Abstract:
A zero ground disturbance dike apparatus and method for the secondary containment of harmful chemicals that are stored in primary storage vessels, wherein the dike apparatus does not require the drilling of postholes or the setting of support posts in concrete. Sections of dike walls are attached to bracing assemblies, each bracing assembly being comprised of a brace and a base plate. Braces are configured to support the assembled wall sections and to provide resistance against the outwardly force exerted by material that is released from the primary storage vessel. Base plates attached to the braces assist in resisting bending moments that may be created about the base of the dike apparatus. The brace assembly also preferably includes at least one base support channel for additional base plate stiffness and support cables to further resist the outwardly forces exerted against the dike apparatus by said released materials.

Description:
RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Application No. 60/430,589, filed Dec. 2, 2002, which is incorporated herein by reference in its entirety. 

   BACKGROUND OF THE INVENTION 
   The present invention pertains to the secondary containment of stored chemicals that are harmful to both the environment and living creatures. More particularly, the present invention relates to a zero ground disturbance dike apparatus for the secondary containment of stored harmful materials that does not require the drilling of postholes or the setting of support posts in concrete. 
   The storage of hazardous materials, such as petroleum contaminated process-water, industrial chemicals, liquid agricultural chemicals, and other corrosive chemicals in storage tanks are well known. Such tanks are designed and fabricated to prevent the uncontrolled release of these and other hazardous materials into the environment so as to reduce the risks associated with the pollution of the surrounding area and/or potential contamination of nearby ground water. 
   However, storage tanks have been known to occasionally accidentally leak or spill the entrapped hazardous material. In an attempt to minimize the potential harmful effects of such a leakage or spill, containment systems are often designed to incorporate both a primary storage containment vessel, such as a storage tank, and a secondary containment system. One form of secondary containment system that is often used with above ground containment systems is a dike apparatus. 
   In the past, dike apparatuses have been constructed from a variety of materials. Most dike apparatuses have been fabricated from earth, wood, and concrete. These apparatuses are often virtually permanent in both size and location. However, the construction of dike apparatuses from such materials, and their intended permanency, typically makes any attempt to subsequently expand these apparatus both labor intensive and expensive. Furthermore, when removed or vacated, such apparatuses often leave an indelible mark on the surrounding surface. 
   Dike apparatuses fabricated from metal are also well known in the art. These systems are often pre-fabricated before being transported to storage facilities for on-site assembly. The metallic walls of such apparatuses are typically bolted to support posts, with the support posts being secured into the surrounding ground. However, the metallic surfaces of these systems often prevent such dikes from being used in conjunction with the storage of materials that are highly reactive to metals, such as liquid fertilizers. Furthermore, the reliance on support posts that are secured-beneath the surrounding ground subjects these systems to damage related to frost heavage. Differential frost heavage typically results in the displacement of the support posts, and their attached wall sections, thus pulling the wall sections away from one another, and thereby potentially compromising the dike&#39;s seal of containment. The need to fix this reoccurring separation between the wall sections so as to maintain the integrity of the dike apparatus typically makes these systems costly to maintain. 
   U.S. Pat. No. 5,882,142 (“&#39;142”) discloses a metal dike system that is designed to prevent damage due to frost heavage. The apparatus disclosed in U.S. Pat. No. &#39;142 includes a plurality of wall sections that are attached to support posts, the support posts being secured in concrete that is located below the frost line. The support posts, which are preferably six to twelve feet long, include elongated apertures that receive the insertion of bolts that attach sections of the steel dike walls to the support posts. The elongation of the apertures is configured to permit the movement of the bolts along the apertures, thereby allowing the steel walls and support posts to move separately of each other in response to post displacement that is caused by differential frost heavage. Additionally, the steel walls are bolted to adjacent wall sections in an end-to-end arrangement so that, in instances of frost heavage, the movement of the posts will not affect the connection between the walls, and thereby prevent the dike seal from being compromised. 
   However, in order to secure support posts in concrete that is located below the frost line, as required by invention disclosed in U.S. Pat. No. &#39;142, postholes must be drilled into the surrounding ground. In order to extend below the frost line, these postholes often have to be drilled up to depths of eight feet. Drilling to such depths can be both expensive and labor intensive, particularly in light of the fact that site conditions throughout the world vary greatly. For instance, in some areas, the presence of limestone or other rock strata makes drilling postholes very difficult and expensive. In other areas of the world, or during winter months, frozen ground increases the difficultly and expense of installation. Drilling to depths of up to eight feet also creates additional potential hazards, including the dangers associated with the drill hitting underground gas lines, electrical lines, and/or pipes. Furthermore, in some countries, such as Canada, local regulations prohibit ground penetrations of more than twelve inches on public lands. Additionally, because such storage facilities are often located in remote areas, transporting cement to set the support posts in the postholes, as required by the &#39;142 patent, is expensive. 
