Abstract:
A fueling environment reduces the likelihood of fuel spilling into the environment by positioning an underground storage tank directly beneath one or more fuel dispensers. The amount of piping thereby exposed to the environment is reduced, reducing the locations at which a leak may occur. The underground storage tank is partitioned into two or more chambers to hold different fuel grades such that a single tank may provide at least two fuel grades to the dispensers above the tank.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention is related to underground storage tanks in a service station fueling environment having a plurality of chambers to hold a plurality of different fuel types.  
         BACKGROUND OF THE INVENTION  
         [0002]    Fueling environments, such as service stations, must have a fuel supply from which fuel may be extracted and delivered to a fuel dispenser for delivery to consumers. The most conventional fuel supply is an underground reservoir, typically referred to as an underground storage tank. Service stations typically have at least two underground storage tanks, and sometimes three or four underground storage tanks to hold different types of fuel. For example, a first underground storage tank may contain low octane fuel; a second underground storage tank may contain high octane fuel; a third underground storage tank may contain an intermediate grade of fuel; and a fourth underground storage tank may contain diesel fuel. Pipes carry the fuel from the underground tanks to the fuel dispensers. Further, pipes may carry vapors removed during refueling of a vehicle from the fuel dispensers back to the underground storage tanks called “stage 2” vapor recovery.  
           [0003]    Environmental regulations have been passed at the state and federal level which require monitoring of fuel leaking into the environment from components in a fueling environment. To help catch leaks before they grow to environmentally threatening events, fueling environments have installed leak detection sensors and perform leak inspections periodically. Further, the land containing the fuel elements may be treated to help contain any leaks. For example, a concrete trench may contain piping components and a concrete bed with fill material may be used to house underground storage tanks.  
           [0004]    Because many fueling environments have multiple fuel dispensers and only one set of underground storage tanks, at least some of the fuel dispensers, of necessity, are positioned remotely from the underground storage tanks. This causes the piping interconnecting the underground storage tanks with the fuel dispensers to be extensive and frequently spread out over a relatively large lateral area below ground level. The extensive piping network requires more leak detection sensors and increases the amount of land which must be treated to help contain leaks.  
           [0005]    The problems experienced by fueling environments are exacerbated in high volume retail (HVR) environments such as fueling environments associated with member only discount price club stores. Specifically, HVR environments associated with stores such as WAL-MART, K-MART, SAM&#39;s CLUB, COSTCO, and the like, may have many fuel dispensers compared to a typical fueling environment given their customers&#39; high volume demands for fueling. These extra fuel dispensers each require the same piping connections, additional space, and create more opportunities for leaks.  
           [0006]    Thus, it would be advantageous to provide a system for use in a fueling environment which minimized piping requirements, especially in HVR fueling environments.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention builds on the teachings of commonly invented U.S. patent application Ser. No. 10/209,962, filed Jul. 31, 2002, entitled CONTAMINANT CONTAINMENT SYSTEM IN A FUELING ENVIRONMENT, which is hereby incorporated by reference in its entirety.  
           [0008]    A dedicated dual chambered underground storage tank may be positioned beneath a fueling island. The underground storage tank is dedicated in that it serves only those fueling islands directly above the tank, thus reducing the amount of fuel piping required. The dual chambers of the underground storage tank allow two grades of fuel to be supplied to the fueling islands, again reducing the need for piping from an underground storage tank remote from a fuel dispenser to deliver fuel to the fuel dispenser. Intermediate grades of fuel may be created by the fuel dispensers blending the high and low octane fuels from the dual chambered underground storage tank.  
           [0009]    While the dual chambered dedicated underground storage tanks may result in more tanks being installed at a service station, the footprint of land that must be treated to contain leaks is smaller and the amount of piping that runs beneath the surface is minimized since each tank supplies all the fuel connections to the fuel dispensers directly above the tank.  
           [0010]    As an alternate embodiment, the underground storage tank may have three or more chambers to accommodate differing types of fuel. In an exemplary embodiment, a third chamber is provided for intermediate octane fuel or diesel fuel. The size of the tank may change to reflect this additional chamber, or the tank may remain constant and the chambers reduced as needed or desired.  
           [0011]    The underground storage tank may be a double-walled tank, and may include appropriate leak sensors that communicate with a tank monitor as needed or desired.  
           [0012]    Those skilled in the art will appreciate the scope of the present invention and realize additional aspects thereof after reading the following detailed description of the preferred embodiments in association with the accompanying drawing figures. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the invention, and together with the description serve to explain the principles of the invention.  
