FY20_PNSR0392_InspRpt Cascade Spillway Bridge.pdf

United States Department of the Interior

BUREAU OF RECLAMATION

1150 North Curtis Road Boise, ID 83706-1234

CPN-3233

2.2.4.21

VIA ELECTRONIC MAIL ONLY

Memorandum

To: Manager, O&M Technical Services, Middle Snake Field Office, Boise, Idaho Attention: VHoffman@usbr.gov

From: Chad M. Wallace, P.E.

O&M Supervisor (Acting), Facility Operations and Maintenance

Subject: July 2020 Routine Inspection Report for the Cascade Dam Spillway Bridge

(15CAS001), Boise Project, Idaho

Attached for your files and distribution to appropriate parties is an electronic copy of the subject report documenting the inspection conducted July 9, 2020, for Bridge 15CAS001. Comments received from your personnel, as well as from a peer review performed within this office, were incorporated into the report. The report reflects conditions at the time of the onsite inspection and does not include information resulting from studies, analyses, or changes that may have occurred in the interim.

Please contact Jill Armer-Brinkman, Civil Engineer, at jarmerbrinkman@usbr.gov or

(208) 378-5222 if you have any questions.

Attachment cc: RKent@usbr.gov DStaton@usbr.gov GDill@usbr.gov Enterprise Content System (ECS) Reclamation Bridge Inventory ADowning@usbr.gov cramsdell Date Stamp

Cascade Dam Spillway Bridge Inspection Report

Bridge elevation view, looking upstream.

Structure Information

Inspection Type: Routine Maintenance Type: Reserved Dam Road OVER Cascade Dam Spillway

Boise Project Columbia-Pacific Northwest Region Middle Snake Field Office

NBI #: 15CAS001 RBI #: PNSR0392

Date of Inspection: 7/9/2020 Date of Last Inspection: 4/11/2018

Bridge Name: Cascade Dam Spillway Bridge Inspection Date: 7/9/2020 NBI #: 15CAS001 Middle Snake Field Office

Inspection Information Inspection Members: Jill Armer-Brinkman (Team Leader), Columbia-Pacific Northwest (CPN) Regional Office Inspection Attendees: Andrew Downing, Middle Snake Field Office (Field Office); Sam Plant and Dan Dunnam, Black Canyon Facility Office Time of Inspection: Afternoon Temperature: 61°F Weather Description: Clear and sunny GPS Coordinates Latitude: 44.524631 Longitude -116.049581

Bridge Description

The Cascade Dam Spillway Bridge (15CAS001) is located at Cascade Dam approximately ½ mile north from the town of Cascade, Idaho in Valley County (Photographs 1 and 2). The bridge was constructed in 1947 and spans the concrete spillway chute at the right abutment of the dam. The bridge carries the road crossing the dam crest, provides access from the right abutment area to Cascade Reservoir campgrounds beyond the left abutment, and provides secondary access to the Idaho Power Company powerplant below the dam. Typical traffic crossing the bridge consists of passenger, recreational, and dam maintenance vehicles. Public access to the bridge is unrestricted. The current average daily traffic (ADT) volume is estimated at 100 vehicles, and the 20-year future (2040) ADT volume is estimated at 150 vehicles. The speed limit is not posted on either approach road into the bridge. Due to the sharp turns at each end of the bridge, the safe entrance speed is estimated to be 10 miles per hour (mph) or less.

Prior to 2002, the bridge was routinely inspected by the Idaho Transportation Department (ITD). In 2002, Reclamation’s CPN Regional Office assumed inspection responsibilities. The CPN Regional Office contracted with the U.S. Army Corps of Engineers to conduct the initial in-depth inventory inspection of the bridge on November 21, 2002. Subsequent routine inspections have been performed by Reclamation personnel.

