Scour_Analysis_0005.pdf

Date

FEDERAL HIGHWAY ADMINISTRATION NATIONAL PARK SERVICE

FEDERAL LANDS BRIDGE OFFICE

LEVEL 1 SCOUR EVALUATION FORM

FACILITY:

STRUCTURE NUMBER:

STRUCTURE NAME:

FEATURE CARRIED:

FEATURE INTERSECTED:

DATE:

PREPARED BY:

CHECKED BY:

Date

REVIEW BY:

Date

GLACIER NATIONAL PARK

1430 - 007P

FISH CREEK BRIDGE

FISH CREEK CAMPGROUND ROAD

FISH CREEK

Page 1 of 10 Structure No.

1.0 SUMMARY OF FINDINGS

2.0 RECOMMENDATIONS

3.0 BASIS OF EVALUATION

4.0 MATERIALS AND DOCUMENTATION

2015 Bridge Inspection Report

Bridge number 1430 - 007P is identified as a scour susceptible (low risk). The bridge is located on Fish Creek. The bridge is rated as scour susceptible because it is a multi span bridge with known foundations and low priority because there is evidence of scour and is not below footings.

A level 2 analysis is recommended. Continue monitoring and inspections to track scour progress. Put in scour countermeasures to halter erosion and scour progress along abutments and banks. Fill in undermining along abutments.

Based on the 2015 bridge inspection, scouring along the the north face of the south pier has been partially filled in, however footings still remain exposed along entire width of bridge. Note that no undermining has been found. Erosion has been found at the downstream end of the south pier due to the bridges poor alignment with the flow of the stream.

Page 2 of 10 Structure No.

SCOUR EVALUATION – FIELD/OFFICE REVIEW REPORT

1. SCOUR VULNERABILITY RATING (PER FHWA)

a. Scour Susceptible (1) High (2) Medium (3) Low

Low Risk (4) High (5) Medium (6) Low

Scour Critical Yes No COMMENTS:

Foundations Unknown Known Estimated

b. Reasons for Rating

2. RECOMMENDATIONS

a. Countermeasures

Riprap

Scour Monitor

Inspection

Other

b. Level Two Analysis

c. Scour Susceptibility Priority

• Multi span bridge

• Minor scour along south pier

• Exposed footing of south pier

• Moderate undermining along abutment caps

Riprap should be placed to prevent future undermining along abutments. Fill in undermining of abutments. place scour preventative measures along south pier or along south bank to redirect flow

Recommended

Low

Page 3 of 10 Structure No.

3. SITE FIELD REVIEW

a. Evidence of Scour at Structure COMMENTS

1) Abutment Tilting / Moving In Yes No

2) Slopes Washing in / Sloughing Yes No

3) Scour Holes Near Abutments / Bents Yes No

4) Bed Deposits Downstream Yes No

5) Bridge Railing Sagging Yes No

6) Debris Yes No

7) Highwater Mark Yes No

b. Feasibility of Monitoring During High Flow COMMENTS

1) Rod / Pole / Weight from Deck Yes No

2) Fixed Monitoring Device Yes No

c. Feasibility of Adding Riprap or Other Scour Countermeasures Yes No

4. ABUTMENTS

a. Type of Abutment: Spill Through Vertical Wall Wing Walls Seawall

Source of Data: Field Review Design Plans As-Built Drawings

Pile Driving Records Inspection Reports Other

b. Foundation

1) Type of Footings: Spread Footings Pile Footings Pile Bents Drilled Shafts

2) Dimensions (L,W,D)

3) Embedment

4) Scour Exposure

c. Location of Abutment from Bank Set Back At Bank In Channel

1) Left

2) Right

d. Abutment Protection Yes No

1) Riprap: Sand Cement Rubble Commercial Block Concrete

2) Other

3) Condition

Left Good Fair Poor

Right Good Fair Poor

Scour along South pier✔

Page 4 of 10 Structure No.

5. PIER/BENT

a. Type of Pier/Bent: Concrete Wall Pile Bent Column Type

b. Nose Shape: Square Rounded Sharp Nose

c. Dimension (H,W,L):

d. Foundation (Worst Pier/Bent)

Source of Data: Field Review Design Plans As-Built Drawing

Pile Driving Records Inspection Reports Other

1) Type of Footings: Spread Footings Pile Footings Pile Bents Drilled Shafts

2) Dimensions (L,W,D)

3) Embedment

4) Scour Exposure

5) Comments

e. Pier Protection Yes No

1) Countermeasure: Riprap Sand Cement Rubble Commercial Block Grouted

2) Other

3) Condition Good Fair Poor Unknown

6. CHANNEL LATERAL STABILITY

a. Bends Yes No

1) Bridge Location: Upstream of Bend Downstream of Bend In Bend

2) Migration Yes No

3) Countermeasures Yes No Type:

b. Bank Condition: Eroding Stable Vegetated Countermeasures

1) Upstream Left

Right

2) Downstream Left

Right

c. Angle of Attack Flood Flow 0° Normal Flow 0°

d. Point Bar Under Bridge Yes No

e. Island or Bars

1) Upstream Yes No

2) Downstream Yes No

Page 5 of 10 Structure No.

7. CHANNEL VERTICAL STABILITY

a. Exposed Footing Yes No

b. Exposed Piles Yes No

c. Contraction Scour (Encroachment)

1) Overbank Flow: Left Right

2) Relief Bridge: Yes No

3) Abutments:

Left Set Back At Bank In Channel

Right Set Back At Bank In Channel

4) Overtopping Yes No Unknown

d. Long Term: COMMENTS

1) Aggradation

Channel Yes No

Slope Yes No

2) Degradation

Channel Yes No

Slope Yes No

e. Bed Material: Silt-Clay Silt Sand Gravel Cobbles

Description:

D16: mm D50: mm D84: mm

8. GEOMORPHOLOGY COMMENTS

a. Alluvial Fan Yes No

b. Dam or Reservoir Yes No

c. Instream Mining Yes No

d. Headcuts or Nickpoints Yes No

e. Diversions: Yes No

f. Channel Straightening Yes No

g. River Form: Straight Sinuous Meandering Highly Meandering

h. Stream Size: Small (<100 feet) Medium (100 – 500 feet) Large (> 500 feet)

i. Flow Characteristics: Ephemeral Intermittent Perennial but Flashy Perennial

Page 6 of 10 Structure No.