         [0014]    [0014]FIG. 1 illustrates an exemplary fueling environment and some of the communicative links therein;  
         [0015]    [0015]FIG. 2 illustrates a cross-sectional view of a portion of a fueling environment showing one possible placement for the underground storage tank of the present invention;  
         [0016]    [0016]FIG. 3 illustrates a cross-sectional view of a portion of a fueling environment showing an alternate placement for the underground storage tank of the present invention;  
         [0017]    [0017]FIG. 4 illustrates an alternate embodiment of the embodiment illustrated in FIG. 2;  
         [0018]    [0018]FIG. 5 illustrates a three chambered underground storage tank embodiment of the present invention;  
         [0019]    [0019]FIG. 6 illustrates a first embodiment of a piping-underground storage tank interface;  
         [0020]    [0020]FIG. 7 illustrates a second embodiment of a piping-underground storage tank interface;  
         [0021]    [0021]FIG. 8 illustrates a flow chart outlining an exemplary method of constructing an underground storage tank according to the present invention; and  
         [0022]    [0022]FIG. 9 illustrates a flow chart outlining an exemplary method of installing an underground storage tank according to the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the invention and illustrate the best mode of practicing the invention. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the invention and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.  
         [0024]    Fueling environments come in many different designs. Before describing the particular aspects of the present invention (which begins at the description of FIG. 2 below), a brief description of a fueling environment follows. A conventional, exemplary fueling environment  10  is illustrated in FIG. 1. Such a fueling environment  10  may comprise a central building  12 , a car wash  14 , and a plurality of fueling islands  16 .  
         [0025]    The central building  12  need not be centrally located within the fueling environment  10 , but rather is the focus of the fueling environment  10 , and may house a convenience store  18  and/or a quick serve restaurant  20  therein. Both the convenience store  18  and the quick serve restaurant  20  may include a point of sale  22 ,  24 , respectively. The central building  12  may further house a site controller (SC)  26 , which in an exemplary embodiment may be the G-SITE® sold by Gilbarco Inc. of Greensboro, N.C. The site controller  26  may control the authorization of fueling transactions and other conventional activities as is well understood. The site controller  26  may be incorporated into a point of sale, such as point of sale  22 , if needed or desired. Further, the site controller  26  may have an off site communication link  28  allowing communication with a remote location for credit/debit card authorization, content provision, reporting purposes, or the like, as needed or desired. The off site communication link  28  may be routed through the Public Switched Telephone Network (PSTN), the Internet, both, or the like, as needed or desired.  
         [0026]    The car wash  14  may have a point of sale  30  associated therewith that communicates with the site controller  26  for inventory and/or sales. purposes. The car wash  14  alternatively may be a stand alone unit. Note that the car wash  14 , the convenience store  18 , and the quick serve restaurant  20  are all optional and need not be present in a given fueling environment  10 .  
         [0027]    The fueling islands  16  may have one or more fuel dispensers  32  positioned thereon. The fuel dispensers  32  may be, for example, the ECLIPSE® or ENCORE® sold by Gilbarco Inc. of Greensboro, N.C. The fuel dispensers  32  are in electronic communication with the site controller  26  through a LAN or the like.  
         [0028]    A tank monitor  36  may also be housed in the central building  12 . The tank monitor  36  typically has fluid level sensors and other data gathering devices positioned in the underground storage tanks of the fueling environment  10 , and potentially throughout the piping of the fueling environment  10 , which are communicatively coupled to the tank monitor  36 . The tank monitors  36  may communicate with the fuel dispensers  32  (either through the site controller  26  or directly, as needed or desired) to determine amounts of fuel dispensed and compare fuel dispensed to current levels of fuel within the underground storage tanks as reported by the sensors to determine if the underground storage tanks are leaking.  
         [0029]    The tank monitor  36  may communicate with the site controller  26  and further may have an off site communication link  38  for leak detection reporting, inventory reporting, or the like. Much like the off site communication link  28 , the off site communication link  38  may be through the PSTN, the Internet, both, or the like. If the off site communication link  28  is present, the off site communication link  38  need not be present and vice versa, although both links may be present if needed or desired. As used herein, the tank monitor  36  and the site controller  26  are site communicators to the extent that they allow off site communication and report site data to a remote location.  
