Supplemental Data SLDW Feasibility Study 6-23-21.pdf

20212488.001a June 21, 2021 © 2021 Kleinfelder www.kleinfelder.com

SPRING LAKE DAM PEDESTRIAN WALKWAY

FEASIBILITY STUDY

UNITED STATES FOREST SERVICE

OZARK - ST. FRANCIS NATIONAL FOREST

YELL COUNTY, ARKANSAS

KLEINFELDER PROJECT 20212488.001A

JUNE 21, 2021

Copyright 2021 Kleinfelder All Rights Reserved

ONLY THE CLIENT OR ITS DESIGNATED REPRESENTATIVES MAY USE THIS DOCUMENT AND ONLY FOR THE SPECIFIC

PROJECT FOR WHICH THIS REPORT WAS PREPARED.

http://www.kleinfelder.com/

USFS, AR – SPRING LAKE DAM WALKWAY

KLEINFELDER JOB NUMBER 20212488.001A

i

TABLE OF CONTENTS

1. EXISTING CONDITIONS.................................................................................................................... 1-1

1.1 EXISTING CONDITION OF WALKWAY ................................................................................................ 1-1

2. PROPOSED CONDITIONS ................................................................................................................ 2-1

2.1 DESIGN CRITERIA .......................................................................................................................... 2-1

2.2 SUPERSTRUCTURE ALTERNATIVES .................................................................................................. 2-1

2.2.1 Alternative 1 – No Action ...................................................................................................... 2-1

2.2.2 Alternative 2 – Close Pedestrian Walkway .......................................................................... 2-2

2.2.3 Alternative 3 – Superstructure Rehabilitation ....................................................................... 2-2

2.2.4 Alternative 4 – Spanning Deck Replacement ....................................................................... 2-3

2.2.5 Alternative 5 – Superstructure Replacement ....................................................................... 2-4

3. ADDITIONAL CONSIDERATIONS .................................................................................................... 3-1

3.1 ENVIRONMENTAL CONSIDERATIONS ................................................................................................ 3-1

3.2 CULTURAL RESOURCE IMPACTS ..................................................................................................... 3-1

3.3 CONSTRUCTION SCHEDULE ............................................................................................................ 3-1

3.4 RIGHT-OF-WAY .............................................................................................................................. 3-1

3.5 UTILITIES ....................................................................................................................................... 3-1

3.6 HYDRAULICS .................................................................................................................................. 3-2

3.7 TRAFFIC CONTROL ......................................................................................................................... 3-2

4. RECOMMENDATION ......................................................................................................................... 4-1

4.1 RECOMMENDATION ........................................................................................................................ 4-1

USFS, AR – SPRING LAKE DAM WALKWAY

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LIST OF FIGURES

Figure 1 - Location Map Figure 2 - Transverse Section – Existing Superstructure Figure 3 - Transverse Section – Alternative 3 Figure 4 - Transverse Section – Alternative 4

LIST OF APPENDICES

APPENDIX 1 – TOPSIDE BRIDGE INSPECTION REPORT

APPENDIX 2 – NONDESTRUCTIVE TESTING REPORT

APPENDIX 3 – LOAD RATING MEMO

APPENDIX 4 – ENGINEER’S OPINION OF PROBABLE PROJECT COSTS

USFS AR – SPRING LAKE DAM PEDESTRIAN WALKWAY

1-1

1. EXISTING CONDITIONS

On November 18, 2020, the Kleinfelder NBIS Bridge Inspection team visited the site of the Spring Lake Dam Pedestrian Walkway to conduct a bridge inspection (See Appendix 1).

The walkway is located on top of the outlet dam for Spring Lake in Belleville, Yell County, Arkansas, and is part of the Ozark-St. Francis National Forest. NDT Corporation assisted the Kleinfelder NBIS Bridge Inspection team by conducting nondestructive testing on the walkway superstructure to locate the existing rebar, determine size, spacing and configuration as well as determine the properties of the existing concrete (See Appendix 2).

1.1 Existing Condition of Walkway

The existing 15-span pedestrian walkway consists of a concrete superstructure supported by stacked stone and mortar piers that are located on top of the Spring Lake Dam (See photos 1 and 2). The walkway connects the Spring Lake Recreational Area located at the east end of the walkway to Spring Lake Road on the west end of the walkway. For discussion purposes the spans and piers are numbered from east to west. The walkway is curved along the top of the dam with a centerline radius of approximately 360 feet. The walkway spans approximately 236 feet and has a total length of approximately 283 feet.

The clear span of span 1 is 9.9’, spans two through 14 vary from 13.2 to 13.8 feet with span 14 equal to 8.3 feet. The Spring Lake Dam was constructed in 1937 and it is assumed the walkway was constructed about the same time as the dam.

Photo 1 - Downstream View

1-2

Photo 2 - Upstream View

The fourteen stacked stone and mortar piers extend approximately four feet above the level of the walking surface forming two pilasters with a five foot wide opening between them for the walkway to pass through. The piers are approximately nine feet long at the top of the piers and the width of piers vary from three feet at the top to 4 feet at the top of the dam (See photos 3 and 5). The abutments are the same stacked stone and mortared construction as the piers with return wingwalls. The width of abutment is approximately equal to the length of the piers (See photo 4).

Photo 3 - Typical Pier Photo 4 - Typical Abutment

The walkway superstructure consists of concrete edge beams on each side which support concrete deck panels (See photos 5, 6, and Figure 1). The edge beams are assumed to

1-3 be simply supported by stacked stone and mortar piers and are embedded under the pilasters. The walkway rail system consists of two metal pipe rails spanning between the pilasters with chain link fence extending down from the lower rail to the top of the edge beam/deck. The approximate rail to rail width of the walkway is five feet. The area of the top of each pier between the edge beams has been infilled with concrete.

