Passive Irrigation & Rainwater Harvesting Retrofitting New ConstructionJanuary 10, 2019
Closing one door and opening another! We love the challenges presented by new construction. In this case, a beautiful addition to the rear of our client’s lovely home in Mamaroneck required extensive conventional engineering and drainage construction.
With all the rainfall this year we have to ask…where do we put the water?
When designing storm water systems, we must consider three sources: sheet flow (surface storm water), ground water, and water displaced by impervious space (i.e. house patios, walks, driveways, pools, ponds etc. that prohibit water from infiltrating to the aquifer
Typical of new construction, to conform to building codes and gain architectural review board approval, subsurface drainage systems are designed to contain allrainfall/storm water on site during a specific, extreme storm event. This usually includes solid piping (from gutters/leaders) and/or perforated pipe surrounded by gravel, in conjunction with storm chambers, cultecs , or some form of galleries or underground dry-wells. While highly effective as designed, when constructed and installed they are limited in the ability to accommodate all the surface water. This is particularly true in the case of managing runoff from adjacent properties.
[Above: Rain Water Harvesting Passive Irrigation system overlayed on existing dry well system required by town for the new construction.]
GJL was hired (in part) to optimize the existing system by supplementing with a tile-like piping system, which will deliver roof collection of storm water from gutters and leaders, redirect it to landscape planting beds, as well a rain garden and two gravel surface patios. An important component of our passive irrigation system is a vertical infiltration pipe connected to a distribution box/clean-out from the system, which insures that surface water reaches the deeply buried dry-wells (~3’ below grade). This is critical to insuring performance and ease of maintenance. Don’t forget to clean your distribution boxes of leaves and debris!
In addition, we find it very helpful to treat the soil to relieve compaction due to construction or the existing soil type (i.e. heavy clay). Sometimes this involves excavating, rototilling, or soil amending with sand, compost, gypsum etc. This pertains to lawn, landscape planting beds and basically all of the 6-8” depth of soil surface.
The next step is to compose the landscape with plants that will improve the natural hydrologic cycle. That is determined by the right soil type, sun/shade, topography and of course the aesthetic style of the landscape design composition and theme. In this case the gardens were named: Health and Healing Garden, Cornucopia of Hope (which includes a water feature, fire pit and living wall) and the Bird and Butterfly Rain Garden. The end result is to create a beautiful and highly ecologically functional landscape in terms of resource management.
A landscape should be beautiful to look at while improving our human health, managing and conserving resources, creating habitat for beneficial species, and critically important: producing a carbon positive landscape environment!
We can make our world more beautiful and healthier by designing and building carbon positive ecological landscapes!
Jay Archer, President