In order to achieve the authorized project depth in the Calumet Outer Harbor, bedrock will be removed starting on Aug. 10, 2017 through July 2018. The Corps awarded a contract to Roen Salvage Company of Sturgeon Bay, Wis., on Sept. 30, 2016, for $6,053,900. Work will occur 7 days a week through December 2017, then start up again in spring 2018.
Naturally occurring dolomitic bedrock outcropping, or rock formation above the surface, in Calumet Harbor has prevented full maintenance of the shipping channel to the authorized depth of 30 low water datum, which prevents full use of the navigation channel by deep draft vessels during low lake levels.
Daily work includes rock blasting underwater and 1 mile offshore, and rock placement on a barge using an excavator. The barge will then move over to the nearby breakwater, where rock will be unloaded with a crane and placed.
There will be one blast per day at the end of each day. A notice to mariners has been posted at https://www.navcen.uscg.gov/?pageName=lnmMain. The U.S. Coast Guard will broadcast a safety zone and all traffic will be stopped at 2,000 feet from the blast area, for approximately 30 minutes. Vibration and air blast monitoring will be used as part of the operation. No noise will be heard on land and nothing felt. Also, methods will be used to protect aquatic species during the blasting activities via a repelling noise to move fish away from the immediate zone.
Once the blasting barge is loaded, the attendant tug will move the barge out to the blasting area in the outer harbor. At the blasting work area, the dredge barge will be spudded down in a position on line and at station to accept placement of the blasting barge along its side. The tug will position the blast barge near one end of the dredge where drilling will begin.
Explosive materials will be placed in drill holes and then fired one time at the end of the day. After the shot is fired, any unused explosives will be moved off-site to a secured storage facility.
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