2021-624 Georeport_Final.pdf

Geotechnical Engineering Services

Central Power Plant Temple, TX

Arias Project No. 2021-624

Prepared For:

Cox Design Associates, Inc

August 2021

Austin Corpus Christi Eagle Pass Fort Worth San Antonio

13581 Pond Springs Road, Suite 210, Austin, Texas 78729 • Phone: (512) 428-5550 • Fax: (512) 428-5525

August 11, 2021 Arias Project No. 2021-624 VIA Email: bcox@coxdesignassociates.com

Bob Cox

Cox Design Associates, Inc

5121 Bee Caves Road, Suite 203

Austin, TX 78746

RE: Geotechnical Engineering Services

Temple, Texas

Dear Mr. Cox, Arias & Associates, Inc. (Arias) is pleased to submit this Report of Geotechnical Engineering Services for the above referenced project. Our services were performed as outlined in our proposal dated June

3, 2021 and authorized on June 7, 2021.

The purpose of this geotechnical engineering study was to establish foundation and pavement engineering properties of the subsurface soil and groundwater conditions present at the site. The scope of the study is to provide geotechnical engineering criteria for use by design engineers in preparing the foundation and pavement designs.

We sincerely appreciate the opportunity of working with Cox Design Associates, Inc on this project and look forward to our continued services. Please do not hesitate to contact us about this report, or if we can be of further service.

Sincerely, ARIAS GEOPROFESSIONALS, INC.

TBPE Registration No. F-32

Nan Zhang, Ph.D., P.E. Oscar Salazar Project Geotechnical Engineer Graduate Engineer

8/11/2021 mailto:bcox@coxdesignassociates.com

TABLE OF CONTENTS

Page

Arias Geoprofessionals i Arias Job No. 2021-624

INTRODUCTION

AUTHORIZATION AND SCOPE

FIELD EXPLORATION

LABORATORY TESTING

SITE AND SUBSURFACE CONDITIONS

Area Geology

Site Stratigraphic and Engineering Properties

Groundwater

FOUNDATION RECOMMENDATIONS

Potential Vertical Rise

PAVEMENT DESIGN AND CONSTRUCTION

Flexible Pavements

Drainage and Groundwater Control

Pavement Construction

CONSTRUCTION CONSIDERATIONS

Site Drainage

Site Preparation

Earthwork and Foundation Acceptance

ADDITIONAL DESIGN CONSIDERATIONS

GENERAL COMMENTS

Subsurface Variations

Quality Assurance Testing

Standard of Care

TABLE OF CONTENTS

Page

Arias Geoprofessionals ii Arias Job No. 2021-624

APPENDICES

APPENDIX A: FIGURES ............................................................................................................ A

VICINITY MAP ..................................................................................... FIGURE 1

BORING LOCATION PLAN .................................................................. FIGURE 2

SITE AND SAMPLE PHOTOGRAPHS ................................................. FIGURE 3

GEOLOGIC MAP .................................................................................. FIGURE 4

APPENDIX B: BORING LOGS AND KEY TO TERMS ............................................................... B

APPENDIX C: LABORATORY TEST DATA AND PROCEDURES ............................................. C

APPENDIX D: GBA INFORMATION – GEOTECHNICAL REPORT ........................................... D

Tables Page

Table 1: Project Description

Table 2: Existing Conditions during Geotechnical Study

Table 3: Boring Summary Table

Table 4: Subsurface Conditions and Engineering Properties

Table 5: Potential Vertical Rise Estimate with Select Fill Pad Thickness

Table 6: Building Pad Recommendation

Table 7: Allowable Bearing Pressure and Beam Penetration

Table 8: Pavement Design Assumptions

Table 9: Recommended Flexible Pavement Section

Table 10: Pavement Subgrade Preparation Recommendations

Table 11: Flexible Pavement Material Construction

Table 12: Earthwork and General Fill Requirements

Arias Geoprofessionals 1 Arias Job No.2021-624

INTRODUCTION

The project consists of construction of a new boiler power plant located at 1901 Veterans

Memorial Drive, Temple, TX. The footprint area of the new single-story building is approximately

13,700 SF. The column and floor loads are not available at the time of this report. The project is currently in a preliminary phase, and grading operation might be needed within the project site for the construction. The project site location is shown on the Vicinity Map included as Figure 1 in

Appendix A. Project and site conditions are summarized below.

Table 1: Project Description

Project Central Power Plant

Project Location Temple, TX

Proposed Development One (1) one-story 13,700 SF power plant

Anticipated Structural Loads The maximum column load is less than 70 kips

Recommended Foundation Types Slab-on-grade atop select fill pad

Table 2: Existing Conditions during Geotechnical Study

Existing Surface Conditions Low lying grass and asphalt pavement

Predominant Soil Type Fat Clay (CH) and Lean Clay (CL)

Measured Plasticity Indices and Percent

Fines (material passing No. 200 sieve)

PI = 25 to 52 (Avg = 33)

-200 = 66 to 94 (Avg = 88)

Depth to Groundwater

Groundwater was not encountered in the borings during drilling. Groundwater conditions may be different at the time of construction.

AUTHORIZATION AND SCOPE

The geotechnical investigation was authorized and performed as outlined in our proposal dated

June 3, 2021 and authorized on June 7, 2021. The proposal outlines the authorized and agreed upon scope of services.

The purpose of the investigation was to obtain subsurface information adequate for (1) the selection of suitable type of foundation and pavements with respect to cost and performance, compatible with the type of structure proposed, (2) the formulation of design criteria for the type

Arias Geoprofessionals 2 Arias Job No.2021-624 of foundations selected, and (3) the selection of materials and compaction requirements for earth construction.

The scope of the investigation included (1) a field investigation for determining subsurface conditions and obtaining representative samples for classification and testing, (2) a laboratory testing program to aid in the classification of the substrata and to provide parameters for the selection of foundation and pavement criteria, and (3) engineering analyses and evaluations of the results of the field and laboratory data to aid in assessing the geology, foundation and pavement design and construction issues.

FIELD EXPLORATION

A total of four (4) borings were drilled for this project. The boring locations are shown on the

Boring Location Plan, in Figure 2 in Appendix A. Site and Sample Photographs are presented in

Figure 3 in Appendix A. Borings, designated B-1, B-2, B-3 and B-5, were drilled to the depth of

25-ft. The boring information is presented in the following table.

