on-site soils, rather than granular materials.

DEEP FOUNDATIONS

Augered Cast-in-Place (ACIP) Pile Design Parameters

The following table can be used to estimate capacities for individual, continuous flight auger piles, commonly referred to as Augered Cast-in-Place (ACIP) piles. ACIPs should be spaced at least three pile diameters apart (center-to-center) if side friction is used for compressive loads. The end bearing values include a factor of safety of three and the skin friction values include a factor of safety of two. If the deep foundation type is changed to straight sided drilled shafts, either temporary casing or slurry method will be required because of the presence of groundwater.

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Design Parameter Recommendations

Bearing stratum Fat Clay

Bearing stratum thickness 0 to 10 feet 10 to 25 feet Below 25 feet

Maximum net allowable end bearing capacity NA 10,000 psf 16,000 psf

Allowable skin friction – compression and Tension NA 475 psf 750 psf

Penetration depth to include skin friction 5 feet

Settlement ACIP settlements are expected to be less than one-half inch.

Differential settlement 50 to 75 percent of the total settlement

ACIP Penetration Depths

The required penetration of the ACIP piles may be greater than the minimum penetration recommended in this report based on the structural load, uplift resistance, size of the pile, and bearing materials present at the bottom of excavation.

Our design recommendations were developed based on the recommended methods provided in Design and Construction of Driven Pile Foundations, Publication No. FHWA-NHI-16-009, published on July 2016.

Drilled and Underreamed Shaft Design Parameters

Design parameters are provided below in the table for the design of drilled and underreamed foundations that can be used for supporting canopy loads. The value presented for the end bearing includes a factor of safety of three.

Design Parameter Recommendation

Bearing Stratum Fat Clay

Bearing Depth 20 feet below existing grade

Allowable Bearing Pressure 10,000 psf

Minimum Underream to Shaft Diameter Ratio 2 to 1

Maximum Underream to Shaft Diameter Ratio 3 to 1

Minimum Shaft Diameter 18 inches

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Design Parameter Recommendation

Minimum Underream Edge to Underream Edge Spacing

One underream diameter, based on the larger of the two. Closer drilled shaft spacing should be evaluated by Terracon to determine if reductions in the allowable bearing pressures should be made to control settlement.

Allowable Uplift Resistance, Q Uplift Allow

(Factor of Safety of 2)

Q Uplift Allow = 1,000 x Nu x (B2 – S2), lbs.

Where, Nu = 4.57 (Db/B-0.75) for 0 < (Db/B) < 2.5 Nu = 8 for (Db/B) ≥ 2.5 Db = Depth to bottom of underream B = Bell Diameter, feet S = Shaft Diameter, feet

Total settlement 70 to 80 percent of the foundation settlement is expected to occur as the shafts are loaded. The total settlement is estimated to range from ½ to 1 percent of the underream diameter.

Differential settlement ½ to ¾ of the total settlement.

Soil Induced Uplift Loads

Drilled underreamed shaft and auger cast piles (ACIP) will be subject to uplift as a result of heave in the overlying clay soils. The magnitude of these loads varies with the shaft diameter, soil parameters, and particularly the in-situ moisture levels at the time of construction. The shafts and piles must contain sufficient continuous vertical reinforcing and embedment depth to resist the net tensile load. The design uplift adheave design value of 1,800 psf is recommended to be used for an embedment depth of 10 feet.

Lateral Loading

When ACIP are used in groups, the lateral capacities of the piles in the second, third, and subsequent rows of the group should be reduced as compared to the capacity of a single, Soil Type Clays Clays

P-Y Model Stiff clay without free water Stiff clay without free water

Depth (ft.) 2 - 25 Below 25

Effective Unit Weight (pcf) 125 125

Undrained Cohesion, c (psf) 1,900 3,000

Strain Factor, є50 0.005 0.005

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Responsive ■ Resourceful ■ Reliable 9 independent pile. Guidance for applying p-multiplier factors to the p values in the p-y curves for each row of pile foundations within a pile group are as follows:

■ Front row: Pm = 0.8;

■ Second row: Pm = 0.4

■ Third and subsequent row: Pm = 0.3.

For the case of a single row of piles supporting a laterally loaded grade beam, group action for lateral resistance of piles would need to be considered when spacing is less than three pile diameters (measured center-to-center).

