The design of the discharge pipe for the dredging project at Lake Beauclair enabled uniform distribution of the sediment over the existing lake bottom as well as aeration in the water. Oxygen content in the water was an issue during dredging if the oxygen level dropped the fish would die.
The outer ring has a turbidity curtain hanging from it to control turbidity and promote settling. Polymers were also used to increase the settling time of the sediment.
On the Raisin River Area of Consern Restoration project J.F. Brennan used its broadcast capping system (BCS) to quickly place 6 inches of residual sand cover and a four- to six-inch interim cap with tight thickness tolerances and no disturbance of the underlying materials.
On River Raisin the backhoe-mounted custom paddle blended Portland cement with sediment.
Craig Vogt chairmen of the WEDA Environmental Commission presents the Environmental Dredging Navigation award to Bill Hanson of Great Lakes Dredge & Dock Vinton Bossert of the Corps of Engineers Marine Design Center and Robert Ramsdell of Great Lakes Dredge & Dock for their work on the Deer Island Restoration project.
At the WEDA conference dinner August 27 the WEDA Environmental Commission chaired by Craig Vogt of Craig Vogt Inc. presented the four 2013 Environmental Excellence Awards in two categories navigational and environmental dredging.
Environmental WINNER: Aquatic Enhancement of Lake Beauclair
This project in Lake Beauclair in Lake County Florida included both environmental and navigational dredging and was nominated for this award by Jahna Dredging Inc. and Taylor Engineering Inc. The project owner the Lake County Water Authority (LCWA) restored water quality and habitat in the lake and four residential canals by hydraulically dredging more than 1.3 million cubic yards. The sediment a nutrient-rich fine-grained organic muck had long compromised habitat and navigation during low water conditions. The award application said “Removal of the muck sediments to the lake’s natural sand bottom has improved the substrate to establish aquatic plants improve fish habitat and provide a superior surface for fish spawnng. In addition to the habitat degradation this muck layer had also created water depths too shallow for boaters to navigate without disturbing the muck layer. Suspended muck sediments cause two undesirable consequences: the presence of malodorous and aesthetically displeasing black plumes of muck and damage to boat motor cooling systems from muck entrained in outboard engines.
The 1118-acre lake downstream of Lake Apopka receives nutrients and sediments via the Apopka-Beauclair Canal. It had accommulated for many years leading to the degradation of the aquatic plant community and the proper biological balance. LCWA analyzed the top five feet of sediment and determined them to be recent deposits from farm discharges around the lake.
Jahna Dredging removed sediment from an estimated 255.4 acres in the western portion of Lake Beauclair and 6.3 acres in the residential canals. It hydraulically pumped the dredged material via and eight-mile high-density polyethylene pipe and a series of booster pumps along the canal into a disposal area located just west of the Apopka-Beauclair Canal. The dredged material had about 4 percent solids and much lower pesticide concentrations relative to the in-situ soil at the disposal site. According to the award application the property owners and regulatory agencies anticipate that disposal there will contribute to reducing presicides in the soil-water environment in the area. The effects should positively influence areas downstream throughout the Harris Chain-of-Lakes and Ocklawaha River.
At the disposal site the project faced the unique challenge of preventing birds from feasting on the live and dead fish which were affected by the cleaner lake sediments capping the shallow areas requiring a fish kill monitoring plan. Jahna Dredging used solar-powered floating dissolved oxygen meters which transmitted reading via electronic signal to a data collection point 1.5 miles away. The proper sediment cap required a diligent uniform distribution on the bottom. A disposal ring designed by Jahna Dredging prevented sediment from accumulating within one foot of the water surface so wading birds did not feed on contaminated material.
Silver Award: River Raisin Area of Concern Restoration
The construction team of Environmental Restoration LLC (general contractor) J.F. Brennan Company Inc. (marine operations) and Natural Resource Technology Inc. (construction quality control) won an award for the River Raisin Area of Concern Project in Monroe Michigan. Under the Great Lakes Legacy Act the USEPA Great Lakes National Program Office and the Michigan Department of Environmetnal Quality (MDEQ) were tasked with dredging 100000 cubic yards of PCB-contaminated sediment from the lower 1/5 miles of the river.
Navigation WINNER: Deer Island Restoration
The restoration of Deer Island a 3.5-mile spindle-shaped island off the coast of Biloxi Mississippi is part of the Coastal Preserves Program and an on-going multiple project joint effort by the Corps of Engineers Mobile District the Mississippi Department of Marine Resources (MDMR) and local environmental groups – aiming to restore the island 1850s footprint.
Hurricanes Camille Ivan and Katrina had destroyed forested areas significantly eroded the sandy shoreline and left elevations too low to support marsh vegetation. The award application said “The primary objective of the Deer Island Restoration Project was the restoration of marsh along the Mississippi coast for environmental benefit. Through creative thinking innovative design concepts and collaborative partnering the USACE MDMR and local stakeholders also identified several other objectives for the project. Together the project team and stakeholders developed a plan that would deliver economic and social benefits as well.” The project used 1.95 million cubic yards of hydraulically dredged material from a nearby borrow site to fill the west end breach to restore the southern shoreline. It placed 170000 cubic yards of fine-grained material dredged from federally-authorized navigation channels to construct a one million cubic yard capacity lagoon. The project also planed more than 300000 plants on the island with 325000 more to come.
“The principles and practices used for the Deer Island Restoration Project provide significant environmental benefits for the region as well as protection for the city of Biloxi from storm events recreation opportunities for people and hard-to-come-by economically feasible and environmentally acceptable beneficial use opportunities for dredged material” its application said.
The project created approximately 215 acres of new habitat and protects valuable foraging and nesting habitat on the interior of the island. After nearly two decades without a reported sea turtle nesting event on any Mississippi beach a loggerhead sea turtle (a federally-listed ‘threatened’ species under the Endangered Species Act) nesting occurred on a restored portion of Deer Island.
The one million cubic yards of beneficially used dredged material formed the lagoon with a spur dike and sand underwater weir to minimize impacts from the material placement and alleviate water quality concerns. It provides valuable marsh habitat and protection from future storms. The lagoon capacity also allows for additional placement of dredged material for future operations. “The USACE Mobile District broke new ground by designing a project whose primary purpose was aquatic ecosystem restoration in such a way that it simultaneously became a future beneficial use site” the project application said.
Silver Award: Port of Long Beach Middle Harbor Redevelopment
The Middle Harbor Redevelopment Project (MHRP) at the Port of Long Beach developed a management strategy and methodology for the beneficial reuse of 2.5 million cubic yards of port contaminated sediments around the region. The port designed the fill project to give excess capacity to outside entities which the port identified through a comprehensive selection process. The port considered no less than 11 individual projects and at the time of the application had accepted almost one million cubic yards of contaminated material for the Middle Harbor Fill Site – contaminated sediment that otherwise would likely still be impacting water quality. The contaminated sediments included heavy metals like copper lead zinc and mercury pesticides like DDT and chlordane and other persistent toxicants like PCBs.
“Between March 2012 and July 2012 approximately 1200000 cubic yeards of material was imported into the Middle Harbor Fill Site for beneficial use. This included almost 800000 cubic yards of third party material and more than 500000 cubic yards of material generated from the Middle Harbor project. The logistics and coordination required to ensure a safe working environment adherence to the engineering fill design as well as preventing any accidental disposal of contaminated material outside of the fill area was managed through the creation of a third party disposal working group within the construction management team” the application said.
The USACE Coastal/Navigation Section Jacksonville District also won a silver navigation award for its maintenance dredging program.