VA LTSCI Bid Pack B Suppl Info part 2of2 g.pdf

BID PACKAGE B – SUPPLEMENTAL INFORMATION LTSCI PROJECTS

DATE: 14 JULY 2021 VANTHCS, DALLAS, TX

PROJECT 549-820B

Tab E-LTSCI GeoTech Report and Addendums

(REV 10 AUGUST 2022)

this page left blank intentionally

Geotechnical Engineering Report

Veterans Affairs – North Texas Healthcare System 4500 South Lancaster Road

Dallas, Texas June 18, 2010

Terracon Project No. 94105089

Prepared for:

PageSoutherlandPage, LLP

Dallas, Texas

Prepared by:

Terracon Consultants, Inc.

Dallas, Texas

TABLE OF CONTENTS

Page

1.0 INTRODUCTION

2.0 PROJECT INFORMATION

2.1 Site Location and Description

2.2 Project Description

3.0 SUBSURFACE CONDITIONS

3.1 Local Geology

3.2 Site Investigation

3.3 Typical Profile

3.4 Groundwater

4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION

4.1 Geotechnical Considerations

4.2 Deep Foundations

4.2.1 Allowable Net Bearing Pressures

4.2.2 Lateral Capacity

4.2.3 Uplift Resistance

4.2.4 Drilled Shaft Construction Considerations

4.2.5 Seismic Considerations

4.2.6 Grade Beams/Pier Caps

4.3 Floor System

4.3.1 Structural Floor Slabs

4.3.2 Floor Slabs/Flatwork on Modified Subgrade

4.4 Below Grade Construction

4.4.1 Excavations

4.4.2 Below Grade Walls

4.4.3 Wall Backfill Settlement

4.4.4 Basement Wall Drainage

4.4.5 Sub-Floor Drainage Systems

4.5 Earthwork

4.5.1 Suitable Fill and Subgrade Preparation

4.5.2 Select Fill

4.5.3 Compaction Requirements

4.5.4 Drainage and Utilities

4.6 Area Paving

4.6.1 Pavement Subgrades

4.6.2 Pavement Traffic

4.6.3 Pavement Sections

5.0 GENERAL COMMENTS

APPENDIX A – FIELD EXPLORATION

Exhibit A-1 Boring Location Plan Exhibits A-2 through A-43 Logs of Borings Exhibit A-44 Field Exploration Description

APPENDIX B – LABORATORY TESTING

Exhibit B-1 Laboratory Testing

APPENDIX C – SUPPORTING DOCUMENTS

Exhibit C-1 General Notes Exhibit C-2 Unified Soil Classification

Reliable ■ Responsive ■ Convenient ■ Innovative 1

GEOTECHNICAL ENGINEERING REPORT

VETERANS AFFAIRS – NORTH TEXAS HEALTHCARE SYSTEM

DALLAS, TEXAS

Terracon Project No. 94105089

June 18, 2010

1.0 INTRODUCTION

Several new structures are planned on the VA Medical Center campus located at 4500 South Lancaster in Dallas, Texas. Our scope of services included drilling and sampling thirty-four borings, laboratory testing, and engineering analyses. The purpose of these services is to provide information and geotechnical engineering recommendations relative to:

subsurface soil conditions groundwater conditions earthwork foundation design and construction seismic considerations floor slab design and construction below grade construction pavement and associated drives

2.0 PROJECT INFORMATION

2.1 Site Location and Description

Item Description

Location 4500 South Lancaster Road in Dallas, Texas. The site is bounded by East Ann Arbor Drive to the north, South Lancaster Road to the west, and Veterans Drive to the east.

Existing structures The site is an existing facility, with multi-story hospital buildings, administrative and office buildings, and site parking.

Current ground cover Portions of the ground are paved with landscaping and islands.

Grassy areas are also present.

Existing topography

The site has a maximum elevation of about 545 in the north central portion of the site. From the highest elevation, the site drains in a dome. The lowest elevation of the work area lies near the central southern end of the site, at about elevation 518.

2.2 Project Description

Item Description

Site layout See Appendix A, Exhibit A-1, Boring Location Plan.

Buildings

6-story concrete-frame hospital building (Mental Health Building) 3-story concrete frame hospital building (LTSCI Building) 5-story concrete frame parking garage (east) 5-story concrete frame parking garage (west) 2-story steel frame warehouse

Veterans Affairs - North Texas Healthcare System ■ Dallas, Texas June 18, 2010 ■ Terracon Project No. 94105089

Reliable ■ Responsive ■ Convenient ■ Innovative 2

Item Description

Finished floor elevations

6-story Mental Health building: elevation 538.5 3-story LTSCI building: elevation 535.2 5-story parking garage (east): 529.5 5-story parking garage (west): 525 2-story warehouse: 527

Maximum column loads

6-story Mental Health building: 1,600 kips 3-story LTSCI building: 850 kips Parking garages: 960 kips 2-story warehouse: 408 kips

Maximum assumed allowable vertical movement

Columns: ½ inch Walls: 1 inch Floor Slab: 1 inch

Cut and fill slopes 3H:1V (Horizontal to Vertical) max (recommended)

Below grade areas

Mental Health building: Basement level at 516 LTSCI building: Basement level at 519.2 Sub-basement at 501.2 Parking garage (west): Level B at 514.50

3.0 SUBSURFACE CONDITIONS

3.1 Local Geology

The site is situated on the outcrop of the Austin Chalk Formation of Cretaceous Age. The Austin is chalky limestone with interbedded marl. In full section the Austin is over 700 feet thick and dips to the southeast approximately 2 degrees. Locally the Austin may be divided into three parts. The upper part contains more limestone than marl. The middle is composed of weaker limestone with thick beds of marl and the lower part consists of massive limestone with thin shale partings.