Photo 5 - Typical Span from Underside

Photo 6 – Typical Span Topside

The Kleinfelder bridge inspection report, dated January 14, 2021, notes the following:

Substructure: The overall substructure is in Fair Condition with no evidence of major movement or settling. Minor mortar cracking and movement noted at stress points caused by the railing risers. Minor staining and efflorescent appears to be coming from the mortar between the stones.

Deck/Superstructure: The overall superstructure is in Poor Condition with concrete scaling, cracking, leaking, and delamination noted in most spans. Some spans have severe spalling and holes through the deck. Said areas have steel plates on the walkway to accommodate pedestrians. A majority of the exterior beams are in good condition;

however, a few beams show signs of cracking and efflorescent staining.

Pedestrian Railing: The overall railing is in Good Condition with minor surface rust along the entire length.

As part of this project a load rating analysis (See Appendix 3) was completed for the existing walkway. The results of the load rating showed the exterior beams were not capable of supporting the current pedestrian design loading of 90 pounds per square foot.

Although the walkway has been able to safely support typical pedestrian loads since its original construction, consideration should be given to load posting the walkway to limit the live load on any given single span of the walkway at one time (i.e. “LOAD LIMIT 1 PERSON ON EACH SPAN AT ONE TIME”). This recommendation considers the current condition and rating of the walkway. The existing bollard at one end and the gate at the opposite end shall be kept in place to restrict walkway use to light foot and bicycle traffic (no motorized vehicles or equipment).

2-1

2. PROPOSED CONDITIONS

Purpose: The primary purpose of the Spring Lake Dam Pedestrian Walkway project is to address structural deficiencies and provide safe pedestrian access over Spring Lake Dam to and from the Spring Lake Recreational Area and Spring Lake Road. The proposed solution should be cost effective with low maintenance over its design life.

Need: The existing walkway superstructure is in poor condition with holes through the deck in some locations.

2.1 Design Criteria

Where applicable, the proposed walkway improvements will be designed in accordance with the following documents:

• The AASHTO LRFD Bridge Design Specifications 9th Edition 2020

• The LRFD Guide Specifications for the Design of Pedestrian Bridges, American Association of State Highway & Transportation Officials, 2nd Edition, 2009 with 2015 Interims

• The AASHTO Manual for Bridge Evaluation, 3rd Edition 2018 with 2020 Interim Revisions

2.2 Superstructure Alternatives

Based upon the current condition of the walkway and its inadequate load carrying capacity, superstructure improvements are recommended. Only superstructure alternatives were investigated as part of this study, substructure evaluation was not included in the scope of services.

Five walkway alternatives were evaluated as part of this Feasibility Study as listed below:

Alternative 1: No action

Alternative 2: Close Pedestrian Walkway

Alternative 3: Superstructure Rehabilitation

Alternative 4: Spanning Deck Replacement

Alternative 5: Superstructure Replacement

2.2.1 Alternative 1 – No Action

The existing walkway deck is in poor condition and is becoming no longer serviceable. If no action is taken, the walkway will continue to deteriorate. Additional deck segments will deteriorate to the point they need to be plated over like previous repairs. The edge beams

2-2 will also continue to deteriorate and at some point, the walkway will need to be closed.

This Alternative is not recommended.

Advantages:

• No direct construction cost

Disadvantages:

• Unknown cost to continue to repair the walkway

• Does not increase the load carrying capacity of the walkway and it does not remove the recommended load posting of the walkway

• Does not increase the service life of the superstructure

• Additional risk to the traveling public due to continued deterioration of the superstructure

2.2.2 Alternative 2 – Close Pedestrian Walkway

This alternative would preemptively close the bridge to pedestrian and bicycle traffic with a physical barrier at each end. This alternative reduces the amount of monitoring that would likely be necessary to maintain safe access if the No Action alternative was selected. Closure will not address the structural deficiencies of the walkway and will result in further deterioration of the structure. This alternative is not recommended.

Advantages:

• Minimal direct cost for barricades and associated fencing

Disadvantages:

• Does not increase the load carrying capacity of the walkway and it does not remove the recommended load posting of the walkway

• Limits recreational access to the area by eliminating the connection provided by the walkway.

• Does not increase the service life of the superstructure

• Possible damage to the dam by falling debris/collapse of the walkway onto the dam

2.2.3 Alternative 3 – Superstructure Rehabilitation

The existing walkway deck panels are in poor condition and are at the end of their service life. The deck should be replaced. However, the results of the load rating indicated the existing edge beams are not capable of supporting pedestrian live loads in accordance with current design codes even if a lightweight deck is used as a replacement option. It is not recommended to place a new deck on the existing edge beams. The existing edge beams can be strengthened with fiber reinforced polymers (FRP) bonded to the faces but this Alternative will cost more than Alternative 4. In addition, this rehabilitation approach would have a reduced service life and not be as aesthetically pleasing. Therefore, superstructure rehabilitation is not recommended.

Advantages:

• Closely maintains the aesthetics of the existing superstructure (FRP repairs would be visible)

• Maintains existing hydraulic opening

• Minimizes demolition and reconstruction to the existing deck panels only

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Disadvantages:

• Requires strengthening of existing edge beams

• Costs more than Alternative 4 but less than Alternative 5

• Shortest service life increase

The preliminary opinion of the probable construction cost for Alternative 3 is $360,000 (See Appendix 4 for cost breakdown). This does not include life cycle costs.

