Capping device for uniform capping of subaquatic sediments

A method for delivering a substantially uniform depth of capping material to a selected portion of the sediment surface of a body of water, said method comprising the steps of:

• providing capping material to a hopper in operative communication with at least one rotary feeder, said at least one rotary feeder being in operative communication with an array of vertically submerged tremies depending from a capping vessel operable to be moved over said selected portion of the sediment surface along a predetermined course, wherein each tremie of said array of tremies is adapted to be extensible and is provided with means to effect the selective extension thereof;
• detecting the depth and profile of the sediment along the predetermined course of the platform by means of a detector disposed to the fore of said platform, wherein said means for effecting the extension of each of said tremies is provided with controlling information from said fore detector;
• causing the at least one rotary feeder to rotate at a predetermined rate relative to the desired depth of capping required and the velocity of said capping vessel;
• and
• causing said capping vessel to move along the predetermined course while delivering the desired depth of capping material to the sediment surface.

A method for delivering a membrane to the sediment surface of a body of water and covering said membrane with a substantially uniform depth of capping material along a predetermined course, said method comprising the steps of:

• providing capping material to a hopper in operative communication with at least one rotary feeder, said rotary feeder being in operative communication with an array of vertically submerged tremies depending from a capping vessel adapted for controlled movement along a predetermined course, wherein each tremie of said array of tremies is adapted to be extensible and is provided with means to effect the selective extension thereof;
• detecting the depth and profile of the sediment along the predetermined course of the platform by means of a detector disposed to the fore of said Platform, wherein said means for effecting the extension of each of said tremies is Provided with controlling information from said fore detector;
• providing a roll of membrane material on a roll means disposed to the fore of said array of tremies and adapted to be proximate the sediment surface, said roll means adapted to unroll said membrane at a predetermined controlled rate;
• unrolling the membrane from the roll at a predetermined rate and anchoring the leading edge thereof to the sediment surface;
• rotating said at least one rotary feeder at a predetermined rate relative to the desired depth of capping required and the velocity of said capping vessel;
• and
• causing said capping vessel to move along said predetermined course so as to lay said membrane and provide a capping thereto substantially simultaneously.

A method for delivering a substantially contiguous overlapping membrane to an area comprising the sediment surface of a body of water and covering said membrane with a substantially uniform depth of capping material over the area, said method comprising the steps of:

• providing capping material to a hopper in operative communication with a plurality of rotary feeders, each of said rotary feeders being in operative communication with an associated tremie of an array of vertically submerged tremies depending from a capping vessel, said capping vessel adapted for controlled movement along a predetermined course;
• providing a roll of membrane material on a roll means disposed and adapted to be proximate the sediment surface to the fore of said array of tremies and laterally offset therefrom a predetermined amount, said roll means adapted to unroll said membrane at a predetermined controlled rate;
• unrolling the membrane from the roll at a predetermined rate and anchoring the leading edge thereof to the sediment surface;
• rotating said at least one rotary feeder at a predetermined rate relative to the desired depth of capping required and the velocity of said capping vessel;
• causing said capping vessel to move along a first predetermined course over the area to be covered, so as to lay said membrane and provide a capping thereto substantially simultaneously, whereby the membrane is substantially covered save the edge in the offset direction;
• causing said capping vessel to move along subsequent predetermined courses over said area to be covered, wherein each of said subsequent courses is laterally displaced a predetermined width from said first course and repeats the step of the first course;
• and
• wherein during the last of said subsequent courses, no membrane is laid, and predetermined tremies of said tremie array provide capping material to the offset edge of the last laid membrane.