W912P5-16-B-0004-DDR-Am3.pdf

Kentucky Lock Addition

Downstream Cofferdam

Design Documentation Report

This Design Documentation Report (DDR) is provided for information only. All aspects of the plans and specifications take precedence over the content of the DDR.

DESIGN OF DOWNSTREAM COFFERDAM

KENTUCKY LOCK

TENNESSEE RIVER

DESIGN DOCUMENTATION REPORT

FINAL DESIGN

MAY 1, 2016 Page i

TABLE OF CONTENTS

1. PROJECT DESCRIPTION

1.1 STUDY AUTHORITY AND MANAGEMENT

1.2 PROJECT DESCRIPTION

1.2.a Existing Project Features 1.2.b Proposed Changes 1.2.c Previous Cofferdam Studies

1.3 DOWNSTREAM COFFERDAM ALTERNATIVE

2. STRUCTURAL DESIGN CRITERIA

2.1. REFERENCES

2.1.a. U.S. Army Corps of Engineers Publications 2.1.b. Technical Publications

2.2 PERTINENT PROJECT DATA

3. FOUNDATION CONDITIONS AND TREATMENT

3.1 GENERALIZED SUBSURFACE CONDITIONS

3.1.a Overburden and Residuum 3.1.b Bedrock 3.1.c Geotechnical Properties

3.2 PREPARATORY EXCAVATION

3.3 SUBGRADE PREPARATION

3.4 GROUT CURTAINS AND OTHER SPECIALTY WORK

3.4.a Cofferdam Grout Curtain 3.4.b Other Specialty Work

4. DOWNSTREAM COFFERDAM

4.1 OVERVIEW

4.1.a General Description

4.2 SHEET PILE COFFERDAM

4.2.a General 4.2.b Design Loads 4.2.c Design Loading Conditions 4.2.d Design Methodology 4.2.e Design Summary

4.3 FLOODING FACILITY

4.3.a General 4.3.b. Design Loads 4.3.c. Design Loading Conditions 4.3.d. Design Methodology 4.3.e. Design Summary

4.4 BRIDGE

4.4.a General 4.4.b Design Loads 4.4.c Design Methodology 4.4.d Design Summary

4.5 PROTECTION WALL

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4.5.a General 4.5.b. Design Loads 4.5.c. Design Loading Conditions 4.5.d. Design Methodology 4.5.e. Design Summary

5. FLOAT-IN SEGMENT COFFERDAM

5.1 GENERAL DESCRIPTION

5.2 DESIGN FEATURES

5.3 MATERIAL PROPERTIES

5.3.a Reinforced Concrete 5.3.b Steel Structures 5.3.c Tremie Concrete 5.3.d Controlled Low Strength Material 5.3.e Grout Bag and Grout Infill

5.4 DESIGN LOADING CONDITIONS

5.4.a Loads 5.4.b Load Case Descriptions 5.4.c Load Combinations

5.5 DESIGN METHODOLOGY

5.6 DESIGN SUMMARY

5.7 CONSTRUCTION CONSIDERATIONS

5.7.a Casting Site for Float-In Cofferdam Segments 5.7.b Launch of Float-In Cofferdam Segments 5.7.c Stability of the Float-In Cofferdam Segments 5.7.d Positioning and Set-Down of Float-In Cofferdam Segment 5.7.e Cofferdam Infill 5.7.f Closure Existing Lock Channel During Float-In Cofferdam Construction

6. GUARD CELLS

6.1 GENERAL

6.2 DESIGN LOADS

6.3 DESIGN LOADING CONDITIONS

6.3.a Concrete Filled Cell 6.3.b Granular Filled Cell

6.4 DESIGN METHODOLOGY

6.4.a Concrete Filled Cell 6.4.b Granular Filled Cell

6.5 DESIGN SUMMARY

6.5.a Concrete Filled Cell 6.5.b Granular Filled Cell

7. INSTRUMENTATION

7.1 BLAST MONITORING

7.2 COFFERDAM

8. DEWATERING PLAN

9. POWER AND LIGHTING

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9.1 DRAWINGS

9.2 POWER SOURCE

9.3 COFFERDAM POWER

9.3.a Dewatering Wells Pump Starters 9.3.b Navigation Lights 9.3.c Roadway Lighting 9.3.d Instrumentation 9.3.e Slide Gates 9.3.f Enclosure Heater

9.4 DISTRIBUTION SYSTEM

9.5 GROUNDING & BONDING

9.6 TOTAL ELECTRICAL DEMAND

10. MCACES COST ESTIMATE

10.1 BACKGROUND

10.2 DETAILED ESTIMATE PARAMETERS

11. CONSTRUCTION SCHEDULE

11.1 GENERAL

11.2 METHODOLOGY

11.3 CONSTRAINTS

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REPORT ATTACHMENTS

CONSTRUCTION SCHEDULE

ENGINEERING CONSIDERATION FOR FIELD PERSONNEL REPORT

MINUTES FROM NAVIGATION IMPACTS COORDINATION MEETING

LIST OF APPENDICES

APPENDIX A DRAWINGS AND SPECIFICATIONS

APPENDIX B FOUNDATION DESIGN CALCULATIONS

APPENDIX C CELLULAR COFFERDAM DESIGN CALCULATIONS

APPENDIX D GUARD CELLS DESIGN CALCULATIONS (NOT INCLUDED)

CALCULATIONS NOT REVISED SINCE PHASE 1.

APPENDIX E FLOAT-IN SEGMENT DESIGN CALCULATIONS

APPENDIX F INSTRUMENTATION PRODUCT DATA

APPENDIX G POWER AND LIGHTING DESIGN

APPENDIX H SCOPE OF SERVICE

APPENDIX I ITR/QC CERTIFICATION AND REVIEW

APPENDIX J PROJECT CORRESPONDENCE

APPENDIX K MCACES COST ESTIMATE

APPENDIX L QUANTITIES AND BACKUP MATERIAL

APPENDIX M THERMAL ANALYSIS

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1. PROJECT DESCRIPTION

1.1 STUDY AUTHORITY AND MANAGEMENT

The Tennessee Valley Authority (TVA) Act of 1933, as amended, authorized the TVA to “construct such dams and reservoirs in the Tennessee River and its tributaries as well as provide a 9-foot channel in the said river and maintain a water supply for the same, from Knoxville to its mouth, and will best serve to promote navigation on the Tennessee River and its tributaries and control destructive flood waters in the Tennessee and Mississippi River drainage basins.”

