Hillsdale Holding Dam Report Hearing Tuesday

An engineering firm hired by Hillsdale to study United Water's planned upgrade to the Woodcliff Lake Dam has submitted their report to the borough and officials are planning to hold a presentation at their council meeting Tuesday night.

The Woodcliff Lake Dam Study prepared by GEI Consultants of Montclair questioned the Spillway Design Flood used by the Department of Environmental Protection and engineering firm BS&J, who United Water hired for the project, in their examination of the dam, as well as the flood model used by BS&J. The model is "unsuitable for evaluation of flooding of Pascack Brook downstream of the dam because it lacks sufficient site-specific detail to reliably predict flood impacts," GEI engineers wrote.

A representative for United Water said he could not yet comment because they hadn't had time to fully examine the report.

The engineers also wrote that they believed the dam would not change flooding in the Pascack Brook regardless of United Water's plan.

"The primary cause of the downstream flooding is related to the limited channel capacity of Pascack Brook, constrictions along its length, and encroachment into the floodplain," engineers wrote. "Without significant modifications of these elements, Pascack Brook will continue to flood regardless of the dam configuration."

GEI made several recommendations, including having United Water proceed with the project.

"The Woodcliff Lake Dam needs to be rehabilitated to protect the downstream residents from a potential dam failure," they wrote.

Donald MacLachlan, the attorney for the Hillsdale & Westwood Flood Solution Group, disagreed with some of the report's conclusions, emphasizing that the Pascack Brook is carrying United Water's "commercial product."

"When we first read the report, we thought we were reading a report written by United Water's engineers," MacLachlan said. "There is much focus on what United Water is required to do by regulation, and little focus on what needs to be done to address the concerns of Hillsdale's residents."

The report also found that "there will not be a significant change in flood scenarios once the dam is reconstructed," though United Water's design will double the maximum rate at which water can exit the reservoir, as was required by the DEP.

MacLachlan said he believed GEI's engineers "completely missed" that the water level in the reservoir and the timing and speed it is released in relation to storms "is all important to how much flood water" there is in the brook.

"This modestly-funded and incomplete report is not a substitute for the enforcement of Hillsdale's land use laws and full public hearings with United Water before the Hillsdale Planning Board," MacLachlan said.

Representatives from GEI will attend the Hillsdale Council meeting at 7:30 p.m. Tuesday in Borough Hall to present their findings. Members of the public will be able to share their thoughts and ask questions about the report, though speakers will be limited in how much time they can take and officials will end the meeting at 9:30, with a possibility for the council to extend it until as late as 10:30.

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