3 West Point Dam- Spillway Tainter Gate Inspection 2020 Report - FINAL_03 24 20.pdf

FINAL

West Point Dam Spillway Tainter Gate Inspection Report

Inspection Performed by St. Louis District Report Prepared by St. Louis District Engineering and Construction Division

For Mobile District Engineering Division

Inspected November 2019

This page was intentionally left blank for duplex printing.

West Point Dam

Spillway Tainter Gate Inspection

Report

United States Army Corps of Engineers Mobile District

Inspected November 2019

Prepared by:

United States Army Corps of Engineers

St. Louis District

Executive Summary The purpose of the engineering inspection of the spillway Tainter gates at West Point Dam is primarily to evaluate structural adequacy in accordance with Engineer Regulation 1110-2-8157, “Responsibility for Hydraulic Steel Structures”.

The West Point Dam project consists of six (6) Tainter gates. The Tainter gates are approximately 50 ft.

wide and 41 ft. high. The project was completed in 1974.

On November 13-14, 2019, structural engineers from the U.S. Army Corps of Engineers St. Louis District utilized industrial rope access techniques to provide the necessary access to perform close-up, hands-on inspection of the critical structural components of the Tainter gates. In addition, an NDT inspection including shear wave ultrasonic inspection was performed on critical weld locations located along the struts and trunnions. The NDT inspection was sub-contracted to Wood Environment and Infrastructure Solutions Inc. and was performed by a technician certified in UT and rope access.

Inspection findings and general condition were noted for each component. The gates were secured with lock out tag out procedures outlined in the districts Hazardous Energy Control Program during the inspection.

The Tainter gates were found to be in satisfactory condition. Primary findings and conditions on the downstream side of the gates include isolated deformations along the struts and strut end frame bracing members, complete section loss in girder web stiffeners, moderate to severe surface corrosion, and debris and ponding at the joints.

The recommendations for future evaluations include to evaluate and determine the implications of the section loss and deformations noted along the strut arms and strut bracing members considering the implications of trunnion friction as part of this analysis, the incomplete CJP welds noted on the strut arms and strut bracing members, and the section loss noted at the girder web stiffener to girder flange connections as well as the strut bracing to the strut arm.

The primary recommended actions include repainting of the gates as soon as practical when funding becomes available. Consider grinding weld spatter and welds with poor profile, repairing incomplete welds, and removing remaining erection welds, etc. prior to repainting in order to ensure proper paint adherence. Repairs of significant areas of section loss and any other structural repairs should also be done prior painting. Drain holes should be enlarged in areas of insufficient drainage.

Additional maintenance recommendations include periodic cleaning and removal of vegetation and debris from gates and clean existing drain holes.

The next fracture critical HSS inspection of these gates is scheduled to be performed in 2024.

Table of Contents Chapter 1 - Introduction

1.1. Purpose

1.2. Scope of Inspection

1.3. Limitations

Chapter 2 - Project Background

2.1. Project Description

2.2. Gate Design and Construction

2.3. Gate Operation

2.4. Gate Maintenance

2.5. Inspection History

Chapter 3 - Inspection

3.1. General

3.2. Procedure

Chapter 4 - Inspection Observations

4.1. Downstream Inspection

Chapter 5- NDT Testing of Strut Welds

Chapter 6- Findings and Conclusions

Chapter 7- Recommendations

7.1. Evaluations

7.2. Actions

7.3. Maintenance

7.4. Future Inspection Considerations

List of Appendices

Appendix A: Field Notes

Appendix B: Photo Log

Appendix C: Job Hazard Analysis (JHA)

Appendix D: Select Gate Drawings

Appendix E: NDT Reports

West Point Dam – Spillway Tainter Gate Inspection Report – 2019

Chapter 1 - Introduction

1.1. Purpose

The U.S. Army Corps of Engineers (USACE), Mobile District (SAM), contacted the St.

Louis District (MVS) to assist with performing the inspections of the spillway Tainter gates at West Point Dam. The work was performed per the scope of work provided by

SAM.

1.2. Scope of Inspection

This scope of the inspection includes:

Review of design, construction, maintenance, and operations information as provided by the Mobile District.

Hands-on, rope access, visual inspection of accessible downstream portions of the spillway Tainter gates performed by structural engineers trained and certified in industrial rope access techniques.

Non-destructive testing of complete-penetration groove welds at the trunnion to strut and strut to girder connections.

A formal report including documentation of the condition of the gate, inspection results, conclusions, and recommendations.

1.3. Limitations

The conclusions and recommendations presented in this report are based on the information provided by the Mobile District, the visual inspection of the downstream portions of the Tainter Gates, and NDT results. Only exterior portions of the gates were inspected. Inaccessible areas include: the inside surfaces of the trunnion bushing and pin, embedded (in concrete) portions of the trunnion anchorages, and the upstream side of the gates. Some debris accumulation was noted at joints and pockets throughout the gates, blocking water and concealing segments of the structure. Inspectors attempted to clear the areas as much as possible in order to drain the water and clear debris to be able to inspect the joints.

No laboratory testing was conducted in the course of the inspection. Other components of the gates such as hoist machinery and other mechanical components and electrical features were not within the scope of work and therefore were not included in this inspection.

Chapter 2 - Project Background

2.1. Project Description

West Point Lake is located on the Chattahoochee River in West Point, GA. West Point Dam is a 121 foot high, 896 foot long concrete dam with earth embankments on each end. The top of the dam is located at El. 652 (NGVD 29). It has 6 spillway control Tainter gates along with a hydropower plant. Construction of the dam was completed in June 1974. The dam is operated as part of the Chattahoochee River System. The total project design discharge is 423,900 cfs.

