Pennsylvania power company never inspected plant equipment that failed, data show

The Pennsylvania plant's 1,500-foot-long basin was to let the fly ash - a byproduct of burning coal - settle to the bottom while clear water from the top flowed out a discharge pipe. But a leaking barrier allowed the ash to mix with the discharge water, officials said. About 100 million gallons of coal ash slurry spilled into the river.

The discharge structure had concrete walls on three sides and wooden stop logs on the fourth. The stop logs, which look like railroad ties, were the part that failed.