But other than more testing, mine disposal is not subject to the same safeguards as when coal ash is dumped anywhere else. Ash put in landfills must be kept away from ground water with a heavy plastic barrier, and monitoring wells must surround the site to give early warning if any contaminants leak out.
Maryland officials say that liners aren't needed in mines, because the ash is being dumped well above the water table and in relatively small amounts.
Warrior Run is depositing 370,000 tons of ash in four Allegany mines, according to an AES report to the state. That's much less than the estimated 8 million tons Constellation poured into the Gambrills gravel pits.
State regulators say monitoring wells aren't practical at mines, because they are so far above the water table. Instead, mines are required to test water seeping from springs at the base of slopes or in creeks downstream from the mine. Also, officials say, they only allow alkaline ash to be dumped in mines, so it will help neutralize acid mine drainage. Warrior Run's ash is highly alkaline because the power plant burns coal with limestone to reduce air pollution.
Environmentalists say Maryland's new coal-ash disposal regulations are better than those in many states but are still inadequate when it comes to mine disposal.
"It doesn't seem like the gap has been plugged," said Earthjustice's Evans. "We still have potential problems that can occur from this waste. It's just going to a location that is arguably more distant, and it's a little harder to tell what the impacts will be."
Neither Maryland nor most other states require sufficient testing of water for ash contaminants, contends Jeffrey Stant of the Environmental Integrity Project, a Washington-based group led by a former EPA enforcement official. State rules only require water monitoring for five years after the mine has been reclaimed. Stant said problems may not show up for a decade or more after the ash has been put in the ground.
While state officials say there hasn't been evidence of coal ash harming Western Maryland streams, others say it may not be easily discernible. Even contaminants not at levels deemed unsafe for humans can affect fish and other water-dwelling creatures.
