4-TRE Double Track Sealed Geotechnical Report.pdf

Geotechnical Evaluation Report

Trinity Metro - TRE Double Track Handley-Ederville Road to Precinct Line Road Fort Worth, Texas

Prepared for

TranSystems

Professional Certification:

I hereby certify that this plan, specification, or report was prepared by me or under my direct supervision and that I am a duly licensed Professional Engineer under the laws of the State of Texas.

Morgan Race, PhD, PE Senior Engineer License Number: 139402

January 23, 2025

Project B2405130

Braun Intertec Corporation TBPELS Firm Registration No. 12228

AA/EOE

Braun Intertec Corporation 1160 Mustang Drive, Ste. 300 Dallas, TX 75261

Phone: 817.786.5999 Web: braunintertec.com

Send USPS mail to: P.O. Box 1685 Grapevine, TX 76099

January 23, 2025 Project B2405130

Michael R. Hobbs, PE TranSystems 500 W Seventh St, Ste 1100 Fort Worth, TX 76102

Re: Geotechnical Evaluation Report Trinity Metro – TRE Double Track Handley-Ederville Rd to Precinct Line Rd Fort Worth, Texas

Dear Mr. Hobbs:

We are pleased to present this revised geotechnical evaluation report for the planned construction of the Trinity Metro – TRE Double Track project located in Fort Worth, Texas. The purpose of our evaluation was to characterize subsurface conditions for the proposed track expansion. The attached report contains our findings, analyses, and recommendations for design and construction.

Thank you for making Braun Intertec your geotechnical consultant for this project. If you have questions about this report, or if there are other services that we can provide in support of our work to date, please contact Morgan Race at 214.679.9951 (mrace@braunintertec.com) or Scott Mackiewicz at 816.274.1499 (smackiewicz@braunintertec.com)

Sincerely, BRAUN INTERTEC CORPORATION

TBPELS Firm Registration No. 12228

Jeffrey Joseph, GIT Morgan Race, PhD, PE Staff Geologist Senior Engineer

Scott M. Mackiewicz, PhD, PE, BC.GE Randy Deatherage, PE Vice President, Principal Engineer Senior Engineer

Table of Contents

Description Page

A. Introduction

A.1. Project Description A.2. Purpose, Scope of Services and Scope Limitations

A.2.a. Purpose A.2.b. Scope Limitations

A.3. Background Information and Reference Documents A.4. Site Conditions and History

A.4.a. Site Conditions A.4.b. Historical Conditions

B. Results B.1. Geologic Overview

B.1.a. Texas Geologic Survey B.1.b. Soil Survey

B.2. Exploration Results B.2.a. Borings

B.3. Laboratory Results B.3.a. Consolidation Test B.3.b. Direct Shear Test

C. Recommendations C.1. General

C.1.a. Track C.1.a.1. Embankment C.1.a.2. Embankment Settlement C.1.a.3. Drainage

C.1.b. Retaining Walls C.1.c. Bridge Foundations C.1.d. Box Culverts C.1.e. Limitations

C.2. Subgrade Preparation and Site Grading C.2.a. Site Stripping and Grubbing C.2.b. Undercutting and Subgrade Stabilization C.2.c. Site Drainage C.2.d. Subgrade Preparation C.2.e. Existing Track Drainage - Trench Drains C.2.f. Excavation Backfill and Embankment Fill C.2.g. Placement and Compaction of Fill C.2.h. Benching C.2.i. Permanent Slopes C.2.j. Site Utilities C.2.k. Temporary Excavations

C.2.k.1. Soil Classification C.2.k.2. Excavation Dewatering C.2.k.3. Excavation Backfill

C.2.l. Climatic Conditions C.3. Embankments

Table of Contents (continued)

C.3.a. Embankment Settlement C.3.b. Steepened Slopes

C.4. Retaining Walls C.4.a. Wall Locations, Heights, and Type C.4.b. Design Criteria C.4.c. Design Loads C.4.d. Drilled Shaft and Trench Retaining Wall Geotechnical Design Parameters C.4.e. Evaluation Assumptions C.4.f. Lateral Earth Pressures from Backfill C.4.g. Drilled Shaft Lateral Resistance C.4.h. Retaining Wall Drainage C.4.i. Settlement and Horizontal Movement

C.4.i.1. Settlement C.4.i.2. Horizontal Movement

C.4.j. Track and Adjacent Structure Monitoring C.4.k. Construction Considerations

C.5. Box Culverts C.5.a. General

C.5.a.1. Culvert A C.5.b. Foundation Bearing Capacity C.5.c. Settlement C.5.d. Lateral Earth Pressures and Sliding Coefficients C.5.e. Construction Considerations

C.6. Track Substructure C.6.a. Railway Alignment C.6.b. Track Subgrade C.6.c. Ballast and Subballast Materials

C.7. Bridge Foundations C.7.a. Bridge Information C.7.b. Pile Foundations C.7.c. Pile Foundation Axial Resistance C.7.d. Lateral Earth Pressures for Abutments and Wing Walls C.7.e. Design and Construction Considerations

C.7.e.1. General C.7.e.2. Driven Piles C.7.e.3. Pre-drilled, Set-in-place Piles

C.7.f. Drilled Shaft Foundations C.7.f.1. Drilled Shaft Axial Resistance C.7.f.2. Drilled Shaft Design and Construction Considerations C.7.f.3. Design Considerations C.7.f.4. Construction Considerations

C.7.g. Lateral Geotechnical Resistance C.7.h. Spacing and Group Effects C.7.i. Seismic Site Classification

Table of Contents (continued)

C.7.j. Corrosion Potential D. Procedures

D.1. Borings D.2. Exploration Logs

D.2.a. Log of Boring Sheets D.3. Material Classification and Testing

D.3.a. Visual and Manual Classification D.3.b. Laboratory Testing

D.4. Groundwater Measurements E. Qualifications

E.1. Variations in Subsurface Conditions E.1.a. Material Strata E.1.b. Groundwater Levels

