Monday, July 2, 2012

Why have a coal-ash pond?



Coal-ash ponds ponds – also known as coal-ash waste impoundments – are an essential part of the coal-burning process at many power plants, which generate electricity by boiling water to turn turbines. 
Burned coal leaves behind ash, which typically is flushed away with water. That mixture flows to large settling ponds, which often are created in part by earthen dams. Surplus water eventually flows out of the pond into a nearby waterway – Mountain Island Lake, in the case of the Riverbend coal-fired power plant.

The danger comes from the harmful heavy metals found in ash, including mercury and arsenic. The state recently posted signs along Mountain Island Lake warning fishers about the health danger – particularly to children and pregnant women – from eating too much fish due to their high mercury content. 
Following the rupture of coal-ash ponds on the Tennessee River in 2008, the EPA designated 44 similar impoundments as having high hazard potential.
"A high hazard potential rating is not related to the stability of those impoundments but to the potential for harm should the impoundment fail," the EPA announcement said.
“The presence of liquid coal ash impoundments near our homes, schools and business could pose a serious risk to life and property in the event of an impoundment rupture,” said EPA Administrator Lisa P. Jackson in the 2009 news release. “By compiling a list of these facilities, EPA will be better able to identify and reduce potential risks by working with states and local emergency responders.” 

Duke Energy operates 10 of the coal-ash impoundments, including two at Riverbend, one at Marshall Steam Plant on Lake Norman and one at Allen Steam Plant on Lake Wylie.


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