Coastal Heritage Magazine
Slowing Stormwater: Improving Water Quality by Imitating Nature
Innovative development practices and construction products are allowing stormwater to be filtered on-site and preventing pollution from reaching waterways.
Swash Stew. Along an Horry County beachfront, children play in a swash—a shallow tidal creek—contaminated by stormwater runoff. Photo by Jackie Taylor.
Coastal Heritage Magazine
Volume 22 – Number 4
John H. Tibbetts
Slowing Stormwater: Improving Water Quality by Imitating Nature
On summer days along the Grand Strand, small children play in the quiet, shallow tidal creeks called swashes that often spill over the beachfront and capture high tides. Kids and their mothers are drawn to swashes, which are more tranquil than the rough surf.
Bacteria, unfortunately, contaminate the creeks.
“When I see children in swashes,” says Jackie Taylor, a water-quality official with Horry County Stormwater Management, “I point to the warning signs, which are clearly posted along the beachfront, and explain to their mothers about all of the stuff that runs in there.”
From roads and other urban surfaces, rain captures a nasty brew of oil, grease, pet and wildlife waste, sediment, pesticides, fertilizers, and heavy metals. The stormwater runoff and untreated contaminants then flow into Grand Strand swashes.
“Bacteria in the swashes can cause gastrointestinal problems, ear and eye infections, respiratory problems, and urinary-tract infections,” Taylor says. “A lot of times the mothers just ignore me when I tell them. They don’t believe me. As long as the water’s clear and it’s not smelly, they don’t associate it with pollution. Because the tides come in, they think that the swashes get cleaned out. But the tides just slosh the contaminants back and forth a little bit; they don’t really go anywhere.”
Polluted swashes are just one example of impaired water quality along parts of America’s coastlines. Each year, elevated bacterial counts from storm-water runoff and other sources have caused potential health threats along beachfronts. The S.C. Department of Health and Environmental Control (SCDHEC) monitors water quality at 118 sample sites along the state’s coastline and issues public-health advisories when bacterial counts are elevated in the surf.
In an effort to clean up many of the nation’s neglected waterways, the Environmental Protection Agency (EPA) has recently required thousands of small and mid-sized communities, including Horry County, to establish tougher measures to manage stormwater runoff.
The new rules are complex, and local officials say it will take time to learn how to implement them. Already, though, the regulations are proving to be expensive, and there is scant federal or state money available to help communities. Localities must identify pollution sources, which won’t be easy, and find cost-effective solutions.
In response, a number of local officials, environmentalists, developers, architects, engineers, and scientists are calling for innovative “green-infrastructure” practices that can improve water quality in new developments and redevelopments, while saving money over the long term.
The idea is to absorb and treat rainwater on-site now rather than try to fix pollution and flooding problems later by building costly “gray infrastructure,” including extensive pipes, storage systems, and water-treatment plants.
Advocates of green infrastructure want to stem the flood of polluted stormwater pouring into rivers and creeks. “The faster that water moves across the surface, the more pollution you see in local waterways,” says Jeff McNesby, director of the Town of Bluffton Department of Environmental Protection. “Pollution rides stormwater sediments into the river, and we want to slow that down.”
On the Cover. S.C. Sea Grant Consortium researcher Daniel Hitchcock (right) and Anand Jayakaran, both of Clemson University, measure a stream channel’s depth and width in an effort to understand the baseline hydrology of a Georgetown County land tract called Bannockburn Plantation. The scientists are studying the tract’s hydrology before, during, and after construction as part of a larger effort to test and improve low-impact development practices for coastal areas with shallow water tables and flat topography. Photo by Wade Spees.
On a regional scale, some communities have already invested in green infrastructure by conserving large tracts of watersheds with outright purchases or conservation easements. Protecting land allows storm-water to be treated by natural filtration and, in the process, helps assure that clean water is available for drinking, swimming, fishing, and other uses.