Considerable faulting has occurred in the formation. The faults are no longer considered active.

Displacements are normally less than 5 feet, but can exceed 30 feet. The Austin is not water bearing; however, groundwater often is found in the fracture zones associated with faults.

3.2 Site Investigation

Subsurface conditions were explored by drilling thirty-four borings at the approximate locations indicated on Exhibit A-1 in Appendix A. Logs of borings are presented on Exhibits A-2 through A-43. A description of the field work is presented on Exhibit A-44.

Laboratory tests were performed to evaluate soil engineering characteristics. A brief description of the tests is presented on Exhibit B-1 in Appendix B.

Reliable ■ Responsive ■ Convenient ■ Innovative 3

3.3 Typical Profile

Conditions encountered at each boring location are indicated on the individual boring logs.

Stratification boundaries on the boring logs represent the approximate location of changes in soil types; in-situ, the transition between materials may be gradual. Details for each of the boring locations can be found on the boring logs in Appendix A of this report.

Based on the results of the borings, subsurface conditions on the project site can be generalized as follows:

Stratum Approximate Depth to Bottom of Stratum Material Encountered

Consistency/ Classification

Pavementa 4 to 6 inches Concrete or asphalt pavement

N/A

Stratum 1b At the surface or beneath the pavements, extending to depths of about 1 to 12 feet.

Fill materials consisting of clays, silty clays, sands, gravelly sands, silty sands, clayey sands, and processed limestone.

Clays: stiff to hard; CH and CL

Sands: medium dense to dense; SW, SP, and SC

Stratum 2c

Beneath the fill materials, pavements, or at the surface, extending to depths of about 2 to 12 feet. Boring B-24 terminated in this stratum at a depth of about 5 feet.

Tan, brown, dark brown, gray, and dark gray clays.

Stiff to hard Fat clays (CH)

Stratum 3d

Beneath Stratum 2 or beneath the fill materials, extending to depths of about 2 to 14½ feet.

Borings B-23 through B-27, and B-37 through B-39 terminated in this stratum at depths of about 5 feet.

Tan and brown silty clays.

Stiff to hard

Lean clays (CL)

Stratum 4 Beneath Stratum 2 or Stratum 3, extending to depths of about 7 to 27 feet.

Tan limestone. Clay layers were occasionally encountered. A gray limestone layer was observed in Boring B-17.

Hard

Stratum 5

Beneath Stratum 4, extending to termination depths of about 25 to 50 feet in the remaining borings.

Gray limestone Hard

Note a: Pavement materials were encountered in Borings B-4, B-5, B-8 through B-18, B-23, B-29 through B-32, B-35, and B-36.

Note b: Fill materials were not encountered in Borings B-4, B-10, B-17, B-28, B-33, B-35, or B-36.

Note c: Fat clays were not encountered in Borings B-13, B-15, B-18, B-19, B-22, B-29, B-30, B-35, or B-36.

Note d: Silty clays were not encountered in Borings B-2, B-5, B-8 through B-12, B-16, B-18, B-20, or B-24.

Reliable ■ Responsive ■ Convenient ■ Innovative 4

3.4 Groundwater

The borings were advanced in the dry using auger drilling techniques, which allows short-term groundwater observations to be made while drilling. Groundwater was not observed either during drilling or following the completion of drilling in the borings during the subsurface investigation.

Groundwater conditions may be different at the time of construction. Seasonal seepage typically occurs above the tan limestone. Groundwater may also be present in fissures and fractures within the limestone. Conditions may change because of seasonal variations in rainfall and landscape irrigation.

4.0 RECOMMENDATIONS FOR DESIGN AND CONSTRUCTION

4.1 Geotechnical Considerations

Based on the conditions encountered in the borings and the expected column loads, straight drilled shafts bearing in the gray limestone are recommended to support the structures at this site.

The potential for vertical movement in slabs and flatwork on grade varies from on the order of 1 to 4 inches for dry subgrade conditions. Due to the presence of expansive soils on this site, movement and cracking in the building floor slabs should be anticipated if supported on the clays. Floor slabs can be supported on a prepared or modified subgrade to achieve an estimated slab movement of about ½ to 1 inch. If the building floor slab movement must be limited to less than ½ to 1 inch, a floor system structurally suspended above the subgrade is recommended.

Below grade construction is anticipated for the Mental Health building, LTSCI building, and the parking garage on the western side of the site. Additionally, a tunnel system is planned between existing and future buildings.

Asphaltic concrete pavement or portland cement concrete pavement can be used at this site. If asphaltic concrete is used, the subgrade should be stabilized with lime. These pavements are not equal in performance. The portland cement concrete pavement is expected to require less maintenance.

Geotechnical recommendations for building foundations, floor slab support, below grade construction, pavement, and earthwork are presented in the following report sections.

Reliable ■ Responsive ■ Convenient ■ Innovative 5

4.2 Deep Foundations

4.2.1 Allowable Net Bearing Pressures

Foundation loads can be supported by straight drilled shafts bearing in the gray limestone. The drilled shafts can be designed for a combination of end bearing and skin friction resistance in the gray limestone. Design recommendations are included in the following table.