9. OTHER CONSIDERATIONS

a. Sediment Transport (observed):

1) Live Bed Condition Clear Water Condition

2) Armored Bed Yes No

b. Watershed: Agricultural Forested Swamp Urban

c. Tidal Influence: Yes No Possibly

d. Tidal Features Bay Estuary Inlet Barrier Island

1) Normal Range (amplitude) Field Observation Tide Table

2) Observed Surface Velocity

3) Seiching (wind set up)

4) Distance to Coast Along Thalweg

e. Traffic: Ship Recreation Commercial Barge I.C.W.

f. Tributaries: Stream Factor? (Y or N)

Upstream

Downstream

g. Observed Stream Velocity Left Bank Channel Right Bank

Upstream

Downstream

h. Manning’s n: Channel Overbank

10. ADDITIONAL COMMENTS

a. Photographs: Bridge with Stations Upstream Channel Upstream Face

Against Stations Downstream Channel Downstream Face

b. Remarks:

Field Inspectors:

Date of Evaluation: Weather Conditions: Time:

Page 7 of 10 Structure No.

Page 8 of 10 Structure No.

Page 9 of 10 Structure No.

FEDERAL HIGHWAY ADMINISTRATION

LEVEL 1 SCOUR STUDY

INSTRUCTIONS AND INFORMATION SHEET

Level 1 Qualitative Scour Evaluation

Field/Office Review Report

This form provides a standardized format for the Level 1 evaluation of bridge scour as required by the Federal Highway Administration. It represents a simple qualitative evaluation of physical characteristics and structural features which are considered important in the evaluation of bridge scour, in accordance with the guidelines contained in FHWA HEC 18 & 20. It is intended to provide direction in the initial field inspection and data collection, and also serve as a format for office review.

Since the Level 1 scour evaluation provides only a one time evaluation of site conditions, it is important that the inspector or reviewer pay special attention to the potential scour associated with high flow conditions. If there is concern for potential scour during storm events or particular tidal conditions, then Level 2 analysis, and/or countermeasures should be recommended.

The form consists of ten (10) categories which systematically address structures, abutments and piers, lateral and vertical stream stability, geomorphology, and other considerations which can be evaluated on a qualitative basis during field inspection. The appropriate data collected in the field for categories 3 through 10 should then be assimilated during the Level 1 office evaluation/review. Specific conclusions reached following the office review should be summarized in categories 1 and 2, which outline the Scour Vulnerability Rating and appropriate recommendations for further action. For the field inspection to be meaningful, it would be prudent to review the available site specific data as a precursor to the actual field investigation.

The forms are arranged to guide the inspector/reviewer through a standard evaluation process. In this regard, several areas of the form allow alternative choices in each of the categories. These areas should be appropriately marked or circled in the field for further evaluation in the office. The scope of Level 1 qualitative analysis is designed to formulate an informed opinion of scour susceptibility based on available site specific data and good engineering judgment.

Certain areas of the form should adhere to specific guidelines for conformance with the basic intent of the evaluation. Countermeasures identified on the form are representative of recommendations of the inspector or reviewer. If scour monitoring is specified as a countermeasure, this requires installation of a device designed to continuously or periodically measure scour. If inspections are recommended as a countermeasure, the frequency should be specified (i.e. during routine bridge inspections, frequent seasonal inspections, or inspections made following storm events or tidal surges). Similarly, if special conditions or other considerations were noted during the site investigation, then these issues should be addressed under Category 10 as additional comments.

The Scour Vulnerability Rating for the bridge was developed to establish a qualitative rating system to enable the inspector/reviewer to formulate an informed site specific opinion. The rating is divided into six general classifications and two informational items as outlined below:

CATEGORY RATING

Scour Susceptible High Medium Low Low Risk High Medium Low Scour Critical High Medium Low Scour Critical Yes No Foundations Known Unknown

Page 10 of 10 Structure No.

LEVEL 1 SCOUR STUDY

Guidelines for these ratings are provided as follows:

SCOUR SUSCEPTIBLE (HIGH PRIORITY)

• Aggressive stream or tidal waterway (high velocity, deep)

• Foundations are spread footings on erodible soil, shallow piles or embedment unknown

• Tidal flows have high velocity (surface velocity >3fps) and large tidal amplitude (>2 ft)

• Bed material is easily eroded

• Evidence of scour and/or degradation

• Scour is below top of footing

• Large angle of attack (>10 degrees)

• Countermeasures in poor condition or lacking

SCOUR SUSCEPTIBLE (MEDIUM PRIORITY)

• Characteristics fall between High and Low

SCOUR SUSCEPTIBLE (LOW PRIORITY)

• Stream is not aggressive (low velocities) or other factors mitigate the high velocities

• Foundations on piles but of unknown embedment

• Tidal flows have low velocity and tidal amplitude

• Bed material is erodible

• Some evidence of scour or degradation

• Scour is not below top of spread footings

• Stream is stable and foundations are unknown or spread footing in erodible soil

• Countermeasures are in fair to good condition

LOW RISK (HIGH PRIORITY)

• Stream is not aggressive (low velocity) or other factors mitigate the high velocity

• Foundations on piles of known embedment

• If stream is aggressive or tidal range large, then foundations are known and cross section is stable

• Stream is aggrading or stable

• Countermeasures in fair condition

LOW RISK (MEDIUM PRIORITY)

• Characteristics fall between High and Low

LOW RISK (LOW PRIORITY)

• Stream is not aggressive or other factors mitigate high velocity

• Foundation is in bedrock

• Stream aggrading or stable

• Pile foundations are deep

• Cross section stable

• No evidence of scour

• Tidal flows have low velocity and range

• Countermeasures are in good condition

• No possibility of overtopping bridge

• Foundations designed using current technology

• Channel heavily vegetated

SCOUR CRITICAL:

• Aggressive stream or tidal waterway

• Exposed footing in erodible material

• Exposed piles with unknown or insufficient embedment

• Needs countermeasures immediately

• Actively degrading channel

• Evidence of structural damage due to scour

UNKNOWN FOUNDATIONS

• No record of foundation type (i.e. spread footing vs. piles) or condition of foundation or pile embedment is unknown

FEDERAL LANDS BRIDGE OFFICE

LEVEL 1 SCOUR EVALUATION FORM

FACILITY:

STRUCTURE NUMBER:

STRUCTURE NAME:

FEATURE CARRIED:

Date

REVIEW BY:

Date

GLACIER NATIONAL PARK

1430 - 007P

FISH CREEK BRIDGE

2.0 RECOMMENDATIONS

3.0 BASIS OF EVALUATION

4.0 MATERIALS AND DOCUMENTATION

2015 Bridge Inspection Report

Bridge number 1430 - 007P is identified as a scour susceptible (low risk). The bridge is located on Fish Creek. The bridge is rated as scour susceptible because it is a multi span bridge with known foundations and low priority because there is evidence of scour and is not below footings.