Table 3: Boring Summary Table

Boring Designation

Drilled Depth (ft)

Date Drilled

GPS

Latitude

GPS

Longitude

B-1 25 7/10/2021 31° 4'33.08"N 97°20'36.78"W

B-2 25 7/10/2021 31° 4'31.92"N 97°20'37.02"W

B-3 25 7/10/2021 31° 4'32.38"N 97°20'37.39"W

B-5 25 7/10/2021 31° 4'32.05"N 97°20'38.21"W

Detailed descriptions of subsurface conditions encountered in the borings are presented on the

Boring Logs included in Appendix B. Sample type and interval are included on the individual soil boring logs at the respective sample depth. The key to the terms and symbols used on the logs are also included in Appendix B, following the boring logs.

The borings were sampled using seamless push tubes for cohesive soils (ASTM D1587) and split-barrel sampler while performing the Standard Penetration Test (ASTM D1586) on granular soils.

Boring depths were measured from below the existing surface elevation at the time of drilling. A truck-mounted drill rig using a single flight auger drilling method together with the sampling tools noted was used to obtain samples. After completion of drilling, the boreholes were backfilled with a mixture of auger cuttings and bentonite. Asphalt and base material thickness were measured and reported for borings drilled through pavements. Boreholes drilled through existing pavements were capped with at least 2 feet of sackcrete packaged concrete and surface patched with cold patch asphalt. An Arias representative visually logged each recovered sample and selected representative samples for laboratory testing.

Arias Geoprofessionals 3 Arias Job No.2021-624

SPT N-values for those intervals where the sampler was advanced for a 12-inch penetration after the initial 6-inch seating are shown on the individual boring logs included in Appendix B. The

GPS coordinates (horizontal datum WGS 84) obtained using a hand-held GPS device are shown on the boring logs and should be considered approximate. Drilling notes are also shown on the boring logs.

Soil classifications and borehole logging were conducted during the exploration by one of our field engineering technicians working under the supervision of our Geotechnical Engineer. Final soil classifications, as seen on the boring logs included in Appendix B, were determined in the laboratory based on laboratory and field test results and applicable ASTM procedures.

LABORATORY TESTING

The laboratory testing was performed on representative samples to determine soil water content

(ASTM D2216), Atterberg Limits (ASTM D4318), grain size analyses (ASTM D422), and unconfined compressive strength tests (ASTM D2166). Classification tests are presented on the boring logs at the respective sample depth included in Appendix B, and presented graphically in

Appendix C.

The soil laboratory testing for this project was done in accordance with applicable ASTM procedures with the specifications and definitions for these tests listed in the Appendix C.

SITE AND SUBSURFACE CONDITIONS

Area geology and topography generalized stratigraphy and groundwater conditions are discussed in the following sections. The subsurface and groundwater information are based on conditions encountered at the boring locations to the depths explored at the time of drilling.

Area Geology

According to published geologic mapping1 and nearby experience, the site is mapped as being underlain by surficial clay of Ozan Formation (Ko) underlain by limestone of Austin Chalk (Kau).

The Ozan formation forms broad terraces in the vicinity of Temple and downstream along Austin

Chalk. A Geologic Map is presented on Figure 4 in Appendix A.

1 Garner, L.E. and Young, K.P. (1976), “Environmental Geology of the Austin Area: An Aid to Urban Planning,”

Report of Investigation No. 86, Bureau of Economic Geology, The University of Texas at Austin, Plate VII

(reprinted (1992).

Arias Geoprofessionals 4 Arias Job No.2021-624

Site Stratigraphic and Engineering Properties

Subsurface conditions can be best understood by a thorough review of the boring logs included in Appendix B. Based on the borings drilled for this study subsurface conditions consist of dark brown, gray and tan Fat Clay (CH) and Lean Clay (CL). A summary of subsurface conditions and measured engineering properties are given in the following table.

Table 4: Subsurface Conditions and Engineering Properties

Stratum Depth

(ft) Material Type Index Test Strength Tests

I to

(BTD)

Fat Clay (CH) and

Lean Clay (CL)

PI

25 to 52

(Avg = 33)

-200

66 to 94

(Avg = 88)

PP

4.0 to 4.5+ (Avg = 4.4)

N

57 to 50/2’’

UC

2.3, 3.1

Where: Depth - Depth from existing ground surface at the time of geotechnical study, feet PI - Plasticity Index, % -200 - Percent passing U.S. Standard No. 200 sieve, % N - Standard Penetration Test, N-value, in blows per foot (bpf)

PP - Pocket Penetrometer, tsf UC - Unconfined Compressive Strength, tsf BTD - Boring Termination Depth Avg - Average Value

Soil conditions may vary between the sample boring locations. Transition boundaries or contacts, noted on the boring logs to separate soil types, are approximate. Actual contacts may be gradual and vary at different locations. If conditions encountered during construction indicate more variation than established as a result of this study, we should be contacted to evaluate the significance of the changed conditions relative to our recommendations.

Groundwater

Groundwater was not encountered in the borings at the time of drilling. Groundwater conditions are often based on antecedent rainfall conditions and may be different at other times, and during construction. Perched or transient groundwater could be encountered in excavations during and shortly after periods of rainfall. More likely than not, if encountered, perched or transient groundwater can be handled by sumping and pumping. The quantity of perched water is usually strongly influenced by antecedent rainfall conditions and proximity to drainage features and faults.

Groundwater management is considered to be part of the “means and methods” used by contractor during construction, and hence the selection and implementation of the appropriate method to control and dispose groundwater is the sole responsibility of contractor.

Arias Geoprofessionals 5 Arias Job No.2021-624

FOUNDATION RECOMMENDATIONS

The project will consist of one (1) new single-story building. The footprint size of the structures is approximately 13,700 SF. Based on the subsurface conditions encountered in the borings and our understanding of the proposed development, it is recommended that the new building will be supported on stiffened beams and slab-on-grade foundations atop an engineered building pad, considering that the finish floor elevations (FFE) of the building and structure is anticipated to be within ± 3 feet of the existing ground surface.