The structure is a two-span, steel beam bridge with a timber deck (Photographs 3 and 4). The superstructure is supported on concrete abutments and a concrete pier. The bridge is immediately downstream from the operating deck for the spillway radial gates. The distance between the face of each concrete abutment and the face of the pier is 21 feet. The four steel 18WF47 beams of each span rest on rocker bearings at the abutments and at the center pier. The distance between the centerline of the bearing plates of each span is 22 feet 5 inches. The center-to-center distance between the webs of the beams is 3 feet 4 inches. There are ⅜- by 8½-inch plates between the beams at the ends and midpoint of each span that provided alignment during original installation and currently provides minimal lateral structural support. The wooden laminated deck is made up of 2- by 8-inch planks on their sides, nailed together at 30-inch intervals, staggered 10 inches in adjacent planks. The width of the deck is 12 feet between the 6-inch-square wooden curbs. The 6-inch-square wooden curbs are set on a scupper block every 3 feet and secured with ⅝-inch-diameter bolts to the deck and guardrail posts. The curbs and scupper blocks were replaced in October 2008. There are two wooden rails comprised of 2- by 10-inch timbers bolted to 6-inch-square posts along each side of the deck.

For the purposes of this report, the steel beams are numbered 1 through 4, upstream to downstream, in the right bay and 5 through 8, upstream to downstream, in the left bay. The right abutment bearings are designated RS1 through RS4, upstream to downstream. The left abutment bearings are labeled LS5 to LS8, upstream to downstream. The bearings on the top of the center pier at the left end of the right span beams are numbered CS1 through CS4, upstream to downstream. The bearings on top of the center pier at the right end of the left span beams are numbered CS5 through CS8, upstream to downstream. The location and designation of the beams and bearings are shown on Figure 1.

The configuration of the bridge is shown on Drawing Nos. 3-D-1672, 3-D-2136, and 3-D-213 attached to this report.

The bridge has a southeast-northwest orientation. Left and right references in this report refer to an orientation facing in the downstream direction of the spillway, with left being to the northwest and right to the southeast.

The bridge is operated and maintained by Reclamation Black Canyon Facility Office personnel and is a reserved works.

Bridge 15CAS001 is categorized as a Type 1 bridge under the Reclamation Bridge Inspection Program because it is open to the public (reference Reclamation Manual Directives and Standards FAC 07-01 Transportation Program, dated April 13, 2020). Type 1 bridges are typically inspected at 2-year intervals.

Bridges deficient due to condition or load capacity may require inspections on a more frequent basis.

Inspections are conducted under the guidelines contained in the National Bridge Inspection (NBI) Standards.

Report Approval Team Leader: Jill C. Armer-Brinkman, P.E. Reviewer: Sonja Norton

X Team Leader

Reviewer

Approver: Jill C. Armer-Brinkman, P.E.

Approver

Critical Findings Was a Critical Finding identified during this inspection? No If yes, describe the Critical Finding: NA

Critical Finding Plan of Action

If a Critical Finding was identified, what is the required Plan of Action to correct the issue? NA

Structural Evaluation Summary

The deck is assigned an overall condition rating of SATISFACTORY. The structural elements show some minor deterioration.

The superstructure is assigned an overall condition rating of GOOD. All the primary structural elements were sound, and no structural issues were noted. The overall condition of the bearing devices is being downgraded from good to fair because the grout pads were cracked and a corner of the grout pad under Bearing CS1 was displaced. However, the Superstructure NBI Item 59 condition rating is not being downgraded from 7.

According to the “Recording and Coding Guide for the Structure Inventory and Appraisal of the Nation's Bridges (NBI Coding Guide)”, under Item 59 – Superstructure, “the condition of bearings, joints, paint system, etc. shall not be included in the rating, except in extreme situations, but should be noted on the inspection form.” Refer to the Superstructure Condition section of this report for more details regarding the bearing devices.

The substructure is assigned an overall condition rating of GOOD. All the primary structural elements were sound, and no structural issues were noted.

Recommendations and Estimated Costs Definitions Category 1 Recommendations involving the correction of severe deficiencies where immediate responsive action is required to ensure structural safety and operational integrity of a facility.

Category 2 Recommendations covering a wide range of important matters where action is needed to prevent or reduce further damage or preclude possible operational failure of a facility.

