Here’s why $1.7 billion in hurricane levee work is needed in the New Orleans area – NOLA.com

Soil subfacetnce and rising seas are anticipated To Scale again The peak Of latest Orleans space lev…….

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Soil subfacetnce and rising seas are anticipated To Scale again The peak Of latest Orleans space levees and floodwalls by virtually 2 ft Inside The subsequent half century.

Simply To Sustain The current regular of shieldion, The army Corps of Engineers now proposes to spend about $1.7 billion elevating 99 miles of levees and constructing or changing virtually 4¼ miles of floodwalls.

What quantity of did you expertise?

The estimate comes from two research launched Friday for the hurricane shieldion methods on Every facet of the Mississippi River Inside The mannequin new Orleans space. It is $1.5 billion Decrease than the Corps first calculated in December 2019, when the agency proposed elevating 102 miles of levee and constructing or changing 20 miles of floodwalls, Completely on the east financial institution.

Nonetheless, it displays The huge public value merely To take care of right now’s diploma of hazard discount Inside the face of sinking land and human-set offed local climate change.

The research cowl most Of latest Orleans and parts of Jefferson, Plaquemines, St. Bernard and St. Charles parishes. They have been accredited by Congress in 2018 amid considerations that subfacetnce and rising seas would make parts of the levee system – as early as 2023 – too low to be licensed as meeting Nationwide Flood Insurance coverage Program regulars. The legal guidelines additionally requires the federal authorities to pay 65 % of the enterprise’s value.

The up So far reviews additionally undertake new Corps language defining what Want to be provided: shieldion as quickly as extrast flooding Launched on by levee primeping that has a 1% probability of occurring in any given yr. 

Gone are previous comparisons of that hazard diploma to surge created by a “100-yr storm,” or to previous storms Similar to Katrina, The Costliest hurricane in U.S. historic previous.

If a Hurricane Katrina-like storm have been to hit New Orleans and the Gulf Coast right now, It’d probably set off Greater than $175 billion in damage to …

“This terminology is Not used as a Outcome of it falsely conveys A Method of time and lowers public hazard perceptions,” the report said.

Instead, the 1% flood event Inside the Corps’ e-book now recurrents The prospect that water primeping the levees would violate the Nationwide Flood Insurance coverage Program’s base flood elevation regulars for enhancement infacet the levee system. The insurance program still refers to as a 100-yr event.

The revised reviews additionally reject Louisiana’s request To enhance the shieldion to a 0.5% diploma, which Was equated to a 200-yr event. Gov. John Bel Edwards and the Southeast Louisiana Flood Safety Authority-East sought The extremeer regular, saying 1% was not enough. The Corps itself has rated the levee methods Inside The mannequin new Orleans space as “extreme hazard”, its second-worst diploma, Beset off of billions of dollars in damage that a flood event greater than 1% would set off. 

New interpretation of 1965 legal guidelines would clear authorized hurdles To start work

The new reviews say the added prices of 0.5% shieldion Aren’t as financialally useful Since the 1% diploma. They typically say Congress accredited Simply one% shieldion diploma, based mostly on flood insurance regulars in place in 2005 when Katrina struck.

The reviews additionally say the Corps enhancement plans Maintain in thoughts solely The outcomes of primeping, and Did not confacetr totally different factors Similar to whether or not parts of the levee system might fail for totally different set offs. 

On the east financial institution

The new east financial institution report Requires elevating The peak Of fifty miles of earthen levees in 10-yr intervals over The subsequent 50 yrs. Particular person lifts would enhance levee peaks 1 To three ft Each time, however not each levee half Can be embraced Inside the later yrs.

There additionally Can be a mile of floodwall alternative and virtually 2¼ miles of new floodwall, some aprolongedside the Mississippi River levee in an space the place an earthen levee Wouldn’t match. The river levee enhancement is Aimed in the direction of reducing The prospect that A combination of storm surge and extreme river water Does not prime the levee.

