Jefferson Parish plans to build its own pipelines to avoid salt water in Mississippi - NOLA.com

Jefferson Parish to build pipelines to avoid salt water | Jefferson Parish | nola.com

Less than four weeks before salt water is estimated to reach the intakes for their treatment plants, Jefferson Parish officials said Friday they have received approval to lay pipelines upstream along the banks of the Mississippi River to deliver enough fresh water to their systems to continue producing safe drinking water.

The plan is to pay contractors to run flexible piping to an area of the river in Kenner where the level of salt is expected to remain much lower than at the downstream intakes, in Marrero and Old Jefferson. It has been approved by the Army Corps of Engineers, and work will begin as early as next week, officials said.

Map shows a timeline animation of when salt water is forecast to creep up the Mississippi River and threaten municipal water intakes, according to the Army Corps of Engineers. The Mississippi River is the primary source for drinking water for the New Orleans metro area, as nearly every other body of water surrounding the region is salty or brackish.

Jefferson's emergency pipeline initiative comes as officials across southeast Louisiana brace for a Gulf of Mexico saltwater wedge that is creeping up the Mississippi, threatening the region's drinking water systems. It has already made its way into Plaquemines Parish drinking water, where local residents relied on bottled water for months as officials scrambled to build temporary connections and feeds into upriver water intakes.

New Orleans emergency management officials said Thursday they were preparing for the intrusion to last as long as three months, until January. The city has floated its own plan to build a pipeline from its Carrollton plant water intake to a spot farther upstream. That plan, which is separate from Jefferson's, hasn't received approvals yet and could cost as much as $250 million.

Jefferson is in the process of engaging contractors to work on the two pipeline projects, one to supply water to the river intake in Old Jefferson, which takes in 40 million gallons of water a day and serves the entire east bank, and one for the West Bank intake in Marrero, which takes in 30 million gallons of water a day.

"This is what we're calling a flexible waterline system, sometimes known as lay-flats in the industry, to draw in fresh water from up the river,” Parish President Cynthia Lee Sheng said.

Jefferson Parish President Cynthia Lee Sheng speaks at a news conference about the salt water moving up the Mississippi River, at the Emergency Operations Center in Gretna on Friday, Sept. 29, 2023.

Work will start on the West Bank because its intake is farther downriver and will be affected first. Parish officials have not finalized the contracts and didn't provide an expected cost.

Public Works Director Mark Drewes said contractors will lay as much as 15 miles of flexible pipes with high-velocity diesel pumps from the West Bank plant to a natural upriver sill, called the "Kenner hump," where there’s a "significant change in grade in the Mississippi River."

"In the recent past, in 1988, the [tip of the salt water] reached about that point and quickly retreated, so it’s an ideal spot. So if we can get in that vicinity ... we should be OK,” Drewes said.

The West Bank system will have four, 12-inch diameter lay-flat pipes. There will be four diesel pumps at five-mile increments. Drewes said the system is “buildable” and may not need to reach the full 15 miles officials are planning.

Salt water is creeping up the mouth of the Mississippi River and threatening the drinking supply of several parishes in Southeast Louisiana, i…

A similar system will be built on east bank, but with five lay-flat pipes to accommodate more water, Drewes said.

"We do believe it's doable with the timeframe and the schedule the Corps has set out," he said.

Lee Sheng said that while the East Jefferson pipeline is separate from those being considered for the east bank of Orleans Parish, it would likely run in the same area. Drewes said officials are already scouting the route and will begin bringing in equipment next week.

He said the West Bank project should have five miles completed “in a couple weeks.”

Gretna and Grand Isle

There is a separate plan for Gretna, the first area in Jefferson Parish to be affected by the salt intrusion and the only one of the parish's six municipalties to rely on its own water treatment and distribution system.

Gretna processes only 4 million gallons a day, far less than the tens of millions of gallons supplied by other water plants in the region. That means that instead of pipelines, Gretna may use reverse osmosis machines or barge in fresh water from upstream to dilute the river water to safe drinking levels at is plant.

Mayor Belinda Constant said a barge will be secured by Saturday at 3 p.m.

"We really want the constituency to understand that we stand ready," Constant said, adding that “there may be challenges" and that residents may be asked to reduce water use so it can be targeted for emergency purposes.

Westwego sends municipal bills for drinking water, but it buys the water from Jefferson Parish and gets it from the parish's Marrero plant, Lee Sheng said.

Grand Isle ordinarly gets water from Jefferson Parish but will get it from Lafourche Parish for the time being.

Last week, Lee Sheng declared a state of emergency for Jefferson Parish, a standard requirement for the parish to receive federal reimbursement later for local emergency expenses. The declaration also allows her to disregard public bid laws, compel evacuations and commandeer private property, among other things.