If you are a stormwater system manager and want to find illicit, illegal and unintentional discharges of pollutants, go looking in the fall.

It’s not too cold, the vegetation has died and groundwater influences are minimal. And, there’s less rain than most times of the year. Dry weather makes it easier to find discharges like soapy wash water from an incorrectly plumbed private home or raw sewage leaking from a pipe at an industrial site or a broken pipe in the storm sewer system.

These sources can contribute as much as 40 percent of the annual load of nutrients from urban watersheds, as well as bacteria from sewage leaks or chemicals such as laundry whiteners. These pollutants are also flushed into streams and rivers during wet weather, but because they are diluted by the rain, it is difficult to detect and measure them.

Finding and fixing problems in the underground network of sewer, water and storm drain pipes that serve a community could be a cost-effective way for many cities, especially older ones, to clean up local streams and meet the nutrient reductions required under the Chesapeake Bay Total Maximum Daily Load.

Many of these discharges went undiscovered, and therefore, not fixed — because until now, many cities only implemented the minimum measures necessary to comply with their stormwater permits. A credit program approved by the Chesapeake Bay Program in November 2014 may change that. It offers cities a way to get nutrient reduction credits by going beyond the minimum requirements of their stormwater permits.

But whether the new credits provide enough incentive for cities to do that depends on multiple factors: the city’s size and resources, the age and condition of its infrastructure, or if it has already invested in other practices such as urban stormwater retrofits or stream restorations.

“This is not a theoretical percent removal — you get credit for what you actually find and fix,” said Tom Schueler, executive director of the Chesapeake Stormwater Network.

Stormwater permit basics

In the 1980s, the EPA’s major concern with stormwater was the “combined sewer systems” in many large cities. In these systems, the sanitary sewers also convey stormwater to waste treatment plants and are designed to overflow directly into rivers when they are overwhelmed by heavy rains. This increasingly happened as cities grew and the infrastructure aged, sending even more untreated waste into streams.

Many cities have made great strides to increase capacity and upgrade their infrastructure by separating stormwater conveyance from the sanitary sewer, creating a municipal separate storm sewer system, or MS4.

Approximately 1,000 localities in the Bay watershed have these systems. They are allowed to discharge stormwater to rivers and the Bay under MS4 stormwater permits, which require that the system of storm inlets and underground pipes is built and maintained to ensure that it conveys only stormwater.

But stormwater systems — especially those in older cities that were cobbled around aging sanitary sewer and drinking water systems — are not perfect. They suffer from groundwater infiltration, inadvertent cross-connections with sewage, and illegal hook-ups from private homes — all of which can result in flows during dry weather.

“In the 1980s, we often had dry weather overflows of millions of gallons a day,” said Bill Stack, deputy director for programs with the Center for Watershed Protection. Stack was with the City of Baltimore for 30 years, and studied dry weather flows during his tenure as a stormwater and drinking water manager. “We knew that it was the small day-to-day leaks throughout the system that were contributing to the problem.”

Raw sewage leaking into the system is not the only problem. The improper disposal of oil and household toxics, car and laundry wash wastewater and spills from roadway accidents also enter stormwater drains.

As a result, MS4 stormwater permit holders must have an “Illicit Discharge Detection and Elimination” program to address these pollutants. These have robust measures to map the stormwater system, prohibit illegal discharges and the improper disposal of waste, and set quantifiable goals for pollution reduction. But they often fall short of eliminating the problems.

“IDDE has often been more of a ‘check the box’ strategy rather than truly “find and fix the problems’ strategy,” said Dave Hirschman, stormwater manager for the center, which has worked for decades with the EPA and communities around the country on stormwater issues.

Only checking the boxes has a cost, though. A landmark study by the center published in 2011 showed that these illicit discharges could contribute 20–40 percent of the annual nutrient load in urban watersheds.

Another study, set in Richmond, showed that the correction of cross-connections and sewer repair was one or more orders of magnitude less costly than best management practices such as bioretention and dry detention ponds.

