A22 -W912EK25RA018 - PLAN_SET_REF-SITE_CHAR.pdf

MISSISSIPPI RIVER

LOCK NO. 19

NOSE PIER REPLACEMENT AND BULKHEAD RECESS

Site Characterization Information

Historical Borings

MISSISSIPPI RIVER

LOCK NO. 19

NOSE PIER REPLACEMENT AND BULKHEAD RECESS

Site Characterization Information

Geotechnical Report 2024

REPORT OF GEOTECHNICAL INVESTIGATION

AND ENGINEERING ANALYSIS

Proposed Nose Pier Replacement and Bulkhead Recess

Lock 19

Keokuk, Iowa

Prepared For:

US Army Corps of Engineers Rock Island District

1500 Rock Island Drive Rock Island, Illinois 61201

Prepared By:

ABCD Geotechnical-JV, LLC 52 Lindsley Avenue, Suite 101 Nashville, Tennessee 37210

Contract No. W912EK24D0001 Task Order No. W912EK24F0059

22 January 2025

22 January 2025

Ms. Ranjit Kaur US Army Corps of Engineers Rock Island District 1500 Rock Island Drive Rock Island, Illinois 61201

Subject: Report of Geotechnical Investigation and Engineering Analysis

Proposed Nose Pier Replacement and Bulkhead Recess Lock 19 Keokuk, Iowa Contract No. W912EK24D0001; Task Order No. W912EK24F0059

Dear Ms. Kaur:

ABCD Geotechnical JV, LLC (ABCD) is pleased to submit this report which details the results of our geotechnical exploration for the referenced project. Our services were performed in general accordance with the provided Scope of Work for Geotechnical Investigation and Engineering Analysis for Lock 19 Nose Pier Replacement and Bulkhead Recess in Keokuk, Iowa, Revision 2, dated 12 November 2024.

The attached report summarizes the project information provided to us, describes the site and subsurface conditions encountered, and details our geotechnical recommendations for the project. The Appendices include figures, descriptions of our field-testing procedures, and our field and laboratory test results.

We appreciate this opportunity to be of service to you on this project. Please contact us if you have any questions regarding this report. We look forward to serving as your geotechnical consultant for the remainder of this project.

Sincerely, ABCD Geotechnical JV, L.L.C.

Bradley Kouchoukos, PE, VMA Nathan Long, PE Project Engineer Director of Geotechnical Services

Enclosures: Report of Geotechnical Exploration

Report of Geotechnical Investigation and Engineering Analysis 22 January 2025 Proposed Nose Pier Replacement and Bulkhead Recess Contract No. W912EK24D0001 Lock 19 – Keokuk, Iowa Task Order No. W912EK24F0059

TABLE OF CONTENTS

1.0 INTRODUCTION

1.1 PURPOSE AND PROJECT DESCRIPTION

1.2 OBJECTIVE AND SCOPE OF SERVICES

2.0 SITE GEOLOGY

3.0 EXPLORATION PROCEDURES AND FINDINGS

3.1 GENERAL

3.2 EXISTING NOSE PIER CONDITIONS AND DESIGN

3.3 EXISTING RETAINING WALL

3.4 OVERWATER DRILLING CONDITIONS

3.4.1 Alluvial Soils

3.4.2 Bedrock

3.4.3 River Level

4.0 LABORATORY TESTING

5.0 GEOTECHNICAL DESIGN AND CONSTRUCTION RECOMMENDATIONS

5.1 IN-THE-WET AND IN-THE-DRY CONSTRUCTION DISCUSSION

5.1.1 General

5.1.2 In-the-Wet – River Wall Extension

5.1.3 In-the-Dry – River Wall Extension

5.1.4 In-the-Wet – Sill

5.1.5 In-the-Dry – Sill

5.1.6 In-the-Dry Bulkhead Recess on the Face of the Existing Land Wall

5.2 BEDROCK EXCAVATION

5.3 NOSE PIER DEMOLITION

5.4 SHALLOW FOUNDATIONS

5.5 DRILLED SHAFT FOUNDATIONS

6.0 QUALIFICATIONS OF RECOMMENDATIONS

APPENDICES

APPENDIX A: GEOLOGIC MAP / SITE VICINITY PLAN / BORING LOCATION PLAN / RIVER WALL EXTENSION – PROPOSED

WORK EXTENTS

APPENDIX B: FIELD CLASSIFICATION / SOIL CLASSIFICATION CHART (USCS) / FIELD PROCEDURES

APPENDIX C: TEST BORING LOGS / ROCK CORE PHOTO LOG / CONCRETE CORE PHOTO LOG

APPENDIX D: SITE PHOTOGRAPHS

APPENDIX E: LABORATORY TEST RESULTS

APPENDIX F: CONSTRUCTION RECOMMENDATION REFERENCE PHOTOGRAPHS AND FIGURES

1.0 INTRODUCTION

1.1 PURPOSE AND PROJECT DESCRIPTION

The Rock Island District (MVR) has identified “the purpose of this geotechnical investigation is for extension of the upstream river wall to provide recesses for bulkheads that will allow the upstream guard gate to be dewatered and inspected. The bulkhead system will include a concrete sill that extends the width of the lock chamber, connecting to the new river wall extension and the existing land wall.”

Additionally, according to the Scope of Work (SOW), an existing retaining wall foundation, which was constructed as part of the 1912 Lock and Drydock, spans across the lock chamber floor and is planned to be incorporated into the river wall extension. The latest scan of the river floor detailed in the Existing and Planned Features Plan (i.e., Figure 2 of the SOW) shows the current elevations of the channel bottom within the proposed sill footprint ranges from approximately El. 465 to El. 473. The estimated channel bottom elevations within the river wall extension ranges from about 473 feet to 484 feet. The water level at the site may vary considerably but is generally maintained close to EL 518.2 ft MSL 1912 Datum.