Design Parameter Recommendation

Bearing stratum Gray limestone

Allowable end bearing resistance 40,000 psf

Allowable skin friction in compression or tension 8,000 psf

Minimum penetration to develop end bearing 3 feet or 1 shaft diameter, whichever is greater

Penetration to develop skin friction Depth below any temporary casing in gray limestone

Minimum center to center spacing to develop full skin friction

2.5 times the diameter of the larger shaft. Closer spacing may require some reductions in skin friction and/or changes in installation sequences. Closely spaced shafts should be examined on a case by case basis. As a general guide, the design skin friction will vary linearly from the full value at a spacing of 2.5 diameters to 50 percent of the design value at 1.0 diameter.

Groups of 3 or more shafts spaced closer than

2.5 shaft diameters

Should be evaluated on a case by case basis by this office. Alternative installation sequences may be needed to allow for a minimum of 48 hours concrete curing time, before installation of adjacent shafts

Minimum shaft diameter 1.5 feet

Settlement Less than ¼ inch

Reliable ■ Responsive ■ Convenient ■ Innovative 6

4.2.2 Lateral Capacity

The drilled shafts may be subject to lateral loads. The parameters for lateral load analysis are provided in the follow tables for use in Ensoft’s L-PILE (version 5.03) computer program.

Soil Type Clay Soils Tan Limestone Gray Limestone

LPILE Material Type Stiff clay w/o free water

Weak Rock (Reese)

Weak Rock (Reese)

Effective Soil Unit Weight (pci) 0.069 0.075 0.078

Undrained Cohesion, c (psi) O

V E

R B

U R

D E

N

S O

IL

S

15 N/A N/A p-y Modulus, k (pci) 225 N/A N/A

Strain Factor, є50 0.005 N/A N/A

Young’s Modulus, Er (psi)

B E

D R

O C

K

N/A 15,000 33,000

Uniaxial Compressive Strength (psi) N/A 150 330

Rock Quality Designation, RQD (%) N/A 80 90

Krm N/A 0.0005 0.0003

4.2.3 Uplift Resistance

The drilled shafts 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 must contain sufficient continuous vertical reinforcing and embedment depth to resist the net tensile load.

For the conditions encountered at this site, the uplift load can be approximated by assuming a uniform uplift of 1,800 psf over the shaft perimeter for a depth of 10 feet or to the top of tan limestone, whichever is more shallow. If the subgrade is moisture conditioned as discussed in the “Floor Slabs/Flatwork on Modified Subgrade” section, a uniform uplift of 1,200 psf can be used. If the subgrade is replaced with select fill, uplift forces can be neglected for drilled shafts installed through the select fill.

4.2.4 Drilled 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 penetration depth; 3) that groundwater seepage is correctly handled; and 4) that the shafts are within acceptable vertical tolerance.

Reliable ■ Responsive ■ Convenient ■ Innovative 7

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

Item Recommendation

Drilled shaft 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 Drilled shaft construction should be completed within 8 hours of beginning the design penetration in a continuous manner to reduce side wall and base deterioration

Drilled shaft construction Shaft excavations should be installed using dry methods

Temporary Casing Temporary casing may be required to seal off groundwater.

Special conditions Fractures in the gray limestone may result in water entering the drilled shafts. This can require extending the casing and deepening the shafts.

4.2.5 Seismic Considerations

Code Used Site Classification

2006 International Building Code (IBC) 1 C 2

1. In general accordance with the 2006 International Building Code, Table 1613.5.2.

2. The 2006 International Building Code (IBC) requires a site soil profile determination extending a depth of 100 feet for seismic site classification. The current scope requested does not include the required 100 foot soil profile determination. Borings extended to a maximum depth of approximately 50 feet and this seismic site class definition considers that hard rock extends below the maximum depth of the subsurface exploration, which is consistent with the site geology. Additional exploration to deeper depths would be required to confirm the conditions below the current depth of exploration.

Alternatively, a geophysical exploration could be utilized to attempt to justify a higher seismic site class.

4.2.6 Grade Beams/Pier Caps

In conjunction with drilled shafts, all grade beams or wall panels should be supported by the drilled shafts. For each building location, the recommended amount of void space between the bottom of grade beams, pier cap extensions or wall panels and the subgrade is shown in the following table. This void will serve to minimize distress resulting from swell pressures generated by the clays. Structural cardboard forms are one acceptable means of providing this

Reliable ■ Responsive ■ Convenient ■ Innovative 8 void beneath cast-in-place elements. Soil retainers should be used to prevent infilling of the void. A void is not necessary beneath elements cast on limestone.

BUILDING MINIMUM VOID SPACE BENEATH

GRADE BEAMS/WALL PANELS

6-story Mental Health building 4 inches

3-story LTSCI building 8 inches

5-story parking garage (west) 6 inches

5-story parking garage (east) 8 inches

2-story steel warehouse 6 inches

The grade beams should be formed rather than cast against earth trenches. Backfill against the exterior face of grade beams and wall panels should be properly compacted onsite clays.

Compaction should be a minimum of 92 percent of ASTM D698, at a minimum of +3 percent above the optimum moisture content determined by that test.

4.3 Floor System

Lightly loaded floor slabs placed on-grade will be subject to movement as a result of moisture induced volume changes in the active soils. 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 indeterminate. It is influenced by the soil properties, overburden pressures, and to a great extent by soil moisture levels at the time of construction. The potential for movement of slabs-on-grade will vary for the buildings across the site, based on the depth to rock and the soil types encountered in the borings. We estimate the potential movements for each building as shown in the following table.

BUILDING ESTIMATED POTENTIAL

MOVEMENTS

6-story Mental Health building 1 to 2 inches

3-story LTSCI building About 4 inches

5-story parking garage (west) About 3 inches

5-story parking garage (east) About 4 inches

2-story steel warehouse About 3 inches

Reliable ■ Responsive ■ Convenient ■ Innovative 9

The building slabs can be supported on a modified subgrade to reduce soil movements to about ½ to 1 inch. A structural slab is recommended if foundation movements are to be limited to less than ½ inch. Note that movements of ½ to 1 inch can result in uneven floors, sticking doors, and cracking of floor slabs and wall partitions. If the risk of these movements is unacceptable, the floor slab should be structural.