Achievement of this objective required that a dam or a series of dams be constructed on the lower Tennessee River. The initial appropriation by Congress for the original Kentucky Project was given on May 28, 1937. The TVA Board of Directors authorized the project on December 20, 1937. The Kentucky project includes Kentucky Dam and Kentucky Lock.

The Kentucky Locks Addition Project was authorized by a resolution adopted by the Committee on Public Works of the U.S. Senate dated October 2, 1972, and a resolution adopted September 9, 1982 by the U.S. Senate Committee on the Environment and Public Works. The U.S. Army Corps of Engineers (USACE), Nashville District, is managing the project. Several of the lock design studies Design Memorandums have been completed by Nashville District and various engineering consulting firms. Several studies on the downstream cofferdam study have been completed and are listed in Section 1.2.c, Previous Cofferdam Studies. The final design, plans and specifications are based primarily on the Phase 2 Final Design by a joint venture design team of Bergmann Associates and Ben C. Gerwick with D’Appolonia Engineering. This Phase 2 included preparation to the final design and final contract documents for the downstream cofferdam. It was performed under Contract Number DACW62-02-D-0005, Delivery Order Number 1. Previous work was performed under Contract Number DACW62-99-D-0020, Delivery Order Number 5 and 6. The scope of services for this work is provided in Appendix H.

Funding for the construction of the downstream cofferdam was authorized in fiscal year 2016.

With the allocation of funding for construction, USACE Nashville District began the final preparation of plans and specifications in the spring of 2015. Revisions, clarifications, or additional design since the completion of the Phase 2 Final Design are documented in this DDR in italics within the original sections.

For the final plans and specifications, USACE Nashville District has decided to change to a non-prescriptive construction method for the concrete portion of the cofferdam. Therefore, the float-in details for the concrete cofferdam have been removed. The plans for the concrete portion of the cofferdam now show the basic concrete outline, final reinforcement requirements, and final monolith joint configuration. Information regarding the original float-in design of the concrete portion of the cofferdam has been retained in the DDR, but are not longer applicable, except that the design for strength and stability of the wall monoliths, foundation preparation, founding elevation, monolith dimensions and monolith joint locations have not been changed from the original Phase 2 design. The contractor awarded the contract will submit the proposed method of construction for approval.

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1.2 PROJECT DESCRIPTION

1.2.a Existing Project Features

The Kentucky Lock Project is located on the Tennessee River at river mile 22.4 and is 67.4 river miles above the mouth of the Ohio River at Cairo, IL. The navigation lock is located on the right bank or east side of the river. The upper pool of the dam extends upstream for a distance of 184 miles to the Pickwick Landing Locks and Dam at river mile 206.7.

Construction of the Kentucky project commenced on July 1, 1938 and the lock was opened to navigation September 12, 1944. The main features of the dam consists of a 5,860-foot long west embankment retained at the spillway terminus by a concrete retaining wall; a 1,176-foot long 24-gate spillway; a 478-foot long five-unit powerhouse and service bay; a 732-foot embankment between the service bay and lock; a 110-foot wide navigation lock; and a 200-foot long east embankment. The total length of the project, from abutment to abutment, is approximately 8,422 feet. The switchyard structure is located downstream from the earth embankment between the lock and service bay. The Paducah and Louisville Railroad and United States Highway No.

62/641 currently cross the Tennessee River over the crest of the dam.

Since the completion of the Phase 2 design, the Paducah and Louisville Railroad and United States Highway No. 62/641 bridges have been relocated to new structures downstream of the existing and future lock. The original structures over the existing lock chamber are scheduled for demolition in future new lock addition construction contracts.

1.2.b Proposed Changes

The USACE Nashville District has identified the Kentucky Lock as a cause of major delays for the shipping industry on the Tennessee and Cumberland Rivers. The existing lock is 600 ft long;

requiring the standard 1,200 ft tows and barges to be broken for locking. Plans initially prepared by the TVA (owners of the lock and dam) and further developed by the USACE Nashville District (operators of the lock) in a feasibility level study recommended the addition of a 1,200 ft lock landward of the existing lock to avert navigation delays.

This Phase 2 scope of work presents the 90% complete level design of the downstream cofferdam for the new navigation lock, including the design layout, foundation treatment, blasting requirement, instrumentation, power and lighting, estimated quantities, construction cost estimate and construction schedule.

1.2.c Previous Cofferdam Studies

Design development of the proposed cofferdam alternatives founded on rock is based upon the results of previous studies of cofferdam layouts and types. Results of these previous studies are presented in the following documents:

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MAY 1, 2016 Page 3

1. “Kentucky Lock Addition, Analysis and Investigation For the Value Engineering Downstream Cofferdam Study, Tennessee River”, Final Report, Bergmann Associates and Ben C. Gerwick, Inc, January 24, 2000.

2. “Kentucky Lock Addition, Design Memorandum, Downstream Cofferdam”, Final Report, Volumes 1 and 2, Harza Engineering Company in association with The Glosten Associates, March 2000.

3. “Upstream Cofferdam, Kentucky Lock Addition Project”, 95% Submittal, Black and Veatch, March 17, 2000.

4. “Upstream Cofferdam, Kentucky Locks Addition Project”, 70% Complete Plans and

Specification, Black and Veatch, September 22, 2000, including the sheet pile driving test records.

5. “Kentucky Lock Addition, Downstream Cofferdam Phase 1 Design Documentation –

Revised Submittal for Navigation Modeling”, Ben C. Gerwick, Inc., December 8, 2000.

6. “Kentucky Lock Addition, Underwater Blasting and Excavation, Downstream Cofferdam

Phase 1 Design Documentation”, D’Appolonia Engineering, subconsultant to Bergmann Associates and Ben C. Gerwick, Inc., November 21, 2000.

