Methods and Systems for Dredging

Abstract

The invention relates to a dredging method for dredging a navigation channel for guaranteeing a nautical depth of a navigation channel. The method comprises performing agitation for mobilizing sediment and displacing the mobilized sediment to a collector which is embedded in the bottom of the navigation channel, the collector being a trench in the navigation channel wherein the trench has, when not being filled with sediment, a bottom level positioned substantially deeper than the nautical depth of the navigation channel. The method also comprises, in a step different from said performing agitation dredging, after solidification of the sediment collected in the collector, removing the solidified sediment from the collector so that the collector again has a bottom level positioned substantially deeper than the nautical depth of the navigation channel.

1 - 30 . (canceled) 
     
     
         31 . A method for dredging a navigation channel for guaranteeing a nautical depth of a navigation channel, the method comprising
 performing agitation for mobilizing sediment and displacing the mobilized sediment to a collector which is embedded in the bottom of the navigation channel, the collector being a trench in the navigation channel wherein the trench has, when not being filled with sediment, a bottom level positioned substantially deeper than the nautical depth of the navigation channel,   in a step different from said performing agitation dredging, after solidification of the sediment collected in the collector, removing the solidified sediment from the collector so that the collector again has a bottom level positioned substantially deeper than the nautical depth of the navigation channel.   
     
     
         32 . A method according to  claim 31 , wherein said displacing the mobilized sediment is performed by water injection. 
     
     
         33 . A method according to  claim 31 , wherein said displacing the mobilized sediment is performed by plough dredging. 
     
     
         34 . A method according to  claim 31 , wherein, prior to said agitation dredging, the method comprises forming the trench in the navigation channel. 
     
     
         35 . A method according to  claim 31 , wherein said performing agitation comprises agitation dredging through water injection dredging using a water injection dredger or wherein said performing agitation comprises agitation dredging through water injection dredging using a plough dredger. 
     
     
         36 . A method according to  claim 31 , wherein said performing agitation comprises using a water injection system installed at or near the nautical bottom. 
     
     
         37 . A method according to  claim 36 , wherein said performing agitation comprises performing agitation through a water injection system being at least partly integrated in mats for scour protecting or mats forming the wall of the collector. 
     
     
         38 . A method according to  claim 31 , wherein said removing sediment from the collector comprises removing sediment with a jumbo hopper dredger. 
     
     
         39 . A method according to  claim 31 , wherein said removing sediment from the collector comprises removing sediment by pumping through a stationary or mobile pumping system. 
     
     
         40 . A method according to  claim 31 , wherein the method comprises, prior to said performing agitation for mobilizing sediment, determining any of soil strength and/or density and determining based thereon any or more of the dredging power, the dredging effort, the water injection volume to erode, liquefy or mobilise the underwater sediment layer. 
     
     
         41 . A method according to  claim 31 , wherein the method comprises predicting when the sediment needs to be moved to the collector. 
     
     
         42 . A method according to  claim 31 , wherein the method comprises predicting when the sediment needs to be removed from the collector for guaranteeing a predetermined nautical depth. 
     
     
         43 . A method according to  claim 31 , wherein the method comprises predicting when the sediment needs to be removed from the collector. 
     
     
         44 . A method for assisting according to  claim 43 , wherein said predicting is based on an estimate of the amount of mobilized sediment collected in the collector or the degree of consolidation of the sediment in the collector. 
     
     
         45 . A water injection platform for dredging a navigation channel for guaranteeing a nautical depth of a navigation channel,
 the platform comprising   an agitation system for performing agitation for mobilizing sediment and displacing the mobilized sediment to a collector which is embedded in the bottom of the navigation channel, the collector being a trench in the navigation channel wherein the trench has, when not being filled with sediment, a bottom level positioned substantially deeper than the nautical depth of the navigation channel.   
     
     
         46 . A water injection platform according to  claim 45 , the platform further comprising the collector for collecting the mobilized mud and/or comprising the platform comprising a dredging pumping system for pumping the liquefied sediment and/or wherein the collector is a trench made in the seabed of the navigation channel and/or wherein the agitation system is based on a floating platform or vessel. 
     
     
         47 . A water injection platform according to  claim 45 , wherein the water injection system comprises a submersed system with mounted or integrated nozzles and/or comprises one or more mats where injectors are integrated and connected with a water injection pump and/or wherein the mat is a mat suitable for scour protection or as surface or wall to shape a collector and/or wherein the collector is formed and shaped in the soil or in the mud and/or wherein the collector is made out of material like concrete or steel. 
     
     
         48 . A water injection platform according to  claim 45 , wherein the water injection platform furthermore comprises a monitor system for measuring soil strength and density for determining the dredging power, the dredging effort in hours and the water injection volume to erode, liquefy and mobilise an underwater sediment layer and/or wherein the water injection platform comprises a monitor system for predicting when the sediment needs to be removed from the collector for guaranteeing a predetermined nautical bottom level and/or wherein the water injection platform comprises a pumping station on a dredging ship for pumping the sediment from the collector towards a dredging ship or a stationary pumping station for pumping the sediment from the collector towards a pipe line to relocate the sediment to a dumping or treatment site where the sediment is permanently stored or where it is re-suspended and carried away from the area temporally or permanently. 
     
     
         49 . A monitor system for assisting a dredging process in a navigation channel, the dredging process comprising a step of performing agitation for mobilizing sediment and displacing the mobilized sediment to a collector being a trench in the navigation channel wherein the trench has, when not being filled with sediment, a bottom level positioned substantially deeper than the nautical depth of the navigation channel and a separate step of, after solidification of the sediment collected in the collector, removing the solidified sediment from the collector so that the collector again has a bottom level positioned substantially deeper than the nautical depth of the navigation channel, the monitoring system being adapted for determining any of soil strength and/or density and determining based thereon any or more of the dredging power, the dredging effort, the water injection volume to erode, liquefy or mobilise the underwater sediment layer, and/or for predicting when the sediment needs to be removed from the collector for guaranteeing a predetermined nautical bottom level.