Category 3 Recommendations covering less important matters but believed to be sound and beneficial suggestions to improve, or enhance, the operations and maintenance (O&M) of a project or facility.

Status of Previous Incomplete O&M Recommendations Number Description Cost Scheduled

Completion Status

None

New or Modified O&M Recommendations 2020-2-A Repair or remove and replace the damaged timber curb along the upstream right end of the bridge.

Cost range of $1,000 to $10,000

Fiscal year

(FY) 2024

INCOMPLETE.

Notes to Future Inspectors

The reservoir water surface elevation was 4825.86 feet the day of this inspection. Under the Hazardous Energy Control Program, the radial gates need to be locked out prior to entering the spillway chute. Inspectors attached personal locks to the clearance (lock box) in the spillway control house. In addition, the spillway was entered using a ladder on the left side of the spillway chute during this inspection. The spillway wall downstream from the crest is 15 feet high. Fall protection equipment is required to be worn while climbing down the ladder to enter the spillway chute.

The 2018 Routine Inspection Report states that it would be prudent to periodically inspect the underside of the bridge and the bearings with an under-bridge inspection truck (UBIT) provided by ITD. Use of a UBIT is not required because this bridge is not classified as a fracture critical structure. The inspection report further states that it is not possible to inspect the bearings without use of scaffolding or a UBIT. During this inspection, Field Office personnel used a Go-Pro Camera to take photographs of the upstream-most and downstream-most bearings along the abutments (RS1, RS4, LS5, and LS8) and the center pier (CS1, CS4, CS5, and CS8).

However, the bearings located in the middle of the abutments (RS2, RS3, LS6, and LS7) and the center pier (CS2, CS3, CS6, and CS7) were not able to be observed during this inspection. No unusual displacements of the beams and deck were observed; therefore, the middle bearings are believed to be in-place and functioning similarly to the upstream-most and downstream-most bearings.

A revised load rating for the bridge was performed in March 2017 by Denver Technical Service Center (TSC) personnel and was received by the CPN Regional Office December 8, 2017. The load rating was for all the American Association of State Highway and Transportation Officials (AASHTO) load rating vehicles, including specialized hauling vehicles SU4, SU5, SU6, and SU7, and emergency vehicles EV2 and EV3. The results from the March 2017 load rating performed by the TSC are listed in the Structure Load Rating section of this report.

Additional Inspection Notes and Deficiencies

The April 2020 Routine Bridge Inspection was rescheduled to July 2020 due to the O&M Program Manager directing bridge inspectors to delay all April bridge inspections to no earlier than July 2020 due to the risks associated with the coronavirus pandemic.

During this inspection, Type 3 object markers were posted at each corner of the bridge (Photographs 5 and 6).

Signs along the roadway leading to the right end of the bridge and signs on the dam crest roadway were placed to notify approaching vehicles of the one-lane bridge and vehicle-size and parking restrictions (Photographs 7 and 8).

The Approach Alignment NBI Item 72 condition rating is being upgraded from 3 in the previous inspection to 4.

A condition rating of 3 is defined as “Basically intolerable, requiring high priority of corrective action.” A condition rating of 4 is defined as “Meets minimum tolerable limits to be left in place as is.” A substantial reduction in speed is required to cross the bridge from both the right and left approaches; however, it meets the minimum tolerable limits to be left in place. Refer to the Approach Roadway Alignment section of this report for more details regarding the roadway approaches into the bridge.

Field Inspection Report Condition Rating Codes for Items 58-62 N Not Applicable 3 Serious Condition – loss of section, deterioration, spalling, or scour have seriously affected primary structural components.

Local failures are possible. Fatigue cracks in steel or shear cracks in concrete may be present

9 Excellent Condition 8 Very Good Condition – no problems noted.

7 Good Condition – some minor problems.

2 Critical Condition – advanced deterioration of primary structural elements. Fatigue cracks in steel or shear cracks in concrete may be present or scour may have removed substructure support. Unless closely monitored it may be necessary to close the bridge until corrective action is taken.

