Abstract:
A seamless, double-walled sump is disclosed for collecting run-off materials and waste products. The sump includes a primary containment vessel and a secondary vessel, integrally molded into a single seamless unit. The sump includes a plurality of ribs that cooperate with surrounding concrete or other enclosing material to anchor the sump and prevent floating. The sump may also include a fabric outer layer that serves as an interface between the concrete and the sump to prevent corrosion.

Description:
BACKGROUND 
     Sumps, also referred to as catch basins, have traditionally been utilized in chemical, petrochemical, metal finishing, industrial and municipal operations to capture the flow of hazardous materials. Due to the development and implementation of storm water runoff regulations, the use of sumps is now common in parking lots, salvage yards, scrap yards, and anywhere that rain can combine with oil, grease, fuel, or other hazardous materials. The sumps are typically located in holes dug out of the pavement so that only their upper surface is exposed, allowing run-off to collect directly into the sump. The concrete or asphalt surrounding a sump is generally sloped to the sump to provide for gravitational flow and capture. 
     In current constructions, sumps are commonly constructed from a layer of concrete with a protective coating of tile, brick, or FRP. Other solutions include molded single wall tanks, however these tanks have a tendency to lift or “float” out of their hole and become either damaged or unusable. Anchored sumps of these types are traditionally expensive because the materials necessary to create the anchored sump are costly and there is relatively significant fabrication labor. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the shortcomings of the prior art and comprises a seamless, rotationally molded double wall sump. The seamless, one piece double wall design is unique to the industry and has inherent advantages over previous designs. The dual wall design provides insurance against leakage, and the seamless design prevents seepage or leaks from penetrating the sump. The double wall design may be molded with a fabric faced grating seat as an integral part. The design results in a cost effective, high performance solution that can be produced in large quantities with relatively little labor costs compared with previous sump manufacturing concepts. The double walls form a gap that may be filled with a foam stiffener to further increase the rigidity and strength of the sump. 
     For both retrofit and new construction, the sump of the present invention is cast-in-place using standard concrete materials and methods. That is, the sump is placed into wet cement formed in a pit and allowed to harden around the sump. The adjoining ground level is set such that any liquids within the immediate area will flow to the sump for further disposition which can include outlet piping for gravity flow to a larger collection tank. Or, the sump can be equipped with a level control device and relays to activate a pump for “lifting” or transferring the liquids to another location for storage and/or treatment. The integral ribs of the secondary containment portion of the sump function to “lock” the sump into the surrounding concrete to prevent flotation of the sump in “high water table/empty sump” conditions. The integral fabric face, which can be a polyester or polypropylene sheet, is located on the vertical side and top of the grating seat to allow the thermoplastic sump to be effectively integrated with the chemically resistant flooring system being applied to the surrounding concrete floor. This feature provides for the isolation of the interface between the sump and concrete. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is top view of the sump of the present invention without the grate; 
         FIG. 2  is a cross sectional view of the sump of  FIG. 1 ; and 
         FIG. 3  is a cross-sectional view of the sump in ground with a pump installed to purge collected waste. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A sump  10  of the present invention is generally shown in  FIGS. 1-3 , comprising a cylindrical body  12  having two integrally molded vessels that form a double walled container. The first vessel  14  is a primary containment vessel that forms the interior of the sump  10  and is used to collect the various materials that the sump is designed to capture. The outer or secondary vessel  16  is a redundancy guard against leakage and is molded with the primary vessel to form a seamless integral one-piece unit of double wall construction. Between the two walls is a gap that may be filled with a stiffening foam  18  or other stiffening agent that can be injected between the two walls of the sump  10  during the molding process. The rigidity of the sump  10  is most critical at the upper portion of the sump, since the sump  10  is typically buried in the ground  20  (See  FIG. 3 ) and surrounded by concrete. If the upper portion of the sump is flexible, it can separate from the concrete and create gaps at the surface between the secondary vessel and the ground that can allow contaminants to seep between the cement and the sump, leading to contamination, corrosion, and other deleterious effects. 
     The outer surface of the secondary vessel  16  is formed with a plurality of ribs  22  that protrude radially outward, preferably in concentric circles, and serve as anchors for the sump  10  to prevent the sump from lifting or “floating” in the concrete. First the ground is excavated and then wet cement is poured into the hole to create the base for the sump  10 . Before the concrete sets, the double walled sump  10  is placed on the cement and additional cement poured around the walls to encase the sump  10  in wet cement until only the upper edge  24  of the sump  10  is visible in the concrete. The wet cement fills the gaps  26  between the ribs  22 , and as the cement hardens the ribs  22  and the interleaving cement ridges formed in the gaps  26  prevent the sump from rising upward. 
     The sump  10  may be formed with a first port  28  along the lower surface that can be used to drain the sump as it fills with materials. Piping (not shown) connecting the sump through the port  28  can be gravity fed, so that as material collects when it reaches the port it is carried away under the influence of gravity to a collection area. Alternatively, the port and connecting piping can be coupled to a pump  30  that extracts the material collected in the sump. The pump  30  can be manually actuated, timer actuated, or it may be actuated upon the signaling of a fluid level sensor (not shown) incorporated into the sump. The level sensor determines the level of the collected waste in the sump  10 , and sends a signal to the pump  30  when the level reaches a predetermined position or elevation in the sump to prevent overflow. Alternatively, the level sensor may send a signal to a processor (now shown) remote from the sump that can be used to actuate the pump  30  or other drainage measures. 
     The sump  10  may be configured with a leak detection sensor  32  to warn if the primary container  14  becomes compromised. If the primary container  14  forms a crack or loses integrity, waste will enter the area between the primary container  14  and the secondary container  16 , collecting at the bottom of the gap between the two walls. If sensor  32  is placed at the bottom of the gap, it can send a signal to a nearby microprocessor to send an alarm that the sump needs repair. The leak detector can be as standard detector that detects a change in resistance or capacitance when in contact with a liquid. 
     It is preferable to have the surround ground  20  area adjacent the sump contoured or sloped so that all run-off will collect into the sump via gravity. The sump may also have a second port  36  that leads other collection areas into the sump, such that the sump acts as a localized collection reservoir. The sump  10  may also preferably be formed with a circumferential upper lip  38  that retains a grate  40 , such as a fiberglass grate, so that the opening of the sump  10  is not a hazard that workers can fall into. 
     The foregoing description is intended solely to be exemplary and not limiting as to the scope of the invention. There are many alterations and modifications that would be understood by one of ordinary skill in the art, and the invention is intended to include all such modifications, particularly as to pertains to use, materials, shape, dimension, and the like. For example, the sump could take on a rectangular shape without departing from the spirit or scope of the invention, or could be made from other materials suitable for the particular application. Thus, the invention should be construed to cover all such modifications and alterations, consistent with the language of the claims herein construed using their ordinary and customary meanings without limitation to anything depicted in the drawings or any descriptions above unless expressly limited.