Drilled and Underreamed Shaft Construction Considerations

The construction of all drilled shafts should be observed by experienced geotechnical personnel during construction to confirm: 1) the bearing stratum; 2) the minimum bearing depth; 3) the removal of all cuttings 4) that groundwater seepage, if any, is correctly handled; and 5) that the shafts are within acceptable vertical tolerance.

Recommendations for drilled shaft construction are presented in the following table.

Item Recommendation

Installation specification Current version of American Concrete Institute’s “Standard Specification for the Construction of Drilled Piers” ACI 336.

Top of shaft completion Enlarged (mushroom-shaped) top in contact with the clays should not be allowed.

Time to complete Underreamed shafts should be completed in one day. The side wall and base will begin to deteriorate if the hole remains open.

Installation Methods Shafts should be installed using dry methods.

Groundwater control

Seepage was observed in the borings. Seepage can be encountered during installation of the shafts, particularly during wet periods of the year. If groundwater seepage is encountered during the installation of underreamed shafts, shafts can be elevated slightly to avoid the seepage. Terracon should be contacted for additional recommendations if shafts must be elevated more than 2 feet.

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ACIP Construction Considerations

Installation of adjacent piles with a clear distance spacing of less than ten pile diameters should be delayed until grout in the initial pile has set. This is required to avoid possible grout intrusion between the piles, which could jeopardize pile integrity.

Proper ACIP installation is highly operator-dependent and requires a greater than average dependence on quality workmanship and quality control monitoring. In addition, the successful ACIP completion largely depends on the equipment and installation procedures. The auger should be withdrawn in a controlled manner and a sufficient head of grout should always be maintained in the augers, to prevent necking of fluid grout due to hydrostatic pressures. An ACIP load test is recommended to confirm the design values provided in this report.

The ACIP installation process should be performed under direction of the Geotechnical Engineer.

The Geotechnical Engineer should document the pile installation process including soil/rock and groundwater conditions encountered, consistency with expected conditions, and details of the installed pile.

Grade Beams

All grade beams should be supported by drilled and underreamed shafts and ACIP piles. A minimum void space of 12 inches is recommended between the bottom of grade beams and pier cap extensions and the subgrade. This void will serve to reduce distress resulting from swell pressures generated by the clay soils. Structural cardboard forms are one acceptable means of providing the void space beneath cast-in-place elements. Soil retainers should be used to prevent infilling of the void.

The grade beams should be formed rather than cast against earth trenches. Backfill against the exterior face of grade beams, wall panels and pier caps should be on site materials placed and compacted as described in Fill Compaction Requirements.

FLOOR SLABS

Lightly loaded floor slabs and flatwork placed on-grade will be subject to movement as a result of moisture induced volume changes in the active soils that can occur following construction. The soils expand (heave) with increases in moisture and contract (shrink) with decreases in moisture.

The movement typically occurs as post construction heave.

The potential magnitude of the moisture induced movements is rather variable. It is influenced by the soil properties, overburden pressures, thickness of clay and to a great extent by soil moisture levels at the time of construction. Based on the soil type and thickness encountered in the borings, potential vertical movements in slabs placed on grade are estimated to range from 5 to 6 inches for dry soil conditions.

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Structural Floor System

The building floor slab should be structurally supported above the subgrade to reduce the risk of differential movements between the new floor slab and the existing floor slab. A minimum void space of 12 inches is recommended beneath the slab. The minimum void space can be provided by the use of cardboard carton forms, or a deeper crawl space. A ventilated and drained crawl space is recommended under the building additions for several reasons, including the following:

■ Ground movements will affect the project utilities, which can cause breaks in the lines and distress to interior fixtures.

■ A crawl space permits utilities to be hung from the superstructure, which greatly reduces the possibility of distress due to ground movements. It also can provide ready access in the event repairs are necessary.

■ Ground movements are uneven. A crawl space can be positively drained preventing the ponding of water and reducing the possibility of distress due to unexpected ground movements.

SEISMIC CONSIDERATIONS

The seismic design requirements for buildings and other structures are based on Seismic Design Category. Site Classification is required to determine the Seismic Design Category for a structure.

The Site Classification is based on the upper 100 feet of the site profile defined by a weighted average value of either shear wave velocity, standard penetration resistance, or undrained shear strength in accordance with Section 20.4 of ASCE 7 and the International Building Code (IBC).

