ScourMat fabric forms are identical in performance to SeaMats except that they are designed to be placed and inflated underwater by divers. This application is ideal for span correction and cover in shallow or medium depths, or any other requirement where limited vessel size or crane capacity precludes the use of precast mats. Because the crane is not integral to setting mats, the working radius from a DSV or barge can be as great as 600 feet without relocating the support vessel. Water to water transfer of resupply materials is significantly safer as a result of the 3000 lb load limit.
The material design can be altered to maximize individual element weight and overall weight per square foot, resulting in a mat structure with superior resistance to tractive force without the need of larger lifting equipment for placement on the sea floor. Once mobilized to location, the heaviest lift during operations is 3000 lbs. This allows for mats as heavy as 110 pounds per square foot or 350 lbs per element with minimal marine assets. A comparable pre-cast mat would weigh 17,500 pounds not including lifting rigging. In addition to increased element weight, the matrix of elements can be arranged in a running bond pattern to control flexibility in one direction.
This ScourMat project covered approximately 950 feet of shallow and exposed 30 inch gas pipeline into the bay. Total project length was 1350 feet. The mat was pumped in place and has visible grout-filled scour brakes along both edges to prevent undermining or flipping. Element weight is 188 pounds per block and the running bond pattern provides superior resistance to storm damage.
ScourMats can be inflated with a variety of pumping equipment. SBS has developed a single-lift self-contained portable mixing and pumping unit for remote locations, smaller DSVs and shallow draft barges.