FY20_SourdoughCGBridge_InspRpt 7_22_2020 final.pdf

Form Revised Dec. 2013

Sourdough Campground Bridge

BRIDGE INSPECTION REPORT

INSPECTION TYPE: Routine

Sourdough Campground Entry Road over Sourdough Creek

Anchorage District, AK

Glennallen Field Office

FAMS Location #: L59815

FHWA Structure #: 000000000L59815

Date of Inspection: 6/30/2020

Date of Previous Inspection: 6/12/2018

MILEPOST: 0.1 MI

Aliquot Part: NE1/4 SW1/4 Section: 25 Township: 9N Range: 2W Meridian: Copper River

Time: 12:30 PM Temperature: 59 °F

Weather: Partly Cloudy

Inspection Team: Curt Fortenberry, Team Leader:

Print: Curt Fortenberry Signature Date Report Reviewed By:

Print: Dana Cork Signature Date Report Approval:

Print: Curt Fortenberry Signature Date

U.S. DEPARTMENT OF INTERIOR

BUREAU OF LAND MANAGEMENT

BRIDGE INSPECTION PROGRAM

CURTIS FORTENBERRY Digitally signed by CURTIS FORTENBERRY Date: 2020 07 22 11:06:58 08'00'

DANA CORK

Digitally signed by DANA CORK Date: 2020.07.22 12:18:26 -07 00'

CURTIS FORTENBERRY

Digitally signed by CURTIS

FORTENBERRY

Date: 2020.07.22 11:21:48 -08'00'

Sourdough Campground Bridge Glennallen Field Office FAMS Location #: L59815 Inspection Date: 6/30/2010

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STRUCTURE INVENTORY AND APPRAISAL SHEET

Sufficiency Rating:

Note: Use the NBI Coding Guide for reference. Enter all measurement in English Units. When applicable, describe NBI code that is entered (e.g. 01-Slab, 1-Highway, 4-Poor, etc). Items 67, 68, and 69 are automatically calculated by FHWA and do not need to be populated.

IDENTIFICATION

1.State 568- WY 8.Struc. # 000000000L59815 2.Hwy District 00 7.Facility

Carried Sourdough CG Entry Road

3.County Code

261-Valdez Cordova

9.Location 17 mi N of Gakona Jct.

6.Feature Intersected Sourdough Creek 5A.On/Under 1- On 5B.Rte Sign. 6- Federal 5C.Lvl. Serv. 4- Spur 5D.Rte. # 00000 5E.Directional Suffix

0 98A.Border State Code

98B.Border % Responsible

99.Border Bridge #

4.Place Code 00000 11.Mile Post 0.1 mi.

16.Latitude 62.52737° 17.Longitude -145.51676°

STRUCTURE TYPE AND MATERIALS

46.# Approach Spans

000 45.# of Spans Main Unit

43A.Structure Material 7- Timber 43B.Structure Type of Design 02- Girder 44A.Approach Material 0- No approach spans 44B.Approach Type of Design

00- No approach spans

107.Deck Type 8- Timber 108A.Wearing Surface 7- Timber 108B.Type of Membrane 0- None 108C.Deck Protection 0- None

AGE AND SERVICE

27.Year Built 1991 106.Year

Reconstructed

42A.Type of Service on 1- Highway 42B.Type of Service under 5- Waterway 28A.Lanes on 02 28B.Lanes Under 00 19.Detour Length 199 mi. 29.ADT 50 109.Truck ADT

30.Year of ADT 2018

GEOMETRIC DATA

48.Length Max Span

48.83 ft. 49.Structure Length

52.42 ft.

50A.Curb/Sidewalk Width Left

1 ft. 50B.

Curb/Sidewa k Width Right

1 ft.

51.Width curb-curb 24 ft. 52.Width Out-Out 26 ft.

47.Route Total Horizontal Clearance 24 ft.

32.Approach Roadway Width (w/ Shoulders) 20 ft.

