Agenda - Planning Commission - 03/03/2011

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port, where there are safer places to develop, this mound would remain undeveloped. WHAT DO WE BUILD? As discussed above, compact communities with a sense of place are the most enduring coastal communities anywhere. First and foremost, then, we want to build great communities. The prin- ciples of smart growth enable us to build great as well as safe and resilient coastal communities. Generally, in areas of High resiliency, development codes should generate compact, mixed use, and vibrant places, but in areas of low resiliency, these same codes should limit growth and density. Strategies for getting the right rules in the right areas are discussed below. 0 Zoning for Areas of High Resiliency Development codes for areas of high resiliency must have zoning districts that allow compact, mixed use development. But sim- ply setting high -density thresholds and allowing a wide mix of uses will not generate the vibrant and love- able places that make New Orleans and Venice impossible to abandon. Coastal communities must also consider how their regula- tions help build neighborhoods, not just subdivisions. The community is likely to be more tolerant of density in infill settings if the form of the density fits with their neigh- borhood. Development codes can help shape this form in a more predictable manner. Building Types. Developing a palette of building types or development types that are available in each zoning district can help in a number of ways. It can allow a community to influence the types of buildings on given streets or blocks. Areas intended for three to eight -story mixed use or apartment build- ings could be mapped to only allow these building types, while areas where compact cottages or row houses are desired may be mapped to reflect this pattern. Ideally, this more prescriptive approach will be coupled with a more streamlined approval process. In addition to placemaking qualities, building type regulations also provide com- munities with the ability to require building - specific hazard defense strategies, depend- ing on the zoning district where the building is located. Buildings in high -resiliency areas that stilt may be prone to occasional flooding might be required to address their ground floors differently than buildings that are less likely to be flooded. Lot Size. Zoning for reasonable minimum lot size is essential in generating compact form. Recent residential patterns through much of the coast consist of 7,000- to 9,000-square-foot lots or larger. This is a recipe for sprawl, not compactness. Historically, we didn't build this way. Some of the most loved and resilient neighborhoods in New Orleans mix detached homes on lots averaging around 3,500 square feet to achieve densities of 12 or more units/acre. Streets of detached cottages, mixed with larger homes, can create compact residential pattern that allow coastal communities to become resilient and loveable places. The relatively high topographic ridges (shown in white over this Katrina flood zone map) in New Orleans could accommodate all of the pre -Katrina population at roughly French Quarter densities. The edges of these ridges would have had at most about two feet of floodwater during Katrina. Some adaptation in terms of durable structures and elevation would still be necessary in these areas. The kind of construction found in the French Quarter would be consistent with the lower edges of the ridges. Development codes can promote this pattern by allowing smaller lot sizes or by averaging lot sizes, with upper and lower thresholds. Lot Coverage. Maximum lot coverage is another regulatory device that must be addressed if compact development is to oc- cur. The tendency in some coastal areas is to discourage compact development by applying low lot coverages of 20 to 4o percent. The idea is that by spreading development out the large pervious lot areas will absorb stormwater. While this approach may at first seem rea- sonable, there is no amount of pervious lot area that can absorb the storm surge associated with a major storm event. The "safe" land is too valuable for this approach. A more appropriate approach is to allow much higher lot coverage (7o to 90 percent) in areas of high resiliency. By building compactly in the high -resiliency areas, communities are able to leave the less resilient land open for stormwater. Street Setbacks. As with lot size and lot coverage, large minimum setbacks can lead to difficulties in building compactly. Allowing, or in some conditions requiring, a built -to environment where the buildings are placed at the street can help in two ways. It makes building compactly more efficient and helps activate the streetscape by reorienting the street toward the pedestrian scale. Building Compactly in Rural Areas? It may seem counterintuitive, but even in coastal areas that are perceived as "rural" in character, compact, mixed use, and vi- brant development patterns can contribute to improved resiliency. Fundamentally, the same policy applies. If density is clustered into small rural nodes it shrinks the area to be protected and can make certain defense strategies more affordable. An example of this development type can be seen in the clustered density of Hallig Hoog, Germany. The settlements on this rural island are on a handful of elevated terpen, or earthen mounds. The top of each one- to three -acre terpen is developed with a small number of compact farmsteads, homes, shops, restau- rants, hotels, or civic buildings. Several times a year, storms flood the lowlands, but the elevated terpen and their associated develop- ment are out of harm's way. Each terpen has a compact design, with a clustered density of around eight to 12 units per acre, but maintain a low overall gross density of less than one unit/4o acres. This settlement pattern pro- vides the two benefits noted above. The com- pact, mixed use, walkable clusters maintain a rural form while shrinking the area that must be protected from storms and flooding, and it allows the community to pool their resources to elevate and maintain the terpen. A similar development pattern is achievable along the United States coast through the use of innovative zoning and subdivision rules. Alternative subdivision types, such as cluster or conservation subdivisions, along with mixed use zon- ing districts that allow for consideration of gross density in rural areas, can work together to allow this pattern. The zoning districts should respect the rural character using building type or other form controls to promote hamlet -style settlements in "rural" ZONINGPRACTICE i.is AMERICAN PLANNING ASSOCIATION I page 6