A level 2 analysis is recommended. Continue monitoring and inspections to track scour progress. Put in scour countermeasures to halter erosion and scour progress along abutments and banks. Fill in undermining along abutments.

Based on the 2015 bridge inspection, scouring along the the north face of the south pier has been partially filled in, however footings still remain exposed along entire width of bridge. Note that no undermining has been found. Erosion has been found at the downstream end of the south pier due to the bridges poor alignment with

1. SCOUR VULNERABILITY RATING (PER FHWA)

a. Scour Susceptible (1) High (2) Medium (3) Low

Low Risk (4) High (5) Medium (6) Low

Scour Critical Yes No COMMENTS:

Foundations Unknown Known Estimated

b. Reasons for Rating

2. RECOMMENDATIONS

a. Countermeasures

Riprap

Scour Monitor

Inspection

Other

b. Level Two Analysis

c. Scour Susceptibility Priority

• Multi span bridge

• Minor scour along south pier

• Exposed footing of south pier

• Moderate undermining along abutment caps

Riprap should be placed to prevent future undermining along abutments. Fill in undermining of abutments. place scour preventative measures along south pier or along south bank to redirect flow

Recommended

Low

3. SITE FIELD REVIEW

a. Evidence of Scour at Structure COMMENTS

1) Abutment Tilting / Moving In Yes No

2) Slopes Washing in / Sloughing Yes No

3) Scour Holes Near Abutments / Bents Yes No

4) Bed Deposits Downstream Yes No

5) Bridge Railing Sagging Yes No

6) Debris Yes No

7) Highwater Mark Yes No

b. Feasibility of Monitoring During High Flow COMMENTS

1) Rod / Pole / Weight from Deck Yes No

2) Fixed Monitoring Device Yes No

c. Feasibility of Adding Riprap or Other Scour Countermeasures Yes No

4. ABUTMENTS

a. Type of Abutment: Spill Through Vertical Wall Wing Walls Seawall

Source of Data: Field Review Design Plans As-Built Drawings

Pile Driving Records Inspection Reports Other

b. Foundation

1) Type of Footings: Spread Footings Pile Footings Pile Bents Drilled Shafts

2) Dimensions (L,W,D)

3) Embedment

4) Scour Exposure

c. Location of Abutment from Bank Set Back At Bank In Channel

1) Left

2) Right

d. Abutment Protection Yes No

1) Riprap: Sand Cement Rubble Commercial Block Concrete

2) Other

3) Condition

Left Good Fair Poor

Right Good Fair Poor

Scour along South pier✔

5. PIER/BENT

a. Type of Pier/Bent: Concrete Wall Pile Bent Column Type

b. Nose Shape: Square Rounded Sharp Nose

c. Dimension (H,W,L):

d. Foundation (Worst Pier/Bent)

Source of Data: Field Review Design Plans As-Built Drawing

Pile Driving Records Inspection Reports Other

1) Type of Footings: Spread Footings Pile Footings Pile Bents Drilled Shafts

2) Dimensions (L,W,D)

3) Embedment

4) Scour Exposure

5) Comments

e. Pier Protection Yes No

1) Countermeasure: Riprap Sand Cement Rubble Commercial Block Grouted

2) Other

3) Condition Good Fair Poor Unknown

6. CHANNEL LATERAL STABILITY

a. Bends Yes No

1) Bridge Location: Upstream of Bend Downstream of Bend In Bend

2) Migration Yes No

3) Countermeasures Yes No Type:

b. Bank Condition: Eroding Stable Vegetated Countermeasures

1) Upstream Left

Right

2) Downstream Left

Right

c. Angle of Attack Flood Flow 0° Normal Flow 0°

d. Point Bar Under Bridge Yes No

e. Island or Bars

1) Upstream Yes No

2) Downstream Yes No

7. CHANNEL VERTICAL STABILITY

a. Exposed Footing Yes No

b. Exposed Piles Yes No

c. Contraction Scour (Encroachment)

1) Overbank Flow: Left Right

2) Relief Bridge: Yes No

3) Abutments:

Left Set Back At Bank In Channel

Right Set Back At Bank In Channel

4) Overtopping Yes No Unknown

d. Long Term: COMMENTS

1) Aggradation

Channel Yes No

Slope Yes No

2) Degradation

Channel Yes No

Slope Yes No

e. Bed Material: Silt-Clay Silt Sand Gravel Cobbles

Description:

D16: mm D50: mm D84: mm

8. GEOMORPHOLOGY COMMENTS

a. Alluvial Fan Yes No

b. Dam or Reservoir Yes No

c. Instream Mining Yes No

d. Headcuts or Nickpoints Yes No

e. Diversions: Yes No

f. Channel Straightening Yes No

g. River Form: Straight Sinuous Meandering Highly Meandering

9. OTHER CONSIDERATIONS

a. Sediment Transport (observed):

1) Live Bed Condition Clear Water Condition

2) Armored Bed Yes No

b. Watershed: Agricultural Forested Swamp Urban

c. Tidal Influence: Yes No Possibly

d. Tidal Features Bay Estuary Inlet Barrier Island

1) Normal Range (amplitude) Field Observation Tide Table

2) Observed Surface Velocity

3) Seiching (wind set up)

4) Distance to Coast Along Thalweg

e. Traffic: Ship Recreation Commercial Barge I.C.W.

f. Tributaries: Stream Factor? (Y or N)

Upstream

Downstream

g. Observed Stream Velocity Left Bank Channel Right Bank

Upstream

Downstream

h. Manning’s n: Channel Overbank

10. ADDITIONAL COMMENTS

a. Photographs: Bridge with Stations Upstream Channel Upstream Face

Against Stations Downstream Channel Downstream Face

b. Remarks:

LEVEL 1 SCOUR STUDY

INSTRUCTIONS AND INFORMATION SHEET

Level 1 Qualitative Scour Evaluation

Field/Office Review Report

This form provides a standardized format for the Level 1 evaluation of bridge scour as required by the Federal Highway Administration. It represents a simple qualitative evaluation of physical characteristics and structural features which are considered important in the evaluation of bridge scour, in accordance with the guidelines contained in FHWA HEC 18 & 20. It is intended to provide direction in the initial field inspection and data collection, and also serve as a format for office review.

Since the Level 1 scour evaluation provides only a one time evaluation of site conditions, it is important that the inspector or reviewer pay special attention to the potential scour associated with high flow conditions. If there is concern for potential scour during storm events or particular tidal conditions, then Level 2 analysis, and/or countermeasures should be recommended.