The Tainter gates are each 50 feet wide by 41 feet tall and have a skin plate radius of curvature of approximately 40 feet. The gates are numbered 1 to 6 from right to left looking downstream.

2.2. Gate Design and Construction

The gates and project facilities were designed and built by the U.S. Army Corps of Engineers. The Mobile District provided copies of the engineering drawings and the following information was obtained from the drawings.

The skin plate has three different thicknesses along the height of the gate. The upper section is 3/8-inch thick, the middle section is 7/16-inch thick, and the bottom section is 1/2-inch. There is a 3/4-inch wire rope bearing plate at the ends of the gate that run the entire height of the gate. Wire rope attachment brackets are welded to the skin plate near the bottom corners of the gates. The skin plate is supported by vertical ST10WF 27.5 ribs. The ribs are welded to three horizontal girders. The top girder consists of a built up section with 5/8”x 12” flanges and a 3/8”x50” web plate.

The middle and bottom girders consist of a built up section with 3/4”x15” flanges and a 7/16”x60” web plate. The top girder is supported by 14WF176 struts. The middle girder is supported by 14WF264 struts. The bottom girder is supported by 14WF264 struts. Each strut is connected to the girders with a welded moment connection. The gate strut arms are braced with 14WF30 vertical and diagonal members. There are ST7WF19 girder support braces between the downstream flanges of the horizontal girders. There is also diaphragm bracing consisting of a 14WF30 diagonal member between the middle and bottom girder. The strut frame, girder bracing members, and wire rope brackets are ASTM A36 steel. The skin plate, vertical ribs, and built up girder webs and flanges are comprised of ATSM A441.

Each strut end frame is connected to a 30-inch wide trunnion bearing hub. The trunnion hub is supported by an ASTM A237, Class C steel 24.5-inch diameter pin.

The trunnion bushings are ASTM B148, Grade 9C and have an outside diameter of 18.5-inches, and an inside diameter of 17-inches. The pin is supported by the trunnion yolk/base composed of 2-inch steel yolk plates and 2 to 2 1/2-inch thick base plates attached to the concrete trunnion girder. As-built drawings can be found in Appendix D.

2.3. Gate Operation

The West Point reservoir is intended for flood control, recreation and power generation. The regulating outlet valves are generally used for normal discharge to maintain appropriate reservoir levels and to help regulate temperatures and oxygen levels in the Chattahoochee River system. The spillway Tainter gates are operated during flood surcharge.

2.4. Gate Maintenance

The project’s preventative maintenance program requires all equipment to be operated and tested yearly. Parts are lubricated twice per year.

2.5. Inspection History

Not Available

Chapter 3 - Inspection

3.1. General

The inspection of the Tainter gates was performed on November 13-14, 2019, by William Moeller, PE, Kyle Arentsen, PE, and Ariel Marrero-Irizarry, PE, of the USACE St. Louis District. All inspection personnel from the St. Louis District were structural engineers with training and USACE experience in the design, evaluation and inspection of hydraulic steel structures. NDT was performed by Kevin Nicholson of Wood PLC. The inspection utilized industrial rope access techniques to perform close up inspection of structural components of the gates. The rope access procedures followed EM 385-1-1 and the safe practices and standards set by the Society of Professional Rope Access Technicians (SPRAT). The inspection personnel from St.

Louis District were rope access certified to SPRAT Level 1 and 2. Doug Stephenson from Vertical Consult performed duties as a Level III rope access technician by supervising the rigging and safety of the rope access operation.

The weather was mostly sunny with high temperatures ranging from 49 degrees F to 51 degrees F and average wind speeds of approximately 10 mph. Reservoir elevation during inspection 631.50 feet.

3.2. Procedure

3.2.1. Structural Inspection

The inspection of the gates included close-up hands-on visual inspection of all structural components of the gate with special attention to areas considered critical or fracture critical including, but not limited to, horizontal girders, connections to the downstream flanges of the horizontal girders, strut to girder connections, strut to trunnion connections, and strut arms and bracing.

The downstream side of each gate was inspected by climbing along the horizontal girders and Tainter gate strut arms. Access to the downstream struts and girders was from the machinery platform and the trunnion bridge. Inspection rigging was anchored to tie off points at the machinery platform that were approved by the team and inspected prior to each use. During the inspection the machinery was locked out/tagged out at each position.

The upstream side of each gate was not inspected as bulkheads were not able to be placed to make the upstream sides of the gates accessible for inspection.

The gates, struts, locations of observations, photographs, and all notes in this report are identified as right or left looking downstream, unless otherwise noted.

This report uses the following definitions to categorize the condition of each component:

Excellent Condition

Very Good Condition- no problems noted.

Good Condition- some minor problems.

Satisfactory Condition- structural elements show some minor deterioration.

Fair Condition- all primary structural elements are sound but may have minor section loss, cracking, spalling or scour.

Poor Condition- advanced section loss, deterioration, spalling or scour.

Serious Condition- loss of section, deterioration, or spalling have seriously affected primary structural components. Local failures are possible. Fatigue cracks in steel or shear cracks in concrete may be present.

Critical Condition- advanced deterioration of primary structural elements. Fatigue cracks in steel or shear cracks in concrete may be present. Unless closely monitored it may be necessary remove the gate from operation until corrective action is taken.

Imminent Failure Condition- major deterioration or section loss present in critical structural components or obvious vertical or horizontal movement affecting structure stability. Gate is out of operation but corrective action may put back in limited service.

Failed Condition- out of service - beyond corrective action.

In this report, corrosion is classified as minor, moderate, or severe. Descriptions of the classifications are below:

Minor – Surface corrosion with no delamination. Corrosion cannot be scraped off by hand.