Based on the soil/bedrock properties encountered at the site and as described on the exploration logs and results, it is our professional opinion that the Seismic Site Classification is C.

Subsurface explorations at this site were extended to a maximum depth of 50 feet. The site properties below the boring depth to 100 feet were estimated based on our experience and knowledge of geologic conditions of the general area. Additional deeper borings or geophysical testing may be performed to confirm the conditions below the current boring depth.

PAVEMENTS

Pavement Subgrades

The entrance drive and drop-off lane consist of asphaltic concrete with concrete curbs. The section of the pavement drive in front of the building and the drop off lane is planned to be replaced with Portland cement concrete. The pavement subgrade consists of clay soils that have a potential to shrink or swell with changes in subgrade moisture contents. The pavement movement design criteria provided by the Foresite Group, LLC is one inch. Alternative subgrade treatment

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Pavement Subgrade Compaction Alternative

The pavement subgrade soils have characteristics that indicate a high shrink-swell potential of several inches. The existing driveway asphalt pavement has numerous longitudinal cracks but does not have depressions or mounds in front of the building as often observed in active clay sites. The pavement curbs do not show signs of large differential movements. The sidewalks at street crossings do not exhibit differential movements between the pavement and sidewalks.

Subgrade moisture equilibration under the existing pavement has likely occurred given the length of time the pavement has been in place. The mature trees adjacent to the pavement have not created concentric cracks mirroring the drip line of the trees that are frequently observed where trees are present next to roadway pavements.

A concrete drive is present at the back of the building that begins at Hospital Boulevard. The pavement appears to have performed satisfactorily. The performance of the planned pavement sections in front of the clinic, would in our opinion, perform in a similar manner as the back entrance driveway. If this pavement performance is acceptable and considering the type of traffic, we recommend that the new pavement in front of the building be placed on a six inch compacted subgrade.

Pavement Subgrade Moisture Conditioned Alternative

If the performance of the back entrance driveway is judged unsatisfactory by the owner, the risk of potential pavement movements could be reduced by water or chemical injection. Injections to seven feet are estimated to be required to reduce potential swelling movements to about one inch and injections to five feet to reduce potential movements to about two inches. A minimum 12 inch thick crushed stone flexible base layer is required above the injected subgrade to help reduce moisture losses and to restore pavement support on the softened injected clay subgrade.

Injecting the pavement subgrade should only be considered if there is no risk of penetrating a water, sanitary sewer, gas, fiber, and/or electrical lines with the injection rods. Swelling of the injected clays can occur that can require regrading of the pavement subgrade and lifting of adjacent sidewalks. Care will be required to control the injection adjacent to the slopes between the drive lane and the parking lot so that the injection fluids do not exit from the face of the slope.

In addition, the impact on schedule and costs should be considered. Multiple injection passes and associated confirmation boring and swell testing could be required resulting in project delays.

The area to be injected should first be graded to the bottom of the flexible base cap. The injection should extend at least two feet beyond the edge of the pavement where flatwork is not present.

The injection acceptance criteria are obtaining an average swell under overburden pressure of one present and with no swell test result above two percent swell. The injection process should

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The effectiveness of the water injection should be evaluated by soil borings and laboratory tests following a 24-hour curing period. Three borings should be continuously sampled to the injected to ten feet in the injected surface area. Laboratory tests should be performed on tube samples (not cuttings) to measure the soil moisture content and hand penetrometer resistance at one-foot intervals. A minimum of four absorption swell tests should be performed in each boring.

Additional injections will be required if swell reduction criteria are not met.

Initial penetration with the injection rods may be difficult for soils in a dry condition. It is not possible to predict the actual number of injection passes required to properly moisture condition the active clay soils. Multiple injections should be anticipated.

Pavement Design Parameters

The AASHTO 1993 design methodology was used to design the concrete pavements. Equivalent Single Axle Loads (ESAL’s) of 25,000 for automobile traffic was provided to us by Foresite Group, LLC. Pavement will be subject to ESAL’s of 60,000 for fire truck.

