Green Water Recapture Systems
Today’s irrigation customer is more environmentally savvy than the customer of 20 or 30 years ago. The burgeoning emphasis in our industry on sustainability has stuffed a whole mess of new concerns into the mind of the consumer. Can we include a green roof? What do you think about permeable pavers? Can we design green spaces to soak up excess stormwater?
Customers didn’t ask these questions 20 years ago. These determinations were left to the enterprising contractors.
But the game has changed. Terms like “stormwater management” and “water recapture technology” have made their way into the consumer vernacular. Customers want to know about best management practices for controlling stormwater runoff and reusing it. Many are likely to at least inquire about LEED certification.
EPIC (Environmental Passive Integrated Chamber), the water management system developed by Firestone, is an emerging technique for grappling with this growing area of concern.
Before the advent of EPIC, there was a water management system being used exclusively on athletic fields called Prescription Athletic Turf (PAT). PAT was very similar to contemporary water recapture systems, but never caught on in the same way. This failure had more to do with timing rather than anything else.
But in today’s water-conscious world, water purveyors will ask developers, facility managers and field managers of new commercial developments where the building is going to get its water. Not only in six months—they want to know where a new building is going to get its water in sixty years. The market is primed for an intuitive method for reusing wastewater.
In a traditional water management scheme, runoff is diverted away from the site as efficiently as possible. Elaborate systems of gutters and drains take advantage of the natural grading on a site, directing stormwater into mixed or separate sewer systems.
Irrigation contractors used to treat stormwater runoff like a pollutant. That treatment made intuitive sense; excess stormwater mixes with dirt and chemicals on the surface and can even become contaminated with sewage. The problem is that excess stormwater, after significant rainfall, has the potential to reach larger bodies of water—a serious environmental hazard.
By collecting, filtering, retaining and redistributing water below ground, EPIC changes stormwater from a pollutant to a resource.
How it works Green water recapture systems are essentially simple because they take advantage of the laws of physics to irrigate passively. They have been implemented on such diverse areas as lawns, playing fields, and even raised beds.
Every EPIC system installation begins with an excavation, unless the system is being installed in a raised bed, like a backyard planter bed. You typically excavate to a predetermined depth, usually 36 inches, and then level the base of the excavated area.
Once the base is leveled, you would top it with a geotextile or rubber liner. The purpose of the liner is to create a waterproof catchment area wherein the excess stormwater can pool. This section becomes a reservoir of sorts.
PVC pipes, the heart of the system, feeds water from this reservoir into collection tubes that act as the main storage utility. You can either capture rainwater as it falls, or divert stormwater runoff into your reservoir using gutters and culverts. With smart engineering, you can design a recapture system that appropriates a huge percentage of your site’s wastewater.
What you now have is a system for trapping and pooling excess stormwater onsite. The next step is to integrate a filtration medium that collects pollutants, like nitrates and phosphates, that can actually be used as nutrients for the vegetation aboveground. After filtration, the remaining water is stored for future reuse or reintegrated back into the soil.
The whole system has zero moving parts. Gravity and capillary rise are the only forces necessary to move water up from the collection tubes and through the filtration medium to provide subsurface irrigation.
There you have it—water filtration, subsurface irrigation and stormwater management in one sustainable package.
Sand is the most common filtration medium, according to Christa Petzke, east regional business manager at Firestone Specialty Products LLC. She says, “The top three inches of that sand provide the only filtration system you need; it’s very long lasting. With a project where you’re running rainwater through– actually, any kind of water that’s not very ‘gray,’ you could expect those top three inches to endure without need for replacement for a decade or more.”
Translation: the system isn’t just eco-friendly, it’s durable as well.
While sand provides the standard filtration medium, Petzke says there are many more options for the top layer of an EPIC project. Grass offers the most flexibility. In the event that the filtering layer of sand needs to be removed and replaced, a new lawn can be grown in as little as 45 days. But native plants are also popular, as well as artificial turf and even porous, interwoven pavement.
Greening your irrigation project
The system debuted as a commercial irrigation technique, but has since made the jump to smaller sites. On the residential side of things, Petzke recently put one in at the bottom of a raised vegetable bed in her own backyard.
“Putting in the EPIC system before the bed was filled with soil meant I didn’t have to do any excavating,” she said with a laugh.
Systems like Petzke’s are especially user-friendly, because the customer can actually see how much water has been collected. If the water level ever falls too low due to lack of rain, you can physically see when it’s time to break out the hose. The catch is that this type of system only works for an aboveground project like a raised bed.
On the commercial side, the University of Minnesota was famously successful for installing an underground water recapture system at their TCF Stadium, new home of the Golden Gophers. Among the stadium’s many green building designs was an eco-friendly, stormwater management system.
By capturing rainwater in a comprehensive underground filtering system, the University of Minnesota achieved a 50 percent reduction in the amount of potable water used for landscape irrigation, and a 30 percent reduction of indoor potable water use. Perhaps even more impactful is the sheer volume of polluted stormwater that TCF Stadium’s green design prevents from reaching the Mississippi River every year.
The stormwater recapture and filtration system at UM stores and treats water from a 3.75-acre watershed and maintains an underground capacity in excess of 60,000 gallons. These numbers were impressive enough to make the TCF Stadium the first collegiate or professional football stadium to earn LEED certification from the U.S. Green Building Council.
“From a sustainability standpoint, we’re able to reduce our need–and related costs–for irrigation because the roots from the turf pull water up through the sand profile,” said the land care supervisor for UM. “We also save money by eliminating the disposal of water down the storm sewer.”
For contractors looking to offer more green designs, water recapture systems like EPIC are a glimpse of the future. Stormwater management standards throughout the country are getting more stringent. If you can offer a system that is as simple from an engineering standpoint as it is durable, then you’re already ahead of the curve.