For stormwater, that’s just the start of a complex journey that has important implications for the health and safety of the environment and humans.
By Ken Mammarella
When water from heavy rain or significant snowmelt gushes down the gutter into a catch basin, it appears to be a simple system working efficiently. But it is really a critical process that involves drinking water, tax dollars, and the health of the land and its flora and fauna.
“Most people don’t think about it because the idea is to get the stormwater out of our mind,” says Jerry Kauffman. Just the same, as director of the University of Delaware Water Resources Center, stormwater has been heavily on Kauffman’s mind for decades. “In our Northern Delaware neighborhood, stormwater eventually becomes drinking water,” he says.
The Delaware Department of Transportation, which owns and operates almost all roads in the state, also thinks about stormwater a lot. “Drainage is a significant and important component of all major DelDOT projects,” says C.R. McLeod, the agency’s director of community relations. Roads that flood are roads that are unsafe.
Stormwater systems manage occasional deluges. Sewer systems, in contrast, handle relatively consistent discharges. In some areas, the systems are combined.
Delaware employs several types of stormwater management systems. The most prevalent use gutters along streets and roads to channel stormwater toward drains that are covered with grates to prevent them from being clogged by debris. Because a third of Delaware’s is built up, Kauffman says, about three-fourths of Delawareans live in cities and suburbs that feature curb-and-gutter systems.
Stormwater can also be managed with green engineering. Edging many roads are ditches called swales that allow stormwater to percolate slowly into the soil. Arden’s swales are good examples, Kauffman says, praising their well-manicured beauty. Delaware also has 2,000 miles of tax ditches that drain the land for more than 100,000 people. The last method of stormwater management is, basically, to do nothing. The “rural” system allows water to flow and puddle on large lots.
Down the Drain? Not So Fast!
Curb-and-gutter stormwater systems can be complicated. Newark operates 65 miles of stormwater pipes, 291 outfalls (where the water flows out) and 2,044 catch basins, according to environmental coordinator Kelley Dinsmore. The University of Delaware and DelDOT also operate outfalls and catch basins in Newark’s nine square miles. (That’s a very small portion of Delaware’s 1,948 square miles.)
Standards specify grated drains every 500 feet. Those drains feed into pipes that lead into waterways or into bioretention areas called rain gardens or stormwater ponds. In the hilly piedmont of northern New Castle County, pipes can work by gravity. In the flat alluvial plain that forms the rest of the state, pumps keep the water moving.
Bioretention areas include the landscaping around UD’s Interdisciplinary Science Learning Laboratories in Newark and the rain garden near the Claymont Library. “It works on the same principle as a water treatment plant,” Kauffman says. “The water sits here, the heavy material settles out, and then you have time for bacteria to do their [purification] work. Wetlands with sedges are even better because there’s a biological uptake of nutrients like nitrogen.”
Wetlands are a “relatively inexpensive” method of cleaning stormwater and preventing flooding, according to the federal Environmental Protection Agency. Section 404 of the federal Clean Water Act requires three acres of wetlands to be created for every acre taken for road construction. In Delaware, wetlands reconstruction is most obvious on the sides of Route 1 from the Chesapeake & Delaware Canal to Dover, Kauffman says
Tidal salt marshes—Delaware has thousands of acres of preserved marshes—yield similar benefits. They produce more vegetation per acre than rain forests, filter sediments and contaminants, and help protect inland areas from storm-surge flooding.
More Than Water
Stormwater is, however, more than water. It also carries pollution, which “can have damaging effects on both human health and aquatic ecosystems if not treated,” according to DNREC.
DelDOT notes 10 problems with stormwater pollution: fertilizers and pesticides; pet wastes; motor oil, gas and antifreeze from vehicle maintenance; detergents from washing vehicles and debris from hosing down pavements; yard waste; trash and litter; cigarette butts; household products; household chemicals; and sediment from construction sites.
The liquids can contaminate the water or upset the balance of nutrients. The solids can clog storm drains, causing water to pool in roadways and creating dangerous driving conditions. Cigarette butts can catch fire, and the unsightly litter can clog pipes and waterways. Even too many leaves can clog the system, which is why places like Newark have special pickups for yard waste, Dinsmore says. Newark also regularly sweeps the streets and clears catch basins and other parts of the system.
“On a really nice Saturday, if you drive through Newark, you can see a lot of foam on the creek,” Dinsmore says. That foam comes from people washing their vehicles on the road or driveways. The suds seem to disappear into a catch basin, but, minutes later, they appear in the waterway as pollution. A simple solution: Wash the vehicles on the lawn so suds can dissipate and filter through the soil.