7. “Kentucky Lock Addition, Seismic Design Criteria”, 70% Submittal, Harza Engineering

Company, February 2001.

8. “Kentucky Lock Addition, Downstream Cofferdam, Phase 1 Design Documentation Report”, Bergmann Associates/Ben C Gerwick, Inc. Joint Venture and D’Appolonia Engineering, 100% Submission, May 23, 2001

9. “Comparison of Isolated Blasting and Overexcavation Versus Drilled Pipe Piles to Enhance

Sliding Resistance of Cellular Cofferdam”, Technical Memorandum, D’Appolonia Engineering, subconsultant to Bergmann Associates and Ben C. Gerwick, Inc., August 3, 2001 and Nashville District email reply dated August 29, 2001

10. “Cell 1 Construction Clearance”, Technical Memorandum, Bergmann Associates, August 8, 2001 and Nashville District email reply dated August 29, 2001.

11. “Blasting Study, Kentucky Lock and Dam”, Black and Veatch, 100% Submission, August 3, 2001.

12. “Interim Report on Kentucky Lock Concrete Mixture Proportioning and Thermal and

Mechanical Properties Investigation”, Technical Memorandum, Waterway Experimentation Station, December 20, 2001.

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13. “Kentucky Lock Addition, Downstream Cofferdam, Thermal Analysis of Tremie and Structural Concrete”, prepared by Ben C. Gerwick, Bergmann Associates/Ben C. Gerwick, Inc. Joint Venture and D’Appolonia Engineering, March 1, 2002.

14. “Kentucky Lock Addition, Downstream Lock Monoliths and Sills, Phase 1 Design

Documentation Report”, Huntington District, 90% Submission, June 2002.

15. “Kentucky Lock Addition, Downstream Monoliths Design Documentation Report, Thermal

Analysis, Black and Veatch, Final Submittal, June 5, 2002.

1.3 DOWNSTREAM COFFERDAM ALTERNATIVE

Several of the previous studies listed in Section 1.2.c provide several different design concepts for the downstream cofferdam. The TVA and COE reviewed all the recommendations and decided which option to continue to design. The current option was a combination of two options, 1) the float-in option from the VE study (Reference 1) and 2) the conventional cellular cofferdam closure from downstream cofferdam DM (Reference 2). The option chosen for the downstream cofferdam was to use the float-in wall with cellular sheet pile cofferdam tie in to the existing right bank. The float-in wall is used for the temporary cofferdam in order to build the new land chamber, but will be incorporated into the design of the new middle wall to eliminate its subsequent removal. The float-in wall is connected to the right bank by means of sheet pile cells and a tied Z-pile wall. These features are filled with granular fill and will be removed upon completion of the new land chamber. The downstream cofferdam is protected from barges by two guard cells. Both cells are temporary and would be removed after completion of the new lock chamber.

For the final plans and specifications, USACE Nashville District has decided to change to a non-prescriptive construction method for the concrete portion of the cofferdam. Therefore, the float-in details for the concrete cofferdam have been removed. The plans for the concrete portion of the cofferdam now show the basic concrete outline, final reinforcement requirements, and final monolith joint configuration. Foundation preparation, founding elevation, monolith dimensions and monolith joint locations have not been changed from the original Phase 2 design. The contractor awarded the contract will submit the proposed method of construction for approval.

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2. STRUCTURAL DESIGN CRITERIA

2.1. REFERENCES

2.1.a. U.S. Army Corps of Engineers Publications

As applicable, the following COE Publications were used for this design:

General Design

EC 1110-2-291 31 Oct 97 Stability Analysis of Concrete Structures EM 385-1-1 03 Sep 96 Safety and Health Requirements Manual ER 1110-2-101 15 Mar 96 Reporting of Evidence of Distress of Civil Structures EM 1110-2-2602 30 Sep 95 Planning and Design of Navigation Locks ER 1110-2-1150 31 Mar 94 Engineering and Design for Civil Works Projects EM 1110-2-2000 01 Feb 94 Standard Practice for Concrete for Civil Works

Structures

Sheet Pile Structures

ER 1110-2-8157 31 Jan 97 Responsibility for Hydraulic Steel Structures ER 1110-2-8152 31 Aug 94 Planning and Design of Temporary Cofferdams and

Braced Excavation EM 1110-2-2504 31 Mar 94 Design of Sheet Pile Walls EM 1110-2-2503 29 Sep 89 Design of Sheet Pile Cellular Structures TVA Monograph No. 75 1966 Steel Sheet Piling Cellular Cofferdams on Rock CWGS 02411 Metal Sheet Piling

Foundations and Embankments

EM 1110-2-2300 31 Jul 94 Earth and Rock-Fill Dams – General Design and

Construction Considerations EM 1110-1-2908 30 Nov 94 Rock Foundations TM 5-818-5 15 Nov 83 Dewatering and Groundwater Control for Deep

Excavations EM 1110-2-1902 01 Apr 70 Stability of Earth and Rock-Fill Dams

Impact Analysis

ETL 1110-2-338 30 Apr 93 Barge Impact Analysis AASHTO Feb. 91 Guide Specification and Commentary for Vessel

Collision Design of Highway Bridges.

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Seismic Design

ER 1110-2-1806 31 Jul 95 Earthquake Design and Evaluation of Civil Works

Projects ETL 1110-2-301 26 Aug 83 Interim Procedure for Specifying Earthquake Motions ITL 92-11 Nov 1992 The Seismic Design of Waterfront Retaining Structures

Structural Design

EM 1110-2-2104 Strength Design for Reinforced Concrete Hydraulic

Structures EM 1110-2-2105 31 May 94 Design of Hydraulic Steel Structures Post Tensioning Institute 1990 Manual for Post Tensioned Rock Anchors ETL 1110-2-542 30 May 97 Thermal Studies of Mass Concrete Structures

2.1.b. Technical Publications

The following Technical Publications may apply to the design of various features:

AASHTO Standard Specifications for Highway Bridges, 16th Edition.