2.2.4 Alternative 4 – Spanning Deck Replacement

This alternative replaces the existing walkway deck with a self-supporting concrete slab spanning between the existing substructure units (See Figure 3). A compressible foam or similar materials would be used to isolate the existing edge beams from the loads applied to the proposed slab superstructure. The existing edge beams would no longer support any structural loads other than their own weight. The existing edge beams would only serve as an architectural fascia for the proposed deck and to anchor chain link portion of the existing railing system. The existing pedestrian rail and associated chain link fence would remain in place and function as it does today. The existing walkway rail to rail width of approximately five feet would be maintained. Aesthetically, the walkway would look very similar to what it does today with the only difference being the thickness of the deck (which will still be thinner than the existing edge beams). To slow the deterioration of the existing structure to remain, the existing spalled edge beams, including those at spans 10 and 15, would be repaired. The cracks in the existing stacked stone and mortar piers and pilasters would also be repaired.

To construct this alternative, the existing watermain would be temporarily supported in place from the existing edge beams and/or pier pilasters. The existing deck panels would be removed with the existing edge beams remaining in place. The concrete infill on the top of each pier would be saw cut and removed between the existing edge beams and a new reinforced concrete pier cap constructed. A new spanning concrete superstructure would be placed between the existing edge beams. The edge beams could be used as formwork for a cast in place alternative or a precast/prestressed stay in place concrete panel could be set with a cast in place composite topping placed on top of it. Further verification of the construction tolerances would be needed as the project moves forward to ensure the proper fit up of the precast units between the existing edge beams and along the curvature of the structure. The existing watermain would be secured to the new bridge deck after construction is complete.

The narrow width, poor condition and low rating capacity of the existing walkway will limit the contractor’s means and methods for constructing the spanning deck replacement alternative. If the contractor utilizes the cast in place option, they will likely either start at the middle portion of the walkway and work their way out toward the abutments in each direction or work from one end of the walkway to the other completing the demolition of the existing deck and construction of the proposed spanning deck in a span by span fashion.

If the precast option is chosen, the contractor is likely to complete the pier work prior to the removal of the existing deck. Like the cast in place option it is anticipated that the contractor would start at the middle of the walkway and work in each direction or work from one end of the walkway to the other. Then they would likely bring in a crane on a

2-4 barge or utilize a larger crane set up on shore to remove the existing deck and place the proposed deck.

Advantages:

• Maintains the aesthetics of the existing superstructure

• Lowest construction cost of the replacement options

• Maintains existing hydraulic opening

• Eliminates the need to remove existing stacked stone and mortar pilasters to remove the existing edge beams

• Restores the full load carrying capacity of the walkway and removes the recommended load posting

• Significantly increases the service life of the superstructure

Disadvantages:

• Adds additional dead load to existing substructures, however, additional compression loading on stacked masonry structures is typically not an issue and can be beneficial

• Possible fit up issues with the precast option due the variability of the edge beams and the curvature of the walkway which will require extra attention during design and construction

• Stripping of the forms for the cast in place option could be challenging for the contractor

The preliminary opinion of the probable construction cost for Alternative 4 is $290,000

2.2.5 Alternative 5 – Superstructure Replacement

This alternative replaces the existing walkway with a cast in place or precast concrete slab approximately six feet wide and ten inches thick (See Figure 4). New pedestrian railings would be constructed and the existing walkway rail to rail width of approximately five feet would be maintained. Aesthetically, the walkway would look very similar to what it does today with the only difference being shallower superstructure and the new pedestrian rails.

To slow the deterioration of the existing substructure to remain, the cracks in the existing stacked stone and mortar piers would be repaired.

To construct this alternative, the existing watermain will need to be removed or relocated temporarily. If required, a temporary watermain could be supported from the existing piers.

The existing superstructure consisting of the concrete deck, and edge beams along with the pedestrian rail and associated chain link fence would be removed. At the existing piers, a portion of both stacked stone and mortar pilasters along with the cast in place concrete infill would be removed. New pier caps would be cast on top of the existing piers and the concrete superstructure would then be constructed. The concrete slab superstructure could be either cast in place or precast. Most contractors will likely choose to use precast to eliminate the need to support, place, and remove the formwork for the cast in place option. If precast slabs are utilized closure pours will be required at each substructure unit.

The existing stacked stone and mortar pilasters would then be reconstructed along with construction of the new pedestrian rails. A new watermain located under the pedestrian walkway would also be constructed as part of the project.

Like Alternative 3, the narrow width, poor condition and low rating capacity will limit the contractor’s means and methods to construct the superstructure replacement alternative.

2-5

If the contractor utilizes the cast in place option, they will likely start at the middle of the walkway and work in each direction or work from one end of the walkway to the other with demolition of the existing and construction of the proposed superstructure taking place in a span by span fashion.

If the precast option is chosen, the contractor may demo everything either starting in the middle or at one end and then complete the pier work from a barge. The contractor would then set the precast and complete the project in a similar fashion the cast in place option.

Advantages:

• Maintains the aesthetics of the existing superstructure

• Increases the existing hydraulic opening

• Restores the full load carrying capacity of the walkway and removes the recommended load posting

• Greatest increase in the service life of the superstructure

Disadvantages:

• Adds additional dead load to existing substructures, however, additional compression loading on stacked masonry structures is typically not an issue and can be beneficial

• Formwork for the cast in place option could be challenging for the contractor

• Requires the removal and reconstruction of a portion of the existing stacked stone and mortar pilasters to remove the existing edge beams and place the new superstructure.

• Highest Construction Cost

The preliminary opinion of the probable construction cost for Alternative 5 is $450,000

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3. ADDITIONAL CONSIDERATIONS

3.1 Environmental Considerations

Environmental impacts are expected to be minimal. Debris shields will be required for demolition to prevent any material from falling into Spring Lake, onto the dam, or the outlet waterway below. It is assumed the contractor will most likely utilize a barge with a crane or other pieces of equipment on it to complete the work. It is assumed this will be permittable. Soil and erosion control measures will be limited to the areas disturbed/impacted by the contractor at the ends of the walkway, lay down and delivery areas and impact areas associated with barge use and transferring equipment and materials on and off the barge.