Moderate – Some flaking, beginning to delaminate, but thickness of the delamination is less than approximately 1/16-inch. There is no observable loss of section.

Severe – Delamination with measurable or observable section loss to the member.

Pitting is defined as marks, cavities, or depressions that can be caused by severe corrosion or small impacts and has visible section loss. The term “minor” is often used when areas of pitting corrosion are not significantly measureable.

Crevice corrosion is defined as iron oxides forming in a restricted place that tends to “pack” itself into tight layers as the oxide increases the thickness of the parts, typically between adjacent members with small gaps. Surface corrosion is defined as corrosion residue or staining with no visible damage to member.

Throughout the inspection, excessive sweep and camber of the main struts were recorded only if an abnormal condition was observed.

3.2.2. Member Designations

For the inspection observations and the photographs contained herein, the member designations indicated in Figures 1 through 4 apply. Unless otherwise noted, all locations of observations and notes pertaining to the gates are identified as right or left looking downstream.

Figure 1: Tainter gate end frame labeling scheme.

Figure 2: Tainter gate girder and vertical rib labeling scheme.

Figure 3: Tainter gate member nomenclature

Figure 4: Tainter gate member nomenclature

Chapter 4 - Inspection Observations

4.1. Downstream Inspection

4.1.1. Downstream Surface of Skin Plate

The downstream surface of the skin plate is in satisfactory condition (Photo 4-1) with isolated areas of moderate surface corrosion. Water accumulation between the skin plate, ribs, and girders has caused moderate to severe pitting corrosion to all the members at the joint (Photo 4-2).

Photo 4-1: Typical condition of the downstream skin plate.

Photo 4-2: Typical skin plate, rib, and girder joint.

4.1.2. Vertical Ribs

The vertical ribs are in satisfactory condition (Photo 4-3). Multiple ribs have minor deformations (Photo 4-4). Section loss due to ponding water between the end two ribs at the middle and bottom girders. (Photo 4-5). Moderate corrosion and debris build up was noted on the ribs at the pockets created by rib stiffeners and at the bottom sill (Photo 4-6). Other isolated deficiencies are noted in Table 4-1.

Photo 4-3: Typical condition of the ribs.

Photo 4-4: Typical deformation in rib.

Photo 4-5: Typical ponding between end two ribs

Photo 4-6: Typical condition of the pockets at the rib to bottom seal.

Table 4-1. Isolated Deficiencies, Vertical Ribs Gate 1: Additional Observations

1. Observation:

Rib 1 - Delamination on the flange just above the middle and bottom girder. Maximum 25% section loss in flange.

Areas of moderate to severe pitting corrosion on the web along the length of the rib.

2. Observation:

1MGR15 - 1/8" deformation over 8" of rib flange.

3. Observation:

1MGR15 - 1/16" deformation over 10" of rib flange.

Gate 2: Additional Observations

4. Observation:

2TGR14 - 1/8" deformation over 4.5" of rib flange.

5. Observation:

2BGR23 - Steel delamination on the rib flange. Maximum of 25% of section loss. Areas with moderate to severe pitting corrosion on horizontal plate stiffener and along the entire rib.

6. Observation:

2TGR16 - 1/16" deformation over 4" of rib flange.

Gate 4: Additional Observations

7. Observation:

2MGR22 - Deformation of 1/2” over 8” with a 1/4” gouge in flange above the middle girder.

Gate 5: Additional Observations

8. Observation:

Minor to moderate section loss and delamination (due to ponding water and moisture presence) on horizontal plate stiffener, rib web, rib flange and downstream face of skin plate between MGR1/R2 and MGR23/24. Maximum of 10% of section loss.

Gate 6: Additional Observations

9. Observation:

6MGR5 - 1/8” gouge over 3” in flange.

10. Observation:

Ponding water and section loss of R1, R2, R23, and R24 at the middle girder.

Maximum of 25% of section loss.

11. Observation:

6MGR15 - Deformation of 1/8" over 7" in flange.

4.1.3. Horizontal Girders

The horizontal girders are in satisfactory condition (Photo 4-7). Debris was noted to be building up on the girders at the flanges and stiffeners with moderate to severe corrosion (Photo 4-8). More significant ponding and vegetative growth was noted between the stiffeners at the ends of the bottom and middle girder with surface corrosion, moderate pitting, and section loss (Photo 4-9). Other random isolated areas of surface corrosion were noted throughout the girders, mainly near joints (Photo 4-10). Other isolated deficiencies are noted in Table 4-2.

Photo 4-7: Typical view of downstream girder.

Photo 4-8: Typical debris build up and surface corrosion along the girders.

Photo 4-9: Typical vegetation build up and ponding with moderate corrosion and section loss at the ends of the middle and bottom girders.

Photo 4-10: Typical isolated surface corrosion along the girders.

Table 4-2. Isolated Deficiencies, Horizontal Girders

1. Observation:

1MG1 - Top of girder area with ponding water and vegetation. Unable to unclog the drain holes during

Severe corrosion with section loss ranging from (10%-25%) in a 2”x3” area. Complete section loss for approximate 1” diameter on the middle girder web stiffener between MG2 and MG3.

1MG5 - Moderate pitting corrosion with maximum of 10% of section loss on girder end plate and upstream face of downstream flange

Moderate to severe section loss on downstream side of the upstream bottom girder flange. Maximum of 10% of section loss.

Minor to moderate section loss on bottom girder web (top side) between 1BGR13 and 1BGR14. Maximum of 10% of section loss.

Minor to moderate section loss corrosion on girder web at 2TG1. Maximum of 10% of

Random isolated gouges ranging from (approx. 1/16"

– 1/4”) in the downstream and upstream flanges of the top girder.

