Filling holes dug to build levees could cost $2.5 billion

It could cost as much as $2.5 billion to refill all the clay pits that might be dug during construction of levee improvements in southeast Louisiana, according to recent estimates by the Army Corps of Engineers.

Not only would backfilling add a huge expense, some of which would likely be billed to the state and local levee districts, it also could double the number of trucks using regional roadways and local streets to travel between the pits and construction sites, corps representatives said.

If it takes 50,000 dump truck trips, for example, to haul levee-building clay away from one fully excavated 40-acre pit, it would take twice that many round trips total to haul sand or some other material back in to refill the cavity.

Then there's the issue of where to get the material to refill the pits, once they are excavated for the levee-building clay needed to construct a more robust hurricane flood defense system by 2011.

"Some of the (backfill) could come from the river ... but it could result in more pits being dug in the region," said Col. Al Lee, corps' commander in New Orleans.

"Policies are typically set up for normal circumstances," he said. "The situation here is anything but normal. The enormity of this situation is such that we're hoping they'll revisit the policy to see if there is any flexibility for us to respond to this issue," he said, referring to national corps officials.

The effects of backfilling versus leaving behind 20-foot craters are being spelled out in an issue paper Lee's staff is drafting and will soon send to corps headquarters for review.

The document also will discuss the extra cost of backfilling, which could range from a $500 million to $2.5 billion.

"There are a lot of potential problems with trying to backfill ... including the fact that the president's proposed fiscal year '09 budget includes no money to backfill," said corps section chief Brett Herr.

Maj. Gen. Don Riley, the corps' deputy chief of engineers and deputy commanding general, said Wednesday that the issue is getting serious attention.

"We are clearly considering it, but we're looking at more than just the economics of it," Riley said. "We're looking at the ecology of it, the environmental impacts, where all this would come from," referring to the backfill.

The issue of backfilling the so-called "borrow" pits surfaced last year as residents and local governments learned that in keeping with past practice, the corps did not plan to refill the pits.

But the sheer volume of material needed for post-Katrina construction -- estimated to be enough clay to fill more than 20 Superdomes -- means digging an unprecedented number of borrow pits in some of the communities hit hardest by the 2005 hurricane.

If left open, critics say the pits could hold standing water, potentially breed mosquitoes and become liabilities for landowners.

Local governments in at least three jurisdictions, including Jefferson and St. Bernard parishes, have either already passed or are considering ordinances that would require the pits to be refilled once all useable clay is removed.

Although the corps is searching for ways to import as much clay as possible from outside the region, officials said the demand is so great that several regional pits also will be needed.

Ongoing environmental assessments indicate the noise, vibration and dust that will be generated by digging and hauling clay will have a negative impact on immediate neighbors and, to a lesser degree, those living along the routes trucks will travel between pits and construction sites.

Backfilling could easily double truck traffic to and from those pits that can be filled only with hauled materials.

For pits near the Mississippi River, Herr said it could be possible to use hydraulically pumped sand at a cost estimated at $5 to $10 a cubic yard.

But for those farther out, from 10 to 20 miles away from the river, he said trucks would have to haul in fill at a cost of $15 to $25 a cubic yard.

Sheila Grissett can be reached at sgrissett@timespicayune.com or (504) 717-7700.