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3.1D – Planning and Design – Landscaping

Management Measure

  • Increase groundwater infiltration and recharge by exposing native soils.
  • Increase pollutant attenuation through bioretention.
  • Collect and store non-potable water on-site for use in landscaping.
  • Use landscaping to maintain or restore predevelopment hydrograph.
  • Plant and maintain urban forests.
  • Prioritize landscaping with native plants that are adapted to site specific soils and hydrologic regime.
  • Use topography such as berms to reduce runoff and maintain water on-site.

Management Practices

  • Increase groundwater infiltration and recharge by exposing native soils
    If possible, remove impervious surfaces and expose native soils. Planting vegetation and trees will provide shade and improve bioattenuation of polluted runoff, as well as increasing the aesthetics and provide a park-like setting for recreation. See Management Measure 3.1C, Impervious Surfaces.
  • Increase pollutant attenuation through bioretention
    Polluted runoff is treated by natural soil process (or if natural soils are unavailable, then an engineered soil medium) and phytoremediation. The ideal application is for median strips, parking lot islands, and vegetated swales. Bioretention is not appropriate where soils are subject to freeze and thaw, where groundwater is less than 6 feet below ground surface or groundwater recharge zones, for slopes greater than 20 percent, or in sensitive habitats such as areas where mature trees are growing. Vegetated swales should be planted with grasses that require minimal maintenance and grow at least twice as tall as the maximum height of standing water or at least 4 inches, and side slopes should not exceed 3:1. Vegetated buffers should be planted with native grasses that require minimal maintenance. The width of the vegetated buffer should be at least an order of magnitude less than the width of the area draining into it, e.g. 150 feet wide area would need a vegetated buffer of at least 15 feet. Ensure that soils are permeable enough and the infiltration area is large enough so that water drains in three (3) or less days; this is necessary to ensure mosquito breeding is unsuccessful. Some areas may have mosquitos that take longer to complete their life cycle, visit this Website for information specific to your region.
  • Collect and store non-potable water on-site for use in landscaping
    Disconnect downspouts from roof or other impervious surface runoff collection systems and store water in a cistern, rain barrel, or other small scale water containment device. Make sure that water is stored in a closed container. Use this water on-site for landscaping irrigation, assuming the water is good quality. Always have water tested to be sure. Underground vaults can also be installed to capture and re-use irrigation water.
  • Use landscaping to restore or maintain predevelopment hydrographs
    Install green roofs in highly urbanized areas. A green roof consists of vegetation and soil, or a growing medium, planted over a waterproofing membrane. Additional layers, such as a root barrier and drainage and irrigation systems may also be included. Green roofs can be used in many applications, including industrial facilities, residences, offices, and other commercial property. In Europe, they are widely used for their stormwater management and energy savings potential, as well as their aesthetic benefits (source: EPA Heat Island Effect). Green roofs can also provide habitat for birds and flying insects (e.g. honey bees).
  • Replace Lawns with Rain gardens
    Rain gardens are small bioretention cells landscaped with plants, trees, and grasses. They are a particularly good way for individual homeowners to enhance their landscaping while protecting water quality. By planting easy-care native wildflowers, hardy perennials and grasses, attractive gardens can be constructed that have the added environmental benefits. Ensure that soils are permeable enough and the infiltration area is large enough so that water drains in three (3) or less days; this is necessary to ensure mosquito breeding is unsuccessful. Some areas may have mosquitos that take longer to complete their life cycle, visit this Website for information specific to your region.

    Install planter boxes to use urban runoff from disconnected downspouts in landscaping. Pollutants can be attenuated by phytoremediation and soil microbial activity. To make sure that soils contain the correct amount and type of microorganisms use soil amendments such as microbial inoculations or good quality compost.

    Curbs should be eliminated to allow highway and road runoff to be filtered through vegetated shoulders and medians. Eliminating curbs also increases infiltration to ground water. If eliminating curbs is not possible, curbs can be designed with breaks and energy dissipaters to direct sheet flow to vegetated surfaces. These infiltration areas will require periodic inspection for damage, rilling, ponding, and trash accumulation, and will also require mowing or cropping of vegetation to prevent nuisance conditions.
  • Plant and maintain urban forests
    Urban forests provide shade and reduce the urban heat island effect; improve soil and enhance bioretention; and improve air quality by absorbing nitrogen oxides, sulfur oxides, particulate matter, and carbon dioxide.

