[Goal] With regard to a "deep sediment layer replacement processing method for waste" in which waste is inserted by force into deep ocean sediment and which has been proposed heretofore, to facilitate identification and recognition of the post-processing position and area, and to facilitate prediction of unexpected trouble associated with environmental conservation, and steps related thereto. [Configuration] The area encompassing where a "deep sediment layer replacement processing method for waste" in which waste is injected into deep sediment layers is performed is configured to be an enclosed and cut-off "hollow water area (UTSURO)" by using a bank body configuration such as a purification bank or an impermeable bank body (cut-off sheet pile bank or the like). A verifiable water area is established. [Effect] A gravity-type bank body that configures the enclosed and cut-off "hollow water area (UTSURO)" using a structure has effects for restricting the range in which waste can be inserted by force by using su
