Terrebonne rings in 2017 with restoration work
With another year and another hurricane season in the books, Terrebonne Parish is continuing to bolster its coastal protection for the next wave of challenges.
Terrebonne finished a number of protection projects, including a floodgate in Chauvin, in its first year with Parish President Gordon Dove and a new parish council. According to Dove, additional large-scale projects, such as a $366 million lock system on the Houma Navigational Canal, are closer to beginning construction after design and funding progress over the past year.
After a summer that featured lots of rainfall but little in the way of hurricanes or tropical storms, the parish is still at work building up the Morganza to the Gulf levee system. Dove said additional levees are nearing completion, and Terrebonne is set to have at least 12 feet of levee protection from Pointe-Aux-Chenes to Dularge before the next hurricane season.
Petit Caillou floodgate completed, celebrated
Though state and parish officials did not officially christen it until November, the Petit Caillou floodgate in Chauvin has been complete and functional since March of last year.
The almost $20 million structure lies at the southernmost point of the Morganza system and is key in the protection of communities along Petit Caillou. It has a 110-foot opening, which Terrebonne Levee and Conservation District workers will close during storms.
The floodgate had been in progress well before new parish leadership took over, having gone to bid for construction in late 2014 and contractors taking a year-and-a-half to build.
Levee system closing up
Levee work near that Petit Caillou floodgate will soon accomplish a long-sought goal for local coastal protection leaders.
Dove said work on reach G-2 of the Morganza alignment is set to finish within two months. According to Dove, the work would be finished before this year’s hurricane season “without a doubt.”
Reach G-2 is part of the levee connecting Petit Caillou to the Four Point Bayou. Dove said it is being built to at least 12 feet the entire way, with certain areas being built up to 13.5 feet. The levee is being protected with segmented rocks the entire way to protect the levee from Lake Boudreaux’s wave action.
According to Dove, the finishing up of Reach G-2 along with the expected finish of levees along Falgout Canal will tie up the Morganza system with levee protection from Pointe-Aux-Chenes in the easternmost part of the parish to Dularge on Terrebonne’s west side. Reggie Dupre, executive director of the parish’s levee district, said parish officials set a goal in 2008 to connect the five bayous of Terrebonne along the Morganza alignment. According to Dove, the soon-to-be-completed levee work will make that goal a reality.
“From Falgout Canal to Falgout Canal Road, we’re under construction to the lower Dularge levee. That will be completed before hurricane season. So all the levees will be completed from Pointe-Aux-Chenes all the way to Dularge,” Dove said.
Though it will not be ready for the next hurricane season, Falgout Canal will soon have a floodgate as well. The floodgate, a TLCD project, is expected to go to bid soon. Dove said the parish just got a permit from the U.S. Army Corps of Engineers for the floodgate.
According to Dove, construction on the floodgate will take about 15 months, so it could be ready for next hurricane season if construction starts soon enough. Dove said better vegetation in the parish’s west side near Falgout Canal provides some protection before the parish completes the floodgate.
The levee district does not yet have the entire bill for the floodgate accounted for, though. According to Dupre, the TLCD currently has $31 million dedicated to the project, leaving $14 million unaccounted for. However, Dupre said the TLCD has been receiving lower, competitive construction bids in light of the oil and gas downturn, which means the levee district could see some savings on the floodgate’s $45 million price tag.
One levee not located along the Morganza system is also set for completion this year and should provide transportation and protection benefits. The Thompson Road construction project will be finished this year, according to Dove. The Thompson project is a road built on a “redundant levee,” meaning a smaller levee built inside of the Morganza alignment meant to provide a second layer of protection. Thompson Road will seal the north end of the Lake Boudreaux basin, acting as a buffer between the basin and the Houma-Terrebonne Airport and Industrial Park.
Lock systems in the future
Dove said Terrebonne is also looking to install multiple lock systems to provide protection while still allowing navigation along the parish’s waterways.
Terrebonne received particularly good news at the end of November when the state’s Coastal Restoration and Protection Authority released its draft plan for RESTORE Act money. In the plan, which comes from penalties related to the 2010 Macondo Spill, Louisiana will receive almost $812 million over 15 years for CPRA projects. Included in those projects is a $366 Houma Navigational Canal lock complex, what Dove and Dupre have called the “crown jewel” of the Morganza system.
The lock system will be on the HNC, where the parish currently has the 250 ft.-wide Bubba Dove floodgate. The Bubba Dove will be retrofitted to be a part of the lock complex, with the Bubba Dove to eventually provide 23 ft. of protection. According to Dove and Dupre, the lock system will provide be both a hurricane protection and environmental structure. It will allow the parish to retain more freshwater within the system and disperse it estuaries, aiding coastal restoration.
Dupre said the lock will also greatly improve boating navigation during storms. Dupre said with the Bubba Dove, the levee district has to close the structure well before storms approach, a process that takes three-and-a-half hours. The lock system will feature a set of 110 ft.-wide sector gates to let ships through without allowing water to enter the system. Dupre said he is not sure how long the lock’s gates would take to open and close, but 56 ft. gates take three minutes, meaning the lock could open and close much quicker than the floodgate, giving ships more time to get within the Morganza alignment to find safe harbor.
“So we have to close [the floodgate] and people might be trapped outside and have to seek harbor somewhere else or ride it out. With a lock system you could allow vessels to get harbor at a much later time as a hurricane approaches us,” Dupre said.
However, Dupre said the state is still hammering out details on funding for the structure since the RESTORE Act’s total money will be delivered over 15-year increments. Dupre said he could see the construction of the lock system broken down into multiple phases due to the piecemeal funding structure.
“I think during the next year we will have a much better idea from CPRA what’s going to be the funding stream and timeframe. That’s going to drive when we can build component parts of the lock, along with of course environmental clearances and getting design work done,” Dupre said.
Money or not, the HNC lock is not expected to be finished anytime soon. The RESTORE Act draft had the project’s engineering and design not being completed until March of 2019, with construction of the entire project going until the end of 2022.
Dove said the parish is working on adding another lock system to a Petit Caillou near Boudreaux Canal. There is one existing sector gate there already, but addition of a second gate would turn it into a lock system. The lock would allow vessels to enter without letting water enter the system, which has become a problem for Chauvin during high tides. According to Dove, if sea levels rise and subsidence continues, eventually Terrebonne will need lock systems along all of its bayous to allow navigation while preventing flooding.
Dove said this lock system is currently in an engineering phase, with the parish applying for grants to pay for the estimated $23 million price. Dove said after the lock system in Chauvin is finished, the parish would seek a second one on Bayou Terrebonne in Montegut. •