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

Coastal Hazards flooding storm surge moving water erosion

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StormSmart Properties Fact Sheets Provide Provide informa information tion for for proper property ty owners: owners: • 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 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) 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

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 of 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 • 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 Photos: Wilkinson Ecological Design Site: Barnstable, MA

Bioengineering: Coir Before Rolls & Vegetation 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 ongoing 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 • Add compatible sediment • Increased volume protects landward areas without reflecting wave energy Before Nourishment Photo: Applied Coastal Research & Engineering Before Nourishment • Scale of project may vary: one size does not fit all •Mass DEP’s Best Management Practices for Beach Nourishment in After Nourishment Massachusetts Photo taken after Winter Storm Juno

Elevation of Buildings • Use open pilings without footings in dunes and areas subject to erosion. • Allows overwash and wave energy to dissipate naturally over 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 options 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

Resources 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