The form consists of ten (10) categories which systematically address structures, abutments and piers, lateral and vertical stream stability, geomorphology, and other considerations which can be evaluated on a qualitative basis during field inspection. The appropriate data collected in the field for categories 3 through 10 should then be assimilated during the Level 1 office evaluation/review. Specific conclusions reached following the office review should be summarized in categories 1 and 2, which outline the Scour Vulnerability Rating and appropriate recommendations for further action. For the field inspection to be meaningful, it would be prudent to review the available site specific data as a precursor to the actual field investigation.

The forms are arranged to guide the inspector/reviewer through a standard evaluation process. In this regard, several areas of the form allow alternative choices in each of the categories. These areas should be appropriately marked or circled in the field for further evaluation in the office. The scope of Level 1 qualitative analysis is designed to formulate an informed opinion of scour susceptibility based on available site specific data and good engineering judgment.

Certain areas of the form should adhere to specific guidelines for conformance with the basic intent of the evaluation. Countermeasures identified on the form are representative of recommendations of the inspector or reviewer. If scour monitoring is specified as a countermeasure, this requires installation of a device designed to continuously or periodically measure scour. If inspections are recommended as a countermeasure, the frequency should be specified (i.e. during routine bridge inspections, frequent seasonal inspections, or inspections made following storm events or tidal surges). Similarly, if special conditions or other considerations were noted during the site investigation, then these issues should be addressed under Category 10 as additional comments.

The Scour Vulnerability Rating for the bridge was developed to establish a qualitative rating system to enable the inspector/reviewer to formulate an informed site specific opinion. The rating is divided into six general classifications and two informational items as outlined below:

CATEGORY RATING

Scour Susceptible High Medium Low Low Risk High Medium Low Scour Critical High Medium Low

LEVEL 1 SCOUR STUDY

Guidelines for these ratings are provided as follows:

SCOUR SUSCEPTIBLE (HIGH PRIORITY)

• Aggressive stream or tidal waterway (high velocity, deep)

• Foundations are spread footings on erodible soil, shallow piles or embedment unknown

• Tidal flows have high velocity (surface velocity >3fps) and large tidal amplitude (>2 ft)

• Bed material is easily eroded

• Evidence of scour and/or degradation

• Scour is below top of footing

• Large angle of attack (>10 degrees)

• Countermeasures in poor condition or lacking

SCOUR SUSCEPTIBLE (MEDIUM PRIORITY)

• Characteristics fall between High and Low

SCOUR SUSCEPTIBLE (LOW PRIORITY)

• Stream is not aggressive (low velocities) or other factors mitigate the high velocities

• Foundations on piles but of unknown embedment

• Tidal flows have low velocity and tidal amplitude

• Bed material is erodible

• Some evidence of scour or degradation

• Scour is not below top of spread footings

• Stream is stable and foundations are unknown or spread footing in erodible soil

• Countermeasures are in fair to good condition

LOW RISK (HIGH PRIORITY)

• Stream is not aggressive (low velocity) or other factors mitigate the high velocity

• Foundations on piles of known embedment

• If stream is aggressive or tidal range large, then foundations are known and cross section is stable

• Stream is aggrading or stable

• Countermeasures in fair condition

LOW RISK (MEDIUM PRIORITY)

• Characteristics fall between High and Low

LOW RISK (LOW PRIORITY)

• Stream is not aggressive or other factors mitigate high velocity

• Foundation is in bedrock

• Stream aggrading or stable

• Pile foundations are deep

• Cross section stable

• No evidence of scour

• Tidal flows have low velocity and range

• Countermeasures are in good condition

• No possibility of overtopping bridge

• Foundations designed using current technology

• Channel heavily vegetated

SCOUR CRITICAL:

• Aggressive stream or tidal waterway

• Exposed footing in erodible material

• Exposed piles with unknown or insufficient embedment

• Needs countermeasures immediately

• Actively degrading channel

• Evidence of structural damage due to scour

• No record of foundation type (i.e. spread footing vs. piles) or condition of foundation or pile embedment is unknown

FEDERAL LANDS BRIDGE OFFICE

LEVEL 1 SCOUR EVALUATION FORM

FACILITY:

STRUCTURE NUMBER:

STRUCTURE NAME:

FEATURE CARRIED:

Date

REVIEW BY:

Date

GLACIER NATIONAL PARK

1430 - 007P

FISH CREEK BRIDGE

2.0 RECOMMENDATIONS

3.0 BASIS OF EVALUATION

4.0 MATERIALS AND DOCUMENTATION

2015 Bridge Inspection Report

Bridge number 1430 - 007P is identified as a scour susceptible (low risk). The bridge is located on Fish Creek. The bridge is rated as scour susceptible because it is a multi span bridge with known foundations and low priority because there is evidence of scour and is not below footings.

A level 2 analysis is recommended. Continue monitoring and inspections to track scour progress. Put in scour countermeasures to halter erosion and scour progress along abutments and banks. Fill in undermining along abutments.

Based on the 2015 bridge inspection, scouring along the the north face of the south pier has been partially filled in, however footings still remain exposed along entire width of bridge. Note that no undermining has been found. Erosion has been found at the downstream end of the south pier due to the bridges poor alignment with

1. SCOUR VULNERABILITY RATING (PER FHWA)

a. Scour Susceptible (1) High (2) Medium (3) Low

Low Risk (4) High (5) Medium (6) Low

Scour Critical Yes No COMMENTS:

Foundations Unknown Known Estimated

b. Reasons for Rating

2. RECOMMENDATIONS

a. Countermeasures

Riprap

Scour Monitor

Inspection

Other

b. Level Two Analysis

c. Scour Susceptibility Priority

• Multi span bridge

• Minor scour along south pier

• Exposed footing of south pier

• Moderate undermining along abutment caps

Riprap should be placed to prevent future undermining along abutments. Fill in undermining of abutments. place scour preventative measures along south pier or along south bank to redirect flow

Recommended

Low

3. SITE FIELD REVIEW

a. Evidence of Scour at Structure COMMENTS

1) Abutment Tilting / Moving In Yes No

2) Slopes Washing in / Sloughing Yes No

3) Scour Holes Near Abutments / Bents Yes No

4) Bed Deposits Downstream Yes No

5) Bridge Railing Sagging Yes No

6) Debris Yes No

7) Highwater Mark Yes No

b. Feasibility of Monitoring During High Flow COMMENTS

1) Rod / Pole / Weight from Deck Yes No

2) Fixed Monitoring Device Yes No

c. Feasibility of Adding Riprap or Other Scour Countermeasures Yes No

4. ABUTMENTS

a. Type of Abutment: Spill Through Vertical Wall Wing Walls Seawall

Source of Data: Field Review Design Plans As-Built Drawings

Pile Driving Records Inspection Reports Other

b. Foundation

1) Type of Footings: Spread Footings Pile Footings Pile Bents Drilled Shafts

2) Dimensions (L,W,D)