But when development is going to occur, networks of smaller-scale, green efforts are important. Low-impact development (LID) practices, which supplement or replace traditional ways of managing stormwater, include:
- Planting and maintaining vegetated buffers along waterways. Trees and plants help to absorb pollutants, filter runoff, and stabilize banks.
- Installing porous pavement. These surfaces allow runoff to infiltrate into the subsoil where cleansing can occur.
- Building bio-retention landscaping features such as swales, rain gardens, and pocket parks. These treatment systems, which use natural processes, primarily have been located in parking lot islands but can also be sited in community areas or individual yards.
- Constructing stormwater wetlands. They may be dry or boggy at times but can fill with stormwater after rainfall and allow potential pollutants to be filtered.
- Installing rain barrels and cisterns that save rainwater, and reorient gutter down spouts to send water onto lawns instead of pavement.
- Installing green roofs, which allow soil and plant materials there to reduce overall runoff.
- Concentrating homes in a compact portion of the development site in order to provide open space and natural areas elsewhere on site to filter rainfall.
Native Buffer. Most stormwater ponds are not specifically designed to control pollutants such as nutrients, which can stimulate harmful algae. Norm Shea, director for Lakes Management for the Kiawah Island Community Association, says that planting Spartina alterniflora along the bank of this stormwater pond can soak up nutrients and herbicides that run off lawns. Photo by Wade Spees.
“There haven’t been a lot of low-impact development projects in South Carolina yet,” says S.C. Sea Grant Consortium researcher Daniel Hitchcock, a biosystems engineer at Clemson University. “This is all brand-spanking new here, but I think developers and engineers are catching on.”
The Trouble with Ponds
The traditional way of managing stormwater in new developments just isn’t working, experts agree. For decades, engineers have typically designed detention ponds—giant divots in the ground—to capture rainwater runoff for a period of time before it’s discharged into a waterway. Ponds can effectively retain some pollutants such as sediments and heavy metals that settle out on the bottom.
Most ponds are not specifically designed to control pollutants such as nutrients and bacteria. Nitrogen overloads in detention ponds can make them incubators for certain harmful algae, which get released into adjacent waterways.
Over decades, ponds fill up with sediment, which should be dredged to remain effective in treating contaminants and managing flooding. Under current state regulations, property owners and homeowners associations have responsibility for maintaining ponds in new housing developments, though few property owners likely realize when or how to go about it.
“In 20 years of stormwater management, the biggest challenge has been the maintenance of detention ponds,” says Joe Fersner, a former state regulator and now an engineer who works for Woolpert, Inc., in its Mount Pleasant office. “Their maintenance just isn’t easily enforceable.”
There are thousands of stormwater ponds in coastal South Carolina, and regulators lack adequate staff resources to check on them all.
“We do conduct compliance inspections on maintenance of ponds,” says Shannon Hicks, manager of stormwater and state certification at the S.C. Department of Health and Environmental Control–Office of Ocean and Coastal Resource Management (SCDHEC–OCRM). “However, conducting inspections on all ponds is extremely demanding on our resources. And the public education that’s required is a real challenge. We hope to increase the number of inspections through enhanced staff resources and coordination with local governments.”
The development community has come to rely too heavily on ponds. “We’ve expected ponds to be the end-all and be-all of stormwater management,” says Denise Sanger, assistant director for research and planning with the S.C. Sea Grant Consortium. “But we can’t expect only one practice to solve the problem. We need a combination of measures to achieve success.”
That’s why innovative developers and localities are employing various treatment options to supplement or even replace ponds.
Now, two communities in coastal South Carolina—a new green neighborhood called Oak Terrace Preserve in North Charleston and the rapidly growing town of Bluffton—have installed low-impact technologies that capture rainfall and treat it by filtration onsite, as close to where it falls on the ground as possible. In this way, rainfall is filtered before it ever reaches detention ponds or waterways.
Sprawl. Intensive waterfront development, like this condominium project along the Intracoastal Waterway, has increased concern about stormwater runoff from parking lots and yards. Photo by Wade Spees.
