Hydraulic and earth engineering – Foundation – Columnar structure
Reexamination Certificate
1998-05-12
2001-01-09
Lillis, Eileen D. (Department: 3673)
Hydraulic and earth engineering
Foundation
Columnar structure
C405S055000
Reexamination Certificate
active
06171029
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to containment sumps for underground storage tanks, and more particularly, to an improved method and apparatus for retrofitting underground storage tanks with a containment sump.
BACKGROUND OF THE INVENTION
Estimates place the number of underground storage tanks (USTs) (as defined by the Code of Federal Regulations) in the United States at around 2 million. In 1988, the Environmental Protection Agency promulgated a new set of regulations for USTs, detailing stricter release detection, overfill prevention and containment, financial responsibility, and clean-up requirements. Under this new set of regulations, UST owners were given 10 years to bring their systems into compliance. Instead of replacing non-compliant USTs, many owners have decided to bring their tanks into compliance by upgrading and retrofitting the tanks as necessary.
One of the common areas in which upgrading and retrofitting of existing USTs is necessary is in containment sumps. A containment sump is generally defined as a liquid-tight compartment enclosing the turbine pump and piping connections at the top of an UST, which provides containment of any product leaks. However, conventional methods and processes for retrofitting existing USTs with containment sumps are fairly inconvenient. For example, in order to install the containment sump it is usually necessary to first cut, break up and remove concrete or other paving material overlying the UST and then excavate the tank backfill away from the top of the UST. Additionally, during the installation process it is often necessary to cut the existing piping associated with the turbine pump and UST.
Consequently, a need exists for an improved method and apparatus for retrofitting USTs with a containment sump.
SUMMARY OF THE INVENTION
The present invention, therefore, provides an improved method and apparatus for retrofitting USTs with a containment sump that overcomes the disadvantages of the prior art installation processes. Specifically, only a small area of paving material just around the turbine pump needs to be removed and then the sump is installed without first excavating the tank backfill away from the top of the UST or cutting existing piping associated with the turbine pump and UST.
The containment sump wall is a prefabricated cylinder or ring of fiberglass-reinforced plastic (FRP). The ring is pushed downward into the tank backfill around the turbine pump, while sand or gravel inside the ring is removed by means of a vacuum device. During the installation process, vertical slots are cut into the ring as needed to allow the ring to clear the piping associated with the turbine pump. When the ring is in position around the turbine pump, a sump floor is constructed in place, and bonded to the ring using conventional fiberglass layup technology. Additionally, any slots or other openings made in the ring during installation are also repaired by fiberglass layup. Moreover, any piping that penetrates the sump is isolated from the sump wall and floor by means of FRP sleeves, which are bonded to the wall or floor of the sump. Liquid-tight connections between the sleeves and a corresponding pipe are achieved by use of rubber termination boots.
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McGill Milton D.
Wyper Thompson W.
Christie Parker & Hale LLP
Lagman Frederick L.
Lillis Eileen D.
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