The Elk Grove Rain Garden Plaza Continued
Enter the Rain: Permeable Perks
Make Like Water and Pour
Mommy…What’s a permeable?
Sounds like an eruptive skin condition, an ultra hideous pimple that has come to stay forever. But no, it’s most often the missing element in new gardens. Permeable means admitting the passage of fluids, air and nutrients. We also use the term pervious interchangeably with permeable. With rain gardens we are most concerned with water permeability. Think of the material as having pores, so we can pour water through it. There are several permeable surfaces to explore at the Elk Grove Rain Garden Plaza.
With permeability, your choices matter. I am so excited about a local rain garden demonstration because now I can show people firsthand how the materials we choose for our landscape projects can make a big difference in water quality and conservation. I love that the park includes a hands on way to learn more about how water either infiltrates or runs off the different surfaces typically found in a suburban yard. Now let’s explore the big P!
What is water permeable?
- Permeable paver
- Decomposed Granite, aka DG
- Rocks and gravel
- Permeable concrete and asphalt
- Mulch
- Decks
- Healthy soils
- Plants
- Mulch
- Landscape fabric
permeable pavers
permeable concrete
composite decking
plants w/ mulch
DG on right
What is not water permeable?
- concrete
- compacted soil
concrete between two pervious surfaces
- mortared pavers and stone
- pavers and stone without joint openings
- plastic sheeting
These materials all have one thing in common: They allow no escape for water, there are no pores for flow or permeability. There is no flow so that water will collect and quickly shoot off these surfaces. At worst these materials can cause soil erosion, occasional flooding, or just be a nuisance in low lying areas. I would recommend avoiding any of these materials for large areas of a landscape for these reasons.
Here is not permeable in action:
Notice the water running right off the top of the concrete, bunching and quickly forming a mass that rolls downhill. Remind you of our floods here in the valley?
And here is permeable in action:
Enter the Rain
So why would you want a rain garden like this? Why would you choose these permeable materials? The Plaza exposes the micro watershed to our eyes. I LOVE this stuff! In a traditional landscape water shoots off our rooftops into drainage which is hidden underground. By not seeing this cycle of what I call water abuse, we lose track of what is really happening to our precious water, both wasted and saved. A visit to this park allows us to experience directly what happens to water as it hits the ground onto various different conditions of permeability. We can then imagine water percolating through the rain garden into local rivers, or shooting off the impervious concrete of our driveways into local creeks. Hmm, which one would I rather drink? Live in if I were a fish or frog? Which one will provide cleaner water for people downstream?
What thoughtfully planted rain gardens with permeable surfaces can do for you:
- Recharge our ground water
- Keeps water on your property site
- Make your property a mini watershed
- Eliminates chemical inputs of fertilizer, pesticide, fungicides etc.
- Supports pollinators, plants bloom year round
- Save money on water bills and maintenance
- Reduce maintenance time & equipment
- Cools and reduces summer heat
Your choices matter. Remember, your gardening practices and how your landscape is designed and constructed can make a difference in the larger scheme of sustainable life. For the residential scale, don’t let all that mass of decking and expensive hardscape fool you. Your yard can have all of this, or any combination of elements.
Do This: Watch this extra cool local documentary Slow the Flow http://www.waterboards.ca.gov/stormfilm/.
29 minutes. Short and fascinating.
Your Feedback: Note from the documentary Slow the Flow how permeable driveway strips are being encouraged in the San Francisco Bay area. Would you consider doing this in your home or rental? If not your driveway, what other surfaces in your yard could be successfully converted into permeable? I would love to hear your feedback on this idea. Write me back: Is it radically right? Or realistically wrong to cut up a driveway? What are the advantages, drawbacks? What would the neighbors say??
Go There http://www.elkgrovecity.org/rain-garden/index.asp
Got questions or need some help? Call a Green Gardener:
http://www.bewatersmart.info/water-smart-gardening/green-gardener/
Check out more of the Elk Grove Rain Garden Plaza with me in my next blog…
