The regulations require the operator to do daily, quarterly and annual inspections, while the state must make monthly checks. MSHA relies partly on data provided by the companies to spot problems, which critics see as a weakness in the system.
Spadaro is not the only one to question the soundness of impoundments.
Retired miner-turned-activist Joe Stanley raised concerns over the Brushy Fork impoundment in southern West Virginia last year, but his complaints were dismissed by state regulators, and their decision was upheld by the federal Office of Surface Mining Reclamation and Enforcement.
Stanley called Bushy Fork "the biggest and the baddest" of all impoundments and said MSHA inspectors routinely found violations during its construction. But fines weren't levied and construction wasn't stopped.
"They just let them keep going, and then they say, 'Well, there's no way to fix this now, so let's just change the plan.' They're hodge-podging this stuff."
He heavily criticized state regulators and said if it weren't for MSHA, "I think all the damn things would fall down. Immediately."
Just two years ago, MSHA said it had improved oversight of impoundments, with better training and a new handbook on dam management.
The agency made the comments on the 10th anniversary of a disaster in Martin County, Ky., when slurry burst through the bottom of the Martin County Coal Corp.'s 68-acre holding pond, sending black goo through an underground mine and into 100 miles of waterways. The spill in 2000 polluted the water supply of more than a dozen communities and killed aquatic life before reaching the Ohio River.
Massey Energy eventually paid $46 million for the cleanup, along with about $3.5 million in state fines and an undisclosed sum to residents.
Spadaro, who helped investigate that accident, believes MSHA could go further, requiring better engineering evaluations of potential weak spots in impoundments.
He claims regulators at all levels continue to go easy on the industry in favor of coal production. Rather than require companies to build new dams on solid earth or dispose of the wastewater and refuse through a drying system, they allow the operators to raise the height of existing dams and ponds.
Federal law, he said, requires impoundments to be stable during all phases of construction.
"Well, if you build a dam on top of 80 feet of fine coal waste that's wet," Spadaro said, "that is not stable material."