4.3.1 Structural Floor Slabs

Building floor slabs should be structurally supported above the subgrade if movements are to be limited to less than ½ to 1 inch. The minimum void space for each building location is provided in the following table.

BUILDING MINIMUM VOID SPACE

BENEATH STRUCTURAL SLABS

6-story Mental Health building 6 inches

3-story LTSCI building 12 inches

5-story parking garage (west) 9 inches

5-story parking garage (east) 12 inches

2-story steel warehouse 9 inches

The minimum void space can be provided by the use of cardboard carton forms, or a deeper crawl space. The bottom of the void should preferably be higher than adjacent exterior grades.

A ventilated and drained crawl space is preferred under the building 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.

4.3.2 Floor Slabs/Flatwork on Modified Subgrade

Slab on-grade construction should only be considered if slab movements on the order of ½ to 1 inch are considered acceptable. Reductions in anticipated movements can be achieved by using methods developed in this area to reduce on-grade slab movements. Suitable methods for this site consist of placing select fill beneath the slab and/or moisture conditioning the on-site clays using excavation and replacement.

Reliable ■ Responsive ■ Convenient ■ Innovative 10

Movements on the order of ½ inch can be achieved for the Mental Health building and the west parking garage by excavating the clay soils to the top of the limestone and then using non-expansive select fill to establish the building pad.

Alternatively, it is estimated that movements on the order of 1 inch can generally be achieved by undercutting to the depths indicated in the following table, and moisture conditioning the site soils in conjunction with placement of a one foot cap of select fill. In low areas of the site, fill below the indicated elevation should also be placed as moisture conditioned soil. In the event that tan limestone is encountered during excavations prior to the full moisture conditioning depth, it is not necessary to excavate the limestone.

SLAB-ON-GRADE TREATMENT DEPTHS

BUILDING

ELEV

TOP OF

LIMESTONE

POTENTIAL

VERTICAL

MOVEMENT

RECOMMENDED SUBGRADE TREATMENT

For ½“ movement For 1” movement

6-story Mental Health building

(FFE 538.5) 528 to 535 1 to 2 inches

Installation of select fill to the top of tan limestone

Moisture condition to elev. 532

(Basement FCC 516) N/A No action required No action required

3-story LTSCI building

(FFE 535.2)

518.5 to 512

About 4 inches

N/A Moisture condition to elev. 525

(Basement FFE 519.2) About 2 inches

Installation of select fill to top of limestone

Moisture condition to top of limestone

(Sub-basement FFE 501.2) N/A No action required No action required

5-story parking garage (west)

(FFE 514.5)

522 to 506.5 About 3 inches

Installation of select fill to the top of tan limestone

Moisture condition to elev. 507

5-story parking garage (east)

(FFE 529.5)

520 to 513 About 4 inches

N/A Moisture condition to elev. 519

2-story steel warehouse

(FFE 527)

517.5 to 511 About 3 inches

N/A Moisture condition to elev. 518

The excavated soils, except for deleterious materials or rock greater than 4 inches, can then be replaced in accordance with the “Earthwork” section of this report for moisture conditioned clays. A one foot thick select fill layer is recommended to cap the moisture conditioned soils.

In some instances it is considered advantageous to cap the moisture-conditioned pad with a lime stabilized layer, rather than select fill. This provides a more all weather surface for construction, and is often considered an economic advantage. The lime-stabilized section should be 6 inches deep and follow the TxDOT specifications referenced in the “Pavement

Reliable ■ Responsive ■ Convenient ■ Innovative 11

Recommendations” section of this report. Rutted areas should be repaired prior to placing the slab.

The select fill or lime cap and moisture conditioning processes should be extended beyond the building line to include entrances, abutting sidewalks, and other flatwork areas sensitive to movement.

The use of a vapor retarder should be considered beneath concrete slabs on grade that will be covered with wood, tile, or carpet with a water soluble adhesive. A vapor retarder should be used for other moisture sensitive coverings, impervious coverings, or when the slab will support equipment sensitive to moisture. When conditions warrant the use of a vapor retarder, the slab designer and slab contractor should refer to ACI 302 and/or ACI 360 for procedures and cautions regarding the use and placement of a vapor retarder.

4.4 Below Grade Construction

4.4.1 Excavations

Partial basements and mechanical areas are planned below grade for the Mental Health building and LTSCI building. Finished floor elevations for the below grade areas are planned at 516 and 519.2, respectively. A deeper sub-basement is planned at the LTSCI building, with FFE at 501.2. The parking garage on the west of the site is planning on including one below grade level, with FF of Level B at 514.50. Additionally, several tunnels are planned to connect existing and future buildings together.

Based on the subsurface conditions encountered in the borings, excavations will encounter clays, tan limestone, and harder gray limestone. The overburden soils can be excavated with standard earthwork equipment. Excavations into harder limestone will require rock excavation methods including the use of breaker hoes and large dozers with single tooth rippers. Line drilling can be used to control overbreak at the limits of the excavation. The overburden soils will need to be sloped or braced during construction. Tan and gray limestone can stand at or near vertical cuts. Excavations in the limestone should be observed by qualified geotechnical personnel for adverse features requiring additional support. Applicable OSHA standards should be followed. Consideration should also be given to erosion protection on exposed slopes.