Moderate section loss of top girder web between TG2 and TG3. Maximum of 10% of

Weld remnants and 1/8” gouges on downstream side of downstream flange of the middle girder between MG3 and MG4

MG4-MG5 - Top of girder area with ponding water. Unable to unclog the drain holes during

1/16" Max. gouges on the downstream face of downstream flange between 2MG2 and 2MG3

12. Observation:

Ponding water and debris build up causing moderate to severe section loss ranging from (10%-25%) on strut end frame bracing member and bottom girder.

Gate 3: Additional Observations

13. Observation:

Moderate section loss on girder web at 3TG1.

Maximum of 10% of section

14. Observation:

Side seal leaking water onto top girder moderate section loss corrosion on girder web at TG5. Maximum of 10% of

15. Observation:

3MG5 - Top of girder area with ponding water and vegetation. Unable to unclog

16. Observation:

3BG4 and 3BG5 - Top of girder area with ponding water and vegetation. Unable to unclog the drain holes during inspection.

17. Observation:

Severe section loss ranging from (25%-50%) with a 2” diameter 100% section loss at the connection of transverse stiffener and downstream girder flange between TG4 and TG5.

18. Observation:

1/8" Max. gouges on the downstream face of upstream flange between 4TG16 and

4TG17.

19. Observation:

4MG1 - Moderate section loss corrosion on girder right side end plate. Maximum of 10% of section loss.

20. Observation:

1/16" Max. gouges on the downstream face of downstream flange between 4MG2 and 4MG3.

21. Observation:

4MG5 - Top of girder area with ponding water and vegetation. Unable to unclog the drain holes during inspection. Moderate to severe section loss ranging from (10%-25%) on downstream flange due to ponding water and moisture presence. Moderate to severe section loss ranging from (10%-25%) on left end plate due to moisture presence.

22. Observation:

4BG5 - Top of girder area with ponding water and vegetation. Unable to unclog

23. Observation:

Moderate to severe section loss ranging from (10%-25%) in girder web and along downstream flange and web connection between left end plate and first stiffener of the top girder.

24. Observation:

5TG1 - 1/8" max. gouges over 4" on the downstream flange.

25. Observation:

Complete section loss of the first stiffener after the left end plate at the connection to the top girder downstream flange.

Moderate to severe section loss ranging from (10%-25%) along the flange and web connection.

26. Observation:

5TG3 - 1/16" max. gouge over 1" on the upstream flange.

27. Observation:

Moderate pitting corrosion on girder web at 5TG5.

28. Observation:

Moderate section loss on bottom side girder web (top side) between 5TG3 and 5TG4

29. Observation:

5MG1-MG2 - Top of girder area with ponding water and vegetation. Unable to unclog

30. Observation:

5MG4 - 1/32" max. gouge over 1" on the strut stiffener plates.

31. Observation:

5BG1-BG2 - Top of girder area with ponding water and vegetation. Unable to unclog

32. Observation:

Moderate section loss on the bottom girder web between BG2 and BG3. Maximum of

33. Observation:

downstream face of the downstream flange between 5BG2 and 5BG3. Maximum of

34. Observation:

bottom girder web (top side) between 5BG3 and 5BG4.

35. Observation:

Moderate section loss on top of girder web and in downstream girder flange, web, and stiffener at TG1.

36. Observation:

Section loss in top girder panel 5 web between G2 and G3. Maximum of 10% of

37. Observation:

6" diameter paint failure with minor section loss and other localized paint fail on top girder at G3

38. Observation:

Section loss in downstream flange of the middle girder at MG1. Maximum of 10% of

39. Observation:

1”x2”x1/8”deep gouge in downstream flange of the middle girder at MG2 on Gate 6.

40. Observation:

Butt weld in middle girder web though panel 9 not flush or grinded.

41. Observation:

1/16” section loss of stiffener plate, downstream flange, and web at MG3 on Gate 6.

42. Observation:

3" weld remnants near MG3 on downstream girder flange

4.1.4. Girder Flange Bracing and Diaphragm Bracing

The girder flange bracing were noted to be in fair condition with typical minor to moderate corrosion and paint failure at girder ends (Photo 4-11 and Photo 4-12).Typical minor to moderate corrosion was also noted on the gusset plates, especially on the middle and bottom girders. (Photo 4-13).

Photo 4-11: Typical condition of the girder bracing connection.

Photo 4-12: Typical condition of the girder bracing connection.

Photo 4-13: Typical gusset plate corrosion.

4.1.5. Strut End Frames and Bracing

The right and left strut end frames and the associated vertical and diagonal bracing are in poor condition (Photo 4-14). The paint is in poor condition, with isolated areas of paint failure and severe corrosion (Photo 4-15). Typical ponding water causing moderate to severe corrosion and delamination at the strut bracing and strut arm joints (Photo 4-16). Typical poor weld profile, undercut, and incomplete welds were found on numerous strut frame bracing member welds (Photo 4-17).

Areas of corrosion were noted throughout the strut frames (Photo 4-18). Other isolated deficiencies are noted in Table 4-3. Areas of minor corrosion were considered typical and not included in Table 4-3.

Photo 4-14: Overall view of the right strut end frame.

Photo 4-15: Typical area of paint failure and minor surface corrosion.

Photo 4-16: Typical ponding water with moderate to severe corrosion

Photo 4-17: Typical poor weld profile, undercut and incomplete bracing member welds.

Photo 4-18: Typical corrosion with moderate to severe section loss on strut end frames.

Table 4-3. Isolated Deficiencies, Strut End Frames and Bracing

1. Observation:

1LT5 – Paint breach with localized minor corrosion noted in girder web and girder stiffeners just upstream of joint.