The borings drilled across the site and within the building footprints encountered varying depths and thicknesses of fat expansive clay. The fat clay had high plasticity indicative of a high potential for volume change with moisture variation. Accordingly, for shallow foundation support with potential vertical rise on the order of 1 inch, we recommend excavation and removal of at least 6 ft of existing soil and its replacement with a select fill pad.

The following sections present estimates of select fill pad thicknesses based on potential vertical rise (PVR), and recommendations for foundation design.

Potential Vertical Rise

The PVR behavior associated with moisture change of surficial clay soils was estimated using the

Texas Department of Transportation (TxDOT) Potential Vertical Rise (PVR) test method, TEX-

124-E2, and the McDowell3 procedure which are both based on correlations with liquid limit, plasticity index, and in-situ moisture condition.

Based on the subsurface conditions encountered in the borings, we have estimated the Potential

Vertical Rise (PVR) varying approximately from 2.0 to 3.9 inches due to shrink/swell behavior of expansive fat clay.

The estimated PVR is based upon assumed dry soil moisture content; however, soil movements in the field depend on the actual changes in moisture content. Thus, actual soil movements could be less than calculated if less soil moisture variations occur, or the actual movement could exceed the estimated value if more soil moisture variations occur. Such moisture conditions that exceed the limits of the PVR method may be the result of extended droughts, flooding, perched groundwater infiltration, poor surface drainage, excessive irrigation, and/or leaking irrigation or plumbing lines.

2 The State of Texas, Texas Department of Transportation, Materials and Tests Division, Manual of Testing

Procedures, Volume 1, Test Method TEX-124-E, Rev. January 1, 1978.

3 McDowell, C. (1956), “Interrelationships of Loads, Volume Change, and Layer Thickness of Soils to the

Behavior of Engineering Structures,” Highway Research Board, Proc., 35th Annual Meetings, Publ. No. 426, Transportation Research Board, Washington, D.C., 754-772.

Arias Geoprofessionals 6 Arias Job No.2021-624

Compacted, low-expansive select fill materials between the natural soils and the floor slab can reduce the PVR. The reduction in magnitude of PVR is illustrated in the following table considering the undercut and replacement method for constructing the building pad.

Table 5: Potential Vertical Rise Estimate with Select Fill Pad Thickness

Approximate

Undercut Depth

(feet)

Minimum Select Fill

Pad Thickness Below

Slabs (feet)

Approximate

Resulting PVR (inch)

6 6 1.0

The unknown weather factors previously mentioned cannot be determined at the time of the geotechnical study. Therefore, estimated shrink/swell movements are calculated only in consideration of historical climate data related to soil moisture variations. Movements exceeding those estimated should be anticipated and regular maintenance should be provided to address these issues throughout the life of the structure.

Building Pad Preparation

We propose to support the proposed structures on stiffened beam and slab-on-grade foundations atop a select fill pad of 6 feet, to reduce PVR to approximately 1.0 inch. Recommendations for building pad preparation are given in the following table.

Table 6: Building Pad Recommendation

Recommended Foundation Type:

Stiffened beam and slab-on-grade foundation atop a select fill pad

Site Improvement Method:

Excavate and remove existing surficial soils to a depth of

6 feet, or as required to accommodate a 6-feet thick select fill pad below slabs. Moisture condition and compact exposed subgrade. Replace excavated soil with select compacted fill.

Recommended Site Condition

(PVR):

1.0 inch

Recommended Select Fill Pad Thickness Below Slabs

Minimum 6.0 feet

Scarify, Moisture Condition Subgrade:

Scarify at least 8 inches

Moisture condition within -1 to +5% of optimum of TEX-

114-E

Subgrade Preparation Compact to at least 95% of the maximum dry density determined from TEX-114-E

Select Fill Type Crushed Limestone Derivative

Arias Geoprofessionals 7 Arias Job No.2021-624

• Maximum of 25% passing #200 sieve

• Minimum of 15% retained on #4 sieve

• Maximum particle size of 3 inches

• PI = 5 to 20 and/or

Crushed Limestone Base Material

• TxDOT Item 247, Type A, Grade 1-2, 3, or 5

Select Fill Placement Compact to ≥95% maximum dry density at ±2 percentage points of optimum moisture content (TxDOT Tex-113-E)

Capillary Moisture Layer Place minimum of 4 inches of ASTM C33 Grade 57 open-graded stone, or approved equivalent.

Vapor Retarder A 10-mil or thicker vapor retarder is recommended beneath the slab.

Notes:

1. Following stripping operations, excavate and remove surficial fat clay to the required depth to accommodate a select fill pad below the slabs, with a minimum thickness of 6 feet. This thickness must be uniform across the entire slabs. The excavation and removal operation needs to extend at least 5 feet beneath the footprint of the structures and needs to cover the full width of flatwork and the entire footprint of shallow concrete pads used to support equipment sensitive to movements.

2. The exposed subgrade should be scarified to a depth of 8 inches, moisture conditioned and compacted as specified in the Table 6. The pre-fill subgrade should be observed by the Geotechnical Engineer prior to select fill placement. At that time, the Contractor should be prepared to proofroll the prepared subgrade with a heavily-loaded pneumatic tired vehicle. Soft areas and utility backfill may require further undercutting to achieve specified compaction.

3. If moisture migration through the slab is a concern, place a capillary moisture barrier/drainage layer (minimum thickness of four inches) under the entire building footprint atop the compacted select fill. The material should consist of free-draining, clean, crushed stone with sizes ranging mostly between ½ and ¾ inch. A material conforming to ASTM C33, Grade 57, is suggested. The purpose of this layer is to break the transmission of capillary moisture to the underside of the slab.

4. We recommend that at least a 10-mil vapor retarder be used under the slab where the floor will be covered by tile, wood, carpet, impermeable coating, where the floor will be in contact with moisture-sensitive equipment or products, or any case where vapor emission through the slab is concern. The vapor retarder should conform to ASTM E 1745, Class

C or better and shall have a maximum water vapor permeance of 0.044 perms when tested in accordance with ASTM E96. A 10 mil Stego Wrap by Stego Industries LLC or other

Arias Geoprofessionals 8 Arias Job No.2021-624 similar products meeting these requirements would be acceptable. The slab designer should refer to ACI 302 and ACI 360 regarding the use, placement and location of the vapor retarder. The selected vapor retarder should be compatible with subgrade materials and be of sufficient strength to withstand workman construction traffic and placement of reinforcing steel and concrete without puncturing.