3.2 Cultural Resource Impacts

The Spring Lake Dam Pedestrian Walkway is a contributing resource to the Spring Lake Recreation Area Historic District (#94001613). A Secretary of the Interior Qualified Architectural Historian was consulted on different options and the final design will need to consider the Secretary of the Interior’s Standards for the Treatment of Historic Properties.

3.3 Construction Schedule

The anticipated construction duration for Alternative 3 and 4 is one construction season assuming the contractor starts in the spring, works through the summer, and completes the project in fall of that same year. The walkway would be closed for the duration of the construction project. The schedule would be dependent upon dam operations such that it would be safe for the contractor to use a barge for crane work and/or to access the underside of the walkway and the piers from boats or barges. The use of a self- supporting temporary work trestle is not anticipated since it is likely cost prohibitive due the depth of the water on the upstream side of the dam. The contractor may opt to construct temporary platforms suspended from and/or supported by the existing substructure units.

3.4 Right-of-Way

The existing right-of-way (R.O.W.) information was not investigated as part of this study.

It was assumed that the forest service owns all of the land adjacent to the walkway that the contractor would need to utilize to complete the proposed alternatives.

3.5 Utilities

The existing walkway carries a 4” water line across the walkway deck. For this study it was assumed the watermain had to be supported in place during construction of the proposed spanning deck replacement alternative (Alternative 4). If the superstructure is to be replaced in its entirety under Alternative 5, a temporary watermain may need to be constructed to maintain flows during construction. If the walkway superstructure is

3-2 ultimately replaced in its entirety it is recommended the watermain be relocated under the pedestrian walking area for safety purposes.

3.6 Hydraulics

Hydraulics were not evaluated as part of the study. For hydraulic purposes, it was assumed the existing low chord elevations on each beam would be maintained. The low chord of the walkway is approximately six feet above the top of the dam spillway.

3.7 Traffic Control

During construction, the walkway will be closed to public pedestrian traffic. Depending upon the contractor’s means and methods, single lane closures or shoulder area closures could be required on Spring Lake Road (Route 35). Due to the curvature of the road and reduced sight distance flaggers may be needed to maintain alternating one-way traffic during the delivery of equipment and materials to the construction site. Allowing the contractor to access and deliver equipment and materials through the Spring Lake recreational area will need to be evaluated as the project progresses. Providing a staging area on the east side of the project could be the preferred location since it is not adjacent to an active roadway. Allowing the contractor options with respect to access will help optimize bidding results.

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4. RECOMMENDATION

4.1 Recommendation

Kleinfelder recommends Alternative 4: Spanning Deck Replacement as it offers the following:

• Restores the full load carrying capacity of the walkway and removes the recommended load posting

• Significantly increases the service life of the superstructure o Safely supports pedestrian loads in accordance with current standards o Durable and low maintenance

• Least expensive long-term solution

• Minimizes the impacts to the historic structure o Maintains the aesthetics of the existing superstructure o Eliminates the need to remove and reconstruct the existing stacked stone and mortar pilasters

• Maintains existing hydraulic opening

• Constructability Advantages - leaving the existing edge beams:

o Allows the contractor more flexibility in terms of access and means and methods to complete the work o Enables the contractor to leave the waterline on the existing structure without disrupting service o Minimizes construction duration

FIGURES

Spring Lake Dam Walkway Ozark-St. Francis National Forest, Arkansas

Dam site

Dam site Project Location

PEDESTRIAN

APPENDIX 1

TOPSIDE BRIDGE

INSPECTION REPORT

#20212488.001A Page i of iii January 14, 2021 © 2020 Kleinfelder www.kleinfelder.com

Topside Bridge Inspection

OZARK-ST. FRANCIS NATIONAL FOREST

BELLEVILLE, YELL COUNTY, ARKANSAS

KLEINFELDER PROJECT #20212488.001A

January 14, 2021

Copyright 2021 Kleinfelder All Rights Reserved

ONLY THE CLIENT OR ITS DESIGNATED REPRESENTATIVES MAY USE THIS DOCUMENT AND ONLY FOR THE SPECIFIC

PROJECT FOR WHICH THIS REPORT WAS PREPARED.

#20212488.001A Page ii of iii January 14, 2021 © 2020- Kleinfelder www.kleinfelder.com

A Report Prepared for:

United States Forest Service

Topside Bridge Inspection of the

OZARK-ST. FRANCIS NATIONAL FOREST

Inspection Date: 11/18/2020

Inspection Team: Michael Falla, Inspector Tim Merrithew, Inspector Michael Barden, Tender

Report Prepared by:

Michael D. Falla, PLS, Dive Team Leader, NBIS Team Leader

Reviewed by:

Tyler A. Turcotte Project Professional

KLEINFELDER

Central Maine Commerce Center 16 Commerce Drive, Suite 2 Augusta, ME 04330

12/10/2020 Kleinfelder Project No 20212488.001A

#20212488.001A Page iii of iii January 14, 2021 © 2020- Kleinfelder www.kleinfelder.com

Section Page

1 EXECUTIVE SUMMARY ................................................................................... B-1

2 GENERAL REMARKS & GENERAL CONDITION ............................................ B-2

3 INSPECTION NOTES …………...…………………………...……………………..B-3

4 PICTURES……………..………………………………………………..……………B-7

#20212488.001A B-1 January 14, 2021

SPRING LAKE DAM PEDEISTRIAN WALKWAY

OZARK-ST. FRANCIS NATIONAL FOREST

1 EXECUTIVE SUMMARY

On November 18th, 2020 the Kleinfelder NBIS Bridge Inspection Team conducted an in-depth, comprehensive visual inspection of the Spring Lake Dam Pedestrian Walkway in the Ozark-St.