E.2. Continuity of Professional Responsibility E.2.a. Plan Review E.2.b. Construction Observations and Testing

E.3. Use of Report E.4. Standard of Care

Appendix A Figure A-1: Soil Boring Location Sketch and Profile (6 pages) Table A-1: Retaining Wall Geotechnical Design Parameters Log of Boring Sheets (48 pages) Log of Previous Borings (6 pages) Sieve Analysis Test Results (19 pages) Consolidation Testing Results (19 pages) Direct Shear Testing Results (2 pages) Corrosion Test Results (2 pages) Descriptive Terminology of Soil (1 page) Descriptive Terminology of Rock (1 page)

Appendix B Global Stability Results

A. Introduction

A.1. Project Description

The Trinity Metro – TRE Double Track project includes adding a second trinity railway express (TRE) mainline in Fort Worth, Texas. This report covers the alignment from Handley-Ederville Road to Precinct Line Road, Sta. 0+00 to 149+56. Table 1 provides a summary of south project contained herein, design information, and our assumptions.

Table 1. Summary of Proposed Project Information

Aspect Description

TRE Double Track Project*

Location: Sta. 0+00 to 149+56 South of the existing mainline track Between Handley-Ederville Road to Precinct Line Road

Track Structure:

Minimum 15 ft track centers (15 to 32 feet)

136# CWR with 7”x 9”x 8’6” Concrete Ties at 24” c-c 12 inches ballast (minimum) 12 inches subballast (minimum) Speed: 79 mph passenger/60 mph freight

Grade Changes: Cuts < 10ft, Fills < 19ft Planned cut and fill slopes: 3H:1V, except where noted below as a 2H:1V slope

Sta. 26+00 to 31+50 Sta. 60+75 to 78+50 Sta. 71+44 to 78+50 (ditch) Sta. 122+98 to 126+00 Sta. 132+50 to 133+00 Sta. 145+75 to 150+25

New Bridges:

Bridge MP619.03, Sta. 35+76, over 121/820 Creek (Existing Timber

Bridge to be replaced) Bridge MP620.40, Sta. 113+18, over Calloway Branch (Existing Concrete

Bridge to remain) Bridge MP620.60, Sta. 118+58, over Walker Branch (Existing Concrete

Bridge to remain) Bridge MP621.06, Sta. 143+18, over Lorean Branch (Existing Concrete

Bridge to be replaced) New/Extend Culverts

MP618.76, Sta. 21+51, New 8ft x 5ft Box Culvert (Existing Bridge on Mainline to remain)

Sta. 42+47, Extend 18” SSP Culvert Sta. 68.77, Extend 2-66” RCP Culvert Sta. 81+26, Extend 48” RCP Culvert Sta. 122+42, New 18” SSP Culvert under Precinct Line Road Sta. 132+77, Extend 36” CMP Culvert

Project B2405130 Trinity Metro – TRE Double Track January 23, 2025

Aspect Description Retaining Wall Structures (Drilled Shaft and Trench Type Walls)

RW-01 – Sta. 13+00 to 17+00, Max. Exposed Height = 2 feet RW-02 – Sta. 19+00 to 20+49, Max. Exposed Height = 13 feet RW-02A – Sta. 20+72 to 20+22, Max. Exposed Height = 16 feet RW-03 – Sta. 20+59 to 22+50, Max. Exposed Height = 18 feet RW-04 –Omitted RW-05 – Sta. 35+00 to 36+47, Max. Exposed Height = 10 feet RW-06 – Sta. 37+01.10 to 45+75, Max. Exposed Height = 13 feet RWTL –Sta. 53+97 to 54+72, Max. Exposed Height = 3 feet RW-08 – Sta. 106+00 to 113+38, Max. Exposed Height = 12 feet RW-09 – Sta. 114+90 to 118+99, Max. Exposed Height = 12 feet RW-10 –Sta. 120+12 to 121+50, Max. Exposed. Height = 16 feet RW-11A –Sta. 126+00 to 132+00, Max. Exposed. Height = 3 feet RW-11B –Sta. 133+00 to 138+50, Max. Exposed. Height = 6 feet

*From the 90% plans, Trinity Metro, Texas Railway Express - Double Tracking, dated December 2024

A.2. Purpose, Scope of Services and Scope Limitations

A.2.a. Purpose The purpose of our evaluation was to characterize subsurface conditions for the proposed TRE Double Tracking. This information will serve as a basis for site development, track substructure design, bridges and station foundation recommendations, and constructability recommendations for the proposed double track.

A.2.b. Scope Limitations The scope of our evaluation, as well our findings and recommendations, were based on the project information obtained during our exploration and fieldwork and design information provided by TranSystems. If pertinent details of the project have changed or otherwise differ from our descriptions and assumptions, we must be notified and engaged to review the changes and modify our recommendations, if needed.

A.3. Background Information and Reference Documents

We reviewed the following provided information as part of this project:

90% Submittal, Plans, Profile, and Cross Sections, Trinity Metro, Trinity Railway Express – Double Tracking, Handley-Ederville Road to Precinct Line Road, dated December 2024.

Trinity Metro – TRE Double Track

In addition to the provided sources, we have used several publicly available sources of information including the following:

Web Soil Survey, http://websoilsurvey.nrcs.usda.gov/. United States Department of Agriculture (USDA) and Natural Resources Conservation Service (NRCS) used to aid in our evaluation of the subsurface soil conditions.

Google Earth© aerial imagery, used to aid in evaluating site access and historic construction.

USGS Geologic Atlas of Texas, <https://webapps.usgs.gov/txgeology/>, accessed September 2024.

A.4. Site Conditions and History

A.4.a. Site Conditions The area proposed for the mainline extension traverses residential and commercial areas in Fort Worth, Texas. The western extent of the project is Milepost 0618.40. The eastern extent of the project is milepost 0621.17. The existing main line track includes two road crossings at Handley-Ederville Road and Precent Line Road as well as a segment underneath the East Loop 820 highway overpass.

Both the previous Richland Hills Station and the existing Trinity Lakes Station are situated along the extent of the proposed extension.