33.Median 0- None 34.Skew 0- No 35.Structure

Flared 0- No

10.Route Min. Vertical Clearance 99.99 53.Min. Vertical Clearance Over Bridge 99.99 54A.Min. Vertical Underclearance Reference N 54B.Min. Vertical Underclearance 0000 55A.Min. Lateral Underclearance Reference N 55B.Min. Lateral Underclearance Right 000 56.Min. Lateral Underclearance Left 000

NAVIGATION DATA

38.Navigation Control 0- No permit required 39.Vertical Clearance

0000 40.Horizontal Clearance

00000

111.Pier Protection

116.Lift Bridge Vertical Clearance

INSPECTION

91.Frequency 24 mos. 90.Insp. Date 0618 92A.Fracture Critical Frequency

N 93A.Fracture Critical Date

92B.Under Water Frequency

N 93B.Under Water Date

92C.Special Inspection Freq.

N 93C.Special Inspection Date

CLASSIFICATION

12.Base Hwy Network

0 13B.Subroute #

13A.LRS Inventory Route 100.Defense Highway

0 101.Parallel Structure

N

102.Direction of Traffic

2- 2 way traffic

103.Temporary Structure

104.Highway System

0 112.NBIS

Length

Y

105.Federal Lands Hwy

0 110. National Truck Network

20.Toll Facility

3- Free 26.Functional Class

09- Local, rural

37.Historical Significance 5- not elig ble 22.Owner 68- BLM 21.Maintenance Responsibility 68- BLM

CONDITION

58.Deck 7 – Good 59.Super 5 – Fair 60.Sub 4 – Poor 62.Culvert N 61.Channel/Channel Protection 7 – Good

LOAD RATING AND POSTING

65.Inventory Rating Method

8- LRFR 63.Operating Rating Method

8- LRFR

66.Inventory Rating

0.44 64.Operating Rating

0.58

31.Design Load

5- HS20 70.Posting 1- 30-39% below

41.Posting Status P- Posted for load

APPRAISAL

36A.Bridge Rail

1 36B.Transition N

36C.Approach Rail

N 36D.Approach Rail Ends

N

71.Waterway Adequacy

6- Satisfactory

72.Approach Alignment

6- Minor speed reduc.

113.Scour Critical 5- Scour within footing depths

PROPOSED IMPROVEMENTS

94.Bridge Cost

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95.Roadway Cost

76.Length of Improvement

80 ft.

96.Total Cost 114.Future

ADT

97.Year of Cost Estimate

2020 115.Year of Future ADT

75A.Type of Work 31- Replace bridge 75B.Work Done By 1- Contract

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CRITICAL FINDINGS

Were any Critical Findings identified?: No If Yes, provide detailed explanation:

FOLLOW-UP PLAN

If a Critical Finding was identified, what is the recommended Follow-Up Plan?:

STRUCTURE EVALUATION SUMMARY

Sourdough Campground Bridge is in poor to fair overall condition. The superstructure remains in fair condition with the only concern being the general weathering and deterioration of the over 60 year old glue-laminated girders. The main concern at the bridge is the horizontal and vertical differential movement that is occurring. The joint opening at each corner of the bridge varies between 0” and 4.5” which indicates horizontal differential movement. In addition, 6 of the 16 anchor bolts have sheared off due to excessive horizontal movement and the remaining anchor bolts are all bent. All 4 bolts of G3’s anchor bolts have been sheared off leaving no anchorage for that member. The remaining anchor bolts were bent in the contracted state likely due to winter temperatures well below -30°F.

There is also upward heaving of the bridge likely caused by frost heaving. The bridge was designed with no superelevation so each corner of the bridge should be the same elevation.

However, the upstream side of the concrete backwall at Abutment 2 is 0.8’ higher than the downstream side of Abutment 1. This measurement in the 2016 inspection was 0.71 ft. which indicates that the movement continues to occur. The concrete cap beams above the abutment columns are elevated off the existing ground in multiple locations which indicates that the bridge is heaving upward rather than settling downward. This movement of the bridge has caused the conduit on the downstream side of the bridge to separate at Abutment 2. The excessive movement of the bridge caused the substructure rating to be reduced to poor condition.

The bridge is also posted for weight restriction due to the superstructure. In general, the bridge is deteriorating and nearing the end of its useful life. The bridge is funded for replacement and design in underway under agreement with the Federal Highways Western Federal Lands. Replacement year is expected to be 2022. Current proposal is for an span of 80’ for floodway.

The NOC provides bridge inspection services upon request for bridges under the jurisdiction of the Bureau of Land Management (BLM). The bridge inspections services provided are in compliance with the National Bridge Inspection Standards (NBIS). As a minimum, any BLM owned, public vehicular structures having an overall length of 20 feet or greater should be inspected in accordance with the NBIS. Tunnels, trail bridges, major culverts and other significant structures may be inspected upon request.