These studies marked a turning point in how these discharges were perceived by the Chesapeake Bay Program. (See “Groups piping up about threat of many small drains to water quality,” (November 2011).

An expert panel was convened to evaluate how to give local governments credit for measurably reducing illicit discharges. It decided that communities that identified and fixed these discharges — which the panel called “discovered discharges” — should be eligible for nutrient reduction credits. It then created a two-phase credit system.

In 2015, localities became eligible to seek nutrient credits for the “Advanced Nutrient Discovery Program” by shifting their local IDDE programs away from traditional visual outfall screening methods and toward targeted nutrient screening and discovery methods. They must also meet several numeric metrics for program performance. In this first phase, localities can receive a credit of 0.2 percent reduction in their annual nutrient load, Schueler said. “It may not seem like much, but in many cases that small percent will be applied over a significant area, resulting in a significant credit.”

In the second phase, starting in 2018, localities will be able to apply for credit for each individual “discovered discharge” that has been found, fixed and monitored to ensure the discharge has been eliminated. A more complex process, requiring more sophisticated sampling techniques, these individual credits will more accurately reflect the actual pollution prevention achieved and be valued higher than the credits received for just having the advanced program in place.

“The panel built this two-step process to enable local governments to grow into the program,” Schueler said. In the meantime, he said, “when you think about the money needed for stormwater retrofits, elimination of these sources is still going to be a bargain.” It is hoped, he said, that the credit will encourage local governments to “get it done.”

Implementing the credit program

Larger cities like Richmond and Arlington, VA, and Montgomery County, MD, that have had MS4 permits in place for a longer time than smaller localities, may have an easier time achieving advanced program credits.

Kelley Junco, MS4 program coordinator for Harrisonburg, VA, said, “We are already doing components of the advanced program, and we are interested in receiving advanced program credits.” But to quantify these activities and coordinate them across departments will take more administrative work and record-keeping, both of which cost time and money.

Harrisonburg has just started collecting a stormwater utility fee, and Junco said there’s a queue of stormwater improvement projects that will use that revenue. “For now, we’re going to direct that money where the public can see their utility dollars being spent.”

Junco pointed out that the credits earned for discovering and shutting down individual sources of pollution are only available for five years after the first year in which they are reported. “We’re looking for continued, sustained credits,” Junco said, “like stream restoration, which gives credits over a longer period of time once the restoration is completed.”

And developing a program beyond the required basics can be difficult. Laurel Williamson conducts stormwater training for local governments for the Center for Watershed Protection. “Many localities are still working on the basics: What is the IDDE program? What is the minimum we must do for our MS4 permit? And how do we do it?”

For many small MS4 permit holders, like townships in Pennsylvania that Williamson has worked with which have only three people on staff, the IDDE gets shoved to the bottom of the list.

“I can understand why this happens,” Williamson said. “It’s complicated, it takes a lot of tools, good mapping of the stormwater infrastructure — which a lot of localities don’t have — and an understanding of chemistry if you’re going to be taking water samples.”

And unless there’s an obvious break in a pipe, sleuthing out the source of discharges takes patience — and staff— and the results are unpredictable, Williamson said.

“You don’t know what you’re going to find unless you look for it,” she said. And when you find the problem, the fix may be expensive — or not. The local government can’t really know what credit is possible until the source is found, tested, eliminated and documented.

Costly capital equipment, like closed-circuit TV systems for inspecting municipal pipe networks, may be difficult for an MS4 locality to obtain. “And if your utility is being run by an authority separate from local government, or even another department in the same city,” Williamson said, “it can be hard to gain access to the equipment you might need.”

But not everywhere. In Lynchburg, VA, for example, the same manager is responsible for both stormwater and public works. This makes for better communication, said water quality compliance specialist Craig Homan. “I can just pick up the phone and ask public works if I can borrow the vacuum truck for cleaning out storm drains. It’s easy.”

Improving local water quality

The heart of the MS4 permit program is to protect and improve local water quality, and most people would agree that eliminating illicit discharges is positive, whether or not a local government chooses to seek nutrient reduction credits.