Site observations of the existing site conditions were made during the performance of our fieldwork in June and July 2024. At the time of our fieldwork in 2024, most of the existing track embankment along the proposed extension alignment was heavily vegetated with thick brush and some large trees that limited the extent of our observations. The existing track embankments range in height from less than 5 to 10 feet tall with side slopes ranging from about 3H:1V to approximately 1H:1V. The nearby ditches and toes of slope are heavily vegetated.

Five bridges currently exist along the extent of the proposed extension. One bridge is located over an existing drainage way immediately east of station 20+00. Near (MP 619.03), another timber bridge is located where the existing mainline crosses TRIB WF-9, a tributary stream of the Trinity River. Three final bridges are located where the mainline crosses the Calloway Branch, Walker Branch, and Lorean Branch.

Figure 1 below displays the existing bridges within the extent of the project with progression from west to east.

Trinity Metro – TRE Double Track

A.4.a.1.

Figure 1. Photographs of Google Earth images of existing bridges over a) drainage creek b) Tributary WF-9 creek c) Calloway Branch and Walker Branch creeks and d) Lorean Branch.

A.4.b. Historical Conditions

In our review of historical photographs, we noted a possible slope repair located east of the Lorean Branch bridge (MP 621.06), extending from station 145+75 through 148+15 on the northern slope. Figure 2 illustrates the area. The previous repair appears to have been performed between December of 2009 and June 2011. It is unclear what conditions resulted in the need to place riprap although slope instability is considered likely. It appears that there has been no noticeable slope movement since placing riprap on the slope.

A B

D C Walker Branch

Calloway Branch

Trinity Metro – TRE Double Track

Figure 2. Historical photographs of possible slope failure repair along the proposed alignment east of the Mesquite Creek bridge from Google Earth © dated a) December 2009 and b) June 2011.

According to the historical imagery, it appears that segments of the mainline track within the project limits were replaced between November 2018 and November 2020. Figure 3 displays one area of track replacement near Station 93+45.

Figure 3. Historical photographs track replacement along the proposed alignment beginning near Sta.

93+45. Google Earth images © dated a) October 2019 and b) December 2019.

According to available historical imagery the Richland Hills Station was in use sometime prior February 2001. Construction of the platform at the new Trinity Lakes Station began sometime between October 2021 and January 2023. By February 2024, the Trinity Lakes Station was mostly completed the Richland Hills Station was closed.

B A Slope Repair Slope Failure

B A

Trinity Metro – TRE Double Track

B. Results

B.1. Geologic Overview

B.1.a. Texas Geologic Survey Based on the observed subsurface conditions and the Geologic Atlas of Texas, Dallas Sheet (published by the Bureau of Economic Geology), the site is situated within the Fluviatile Terrace Deposits and Alluvium associated with the West Fork Trinity River. Terrace deposits and alluvium generally consist of gravel, sand, silt, and clay of different ages deposited by rivers and streams. These deposits are underlain by the Grayson Marl and Main Street Limestone, undivided. The Grayson Marl is comprised of calcareous clay and marl roughly 60 to 100 feet thick. The Main Street Limestone is generally comprised of chalky, medium-grained limestone 25 to 30 feet thick with some thick beds of calcareous shale.

Please note that the geologic mapping was originally performed using aerial photography. Local variations and anomalies do occur, and previous site work may have altered the expected subsurface profile in some areas of the project limits.

B.1.b. Soil Survey The Web Soil Survey developed by the United States Department of Agriculture (USDA) and Natural Resources Conservation Service (NRCS) was reviewed for the area near the project. A general description of the soil property identified along the length of this project, as reported by the NRCS, is summarized in Table 2.

Table 2. Properties of Soil Series

Series Symbol Soil Series Description

Liquid Limit

Plasticity Index USCS

ArA Arents, Loamy Slope alluvium over residuum 30 to 44 11 to 23 CL,SC

BfB Bastsil fine sandy loam complex Loamy alluvium 17 to 46 2 to 25 SC-SM, CL, SC, SM

BfC Bastsil-Urban land complex Loamy alluvium 17 to 46 2 to 25 SC-SM, CL,SM,CL, SC

Ps Pulexas fine sandy loam Loamy alluvium 0 to 30 NP to 10 SM, ML, SC, CL, CL-ML

SfC Silawa fine sandy loam Loamy alluvium 16 to 40 NP to 7

CL-ML, ML,

SC-SM, SM,

CL, SC, GM,

SP-SM

Trinity Metro – TRE Double Track

Series Symbol Soil Series Description

Liquid Limit

Plasticity Index USCS

Wf Whitesboro loam Loamy alluvium 60 to 91 6 to 27 CL, CL-ML, WuA Wilson-Urban land complex

Clayey alluvium of quaternary age derived from mixed sources 38 to 65 20 to 48 CL, CH

B.2. Exploration Results

B.2.a. Borings We performed 32 borings to provide information for our geotechnical evaluation. All the borings, except RW-03, were drilled on the south side of the existing main line track on right-of-way, along the proposed double track alignment. RW-03 was drilled on the south side of the existing track, but on private property at 2704 Handley-Ederville Road in Fort Worth, Texas. Boring locations are shown in Figure A-1 in the Appendix A.

During our fieldwork, we used a Trimble Catalyst GPS device, having vertical accuracy of less than 1/2 foot, to determine the coordinates and ground surface elevations of our as-drilled boring locations.

Borings were left staked after the completion of the fieldwork. Locations and elevations of the borings should be considered accurate only to the degree implied by the methods used to obtain them.

Table 3 provides a summary of the borings, in the general order we encountered the strata, as well as laboratory test results and groundwater observations.

B.3. Laboratory Results

We performed laboratory tests on selected representative samples to aid in soil classification and to evaluate physical properties of the soils influencing project design and construction. Laboratory tests were performed in general accordance with applicable American Society of Testing Material (ASTM) standards. This information is also presented on the Log of Boring sheets in the Appendix A.

B.3.a. Consolidation Test We performed three consolidation tests per ASTM D2435 on representative samples from borings B-01, B-05, and TK-02. The results are summarized in Table 4 and presented in the Appendix A.

