Though it’s been derided as “rickety” and “pathetic,” the 85-year-old Gilboa Dam stood firm — but flexible — against record-breaking floodwater.
Engineers laid out some post-flood data for Schoharie County supervisors Friday while fending off questions about the dam’s ability to hold back 19.5 billion gallons of water during a flood.
While hundreds continue to repair their homes or find a place to endure the oncoming winter, county supervisors heard positive news about the dam and the Enterprise Products/Teppco pressurized propane pipeline that was unearthed in three spots by raging water.
The region also heard more positive words as federal lawmakers announced the Federal Emergency Management Agency will provide individual assistance disaster aid to Schoharie County residents affected by Tropical Storm Lee. Also Friday, FEMA announced governments in Schenectady County are now eligible for public assistance for the same storm.
But an update U.S. Rep. Paul Tonko, D-Amsterdam, provided to Schoharie County supervisors was a bit more somber. The recent battle in Congress that provided more disaster aid to FEMA will be revisited in November when that temporary legislation expires, Tonko said. And some in the federal government are unwilling to even consider releasing more funding for disaster recovery.
Residents have questioned why the Schoharie Reservoir wasn’t drained when forecasts were calling for a possible hurricane and it’s been suggested that extra capacity in the reservoir might have given more time for pre-flood preparation.
John Vickers, an engineer with the New York City Department of Environmental Protection, said it would take 45 days just to drain the massive body of water, which is part of the city drinking water system. And 45 days before Aug. 28, 2011, “would have been before [Hurricane] Irene started to form off the coast of Africa.”
Even if it could be drained faster, engineers put together a hypothetical model and determined an empty Schoharie Reservoir would have eventually dumped 85,000 cubic feet per second of water over the Gilboa Dam because of the massive amount of rainfall that came down so quickly. To put that into perspective, water over the Gilboa Dam during the flood of 1996, considered the “big one” up until now, was measured at 70,800 cubic feet per second.
During Tropical Storm Irene, engineers estimate the Gilboa Dam saw 110,000 cubic feet per second rushing over the top of it.
It may be considered old, but concrete “gets better with age” as it cures and the Gilboa Dam “performed very well,” said Vickers, the DEP’s eastern operations chief.
He was joined by DEP regional engineer Mark Suttmeier and engineer Robert Kline, Gannet-Fleming’s design manager for the dam’s ongoing $350 million reconstruction project.
Kline told supervisors that sensors on the dam showed it moved — but that happens. It flexed under the fierce pressure of unprecedented rainfall much like a plank in a floor flexes then goes back where it belongs, he said.
When engineers realized the concrete dam didn’t meet modern design standards — there was concern a massive flood would push the dam aside — the DEP installed 80 cable anchors through the dam and mounted them to the bedrock below.
Though he didn’t say what would have happened if the anchoring system were not in place when Irene raged through the valley, Vickers said those stability improvements “we believe were put to good use.”
The work added the equivalent of 150 million pounds to the dam’s strength, and upgrades to be included in the reconstruction project will add another 100,000 cubic yards of concrete or 234 million pounds of extra load to hold back the Schoharie Reservoir, Vickers said.
Once the murky floodwater receded, a more thorough inspection revealed some scouring and damage to the concrete steps that lead to the “plunge pool” where the water lands once it goes over the dam, Vickers said. Repairs are ongoing for that damage, and despite the setbacks in August and September, the construction timetable is still on target for completion in early 2017.
In an effort to instill confidence in the team that’s responsible for the dam that towers above the Schoharie Valley, Vickers displayed a list of engineers and scientists involved in planning the upgrades, coordinating construction and checking each other’s work. The list showed people with decades of experience and education.
And Vickers told the group — including several representatives from watchdog group Dam Concerned Citizens — these people care about their work and the safety of residents.
“We really do take this seriously,” he said.
Hurricane Irene unearthed the Enterprise Products/Teppco pressurized propane pipeline in three places but the 8-inch steel line that travels from Watkins Glen to Selkirk is secure, according to engineer Brian Pausley, Albany area manager for Enterprise Products.
The pipe killed two people when it exploded in North Blenheim in 1990 then it blew up again in Delaware County in 2004, destroying a home. It sprang a leak last year, forcing the evacuation of a 3-mile area.
In the aftermath of that incident, residents and officials complained about the pipeline visibly sticking out of the Schoharie Creek and Enterprise Products officials commissioned a repair that entailed placing a massive concrete mat on top of it.
The pipeline was exposed during the recent flooding near the Westkill Creek off of Westkill Road, at the Schoharie Creek along Bear Ladder Road, and also just east of Keyserkill Road, Pausley said. One of the exposures showed some dents, presumably from rocks pushed downstream during the flood, but the pipe was inspected and determined to be OK, he said.
These exposures are not uncommon, Pausley said, but the Schoharie and Westkill creek have both exposed the pipeline so the company is eliminating this situation altogether. They are drilling a hole 50 feet deep and drilling a channel underneath both creeks with plans to run the pipe completely underground, eliminating the chance future flooding will expose it to rushing floodwater and debris.
Pausley said it depends on the weather but he’s hoping to get the pipes re-routed to their new, safer locations by winter. The pipeline was shut down for nearly a month by the flooding. Gas started flowing again Sept. 28, Pausley said.
U.S. Sens. Charles E. Schumer and Kirsten Gillibrand issued a statement Friday announcing Schoharie County residents affected by Tropical Storm Lee are now eligible for federal individual assistance.
Officials have said some people in Schoharie County quickly replaced their homes’ heating systems after Tropical Storm Irene only to have them inundated the next week when Lee dumped more rain on the region.
Damage from Lee was pronounced in Schenectady County, with cut roadways and washed out culverts. Municipalities here will be able to get public assistance from FEMA for debris removal, emergency protective actions and repair and replacement of damaged facilities.
Earlier, residents in Schenectady County were made eligible for individual assistance and governments in Schoharie County were offered public assistance for Tropical Storm Lee.
“The devastation in the Capital Region as a result of recent tropical storms is unimaginable, and it’s been abundantly clear that the region needs the full support of the federal government to begin rebuilding,” Schumer said in a news release.
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Categories: Schenectady County