Truckload after truckload, 240 cubic yards of concrete was poured into a void found beneath the movable dam at Lock 13 on the Erie Canal.
But engineers at the state Canal Corp. aren’t stopping there.
“We’re going to over-fix it,” said canal engineer Joe Moloughney while a drilling rig spun methodically, forcing a hole deep into the floor of the Mohawk River.
Workers from Tioga Construction were busy on two projects Thursday when Canal Corp. officials stopped by to check on progress fixing the void that forced the closure of a 17-mile stretch of the canal from Tribes Hill to Canajoharie.
A $15.5 million rehabilitation project begun in 2010 was under way when the workspace alongside the movable dam began filling with water. The pressure was so great it blew out a section of the coffer dam separating the work from the river and left the massive dam structure supported by only one solid pier.
The pier on the northern side was resurfaced as part of the ongoing rehabilitation, but the concrete for the pier on the southern side needed full replacement, according to Canal Corp. project engineer Kevin Mainello.
The blowout at the coffer dam was the result of a void dug out by the river beneath the center pier, leaving support below it confined to its edges.
The hole is filled now, but Moloughney said roughly a dozen additional holes are being drilled around the pier and will be filled with concrete, too, just to make sure the structure is sound.
As it stands now, it’s not sound, and the 96-year-old movable dam wouldn’t support the weight of the Mohawk River.
Drilling rigs, excavators, a crane and coffer dams that can be removed and re-used are all required for the upgrade and repair project, tools that weren’t around in the early 1900s, when the structure was being built.
“I can only imagine how they did it,” Canal Corp. Director Brian Stratton said while gazing over the massive worksite on the floor of the Mohawk River alongside the movable dam.
The fix for Lock 13 is the latest construction project on a canal that’s been pummeled by violent weather this year.
Strong current and high water levels that followed rain and tornadoes in three Capital Region counties forced the canal to shut down from Lock 7 in Niskayuna to Lock 19 in Frankfort, Herkimer County, for one day May 30, followed by lowered water levels at Lock 7 in Vischer Ferry because flashboards that maintain water levels on the New York Power Authority’s dam were battered.
Another blast of rainfall shut down the system June 11 from Lock 6 in Crescent to Lock 19.
A forecast for severe weather after the June 11 closure again interrupted the navigation season as the Canal Corp. opened the system as is done in the winter to ensure water from rainfall would flow through. There were plans to re-open the canal from Lock 8 in Glenville to Lock 15 in Fort Plain on June 28, but deadly flash flooding that claimed the life of a Fort Plain woman canceled those plans.
The canal finally did re-open July 17, giving mariners nearly two solid months of cruising time before the workspace at Lock 13 began filling with water, forcing water levels to be lowered from locks 13 to 14.
Workers attempted to fill a hole with grout over the weekend of Sept. 14 but realized the next week the issue was bigger than a leak that could be filled that way. A diver sent into the water found the massive hole beneath the movable dam’s pier, launching the construction effort Canal Corp. officials hope will be done in time for more recreation before the canal system’s annual closure in mid-November.
Work is progressing at Lock 13 and a break in the construction schedule will give boaters a chance to head east or west through the 17-mile stretch that remains closed from locks 12 through 14. The canal will open at 7 a.m. Friday, Oct. 4, and remain open through 8 p.m. Sunday, Oct. 6, but with limited depth of seven feet west of Lock 14 and eight feet between locks 13 and 14.
Moloughney said crews could get some work done on the project that weekend, but concrete will be curing, so the three-day opening won’t disrupt work too much.
Repairs will continue after the three-day opening, and it could be another three weeks before the system is fully re-opened, giving boaters about two weeks of remaining navigation season.