Trinity Metro – TRE Double Track

B.3.b. Direct Shear Test We performed two direct shear tests per ASTM D3080 on representative samples from borings RW-06 and RW-14. The results are summarized in Table 4 and presented in the Appendix A.

Table 3. Subsurface Profile Summary*

Strata

Soil Type -

ASTM

Classification Field and

Laboratory Results Commentary and Details

Topsoil Fill N/A N/A

Encountered to depths of 2 inches to 8 inches.

Not observed in borings CW-11, CW-12, RW-02, RW-03, RW-06, RW-07, RW-14, TK-01, TK-04, or TK- 05.

Fill CL, CH, SP, SC

N = 5 BPF to 50 blows for 4”(REF)

W = 6 to 15% qp= 1.4 to >4.5 tsf

LL=25, PI=10

Encountered in borings B-03, B-06, CW-11, CW-12, RW-03, RW-04, RW-06, RW-08, and RW-14.

Generally moist with various hues and shades of brown. Olive gray at 6.5 feet in boring CW-11

Various amounts of Clay, Silt, and Gravel. Includes root fragments

Native

CL, CH, CL-ML

N = 3 to 53 BPF W = 5 to 30% qp=0.75 to >4.5 tsf LL = 17 to 57 PI = 5 to 39

DD= 116 to 121 pcf Qu=2.24 to 10.54 tsf

Encountered in all borings except B-03, B-06, RW- 04, RW-05, RW-15, RW/CW-16, TK-03, and TK-05.

Generally moist to wet, brown and gray.

Generally soft to hard in consistency.

Contains Sand, Silt and Gravel in varying amounts.

Occasional Sand layers, Limestone layers, and

Gravel lenses.

SC

N = 0 to 45 BPF W = 1 to 19% LL = 23 to 47 PI = 11 to 31

Encountered in all borings except B-01, B-04, RW-

02, RW-03, RW-08, RW-14, TK-01, TK-03.

Generally dry to moist, various hues and shades of brown.

Generally very loose to dense in consistency.

Occasionally contains Gravel, and Clayey Sand layers.

SP, SP-SM,

SP-SC, SM

N = 2 BPF to 50/5.5”

W = 1 to 19%

Encountered in all borings except B-02, B-03, B-06, B-07, RW/CW-09, RW-15, TK-01, TK-02, TK-03.

Generally dry to wet, Light brown, brown, and reddish brown.

Generally very loose to medium dense in consistency.

Commonly contains Gravel. Occasionally contains clay layers.

Rock Shale N = 41 to 50/5.5”

W = 11 to 19%

Encountered in all borings except RW-01 to RW-07, CW-10, CW-11, CW-15, RW/CW-16, CW-17, CW-19, TK-01 to TK-05.

Trinity Metro – TRE Double Track

Strata

Soil Type -

ASTM

Classification Field and

Laboratory Results Commentary and Details

Occurs as layers within Limestone in borings B-07 and CW-12.

Encountered at depths generally ranging from 28 to 58 feet.

Generally gray to dark gray and grayish brown to dark grayish brown, unweathered to highly weathered.

Generally soft to moderately hard.

Limestone N = 50/4” to 50/1” W = 9 to 38%

Encountered in all borings except RW-01 to RW-07, RW/CW-09, RW-14, CW-10, CW-11, TK-01 to TK-03, and TK-05.

Encountered at depths ranging from 9 to 38 feet below the existing ground surface.

Generally Tan to Gray, highly weathered to unweathered.

Generally moderately hard.

Commonly contains shale layers.

Groundwater --- ---

Encountered in all borings except RW-01, RW-02, RW-04, RW-05, RW-07, RW-08, TK-01, and TK-03 to

TK-05.

Encountered at depths of 8 to 33 feet during drilling.

Piezometers and/or monitoring wells would be required to confirm groundwater conditions.

Seasonal fluctuations should be anticipated.

*Abbreviations defined in the attached Descriptive Terminology sheets.

Trinity Metro – TRE Double Track

Table 4. Laboratory Strength/Compression Test Results

Location

Sample Depth

(ft) Classification

Dry Density (ɣ, pcf)

Effective Friction Angle

(φ, deg)

Effective Cohesion, (c’, psf)

Compression Index (Cc/Cr)

Estimated Pre-Consolidation

Pressure (Pc, psf)

B-01 2-4 Silty Lean Clay

(LL=22, PI=7) 117 --- --- 0.05/0.01 1,022

B-05 6-8 Lean Clay

(LL=41, PI=27) 116 --- --- 0.14/0.01 4,489

TK-02 8-10 Lean Clay

(LL=41, PI=27) 107 --- --- 0.13/0.03 3,420

RW-06* 8-10 Lean Clay

(LL=21, PI=4) 110 38 0 --- ---

RW-14 8-10 Lean Clay

(LL=25, PI=11) 118 36 0 --- ---

*Two of three samples were remolded

C. Recommendations

C.1. General

Based on our findings, it is our professional opinion that the double track extension can be constructed using conventional methods. We have summarized the potential geotechnical design and construction concerns in the following sections.

C.1.a. Track

C.1.a.1. Embankment It should be noted that the construction of the embankment will be adjacent to the existing live track within the ROW limits. Due to the limited access and confined areas of work, placement of fill materials may require that haul trucks use the constructed embankment to access the site. If used, hauling on the constructed embankment should be limited, when possible, and the traffic pattern should be adjusted to reduce potential rutting, disturbance, and reworking of the in-place materials.

Trinity Metro – TRE Double Track

C.1.a.2. Embankment Settlement Settlement of the existing and new embankments will occur during and after fill placement. Below the proposed new track, we anticipate about 2 to 3 inches of settlement due to compression of the foundation soils. In addition, we anticipate up to 1/2 to 1 inch of settlement will occur below the existing mainline tracks during and after the placement of new fill is complete. We anticipate that the existing track geometry can be maintained using periodic monitoring and surfacing during construction.