4.4.2 Below Grade Walls

Below grade walls should be supported by straight drilled shafts bearing in the gray limestone as previously recommended. Alternately, the walls can be founded on continuous footings founded in the limestone.

Reliable ■ Responsive ■ Convenient ■ Innovative 12

Footings should be cut a minimum of two feet into the limestone or two feet below the level of the general excavation, where the limestone is exposed. Concrete should be placed directly against the face of the cut with no backfill below the level of the general excavation.

Continuous footings can be designed for an allowable bearing capacity of 7,000 psf in tan limestone and 25,000 psf in gray limestone. The footings should be a minimum of 1.5 feet wide.

These values contain a factor of safety of 3. An ultimate sliding resistance coefficient of 0.40 between the bottom of the footing and the subgrade is recommended for design. The footing should have a factor of safety of at least 1.5 against sliding for transient wind and seismic loads.

For footings founded in limestone, an allowable passive pressure of 5,000 psf may be considered against the face of a key beneath the footing.

The basement walls are expected to be restrained from lateral movements by the interior floor slabs. For these conditions, at-rest earth pressures are recommended for design. The walls should be designed with a drainage system to prevent hydrostatic pressures from developing.

Water proofing should be provided, if the interior of the walls are to remain in a dry state.

Recommended lateral earth pressures, expressed as equivalent fluid pressures, are presented in the following table for a rigid double-formed wall with a drained condition and a level backfill.

The pressures given below assume that select or granular backfill is a minimum of 3 feet wide at the base and slopes back at 1H: 2V. Surcharge loads should be included in the wall design where appropriate. A lateral pressure coefficient of 0.5 is recommended for uniformly distributed surcharge loads.

Backfill Material At-Rest (pcf)

On-site soils 90

Select fill, with Liquid Limit less than 35% and PI less than 15. 65

Granular backfill with less than 3% passing No. 200 sieve and less than 30% passing No. 40 sieve, non-plastic

Wall backfill materials should be placed in loose lifts less, than 9 inches thick, and uniformly compacted to a minimum of 95 percent of the ASTM D 698 maximum dry density in order to reduce backfill settlement. Moisture content during placement of cohesive backfill should be within 0 to +4 percentage points of the optimum moisture content as measured in test method ASTM D 698. Granular backfill should not be water jetted to achieve compaction and should be placed at moisture contents to allow the desired density to be achieved.

The top of the granular backfill should be protected by flatwork, paving or a minimum 2-foot thickness of clay (PI>20) to reduce surface infiltration.

Reliable ■ Responsive ■ Convenient ■ Innovative 13

4.4.3 Wall Backfill Settlement

Settlement of the wall backfill should be anticipated. Piping and conduits through the fill should be designed for potential soil loading due to fill settlement. Vertical pipes in the backfill material can be pulled down and joints opened. The pipe joints should be rigidly connected. Floor slabs, sidewalks, and pavements over fills may also settle. Backfill compacted to the density recommended above is anticipated to settle on the order of one to two percent of the fill thickness.

4.4.4 Basement Wall Drainage

The equivalent fluid pressures presented above assume a drained condition. Drainage must be provided behind the below grade walls to prevent the development of hydrostatic pressures.

A vertical drain is recommended for below grade walls, elevator/mechanical pits, and tunnel walls. This drain may consist of manufactured products such as "Enka-Drain", "Miradrain" or other similar systems. An aggregate drain can also be used. The aggregate drain should meet the gradation requirements presented in the previous table for granular backfill. The vertical drain should be connected to a permanent perimeter drainage system that is located 12 or more inches lower than the bottom of the adjacent below grade slab or crawl space.

The perimeter drain should be a perforated or slotted drain with a minimum pipe diameter of 4 inches. The pipe should be surrounded with at least 6 inches of drainage rock. The drainage rock should be wrapped with an effective geotextile for protection against infiltration. Accessible clean-outs should be provided.

4.4.5 Sub-Floor Drainage Systems

A drainage blanket under the basement floor slabs is recommended to prevent hydrostatic uplift pressures and wet spots on the basement floor slab. The drainage blanket should be at least 6 inches thick and should consist of clean crushed stone that meets the gradation requirements of the ASTM C-33 No. 56 or 57 coarse aggregate. The drainage blanket can be drained by placing drain lines in trenches under the drainage blanket. Sub-floor drain lines should be situated a minimum of 12 inches lower than the bottom of the slab. A filter fabric should be used to separate the drainage material from the subgrade soils.

4.5 Earthwork

4.5.1 Suitable Fill and Subgrade Preparation

The on-site soils, free of vegetation, debris, and rocks greater than 4 inches in maximum dimension, are generally suitable for site grading. If imported fill materials are used, they should

Reliable ■ Responsive ■ Convenient ■ Innovative 14 be clean soil with a Liquid Limit preferably less than 50 percent and no rock greater than 4 inches in maximum dimension.

4.5.2 Select Fill

The material used as select fill should be sandy clay to clayey sand with a Liquid Limit (LL) of less than 35 percent and a Plasticity Index (PI) preferably between 6 and 15. The first lift of select fill should be placed wet of optimum to prevent drying the underlying subgrade. Positive drainage must be provided away from the structure to prevent the ponding of water in the select fill.

As an alternate to select fill, flexible base can be used. The base should meet the requirements of TxDOT Item 247, Type A, Grade 1 or 2. Recycled concrete meeting these requirements is acceptable.

4.5.3 Compaction Requirements

Recommendations for compaction are presented in the following table. We recommend that engineered fill be 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 should be reworked and retested as required until the specified moisture and compaction requirements are achieved.