Francis National Forest, Belleville, Yell County, Arkansas. The United States Forest Service

(USFS) manages the forest on behalf of the United States Department of Agriculture (USDA).

The Spring Lake Dam Pedestrian Walkway is located on the south end of Spring Lake. The

Pedestrian Walkway is a 15 span pedestrian bridge supported by stone and mortar piers which are attached to the top of the Spring Lake Dam. Because of the bridge pier’s location on the spillway part of the dam, only the upstream side of the piers, upstream exterior beams and underside of the deck were accessible by boat, which was supplied by the Forest Service. The entire topside area of the walkway was visually inspected at National Bridge Inspection Standards

(NBIS) meaning all components were viewed close enough to touch and were sounded with a hammer.

Upstream access to bridge

#20212488.001A B-2 January 14, 2021

2 GENERAL REMARKS & GENERAL CONDITION

The Spring Lake Dam Walkway is oriented east-west. For the purpose of this inspection the spans and piers and were numbered one through fifteen from east to west. The deck consists of three sections (labeled A,B,C from east to west) which are supported by two exterior concrete beams which are embedded into the stone piers. A steel railing is embedded in the stone and motar risers that are supported on each end of the piers. The walkway also supports a small waterline which lays on the upstream side of the deck.

Substructure: The overall substructure is in Fair Condition with no evidence of major movement or settling. Minor mortar cracking and movement noted at stress points caused by the railing risers.

Minor staining and efflorescent appears to be coming from the mortar between the stones.

Typical Span

(Stone & mortar piers, concrete exterior beams, concrete deck, stone & mortar risers with steel hand rail)

#20212488.001A B-3 January 14, 2021

Deck/Superstructure: The overall superstucture is in Poor Condition with concrete scaling, cracking, leaking and delamination noted in most spans. Some spans have severe spalling and holes through the deck. Said areas have steel plates on the walkway to accomodate pedestrians.

A majority of the exterior beams are in good condition, however a few beams show signs of cracking and efflorescent staining.

Pedestrian Railing: The overall railing is in Good Condition with minor surface rust along the entire length.

3 INSPECTION NOTES

East Abutment: Concrete wearing surface has minor scaling and delamination (Picture 3).

Downstream return wing has severe efflorescent staining at mortared joints (Picture 5). Breast wall has severe staining from concrete diaphragm (Picture 4).

Span 1: On the topside of the deck, minor scaling and small areas of delamination. On the underside of the deck leaking and minor staining visible between sections.

Pier 1: Severe scaling and delamination on the top of pier (Picture 6). Slight cracking and efflorescent staining at mortar joints.

Span 2: On the topside of the deck, minor scaling and small areas of delamination. On the

Pier 2: Minor scaling and delamination on the top of pier. Slight cracking and efflorescent staining at mortar joints.

Span 3: On the topside of the deck, minor scaling and small areas of delamination. On the

Pier 3: Slight cracking and efflorescent staining at mortar joints. Severe scaling and delamination on the top of pier.

#20212488.001A B-4 January 14, 2021

Span 4: On the topside of the deck, minor scaling and small areas of delamination. On the

Pier 4: Slight cracking and efflorescent staining at mortar joints. Minor scaling and delamination on top of pier (Picture 9).

Span 5: On the topside of the deck, minor scaling and small areas of delamination. On the underside of the deck leaking and minor staining visible between sections. Full length transverse crack in underside of deck in Section C (Picture 10).

Pier 5: Slight cracking and efflorescent staining at mortar joints. Minor scaling and delamination on top of pier.

Span 6: On the topside of the deck, minor scaling and small areas of delamination. On the

Pier 6: Upstream riser has lift mechanism. (See Picture 11 & 12) Downstream riser severely cracked (Picture 13).

Span 7: On the topside of the deck, minor scaling and small areas of delamination with steel plate

Section B (Picture 14). On the underside of the deck leaking and minor staining visible between sections.

Pier 7: Minor scaling and delamination on top of pier. Slight cracking and efflorescent staining at mortar joints.

Span 8: Heavy scaling and delamination in topside of deck (See Picture 15) Steel plate Section

B (See Picture 16). On the underside of the deck, Section B has severe cracking, leaking and staining.

Pier 8: Slight cracking and efflorescent staining at mortar joints. Minor scaling and delamination

Span 9: Heavy scaling and delamination in topside of deck Section C. Heavy cracking and efflorescent staining of deck Section C (See Picture 18).

#20212488.001A B-5 January 14, 2021

Pier 9: Long vertical crack upstream end of pier propagating from riser-exterior beam interface extending down through five stone courses (See Picture 19). Slight cracking and efflorescent staining at other mortar joints.

Span 10: Upstream and downstream exterior beams have cracking and severe efflorescent leaking and staining (Picture 20 & 21). Section B has severe cracking staining in underside of deck.

Section C has large hole, severe cracking and staining. (See Picture 21 & 22 ) Steel plate over

Section C (See Picture 23).

Pier 10: Slight cracking and efflorescent staining at mortar joints. Minor scaling and delamination

Span 11: On the topside of the deck, minor scaling and small areas of delamination. Section C has severe cracking staining in underside of deck. Steel plate over Section C.

Pier 11: Slight cracking and efflorescent staining at mortar joints. Minor scaling and delamination

Span 12: Heavy scaling and delamination in topside of deck Section A.

Pier 12: East side of the pier has horizontal crack between the second and third stone course

(See Picture 25). Slight cracking and heavy efflorescent staining at mortar joints. Full length horizontal crack upstream end at pier-riser interface.(See Picture 26). Slight cracking and efflorescent staining at other mortar joints.

