Abstract:
A sump containment apparatus for a fuel storage tank has a manhole skirt communicating with a sump interior, a bladder seal with a first portion secured in sealing engagement about an opening in the sump, and a second portion disposed about an inner surface of the manhole skirt and urged into sealing engagement with the inner surface by mechanical compression, preferably by an expansion ring. An observation port in a manhole cove is openable for viewing into the sump.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     Fuel tank installations at service stations having underground tanks, have long had the problem of water entering from the manhole structure above a tank and draining downwardly into a sump structure above a tank. The problem is particularly acute where high ground water levels of underground water tables extend to within a few inches of the ground surface. 
     In the prior art, sump covers have generally been utilized to prevent such water from entering the sumps, as by draining down via the manhole cover, etc., into the sump. Such sump covers are generally effective for a while after installation. However, when it is necessary to remove such cover, as for inspections, etc., workers often do not re-secure the cover correctly. Threaded fasteners have long been utilized in the installation of sump covers. In the tightening of such threaded fasteners, both in initial installation and in later closures after openings, as for periodic inspections required by law, leakage can occur. As a result of human error, uneven tightening of the threaded fasteners or screws can readily occur, as when tightening a cover or structure with a gasket or O-ring, with one screw being tightened too tightly relative to other screws, resulting in tilting of a cover with resultant leakage. Disassembly may occur, or a screw may be omitted, or a screw not tightened at all. 
     The present invention provides positive sealing with application of only relatively limited pressure. Positive sealing is provided at the level of the sump and higher in a manhole to prevent leakage, even when totally submerged, thus to prevent contamination of ground soil. 
     The present invention eliminates the sump cover of the prior art, and the problems associated therewith, and provides a bladder seal which prevents entry of water from above, as via the manhole cover or other leakage into the sump, typically caused by high ground water level leakage. The manhole cover and its annular resilient seal normally prevent such entry. 
     Improved positive sealing according to the invention is provided by a manhole skirt communicating with the interior of a sump, and a bladder seal having spaced-apart first and second portions, and a bladder portion therebetween the first portions being secured in sealing engagement with an upper surface of the sump, and the second portion of the bladder seal being sealingly engaged by being compressed about an inner surface of the manhole wall. The first bladder seal portion is preferably secured by clamped engagement with a flange portion disposed about a sump opening communicating with the manhole skirt, and the second bladder seal portion is preferably sealingly engaged with the manhole wall by an expansion ring with segments urged apart by expansion bolt mechanisms. 
     An observation port opening in the manhole cover is closable by a lid member which is opened and closed by operation of a latch mechanism. With the observation port open, the sump interior is readily viewed to ascertain whether or not water has entered thereinto from above. The observation port eliminates any necessity for the opening and lifting of a heavy manhole cover, normally requiring two persons, then reaching down and removing a sump cover by removing threaded fasteners, etc., in order to determine whether there is water in the sump. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cutaway perspective view showing apparatus of the invention in relation to an underground fuel tank and sump, with conventional concrete structure at ground level and disposed about the tank; 
     FIG. 2 is a cutaway perspective view of manhole and sump structures incorporating the present invention; 
     FIG. 3 is a cutaway perspective view of a modified form of the invention; 
     FIG. 3A is a sectional view of a modified form of a portion of the embodiment of the invention shown in FIG. 3; 
     FIG. 4 is an enlarged sectional view, taken at line  4 — 4  in FIG. 2; 
     FIG. 4A is a sectional view showing a modified form of a portion of FIG. 4; 
     FIG. 5 is an enlarged sectional view, taken at line  5 — 5  in FIG. 2; 
     FIG. 6 is a fragmentary view of a portion of the manhole cover with a cover plate therein according to the invention; 
     FIG. 7 is a sectional view taken at line  7 — 7  in FIG. 6; and 
     FIG. 8 is a view taken at line  8 — 8  in FIG.  7 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings, FIGS. 1 and 2 show a preferred embodiment of apparatus  10  according to the invention mounted atop a sump  12  in an underground fuel tank. 
     A manhole having a wall or skirt  14  is disposed on the sump and supported by engagement of upper ring member with the concrete pavement  15 , as shown. The concrete pavement is disposed about the manhole upper member and concrete walls and flooring are disposed about the tank. 