AISC Load & Resistance Factor Design, 2nd Edition.

AISC Allowable Stress Design, 9th Edition.

American Welding Society, Structural Welding Code, Steel, (AWS-D 1.1-98).

Post-Tensioning Institute, Post Tensioning Manual, 5th Edition.

ACI 318-99: Building Code Requirements for Structural Concrete, American Concrete Institute.

2.2 PERTINENT PROJECT DATA

Data on the existing and proposed structures pertinent to the design of the downstream cofferdam is presented in Table 2-1. The stationing used for the design of the downstream cofferdam is presented in Table 2-2.

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Table 2-1

Summary of Pertinent Data

Item Existing Lock Dimensions

New Lock Dimensions

Lock Structures Top of Lock Wall El. 382.0 El. 382.0 Top of Miter Gates El. 380.0 El. 380.0 Top of Upper Approach Wall Varies Varies Top of Lower Approach Wall El. 342.0 El. 345.0 Upper Approach Wall Foundation N/A N/A Lower Approach Wall Foundation El. 270.0 Varies Upper Sill Elevation El. 335.0 El. 333.5 Lower Gate Sill Elevation El. 289.0 El. 285.0 Lock Floor Elevation El. 289.0 El. 285.0 Minimum Depth of Upper Approach Channel

53 ft 53 ft

Minimum Depth of Lower Approach Channel

11 ft 15 ft

Minimum Draft 9 ft 9 ft Reservoirs Normal Upper Pool El. 359.0 Maximum Upper Pool El 375.0 Maximum Lock Operating Upper Pool El. 375.0 Minimum Upper Pool El. 346.0 Normal Lower Pool (based on 50% duration)

El. 303.6

Maximum Lower Pool El. 360.0 Maximum Lock Operating Lower Pool El. 341.0 El. 344.0 Minimum Lower Pool (before and after construction of Olmsted Dam)

El. 300.0

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Table 2-2

Summary of Lock Stationing Data

Feature Stationing

(A-Upstream, B-Downstream) Upper Miter Gate Pintles of Existing Lock 0+00.0 Upper Miter Gate Pintles of New Lock 1+04.0 B Lower Miter Gate Pintles of New Lock 13+79.0 B Upstream End of Extended Landwall 14+62.0 B Downstream Baffle Trench, Inside Edge, New Lock

15+62.5 B

Offset (R-Right, L-Left looking downstream) Centerline of Existing Lock 0+00.0 Centerline of New Lock 2+15.0 R Landward Edge of Existing Lock Navigation Channel

0+55.0 R

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3. FOUNDATION CONDITIONS AND TREATMENT

3.1 GENERALIZED SUBSURFACE CONDITIONS

The geologic conditions at the Kentucky Lock site have been ascertained from various sources, including:

Documentation of the original lock construction provided by the USACE, including a geologic report, as-built drawings and photographs.

Paul A. Ross of the USACE-Nashville District, Geology Section, January 26, 1996 and March 21, 1997 Memoranda.

HARZA Engineering Company, March 2000 Submittal, “Kentucky Lock Addition, Design Memoranda, Downstream Cofferdam and Downstream Landward Approach Wall”.

HARZA Engineering Company, November 2000 Submittal, “Kentucky Lock

Addition, Detailed Design Report, Downstream Landward Approach Wall, Temporary Transmission Tower Stabilization."

Black and Veatch Special Projects Corporation (Black & Veatch), November 15, 2000 Submittal (70%), Kentucky Lock and Dam, Embankment Evaluation Report.”

Geologic logs for borings in the project area, and subsurface sections and profiles developed by the USACE from those borings.

D’Appolonia Engineering, August 3, 2001 Memorandum, ″Comparison of Isolated

Blasting & Overexcavation versus Drilled Pipe Piles to Enhance Sliding Resistance of Cellular Cofferdam.″

In the specific area of the downstream cofferdam, the native overburden soils consist of rounded, gravel- to cobble-size chert intermixed with silt and clay, and residuum or decomposed bedrock.

The mixtures of chert, silt and clay belong to the Tuscaloosa Formation. The residuum is comprised of remnant chert and clay from the in-place decomposition of Mississippian limestone of the lower Warsaw Formation and/or upper Fort Payne Formation. In the project area, the overburden is underlain by competent limestone bedrock of the Fort Payne Formation, which includes a generally thin, discontinuous weathered horizon. Notably, the limestone bedrock includes karst features as described below.

3.1.a Overburden and Residuum

The current riverbed elevations in the downstream cofferdam area generally range from El. 288 to El. 290. In and adjacent to the cofferdam footprint, the thickness of overburden soil and

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MAY 1, 2016 Page 10 residuum is generally less than 10 feet and the top of rock generally lies above El. 280, except for two prominent areas. Immediately upstream of the cofferdam, in the area of the Existing Land Wall Monoliths L-21 through L-25, the rock surface drops abruptly into major solution features. These solution features were previously treated during the original lock construction, as summarized subsequently. Beneath the upstream end of the cofferdam, the rock surface lies at approximately El. 275, which is believed to coincide with the competent rock surface that was prepared during the construction of Monolith L-25. Also, a soil and gravel-filled solution feature exists just downstream of the future Middle Wall, in the area of proposed Cell 2 and Arcs 1A and 2A. In this area, the rock surface drops well below El. 270 and the overburden thickness increases correspondingly, with a sizable depression at least as deep as El. 251 and possibly deeper. The limits of the solution features shown on the drawings were inferred from a few borings, and are not known with certainty.

Based on Standard Penetration Test (SPT) blow counts, the overburden and shallow infill materials are generally loose/soft with occasional stiffer zones, which coincide with high blow counts. In general, the stiffer zones or layers within the overburden are believed to be thin and discontinuous; although, thicker zones of SPT refusal were encountered in some borings.

Nevertheless, the overburden should not be inordinately difficult to excavate/dredge using conventional river-based techniques (e.g., hydraulic excavator, clamshell, hydraulic clamshell).