Span 13: On the topside of the deck, minor scaling and small areas of delamination. On the

Pier 13: East side of the pier has horizontal crack between the sixth and seventh stone course.

Slight cracking and heavy efflorescent staining at mortar joints. Minimal scaling and delamination

Span 14: On the topside of the deck, minor scaling and small areas of delamination. On the

#20212488.001A B-6 January 14, 2021

Pier 14: East side of the pier has horizontal crack between the third, forth and fith stone course.

(See Picture 27). Slight cracking and heavy efflorescent staining at mortar joints. Severe efflorescent staining on downstream end of pier.

Span 15: Has a 6”-8” depth overlay patch over the entire span topside. (See Picture 28 & 29).

Section A is completely failed with the stay in place forms visible (See Picture 30 & 31). Both ends of the upstream exterior beam have heavy cracking and efflorescent leaking and staining (Picture

32).

West Abutment: Concrete wearing surface has heavy scaling and delamination (Picture 35).

Downstream return wing has severe efflorescent staining at mortared joints. Breast wall has severe staining from concrete diaphragm (Picture 33).

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4 PICTURES

Picture 1 Upstream View

Picture 2 Downstream View

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Picture 3 Top of East Abutment

Picture 4 Upstream side East Abutment

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Picture 5 Downstream side East Abutment

Picture 6 Top Pier 1 (note scaling and delamination)

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Picture 7 East side Pier 3 (note typical efflorescent at mortar joints)

Picture 8 West Side Pier 4 (note typical efflorescent staining from concrete diaphragm)

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Picture 9 Top Pier 4 (note heavy scaling and delamination)

Picture 10 Span 5 Full length transverse crack Section C

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Picture 11 Pier 6 Upstream Riser has lift mechanism

Picture 12 Pier 6 Gate hardware upstream end of pier

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Picture 13 Pier 6 (note cracking in downstream end)

Picture 14 Span 7 Steel plate Section B

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Picture 15 Span 8 (note heavy scaling and delamination)

Picture 16 Span 8 steel plate Section B

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Picture 17 Underside Span 8 Section B

Picture 18 Underside Span 9 Section C

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Picture 19 Crack in Upstream end of Pier 9

Picture 20 Severe cracking and efflorescent exterior downstream beam Span 10

#20212488.001A B-17 January 14, 2021

Picture 21 Severe cracking and efflorescent exterior downstream beam Span 10

Picture 22 Span 10 Section B & C have extreme cracking, staining, hole

#20212488.001A B-18 January 14, 2021

Picture 23 Span 10 Section C Steel plate

Picture 24 Span 11 Section C

#20212488.001A B-19 January 14, 2021

Picture 25 East side of Pier 12

Picture 26 Pier 12 (Note horizontal crack at pier – riser)

#20212488.001A B-20 January 14, 2021

Picture 27 East side of Pier 14

Picture 28 Span 15 Looking west full length patch

#20212488.001A B-21 January 14, 2021

Picture 29 Span 15 Looking east full length patch

Picture 30 Span 15 underside of large patch cracking and efflorescent in exterior beams

#20212488.001A B-22 January 14, 2021

Picture 31 Close up of patch Span 15

Picture 32 Span 15 Upstream exterior beam

#20212488.001A B-23 January 14, 2021

Picture 33 West Abutment Breast wall

Picture 34 West Abutment (upstream return wing)

#20212488.001A B-24 January 14, 2021

Picture 35 Top of west abutment heavy scaling

Picture 36 West Approach (looking east)

#20212488.001A B-25 January 14, 2021

Picture 35 Top of west abutment heavy scaling

Picture 36 West Approach (looking east)

APPENDIX 2

NONDESTRUCTIVE

TESTING REPORT

NONDESTRUCTIVE TESTING

Pedestrian Walkway Spring Lake Dam

Belleville, Arkansas

Prepared for

Kleinfelder, Inc.

January, 2021

January 5, 2021

Mr. Thomas J Marshall PE Project Manager Kleinfelder, Inc.

77 Sundial Ave. Suite 306 Manchester, NH 03103-7236

Dear Mr. Marshall:

NDT Corporation conducted nondestructive sonic/ultrasonic pulse velocity/impact echo (PV/IE) and ground penetrating radar (GPR) measurements on the pedestrian walkway on top of the dam at Spring Lake, located in Belleville, Arkansas. Field work was conducted on November 18th, 2020. This report presents the results of the PV/IE and GPR measurements to aid Kleinfelder with their structural analysis.

We thank you for the opportunity to perform this work and look forward to being of service to you in the future. If you have any questions or comments, contact the undersigned at 978-563-1327.

Sincerely, NDT Corporation

William Horne

1.0 INTRODUCTION AND PURPOSE Page 1

2.0 LOCATION AND SURVEY CONTROL Page 1

3.0 NONDESTRUCTIVE TESTING METHODS Page 1

4.0 RESULTS Page 2

APPENDIX 1 SONIC/ULTRASONIC METHOD OF INVESTIGATION

APPENDIX 2 GPR METHOD OF INVESTIGATION

1.0 INTRODUCTION AND PURPOSE

Nondestructive sonic/ultrasonic pulse velocity/impact echo (PV/IE) and ground penetrating radar (GPR) measurements on the pedestrian walkway on top of the dam at Spring Lake, located in Belleville, Arkansas. Field work was conducted on November 18th, 2020. The primary purpose of the investigation was to determine the rebar details and concrete strength as part of a condition assessment of the structure.

2.0 LOCATION AND SURVEY CONTROL

The location of the Spring Lake Dam in Belleville, AR is shown on Figure 1.

The pedestrian walkway was marked from east to west spans 1-15, and the 3 segments per span were labeled east to west A-C. Below is a sketch of the labeling system created for this site.