     A bladder seal  20 , typically fabricated of rubber, has an enlarged first base portion  22  with openings therethrough to receive bolts  24 . A mounting ring  26  is positioned atop the first portion  22  which is seated on an inwardly extending flange  18  of sump  12 . Bolts  24  cooperate with nuts threaded thereon at the lower side of the flange to clamp the components together to provide positive sealing to prevent entry of water into the sump. The bladder seal  20  has a central bladder portion  28  and an upper second portion  30  (FIG. 4) which defines a plurality of sealing ribs  32  adapted to extend about and sealingly engage the inner surface of the wall  14 , thus to provide multiple seals. Parallel ridges  33 ,  34  are also defined in upper portion  30 , as shown. 
     An expansion ring  36 , comprising three arcuate sections, is disposed between annular ridges  33 ,  34  of the upper seal portion, and is adapted to fit about the interior surface of manhole skirt  14 . Conventional expansion bolt assemblies (FIG. 5) are disposed on adjacent end portions of the arcuate sections. Expansion of the arcuate sections relative to each other, by operation of bolt member  40 , exerts compressive force on the bladder seal upper second section  30  to provide sealing engagement with the inner wall of manhole skirt  14 , thereby providing positive sealing by the multiple sealing ribs  32 . 
     Shown in FIG. 4A is a modified form of bladder seal  20   a  with a bladder portion  28   a  of serpentine configuration to enable elongation thereof with rising of manhole skirt  14  caused by rising of the ground surface level under frost or freezing conditions. 
     It will be understood from the foregoing that positive sealing is provided by the first portion  22  of the bladder seal at the sump, and that positive sealing is also provided at the higher level of the multiple sealing ribs of the upper bladder portion  30 , thus to prevent water entering the sump, particularly from above. 
     FIG. 3 illustrates a modified form  50  of the apparatus of the invention, which is adapted for mounting on a pre-existing sump installation which has been modified by the cutting of an opening in a pre-existing upper sump wall  52 , along a circular line  54 , and by clamping the lower first portion  22  of the bladder seal to a remaining inwardly extending sump flange  56 . The structure and function of the apparatus of this embodiment is otherwise like that of the embodiment of FIGS. 1 and 2. 
     In both the embodiment of FIG.  1  and the embodiment of FIG. 3, a manhole cover  58  and an annular sealing ring  60 , disposed in a groove in a flange at the upper end portion of skirt  14  provide positive sealing against entry of water. 
     An observation port structure  80  (FIGS. 6 to  8 ) comprises a lid plate  82  disposed in a circular opening in a manhole cover  58 . The lid plate is sealingly engaged with a latch body  86  by an O-ring  88  secured by a cam lock latch body. Latch member  90  is movable or pivotable by rotation of member  93  by an appropriate wrench. The latch member may thus be moved or rotated to a latched position wherein end portions  92 ,  94  are moved into engagement under a circular flange  96 , or into an unlatched position (shown in FIG. 8) when the latch end portions are in registration with recesses  98  in the flange, thus enabling the lifting of the assembly comprising the lid plate and the latch member through the opening  84 . Recesses  100 , provided in the manhole cover adjacent to the ring plate, are accessed by a tool to pry open the lid plate when necessary. 
     With this assembly removed from the opening, a person may readily observe the sump interior to ascertain whether or not there is liquid therein, and whether any other problem may exist. 
     Substantial savings of time and cost are provided by provision of the observation port. Typically, in the prior art, two persons are required in the lifting of a heavy manhole cover, typically weighing 100 lbs. or substantially more, in order to remove the manhole cover, and two persons being required by OSHA regulations requiring two persons to lift over 50 lbs. These persons must also remove a conventional sump cover which involves removal of screws through threaded fasteners, and reaching far down to the sump cover. 
     By eliminating the prior art sump cover, and providing the observation port, the task of removing a manhole cover, and removing a sump cover in order to observe whether there is liquid under the sump, are eliminated. 
     Thus there has been shown and described a fuel tank sump containment apparatus which fulfills all the objects and advantages sought therefor. Many changes, modifications, variations and other uses and applications of the subject invention will, however, become apparent to those skilled in the art after considering this specification together with the accompanying drawings and claims. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.