Programs

  • Boston’s Water and Sewer Commission's Downspout Disconnection Program identifies and disconnects downspouts that discharge into the sanitary sewer system.
  • USDA, Effects of Urban Forests and their Management on Human Health and Environmental Quality Program. Scientists and technical staff conduct and analyze various field measurements and develop computer programs to better understand the structure, functions, and benefits of urban forests across the world. Numerous user-friendly tools are also being developed to aid local constituents in analyzing the structure, functions, health, and value of their own urban forest resource.

Information Resources

  • Center for Watershed Protection (CWP), Urban Watershed Forestry Manual provides information on methods for increasing forest cover in a watershed; specific ways to enable developers, engineers, or landscape architects to incorporate more trees into a development site; and detailed guidance on urban tree planting at both the development site and the watershed scale. Parts 1 and 2 of the manual are available for download at this Website.
  • Delaware Department of Natural Resources and Environmental Control Green Technology: The Delaware Urban Runoff Management Approach is a technical manual that reviews impacts of urban runoff on stream ecosystems and riparian zones. The manual presents how green technology management practices can effectively address these impacts and how to properly design the most appropriate management practice. The document includes chapters on construction and testing specifications, design standards and specifications, landscaping standards and specifications, summaries of standards for management practices, and a set of typical details for each type of management practice.
  • D.C. Greenroofs has information on green roofs and cisterns/downspout disconnections.
  • Summit Pump Station Green Roof Project is a 1,200 square foot green roof constructed in central San Francisco, as part of an upgrade of the pump station facility. Impetus for the green roof was primarily aesthetic, because the facility roof is visible from the surrounding hills, and also hydrologic, to provide low-impact stormwater management.
  • Green Roofs for Healthy Cities’ mission is to increase the awareness of the economic, social, and environmental benefits of green roof infrastructure across North America and rapidly advance the development of the market for green roof products and services.
  • Low Impact Development Center contains technical references for implementing low impact development techniques and has case studies of sites where these practices have been successfully implemented.
  • TreeLink was created to provide information, research, and networking for people working in urban and community forestry. For the researcher, the arborist, the community group leader, the volunteer - our purpose is to inform, educate, and inspire.
  • Urban Forest Ecosystems Institute (UFEI) is based at the College of Agriculture at California Polytechnic State University, San Luis Obispo, California. UFEI was developed by the Natural Resources Management Department faculty to address the increasing need for improved management of the urban forests in California.
  • Lemoine, R. October 2007. An Evaluation of the Reduced Environmental Impact from High-Density Development. Stormwater Journal.
  • Portland, Oregon Environmental Services Program on downspout disconnection has a manual on Downspout Disconnection: how to disconnect downspouts.
  • Stoner, N. 2006. Rooftops to Rivers: Green Strategies for Controlling Stormwater and Combined Sewer Overflows. Natural Resources Defense Council.
  • UC Davis Extension Center for Water and Land Use, Low Impact Design provides tools, resources, courses, and workshops on low impact design techniques.
  • University of Minnesota, Urban Forestry Database, indexes publications relating to the history of urban forestry; urban forest legislation; the benefits of urban forests, selection and planting of trees; maintenance of the urban forest; planning and management; and urban forestry programs.
  • USEPA 832-F-99-012, Stormwater Technology Factsheet: Bioretention provides technical information on bioretention, including sizing, costs, operation and maintenance, and limitations.
  • USEPA, Heat Island Effect – Green Roofs provides detail on the environmental benefits of green roofs and an associated page provides information on urban forests.
  • USEPA, Watershed Academy, Making the Connection: Smart Growth and Water Resource Protection this training module explains how changes in land use can impact water resources and presents national data on trends in development patterns and activities on land that have become increasingly significant challenges for achieving water quality standards. The module suggests various methodologies used to accommodate future growth in a way that is beneficial to both the economy and the environment. The module also includes a "tools" section with links to on-line resources.

References

USEPA. 2005. National Management Measures to Control Nonpoint Source Pollution from Urban Areas. EPA 841-B-05-004. U.S. Environmental Protection Agency, Washington, DC. Downloaded from http://www.epa.gov/owow/nps/urbanmm on March 3, 2008.

 

(Updated 9/4/08)