C.1.a.3. Drainage We did not identify any significant areas of mud pumping and fouled ballast within the proposed project area during our review of aerial photographs. If mud pumping or ballast pockets are observed during construction, we recommend that test pits be excavated adjacent and below the existing tracks in these areas during construction to better characterize the existing track subgrade conditions and ballast pocket, if present. If ballast pockets are present, we recommend that sand or ballast filled trench drains be installed within the identified problem areas to remove trapped water. The trench drains should extend under the existing/proposed track to remove any trapped water in potential ballast pockets and be graded to drain into the planned ditches.

C.1.b. Retaining Walls Based on the plans dated December 2024 and discussions with the project team, we understand that 13 drilled shaft type retaining walls are planned as noted in Table 1. Global stability of the retaining walls and provided geotechnical design recommendations for the retaining walls is discussed further in Section C.4.

C.1.c. Bridge Foundations We drilled a boring at each of the proposed bridge abutments near MP 619.03, 620.40, 620.60, and

621.06. In our borings, we encountered shale or limestone rock material at depths ranging from 9 to 30 feet. Based on the results of our evaluation, it is our professional opinion that the bridges can be supported on driven/pre-drilled, set-in-place steel HP 14x89 piles embedded into the underlying rock.

Recommendations for the bridge foundations are included in Section C.8.

C.1.d. Box Culverts One reinforced concrete box (RCB) culvert and two reinforced concrete pipe (RCP) culverts are planned as part of the project. RCP culverts should be installed per the manufacturers bedding and installation recommendations. Based on the culvert profile and geologic information obtained in the vicinity the RCB culvert planned at Sta. 19+47 (MP618.76), we anticipate that RCB culvert will be supported by clayey

Trinity Metro – TRE Double Track sands. The existing TRE ML1 bridge at this location will remain in-place. Specific culvert geotechnical design recommendations are presented in Section C.5.

C.1.e. Limitations The recommendations submitted herein are based, in part, upon data obtained from our subsurface exploration. The nature and extent of subsurface variations that may exist at the proposed project site will not become evident until construction. If variations appear evident, then the recommendations presented in this report should be evaluated in light of them. In the event that any changes in the nature, design, location or elevations of the proposed tracks are planned, the conclusions and recommendations contained in this report will not be considered valid unless the changes are reviewed, and our recommendations are modified in writing.

It is important to note that the following recommendations are limited to the area evaluated as described herein. Information and recommendations presented in this report should not be extrapolated to other areas or sites.

C.2. Subgrade Preparation and Site Grading

C.2.a. Site Stripping and Grubbing We recommend stripping vegetation, topsoil, and surface or buried debris from construction areas.

Stripping operations should be observed by a geotechnical engineer or technician working under the direction of a geotechnical engineer to confirm unsuitable materials have been removed prior to filling or placement of track section materials. We recommend the stripped materials be wasted outside embankment and track subgrade limits or placed as topsoil fill on finished embankment slopes if compliant with embankment topsoil specifications.

Care should be taken to remove stumps associated with larger shrubs and trees in the area. Materials disturbed during stump removal should be restored with structural fill.

C.2.b. Undercutting and Subgrade Stabilization Based on the results of our evaluation, we anticipate that the existing on-site materials if moisture conditioned and compacted to the requirements of structural fill within 9 inches of planned subgrade should be suitable for support of the anticipated embankment and track loading along the majority of the alignment.

Trinity Metro – TRE Double Track

Should soft, weak, or otherwise unstable soils be encountered during subgrade preparation, we recommend removing and recompacting or replacing such soils with structural fill or aggregate (“shot rock”) as appropriate/available. New fill placed in this area will need to be “benched” into the existing embankment, as described in Section C.2.i. We recommend having a geotechnical engineer or technician working under the direction of a geotechnical engineer assist in determining the limits and adequacy of corrective excavations and evaluating backfill options. Additional drainage measures could also be considered to improve stability of these areas.

C.2.c. Site Drainage Providing site drainage will be critical to long-term performance of embankments and tracks. Final site grading should route surface water away from track sections to a suitable location. Track ditches should be sloped and routed to promote removal of water from the site. Existing ditches should be rerouted and planned ditches should be installed at the beginning of construction to aid in controlling surface water and saturation of embankment subgrades.

C.2.d. Subgrade Preparation Following stripping, to address track substructure support requirements summarized below in Section C.7, we recommend that surfaces to receive fill or track section materials be scarified to a depth no less than 6 inches below subballast elevations, moisture conditioned to moisture contents within the ranges given below (Section C.2.g) and compacted to the relative compaction values given in Table 5.

We then recommend proof rolling prepared subgrades to evaluate subgrade stability. Proof rolling can be accomplished through use of a fully-loaded, tandem-axle dump truck or similar equipment providing an equivalent subgrade loading. Unsuitable areas identified by the proof rolling operation should be undercut and replaced with structural fill.

C.2.e. Existing Track Drainage - Trench Drains If ballast fouling/mud pumping is observed in the existing track during construction, we recommend that ballast filled trench drains be installed into the existing ballast pocket and embankment and extending through the proposed embankment to drain.

The following sections outline the trench drain construction:

Trench drains should be excavated perpendicular to the embankment slope at an effective center-to-center spacing of 25 feet to 50 feet as determined in the field.

Trinity Metro – TRE Double Track

The trench drain spacing should be optimized (i.e., locations adjusted) so that drains are located in observable subgrade problem areas (i.e., observed fouled ballast).

The drain should extend below the existing a track to the bottom of ballast pocket, be sloped to drain at a minimum 2% slope and extend below the new track and access road to an outlet in the planned ditch.

Trench drains should be approximately 2 foot in width.

The drains should be graded to drain and backfilled with free draining, granular material wrapped in filter fabric (i.e., Mirafi 180N or similar non-woven geotextile) or sand material.

The outlets of each drain should be covered with ballast or drainage rock material.

Trench drains should be excavated perpendicular to the embankment slope at an effective center-to-center spacing of 25 to 50 feet in the area of concern.

