Water run-off can take several forms. In more rural areas, rain and snow land on farms and carry fertilizer and other pollutants with them to local sewers and, ultimately, water ways. In more urban areas—which make up about 97 percent of Montgomery County, according to 2010 Census figures—the main source of run-off pollution is pavement.
We’re not going to get rid of pavement any time soon. But what if we could stop run-off pollution by stopping run-off itself?
That’s the idea behind permeable pavers. Traditional or impervious pavements—asphalt and concrete are in this category—don’t absorb water. Permeable pavers let water run through them. More run-through, less run-off. County residents and businesses that install permeable pavers may be eligible for significant rebates through the Montgomery County RainScapes program.
“The water drains through the pavement into the base of the pavement where it is filtered and infiltrated,” explained Ann English, manager of the RainScapes program.
The technology behind permeable pavement is complex in theory, but relatively simple in practice.
“When pavers are installed, they have small gaps between them,” said David Smith, technical director of the Interlocking Concrete Pavement Institute based in Chantilly, Va. “Because they have the spaces in them, they can store water. Instead of water running off, it gets infiltrated.”
Generally speaking, there are three main types of permeable pavers:
Although it is not yet officially approved for rebates by the RainScapes program, a new option gaining attention is a substance known largely by its brand name, Flexi-Pave. This substance is similar to pervious concrete or asphalt, but is made largely from recycled tires and thus has a more rubberized, softer surface. It provides optimal filtering in parking lots, sidewalks, playgrounds, and other surfaces and has been used successfully around trees in sidewalk settings. As with the permeable interlocking concrete pavers. Flexi-Pave would need to be designed with a deep enough base to handle any stormwater directed to it.
The truth of the matter is that while permeable pavement is initially more expensive to install (costs vary, so it’s not a bad idea to get a few different estimates), in many cases the RainScapes Rewards rebate can cover the difference in price between the cost of a traditional paver installation and a permeable paver installation.
The good news for Montgomery County residents is that RainScapes Rewards rebates are available. When projects meet the program’s eligibility requirements for the rebate, residents or business owners can receive $4 per square foot of impervious area treated or $1,200 per project (whichever is greater), with a 100-square-foot minimum and total maximum rebate amount of $2,500 for one property for permeable pavement or porous concrete installation that replaces existing impervious pavement. (If you just want to eliminate pavement, there is another rebate of $2-4 per square foot for pavement removal.)
All permeable pavement projects for the RainScapes Rewards program must be installed by a trained professional with permeable pavement installation credentials.
In addition, those who install permeable pavers are eligible to apply for a credit off their annual Water Quality Protection Charge, which is assessed during annual property tax bills. Residents and business owners must apply separately for the tax credit after getting a Rewards Rebate.
Before getting started, assess whether your driveway or parking lot meets the RainScapes program’s eligibility requirements.
“Determine whether your site is appropriate,” Smith advised. “You need a house that’s a little higher than the road. You need some slope. But if you have that you can probably take advantage of the rebate and the [tax] credit.”
Scott Harris is a freelance writer who lives in Montgomery County and covers the environment and other topics. Scott may be reached at firstname.lastname@example.org.