W912QR25R0016_CERT_Final_Vol6_ PH1B_DrillFMCR_1of20-0000.pdf

Solicitation For Rough River Dam Safety Modification Project Phase I - New Outlet Works and Cutoff Wall, Rough River Reservoir, Falls of Rough, KY

P2: 145870 Design-Bid-Build

Construction Materials and Foundation Completion Report Vol. 6 (1 of 20)

Certified Final

20 December 2024

W912QR25R0016

ARIMS: 1200

Disposition: Permanent

W912QR25R0016_CERT_Final_Vol6_ PH1B_DrillFMCR_1of20-0000

Rough River Dam (KY03012)

Construction Materials and Foundation Completion Report

Rough River Dam Safety Modification Phase 1

Falls of Rough, KY

Status: Final Report

March 2024

Controlled by: U.S. Army Corps of Engineers Controlled by: CELRL-ED Limited Dissemination Control: FEDCON POC: Troy O’Neal (DSPM), 513-684-3804

US Army Corps of Engineers

Louisville District

Page Intentionally Left Blank

Rough River Dam Louisville District i

Executive Summary

A Dam Safety Modification Report (DSMR) was completed in 2012 which identified internal erosion risk driving failure modes in the foundation of Rough River Dam. The DSMR recommended executing a series of contracts to permanently modify the dam foundation to reduce risks for dam failure to below tolerable risk guidelines as described in ER 1110-2-1156 Safety of Dams – Policies and Procedures (dated 31 March 2014). The Phase 1A Project was executed to relocate the existing state highway to the upstream dam crest. After Phase 1A was complete, the Louisville District installed additional piezometers along the dam crest to monitor conditions in the foundation. The Phase 1B Exploratory Drilling and Grouting (Phase 1B Project) was required to better understand foundation conditions at the dam and for slurry control grouting in advance of the future Phase 2 Cutoff Wall Project (Phase 2 Project). The Phase 2 Project required additional slurry control grouting, installation of a cut-off wall across the dam foundation extending over and around the existing outlet conduit, grouting from below the conduit, and a downstream filter. In 2018, the Phase 2 Project DSMR was modified with a supplement to include a new left abutment outlet works to facilitate installation of the full-length cutoff wall through the existing outlet conduit and the karstic limestone the structure is founded upon. Phase 1 of the project was endorsed by the Dam Safety Senior Oversight Group (DSOG) and approved by the Assistant Secretary of the Army for Civil Works (ASA(CW)) on 7 March 2013. Components of the Phase 1 Project are summarized below:

Phase 1A: Executed under Contract W912QR-09-D-0050, relocated the existing state highway (KY79) to the upstream face of the dam. Relocation of the highway required modifying the upstream dam slope to a 2H:1V slope. The slope modification was achieved by constructing a rock toe at elevation 495 ft NGVD29 and then placing approximately 36,414 CY (65.5 tons) of rock fill covered by 14,758 CY (22 tons) of KYTC Class III riprap on the dam face.

Additional Piezometers: A total of 59 fully grouted vibrating wire transducers were installed in 21 boreholes along the upstream and downstream crest of the dam under Contract W912P5-13-D- 0003 Delivery Order Number CY01. The system included an Automated Data Acquisition System (ADAS) to monitor the dam foundation during the Phase 1 and Phase 2 Projects.

Phase 1B Project: Executed under Contract W912QR-15-C-0008, completed exploratory drilling and grouting utilizing two partial grout lines to evaluate subsurface conditions and to establish the extents for the proposed cutoff wall. The Phase 1B Project was completed in accordance with the 2015 Design Documentation Report (DDR), EM 1110-2-3506 Grouting Technology (2015 draft), and ER 1110-1-1807 Drilling in Earth Embankment Dams and Levees (dated 31 July 2014). The exploratory grouting was, by design, conducted in such a way as to protect the overburden and embankment from excessive grout pressures and hydro-fracture. The technical approach was reviewed and approved by both the Risk Management Center (RMC) and the Dam Safety Modification Mandatory Center of Expertise (DSMMCX).

The Phase 1B Project targeted grouting efforts in the foundation bedrock. Early in the project, while grouting near the outlet conduit in the Beech Creek Limestone (BCLS), grout was quickly observed exiting into the tailrace downstream of the stilling basin end sill. Grouting confirmed the presence of a continuous defect within the dam foundation extending from the dam centerline past the stilling basin. A Semi-Quantitative Risk Assessment (SQRA) was completed ii in 2016 which recommended completion of both slurry control grout lines as part of the Phase 1B Project followed by immediate installation of the Phase 2 cutoff wall. The Phase 1B contract was modified to require full extension of both partial grout lines. The grout lines were not completed across the conduit or within 5 ft of the conduit on either side as this work remained as part of the Phase 2 Project.

Significant findings from the Phase 1 Activities include:

1. The Phase 1A work relocated the state highway to the upstream face of the dam by permanently modifying the upstream slope between elevation 495 ft and 550 ft NGVD29 to a 2H:1V slope.

2. Locations where the Haney Limestone and BCLS are in direct contact with embankment or foundation soils were determined to be critical areas and required split spaced grout holes down to tertiary holes (5 ft on center).

3. Grout was observed exiting downstream of the stilling basin from grouting activities initiated at the dam crest for hole DXS2192 in the BCLS. Piezometers tipped in the upstream overburden up to 75 ft upstream of the dam centerline reacted to the event (PZ-24, PZ-36, PZ-50/51). This event confirmed a continuous pathway existed from the upstream overburden soils to an open exit downstream of the stilling basin nearly 400 ft downstream.

4. The design intent of the grouting was to take great care to contain the grout within the rock mass, including gravity cap grouting for the upper 15 ft of rock to isolate the injection stages away from the top of rock interface. Regardless of care taken, grout was detected above the top of bedrock in several boreholes during and after the grouting campaign.

5. The karstic area below the existing outlet conduit, and extending 5 ft to either side, was not grouted. This untreated “window” along the primary risk-driving PFM pathway currently remains untreated.

