TEMPORARY REPAIRS to breaches in New Orleans' flood walls could stay in place until at least next spring, according a senior engineer working on the repairs.
'We are trying to base the levee repair plan on the risk of damage from future storms, which means seeing out the current hurricane season and maybe even waiting until after the spring Mississippi water rise for more permanent work, ' said Colonel Richard Wagenaar, commander and district engineer in the US Army Corps of Engineers New Orleans District.
Early work has focused on closing breaches near Lake Pontchartrain to stop water flowing into the city.
Engineers have used a combination of 3,000kg sandbags dropped from Chinook and Blackhawk helicopters and a dumped mixture of large rocks, known as riprap, and crushed asphalt.
Wagenaar said sandbagging was the only viable option: 'When we first flew over and saw the hole, it was surrounded by water on all four sides and we knew we couldn't get there by land or bridges.' Sheet piling was subsequently used to stop water flowing into the canals from Lake Pontchartrain.
Wagenaar insisted it would have been impossible to use sheet piles to repair the floodwall damage because his teams could not get vital plant to the site.
The practice of dumping rocks on top of sandbags has, however, been criticised by the New Orleans Sewage and Water Board's general superintendent Joe Sullivan, who worked with the Corps of Engineers and contractors to plug the breaches.
He said: 'I'm unhappy with the fact that they've put riprap in the hole, because it means we can't drive sheet piling straight down.
'I know this couldn't be done at the time, and they said it was urgent, but it's going to mean driving the sheet piling down at a later date in a bowed out section - built around the riprap.'