3.0 NONDESTRUCTIVE TESTING METHODS

3.1 Sonic/ultrasonic Impact-echo and Pulse Velocity Testing

The sonic/ultrasonic data were acquired using a system developed by NDT Corporation specifically for testing concrete. This system uses a projectile impact energy source, a 2.5 foot long four sensor array with sensors spaced 0, 0.5, 1.5, and 2.5 feet from the source and a PC for onsite data display for quality assurance as the data is acquired and to archive the data for future playback and processing.

The projectile impact produces stress waves in the concrete; these stress waves are detected by the array of sensors which measure the amplitude of the stress wave in time (time domain data). This data is used to determine the time required for a compressional and shear wave to travel from the impact point to each of the sensors and the frequency content of the recorded signals.

Compressional and shear wave velocity values are calculated using the travel times and the distance between the impact point and sensors. Resonant frequency data (impact-echo) are used to determine concrete thickness and evaluate for internal delamination or voiding.

Sonic/ultrasonic, compressional and shear wave transmission velocity values are used to determine the mechanical characteristics of concrete. The transmission velocity values determine the elastic deformational characteristics of the concrete, including the Young's, Bulk, and shear modulus values as well as Poisson's ratio and a calculated strength value. These values are principally

M20076AR 1

controlled by the presence of cracking, voiding, or weaker strength concrete. Strength values are expected to be within 500 psi of values determined from laboratory compressive strength test. This accuracy is dependent on the degree and attitude of fracturing. Appendix 1 has a more detailed description of the sonic/ultrasonic testing method.

3.2 Ground Penetrating Radar (GPR)

The ground penetrating radar (GPR) method uses a pulsed electromagnetic signal that is transmitted to and reflected by a “target” (re-bar, wire, moisture, etc.) back to the point of transmission. The wave transmission and reflection is dependent on the electrical properties (dielectric constant and conductivity) of the material(s) being investigated. Since these electrical properties are affected by moisture content in the concrete; saturated or moist conditions reflect energy, cause high attenuation and limit signal penetration. Metal reinforcing typically are easily detected because it is high conductivity and produces strong reflections. GPR targets indicate the location and approximate depths of metal targets; it cannot determine the size of reinforcing.

GPR detects reinforcing perpendicular to the direction of the line of coverage, therefore, to detect longitudinal reinforcing a transverse line of data would be collected and to detect transverse reinforcing, a longitudinal line of data would be collected. From this data an average spacing and time to reflector (rebar) is determined. Using the average time to reflector (rebar) an average signal velocity is used to calculate the depth of cover. Appendix 2 has a more detailed discussion of the GPR survey method. Due to the configuration of the wire mesh installed in the concrete slabs the GPR was unable to penetrate beyond the mesh.

4.0 RESULTS

Sonic/ultrasonic Results The following results are from the analysis of the fieldwork completed on November 18th, 2020.

Sonic/ultrasonic records were collected on each segment of each span (unless there was a metal plate over the span) and on each pier. Visual observations noted during data collection indicate many segments have areas of cracking, spalled concrete, and an area of a bulging delamination.

These areas are noted in Table-1 – Sonic/ultrasonic Results Table below in the comments section.

Span Segment

Average Compressional Wave Velocity

(Ft/sec)

Average Shear Wave

Velocity (Ft/sec)

Calculated In-situ Average Strength (PSI) Comments

1 Abutment 9,400 4,500 1,000 Delamination 1 A 11,700 4,800 1,200 Delamination 1 B 13,600 5,900 3,600 1 C 13,900 6,300 3,800 1 Pier 12,000 5,200 1,700 Delamination 2 A 13,000 5,500 2,300 2 B 14,300 6,000 3,100 2 C 12,800 4,800 1,300 2 Pier 14,000 5,700 2,500 Cracking

Table-1 - Sonic/ultrasonic Walkway Results

Span Segment

Average Compressional Wave Velocity

(Ft/sec)

Average Shear Wave

Velocity (Ft/sec)

Calculated In-situ Average Strength (PSI) Comments

3 A 12,300 5,100 1,700 3 B 13,900 6,300 3,600 3 C 14,700 6,300 3,700 3 Pier 14,300 6,100 3,300 Spalled Area 4 A 10,700 5,000 1,500 4 B 13,300 5,600 2,300 4 C 14,800 6,400 3,900 4 Pier 14,000 6,000 3,100 Spalled Area 5 A 11,400 5,300 2,000 5 B 13,500 5,500 2,300 5 C 13,500 5,700 2,700 5 Pier 13,700 5,600 2,300 6 A 13,100 5,600 2,300 Delamination/ Bulging Concrete 6 B 11,400 5,000 1,500 6 C 13,900 5,900 2,900 6 Pier 13,600 5,600 2,300 7 A 13,300 5,600 2,300 7 B 13,300 5,700 2,600 Delamination 7 C 10,400 4,900 1,400 Delamination 7 Pier 13,000 5,200 1,800 8 A 12,600 5,100 1,700 8 B 8 C 12,600 5,100 1,700 8 Pier 14,000 6,900 4,900 9 A 14,400 6,400 1,200 9 B 12,900 5,500 2,200 9 C 12,900 5,900 2,800 Delamination 9 Pier 11,000 4,800 1,200 10 A 12,800 5,400 2,300 Delamination 10 B 12,200 5,300 2,000 10 C 10 Pier 12,800 5,400 2,000 11 A 13,600 5,500 2,200 11 B 13,400 5,200 1,900 11 C 11 Pier 11,000 5,000 1,400 12 A 13,200 5,100 1,700 Delamination 12 B 10,000 4,600 1,000 Delamination 12 C 14,000 6,000 3,200 12 Pier 13,000 6,200 3,300 13 A 12,800 6,100 3,000 13 B 13,200 5,700 2,600 13 C 12,800 5,800 2,600 13 Pier 10,000 5,100 1,500 Spalled Area 14 A 11,500 5,400 2,000 14 B 13,500 6,000 3,000 14 C 13,000 5,200 1,900 14 Pier 13,700 6,000 2,900 15 A 12,000 5,100 1,800 Repaired Area 15 B 10,800 6,000 2,600 Repaired Area 15 C 14,200 6,700 4,600 Repaired Area 15 Abutment 14,000 6,900 5,100