Moderate localized corrosion with moderate section loss (approx. 1/16”) at intersection of left and right girder stiffener and downstream girder flange.

Member 1LM4-1LB5 - 1” deformation over 10” noted in bracing member left flange.

1LB5 - Paint breach with localized minor-moderate corrosion with approx. 1/16” section loss noted at strut flange and strut end plate on both upstream and downstream side of joint.

1LB4 – Localized severe corrosion with 100% section loss at upstream side of joint in bracing member web at left strut flange. Condition also noted on bracing member web at right strut flange with approx. 60- 70% section loss. Similar condition on downstream side of joint.

1LM3 – Ponding water on upstream side of joint causing moderate to severe corrosion and delamination with section loss (approx. 1/8” to 3/16”) in strut flanges. Delamination and section loss runs approx. 4-ft upstream of joint. Moderate corrosion with section loss (approx. 1/16” to 1/8”) on downstream side of joint noted in strut flanges, web and bracing member web.

1LB3 – Moderate corrosion with section loss (approx. 1/8”) in left flange of strut and bracing member web on upstream side of joint. Ponding water with corrosion and delamination noted in downstream side of joint with estimated 1/8” to 3/16” section loss in bracing member and strut flanges.

Deformation noted (approx. ½” in 8”) in bracing member 1LM3- LB3 right flange just above joint.

1LM2 – Ponding water on upstream side of joint causing moderate to severe corrosion and delamination with section loss (approx. 1/16” to 1/8”) in strut flanges. Moderate corrosion with section loss (approx. 1/16”) on downstream side of joint noted in strut flanges, web and bracing member web.

1LM1 –Moderate corrosion with section loss (approx. 1/16”) noted in both strut flanges just upstream of trunnion assembly.

Localized moderate corrosion with section loss (approx. 1/16”) on underside of middle strut web.

1LT1L – Random large weld remnant in outboard side of left strut flange

Member 1RT3-1RM3 - Deformation of 1/8" over 6" on downstream left flange of bracing member

Member 1RT5-1RM4 - Deformation of 1/16" over 6" on upstream left flange of bracing

12. Observation:

Member 1RM4- 1RB4Deformation of 3/16" over 7" on upstream side right flange.

13. Observation:

1 RB2 - 1/16" section loss at left flange, web, and bracing

14. Observation:

1RB3 - Ponding water and severe corrosion with section loss in the downstream right flange of bracing member M3-B3 at joint B3. Complete section loss for an area of 1/4" by 1”.

1/16” to 1/8” section loss in web and flanges of strut due to ponded water.

15. Observation:

1RT1 – Approximate 1/8" gouge in left flange of the top strut.

16. Observation:

2LM2 - Moderate corrosion with localized section loss (approx.

1/16”) in strut flanges and bracing member web on downstream side of joint.

Evidence of existing areas of moderate pitting noted in these area.

17. Observation:

2LM2 – Ponding water on upstream side of joint causing moderate to severe corrosion and delamination with section loss (approx. 1/16” to 1/8”) in strut flanges and web.

Delamination and section loss runs approx. 2-ft upstream of

18. Observation:

2LM3-T4 – Poor weld profile and incomplete bracing member web complete joint penetration (CJP) weld on upstream side of

19. Observation:

2LM4 – Poor weld profile and incomplete bracing member web CJP weld and bracing member flanges to strut flange on upstream side of joint. Localized areas of moderate corrosion with section loss (approx. 1/16” to 1/8”) in strut flanges.

20. Observation:

2LM5 – Moderate to severe corrosion with section loss (approx. 1/16” to 1/8”) noted in upstream side of joint on underside in downstream girder flange, web stiffeners, strut end plate and girder bracing

21. Observation:

2LB4 – Localized minor to moderate corrosion with section loss (approx. 1/16”) in left strut flanges and bracing member web on upstream side of joint.

22. Observation:

2LB5 – Localized minor to moderate corrosion with section loss (approx. 1/16”) in right strut flanges and strut end plate on downstream side of joint.

Similar condition on upstream side of joint.

23. Observation:

2LB5 – Underside of joint is noted to have minor to moderate surface corrosion throughout in strut flanges and strut end plate on downstream side of joint. A linear weldment and/or gouge was noted in full width of the strut web on underside of strut just below joint B4. This was assumed to be due to some sort of field repair.

24. Observation:

2LT1R – Weldments likely from erection remain in-place on right side of trunnion assembly at

25. Observation:

2LM1 – Ponding water in place during time of inspection.

26. Observation:

2RT5 – Approximate 1/8” section loss in fillet weld between top strut end plate and downstream flange of top girder.

27. Observation:

2RT4 – Approximate 1/16” to 1/8” gouge in right top edge of left flange of top strut. Edge appears to have been flame cut.

28. Observation:

Member 2RT2-2RM2 - Bracing member T2-M2 has gouge in left flange approximately 18" from

RM2.

29. Observation:

2RM2 – Approximate 1/16” to 1/8” section loss in both strut flanges on upstream and downstream side of joint.

30. Observation:

R2M4 – 5/32” undercut in right flange of member RT5-RM4, adjacent to the splice where the bracing member was cut short and short section of plate was installed. CJP weld on left flange is incomplete on upstream side of weld.

31. Observation:

2RB3 - 1/8" section loss in bottom strut right flange upstream of B3.

32. Observation:

2RT1 - 1/8" deformation over 7” in left flange of top strut near

RT1.

33. Observation:

2RT1 - 1/16" undercut in left flange of top strut adjacent to complete joint penetration weld between left trunnion side plate and left flange of top strut.

