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New rule requires new developments to include stormwater management measures on-site

Gowanus Canal has been 'ground zero' for flooding in Brooklyn

February 24, 2022 Brooklyn Eagle Staff
Gowanus Canal
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The New York City Department of Environmental Protection (DEP) on Thursday announced that a new, Unified Stormwater Rule (USWR) requires newly developed or redeveloped properties to more effectively manage stormwater on-site.  

By retaining more stormwater on site, the USWR will help to keep the city’s drainage system from being overwhelmed during heavy rainstorms. Otherwise, this can lead to flooding, backups into homes and businesses, and overflows into waterways. Street drains being clogged with debris is another cause of flooding.

In the past, the most high-profile Brooklyn location that was prone to stormwater flooding was the area near the Gowanus Canal. During rainstorms, the water in the sewer system backed up and inundated local streets. Similar episodes have been reported in Carroll Gardens, Cobble Hill, DUMBO and elsewhere.  High-level storm sewers, which can reduce stormwater runoff, have already been installed on Third Avenue near the Gowanus Canal.

The new rule is expected to result in the reduction of Combined Sewer Overflows citywide by approximately 360 million gallons annually by 2030, helping to further improve the health of New York Harbor.

Our centuries-old stormwater systems are not built to handle the barrage of rain that comes down every year and we need a collective effort to preserve and green our city’s waterways.  The new stormwater rule is a common-sense step in ensuring that any new infrastructure we build can handle the next superstorm and build a more resilient city,” said New York City Comptroller Brad Lander, formerly a Brooklyn councilmember who represented the Gowanus area.  

Flash flooding in DUMBO in July of 2019. Eagle file photo by Mary Frost

“That’s why we fought for these requirements in Gowanus to prevent additional Combined Sewer Overflow from going into the Gowanus Canal, and worked to require these changes citywide,” said Lander.

“We believe the Unified Stormwater Rule is a key initiative that will help achieve Net Zero Combined Zero Overflow as a result of new development in the Gowanus Canal as well as the goals set forth in the NYC Resiliency Plan by promoting green infrastructure on private property, easing the strain on New York City’s already overburdened sewer system, and improving water quality citywide,” said Gowanus Canal Conservancy Executive Director Andrea Parker. 

“Stormwater continues to be a major pollution source for our waterways, so we are very encouraged to see the improved requirements with the Unified Stormwater Rule,” said Newtown Creek Alliance Executive Director Willis Elkins. “With climate change increasing the need for Green Infrastructure projects that can manage runoff through nature based techniques, we applaud DEP for this step in the right direction.” 

Damage after 40 minutes of flooding in Park Slope in August of 2019. Eagle file photo

The USWR updates and aligns Chapters 31 (stormwater quantity and flow rate requirements) and 19.1 (construction/post-construction permitting program water quality requirements) of Title 15 of the Rules of the City of New York.  Under the Chapter 31 amendments, the USWR increases the amount of stormwater required to be managed on a property and further restricts the release rates for all new and redevelopment projects that require a DEP House or Site Connection Proposal.  

Additionally, under the Chapter 19.1 amendments, existing requirements for areas of the city with separated sewers will expand into the areas of the city that are served by combined sewers and will now apply to sites that disturb 20,000 square feet or more of soil or create new impervious surfaces of 5,000 square feet or more.  These properties will be required to apply a green-infrastructure-first approach, employing techniques such as rain gardens, permeable pavers, and green roofs.   

In September 2020, the New York City Council passed Local Law 91 enabling DEP to move forward with the Chapter 19.1 amendments necessary to package the new USWR.  Draft rules were published in 2021, and they become effective on Feb. 15, 2022.  

DEP held dozens of briefings for public agencies, environmental stakeholders, and the private industry in advance of the rule’s publication.  Permit applicants will experience a more streamlined design, review and permit application process and benefit from the new resources included in the Stormwater Manual.   

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