Welcome rainfall Sunday and Monday offered tangible proof that 50 people who labored hard in the Pittman-Sullivan Community Garden Saturday accomplished their task.
The goal for the weekend PermaBlitz event, sponsored by Green Spaces Alliance and neighbors who tend the near-Eastside garden, was to use permaculture and low-impact design techniques to capture rainwater and keep it in the park to water the many fruit trees, ornamental plants and seasonal vegetables.
“We have a limited number of people who are coming to the garden to water,” said Alan Neff, one of a small group of neighbors who created the garden six years ago with urging from dancer Jo Long, longtime leader of the nearby Carver Community Cultural Center, whose favorite hobby is gardening.
“It takes several hours to water with hoses,” Neff notes. “Being able to use the stormwater will benefit the plants. They’ll survive better and produce better during drought conditions.” With a smile, he adds, “It will let us enjoy the fruits of the garden without as much labor.”
The heart of the permaculture redesign for the Pittman-Sullivan Community Garden, conceived by Troy Dorman of Tetra Tech Engineers, are three bioretention basins (pictured below). These shallow bowl-shaped holes, about 15 feet in diameter and three feet deep, work to slow and treat stormwater runoff. As water enters the basins, it percolates through three feet of a mix meant to allow better infiltration into the ground: a 30-30-30 mix of sifted soil (to remove rocks), Poteet red sand, and compost.
Over breakfast tacos, Dorman laid out the plan to a group of enthusiastic volunteers wielding shovels, mattocks and garden forks.
Dorman pointed to Dakota Street that borders the park and to St. Mary’s Catholic Cemetery uphill across Dakota. Right now, he said, when it rains, free and valuable water is lost to runoff. It either flows downhill into the storm sewers, or it runs too quickly over the park ground to soak in. To add insult to injury, the water continues downhill to flood the baseball fields on the other side of the park.
“If we can get the runoff from Dakota Street to collect in our garden, it will lessen the impact downhill and keep the ball field from flooding,” Neff said. “It’s also filtering through the soil and feeding our plants.”
Dorman’s low-impact design was realized by 50 people and an earth-moving machine. First, they redirected the rainwater. On the previous day, Dorman and others had sawed out two-foot sections of concrete in a 40-foot section of curb separating Dakota from the garden. The openings, called “curb cuts,” guided the flow of rainwater from the street into the garden.
“When water from the cemetery uphill from the community garden runs down, it brings with it a lot of dirt, which is good for the garden,” Dorman says. “That’s better than having it flow down the street and into a storm drain.”
The second step was to capture the rainwater as soon as it enters the garden in the bioretention basins, filled with the soil mix, covered with bark mulch and outlined in rocks. The third was to direct the captured water along newly-dug swales (depressions in the ground) leading to planted berms (sloped beds) in the garden.
The proof their plan worked is in this picture (right). At a glance, it’s not impressive: a bunch of dirt, some of it covered with bark mulch, surrounded by rocks, with a curvy line of silt along the curb.
But that curvy silt line is the money shot. It shows that when the early week rains fell, the water did flow into the garden through cutouts in the curb. The silt shows the path the water took over the graded soil into the mulch-covered basins.
From there, all the action happens underground. But in time, the results could take many forms: bigger, healthier plants, a more robust water supply, and even social change.
“The main reason to do rainwater harvesting or bioretention to keep the water in your yard is that your plants grow so much bigger and better with rainwater than with tap water,” Dorman says. “You save water, get better plants and I think the fruits and vegetables grown only with rainwater taste better.”
Bryan Hummel, a pollution prevention specialist with Joint Base San Antonio, says permaculture directly benefits the Edwards Aquifer, one of San Antonio’s major sources of drinking water.
“All the plants and trees in this garden are now going to be gravity-irrigated with rainwater instead of hand-irrigated through a hose with water that has to be treated and pumped out of the Edwards,” Hummel explained.
Hummel maintains the area doesn’t really have a water shortage. “We just get so much water at one time that it runs off before we can recharge our aquifer,” he says. The fix, he contends, is in good land management.
“If we can slow, spread and sink the water into our landscapes, we can recharge our aquifer,” Hummel said.
Angela Hartsell, community gardens program manager for Green Spaces Alliance (GSA), hopes the Pittman-Sullivan garden will be “a demonstration for low-impact design for the city.” The non-profit organization whose goal is to preserve green spaces in urban areas, provided a $7,000 grant to develop the garden in 2008.
“We’re hoping developers will come to visit the garden to see how it’s working and that it’s beautiful,” she said.
GSA invites volunteers to join the team again on Saturday March 21 from 9 a.m. – 4 p.m. and Sunday March 22 from noon to 3 p.m. Also on Sunday, Michelle Gorham of GSA will give a lesson on plant selection and plant guilds from 2:30-3:30 p.m. Click here for details on how to volunteer.
For guidance on how to build a rain garden, complete with videos and plant lists, visit the San Antonio River Authority’s website.
*Featured/top image: Volunteers dig a basin to change the flow of rain water. Photo by Karen Stamm.