6 Satisfactory Condition – structural elements show some minor deterioration.

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

1 “Imminent” Failure Condition – major deterioration or section loss present in critical structural components or obvious vertical or horizontal movement affecting structure stability.

Bridge is closed to traffic, but corrective action may return structure to light service.

4 Poor Condition – advanced section loss, deterioration, spalling, or scour

0 Failed Condition – out of service; beyond corrective action.

Condition Rating Code Equivalents for Sub-Components G = Good (7-9) F = Fair (5-6) P = Poor (0-4) N = Not Applicable UNK = Unknown 58 Deck Condition 6 - Satisfactory

1. Deck Slab F Notes: Photographs 5, 6, and 9 through 23

58.1 - Some minor checks were visible at the ends of the deck planks and on the visible portions of the deck. As reported during previous inspections, there was a minor amount of rot (approximately ⅛ to ¼ inch) observed along the running boards in a few areas. As reported during previous inspections, the tops of the deck boards were not flush with the adjacent boards so that the surface was slightly uneven. The underside of the bridge was observed from the bottom of the spillway channel and could not be closely inspected. As reported during previous inspections, the underside of the deck planks was stained dark.

58.3 - According to the 2018 Routine Inspection Report, the running boards were replaced by Black Canyon Facility Office personnel in April 2017. The three running boards were replaced with four new running boards per wheel lane. Each running board was 4 inches thick by 12 inches wide. In addition, Black Canyon Facility Office personnel installed new metal plates at the ends of the running boards to provide a smooth transition from the approaches in March 2019. During this inspection, the running boards were in good condition and without problems.

58.5 - Timber curbs were provided along each side of the bridge. As reported during previous inspections, the timber curbs had some gouges and scrapes from vehicle impacts and snowplow blades. The most severely damaged area documented since 2012 was in the middle of the downstream curb. The curb was split and the bolt attaching it to the deck was bent (Photograph 13). Above that area, the bottom rail had been gouged. The damaged area appears to be unchanged

2. Expansion Joints N

3. Wearing Surface G

4. Rideability G

5. Curbs, Sidewalks, and Median F

6. Parapets and/or Railing G

7. Drains and Drainage G

8. Utilities N

9. Deflection and/or Vibration G

10. Other and the downstream curb and rail were not loose. During this inspection, the timber curb along the upstream right end of the bridge was missing (Photographs 15 and 16).

Recommendation 2020-2-A is being issued to repair or remove and replace the damaged timber curb along the upstream right end of the bridge.

58.6 - Wooden rails were provided along each side of the bridge. In October 2008, the 2- by 10-inch horizontal wooden rails were installed in 16-foot lengths and arranged so the joints were staggered at each post. The wooden rails were attached to 6-inch-square posts attached with two bolts to a deck plank that extends beyond the edge of the deck (Photograph 18). A bolt connects the post to the curb. During this inspection, the rails were in good condition. As reported during previous inspections, the posts were checked with some splits through some of the bolt holes and were in fair condition. In addition, the deck plank ends attached to the second post from the upstream left end of the bridge were reported as split. During this inspection, the deck plank ends appeared to be unchanged.

The post was not loose but should continue to be monitored as part of routine maintenance.

58.7 - Sixteen approximately 1-inch diameter drain holes were drilled through the deck (Photograph 19). Some of the drain holes were plugged with soil and debris. Black Canyon Facility Office personnel clean the drain holes on an annual basis. As noted in previous inspection reports, a drill bit was stuck in the drain hole through the deck between Beam Nos. 6 and 7.

58.8 - The utility pipes located upstream from the bridge are not attached to the bridge.

59 Superstructure Condition 7 - Good

1. Bearing Devices F Notes: Photographs 20 through 34

59.1 - The bearings were not visible from the spillway floor or from the bridge deck during this inspection. There are eight rocker bearings at the abutments (RS1 through RS4 and LS5 through LS8) and eight rocker bearings at the center pier (CS1 through CS8). During the 2014 Routine Inspection, all the bearings were closely inspected using a UBIT provided by ITD.