We understand at the 30% design phase, the river wall nose pier extension is currently planned to extend an additional 28½ feet in length, be 30 feet wide, have a total weight of approximately 7,500 kips, be a gravity structure, and have an approximate footprint area of 850 square feet. Additionally, we understand the sill is currently planned to be 16 feet tall, 15 feet wide, have a total weight of approximately 3,900 kips, including the bulkheads, be supported on seven drilled shafts, and have an approximate footprint area of 1,650 square feet. The bulkhead sill is currently planned to be approximately 28 feet upstream of lock intake culverts.

Figure 1: View of Proposed Improvements (From Sheet S-901 of 30% Drawings)

River Wall Extension

Bulkhead Sill

Retaining Wall Foundation

Bulkhead Recess

Based on the information provided on 7 November 2024 during the project Industry Day, we understand the contract is planned to be issued as a Base plus Options contract as follows:

• Base Bid – Repair existing nose pier, upstream monolith extension with bulkhead recess

• Option 1 – Land wall bulkhead recess

• Option 2 – Bulkhead recess

• Option 3 – Dewatering

With a potential schedule as follows:

• Contract award – anticipated in FY25 4th QTR

• Construction starting winter 2025-2026; closure period (45-90 days) o 2025 – 2026: Excavation and clearing o 2026 – 2027: Base Bid and Option 1 o 2027 – 2028: Option 2 and Option 3

Additionally, we understand preliminary construction phasing as presented within the Industry Day is as follows:

• River Wall Extension: Demolition of the existing structure is planned to be completed with wire saw and then soil and rock material to be removed with mechanical dredging and rock excavation. Once demolition and removal of material is completed, in-the-wet construction will be completed using pre-cast segments and concrete placement via tremie method.

• Bulkhead Sill: Rock excavation to remove material as needed. Once removal of material is completed, in-the-wet construction will be completed using stay-in-place formwork with concrete placement via tremie method with drilled shafts.

• Land Wall Recess: Demolition of the existing structure is planned to be completed with wire saw and then construction completed within a cofferbox (limpet).

1.2 OBJECTIVE AND SCOPE OF SERVICES

The ABCD team was selected by MVR to perform a geotechnical investigation and engineering analysis for the Lock 19 Project. The objective is to verify and obtain additional subsurface information relative to the properties of materials, foundation soils and rock, and water conditions within the area of the proposed nose pier replacement and sill with bulkhead recesses and obtain additional structural information relative to the existing nose pier to support the design and construction.

The scope of services was detailed in the Scope of Work for Geotechnical Investigation and Engineering Analysis for Lock 19 Nose Pier Replacement and Bulkhead Recess in Keokuk, Iowa, Revision 2, dated 12 November 2024 (SOW).

Our geotechnical exploration services did not include sampling and testing of the soil, rock, surface water, groundwater, or air for the presence of environmental contaminants. Therefore, special procedures were not recommended for handling or managing sediments encountered during future construction, or for handling the soil or rock samples from the borings or concrete samples from cores in the geotechnical testing laboratory.

2.0 SITE GEOLOGY

The project is located in southeastern Lee County, Iowa on the Mississippi River. Available mapping provided by the Iowa Geological Survey (IGS) Geologic Map Service, shown in Figure A1 of Appendix A, provides mapping within the Keokuk quadrangle, which terminates just to the west of the lock site. The lower end of the Lock 19 complex is visible on the map. Similar mapping of the Hancock Quadrangle was not available from Illinois. Other sources, including Rockd geology mapping application, were utilized to identify geologic formations. Based on these sources, the northern end of Lock 19, where the work is to be performed, is mapped as being underlain by the Burlington Limestone near the contact with the stratigraphically younger Keokuk Limestone. Further to the east and west of the site, the bedrock is composed of the younger Warsaw Formation. The following are descriptions of these units taken from the

IGS’s Geologic Map of the Keokuk Quadrangle.

Figure 2: Lithostratigraphic Unit Table from Bedrock Geologic Map of the Keokuk 7.5’ Quadrangle, Lee

County, Iowa, Hancock County, Illinois, and Clark County Missouri

3.0 EXPLORATION PROCEDURES AND FINDINGS

3.1 GENERAL

The field investigations took place from 7 to 12 October and 22 to 25 October 2024 in accordance with our

Work Plan provided to USACE on 25 September 2024. We completed three (3) marine borings from a barge platform to collect representative soil and bedrock samples within the areas for the new bulkhead sill, the expected existing submersed foundation wall, and the new river wall extension. Additionally, four Probe

Borings (i.e., P-1 through P-4) were completed within the footprint of the new sill to evaluate bedrock depth by extending the drill rod and drill bit to the bottom of the riverbed until resistance estimated to be bedrock was encountered. No rock cores or soil samples were collected at Probe Borings P-1 through P-4; however, the depth of estimated bedrock was recorded. Two (2) concrete cores were also completed to collect representative concrete samples of the existing river wall nose pier where the damage from various barge impacts is most severe. Additional details concerning Drilling / Coring Scope and Methodology are provided in our Work Plan.

Table 1 summarizes the location where each geotechnical and probe boring and concrete core was performed. Prior to drilling/coring operations, boring locations were marked in the field utilizing Trimble

R12/R12i Dual Frequency GPS and a Trimble SX12 Robotic Total Station. The Site Vicinity Map and Boring

Location Plan, located in Appendix A, shows the approximate site and boring locations, respectively.

Additional discussion regarding field procedures used during this exploration are provided in Appendix B.

