City Council hears flood mitigation options | Edgemont/Hartsdale

Flood mitigation was presented at a Greenburgh City Council business session on April 5 by consultants from New York-based AKRF, who are also working on the redevelopment plan of Four Corners. AKRF Vice President Justin Seeney outlined short- and long-term flood mitigation strategies for Four Corners and the greater Hartsdale Brook area.

The Hartsdale Creek watershed comprises an area covering approximately 850 acres, ultimately draining into a single “pinch point” of culverts that pass under infrastructure along the west side of E. Hartsdale Avenue.

“It’s not an insignificant flow, and as most people who’ve seen the area know, there’s no well-defined stream to carry it,” Seeney said.

According to the company’s analysis of historical topographic maps of the area from the last century, this drainage creek along E. Hartsdale Avenue was historically wider and more defined, but has become increasingly narrower and more restricted as a result of the infrastructural developments that occurred during the middle. at the end of the 20th century. As a result, existing culverts along E. Hartsdale Avenue often struggle to handle the entire area’s drainage, resulting in backups and flooding.

“We recognized that there is a need to address transportation,” Seeney said. “We are at a very small capacity given the flow we are experiencing.”

Identifying the Hartsdale Brook area’s Central Park Avenue and E. Hartsdale Avenue as particularly problematic stormwater overflow areas, AKRF presented redevelopment proposals for short-term storm flood countermeasures as well as Larger scale mitigation options for major stormwater and flood events over the long term.

Currently, the capacity of the Central Park Avenue drainage system along Four Corners can only handle about half the flow of potential smaller-scale stormwater events expected to occur in the near term. To solve this problem, AKRF has proposed installing a series of culverts to channel stormwater out of the intersection, which the company says will cost about $4-5 million. The city council is seeking federal and state grants to support funding for this development.

Similarly, with a 100-year storm prospect, the company proposed to install relatively larger and deeper culverts along Central Park Avenue and E. Hartsdale Avenue, connected by a series of wide canals that would run along the boundary between the Scarsdale Country Club golf course and the buildings on the east side of Central Park Avenue. Given the broader scope of the project, Seeney estimated a cost of between $40 million and $50 million.

To address smaller-scale stormwater issues along E. Hartsdale Avenue, AKRF proposed to use the golf course’s Hartsdale Lake as an outlet for floodwater retention through various modifications. of the depth of the lake.

“This approach which would provide about 4 feet of flood storage would more than halve the peak flow at this E. Hartsdale pinch point system,” Seeney said. “Again, this still puts us in a position where the flow to this system exceeds the capacity of this pinch point.”

The county is expected to make a decision on funding these proposals next week.

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