Stiffened Beam and Slab-on-Grade

A stiffened beam and slab-on-grade foundation is to allow the structure and foundation to move with soil movements while providing sufficient stiffness to limit differential movements within the superstructure to an acceptable magnitude. Perimeter grade beams should extend at least 2 feet below surrounding finished grade, and interior grade beams should extend at least 12 inches below grade. Additional depth may be required by the project structural engineer based on the results of their analysis. Grade beams should bear in compacted select fill placed as recommended herein or in a moisture conditioned and compacted exposed subgrade. The grade beams should be designed for the allowable bearing capacity provided in the following table below. Grade beams may be thickened and widened at concentrated loads to serve as spread footings.

Table 7: Allowable Bearing Pressure and Beam Penetration

Allowable Bearing Pressure 2,500 psf – Exterior Beam/Footing

1,500 psf – Interior Beam/Footing

Bearing Stratum at Bottom of Grade Beams Compacted Select Fill

Min. Footing Width to Protect Against Localized

Shear Failure

24 inches – Exterior Beam/Footing

12 inches – Interior Beam/Footing

Min. Penetration of Beams Below Final Grade for

Bearing Pressure Requirements

24 inches – Exterior Beams

12 inches – Interior Beams

Notes:

1. Actual beam depth should be determined by structural engineer. Minimum penetration below final grade is necessary to protect against erosion, reduce the potential for water penetration under the foundation, and to stiffen the foundation system.

2. Footing excavations should be observed by the geotechnical engineer prior to reinforcing steel and concrete placement to confirm bearing conditions.

Arias Geoprofessionals 9 Arias Job No.2021-624

Interior Floor Slab

For a continuously reinforced flat slab, the reinforcement requirement is intended to control shrinkage and temperature cracking. The thickness of the slab and the amount of steel reinforcement should be selected by the structural engineer to resist the proposed structural loads. Based on the building pad recommendations for reducing the PVR to 1 inch, a modulus of subgrade reaction (k-value) of 250 pci may be used for design of the floor slab. This value is for a 1-foot square plate and should be corrected for the size and shape of the loaded area accordingly. The slab design and slab support (k-value) will need to be considered for slab loads.

PAVEMENT DESIGN AND CONSTRUCTION

The anticipated pavements will likely consist of parking stalls (light duty) and driveway areas

(heavy duty). Accordingly, we have estimated pavement sections based on light duty and heavy duty uses. The project civil designer should select the appropriate pavement section for the intended use. Pavement thickness design was based on the subsurface conditions encountered in the borings. If different materials are encountered during construction, we should be contacted immediately to review and potentially revise our recommendations accordingly.

A traffic loading (18-kip equivalent single axle load applications) estimate was selected using

Baker (1975)4. The selected traffic loading and subgrade conditions used for design are presented in the following table. If these traffic loadings do not reflect anticipated traffic, Arias should be notified to re-evaluate the recommended pavement sections.

Table 8: Pavement Design Assumptions

Traffic Load for Light Duty Pavement (Parking Stalls)

20,000 equivalent single axle loads (ESALs)

Traffic Load for Heavy Duty Pavement (Entrances and Driveways)

100,000 equivalent single axle loads (ESALs)

Resilient Modulus Subgrade (Mr) 3,000 psi for moisture conditioned, compacted, approved subgrade

Raw Subgrade Modulus of Subgrade Reaction, k (pci)

200 for moisture conditioned, compacted, approved subgrade

4 Baker, R.E., et al, (1975), Handbook of Highway Engineering, Robert F. Baker, Editor, Van Nostrand, New York, Chapter 16.

Arias Geoprofessionals 10 Arias Job No.2021-624

Accumulation of water beneath the pavement surface can cause progressive and rapid deterioration of the pavement section. Similarly, pavement surfaces should be well drained to eliminate ponding with a two-percent minimum slope, as possible.

Flexible Pavements

Using the 1993 AASHTO procedure and an estimated traffic and subgrade conditions presented herein, flexible pavement sections consisting of hot mix asphaltic concrete (HMAC) over crushed limestone base material (CLBM) over lime stabilized subgrade (LSS) were developed for the selected traffic categories and anticipated subgrade condition. Our recommended flexible pavement sections are provided in the following table.

It should be noted that due to the expansive nature of the soils at the site, potential cracks in the flexible pavements due to subgrade swell/shrink are possible and likely to develop with time.

Table 9: Recommended Flexible Pavement Section

Traffic

Category

18-kip

ESAL

LSS

Thickness

(inches)

CLBM

Thickness

(inches)

HMAC

Thickness

(inches)

Light Duty

(Parking stalls) 20,000 4 6 4

Heavy Duty

(Entrances, Driveways) 100,000 7 10 4

Notes:

1. Light duty areas are for parking stalls and passenger vehicles. Heavy duty areas are for entrances, driveways, and where passenger vehicles traffic is concentrated.

2. Material specifications, construction considerations, and pavement section recommendations are presented in the following Pavement Construction section of this report.

Drainage and Groundwater Control

Control of surface drainage and groundwater is important to the performance and life of pavements. Infiltration of water into the pavement subgrade and pavement structure will result in premature loss of serviceability. Adequate drainage provisions should be included in the pavement design. Additionally, the placement of curbs, islands and irrigation systems should be carefully planned in a manner that will not lead to ponding and saturation of pavement base materials that extend into island areas.

Arias Geoprofessionals 11 Arias Job No.2021-624

During the paving life, maintenance to seal surface cracks within the paving should be undertaken to achieve the desired paving life. Perimeter drainage should be controlled to reduce the influx of surface water from areas surrounding the paving. Water penetration into base or subgrade materials, sometimes due to irrigation or surface water infiltration leads to premature paving degradation. Curbs should be used in conjunction with paving to reduce potential for infiltration of moisture into the base course. Curbs should extend the full depth of the base course and should extend at least 3 inches below the base material. The base layer should be tied into the area inlets to drain water that may collect in the base. Fill behind the curb should extend horizontally at least 2 feet and should be compacted in accordance with the General Fill

Placement criteria of Table 10.

