Dredging Project Update

Dredging Update. George Antoniou, Lake Restoration Program Coordinator IDNR, recently (4/30/20) provided FOLM an update on the project. We have attached the JF Brennan submitted in-lake buoy and watercraft safety plan for Phase 2 dredging. We have also attached the Phase 2 dredging and dewatering plan that clarifies the approach and concerns with filling in the deep region, SE of the point, created during Phase 1.

“The work being completed to date was focused on an initial first pass over the Phase 2 dredge area to remove the top silt/mud layer. The “sweeping” of ~120,000CY of material was discharged within the in-lake spoil area located in the identified deep hole. This work is either completed or wrapping up by the end of this week. You are correct – that will decrease depth in this region. However, material placed in this area should be below the 953 elevation, which still¬†leaves a minimum depth of 14ft. In addition, the lake will be left with additional acreage¬†of deep water habitat at the end of this year’s work.

Dredge Phase 2 starting

Dredge in action

Sweeping of the Phase 2 dredge area was done to limit the possibility of excavating and transporting mud during sand dredging. Mud transported to the stockpile area during Phase 1 dredging caused issues with the dewatering plant and ultimately takes up needed space in the settlement basin.

Sand dredging operations in the Phase 2 dredge area are expected to start next week and upon completion the new dredged region will have a minimum water depth of 10ft and maximum depth of 25ft. The final step will be removal of ~2ft of lacustrine material from the east shoreline of Lake Manawa, which will be pumped to the Phase 2 dredging area while still maintaining a minimum lake depth of 10ft across the entire phase 2 dredge area and a 4ft maximum thickness of lacustrine material.”