         [0030]    The present invention is also suitable for use with a high volume retailer (HVR). Such a HVR may be functionally identical to the fueling environment  10 , but may reposition elements as needed. For example, the central building  12  may be a warehouse-like building, and the convenience store  18  may be turned into a full-fledged members-only discount store such as SAM&#39;s CLUB, COSTCO, or the like.  
         [0031]    For further information on how elements of a fueling environment  10  may interact, reference is made to U.S. Pat. No. 5,956,259, which is hereby incorporated by reference in its entirety. Information about fuel dispensers may be found in commonly owned U.S. Pat. Nos. 5,734,851 and 6,052,629, which are hereby incorporated by reference in their entireties. Information about car washes may be found in commonly owned U.S. patent application Ser. No. 60/380,111, filed May 6, 2002, entitled IMPROVED SERVICE STATION CAR WASH, which is hereby incorporated by reference in its entirety. An exemplary tank monitor  36  is the TLS-350R manufactured and sold by Veeder-Root. For more information about tank monitors and their operation, reference is made to U.S. Pat. Nos. 5,423,457; 5,400,253; 5,319,545; and 4,977,528, which are hereby incorporated by reference in their entireties.  
         [0032]    Against the backdrop of the fueling environment  10 , the present invention comprises creating a underground storage tank  34  as illustrated in FIGS. 2 and 3. The underground storage tank  34  may be double-walled so that leaks occurring by a breach of the inner wall are contained. The underground storage tank  34  is divided into two or more chambers  40 ,  42  that house different grades of fuel therein. For example, first chamber  40  may house low octane (87 for example) fuel, and second chamber  42  may house high octane (93 for example) fuel. An intermediate grade of fuel may be achieved by blending in the fuel dispenser  32  or by pre-providing the intermediate grade and storing it in a third chamber (see FIG. 5). For more information on blending, the interested reader is directed to U.S. Pat. Nos. 4,876,653 and 5,029,100, both of which are hereby incorporated by reference in their entireties. Other fuel types such as diesel fuel may also be stored in one of the chambers  40 ,  42  if needed or desired. The wall  44  separating the chambers  40 ,  42  may be a double wall if needed or desired to insure fuel separation integrity. Note further that while the wall  44  is displayed as being a vertical wall, it is possible that the wall  44  could be horizontal or otherwise oriented as needed or desired.  
         [0033]    Sensors  46  may be positioned in each chamber  40 ,  42  to determine fuel levels within the chambers  40 ,  42 , detect contaminants, monitor vapor pressure, and the like as needed or desired. The sensors  46  may communicate with the site controller  26  or the tank monitor  36  (or both) as needed or desired. For a more detailed discussion of sensors  46 , the interested reader is directed to U.S. Pat. Nos. 4,977,528; 5,544,518; 5,665,895, all of which are incorporated herein by reference in their entireties, and which describe tank-strapping curve sensors and the like.  
         [0034]    In addition to the sensors  46 , submersible turbine pumps  48 ,  50  may be positioned within the chambers  40 ,  42  respectively. The submersible turbine pump  48  may fluidly communicate with distribution heads  52 ,  54  via pipes  56 ,  58  respectively. The pipes  56 ,  58  lead to two exit locations in the double-walled vessel that forms the underground storage tank  34 . The submersible turbine pump  50  may fluidly communicate with distribution heads  60 ,  62  via pipes  64 ,  66  respectively. The pipes  64 ,  66  lead to two additional exit locations in the double-walled vessel that forms the underground storage tank  34 . More detail on exit locations is presented below with respect to FIGS. 6 and 7 discussed later in this application. The pipes  56 ,  58 ,  64 , and  66  may be double-walled pipes and are generally fully contained within the underground storage tank  34 .  
         [0035]    The submersible turbine pumps  48 ,  50  may be those sold under the trade name RED JACKET by Marley Pumps or the like as needed or desired such as that described in U.S. Pat. No. 6,126,409, incorporated herein by reference in its entirety. While it is possible that the motors and/or pumps of the submersible turbine pumps  48 ,  50  be positioned in the distribution heads and only a boom extended into the chambers  40 ,  42 , such is not preferred.  
         [0036]    Riser pipes  68 ,  70 ,  72 , and  74  carry fuel from the distribution heads  52 ,  54 ,  60 , and  62  to the fuel dispenser  32 . In an exemplary embodiment, the riser pipes  68 ,  70 ,  72 , and  74  are as short as feasible, meaning that the underground storage tank  34  is just beneath the level  76  of the pavement. This helps reduce the amount of piping that is exposed to the environment and thus able to leak into the environment. While not shown, vapor recovery piping may also be present and direct recovered vapor to one of the chambers  40 ,  42 .  
