Permeability

Patio PadsI’ve been having some conversations with our Home Provider about permeability. 

Because stormwater runoff is a bad thing (moving water with pesticides, fertilizer and general trash into the sewer system, local lakes and streams), LEED SS4.2 values permeability – meaning it’s a good thing for the rainwater falling on your property to soak into your property and not run into your neighbors yard or into the street.

LEED provides a graduated point system that ends with 4 points for 100% permeability.  Keep in mind that 100% permeability doesn’t mean you can have -0- concrete.  Rather the Rating System states that you have to have features that direct water falling on the impermeable areas to features designed to capture the water and direct it to an area where the water will be absorbed.

With this post I provide a photo of our back patio – designed to direct water to the spaces between the concrete pads (versus having a solid slab).  Also, next to the patio (and difficult to see in this photo) is a swale that keeps the water from running downhill into our neighbor’s yard. 

drive_ribbon_2 (2)

The key question that I’m discussing with our Home Provider is the driveway ribbons.  We specifically designed this drive for permeability purposes.  The current question is whether the space between the ribbons is sufficient to support the amount of runoff from the ribbons…our Landscape Designer is working on the calculations.

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July 15th, 2009 2:35 pm

Thanks Greg for that informative post. Yes, we need not totally eliminate impermeable surfaces from our landscape. We just need to ensure that water in our backyards manage to get to other places within our premises where they can permeate into the soil and not run off into the sewer system. Makes absolutely perfect sense.

Thanks for the wonderful tips.
Joost Hoogstrate

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