This strategy is part of a revolution in landscape design and stormwater engineering. In the past, engineers usually thought only about water transport and quantity, says Hitchcock. Engineers still have to manage quantity, he adds, but now they also need to improve water quality by using innovative systems that imitate natural processes.
Meanwhile, though, communities up and down the South Carolina coast face complex water-quality challenges in existing developments. Take the Grand Strand’s swashes. Local people and tourists have been swimming in these creeks for generations, but rapid growth has overwhelmed the waterways.
“When I was a little kid, that’s where we played,” says Taylor of Horry County Stormwater Management. “You were out of the waves, and Momma could see you. Water quality wasn’t good then, but now it’s really, really, really loaded with bacteria. The population has grown along the coast and there’s a lot more development that adds impervious surfaces.”
Impervious surfaces? She’s referring to roads, bridges, sidewalks, highways, parking lots, and driveways made of conventional asphalt or concrete. Also, roofs.
Conventional pavements are manufactured with high concentrations of relatively fine materials of various sizes. These impervious—or dense— paving surfaces lack the tiny spaces, or voids, where rainwater can enter and filter through to the ground below.
When it rains in a meadow or forest, some of the precipitation filters into the subsurface where soils and beneficial microbes cleanse it. Eventually the water gravitates into the aquifer, recharging deep groundwater, or it seeps slowly downslope to recharge rivers, lakes, salt marshes, and the ocean. Another portion of the rainfall is absorbed by plants and transpired back into the atmosphere. And some runs off the landscape, though slowly and steadily in most cases, into waterways.
Typical suburban development, by contrast, transforms this water cycle. Conventional developers cut down water-absorbing trees and other vegetation, compact soils with heavy equipment, and install acres and acres of dense paving surfaces. During a one-inch rainfall, the volume of water coming off an acre of impervious pavement is 10 to 20 times greater than that from an acre of grass, according to a number of scientific studies. Stormwater also moves far faster across impervious surfaces than across those of natural areas.
It doesn’t take a lot of conventional concrete or asphalt to harm a small waterway’s biological life, scientists say. Adding impervious surfaces to just one-tenth to one-fourth of a natural watershed’s acreage can impair local streams, perhaps permanently.
After development, “90 percent of the water that once was in the ground now remains on the surface,” says Derek Booth, a geologist, civil engineer, and president of Stillwater Sciences, a consulting company with offices in California and Washington state. “You’re denying water to the subsurface, and that’s a massive alteration of ecological conditions” with implications for water storage and water quality. The subsurface is a crucial storage area, and underground soils and microbes are effective water cleansers.
Rapid stormwater runoff from impervious surfaces—and the contamination it carries—is the most significant and immediate threat to many coastal waterways in the Southeast, according to Craig Hesterlee, a watershed coordinator with the EPA Atlanta regional office.
One quarter of a million acres in the United States are either paved or repaved every year. And as much as 65 percent of the total impervious cover across the American landscape consists of “habitat for cars”—highways, bridges, streets, parking lots, and driveways, according to the nonprofit Center for Watershed Protection, based in Ellicott City, Maryland.
Over the past several decades, then, auto-dominated sprawling development has helped degrade nature’s beneficial underground water-storage and water-cleansing system, scientists say.
Americans meanwhile have increasingly purchased second homes, retirement homes, and vacation condominiums along the banks of the nation’s lakes, streams, rivers, and estuaries. New housing and tourism developments, which slather landscapes with densly paved surfaces and close-cropped lawns, are often built as close to the waterways as possible, taking down healthy buffering vegetation that disrupts high-value views.
“Development is following water frontage in almost every watershed,” says Cal Sawyer, a water-quality specialist with the Clemson University Extension Service.
The American love affair with waterfront living and the automobile is damaging the biological health of the very places where newcomers have relocated to admire. People are rushing to live along waterfronts, though “it’s clear that separating development from the water is the best thing for water quality,” says Greg Jennings, a water-resources engineer at North Carolina State University.
