Design the Edge Criteria

While the primary intent of the city's edge has traditionally been to keep land from eroding into the water, the Designing the Edge approach engages interdisciplinary and participatory design to create waterfront edges that achieve multiple goals: in-water recreation, flood storage, access to the water, shoreline habitat and reduced pollution from storm water. The following table lists the alternative design possibilities but not all of the design objectives have to be incorporated in order to be successful.

• Install Varied Surfaces – Rough textured and differently sized materials facilitate different kinds of fish habitat and help algae and filter-feeding organisms to attach and filter stormwater.

• Incorporate Living Water Filtration System – Incorporating mussel, oyster and clam shells into shoreline structures will encourage the formation of a crust of filtering organisms. These will serve as a living water-filtration layer to reduce excessive nutrients and some pollutants.

• Reduce Wave/Wake Energy – Porous, gently sloping terraces result in shallow water zones with high light penetration which is important for fish spawning, food production and wake energy reduction. Gently sloped structures absorb wake energy instead of reflecting it, as vertical structures do. The reduced turbulence lowers scour and stresses on the shore, reduces noise and makes the nearshore safe for kayakers and rowboats.

• Reduce Velocity of Fast Moving Water – Irregular, staggered or curvilinear shorelines with various inlets and coves rather than straightened shorelines, reduce flow velocity and scour by producing a string of eddies. This allows sediment to settle out, creating micro-conditions that are similar to natural shores.

• Build with Porous Surfaces – Porous walls with terraces for plants, capture stormwater runoff, strengthen erosion resistance, and improve the shore's habitat and local water quality.

• Install gabions – Rectangular wire mesh baskets filled with oyster shells and rock encourage attachment of filter-feeding shellfish and salt marsh grasses which enhance habitat value.

• Build with Durable Materials – Marine-grade plastics, salt-resistant concrete, recycled rubber tires and stone can tolerate salt corrosion, vandalism, wake action, ice scour and freeze/thaw expansion and contact.

• Incorporate Bioremediation – Earthen banks, along with vegetated space, allow polluted runoff to percolate through layers of roots, soils and rock, so microorganisms can cleanse the water.

• Accommodate Safe Access – Terraced steps or a sloping shore without sharp rocks allow people to touch the water. These design solutions accommodate safe entrance to the water's edge and allow boats to dock alongside the seawall for evacuation.

• Accommodate Visiting Boats – Cleats for docking and roll-on/roll-off access for emergency vehicles will improve emergency response time.