6. Embankment cracks located above the karst bedrock between Stations 18+50 and 19+50 and from Station 21+90 to 22+10 were identified; these cracks are interpreted as embankment distress. High annular space grout takes were also observed in these areas.

7. In the Haney Limestone, multiple large solution features up to 50 ft wide by 50 ft deep and solutioned cavities up to 8 ft in diameter were encountered in the left abutment.

8. While coring hole DXP2162 and grouting hole DXP2262, pressures were transmitted through the BCLS below the conduit.

9. Alluvial deposits were encountered, including large sand deposits (SP, SP-SC, and SP-SM) ranging up to 40 ft thick across the historic river valley areas.

10. Gas deposits were encountered in two boreholes within the dam overburden soil foundation.

11. Between Stations 19+82 to 21+22, the Sample Sandstone was observed to be oil bearing.

12. Multiple piezometers experienced notable changes from foundation grouting. Grouting operations were halted on several occasions due to piezometer reactions in PZ-40, PZ-41, PZ-42, PZ-58, PZ-24 and PZ-36.

In total, the Phase 1B project successfully installed 328 acceptable grout holes including 20 verification holes. These holes required 32,422 linear ft of overburden and embankment drilling, 7,477 linear ft rock coring, 26,058 linear ft percussion rock drilling, and a total of 212,763 gallons (1,053 cubic yards) of grout injected into the dam foundation bedrock. Cutoff wall installation for the Phase 2 Project was endorsed by the DSOG and approved by the ASA(CW) on 10 February 2017, with a supplement re-approved on 20 October 2021.

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Table of Contents

1. Project Background Information

1.1. Project Location

1.2. Original Construction Authority

1.3. Project Geology

1.3.1. Karst Potential

1.4. Purpose of the Rough River Dam Safety Modification

1.5. Risk Driving Failure Modes

1.6. Existing Project Overview

1.6.1. Dam Embankment

1.6.2. Outlet Works

1.6.3. Emergency Spillway

2. Construction and Modification History

2.1. Outlet Works Construction

2.1.1. Stilling Basin Repairs

2.2. Dam Construction

2.2.1. Native Overburden and Foundation Drains

2.2.2. Right Abutment Special Treatment Zone

2.2.3. 1958 and 1960 Historic Grouting

2.2.4. 1958 Dam Raise

2.3. Dam Safety Assurance Project (DSAP)

2.4. 2011 Record Pool and 2012 Stilling Basin Repairs

3. Phase 1A: State Highway 79 Road Relocation Contract

3.1. Project Overview

3.2. Key Personnel

3.3. Slope Construction Methodology

3.4. Road Construction Methodology

3.5. Materials

3.5.1. Laboratory Test Requirements

3.6. Major Coordinated Efforts and Issues

3.6.1. Piezometer Installation

3.6.2. Unusual Observations from VW Installations

4. Phase 1B: Exploratory Drilling and Grouting Contract

4.1. Project Overview

4.2. Key Personnel

4.3. Borehole Layout, Spacing, and Locations

4.3.1. Grout Hole Naming Convention

4.3.2. Grout Hole Location Methodology

4.3.3. Work Sequence Restrictions

4.3.4. Real-Time Instrumentation Monitoring and Integrated Electronic Records

4.4. Soil/Bedrock Interface Drilling and Grouting Methodology

4.4.1. Embankment/Foundation Drilling Production Rates

4.4.2. PVC Casing Installation and Annulus Grouting Procedure ii

4.4.2.1. Grout Results for Casing Installation Procedure

4.4.3. Upper Interface Zone Grouting – Rock Socket Grouting Procedure

4.5. Bedrock Drilling and Grouting Methodology

4.5.1. Rock Coring

4.5.1.1. Rock Coring Production Rate

4.5.2. Percussion Rock Drilling

4.5.2.1. Percussion Rock Drilling Production Rates

4.5.3. Borehole Geophysics and Deviation Surveys

4.5.4. Use of Instrumented Packers

4.5.5. Water Pressure Testing

4.5.6. Stage Assignments

4.5.7. 15-Ft Gravity Grouting Zone Procedure

4.5.8. Pressure Grouting Procedure

4.5.9. Other Restrictions

5. Phase 1B Project Grout Mix Design

5.1. Grout Batch Plants

5.2. Quality Control and Testing Methods

5.2.1. Quality Control Results and Analyses

5.2.1.1. First 125 Marsh Funnel and Specific Gravity Tests

5.2.1.2. Remaining Marsh Funnel and Specific Gravity Tests

5.2.1.3. Bleed and Pressure Filtration Tests

5.2.1.4. Grout Set Time Tests

5.2.1.5. Unconfined Compressive Strength Tests

6. Phase 1B Construction Issues Noted

6.1. Misaligned Boreholes

6.2. Lost Tooling

7. Phase 1B Project Significant Findings – Soils

7.1. Embankment Fill

7.1.1. Embankment Cracks

7.1.2. Poor Recovery

7.2. Foundation Soil

7.2.1. Foundation Soil in Contact with the Left Haney Limestone

7.2.2. Foundation Soil in Contact with the Beech Creek Limestone

7.2.3. Foundation Soil in Contact with the Reelsville Limestone

7.2.3.1. Foundation Natural Gas

7.2.4. Foundation Soils in Contact with the Upper Right Abutment

8. Phase 1B Project Significant Findings - Bedrock

8.1. Beaver Bend Limestone

8.2. Sample Sandstone

8.2.1. Sample Sandstone Oil Encounters

8.3. Reelsville Limestone

8.4. Elwren Shale

8.5. Beech Creek Limestone

8.5.1. Beech Creek Limestone – Hole DXS2192 Unfiltered Exit

8.5.2. Beech Creek Limestone- DXT2187

8.5.3. Beech Creek Limestone – DXP2142 through DXP2182

8.5.4. Beech Creek Limestone – Vertical Holes Near Conduit

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8.5.5. Beech Creek Limestone – DXT2227 Through DXP2267