3/32” gouges in left trunnion side plate

Gate 3: Additional Observations

34. Observation:

3LM2 – Incomplete complete joint penetration weld (CJP) at strut bracing member web on

35. Observation:

3LM2 – Existing 100% section loss in bracing member M2-T3 web in two locations. Apparent existing pitting noted to have been painted over in the past.

36. Observation:

3LM2 – Incomplete bracing member web complete penetration weld on downstream side of joint at member M2-T3. Minor to moderate corrosion noted in right strut flange.

37. Observation:

3LM2 – Deformation noted (approx. 1/4” in 6”) in right flange of bracing member M2- B2.

38. Observation:

3LM3-T3 – Incomplete bracing member web CJP weld on

39. Observation:

3LM3 –Deep gouges noted in existing blank bolt holes in bracing members M3-T3 and M3-T4 that were likely used during erection. Poor weld profile and incomplete bracing member M3-T4 web CJP weld and bracing member flanges to strut flange on downstream side

40. Observation:

3LM4 - Localized minor to moderate corrosion with section loss (approx. 1/16”) in strut flanges and bracing web on downstream side of joint.

Moderate corrosion with section loss (approx. 1/16”-1/8”) in strut flanges, web and bracing web in pocket formed between two bracing member. Similar condition on upstream side of

41. Observation:

3LB1R – Undercut and 1/16” – 1/8” gouge noted in bottom strut right flange weld to trunnion assembly.

42. Observation:

3LM4 – 1/2" deformation over 8” in right flange of bracing member M4-B4.

43. Observation:

3RT5 – Approximate 3/8” deformation of top right corner of top strut end plate at downstream flange of downstream flange of top girder flange. Top right corner appears to have been in the field during fabrication.

44. Observation:

3RM4 – Incomplete CJP weld between left flange of bracing member 3T4-3M4 and left flange of middle strut, along with two incomplete sections (1/2” and 3/4") of the strut bracing web CJP weld.

45. Observation:

3RM4 – Fill plate installed between web of bracing member 3T5-3M4 and bracing member web extension plate welded to the middle strut.

46. Observation:

3RM4 – 1/4" deformation over 7” of right flange of bracing

47. Observation:

Deformation of bottom strut left flange between 3RB1 and 3RB2.

The deformation measured on top was 1/8” over 4’, while the deformation measured on bottom was 3/16”.

48. Observation:

3RT4 – Right flange of top strut has two minor deformations around 3RT4. Deformations were less than 1/16”.

49. Observation:

3RT1 – 3/32” maximum gouges in trunnion side plate.

50. Observation:

4LM2 - Localized minor to moderate corrosion with section loss (approx. 1/16”) in strut flanges and bracing web on DS side of joint. Ponding water with moderate to severe corrosion with section loss (approx. 1/16”- 1/8”) in strut flanges, web and bracing web in pocket formed between two bracing member.

Similar condition on US side of joint with severe corrosion and section loss (approx. approx.

1/16”-1/8”) in strut flanges.

51. Observation:

4LB2 - Localized moderate to severe corrosion with section loss (approx. 1/16” to 1/8”) in strut flanges and bracing web on downstream side of joint.

Similar condition noted on US

52. Observation:

4LM3-T3 – Poor weld profile and incomplete CJP weld of strut bracing member web on DS side of joint. Similar weld condition noted throughout welds at joint.

53. Observation:

4LM4-T3 – Poor weld profile and incomplete CJP weld of strut bracing member web on US side

54. Observation:

4LM4 – 1/2" deformation over 10” noted in left flange of bracing member B4-M4.

55. Observation:

4LT1R – Weldments and gouges likely from erection remain in-place on right side of trunnion assembly at joint.

56. Observation:

4RM2 - 3/16" section loss in right flange, 1/8" section loss on web and left flange on upstream and downstream side of joint.

57. Observation:

4RT2-4RM2 – 1/8”

deformation in right flange of bracing member w/ evidence of impact.

58. Observation:

4RM3 - 1/8" section loss in strut flanges and on bracing member webs.

59. Observation:

Bracing member RM4-RB4 has 5 deformations:

1. Downstream side of left flange, 1/2" over 8" (immediately below M4).

2. Upstream side of left flange, 1/2" over 9” (6’ above B4).

3. Upstream side of left flange, 3/4" over 9" (2’ above B4).

4. Downstream side of left flange, 1/2" over 8" (9” above B4).

5. Upstream right flange, 1/8" over 7" (3’ above B4).

60. Observation:

4RB4 - 1/8" section loss in right flange and 3/16” section loss in strut web on upstream side of joint. Standing water with 3/16" section loss in right flange on downstream side of joint, 1/8" section loss on strut web and left flange on downstream side.

61. Observation:

4RM4 - Rolling defect in middle strut right flange, downstream of M4.

62. Observation:

5LT5 – Localized deformation noted in left top edge of strut end plate (approx. 1/2" in 3”).

Evidence of marking on downstream face of end plate were noted

63. Observation:

5LM3 – Poor weld profile and undercut noted in strut to M3- T4 bracing member web CJP weld on downstream side of joint. Poor weld profile and incomplete fill in strut to M3-T4 bracing member web CJP weld on upstream side of joint.

64. Observation:

5LM4 – Poor weld profile and incomplete M4-T4 bracing member web CJP weld on downstream side of joint

65. Observation:

5LM5 – Undercut noted (approx.

1” in length and 1/16” deep) in strut right flange to strut end plate.

66. Observation:

5LB4 – Localized minor to moderate corrosion with section loss (approx. 1/16”) in strut flanges and bracing member web on downstream side of joint. Similar condition on upstream side of joint.