“The thought used to be to get the water into the catch basin and into the creek as quickly as possible,” Dinsmore says. “We’re changing course on that and trying to mimic what nature does. Slow it down. Soak it in.”
Another important idea is keeping contaminants out of the stormwater system in the first place. That’s why Newark goes through 30,000 pet waste bags a year at its parks. “We’re trying to make it easier for people to pick it up and remove instead of leaving it on the ground.”
The homepage of the Delaware Solid Waste Authority contains links to all its facilities, recycling guidelines and hazardous-waste collections so the bad stuff can be disposed of properly.
There’s Even More. It’s Called MS4.
In 1987 an amendment to the Clean Water Act created a phased approach to regulating urban stormwater runoff. Starting in 1990, municipal separate storm sewer systems (called MS4s) were required to get National Pollution Discharge Elimination System permits by proving they were doing good things for stormwater and discharges, including:
• Controlling erosion at construction sites.
• Detecting and eliminating illicit discharges, such as “septic tank drainage, laundry wash water, paint, automobile oil, grease from restaurant grease traps and sanitary waste.”
• Preventing pollution and good housekeeping. Such as maintaining government infrastructure.
• Managing stormwater after construction. Developers are encouraged to use low-impact practices such as regular street sweeping and setting aside sensitive areas as buffers.
• Educating the public about stormwater management.
• Involving the public in stormwater management.
The first phase of MS4s included large municipal governments. In Delaware that meant DelDOT and New Castle County (including Delaware City, Elsmere, New Castle, Newport and Wilmington). A second phase for smaller communities began in 1999. In 2020 drafts of the permits were released for public comment. That second phase has two tiers: Tier 1 includes DelDOT in Kent County, Dover, Middletown and Newark/UD. Tier 2 permits went into effect in 2024.
Delaware administrative code takes about 85,000 words—the length of an average novel—to cover it all. The process was written by lawyers, not water scientists, so “implementation is as bad as it sounds,” Kauffman says.
Another problem: The systems tend to follow political boundaries, not the natural drainage boundaries of the hills and valleys. Delaware has 42 watersheds and four management basins. Some watersheds span portions of other states, so UD’s Water Resources Center also watches what happens upstream in Pennsylvania.
“I’ve talked to college professors who have dumped yard waste in a catch basin and don’t understand why that’s bad,” Dinsmore says. The creek can’t handle the load and the debris can cause erosion. “At the end of the day, the goal is to improve water quality,” she says. “Everybody wants clean water.”
About the Author: Ken Mammarella is a Delaware native and longtime journalist who in his spare time likes to explore the terrain by bike.
Learn More
Delaware Solid Waste Authority https://dswa.com
Municipal Separate Storm Sewer Systems https://dnrec.delaware.gov/water/commercial-government/npdes/ms4/
New Castle County celebrates Earth Day with new rain garden in Claymont https://www.delawarepublic.org/science-health-tech/2022-04-22/new-castle-county-celebrates-earth-day-with-new-rain-garden-in-claymont
Sediment and Stormwater https://dnrec.delaware.gov/watershed-stewardship/sediment-stormwater/
Stormwater Management https://deldot.gov/Programs/stormwater/
Strategies in Which Precipitation Enters the Landscape https://www.isll.udel.edu/harker-ise-building/green-technology/stormwater
Drainage and Stormwater https://dnrec.delaware.gov/drainage-stormwater/
What is an MS4? https://extension.psu.edu/what-is-an-ms4
Where Stormwater Pollution Comes From https://deldot.gov/Programs/stormwater/index.shtml?dc=wherestorm
If you want to help
At home, follow these tips from New Castle County’s Clean Streams Champions program:
- Scoop your pet poop, then dispose of it in bio-degradable bags.
- If you have your own septic system, pump your tank every three years.
- Garden with native plants. They are adapted to local water conditions and they promote native biodiversity.
- Keep grass clippings, leaves, litter, fertilizer, mulch and loose soil off hard surfaces so they don’t wash into storm drains. Place yard waste for collection in approved containers.
- Wash your car on the lawn or use a commercial car wash that recycles water.
- Use simple soaps. Avoid antibacterial soaps and soaps with microbeads.
- Clean with non-hazardous products such as lemon juice, vinegar, hot water, borax, and baking soda instead of harsh chemical cleansers.
- Keep cooking grease from out of the drain. Cool kitchen fat in a container, then put it in the trash.
Find more great tips here. Subscribe here to Delaware Nature Society’s advocacy newsletter to stay informed of emerging policy changes and action alerts.