They're more than an eyesore.

Authorities say the iceboxes pose health and environmental risks, and symbolize a monumental task: digging New Orleans and other parts of southeastern Louisiana out from the mountain of debris created by Hurricane Katrina.

Since the flooding receded, a fleet of dump trucks has collected about 4.6 million cubic yards of waterlogged waste from the ruins, according to the U.S. Army Corps of Engineers. The corps, which is supervising the cleanup, estimates the total will exceed 17 million cubic yards - a calculation that doesn't include abandoned cars, boats or homes awaiting demolition.

''We're adding more and more trucks everyday,'' corps spokeswoman Mary Beth Hudson said. ''It's a huge undertaking.''

The corps has awarded contracts worth up to $3 billion to three firms that specialize in disaster recovery and debris removal projects. The resume of one, Phillips & Jordan Inc. of Knoxville, Tenn., includes the cleanup of ground zero at the World Trade Center.

The firms and their subcontractors have been separating the debris to ensure proper disposal. Trees and other vegetation will be converted to mulch or burned to prevent the spread of termites. Furniture, mattresses, carpeting and other household debris will go to scores of landfills in the region.

Another category officials call ''white goods'' - broken dishwashers, stoves, microwaves, computers and refrigerators - will be recycled.

Special trucks rigged with ''knuckle boom'' cranes have slowly begun plucking refrigerators off of sidewalks, front lawns and center dividers.