Planning Approaches for Stormwater BMPs

Strategies

Planning strategies for retrofits must be formulated for all the various levels of executive governance, including elected officials and career service employees, that impact stormwater management. Municipalities must be able to meet the regulatory mandates of the larger governing bodies such as U.S. EPA and State environmental agencies as they grapple with on-the-ground solutions for urban retrofits and reducing combined sewer overflows. Stormwater BMPs are a set of site-specific tools that may be employed strategically at the planning level in the form of green infrastructure planning and at the enforcement level at the permitting and monitoring stages.

As stormwater controls have begun being integrated into the urban landscape as part of an evolving infrastructure network, the responsibilities for stormwater management have moved beyond the engineers who have historically borne the responsibility to planners and decision-makers who play an equally important role in community and economic development. The coordinated effort of technical and planning staffs and elected officials is critical to the success of a distributed, yet integrated system. Stormwater BMPs are adaptable to both micro- and macro-scale applications to solving water quality problems. They are able to meet stormwater management goals as well as other planning and design needs for urban settings to the benefit of urban dwellers and downstream recipients of stormwater. While often considered solely in a technical context, several planning alternatives can influence stormwater management.

Planning Tools for Water Quality Protection
Planning Tools Function
Comprehensive master planning
  • Provides a coordinated approach with consideration of water quality protection.
Stream and wetland setbacks
  • Place limits on development activities within certain distances of streams and wetlands.
  • Maintain natural flood and erosion control functions.
  • Protect infrastructure and homes from moving streams.
  • Use protection zones.
    • Based on public health and safety services.
    • Establishes minimum setback widths.
    • Details permitted and prohibited structures and uses.
    • Allows for non-conforming structures and uses.
    • Includes variance section to maintain buildability and provide flexibility.
Conservation design
  • Allows for partial conservation of natural resources while development occurs.
  • Allows homes to be closer together while remainder of development area is in open space.
  • Requires understanding of site's soils, topography, and natural features.
Distributed stormwater management
  • Stormwater controls are site features implemented at the source of impacts.
  • Potentially reduces stormwater infrastructure costs.
  • Promotes public participation and public education in pollution prevention and maintenance stormwater management practices.
  • Satisfies NPDES Phase II stormwater requirements.
  • Application for retrofit projects.

Creative problem solving of urban runoff with stormwater BMPs can provide a community with a solution that mitigates the identified stormwater problems and adds value to the community in the form of a variety of treatment applications which are attractive and cost less to implement and maintain when considered in a life-cycle cost context. This process allows a municipality to meet its regulatory obligations while enhancing its natural resources.

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Selecting BMP Strategies According to Land Use

Stormwater BMP suitability for particular land uses will influence the selection of management strategies. Once appropriate controls are identified, implementation alternatives for integrating the controls into site are needed. Four implementation strategies that can be used to encourage BMP implementation are:

  1. pilot installations;
  2. watershed-based approaches;
  3. building and site redevelopment projects; and
  4. large-scale urban revitalization projects.

For each municipality, the particular stormwater drivers will need to be identified. This will also influence the controls that are appropriate for the land use and the critical stormwater management parameters (e.g., volume reduction in combined sewer systems, volume reduction and water quality for MS4s with sensitive receiving waters). The common stormwater driver in each instance will be volume control. Controlling volume is critical to achieving the physical, water quality, and habitat goals of stormwater management. Excess runoff volume is the primary determinant of impairment and the root cause of stormwater pollution. The ability of stormwater BMPs to effectively control water quantity allows them to provide enhanced water quality and natural resource protection.

Land use types that already have vegetation are the most readily converted to an urban retrofit. Several of the stormwater BMPs are well-suited for application in areas that are already planned to be vegetated. However, even when land is limited or seemingly non-existent, BMP options are still available, most commonly by methods such as the introduction of green roofs and infiltration planters that can be combined with other necessary functions. Some areas with heavy industrial contamination of soils may not be suitable for infiltration strategies but are appropriate for BMPs that focus on water quality enhancements. A description of opportunities to integrate stormwater BMPs into various land uses is provided below.

  • Landscaped areas are often raised up and shed water. These areas can be reconfigured to function as part of a system of BMPs for stormwater control while still serving the original landscaped area functions.
  • Vacant lots can be evaluated for use as part of the control strategy that a community adopts. The type of BMP used will be determined by the vacant lot's site-specific attributes.
  • Parks and playfields offer large land areas that can serve dual purposes. The recreational use is unimpeded by the introduction of stormwater controls in this setting. Playing fields can be designed and built to act as infiltration areas for stormwater, forested areas in parks are natural infiltration zones, grassy swales can be used alongside of park roads, hard courts can be constructed of porous pavements or as the top of a large concrete cistern, and rain gardens can be installed as part of a habitat or environmental education initiative in a park. Other practices could be implemented as part of the control strategy for a given park or playfield.
    Section drawing showing BMP options for parks and open space.

    BMP options for parks and open space.

  • Dense, urban areas will make use of stormwater BMPs that can be most easily integrated within a building footprint or right-of-ways. Mitigating runoff from these highly impervious land uses will focus on managing runoff from roofs, roads, and parking lots. Green roofs, permeable pavements, infiltration planters, and rainwater harvesting are well-suited.
    Section drawing showing BMP options for dense, urban applications.

    BMP options for dense, urban applications.

  • Urban open space corridors can function as important linking elements in the stormwater treatment train. These corridors are linear features that provide links between destinations for people, wildlife, and water. Several distributed retrofits are logical to evaluate for use in corridors. Grassy swales, rain gardens, and tree boxes are some of the retrofit tools that can be installed to mitigate stormwater runoff.
    Section drawing showing BMP options for open space and transportation corridors.

    BMP options for open space and transportation corridors.

  • Commercial and governmental entrances, property line buffer zones, and campus applications provide retrofit opportunities. Entrances are developed to draw attention to a place. The use of a BMP that is attractive allows the entrance to multiple functions, such as marking the entrance, improving stormwater quality, and reducing stormwater volume. Rain gardens infiltrate and clean the water while creating an attractive low maintenance entrance. The style of a rain garden can vary from the very formal to more casual aesthetic.
    Section drawing showing BMP options for government buildings and big boxes.

    BMP options for government buildings and big boxes.
    Click to view larger image.

  • Urban residential areas provide many opportunities for stormwater BMPs. Almost the full range of control options are available for this land use type and are well-suited as a stormwater control and aesthetic amenity. Typical building construction and available green space, though limited, provide sufficient opportunity to integrate a treatment train approach that incorporates rainwater retention and reuse.
    Section drawing showing BMP options for urban residential areas.

    BMP options for urban residential areas.

  • Suburban residential areas offer a range of possibilities for stormwater BMPs. A combination of preservation and minimization techniques can complement the introduction of stormwater controls. Available open space is conducive to downspout disconnection efforts. The use of stormwater BMPs also provides aesthetic and community benefits that have been well-received by residents.
    Section drawing showing BMP options for suburban residential areas.

    BMP options for suburban residential areas.
    Click to view larger image.


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