RICHMOND, Va. (AP) - A new report prepared for Dominion Energy says it would be cheaper and quicker to close and cover the company's largest Virginia coal ash ponds than to recycle the waste or move it to landfills.

The report released Friday was mandated by Virginia's General Assembly, which also put on hold the company's plans to close its coal ash ponds until lawmakers can review Dominion's findings.

Coal ash is the heavy metal-laden waste that's left over after decades of burning coal to produce electricity.

For decades, coal ash has been stored in landfills or in ponds, often near waterways. Recent spills have drawn concerns about its storage.

Environmental groups criticized the report, saying it appears designed to justify Dominion's initial plans. They say the ash must be excavated from unlined pits.