3) Embedment

4) Scour Exposure

c. Location of Abutment from Bank Set Back At Bank In Channel

1) Left

2) Right

d. Abutment Protection Yes No

1) Riprap: Sand Cement Rubble Commercial Block Concrete

2) Other

3) Condition

Left Good Fair Poor

Right Good Fair Poor

Scour along South pier✔

5. PIER/BENT

a. Type of Pier/Bent: Concrete Wall Pile Bent Column Type

b. Nose Shape: Square Rounded Sharp Nose

c. Dimension (H,W,L):

d. Foundation (Worst Pier/Bent)

Source of Data: Field Review Design Plans As-Built Drawing

Pile Driving Records Inspection Reports Other

1) Type of Footings: Spread Footings Pile Footings Pile Bents Drilled Shafts

2) Dimensions (L,W,D)

3) Embedment

4) Scour Exposure

5) Comments

e. Pier Protection Yes No

1) Countermeasure: Riprap Sand Cement Rubble Commercial Block Grouted

2) Other

3) Condition Good Fair Poor Unknown

6. CHANNEL LATERAL STABILITY

a. Bends Yes No

1) Bridge Location: Upstream of Bend Downstream of Bend In Bend

2) Migration Yes No

3) Countermeasures Yes No Type:

b. Bank Condition: Eroding Stable Vegetated Countermeasures

1) Upstream Left

Right

2) Downstream Left

Right

c. Angle of Attack Flood Flow 0° Normal Flow 0°

d. Point Bar Under Bridge Yes No

e. Island or Bars

1) Upstream Yes No

2) Downstream Yes No

7. CHANNEL VERTICAL STABILITY

a. Exposed Footing Yes No

b. Exposed Piles Yes No

c. Contraction Scour (Encroachment)

1) Overbank Flow: Left Right

2) Relief Bridge: Yes No

3) Abutments:

Left Set Back At Bank In Channel

Right Set Back At Bank In Channel

4) Overtopping Yes No Unknown

d. Long Term: COMMENTS

1) Aggradation

Channel Yes No

Slope Yes No

2) Degradation

Channel Yes No

Slope Yes No

e. Bed Material: Silt-Clay Silt Sand Gravel Cobbles

Description:

D16: mm D50: mm D84: mm

8. GEOMORPHOLOGY COMMENTS

a. Alluvial Fan Yes No

b. Dam or Reservoir Yes No

c. Instream Mining Yes No

d. Headcuts or Nickpoints Yes No

e. Diversions: Yes No

f. Channel Straightening Yes No

g. River Form: Straight Sinuous Meandering Highly Meandering

9. OTHER CONSIDERATIONS

a. Sediment Transport (observed):

1) Live Bed Condition Clear Water Condition

2) Armored Bed Yes No

b. Watershed: Agricultural Forested Swamp Urban

c. Tidal Influence: Yes No Possibly

d. Tidal Features Bay Estuary Inlet Barrier Island

1) Normal Range (amplitude) Field Observation Tide Table

2) Observed Surface Velocity

3) Seiching (wind set up)

4) Distance to Coast Along Thalweg

e. Traffic: Ship Recreation Commercial Barge I.C.W.

f. Tributaries: Stream Factor? (Y or N)

Upstream

Downstream

g. Observed Stream Velocity Left Bank Channel Right Bank

Upstream

Downstream

h. Manning’s n: Channel Overbank

10. ADDITIONAL COMMENTS

a. Photographs: Bridge with Stations Upstream Channel Upstream Face

Against Stations Downstream Channel Downstream Face

b. Remarks:

LEVEL 1 SCOUR STUDY

INSTRUCTIONS AND INFORMATION SHEET

Level 1 Qualitative Scour Evaluation

Field/Office Review Report

This form provides a standardized format for the Level 1 evaluation of bridge scour as required by the Federal Highway Administration. It represents a simple qualitative evaluation of physical characteristics and structural features which are considered important in the evaluation of bridge scour, in accordance with the guidelines contained in FHWA HEC 18 & 20. It is intended to provide direction in the initial field inspection and data collection, and also serve as a format for office review.

Since the Level 1 scour evaluation provides only a one time evaluation of site conditions, it is important that the inspector or reviewer pay special attention to the potential scour associated with high flow conditions. If there is concern for potential scour during storm events or particular tidal conditions, then Level 2 analysis, and/or countermeasures should be recommended.

The form consists of ten (10) categories which systematically address structures, abutments and piers, lateral and vertical stream stability, geomorphology, and other considerations which can be evaluated on a qualitative basis during field inspection. The appropriate data collected in the field for categories 3 through 10 should then be assimilated during the Level 1 office evaluation/review. Specific conclusions reached following the office review should be summarized in categories 1 and 2, which outline the Scour Vulnerability Rating and appropriate recommendations for further action. For the field inspection to be meaningful, it would be prudent to review the available site specific data as a precursor to the actual field investigation.

The forms are arranged to guide the inspector/reviewer through a standard evaluation process. In this regard, several areas of the form allow alternative choices in each of the categories. These areas should be appropriately marked or circled in the field for further evaluation in the office. The scope of Level 1 qualitative analysis is designed to formulate an informed opinion of scour susceptibility based on available site specific data and good engineering judgment.

Certain areas of the form should adhere to specific guidelines for conformance with the basic intent of the evaluation. Countermeasures identified on the form are representative of recommendations of the inspector or reviewer. If scour monitoring is specified as a countermeasure, this requires installation of a device designed to continuously or periodically measure scour. If inspections are recommended as a countermeasure, the frequency should be specified (i.e. during routine bridge inspections, frequent seasonal inspections, or inspections made following storm events or tidal surges). Similarly, if special conditions or other considerations were noted during the site investigation, then these issues should be addressed under Category 10 as additional comments.