67. Observation:

5LT1R – Weldments and gouges likely from erection remain in-place on right side of trunnion assembly at joint.

68. Observation:

5RT5 – The heads of the bolts are not completely seated against the strut end plate.

69. Observation:

5RM2 - Approximate 1/8” section loss at joint in all components, strut web and flange and bracing web.

70. Observation:

5RM3 – Approximate 1/8” section loss at joint in all components, strut web and flange and bracing web and flange.

71. Observation:

5RB4 – 1/8” deformation over 9” in left flange of 5M4-5B4.

1/16” deformation over 7” in right flange of 5M4-5B4.

72. Observation:

5RM4 – Incomplete CJP weld between right middle strut flange and right flange of bracing member T4-M4 on downstream

73. Observation:

RB4 – 3/16” deformation over 6’ on bottom of bottom strut right flange. The top of right strut flange does not appear to be deformed.

74. Observation:

5RB3 - 5/32" undercut in left strut flange adjacent to M3-B3 bracing member CJP weld.

75. Observation:

Middle Strut- right flange of middle strut has rolling defect at various points along its length.

76. Observation:

5RT2 – Deformation of ¼” over 9” in left flange of bracing member 5T2-5M2

77. Observation:

Member 5RM3-5RB3:

Deformation of ¼” over 10” in upstream left flange of bracing

78. Observation:

Bracing member 5RT5-5RM4 – 1/8” deformation over 8” in left flange of bracing member, 3’ above M4.

79. Observation:

6LM2 - Localized minor to moderate corrosion with section loss (approx. 1/16”) in strut flanges, web and bracing web on downstream side of joint.

Ponding water with moderate corrosion with section loss (approx. 1/16” to 1/8”) in bracing member webs in pocket formed between two bracing member. Similar condition on upstream side of joint with ponding water and moderate corrosion with section loss (approx. 1/16” to 1/8”) in strut flanges and web.

80. Observation:

6LB2 - Localized minor to moderate corrosion with section loss (approx. 1/16” to 1/8”) in strut flanges and bracing web on upstream side of joint. Ponding water with moderate corrosion with section loss (approx. 1/16” to 1/8”) in strut flanges and bracing web on downstream

81. Observation:

6LB3 - Localized minor to moderate corrosion with section loss (approx. 1/16” to 1/8”) in strut flanges and bracing web on upstream side of joint. Moderate corrosion with section loss (approx. 1/8” to 3/16”) in strut flanges and bracing web on

82. Observation:

6LM4 - Localized minor to moderate corrosion with section loss (approx. 1/16”) in strut flanges and web on downstream side of joint. Ponding water with minor corrosion in bracing member webs in pocket formed between two bracing member.

Similar condition on upstream side of joint with ponding water and minor corrosion with section loss (approx. 1/16”) in strut flanges and bracing web.

83. Observation:

6LM4 – 1/2" deformation over 8” noted in left flange of bracing

84. Observation:

6LB4 - Localized minor corrosion with section loss (approx. 1/16”) in strut flanges and bracing web on upstream side of joint. Moderate to severe corrosion with delamination and section loss (approx. 1/8”) in strut flanges and bracing web on

85. Observation:

6LT1 – Gouges (approx. 1” long and 1/8” deep) noted in top side of top strut at weld to trunnion assembly. Weldments and gouges likely from erection remain in-place on right and left sides of trunnion assembly and strut flanges at joint.

86. Observation:

6LM1 – Debris with localized minor corrosion with section loss (approx. 1/16”) in strut flanges and web on upstream

87. Observation:

6LB1 – Debris with localized minor corrosion with section loss (approx. 1/16”) in strut flanges and web on upstream

88. Observation:

6RT4 – 3/16” deformation over 42” in the left flange of the top strut, 2’ downstream of T4.

89. Observation:

Member 6RT4-6RM4 – 1/16” deformation over 7” in left flange of bracing member, 2’ above M4.

90. Observation:

6RM2 - Ponded water on upstream side of M2 with maximum section loss of 13/32" in strut flanges and 1/16" in web. 13/32” maximum section loss is isolated near wide flange fillet on left flange. General section loss in both flanges at joint is 1/8”.

91. Observation:

6RM2 - Ponded water on upstream side of M2 with section loss of 13/32" in strut flange and 1/16" in web.

92. Observation:

Member 6RM4-6RB4 – 1/4" deformation over 7” in right flange of bracing member below M4.

93. Observation:

6RB4 - Approximate 1/8" section loss in strut flanges and 1/16” section loss in strut web, and bracing member web and flanges. Section loss is located on downstream side of joint.

3/16” section loss on left and right flanges, and 1/4" section loss on strut web and bracing member web extension plate on

94. Observation:

6RB5 - 3/16" section loss in strut end plate, 1/8" section loss in strut web and left flange.

Incomplete CJP weld between left flange of bottom strut and strut end plate, on top right side for approximately 1/4".

95. Observation:

6RB3 - 3/16" section loss in strut web and right flange on

96. Observation:

6RM1 – Maximum 1/8” section loss in flanges of middle strut for approximately 30” upstream of

4.1.6. Trunnion Bearing Assembly

The trunnions appear to be in satisfactory condition (Photo 4-19 and Photo 4-20).

Debris was building up in the pockets of the trunnion hub connection contributing to the initiation of minor isolated corrosion in those areas (Photo 4-21). Grease was noted to be emanating between trunnion yoke and trunnion hub and around pin on trunnion yoke plate (Photo 4-22).

Photo 4-19: Typical trunnion condition.

Photo 4-20: Typical view, underside of the trunnion.

Photo 4-21: Typical ponding at the top of the trunnion hub with very isolated surface corrosion.