Pavement Construction

Recommendations for subgrade preparation in planned pavement areas are presented in Table

10. Recommendations for pavement material construction are provided in Table 11 for flexible pavements.

Table 10: Pavement Subgrade Preparation Recommendations

Stripping Depth 8 inches or as needed to remove roots and organics

Reuse Excavated Soils

Material free of roots, debris and other deleterious material with a maximum particle size of 3 inches and PI<25 may be reused as subbase

Horizontal Undercut Extent Estimated 24 inches beyond the paving limits

Exposed Subgrade Treatment

Proof roll with equipment weighing at least 25 tons and remove and replace weak yielding material with select fill. Scarify to 9-inch depth and recompact soils to ≥95% maximum dry density at -1 to +3 percentage points of optimum moisture content

(TxDOT Tex-114-E if clayey and TxDOT Tex-113-E if gravelly).

Proofroll the prepared subgrade in accordance with Item 216 of the current TxDOT Standard Specifications.

Geotechnical Engineer should observe proofrolling operation.

General Fill Type Material free of roots, debris and other deleterious material with a maximum particle size of 3 inches and a PI less than 25.

Maximum General Fill Loose Lift

Thickness 8 inches

General Fill Placement Criteria

Compact soils to ≥95% maximum dry density at

-1 to +3 percentage points of optimum moisture content

(TxDOT Tex-114-E if clayey and TxDOT Tex-113-E if gravelly)

Arias Geoprofessionals 12 Arias Job No.2021-624

In-Place Density and Moisture Verification Frequency

Test frequency (all materials) 1 test per 5,000 square feet per lift (min. 3 tests per lift)

Table 11: Flexible Pavement Material Construction

Flexible Asphalt Pavement

Flexible Base Material Type TxDOT Item 247, Type A, Grades 1-2, or 5

Maximum Flexible Base Loose Lift

Thickness 8 inches

Flexible Base Placement Criteria Compact to ≥100% maximum dry density at ±2 percentage points of optimum moisture content (TxDOT Tex-113-E)

Hot Mix Asphaltic Concrete (HMAC) TxDOT Standard Specifications Item 340 Type C or D

HMAC Placement Criteria 91% to 95% Theoretical Lab Density

(TEX 207 F)

Project specifications should dictate that the CLBM and HMAC thicknesses specified in the table above be a minimum at any location rather than an average.

All joints should be sealed in accordance with the manufacturer’s recommendations. Stage pavement construction such that construction traffic, including concrete trucks, do not travel on newly placed concrete pavement until the concrete achieves at least 75 percent of the design strength, usually 7 days.

CONSTRUCTION CONSIDERATIONS

Site Drainage

Good positive drainage during and after construction is very important to reduce induced settlement of existing fill that can detrimentally affect the performance of the planned development. Proper attention to surface and subsurface drainage details during the design and construction phase of development can aid in preventing many potential soil shrink-swell or other moisture-related problems during and following the completion of the project.

Site Preparation

Completely strip away any existing foundations, soil, organics, and any deleterious material as needed and dispose outside of the building area. Undercut to the required depth and extent as noted herein. The backfill should be placed and compacted in accordance with the Earthwork

Arias Geoprofessionals 13 Arias Job No.2021-624 and General Fill requirements in the following table. A site representative of the geotechnical engineer should observe grading and earthwork operations.

Table 12: Earthwork and General Fill Requirements

Description Material Compaction

Test Percent

Compaction

Optimum Moisture Content

Testing Requirement

Building Pad Area

Overexcavated (pre-fill) Subgrade

Not Applicable

Remove at least 6.0 feet of surficial high plasticity fat clay

Observe by Geotechnical

Engineer

Exposed Subgrade Tex-114-E 95% -1% to +5%

1 per 5,000 SF;

min. 3 per lift

Select Fill:

(Material Meeting Requirements

Outlined Herein)

Tex-113-E 95% -2% to +2%

1 per 5,000 SF;

min. 3 per lift

Pavement Areas

Exposed Subgrade Not

Applicable Proofroll

Observe by Geotechnical

Engineer

Scarified On-site Soil (Subgrade)

Tex-114-E 95% -1% to +3%

1 per 5,000 SF;

min. 3 tests

General Fill

(Onsite Material, screened, max 3” size, PI<25)

Tex-114-E 95% -1% to +3%

1 per 5,000 SF;

min. 3 per lift

Base Material Tex-113-E 100% -2% to +2%

1 per 10,000

SF;

min. 3 per lift

Hot-mix asphaltic concrete

TEX 207 F

91% to 95% Theoretical Lab Density

Not Applicable

1 per 10,000

SF;

min. 3 per day

Earthwork and Foundation Acceptance

It is recommended that all foundation excavations be extended to final grade and constructed as soon as possible following subgrade preparation. The foundation bearing level should be free of loose soil, ponded water or debris and should be observed prior to concreting by the geotechnical engineer or his representative.

Arias Geoprofessionals 14 Arias Job No.2021-624

Subgrade preparation and fill placement operations should be monitored by the soil engineer or his representative. Any areas not meeting the required compaction should be recompacted and retested until compliance is met.

ADDITIONAL DESIGN CONSIDERATIONS

Flatwork Considerations Outside Building Footprint

Minor differential movements between the planned structure and abutting flatwork should be expected if the flatwork is supported on similar conditions as the building pad. Thus, we recommend that undercut (or partial undercut) and select fill replacement be extended to include adjacent movement-sensitive flatwork such as entry sidewalks. Movement-sensitive exterior flatwork outside the building pad should be undercut a minimum of 2 feet and backfilled with select fill meeting the plasticity, gradation and compaction requirements set forth herein. This undercut depth should extend some distance from the building and may be transitioned to a depth of 1 foot.

Flatwork supported on unimproved, natural site conditions will result in differential foundation movement. We recommend that the flatwork and the building be designed to include details that permit foundation movements without resulting in vertical separations and without distressing either element. Control joints should be included that include steel reinforcing to prevent vertical shear, but to allow bending.

The flatwork and abutting sidewalks or pavements should be designed and constructed to allow for positive drainage to be maintained away from the building foundation. The planned site grading should allow for potential future differential movements, and should never be allowed to reach a level condition or negative slope that promotes drainage toward the foundation. This reversal in drainage can direct moisture into the building envelope and can become a constant nuisance and maintenance issue as well as resulting in foundation movement.