However, we anticipate that some harder zones and boulders will be encountered and could impede the driving of straight-web sheet piling to rock. Therefore, some isolated pre-excavations, chiseling, or other corrective action may be necessary on occasion to permit advancement of the sheet piling to rock. Sheet pile driving will be more difficult proximate to and on the right bank, where the Tuscaloosa Formation and residual soils are present.

3.1.b Bedrock

The more pronounced weathering features in the bedrock noted on the boring logs are generally confined to the upper 5 feet of bedrock, extending no deeper than approximately El. 276 and El.

269 in the concrete cofferdam section and coffercell/Z-pile wall areas, respectively. The weathering features and other defects in the rock mass appear to be more prevalent and affect thicker horizons downstream of the concrete cofferdam segments and nearer the right bank (i.e., beneath the tied Z-pile wall). The inference of a weathered rock horizon primarily stems from occasions of unaccountable core loss ("UL"), a higher frequency of fractures, joints and other discontinuities, and a weaker rock fabric at shallower depths below the rock surface. Although the weathered bedrock zone is not as competent as the underlying, competent limestone, the weathered rock is still generally hard and exhibits high RQD values where discontinuities/defects are not pervasive.

Considering the large bearing areas of the cofferdam structures relative to the small thickness of the weathered rock zone, the rock surface exposed immediately beneath the overburden would possess adequate bearing capacity (allowable bearing capacity, qa = 36 tsf) to reliably support the cofferdam structures. However, the concrete cofferdam section of the cofferdam will ultimately be integrated with the new Middle Wall monoliths. For this reason, the inferred weathered rock zone, which includes shallower zones of unaccountable core loss, will be

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MAY 1, 2016 Page 11 removed and the concrete cofferdam segments will bear on rock of similar competency to the likely rock foundation for the monolith portion constructed in-the-dry.

In the area of the cofferdam cells and tied Z-pile walls, widespread excavation of weathered rock is not currently being contemplated. For the cellular cofferdam area, D’Appolonia completed a technical evaluation and cost comparison of two options to enhance the sliding resistance of the downstream cellular cofferdam. The options included targeted overexcavation of rock with underwater blasting to create "shear keys" or the installation of drilled pipe piles. These options were discussed in detail in D’Appolonia's August 3, 2001 Memorandum, "Comparison of Isolated Blasting & Overexcavation versus Drilled Pipe Piles to Enhance Sliding Resistance of Cellular Cofferdam." The TVA and USACE selected the drilled pipe pile option, in lieu of blasting isolated "shear keys" into rock over a portion of the cellular cofferdam footprint.

Drilled pipe piles will be installed in Cells 1, 2 and 3, and in Arc 1A to integrate the bottom concrete plugs with the underlying, competent rock. Piles were excluded from Arc 2A to simplify coordination with the floodway and bridge construction that will occur over the arc, and because of the more difficult logistics posed by the distinctly lower top elevation of the arc.

The bedrock stratigraphy is characterized by medium- to thick-bedded limestone with occasional shaly zones and more common shale partings and chert beds, bands, and nodules. The limestone bedrock is hard to very hard, exhibiting high unconfined compressive strengths, which is due to a highly siliceous composition (approximately 30% silica based on available data). The bedrock also exhibits very high RQD values with few exceptions. The prominent rock mass discontinuities include nearly horizontal bedding planes, and steep (60 or more degrees from the horizontal) to nearly vertical fractures or joints. Based on the available borings, the bedding planes and fractures/joints are generally tight (“hairline”) and/or calcite-filled. However, borings outside the study area and past experience at the site indicate that some open and weathered discontinuities (usually filled with clay and/or gravel) should also be expected. Smaller solution zones have been encountered along some bedding planes and joints and, as mentioned above, major solution features have been identified just upstream and downstream of the concrete cofferdam section of cofferdam.

Experience from the original lock construction suggests that other significant solution features could exist, and possibly extend from the rock surface to below El. 100. Some deeper solution channels beginning below about El. 245 were encountered in a few borings upstream of the New Middle Wall. However, slickensides and other evidence of movement along the discontinuities do not appear prevalent. Therefore, as characterized in the aforementioned references, the overall rock mass is hard and competent, and the predominant discontinuities of interest are the horizontal bedding planes and shaly zones or partings, and near vertical joints and fractures. The larger and more extensive solution features and other significant discontinuities are of primary interest because they might affect the configuration of a particular monolith (e.g., bearing elevation) and influence foundation treatment requirements (e.g., grouting to control seepage, and/or to enhance the stiffness and shear strength of the rock mass).

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3.1.c Geotechnical Properties

The following tables present the geotechnical properties that were derived from the above-referenced sources, and include the properties being applied under the Phase 1 work.

SOIL PROPERTIES

MATERIAL TYPE MOIST UNIT

WEIGHT

(pcf)

SATURATED

UNIT

WEIGHT

(pcf)

UNDRAINED

SHEAR

STRENGTH

(su, psf)

DRAINED

FRICTION

ANGLE

(, degrees)

DRAINED

SHEAR

STRENGTH

(c, psf)

GENERALIZED SOIL STRATIGRAPHY (REFER TO BORING LOGS FOR APPLICABILITY)

Soft to medium silty clay

110 115 300 26 0

Medium to stiff silty clay

115 120 600 30 0

Soft to stiff clayey gravel/gravelly clay

110 115 500 30 0

Med. to very stiff clayey gravel/gravelly clay

115 120 1250 34 0

Medium dense to dense gravelly sand

115 120 NA 35 0

GENERALIZED DESIGN PROPERTIES FOR IN-SITU (UNDISTURBED) ALLUVIUM PHASE 1

DDR

115 120 NA 30 0

ALLUVIUM OR GRANULAR FILL REPLACED (DUMPED) IN RIVER PHASE 1

DDR

110 116 NA 25 0

GRANULAR BACKFILL MATERIAL FOR SHEET PILE CELLS PHASE 1

DDR

115 125 NA 32 0

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ROCK PROPERTIES

ROCK PROPERTY UNITS ADOPTED BY USACE

(DESIGN MEMORANDUM

DATED JANUARY 26, 1996)

