A cutterhead for dredging a body of water. The cutterhead comprising a shroud including a top wall, a bottom wall, and two sidewalls each extending between the top and bottom walls. The cutterhead additionally comprises a rotatable cutterbar at least partially received within an interior space presented by the shroud, a first water-jet bar extending along a portion of the top wall of the shroud, and a second water-jet bar extending along at least a portion of one of the two sidewalls. The cutterbar and the water-jet bars are configured to generate a slurry of fluidized material from the water-bed.

A microtrencher having a vacuum system configured to clean spoil from a microtrench having a rotating brush. A method of using the microtrencher to cut a microtrench in a roadway and using the vacuum system to clean spoil from the roadway and microtrench.

A microtrencher having a vacuum system configured to clean spoil from a microtrench having a rotating brush. A method of using the microtrencher to cut a microtrench in a roadway and using the vacuum system to clean spoil from the roadway and microtrench.

A dredging head assembly for deploying on the bed of a body of water, is provided, the assembly comprising a cutter housing having a cutting opening for extending over a section of the bed from which material is to be removed; a cutting assembly disposed within the cutter housing, the cutting assembly operable through the cutting opening in the cutter housing to loosen material from the bed; and an outlet opening in the cutter housing for removing water and entrained material from within the cutter housing under suction; wherein the cutter housing comprises a plurality of holes therein, in use water being drawn into the cutter housing through the holes under the action of reduced fluid pressure within the cutter housing. A dredging assembly comprising the dredging head assembly and a method of dredging are also provided.

A microtrencher having a vacuum system configured to clean spoil from a microtrench having a side shroud and a suction nozzle. A method of using the microtrencher to cut a microtrench in a roadway and using the vacuum system to clean spoil from the roadway and microtrench.

A method for renewing a placement area may include one or more of the following steps. A dredge barge may be disposed inside a placement area containing materials dredged from one or more other locations and disposed within the placement area. Material may be dredged from the placement area. The dredged material may be processed. Water may be added to the placement area to maintain a flotation level of the dredge barge. The dredge barge may be removed from the placement area. The water may be removed from the placement area. This process may allow a placement area to be continually renewed and may allow useful materials to be recovered from a placement area.

Systems and methods for recovering and concentrating rare earth elements from seabed sediment deposits using seabed excavators and shipboard processing systems.

In some embodiments, a system may include a harvesting unit configured to operate under water to traverse and extract gas from clathrate hydrate deposits. The harvesting unit can include a housing defining an enclosure at least partially open along a bottom portion to receive a clathrate slurry associated with a selected one of the clathrate hydrate deposits. The harvesting unit may further include a separator chamber within the housing defining a negative pressure and configured to receive the clathrate slurry and a skirt coupled to the enclosure adjacent to the bottom portion and configured to form a flexible barrier between the enclosure and an external environment. The skirt may be formed from a plurality of elements configured to allow fluid flow therethrough.

Systems and methods for recovering and concentrating rare earth elements from seabed sediment deposits using seabed excavators and shipboard processing systems.

A dredging head assembly for deploying on the bed of a body of water, is provided, the assembly comprising a cutter housing having a cutting opening for extending over a section of the bed from which material is to be removed; a cutting assembly disposed within the cutter housing, the cutting assembly operable through the cutting opening in the cutter housing to loosen material from the bed; and an outlet opening in the cutter housing for removing water and entrained material from within the cutter housing under suction; wherein the cutter housing comprises a plurality of holes therein, in use water being drawn into the cutter housing through the holes under the action of reduced fluid pressure within the cutter housing. A dredging assembly comprising the dredging head assembly and a method of dredging are also provided.