C.2.f. Excavation Backfill and Embankment Fill

We recommend excavation backfill and additional required embankment fill consist of approved materials classifying as ASTM D2487 GW, GP (angular), GC, GM, SM, SW, SC, SP, CL and CH (PI≤30) . We further recommend these materials contain less than 3 percent of organic matter.

Per UP General Specifications (07-01-2021), fat clay (CH) with a PI≥15 can be used as embankment fill materials, if amended with lime or placed within the core of the embankment. In that, we recommend that untreated embankment fill comprised of fat clay with a 15≤PI≤30 should not be placed within 3 feet of the track subgrade or side slope ground surface. We anticipate that hydrated lime incorporated at approximately 6 percent by dry weight basis would be required to amend fat clay fill materials (15≤PI≤30) for reuse in the upper portion of embankment fill. Additional sulfate and lime series testing should be performed on the onsite and planned borrow materials to determine soil suitability for lime stabilization and the amount of lime required to reduce the plasticity characteristics to meet UP specification requirements.

Soils considered unsuitable for reuse as excavation backfill or embankment fill classify as ASTM D2487 GP (rounded), ML, CL-ML, MH, OL, OH, PT and CH with PI>30.

Trinity Metro – TRE Double Track

Based on these considerations, the bulk of the filled and naturally deposited soils encountered by our borings appear suitable for reuse, assuming they are segregated from vegetation, topsoil and, in the case of fill, entrained debris.

Additional testing of borrow materials planned for use as retaining wall backfill will be required to assess drained shear strength parameters.

Fine-grained soils (i.e., clays) being considered for reuse may be moisture sensitive and subject to disturbance, particularly if they are wet of their optimum moisture content. Moisture conditioning of these materials will likely be required during fill placement.

In small, confined areas that are difficult to compact with conventional or hand equipment, such as utility trenches, and narrow excavations, the contractor could use Controlled Low Strength Material (CLSM), also referred to as “flowable fill” or “lean mix.” as backfill material. In wall backfill applications, the CLSM should be placed in multiple lifts to help reduce pre-cure lateral pressure on the foundation walls. In addition, measures will be required to prevent clogging of the wall drain system due to placement of CLSM backfill.

C.2.g. Placement and Compaction of Fill Based on the clayey nature of the planned native and fill materials, we recommend compaction in accordance with test method ASTM D698 (Standard Proctor). We recommend placing fill in loose lifts no greater than 8 inches. We recommend moisture conditioning and compacting excavation backfill and additional embankment fill in accordance with the criteria presented below in Table 5.

The relative compaction of utility backfill should be evaluated based on the structure below which it is installed and proximity to that structure. Moisture and compaction specifications for utility backfill should be established based on the structure below which it is installed and the proximity to that structure.

Trinity Metro – TRE Double Track

Table 5. Compaction Recommendations Summary

Reference

Relative Compaction, %

(ASTM D 698

– Standard Proctor) Moisture Content Variance from

Optimum, percentage points Embankments/Track Substructure Soil < 3 foot below subgrade Soil > 3 foot below subgrade Soil Within 100 ft of Bridge Abutments Soil within 20 ft of Culvert Subballast

Cohesive Fill with LL>40: 0 to +4 Cohesive Fill with LL≤40: -1 to +3 Granular Fill: -3 to +3

Access Roads Aggregate Base/Subballast Subgrade Soils

Retaining Wall Clay/Sand Backfill Aggregate Backfill

Moisture and compaction specifications for utility backfill should be established based on the structure below which it is installed and the vertical proximity to that structure.

The contractor should expect that it will be necessary to adjust the moisture content of the on-site soils to levels suitable to achieve the specified compaction. Moisture contents should be maintained within the recommended range until completion of the embankment.

The project documents should not allow the contractor to use frozen material as engineered fill or to place engineered fill on frozen material.

C.2.h. Benching We recommend benching fill into slopes steeper than 5H:1V (horizontal: vertical). Benches can be established in advance of filling or cut into the slopes as fill is being spread and compacted. If cut in advance, we recommend a limiting bench height of 2 feet.

If water is found seeping from slopes during benching or grading operations, we recommend consulting with a geotechnical engineer to determine how best to capture and dispose of that water (e.g., trench drain, chimney drain, drain tile, etc.).

Trinity Metro – TRE Double Track

C.2.i. Permanent Slopes We recommend that typical cut and fill slopes are designed at gradients no steeper than 3:1 (horizontal:

vertical) for the track embankment. For permanent cut and fill soil slopes designed at a 3H:1V, additional maintenance of the slopes (i.e., regrading) due to potential near surface instability (i.e., sloughing) and riling will likely be required during the life of the project.

To maintain track subgrade stability, the crest/shoulder of the embankment subgrade should be no closer than 15 feet from the centerline of proposed track.

We recommend vegetating slopes as soon as practical to minimize the potential for erosion. In addition, surface water should not be directed over the crest of the slopes in an uncontrolled fashion.

Embankments constructed of sandy silts (SM), silty clays (CL) or silts (ML) with PI<10 will be prone to surface rilling and erosion. We recommend that the flow on unprotected embankment slopes be limited to 2.0 feet/second on silts (ML) and sandy silt (SM) slopes and to 3.5 feet/second for clay (CL with PI>10, CH) slopes, to reduce potential surface erosion.

C.2.j. Site Utilities Proposed construction settlement impacts to existing and proposed utilities beneath embankment loads should be evaluated during design. We recommend this include an assessment of the condition of existing utilities. Existing utilities that could be unfavorably impacted by settlement should be reinstalled post-construction or relocated.

We recommend evaluating backfill above existing utilities to confirm if it is suitable for support of embankment fill. Hand auger borings, dynamic cone penetrometer tests, and compaction tests would assist in this evaluation.

Excavations for utility installation, removal, or maintenance should be wide enough to accommodate equipment capable of producing relative compaction consistent with the parameters above in Table 5.

We recommend placing utility backfill in accordance with the recommendations presented above in Section C.2.g.