A table is included in the 2014 Routine Inspection Report documenting the observations made for each bearing. During this inspection, Field Office personnel used a Go-Pro Camera to take photographs of the upstream-most and downstream-most bearings (RS1, RS4, LS5, LS8, CS1, CS4, CS5, and CS8).

These bearings were in similar condition as that documented in the 2014 Routine Inspection Report. During this inspection, the grout pads were cracked and a corner of the grout pad under Bearing CS1 was displaced (Photographs 33 and 34). A photograph review between this inspection and the 2014 Routine Inspection shows Bearing CS1 to be in similar condition with no additional displacement of the grout pad or tilting of the bearing. During this inspection, the bearings observed through

2. Girders or Beams G

3. Arches or Slabs N

4. Floorbeams and Stringers N

5. Trusses N

6. Diaphragms and Bracing G

7. Paint G

8. Connections or Welds N

9. Deflection and/or Vibration G

10. Alignment G

11. Other the photographs taken by Field Office personnel, showed there was some minor corrosion. The shims were intact and not dislodged. The containment of the shims by the intact grout appeared to be in good condition. The visible bearing plates were not displaced. The rocker bearings were functioning as intended. There was no unusual displacement of the beams or bridge deck. No crushing of the concrete below the bearings was observed. The overall condition of the bearing devices is downgraded to fair because the grout pads were cracked and the corner of the grout pad under Bearing CS1 was displaced.

59.2 - During this inspection, the beams were viewed from the spillway floor and could not be closely inspected. The beams appeared to be straight without any distortions or deflections.

As reported during previous inspections, some minor surface corrosion was noted in a few areas.

59.7 - The protective coating on the beams appeared to be intact and in good condition.

60 Substructure Condition 7 - Good Abutments Notes: Photographs 24 through 26 and 35

60.1 - No significant deterioration, cracking, spalling, joint offsets, or other indication of structural distress on the abutments were noted. As reported during previous inspections, a few thin cracks were located in the right abutment below Bearing RS1. As reported during the 2018 Routine Inspection, a crack and spall were observed at the top of the right spillway wall at the base of a metal handrail post adjacent to the downstream side of the bridge (Photograph 35). The crack appeared to be in similar condition as that documented in the 2018 Routine Inspection Report.

60.10 - No indication of settlement or rotation of the abutments was noted.

1. Breastwalls or Columns G

2. Piles N

3. Caps and/or Bearing Seats G

4. Backwalls and/or Bulkheads N

5. Foundations UNK

6. Wingwalls N

7. Weep Holes N

8. Expansion Joints N

9. Erosion and/or Scour G

10. Settlement or Deflection G

11. Slope Protection G

12. Other Piers Notes: Photographs 24 and 35 through 40

60.13 - No significant deterioration, cracking, spalling, or other indication of structural distress on the center pier was noted. As reported during previous inspections, minor cracking was observed and appeared to be in similar condition during this inspection. A thin diagonal crack was observed on the left side of the center pier below the upstream-most Bearing CS5 (Photographs 36 and 37). Note CS5 is located on top of the center pier at the right end of the left span Beam No. 5 (refer to Figure 1). During this inspection, the thin diagonal crack appeared to be in similar condition with no horizontal displacement observed along the crack. As reported during previous inspections, a thin diagonal crack was observed on both sides of the downstream end of the center pier (Photographs 39 and 40). During this inspection, the thin diagonal crack appeared to be in similar condition.

A close inspection of the bearings was performed in 2014 using a UBIT provided by ITD. According to the 2014 Routine Inspection

13. Walls and/or Columns G

14. Piles N

15. Caps and/or Bearing Seats G

16. Foundations UNK

17. Erosion and/or Scour G

18. Settlement or Deflection G

19. Other

Report, thin cracks in the center pier were observed below Bearings CS1, CS3, CS5, and CS7.

60.17 - According to the 2018 Routine Inspection Report, undercutting of the downstream end of the center pier had been observed for many years. The depth of the undercut was reported to be approximately 10 inches. The undercut area was filled with grout in 2015 (Photographs 24 and 38). During this inspection, the grout was intact and in good condition.

