Property Owners to Address Coastal Erosion and Storm Damage Rebecca - - PowerPoint PPT Presentation

StormSmart Properties: Resources for Property Owners to Address Coastal Erosion and Storm Damage Rebecca Haney

April 26, 2019 Coastal Geologist Massachusetts Office of Coastal Zone Management

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StormSmart Properties Fact Sheets

Provide Provide informa information tion for for proper property ty owners:

• wners:
• Inform decisions about shore

protection techniques

• What the technique involves
• How it reduces storm damage
• Relative benefits
• Limitations
• Ways to minimize impacts
• Design considerations to

maximize effectiveness

• Permitting
• Professional services
• Project timeline
• Maintenance
• Additional information/resources
• Cost comparison table

Dune Nourishment & Artificial Dunes

Artificial Dune

• Construct seaward of an

eroding coastal bank/bluff

• Volume determined by desired

level of protection

• Grain size
• Slope
• Sand fencing and vegetation
• Sacrificial dunes

Dune nourishment

• Need space: dry beach at high

tide seaward of dune

• Use compatible sediments
• Design slope: 3:1 or less
• Combine with vegetation and

fencing

• Minimize impacts to sensitive

habitats (e.g., slope, grain size)

Vegetation Vegetation

• Salt-tolerant plants with

extensive roots hold soils & absorb runoff

• Plant diverse mix of

native, salt-tolerant species

• Address invasive

species – remove with caution

• Install plants in the

spring for best results

• Temporary irrigation

may be needed

• Most appropriate where

there is a dry beach

• Establish stable slope

Photos: MA CZM (top), Wilkinson Ecological Design (bottom)

Vegetation

Figure redrawn from illustration by Dede Christopher of the Tennessee Valley Authority, Benefits of Riparian Zones.

Vegetation - Banks

Banks – exposed/lower areas

• Switchgrass
• Saltmeadow Cordgrass
• Little Bluestem

Banks – higher areas

• Northern Bayberry
• Bearberry
• Marsh Elder

Maintenance required!

Photos: New England Environmental Inc.

Vegetation - Dunes

Primary Dunes

• American beachgrass
• Little Bluestem
• Purple Lovegrass
• Seaside Goldenrod

Secondary Dunes - In addition to grasses

• Beach Heather
• Lowbush Blueberry
• Bayberry

:

Bioengineering Definition Bioengineering Definition

The use of dead plant materials strategically combined with living plants materials to provide rapid stabilization of a landform.

Seth Wilkinson, Wilkinson Ecological Design

Photo: Wilkinson Ecological Design

Natural Fiber Blankets

• Blankets stabilize soils devoid
• f vegetation, allowing new

plants time to get established

• Establish a stable slope
• Salt-tolerant seed mix

scattered on bare soil

• Use blankets made of only

natural fibers

• Anchor blankets in small trenches

at the bottom and top of slope

• Install blankets perpendicular to

the bank slope

• Plugs planted through blanket
• Use biodegradable anchors and

twine to ensure appropriate soil/seed/blanket contact

Photos: Wilkinson Ecological Design (top), Cape Organics (bottom)

Bioengineering: Coir Rolls & Vegetation

• Pre-plant vegetation in coir

rolls

• Cover rolls with natural fiber

blanket and sand

• Plant a diverse community of

native, salt-tolerant plants

Photos: Wilkinson Ecological Design Site: Barnstable, MA

• In higher energy areas, a high

density roll may be considered at the toe, with lower density rolls above

• Use duckbill anchors anchored

in compacted sediment

• Do NOT use Mirafi or other filter

fabric under/behind rolls

Bioengineering: Coir Rolls & Vegetation

Before During Construction 10 Years later

• Reflects less wave

energy than structures

• Reduces erosion
• Provide stability at the

toe of bank

• Address invasives
• Establish stable slope
• Use to re-establish

vegetation

Photos: New England Environmental Inc.

Sand Fencing

• Thin wood slats &

twisted wire preferred

• Site landward of

reach of waves

• Avoid plastic &,

metal

Runoff Control

• Significant contributor to coastal

erosion

• Remove and reduce impervious

surfaces

• Maintain vegetative buffers
• Capture & infiltrate runoff
• Regrade to redirect water away

from shoreline

• Minimize maintained lawn areas

Runoff Control Techniques

Repair and Reconstruction of Seawalls and Revetments

• Design improvements should

be used to reduce wave reflection, overtopping, and damage landward of and adjacent to coastal engineering structures.

• Improves longevity of the

structure and reduces maintenance costs.

• Upgrade design to reduce

impacts.

Repair and Reconstruction of Seawalls and Revetments

• Structures do not stop
• ngoing beach erosion.
• Maintain the level of the

beach seaward of the structure.

• Break the cycle of bigger

structures.

Repair and Reconstruction of Seawalls and Revetments

• Keep structures as

far landward as possible

• Address sources of

upland runoff.

• Sloping structures

dissipate wave energy better than vertical structures.

Repair and Reconstruction of Seawalls and Revetments

• Minimize end

effects on adjacent properties by pulling the structure back 15- 20’ from the property line.

• Transition to

adjacent properties to minimize end effects.

Beach Nourishment

Before Nourishment After Nourishment Photo taken after Winter Storm Juno

• Scale of project may

vary: one size does not fit all

• Mass DEP’s Best

Management Practices for Beach Nourishment in Massachusetts

• Add compatible

sediment

• Increased volume

protects landward areas without reflecting wave energy

Before Nourishment Photo: Applied Coastal Research & Engineering

Elevation of Buildings

• Use open pilings without

footings in dunes and areas subject to erosion.

• Allows overwash and wave

energy to dissipate naturally

• ver a wide area.
• Reduces channelization of

water flow around foundations.

• Eligible for lower flood

insurance rates if raised above the base flood elevation.

• Reduces damage to

building, adjacent property and infrastructure.

Photos: MA CZM

Disclaimer

No shoreline stabilization option permanently stops all erosion or storm damage. The level of protection provided depends on the option chosen, project design, and site- specific conditions such as the exposure to storms. All

• ptions require maintenance, and many also require steps

to address adverse impacts to the shoreline system, called

• mitigation. Some options, such as seawalls and other hard

structures, are only allowed in very limited situations because of their impacts to the shoreline system. When evaluating alternatives, property owners must first determine which options are allowable under state, federal, and local regulations and then evaluate their expected level of protection, predicted lifespan, impacts, and costs of project design, installation, mitigation, and long-term maintenance

StormSmart Coasts website www.mass.gov/czm/stormsmart

• StormSmart Properties
• Fact sheets
• Comparison chart – relative costs

Beach Nourishment: MassDEP’s Guide to Best Management Practices for Projects in Massachusetts Contact: rebecca.haney@state.ma.us, 617 626-1228

Resources