8.5.6. Beech Creek Limestone – DXS2232

8.5.7. Beech Creek Limestone – DXS2252

8.5.8. Beech Creek Limestone – UXT2157 through UXS2192

8.5.9. Beech Creek Limestone – Left Side

8.5.9.1. Beech Creek Limestone – UXS1906

8.6. Big Clifty Sandstone

8.7. Haney Limestone

8.7.1. Haney Limestone – Left Side Karst

8.7.1.1. Haney Limestone – Downstage Grouting

8.7.2. Haney Limestone – DXP1186

8.7.3. Haney Limestone – UXP1276

8.7.4. Haney Limestone – Right Side Grout Outbreaks

9. Phase 1B Project - Threshold Monitoring Piezometers

10. Phase 1B Project - Grouting Summary

10.1. Grouting Results

10.2. Grouting In Critical Areas

10.2.1. Grouting Results - Outliers

10.3. Closure Analysis

Appendix A – Daily Field Reports Appendix B – Instrumentation Evaluation Appendix C – Boring Logs and Lab Testing Appendix D – As-Builts Appendix E – Karst Summaries Appendix F – Phase 1A and Phase 1B Construction Documents Appendix G – ACT Final Report Appendix H – References iv

List of Figures

Figure 1: Project Location Figure 2: Geologic Cross Section of the Project Area (Profile Post Phase 1B) Figure 3: Generalized Stratigraphic Column Figure 4: Karst Map of Kentucky, Kentucky Geologic Society Figure 5: Overview of Phase 1 Dam Modifications Figure 6: Dam Layout Figure 7: Foundation Preparation Figure 8: Outlet Conduit Construction Figure 9: 1984 Apron Scour Figure 10: Location of 1980’s Retreat Channel Apron Remediation Figure 11: 2004 Apron Grouting Figure 12: Drainage Blanket and Drainage Well Configuration Figure 13: Right Abutment Special Treatment Zone; (2015 Profile Shown) Figure 14: Historic Grouting at Dam Centerline (1958 and 1960) Figure 15: Seepage from Weep Hole During 2011 Dewatering Figure 16: BCLS from Drilled Caissons Figure 17: As-Built Geometry for the Upstream Slope and Toe Trench at Elevation 495 ft.

Figure 18: Construction Sequence for Phase 1A Figure 19: Warm Seepage Observed at Sta. 18+20 Figure 20: Gas Bubbles Observed Upstream of Rough River Dam Figure 21: Phase 1B Base Contract Boreholes; (2015 profile shown) Figure 22: Phase 1B Modified Contract Boreholes; (2015 profile shown) Figure 23: Phase 1B Base and Modified Grouting Extents and Grout Zones Figure 24: Embankment Drilling Figure 25: Installation of Barrier Bag Figure 26: Grouting MSPS Annular Space Figure 27: Upper Interface Zone Grouting Figure 28: Water down-the-hole hammer Figure 29: Instrumented Packer Used at Rough River Dam Figure 30: “Supercube” Batch Plant #1 on the Left Abutment Figure 31: Screen Batching System Display Figure 32: On Site QC Laboratory Figure 33: Marsh Time and Specific Gravity of Mix A – Initial 125 Batches Figure 34: Marsh Time and Specific Gravity of Mix B – Initial 125 Batches Figure 35: Marsh Time and Specific Gravity of Mix A–- Project Figure 36: Marsh Time and Specific Gravity of Mix B – Project Figure 37: Marsh Time and Specific Gravity of Mix C – Project Figure 38: Marsh Time and Specific Gravity of Mix D – Project Figure 39: Marsh Time and Specific Gravity of Mix E – Project Figure 40: Representative Embankment Soils from DXP2026 (25-35 ft) Figure 41: Representative Embankment Soils from DXP2026 (65-75 ft) Figure 42: Profile View of Embankment Cracks; (2015 profile shown) Figure 43: Embankment Crack from UXT1891 Showing Mineralization Figure 44: Poor Recovery Located Below Embankment Cracks v

Figure 45: Extents and Typical Overburden Soils; (2015 profile shown) Figure 46: Summary of Laboratory Test Data Across the Valley Foundation Figure 47: Typical Karst and Clay Infill Encountered in the Haney Limestone Figure 48: Typical Overburden Soils in Contact With the Left BCLS Figure 49: Typical Overburden Soils in Contact With the right BCLS Figure 50: Typical Clay Infill Encountered in the Right BCLS – DXP2242A Figure 51: Sand from Borehole DXP2046 from 124 and 164 ft below the Dam Crest Figure 52: Sand from Borehole UXT2076 with a Cu Less than 2 Figure 53: Grout Takes Above The Reelsville Limestone Figure 54: Photo of UXP2056 From 125 to 135 ft Below Ground Surface Figure 55: Revised Upstream and Downstream Geologic Profiles Figure 56: Groutholes in the Reelsville Limestone Figure 57: Summary of Difficulties for Grouting the Reelsville Limestone Figure 58: Phase 1B Geologic Interpretation of the Right BCLS; (2017 profile shown) Figure 59: DXS2192 Soil/Bedrock Contact – Rock Socket Figure 60: DXS2192 Upper 15-ft Rock Core Figure 61: Grout Exiting Downstream of the Stilling Basin Figure 62: Grout Time History Plot Figure 63: Piezometric Responses to DXS2192 Grouting Figure 64: Cross Hole Communication below the Conduit Figure 65: DXP2162 Core and OATV Figure 66: Clay Filled Voids and Grout in Borehole DXP2242-A Figure 67: Hydrofracture of Soft Clay Infill at Gravity Pressure Figure 68: Recovered Samples in UXP2242-2 Figure 69: Recovered Samples in UXP2267-1 Figure 70: Grout in Embankment Figure 71: PZ-35 in Relation to DXS2232 and PZ-40 Figure 72: PZ-40 Reaction to Grouting Figure 73: Upstream PZ Reactions to Soil Drilling; (2016 profile shown) Figure 74: Upstream Piezometer Reactions to Soil Drilling Figure 75: Upstream Borings – Hole Communication and Grout Takes; (2015 profile shown) Figure 76: Summary of Left Upstream BCLS Figure 77: Summary of Left Downstream BCLS Figure 78: Typical Solution Features in the Left BCLS Figure 79: Locations of PZ-4, -44, -46, and -58, and UXS1908 Figure 80: Reactions of PZ-44 (Green) and PZ-46 (Brown) from 10JAN-25MAR17 Figure 81: Reactions for PZ-56 Figure 82: Upper Haney Limestone Outcrop Figure 83: Lower Haney Limestone Outcrop Figure 84: Identified Haney Karst Features Figure 85: Grout Exiting the Work Platform Figure 86: View of DXS1196 Recovered Samples from Sonic Drilling Figure 87: DXP1186 Pressure Volume Relationships Figure 88: Top of Bedrock Contact Elevations; (2015 profile shown) Figure 89: Grout Outbreak from DXP2582; (2015 profile shown) Figure 90: Grout Takes by Dam Station vi

