The early 20th century English writer and poet Rudyard Kipling once warned his country about complacency in the face of history: “Ere rivers league against the land/In piratry of flood/Ye know what waters steal and stand/Where seldom water stood.”
West Windsor has witnessed on many occasions the lessons of history pertaining to flooding. During Hurricane Irene in 2011, Little Bear Brook, which runs into the Millstone River that empties into Carnegie Lake, flooded out Washington and Alexander roads and many areas in between, including the tunnel that runs under the tracks at the Princeton Junction train station. At that time a study was promised to determine what could be done to ameliorate the flooding. But as recently as May 1, with no study yet in place and no remediation efforts begun, a major rainstorm ended in similar though less devastating results.
Realistically, what can actually be done to prevent it? And what has kept the township from acting to fix the flooding problem?
There are no easy answers, but at least the magnitude of the problem began to come into focus at a June 30 meeting reviewing a long-awaited flood and stormwater assessment study by Storm Water Management Consulting LLC and Princeton Hydro LLC, two affiliated companies based in Ringoes. The meeting at the municipal building was moderated by Pat Ward, director of community development, and Francis Guzik, township engineer.
Joe Skupien of Storm Water Management suggested several general strategies for flood mitigation — none was a quick fix.
The strategies included approaches such as upstream water storage for the Millstone (dams and lakes, for example), the lowering of downstream starting water elevations (pre-drain Carnegie Lake before major events), modification of the Route 1 bridge over the Millstone to reduce the restriction there, levees and floodwalls (along Little Bear Brook), road raisings (Washington and Alexander roads), an enhanced flood warning system (using the town’s website), and finally individual structural floodproofing by various means (for example, the house on Alexander Road that recently was lifted to a second story level to avoid the next major flooding event).
Some of these would involve significant expense by other jurisdictions as well as West Windsor, even assuming they could be carried out at all. Hard choices will have to be made.
And the problems could get worse unless full provision is made to properly hold and dispose of the excess water that will inevitably result from two proposed new developments.
The former American Cyanamid property, 650 acres between Route 1 and the Amtrak line, crossing Clarksville Road, is now being considered for development. Mostly farmland and grassland at present, it’s drained by Duck Pond Run and to a lesser extent (to the south) by the Assunpink Creek, which passes through Trenton to the Delaware. Increasing runoff into these streams could have significant impacts downstream, including Carnegie Lake and possibly even the Millstone, by backwater effects.
Further along on the development pipeline are 24 acres on Washington Road near the Princeton Junction train station, where council approvals are in place for a substantial mixed use residential, retail, and office development. A provision in the settlement agreement with the development’s owner — Intercap at the time — allowed up to 95 percent improvement coverage in these critical 24 acres. This much coverage could lead to further flooding problems in the future. This site is still subject to planning board, NJ Transit, and environmental approvals before any construction could begin, and funding would have to be sought for the projected Vaughn Drive connector.
Mary Paist-Goldman of Princeton Hydro continued with an update on the regional stormwater management plan for that redevelopment area. She presented two maps showing locations where new detention basins might be placed, one with existing buildings and one with projected buildings. Her preliminary calculations suggested that sufficient water storage to avoid increasing existing problems with Little Bear Brook could be achieved with either seven acres of basins with a three-foot capacity or four acres with a six-foot capacity. The locations in either case would involve significant land acquisition issues impacting multiple present ownerships.
Even the implementation of the study has a long history. The $250,000 received from Toll Brothers to address storm water flooding issues in the Windsor Haven area was partitioned by council in February, 2013. Of this $100,000 was reserved for a formal flood study, $69,556 was to be remitted to the Windsor Haven Homeowner’s Association plus another $10,000 in legal fees, and the remaining $70,444 was retained by the township for “future storm water management and flood mitigation.”
