Rip-Rap Revetment: Flood Adaptation Measure


Seawall of riprap on Panama Bay - Panama City, Panama
© Crandall / Alamy Stock Photo

PHYSICAL INFRASTRUCTURE
SHORELINE LOCATION: Upland




DESIGN LIFE
ADAPTABILITY
IMPACT ON THE WATERFRONT
CONSTRUCTION COST
50+ Years
High
Major Intervention
TBD


COASTAL FLOOD HAZARDS MITIGATED:
Sea Level Rise
Storm Surge
Groundwater
Waves
Erosion


MEASURES COMPATIBILITY:
ECOSYSTEM SERVICES: Measure may affect these shoreline values
Flood
Seismic
Vegetated Terraces, Seawalls, Floodwalls, Tide Pools, Ecological Concrete Units
Nearshore Seawall, Soil Buttress, Liquefaction Mitigation
Aquatic Habitat
Terrestrial Habitat
Water Quality
Carbon Storage


DESCRIPTION:
Rip-rap revetments are the most commonly used structures for shore protection in San Francisco Bay. Typically, they consist of an armor layer of stone with additional stone underlayers and/or a geotechnical fabric to prevent the loss of soil material due to wave action. Revetments are typically built at a 2H:1V or shallower slopes and achieve stability through the weight of the armor stone as well as some interlocking between stones. Rip-rap revetments are generally less expensive than bulkheads or seawalls but with a larger footprint. Revetments also have an advantage that they are flexible and can sustain some damage or adjust to settlement and still retain their function.


CONSIDERATIONS:
ADVANTAGES:
DISADVANTAGES:
  • Design must account for geotechnical stability and foundation settlement
  • Effectively mitigates erosion
  • Economical and low maintenance
  • Can sustain damage or adjust to settlement without catastrophic failure
  • Can provide habitat for rock-dwelling mollusks and aquatic vegetation
  • Can lead to loss of existing intertidal habitat due to the footprint of the structure
  • On sandy shores, can accelerate erosion of adjacent unprotected shores
  • Slope of revetment can limit maritime access to the shoreline
  • Rip-rap can provide unwanted habitat to rodents or other pests and be a hazard to people climbing on the revetment
  • Requires permitting of additional bay fill


CONSTRUCTION IMPACTS TO THE PUBLIC:
SEA LEVEL RISE ADAPTATION OPPORTUNITIES:
CASE STUDIES:
  • Installation can be completed from the water or landside
  • Access to the shoreline will be restricted during construction.
  • Flood walls can be added to the crest to reduce flooding due to rising sea levels without increasing the overall footprint of the revetment.
  • Treasure Island, SF; Brooklyn Bridges Park, NYC


DESIGN OPPORTUNITIES:
Ecological Enhancements
Urban Design
Form
  • Vegetation benches and aquatic habitats can be integrated into the design of revetments
  • Pathways can be set on top of revetment structures
  • Revetment structures can have different slopes and create unique spaces along the waterfront


DESIGN CONSIDERATIONS:

  • Armor layer must be sized to remain stable under extreme wave conditions as well as propeller wash from ship operations at the site.
  • Underlayer size and grading should meet specific filter and stability criteria to prevent loss of soil material and underlayer material.
  • Design must account for geotechnical stability and foundation settlement. • Additional stone is normally placed at the toe to support the armor layer and to prevent scour of the toe.
  • Design should consider potential for erosion behind the crest due to wave overtopping.

SITE-SPECIFIC CONSIDERATIONS:

  • Water levels, waves, currents, propeller wash from ship activity should be well defined.
  • Geotechnical investigations should be performed to determine potential for settlement and stability.

ARCHITECTURAL CONSIDERATIONS:

  • Randomly placed rip-rap on the armor layer may not be an aesthetically attractive at certain locations. Fitted stone could be considered as an alternative.

URBAN DESIGN CONSIDERATIONS:

  • Rip-rap revetments can present a hazard if people walk on or climb down the revetment. Armor stone should be angular in shape or other measures should be employed to discourage people from climbing down to the water over the revetment.
  • Rip-rap of revetments accessible to the public should be sized large enough to prevent removal of stones by people.

INSTALLATION AND CONSTRUCTABILITY CONSIDERATIONS:

  • Installation can be performed from landside or waterside from a barge.
  • Requires grading of existing soil prior to placing revetment material. Potential for suspension of sediment.

OPERATIONS AND MAINTENANCE CONSIDERATIONS:

  • Once constructed, little to no maintenance should be required.
  • Revetment should be inspected periodically following significant storm events and damage areas that could affect the stability of the structure repaired.


Download the Rip-Rap Revetment Factsheet.