Figure 91: Average Grout Take; Base Contract Versus Modification Boreholes Figure 92: Average Grout Takes by Stage Length in Zone 1 Figure 93: Average Grout Takes by Stage Length in Zone 3 Figure 94: Average Grout Takes by Stage Length in Zone 5 Figure 95: BCLS Grout Takes in Zone 5 per Stage; (2015 profile shown)

List of Tables

Table 1: Modified Upstream Slope Geometry Table 2: Gradation Test Requirements Table 3: Average Instantaneous Drilling Rates per Stratigraphy – Rock Table 4: Grout Mix Design and Testing Parameters Table 5: Grout Marsh Time (E- Flow Cone Time) of Initial 100% 125 QC Tests Min Table 6: Grout Specific Gravity of Initial 100% 125 QC Tests Min Table 7: Grout Marsh Time (E- Flow Cone Time) of All Project QC Tests Table 8: Grout Marsh Time (E- Flow Cone Time) of All Project QC Tests Table 9: Grout Bleeding and Pressure Filtration QC Tests Table 10: Grout Initial and Final Set Time QC Test Table 11: Grout UCS Test Results Table 12: Summary of Mis-drilled Boreholes Table 13: Vertical Embankment Crack Locations Table 14: Summary of Overburden Soils Above the Left BCLS Table 15: Summary of Overburden Soils Above the Right BCLS Table 16: Summary of Downstage Grouting Required Table 17: Summary of Grouting

1. Project Background Information

The project was designed and referenced to the COE Datum which is equivalent to the National Geodetic Vertical Datum of 1929 (NGVD29) and MSL. All elevations in this report are in NGVD29 unless otherwise referenced. To obtain NAVD88, 0.43 ft should be subtracted from any elevation provided in NGVD29.

The Phase 1B Project provided a better understanding of the subsurface environment at Rough River Dam. Profiles and depictions used to characterize the subsurface environment have evolved with this improved understanding. This has led to some inconsistencies between drawings and depictions generated from various eras. The current official geologic profile is shown in Figure 2. Whenever drawings and figures from the Phase 1B construction are used or referenced, the year of the geologic interpretation is also included. This clarification is provided to aid future readers and users of the report to better understand slight changes in some geologic depictions.

1.1. Project Location

Rough River Dam is located in Falls of Rough, Kentucky on the Rough River, and 89.3 miles above its confluence with the Green River. The project is located in south-central Kentucky, approximately 60 miles southwest of the U.S. Army Corps of Engineers (USACE) Louisville District Office (LRL) and approximately 20 miles northwest of Leitchfield, Kentucky (Figure 1).

Figure 1: Project Location.

1.2. Original Construction Authority

The flood protection plan for the Ohio River Basin, which included the construction of the Rough River Dam, was authorized by the Flood Control Act, approved 28 June 1938 (Public Law 761, 75th Congress, 3rd Session), revised under a report titled “Rough River and Tributaries, Kentucky” and published as House Document No. 535, 78th Congress, 2nd Session, 1944. The project was constructed under Contract No. DA-15-029-CIVENG-57-87 beginning in 1955 and was placed in full operation in December of 1960. The original authorization indicated that there are no local cooperation requirements. Because the project was completed several years before cost-sharing requirements were established under Section 2 of the Federal Water Project Act approved July 9, 1965 (Public Law No. 89-72), cost-sharing responsibility on the part of the State of Kentucky or any other non-Federal public entity is null and void. Water supply was authorized per the Water Supply Act of 1958 (43 U.S. Code § 390b). Water supply agreements are in place with Leitchfield, KY (120 acre-ft) and Grayson County, KY (260 acre-ft).

1.3. Project Geology

Rough River Dam is located in the northwestern portion of the Mississippian Plateau in Kentucky. The Rough River valley is a relatively narrow entrenchment cut into rock of the lower and middle Chester Series of Mississippian age that dip down to the southwest at a rate of about 85 ft per mile. As a result, the beds dip approximately 2 to 3 degrees downstream and towards the left abutment (west). The rocks of early Chester age were deposited on a shallow-marine shelf across western and west-central Kentucky. The normal shelf deposition of skeletal carbonates was periodically interrupted by deposition of deltaic and littoral sandstones and shales which prograde from the north and northeast. This depositional environment resulted in the alternating sandstone, shale, and limestone sequences present at the project site.

Limestone formations in this geology are karstic and prone to weathering and solutioning along joints and bedding planes. The thickness and contact location of the limestone formations are quite predictable across the site except where karst is encountered. The shale layers within the Big Clifty Sandstone have some variation and undulation which cause the layers to thicken and thin locally. In general, the sandstone, shale, and inter-bedded units within the Big Clifty fall into this category.

There are no faults documented at the dam site, but the Rough Creek Graben, a major regional tectonic feature, is located approximately seven miles south of the dam, and the Locust Hill Fault is approximately 1.5 miles southeast of the dam and trends approximately sub-parallel to the dam axis.

The geologic profile at the dam site is summarized in Figure 2 and Figure 3.

