Agents with the FBI and the EPA's Criminal Investigation Division conducted a search of the facility in November.
Tests of the collected runoff show it was still too contaminated to be released.
Waste has been stored and recycled at other sites, but LDEQ grants an emergency exemption for River Birch
Gov. Jeff Landry scraps sediment diversion planned for Breton Sound marsh.
Plant held millions of gallons of motor oils, fluids and other petrochemicals.