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Lopez: Scrutinize Gilboa Dam

Legislator worried flood risks remain high in Schoharie Valley

Tuesday, October 11, 2011
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— Republican state Assemblyman Pete Lopez wants the state Legislature to scrutinize the safety of the 84-year-old Gilboa Dam and the massive reservoir that looms over more than 32,000 residents in the Schoharie Valley and two cities downstream.

One of hundreds of homeowners routed by flooding from Tropical Storm Irene, Lopez, of Schoharie, is requesting a joint hearing of the Assembly and Senate environmental conservation committees to probe the dam’s structural integrity, emergency and safety procedures, its use for flood control purposes, indemnification and other issues.

Owned by New York City and part of its water supply system, the 19.5-billion-gallon Schoharie Reservoir is held back by the Gilboa Dam, a concrete structure deemed inadequate by engineers in 2005.

The discovery that the dam’s integrity could be threatened in a severe flood prompted a $24 million emergency stabilization project that included drilling holes through the dam and mounting post-tensioned cable anchors to bedrock beneath it.

A $350 million reconstruction project was under way at the dam when Irene hit the region.

Lopez on Monday said an official from the New York City Department of Environmental Protection called Schoharie County’s emergency center on Sunday, Aug. 28, telling officials to call for an evacuation.

Deputy DEP Commissioner Paul Rush told officials the low-level sensors — tied into the post-tensioned anchors — were all triggered as floodwaters surged over the dam.

“So something’s happened, there’s movement at the base of the dam,” Lopez said in recounting what he heard that frightful day. “He then went on to say we’ve lost all visuals, our remote sensing equipment has all failed, and the water’s coming over [the dam] faster than the ’96 flood,” Lopez said.

“I said, ‘So you’re basically telling us to get the hell out of there,’ [and] he said ‘yes’,” Lopez said.

NOWHERE TO GO

By the time officials hit the button to sound the series of 20 sirens that were installed after 2005 to alert residents of potential trouble with the dam, some had nowhere to go.

High winds from Irene, coupled with massive amounts of rainwater overcoming culverts and streams, made travel difficult, if not impossible.

“By the time the alarms went off, roads and bridges were already compromised. Trees and telephone lines were blocking the roads. There was no way out, even if you wanted to get out,” Lopez said.

“My wife and daughter ran up the mountain to get as far up the mountain from our house as they could,” he said.

The 20 sirens, believed to have saved lives in creekside communities, were put out of commission by the hurricane — at least one was torn out of the ground by the raging Schoharie Creek.

Without those sirens, firefighters and emergency officials were forced to employ the reverse-911 telephone system and go door to door to evacuate residents a week later when Tropical Storm Lee dumped more rain on the watershed.

Dam Concerned Citizens, a local group that formed after the 2005 announcement calling the dam’s design into question, supports Lopez’s call for a state Legislature investigation because residents don’t trust the New York City Department of Environmental Protection anymore, DCC member Howard Bartholomew said.

“I wouldn’t buy a used car from any one of those guys now,” Bartholomew said on Monday.

It wasn’t until Barthlomew and his wife, Sherrie, started asking questions about a 200-foot-long notch cut into the top of the Gilboa Dam for the reconstruction work that officials in Schoharie County became aware of it.

The bulkhead covering the notch failed and caused a surge of water to rush downstream — something officials couldn’t plan for because they didn’t know the bulkhead and notch were there.

Bartholomew said Dam Concerned Citizens is calling for an inquiry into why that information wasn’t passed along to county officials, to the New York Power Authority that operates a hydroelectric facility just downstream of the Gilboa Dam, and to the U.S. Geological Survey that operates streamflow gauges and notifies the National Weather Service of flooding.

“We want the city of New York to operate taking into consideration the fact that their responsibilities do not end at the base of that dam,” Bartholomew said.

The “extensometers” connected to the massive cables that gauge movement of the concrete dam apparently failed about the same time as gauges that measure the flow of water failed that Sunday, he said.

Despite a study put out by the DEP in the days after Tropical Storm Irene saying the dam is fine, Barthlomew said Dam Concerned Citizens is demanding an independent review of all the data generated that day.