Figure 2: Geologic Cross Section of the Project Area (Profile Post Phase 1B).

Figure 3: Generalized Stratigraphic Column.

1.3.1. Karst Potential

The United States Geologic Survey (USGS) defines Karst as “A terrain, generally underlain by limestone or dolomite, in which the topography is chiefly formed by the dissolving of bedrock which may be characterized by sinkholes, sinking streams, closed depressions, subterranean drainage, and caves.” Additionally, a karst aquifer has fast and turbulent flow of groundwater in secondary porosity features such as bedding planes, small conduits, and in tertiary caves. The Rough River Dam project location is cited in an area of Moderate Karst Potential in accordance with the USGS Karst Map of Kentucky (Figure 4). Intense karst is known to exist along the dam abutments due to the incised nature of the river valley that subjected exposed limestone outcrops to weathering. Karst potential is lower where cap rock protected the limestone from weathering.

Figure 4: Karst Map of Kentucky, Kentucky Geologic Society.

1.4. Purpose of the Rough River Dam Safety Modification

The intent of the combined phases of the Rough River Dam Safety Modification Project are to reduce risks for dam failure to below tolerable risk guidelines. A Dam Safety Modification Report (DSMR) was completed in 2012 in accordance with ER 1110-2-1156 (dated 31 March 2014).

The DSMR recommended executing a series of contracts to perform foundation grouting, installation of a cutoff wall, conducting conduit grouting, and installing a downstream filter. The DSMR was endorsed by DSOG with Phase 1 of the project approved by the Assistant Secretary of the Army for Civil Works, ASA(CW) on 7 March 2013.

A summary of Phase 1 construction is shown in Figure 5 below. The first contract, referred to as Phase 1A Project, required relocating Highway 79 to the upstream crest of the dam to allow the passage of traffic during future phases of the dam safety modification project. The Phase 1B Project required installation of two partial exploratory grout lines to provide slurry control in advance of the future Phase 2 Project. The Phase 2 Project originally required additional slurry control grouting, installation of a cut-off wall across the dam foundation extending over and around the existing outlet conduit, grouting from below the conduit, and a downstream filter.

Once Phase 1B grouting confirmed the severity of the foundation conditions, the Phase 1B contract was modified to perform most of the anticipated Phase 2 grouting as part of the Phase 1B Project. In 2018, the Phase 2 Project was again revised to consist of a new outlet works and installation of a full-length cutoff wall to extend fully across the dam foundation and sever the existing outlet conduit.

This report documents the as-built geotechnical and geological conditions observed, notable events, and issues encountered during construction of the Phase 1 Project in accordance with ER 1110-1-1901 Engineering and Design, Construction Project Geotechnical and Materials Completion Report (dated 28 February 2017).

Figure 5: Overview of Phase 1 Dam Modifications.

1.5. Risk Driving Failure Modes

A Potential Failure Mode Analysis (PFMA) was completed in 2008 followed by an Expert Opinion Elicitation (EOE) in 2011 which indicated the foundation for Rough River Dam posed unacceptable risks from internal erosion related failure modes. At the time of Phase 1B construction, the dam was assigned a Dam Safety Action Classification (DSAC) Classification 2 (High Urgency) ranking based on the following Potential Failure Modes (PFM):

14 - Concentrated leak erosion along the conduit

21A - Concentrated leak erosion into and along the Haney Limestone on the right abutment

22 - Concentrated leak erosion into and along the Haney Limestone on the left abutment

23A - Concentrated leak erosion of the valley soil along the BCLS

23C - Erosion into the untreated valley center and lower left abutment BCLS

Additional risk assessments were completed in 2016 and 2017 as grouting was nearing completion. These risk assessments indicated that the two primary risk driving failure modes were PFM 22 Internal Migration (stoping) into and along the left abutment Haney Limestone, and PFM 23A scour (concentrated leak erosion (CLE)) into the right abutment BCLS. These karstic formations are present on both sides of the incised valley.

A Semi-Quantitative Risk Assessment (SQRA) was performed between 2022 and 2023 to re-evaluate the existing condition of the dam. The draft Rough River Dam Construction Materials and Foundation Completion Report was utilized as a resource during the SQRA. The SQRA indicated the foundation for Rough River Dam posed unacceptable risks from internal erosion related failure modes. The dam was assigned a DSAC 2 (High Urgency) ranking based on the following PFM’s:

PFM 1: Overtopping

PFM 4: CLE along the right side of the conduit

PFM 5: CLE into/along defects in the foundation rock (right side BCLS)

PFM 17: Internal migration (stoping) into defects in untreated Haney Limestone at left abutment

PFM 22: Backwards Erosion and Piping (BEP) through foundation soils in the original river channel

1.6. Existing Project Overview

A layout of the dam and appurtenant features is depicted in Figure 6. A detailed synopsis of the project features and construction history are officially documented in the final 2023 SQRA.

Figure 6: Dam Layout.

1.6.1. Dam Embankment

The dam consists of a 1,590-ft long, earth-filled embankment having a maximum height of 130 ft above the streambed with a 30-ft crest width. The maximum width at the dam base is 819 ft.

The dam was constructed in the late 1950s and is composed of compacted clay fill founded on undisturbed, natural alluvial soils. Seepage cutoff features were not constructed through the alluvial soils or foundation bedrock across the river valley. Internal drainage of the embankment is provided by a 10-ft thick, 1.0H:2.0V inclined drain starting at elevation 495 ft, as well as a 2-ft thick, basal filter blanket extending to the downstream toe of the dam. An upstream filter blanket was installed above the alluvial soils between the historic river channel and the outlet conduit.