PHASE 1 - DDR

Total unit weight (t) (pcf) 167 167

Unconfined compressive strength (qu) (psi) 28,000 (average value) 28,000

Ultimate tensile strength (tu) (psi) 1,145

Allowable tensile strength (ta) (psi) 0

Elastic modulus (E) (psi) 5.5E06 5.5E06

Poisson’s ratio () (dim) 0.3 0.3

ROCK MASS SHEAR STRENGTH PROPERTIES FOR WEDGE FAILURE ANALYSES

Angle of internal friction ():

rock mass

(degrees) 36 36(1)

Cohesive strength (c): rock mass (psi) 13.2 13.2(1)

INTERFACE SHEAR STRENGTH PROPERTIES FOR SLIDING ANALYSES

Angle of friction (): shear along rock-grout contact

(degrees) 29.3 [40] ##(2)

Cohesion (c): shear along rock-grout contact

(psi) 62.5 [0] ##(2)

ALLOWABLE BEARING PRESSURE

Weathered rock (ksf) 72 72

Competent/Sound rock (ksf) 800(3)

TIEBACK/ANCHOR ALLOWABLE BOND STRESS IN COMPETENT ROCK

Allowable bond stress:

anchor grout-competent rock bond

(psi) 100 100

(1) Failures through the rock mass must consider the influence of prevalent joint and fracture patterns, characteristically weaker bedding contacts, and other discontinuities/defects, as well as the potential adverse impacts of blasting activities. The reported rock mass shear strength properties were derived by the USACE by weighting the results of laboratory shear strength tests (direct shear and triaxial compression tests) on natural fractures, joints and intact rock.

(2) Some of the available borings indicate that horizontal discontinuities, lenses of chert and clay, and possibly open voids or cavities exist between El. 269 and El. 280. In recognition of these rock mass defects, the extent of which is uncertain, reduced sliding resistance parameters were considered in the cofferdam design. Refer to the subsequent table and discussion concerning sliding resistance parameters.

(3) The reported minimum and maximum unconfined compressive strengths (UCSs) of the limestone bedrock are approximately 16,688 psi and 36,512 psi, respectively. The reported allowable bearing pressure is one-third the minimum UCS-value. Bearing capacity of the competent rock mass should not govern the design of the cofferdam structures, as the maximum bearing stress imposed by the cofferdam structures will be a very small percentage of even the minimum UCS.

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ALLOWABLE SLIDING RESISTANCE

SLIDING RESISTANCE ANGLE OF FRICTION

(DEGREES)

COHESION (PSI)

Upper Bound(1) 35 6

Intermediate(2) 37 0

Lower Bound(3) 29 0

(1) Sliding resistance along natural fractures in rock. Values are applicable where there is reasonable confidence that weathered rock, cavities and voids that are prevalent in the upper few feet of rock will be removed by the planned excavation activities.

(2) Sliding resistance along natural fractures in rock, neglecting the cohesive strength component. Values are applicable where there is reasonable confidence that weathered rock, cavities and voids that are prevalent in the upper few feet of rock will be removed by the planned excavation activities, or where there are additional measures taken to augment the sliding resistance of the rock such as keying the structure into more competent rock using drilled pipe piles.

(3) Based on available laboratory test data, a 29 degree friction angle approximates the minimum drained shear strength of cohesive soils prevalent in the downstream cofferdam area, and the average shear strength along the interface of sawn rock surfaces neglecting cohesion.

The upper-bound properties for sliding resistance are judged to be appropriate for the concrete cofferdam section of cofferdam, where extensive excavation and subgrade preparation are planned throughout the area. The intermediate and upper-bound properties are appropriate for comparative sliding stability analyses of the cofferdam cells, recognizing that drilled pipe piles are planned within the footprint of some cells and arcs to augment the rock sliding resistance by keying the base of the structure into more competent rock. The lower bound properties were established for use in a sensitivity study of the cofferdam cell sliding stability, but are judged to be inappropriately low for final design because they understate the sliding resistance provided by the planned scope of foundation preparation and the application of drilled pipe piles within the footprint of selected cells.

The sensitivity study of the cofferdam cell sliding stability indicates that required factors of safety are met or exceeded when applying either the upper bound or intermediate properties.

With the lower-bound properties, the factor of safety for sliding stability exceeds 1.35 even under the more critical load cases. Therefore, in our professional opinion, an acceptable margin of safety against sliding instability will be achieved with the scope of foundation preparation that is currently planned in the cellular cofferdam area. Refer to Section 4.2, paragraph Cellular Cofferdam – Foundation Parameter Sensitivity Analysis, for additional discussion of the cellular cofferdam stability.

3.2 PREPARATORY EXCAVATION

The current riverbed elevations in the cofferdam area generally range from El. 288 to El. 290.

The cofferdam area will be excavated in two stages as part of foundation preparation. The initial stage (Stage 1) involves conventional river and land-based excavation of overburden soils to remove riprap and other obstructions from the right bank and to expose the rock surface in and around the area of the concrete cofferdam segments. The primary purposes of the Stage 1 overburden excavation are to facilitate pile driving on the right bank, and to expose the rock surface in areas of subsequent underwater blasting.

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Stage 2 involves rock excavation employing underwater blasting and conventional river-based excavation techniques, and preparation of the navigation channel in advance of placement of the concrete cofferdam segments. In the Stage 2 rock excavation, high rock areas in and around the concrete cofferdam section of cofferdam will be removed to enable positioning and setdown of the concrete cofferdam segments and construction of Cell 1. An area somewhat larger than the footprint of the segments will be excavated to El. 278 to accommodate the planned setdown level of the segments.

D'Appolonia's Final Report (dated April 11, 2001) on Underwater Blasting and Excavation for the downstream cofferdam construction was submitted to the USACE in April 2001. The report identifies the primary construction aspects, considerations, and concerns associated with underwater blasting and excavation at the KY Lock site. More recently, Black & Veatch completed a blasting study, and a structure and equipment inventory for the entire Kentucky Lock & Dam site (“Blasting Study,” 100% Submittal, August 3, 2001, Contract No. DACW62- 99-D-0022, D.O. #6), and prepared a report of recommended blast vibration limits and blasting restrictions to be applied across the site. The Black & Veatch report also included guideline blasting specifications, which are intended to guide all blasting activities at the site.