The Scour Vulnerability Rating for the bridge was developed to establish a qualitative rating system to enable the inspector/reviewer to formulate an informed site specific opinion. The rating is divided into six general classifications and two informational items as outlined below:

CATEGORY RATING

Scour Susceptible High Medium Low Low Risk High Medium Low Scour Critical High Medium Low

LEVEL 1 SCOUR STUDY

Guidelines for these ratings are provided as follows:

SCOUR SUSCEPTIBLE (HIGH PRIORITY)

• Aggressive stream or tidal waterway (high velocity, deep)

• Foundations are spread footings on erodible soil, shallow piles or embedment unknown

• Tidal flows have high velocity (surface velocity >3fps) and large tidal amplitude (>2 ft)

• Bed material is easily eroded

• Evidence of scour and/or degradation

• Scour is below top of footing

• Large angle of attack (>10 degrees)

• Countermeasures in poor condition or lacking

SCOUR SUSCEPTIBLE (MEDIUM PRIORITY)

• Characteristics fall between High and Low

SCOUR SUSCEPTIBLE (LOW PRIORITY)

• Stream is not aggressive (low velocities) or other factors mitigate the high velocities

• Foundations on piles but of unknown embedment

• Tidal flows have low velocity and tidal amplitude

• Bed material is erodible

• Some evidence of scour or degradation

• Scour is not below top of spread footings

• Stream is stable and foundations are unknown or spread footing in erodible soil

• Countermeasures are in fair to good condition

LOW RISK (HIGH PRIORITY)

• Stream is not aggressive (low velocity) or other factors mitigate the high velocity

• Foundations on piles of known embedment

• If stream is aggressive or tidal range large, then foundations are known and cross section is stable

• Stream is aggrading or stable

• Countermeasures in fair condition

LOW RISK (MEDIUM PRIORITY)

• Characteristics fall between High and Low

LOW RISK (LOW PRIORITY)

• Stream is not aggressive or other factors mitigate high velocity

• Foundation is in bedrock

• Stream aggrading or stable

• Pile foundations are deep

• Cross section stable

• No evidence of scour

• Tidal flows have low velocity and range

• Countermeasures are in good condition

• No possibility of overtopping bridge

• Foundations designed using current technology

• Channel heavily vegetated

SCOUR CRITICAL:

• Aggressive stream or tidal waterway

• Exposed footing in erodible material

• Exposed piles with unknown or insufficient embedment

• Needs countermeasures immediately

• Actively degrading channel

• Evidence of structural damage due to scour

• No record of foundation type (i.e. spread footing vs. piles) or condition of foundation or pile embedment is unknown

FEDERAL LANDS BRIDGE OFFICE

LEVEL 1 SCOUR EVALUATION FORM

FACILITY:

STRUCTURE NUMBER:

STRUCTURE NAME:

FEATURE CARRIED:

Date

REVIEW BY:

Date

GLACIER NATIONAL PARK

1430 - 007P

FISH CREEK BRIDGE

2.0 RECOMMENDATIONS

3.0 BASIS OF EVALUATION

4.0 MATERIALS AND DOCUMENTATION

2015 Bridge Inspection Report

Bridge number 1430 - 007P is identified as a scour susceptible (low risk). The bridge is located on Fish Creek. The bridge is rated as scour susceptible because it is a multi span bridge with known foundations and low priority because there is evidence of scour and is not below footings.

A level 2 analysis is recommended. Continue monitoring and inspections to track scour progress. Put in scour countermeasures to halter erosion and scour progress along abutments and banks. Fill in undermining along abutments.

Based on the 2015 bridge inspection, scouring along the the north face of the south pier has been partially filled in, however footings still remain exposed along entire width of bridge. Note that no undermining has been found. Erosion has been found at the downstream end of the south pier due to the bridges poor alignment with

1. SCOUR VULNERABILITY RATING (PER FHWA)

a. Scour Susceptible (1) High (2) Medium (3) Low

Low Risk (4) High (5) Medium (6) Low

Scour Critical Yes No COMMENTS:

Foundations Unknown Known Estimated

b. Reasons for Rating

2. RECOMMENDATIONS

a. Countermeasures

Riprap

Scour Monitor

Inspection

Other

b. Level Two Analysis

c. Scour Susceptibility Priority

• Multi span bridge

• Minor scour along south pier

• Exposed footing of south pier

• Moderate undermining along abutment caps

Riprap should be placed to prevent future undermining along abutments. Fill in undermining of abutments. place scour preventative measures along south pier or along south bank to redirect flow

Recommended

Low

3. SITE FIELD REVIEW

a. Evidence of Scour at Structure COMMENTS

1) Abutment Tilting / Moving In Yes No

2) Slopes Washing in / Sloughing Yes No

3) Scour Holes Near Abutments / Bents Yes No

4) Bed Deposits Downstream Yes No

5) Bridge Railing Sagging Yes No

6) Debris Yes No

7) Highwater Mark Yes No

b. Feasibility of Monitoring During High Flow COMMENTS

1) Rod / Pole / Weight from Deck Yes No

2) Fixed Monitoring Device Yes No

c. Feasibility of Adding Riprap or Other Scour Countermeasures Yes No

4. ABUTMENTS

a. Type of Abutment: Spill Through Vertical Wall Wing Walls Seawall

Source of Data: Field Review Design Plans As-Built Drawings

Pile Driving Records Inspection Reports Other

b. Foundation

1) Type of Footings: Spread Footings Pile Footings Pile Bents Drilled Shafts

2) Dimensions (L,W,D)

3) Embedment

4) Scour Exposure

c. Location of Abutment from Bank Set Back At Bank In Channel

1) Left

2) Right

d. Abutment Protection Yes No

1) Riprap: Sand Cement Rubble Commercial Block Concrete

2) Other

3) Condition

Left Good Fair Poor

Right Good Fair Poor

Scour along South pier✔

5. PIER/BENT

a. Type of Pier/Bent: Concrete Wall Pile Bent Column Type

b. Nose Shape: Square Rounded Sharp Nose

c. Dimension (H,W,L):

d. Foundation (Worst Pier/Bent)

Source of Data: Field Review Design Plans As-Built Drawing

Pile Driving Records Inspection Reports Other

1) Type of Footings: Spread Footings Pile Footings Pile Bents Drilled Shafts

2) Dimensions (L,W,D)

3) Embedment

4) Scour Exposure

5) Comments

e. Pier Protection Yes No

1) Countermeasure: Riprap Sand Cement Rubble Commercial Block Grouted

2) Other

3) Condition Good Fair Poor Unknown

6. CHANNEL LATERAL STABILITY

a. Bends Yes No

1) Bridge Location: Upstream of Bend Downstream of Bend In Bend

2) Migration Yes No

3) Countermeasures Yes No Type:

b. Bank Condition: Eroding Stable Vegetated Countermeasures

1) Upstream Left

Right

2) Downstream Left

Right

c. Angle of Attack Flood Flow 0° Normal Flow 0°

d. Point Bar Under Bridge Yes No

e. Island or Bars

1) Upstream Yes No

2) Downstream Yes No

7. CHANNEL VERTICAL STABILITY

a. Exposed Footing Yes No

b. Exposed Piles Yes No

c. Contraction Scour (Encroachment)

1) Overbank Flow: Left Right

2) Relief Bridge: Yes No

3) Abutments:

Left Set Back At Bank In Channel

Right Set Back At Bank In Channel

4) Overtopping Yes No Unknown

d. Long Term: COMMENTS

1) Aggradation

Channel Yes No

Slope Yes No

2) Degradation

Channel Yes No

Slope Yes No

e. Bed Material: Silt-Clay Silt Sand Gravel Cobbles

Description:

