Dredging local waterways was the flood prevention strategy most requested by Phoenicia area residents at the October 14 meeting on Local Flood Analysis (LFA), as consultants from New Paltz engineering firm Milone and MacBroom invited feedback on flood issues. It was clear that the managers of the LFA program, designed to consider the feasibility of proposed projects, see removal of sediment as a complex issue that must be approached with careful planning.
While important flood mapping and resident surveys have been conducted in Shandaken since the devastation of Hurricane Irene in 2011, supervisor Rob Stanley opened the meeting by observing, “This is not just a study. It’s about what can we do in the ground physically with the stream and the immediate environment to lower flooding in Phoenicia.” A similar meeting for Mount Tremper is scheduled for Monday, October 20, at 6:30 p.m. at the Emerson Inn.
Project manager Mark Carabetta introduced the New York City-funded LFA process, which begins with fieldwork to evaluate causes of local flooding. “We already have a lot of information through FEMA flood models for the Esopus and Stony Clove Creeks,” he said. “And we have the flood hazard mitigation plans of county and the town. We will use hydraulic modeling to assess potential strategies, so we can determine what reduction in flood levels each plan would have. Then we’ll vet costs and benefits, feasibility, and amount of public support for each project.” Possible funding sources will also be identified.
Strategies under consideration include stream channel alteration, such as widening and realignment; replacing bridges, since water can back up and cause flooding behind an undersized bridge; dredging of accumulated sediment; and floodproofing buildings in the floodplain, including increasing elevation or relocation.
Milone and MacBroom designed the 2011 channel modification at the Main Street bridge, which prevented flooding when Tropical Storm Lee arrived ten days after Irene, and the firm has worked on projects along the Stony Clove in the past three years. “We come with some knowledge from our work here and in other places,” principal-in-charge Jeanine Gouin told the 40 or so attendees, “but you have a lifetime of knowledge. We want to hear what you know and what you think will work.”
“Mountains erode. We can’t stop that,” stated Dakin Morehouse, president of the Empire State Railway Museum and owner of the creekside Phoenicia Forge property and the Roxmor Colony in Woodland Valley. “The sand and gravel go into our streams. The only thing to do is stream maintenance. We used to crush rock from the stream beds and use it for town highways. It was a natural resource, which we are deprived of now, since the 70s,” when the New York State Department of Environmental Conservation halted dredging of streams.
In recent years, especially since Irene, as the public and the town have clamored for dredging, some meticulously engineered dredging projects have been permitted by the DEC, but Morehouse and other speakers insisted that virtually the entire stream system should be dredged to prevent flooding, as was done in the past. He pointed out that when engineers were removing sediment near the Main Street bridge, he asked why they didn’t dig deeper, and they said it was because the Esopus was too high to accommodate the flow that would result from the Stony Clove. “The Esopus has to be dredged too,” he declared.
Morehouse mentioned that old photos show the Main Street bridge with 15 feet of clearance, as opposed to today’s five feet, and Gouin requested that members of the public send in historic photos of area bridges and waterways.
“Flotsam damage” was Morehouse’s next topic, as he asserted that bridges are not wrecked by water but by collision with trees carried on the racing current. He suggested that qualified contractors be given permits to remove trees that are growing along the creek and in danger of being torn up in a storm. The harvested trees could be cut up and sold as firewood.
Addressing flood insurance rates
Tom Rinaldo, who lives 50 feet from the Stony Clove in the hamlet of Phoenicia, said his basement routinely takes on water in spring and fall, but his home has never had suffered flood damage. “Is that considered flooding?” he asked.
Stanley pointed out that with the revised FEMA flood maps, Rinaldo’s house will be considered within the floodplain, and banks holding mortgages on such homes will require flood insurance, even if no actual damage has ever occurred. “That needs to be addressed,” said Stanley, adding that for homes that do flood, “a reduction of flood elevation from four feet to six inches in your home could dramatically reduce your flood insurance rates.”
Gouin said it’s possible to apply for map revisions, especially important now that insurance rates are scheduled to rise in the next few years, since the creation of the new FEMA flood maps. “If a stream is modified, we can ask FEMA to change their map. We’ve also found errors in maps. These changes would reduce flood insurance, which is going to go up. Rates could double, triple, even quadruple.”
Phoenicia water commissioner Rick Ricciardella insisted that all the streams should be dredged, perhaps as much as 15 feet, and many should be armored with walls. Chichester fly fishing guide Mark Loete said that strategy has been attempted for many years on the Mississippi, with devastating results.
“You have a natural river bed with a base of cobble,” said Gouin, explaining that removal of sediment that has accumulated on top can be helpful. “But if you go too deep, you can punch through the natural river bed into clay deposits, and now you’re creating a worse situation.” Besides creating an endless source of turbidity, exposed clay can make the banks more vulnerable to being undermined.
“You rarely find a situation where there’s one solution that takes care of all the problems,” Gouin observed. “With computer modeling, we can figure out what happens if we dig eight feet deep, dig 10 feet deep, change the bridges. We want to get to a cobble bed that’s sustainable.”
Plans to be presented, more feedback accepted
Following the discussion period, attendees moved to maps spread out on tables and showed Carabetta and Gouin where specific flooding problems need attention. At the next public LFA meeting, yet to be scheduled, the consultants will present their recommendations for projects and solicit further feedback from residents. Check the Town of Shandaken Facebook page or website, https://www.shandaken.us, for details.