ITEM DESCRIPTION

Subgrade preparation to receive fill Surface scarified to a minimum depth of 6 inches

Clay and select fill lift thickness 9-inches or less loose lift thickness

Subgrades and fills not under buildings

95% maximum standard Proctor dry density (ASTM D 698) at minimum of +2 percent above optimum moisture content

Moisture conditioned clays under buildings

92% to 98% standard Proctor dry density (ASTM D 698) at minimum of +4 percentage points above optimum moisture content for clays with LL > 60 and +3 percentage points above optimum for clays with LL < 60

Select fill/flexible base 95% maximum standard Proctor dry density (ASTM D 698) -2 to +2 percentage points of optimum moisture content

Utility trench backfill 95% maximum standard Proctor dry density (ASTM D 698) at a minimum of +2 percentage points above optimum moisture content

Reliable ■ Responsive ■ Convenient ■ Innovative 15

4.5.4 Drainage and Utilities

All grades must be adjusted to provide effective drainage away from the structures. Open ground should preferably be sloped at a minimum of 5 percent grade for at least 10 feet beyond the perimeter of the structures. Water permitted to pond near the buildings will result in movements that exceed those discussed in this report. Where paving or flatwork abuts the structures, care should be taken that the joints are properly sealed and maintained to prevent the infiltration of surface water.

Flatwork and pavement will be subject to post construction movement. Maximum grades practical should be used for paving and 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 the “Building/Flatwork Subgrade Modification” section of this report in movement sensitive areas.

Planters located adjacent to the structures 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 line. If heads must be located adjacent to the structures, then service lines off the main should be provided. Roof drains should discharge on pavement or be extended away from the structures. Ideally, roof drains should discharge by closed pipe to the storm drainage system.

Care should be taken that utility trenches are properly backfilled. Backfilling should be accomplished with properly compacted on-site soils. A minimum 3-foot wide, properly compacted clay plug at the building line is recommended to help prevent water from migrating under the building through the utility trench backfill.

4.6 Area Paving

4.6.1 Pavement Subgrades

Subgrade materials at this site will consist of clay soils. These soils are subject to loss of support with the moisture increases that can occur beneath paving. The clay soils react with hydrated lime, which serves to improve and maintain their support value. Lime stabilization is recommended beneath flexible (asphalt) pavement sections. Rigid (concrete) pavements may be placed on compacted subgrade without lime treatment.

For budgeting purposes, 7 percent hydrated lime (TxDOT Item 264), by dry weight, can be used for treating the subgrade beneath flexible pavements. The lime application rate should be determined by laboratory testing once the pavement subgrade is rough graded. The lime should be thoroughly mixed and blended with the top 6 inches of the subgrade (TxDOT, Item 260). Stabilization should extend a minimum of one foot beyond the edge of the pavement.

Reliable ■ Responsive ■ Convenient ■ Innovative 16

The lime stabilized or natural subgrade should then be uniformly compacted to a minimum of 95 percent of ASTM D698 between -1 to +3 percentage points of the optimum moisture content determined by that test. It should then be protected and maintained in a moist condition until the pavement is placed. Pavement subgrades should be graded to prevent ponding and infiltration of excessive moisture on or adjacent to the pavement subgrade surface.

Site grading is generally accomplished early in the construction phase. However as construction proceeds, the subgrade may be disturbed due to utility excavations, construction traffic, desiccation, or rainfall. As a result, the pavement subgrade may not be suitable for pavement construction and corrective action will be required. The subgrade should be carefully evaluated at the time of pavement construction for signs of disturbance or excessive rutting. If disturbance has occurred, pavement subgrade areas should be reworked, moisture conditioned, and properly compacted to the recommendations in this report immediately prior to paving.

4.6.2 Pavement Traffic

Traffic patterns and anticipated loading conditions were not available; however, typical pavement sections with subgrade stabilization alternatives for 20 year design life are provided.

These represent a total of 45,000 18-Kip Equivalent Single Axle Loads (ESAL’s) for Light Duty pavement and 100,000 18-Kip ESAL’s for the Medium Duty pavement. The Light Duty pavement is intended for passenger car and pick up trucks and occasional delivery trucks. The Medium Duty pavement is intended for passenger car, pickup trucks, small delivery trucks, and tractor trailer trucks.

If the pavements are subject to heavier loading and higher traffic counts than the assumed values, this office should be notified and provided with the information so that we may review these pavement sections and make revisions if necessary.

4.6.3 Pavement Sections

Both asphalt and concrete pavement sections are presented in the following table. They are not considered equal. Over the life of the pavement, concrete sections would be expected to require less maintenance. We recommend that the dumpster apron/drive areas be a minimum of 7 inches thick Portland cement concrete.

Reliable ■ Responsive ■ Convenient ■ Innovative 17

Pavement Section Pavement Thickness, Inches

Light Duty 45,000 x 18-kip ESAL’s

Medium Duty 100,000 x 18-kip ESAL’s

Portland Cement Concrete

Concrete 5 6

Compacted Subgrade 6 6

Full Depth Asphaltic Concrete

TxDOT Type D TxDOT Item 340

Asphaltic Concrete 2 2

Type A or B TxDOT Item 340

Asphaltic Concrete 3 4

TxDOT, Item 260 Lime Stabilized Subgrade 6 6

*All materials should meet the TxDOT Standard Specifications for Highway Construction.

The concrete should have a minimum 28-day compressive strength of 3,000 psi in automobile lots and 3,500 psi in truck and dumpster areas. It should contain a minimum of 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.

Pavements will be subject to differential movement due to heave in the site soils. Flat grades should be avoided with positive drainage provided away from the pavement edges. Backfilling of curbs should be accomplished as soon as practical to prevent ponding of water.

