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a green roof?
rain garden/native habitat garden/bayscaping
dc greenworks partners with the Anacostia Watershed Society (AWS) in the implementation of RiverSmart Communities, a District Department of the Environment program geared to multi-family residences and houses of worship. Through the program DCG has installed rain gardens, native gardens, bayscaping, as well as cisterns, at projects that include McLean Gardens and Logan Circle Condos. For more about the two projects, read our press. Is your condo board or church interested in learning more? Visit the RiverSmart Communities website.
Rain gardens and bayscaping are both available to homeowners through the RiverSmart Homes progam, each with its own distinct advantages. For more, read on.
Rain gardens are shallow landscaped depressions that capture rainwater runoff from impervious surface areas, including rooftops, paved streets, parking lots and compacted lawns. Rain gardens absorb the rainwater runoff at or near where it falls. This reduces the load of runoff into municipal sewer and stormwater systems. In separated stormwater systems rain gardens prevent runoff, carrying pollutants and trash from streets and lawns, from entering directly into waterways, eroding stream and river banks, and causing sedimentation damaging to aquatic life and recreation.
Rain gardens are typically planted with wildflowers and other native vegetation over a complex mix of soils, sand and gravel that allow approximately 30% more water to soak into the ground. Following a heavy rain, runoff will pond in the rain garden and be slowly filtered by the plants and soil.
A simple rain garden can be planted in most landscapes with little or no modification to existing conditions. It is easiest to plant the garden based upon natural drainage flows (look for low spots where water ponds following a heavy rain). However, if this is not feasible due to the location of existing structures, or for other reasons, some minor landscaping can redirect flows to areas that better meet site conditions.
Because the depth of a rain garden can be as little as six inches, heavy machinery is not necessarily required. Even sites with heavy clay or compacted soils can be conducive to rain gardens. For clay or hardpan soils, some excavation and replacement of soil may be necessary. When replacing soil, a mix of 50-60% sand, 20-30% topsoil, and 20-30% compost is recommended. Compacted, hardpan soils should be loosened, for drainage and root growth, to two feet deep. Ideally, the rain garden should be planted with native or locally adapted plant species. This provides for ease of care and maintenance as well as habitat for local, often beneficial, wildlife.
In the Mid-Atlantic Region, BayScaping is planting vegetation native to the Chesapeake Bay region. Native plants are indigenous species that were present in our region prior to the arrival of Europeans. BayScaping is a low-cost alternative to traditional landscaping that utilizes turf grass and ornamental plantings.
BayScaping requires much less maintenance and cost than a grass lawn. BayScaping:
- can eliminate the need for mowing, pruning, irrigation and fertilization
- is 50-80% less costly than conventional landscapes
- has a greatly survival rate than turf and ornamental plants
- is creative, unique and aesthetically pleasing
The District Department of the Environment (DDOE) promotes BayScaping. Through DDOE’s RiverSmart Homes Program BayScaping improves the health of local streams and waterways by absorbing more stormwater than a conventional landscape. Learn more about BayScaping in DC here.