Table 1: Boring Location Summary

Boring No. Coordinates Location

LB-24-01A 151589.81 N, 2232391.90 E Within Footprint of Proposed New Sill

LB-24-02 151580.39 N, 2232446.58 E

Within Footprint of River Wall Extension within Existing

Submersed Foundation Wall

LB-24-03 151628.37 N, 2232468.96 E Within Footprint of River Wall Extension

LC-24-01 151555.74 N, 2232446.12 E Vertical Core Within Existing Nose Pier

LC-24-02 151559.83 N, 2232439.15 E Horizontal Core Within Northwest Wall of Existing Nose Pier

P-1 151582.56 N, 2232347.83 E Within Footprint of Proposed New Sill – Land Side Downstream

P-2 151597.07 N, 2232356.40 E Within Footprint of Proposed New Sill – Land Side Upstream

P-3 151570.21 N, 2232402.99 E Within Footprint of Proposed New Sill – River Side Downstream

P-4 151584.47 N, 2232405.81 E Within Footprint of Proposed New Sill – River Side Upstream

3.2 EXISTING NOSE PIER CONDITIONS AND DESIGN

The existing nose pier is generally in fair condition with the exception of the portion of the structure which has been struck by barge traffic on multiple occasions including two incidents during the month of October

2024. The damaged segment of the wall is about 30 feet long, with the most damaged area being at the downstream end of the segment, just before the wall straightens out for the lock chamber. The impacts have caused damage to/removal of armoring and damage to the concrete itself. The impacts have also lifted the upper 4 to 6 inches of concrete for the nose pier’s horizontal surface within 2 to 3 feet of the vertical face. Loss of concrete has occurred within the upper 2 feet of the wall, especially within the most heavily damaged area identified above. See images in Appendix D for the condition of the nose pier during our investigation.

Drawing No. M-L-19-2 20/6 from the Drawing Set Mississippi River Lock & Dam No. 19 New 1200-ft Lock

Monolith & Lift Layout Upper End, Rev. 2, dated 1 May 1958 (PDF A02.02), identifies the nose pier is designated as Monolith 1-R which has a top elevation of 525.75 feet and base elevation ranging from 456.5 to 468.0 feet. Based on the lift layout, the monolith was constructed in seven lifts. Based on the Drawing

No. M-L-19-2 20/7 from the same drawing set, the monolith bears on bedrock.

The vertical concrete core LC-24-01 was completed on the surface of the nose pier within the extent of the nose pier planned to be removed for construction of the nose pier extension structure. Concrete core

LC-24-01 extended a total depth of 14.6 feet to an elevation of 510.61 feet. The core was terminated prior to the planned depth of 15 feet due to encountering reinforcing steel with the corehole. The upper approximate 20 inches of recovered material were highly fractured and broken. The underlying material extending to an approximate depth of 7.7 feet was slightly to moderately fractured. Below a depth of 7.7 feet, the concrete was slightly weathered. We did not observe an obvious break at the understood Joint

Elevation of 512.34ft (Core Depth approx. 13 ½ ft).

The horizontal concrete core LC-24-02 was completed on the northwest side of the nose pier approximately

2½ feet below the top surface of the nose pier within the heavily damaged area. The core extended approximately 3.3 feet into the nose pier. The initial approximately 16 inches of the concrete core had noticeable, degraded concrete; however, the remaining approximately 24 inches of concrete appeared to be mostly intact and only broken up due to the mechanical removal process during coring operations.

Similarly to the vertical concrete core LC-24-01, reinforcing steel was encountered; however, it was much smaller in size within the horizontal concrete core LC-24-02 and did not result in termination of the core.

Table 2: Summary of Core Investigation

Boring No.

Direction of Core

Approx. Ground Surface Elevation

(ft)

Core Termination

Depth (ft)

Approx.

Termination Elevation (ft)

Elevation (ft) Core Length

(ft)

LC-24-01 Vertical 525.2 14.6 510.6 --- ---

LC-24-02 Horizontal --- --- --- 522.63 3.3

3.3 EXISTING RETAINING WALL

Based on the SOW, we understand it was expected an existing retaining wall foundation may be present extending from the existing nose pier to the start of the land side guidewall. Drawing No. M-L-19-2 20/5 from the Drawing Set Mississippi River Lock & Dam No. 19 New 1200-ft Lock Concrete Removal – Existing

Retaining Wall (PDF A02.02) provides detailed information about the retaining wall prior to removal in 1958 during construction of the existing lock. Based on this drawing, the retaining wall was approximately 53 feet tall with a top elevation of 523.2 ft and approximately 26 feet wide at the bottom with a bottom elevation of 470.2 ft. Along the land wall, the entirety or portion of the retaining wall are shown to remain;

however, as you continue into the extents of the lock navigational path, the retaining wall is either shown as being removed in its entirety (Section E-E) or to the same elevation as the natural rock (Section D-D). It is not clear from this drawing the extent entire removal compared to the removal to the same elevation as natural rock was completed.

Boring LB-24-02 was performed within the estimated footprint of the previous retaining wall foundation as shown on the Boring Location Plan in Appendix A. Our boring did not encounter concrete and instead initially encountered the bedrock surface at an elevation of 473.0 ft. Based on our review of the drawing referenced in the previous paragraph, we anticipated excavation operations for removal of the retaining wall’s foundation to extend to a depth of 470.2 ft. Based on this information, the retaining wall may have been constructed with its base at varying elevations depending on the bedrock elevation and therefore the ground elevation (bedrock/remaining concrete) may vary along the previous retaining wall’s alignment.

3.4 OVERWATER DRILLING CONDITIONS

A brief review of the subsurface materials encountered at the boring locations completed overwater and river conditions during the investigation are presented in the following subsections. Specific detailed stratigraphy of the subsurface materials encountered in our boring locations is shown on the individual

Boring Logs in Appendix C.

3.4.1 ALLUVIAL SOILS

We encountered alluvial soils at Boring LB-24-03 extending to the refusal depth of 7.8 feet below the top of riverbed material. The alluvial soils generally consisted of clayey sand with a thin layer (approx. 1 inch) of lean clay at approximately two feet below the top of riverbed material. The alluvial soils exhibited

Standard Penetration Test (SPT) N-Values ranging from 7 to 9 blows per foot (bpf), indicating a loose relative density.

3.4.2 BEDROCK

We encountered refusal at each of the seven (7) overwater borings performed during this investigation.

Within the proposed new sill footprint, auger refusal occurred between elevations of 462.3 and 471.8 feet with the bedrock surface elevation decreasing from upstream to downstream. Within the proposed new river wall extension, refusal occurred at elevations of 471.6 and 473.7 feet with a similar trend as observed with the sill footprint with the bedrock surface elevation decreasing as you proceed downstream.