Design Value Description

Concrete Flexural Strength, psi 550

Concrete Modulus of Elasticity, ksi 3,700,000

CBR 2

Resilient Subgrade Modulus, ksi 3,000

Reliability 80

Design Life, years 20

Initial Service Index 4.5

Final Service Index 2.25

Pavement Section Thickness

The following table provides option for Portland Cement Concrete (PCC) Pavement Sections:

Minimum Portland Cement Pavement Thickness

Traffic Area Portland Cement Concrete

Compacted Subgrade

Compacted Flexible Base

Total Thickness

Light Duty 5 inches 6 inches 0 11 inches

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Minimum Portland Cement Pavement Thickness

Traffic Area Portland Cement Concrete

Compacted Subgrade

Compacted Flexible Base

Total Thickness

Heavy Duty 6 inches 6 inches 0 16 inches

Light Duty 5 inches 0 12 inches 17 inches

Heavy Duty 6 inches 0 12 inches 18 inches

The concrete should have a minimum 28-day compressive strength of 4,000 psi and meet the City of Grand Prairie requirements in fire lanes. The concrete should contain a minimum of 4.5±1.5 percent entrained air. As a minimum, the section should be reinforced with No. 3 bars on 18-inch centers in both directions.

Pavement Maintenance

The pavement sections represent minimum recommended thicknesses and, as such, periodic maintenance should be anticipated. Therefore, preventive maintenance should be planned and provided for through an on-going pavement management program. Maintenance activities are intended to slow the rate of pavement deterioration and to preserve the pavement investment.

Maintenance consists of both localized maintenance (e.g., crack and joint sealing and patching) and global maintenance (e.g., surface sealing). The joint area between the Portland cement concrete section and the asphaltic concrete pavement is like to require the greatest continuing maintenance requirements.

Preventive maintenance is usually the priority when implementing a pavement maintenance program. Additional engineering observation is recommended to determine the type and extent of a cost-effective program. Even with periodic maintenance, some movements and related cracking may still occur, and repairs may be required.

Pavement performance is affected by its surroundings. In addition to providing preventive maintenance, the civil engineer should consider the following recommendations in the design and layout of pavements:

■ Subgrade and pavement surfaces should have a minimum 2% slope to promote proper surface drainage.

■ Install joint sealant and seal cracks immediately.

■ Seal all landscaped areas in or adjacent to pavements to reduce moisture migration to subgrade soils.

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

■ Place curb, gutter and/or sidewalk directly on clay subgrade soils rather than on unbound granular base course materials.

May 20, 2022 ■ Terracon Project No.94225110-R1

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GENERAL COMMENTS

Our analysis and opinions are based upon our understanding of the project, the geotechnical conditions in the area, and the data obtained from our site exploration. Natural variations will occur between exploration point locations 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 pertinent construction phases. 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 studies should be undertaken.

Our services and any correspondence or collaboration through this system 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 to support the services provided by Terracon to our client.

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.

Site safety, and cost estimating including, excavation support, and dewatering requirements/design are the responsibility of others. If changes in the nature, design, or location of the project are planned, our conclusions and recommendations shall not be considered valid unless we review the changes and either verify or modify our conclusions in writing.

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ATTACHMENTS

May 20, 2022 ■ Terracon Project No.94225110-R1

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

EXPLORATION AND TESTING PROCEDURES

Field Exploration

Borings id Boring Depth (feet) Location

B-1 through B-4 50 See Exploration Plan

Boring Layout and Elevations: Unless otherwise noted, Terracon personnel provided the boring layout. Coordinates were obtained with a handheld GPS unit (estimated horizontal accuracy of about ±10 feet) and approximate elevations were obtained from Google Earth. If a more precise boring layout and more precise surface elevations are desired, we recommend borings be surveyed.

Subsurface Exploration Procedures: We advanced the borings with a truck-mounted, rotary drill rig using continuous flight augers. Soil samples were obtained using thin-walled tube sampling procedures, also split spoon sampling was used to retrieve a sample from boring B-3 at depth of

43.5 feet. In the thin-walled tube sampling procedure, a thin-walled tube is pushed hydraulically into the soil to obtain a relatively undisturbed sample. In the split-barrel sampling procedure, a split-barrel sampling spoon is driven into the ground. The load-carrying capacity of bedrock was evaluated in place by the modified Texas Department of Transportation (TxDOT) cone penetration test.

Soil samples were placed in appropriate containers, taken to our laboratory for testing, and classified under the direction of a geotechnical engineer. In addition, we observed and recorded groundwater levels during drilling and sampling. For safety purposes, all borings are backfilled with auger cuttings after their completion.