   It is therefore an object of the present invention to provide an apparatus for the secondary containment of hazardous materials that may be accidentally released from a primary storage vessel. 
   It is a further object of the present invention to provide a zero ground disturbance system for the secondary containment of hazardous materials. 
   It is another object of the present invention to provide a secondary containment system that does not require the drilling of postholes for support posts. 
   A further object of the present invention is to provide a secondary containment system to control the accidental leakage or spillage of hazardous materials from a primary containment system that does not require the setting of support posts in concrete. 
   It is also on object of the present invention to provide a secondary containment system that complies with local regulations regarding limitations on ground penetration. 
   These and other desirable characteristics of the present invention will become apparent in view of the present specification, including the claims and drawings. 
   BRIEF SUMMARY OF THE INVENTION 
   The present invention is directed towards a method and apparatus for the secondary containment of hazardous materials. Specifically, the present invention relates to a zero ground disturbance dike apparatus for the secondary containment of harmful materials that are stored in a primary storage vessel, wherein the dike apparatus does not require the drilling of postholes or the setting of support posts in concrete. 
   The dike apparatus of the illustrated embodiment is comprised of wall sections that are operably attached to brace assemblies. Each wall section preferably boltingly engages an adjacent wall section in an overlapping end-to-end arrangement, the attachment of the wall sections being oriented to form a dike apparatus inner chamber, the region encapsulated within the inner chamber preferably extending down to at least to the adjacent ground. A seal between each wall section is also preferably created by the placement of a seam sealant to the outer edge of each vertical seam that is formed by said overlapping engagement of the wall sections. 
   Each brace assembly is preferably comprised of a brace and a base plate. In the illustrated embodiment, the braces preferably have a body portion, a stiffening plate, an upper flange, and a lower flange. The braces are configured to provide vertical support to the walls and, in the event that materials are leaked or spilled from the primary storage vessel, assist in withstanding the resulting outwardly forces that may be exerted on said walls by the released materials while also maintaining minimal wall deflection. The braces are also preferably attached to a wall section or sections via the bolting of the upper flange to the adjacent wall section(s). 
   The base plate is configured to resist the bending moment that is created at the base of the dike apparatus when materials released from the primary storage vessel exert an outwardly force against the attached wall sections. The base plates in the illustrated embodiment are comprised of an upper surface, a bottom surface, a proximate end, a distal end, and side extensions, and are preferably generally rectangular in shape. At least a portion of the upper surface preferably boltingly engages the lower flange of the brace, thereby securing the brace to the base plate. 
   In the illustrated embodiment, the base plate is positioned so that a substantial portion of the proximate end extends within the region defined by the inner chamber, as illustrated in  FIGS. 3 ,  4 ,  7 ,  8 , and  9 . This configuration allows the base plate to use the weight of both the released materials from the primary storage vessel and the components of the containment system that are located above that portion of the base plate that is within the inner chamber to resist the bending moment created at the base of the dike apparatus, thereby preventing the base plate and attached brace and walls from tipping over in a generally outwardly direction. 
   The side extensions are configured to provide traction for the base plate. When subjected to the weight of said released materials and the dike apparatus, the lower portion of the side extensions aid in gripping the surrounding ground so as to resist any lateral movement caused by the outwardly forces that are exerted by the spilled or leaked material against the walls of the dike apparatus. 
   The illustrated embodiment of the present invention also preferably includes at least one base support channel that is operably connected to the base plate. The base support channel is configured to provide additional stiffness to the base plate so as to provide additional resistance against any bending moment that may be created at the base of the dike apparatus. In an attempt to not compromise the stability of the brace assembly, the base support channel is preferably recessed into the base plate, whereby the base support channel attaches to the bottom surface of the base plate and does not extend beyond the lower portion of the side extensions or the proximate or distal ends of said base plate. Alternatively, the base plate channel may be constructed to provide sufficient stiffniess so as to eliminate the need for a brace support channel. 