After refusal was encountered, rock coring was performed in each of the three (3) sample borings to sample the refusal materials. Rock coring was performed to a maximum depth of 50.9 feet below the riverbed surface. A summary of auger refusal depths and boring termination depths is provided in Table 3.

Table 3: Summary of Boring Refusal/Termination Depths

Boring No.

Approx. Ground

Surface Elevation (ft)

Auger Refusal

Depth (ft)

Approx.

Refusal

Elevation (ft)

Boring Termination

Depth (ft)

Approx.

Termination Elevation (ft)

Water Elevation

(ft)

LB-24-01A 471.6 0.0 471.6 50.1 421.5 518.0

LB-24-02 473.0 0.0 473.0 47.2 425.8 517.9

LB-24-03 481.5 7.8 473.7 50.9 430.6 517.6

P-1 462.3 0.0 462.3 0.0 462.3 517.7

P-2 468.3 0.0 468.3 0.0 468.3 517.7

P-3 465.6 0.0 465.6 0.0 465.6 517.7

P-4 471.8 0.0 471.8 0.0 471.8 517.4

The sampled refusal materials was generally classified as an upper layer of fossiliferous, shaley limestone with dolomite, chert, and occasional thin (up to 0.3 feet thick) shales seams and one moderately thick

(approx. 0.9 to 1.6 feet thick) shale seam at an elevation of 466.1 to 467.7 feet in Boring LB-24-01A, 466.7 to 467.8 in Boring LB-24-02, 467.7 to 468.8 in Boring LB-24-03. Recovery values for rock core sampling of this upper layer was 100 percent with Rock Quality Designation (RQD) values ranging from 48 to 70 percent

(poor to fair quality) from the bedrock surface down to a depth of 13.1 feet below the top of rock elevation in Boring LB-24-03.

Underlying the fossiliferous limestone, the bedrock was classified as limestone and dolomite with chert.

Recovery values for rock core sampling continued to be 100 percent with greater RQD values ranging from

80 to 100 percent (good to excellent quality) extending to the termination depths.

Table 4 – Summary of Rock Coring

Boring No.

Core Run

No.

Depths Top Elev. (ft) Recovery (%)

RQD Values

Relative Quality

LB-24-01A

1 0.0 – 4.8 471.6 100 48 Poor

2 4.8 – 9.8 466.8 100 82 Good

3 9.8 – 15.0 461.6 100 83 Good

4 15.0 – 20.0 456.6 100 94 Excellent

5 20.0 – 25.0 451.6 100 88 Good

6 25.0 – 30.0 446.6 100 88 Good

7 30.0 – 35.1 441.5 100 94 Excellent

8 35.1 – 40.0 436.6 100 90 Excellent

9 40.0 – 45.0 431.6 100 88 Good

10 45.0 – 50.1 426.6 100 94 Excellent

Boring No.

Core Run

No.

Depths Top Elev. (ft) Recovery (%)

RQD Values

Relative Quality

LB-24-02

1 0.0 – 2.2 473.0 100 68 Fair

2 2.2 – 7.2 470.8 100 66 Fair

3 7.2 – 12.2 465.8 100 94 Excellent

4 12.2 – 17.2 460.8 100 86 Good

5 17.2 – 22.2 455.8 100 82 Good

6 22.2 – 25.3 450.8 100 94 Excellent

7 25.3 – 27.2 447.7 100 89 Good

8 27.2 – 32.2 445.8 100 80 Good

9 32.2 – 37.2 440.8 100 100 Excellent

10 37.2 – 42.2 435.8 100 96 Excellent

11 42.2 – 47.2 430.8 100 100 Excellent

LB-24-03

1 7.8 – 10.9 473.7 100 68 Fair

2 10.9 – 15.9 470.6 100 58 Fair

3 15.9 – 20.9 465.6 100 70 Fair

4 20.9 – 25.9 460.6 100 90 Excellent

5 25.9 – 30.9 455.6 100 86 Good

6 30.9 – 35.3 450.6 100 100 Excellent

7 35.3 – 35.9 446.2 100 100 Excellent

8 35.9 – 40.9 445.6 100 92 Excellent

9 40.9 – 45.9 440.6 100 100 Excellent

10 45.9 – 50.9 430.6 100 100 Excellent

3.4.3 RIVER LEVEL

During drilling operations, the river level water elevation ranged from approximately 517.4 feet to 518.0 feet. Based on information provided, we understand the water level at the site may vary considerably but is generally maintained close to EL 518.2 ft MSL 1912 Datum matching the Upper Pool Elevation of Dam

19.

4.0 LABORATORY TESTING

ABCD subcontracted with Stantec to perform laboratory unconfined compressive strength testing on select rock core samples in general accordance with ASTM D7012, Method D and select concrete core samples in general accordance with ASTM C42. The test results are summarized in Tables 5 and 6, and the test reports are included in Appendix E.

Table 5: Summary of Unconfined Compressive Strength of Rock Core Results

Boring No.

Sample Depth (feet)

Unconfined Compressive Strength (psi)

Poisson’s Ratio

Young’s Modulus (psi)

Rock Classification

LB-24-01A 4.8 – 5.2 5,290 0.38 0.71 x 106 Shale, dark gray, moderately hard

LB-24-01A 12.1 – 12.5 3,070 0.37 4.00 x 106 Dolomite/Shale, tan/light gray, moderately hard

LB-24-01A 21.0 – 21.4 12,180 0.35 9.83 x 106 Limestone, light gray, hard

LB-24-02 12.2 – 12.6 4,230 0.48 3.83 x 106 Limestone/Dolomite, tan/light gray, hard

LB-24-02 24.9 - 25.3 7,780 0.38 5.78 x 106 Dolomite/Shale, light gray, moderately hard

LB-24-02 42.3 – 42.7 6,990 0.46 4.66 x 106 Dolomite/Shale, tan/light gray, moderately hard

LB-24-03 9.1 – 9.5 14,260 0.32 10.23 x 106 Dolomite/Shale, tan/light gray, moderately hard

LB-24-03 14.9 – 15.3 6,970 0.49 5.01 x 106 Dolomite, tan/light gray, moderately hard

LB-24-03 37.6 – 38.0 13,410 0.35 6.64 x 106 Dolomite, gray, hard

AVG 8,240 0.40 *6.25 x 106

*Average of Young's Modulus does not include LB-24-01A 4.8 - 5.2 feet Shale Rock Core Sample

Table 6: Summary of Unconfined Compressive Strength of Concrete Core Results

Boring No.

