WV_ERFO_FS_2016-1(4)_-_Final_Geotech_Report.pdf

SOILS AND FOUNDATIONS

REPORT NO. 02-19

PROJECT: WV ERFO FS 2016-1(4)

BOX CULVERT AND BRIDGE CONSTRUCTION

MONONGAHELA NATIONAL FOREST

WEBSTER COUNTY, WEST VIRGINIA

US DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION

EASTERN FEDERAL LANDS HIGHWAY DIVISION

21400 RIDGETOP CIRCLE

STERLING, VA 20166

JANUARY 19

TABLE OF CONTENTS

1. INTRODUCTION

1.1. General

1.2. Project Location

1.3. Background

2. GEOLOGY

2.1. Regional Geology

2.2. Soil Survey

3. SUBSURFACE EXPLORATION PROGRAM

3.1. Drilling and Sampling

3.2. Data Summary

3.3. Laboratory Testing

4. SUBSURFACE CONDITIONS

4.1. Stratification

5. DESIGN ANALYSIS AND RECOMMENDATIONS

5.1. Design Analysis

5.2. Recommendations

6. CONSTRUCTION SPECIFICATIONS

6.1. General

6.2. Excavations and Foundation Preparation

6.3. Ground and Surface Water Management

6.4. Backfill Material and Placement

7. REFERENCES

8. DISCLAIMER/LIMITATIONS CLAUSE

APPENDICES

Appendix A – Figures

Appendix B – Boring Location Map and Subsurface Profile

Appendix C – Boring Logs

Appendix D – Laboratory Testing

Appendix E – Design Computations

Appendix F – Preliminary Construction Plans

Appendix G – Site Photographs

Note: Design changes subsequent to publication of this report and prior to the project’s advertisement will be documented by a memo attached after the title page.

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PAGE 3 OF 35 DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION

EASTERN FEDERAL LANDS HIGHWAY DIVISION

STERLING, VA

SOILS AND FOUNDATIONS

REPORT NO. 02-19

MONONGAHELA NATIONAL FOREST

WEBSTER COUNTY, WEST VIRGINIA

1. INTRODUCTION

1.1. General

This report presents the findings of our subsurface exploration and laboratory testing and provides preliminary recommendations for the foundations of the proposed precast reinforced concrete box culvert and a single span bridge.

1.2. Project Location

The precast reinforced concrete box culvert, and the single span bridge site are located along Williams River

Road (FS Rte 86) at MP 9.5 and MP 10.8 respectively in the Monongahela National Forest in Webster

County, West Virginia. Site locations are shown in Figure 1, Appendix A.

1.3. Background

Monongahela National Forest Service was devastated by a 1000-year storm between June 23 and June 26, 2016 causing widespread road damage. Proposed for construction at MP 9.5 is a 12-ft wide by 5-ft high reinforced concrete box culvert. The damaged bridge located at MP 10.8 will be replaced with a 30-ft long single span bridge.

2. GEOLOGY

2.1. Regional Geology

The Geologic Map of West Virginia (1968) indicated that the parent rock at the project sites are predominantly the Hinton Formation (Mh) and the Bluestone and Princeton Formation (Mbp).The Hinton

Formation is described as red, green and medium-gray shale and sandstone, with a few thin limestone beds, including the Avis.

The Bluestone formation is described as a red shale, but contains many beds of impure limestone, sometimes conglomeratic, and red sandstone of varying thickness and character. The Princeton formation varies from a siliceous to calcareous sandstone, and in places is interbedded with shale.

The geologic map of the area is shown in Figure 2 of Appendix A.

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FEDERAL HIGHWAY ADMINISTRATION

EASTERN FEDERAL LANDS HIGHWAY DIVISION

STERLING, VA

2.2. Soil Survey

A soil survey evaluation was performed using the USDA-NRCS Web Soil Survey website to obtain estimated shallow geologic information. It was found that the sites are located in a Snowdog channery loam

(SwE) and Chavies fine sandy loam (Ch). See Figure No. 3 of “Appendix A – Figures” to see the project soil survey map.

3. SUBSURFACE EXPLORATION PROGRAM

3.1. Drilling and Sampling

A subsurface exploration program was conducted on July 27 and 29, 2017 by the EFLHD subsurface exploration team. The program consisted of drilling one (1) boring at each structure. The borings were advanced to their termination depths with a CME 750 ATV-mounted rotary drill rig. The boring locations were selected by an EFLHD geotechnical engineer based on the location of existing structures, presence of underground utilities, and accessibility of the drilling rig. All boreholes were backfilled with auger cuttings upon completion. Boreholes were laid out by EFLHD field personnel by measuring distances from mapped landmarks and using a hand-held GPS. Boring elevations were determined from plan topography. The borings are graphically depicted on the Boring Location Plan in Appendix B. Boring logs are presented in

Appendix C.

