Technical Resources

This Week in Washington



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 storm events 

 WEF Events 

Clean Water Act Integrated Planning Framework — Next Steps
June 14
10 a.m.–12 p.m. (EDT)
A three-part, no-charge webcast 

Design of Urban Stormwater Controls MOP Series
June 14, July 12, Aug. 9
1:00-2:30 p.m. (EDT)
A no-charge webcast series 

WEF/CWEA Stormwater Symposium 2012
July 19–20

Sept. 29–Oct. 3
New Orleans


Member Association Events 

Ohio Water Environment Assoc.
Annual conference 
June 18–21
Aurora, Ohio
With stormwater sessions 

Ohio Water Environment Assoc.
Free Lunchtime Webinar — Green Infrastructure 
June 28
12–1 p.m. (EDT)
Part of 2012 Green Infrastructure Series 

New York Water Environment Assoc.
2012 Watershed Science and Technical Conference 
West Point, N.Y.
Sept. 13–14


 Other Events 

 APEGBC: Stormwater Detention Facility Design June 13
Richmond, British Columbia

Stormwater, Coal-Tar Sealcoat, and PAHs
June 14
1–3:45 p.m. (EDT)
Part of a stormwater pollution prevention webinar series 

Section 319 Nonpoint Source Success Stories 
June 14
1–3:45 p.m. (EDT)

Region 6 Stormwater Conference  
June 24–29
Fort Worth, Texas


  June 7, 2012                                                Vol. 2, No. 6  

 storm feature 



Why is Bioretention So Popular? 

In suburban areas, bioretention is becoming a common best management practice (BMP) for stormwater because it is cost-effective, as well as highly effective at reducing volume and removing pollutants.

“For pollutant removal, across the board, bioretention is the best practice,” said William Hunt, associate professor and extension specialist in the Stormwater Engineering Group at North Carolina State University.

Other BMPs can be combined to effectively remove pollutants, but bioretention cells (BRCs) can be designed to incorporate a variety of pollutant removal mechanisms — from filtration to adsorption. “Bioretention is, in its own right, a series of pollutant removal mechanisms,” Hunt said.

Between 2010 and 2011, the International BMP Database released performance summaries for bacteria, volume reduction, nutrients, solids and metals, with a major update to be released this month. Of the BMP categories analyzed, BRCs provided the best volume reduction performance, especially for small storm events. On average, BRCs reduced runoff volume by approximately 55% using underdrains and by nearly 90% without underdrains. Volume reduction estimates are based on the fraction of total monitored inflow volume that did not discharge from the BRCs in the studies analyzed.

“No other practices are as good at taking runoff and converting it to infiltration and evapotranspiration,” Hunt said. However, bioretention is not good at mitigating peak flows from larger events. In those cases, Hunt recommends combining BRCs with a pond, wetland, or underground storage device.

Studies show bioretention to be effective at reducing sediment and nutrients. To effectively remove nitrate and nitrite, a BRC must include an anoxic zone by retaining water in the soil matrix for a sufficient time. Most phosphorus, however, is bound to sediments, so bioretention can be highly effective at removing phosphorus through sedimentation and filtration, given proper media specifications. According to BMP Database performance summaries, bioretention removes total suspended solids with efficiencies similar to media filters and wetland basins, but bioretention provides the added benefit of volume reduction.

The BMP Database metals performance summary showed that bioretention is effective at removing such metals as cadmium, copper, and zinc. Studies by Allen Davis, a professor of civil and environmental engineering at the University of Maryland, have also shown very high removal rates for copper, zinc, and lead. Bioretention media can also be engineered to target specific pollutants in certain industrial settings, according to Eric Strecker, co-principal investigator for the BMP Database.

“Water leaving a BRC is about as clean as you can imagine, having passed over urban surfaces,” said Hunt, regarding his research in North Carolina. Comparisons show that it matches water quality found in streams supporting healthy benthic communities.

However, “BRCs are somewhat fragile practices,” Hunt said. They will not deliver their potential benefits if clogged, which will likely happen if not properly maintained or located in a watershed experiencing high rates of erosion.

Economics also favors bioretention in suburban areas. “The free market has led to bioretention being the most commonly implemented practice in the Mid-Atlantic,” Hunt said. It is particularly attractive at commercial facilities where it meets landscape requirements and stormwater needs simultaneously and in states that force or incentivize nutrient export limits in new construction and redevelopment, he said.

Cost and performance data are important to share with regulators and designers, so they can make informed decisions regarding stormwater treatment, Hunt said. That is where the International BMP Database comes in. It also helps researchers determine the bounds of effectiveness for specific practices and compare local and national performance data.