The Stage 2 excavation will also involve preparation of the navigation channel for installation of the concrete cofferdam segments. Immediately before placement of the first concrete cofferdam Segment to be installed, a "bar sweep" or similar survey of the entire downstream navigation channel will be performed from the lower gate of the existing lock through Station 16+30B.

Concurrent with this survey, the channel will be excavated where required to ensure a riverbed elevation no higher than El. 288, within a tolerance of +/- 12 inches. If concrete cofferdam segments are not installed in continuous succession, this process will be repeated before placing each segment until the last segment is installed.

3.3 SUBGRADE PREPARATION

The planned underwater blasting and excavation through the concrete cofferdam section of the cofferdam should remove all unsuitable rock and expose sound limestone. However, some rubble, debris and sediment (i.e., unsuitable materials) will likely remain and/or accumulate on the rock surface after the initial mass rock excavation is completed. These unsuitable materials will be removed through suction dredging and/or airlifting during subgrade preparation. Also, rock through the subgrade or subdrilling zone and the bearing surface will be disturbed by the blasting activities. Portions of the disturbed horizon will be grouted during the grout curtain construction, and drilled pipe piles in the coffercells will be installed in critical areas to enhance sliding resistance and provide excavation support. Additional exploratory drilling will conducted in this contract to provide additional information about jointing in rock adjacent to the concrete cofferdam. The design analysis for the next contract will include investigating the need for post-tensioned anchors to enhance sliding resisitance along potential rock jointing below the permanent concrete cofferdam. The original design included the use of drilled pipe piles below the concrete portion of the cofferdam. During the ATR, concern was raised at the large magnitude of load in the pipe piles, as designed. With the potential for weathered rock at the interface with the concrete, the potential for deflection at the top of the pile and the resulting moment was considered a possibility. This was not accounted for in the original design.

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Although, the angle of rock jointing used in the original design was considered conservative, checking the force in the piles for a more realistic joint angle still resulted in large lateral loads in the piles.

Once the major underwater excavation is completed, the bearing surface will be inspected for unsuitable materials and obvious disturbance/defects (e.g., open discontinuities). Where underwater inspection is required, the bearing surface will be directly inspected with divers and a remotely operated submersible camera. A submersible camera shielded in a drum with a high intensity light source and external supply of clear water should create good visibility for remote underwater inspection. We have specified that divers accompany the submersible camera, as divers will enable suspect areas to be targeted for videotaping and physically probed. Unsuitable areas will be excavated further, jetted, and/or suction dredged, depending on the consistency, thickness and extent of unsuitable material. Considering the large bearing area of the proposed structures, occasional defects or substandard conditions in the bearing surface are tolerable.

Fractures, joints, solution channels, and other perceptible defects that bisect the bearing surface will be documented and addressed through foundation preparation, which will include grout curtain construction (in a later contractor prior to unwatering) and reinforcement (drilled pipe piles) of the structure-bedrock interface.

3.4 GROUT CURTAINS AND OTHER SPECIALTY WORK

3.4.a Grout Curtain

A grout curtain will not be installed as part of the downstream cofferdam contract. The contract does not include unwatering of the cofferdam area. A grout curtain will be designed and installed prior to unwatering in the next contract. There are exploratory borings included in this contract and will aid in the design of the grout curtain.

3.4.b Other Specialty Work

As indicated previously, defects exist in the rock horizon between El. 269 and El. 280 beneath the cofferdam cells. Drilled pipe piles will be installed in Cells 1, 2 and 3, and in Arc 1A to bypass unsuitable rock horizons and integrate the bottom concrete plugs with the underlying, competent rock, thereby enhancing the cellular cofferdam sliding stability. Piles were excluded from Arc 2A to simplify coordination with the floodway and bridge construction that will occur over the arc, and because of the more difficult logistics posed by the distinctly lower top elevation of the arc. Therefore, the density of piles in Cells 2 and 3 was increased to compensate for the absence of piles in Arc 2A. The drilled pipe piles will consist of 9-5/8 inch diameter pipe piles grouted in 12-inch minimum diameter drill holes. The design anticipates that the piles will be constructed from the tops of the completed cells and arc, through the granular backfill and bottom concrete plugs. The piles were designed to augment the base frictional resistance and increase the sliding factor of safety above 1.5.

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4. DOWNSTREAM COFFERDAM

4.1 OVERVIEW

The downstream cofferdam provides the downstream closure in which the new middle wall and new land wall will be constructed.

4.1.a General Description

The downstream cofferdam is composed of the following main features:

1. Sheet Pile Cofferdam (See Section 4.2)

2. Flooding Facility (See Section 4.3)

3. Float-In Segment (See Section 5)

The cellular portion is approximately 335 ft long measured along the centerline of the cells. It extends from the downstream end of the float-in segment No. 2 at station 15+19.38B, curves to the right bank, connects to a tied Z-pile wall and then intersects the right bank. The tops of the sheet pile portions are at El. 343.5. The cells and tied Z-pile wall are filled with granular fill material and are founded on rock. See drawings 510N105 through 510N107 and drawings 518N200 through 518N214 for details.

A cofferdam flooding facility is provided at Arc #2A between Cells #2 and #3. This facility provides a controlled means of flooding the inside of the cofferdam during times of high water when the river is expected to overtop the cofferdam. See drawings 518N206 through 518N214 for details.

The float-in segment cofferdam extends from the connection with the existing lower guide wall monolith L-25 to the connection with Cell #1 of the cellular cofferdam. The float-in portion is constructed in two segments. Segment No.1 is the upstream most segment that connects to monolith L25. Segment No.2 connects to the downstream edge of Segment No.1 and upstream edge of Cell #1. See drawings 61N650-1 through 61N650-55 for details.

A river current training dike will be constructed prior to the construction of the downstream cofferdam. This training dike is located at the downstream tip of Powerhouse Island. This training dike was placed in the hydraulic model. Preliminary results show that this training dike has a beneficial impact on the approach river conditions by reducing the strength of the primary eddy as well as moving it downstream and virtually eliminating the secondary eddy in the lock approach. An approximate location of the dike is shown on drawing 510N102.

