Memorandum_Lock and Dam 2 Upstream Guide Wall Tow Impact_Redacted.pdf

DEPARTMENT OF THE ARMY

U.S. ARMY CORPS OF ENGINEERS, ST. PAUL DISTRICT

332 MINNESOTA STREET, SUITE E1500

ST. PAUL, MN 55101

CEMVP-ECD November 02, 2023

MEMORANDUM FOR JARROD BROWN, Civil Engineer, Locks and Dams

SUBJECT: Lock and Dam 2 Upstream Guide Wall Tow Impact – Dive Inspection Report

1. The undersigned planned and witness a dive inspection of damage to the upstream end of the upper guide wall at Mississippi River Lock and Dam 2 at approximately 1030 on October 26, 2023. The upstream end of the wall had been struck by a barge tow at approximately 0500 on October 22, 2023. A memorandum documenting the damage to the guide wall is attached as Attachement A. The dive inspection was conducted to ascertain additional information related to the impact below the waterline and to verify field dimensions taken at the initial inspection on October 23rd. The undersigned, along with , met the dive team on site. The dive team consisted of , . The dive team was briefed about the impact and shown images and figures of what information needed to be ascertained.

2. The clarity and flow conditions of the Mississippi River were limitations to the dive team and underwater footage or pictures not were available. However, , the diver for this inspection, had enough visibility to take measurements and use sense of touch along with his experience to survey all the damage. Another limitiation was the elevation of the river bottom on the landside of the wall. For most of the length of UG25, the river bottom on the landside was higher than the shear plane. See Figure 1.

CEMVP-ECD

Figure 1: Elevation view of landside of the UG25 showing river bottom covering most of the shear plane.

3. The inspection verified or presented a number of items below:

a. The shear plane occurred at Elevation 680’-0” across the entirety of UG25. This is the exact elevation of the interface of the new and old concrete from the repair completed in 2011.

b. Lateral movement at the end of UG25 was measured to be approximately 34”.

See Figure 2 and Figure 3.

c. Field measurements taken the day after the impact showed that a 17” displacement of the bottom portion of UG25 occurred. This field measurement relied solely on line of site relative to the plane of the remaining guidewall and a location on a moving boat. The dive inspection, in conjunction with the undersigned’s structural analysis of the impact, confirmed the bottom portion did not displace due to the impact. reported that no gap existed between the bottom portion of UG25 and the riverside river bottom. Probing the river bottom adjacent to UG25 revealed fully compacted river bottom, further suggesting that no movement occurred to the bottom portion of UG25.

d. At the shear plane, there exists a 2”-4” gap that extends into UG25 more than 4’.

This confirms the fields measurement made showing UG25 is rotated 1.25 degrees landward about it’s vertical axis. See Figure 2

e. A large crack propegating from the second ledge of UG25 at the monolith joint and extending upstream and down at a 45 degree angle toward the shear plane was identified. reported and showed large portions of concrete have broken off. It is not certain how deep this crack goes because the river bottom was very high at this point. See Firgure 1.

f. Damage to UG24 was reported in the initial inspection report. The dive inspection verified that no additional damage occurred to UG24 below the water line and up to the top of the river bottom. Verifcation of damage to UG24 below the river bottom elevation did not occur.

Figure 2: Section view at the end of UG25.

Figure 3: Plan view of UG25.

4. Structural analysis was computed by the undersigned in conjunction with this report.

The analysis will be attached as Appendix B. The purpose of the analysis was to determine if any displacement may have occurred to the bottom portion of UG25 and to determine the minimum velocity of the barge. Determining whether displacement of the bottom portion of UG25 occurred was necessary in order to rule out if any additional inspections are needed. The results of the dive inspection, in conjunction will the analysis, have determined that no further investigation of the bottom portion of UG25 is needed. Many key assumptions were made in order to validate this conclusion. These include: angle of barge impact relative to the chamfer corner of UG25 (based on witness testimony and survalence video), unit weight of the river bottom in-situ material, and passive resistance soil coefficient.

5. Conclusions based on the dive inspection are as follows:

a. The current Notice to Navigation should continue until repairs are made.

b. No further investigation of the bottom portion of UG25 is needed.

c. A team should be assembled to recommend and design a repair for UG25 and the small portion of UG24 that was damaged.

5. The point of contact is , Encl(s)

STRUCTURAL ENGINEER

ST. PAUL DISTRICT

DEPARTMENT OF THE ARMY

U.S. ARMY CORPS OF ENGINEERS, ST. PAUL DISTRICT

332 MINNESOTA STREET, SUITE E1500

ST. PAUL, MN 55101

CEMVP-ECD October 24, 2023

MEMORANDUM FOR , Civil Engineer, Locks and Dams

SUBJECT: Lock and Dam 2 Upstream Guide Wall Tow Impact – Initial Inspection Report

1. The undersigned inspected damage of upstream end of the upper guide wall at Mississippi River Lock and Dam 2 at approximately 1030 on October 23, 2023. The upstream end of the wall had been struck by a barge tow at approximately 0500 on October 22, 2023. Lock staff reported the tow had impacted the upstream end of the upper guide wall. Base on field measurements, the impact caused monolith UG25 to rotate towards the landside approximately 5 degrees, resulting in an approximate 44” lateral movement of the end of the monolith and a 17” permanent displacement of the foundation. Lock staff reported that the tow consisted of 12 fully loaded barges and impacted the wall at an approximate angle of 45 degrees. Figure 1 shows the rotation of monolith UG25 towards the landside. Figure 2 shows the approximate lateral movement measured from the plane of the guide wall to the end of the UG25. A similar incident occurred in 2011 and resulted in new concrete being poured for UG24 and UG25 from elevation 680’ to the current elevation.

