Written by Pat Grace Friday, 26 February 2010 00:00
A gabion is a series of rocks wrapped in a steel cage or a caged block of rocks that acts as a wall or barrier against the tide. It is a preventive erosion tactic, often used in a coastal tidal area, to protect structures from the forces of nature in breaking apart land mass and structure.
The gabions below Plandome Road North, between Leeds Pond and Manhasset Bay in Plandome Manor, have seen better days. When you drive by, just across from the entrance to the Science Museum, note the orange cones indicating danger on the sidewalk, which is also crumbling.
Plandome Manor Building Inspector Edward P. Butt provided a brief history explaining that in 1926 Leeds Pond was a saltwater coastal lake fed from Flower Hill, that Leeds Pond now acts as a repository for storm drainage run-off for Plandome Manor, Flower Hill, parts of Plandome and Roslyn; that Northern Boulevard is the high point, Leeds Pond the low point for run-off.
Sometime between 1926 and 1950, he continued, most likely for ecological reasons to control erosion of the road surface, the decision was made to desalinate Leeds Pond and make it a freshwater pond. A culvert was built as an erosion control method. A culvert is a conduit used to enclose a flowing body of water and it may be used to allow water to pass underneath a road or railway.
Records indicate, Butt said, that in 1979 or so the culvert began to deteriorate and the Town of North Hempstead commissioned emergency repair work on two culverts by using gabions that were put in place later that year. They have not been repaired since that time. It is difficult to calculate the shelf life of gabions as you are dealing with rocks, tides—with Mother Nature, but it is roughly estimated at 25 years.
Ownership can be confusing. North Plandome Road in 1979 was owned by the town, the building inspector noted, but is currently owned by the Village of Plandome Manor. And, he said, the sidewalk, on the north side of the road, is also owned by Plandome Manor.
Leeds Pond, however, is owned by the Town of North Hempstead. And the north side of the sidewalk (marsh, water) is also owned by the town. The culverts are owned by the town as are the gabions in the culvert.
About two and one-half years ago deterioration was noticed and an engineering study was commissioned by Plandome Manor—a study of the gabions and the entire culvert that they protect. The current interest is that the gabions that protect the culvert be repaired to last longer.
Ultimately, Butt explained, the culverts must be repaired by gabions, or by other means (bulkheads). Plandome Manor has been dealing with the town, Butt said, for a year and a half to clarify the matter in order to begin repairs.
According to Butt the town attorney had claimed the culvert goes under North Plandome Road and therefore the culvert is Plandome Manor’s responsibility. Meetings have been held with Town Supervisor Jon Kaiman and the town engineer, Sidney Bowne, to develop a method to repair the culvert or the inlet side of the culvert. One solution would be to permanently install bulkheads to protect the culvert. A bulkhead is a more permanent solution, maybe 40 to 50 years, costing around $150,000.
However, if temporary gabions are installed they will provide several more years of protection. The cost would be negligible as the town is capable of doing the work itself. Yet, it is still considered an emergency repair requiring the Department of Environmental Control (DEC) to approve it. It was, Butt said, presented to them as an emergency repair about 4-5 months ago.
Three agencies within the DEC must sign off on the emergency repair work: title wetlands; water quality certification; and fresh water wetlands. The DEC permit administrator is John Wieland and Feb. 10, the permit the town applied for came through. Ed Butt clarified that Plandome Manor could not apply for the permit because the village did not own the property.
The DEC permit is to perform the gabion repair work. Ed Butt said they have bought three years of time and that the town has applied to the state to receive funds to install a bulkhead.
Mr. Butt said he believes incorporated villages are more responsive to residents because they can control their building departments and provide more personal service. You can get a building permit within a week to 10 days in a village, he said, while the same permit might take 10 to 12 weeks from the town.
Work will be performed depending on the availability of the Department of Public Works and the cooperation of the weather. Butt noted winter is the worst time for erosion. Once work commences estimated time for repair work is one week.