We recommend that constrained utility excavations – those that cannot accommodate conventional compaction equipment – be backfilled with Controlled Low Strength Material (CLSM), also referred to as “flowable fill” or “lean mix.”

Trinity Metro – TRE Double Track

C.2.k. Temporary Excavations We recommend that excavations comply with applicable railroad, local, state, and federal safety regulations. The responsibility for excavation safety and stability of temporary construction slopes lies solely with the Contractor. We are providing this information below solely as a service to our client.

Under no circumstances should it be assumed that Braun Intertec is responsible for construction site safety or the Contractor’s activities.

C.2.k.1. Soil Classification The majority of the filled and naturally deposited soils encountered by our borings classify as Type “B” or “C” soils under Occupational Safety and Health Administration (OSHA) 29 CFR, Part 1926, Subpart P, “Excavations and Trenches”. Therefore, unbraced excavations should be maintained at a minimum slope of 1.5H:1V (Horizontal: Vertical) for OSHA soil types “B” or “C”, respectively. The contractor should evaluate the actual field conditions and classify the soils and required excavation slopes at the time of construction.

All shoring and excavations adjacent to existing track should comply with AREMA and UPRR/BNSF Temporary Shoring Guidelines and be designed for railroad loading where applicable.

C.2.k.2. Excavation Dewatering We do not anticipate that the majority of excavations at this site will extend below the hydrostatic groundwater table. We recommend removing water from excavations prior to backfilling. Sumps and pumps can be considered for excavations in low-permeability clay-rich soils. Special conditions or methods may be required for construction of the box culvert, pipes and bridge elements in our near the flow line of existing creeks and waterways.

C.2.k.3. Excavation Backfill Excavation backfill supporting the track substructure should consist of structural fill materials as outlined in Section C.2.g or meets the manufacturer’s requirements for pipe structures. On-site soils that meet this requirement and are free of organic soil and debris may be suitable for reuse as backfill and fill.

C.2.l. Climatic Conditions Weather conditions will influence the site preparation required. Following periods of rainfall, the moisture content of the near-surface soils may be significantly above the optimum moisture content.

Excessive moisture could seriously impede grading by causing an unstable subgrade condition. Typical remedial measures include aerating the wet subgrade, removal of the wet materials and replacing them with materials at or near optimum moisture, or treating the material with lime, cement or fly ash.

Trinity Metro – TRE Double Track

If site grading commences during summer months, moisture contents may be low and typical discing and moisture conditioning of the exposed subgrade materials may be required. As an alternative, the dry soils could be undercut and replaced with structural fill.

If construction of the project is to be performed during winter months, appropriate steps should be taken to prevent the soils from freezing. In no case should the ballast, fill or any exterior flat work be placed on or against frozen or partially frozen materials. Frozen materials should be removed and replaced with a suitable material. Frozen materials should not be included in any compacted fills.

C.3. Embankments

C.3.a. Embankment Settlement Embankment settlement will be governed by the compressibility of the soils on which embankment fill is placed and the thickness of that fill. These things considered, we anticipate between 2 to 3 inches of embankment settlement is possible long-term, assuming the subgrade preparation procedures outlined above are followed for the embankment construction. Thus, any settlement after completion of construction can be addressed during resurfacing operations.

C.3.b. Steepened Slopes We understand, based on the 90% plans dated December 2, 2024, the typical cut and fill slopes are designed at gradients no steeper than 3H:1V (horizontal: vertical) as recommended in Section C.2.i, except for areas where right-of-way restrictions and utilities which require steepened slopes of up to 2H:1V. We have noted six locations with steepened slopes in Table 6. We evaluated the global stability of the end-of-construction (undrained) and long term (drained) conditions for the proposed 2H:1V slope.

We recommend using an acceptance criterion of minimum factor of safety values of 1.3 and 1.5 for undrained and drained conditions, respectively.

Trinity Metro – TRE Double Track

Table 6. Global Stability Analysis Results for Steepened Slopes

Description Station

Start Station

End Max.

Height Analyzed Station

Factor of Safety Short-Term (Undrained)

Long-Term (Drained)

Fill Slope 2H:1V 26+00 31+50 29 29+00 --- 1.5* Concrete Protected Slope 2H:1V 60+75 78+50

17 73+00 1.9 1.5 Ditch 2H:1V 71+44 78+50

Concrete Protected Slope 2H:1V 122+98 126+00.19 6 123+00 --- 1.3* Concrete Protected Slope 2H:1V 132+50 133+00 10 132+75 1.7 1.5

Concrete Protected Slope 2.5H:1V 145+75 150+25 18 146+00 1.5 1.6

*See discussion below regarding the long-term stabilization of the proposed slopes.

To meet the long term design criteria in newly constructed embankment slopes, the new embankments in areas of the steepened slope will need to be constructed using clay materials having minimum effective shear strength parameters of cohesion(c’)=150 psf and friction angle(φ)=27 degrees. Additional testing of planned borrow prior to fill placement will be required to establish actual shear strength parameters of materials.

Sta. 26+00 to 31+50: Based on the provided cross-sections, we understand that the existing embankment outside right-of-way is standing at about 1.3H:1V. We did not perform geotechnical fieldwork specifically at this location which is outside of ROW; therefore, we assumed that subsurface conditions are consistent with material encountered in our nearby borings.

We anticipate that long term slope movement will occur outside ROW at this configuration due to anticipated slope materials, weather influence (i.e., wetting/drying), and introduction of water at the slope crest from the proposed ditch. In that, the track embankment and ditch flow characteristics may be impacted by progressive slope movement. We would recommend that the slope in this area be flattened to 3H:1V or stabilized to reduce potential movement.

Sta. 122+98 to 126+00.19: Based on the subsurface profile from borings RW-15 and RW-16, we anticipate the proposed backslope consists primarily of sand and clayey sand. Due to the non-cohesive nature of these materials, we anticipate surficial slope sloughing of the planned 2H:1V backslope which will lead to material accumulation and potential clogging of the ditch. We recommend the planned backslope in this area be designed flatter than 2.5H:1V or reinforced with erosion control materials to maintain slope integrity.