On August 5 of last year the above $100,000 was applied to the present study, which together with an additional $36,290 of township funds made up the contract price of $136,290 including a 10 percent contingency. Councilman Bryan Maher stated then that the owners of the 24-acre Washington Road property — until recently InterCap — ought to be funding part of this study, as some of the results would directly concern their property rather than just the lower Penns Neck area near Little Bear Brook. However, attorney Steve Goodell [of the Herbert law firm representing the township] said that the appropriate time to request a contribution from them would be if and when any actual development plan came before the Planning Board, a position with which Mayor Shing-Fu Hsueh agreed.
The study was originally due within 150 days of council approval, but this was changed on September 3 to 150 days after actual project initiation. Paist-Goldman and Skupien gave their introductory presentation at a council meeting on September 16. At the June 30 meeting, Skupien apologized for the delay, which he attributed to staffing issues and the severe winter that limited field activities.
The bulk of Skupien’s long-awaited presentation consisted of data and charts about the levels to which the Millstone River and Little Bear Brook would rise for different flood categories.
He rated the most recent May 1 flood as a 5 to 10-year event — in other words, that level of flooding has a 10 to 20 percent chance of happening in any given year. Though the May 1 flood was inconvenient for commuters and West Windsor residents, it did have a silver lining. The flood allowed Skupien to get real-time data and photographs that helped correlate this amount of rainfall, 5.3 inches in 36 hours, with the degrees of actual flooding along Little Bear Brook, the Millstone River, and Carnegie Lake.
When questioned later about how he would characterize Irene, one that came up to at least the 500-year mark on maps and photos, Skupien said that it even might have been a “1,000-year” flood.
With 78 square miles of upstream drainage area, the Millstone dominates the West Windsor scene even before Little Bear Brook enters with its relatively puny 2.9 square miles of drainage.
Skupien explained that when the Millstone is high, Little Bear Brook is stymied in the same way that cars trying to enter Route 1 from Fisher Place back up during the morning rush hour. Any partial obstructions in the brook may somewhat hinder its drainage during severe events, but the main problem is the Millstone. The result is that lower Fisher Place and Washington Road are expected to have some flooding with even four-year rain events, while some structures there will have issues at 5 and 10-year intervals, on average.
Other problems with the Millstone relate to a partial dam effect at the Route 1 bridge and its difficulty emptying into Carnegie Lake when the lake’s water level is already high. Skupien took photos of the Carnegie Lake dam on April 30 from the Princeton side before the flooding and also on May 1. The water was so high on May 1 that the dam completely disappeared and the level on the far shore was many feet higher than the day before.
Separately, photos of lower Harrison Street (at the Sunoco station) taken by resident Pete Weale on August 28, 2011, when the Route 1 bridge was closed due to Irene show that Harrison Street, normally at an elevation of about 58 feet, had 3 to 4 feet of water on it as judged by the level on flooded cars parked on the other side of the street. Harrison Street is on the downstream side of the bridge, which means that the part of the Millstone from the bridge to Carnegie Lake, and likely the lake itself, was at least 61 to 62 feet.
Washington Road crested at about 63 feet as judged from photos taken by resident Susan Conlon. The very low gradient all along the complete drainage path must have been the main reason for West Windsor’s major flood then, and certainly contributes during lesser events. Little slope translates into little flow.
During the public question period, resident Andy Bromberg asked if mathematical modeling of the Millstone River watershed would be helpful in forecasting future flooding potentials. Once a working model had been constructed, available software could project resulting downstream flow and accumulation scenarios from various rainfall events. The model could be calibrated using data that Skupien generated during his study.
Skupien and Paist-Goldman should be issuing their full report by September. Their presentations at the June 30 meeting have also been posted on the township website.
John A. Church has lived in West Windsor since 1966 and has been a homeowner here since 1969. A Ph.D. research chemist, he retired in 2001 from the Colgate-Palmolive Company and is a 50-year member of the American Chemical Society. An editor of his college newspaper, he enjoys keeping his hand in local news media. He has written three books and edited several others, including the memoirs of his good friend Tai Shin of West Windsor. His most recent editing project was a 92-page report on the possible restoration of the Grover Homestead. He attends most council meetings and speaks on topics of current interest.
