Millions of dollars spent on Lake Nighthorse to fix design deficiencies, other problems

FARMINGTON — No water will be pumped from the Animas River into Lake Nighthorse this year.

That is because the headgates at the dam southwest of Durango, Colorado, have to be destroyed and replaced, according to Animas-La Plata Project Operations, Maintenance and Repair Association General Manager Russ Howard.

Howard told the San Juan Water Commission on March 4 that the $6.5 million project is needed because the design was not appropriate for the location. This work is being done by the U.S. Bureau of Reclamation.

He said work was also done prior to choosing to replace the gate. Howard said $1.5 million was spent “over the years trying to put a Band-Aid on something that shouldn’t have been there in the first place.”

When asked about the gate, Howard said the design, known as an Obermeyer, gate is not a bad design, but it was not appropriate for the Animas River.

U.S. Bureau of Reclamation spokeswoman Justyn Liff  agreed with Howard that the design was a good design but was not compatible with the Animas River’s conditions. She said on another river it would have worked fine, but the bureau had not realized how muddy the Animas River is.

The amount of mud in the Animas River caused problems and filled the pipes with mud.

In addition to the $6.5 million replacement of the headgates, Liff said the the gate's original construction, retrofits to keep them operational and engineering studies and design cost about $6.2 million. 

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Howard expressed some concerns that the coffer dam constructed to isolate the intake from the Animas River while the construction is underway could cause some flooding in Santa Rita Park in Durango, Colorado, this spring. Liff said the Bureau of Reclamation is monitoring conditions and, based on current projections, it does not anticipate flooding.

Howard: $15 million spent fixing problems identified since 2012

Over the years, Howard has discussed numerous things with the water commission that had to be corrected at Lake Nighthorse. He said these include design deficiencies and overlooked engineering problems.

Howard said the operations, maintenance and repair association lets the Bureau of Reclamation know about these problems and they are fixed without the member entities like the San Juan Water Commission having to reimburse the cost of fixing them.

However, he said since 2012 the U.S. Bureau of Reclamation has spent $15 million on those types of projects.

Liff said she was not sure about the $15 million number that Howard cited.

Liff said the entire project to construct Lake Nighthorse cost $600 million. She said it is not uncommon on large, expensive projects like the reservoir to have things that require fixing after it is completed.

Problem with pipes could have led to catastrophic motor failure

Howard said the system of radiators and plumbing used to keep the motors cool is one area that had a design problem.

The eight motors in the plant each have coolers to keep them from overheating. The motor coolers are water operated. Raw water is filtered and then sent into a radiator. The radiators are located directly above the motors.

"If you develop a leak in one of these radiators, it starts leaking directly into the motor," Howard said. "And if you have a defect in your insulation, you could have a catastrophic failure of a 6.25 kV electrical motor. It would not be pretty."

Howard said there were sections of the plumbing connected to the radiators that were deteriorating and welds were coming apart.

One of the problems discovered was that there were dissimilar metals placed together without isolation, creating what is known as galvanic corrosion.

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"You have to isolate. You're basically creating a battery when you have dissimilar metals together and then you stick them in water," he said. "You generate an electrical current and it seeks the weakest point and, as it leaves the metals, it takes material with it."

New headgate design means faster closure, safer operations

Lake Nighthorse stores water that can be used during droughts. Howard said there will still be enough water in the reservoir if needed this summer despite not being able to pump from the Animas River.

The construction on the headgates is happening across the river from Santa Rita Park.

The original intake included three gates opened using bags that fill up with air or deflate.

“It took hours to close a gate,” Howard said.

This could create problems if something like a gasoline spill occurred upstream of the intake.

The new design will use electricity to open and close the gates, which means they will close much faster.

The bulkheads in the intake structure were dangerous to remove, Howard said. He said cranes must lift vertically, but the bulkheads were installed at an angle. That put pressure on the crane and meant that, once the bulkhead was lifted out, it would swing dangerously like a pendulum.

Other design problems made it so the Animas-La Plata Project Operations, Maintenance and Repair Association essentially operated the reservoir without headgates, meaning additional sediment entered the dam.

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“It will hopefully be this time next year when we can call this project complete,” Howard said.

Hannah Grover covers government for The Daily Times. She can be reached at 505-564-4652 or via email at hgrover@daily-times.com.

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