The rain garden, in this case a fancy word for a depressed area in the landscape where rain water can pond and slowly infiltrate back into the soil, is partially installed. The trick here is that we’re blessed with heavy clay soil, so we didn’t know if the rain garden would take days or weeks to drain. So far, it seems to empty out after about three to four days of dry weather.
Another trick is that the plants in the lower portions have to survive immersion for indeterminate periods. For this, we’re testing various meadow grasses and perennials to see what works. So far, everything appears to be thriving despite multiple immersions. The lowest point is planted with Deschampsia caespitosa and Carex pansa, with some Lupinus polyphyllus thrown in. Areas that are not normally subject to immersion have Festuca idahoensis ‘Siskiyou Blue’, Muhlenbergia rigens, Calamagrostis acutifolia, Schizachyrium scoparium and Achillea millefolium ‘Paprika’. In summer, the rain garden will become a flowering meadow adjacent to an outdoor dining area.
When complete, the rain garden will overflow into a sediment trap, then into a powered sump that will remove the excess water before the house starts to float. Hopefully with time, biological processes of root growth, burrowing worms and insects will naturally introduce organic matter into the underlying clay and make it more permeable.
Right now, it just looks like a large mud puddle, but we’re hoping that it will transform into a beautiful green area with an added ecological function.