Crews working for the U.S. Army Corps of Engineers have found “isolated” amounts of concrete and other “unsuitable” materials in the levees along the 17th Street Canal, but that debris does not present a risk, officials told the board that oversees the east bank flood protection system Thursday. The debris was discovered while the Corps was installing 65-foot-long sheet piling into about 1,400 feet of the levees along the canal, Brad Drounant, a senior project manager with the Corps, told the Southeast Louisiana Flood Protection Authority-East.
“We’re confident that this isolated amount of material is not a threat” even if it remains in the levee, Drounant said.
Critics have raised concerns the debris could undermine the levees, which were the site of a catastrophic breach during Hurricane Katrina, when the floodwalls on the levees failed.
The Corps has specifications for the types of materials that can be used when building a levee and rules on how much “unsuitable material” can be allowed in the structure before it presents a risk.
The risk is that such materials will not be up to the standards needed to ensure the levee can hold or will allow water to seep through and undermine the levees. Those issues are more of a threat when organic material that can decompose is found in the levees, officials have said.
Drounant said the amount found in the 17th Street Canal levee is not of concern, though it is being removed as crews work on the project. The levees in that area date back to before the federal government began designing the Lake Pontchartrain levees in the New Orleans area. The original levees still sit below the newer, improved levees since erected under Corps supervision, Drounant said, and the debris likely is left over from the earlier defenses.
Other material that can be seen in the area may have come from temporary ramps and staging areas built near the levees to allow construction equipment to access the construction site and is not part of the levee, he said.
The Corps has also taken borings from areas outside the current construction site and has not found any results that are a cause for concern, he said.
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