How To Design Sustainable Patios and Walkways

The walkway and sitting patio in this tiny Pacific Beach backyard were segmented, allowing more area for rain to penetrate into the soil.

 The second part of a two-part series.  We discussed the watershed approach  in the last article: How to Design Sustainable Patios and Walkways. But what exactly is the watershed approach?  To understand this concept, let’s reverse the terms.  We approach our outdoor landscapes as a natural watershed, which it is.  The old concept of draining excess water directly to the gutter is archaic in California, replaced with the idea that we need to save this valuable resource and use it when we can, allowing it to sink into the soil and nourish plants rather than sending it to storm drains.  It’s not only ethical, it’s practical and will save money on the water bill.
      How does the hardscape play a role with the watershed approach?  As explained in Part One, hard or impermeable surfaces need to be minimized but that does not necessarily translate to less patio and walkway surface overall.  We just need to use our design skills to allow areas for water to runoff and pool, then pick the right materials that are conducive to our goals.  Here are a few tips.

1. Begin with a concept plan, drawing a rough sketch. Plot out the size of areas that people witll utilize to enjoy and move through garden areas.  Make these areas large enough for comfortable use.
2. The rest of the landscape will presumably be used for plants, dry streambeds, etc.  Ideally there is a comfortable square footage ratio of hardscape to softscape.
3. Include the house and outbuilding footprint, and any other impermeable existing surfaces in your ratio calculations.  The ratio may be overwhelmingly in favor of hard surfaces and structures. Time  to get creative.
4. Plot current drainage.  Where will rain runoff go?  Draw arrows that direct runoff away from buildings and living areas – any places you don’t want water to remain after a rain.  Direct runoff to planter beds in the landscape where it can settle, by designing in dry creek beds, etc.
5. Make sure you later choose plants that can tolerate periods of sitting in water in these low-lying areas designated as ponding beds.
6. Still not enough space for water to safety drain and sink into the soil?  Get more creative.  Draw in rain barrels under the eaves to capture water.  Break up hard surfaces.  Walkways, especially secondary walkways, can be made of decomposed granite or crushed decorative rock, patios can be creatively laid in segments with spaces left for gravel or ground-hugging plants.  Even concrete can be laid as permeable, a specialized mix installed by a qualified contractor. There are many  creative ways to capture most, if not all excess water, even on a small lot.
7. Still worried about too much water? Drains can be set a few inches above the soil area in our low spots created for ponding.  These drains can be used to carry excess away from the property during those gully washers that, though rare, occasionally hit the San Diego region.

These seven how-to’s describe, in a nutshell, how to turn water runoff into a recycled, valuable resource – the key points in using the watershed approach to design your landscape.

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