Supervisors receive update on weir problems on Pearl River
During Monday’s meeting of the Pearl River County Board of Supervisors, County Engineer Les Dungan gave the board an update on the condition of the weir at Wilson Slough near Walkiah Bluff on Pearl River.
The weir was constructed in 1998 to correct flow problems with the Pearl River to create a 50/50 flow of river water to Louisiana and Mississippi, but that split has never occurred and hydrologists have reported the flow is close to 85 percent to Louisiana into the Bogue Chitto River and 15 percent to what is referred to as East Pearl River.
Dungan presented imagery he had collected dating back to 1998 just after the construction of the weir. Dungan showed that around 2005, erosion began to show over time to the the rip rap on both the upstream and downstream side of the weir structure.
The images detailed a scour hole that continued to grow on the downstream side of the sheet piling wall. Dungan noted that the weir structure itself has began to show signs of leaning over and coming apart which is allowing even more water to go to Louisiana to the Bogue Chitto River.
All images courtesy of Les Dungan
The weir and support structures shown above in 2007
The weir and support structures erosion shown above in 2019
Dungan presented a suggested Phase 1 project that would be to secure the structure:
· Construct Access Road
· Repair Sheet Pile Wall
· Replace Fill Material (That Has Floated Away)
· Replace / Repair Riprap
· Remove Access Road
Phase 1 Project overview from Les Dungan
Phase 2 Project overview from Les Dungan
Dungan said there are many hurdles to get by in order to implement the project. County Administrator Adrain Lumpkin said that from a previous meeting with the Corp of Engineers in Jackson, he recalls the Corps saying that gaining access to the weir to do the work under a scope of maintenance would most likely be agreeable. Otherwise, work on the weir would be delayed because approval would have to go through the process of environmental studies that could take 3 to 4 years and millions of dollars. Lumpkin said the best outcome would be for the Corp to give the county a permit to proceed with the projects.
Dungan said that in the environmental impact study of the original plan for the weir in the late 90s, the plan specifically stated that maintenance on the weir structure would be required in the next 25 years (1998 through 2024). He says this gives the county an open door to do maintenance under the original study.
Phase 2 would be to dredge approximately 3 miles of Pearl River beginning at the weir and continuing southward on East Pearl River creating a pilot channel twenty feet wide and a minimum of three feet deep.
There is approximately $4 million set aside from previous funding that is designated for the weir for maintenance.