   To further prevent the lateral movement of the walls when the walls of the dike apparatus are subjected to the outwardly forces created by the release of material from primary storage vessel, the dike apparatus of the present invention also preferably includes at least one support cable. The support cable preferably has a first end and a second end, the first end being secured to a first brace assembly and the second end being secured to a second brace assembly, the first and second brace assemblies preferably being located across from one another on opposing walls. When secured to the brace assemblies, the support cable extending across the inner chamber is preferably maintained in a taut condition so as to assist in resisting any outwardly forces that may be exerted against said walls and the brace assemblies. 

   
     BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
     For a more complete understanding of this invention reference should now be had to the embodiment illustrated in greater detail in the accompanying drawings and described below by way of example of the invention. 
       FIG. 1  is an exploded view of a containment system that employs a dike apparatus in accordance with the illustrated embodiment of the present invention. 
       FIG. 2  is an exploded view of two adjacent wall sections in accordance with the illustrated embodiment of the present invention. 
       FIG. 3  is an exploded view of a brace assembly in accordance with the illustrated embodiment of the present invention. 
       FIG. 4  is a perspective view of the brace assembly in accordance with the illustrated embodiment of the present invention. 
       FIG. 5  is a rear elevated view of the brace assembly in accordance with the illustrated embodiment of the present invention. 
       FIG. 6  is a top view of the brace assembly in accordance with the illustrated embodiment of the present invention. 
       FIG. 7  is an elevated side view of the brace assembly in accordance with the illustrated embodiment of the present invention. 
       FIG. 8  is a top view of a portion of a rectangular dike apparatus in accordance with an illustrated embodiment of the present invention. 
       FIG. 9  is a top view of a portion of an oblong dike apparatus in accordance with an illustrated embodiment of the present invention. 
       FIG. 10  illustrates an exploded view of a corner bracket for a dike apparatus in accordance with one embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  illustrates a containment system  10  in accordance with the illustrated embodiment of the present invention. The containment system  10  is comprised of a primary storage vessel  12 , such as a storage tank, that is configured to hold hazardous materials, and a secondary containment system in the form of a dike apparatus  14 . The dike apparatus  14  is comprised of a plurality of brace assemblies  34  set upon the ground  16 . The plurality of brace assemblies  34  provide support to a plurality of wall sections  32 , at least a portion of the plurality of wall sections  32  preferably being bolted to at least a portion of an adjacent brace assembly  34 . The wall sections  32  and attached brace assemblies  34  are arranged to create an enclosed inner chamber  36 , as illustrated in  FIGS. 1 ,  8 , and  9 . The region encapsulated within the inner chamber  36  extends down to at least the enclosed ground  16 . The plurality of brace assemblies  34  are also preferably positioned along the plurality of wall sections  32  so as to equally distributed the forces that are, or, in the event of a spill or leak, may be asserted against the wall sections  32 . 
   The dike apparatus  14  also includes a dike base cover  28 . The dike base cover  28  in the illustrated embodiment of the present invention is a layer of sand that is preferably approximately two inches deep. Ground  16  conditions beneath the dike base cover  28  are preferably stable and suitable for the fluid loads that are placed upon the walls of the primary storage vessel  12  and those that may be placed upon the wall sections  32  of the dike apparatus  14  in the event of the leakage or spilling of said hazardous materials. Furthermore, the ground  16  under and around the containment system  10  is also preferably undisturbed or re-compacted and sufficiently level. The ground  16  adjacent to the containment system  10  also preferably provides sufficient drainage to prevent soil erosion around the containment system  10 . 
   Above the dike base cover  28  is a pad  26 , the pad  26  being preferably made from at least eight-ounce geotextile fabric. The pad  26  is configured to enwrap a liner  24 , and, along with the liner  24 , is inserted into at least a portion of the inner chamber  36 . The liner  24  is constructed of material that prevents the passage therethrough of said leaked or spilled materials from the primary storage vessel  12 . 
   The liner  24  and pad  26  are both preferably attached to at least a portion of the wall sections  32 . In the illustrated embodiment, the liner  24  and pad  26  are secured to the top portion of the plurality of wall sections  32  through the use of clamps  40  and corner clamp assemblies  42 . Furthermore, in the illustrated embodiment, the upper edge of the wall sections  32  are flanged so as to provide a surface upon which the liner  24  and pad  26  are pulled over and to which the clamps  40 ,  42  may secure the liner  24  and pad  26  to the wall  32 . The clamps  40  preferably have a V-shape, the V-shape having upper and lower legs. In such an arrangement, at least a portion of the top of the liner  24  and pad  26  are placed between the flanged upper portion of the wall  32  and the inner surface the upper leg of the V-shaped clamp  40 . The inner portion of the lower leg of the V-shaped clamp  40  is positioned against at least a portion of the bottom of the flanged upper portion of the wall  32 . Bolts and/or screws are inserted through the clamps  40 , liner  24 , pad  26 , and upper flanged portion of the wall sections  32  so as to tighten the compressing force of the clamps  40  on the liner  24 , pad  26 , and flanged portion of the wall  32 . The clamps are preferably elongated to decrease the ability of the liner  24  and pad  26  to pull away from the inserted bolts and/or screws. 
