Abstract: The disclosure relates to a method of producing and laying on the ground a ballasted mat defined by two layers of sheet material joined together along parallel lines and enclosing particulate ballast material by providing two sources of sheet material and continuously drawing the sheet material from the sources under the influence of the ballasted mat, continuously leading the sheet material to meet in generally overlapped relationship, seaming the sheet material to enclose at least two parallel compartments, continuously filling the two parallel compartments with particulate ballast material, continuously advancing the sources of sheet material over the ground adapted to be covered by the ballasted mat, continuously lowering the ballasted mat to the ground during the formation thereof and during the advancing of the sources of sheet material in timed relationship to the drawing of the sheet material from the two sheet material sources, and seaming cross-wise the end of each ballasted mat and the adjacent end

Abstract: This invention relates to a system for depositing and protecting sediments on the floor of a body of water by utilizing a pair of rigid cast sheets of heavy material which are hinged together to form an arch-shaped device with the weight thereof being utilized to maintain the device in bridging relationship to a pipe or like installation resting on the floor of the body of water. The arch-shaped device has a generally central apex portion and opposite leg portions with respective upper convex and lower concave surfaces which diverge away from each other in a direction away from the apex portion.