Our exploration team prepared field boring logs as part of the standard drilling operations. These field logs include visual classifications of the materials encountered during drilling and our interpretation of the subsurface conditions between samples. Final boring logs are prepared from the field logs. The final boring logs represent the geotechnical engineer's interpretation of the field logs and include modifications based on observations and tests of the samples in our laboratory.

Laboratory Testing

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

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

May 20, 2022 ■ Terracon Project No.94225110-R1

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

■ Water (Moisture) Content of Soil

■ Liquid Limit, Plastic Limit, and Plasticity Index of Soils

■ Unconfined Compressive Strength of Cohesive Soils

■ Material Finer than 75-μm (No. 200) Sieve

■ Absorption Swell Tests

■ Unit Dry Weight

Absorption swell tests were performed on selected samples. These tests were used to quantitatively evaluate volume change potential at in-situ moisture levels. Selected samples were also tested for soluble sulfates. The results of these tests are presented in the following tables.

SWELL TEST RESULTS

Boring No.

Depth (feet)

Liquid Limit

Plasticity Index

Initial Moisture

Final Moisture

Surcharge (psf)

Swell

B-2 8-10 59 41 13.4 20.0 1,125 0.0

B-3 2-4 65 46 22.4 25.7 375 2.0

B-4 8-10 Not Tested

Not Tested 26.3 28.4 1,125 1.0

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SITE LOCATION AND EXPLORATION PLANS

Contents:

Site Location Plan Exploration Plan

Note: All attachments are one page unless noted above.

SITE LOCATION

May 20, 2022 ■ Terracon Project No.94225110-R1

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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 PORTRA IT

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

EXPLORATION PLAN

May 20, 2022 ■ Terracon Project No.94225110-R1

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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.

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EXPLORATION P LAN

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

Approximate Limits of New

Pavement

EXPLORATION RESULTS

Contents:

Boring Logs (B-1 through B-4) GeoModel

4.0 (HP)

4.5 (HP)

4.5+ (HP)

4.5 (HP)

4.0 (HP)

4.5 (HP)

4.5+ (HP)

3.5 (HP)

25.0

30.8

17.9

33.8

61-19-42

79-30-49

TOPSOIL, 6 inches FAT CLAY (CH), dark brown, very stiff

FAT CLAY (CH), tan, very stiff, with calcareous seams

FAT CLAY (CH), silty, tan, very stiff

FAT CLAY (CH), shaley, silty, tan, very stiff

0.5

6.0

16.0

20.0

582.5

Lattitude and longitude were obtained with hand-held GPS device.

Elevation was obtained from Google Earth.

3.8

3.6

3.33

3.51UC

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

T H

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W A

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S STRENGTH TEST

F

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LL-PL-PI

ATTERBERG

LIMITSLOCATION See Exploration Plan

Latitude: 32.7346° Longitude: -97.0501°

G R

A P

H

IC

L O

G

M O

D E

L

LA

Y E

R

DEPTH ELEVATION (Ft.)

Surface Elev.: 583 (Ft.)

Advancement Method:

Dry Auger

Abandonment Method:

Boring backfilled with auger cuttings upon completion.

Notes:

Project No.: 94225110

Drill Rig: Truck-mounted

BORING LOG NO. B-1

Valiant Construction LLCCLIENT:

Louisville, KY

Driller: CoreCo USA

Boring Completed: 04-15-2022

PROJECT: VA Outpatient Expansion Gand Prairie

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.

2737 Sherman St Grand Prairie, TX

SITE:

Boring Started: 04-15-2022

8901 John W Carpenter Fwy Ste 100 Dallas, TX

While drilling

At completion of drilling

WATER LEVEL OBSERVATIONS

S T

R A

IN

C O

M P

R E

S S

IV

E

S T

R E

N G

T H

(t sf

T E

S T

T Y

P E

P E

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E N

T F

IN

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S

S A

M P

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T

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4.0 (HP)

4.5+ (HP)

TC=100/5.5"

TC=100/2.5"

30.3 93

FAT CLAY (CH), shaley, silty, tan, very stiff (continued)

FAT CLAY (CH), silty, light gray and tan, very stiff

WEATHERED SHALE, gray

Boring Terminated at 50 Feet

30.0

44.0

50.0

6.33.63UC

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

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LL-PL-PI

ATTERBERG

LIMITSLOCATION See Exploration Plan

Latitude: 32.7346° Longitude: -97.0501°

G R

A P

H

IC

L O

G

M O

D E

L

LA

Y E

R

DEPTH ELEVATION (Ft.)