“We want to have the record of what those instruments indicated studied by an independent third party. We want to have them look it over and see if indeed … there was a failure of the instruments — or a failure of an anchor or something,” Bartholomew said.

EVACUEES UPROOTED

As floodwater from Irene gushed into Schoharie Valley communities, dozens of evacuees had to be uprooted from emergency shelters after gauges that monitor flow over the Gilboa Dam were destroyed, leaving no way to determine the dam’s ability to hold its water nor how much was flowing over it.

The Schoharie Reservoir has its own estimated flood inundation zone that’s greater in extent than Irene’s flooding, which forced officials to evacuate shelters like the Esperance Elks Lodge and the Schoharie Central School in case the dam broke.

A catastrophe at the Gilboa Dam would mean serious issues for people miles to the north in the cities of Amsterdam and Schenectady — two populated areas along the Mohawk River that lie within reach of floodwaters from the Schoharie Creek, which is the river’s primary tributary.

There are maps available showing the devastation a dam failure would bring along the Schoharie Valley, but none have been developed for Amsterdam and Schenectady.

Bartholomew said Dam Concerned Citizens is meeting this week and a request to county officials for additional maps is one topic planned for discussion.

“I think it would be very, very useful. Then, they could design escape maps,” Barthlomew said.

In its current condition, the Gilboa Dam isn’t capable of getting rid of much water. A low-level outlet installed during its construction eight decades ago is now covered in silt and unusable.

Another low-level outlet to be channeled through the mountainside is part of plans for the ongoing reconstruction project and could be used to benefit communities if it’s employed early enough, Barthlomew said.

“What we would like to see as a result of these hearings is some legislation enacted regulating the operations of the NYCDEP in the area of release of water prior to the appearance of a storm,” he said.

“Once they have a low-level outlet in the dam, they would have the capacity to draw the reservoir down several feet pre-emptively,” Barthlomew said.

Such a system wouldn’t have done much with the magnitude of water that poured over the region from Irene, he said.

But during a “regular” flood event, the outlet would be sufficient to lower the reservoir’s holdings over a period of five days before massive rainfall, thereby heading off a spillover at the Gilboa Dam and giving people time to react.

FLOODING FOCUS

Discussion over New York City’s role as it relates to flooding has been ongoing for as long as people have been talking about the concrete monolith’s threat to those downstream.

“This is continuation of a dialogue that has existed with the city of New York for decades, and it’s the issue of their mission of providing drinking water to 9 million people in the city of New York versus what we feel is their obligation of managing the dam for flood control purposes to protect the life and property of the tens of thousands or more people downstream,” Lopez said.

“And that includes the piece that we don’t even want to think about: the potential catastrophic failure of that dam, sending a pulse of over 20 billion gallons of water between the Gilboa Dam and the Pumped Storage Project and a tidal wave down the Schoharie Valley to Amsterdam and surging into Schenectady,” Lopez said.

“This is a profound impact that we live with every day, and Irene and Lee have done nothing more than amplify and highlight how sensitive this issue is,” he said.

But, during that discussion, the city’s DEP has contended the agency’s purpose is for drinking water, not flood mitigation.

“They say, ‘No, we don’t do flood control, we’re not interested in it, we’re not required to’,” Lopez said.

“My respectful response is whether you want to or not, you must. For the people downstream, you must, it’s your obligation and your responsibility,” Lopez said.

Lopez said he sent a letter to the state Assembly’s Environmental Conservation Committee Chairman Robert Sweeney to request joint hearings and he awaits word on a decision.

The New York City Department of Environmental Protection’s press office was closed for the Columbus Day holiday Monday.

Efforts to reach Schoharie County Board of Supervisors Chairman Harold Vroman were also unsuccessful Monday.

Maps showing where floodwaters would surge in the event of a catastrophe at the Gilboa Dam can be viewed on the Internet here .

 
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comments

October 11, 2011
11:15 a.m.
MDogsMom says...

Map web addy is bad - can you post a link in the story?

October 11, 2011
12:33 p.m.
jpatrick says...

The link to the maps has been added.

Judy Patrick
Managing editor

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