Fixed, not by a dam site

By DAVID HULSE

FORESTBURGH, NY — They’re feeling better about it and they have a plan for repairs, but Mirant managers are still worrying about the impact of a major rainfall on the Swinging Bridge dam. They have suspended all recreational activities on or near their three Mongaup River reservoirs until further notice.

Assemblywoman Aileen Gunther hosted an informational session on May 25 with Mirant officials, their contractors and regulatory officials. More than 50 people jammed the bay of the Forestburgh Fire House, many of them Swinging Bridge property owners wondering if they would have a lake this summer.

The short answer was no.

Despite the assurances of one property owner who said he “knows where all the stumps are,” Swinging Bridge Manager Elliot Neri said Mirant is suspending its recreational plan for land and water uses at Swinging Bridge, Mongaup Falls and Rio for the summer. While officials insist that the dam is stabilized, Neri said that should the dam fail, engineers believe the ensuing flood would break the two downstream dams.

“There’s a difference between stable and safe. It will be safe when it handles [the lake’s standard water elevation] 1,065 [feet above sea level] again,” Neri said.

Asked why the Delaware has reopened to boating traffic at the confluence with the Mongaup, officials said the National Park Service was satisfied that the dam was stable enough to be in “their comfort zone.”

So far, the lake has been lowered to 1,047 feet. “We’ve yet to determine if it needs to be drawn down further,” said Constantine Tjoumas, the Federal Energy Regulatory Commission’s (FERC) Director of the Division of Dam Safety.

Neri said that there is some concern about endangering the stability of the dam in drawing the lake down too much. The earthen core is normally partially saturated with water.

Regarding the repair work, Neri said that a board of consultants, including engineers from FERC and the U.S. Environmental Protection Agency, has done a preliminary review of Mirant’s plans for investigating the interior structure. Mirant is hoping to finalize plans in about three weeks and begin an expected 80 days of repair work.

So far, the work has been external. “Now we’re going to look at the core,” Neri said.

Consulting engineer James Cole said instruments to monitor water level have already been “nested” around various locations in the dam. Internal inspection would require the drilling of bore holes of about six inches in diameter. Cole reported that an exterior inspection revealed four holes in the penstock and “a number “ in the diversionary tunnel buried under the penstock.

The cause of the sink hole atop the dam is still unknown. While the hole did not appear until May 5, a month after the April flooding, Neri said the dam’s problem might have been “a delayed reaction,” from the heavy April rains. Neri said the company continues to have concerns about an unusual rain event during the repair period.

Tjoumas said the consulting board is a FERC requirement. “We want to be comfortable that what’s done is safe, even the act of drilling. I don’t want some activity to fail the dam,” he said.

Tjoumas said there was great concern because the 1920’s dam construction style is obsolete. “In the 1970s, we learned that it was not the type you wanted to build. We’ve had problems,” he said.

While he said the dam would not need to be replaced, he said engineers will be “trying to figure out what kind of a fix is necessary.”

Tjoumas said the hydro-fill construction style, using water to dump rock and soil leaves an interior core of finer material, which liquefied during an earthquake on one occasion. The repair work would address the construction’s faults and correct them, he concluded.

In answer to Thompson Councilman “Peppy” Satenstein’s query about the bankrupt utility’s finances, Mirant-New York Vice President Lee Davis said the corporation is emerging from bankruptcy and has $1 billion cash reserve. “I don’t think this is going to be a billion-dollar project,” he added.

Satenstein said the Town of Thompson would be available to assist with the work in any way possible.

A spokesman for the Sullivan County Sportsmen’s Federation volunteered the group’s help in aiding lake fish, which might suffer stress from shallower warmer water.

“Mirant’s been a good neighbor,” one resident told the audience. “Let’s stop the anxiety. It’s been a rough year. We’ll get through it,” he said.

Mirant has established a toll-free information line to update progress on the project at 888/326-3389 and Tjoumas said that the FERC’s website would also carry information about the project at ferc.gov.