No Testing Steel Plate

No Testing Steel Plate

No Testing Steel Plate

Calculated in-situ strength values under 3,000 PSI are highlighted in red and deemed low strength areas. Some of these low strength values can be attributed to visible cracking, delamination, and/or spalling. Cracking may lower the measured velocity by increasing the direct path for the energy wave to the sensors therefor resulting in lower velocities and lower average compressive strength readings. The data analysis indicates that the concrete pedestrian walkway has an overall average compressional wave velocity of 12,800 feet/sec., and an average shear wave velocity of 5,600 feet/sec. resulting in an average in-situ strength value of 2,400 PSI. Data analysis concludes that 32/42 (71%) of the segments resulted in PSI values under 3,000, and 11/16 (69%) of the piers/abutments were also under 3,000 PSI.

Additional Sonic/ultrasonic measurements were collected on the north face of the north support beams that span from pier to pier. These measurements were collected with assistance of the Forest Service boat, not all the beams were safely accessible due to their location, so 5 representative beams were tested. The results of this testing are listed below in Table-2. The data analysis indicates that the concrete beams that support the pedestrian walkway has an overall average compressional wave velocity of 13,000 feet/sec., and an average shear wave velocity of 5,700 feet/sec. resulting in an average in-situ strength value of 2,600 PSI. Data analysis concludes that 3/5 (60%) of the beams tested resulted in PSI values under 3,000 PSI.

Table-2 - Sonic/ultrasonic Beam Results

Ground Penetrating Radar Results Segments Ground Penetrating Radar data was collected longitudinally across the whole structure in both directions (Line 1 - 1’ south of the pipe along the northern edge & 1’ from the southern edge) with crosslines collected in each span and pier/abutment. GPR data indicates that there is a steel mesh reinforcement mat installed in the segments of the walkway. Due to this mesh being made of expanded metal (not a typical 4”x4” or 6”x6” mesh) the GPR signal could not penetrate around it.

When investigating Span 15 from the boat it was determined that the reinforcing bars located in the haunches are 0.5” (#4) bars with approximately 1-1.5” of cover from the bottom of the haunch.

Haunches were spaced every 2-2.5’. Figure 2 is a cross section sketch of a typical walkway segment. This Figure displays the overall dimensions as well as the depths of the reinforcing located in the walkway concrete. The photograph below was taken under span 15 which shows the deterioration of the concrete in that span as well as exposed reinforcing in the haunch.

Span

Average Compressional Wave Velocity

(Ft/sec)

Average Shear Wave

Velocity (Ft/sec)

Average Strength

(PSI) Comments 4 13,400 5,600 2,300 6 13,700 6,100 3,300 10 13,000 5,400 2,100 12 13,900 6,500 4,000 15 11,200 4,700 1,200 Delamination

Photograph-1 Exposed reinforcing under Span 15

GPR data was collected on the outside face of the support beams that support Spans 4, 6, 10, 12, & 15. Data was collected vertically and horizontally to get the layout of the longitudinal and stirrup reinforcing details. Figure 3 is a sketch of a typical beam with reinforcing layout where the concrete cover does vary somewhat. The photograph below shows both the upstream and downstream beams. The GPR data indicates there are 4 longitudinal bars per beam, with 2 bars ranging from 2-4” from the bottom of the beam and 2 bars approximately 13-14” from the bottom of the beam. Stirrups on average are spaced 16” apart and 1-1.5” in from the upstream face. Due to safety concerns of logistically chipping from the boat at the crest of the dam, no chipping was performed. When comparing the data from the different lines of coverage collected on the multiple beams, it is assumed that the size of the reinforcing bars appear to be #4 bars (0.5-inch diameter) which is consistent with the reinforcing used in the haunches.

Photograph-2 Support Beams Span 6

Ground Penetrating Radar Results over Piers GPR & Sonic/ultrasonic data collected on the piers was inconclusive for the thickness as multiple reflectors were observed, resulting in inconclusive data to determine an overall thickness of the pier slab. Reflectors detected at 2” and 6” were the most common but were not consistently detected on all the piers. GPR data did not detect reinforcing bars/mesh in the pier slabs.

Non Destructive Testing Pedestrian Walkway

Spring Lake Dam Belleville, AR Prepared for

Kleinfelder, Inc.

by

NDT Corporation

Area of Investigation

January

Figure 1

2"4"

0.5"(#4) Transverse bars in Haunches

Expanded Metal Mesh Installed in Concrete Slab at Variable Depth 0.5-2"

1+/-" 2-2.5'

Non Destructive Testing Pedestrian Walkway

Spring Lake Dam Belleville, AR Prepared for

Kleinfelder, Inc.

by

NDT Corporation

Pedestrian Concrete Segment Cross Section

January

Figure 2

Not to scale

Stirrup reinforcing

Horizontal reinforcing

2-2.5"

6+/-"

6+/-"

13-14"

13-14"

2-4"2-4"

1.75- 2.5"

16"

8.5"

1-1.5"

1-3.25"

Non Destructive Testing Pedestrian Walkway

Spring Lake Dam Belleville, AR Prepared for

Kleinfelder, Inc.

by

NDT Corporation

Beam Reinforcing Detail

January

Figure 3

4"

2"

12"

6.5"

APPENDIX 1

SONIC/ULTRASONIC

METHOD OF…