| 摘要 |
An underground storage tank (3) has a spherical first wall portion (11) joined to a collar (6) surrounding an accessway. The collar is fixed to the first wall portion above an equator of the first wall portion toward an outer side of the first wall portion. A bulbous second wall portion (14) joins the first wall portion to the collar portion to provide an increased liquid surface area near the top of the tank. An aperture may be cut in localized reinforcement in the wall of the collar to receive a pipe for connection to an adjacent tank. The reinforcement has a planar face that projects outwardly from an adjacent outer surface of the collar. A septic waste treatment system includes a plurality of such underground storage tanks with pipes for transferring products between the tanks. Connectors connect the offset collars of the tanks to form an assembly. The connectors are hollow member having walls substantially enclosing an interval volume concave faces for abutting the convex outer connector-receiving on the collars of the tanks.
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