Sample Depth

(feet) Unconfined Compressive

Strength (psi)

LC-24-01 3.9 – 4.4 5,480

LC-24-01 11.5 – 12.1 6,540

AVG 6,010

5.0 GEOTECHNICAL DESIGN AND CONSTRUCTION RECOMMENDATIONS

The conclusions and recommendations in this report have been derived by relating the general principles of the discipline of geotechnical engineering to the project information outlined in Section 1.1 of this report.

If this information is not correct or has been updated, we should be contacted to review the corrected or updated information and confirm the recommendations presented herein are appropriate. Because changes in surface, subsurface, and climatic conditions can occur, the use of this report should be restricted to this specific project.

5.1 IN-THE-WET AND IN-THE-DRY CONSTRUCTION DISCUSSION

5.1.1 GENERAL

We understand USACE is not restricting the means and methods of the contractor at this time and both in-the-wet and in-the-dry methods are currently acceptable as long as schedule constraints within winter shutdowns are met for work on the project.

We understand the application of in-the-wet technology was embraced by USACE starting in the late 1990s and has been employed with mixed success at several significant navigation projects. With in-the-wet construction, foundation elements are generally constructed from the decks of work barges, and divers are employed to cut off casings above critical elevations after foundation installation. The process often involves large, hollow precast concrete elements, called “shells”, mounted over the tops of the cut off foundation elements; the open space between the foundation elements and the shells are then filled with concrete installed by the tremie method. In-the-wet construction requires specialized heavy lift barges.

In-the-dry construction consists of constructing a cofferdam to allow for dewatering of the project site. The structural elements can then be constructed using typical means and methods for land construction.

5.1.2 IN-THE-WET – RIVER WALL EXTENSION

It is understood MVR envisions a Base Bid consisting of repairing the existing nose pier and constructing the river wall extension entirely in-the-wet over the duration of two winter shutdowns. There is precedent for this type of construction, exemplified by the Charleroi Lock’s work over the past 30 years. Powerpoint slides presented at the recent Lock 19 construction Industry Day dated 7 Nov 2024 show photos from a previous project where precast panels were installed in-the-wet along a lock wall. The recently updated

Lock 19 design drawings (dated 23 October 2024) do not include any details for the precast panels and do not indicate how these panels would receive lateral and vertical support. The process typically would involve several critical steps:

1) Riverbed soil material, rock, and concrete will be removed to the specified limits - an activity MVR envisions could be completed in the first winter navigation shutdown.

2) Divers will then install anchors for steel support frame - Due to the difficulty of drilling anchor holes accurately in deep, cold water on uneven surfaces by divers, it is very likely the as-built locations of the anchor holes will then have to be provided to the frame designer and fabricator before fabrication can be completed.

3) A 3D map of the resulting surfaces and as-built locations of anchor holes would have to be created in order for the design and fabrication of both the required steel support frame and precast panels.

4) The steel support frame would be fabricated on dry land.

5) The steel support frame would then be installed in-the-wet to provide these supports. Such a frame would be fixed in place by anchors into both the rock and the existing river wall concrete.

It is difficult to envision all of the above steps being accomplished within the duration of a single winter shutdown period. However, if steps 1 through 3 can be completed during the Year 1 shutdown, then step

4 can be completed during the non-shutdown period, and step 5 could take place during the Year 2 shutdown.

It is assumed more design and construction details will be specifically addressed future submittals. The schedule MVR presented to the construction industry during the industry day appears optimistic given the short duration of allowable winter navigation shutdowns together with the experiences observed for other similar attempts to construct large concrete navigation with complex geometries in-the-wet. An alternate approach is discussed below.

5.1.3 IN-THE-DRY – RIVER WALL EXTENSION

The application of in-the-dry was also considered. A series of large diameter drilled shafts installed into the underlying bedrock could be constructed within the proposed new river wall extension footprint during short navigation shutdowns. A sheet pile “Combi wall” cofferdam laterally supported by struts connected to the drilled shafts and the existing nose pier concrete would be constructed parallel with the lock wall with its upstream end wrapping around the upstream side of the river wall pier. During and after completion of this work, commercial navigation would have to be restricted to no more than two barges wide to reduce to the greatest extent possible the likelihood of a collision between upbound or downbound barges and the temporary cofferdam, which will likely extend at least 10 feet into the lock navigation path.

It is understood the site currently does not have a tow kevel system, which, if available, would be a secure method for keeping all navigation traffic hugging the land wall. Therefore, the use of helper towboats would be necessary in all navigation conditions. This is a conventional construction method employed in deep water for the installation of bridge piers (Figure F1 in Appendix F).

The ends of the cofferdam sheet piling would be connected to the existing concrete river wall using “Pile

Pro” WOM type connectors (Figure F2 in Appendix F) welded to steel plates with pre-drilled holes (note for clarity, Figure F2 shows the WOM connector welded to a steel pipe pile). The anchor bolt holes for the pile pro/plate would receive anchor bolts which would be installed within a dewatered limpet box / coffer box

(Figures F3 and F4 in Appendix F). A limpet box is a prefabricated cofferdam, often a three-sided steel structure that can be precisely positioned below the water line at the required bulkhead recess location.

After precise alignment is completed, water is then carefully pumped out of the three-sided structure, allowing the external pressure to create a water-tight seal. Conventional construction techniques, albeit within a fairly restricted workspace, can then be undertaken within. This technology can maintain a dry working environment regardless of project duration or variation in the water level.