D16: mm D50: mm D84: mm

8. GEOMORPHOLOGY COMMENTS

a. Alluvial Fan Yes No

b. Dam or Reservoir Yes No

c. Instream Mining Yes No

d. Headcuts or Nickpoints Yes No

e. Diversions: Yes No

f. Channel Straightening Yes No

g. River Form: Straight Sinuous Meandering Highly Meandering

9. OTHER CONSIDERATIONS

a. Sediment Transport (observed):

1) Live Bed Condition Clear Water Condition

2) Armored Bed Yes No

b. Watershed: Agricultural Forested Swamp Urban

c. Tidal Influence: Yes No Possibly

d. Tidal Features Bay Estuary Inlet Barrier Island

1) Normal Range (amplitude) Field Observation Tide Table

2) Observed Surface Velocity

3) Seiching (wind set up)

4) Distance to Coast Along Thalweg

e. Traffic: Ship Recreation Commercial Barge I.C.W.

f. Tributaries: Stream Factor? (Y or N)

Upstream

Downstream

g. Observed Stream Velocity Left Bank Channel Right Bank

Upstream

Downstream

h. Manning’s n: Channel Overbank

10. ADDITIONAL COMMENTS

a. Photographs: Bridge with Stations Upstream Channel Upstream Face

Against Stations Downstream Channel Downstream Face

b. Remarks:

LEVEL 1 SCOUR STUDY

INSTRUCTIONS AND INFORMATION SHEET

Level 1 Qualitative Scour Evaluation

Field/Office Review Report

This form provides a standardized format for the Level 1 evaluation of bridge scour as required by the Federal Highway Administration. It represents a simple qualitative evaluation of physical characteristics and structural features which are considered important in the evaluation of bridge scour, in accordance with the guidelines contained in FHWA HEC 18 & 20. It is intended to provide direction in the initial field inspection and data collection, and also serve as a format for office review.

Since the Level 1 scour evaluation provides only a one time evaluation of site conditions, it is important that the inspector or reviewer pay special attention to the potential scour associated with high flow conditions. If there is concern for potential scour during storm events or particular tidal conditions, then Level 2 analysis, and/or countermeasures should be recommended.

The form consists of ten (10) categories which systematically address structures, abutments and piers, lateral and vertical stream stability, geomorphology, and other considerations which can be evaluated on a qualitative basis during field inspection. The appropriate data collected in the field for categories 3 through 10 should then be assimilated during the Level 1 office evaluation/review. Specific conclusions reached following the office review should be summarized in categories 1 and 2, which outline the Scour Vulnerability Rating and appropriate recommendations for further action. For the field inspection to be meaningful, it would be prudent to review the available site specific data as a precursor to the actual field investigation.

The forms are arranged to guide the inspector/reviewer through a standard evaluation process. In this regard, several areas of the form allow alternative choices in each of the categories. These areas should be appropriately marked or circled in the field for further evaluation in the office. The scope of Level 1 qualitative analysis is designed to formulate an informed opinion of scour susceptibility based on available site specific data and good engineering judgment.

Certain areas of the form should adhere to specific guidelines for conformance with the basic intent of the evaluation. Countermeasures identified on the form are representative of recommendations of the inspector or reviewer. If scour monitoring is specified as a countermeasure, this requires installation of a device designed to continuously or periodically measure scour. If inspections are recommended as a countermeasure, the frequency should be specified (i.e. during routine bridge inspections, frequent seasonal inspections, or inspections made following storm events or tidal surges). Similarly, if special conditions or other considerations were noted during the site investigation, then these issues should be addressed under Category 10 as additional comments.

The Scour Vulnerability Rating for the bridge was developed to establish a qualitative rating system to enable the inspector/reviewer to formulate an informed site specific opinion. The rating is divided into six general classifications and two informational items as outlined below:

CATEGORY RATING

Scour Susceptible High Medium Low Low Risk High Medium Low Scour Critical High Medium Low

LEVEL 1 SCOUR STUDY

Guidelines for these ratings are provided as follows:

SCOUR SUSCEPTIBLE (HIGH PRIORITY)

• Aggressive stream or tidal waterway (high velocity, deep)

• Foundations are spread footings on erodible soil, shallow piles or embedment unknown

• Tidal flows have high velocity (surface velocity >3fps) and large tidal amplitude (>2 ft)

• Bed material is easily eroded

• Evidence of scour and/or degradation

• Scour is below top of footing

• Large angle of attack (>10 degrees)

• Countermeasures in poor condition or lacking

SCOUR SUSCEPTIBLE (MEDIUM PRIORITY)

• Characteristics fall between High and Low

SCOUR SUSCEPTIBLE (LOW PRIORITY)

• Stream is not aggressive (low velocities) or other factors mitigate the high velocities

• Foundations on piles but of unknown embedment

• Tidal flows have low velocity and tidal amplitude

• Bed material is erodible

• Some evidence of scour or degradation

• Scour is not below top of spread footings

• Stream is stable and foundations are unknown or spread footing in erodible soil

• Countermeasures are in fair to good condition

LOW RISK (HIGH PRIORITY)

• Stream is not aggressive (low velocity) or other factors mitigate the high velocity

• Foundations on piles of known embedment

• If stream is aggressive or tidal range large, then foundations are known and cross section is stable

• Stream is aggrading or stable

• Countermeasures in fair condition

LOW RISK (MEDIUM PRIORITY)

• Characteristics fall between High and Low

LOW RISK (LOW PRIORITY)

• Stream is not aggressive or other factors mitigate high velocity

• Foundation is in bedrock

• Stream aggrading or stable

• Pile foundations are deep

• Cross section stable

• No evidence of scour

• Tidal flows have low velocity and range

• Countermeasures are in good condition

• No possibility of overtopping bridge

• Foundations designed using current technology

• Channel heavily vegetated

SCOUR CRITICAL:

• Aggressive stream or tidal waterway

• Exposed footing in erodible material

• Exposed piles with unknown or insufficient embedment

• Needs countermeasures immediately

• Actively degrading channel

• Evidence of structural damage due to scour

• No record of foundation type (i.e. spread footing vs. piles) or condition of foundation or pile embedment is unknown

FEDERAL LANDS BRIDGE OFFICE

LEVEL 1 SCOUR EVALUATION FORM

FACILITY:

STRUCTURE NUMBER:

STRUCTURE NAME:

FEATURE CARRIED:

Date

REVIEW BY:

Date

GLACIER NATIONAL PARK

1430 - 007P

FISH CREEK BRIDGE

2.0 RECOMMENDATIONS

3.0 BASIS OF EVALUATION

4.0 MATERIALS AND DOCUMENTATION

2015 Bridge Inspection Report

Bridge number 1430 - 007P is identified as a scour susceptible (low risk). The bridge is located on Fish Creek. The bridge is rated as scour susceptible because it is a multi span bridge with known foundations and low priority because there is evidence of scour and is not below footings.