Trinity Metro – TRE Double Track

C.4. Retaining Walls

C.4.a. Wall Locations, Heights, and Type Project plan and alignment and typical cross sections have been provided for reference in the below documents for our evaluation.

Trinity Railway Express - Double Tracking, Handley-Ederville Road to Precinct Line Road 90% Submittal, provided by TranSystems, dated December 2024.

Communication with TranSystems in October and December 2024 regarding retaining wall types.

Based on our review of the plans and conversations with TranSystems, 12 retaining walls are planned along the project to support fills and to retain native materials in cut areas. We further understand that the retaining walls will be designed as either 1) drilled shaft supported cast-in-place concrete walls in fill areas, 2) drilled shafts with a cast-in-place facing in cut areas or 3) trench walls (see Figure 4, Typical Sections). The proposed retaining walls, locations, maximum wall heights, and relevant borings are presented in Table 7.

C.4.b. Design Criteria The design of the retaining wall system includes but is not limited to selection of wall type, wall design, global stability of wall, settlement, retention of backfill, proper drainage to prevent trapped water behind the wall, and protection of adjacent structures, utilities, fences, or property immediately behind the wall.

Retaining walls should be designed in accordance with the AREMA MRE.

Of note, due to the proximity of existing railroad track and adjacent structures, temporary shoring may be required to complete the construction permanent retaining wall and safely protect personnel and adjacent track, structures, utilities, and property. Temporary shoring should be designed in accordance with the “UP/BNSF Guidelines for Temporary Shoring,” dated 12/7/2021.

C.4.c. Design Loads Loads include, but are not limited to, earth pressure, railroad track loading, railroad service vehicles (HS- 20 truck) on access roadways, fills placed above the top of the walls, construction equipment, crane pads, future grading and paving, structures, material storage piles, and snow. Lateral loads induced by these loads should be applied in the design of retaining walls. The retaining wall should be designed to structurally withstand all applied loads and anticipated deformation.

Trinity Metro – TRE Double Track

Track surcharge (i.e., Cooper E80 load) can be modeled as a strip load with a width of 8.5 ft and intensity of 1.882 ksf. Track surcharge should be applied simultaneously at all track locations shown in the cross sections in design. Other surcharge loads should be applied as outlined in AREMA MRE or the UPRR & BNSF Guidelines for Temporary Shoring.

Figure 4. Typical Drilled Shaft Walls 1) Fill Wall, 2) Cut Wall and 3) Trench Wall (from 90% plans), dated December 2, 2024.

1) Drilled Shaft Fill Wall 2) Drilled Shaft Cut Wall 3) Trench Cut Wall

Trinity Metro – TRE Double Track

Table 7. Summary of Proposed Retaining Wall Information

Wall No.

Location Approximate

Mainline Station Typical Section

Wall Type

Estimated Maximum

Exposed Wall Height (ft) Borings

RW-01 13+00 to 17+00 Fill Trench Foundation supported CIP Wall 2

RW-02 19+00 to 20+49 Fill Drilled Shaft supported CIP Wall 13 RW-05/06

RW-02A 20+72 to 20+22 Fill Drilled Shaft supported CIP Wall 16 RW-05/06

RW-03 20+59 to 22+50 Fill Drilled Shaft supported

CIP Wall 18 RW-06

RW-04 DELETED per TranSystems Segment changed to 3H:1V graded slope

RW-05 35+00 to 36+47 Fill Drilled Shaft supported CIP Wall 10 B-01

RW-06

37+01.10 to 41+00 Fill Drilled Shaft supported

CIP Wall 13 B-02

41+00 to 45+75 Cut Drilled Shaft w/

CIP Facing w/ 2H:1V Backslope1

17 CW-11/ 12

RWTL 53+97 to 54+72 Fill Trench Foundation supported CIP Wall 2 1/2 RW-14/TK-01

RW-08 106+00 to 113+38 Fill Drilled Shaft supported

CIP Wall 12 B-03

RW-09 114+90 to 118+99 Fill Drilled Shaft supported

CIP Wall 12 B-04/05

RW-10 120+12 to 121+50 Fill Drilled Shaft supported

CIP Wall 16 B-06

RW-11A 126+00 to 132+00 Cut

Drilled Shaft w/ CIP Facing w/ 2H:1V Backslope1

3 CW-17

RW-11B 133+00 to 138+50 Cut

Drilled Shaft w/ CIP Facing w/ 2H:1V Backslope1

6 CW-19

1The 2H:1V backslope will not be globally stable long term, slope should be flattened to 3H:1V.

Trinity Metro – TRE Double Track

C.4.d. Drilled Shaft and Trench Retaining Wall Geotechnical Design Parameters The information obtained from this geotechnical investigation was used to develop our design geologic profile and groundwater conditions. The design geologic profile and design parameters for each wall are included in Table A-1 of the Appendix. The selection of engineering parameters for use in our evaluations was based on available laboratory test results, local experience with similar soils, project details, and engineering judgment. Groundwater levels and fluctuations appropriate for the planned structure and future events should be used in evaluation of the structure.

C.4.e. Evaluation Assumptions We have assumed the following in our evaluation of the wall systems:

The following summarizes our geotechnical design information and assumptions:

Geotechnical design parameters for use in the evaluation of lateral load resistance and deflection of drilled shaft walls for soils and rock are included in Table A-1 in the Appendix.

Sloping grades or influence of other structures or utilities should be included in the analyses.

A minimum 4-foot bench in the front or behind the wall

3H:1V or flatter foreslopes in front of the wall or backslopes behind the wall

No walls will be subject to flooding or inundated during storm events.

The bottom of wall will be embedded a minimum of 2.5 feet below final exterior grades.

Walls will be supported by 30 to 48 inch diameter drilled shafts at 5 to 8 feet c-c spacing.

Drilled shafts will provide shear resistance needed to maintain global stability.

Drilled shafts will have a minimum length of 12 feet.

Drilled shafts should be located to avoid any potential conflicts with existing bridge foundations, utilities, pipelines, or structure components.