From The Editor | November 7, 2017

Case Studies From The World Of Improved Stormwater Management

Peter Chawaga - editor

By Peter Chawaga

As we finally move out of hurricane season, there are many examples to look back on that show just how difficult stormwater can be to manage. Florida, Texas, Puerto Rico, and many other locales were devastated this year by storm surge, and though a certain level of this destruction appears impossible to avoid, many applicable stormwater management lessons can be derived from their experiences.

The New York City Department of Environmental Protection (DEP) has been collecting such lessons from around the world, releasing a new report on “Innovative and Stormwater Management” as a way to share what it has learned from other communities.

The report, which has been released in partnership with the Water Research Foundation (WRF), offers lessons from a data-sharing program between 34 communities, the common challenges to flood mitigation, how to integrate stormwater management into broader initiatives, and tips for regulatory compliance.

“The timing of the release is important as many communities around the nation have been impacted by flooding due to heavy rains and hurricanes in recent months,” said Pinar Balci of the DEP. “The report provides several innovative approaches that NYC and other water utilities used around the country and internationally and how to proactively handle the stormwater, heavy downpours, climate change, and flooding as part of an integrated plan rather than individually.”

The DEP collected data on stormwater solutions for over nine months, looking at other programs that could help it enhance and refine New York City’s approach in a more integrated and innovative way.

Of the three case studies from the project that Bacli highlighted, the first is from New York City itself. The city has a “future stormwater controls program” that it uses to fund the development of stormwater efforts beyond what is required by state and federal regulators for new development and redevelopment. It operates a “nonpoint source pollution strategy” for two local basins that focuses on reducing non-point pollution. It also has a septic repair program that keeps unfiltered supplies from entering source water.

Bacli also pointed to a “cloudburst management” program in Copenhagen, Denmark.

“The City of Copenhagen revised its approach to citywide stormwater management due to an increased amount of intense rainfall events and dry spells interspersed with heavy thunderstorms that leave the city inundated,” the report reads. “As a result, Copenhagen is currently planning for increased precipitation (a 30 percent increase in the extrapolation of recent events), and rising sea and groundwater levels.”

The city estimates its risk of damage caused by torrential rain in the next century to be about $2.2 billion. As such, it is planning to revise street surfaces to carry water to source bodies, implement underground tunnels to transport runoff, and build retention facilities upstream in the system to prevent overflow.

Finally, Bacli noted Seattle’s integrated plan as a case study particularly worthy of note. The city has proposed a list of stormwater projects to be completed by 2025, which would help it better protect water quality and treat larger volumes of water. Its plan takes into consideration a combination of consent decree requirements, waterbody impairments, and wet weather flow volumes to offer an integrated solution.

Though there are many successes and potential initiatives for others to emulate in the report, it also uncovered many needs and gaps that should be addressed. Bacli pointed to a dearth of strong leadership, a lack of funding sources, and competing areas of need as the greatest challenges uncovered during the research. But uncovering these pain points can serve as a positive step in addressing them.

“How some utilities used these challenges as a benefit rather than a constraint and utilized the integrated approach to meet multiple demands [offers a potential solution to others],” Bacli said. “Also, some utilities created sustainable funding streams through fees or streamlined regulations to enable private sectors for stormwater management.”

For those who want to dig deeper into solutions for their own stormwater management issues, the report serves as a wealth of knowledge and potential resources.