St. Mary Parish Unified Development Code

With a focus of reducing the risk of damage from disasters and promoting high standards of development, the St. Mary Parish has developed a Unified Development Code. A major goal of the Unified Development Code is to improve the overall organizational structure and consistency in the Parish’s development codes. This new code incorporates Smart Growth principles and floodplain management to better prepare the parish, its communities, and landscapes for natural disasters as well as development pressures. To this aim, the code also includes form-based alternatives, such as TNDs, as well as other quality-of-life measures, such as sign and landscape regulations.

In 2002, St. Mary Parish prepared its first comprehensive master plan, which was approved by resolution in December of that same year. A major component of the plan was a first-time parish wide zoning ordinance. The Parish has since established a planning and zoning office, planning and zoning commission, and board of adjustment, as well as completed several amendments to its land use maps. However, the recent spate of storms has made the significance of planning and mitigation all the more apparent.

St. Mary Parish is located in south Louisiana near the center of the state’s coastline. With its proximity to the coast and the Atchafalaya River, the Parish is subject to storm and riverine flooding throughout the year. In particular, the Atchafalaya River generates flooding in the region on a near annual basis during winter and spring. The Parish is also subject to stormwater events and backwater flooding resulting from the combination of riverine and surge events. State and Federal officials rated the Parish eighth in flood-related damages from Hurricanes Gustav and Ike.

Resilience Planning in Action

Due to St. Mary Parish’s geographical location, vulnerabilities related to climate change are increasing. Through the new Unified Development Code, the Parish has been able to integrate ordinances that mitigate flood hazards and design standards that promote appropriate density in specific locations.

Environment

A key component to resilience planning is the integration of Hazard Mitigation and Urban Planning. St. Mary Parish is particularly vulnerable to riverine flooding, storm surge, and backwater flooding. The Unified Development Code includes standards that mitigate flood hazards to residential and non-residential structures by requiring certain mitigation activities. These regulations protect the natural environment as well as citizens’ property.

Proposed Actions:

  • Require structures to be built at or above the Base Flood Elevation (BFE)
  • Non-residential structures to be either built at or above BFE or the structure below BFE be water tight
  • The document provides opening specifications for enclosed, waterproofed structures, ie minimum opening requirements; location above grade, etc.
  • Manufactured homes must be elevated and anchored to resist flotation, collapse, or lateral movement
  • Base Flood Elevation data required for new subdivision proposals
  • Prohibit the use of fill in floodplain
  • Prohibit man-made alterations of sand dunes and mangrove stands in the floodplain

Infrastructure

St. Mary Parish employs a levee protection system to reduce its vulnerability to flooding. This requires careful consideration for how internal stormwater is managed. The plan acknowledges that it is in the public interest to control stormwater runoff increases due to construction and development activities, and protect from environmental degradation through soil erosion, stream channel erosion, and nonpoint source pollution.

Proposed Actions:

  • Require separate storm and sewer systems in new developments
  • Require a Drainage Impact Study for any project which subdivides, develops, improves or builds upon any residential, industrial, or commercial site, unless development increases runoff by less than 10%, or impervious surfaces of development are less than 20% of site area

Community

The Unified Development Code does several things to promote a sense of community and ensure quality development in safe places across the Parish. Aspects of the code include various design standards, construction standards for building in high risk areas, and new planning and economic development oversight entities for the region.

Proposed Actions:

  • Establish a new Regional Planning Commission, the Acadiana Regional Planning Commission
  • Establish architectural standards for Traditional Neighborhood Developments (TND) per district (Center, General, and Edge) and pedestrian elements
  • Implement building design standards to protect quality of building materials, property values, and community character
  • Establish density and intensity of development and common open space requirements
  • In coastal high hazard zones, all new construction to be located landward of mean high tide
  • In coastal high hazard zone, all new construction and substantially improved structures shall be elevated on pilings and columns with the lowest horizontal member at or above BFE; and footings designed to withstand lateral movements due to wind or water loads

New construction and subdivision improvements have a space below lowest floor free of obstruction or with non-load-bearing break away walls