   Corner clamp assemblies  42  for rectangular or square shaped dike apparatuses  14  are preferably comprised of upper and lower brackets  46 ,  47  and a corner clamp  48  that joins intersecting wall sections  32   c ,  32   d , as illustrated in FIG.  10 . In operation, the upper bracket  46  is positioned against the liner  24 , while the lower bracket  47  is placed against the bottom of the flanged upper portion of the respective wall  32   c ,  32   d . Bolts and/or screws are inserted through the brackets  46 ,  47 , corner clamp  48 , liner  24 , pad  26 , and upper flanged portion of the wall  32  to create the desired clamping force. 
   A second pad  22  is placed along at least a portion of the base of the liner  24 . This second pad  22  is preferably constructed from eight-ounce geotextile fabric, but may also be an approximately two inch deep layer of sand. Above the second pad  22 , and within the inner boundaries of the liner  24 , is a layer of pea gravel  20  that is configured to support the primary storage vessel  12 . In the illustrated embodiment, the layer of pea gravel  20  is approximately six inches deep. To further assist in containing any leakage or spill from the primary storage vessel  12 , a gravel ring  18  is preferably positioned on top of the layer of pea gravel  20  and around the base of the primary storage vessel  12 . 
     FIG. 2  illustrates the attachment of two adjacent sections of dike wall sections  32   a ,  32   b  in accordance with the illustrated embodiment of the present invention. In the illustrated embodiment, the first and second vertical ends  58 ,  59  of the wall sections  32   a ,  32   b  are generally parallel to one another while the horizontal edges  78 ,  79  are generally parallel to each other. As shown, the adjacent wall sections  32   a ,  32   b  that form each individual wall of the inner chamber  36  of the dike apparatus  14  are arranged in an overlapping end-to-end configuration and are attached to each other through the use of bolts  31  and nuts  33 . A seal between each wall is also created by the placement of a seam sealant  44  to the outer edge  43  of each vertical seam. In the illustrated embodiment, each section of wall  32   a ,  32   b  is preferably fabricated from, but not limited to,  10 ,  12 ,  14 , or  15  gauge high strength galvanized corrugated sheet steel that is around 25 to 57 inches high and 56 to 112.5 inches in length. Furthermore, each section of wall  32   a ,  32   b  may be formed to create a variety of dike apparatus  14  configurations, including round, oblong, or rectangular, as exemplified in  FIGS. 1 ,  8 , and  9 . Note that although the curved wall portion illustrated in  FIG. 9  is shown without any attached brace assemblies  34 , in the illustrated embodiment such assemblies  34  are installed if the curve exceeds 78 feet. 
     FIGS. 3 ,  4 ,  5 ,  6 , and  7  illustrate the brace assembly  34  in accordance with the illustrated embodiment of the present invention. Brace assemblies  34  are preferably positioned along the dike apparatus  14  in a manner so as to equally distribute any outward forces that may be exerted against the inner chamber  36  of the wall sections  32 . The brace assembly  34  is comprised of a brace  52  that is operably mounted to a base plate  50 . The base plate  50  in the illustrated embodiment includes an upper surface  90 , a bottom surface  91 , side extensions  92 , a distal end  86 , and a proximate end  88 . In the illustrated embodiment, the brace  52  includes a body portion  51 , lower flanges  80   a ,  80   b , an upper flange  82 , and a stiffening plate  84 . The lower flanges  80   a ,  80   b  preferably rest upon the distal end  86  of the upper surface  90  of the base plate  50  and have at least one perforation that mates perforations in the base plate  50 . These perforations are configured to permit the brace  52  to be bolted to the base plate  50  via at least one bolt  64 , washer  65 , and nut  66 . 