60.18 - No indication of settlement or rotation of the center pier was noted.

60.19 - The bridge is located approximately 20 feet upstream from the downstream end of the center pier.

61 Channel and Channel Protection Condition 7 - Good

1. Alignment G Notes: Photographs 41 and 42

61.2 - The spillway chute floor was rough with 1 to 2 inches of concrete relief from erosion and freeze-thaw damage. The damage has been documented for many years.

61.4 - The inlet channel upstream from the radial gates was submerged and not visible during this inspection.

61.5 - Little debris buildup had accumulated downstream from the radial gates.

2. Erosion and/or scour G

3. Channel Protection G

4. Waterway Obstructions G

5. Adequacy of Opening G

6. Streambed Composition G

7. Other

62 Culverts N - Not Applicable

1. Alignment N Notes:

2. Settlement N

3. Joints N

4. Scour N

5. Adequacy of Opening N

6. Wingwalls N

7. Other

Scour Critical Bridges Every bridge should have a scour evaluation report on-file that documents the code for Item 113 – Scour Critical Bridges. Every routine inspection should verify that the Item 113 code is still valid.

Item Current

Rating Valid?

(Yes/No)

Notes

113 – Scour Critical Bridges

6 Yes The bridge is located over a gated spillway designed for discharges of 12,500 cubic feet per second. However, a scour calculation/evaluation has not been made for this bridge. The bridge still needs to be evaluated for scour potential.

Traffic Safety Rating Codes 0 – Does not meet standards or a safety feature is required, and none is provided

1 – Meets currently applicable standards

N – Not applicable or a safety feature is not required

Item Rating Notes 36A – Bridge Railing 1 A 6-inch-square timber curb on scupper blocks with a wooden railing is located on the upstream and downstream edges of the bridge (Photographs 9 through 12). The existing curbs are approximately 10 inches high and anchored to the timber deck.

According to previous inspections, the timber curb on scupper blocks and wooden railing are considered to be adequate to contain errant vehicles traveling at the low speeds necessary to enter the bridge. Therefore, a new rail/curb system is not deemed necessary.

36B – Transitions N No transitions, approach guardrail, or approach guardrail ends were provided. Due to the vehicle parking areas located on either side of the right and left approaches installing these traffic safety features is not possible. Concrete Jersey barriers were placed near the upstream corners of the bridge and along the parking areas on the downstream side of the bridge.

36C – Approach Guardrail N No transitions, approach guardrail, or approach guardrail ends were provided. Due to the vehicle parking areas located on either side of the right and left approaches installing these traffic safety features is not possible. Concrete Jersey barriers were placed near the upstream corners of the bridge and along the parking areas on the downstream side of the bridge.

36D – Approach Guardrail Ends N No transitions, approach guardrail, or approach guardrail ends were provided. Due to the vehicle parking areas located on either side of the right and left approaches installing these traffic safety features is not possible. Concrete Jersey barriers were placed near the upstream corners of the bridge and along the parking areas on the downstream side of the bridge.

Waterway Adequacy See Coding Guide for a description of each rating code Item Rating Notes 71 – Waterway Adequacy 9 The bridge deck and roadway approaches are above the flood water elevations. The chance of overtopping is remote.

Approach Roadway Alignment 8 No speed reduction required when approaching structure 6 Minor speed reduction required when approaching structure 3 Substantial speed reduction required when approaching structure Interpolate between defined values when necessary Item Rating Notes 72 – Approach Roadway Alignment

4 The approach to the left end of the bridge is level with a 45-degree angle to the bridge (Photographs 7 and 43). The approach to the right end of the bridge is paved with asphalt, on a downhill slope, and enters the bridge at an approximately 60-degree angle (Photographs 8 and 44). The alignments of both the right and left approaches to the bridge requires a substantial reduction in speed. It is estimated vehicles enter the right and left ends of the bridge at 10 mph or less. A new concrete apron was placed at both ends of the bridge adjacent to the bridge deck. New metal plates were installed at the ends of the running boards. See Photographs 5, 6, 14, and 15. The concrete aprons and metal plates were installed in March 2019 by Black Canyon Facility Office personnel.

