LaBella Associates engineers Caroline Wheadon, left, and Jeff Wackowski, second from left, answer a question from Piercefield resident Carol Diamond, right, following their presentation to the Tupper Lake Town Board during a special meeting at the town hall on Monday. (Enterprise photo — Chris Gaige)

TUPPER LAKE — The Tupper Lake Town Board received an update on the Setting Pole Dam from engineers Caroline Wheadon and Jeff Wackowski at a special meeting held Monday, following a draft report that was sent to the town last week.

Wheadon and Wackowski, both with LaBella Associates, a Rochester-based firm the town hired to assess the dam’s current structural condition, provided a slate of potential project options for restoring the dam detailed in the report. They also estimated the costs of those and identified grants or other funding opportunities the town could pursue.

The Setting Pole Dam is over 90 years old, having been originally constructed in 1934. The dam received renovations in 1982, but has not had improvements made since then. There are several structural problems with the dam, such as concrete deterioration, which led the town to retain an engineering firm to devise possible fixes.

The Setting Pole Dam is owned and operated by the town of Tupper Lake. The dam regulates the water level of Raquette Pond, Big Tupper Lake and Lake Simond. Those formed from damming the Raquette River — which flows into Lake Simond from Long Lake to the south and the High Peaks Wilderness in the east.

The Raquette River then flows north from Tupper Lake, eventually draining into the St. Lawrence River near Akwesasne. The Setting Pole Dam’s access road is off of state Route 3 heading west from Tupper Lake toward Piercefield. The dam is upriver from the larger Piercefield Project dam, which is operated by Brookfield Renewable U.S. — a green energy company with numerous sites throughout the U.S. and Canada.

The state classifies dams in three categories, A, B and C, according to how much damage and risk to life and property they would cause if they were to fail. Class A, in this case, is the lowest hazard, B is in the middle and C is the highest hazard. Setting Pole is a Class A dam.

“What that means is in the event of a dam failure or a dam breach, there really wouldn’t be any downstream damage,” Wheadon said.

This is due to a combination of the riparian zone’s topography and the amount of water the dam holds back.

Given the lesser risk, Wheadon said Class A dams like Setting Pole are subject to less stringent regulations and inspection schedules by the state than Class C or B dams.

Unlike the Piercefield Project — a Class B dam — Setting Pole does not produce electricity. Tupper Lake Town Supervisor Rickey Dattola asked the engineers if it was possible to generate hydroelectricity at Setting Pole as part of potential renovations, noting that it was a question he had repeatedly been asked by constituents leading up to the meeting.

“Wherever there’s moving water, it is possible to generate power — and you have moving water there,” Wheadon responded. “But if you want to pursue that, we would recommend looking at your return on investment and what it would cost to actually implement a hydropower unit versus what generation revenue you would actually gain from that.”

She noted that Setting Pole is a low head dam and the relatively small upstream versus downstream elevational difference — and subsequent lack of electric generation — could make hydropower generation financially disincentivizing.

The engineers discussed the various methods undertaken last fall to get a sense of what shape the dam was in, both on the upstream and downstream sides. These included bathymetric survey — figuring out the sediment of the waterbody and streambed — a topographical survey of the surrounding landscape, drawing down water levels to inspect portions of the dam that are typically submerged and having divers inspect other underwater sections.

“The divers noted that there were, in some areas, large areas of concrete spalling where the surface is roughened and material has been lost,” Wackowski said. “There are large construction joints in the dam, which is common, but those joints have begun to spall, which means the material is separated from those cracks, more water is being able to pass in there and in some cases pass through.”

He added that the original foundation has partially eroded or washed away.

“Which means that there is a missing bearing surface that it should be resting against and it’s not in those circumstances,” Wackowski said.

Given the extent of the problems, the firm recommended extensive repairs.

“Due to the severity of how deep these spalls are and how deep the cracks are and how much undermining there is, we think that the best course of action would be to do a large-scale resurfacing of the dam,” Wackowski said. “Getting a minimum of 6 inches, possibly a foot, on the upstream and the downstream slope of new reinforced concrete that would be much more resistant to cracking and spalling over time.”

Councilman Tim Larkin noted that concrete today is much more consistent and higher quality than what was poured to create the dam in the mid-1930s.

The engineers also presented on the various facets that they must demonstrate dam construction will satisfy in order for the state to grant a permit for the work. The report states that these include:

¯ Normal loading — water level at normal pond elevation.

¯ Normal loading plus ice — minimum ice load of 5,000 pounds per linear foot applied at the normal pond elevation.

¯ Design loading condition — water level at the spillway-designed flood, which in the case of an existing Class A dam is the 100-year flood.

¯ Maximum hydrostatic loading condition — the upstream and downstream water elevations below the 100-year flood that correspond to the largest force impacts on the dam stability. This case only applies when the spillway is submerged, which is the case for this dam.

¯ Seismic Loading Condition — normal pond condition plus earthquake forces.

In the case of the 100-year flood, the dam would be fully submerged underwater, which the engineers said actually reduces the stress on the structure, as it minimizes the pressure differential between the upstream and downstream components. Wackowski noted that the dam’s greatest pressure differential occurs close to its normal operating flows.

“What we found is with the assumptions we had to make on the foundation conditions … all of those cases were OK by analysis other than the ice loading condition,” he said.

The engineers said that any repairs would have to demonstrate an ability to handle the ice, and increase stability, which the report delved into several avenues to do so.

“Any approach to increase the stability of the spillway will require a geotechnical investigation,” the report states. “A detailed understanding of the bedrock and sediment profiles and compositions upstream, downstream and beneath the dam are necessary to design any remedial foundation work. It is possible that the results of the geotechnical investigation will provide information that improves the stability analysis of the spillway by exceeding the assumed foundation values used, possibly to the point further stability improvements may not be required.”

The report also noted that further investigation could result in other foundational analyses previously thought to be satisfactory actually not being so.

“It is also possible that the results of a geotechnical investigation are worse than our assumed values, thus requiring improvements for design load cases other than just the ice condition,” the report states. “In this case, again, the permanent rock anchor solution would be the most applicable means to improve the stability of the dam.”

Dattola asked the engineers for a plausible timeline if the town were to act on the recommendations presented in the report.

“It might be tough to do this year, but definitely next year,” Wheadon said.

She added that she was hesitant to say this year, given that it would likely take at least two months to line up funding, necessary permits and labor — all of which would ideally be completed ahead of the summer work season to give the widest possible time window to complete the work.

In its report, LaBella estimated the total cost to be $875,500 — although the report noted that this was subject to change as it does not account for any contingencies or inflation, meaning the actual cost could be higher.

The report identifies several grants that the town could apply for, with several board members noting that the town of Tupper Lake could not otherwise budget the money for the work.

“We have to do the grants, and then we have to see how that plays out,” Councilman John Gillis said. “A lot of these grants are reimbursement grants that we don’t get reimbursed for unless we’re awarded the grant, then we spend the money (first).”

Wheadon said another staff member at LaBella oversaw the grant search and would follow up with the town again before further decisions are made on moving forward with the project.

“I understand that as a town, you may not want to appropriate (for example) a general construction contractor until you knew those grants were in place,” Wheadon said.

The draft report can be viewed online at tinyurl.com/yc5zcv92.