Coastal areas are at special risk because of the intensity of population growth and development there. About 3,500 new residents move to U.S. coastal counties every day, building homes and businesses that add more dense surfaces.
“Does the public understand that we’re losing water-quality characteristics along our coasts, and we’re not likely to get them back?” asks Jennings. “We’re dealing with a crisis situation with impervious surfaces and hydrology along the coast.”
Tougher Federal Rules on Water
Thousands of small and mid-sized communities around the country have begun taking part in the nation’s second generation of water cleanup.
The first generation began with the Clean Water Act, which was passed in 1972. Over the next two decades, EPA, states, and localities largely focused on addressing contaminants in discharges from “point sources,” particularly municipal treatment plants and industry. EPA has required that such dischargers apply for federal or state permits for contaminants they send into waterways.
Overall, these efforts have been successful, experts say, in preventing contaminated discharges from point sources. But runoff and many other diffuse sources of contamination—called nonpoint-source pollution—have continued to make waterways unfit for drinking, swimming, and other uses.
In the early 1990s, federal regulators began cracking down on nonpoint sources. First, EPA required that larger cities and major construction projects apply for National Pollution Discharge Elimination System (NPDES) permits for the contaminated runoff they produce and establish plans to manage it.
Since 1999, some 3,500 smaller municipal and county governments also have had to abide by these rules, although it wasn’t until 2007 that many South Carolina localities were required to implement them.
“It affects almost every local government now,” not just the larger cities, says Bruce K. Ferguson, director of the University of Georgia School of Environmental Design. “They have to pay attention to this issue.” Since EPA required larger metro areas to fix stormwater pollution, there has been a surge in innovative solutions to this problem. “It has been the hand of regulation that has caused us to learn more about stormwater over the past 10 years.”
Seventy South Carolina local governments—25 in coastal counties— were called on to create plans to address nonpoint-source pollution by September 1, 2007. In coastal counties, SCDHEC–OCRM reviews the plans and issues NPDES permits. Still, a number of localities are appealing to opt out of this requirement.
Some major cities have invested huge sums to manage runoff pollution. Boston, Chicago, and Atlanta have substantially upgraded or built new gray-infrastructure facilities to address stormwater. These facilities include conventional piped systems, giant tunnels to hold runoff, plus additional capacity in wastewater plants to treat it. But this kind of traditional infrastructure is very expensive to build, operate, and maintain. Storage tunnels alone can cost hundreds of millions of dollars.
A storm-drain marker in Beaufort County. The county identified and marked more than a thousand drain inlets in a project funded by the S.C. Coastal Community Initiative, a small grants program established by the S.C. Sea Grant Consortium. Photo by Kathryn Madden.
Now add intense droughts to these pressures on the nation’s water supply. The Southeast, for instance, suffered through a long drought—1998 to 2002—and it had still not recovered when another one struck in 2007.
At first glance, the Southeast shouldn’t have water troubles; it’s relatively wet overall. But explosive population growth, a changing climate, and suburban sprawl could increasingly make fresh water scarcer where and when it’s needed in the region. It’s becoming more difficult to provide clean water at a minimum cost at the right time and in reliable volumes to thirsty consumers.
In 2007, EPA and four national environmental groups signed an agreement to promote green infrastructure as an environmentally preferable approach to managing stormwater. The U.S. Conference of Mayors has also strongly endorsed it.
Even so, green infrastructure hasn’t been widely embraced, according to Nancy Stoner, director of the Clean Water Project at the Natural Resources Defense Council, an environmental organization based in Washington, D.C. In most cities, green practices are “the garnish, not the meal,” she asserts.
Why? This is a new, rapidly changing field, and engineers rarely take risks on something unknown or unproven. Many developers are wary that green, low-impact practices could cost them time and money in the short run and expensive maintenance in the future. Few contractors know how to install the newest green materials. Many regulators and local officials are unfamiliar with low-impact development practices.