Structure Load Rating Load Rating Details Design Loading Level: HS20-S-16-44 Date of Load Rating Calculation: 3/7/2017 Load Rated By: Clark Larsen Does Structure Require Load Posting? No Load Rating Controlling Member: Steel beam flexure controls the load rating.

Load Rating Notes/Summary A revised load rating for all the AASHTO load rating vehicles, including the specialized hauling vehicles SU4, SU5, SU6, and SU7, and emergency vehicles EV2 and EV3, was performed by Denver TSC personnel in March 2017. The Allowable Strength Design rating method was used to calculate the load rating. See the results from the load rating below.

Load Posting/Rating Evaluation Yes/No/NA Notes Is Load Posting Properly Installed (when required)?

NA The revised load rating dated March 2017 states that no posting of the bridge is required. However, the bridge is posted for 20 tons. A 20-ton load limit sign is posted on the spillway control house and also along the right approach roadway (Photographs 7 and 8). According to the 2018 Routine Inspection Report, a previous recommendation was issued to post the bridge for 20 tons. The 2016 Routine Inspection Report includes information regarding past history on previous load ratings and postings.

See the 2016 Routine Inspection Report for more information regarding the previous load ratings and postings.

Does this structure require a revised load rating?

No A revised load rating for all the AASHTO load rating vehicles, including the specialized hauling vehicles SU4, SU5, SU6, and SU7, and emergency vehicles EV2 and EV3, was performed by Denver TSC personnel in March 2017. No structural deficiencies or design changes have been made to the structure; therefore, a revised load rating is not required.

The values used for NBI Items 64 and 66 for a HS-20 type vehicle are highlighted in blue in the following table.

Rating Vehicle

Inventory Rating Factor

NBI Item

Inventory (Tons)

Operating Rating Factor

NBI Item 64 Operating

(Tons)

HS-20 0.86 31.1 1.24 44.6

H-20 0.86 17.3 1.24 24.8

Type 3 0.98 24.4 1.40 35.0 Type 3S2 1.07 38.5 1.53 55.2 Type 3-3 1.19 47.5 1.70 68.1

NRL 0.73 29.2 1.05 41.9

SU4 0.83 22.5 1.19 32.3

SU5 0.78 24.2 1.12 34.6

SU6 0.73 25.5 1.05 36.5

SU7 0.73 28.3 1.05 40.6

EV2 0.83 23.7 1.18 34.0

EV3 0.54 23.0 0.77 33.0

Structure Inventory & Appraisal (1 of 2)

Structure Inventory & Appraisal (2 of 2)

Photographs

Photo 1: Location of Bridge 15CAS001.

Photo 2: Aerial photograph of Bridge 15CAS001 vicinity.

Photo 3: Looking downstream at the upstream side of the bridge (arrow). The operating deck for the spillway radial gates is located upstream from the bridge.

Photo 4: Looking upstream at the downstream side of the bridge.

Photo 5: Looking to the right across the bridge. Note the Type 3 object markers at the left end of the bridge.

Also, note the new concrete apron adjacent to the left end of the bridge.

Photo 6: Looking to the left across the bridge. Note the Type 3 object markers at the right end of the bridge.

Also, note the concrete apron adjacent to the right end of the bridge.

Photo 7: Looking to the left toward the left approach to the bridge. Note the “20 Ton Load Limit” sign posted on the spillway control house.

Photo 8: Looking to the right toward the right approach to the bridge. Note the “ONE LANE BRIDGE” and “20 Ton Load Limit” signs posted on the right approach roadway.

Photo 9: Looking upstream and to the right across the bridge toward the timber curb and wooden railing.

Photo 10: Looking upstream and to the left across the bridge toward the timber curb and wooden railing.

Photo 11: Looking downstream and to the right across the bridge toward the timber curb and wooden railing.

Photo 12: Looking downstream and to the left across the bridge toward the timber curb and wooden railing.

Photo 13: The split in the downstream curb and the bent bolt attaching the curb to the timber deck.