Learn about other types of measures from our Measures Explorer page.



Seawall of riprap on Panama Bay - Panama City, Panama
© Crandall / Alamy Stock Photo

PHYSICAL INFRASTRUCTURE
SHORELINE LOCATION: Upland




DESIGN LIFE
ADAPTABILITY
IMPACT ON THE WATERFRONT
CONSTRUCTION COST
50+ Years
High
Major Intervention
TBD


COASTAL FLOOD HAZARDS MITIGATED:
Sea Level Rise
Storm Surge
Groundwater
Waves
Erosion


MEASURES COMPATIBILITY:
ECOSYSTEM SERVICES: Measure may affect these shoreline values
Flood
Seismic
Vegetated Terraces, Seawalls, Floodwalls, Tide Pools, Ecological Concrete Units
Nearshore Seawall, Soil Buttress, Liquefaction Mitigation
Aquatic Habitat
Terrestrial Habitat
Water Quality
Carbon Storage


DESCRIPTION:
Rip-rap revetments are the most commonly used structures for shore protection in San Francisco Bay. Typically, they consist of an armor layer of stone with additional stone underlayers and/or a geotechnical fabric to prevent the loss of soil material due to wave action. Revetments are typically built at a 2H:1V or shallower slopes and achieve stability through the weight of the armor stone as well as some interlocking between stones. Rip-rap revetments are generally less expensive than bulkheads or seawalls but with a larger footprint. Revetments also have an advantage that they are flexible and can sustain some damage or adjust to settlement and still retain their function.


CONSIDERATIONS:
ADVANTAGES:
DISADVANTAGES:
  • Design must account for geotechnical stability and foundation settlement
  • Effectively mitigates erosion
  • Economical and low maintenance
  • Can sustain damage or adjust to settlement without catastrophic failure
  • Can provide habitat for rock-dwelling mollusks and aquatic vegetation
  • Can lead to loss of existing intertidal habitat due to the footprint of the structure
  • On sandy shores, can accelerate erosion of adjacent unprotected shores
  • Slope of revetment can limit maritime access to the shoreline
  • Rip-rap can provide unwanted habitat to rodents or other pests and be a hazard to people climbing on the revetment
  • Requires permitting of additional bay fill


CONSTRUCTION IMPACTS TO THE PUBLIC:
SEA LEVEL RISE ADAPTATION OPPORTUNITIES:
CASE STUDIES:
  • Installation can be completed from the water or landside
  • Access to the shoreline will be restricted during construction.
  • Flood walls can be added to the crest to reduce flooding due to rising sea levels without increasing the overall footprint of the revetment.
  • Treasure Island, SF; Brooklyn Bridges Park, NYC


DESIGN OPPORTUNITIES:
Ecological Enhancements
Urban Design
Form
  • Vegetation benches and aquatic habitats can be integrated into the design of revetments
  • Pathways can be set on top of revetment structures
  • Revetment structures can have different slopes and create unique spaces along the waterfront


DESIGN CONSIDERATIONS:

  • Armor layer must be sized to remain stable under extreme wave conditions as well as propeller wash from ship operations at the site.
  • Underlayer size and grading should meet specific filter and stability criteria to prevent loss of soil material and underlayer material.
  • Design must account for geotechnical stability and foundation settlement. • Additional stone is normally placed at the toe to support the armor layer and to prevent scour of the toe.
  • Design should consider potential for erosion behind the crest due to wave overtopping.

SITE-SPECIFIC CONSIDERATIONS:

  • Water levels, waves, currents, propeller wash from ship activity should be well defined.
  • Geotechnical investigations should be performed to determine potential for settlement and stability.

ARCHITECTURAL CONSIDERATIONS:

  • Randomly placed rip-rap on the armor layer may not be an aesthetically attractive at certain locations. Fitted stone could be considered as an alternative.

URBAN DESIGN CONSIDERATIONS:

  • Rip-rap revetments can present a hazard if people walk on or climb down the revetment. Armor stone should be angular in shape or other measures should be employed to discourage people from climbing down to the water over the revetment.
  • Rip-rap of revetments accessible to the public should be sized large enough to prevent removal of stones by people.

INSTALLATION AND CONSTRUCTABILITY CONSIDERATIONS:

  • Installation can be performed from landside or waterside from a barge.
  • Requires grading of existing soil prior to placing revetment material. Potential for suspension of sediment.

OPERATIONS AND MAINTENANCE CONSIDERATIONS:

  • Once constructed, little to no maintenance should be required.
  • Revetment should be inspected periodically following significant storm events and damage areas that could affect the stability of the structure repaired.


Download the Rip-Rap Revetment Factsheet.

Learn about other types of measures from our Measures Explorer page.