Figure 1: Impacted monolith UG25 showing rotation and subsequent lateral movement.

Report

Figure 2: Shows approximate lateral movement away from the alignment of the guide wall. 3’8” was measured from the end of UG25.

2. Rotation of the UG25 towards the landside caused a crushing failure, resulting in localized delamination of the concrete on UG24. Two distinct delamented areas were created. See Figure 3. Delamentated portions of the monolith were removed with a hammer to reveal the exposed reinforcement. See Figure 4. The delaminated area is approximately 6 in deep. See Figure 5.

Figure 3: Landside of the monolith at UG25/UG24 showing the delaminated areas on

UG24.

Figure 4: Delaminated area of UG24 showing exposed reinforcement.

Figure 5: Shows a delamination depth of approximately 6 in.

3. The riveside of the UG25 was measured to be 2 ½ inches higher than the riverside of UG24, likely caused by wall tipping and rising up as it slides over uneven fracture surface. . See Figure 6. The landside of the UG25 was measured to be 7/8 inches higher than UG24. The gap between monoliths was 8 ½ inches at the top, riverside.

See Figure 7. The gap at the top landside was 3 ½ inches.

Figure 6: Vertical displacement, riverside.

Figure 7: Horizontal displacement parallel to the chamber, riverside.

4. The impact zone appeared to be fairly small. See Figure 8. A large 6” x 41” section of concrete was damaged as well as other small areas of concrete and corner protection. See Figures 9, 10, and 11. Lock staff reported damage to the barge where it impacted the wall was minimal and no barge photos were available. Lock staff was working to capture video from site cameras.

Figure 8: Plan view of UG25 show impact zone and approximate angle of impact

Figure 9: Impact zone.

Figure 10: 6”x42” zone of missing concrete due to impact.

Figure 11: Damage to corner protection

5. The monolith appeared to be leaning towards the landside. A plumb bob was used to determine the severity of the lean. Based on measurements in the field the monolith is leaning 1.25 degrees towards the landside.

6. Conclusions based on the initial site inspection

a. Notice to Navigation should be issued stating UG24 and UG25 should not be used by any river traffic until repairs are made.

b. A dive inspection should occur to ascertain the condition of the shear plane below the waterline and if possible, the condition of piling. Further, inspection of UG24, the adjacent monolith, should be done to assess if any damage occurred below the waterline.

c. Given magnitude displacement, the condition of foundation should be evaluated.

Based on field measurements, the foundation has 16-18” of permanent displacement. A dive inspection will be performed to help evaluate the foundation condition.

d. Given that two similar incidents have occurred withing 12 years of each other, the design and construction of an end cell should be given high priority.

5. The point of contact is

Encl(s) , PE

STRUCTURAL ENGINEER

ST. PAUL DISTRICT

Designer: , PE Date: 11/02/2023 MVP Operations

Checker: , EIT Date: 11/02/2023 US Army Corps of Engineers Lock and Dam 2 Upper Guardwall Barge Impact St. Paul District

Figure 1-2: Portion of Monolith UG25 sheared off that is above the water line

2. Resistance Above At and Above Shear Plane

Determine Resistance due to Weight of Concrete Section that Sheared Off.

≔VUG25Upper 5230.31 ft3 Volume of concrete of the sheared off portion of UG25 (From Revit)

≔VUG25_WaterUpper 2240.03 ft3 Volume of concrete of the sheared off portion of UG25 that is above the water line. Figure 1-2 (Water Elevation Assumed to be 687.24)

≔VUG25_buoyantUpper =-VUG25Upper VUG25_WaterUpper 2990.3 ft3 Volume of concrete of the sheared off portion of UG25 that is below the water line and subject to buoyancy

≔γw 62.43 ― lbf ft3 Unit Weight of Water

≔γc 145 ― lbf ft3 Unit Weight of Normal Weight Concrete

≔γb =-γc γw 82.6 ― lbf ft3 Buoyant weight of concrete

Designer: , PE Date: 11/02/2023 MVP Operations

Checker: , EIT Date: 11/02/2023 US Army Corps of Engineers Lock and Dam 2 Upper Guardwall Barge Impact St. Paul District

Determine Passive Resistance of all the Soil and Water

≔ELLowerSoil 676.28 ft Elevation of the river bottom at the end of UG25 (Determined from dive inspection)

≔ELFoundation 665.00 ft Elevation of foundation

≔Ps_midpoint =⋅⋅⋅⋅kp 0.5 ⎛⎝ -ELSoil ELFoundation⎞⎠ γ l1 728.2 kip Passive resistance of soil from UG24 to midpoint of UG25

Figure 3-2: Area of soil elevation change.

≔Area = d

21.5 ft

7 ―― x

21.5 x 75.3 ft2 Area of the sloped section of soil from mipdoint of UG25 to end of UG (See

Figure 2-2)

≔Ps_midpoint_end =⋅⋅⋅kp 0.5 γ ⎛

↲⎛⎝ ⋅Area ⎛⎝ -ELSoil ELLowerSoil⎞⎠⎞⎠

⋅⎛⎝ -ELLowerSoil ELFoundation⎞⎠ l1

330.7 kip Passive resistance of soil from midpoint of UG25 to end of UG25

≔Ps =+Ps_midpoint_end Ps_midpoint 1058.8 kip Total passive soil resistance.