UNDERGROUND STORAGE TANK AND SEPTIC WASTE TREATMENT SYSTEM

摘要

A polymeric underground storage tank (3) for holding effluent, and the like, has a spherical first wall portion (11) joined to a collar (6) surrounding an accessway with a closure (5). The collar (6) is fixed to the first wall portion (11) above an equator (33) of the first wall portion (11). An offset (41) is formed between the axis of the collar (31) and the diametrical axis of the first wall portion (30). A bulbous second wall portion (14) joins the first wall portion (11) to the collar (6) to provide an increased liquid surface area near the top of the tank (3). A septic waste treatment system includes a plurality of such underground tanks (3) with pipes transferring products between them.