Openings in pavement, such as landscape islands, are sources for water infiltration into surrounding pavements. Water collects in the islands and migrates into the surrounding subgrade soils thereby degrading support of the pavement. This is especially applicable for islands with raised concrete curbs, irrigated foliage, and low permeability near-surface soils.

The civil design for the pavements with these conditions should include features to restrict or to collect and discharge excess water from the islands. Examples of features are edge drains connected to the storm water collection system or other suitable outlet and impermeable barriers preventing lateral migration of water such as a cutoff wall installed to a depth below the pavement structure.

5.0 GENERAL COMMENTS

Terracon should be retained to review the final design plans and specifications so comments can be made regarding interpretation and implementation of our geotechnical recommendations in the design and specifications. Terracon also should be retained to provide observation and testing services during grading, excavation, foundation construction and other earth-related construction phases of the project.

Reliable ■ Responsive ■ Convenient ■ Innovative 18

The analysis and recommendations presented in this report are based upon the data obtained from the borings performed at the indicated locations and from other information discussed in this report. This report does not reflect variations that may occur between borings, across the site, or due to the modifying effects of weather. The nature and extent of such variations may not become evident until during or after construction. If variations appear, we should be immediately notified so that further evaluation and supplemental recommendations can be provided.

The scope of services for this project 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.

This report has been prepared for the exclusive use of our client for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranties, either express or implied, are intended or made. Site safety, excavation support, and dewatering requirements are the responsibility of others. In the event that changes in the nature, design, or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless Terracon reviews the changes and either verifies or modifies the conclusions of this report in writing.

APPENDIX A

FIELD EXPLORATION

Exhibit A-44

Field Exploration Description Subsurface conditions were explored by drilling thirty-four borings at the approximate locations indicated on the Boring Location Plan on Exhibit A-1 in Appendix A. The field exploration was performed on May 5 through May 24, 2010. The test locations were established in the field by measuring from available reference features and estimating right angles. The boring locations should be considered accurate only to the degree implied by the methods employed to determine them.

The borings were performed using a truck-mounted drill rig. Continuous-flight augers were used to advance the borings. Samples of the cohesive soils encountered in the borings were obtained using thin-walled tube sampling procedures. The samples were tagged for identification, sealed to reduce moisture loss, and taken to the laboratory for further examination, testing, and classification. The load carrying capacity of the bedrock was tested in place by performing the TxDOT cone penetration test. When borings were drilled on pavements, the surfaces were patched with sacrete.

Field logs of the borings were prepared by the drill crew. The logs included visual classifications of the materials encountered as well as interpretation of the subsurface conditions between samples. The boring logs included with this report represent the engineer’s interpretation of the field logs and include modifications based on laboratory evaluation of the samples. Logs of the borings are presented on Exhibit A-2 through A-43 in Appendix A. General notes to log terms and symbols are presented on Exhibit C-1 in Appendix C.

APPENDIX B

LABORATORY TESTING

Exhibit B-1

Laboratory Testing The Logs of Boring and samples were reviewed by a geotechnical engineer who selected soil samples for testing. Tests were performed by technicians working under the direction of the engineer. A brief description of the tests performed follows.

Liquid and Plastic Limit tests and moisture content measurements were made to aid in classifying the soils in accordance with the Unified Soil Classification System (USCS). The USCS is summarized on Exhibit C-2 in Appendix C. Absorption swell tests were performed on selected samples of the cohesive materials. These tests were used to quantitatively evaluate volume change potential at in-situ moisture levels. Strength of cohesive soils was estimated by field pocket penetrometer tests.

The result of the swell tests are presented in the following table. The results of the other laboratory tests are presented on the Logs of Boring in Appendix A.

Boring No.

Depth (feet)

Liquid Limit

Plasticity Index

Initial Moisture

Final Moisture

Surcharge

(psf) Swell

B-2 8 – 10 54 33 22.4 25.2 1,250 0.3

B-5 8 – 10 59 35 19.5 23.4 1,250 0.1

B-6 8 – 10 43 23 22.2 24.3 1,250 0.1

B-8 8 – 10 54 28 35.8 38.0 1,250 0.2

B-13 8 – 10 84 54 37.7 38.7 1,250 0.2

B-14 4 – 6 62 36 25.0 28.0 625 0.8

B-16 8 – 10 56 35 21.0 23.8 1,250 0

B-20 7 – 9 54 34 16.2 18.2 1,000 0.3

B-21 8 – 10 37 15 18.8 23.5 1,250 0

APPENDIX C

SUPPORTING DOCUMENTS

Exhibit C-1

GENERAL NOTES

DRILLING & SAMPLING SYMBOLS:

SS: Split Spoon – 1-3/8" I.D., 2" O.D., unless otherwise noted HS: Hollow Stem Auger ST: Thin-Walled Tube - 2" O.D., unless otherwise noted PA: Power Auger TC: TxDOT Cone Penetrometer Test HA: Hand Auger DB: Diamond Bit Coring - 4", N, B RB: Rock Bit BS: Bulk Sample or Auger Sample WB: Wash Boring or Mud Rotary

The number of blows required to advance a standard 2-inch O.D. split-spoon sampler (SS) the last 12 inches of the total 18-inch penetration with a 140-pound hammer falling 30 inches is considered the “Standard Penetration” or “N-value”. For TxDOT cone penetrometer (TC) the penetration value is reported as the number of blows required to advance the sampler 12 inches or penetration in inches after 100 blows using a 170-pound hammer falling 24 inches, reported as “blows per foot” or inches per 100 blows, and is not considered equivalent to the “Standard Penetration” or “N-value”.

