Watering green - low-flow, no-mow
When it comes to green building, energy is first-born, and water is the red-headed step child. At least until recently as the infernal drought in California has grabbed headlines and alarmed many of us west of the Mississippi.
Nine cities in the United States are literally running out of water, and 100 percent of those are in California. Not only could zero water foreshadow emigrations from cities and perhaps entire regions, think what dry faucets would do to real estate property values. (Las Vegas – I’m talkin’ to YOU.)
A number of green-building certifications like LEED are ahead of the curve, incentivizing water savings and aquifer recharge by requiring owners to “infiltrate” runoff on-site
(soak up water like a sponge) rather than dumping it into the streets and storm sewers. The goal? Use as little potable water as possible, and recharge as much as possible.
The irony is that the dirtiest water on a site is the runoff right after rain starts – when chemicals, pet waste, oil and other pollutants rinse off a site and into storm water drains. But by directing runoff downward, porous dirt, roots and greenery filter impurities so that water hitting below-grade aquifers is drip-purified.
One of my private clients in Boulder did just that. Their project is seeking LEED certification (gold), and the landscape designer, Khalana Gocken of Ethos Landscaping, designed gorgeous on-site features that retain water for natural filtration. French drains, swales and permeable pavers channel water from the roof to an on-site rain garden.
The upshot? The site requires basically no water, the native buffalo grass doesn’t need mowing, and the Xeric (low-water) plants are gorgeous.
FRENCH DRAINS & SWALES –French drains are pipes, sometimes porous and usually buried, laid over a gravel bed. As water runs through them, they seep water and divert it through a channel. And swales are low, vegetated channels that direct water yet also allow for ground absorption.
At this residence, the right side of the house is on the high side of the hill, and heavy rain runoff threatened to flood the client’s basement. So the builder raised the foundation walls two feet, and Gocken ran a French drain along that side of the house, diverting the water away from the basement walls.
RAIN GARDEN –The back of the lot was a low spot. Rather than in-fill it, Gocken designed a patio, and created a gorgeous rain garden behind it – a low spot to serve as a basin for rain runoff. She then planted it with beautiful native plantings that don’t need additional watering.
PERMEABLE PAVERS –Rather than pour a conventional concrete driveway, which would act as an impermeable channel for runoff, the client instead opted for stamped, colored pavers to allow the rain to be absorbed around the concrete pads.
Permeable paving is showing up all over the country, and the city of Chicago is even now re-paving alleys with pavement that allows water to flow through it rather than off it to inundate the city’s old storm water system. The stamped, colored pavers used here came at a premium, but basic concrete pads aren’t significantly more expensive than a solid pour.
Water, like energy, has a quantifiable impact on the cost to run a home. And while it hasn’t historically gotten quite the headlines energy has, that’s changing. NOW is the time to address it – micro and macro.
REAL ESTATE IMPACT: If you have low-water landscaping, quantify that benefit, and market it when you sell. In places with seasons, one rule-of-thumb calculation for irrigation needed per year is 18 gallons per square foot (non-drought), divided by 6 months. With this house, all grass, trees and shrubs total 2,073 square feet. So (18 x 2,073) / 6 = 6,219 gallons per month.
With the low-water features this client installed, that number essentially vanished. Your water utility can give you the right numbers for your climate zone and price per gallon.
If you’d like a .pdf of the landscape plan for this property, email me: [email protected]