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January 27, 2008
"Rain gardens" to help control runoff, reduce pollution
Several to be built near Wreck Pond

By TODD B. BATES
ENVIRONMENTAL WRITER
APP

Rain gardens capture and filter polluted storm water, keeping it from rushing into waterways and the Atlantic Ocean, according to experts.

And municipalities, homeowners and others in Monmouth County should build these shallow depressions - planted with native vegetation - to reduce pollution and recharge underground water supplies, according to experts.

"It's not only water quality, it's water quantity" that needs to be protected, according to William J. Sciarappa, agricultural and resource-management agent with Rutgers Cooperative Extension of Monmouth County.

The idea of rain gardens "sounds great and it makes a lot of sense," said Joe Mairo, 30, a Bradley Beach resident and biology teacher at Wall High School.

Sciarappa and Vivian Quinn, agricultural and resource-management program assistant, have been presenting rain garden seminars to promote the idea of building them.

So far, Monmouth County has very few rain gardens, Sciarappa said.

But the goal is to build demonstration gardens in 10 to 12 municipalities this year and perhaps motivate at least 100 homeowners to build them, according to Sciarappa.

A half-dozen rain gardens will be created on public property near polluted Wreck Pond alone, he said. Pollution from the pond's outfall, as well as concerns about its discharges, has resulted in most of the ocean swimming bans in New Jersey in recent beach seasons. The pond is between Spring Lake and Sea Girt.

"We're scouting right now the best places," including in Spring Lake, Sea Girt, Spring Lake Heights and Wall, Sciarappa said. Another rain garden is planned for the center of Manasquan. Belmar is planning one and a number of other towns have also expressed interest, the experts said.

Rain gardens, which also can prevent erosion and flooding, collect stormwater via rain gutters, curb cuts and swales, according to an e-mail from them. Plants and soil remediate the stormwater.

A rain garden can be located near downspouts to collect roof runoff, placed to collect water from the lawn and roof or sited along driveways and sidewalks, according to a Rutgers fact sheet.

The area for a rain garden must have a slope of between 1 percent and 10 percent, be at least 10 feet from a house foundation and be free of existing ponding, the fact sheet says.

"Good soil drainage is important," it says.

To conduct a percolation test, dig an 8-inch hole and fill it with water. After the water has drained, refill it and if the hole completely drains within a few hours, the area is suitable, the fact sheet says.

A demonstration rain garden was built at the Monmouth County Agriculture Building in Freehold Township, and it captures stormwater from the parking lot there, preventing it from flowing into a stream, according to Sciarappa and Quinn.

The garden is designed to capture up to 1 1/4 inches of rainfall from the 30,000-square-foot parking lot, Sciarappa said.

"But we've had a 2-inch rainfall . . . within 24 hours and it still captured all of that," so "we're very happy," he said. He calculated that the rain garden will collect 875,000 gallons in a year, he said.

An "average small-size homeowner rain garden" that covers 150 to 300 square feet will cost $2 to $4 a square foot if you build it yourself and four to six times as much if a landscaper does it, according to an e-mail from Sciarappa.

"Depending on the size and soil situation, a homeowner might expect to spend from $300 to $800 doing it themselves," the e-mail says.

An average, medium-size rain garden covering 500 to 1,000 square feet and built by a landscaper would cost about $3,500, while an average large-size demonstration municipal rain garden would cost $5,000, the e-mail says.

"Native plants that are suitable for wet sites," including with flowers, shrubs and trees, are used in rain gardens, Quinn said.

Rain gardens serve as habitat for birds, butterflies and beneficial insects, Sciarappa said.

The best way to deal with stormwater runoff is on a lot-by-lot basis, said Chris Obropta, extension specialist in water resources at Rutgers Cooperative Extension in New Brunswick.

Rain gardens enhance the landscape and look nice, he added. "It could be a huge thing for the state," he said.

County residents can call Rutgers Master Gardeners at the Monmouth County Agriculture Building at (732) 303-7614 to get free advice on how to build rain gardens, he said. The e-mail address is Mgarden@co.monmouth.nj.us