4.2 SHEET PILE COFFERDAM

4.2.a General

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The design of the cellular cofferdam portion was based on EM 1110-2-2503 Design of Sheet Pile Cellular Structures and the right bank tie-in portion is based on EM 1110-2-2504 Design of Sheet Pile Walls. These portions of the cofferdam are considered temporary, and were designed with granular fill to facilitate its removal after the future lock chamber is completed. See drawings 510N105 through 510N107 and drawings 518N200 through 518N214for details.

4.2.b Design Loads

1. Concrete The unit weight of concrete is taken as 150 pcf. The unit weight of tremie concrete is taken as 150 pcf.

2. Steel The unit weight of the steel sheet piles and any steel is taken as 490 pcf.

3. Granular Fill Material The granular fill material within each of the cells and arcs is assumed to have geotechnical properties as described in section 3.1.c Geotechnical Properties.

4. Alluvium Material The river bed (alluvium) material outside the cofferdam is assumed to have geotechnical properties described in section 3.1.c Geotechnical Properties.

5. Horizontal Water Pressure The horizontal triangular distribution is defined by applicable pool elevations with a unit weight of water taken as 62.4 pcf.

6. Hydrostatic Uplift The hydrostatic uplift distribution across the base of the cells is assumed to be full hydrostatic headwater pressure applied to the portion of the base in tension (ineffective) and vary linearly from headwater to tailwater along the portion of the base in compression.

7. Barge Impact Since the downstream cofferdam is protected by two guard cells, and that the cofferdam is consider a temporary structure, barge impact loads are not considered. The need, location, and configuration for the two guard cells were determined through a 1 to 100 scale physical modeling effort performed by ERDC, Coastal and Hydraulics Laboratory. These efforts were documented in a report entitled "Kentucky Lock and Dam, Tennessee River, Kentucky, Navigation Study" dated April 2002 with a reference number of ERDC/CHL TR-02-3.8.

Saturation Level The saturation level of the granular fill material is established in accordance to Figure 4-2 in EM 1110-2-2503. The presence of weep holes, dewatering wells, and berms are taken into consideration. The fill material within the cells is assumed to be free draining coarse graded fill.

9. Operating Basis Earthquake (OBE)

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The analysis performs a pseudo-static seismic analysis with computed dynamic forces. These dynamic forces include hydrodynamic soil and water forces and structure inertia forces. These forces are computed and applied in the most unfavorable direction. During the operating basis earthquake, the horizontal seismic coefficient (kh) used in the analysis was 2/3 * .05 = .033. The horizontal Seismic Coefficient was taken as 2/3 of the Significant Hazard PGA (Peak ground acceleration) recommended from, Seismic Design Criteria, Kentucky Lock Addition, 70% submittal, dates February 2001, by Harza Engineers.

10. Maximum Design Earthquake (MDE) The analysis performs a pseudo-static seismic analysis with computed dynamic forces. These dynamic forces include hydrodynamic soil and water forces and structure inertia forces. These forces are computed and applied in the most unfavorable direction. During the maximum design earthquake, the horizontal seismic coefficient (kh) used in the analysis was 2/3 * .13 = .0867.

The horizontal Seismic Coefficient was taken as 2/3 of the Significant Hazard PGA (Peak ground acceleration) recommended from, Seismic Design Criteria, Kentucky Lock Addition, 70% submittal, dates February 2001, by Harza Engineers.

Since the completion of the Phase 2 design, TVA has updated the seismic criteria since the completion of the Seismic Design Criteria report in 2001, by Harza Engineers. The current MDE for the project is 0.39 and the OBE is 0.15 for high hazard structures (at 100 hz). Though not specifically provided by TVA, the values for significant hazard structures (used for the downstream cofferdam) will be less than these values.

The Upstream Cofferdam and Upstream Monoliths for the Kentucky Lock Addition were designed using the seismic criteria from the 2001 Harza Report. In 2009, before construction of the Upstream Monoliths, Black and Veatch performed a Seismic Study to determine the effects of the updated seismic criteria on the design of the Upstream Monoliths. They noted in the study that for both the MDE and OBE, the previous spectral curve completely envelopes the new response spectra curve. Therefore, the seismic demand on the upstream monoliths is actually reduced from what was previously calculated and the previous designs were adequate.

Since the stability results of the cellular cofferdam are not currently controlled by the seismic load cases and the seismic demand is less for the new response spectra curves, the seismic analysis is considered adequate.

4.2.c Design Loading Conditions

Case 1 - Normal Operating (Normal)

Tailwater at EL. 335.0 (maximum before evacuation) Cofferdam Dewatered

Case 2A - Maximum Pool (Temporary) Tailwater at EL. 343.5 (equal to 25 year flood elevation) Cofferdam Dewatered

Case 2B - Initial Filling (Temporary)

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Tailwater at EL. 300.0 before(approximate minimum tailwater before and after Olmsted is in Operation)

Saturation level – fill material assumed to be fully saturated to top of cell (EL. 343.5) Before Cofferdam Dewatered

Case 3 - Drawdown Condition (Temporary)

Tailwater at EL. 335.0 (maximum before evacuation) Cofferdam Dewatered

Case 4A - Normal Operating with Operating Basis Earthquake (OBE)(Seismic)

Tailwater at EL. 303.6 (equal to 50% tailwater duration) Cofferdam Dewatered

Earthquake coefficient – Kh = Horizontal Coefficient = 2/3 * 0.05 = 0.033 Kv = Vertical Coefficient = 2/3 of Kh

Case 4B - Normal Operating with Maximum Design Earthquake (MDE)(Seismic)

Tailwater at EL. 303.6 (equal to 50% tailwater duration) Cofferdam Dewatered Earthquake coefficient – Kh = Horizontal Coefficient = 2/3 * 0.13 = 0.0867 Kv = Vertical Coefficient = 2/3 of Kh

4.2.d Design Methodology

4.2.d(1)…