IRL Restoration: Grand Canal Muck Dredging Gets Underway
BREVARD COUNTY, FL. – Nearly 500,000 cubic yards of muck will be removed from the Grand Canal as part of a $27 million Indian River Lagoon restoration project that is slated to begin dredging this week and is expected to take four years to complete.
The project entails hydraulic dredging of the Grand Canal system from Pineda Causeway south to the north end of Samson Island. Work includes muck removal from entrance canals entering from the Banana River and residential finger canals but excludes the canal between Port Royal Boulevard and St. Georges Court, which may occur later but not currently included due to manatee protections.
As part of this project the County has conducted sediment sampling in 2015, 2018, and 2019. These samples were tested for chemical constituents often found in dredged sediment plus a large suite of atypical analytes selected due to proximity to the military dump located in South Patrick Shores. Test results support moving forward with dredging. The County has also developed a rigorous sediment sampling plan that will continue throughout the duration of the project.
All of the canals within the Grand Canal Muck Removal Project Area have been investigated and determined to contain a significant amount of muck. Muck is considered a legacy load caused by decades of stormwater runoff, wastewater treatment facility discharges, septic system drain fields, and excess fertilizer applications. Muck is material on the bottom of the lagoon that contains fine-grained organic material; creates large areas that are not hospitable to seagrass, shellfish or other marine life; releases large amounts of hydrogen sulfide and nutrients into the water column that contribute to harmful algal blooms; creates turbid conditions that negatively affects seagrass growth and the benthic communities that it supports; and depletes oxygen in the water column that can result in fish kills.
The project is funded primarily through a Save Our Indian River Lagoon (SOIRL) 10-year half-cent sales tax approved by Brevard County voters in 2016, but also about $9 million in grant funds approved by the Florida Legislature for muck removal. While the work is anticipated to begin this week, dredging is expected to continue intermittently through spring 2023 due to seasonal manatee closures required by regulatory agencies.
The contracted muck removal will entail an auger-head and vacuum-style (hydraulic) dredge. Here’s how it works:
- The muck will be sucked from the bottom of the canals and pumped through a pipeline to a temporary dredged material management area (DMMA) along the south side of Pineda Causeway, just west of the S. Patrick Drive exit.
- The muck will be pumped into geotubes (big geotextile duffle bags) and dewatered.
- Once a geotube is filled with muck, it will sit for approximately five-to-seven days to allow the muck to decant water and dry out.
- Once the muck is in a dry enough condition, each geotube will be cut open and the dried muck will be loaded into haul trucks, transported to and placed on agricultural land west of I-95 for beneficial re-use as an organic soil amendment.
- The decanted water (dredge effluent) from the geotubes will be diverted through a temporary water treatment system assembled at the DMMA to reduce nitrogen and phosphorous concentrations prior to being returned to the Grand Canal system.
The SOIRL half-cent sales tax has included other dredging projects that have either already been completed, are under way or are currently in the bid and/or permitting stages. They include:
- Turkey Creek Muck Removal Project – Dredging was completed with state grant funds. The area was cleaned again with SOIRL funds after a hurricane move muck in to the cleaned area. FEMA reimbursement for 87.5% of the SOIRL clean-up cost is pending.
- Mims Boat Ramp Muck Removal Project – Dredging was completed December of 2018. Funded through the State grant. Additional nutrient removal was contracted with SOIRL funds.
- City of Cocoa Beach Muck Removal – Phase III – Work underway. Dredging to be completed by end of 2019
- City of Cocoa Beach Muck Removal – Phase IIb – Work underway. Dredging to be completed by the end of 2021
- Sykes Creek Muck Removal Project – Phase I – Anticipated to go out to bid in the next 30 days. Includes approximately 58,000 cubic yards of muck from residential canals and open water borrow pits just east of Kiwanis Island Park in Merritt Island.
- Eau Gallie Causeway Muck Removal Project – Anticipated to go out to bid within the next 60 to 90 days. Includes removal of approximately 250,000 cubic yards of muck from areas adjacent to Eau Gallie Causeway.
- Merritt Island District Two Muck Removal – FDEP permit issued. Anticipated to go out to bid within the next 6 months.
- Titusville Railroad Bridge (East and West) – Field data collection underway. Anticipate submittal of permit applications to FDEP and USACE in early 2020. Regulatory authorization and bid advertisement anticipated by end of 2020.
- NASA Causeway East – Field data collection is underway. Anticipate submittal of permit applications to FDEP and USACE in early 2020. Regulatory authorization and bid advertisement anticipated by end of 2020.