Design Measures to Reduce Changes in Soil Moisture

The following recommended measures can reduce possible moisture fluctuations of the soils under the floor slab. Movements of the foundation soil can be effectively reduced by providing horizontal and/or vertical moisture barriers around the edge of the slab. Typically, moisture barriers consist of concrete flatwork or asphalt or concrete pavement placed adjacent to the edge of the building, a clay cap over poly sheeting, and/or a deepened perimeter grade beam or vertical trench filled with flowable fill.

Although subgrade modification is recommended to reduce potential soil-related foundation movements, the design and construction of a grade-supported foundation should also include the following elements:

1. Roof drainage should be controlled by gutters and carried well away from the structure.

Arias Geoprofessionals 15 Arias Job No.2021-624

2. The ground surface adjacent to the building perimeter should be sloped and maintained a minimum of 5% grade away from the building for 10 feet to result in positive surface flow or drainage away from the building perimeter. In areas adjacent to the building controlled by ADA, concrete flatwork slopes should not be more than 2% within 10 feet of the building.

3. Hose bibs, sprinkler heads, and other external water connections should be placed well away from the foundation perimeter such that surface leakage cannot readily infiltrate into the subsurface or compacted fills placed under the proposed foundations and slabs.

4. No trees or other vegetation over 6 feet in height shall be planted within 15 feet of the structure unless specifically accounted for in the foundation design.

5. Utility bedding should not include gravel near the perimeter of the foundation. Compacted clay or flowable fill trench backfill should be used in lieu of permeable bedding materials between 2 feet inside the building to 4 feet beyond the exterior of the building edge to reduce the potential for water to infiltrate within utility bedding and backfill material.

6. Paved areas around the structure are helpful in maintaining soil moisture equilibrium. It will be very beneficial to have pavement, sidewalks or other flatwork located immediately adjacent to the building to both reduce intrusion of surface water into the more permeable select fill and to reduce soil moisture changes along the exterior portion of the floor due to soil moisture changes from drought, excessive rainfall or irrigation, etc. The use of a clay cap over poly sheeting (horizontal barrier) or impervious geosynthetic liner or concrete

(vertical barrier) is recommended in those areas not covered with asphalt or concrete pavement or flatwork. For this project, the minimum recommended horizontal distance of relatively impervious cover from pavement, flatwork or geosynthetic liner is 8 feet. For a deepened concrete beam or other type of impervious vertical barrier, a minimum depth of

6 feet is recommended.

7. Flower beds and planter boxes should be piped or watertight to prevent water infiltration under the building.

8. Experience indicates that landscape irrigation is a common source of foundation movement problems and pavement distress. Repairing irrigation lines as soon as possible after leakage commences will benefit foundation performance greatly.

9. Foundation pad and pavement subgrade should be protected and covered within 48 hours to reduce changes in the natural moisture regime from rainfall events or excessive drying from heat and wind.

Arias Geoprofessionals 16 Arias Job No.2021-624

GENERAL COMMENTS

This report was prepared as an instrument of service for this project exclusively for the use of Cox

Design Associates, Inc., and the design team. If the development plans change relative to layout, size or anticipated loads or if different subsurface conditions are encountered, we should be informed and retained to ascertain the impact of these changes on our recommendations. We cannot be responsible for the potential impact of these changes if we are not informed.

Subsurface Variations

Soil and groundwater conditions may vary between the sample boring locations. Transition boundaries or contacts, noted on the boring logs to separate soil/rock types, are approximate.

Actual contacts may be gradual and vary at different locations. The contractor should verify that similar conditions exist throughout the proposed area of excavation. If different subsurface conditions or highly variable subsurface conditions are encountered during construction, we should be contacted to evaluate the significance of the changed conditions relative to our recommendations.

Quality Assurance Testing

The long-term success of the project will be affected by the quality of materials used for construction and the adherence of the construction to the project plans and specifications. As

Geotechnical Engineer of Record (GER), we should be engaged by the Owner to provide Quality

Assurance (QA) testing. Our services will be to evaluate the degree to which constructors are achieving the specified conditions they are contractually obligated to achieve and observe that the encountered materials during earthwork for foundation and pavement installation are consistent with those encountered during this study. If Arias is not retained to provide QA testing, we should be immediately contacted if differing subsurface conditions are encountered during construction. Differing materials may require modification to the recommendations that we provided herein.

Arias has an established in-house laboratory that meets the standards of the American Standard

Testing Materials (ASTM) specifications of ASTM E-329 defining requirements for Inspection and

Testing Agencies for soil, concrete, steel and bituminous materials as used in construction. We maintain soils, concrete, asphalt, and aggregate testing equipment to provide the testing needs required by the project specifications. All of our equipment is calibrated by an independent testing agency in accordance with the National Bureau of Standards. In addition, Arias is accredited by the American Association of State Highway & Transportation Officials (AASHTO), the United

States Army Corps of Engineers (USACE) and the Texas Department of Transportation (TxDOT), and also maintains AASHTO Materials Reference Laboratory (AMRL) and Cement and Concrete

Reference Laboratory (CCRL) proficiency sampling, assessments and inspections.

Furthermore, Arias employs a technical staff certified through the following agencies: The

National Institute for Certification in Engineering Technologies (NICET), the American Concrete

Arias Geoprofessionals 17 Arias Job No.2021-624

Institute (ACI), the American Welding Society (AWS), the Precast/Prestressed Concrete Institute

(PCI), the Mine & Safety Health Administration (MSHA), the Texas Asphalt Pavement Association

(TXAPA) and the Texas Board of Professional Engineers (TBPE). Our services are conducted under the guidance and direction of a Professional Engineer (P.E.) licensed to work in the State of Texas, as required by law.

Standard of Care

Subject to the limitations inherent in the agreed scope of services as to the degree of care and amount of time and expenses to be incurred, and subject to any other limitations contained in the agreement for this work, Arias has performed its services consistent with that level of care and skill ordinarily exercised by other professional engineers practicing in the same locale and under similar circumstances at the time the services were performed.

Information about this geotechnical report is provided in the GBA publication included in Appendix

D.

Arias Geoprofessionals Arias Job No.2021-624

APPENDIX A: FIGURES

13581 Pond Springs Road, Suite 210, Austin, Texas 78729 Phone: (512) 428-5550 • Fax: (512) 428-5525

VICINITY MAP

Date: July 21, 2021 Job No.: 2021-624

Figure 1 Drawn By: OS Checked By: NZ

Approved By: NZ Scale: N.T.S.

