Methods for fabricating an underground septic tank

Abstract

Storage tanks, for example, underground septic tanks, and their methods of fabrication are provided. The tanks include a substantially liquid impermeable plastic vessel having a top, a bottom, and sides; a concrete container encasing and retaining the plastic vessel, the concrete container contacting the bottom and at least partially contacting the sides of the plastic vessel; and at least one opening for receiving effluent, for example, waste effluent, into the plastic vessel. The methods of fabricating the tanks include positioning a plastic vessel into an enclosure; introducing concrete into the enclosure about the plastic vessel; allowing the fluid concrete to cure to provide a substantially solid concrete container about the plastic vessel; and removing the plastic vessel having a concrete container from the enclosure. Vessel shape retaining devices are also disclosed. Aspects of the invention are uniquely adapted to underground storage.

1 - 10 . (canceled) 
     
     
         11 . A method for fabricating an underground septic tank, the method comprising:
 positioning a substantially liquid impermeable plastic vessel having a top, a bottom, and sides into a mold;   introducing a fluid concrete into the mold wherein the fluid concrete contacts the bottom and at least partially contacts the sides of the plastic vessel;   allowing the fluid concrete to at least partially cure to provide a substantially solid concrete container about the plastic vessel; and   removing the plastic vessel having a concrete container from the mold.   
     
     
         12 . The method as recited in  claim 11 , wherein introducing the fluid concrete into the mold comprises introducing the fluid concrete wherein the fluid concrete contacts the bottom, the sides, and at least partially the top of the plastic vessel. 
     
     
         13 . The method as recited in  claim 11 , wherein the method further comprises, prior to introducing the fluid concrete to the mold, retaining the plastic vessel in the mold to counteract buoyant forces on the plastic vessel. 
     
     
         14 . The method as recited in  claim 13 , wherein retaining the plastic vessel in the mold to counteract buoyant forces is practiced with chains. 
     
     
         15 . The method as recited in  claim 11 , wherein introducing the fluid concrete into the mold comprises a introducing the fluid concrete in a plurality of pours. 
     
     
         16 . The method as recited in  claim 11 , wherein the method further comprises, prior to introducing the fluid concrete, supporting the vessel above a bottom of the mold. 
     
     
         17 . The method as recited in  claim 11 , wherein the method further comprises, prior to introducing the fluid concrete, introducing reinforcement elements about the vessel. 
     
     
         18 . The method as recited in  claim 11 , wherein the method further comprises, prior to introducing the fluid concrete, introducing ballast to the vessel. 
     
     
         19 . The method as recited in  claim 11 , wherein the method further comprises retaining at least one of the top, the bottom, and at least one of the sides from deflecting. 
     
     
         20 . The method as recited in  claim 19 , wherein retaining at least one of the top, the bottom, and at least one of the sides from deflecting comprises introducing a retaining device into the substantially liquid impermeable plastic vessel, wherein the retaining device minimizes deflection of at least one of the top, the bottom, and at least one of the sides. 
     
     
         21 - 60 . (canceled) 
     
     
         61 . The method as recited in  claim 11 , wherein the substantially liquid impermeable plastic vessel comprises a substantially liquid impermeable cylindrical plastic vessel. 
     
     
         62 . The method as recited in  claim 61 , wherein the substantially liquid impermeable cylindrical plastic vessel comprises a longitudinal axis; and wherein positioning the substantially liquid impermeable cylindrical plastic vessel into the mold comprises positioning the substantially liquid impermeable cylindrical plastic vessel into the mold wherein the longitudinal axis is substantially horizontal. 
     
     
         63 . The method as recited in  claim 11 , wherein the substantially liquid impermeable plastic vessel comprises at least one opening for receiving waste effluent. 
     
     
         64 . The method as recited in  claim 63 , wherein the at least one opening for receiving waste effluent comprises a first opening at a first end of the cylindrical plastic vessel and at least one second opening at a second end of the cylindrical plastic vessel, opposite the first end. 
     
     
         65 . The method as recited in  claim 11 , wherein the plastic vessel having the concrete container is adapted to withstand vehicle loading. 
     
     
         66 . The method as recited in  claim 65 , wherein the vehicle loading comprises at least AASHTO H-20 LL vehicle loading. 
     
     
         67 . The method as recited in  claim 12 , wherein introducing the fluid concrete into the mold comprises introducing the fluid concrete wherein the fluid concrete completely encases the plastic vessel.