WATER LEVEL MEASUREMENT SYMBOLS:

WL: Water Level WS: While Sampling N/E: Not Encountered WCI: Wet Cave in WD: While Drilling DCI: Dry Cave in BCR: Before Casing Removal AB: After Boring ACR: After Casing Removal

Water levels indicated on the boring logs are the levels measured in the borings at the times indicated. Groundwater levels at other times and other locations across the site could vary. In pervious soils, the indicated levels may reflect the location of groundwater.

In low permeability soils, the accurate determination of groundwater levels may not be possible with only short-term observations.

DESCRIPTIVE SOIL CLASSIFICATION: Soil classification is based on the Unified Classification System. Coarse Grained Soils have more than 50% of their dry weight retained on a #200 sieve; their principal descriptors are: boulders, cobbles, gravel or sand.

Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are principally described as clays if they are plastic, and silts if they are slightly plastic or non-plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse-grained soils are defined on the basis of their in-place relative density and fine-grained soils on the basis of their consistency.

CONSISTENCY OF FINE-GRAINED SOILS RELATIVE DENSITY OF COARSE-GRAINED SOILS

Unconfined

Compressive Strength, Qu, psf

Standard Penetration or N-value (SS)

Blows/Ft.

Consistency

Standard Penetration or N-value (SS)

Blows/Ft.

TxDOT Cone Penetrometer (TC)

Blows/Ft.

Relative Density

< 500 0 - 1 Very Soft 0 – 3 0-8 Very Loose 500 – 1,000 2 - 4 Soft 4 – 9 8-20 Loose

1,001 – 2,000 4 - 8 Medium Stiff 10 – 29 20-80 Medium Dense 2,001 – 4,000 8 -15 Stiff 30 – 49 80-5”/100 Dense 4,001 – 8,000 15 - 30 Very Stiff > 50 5”/100 to 0”/100 Very Dense

8,000+ > 30 Hard

RELATIVE PROPORTIONS OF SAND AND GRAVEL GRAIN SIZE TERMINOLOGY

Descriptive Term(s) of other Constituents

Percent of Dry Weight

Major Component of Sample

Particle Size

Trace < 15 Boulders Over 12 in. (300mm) With 15 – 29 Cobbles 12 in. to 3 in. (300mm to 75 mm)

Modifier > 30 Gravel 3 in. to #4 sieve (75mm to 4.75 mm)

Sand

Silt or Clay #4 to #200 sieve (4.75mm to 0.075mm)

Passing #200 Sieve (0.075mm)

RELATIVE PROPORTIONS OF FINES PLASTICITY DESCRIPTION

Descriptive Term(s) of other Constituents

Percent of Dry Weight Term

Plasticity Index

Trace < 5 Non-plastic 0 With 5 – 12 Low 1-10

Modifiers > 12 Medium 11-30 High 30+

Exhibit C-2

UNIFIED SOIL CLASSIFICATION SYSTEM

Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests A Soil Classification

Group Symbol Group Name B

Coarse Grained Soils:

More than 50% retained on No. 200 sieve

Gravels:

More than 50% of coarse fraction retained on No. 4 sieve

Clean Gravels:

Less than 5% fines C

Cu ≥ 4 and 1 ≤ Cc ≤ 3 E GW Well-graded gravel F Cu < 4 and/or 1 > Cc > 3 E GP Poorly graded gravel F

Gravels with Fines:

More than 12% fines C

Fines classify as ML or MH GM Silty gravel F,G, H Fines classify as CL or CH GC Clayey gravel F,G,H

Sands:

50% or more of coarse fraction passes No. 4 sieve

Clean Sands:

Less than 5% fines D

Cu ≥ 6 and 1 ≤ Cc ≤ 3 E SW Well-graded sand I Cu < 6 and/or 1 > Cc > 3 E SP Poorly graded sand I

Sands with Fines:

More than 12% fines D

Fines classify as ML or MH SM Silty sand G,H,I Fines Classify as CL or CH SC Clayey sand G,H,I

Fine-Grained Soils:

50% or more passes the No. 200 sieve

Silts and Clays:

Liquid limit less than 50

Inorganic:

PI > 7 and plots on or above “A” line J CL Lean clay K,L,M PI < 4 or plots below “A” line J ML Silt K,L,M

Organic:

Liquid limit - oven dried

< 0.75 OL

Organic clay K,L,M,N

Liquid limit - not dried Organic silt K,L,M,O

Silts and Clays:

Liquid limit 50 or more

Inorganic:

PI plots on or above “A” line CH Fat clay K,L,M PI plots below “A” line MH Elastic Silt K,L,M

Organic:

Liquid limit - oven dried

< 0.75 OH

Organic clay K,L,M,P

Liquid limit - not dried Organic silt K,L,M,Q Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat

A Based on the material passing the 3-in. (75-mm) sieve B If field sample contained cobbles or boulders, or both, add “with cobbles or boulders, or both” to group name.

C Gravels with 5 to 12% fines require dual symbols: GW-GM well-graded gravel with silt, GW-GC well-graded gravel with clay, GP-GM poorly graded gravel with silt, GP-GC poorly graded gravel with clay.

D Sands with 5 to 12% fines require dual symbols: SW-SM well-graded sand with silt, SW-SC well-graded sand with clay, SP-SM poorly graded sand with silt, SP-SC poorly graded sand with clay

E Cu = D60/D10 Cc =

DxD

)(D

F If soil contains ≥ 15% sand, add “with sand” to group name.

G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.

H If fines are organic, add “with organic fines” to group name.

I If soil contains ≥…