The BMP Database provides performance information for many different stormwater BMPs in various land use settings. There are many BMPs that remove pollutants effectively, and “engineers should consider multiple factors when selecting the best BMPs for a site,” said Jonathan Jones, co-principal Investigator for the BMP Database project. Factors include performance, as well as safety, maintainability, multipurpose community benefits, integration with flood control objectives, deicing practices, onsite contamination, and others.

This year, the International Stormwater BMP Database exceeded 500 performance studies and has become easier than ever to use. The site has added several new features, including an interactive BMP mapping tool and online statistical analysis feature (beta version). Additionally, the Water Environment Research Foundation is leading efforts to incorporate more Chesapeake Bay data and an expansion of the database to include agricultural BMPs.

 Storm news 

Arlington County, Va., Rain Garden Traps Pollutants and Educates Visitors  

Powhatan Springs Park in Arlington, Va., is an example of an innovative rain garden design that combines bioretention with stormwater education. The children's rain garden exposes and animates the flow and collection of rainwater, while the soil media and wetland plants help remove sediments, nutrients, and other pollutants. The garden, combined with an underground cistern, has the capacity to hold 42 m3 (11,123 gal) of stormwater.

This is the second kickoff video for the Stormwater Call for Media, an effort to collect and share innovative stormwater projects through pictures and video. Check out videos already shared, and remember to like your favorites. Top picks will be shown at the 2012 Stormwater Symposium and at WEFTEC® 2012. Submissions are due June 30. Get the details.


Super Saver Rate Still Available for 2012 Stormwater Symposium 

pondThe 2012 Stormwater Symposium, hosted by the Water Environment Federation and Chesapeake Water Environment Association, will be held in Baltimore July 18 to 20. Be sure to register before the Super Saver rate closes June 13. Conference sessions will cover an array of stormwater topics from policy to cutting-edge research to innovative technologies. The New Stormwater Management Paradigm, a panel discussion, will involve several well-known professionals in the stormwater field.

Larry Coffman, president of Stormwater Services, recognized as an early leader in the development of Low Impact Development at Prince George's County, Md. will act as the moderator for this group.  Panelists will include Lawrence Liebesman, partner at Holland & Knight, who represents multiple clients in the stormwater sector, particularly in the areas of stormwater funding and finance and Chris Kloss, green infrastructure coordinator for the U.S. Environmental Protection Agency and an integral member of the team focusing on the current national stormwater rulemaking effort.   

Opening general session participants will include Robert Traver, who is a leading researcher in the stormwater field and is the director of the Villanova Urban Stormwater Partnership, Kim Burgess (invited) who is chief of surface water management with City of Baltimore Public Works Department, and Maryland Gov. Martin O’Malley (invited). Robert Summers, secretary of the environment with the Maryland Department of the Environment, who has been at the forefront of many of Maryland’s progressive stormwater programs, will provide input as a lunch keynote speaker along with a representative from the organization Green for All, which released a report last year focusing on green infrastructure and green jobs.


DC Water adopts Clean Rivers Fee To Fund Multibillion Dollar CSO Tunnel Project 

storm drainDC Water has a plan to reduce combined sewer overflows (CSOs) by 96% in the District of Columbia. The Clean Rivers Project comprises the construction of three large storage tunnels to capture and store wet weather runoff. Though the project is federally mandated, funding had not been earmarked for the project.

 As the process stands now, the 130,000-plus account holders served for the District of Columbia — including residential and wholesale suburban customers — will pay the vast majority of project costs, estimated at $2.6 billion through 2025. To help allocate cost as equitably as possible among its customers, DC Water developed a stormwater fee based on impervious areas. Read more in the May issue of WE&T.


 Volunteers Needed for 2012 Stormwater Symposium 

Conference leadership is looking for additional involvement at the 2012 Stormwater Symposium, including workshop room monitors on July 18 and session co-moderators for both July 19 and 20. Co-moderators help organize speakers before and during the session and help introduce speakers before each talk. For more information, please e-mail Jeff Cantwell at


 U.S. EPA Launches Campus RainWorks Challenge 

The U.S. Environmental Protection Agency (EPA) recently launched the Campus RainWorks Challenge, a green infrastructure design competition for student teams working under a faculty advisor. Registration opens Sept. 4, and entries are due Dec. 14. Student teams could win up to $2500 in cash prizes and up to $11,000 in research funds for their faculty advisor. Next year, EPA plans to expand the competition to include a demonstration component. Read more.


 Tennessee Gives Municipalities Approval Authority for NPDES Construction Permits  
On May 15, Tennessee Gov. Bill Haslam signed SB 3187, eliminating duplicate state- and local-level review of National Pollutant Discharge Elimination System (NPDES) construction permits by giving municipalities authority to approve. A pilot program is currently ongoing until the law takes effect July 1, 2013. To gain authority to run its own construction permitting program, a municipality must establish requirements that exceed those of the state. The Tennessee Department of Environment and Conservation estimates that this streamlined process could save construction owners and operators up to $7500 in state fees. Read more.


