The six inches of rain that fell in New Jersey on April 30 caused some serious flooding in West Windsor, and though the new ponds and lakes were short-lived and the flooding caused no significant long-term property damage, motorists were stuck for hours in traffic along Clarksville Road, Alexander Road, Route 571, and Route 1; school buses were delayed; and people’s properties turned into swamps and wetlands.
The deluge also caused some residents to think back to the flooding caused by Hurricane Irene in 2011 and to wonder what — if anything — can be done to mitigate the damaging effects of Mother Nature; and what happened to the stormwater management study commissioned by the township as a result of that storm.
As for the town’s actual ponds and lakes, some fared better than others in the April 30 storm. Grover’s Mill pond did not overflow its banks, as it has in the past; whereas Lake Mercer in Mercer County Park overflowed up to the marina area, covering grass, paths, and benches near the shoreline.
“This area has too many artificially created lakes and ponds, created by damming rivers and other water supplies,” said West Windsor Mayor Shing-Fu Hsueh, whose background is in environmental engineering and stormwater management. “This can lead to flooding. In addition, you need to consider the ratio between land use and impervious area. To avoid flooding problems, you need enough surface contact between rainfall and the groundwater. Too much concrete and asphalt, which are impervious, can create surface water run-off that leads to flooding.”
“Grover’s Mill Pond is artificially created, and we always need to keep an eye on it during periods of heavy rainfall. When we see that a storm is coming, we have learned to open the dam a little bit to reduce the likelihood of flooding. Lake Mercer, in Mercer County Park, is also an artificially created lake, and it likely flooded because the county did not open the dam in time. I am sure they have some procedures in place, but maybe they need to review those procedures and develop a better process to control the dam,” he said.
Hsueh also noted that some of the flooding in West Windsor comes from being downstream from Carnegie Lake, which is primarily located in Princeton. “Carnegie Lake is also an artificial lake, which was created by damming the Millstone River. During times of severe rain, it affects Alexander Road and Bear Brook Road because the overflow causes the water to flow in the opposite direction from how it normally flows. We have no control over Carnegie Lake. That is why the township is conducting a stormwater review study, to determine how to hold stormwater better and control the backflow.”
The stormwater review study, known officially as the flood hazard assessment for Little Bear Brook and a redevelopment area stormwater management analysis, should have been completed by now.
Township officials, politicians, and residents — particularly those living in the flood-prone Penns Neck area — began discussing a township stormwater management study in the immediate aftermath of Hurricane Irene (The News, February 3, 2012).
The township did not want to wait for the federal or state governments to conduct studies, and Hsueh and township staff felt that having the results of a comprehensive township study in hand would help generate solutions as well as needed funding.
The township contracted with Princeton Hydro LLC and Storm Water Management Consulting LLC to conduct a comprehensive study. A representative from the companies gave a presentation at the September 16, 2013, town council meeting, outlining the scope and depth of the study. The companies’ representative estimated that all phases of the project would take about five months, and the entire project should be completed by February of this year. That hasn’t happened.
Township engineer Francis Guzik addressed the delay. “There have been numerous delays in this and every outdoor project due to the long winter we had, and the number of snowstorms,” he said. “In addition, the company experienced some significant staffing issues that also caused delays. These appear to be rectified now, and the project is expected to move forward quickly.”
So far, Guzik said, the engineers have completed much of the area mapping and field surveys of properties in or near the Little Bear Brook basin. They have also conducted aerial photography to get reference points and benchmarks for comparisons to the Army Corps of Engineers’ computer model of the flood plain. Surveys have also been collected from all of the affected residents.
“We expect all aspects of the study to be completed by mid-summer at the latest,” said Guzik. “In the meantime, strange as it may seem, this latest heavy rainfall may actually have been beneficial. We are now trying to determine if the flooding was caused by local issues, which would mean that we might be able to alleviate the flooding locally, rather than through a huge Army Corps of Engineers area-wide project.”
“We are reviewing the water levels during the heaviest periods of rain and flooding and comparing them to when the Millstone River crested. If the flooding does not coincide with the river’s cresting, then it may be that the Millstone River is not the primary cause of the flooding. Instead, it may be the Little Bear Brook.”
“To really determine whether this is true, I am looking for someone who has an hour-by-hour measurement of the rainfall and flooding,” said Guzik. “I have the overall measurements, but not hour-by-hour. I have checked with Rutgers and Princeton universities, as well as Mercer County Community College and state officials, but so far nobody has been able to provide an hour-by-hour reading. If anyone out there knows where I can find that data, it would be a great help if they would contact me.”