Rock coring was performed in both of the borings using rotary drilling techniques and samples were retrieved using an NQ core barrel and wireline. Rock core samples were preserved in wooden boxes for laboratory testing. Borings CH17-03 (MP 10.8) and CH17-04 (MP 9.5) extended to depths of 13.8 ft. and

28.9 ft below existing site grades, respectively. See Table No. 1 for additional subsurface exploration information.

Table No. 1: Subsurface exploration summary table.

Boring No. Location Northing Easting Surface Elev. (ft) Depth (ft)

CH17-03 MP 10.8 4246535.6 560996.4 2629.0 13.8

CH17-04 MP 9.5 4245229.5 551515.4 2560.0 28.9

The EFLHD geotechnical crew performed field tests and took measurements during the course of the subsurface exploration. Percent core recovery (CR) and rock quality designation (RQD) were determined for each core run to provide a quantitative basis for evaluation of the conditions of the rock.

3.2. Data Summary

The results of the field tests and measurements were recorded in the driller’s logs and appropriate data sheets in the field. These data sheets and logs contain information concerning the boring methods, samples attempted and recovered, and indications of materials encountered. They also contain interpretations by the exploration foreman of the subsurface conditions based on the performance of the equipment and cuttings

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FEDERAL HIGHWAY ADMINISTRATION

EASTERN FEDERAL LANDS HIGHWAY DIVISION

STERLING, VA

brought to the surface by the drilling tools. Therefore, the field data represents both factual and interpretative information.

The boring logs in Appendix C represent compilation of field and laboratory data.

3.3. Laboratory Testing

A laboratory testing program was conducted on representative rock samples recovered during the subsurface explorations. Unconfined compressive strength, following ASTM D7012 standards, was conducted on representative rock samples to evaluate the strength of the bedrock. The laboratory testing results are presented in Appendix D and are summarized in Table 1.

Table No. 2: Summary of geotechnical laboratory test results.

Run# Rock Depth

(ft) Rock Type

*RQD

**UCS

(psi)

C-3 / MP 10.8 / R-2 5.0-13.8 Sandstone 98 11,310

C-4 / MP 9.5 / R-6 21.8-28.9 Sandstone 100 22,290

*RQD: Rock Quality Designation.

**UCS: Unconfined compressive strength.

4. SUBSURFACE CONDITIONS

4.1. Stratification

Descriptions of the rock conditions encountered during the subsurface exploration are presented below. The stratification lines designating the interfaces between rock types on the boring logs represent approximate boundaries. The subsurface layers encountered were as follows:

▪ FSRD 86 MP 10.8

Boring CH17-03 encountered a 5 ft thick layer of conglomerate, followed by Sandstone rock. The

Sandstone layer extended to the termination depth of the boring and yielded an RQD value of 98%.

An unconfined compressive strength value of 11,310 psi (78 MPa) was obtained from laboratory testing, indicating strong rock (R4) per Table II.3 of Wyllie (1999).

▪ FSRD 86 MP 9.5

Boring CH17-04 yielded a 22 ft thick layer of conglomerate, followed by Sandstone rock. The

Sandstone layer extended to the termination depth of the boring and yielded an RQD value of 100%.

An unconfined compressive strength value of 22,290 psi (154 MPa) was obtained from laboratory testing, indicating very strong rock (R5) per Table II.3 of Wyllie (1999).

▪ Groundwater

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FEDERAL HIGHWAY ADMINISTRATION

EASTERN FEDERAL LANDS HIGHWAY DIVISION

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No reliable groundwater measurements were obtained because water was introduced during the rock coring process. However, it should be noted that fluctuations in the groundwater conditions due to seasonal weather changes should be anticipated.

5. DESIGN ANALYSIS AND RECOMMENDATIONS

Based on our familiarity with similar subsurface conditions and similar projects, we concluded that shallow footings supported on Sandstone rock represent the most cost-effective foundation system for the proposed developments.

5.1. Design Analysis

Bridge foundation recommendations was conducted using limit equilibrium methodology, following

“AASHTO LRFD Bridge Design Specifications, 8th Ed.” (2017) design requirements. A summary of rock engineering parameters assumed in the analyses is presented in Table No. 3

Table No. 3: Foundation engineering properties.

