This is the site before we began the renovation, showing the typical rain water runoff pattern through the property.
Diagram of schematic layout of system. We designed a system that slows the storm water runoff, temporarily stores large volumes of water on site, promotes infiltration of water into the subsoil, captures and stores water for landscape use, and reduces and slows the storm water flow downstream. The system includes six components that contribute to the solution: water infiltration and storage swales, water features storage tanks, infiltration and storage pond, recirculating stream that doubles as water features storage, dry creek beds, and appropriate plantings for occasional water inundation.
Schematic of swale construction
The infiltration swales are the first line of defense. They slow and channel the runoff as it flows down the sloping backyard toward the house. They are designed to store water and allow it to percolate into the subsoil. The swales were installed outside the dripline of a large old Magnolia grandiflora, which both thrives in wet soil and is capable of transpiring large amounts of water.
Infiltration swale under construction
Infiltration swale grown in by year 2
When the swales have reached capacity, they overflow into a below-ground cistern. Water from this cistern is distributed in two ways: to supply drip irrigation and for replacing water lost to evaporation in the ornamental water features. In addition to the below-ground cistern, the project includes separate rainwater storage under a deck, which collects water from the roof of the home to also use for irrigation and water features.
Stream completed and grown in year 2
Close up of stream detail
When all these water-storage components are filled to capacity, the excess overflows into an infiltration pond, which is planted with a variety of garden plants that tolerate occasional inundation, such as bald cypress, summer sweet, swamp hibiscus, ferns, and rushes. Much of the water seeps into the surrounding soil, some evaporates, and some is absorbed by the garden plants and transpired. When the infiltration pond is filled to capacity, it continues to slow the flow of water so that its speed and eroding power are substantially reduced before it is released downstream.
The urban backyard is now a beautiful habitat for garden plants and wildlife.
This great blue heron and a host of other species entertain the homeowners and find a habitat in the middle of the city.
Although the principal landscape design effort was directed toward management of the storm water problem, the site does not look at all as if it were designed for storm water control. In the eyes of the owner and visitors, it is a lush, natural-style garden dominated by a convincingly natural pond and stream water features.