Along the right abutment, the structure is founded on limestone, in which a special treatment zone was slush grouted and treated with dental concrete and concrete bulkheads at several overhangs and ledges. A volume of 1,141,400 cubic yards of earth and rock material was required for the original embankment construction. In addition to the embankment and drainage features, there is a downstream rock toe comprised of shot limestone, having a top elevation of 460 ft and an upstream slope of 1.0H:1.0V. Three relief wells were installed during original construction at the downstream toe in the left bank foundation to reduce uplift pressures and to control water movement through the soil. The original upstream face has 4 ft of dumped riprap stone protection underlain by 12 inches of spalls and choker material. The original crest elevation was at 551 ft but was raised to 554 feet before the dam was placed into service due to freeboard inadequacy. The dam was raised to its final elevation of 555.5 ft as a result of the Dam Safety Assurance Project (DSAP) discussed in section 2.3. The DSAP also installed a 4-ft tall concrete parapet wall to extend the level of protection for wave-wash up to elevation 559.5 ft.

1.6.2. Outlet Works

The outlet works is located at the base of the right abutment and founded predominately on the karstic BCLS. The outlet conduit can provide a discharge capacity of 3,000 cubic ft per second (cfs) at summer pool (elevation 495 ft), and 5,580 cfs at spillway crest level (elevation 524 ft).

The dry-type control tower has three hydraulically operated 4.75-ft by 9.5-ft vertical lift slide gates (invert elevation of 430 ft) and two 24-inch low-flow bypass pipes (invert elevation of 450 ft), discharging to a 1548 ft long, 12-ft by 12-ft, semi-elliptical concrete conduit with a slope of

0.2 percent. There are five seepage collars along the outlet conduit spaced every 60 ft. The middle seepage collar is located approximately 8 ft upstream of the dam centerline. The conduit drains into an energy dissipating stilling basin and concrete apron that directs the flow to a riprap-lined retreat channel. The stilling basin was originally a 52-ft-long dispersal bucket and has had several remedial repairs. In 2007, the end sill and apron were removed and extended increasing the stilling basin length to 139 ft with the addition of five baffle blocks. A 144-ft, simple-span, steel truss service bridge extends from the control tower to a roadway on the right abutment.

1.6.3. Emergency Spillway

A 65-ft wide, 1,800-ft long uncontrolled, unlined, open rock cut emergency spillway was excavated on a 1H:4V slope roughly 33 ft deep into rock. Water enters the spillway through a natural drainage valley in the left abutment and flows over a 6-ft-wide concrete sill with a crest elevation of 524 ft, installed for grade protection, after which the spillway slopes downstream at

1.5 percent and spills approximately 400 ft beyond the left abutment. The Contractor overshot the rock leaving the ragged appearance in the walls and floor. Overburden was excavated with 2H:1V side slopes. The spillway is crossed by Kentucky Highway 79 using a single span, simply supported, steel multi-girder bridge with a cast-in-place concrete deck that extends approximately 36 ft above the spillway floor. The spillway side slopes are lined only at the bridge location to support the bridge structure.

2. Construction and Modification History

Two contracts were awarded to construct the Rough River Dam project. A contract for the tower and outlet works was awarded in 1955. A contract for construction of the dam and spillway was awarded in May 1957 and proceeded concurrently with construction of the outlet works to expedite completion of the project. The embankment was completed in December 1958, and the project was placed in limited operation in October 1959 after the dam was raised. The dam was placed into full operation in December 1960 after foundation grouting in the abutments was completed. Design of the project features was aided by pre-construction and construction field explorations. Key construction items pertinent to the Phase 1 Project include the original outlet works construction, right abutment dental treatment (Special Treatment Zone), natural alluvium and overburden left in place, and abutment grouting. A summary of key construction information is contained in Figure 7.

Figure 7: Foundation Preparation.

2.1. Outlet Works Construction

Construction of the outlet works began in November 1955 and was completed in January 1958.

The original outlet works construction consisted of the control tower monolith, two transition monoliths, 27 conduit monoliths, and the outlet bucket structure. Most of the rock excavation was performed by drilling and blasting complimented by mechanical removal. The tower and approximately two-thirds of the upstream portion of the conduit was founded on the BCLS, while the stilling basin and remaining portion of the conduit was founded on the Big Clifty Lower Shale, which is underlain by the BCLS. During the conduit trench excavation, the limestone was documented to contain a significant number of karstic features. These features were several feet in width and ran sub-parallel to the conduit exiting the excavation toward the left (valley side). Where discovered within the excavation, karst features were dentally treated with concrete. Geology notes indicate that karst features exited the excavation to the left near monolith 9 and re-entered the excavation at monolith 15. Karst features exiting the excavation were not treated.

The karst features encountered at the base of the tower and conduit excavations were cleaned with an air-water jet and dentally treated. The prepared foundation received a lean concrete mud mat between 0.5 and 2 ft thick. The shale foundation was left in place for the downstream third of the alignment. The shale was covered with a 3-inch-thick concrete seal coat prior to placing conduit concrete. The conduit concrete was then placed in approximately 18-inch layers and consolidated with vibrators. The conduit itself ranges from 12 to 18 inches thick and is considered structurally deficient by modern design standards. The left side of the conduit trench was excavated at a 2H:1V slope into native alluvium soil. The right side of the excavation was excavated 20 to 30 ft into bedrock to achieve the 1H:4V slope (Figure 8).

Figure 8: Outlet Conduit Construction.

2.1.1. Stilling Basin Repairs

Following completion of the dam in December 1960, the paved outlet channel endured extensive erosion damage requiring multiple dewaterings and repairs. Damage to the stilling basin apron and foundation scour in the Lower Big Clifty Shale was observed in 1979, 1984, 1989, 1991, and 1992. Each scour hole was typically cleaned and backfilled with concrete. In June 1984 (Figure 9), a section of the concrete apron immediately downstream from the end sill was damaged. An 18 ft by 15 ft section of concrete was missing and the rock below the stilling basin was eroded to a depth of approximately 8 ft beneath the adjacent slabs. The void was filled with 88 cy of concrete. In 2003, undermining of the concrete apron near the right stilling basin wall was observed in the same location as the 1979 and 1984 repairs. In 2004 a total of 50 cy of grout were injected under the paved apron thought to partially fill voids in direct contact with the stilling basin weep holes. The scour hole was treated with a 5 ft deep concrete turndown key at the downstream edge of the apron. These continuous erosion issues removed portions of the Lower Big Clifty Shale exposing the BCLS in some locations. Additional details for historic stilling basin repairs can be found in the 2023 Rough River SQRA Report. A plan view showing the location of the 1980’s repairs is shown in Figure 10.