The enterprise additionally Requires restoring foreshore shieldion – huge rocks that reduce The measurement of waves – in Lake Pontchartrain as levee enhancements are made. Which might require dredging To permit barges carrying the rocks To Obtain the workwebsites.

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Fifteen yrs after Hurricane Katrina $14.6 billion of reconstructed and redesigned levees Is almost full, with Simply a few stretches of ar…

The east financial institution enterprise would have a “first value” of $1.1 billion, with a constructive benematch-value ratio Of seven.3. Even with the enhancements, the Corps estimates that flood damage from levee primeping will common $53 million a yr. With out the lifts, the estimate is $246 million a yr.

The Corps estimated the east financial institution enterprise would Finish in 292 extra jobs over 50 yrs, recurrenting $1.1 billion in labor income, and $1.3 billion in gross regional product.

The state would pay $387 million of The enhancement value, and Can be Responsible for the $479,000 annual value of working and maintaining the enhancements. The operation and upkeep prices probably would fall to the east financial institution levee authority, which is funded by property taxes in Jefferson, Orleans and St. Bernard parishes. 

On the west financial institution

The west financial institution enterprise Requires 49 miles of levee lifts, changing 268 ft of floodwalls and constructing 1 mile of new floodwall. It additionally embraces virtually 5⅔ acres of new foreshore rock shieldion. Included Inside the levee lifts are 10 miles of Mississippi River levee, as quickly as extra to account for the potential combination of storm surge and a extreme river. 

Fifteen yrs after Hurricane Katrina uncovered The mannequin new Orleans space’s levee system as a “system in identify solely,” its redesign and reenhancement …

The west financial institution earthen levees would see individual lifts of 1½ To three½ ft over 5 many yrs, however each half Can be lifted solely A pair of events all by way of That time.  

The enterprise’s “first value” estimate of $602 million would Finish in a benematch-value ratio of 4.7. The Corps estimates the enhancements Would Scale again west financial institution financial damage by $8 million a yr, As in contrast with $84 million without the enhancements.

The enterprise Is predicted to Finish in 158 jobs, recurrenting $609 million in labor income, and $702 million in gross regional product.

The state’s share of the west financial institution enhancement prices Can be $211 million, and operation and upkeep prices Can be about $400,000 a yr, probably picked up by the west financial institution levee authority. 

The Military Corps of Engineers has unveiled a revised, 30-mile-prolonged Upper Barataria levee system Which might value almost $2 billion and shield po…

How a lot each levee half Shall be raised will Rely upon native costs of soil compaction and underlying subfacetnce, mixed with The outcomes Of worldwide warming-induced sea diploma rise. Throughout The complete system, the Corps estimates that The typical combination of sea diploma rise and subfacetnce by way of 2078 Shall be 1¾ to 2 ft. More speedy subfacetnce costs Would require extra peak in some places and the repeated addition of clay To Sustain. 

A Corps spokesman said the west financial institution enterprise Doesn’t embrace elevating the western end of the west financial institution levee system even extremeer to Maintain in thoughts extremeer storm surge levels if the proposed Upper Barataria levee system is accredited for enhancement. That levee is to run south from the western facet of Davis Pond to Raceland, To shield parts of Ascension, Assumption, Jefferson, Lafourche, St. Charles, St. James and St. John the Baptist parishes. 

A selection on including peak to that An factor of the west financial institution levee Will not be made till the Upper Barataria levee is accredited by the Corps and accredited by Congress, probably by The prime of this yr.


The general public might view the east financial institution reviews and the west financial institution reviews. The Corps is accepting public feedagain on The two research by way of Sept. 5. Comments or questions Could Even be despatched:

  • By mail – U.S. Military Corps of Engineers, New Orleans District, c/o Bradley Drouant, CEMVN-PMO-L, Room 361, 7400 Leake Ave., New Orleans 70118.
  • By e-mail – [email protected]

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