1. Technical Field
This application relates generally to an attached sump collar for an underground storage tank, in particular, a flat-sided collar that accommodates pipe penetrations.
2. Background of the Technology
Storage tanks are used to store a wide variety of materials, such as gasoline, petroleum products, manufacturing liquid waste, sewage and other environmentally hazardous materials. Storage tanks are often located underground to conserve space. Concern about leaks in underground storage tanks (USTs) has lead to the adoption of a variety of products and methods for leak detection and secondary containment. For example, USTs are now typically constructed with materials such as fiberglass reinforced plastic (FRP) for improved resistance to corrosion and rusting. USTs also can be double-walled or triple-walled, where the tank is provided with a surrounding wall(s) to contain any fluid that leaks from the tank until repairs can be made. The annular space between the walls may contain alarm devices of a variety of designs to detect the passage of liquid from the interior tank or through the exterior wall(s). Multi-walled USTs manufactured by Xerxes Corporation, the assignee of the present application, have proven reliable over prolonged use for many years. Piping and attached containment sumps also may use double walls, as described, for example, in application Ser. No. 10/796,198, entitled “Double Walled Containment Sumps,” assigned to Xerxes Corporation.
A UST typically is provided with a manway, which allows access to fill or repair the tank. To access the interior of the tank, the manway generally is provided with a removable lid mounted on a flange. A variety of fixtures, e.g., filling devices, submersible pumps and the like, can run through the manway lid.
Access to the manway may be provided by a containment riser that surrounds the manway and extends from the UST to a point just below the ground level of the installation site of the UST. Access from the ground level to the top of the riser is accomplished at a street box having a removable manhole cover. Where the riser is intended for secondary containment, the containment system is typically called a sump. In this case, an alarm is frequently provided to detect the accumulation of liquid in the riser.
Since USTs are buried usually to a standard depth, the riser providing access to the manway likewise is typically a standard length. The riser may be fabricated from such materials as steel, polyethylene or fiberglass reinforced plastic (FRP). The riser may be attached directly to the outer wall of the tank by a variety of means known in the art, e.g. by “glassing” when the riser is made of FRP. The riser may be attached to the tank at the factory or at the installation site. Installation at the factory is preferred because the integrity of the seal between the riser and UST can be better controlled and the potential escape of harmful chemicals into the environment can be avoided. Given the combined height of the riser when attached to the UST, transporting a UST with a riser in place may be problematic if the transportation route to the installation site crosses under bridges, etc.
For these reasons, a sump collar first can be attached to, or molded as an integral part of, the UST. The top of the sump collar is designed to be easily mated with a riser, facilitating attachment of the riser in the field at the site of installation of the UST. The riser can be attached to the collar with adhesives, for example, creating a tight seal and avoiding release of harmful chemicals into the environment. Various means of attaching the collar to the UST and the riser to the collar are described in application Ser. No. 10/801,854, “Reverse Flange Collar Adapter and Reverse Flange Collar,” assigned to Xerxes Corporation and incorporated herein by reference.
The water table in many parts of the country may rise for extended periods to a height exceeding all or part of the riser. For that reason, Xerxes Corporation provides a watertight riser, described in U.S. Pat. No. 5,595,456, “Water-Tight Riser for Underground Storage Tank Manway,” incorporated herein by reference. Risers, however, are typically penetrated by pipes or other fixtures leading horizontally away from the manway, whether the riser is attached directly to a UST or to a collar. Connections between the pipes or other fixtures and the round wall of the riser are difficult to seal, and care must taken to ensure that these connections are watertight and provide some measure of leak resistance, especially where the water table exceeds the height at which the riser is penetrated by a fixture. Accumulated liquid within the riser otherwise could impede access to the manway or compromise the integrity of the various fixtures used with the UST.
The present invention addresses this and other needs by providing an attached flat-sided single-walled sump collar. Fixtures from the manway penetrate and connect with the collar at the flat wall surface, advantageously providing a more efficient seal around the connection between the fixture and the wall. In one embodiment, the fixture penetrates the flat wall surface at a nearly right angle. In another embodiment, the connection between the fixture and the flat wall surface is liquidtight.
Accordingly, in a first aspect of the invention, a UST assembly comprises a UST having a manway, a fixture extending from the UST through the manway, and an extended single-walled sump collar attached to the UST and surrounding the manway. The collar comprises a flat wall surface, i.e., it may be polygonal, and the fixture penetrates and connects to one of the flat wall surfaces of the collar. The fixture may penetrate the flat wall surface of the collar at a right angle or at nearly a right angle, and it may penetrate the collar horizontally. The assembly further may comprise a riser attached to the collar, where the riser extends to a street box at ground level and where the riser is not penetrated by a fixture extending from the UST. The attachments between the riser, collar and UST and the connection between the fixture and the flat wall surface of the collar may be liquidtight.