Photo 4-22: Typical grease emanating between the yoke and the pin.

4.1.7. Trunnion Girder

The trunnion girders appear to be in fair condition (Photo 4-23). The concrete was sounded with a hammer and no evidence of delamination or spalling noted.

Photo 4-23: Typical condition of the trunnion girder.

4.1.8. Bottom Seal

The bottom seal appears to be in satisfactory condition along the width of the gate with minor to moderate surface corrosion noted on the downstream surface of the skin plate and sill (Photo 4-24). Water was on the upstream side of all the gates;

therefore, the seals themselves were not inspected, however their functionality was observed. Gates 1 and 3 had water leaking from the bottom corners and midspan, this leaking was due to the joint in the embedded plate. The remaining gates had little to no water leaking (Photo 4-25).

Photo 4-24: Typical downstream view of the bottom seal.

Photo 4-25: Typical leaking at Gate 1 and 3.

Chapter 5- NDT Testing of Strut Welds NDT in the form of shear wave ultrasonic testing was performed on the strut to trunnion and strut to strut end plate CJP welds. During the inspection phased array was utilized at locations with complete penetration welds from the strut arms to the girders. A total of 36 locations welds were tested per gate. No relevant indications were noted at any testing locations. See Appendix E for complete detailed NDT report.

Chapter 6- Findings and Conclusions Overall, the Tainter gates at West Point Dam were found to be in satisfactory condition.

Deficiencies such as deformations, moderate corrosion and gouges were noted in the downstream structure. The skin plate is starting to show deterioration with surface corrosion and minor section loss. Based on the assessment of the structural condition and noted deficiencies of the gates, and considering no other factors (i.e. operation, maintenance, adequacy of original design, foundation, etc.), the probability of failure of the gate during normal loading events is considered to be low.

Table 7- Gate Component Condition Summary

Gate #: 1 2 3 4 5 6 Overall Rating S S S S S S

Down Stream Skin Plate S S S S S S

Vertical Ribs S S S S S S

Horizontal Girders F S S F F S

Girder Bracing & Diaphragm Bracing F F S F S S

Strut End Frames F F F P P P

Trunnions S S S S S S

Trunnion Girder G G G G G G

Bottom Seal S G S G G G

Side Seals and Embedded Plates S G S G S G

E-Excellent, VG-Very Good, G-Good, S-Satisfactory, F-Fair, P-Poor, SC-Serious, C-Critical, I- Immanent Failure, FC-Failed

Observations resulting from the inspection include:

1. On the downstream side of the gate, the paint system is showing signs of age with localized areas of general paint failure and moderate to severe corrosion. The moderate to severe section loss generally occurs where there is inadequate drainage. The moderate to severe section loss occurs in girder web stiffeners, and the webs and flanges of struts and strut bracing members at strut end frame joints.

2. Overall the welds appear to be structurally sound. All critical end frame welds tested with shearwave ultrasonic testing yielded no rejectable indications.

Numerous incomplete CJP welds were noted on strut end frame bracing member welds. An incomplete CJP weld was also noted between the left end frame bottom strut left flange and strut end plate on Gate 6.

3. Multiple deformations exist in flanges of the strut bracing and strut arm flanges.

These likely have been a result of fabrication or handling. It cannot be ruled out that the observed deformations may have been a result of overload associated with trunnion friction.

4. Inadequate drainage exists on the girders and strut end frame joints at M5 and B5 due to undersized or hindered drain holes. Inadequate drainage also exists on the strut end frame joints M1 through M4 and B1 through B4 due to a lack of drain holes. Debris buildup, vegetation growth and ponding of water were observed as a result of the insufficient drainage.

5. Other minor deficiencies were noted throughout the structure from fabrication including gouges and poor welds.

Chapter 7- Recommendations Based on the inspection findings, recommendations are as follows.

7.1. Evaluations.

Evaluations/analysis should be performed on the following as soon as possible in order to determine significance to the structural integrity and functionality of the gates:

1. Evaluate and determine the implications of the section loss and deformations noted along the strut arms and strut bracing members.

Consider the implications of trunnion friction as part of this analysis.

2. Evaluate and determine the implications of the incomplete CJP welds noted on the strut arms and strut bracing members.

3. Evaluate and determine the implications of the section loss noted at the girder web stiffener to girder flange connections as well as the strut bracing to the strut arm.

7.2. Actions.

The following repair and miscellaneous action items should be completed within the next 5 years and prior to the next HSS inspection in order to minimize further deterioration of the gate:

1. Consider cleaning, blasting and repainting of the gate as soon as practical when funding becomes available is recommended. The existing paint system is thinning and has failed at various locations. Consider grinding weld spatter and welds with poor profile, repairing incomplete welds, and removing remaining erection welds, etc. prior to repainting in order to ensure proper paint adherence. Repairs of significant areas of section loss and any other structural repairs should also be done prior painting.

2. Drain holes should be enlarged in areas of insufficient drainage, especially at those adjacent to the stiffeners. Install new drain holes downstream of joints in strut end frame on middle and bottom strut. An evaluation should be made by Engineering before enlargement of existing holes or addition of new drain holes to ensure strength of the members is not compromised by the drain holes. Modification of bracing members may be necessary to improve drainage.

7.3. Maintenance.

Regular maintenance Recommendations include:

1. Gates should be cleaned of debris and vegetation on a periodic basis, but at a minimum before future structural inspections.

7.4. Future Inspection Considerations

1. It is recommend that the next fracture critical HSS inspection of these gates 5 years from the date of this inspection.

2. Clean all the debris on the gates, just before visual inspection in order to increase the effectiveness of visual inspection.

3. Inspect upstream of all gates during future inspections.