Chesapeake Bay Commission Releases Nutrient Trading Cost Analysis    

On May 3, the Chesapeake Bay Commission released Nutrient Credit Trading for the Chesapeake Bay: An Economic Study by RTI International. The study reports that nutrient trading could produce a potential cost savings of 20% to 80%, depending on implementation parameters. The highest cost savings reported are achieved through a watershed-wide program that allows urban stormwater systems to swap with farmers, as agricultural best management practices offer lower cost options. The report also recommends government-defined rules and enforcement, as well as technical assistance and information, in order to actually deliver on pollution reductions.


U.S. EPA Drops Flow-Based Surrogate From Missouri TMDL   

The U.S. Environmental Protection Agency (EPA) has agreed to drop a flow-based surrogate from the total maximum daily load (TMDL) for Hinkson Creek, Mo. This move indicates that EPA may drop this approach from future national policy plans. The settlement came after a lawsuit filed by the Missouri Department of Natural Resources; Boone County, Mo.; the City of Columbia, Mo.; and the University of Missouri. Read more about the original case.


Cases on Federal Payment of Stormwater Fees Could Lead to a Federal Court Split   

The 2011 Clean Water Act (CWA) Amendment allows municipalities to leverage reasonable stormwater fees on federal facilities. In USA v. Cities of Renton and Vancouver, a Washington State District Court recently ruled that federal facilities are responsible for municipal stormwater fees billed prior to enactment of the 2011 amendment. This decision could create a split among federal courts, as the U.S. Department of Justice is arguing that stormwater fees do not apply retroactively in DeKalb County, Georgia v. USA. If the Georgia federal claims court rules that the federal government is not required to pay stormwater fees incurred prior to January 2011, the stage will be set for a petition to the U.S. Supreme Court. 


 U.S. EPA Will Not Require Stormwater Permits for Logging Roads   

In the May 23 Federal Register, the U.S. Environmental Protection Agency (EPA) published a notice that logging roads will not require Clean Water Act permits. EPA plans to release a rule maintaining the precedent that best management practices are more practical than issuing permits for millions of miles of forest roads. This issue arose due to a decision by the U.S. Court of Appeals for the 9th Circuit stating that forest roads require National Pollutant Discharge Elimination System permits for stormwater runoff. The U.S. solicitor general has advised the U.S. Supreme Court to let the appeals court ruling stand. Forest industry representatives, however, fear that without decisive action by the Supreme Court, the issue will remain open to litigation.

A temporary ban on stormwater permitting for logging roads is currently in effect until Sept. 30, after which EPA hopes to have finalized a rule.


Cities Cite Stormwater as Primary Climate Change Concern   

On May 16, the Natural Resources Defense Council and the Rocky Mountain Climate Organization released Doubled Trouble: More Midwestern Extreme Storms. According to the report, severe Midwestern rain storms — those totaling 75 mm (3 in.) or more in 1 day — have doubled in the last century. An earlier Water Environment Research Report states that annual precipitation associated with extreme events increased by 14% per decade from 1970 to 1999.

Many existing stormwater systems are not designed to handle more-intense rain events associated with climate change. In a recent survey of 468 cities, stormwater runoff was the climate change issue cities most anticipate addressing, according to a report by the Massachusetts Institute of Technology in collaboration with ICLEI–Local Governments for Sustainability.

The Minnehaha Creek Watershed District is taking part in a 2-year study of Minnesota's changing weather funded by the U.S. National Oceanic and Atmospheric Administration. The study will focus on adapting stormwater infrastructure to projected rainfall patterns in an already developed city, Minneapolis, and a developing city, Victoria.

Read more about how municipalities are becoming “climate-ready” by incorporating adaptation into scheduled maintenance and upgrades.  


Sewage Dogs Sniff Out Stormwater Contamination   

Milwaukee Riverkeeper is using sewage dogs to sniff out areas where water may be leaking from the sanitary sewer into the storm sewer. The dogs are trained to alert people if they smell fecal pollution. By identifying specific manholes with contamination, the dogs can help narrow the area of investigation.

Milwaukee River Keeper received a $4000 grant from Sweet Water Trust to test the effectiveness of the dogs’ sniffing skills. Volunteers pulled samples from the manholes that the dogs sniffed to verify the findings. The dogs came from Environmental Canine Services, a company that specializes in training dogs to detect illicit discharges.


Post ItCheck It Out! 

Retention ponds are designed to manage stormwater flow and trap pollutants. Because many collect a significant amount of nutrients, the ponds often grow algae on the surface of the water. This can create odor concerns and lead to low oxygen levels that do not support aquatic life. The floating wetlands are essentially buoyant mats that can be filled with plants. The plants help remove water through evapotranspiration and filter pollutants. They also provide habitat and help prevent ponds from developing low oxygen conditions. Read more.