         [0037]    Note that in the embodiment of FIG. 2, the underground storage tank  34  crosses two fueling islands  16 . In contrast, the embodiment of FIG. 3 serves two fuel dispensers  32  on the same fueling island  16 . Note that in FIG. 3, the viewer sees the front faces of the fuel dispensers  32  as is well understood.  
         [0038]    In FIG. 4, a permutation suitable for use with any of the embodiments is disclosed, and is shown for simplicity with the embodiment of FIG. 2. The sumps  78  and  80  are positioned around the risers  68 ,  70 ,  72 , and  74  as illustrated. These sumps  78 ,  80  may be comparable to the ones sold by ENVIRON Products Inc. of P.O. Box 330, Smithfield, N.C., 27577, USA, and as illustrated in the concurrently submitted product catalog, which is hereby incorporated by reference. These sumps  78 ,  80  allow other containment options for the riser pipes  68 ,  70 ,  72 , and  74  beyond a simple concrete or fill material containment scheme.  
         [0039]    While it is contemplated that the underground storage tanks  34  will be dedicated to serve only those fuel dispensers  32  that are directly above the underground storage tanks  34 , it is possible that the underground storage tanks  34  may serve more dispensers  32 . U.S. Pat. Nos. 5,244,307; 5,921,712; and 6,270,285 all describe such alternate arrangements and are hereby incorporated by reference in their entireties. As used herein, the terms “above” and “beneath” mean at least partially directly above and beneath as opposed to an absolute vertical measurement.  
         [0040]    [0040]FIG. 5 illustrates another alternate embodiment, in which the underground storage tank  34  has three chambers  40 ,  42 , and  82  designed to hold three different fuel types. This configuration may be desirable if the fuel dispenser  32  requires three different types of fuel. For example, one chamber  82  may contain diesel fuel, and the other two chambers  40 ,  42  may contain high and low octane gasoline. Alternatively, the three chambers  40 ,  42 ,  82  may contain three different grades of gasoline. It should be appreciated that a four or more chambered underground storage tank  24  is also within the scope of the present invention. Additional pipes  84 ,  86  and riser pipes  88 ,  90  may be used along with distribution heads  92 ,  94 . An additional sensor  46  and an additional submersible turbine pump  96  may also be used to complete the system. Walls  44 A and  44 B may fluidly isolate one chamber from the others. For the reasons explained above with respect to wall  44 , walls  44 A and  44 B may be double walled.  
         [0041]    [0041]FIGS. 6 and 7 illustrate two different embodiments for how the pipes exit the underground storage tank  34 . In FIG. 6, a first aperture  98  may be designed such that pipes  58  and  64  may exit therefrom. A second aperture  100  may be designed such that pipes  56 ,  66  may exit therefrom. In practice, a collar or other capping mechanism (not illustrated) may be installed over the apertures  98 ,  100  and the distribution heads  52 ,  54 ,  60 , and  64  mounted thereon. It should be appreciated that more pipes may extend through the apertures if there are more than two chambers  40 ,  42 . For example, three pipes  58 ,  64 , and  84  may extend through the first aperture  98  if a three chambered underground storage tank  34  is used.  
         [0042]    In contrast, FIG. 7 illustrates dedicated apertures  102 ,  104 ,  106 , and  108  for the pipes  56 ,  58 ,  64 , and  66 . In this embodiment, a collar or capping element is applied to each aperture  102 ,  104 ,  106 , and  108  and a distribution head mounted thereon as needed or desired. Again, where an underground storage tank  34  has more than two chambers  40 ,  42 , additional apertures may be used.  