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FIELD INSPECTION REPORT

CONDITION RATING CODES FOR ITEMS 58 - 62

N NOT APPLICABLE

9 EXCELLENT CONDITION

8 VERY GOOD CONDITION - no problems noted.

7 GOOD CONDITION - some minor problems.

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.

4 POOR CONDITION - advanced section loss, deterioration, spalling, or scour.

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.

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 structure until corrective action can be taken.

1 IMMINENT FAILURE CONDITION - major deterioration or section loss present in critical structural components or obvious vertical or horizontal movement affecting structure stability. Structure is closed to traffic but corrective action may return structure to light service.

0 FAILED CONDITION - out of service; beyond corrective action.

CONDITION RATING CODE EQUIVALENTS FOR SUB-ELEMENTS

G = GOOD (CODES 7 - 9)

F = FAIR (CODES 5 - 6)

P = POOR (CODES 0 - 4)

58 Deck Condition 6- Satisfactory

1. DECK SLAB G Notes (w/item reference):

58.2- Expansion joints have gaps except SE corner which has fully closed and compressed the joint material. The expansion joint material has dropped due to gaps at Abutment 2. Gravel from the approach roadway is falling in the expansion joint and collecting on the bearing seat.

58.3 Abrasion damage to wearing surface and minor decay in deck planks is approximately 1/4”.

58.4 Four potholes in the approach reducing rideabilty.

58.8- Large gap in the electrical conduit on the d/s of A2.

2. EXPANSION JOINTS P

3. WEARING SURFACE P

4. RIDEABILITY F

5. CURBS, SIDEWALK AND MEDIAN G

6. PARAPETS AND/OR RAILINGS G

7. DRAINS AND DRAINAGE G

8. UTILITIES F

9. DEFLECTION AND/OR VIBRATION F

10. OTHER

59 Superstructure Condition 5- Fair

1. BEARING DEVICES P Notes (w/item reference):

59.2- Girders are over 60 years old. Weathering is evident, but the creosote coating is still functional. Checks are evident although minor and shallow.

Hammer sounding of the girders revealed no substantial concerns with rot or decay. 1 small split observed at d/s side of G1.

2. GIRDERS OR BEAMS F

3. ARCHES OR SLABS N

4. FLOOR BEAMS AND STRINGERS N

5. TRUSSES N

6. DIAPHRAGMS AND BRACING G

7. PAINT G

8. CONNECTIONS/WELDS G

9. DEFLECTION AND/OR VIBRATION G

10. ALIGNMENT F

11. OTHER

60 Substructure Condition 4- Poor

Abutments Notes (w/item reference):

60.3- There is an accumulation of gravel on the bearing seat and behind the girder which could be restricting movement of the girders.

60.5- Differential upheaving most likely due to frost heaving

60.8- All anchor bolts are either sheared off or badly bent. Bridge fully contracted in June, leaving concerns for Winter months. 3 anchor bolts sheared off at each abutment. All four of the anchor bolts are sheared off at G3 and G4 has 2 anchor bolts sheared off on opposite abutments.

1. BREASTWALLS OR COLUMNS F

2. PILE BENTS N

3. CAPS AND/OR BEARING SEATS F

4. BACKWALLS AND/OR BULKHEADS F

5. FOUNDATIONS P

6. WINGWALLS F

7. WEEP HOLES N

8. ANCHOR ASSEMBLIES P

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Substructure Condition, con’t.

9. EROSION AND/OR SCOUR G 60.10- Abutments are settling. SE corner is 0.8’ lower than NW (highest) corner.

Abutments are not parallel; the downstream side is 5” closer than the upstream side.

60.11- The riprap is small and unstable at Abutment 2

10. SETTLEMENT OR DEFLECTION P

11. SLOPE PROTECTION F

12. OTHER

Piers Notes (w/item reference):

13. WALLS AND/OR COLUMNS

14. PILE BENTS

15. CAPS AND/OR BEARING SEATS

16. FOUNDATIONS

17. EROSION AND/OR SCOUR

18. SETTLEMENT OR DEFLECTION

19. OTHER

61 Channel and Channel Protection Condition 7- Good

1. ALIGNMENT F Notes (w/item reference):

61.1- The channel has some sharp turns and there are some small rapids d/s of the bridge.