Surface Elev.: 583 (Ft.)

Advancement Method:

Dry Auger

Abandonment Method:

Boring backfilled with auger cuttings upon completion.

Notes:

Project No.: 94225110

Drill Rig: Truck-mounted

BORING LOG NO. B-1

Valiant Construction LLCCLIENT:

Louisville, KY

Driller: CoreCo USA

Boring Completed: 04-15-2022

PROJECT: VA Outpatient Expansion Gand Prairie

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.

2737 Sherman St Grand Prairie, TX

SITE:

Boring Started: 04-15-2022

8901 John W Carpenter Fwy Ste 100 Dallas, TX

While drilling

At completion of drilling

WATER LEVEL OBSERVATIONS

S T

R A

IN

C O

M P

R E

S S

IV

E

S T

R E

N G

T H

(t sf

T E

S T

T Y

P E

P E

R C

E N

T F

IN

E

S

S A

M P

LE

T

Y

4.5+ (HP)

4.5+ (HP)

4.5+ (HP)

4.5+ (HP)

4.5+ (HP)

3.0 (HP)

3.0 (HP)

4.0 (HP)

16.7

16.7

17.2

13.4

28.2

59-18-41

61-18-43

TOPSOIL, 6 inches FAT CLAY (CH), dark brown, hard

FAT CLAY (CH), light brown and tan, very stiff to hard, with calcareous seams

FAT CLAY (CH), silty, tan, very stiff

0.5

6.0

15.0

582.5

Lattitude and longitude were obtained with hand-held GPS device.

Elevation was obtained from Google Earth.

11.3

3.7

8.64

2.96

UC

UC

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

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W A

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A T

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LL-PL-PI

ATTERBERG

LIMITSLOCATION See Exploration Plan

Latitude: 32.7346° Longitude: -97.0497°

G R

A P

H

IC

L O

G

M O

D E

L

LA

Y E

R

DEPTH ELEVATION (Ft.)

Surface Elev.: 583 (Ft.)

Advancement Method:

Dry Auger

Abandonment Method:

Boring backfilled with auger cuttings upon completion.

Notes:

Project No.: 94225110

Drill Rig: Truck-mounted

BORING LOG NO. B-2

Valiant Construction LLCCLIENT:

Louisville, KY

Driller: CoreCo USA

Boring Completed: 04-15-2022

PROJECT: VA Outpatient Expansion Gand Prairie

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.

2737 Sherman St Grand Prairie, TX

SITE:

Boring Started: 04-15-2022

8901 John W Carpenter Fwy Ste 100 Dallas, TX

While drilling

At completion of drilling

WATER LEVEL OBSERVATIONS

S T

R A

IN

C O

M P

R E

S S

IV

E

S T

R E

N G

T H

(t sf

T E

S T

T Y

P E

P E

R C

E N

T F

IN

E

S

S A

M P

LE

T

Y

3,5 (HP)

4.5 (HP)

TC=100/1.25"

TC=100/2.5"

28.6 92

FAT CLAY (CH), silty, tan, very stiff (continued)

FAT CLAY (CH), silty, light gray, very stiff

SHALE, gray

Boring Terminated at 50 Feet

35.0

44.0

50.0

2.32.33UC

Hammer Type: AutomaticStratification lines are approximate. In-situ, the transition may be gradual.

T H

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W A

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S STRENGTH TEST

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W A

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W E

IG

H

T pc f)

LL-PL-PI

ATTERBERG

LIMITSLOCATION See Exploration Plan

Latitude: 32.7346° Longitude: -97.0497°

G R

A P

H

IC

L O

G

M O

D E

L

LA

Y E

R

DEPTH ELEVATION (Ft.)

Surface Elev.: 583 (Ft.)

Advancement Method:

Dry Auger

Abandonment Method:

Boring backfilled with auger cuttings upon completion.

Notes:

Project No.: 94225110

Drill Rig: Truck-mounted

BORING LOG NO. B-2

Valiant…