After connection of the sheet pile/wale system to the wall-mounted Pile Pro/plate fabrications, the bottom of the cofferdam would be filled with tremie concrete. After curing of the tremie concrete is complete, the cofferdam can be dewatered, and the river wall extension can be completed using conventional construction techniques.

5.1.4 IN-THE-WET – SILL

Details have not yet been fully developed per the 23 October 2024 plans, but it is understood MVR intends the sill to be accomplished fully in-the-wet. The construction of the bulkhead sill is identified as Option 1 in the planned construction contract. The removal of rock to the limits shown on drawing sheet BHSILL S-301 will have to be completed before installing the drilled shafts. It is hard to estimate the duration the rock removal will take. Required rock removal limit surfaces will not be directly accessible to geologists for assessment because they will be submerged. Conservative and careful rock removal means and methods will have to be utilized to limit possible overbreak. This will likely slow down the removal process significantly compared to what would normally be possible on dry land. The rock removal may be accomplished during a series of limited navigation shutdowns, or as envisioned by MVR, it would be accomplished entirely during the course of the Year 1 three-month navigation shutdown. Similarly, the planned drilled shafts could be installed individually during a series of seven limited navigation shutdowns, but it is believed MVR plans the drilled shafts to be constructed during the course of the Year 1 or more likely the Year 2 winter three month shutdown.

After the completion of the drilled shafts, a 3D map of the resulting rock surface would have to be created.

This would be required in order for the design and fabrication of both a support frame and the envisioned stay-in-place formwork. Typically, a steel support frame would be fabricated on dry land and installed in the wet to provide these supports. Such a frame would then be fixed in place by anchors into the rock. The entire process of installing these anchors would typically be accomplished by divers. Because of the same challenges and difficulties described above for the river wall extension to drill anchor holes in deep, cold water by divers will also apply for the sill. Again, it is almost certain the as-built locations of the anchor holes will have to be provided to the frame designers and fabricator, as well as the form designer/fabricator before these fabrications can be completed. Add to these tasks the complicated tasks of precisely placing the stay-in-place formwork and then placing the sill concrete via the tremie method. It will be challenging for even an experienced river contractor to complete all of the above steps within the duration of two winter shutdown periods. More than likely Option 2 will extend to a three year duration.

A significant question associated with the MVR’s currently envisioned sill construction plan is the absence of a seal plate. Many, but not all, USACE navigation lock bulkhead sills have embedded steel seal plates. EM

1110-2-2602 (PLANNING AND DESIGN OF NAVIGATION LOCKS) does not address seal plates in bulkhead sills. But the concern is the quality of the sealing surface expected from a sill cast using tremie method. In a submerged tremie concrete placement, laitance can be expected to form on the upper surface. Laitance is soft, weak, water-laden mortar that typically appears on the surface of a submerged concrete placement.

A submerged concrete sill topped by this material generally will not result in a smooth, even, durable concrete surface. Additionally, if a single precast concrete shell is utilized for the proposed Lock 19 construction, anticipated to be approximately two-foot-thick, it could be expected to weigh over a total of

1,500 kips. A custom fabricated steel lifting frame would almost certainly need to be designed to distribute the lifting loads evenly to the shell, and this would add a minimum of 200 kips to the lift. Lifting loads could be reduced by splitting the shell into multiple pieces where the steel lifting frame could also be reduced significantly.

As briefly touched on above, an alternative approach would be to install the sill in-the-wet by placing a series of smaller, match cast precast shell elements. Each element would typically require no less than three points of support to ensure the shells are properly aligned in all three directions; thus, several drilled shafts of lower capacity would need to be installed in addition to the seven drilled shafts MVR has planned for resisting structural loading. Precise mapping of the tops of each support shaft would be required to design the corresponding surfaces on the bottoms of the shells. After careful placements of the precast shells on their support piles, the voids under the shells would be filled with tremie concrete. These precast shell elements could each have an embedded stainless steel seal plate on their top surfaces. Properly aligned vertically and horizontally, these steel plates would provide a superior sealing surface for the stacked bulkheads than the currently planned tremie concrete sill placement. Grout socks would be preplaced in vertical recesses between the match cast elements. These would be filled with grout after the concrete for the shells is placed via tremie, providing a cutoff for potential leakage between adjacent shells.

5.1.5 IN-THE-DRY – SILL

The construction of the sill cannot proceed in-the-dry in a similar manner as the river wall extension because the sill spans the lock chamber; thus, there is far tighter time pressure for this construction element due to the need to pass traffic through the lock chamber for approximately nine months each year. A combi wall cofferdam, no matter how cleverly designed, simply cannot be installed and removed in a period of three months. When work inside a cofferdam is added to the schedule, a minimum one year shut down would be a realistic estimate. Obviously, this would not be acceptable to the commercial navigation industry.

5.1.6 IN-THE-DRY BULKHEAD RECESS ON THE FACE OF THE EXISTING LAND WALL

Work associated with the land wall bulkhead recess can be constructed within a limpet cofferdam / cofferbox, as MVR’s 23 October 2024 plans and recent presentation during the Industry Day have shown.

Removal of the existing concrete would likely be accomplished using the diamond wire cutting method.

Diamond wire cutting employs a motor-driven main wheel, which guides a diamond wire along its cutting path. The wire is looped through a series of pulleys and continuously moves in a single direction. The precision concrete cutting technique is achieved by abrasive cutting, where the diamond-embedded wire grinds away at the material as the wire is pulled or pressed against it, creating a narrow cut or groove. After removal of each block of the existing concrete is completed, conventional construction of the slot can proceed within the limpet box. MVR may decide to prefabricate the bulkhead recess assembly in a precast yard, and the entire slot assembly could be installed within the protective space bounded by the limpet box. Alternately workers can drill holes for dowels and anchors to support the designed embedded metals.

Normal concrete formwork can then be installed, and conventional or high strength concrete can be placed in the dry. See Figure F3 and F4 in Appendix F for examples of a limpet dewatering box.