“Each aspect of low-impact design has economic, regulatory, and engineering obstacles to overcome,” says Hitchcock of Clemson University. “It’s just that more testing and demonstrations are needed. And any information about economic benefits of low-impact design should be shared with other professionals in this field.”
The development community needs better on-the-ground information about which of these practices are cost-effective, says Eve Brantley, who leads watershed-education programs for Auburn University Cooperative Extension Service. It’s essential to address developers’ bottom-line concerns. “We need good examples to show developers,” she says. “Because they will ask, ‘what is this and how can it benefit me?’ ”
North Charleston’s Experiment
Driving along Montague Avenue near I-26 in North Charleston, you might wonder how block after block of worn bungalows and run-down industrial buildings could attract major investors to the lowcountry’s most ambitious redevelopment effort.
Yet here in North Charleston, the Noisette Co. and the city have created an ambitious master plan to guide rehabilitation of some 3,000 acres of neighborhoods and commercial corridors, including the former Navy base on the Cooper River.
The city and the Noisette Co., moreover, are developing a new 55-acre neighborhood called Oak Terrace Preserve on a site where dilapidated housing for World War II workers once stood. Attractive single-family homes—in modest but elegant styles—are being built amongst giant live oak trees. And now, developers, engineers, and scientists are collaborating to implement, study, and showcase various low-impact development practices that could be used elsewhere in the future.
In the previous neighborhood, stormwater would pour untreated into a nearby creek. But now the city and the developers are committed to using green practices to protect water quality. Their goal is to establish a number of “treatment trains” within the neighborhood. A treatment train is a series of linked landscaping features, all of which have water-absorbing or filtering capacity.
Oak Terrace Preserve’s alleys and sidewalks, for instance, are made of permeable material called Flexi-pave,TM a blend of recycled rubber and pebbles, which allows water to filter through into the ground.
Learning Curve. Flexi-paveTM (top), a porous paving material, allows water to filter into the ground, reducing stormwater runoff. But if it’s installed before a construction site is landscaped, loose sediments (middle) can run off and clog the material (bottom). To assist contractors and developers who use new or unfamiliar low-impact building products, S.C Sea Grant Consortium scientists are detailing “lessons learned” during construction of Oak Terrace Preserve, a sustainable neighborhood in North Charleston. Photos by Wade Spees.
To absorb stormwater from roofs and lawns, contractors are building rain gardens adjacent to homes. Rain gardens are shallow depressions in the earth that allow rainfall to percolate and trap contaminants. Contractors install porous soils that allow water to filter into the subsurface. Native grasses, shrubs, or trees are planted to absorb water. And pollution-consuming bacteria live within a thin layer of mulch below the surface.
When it pours, rain gardens in Oak Terrace Preserve are designed to take in larger volumes of stormwater than they can treat. Underground pipes capture the overflows, which run downhill into specially constructed swales along roadsides. Most road runoff ends up in swales, which also have native, water-absorbing plants and engineered soils. These swales are designed to hold and treat by filtration the first two inches of runoff from streets.
A series of underground pipes beneath swales takes further overflows downhill into pocket parks, or deeper vegetated basins where sediments and other pollutants settle out on the bottom.
Overflows from pocket parks are carried via underground pipes to the last site in the treatment train: a “forebay,” which is a small detention pond. Once stormwater has been treated again there, it seeps into a natural forested freshwater wetland, before eventually entering Filbin Creek.
Finally, Oak Terrace Preserve’s underground piping system is perforated, allowing some overflows to filter deeper into soils along its path and thereby providing supplemental stormwater treatment.
S.C. Sea Grant Consortium researchers Dwayne Porter and Lisa Vandiver, of the University of South Carolina Department of Environmental Health Sciences, are testing water flow and contaminants at the outflow of the neighborhood’s treatment train.
They are similarly testing water flow and contaminants from a nearby neighborhood, which has an older, traditional curb-and-gutter storm-water system, of comparable size, soils, and slope. This study could show whether the Oak Terrace Preserve low-impact, on-site treatment system provides improved water quality compared to that of a traditional stormwater system.