         [0043]    [0043]FIG. 8 illustrates an exemplary method of constructing an underground storage tank  34  according to the present invention. The interior hull of the double walled underground storage tank  34  is created (block  160 ). This step may include folding a piece of sheet metal or otherwise forming the interior wall. Once the hull is formed, or perhaps concurrently therewith, at least one interior wall  44  is installed to make at least two chambers  40 ,  42  within the underground storage tank  34  (block  152 ). The underground storage tank  34  is pierced with apertures  98 ,  100  or  102 ,  104 ,  106 , and  108  to create exit apertures for the piping (block  154 ). Piercing as used herein includes cutting a hole in the walls of the underground storage tank  34 , leaving voids in the walls which will form apertures, or other similar techniques to create apertures in the walls of the underground storage tank  34 . The piping is positioned in the underground storage tank  34 . The submersible turbine pumps  48 ,  50  are installed (block  156 ). A fitting collar or other device may be associated with the apertures and the distribution heads  52 ,  54 ,  60 , and  62  secured to the underground storage tank  34 . Exemplary fitting collars are sold by ENVIRON and are illustrated in the concurrently submitted catalog. The pipes and the submersible turbine pumps  48 ,  50  are connected (block  158 ). The seals and seams of the underground storage tank  34  are verified for integrity and then the underground storage tank  34  may be buried in the ground (block  160 ).  
         [0044]    It should be appreciated that manufacturing concerns and limitations may necessitate the rearrangement of the order of the steps of FIG. 8. Specifically, it is possible that the pipes and the interior wall  44  may be created and connected to the submersible turbine pumps  48 ,  50  and the walls of the underground storage tank  34  built therearound. Alternatively, a cylinder may be created for the underground storage tank  34 , all of the interior work done, and then end caps associated with the cylinder may be created to complete the underground storage tank  34 . Other fabrication techniques may also be used. Note further that the underground storage tank  34  may be constructed to differing degrees of completion. Thus, in some fabricating techniques, the fitting collars and riser pipes may not be attached during fabrication. In still other embodiments, the submersible turbine pumps  48 ,  50  may not be preprovided inside the underground storage tank  34 . Thus, those of ordinary skill in the art can appreciate that various levels of completion are possible and may provide pricing variations for consumers or other advantages.  
         [0045]    [0045]FIG. 9 illustrates an exemplary embodiment of a method of installing an underground storage tank  34  according to the present invention. Initially, the land is prepared (block  200 ). This preparation usually entails excavating a section of earth to generate a cavity within the ground. This cavity is sealed (block  202 ). Sealing may be done with a concrete barrier, a liquid barrier, or the like as needed or desired. The underground storage tank  34  is then placed in the ground, and namely in the cavity, beneath the intended surface of the forecourt of the fueling environment  10  (block  204 ).  
         [0046]    Fill material such as gravel, dirt, sand, or the like may be placed in the cavity (block  206 ). Before covering the top of the underground storage tank  34 , the piping may be positioned in the underground storage tank  34  (block  208 ) and secured to the submersible turbine pumps  48 ,  50  in each chamber  40 ,  42  of the underground storage tank  34  (block  210 ).  
         [0047]    The distribution heads  52 ,  54 ,  60 ,  62  are attached via fitting collars or other technique to the underground storage tank  34  (block  212 ). The riser pipes  68 ,  70 ,  72 ,  74  are attached to the distribution heads  52 ,  54 ,  60 ,  62 , with the terminal ends thereof extending above the intended surface of the forecourt of the fueling environment  10  (block  214 ). Any sumps  78 ,  80  that are required may be associated with the underground storage tank  34  as needed or desired.  
         [0048]    In many instances, a plurality of underground storage tanks  34  will be positioned in the fueling environment  10 . Once every underground storage tank  34  is fully in place with all the proper leak detection equipment, fluid level sensors, communication links and the like, the forecourt may be created (block  216 ). This may entail pouring a concrete slab while leaving man hole apertures for access to sumps and the like as is well understood.  
         [0049]    The fuel dispensers  32  are positioned above the underground storage tanks  34  (block  218 ) and the fuel dispensers  32  are attached to the riser pipes  68 ,  70 ,  72 ,  74  as is well understood (block  220 ).  
         [0050]    Note that in some instances, it is possible that the piping, submersible turbine pumps  48 ,  50 , collar fitting, distribution heads  52 ,  54 ,  60 ,  62  and riser pipes  68 ,  70 ,  72 ,  74  may be prefabricated and incorporated into the underground storage tank  34 . In such an instance, the underground storage tank  34  is placed in the cavity, the fill material used, the sumps positioned, the forecourt created over the tank, and the fuel dispensers  32  attached to the riser pipes  68 ,  70 ,  72 ,  74 . Variations in the level of completeness of the underground storage tank  34  are contemplated and within the scope of those of ordinary skill in the art to understand how to complete the installation. Likewise, those of ordinary skill in the art may note other ways of installing the components to achieve the present invention.  
         [0051]    Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present invention. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.