Material

Type

Unit Weight

(pcf)

Cohesion

(psf)

Hoek-Brown Rock

Strength Criterion

(psf)

Internal Friction

Angle ϕ

Sandstone Rock 150 814 175 27°

The resistance factor used for design for both sites are presented in Table No. 4, following (AASHTO-

LRFD, 2017) Section 11.5.7.

Table No. 4: Bridge foundation design resistance factors.

Analysis Resistance Factor

Bearing Φb: 0.45

5.2. Recommendations

Our computations indicated that a bedrock factored bearing resistance (qR) of 1,100 ksf is recommended.

See Appendix E for bearing resistance computations.

6. CONSTRUCTION SPECIFICATIONS

6.1. General

Construction shall be performed following the Standard Specifications for Construction of Roads and

Bridges on Federal Highway Projects (FP-14) and the Special Contract Requirements (SCR).

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FEDERAL HIGHWAY ADMINISTRATION

EASTERN FEDERAL LANDS HIGHWAY DIVISION

STERLING, VA

6.2. Excavations and Foundation Preparation

All excavations are to be performed in accordance with applicable OSHA, Federal and West Virginia regulations and with Section 208 of Standard Specifications for Construction of Roads and Bridges on

Federal Highway Projects (FP-14). Foundation for abutments should be prepared meeting the requirements in Subsection 208.08 of FP-14.

6.3. Ground and Surface Water Management

Control of storm water or seepage water flowing into open excavations and through the cracks between the rocks is necessary in order to maintain dry conditions during construction. The contractor should control the flow of surface water and seepage water into excavations at all times. Storm water collection and control during construction may be performed using collection trenches and sumps, if accumulation does occur.

6.4. Backfill Material and Placement

Backfill material should be structural backfill meeting requirements of Section 704.04 of the FP-14.

Backfill material should be placed and compacted in accordance with Section 209.09 and 209.10 respectively of FP-14. In addition, requirements shown in Subsection 259.13 shall be met.

7. REFERENCES

AASHTO-LRFD. (2017). AASHTO LRFD Bridge Design Specification (8th ed.). Washington, D.C.:

American Association of State Highway and Transportation Officials.

FHWA. (2014). Standard Specifications For Construction of Roads and Bridges on Federal Highway

Projects (FP-14). US Department of Transportation. Washington D.C.: US Department of

Transportation.

Goodman, R. E. (1989). Introdcution to Rock Mechanics" (2nd ed.).

NRCS, U. . (2018, 05 09). Web Soil Survey. Retrieved from Web Soil Survey:

https://websoilsurvey.sc.egov.usda.gov/App/WebSoilSurvey.aspx

USACE. (1994). Engineering and Design - Rock Foundations. Washington D. C: USACE.

Zhang, L. (2005). Engineering Properties of Rock. Elsevier Science.

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FEDERAL HIGHWAY ADMINISTRATION

EASTERN FEDERAL LANDS HIGHWAY DIVISION

STERLING, VA

8. DISCLAIMER/LIMITATIONS CLAUSE

The subsurface explorations and test described in this report have been conducted in accordance with standard practices and procedures (except as specifically noted). The results of these exploration and test represent conditions at the specific locations and dates indicated. Subsurface conditions between these locations may vary. The Geotechnical Design Analyses and Recommendations Sections of this report include interpretations and recommendations developed by the Government in the process of preparing the design. These interpretations are not intended as a substitute for the personal investigation, independent interpretation, and judgment of the Contractor.

Prepared by:

Jonathan Herrera-Roldán, P.E.

Geotechnical Engineer

Reviewed by:

Mounir Abouzakhm, P.E.

Division Geotechnical Engineer

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FEDERAL HIGHWAY ADMINISTRATION

EASTERN FEDERAL LANDS HIGHWAY DIVISION

STERLING, VA

APPENDICES

Appendix A – Figures A - 10

Appendix B – Boring Location Map A - 14

Appendix C – Boring Logs A - 16

Appendix D – Laboratory Testing A - 21

Appendix E – Design Computations A - 24

Appendix F – Preliminary Construction Plans A - 29

Appendix G – Site Photographs A - 35

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Appendix A – Figures

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Appendix B – Boring Location Map and Subsurface Profile

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CH17-03

CH17-03

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Appendix C – Boring Logs

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Appendix D – Laboratory Testing

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Appendix E – Design Computations

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Appendix F – Preliminary Construction Plans

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Appendix G – Site Photographs

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Figure No. 1: FSRD 86, MP 9.5 – Box Culvert location.

Figure No. 2: FSRD 86, MP 10.8 – Bridge replacement location.

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Figure No. 3: FSRD 86, MP 10.8 – Core box.