Map Source: Google Earth Professional

Site

BORING LOCATION PLAN

Date: July 21, 2021 Job No.: 2021-624

Figure 2 Drawn By: OS Checked By: NZ

Approved By: NZ Scale: N.T.S.

Map Source: Google Earth Professional

Photo 1 – Drilling B-5, facing north (7/10/2021)

SITE PHOTOGRAPHS

Date: July 21, 2021 Job No.: 2021-624 Figure 3A

Drawn By: OS Checked By: NZ

Photo 2 – Drilling B-3, facing southeast (7/10/2021)

SITE PHOTOGRAPHS

Figure 3A

Photo 1 – B-1 (0 - 25 ft)

Photo 2 – B-2 (0 - 25 ft)

SAMPLE PHOTOGRAPHS

Figure 3B

Photo 3 – B-3 (0 - 25 ft)

Photo 4 – B-5 (0 - 25 ft)

SAMPLE PHOTOGRAPHS

Figure 3C

GEOLOGIC MAP

Date: July 21, 2021 Job No.: 2021-624

Figure 4 Drawn By: OS Checked By: NZ

Approved By: NZ Scale: N.T.S.

USGS Geologic Map Texas Webviewer: https://txpub.usgs.gov/txgeology/

LEGEND (Youngest to Oldest)

Ko – Ozan Formation

Kau – Austin Chalk

N

Site https://txpub.usgs.gov/txgeology/

Arias Geoprofessionals Arias Job No. 2021-624

APPENDIX B: BORING LOGS AND KEY TO TERMS

"Asphalt: 2.25"; Base: 4.5" LEAN CLAY (CL), very stiff to hard, dark brown to tan, w/calcareous deposits, gravel, sand, ferrous stain

LEAN CLAY (CL), hard, gray, w/limestone fragments

Borehole terminated at 25 feet

3.1

T

T

T

SS

SS

SS

SS

SS

P=4.0

P=4.5+

P=4.5+

N=78/11"

N=50/3"

N=50/5"

N=50/5"

N=50/1"

Coordinates: N31o4'33.08'' W97o20'36.78''

Nomenclature Used on Boring Log

Air rotary: 0 - 25 ft

Backfill: Cuttings/bentonite

Job No.: 2021-624

Sampling Date: 7/10/2021 - 7/10/2021Project: Central Power Plant Temple, TX

Arias Geoprofessionals

Soil Description

Thin-walled tube (T) Split Spoon (SS)

P = Pocket Penetrometer N = SPT Blow Count

PL = Plastic Limit LL = Liquid Limit PI = Plasticity Index

WC = Water Content (%) -200 = % Passing #200 Sieve

DD = Dry Density (pcf) Uc = Compressive Strength (tsf)

Boring Log No. B-1

Location: See Boring Location Plan

Groundwater Data:

During drilling: Not encountered

Field Drilling Data:

Coordinates: Hand-held GPS Unit Logged by: JC Driller: Beyond Engineering and testing Equipment: Truck-mounted drill rig

-6

.G P

J 7/

/2

(B

O R

IN

G

L O

G K

S

LA

U

-1 7, A R

IA

S

S A

-0

1.

G

D T

,L

IB

R A

R Y

-0

K

S L.

G

LB

UcDepth (ft)

Sample Type WC DDLL PI -200P, N

FAT CLAY (CH), hard, dark brown to light brown, w/calcareous deposits, gravel and ferrous stain

LEAN CLAY (CL), hard, ligh tan and light gray, w/calcareous deposits, limestone fragments

LEAN CLAY (CL), very stiff to hard, light gray to gray, w/limestone fragments

Borehole terminated at 25 feet

2.3

T

T

T

T

T

SS

SS

SS

P=4.5+

P=4.5+

P=4.5+

P=4.5+

P=4.5+

N=50/4"

N=57

N=50/3"

Coordinates: N31o4'31.92'' W97o20'37.02''

Nomenclature Used on Boring Log

Air rotary: 0 - 25 ft

Backfill: Cuttings/bentonite

Job No.: 2021-624

Sampling Date: 7/10/2021 - 7/10/2021Project: Central Power Plant Temple, TX

Arias Geoprofessionals

Soil Description

Thin-walled tube (T) Split Spoon (SS)

P = Pocket Penetrometer N = SPT Blow Count

PL = Plastic Limit LL = Liquid Limit PI = Plasticity Index

WC = Water Content (%) -200 = % Passing #200 Sieve

DD = Dry Density (pcf) Uc = Compressive Strength (tsf)

Boring Log No. B-2

Location: See Boring Location Plan

Groundwater Data:

During drilling: Not encountered

Field Drilling Data:

Coordinates: Hand-held GPS Unit Logged by: JC Driller: Beyond Engineering and testing Equipment: Truck-mounted drill rig

-6

.G P

J 7/

/2

(B

O R

IN

G

L O

G K

S

LA

U

-1 7, A R

IA

S

S A

-0

1.

G

D T

,L

IB

R A

R Y

-0

K

S L.

G

LB

UcDepth (ft)

Type WC DDLL PI -200P, N

"Asphalt: 1.0"; Base: 1.5" FAT CLAY (CH), hard, dark brown and tan, w/organics

LEAN CLAY (CL), very stiff to hard, light gray to gray, w/limestone fragments

LEAN CLAY (CL), hard, gray, w/limestone fragments

Borehole terminated at 25 feet

T

T

SS

SS

SS

SS

SS

SS

P=4.5+

P=4.5+

N=50/4"

N=50/3"

N=94/7"

N=50/5"

N=50/5"

N=50/3"

Coordinates: N31o4'32.38'' W97o20'37.39''

Nomenclature Used on Boring Log

Air rotary: 0 - 25 ft

Backfill: Cuttings/bentonite

Job No.: 2021-624

Sampling Date: 7/10/2021 - 7/10/2021Project: Central Power Plant Temple, TX

Arias Geoprofessionals

Soil Description

Thin-walled tube (T) Split Spoon (SS)

P = Pocket Penetrometer N = SPT Blow Count

PL = Plastic Limit LL = Liquid Limit PI = Plasticity Index

WC = Water Content (%) -200 = % Passing #200 Sieve

Boring Log No. B-3

Location: See Boring Location Plan

Groundwater Data:

During drilling: Not encountered

Field Drilling Data:

Coordinates: Hand-held GPS Unit Logged by: JC Driller: Beyond Engineering and testing Equipment: Truck-mounted drill rig

-6

.G P

J 7/

/2

(B

O R

IN

G

L O

G K

S

LA

U

-1 7, A R

IA

S

S A

-0

1.