A second aspect of the invention provides a method of installing the UST assembly of the first aspect of the invention. The method comprises placing the UST in an excavated site and partially backfilling the site to cover the UST except for the manway and the attachment site of the flat-sided single-walled collar. In one embodiment, the method further comprises attaching the single-walled flat-sided collar to the attachment site on the UST, which may be done before or after backfilling. In another embodiment, the collar is molded as part of the UST. The method further comprises connecting a fixture extending from the UST to the flat wall surface of the flat-sided collar, where the fixture may penetrate the wall at a nearly right angle, and where the connection may be watertight. The flat-sided collar may be attached with adhesives, fiberglass, solder, or the like. The method may further comprise attaching a riser to the collar. The method additionally may comprise testing the attached flat-sided single-walled collar for water leaks.
The flat-sided single-walled collar may comprise a plurality of flat wall surfaces to facilitate alignment between the flat wall and fixture(s). In the preferred embodiment, the collar is polygonal in cross-section.
The invention provides a flat-sided single-wall collar for a UST, where a fixture from the UST penetrates the flat wall surface of the flat-sided collar. Connecting the fixture at a flat wall surface advantageously improves the efficiency of the seal between the fixture and the wall. The connection between the fixture and flat wall surface may be made at a nearly right angle. In one embodiment, the flat-sided single-wall collar helps provide liquidtight protection for the manway.
The UST 1 in
A riser cover 23 sits atop the riser 3. The riser cover 23 includes a removable domed cover 24. The collar 2, riser 3, riser cover 23 and domed cover 24 together may form a watertight containment sump 30. An access way 25, also known as a street box, provides access to the domed riser cover 24 via a ground level access way cover 10. The access way 25 and access way cover 10 are not part of the sump and are not necessarily watertight.
The double-walled UST 1 may include a hydrostatic monitoring system 4, which monitors the level of a monitoring fluid, typically brine, between the two walls of the double-walled UST 1. The hydrostatic monitoring system 4 includes a monitoring sensor 9 connected to a communication module 9a through tube 17. The tube 17 is accessible via access cover 16. The interior of the UST 1 may be filled from ground level by removing the cover 11a from the spill containment sump 11, which provides access to the fill cap 12 covering the fill tube 13.
A level probe 7 is disposed within the sump 30 and passes through the manway cover 14a to monitor the level of fluid within the UST 1. A single-walled vent pipe 19 is connected to the housing for the level probe 7 and passes through the wall of the riser 3 to provide venting for the UST 1. Also disposed within the sump 30 is an extractor assembly 21, which is connected through the manway cover 14a to ball float 15 in the interior of UST 1.
A double-walled pipe 20 carries gasoline from the UST 1. The double-walled pipe 20 also passes through a side of the riser 3. The interior wall 26 of the double-walled pipe 20 is connected, via a flex connector 27, to a pipe 18 passing through the manway cover 14a to the interior of the UST 1. The space between the outer wall 28 and the inner wall 26 of double-walled pipe 20 may be in fluid communication with the sump 30, so that fluid leaking from the interior wall 26 of the double-walled pipe 20 will be contained by the outer wall 28 and transported to the sump 30 for containment. A sensor 8 detects any fluid in the sump 30 and triggers an alarm system (not shown in
An example of the flat-sided single-walled collar according to the invention is depicted in
The collar 2a comprises a flat wall surface, as depicted in
The top edge or portion of the collar 2a may be round to facilitate mating the collar 2a with a riser 3. As depicted in
When the collar is attached to the UST at the factory, the collar extends the height of the UST system somewhat during transportation. The increase in overall height is no more than needed to accommodate fixtures, so the increased height generally is not expected to increase significantly the difficulty in transportation. In one embodiment, the collar is molded as an integrated component of the UST during the fabrication of the UST. Alternatively, the collar may be attached to the UST in the field before or after the UST is partially covered by backfilling. The collar may be attached with adhesives or a fiberglass lay-up, for example. The collar may be tested after it is attached to the UST to ensure that the seal between the collar and the UST is watertight.
Fixtures running horizontally from the manway of the UST run through holes made in the flat wall surface(s) of the flat-sided collar, and connections are made between the wall and fixture(s) using conventional techniques. Because of the improved sealing characteristics offered by the present flat-sided collar, the connection is easily and advantageously made liquidtight. In one embodiment, the connection between the fixture(s) and the wall surface is made at a right angle or at nearly a right angle. A riser or several riser segments may then attached to the flat-sided collar, so that the height of the system nearly reaches ground level. In one embodiment, the collar and riser form a liquidtight connection. The various connections can be tested by filling the riser and collar with water and examining the outside of the system for water or the water level in the connected riser and collar. The backfilling is then completed so that the sides of the collar, or collar and riser, are supported by backfill, and a street box is set over the riser cover to provide access to the UST.
While the foregoing specification teaches the principles of the present invention, with examples provided for the purpose of illustration, it will be appreciated by one skilled in the art from reading this disclosure that various changes in form and detail can be made without departing from the true scope of the invention.