Vandiver and her colleagues also plan to identify and examine the obstacles (design, construction, permitting, cost, maintenance) to implementing the low-impact techniques.
When built out, the development will have an elaborate system to manage rainwater, a complexity that has already challenged contractors, says Vandiver. The low-impact techniques are so new and unfamiliar, she says, that it requires a period of trial and error to find the best methods of constructing and installing them. The scientists will provide a summary of the “lessons learned” from Oak Terrace Preserve, which will assist developers and engineers to avoid these problems in the future.
Eco-Conscious. Pet waste is a major stormwater pollutant in America’s waterways. Photo by Wade Spees.
Bluffton’s New Approach
Eight years ago, the town of Bluffton, along the quiet May River in Beaufort County, was a sleepy village of 1,200 people. Since 2000, the town’s population has already grown 10-fold, and tens of thousands of additional residents are anticipated to arrive over the next decade.
Town officials and residents have become worried about development impacts on the May River, which is designated a state outstanding resource waterway by the S.C. Department of Health and Environmental Control. The river and surrounding waters are some of the few remaining pristine shellfish-harvesting areas in the southern coastal counties of South Carolina.
“The level of pollution in the river has appeared to increase because of development in the past few years,” says Jeff McNesby, of the Bluffton Department of Environmental Protection. “People have been paying attention to the May River for some time, and they are aware that it’s a resource that’s extremely valuable and is in danger of being lost. Now, another 50,000 people are expected to move to Bluffton, so how can we protect it?”
Proactive. Standing near Heyward Cove, which flows into the May River, Jeff McNesby, of the Town of Bluffton Department of Environmental Protection, says, “Our stormwater ordinance is among the toughest in the Southeast.” Photo by Wade Spees.
In 2007, the town passed a stormwater ordinance that requires a linked series of treatment systems—three in most projects—to filter runoff pollutants in all new development projects. Some of these treatment systems include orienting roof downspouts onto lawns instead of pavement, installing porous surfaces, and creating stormwater wetlands with vegetative buffers.
Half of the commercial parking spaces in any Bluffon project must be built with material—such as porous pavement—that allows water to soak in. If a project includes more parking spaces that the town requires, all additional parking materials must be porous.
Developers, moreover, are required to test turbidity—the amount of sediment in the water—during and after construction. Only small increases are permitted from pre-development levels. New projects must test water-quality indicators for up to three years after construction. Development projects failing to meet minimum state standards at least 20 percent of the time would have to fix the source of the problems.
“We make (all development projects) infiltrate their first inch of stormwater runoff,” says McNesby. “That’s the first flush, and it’s where the majority of the pollutants are.”
Federal and state regulators are pointing to Bluffton as a municipal government in South Carolina that’s leading the way in protecting water quality.
Says McNesby, “The best-management practices and low-impact development practices that we’ve been hearing about—we’re making them requirements in Bluffton. We’re sending a message. If you’re going to develop in Bluffton, if you’re going to live in Bluffton, you have to help protect the May River.”
Coastal Development Can Impair Headwater Tidal Creeks
These tributaries are especially sensitive to stormwater pollution.
Animals living in small headwater tidal creeks within developed coastal watersheds are especially harmed by runoff pollution, scientists have recently learned. Narrow, shallow, containing little water during low tides, headwater tidal creeks are the “first-order” tributaries that flow into larger coastal creeks and rivers that serve as the primary hydrologic link between uplands and estuaries.
Denise Sanger, a marine scientist and assistant director for research and planning with the S.C. Sea Grant Consortium, and Fred Holland, director of the National Oceanic and Atmospheric Administration Hollings Marine Laboratory in Charleston, have examined 50 headwater tidal creeks in the lowcountry. These creeks are important nurseries and refuge for small estuarine creatures, which look for places to feed and hide from larger animals.