Figure 9: 1984 Apron Scour.

Figure 10: Location of 1980’s Retreat Channel Apron Remediation.

Figure 11: 2004 Apron Grouting.

2.2. Dam Construction

A comprehensive discussion of construction history is included in the 2023 Rough River SQRA Report. The following sections discussing construction history are those most applicable to the Phase 1 Project.

2.2.1. Native Overburden and Foundation Drains

Construction of the dam embankment began in May 1957 and was completed in December 1958. There was no core trench or foundation grouting between the conduit and lower left abutment. Organics were stripped from the foundation soils and a 6-ft deep inspection trench was installed but it did not extend down to bedrock. The foundation soils along the right bank of the original river channel (Station 21+00 to 22+45) had a maximum depth of about 30 ft with no natural drainage stratum. The original dam designers were concerned with embankment stability associated with the poorly draining soils; therefore, the design incorporated a 2 ft thick filter blanket extending to within 50 ft of the dam centerline. Downstream of the dam centerline an inclined filter and 2 ft thick filter blanket was draped over the foundation soils across the downstream toe of the dam and was also extended to within 50 ft of the dam centerline. A series of 368 sand drainage wells were advanced between the historic channel and outlet conduit (141 downstream and 227 upstream) in these areas. The sand drainage wells, 12 inches in diameter, were advanced to the top of bedrock on 13-ft centers (Figure 12). Filter-graded sands were placed via tremie methods.

Left of the river channel, the dam is founded on 40 to 50 ft of lean clay, silts, and sands. During original design and construction, material to the left of the historic river channel was believed to be desirable for embankment construction because it was naturally draining. The material was left in place and three relief wells were installed at the downstream left toe to control the seepage and reduce uplift pressures. RW-1 and WP-1 are noted to reflect artesian pressures at seasonal pool and above with flow generally less than 1 gallon per minute.

Figure 12: Drainage Blanket and Drainage Well Configuration.

2.2.2. Right Abutment Special Treatment Zone

Bedrock on the upper right abutment was treated during original construction with reinforced concrete bulkheads and dental treatment in the form of slush grout to provide a suitable surface to place compacted fill against. This area is referred to as the “Special Treatment Zone” (Figure 13). The slush grouting in this area was only intended to treat the rock surface and did not extend to joints or voids below the surface.

2.2.3. 1958 and 1960 Historic Grouting

Prior to the Phase 1B Project, the dam foundation had two previous grouting efforts. During dam construction in 1958, foundation grouting initially consisted of a single-line grout curtain in the upper abutments. Grouting on the right abutment extended to a bottom elevation of 435 ft, in the Big Clifty Lower Shale, while grouting on the left abutment extended to a bottom elevation of 475 ft, into the Big Clifty Sandstone. From the limited information available about the grouting, it appears that most of the grout takes were associated with vertical stress relief fractures and blast-damaged bedrock, which was encountered at or below elevation 450 ft (Big Clifty interbedded sandstone and shale and the lower shale formation). These stress relief fractures were only observed on the right abutment and when the Big Clifty formation was at or near the working surface. In 1960, additional grouting was performed on the abutments following the discovery of a large cave during excavation of the downstream access road on the left abutment. The subsequent foundation grouting was confined to the upper abutments, terminating at elevation 475 ft in the left abutment and elevation of 485 ft in the right abutment.

Figure 13: Right Abutment Special Treatment Zone; (2015 Profile Shown).

Figure 14: Historic Grouting at Dam Centerline (1958 and 1960).

2.2.4. 1958 Dam Raise

After construction was substantially complete, the embankment was raised from elevation 551 ft to 554 ft in November 1958 based on concerns for available freeboard after a high pool. The project was placed in limited operation in October 1959 and into full operation in December 1960 after the dam raise and grouting was completed.

2.3. Dam Safety Assurance Project (DSAP)

A Dam Safety Assurance Project was completed between 2006 and 2008 to address multiple recurring dam safety issues at the project. The plan included three major construction efforts to address hydraulic deficiencies in the stilling basin, a freeboard deficiency, and to repair downstream sinkholes that developed in 2002 and 2003 due to filter compatibility issues between the dam embankment and the dumped rock toe. The first component of the project constructed a slurry wall to isolate the deepest portion of the rock toe from the dam embankment across the valley center. A two-stage filter was constructed to the right and left of the slurry wall along shallow areas of the lower abutment. Second, the dam crest was raised to elevation 555.5 ft and a concrete parapet wall was added to meet the required protection for wave wash during the probable maximum flood (PMF). The parapet wall adds protection up to elevation 559.5 ft. Finally, the undersized stilling basin was lengthened to better dissipate turbulent discharges and prevent continued erosion and damage. During the stilling basin repair well-developed karst features were exposed in the BCLS. Comprehensive details for each issue and repair can be found in the 2023 Rough River SQRA Report.

2.4. 2011 Record Pool and 2012 Stilling Basin Repairs

In April-May 2011, historic rainfall resulted in a record pool, spillway flow, and high tail water levels at Rough River Dam. High outflows resulted in damage to the left training wall of the stilling basin. During dewatering for the subsequent stilling basin inspection, a weep hole near the left training wall was noted to have high amounts of seepage (Figure 15). The flow was enough to break the water surface through 18 inches of water. Design drawings confirm the drain system was simply placed on top of rock with penetrations into the stilling basin floor and behind the training walls. The flow was sufficient to transport coarse aggregate from the foundation.

In 2012, the stilling basing training wall was repaired by installing a caisson buttress behind the left stilling basin wall. The caissons were advanced through the BCLS and Elwren Shale eventually socketed 2 ft into the Reelsville Limestone. The recovered BCLS was noted to be highly karstic with large solution features and joints capable of producing high velocity flows of water (Figure 16). Additional details of the Pool of Record and subsequent stilling basin and training wall repairs are included in the 2023 Rough River SQRA Report.

