Module and assembly for underground management of fluids for shallow-depth applications

A modular assembly for managing the flow of fluid beneath a ground surface, comprising: a first precast concrete module (100) comprising a first deck portion (130) having a first top deck surface (134), opposing spaced-apart sidewalls (110, 120) integrally formed with and extending downward from opposing longitudinal sides of the first deck portion to respective bottom edges, the opposing spaced-apart sidewalls sloping outward and away from one another as they extend downward from the first deck portion to the respective bottom edges, wherein each sidewall has an interior surface (112, 122) and an exterior surface (114, 124); at least one seat (1600) having a downwardly facing surface (1604) comprising a ledge extending inward from the interior surface of the opposing spaced-apart sidewalls at a location between an underside (132) of the first deck portion and the respective bottom edges, the at least one seat being configured to permit the first precast concrete module to be stacked upon another precast concrete module located below the first precast concrete module; at least one shoulder (118, 128) extending outward from at least one of the opposing spaced-apart first sidewalls, the at least one shoulder having an upwardly facing surface, the first precast concrete module being configured to support another precast concrete module located above the first precast concrete module whereupon the ledge of the another module above the first precast concrete module can be seated upon the upwardly facing surface of the shoulder of the first precast concrete module; and a link slab (150) supported by the at least one shoulder and comprising a top slab surface (152) being flush with the first top deck surface; wherein the first deck portion and the opposing spaced-apart sidewalls define an interior fluid passageway with respect to the first module, the interior fluid passageway having a top portion adjacent an underside of the first deck portion and a bottom portion adjacent the respective bottom edges of the opposing sidewalls, the interior fluid passageway having a flared configuration that widens as it extends from the top portion to the bottom portion; and wherein the interior fluid passageway defines a longitudinal flow path. The invention provides a precast module that can be securely stacked underneath or above another identical module for storage and transport.