G

D T

,L

IB

R A

R Y

-0

K

S L.

G

LB

Depth (ft)

Type WC LL PI -200P, N

SANDY LEAN CLAY (CL), hard, dark brown and tan, w/calcareous deposits, gravel

LEAN CLAY (CL), very stiff to hard, light tan to light gray, w/limestone fragments

LEAN CLAY (CL), hard, gray, w/limestone fragments

Borehole terminated at 25 feet

T

T

T

T

SS

SS

SS

SS

SS

P=4.5+

P=4.5+

P=4.5+

P=4.5+

N=92/10"

N=50/5"

N=50/2"

N=50/3"

N=50/2"

Coordinates: N31o4'32.05'' W97o20'38.21''

Nomenclature Used on Boring Log

Air rotary: 0 - 25 ft

Backfill: Cuttings/bentonite

Job No.: 2021-624

Sampling Date: 7/10/2021 - 7/10/2021Project: Central Power Plant Temple, TX

Arias Geoprofessionals

Soil Description

Thin-walled tube (T) Split Spoon (SS)

P = Pocket Penetrometer N = SPT Blow Count

PL = Plastic Limit LL = Liquid Limit PI = Plasticity Index

WC = Water Content (%) -200 = % Passing #200 Sieve

Boring Log No. B-5

Location: See Boring Location Plan

Groundwater Data:

During drilling: Not encountered

Field Drilling Data:

Coordinates: Hand-held GPS Unit Logged by: JC Driller: Beyond Engineering and testing Equipment: Truck-mounted drill rig

-6

.G P

J 7/

/2

(B

O R

IN

G

L O

G K

S

LA

U

-1 7, A R

IA

S

S A

-0

1.

G

D T

,L

IB

R A

R Y

-0

K

S L.

G

LB

Depth (ft)

Type WC LL PI -200P, N

GW

GP

GM

GC

SW

SP

SM

SC

ML

CL

MH

CH

Massive or Weakly Bedded Limestones

M o re t h a n h a lf o f m a te ri a l S

M A

L L E

R th a n N o S ie v e s iz e

F O

R M

A T

IO

N

A L

M A

T E

R

IA

L S

GROUP

SYMBOLS

KEY TO TERMS AND SYMBOLS USED ON BORING LOGS

C O

A R

S E

-G R

A

IN

E D

S O

IL

S

G R

A V

E L

S S

A N

D S

M o re t h a n H a lf o f C o a rs e f ra c ti o n i s

L A

R G

E R t h a n N o S ie v e s iz e

M o re t h a n h a lf o f m a te ri a l L A

R G

E R t h a n N o S ie v e s iz e

MAJOR DIVISIONS

Silty Gravels, Gravel-Sand-Silt Mixtures

Poorly-Graded Gravels, Gravel-Sand Mixtures, Little or no Fines

Well-Graded Gravels, Gravel-Sand Mixtures, Little or no Fines

DESCRIPTIONS

Clayey Sands, Sand-Clay Mixtures

Silty Sands, Sand-Silt Mixtures

Poorly-Graded Sands, Gravelly Sands, Little or no Fines

Well-Graded Sands, Gravelly Sands, Little or no Fines C le a n G ra v e ls

(l it tl e o r n o F in e s

G ra v e ls w h

F in

(A p p re c ia b le m o u n t o f F in e s

C le a n S a n d

(l tl e o r n o F in e s

S a n d s w it h F in

(A p p re c ia b le m o u n t o f F in e s

L iq u id

L im it l e th n

L iq u id

L im g re a te r th a n

LIMESTONE

MARLSTONE

SANDSTONE

Clayey Gravels, Gravel-Sand-Clay Mixtures

Massive Sandstones, Sandstones with Gravel Clasts

Inorganic Clays of High Plasticity, Fat Clays

Inorganic Silts, Micaceous or Diatomaceous Fine Sand or Silty Soils, Elastic Silts

Inorganic Clays of Low to Medium Plasticity, Gravelly Clays, Sandy Clays, Silty Clays, Lean Clays

Inorganic Silts & Very Fine Sands, Rock Flour, Silty or Clayey Fine Sands or Clayey Silts with Slight

Plasticity

Indurated Argillaceous Limestones

Indicates Final Observed Groundwater Level

Indicates Initial Observed Groundwater Location

Cretaceous Clay Deposits

Massive or Poorly Bedded Chalk Deposits

Mudstone or Massive Claystones

F

IN

E -G

R A

IN

E

D S

O

IL

S

M o re t h a n h a lf o f C o a rs e f ra c ti o n i

S M

A L L E

R t h a n N o S ie v e s iz e

S

IL

T

C

A Y

S

S

IL

T

C

A Y

S

GROUNDWATER

MARINE CLAYS

CHALK

CLAYSTONE

Very Dense

30 - 50

Over 50

10 - 30

Consistency and Strength of Cohesive Soils

Number of Blows per ft., N

Unconfined

Compressive

Strength, qᵤ (tsf)

Consistency

Density of Granular Soils

Relative Density

Very Loose

Number of

Blows per ft., N

0 - 4

4 - 10 Loose

Medium

Dense

Below 2

2 - 4 Soft

Very Soft

Stiff

Less than 0.25

0.25 - 0.5

0.5 - 1.0

1.0 - 2.0

Medium (Firm)

Very Stiff

Hard

4 - 8

8 - 15

15 - 30

Over 30 Over 4.0

2.0 - 4.0

Arias Geoprofessionals

Group

Symbol

GW

(Less than 5% fines C

Cu < 4 and/or GP

[Cc < 1 or Cc > 3] D

Gravels with Fines GM

(More than 12% fines C

GC

Sands Clean Sands SW

(Less than 5% fines H

) Cu < 6 and/or SP

[Cc < 1 or Cc > 3] D

Sands with Fines SM

(More than 12% fines H

SC

Silts and Clays…