“The smallest and youngest of the fish, shrimp, and crabs live in the headwater creeks,” says Sanger. “These are biologically productive places where there are bountiful food sources for the little guys. They can often stay away from predators there and they don’t have to compete as much with the big guys.”
The scientists gathered data from creeks in three watershed categories: high-density urban development, moderate-density suburban development, and forested areas.
In watersheds with higher levels of development, stormwater contaminants and abrupt freshwater pulses after rainfall events have contributed to significant changes in animal communities, the scientists found.
Only those bottom-dwelling animals (a food source for fish and crabs) known for hardiness were found in headwater creeks adjacent to development. And, within these developed watersheds, there were fewer shrimp.
A major conclusion from this research is that headwater creeks, important nurseries and refuges for valued marine animals, are particularly vulnerable to harm from coastal development.
Continued impairment of these head-water creeks will ultimately affect the overall productivity of fish and shellfish populations and lead to degradation in deeper estuarine areas if communities do not change the way they develop the coastal zone, says Sanger.
Porous Pavement Has Arrived
A new generation of low-impact pavements comes to market.
Manufacturers are producing a new generation of porous concrete and asphalt pavements that offer unprecedented water-filtering capacity and over time could help solve some of the nation’s intractable water-quality problems. These new materials, moreover, are less expensive to use than conventional pavements.
That’s according to Bruce K. Ferguson, director of the University of Georgia School of Environmental Design and a nationally recognized expert in stormwater management.
“Porous pavements, surprisingly, turn out very favorably in terms of cost,” he says.
In the past, asphalt and concrete for driveways, parking lots, and roads had to be made water-resistant for the purposes of sturdiness and longevity. One problem with water-resistant pavement is that stormwater picks up contaminants from these surfaces and flows into nearby waterways, diminishing water quality.
Recently, though, manufacturers have successfully produced concrete and asphalt pavements that are tough, long-lasting, and porous, says Ferguson. The newest paving materials are slightly more expensive than conventional ones. But porous pavements can save developers money by reducing the size of stormwater ponds or even eliminating them, depending on soil conditions and other factors, and this frees up more developable land for homes, businesses, or additional open space.
“By using porous pavements, developers don’t have to buy more land on which to put in a single-purpose treatment system” such as a stormwater detention pond, says Ferguson. “Instead, they would just have to change the materials of the parking lot, for instance. You were going to build the parking lot anyway, but now it has two functions: a water filter and a pavement.”
Communities that have embraced this technology to date are primarily those in areas of high-density urban development or redevelopment, which do not have extra space to devote to single-purpose storm-water ponds.
What Can We Do?
Everyone can help reduce stormwater impacts.
Everyone can play a role in reducing stormwater impacts. Limit your load of pollutants through these activities:
- Apply fertilizers and pesticides sparingly and according to directions.
- Reduce bacteria by picking up after pets and disposing of the pet waste appropriately. If your home is on a public sewer system, flush pet waste down the toilet. Other options include disposal in household garbage or burial in your yard at least six inches deep and away from vegetable gardens and waterways.
- Wash your car on your lawn (or other porous areas) where the chemicals can be absorbed into the soil rather than draining into the nearest creek or pond.
- Dispose of lawn clippings in a compost pile.
- Harvest rooftop rain water through rain barrels or rain gardens.
- Take paint, oil, antifreeze, debris, or other chemicals to a county recycling center.
- Clean up spilled brake fluid, oil, grease, and antifreeze. Do not hose them into the street where they can eventually reach local waterways. Take to a county recycling center.
- Maintain proper septic system function with inspections and pump-outs every three to five years.
Reading and Websites
Center for Watershed Protection
Clemson University Cooperative Extension Service
EPA Green Infrastructure – Office of Wastewater Management
Natural Resources Defense Council: Urban Stormwater Solutions
S.C. Department of Health and Environmental Control – Bureau of Water
S.C. Department of Health and Environmental Control – Office of Ocean and Coastal Resource Management