5.2 BEDROCK EXCAVATION

Based on the project information and our investigation, approximate maximum excavation depths for mass rock removal for the sill will be approximately 50 to 60 feet below the water level to an Elevation of 465.8.

We anticipate up to approximately 6 feet of rock removal on the upstream extent of the sill to reach this design bearing elevation.

We anticipate the bearing depth of the river wall extension to be 466.7 feet to match the bearing depth of previous retaining wall. Based on this assumption, the approximate maximum excavation depths for the river wall extension may extend down to approximately 51.5 feet below the water level, with up to approximately 7 feet of rock/concrete removal with up to approximately 8 feet of soil material overlying the bedrock outside of the extents of the current river wall nose pier. See Table 7 with specific boring refusal elevations and ground surface elevations at each investigated location.

Table 7: Summary of Boring Refusal Elevation and Ground Surface Elevation

Location Boring No.

Approx. Refusal

Elevation (ft) Approx. Ground Surface

Elevation (ft)

Sill

LB-24-01A 471.6 Same as Refusal Elevation

P-1 462.3 Same as Refusal Elevation

P-2 468.3 Same as Refusal Elevation

P-3 465.6 Same as Refusal Elevation

P-4 471.8 Same as Refusal Elevation

River Wall Extension LB-24-02 473.0 Same as Refusal Elevation

LB-24-03 473.7 481.5

It is anticipated the bulk of rock will be removed in-the-wet utilizing a ripper and hammer or a combination tool, while tighter tolerance rock removal will likely utilize grinding, milling, or cutting. Typically, less competent intervals of fractured limestone bedrock or shale bedrock, may be removed with a large bulldozer equipped with a single-tooth ripper; however, due to the depth of excavation and the minimal presence of less competent intervals, specialty equipment and procedures as identified above will be required. Additionally, due to proximity of rock to existing structures, we do not anticipate blasting will be feasible for this project. An additional method for rock removal that can be considered that acts similarly to blasting is the use of a demolition grout such as Dexpan. This non-explosive expansive demolition grout when placed into a plastic/rubber tubing and inserted into a predrilled hole underwater can exert up to

18,000 psi of expansive pressure to assist with presplitting of rock for excavation.

We recommend this deep-water excavating be accomplished by an experienced contractor in a controlled manner in accordance with applicable local and state laws. As previously stated, due to the proximity of existing structures to the site, we do not anticipate blasting will be feasible for this project. Additionally, line drilling and/or pre-splitting using demolition grout may be necessary along the perimeter to control overbreak of the rock mass to remain in-place. Care should be taken to prevent excessive disturbance (i.e., disturbing the rock below the design excavation level). If a demolition grout is used, the demolition plan should specifically describe the spacing/depth of holes near the base or horizontal extents of the excavation for this protection. Bedrock damaged by excessive disturbance in foundation areas may have to be undercut and replaced. The contractor should provide a site-specific demolition plan and existing structure monitoring plan for approval prior to construction.

It should be noted, with a planned bottom of sill elevation of 465 feet, it is likely foundation stay-in-place forms/casts will need to extend below the bottom of sill elevation on the downstream extent of the sill to limit loss of tremie concrete during concrete placement.

5.3 NOSE PIER DEMOLITION

Based on the Lock 19 Nose Pier Replacement and Bulkhead Recess, USACE MVR Industry Day Powerpoint

Presentation, dated 7 Nov 2024, Slide 40/64, the currently proposed demolition extent of the damaged concrete located on the nose pier is shown to extend between 6½ and 24 feet off the river wall into the existing monolith. See Figure A4 in Appendix A for the currently identified demolition and extension limits.

Based on our observations of the concrete samples recovered from the vertical concrete core LC-24-01 and the horizontal concrete core LC-24-02, we believe the currently proposed demolition extents should remove the damaged concrete observed at the river wall nose pier. If during demolition damaged concrete extends beyond these limits, the contractor should be prepared to extend the demolition extents to ensure sound concrete exclusively remains.

Recovered samples from Boring LB-24-02, completed within the footprint of the previous submersed foundation wall, did not encounter concrete. At the refusal depth of approximately 45 feet (Elev. 473 feet), limestone bedrock was encountered and sampled. As previously mentioned in Section 3.3, concrete may exist within other portions of the retaining wall footprint outside of our investigated location.

5.4 SHALLOW FOUNDATIONS

We understand at the 30% design phase, the river wall nose pier extension will have a total weight of approximately 7,500 kips and an approximate footprint area of 850 square feet. Additionally, the sill will have a total weight of approximately 3,900 kips and an approximate footprint area of 1,650 square feet.

ABCD believes the sill may be supported by shallow mat foundations bearing on limestone bedrock at approximate elevations of 460 to 466 feet depending on the elevation of bedrock encountered during construction. Additionally, ABCD believes the river wall nose pier extension may be supported by shallow mat foundations bearing on limestone bedrock at an approximate elevation of 466.7 feet. Based on these bearing elevations, we anticipate the majority of the foundation excavation will penetrate through the existing moderately thick shale seam (approx. 0.9 to 1.6 feet thick). If the foundation excavation does not extend through the moderately thick shale seam, that was penetrated at elevations between 466.1 and

467.7 feet, excavations should extend further to bear on a uniform surface of limestone bedrock. Given the relatively low bearing pressure design and extending foundations through the moderately thick shale seam, we do not anticipate settlement concerns due to shale layers for these structures. Additionally, we do not anticipate seepage concerns within the generally impervious limestone or shale bedrock layers.

The mat foundations bearing on limestone bedrock may be designed for an allowable bearing pressure of

10 kips per square foot (ksf) and a modulus of elasticity/deformation of 5 x 106 psi. These values were selected based on the lithology, laboratory testing, and quality of the underlying bedrock observed in our test borings at the anticipated bearing elevations. We conservatively estimate the coefficient of friction between the base of the foundations and the bearing materials to be 0.5 for concrete against bedrock. Use a minimum code-specified factor of safety or load and resistance factors when calculating sliding resistance to resist lateral loads.

