SANDOWN – While stormwater runoff and the erosion and pollution it can cause might seem like a problem solely in the domain of big cities or box store parking lots, Sandown residents had a chance last week to learn how they can do their own small part to mitigate its effects on their prop- erties and the town at large.
Stormwater runoff is ex- actly what it sounds like rain or melting snow that does not soak into the ground. When the rain falls, all of the impervious surfaces it hits from driveways to roofs to a well manicured lawn send the water rushing downhill instead of staying put, as it would in a forest, field or other natural landscape. That run off not only adds to already swollen streams and rivers, but carries with it nutrients and pollutants.
In New Hampshire, stormwater contributes to over 80 percent of surface water quality impairments, according to the state Department of Environ- mental Services (DES). In addition to pollution, that excess runoff is stressing municipal infrastructure like culverts and bridges. Sandown has had numerous road and culvert repair projects handed to taxpayers as the result of heavier rainstorms and flooding in recent years.
The argument goes that taxpayers could avoid the hefty repair bills if they did their part upstream. During a forum at the town hall on Feb. 20, DES’s Jillian McCarthy explained that if each homeowner helped keep the rain that fell on their properties, it would go a long way to reducing both infrastructure damage and pollution. McCarthy is the Non- point Source Specialist with DES’s Watershed Manage- ment Bureau Though the typical homeowner with a couple of acres might not think they add to stormwater runoff, they do.
McCarthy wrote the DES’s New Hampshire Home- owner’s Guide to Stormwater Management and using it as a guide, she led attendees Feb. 20 through a number of easy additions to their properties that would go a long way to stopping runoff. McCarthy suggested that homeowners assess their property with an eye to poten- tial problem areas. These include erosion under a downspout, channels that water carves out during rain storms, or erosion around a driveway.
Next would be to create a project plan and select the Best Management Practices or BMPs to mitigate the problems.
She had nine suggestions to manage storm water on a homeowner’s property.
A dripline infiltration trench collects runoff from the roof to store it as it soaks back into the ground. A driveway infiltration trench has the same purpose in a different location. A dry well is a simple solution, explained McCarthy, saying, “It’s pretty much a big hole in the ground filled with stone, but it’s incredibly effective.”
Infiltration steps slow down and let rainwater infiltrate in sloping areas used for walking paths.
Pervious walkways and patios allow the rain and snow that falls on such areas to trickle into reservoirs and infiltrate into the ground again. A rain barrel is a popular solution to collect the rain that falls on the roof, said McCarthy. The barrel is set up either at the end of a downspout or in an area of the roof that collects water. The water can then be used to water the garden.
Rain gardens are also popular, said McCarthy. Instead of building up the soil, as is the case in most gardens, a rain garden calls for a bowl shaped planting area that catches more water. A vegetated swale is a shallow channel that slows runoff and directs it into an area where it can infiltrate back into the ground. Plantings in swales can also help remove pollutants and trap sediment.
A water bar intercepts water traveling down walkways and other such areas to divert it into stable vegetated areas before it can leave the property. The guide comes with instructions on how to measure the effectiveness of the BMPs installed.
“We know that all of our properties are contributing a small amount, so changes like these can make a big difference. But it will take a lot of these changes,” said McCarthy. To help spread the word, DES has started a program where it partners with local organizations in a voluntary effort to stem runoff. It’s called the Soak Up the Rain program and DES is running pilot programs with three groups this year. The goal is to train leaders in the community on how to iden- tify areas that need BMPs and how to install them. The groups are also hoping to gauge their success at the end of the year.
McCarthy said DES is generally seen as a regulatory agency, but the organization is excited to move forward with a voluntary action plan. McCarthy likened the effort to recycling, something that years ago was not the norm. Now most people take it for granted that they need to separate their trash. “Our goal is to make this as common as recycling,” said McCarthy.To access an electronic copy of the Homeowner’s Guide to Stormwater Man- agement, visit des.nh.gov and click on the stormwater program tab.