61.3- The riprap is small, unstable, and not very deep. New scour observed at both abutments with undermining of pile cap beam up to 29”. Concrete piles have been exposed on A2 which is the worse of the two abutments. Geotech fabrics has been pulled out by scour. A1 has rip rap sloughing as well.

2. EROSION AND/OR SCOUR G

3. CHANNEL PROTECTION F

4. WATERWAY OBSTRUCTIONS G

5. ADEQUACY OF OPENING G

6. STREAMBED COMPOSITION G

7. OTHER

62 Culverts N- NA

1. BARREL(S) Notes (w/item reference):

2. FOOTINGS

3. HEADWALLS

4. WINGWALLS

5. DEBRIS AND/OR SILT

6. EROSION AND/OR SCOUR

7. SETTLEMENT AND/OR

DEFLECTION

8. ADEQUACY OF COVER

9. PARAPETS AND/OR RAILINGS

10. ROADWAY SURFACE

11. RIDEABILITY

12. OTHER

ASSESSMENT

71 Waterway Adequacy 6 72 Approach Roadway Alignment 6- Minor speed reduc.

113 Scour Critical Bridges (0-9, T, U, N) 5- Scour within limits of footings

36A Safety Features – Railing (0-Doesn’t meet Standards, 1-Meets Standards, N-NA) 1 36B Safety Features – Transitions Railing (0-Doesn’t meet Standards, 1-Meets Standards, N-NA) N 36C Safety Features – Approach Railing (0-Doesn’t meet Standards, 1-Meets Standards, N-NA) N 36D Safety Features – Terminal Railing (0-Doesn’t meet Standards, 1-Meets Standards, N-NA) N

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STRUCTURE LOAD RATING

Design Rating Inventory Rating (RF) Operating Rating (RF)

HL-93 0.443 0.575

Legal Rating Rating (RF) Type 3 1.03 Type 3S2 1.12 Type 3-3 1.24

SU4 0.897

SU5 0.831

SU6 0.747

SU7 0.693

Design Loading Level: HS-20 Place X next to appropriate load rating description:

Original Design Load Valid Original Design Load Not Valid Original Load Rating Calculation Valid

X Original Load Rating Calculation Revised Date of Load Rating Calculation: 1/12/2016 Load Rating Controlled By: Timber flexure in exterior girder at midspan

*Note* - If the Rating Factor (RF) for the HL-93 loading is > 1.00, then the legal loads (3, 3S2, 3-3) do not need to be calculated.

Load Rating Remarks:

Sourdough Campground Bridge does not have adequate capacity for all legal loads and needs to be posted. The recommended posting level is 21 Tons.

Detailed Notes/Deficiency Descriptions:

Hydraulic modeling displayed in the design plans estimates that there would be 3.55’ of freeboard during the 50 year flood event.

There is significant horizontal and vertical differential movement occurring at the bridge. The horizontal measurements between the concrete backwall and timber deck were:

o NW Joint Gap = 2.75” o SW Joint Gap = 4.5” o SE Joint Gap = no gap (measured from back of timber to concrete on the side) o NE Joint Gap = 2”

Using an arbitrary datum baseline of the NW corner, the elevation difference at the top of the concrete backwall at each corner of the bridge were:

o NW top of backwall = 0 baseline o SW top of backwall = -0.38 (drop) o SE top of backwall = -0.8 (lowest drop) o NE top of backwall = -0.174 (drop) These measurements show that there is a 0.8’) difference in elevation between A2 (NW side and NE side) and the downstream side of A1 (SE side).

During the previous inspections the maximum elevation difference was o 2013 difference of 0.63’ o 2014 difference of 0.73’ o 2016 difference of 0.71’.

A total of 6 anchor bolts are sheared off all others are bent.

o G3 has all 4 Anchor bolts are sheared off o G4 A1 d/s anchor bolt is sheared off as well as G4 A4 u/s is also sheared off

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Abbreviation Descriptions

A1 = Abutment 1 A2 = Abutment 2 u/s = upstream d/s = downstream G# = Girder number (Girder numbering system is in the General Bridge Description) B# = Beam number (Beam numbering system is in the General Bridge Description) P# = Pier number (Pier numbering system is in the General Bridge Description) NBI = National Bridge Inventory