Figure 15: Seepage from Weep Hole During 2011 Dewatering.

Figure 16: BCLS from Drilled Caissons.

3. Phase 1A: State Highway 79 Road Relocation Contract

3.1. Project Overview

In spring of 2014, Contract W912QR-09-D-0050 was awarded to Future-Net Group LLC (Small Business 8-A) to relocate KY Highway 79 to the upstream face of the dam to serve as a traffic platform for the Phase 1B and Phase 2 Projects. The road relocation required altering the upstream slope of the dam between elevations 495 ft to 550 ft to a 2H:1V slope. The slope modification was achieved by constructing a rock trench toe at elevation 495 ft. The modified slope provides a 30 ft wide roadway surface at elevation 550 ft. The overall project placed 36,414 CY (65.5 tons) of rock fill covered by approximately 14,758 CY (22 tons) of Kentucky Transportation Cabinet (KYTC) Class III riprap on the upstream dam face. Electric, communications, and other utilities are located below the center of the east bound lane below the pavement. Traffic is still currently routed along the relocated Highway 79. A summary of the slope post Phase 1A modification can be found in Table 1.

Table 1: Modified Upstream Slope Geometry.

Upstream Downstream

Slope Elevation (feet MSL)

Slope Elevation

(feet MSL)

2.0H:1.0V 554-550 2.0H:1.0V 554-539

2.0H:1.0V 550-495 2.5H:1.0V 539-531

3.0H:1.0V 495-471 3.0H:1.0V 531-base

4.0H:1.0V 471-base

3.2. Key Personnel

Project Manager: Barry Schuler P.E., CELRL-PM-C, LRL

Lead Engineer: Will Ailstock P.E., CELRL-EDT-G, LRL

Designer/Field Engineer: Steven Shifflett, P.E., CELRL-EDT-G, LRL

Resident Engineer: Tom McQueary P.E., CELRL-CD-K, LRL

Government Quality Assurance Personnel: Adam Scheiter, CELRL-CDC-K, LRL

Contractor: Future-Net Group LLC

Major Subcontractors: Earthwork Subcontractor – Philips Brothers Construction Company;

Asphalt Paving Subcontractor and Quarry provider – Scotty’s Contracting and Paving (Leitchfield, KY)

Major Coordinated Efforts: USACE Dam Safety and USGS installed fully grouted vibrating wire transducers in manholes set along the offset Highway 79 Alignment. These activities were completed on a Nashville District AE Task Order through the Louisville District Engineering Division outside of the Phase 1A contract.

Key construction records for Phase 1A can be found in Appendix F.

3.3. Slope Construction Methodology

Philips Brothers Construction Company was the earthwork subcontractor. A Komatsu D65 bulldozer was used to cut a horizontal bench approximately 8 ft wide across the upstream face of the dam near elevation 498 ft. The rock toe trench was excavated down to elevation 495 ft using a Komatsu PC-300 excavator using a 4 ft wide bucket. The trench was excavated 5 ft wide and approximately 3 ft deep. KYTC Class III Channel Lining (riprap) was end dumped from articulated trucks and tracked into place utilizing a Komatsu D65 bulldozer for the entire dam width. Moving up the slope, subsequent 8-10 ft wide horizontal benches were cut into the dam face using a bulldozer. The height of the benches did not exceed 4 ft and the dam embankment was not exposed for any lift. Tri-axle trucks were used to haul rock fill material to be placed on each bench in compacted 2 ft thick lifts. Rock fill was compacted using a 10-ton smooth drum vibratory roller making 5 passes in vibratory mode with one static pass. The Contractor advanced both rock fill and riprap layers simultaneously as each bench was completed. The rock fill was placed approximately 4 to 10 ft higher than the riprap. Riprap was then dumped on the rock fill from tri-axles and placed via excavator onto the final dam face at the design 30-inch thickness. These methods continued up to elevation 550 ft. Special considerations for raising piezometer standpipes and placing rock fill around the instruments were supervised by USACE.

Manholes were placed at locations of existing instrumentation on the upstream slope. Additional empty manholes were set for a future piezometer installation planned for 2015. Two weight/volume conversion checks occurred during construction by surveying placed rock fill of known weight in small excavations of known volume. The contractor completed a final survey of the riprap on the dam for the final verification of the material volume/weight placed.

3.4. Road Construction Methodology

The pavement section was approved by KYTC. KYTC No. 2 stone was placed directly on top of the rock fill to a thickness of 5 inches. This stone was compacted in compliance with the specification with 5 passes of a 10-ton vibratory roller. Above the No. 2 stone, 4 inches of KYTC crushed stone base was placed and then compacted to 95% of the maximum dry density per ASTM D1557. Non-woven geotextile fabric was not required between the placed rock fill. The No. 2 stone passed particle retention requirements for the stone gradations. Non-woven geotextile fabric was used as a separation layer between the pavement section and the rip rap slope protection which extended flush to the top of asphalt. Asphalt construction was completed by Scotty’s Contracting and Paving. Two asphalt base course layers totaling 6 inches in thickness were constructed with a 1.5-inch-thick layer of asphalt surface. Scotty’s completed the mainline pavement in accordance with specification requirements before Future Net Group defaulted on the contract. Road transitions from the old to the new roadway and the actual traffic shift was removed from the Phase 1A contract and added to the Phase 1B contract. This work was completed by ACT, Inc., who also utilized Scotty’s Contracting and Paving for asphalt paving. Figure 17 and Figure 18 show the plans and photos for the upstream crest construction.

Figure 17: As-Built Geometry for the Upstream Slope and Toe Trench at Elevation 495 ft.

Figure 18: Construction Sequence for Phase 1A.

3.5. Materials

The materials used for rock fill and riprap came from Scotty’s Quarry in Leitchfield, KY. The riprap is KYTC Class III Channel Lining and met the requirements of specification 35 31 19 Rock Fill and Riprap Construction and the minimum requirements of KYTC Standard…