Downspouts and run-off management. Not the likeliest source for innovative and ecologically sound pollution control. Or are they? Well, yeah. Most urban environments deal with storm water surges brought on by heavy rains in much the same way: drainage pipes are laid around the foundation footings to collect run-off from the roof and subsequently fed to larger pipes which ultimately drain into larger bodies of water (rivers, the ocean, or in our case The Puget Sound). Along the way that water accumulates spilled motor oil, pesticide and herbicide residues and deposits these pollutants where they poison and otherwise damage fragile marine ecosystems. What is all this getting at, you might be wondering? Enter the rain garden.
Rain gardens are beautifully planted storm water management systems that supersede the common practice of keeping that water out-of-sight-out-of-mind and utilize the resource to nurture native plants. Downspouts are channeled to a designated area that has been excavated to a size and depth calculated by the volume of water falling on the roof and the drainage capacity of the soil. A mix of sand, compost and original soil are filled into the hole, leaving an area for ponding in times of excessive rainfall, and plants situated to be adapted to the different 'zones' of relative saturation when the rain garden is actively filtering water. Rather than all that precipitation flowing directly into the nearest body of water and carrying with it all the attendant pollution, it percolates through the garden and provides an aesthetically pleasing landscape feature.
Ours is well under way: the pipe located, trench and hole dug, and berm built at the garden's outflow. Phase 1: planning, involved determining the site of the garden (at least 10 feet from the foundation) as well as the size. Phase 2: digging. The next phase will involve the mixing of the soil to be filled in the hole and the planting of adapted species. Finally we'll be ready for the rain.
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