A level 2 analysis is recommended. Continue monitoring and inspections to track scour progress. Put in scour countermeasures to halter erosion and scour progress along abutments and banks. Fill in undermining along abutments.

Based on the 2015 bridge inspection, scouring along the the north face of the south pier has been partially filled in, however footings still remain exposed along entire width of bridge. Note that no undermining has been found. Erosion has been found at the downstream end of the south pier due to the bridges poor alignment with

1. SCOUR VULNERABILITY RATING (PER FHWA)

a. Scour Susceptible (1) High (2) Medium (3) Low

Low Risk (4) High (5) Medium (6) Low

Scour Critical Yes No COMMENTS:

Foundations Unknown Known Estimated

b. Reasons for Rating

2. RECOMMENDATIONS

a. Countermeasures

Riprap

Scour Monitor

Inspection

Other

b. Level Two Analysis

c. Scour Susceptibility Priority

• Multi span bridge

• Minor scour along south pier

• Exposed footing of south pier

• Moderate undermining along abutment caps

Riprap should be placed to prevent future undermining along abutments. Fill in undermining of abutments. place scour preventative measures along south pier or along south bank to redirect flow

Recommended

Low

3. SITE FIELD REVIEW

a. Evidence of Scour at Structure COMMENTS

1) Abutment Tilting / Moving In Yes No

2) Slopes Washing in / Sloughing Yes No

3) Scour Holes Near Abutments / Bents Yes No

4) Bed Deposits Downstream Yes No

5) Bridge Railing Sagging Yes No

6) Debris Yes No

7) Highwater Mark Yes No

b. Feasibility of Monitoring During High Flow COMMENTS

1) Rod / Pole / Weight from Deck Yes No

2) Fixed Monitoring Device Yes No

c. Feasibility of Adding Riprap or Other Scour Countermeasures Yes No

4. ABUTMENTS

a. Type of Abutment: Spill Through Vertical Wall Wing Walls Seawall

Source of Data: Field Review Design Plans As-Built Drawings

Pile Driving Records Inspection Reports Other

b. Foundation

1) Type of Footings: Spread Footings Pile Footings Pile Bents Drilled Shafts

2) Dimensions (L,W,D)

3) Embedment

4) Scour Exposure

c. Location of Abutment from Bank Set Back At Bank In Channel

1) Left

2) Right

d. Abutment Protection Yes No

1) Riprap: Sand Cement Rubble Commercial Block Concrete

2) Other

3) Condition

Left Good Fair Poor

Right Good Fair Poor

Scour along South pier✔

5. PIER/BENT

a. Type of Pier/Bent: Concrete Wall Pile Bent Column Type

b. Nose Shape: Square Rounded Sharp Nose

c. Dimension (H,W,L):

d. Foundation (Worst Pier/Bent)

Source of Data: Field Review Design Plans As-Built Drawing

Pile Driving Records Inspection Reports Other

1) Type of Footings: Spread Footings Pile Footings Pile Bents Drilled Shafts

2) Dimensions (L,W,D)

3) Embedment

4) Scour Exposure

5) Comments

e. Pier Protection Yes No

1) Countermeasure: Riprap Sand Cement Rubble Commercial Block Grouted

2) Other

3) Condition Good Fair Poor Unknown

6. CHANNEL LATERAL STABILITY

a. Bends Yes No

1) Bridge Location: Upstream of Bend Downstream of Bend In Bend

2) Migration Yes No

3) Countermeasures Yes No Type:

b. Bank Condition: Eroding Stable Vegetated Countermeasures

1) Upstream Left

Right

2) Downstream Left

Right

c. Angle of Attack Flood Flow 0° Normal Flow 0°

d. Point Bar Under Bridge Yes No

e. Island or Bars

1) Upstream Yes No

2) Downstream Yes No

7. CHANNEL VERTICAL STABILITY

a. Exposed Footing Yes No

b. Exposed Piles Yes No

c. Contraction Scour (Encroachment)

1) Overbank Flow: Left Right

2) Relief Bridge: Yes No

3) Abutments:

Left Set Back At Bank In Channel

Right Set Back At Bank In Channel

4) Overtopping Yes No Unknown

d. Long Term: COMMENTS

1) Aggradation

Channel Yes No

Slope Yes No

2) Degradation

Channel Yes No

Slope Yes No

e. Bed Material: Silt-Clay Silt Sand Gravel Cobbles

Description:

D16: mm D50: mm D84: mm

8. GEOMORPHOLOGY COMMENTS

a. Alluvial Fan Yes No

b. Dam or Reservoir Yes No

c. Instream Mining Yes No

d. Headcuts or Nickpoints Yes No

e. Diversions: Yes No

f. Channel Straightening Yes No

g. River Form: Straight Sinuous Meandering Highly Meandering

9. OTHER CONSIDERATIONS

a. Sediment Transport (observed):

1) Live Bed Condition Clear Water Condition

2) Armored Bed Yes No

b. Watershed: Agricultural Forested Swamp Urban

c. Tidal Influence: Yes No Possibly

d. Tidal Features Bay Estuary Inlet Barrier Island

1) Normal Range (amplitude) Field Observation Tide Table

2) Observed Surface Velocity

3) Seiching (wind set up)

4) Distance to Coast Along Thalweg

e. Traffic: Ship Recreation Commercial Barge I.C.W.

f. Tributaries: Stream Factor? (Y or N)

Upstream

Downstream

g. Observed Stream Velocity Left Bank Channel Right Bank

Upstream

Downstream

h. Manning’s n: Channel Overbank

10. ADDITIONAL COMMENTS

a. Photographs: Bridge with Stations Upstream Channel Upstream Face

Against Stations Downstream Channel Downstream Face

b. Remarks:

LEVEL 1 SCOUR STUDY

INSTRUCTIONS AND INFORMATION SHEET

Level 1 Qualitative Scour Evaluation

Field/Office Review Report

This form provides a standardized format for the Level 1 evaluation of bridge scour as required by the Federal Highway Administration. It represents a simple qualitative evaluation of physical characteristics and structural features which are considered important in the evaluation of bridge scour, in accordance with the guidelines contained in FHWA HEC 18 & 20. It is intended to provide direction in the initial field inspection and data collection, and also serve as a format for office review.

Since the Level 1 scour evaluation provides only a one time…