A mere 18-inch pipe serves the entire 18.5-acre watershed above Old Colony Road, causing major flooding on Pipeline Road when it rains in Edgemont, according to Brian Zappi, the consulting vice president of ZappiCo Construction LLC, which is proposing to build four houses on Old Colony Road.
Zappi met virtually with the Greenburgh Planning Board on July 15 to present a new water drainage plan for the area. The proposal calls for a pipe to run stormwater down the hill from a headwall on Old Colony Road, under Pipeline Road and the Metro-North Railroad tracks and directly into the Bronx River.
Currently, water from the watershed above Old Colony Road spills into an 18-inch headwall under the roadway. The headwall lets out into a winding drainage ditch that runs downhill through ZappiCo’s property and the water is eventually caught by a receiving 18-inch pipe near Pipeline Road. The pipe, which juts into the property at a diagonal, is often clogged with debris, forcing water to shift its course onto the roadway.
“I think what they are proposing [is] a benefit to the existing town’s infrastructure and I think this would resolve a lot of the drainage issues that we have experienced on Pipeline Road,” said town engineer Brian Simmons. “It seems that a lot of the water that enters onto Pipeline Road comes as a result of the open channel basically not making it into the existing 18-inch pipe, and as a result … overflowing onto Pipeline Road.”
Simmons said enclosing the system with a drainage manhole and then piping the water across Pipeline Road would convey it a lot more efficiently.
After purchasing three parcels of land on Old Colony Road in February 2017, ZappiCo, a Hawthorne-based real estate developer, obtained approval from the Greenburgh Planning Board to build a house at 100 Old Colony Road. A year later, ZappiCo met with the board again to present a plan for 10 houses to be built on the 2.6-acre site. ZappiCo also submitted a wetland watercourse clearance form with a proposal to pipe the existing watercourse — an intermittent drainage ditch. The piped watercourse would connect to an existing 18-inch pipe that runs parallel to Pipeline Road and the water would eventually spill out into an open ditch along the Metro-North Railroad tracks.
The developer downsized the concept to just four houses and submitted a formal application to the planning board. At a meeting in April 2019, the board raised multiple concerns about the proposal, including water drainage and runoff onto Pipeline Road. During a public hearing, Zappi told the board the drainage ditch snaking through tax lots 11 and 12 was servicing the entire watershed above Old Colony Road and he said sediment was building up in the diagonal 18-inch pipe off of Pipeline Road and causing significant flooding.
Pipeline Road, which runs parallel to Old Colony Road below a steep incline, is a major thoroughfare for Edgemont residents that connects the hamlet to the Hartsdale train station, but it floods during heavy rain storms.
“This is all offsite water that’s being handled and treated. None of this water is from the project or involved with the project,” Zappi said, referring to the drainage plan, which is designed to handle all of the upstream water currently flowing out onto the property.
The proposed drainage system would not service the four houses ZappiCo plans to build on the site, as the houses will have their own water storage units rated for a 100-year storm. The system would service all the water draining from Old Colony Road, Midvale Court, Club Way and portions of High Ridge Road.
In the new plan, ZappiCo proposed connecting a 30-inch pipe to an existing 18-inch pipe that connects into a headwall on Old Colony Road. The 30-inch pipe would run down the hill and connect into a manhole on Pipeline Road. Two 24-inch pipes would then run under Pipeline Road and connect into a manhole on the other side of the roadway. Two 30-inch pipes would then run under the Metro-North Railroad tracks and spill out directly into the Bronx River.
There will be an easement around the pipes throughout the property to allow maintenance by the town.
According to Zappi, two 24-inch pipes are needed under Pipeline Road due to an existing water line, which would need to cross the two pipes.
Based on a preliminary analysis ZappiCo gave the town, the 30-inch pipe through the subdivision would be adequately sized to meet the town code’s requirement for a 10-year storm event, Simmons said.
“I don’t want to say [this is] the final iteration of the plan, but this is the plan where we have a verbal informal approval or OK from both Metro-North and from the town engineering department,” said Zappi.
Zappi said he, the town and Metro-North were still going back and forth on who would bear financial responsibility for the project.
Ross Vinograd, who co-chairs the Greenridge Civic Association committee that monitors the issues on Old Colony Road, said the association wants the town to solve Pipeline Road’s flooding issues.
“I think the town has a responsibility to address the Pipeline as a whole,” Vinograd said on behalf of the association. “Relying on ZappiCo to fix one piece is nice but I think it has opened up an opportunity to address the entire Pipeline.”
Although Vinograd said he has seen flooding on the roadway in the area where the drainage ditch lets out into the 18-inch pipe, he has also seen water pooling throughout the roadway.
“There’s no clarity as to how the thing’s getting paid for,” said Vinograd. “The Pipeline today has no drainage so if they’re going to build a conduit under the Pipeline and under Metro-North railroad to the Bronx River, then the town should theoretically be considering how they’re managing Pipeline holistically as a result of this initiative.”
Walter Simon, chair of the planning board, said if the board were to approve the project, it could do so on the condition that the drainage proposal be implemented. If the town and ZappiCo couldn’t agree on who’s to pay for the drainage and the drainage enhancements were not made, then Zappi theoretically would have to bring the site plan application back to the planning board for reapproval.
ZappiCo’s permit application was already submitted to Metro-North, Zappi said, and he expects to receive a response in about a month.
Aaron Schmidt, the deputy commissioner of community development and conservation, said ZappiCo would need to revise the plan, including the application materials for a staff review, and to see if any other agencies besides Metro-North would be involved.
A planning board hearing on the updated application is scheduled for Aug. 5. A public hearing will be scheduled on a future date.