Diane Handy, a member of the expert panel, is a stormwater specialist with the highly regarded MS4 program in Arlington County, VA. She said the county will continue to build its program — whether they seek credits or not — because there are so many benefits for the community.

“We want to use our program to leverage other benefits,” Handy said. For example, eliminating fats, oils and grease discharges into the storm sewer reduces the potential for clogging the system. “But we’ll also be avoiding attracting pests,” Handy said.

And reducing the amount of sewage that enters waterways has immediate and important public health and safety impacts for every community working toward “fishable and swimmable” waters.

“Some of these discharges are egregious,” said Lori Lilly, watershed restoration professional and IDDE expert who served on the expert panel. “It’s not just the nutrients, it’s the bacteria, the heavy metals. We have a right to good clean water, whether it’s regulated or not.” Eliminating these discharges should be thought of as “low-hanging fruit,” Lilly said.

And it’s not all up to the local governments; individuals can help keep fat, oils and grease from going down the drain and by keeping trash out of stormwater outfalls.

The new credit system for discovered discharges will also cover previously unregulated discharges. “Most of the MS4 permits say that you have to monitor outfalls 36 inches or larger,” Schueler said. “These are huge outfalls, and monitoring teams in Maryland, North Carolina and other places around the U.S. have found that the larger source of discharges are coming from the smaller pipes — the ones that are 3, 6, 12 inches in diameter.”

While MS4 permits require municipalities to establish regular outfall inspection programs, there are growing opportunities for watershed groups to help. Lilly points to Blue Water Baltimore’s Outfall Screening Blitz program, which actively engages citizens in detecting stormwater system problems.

A successful IDDE program, Williamson said, “is making sure everybody — utility folks, road crews, public works and citizens — have a picture in their mind of what is normal water coming out of a pipe and what isn’t.” Things like paint, oil, chemical spills and fuel leaks are very intermittent, she said, and you have to catch them right away.

Seeking credits through the advanced program may simply come down to money. With Lynchburg’s newly instituted stormwater fee, Homan said, “we’re actually getting money to move ahead and make repairs” that will help reduce overflows and dry weather discharges.

But Stafford (VA) County’s Stormwater Program coordinator, Paul Santay, said, “we already knew we can achieve 100 percent of our nutrient reduction goals with retrofitting stormwater [BMPs]. At this point, it’s not worth it to us to spend the money to go after the advanced program credits.”

And there are uncertainties associated with policy guidance. Virginia has required all MS4 communities to link the nutrient and sediment reductions prescribed by the Bay TMDL to their MS4 permits, by developing Chesapeake Bay Action Plans. But state guidance for developing these plans came too late for local governments to identify the advanced nutrient program credits as a possible strategy. “We’re looking at seeking credits for the advanced program,” Arlington County’s Handy said, “but we’ll have to wait for our next permit cycle to do so.”

Maryland MS4 permits are also newly tied to the Bay TMDL, and localities are in the midst of putting together their implementation plans. Schueler said that he hoped they would take advantage of the opportunities that fixing “discovered discharges” offer.

“It takes about a year for word to get out about the guidance coming from these expert panels, “Schueler said. “Local governments are just beginning to work this credit through the states,” and 2015 will be the first year that the states can report the credits to the Bay Program. “Hopefully, these localities will enhance their programs so that in 2017 they will be in a position to easily transfer to the individual credit option.”

“It’s not a silver bullet, but it’s a good a strategy for many communities, particularly the older ones. But it will take a little time before it becomes as commonplace as stream restoration and other stormwater BMPs.”

Contributors to Nutrient Loads

These substances contribute to nutrient loads and can be calculated and credited in the Advanced Nutrient Discovery Program:

  • N-1: Laundry wash water
  • N-2: Commercial car washing
  • N-3: Floor drains
  • N-4: Miscellaneous high-nutrient discharges, including air-conditioning condensate, fire engine washing, restaurant cleaning operations, metal plating operations
  • N-5: Sanitary direct connections
  • N-6: Sewage pipe exfiltration
  • N-7: Drinking water transmission loss
  • N-8: Dry weather sanitary sewer overflows