Photo 14: Looking downstream along the left end of the bridge. Note the new concrete apron and metal plates along the left end of the bridge.

Photo 15: Looking downstream along the right end of the bridge. The arrow points to the damaged timber curb along the upstream right end of the bridge (Recommendation 2020-2-A). Note the new concrete apron and metal plates along the right end of the bridge.

Photo 16: Closeup of the damaged timber curb along the upstream-right end of the bridge (Recommendation 2020-2-A).

Photo 17: Typical look and condition of the timber curbing and bridge railing installed along both edges of the bridge deck.

Photo 18: The base of a rail post attached to the deck plank end.

Photo 19: One of the drain holes drilled through the timber deck; typical look and condition of all drain holes.

Photo 20: The underside of the left bridge span.

Photo 21: The underside of the right bridge span.

Photo 22: Looking downstream and at the underside of the left bridge span.

Photo 23: Looking downstream and at the underside of the right bridge span.

Photo 24: The downstream side of the radial gate structure and the bridge. The arrow points to the previously undercut area at the downstream end of the center pier that was filled with grout in 2015.

Photo 25: Looking upstream at the left abutment and the underside of the left bridge span.

Photo 26: Looking upstream at the right abutment and the underside of the right bridge span.

Photo 27: The upstream-most right Bearing RS1 for Beam No. 1 of the right bridge span. Photograph taken by Field Office personnel.

Photo 28: The downstream-most right Bearing RS4 for Beam No. 4 of the right bridge span. Photograph taken by

Photo 29: The upstream-most left Bearing LS5 for Beam No. 5 of the left bridge span. Photograph taken by Field Office personnel.

Photo 30: The downstream-most left Bearing LS8 for Beam No. 8 of the left bridge span. Photograph taken by

Photo 31: Left Bearing CS4 for Beam No. 4 of the right bridge span. The right Bearing CS8 for Beam No. 8 is visible in the background. Photograph taken by Field Office personnel.

Photo 32: Right Bearing CS5 for Beam No. 5 of the left bridge span. The left Bearing CS1 for Beam No. 1 is visible in the background. Photograph taken by Field Office personnel.

Photo 33: Left Bearing CS1 for Beam No. 1 of the right bridge span. The right Bearing CS5 for Beam No. 5 is visible in the background. Note the corner of the grout pad was displaced. Photograph taken by Field Office personnel.

Photo 34: Closeup of the left Bearing CS1 for Beam No. 1 of the right bridge span. The shims were intact and not dislodged. The containment of the shims by the intact grout appeared to be in good condition. Photograph taken by Field Office personnel.

Photo 35: Looking to the right along the downstream side of the bridge. The arrow points to the crack at the base of the post at the top of the right spillway wall adjacent to the bridge.

Photo 36: Looking to the right along the upstream side of the bridge. Note the conduit pipes are not attached to the bridge. The arrows point to the crack located in the left side of the center pier below the upstream-most Bearing CS5 for the left bridge span. See Photograph 37.

Photo 37: The left side of the center pier. The arrows point to cracks in the center pier below the upstream-most right Bearing CS5 and Bearing CS7 of the left bridge span.

Photo 38: Looking downstream at the right side of the center pier. The arrow points to the grout placed to fill the undercutting of the pier.

Photo 39: Looking upstream at the left side of the center pier. The arrows point to the thin diagonal crack in the center pier.

Photo 40: Looking upstream at the right abutment, the right side of the center pier, and the underside of the right span of the bridge. The arrows point to the thin diagonal crack in the center pier.

Photo 41: Looking at the reservoir upstream from the bridge.

Photo 42: Looking at the spillway channel downstream from the bridge.

Photo 43: Looking toward the left approach to the bridge.

Photo 44: Looking toward the right approach to the bridge.

Figure

CS5

CS1

LS5LS6LS7LS8

RS4 RS3 RS2 RS1

CS4

CS8 CS7 CS6

CS2CS3

FLOW

FLOW

8 7 6 5

4 3 2 1

Figure 1: Bridge beam and bearing numbering sketch (not to scale).

Drawings

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