Uplift loads as a result of buoyancy should also be considered for the below water structures. Rock anchoring of the superstructure to the underlying rock may be utilized to resist these loads, if necessary.

5.5 DRILLED SHAFT FOUNDATIONS

Currently the sill is designed to include seven drilled shafts to provide lateral support for the bulkhead. The shafts will be 36-inch outside diameter concrete-filled steel casing shafts with W12x190 structural steel.

The top of drilled shafts are planned for Elevation 476.0 feet with the steel casing extending beyond the bottom of the sill (Elev. 465.8) to an elevation of 462.0 feet. Beneath the casing, the drilled shaft will reduce to a 24-inch outside diameter rock socket filled with concrete with the bottom of rock socket extending to an Elevation of 452.0 feet.

Based on the results of this investigation, we recommend drilled shaft foundations bear within limestone/dolomite bedrock beneath the mat foundation. We understand USACE is completing the lateral analysis and will determine the final design bearing elevation for the drilled shafts sufficient for resisting lateral loading. The top of rock elevation across the sill varies. We developed estimated soil and rock parameters for drilled shaft design which are provided in Table 8. The reported values in Table 8 were developed based on characterization of the underlying limestone bedrock based on Geotechnical Boring

LB-24-01A and Probe Borings P-1 through P-4. The stratigraphy presented in Table 8 was estimated based on the materials encountered in our borings. Specific borings should be referenced and approximate rock surface elevation interpolated for the individual foundation designs and should be considered approximate.

Boring refusal elevations are provided for reference within Table 8.

Table 8: Generalized Drilled Shaft Design Parameters –

Material Designation Approximate

Elevation* (ft)

Allowable Bearing

Pressure (psf)

Qu

(psi) Krm

(in./in.)

Avg.

RQD

Limestone/ Dolomite with Shale Seams 464 to 466 --- 2,000 0.0001 65

Limestone/ Dolomite 425 to 464 100,000 6,000 0.0001 90

*Surface elevation of bedrock encountered as low as 462.3 in Probe Boring P-1 and may be lower outside of investigated locations.

6.0 QUALIFICATIONS OF RECOMMENDATIONS

Our recommendations for this report were developed using the subsurface information obtained from the test borings advanced across the site. The test borings only depict the subsurface conditions at the specific location and time at which they were made. The subsurface conditions at other locations on the site may differ from those occurring at the boring locations.

The conclusions and recommendations contained in this report were based on the available subsurface information, the project information provided, and the assumptions previously stated. Revisions in the plans for the proposed construction from those anticipated in this report should be brought to the attention of an ABCD geotechnical engineer or his representative to determine whether any changes to the recommendations are necessary. If deviations from the noted subgrade conditions are encountered during the construction, they should also be brought to the attention of the geotechnical engineer.

The scope of our geotechnical services did not include assessment or investigation for the presence or absence of hazardous or toxic materials in the soil, groundwater or surface water within or beyond the site studied. Any statements in this report or indicated on the test boring logs regarding odors, staining of soil or other unusual conditions observed are strictly for the information of our client.

Our professional services were performed, our findings obtained, and our recommendations prepared in accordance with generally accepted geotechnical engineering principles and practices. ABCD is not responsible for the conclusions, opinions, or recommendations made by others based upon the data included herein.

APPENDIX A

GEOLOGIC MAP

SITE VICINITY PLAN

BORING LOCATION PLAN WITH EXISTING FEATURES

RIVER WALL EXTENSION – PROPOSED WORK EXTENTS

NOT TO SCALE

JOB NO: 70023.24

Geologic Map LEGEND

REVIEWED BY: BDK

Fi gu re A

1CLIENT: USACE

ADDRESS:

Rock Island District 1500 Rock Island Dr Rock Island, IL 61204

Lock 19 Nose Pier Replacement and Bulkhead Recesses Project

Keokuk, IA

11/26/2024 DRAWN BY: DLH

N

Clarksville

PROJECT LOCATION:

Lock 19

Keokuk, IA

Fi gu re A

2CLIENT: USACE

ADDRESS:

Rock Island District 1500 Rock Island Dr Rock Island, IL 61204

Lock 19

IMAGE SOURCE: Google Maps, 08/07/2024

NOT TO SCALE

JOB NO: 70023.24

Site Vicinity Plan LEGEND

Nose Pier Replacement and Bulkhead Recesses Project Keokuk, IA

DATE: 11/26/2024 DRAWN BY: BK REVIEWED BY: NL

N

Clarksville

Iowa

Illinois

PROJECT LOCATION:

Lock 19

Missouri

Fi gu re A

3CLIENT: USACE

ADDRESS:

Rock Island District 1500 Rock Island Dr Rock Island, IL 61204

Lock 19

Revised Boring Location

LB-24-02

NOT TO SCALE

JOB NO: 70023.24

Boring Location Plan w/ Existing Features LEGEND

Nose Pier Replacement and Bulkhead Recesses Project Keokuk, IA

DATE: 11/26/2024 DRAWN BY: BK REVIEWED BY: NL

Clarksville

LB-24-02 Revised Location

Source: - Lock 19 Nose Pier Replacement and Bulkhead Recess, USACE MVR Industry Day Powerpoint Presentation, dated 7 Nov 2024. Slide 40/64

NOT TO SCALE

JOB NO: 70023.24 River Wall Extension - Proposed Work Extents LEGEND

Fi gu re A

4CLIENT: USACE

ADDRESS:

Rock Island District 1500 Rock Island Dr Rock Island, IL 61204

Lock 19 Nose Pier Replacement and Bulkhead Recesses Project

Keokuk, IA

DATE: 11/26/2024 DRAWN BY: BK REVIEWED BY: NL

Clarksville

APPENDIX B

FIELD CLASSIFICATION SYSTEM

SOIL CLASSIFICATION CHART

FIELD PROCEDURES

FIELD CLASSIFICATION…