   Each brace  52  is configured to provide vertical support to the wall sections  32 . Furthermore, in the event of a leakage or the spilling of material from the primary storage vessel  12 , the outwardly force exerted by the released materials against the inner chamber  36  portion of the wall sections  32  is transferred by the wall sections  32  to the braces  52 . The braces  52  are configured to withstand such outwardly forces and to maintain minimal deflection in the wall sections  32 . In the illustrated embodiment, the brace  52  includes a body portion  51  and stiffening plate  84  that are configured to assist the brace  52  in overcoming any outwardly forces that are exerted against the wall sections  32 . The body portion  51  preferably has a generally triangular configuration. However, the body portion  51  can take on a number of different geometrical configurations, as would be appreciated by one skilled in the art. Attachment between the brace  52  and wall  32  may be achieved through the insertion of at least one bolt  74  into mating apertures in the upper flange  82  of the brace  52  and wall  32 , the bolting engagement also preferably including a washer  75  and mating nut  76 . Furthermore, each bolt head protruding inwardly from any wall  32  that may have contact with the liner  24  is preferably covered with tape so as to prevent the accidental tearing of the liner  24 . 
   In instances where hazardous materials escape from the primary storage vessel  12 , the outwardly force of the released material against the wall sections  32  creates a bending moment at the base of the dike apparatus  14 . This moment is overcome via the base plate  50 . The base plate  50  is preferably configured so that a substantial portion of the proximate end  88  of the base plate  50  is located within the region of the inner chamber  36  of the dike apparatus  14 . Such a configuration utilizes the weight, and associated downward force, of released materials and containment system  10  components that are located above the portion of the base plate  50  that is positioned within the inner chamber  36  to resist said bending moment in order to prevent the brace assembly  34  and attached wall sections  32  from tipping outwardly, thereby supporting the wall sections  32  and maintaining the integrity of the dike apparatus  14 . 
   The base plate  50  may also include side extensions  92  that are configured to provide the base plate  50  with traction against the adjacent ground  16 . When the base plate  50  is subjected to lateral forces created by outwardly pressure that is exerted against the inner chamber  36  portion of the wall sections  32 , the weight exerted down upon the base plate  50  is used by the lower portion  93  of the side extensions  92  to grip the ground  16 , thereby providing traction to resist the lateral movement of said brace assemblies  34  and attached wall sections  32 . 
   As shown in  FIG. 3 , the brace assembly  34  also preferably includes at least one base support channel  54   a . In the illustrated embodiment, each base plate  50  is preferably attached to two base support channels  54   a ,  54   b . Base support channels  54   a ,  54   b  are configured to provide additional stiffniess to the base plate  50  and to provide additional assistance in resisting the bending moment that may be exerted against the base of the dike apparatus  14 . Each base support channel  54   a ,  54   b  preferably has a plurality of perforations configured and aligned to mate with a plurality of perforations in the base plate  50  so as to permit a bolting engagement between said base support channels  54   a ,  54   b  and the base plate  50 . Each base support channel  54   a ,  54   b  further includes a plurality of perforations that are configured for the bolting engagement between said adjacent base support channels  54   a ,  54   b , the bolting engagement including at least one bolt  64 , a flat washer  65  on each side of the channel  54   a ,  54   b , and a mating nut  66 . 
   For stability purposes, in the illustrated embodiment, the support base channels  54   a ,  54   b  are preferably configured to be recessed into the base plate  50  and do not extend beyond the lower portion  93  of the side extensions  92  or the distal or proximate ends  86 ,  88 . Such a configuration is intended to prevent the potential tipping of the dike apparatus  14 , or its components, that may arise when uneven load distributions are transmitted to the brace assembly  34 . 
   The incorporation of base support channels  54   a ,  54   b  in the illustrated embodiment of the present invention, and the associated stiffening created through their use, permits the base plate  50  to be fabricated from thinner material and thus have a lighter configuration than would be required in an embodiment that did not include the base support channels  54   a ,  54   b . Decreasing material thickness not only reduces the material cost of the base plate  50 , but also labor expenses associated with the handling, transportation, and installation of lighter materials are also typically reduced. However, in an alternative embodiment, the base plate  50  is configured to provide sufficient stiffness so as to eliminate the need for brace support channels  54   a ,  54   b.    
   As an additional measure to prevent the outwardly tipping of the wall sections  32  and the brace assembly  34  when released materials from the primary storage vessel  12  exert pressure against the wall sections  32 , and to resist any lateral movement of the brace assemblies  34  and attached wall sections  32 , the brace assembly  34  in the illustrated embodiment may also incorporate at least one support cable  56 , as illustrated in  FIGS. 3 ,  4 ,  6 ,  7 ,  8 , and  9 . Support cables  56  are preferably constructed from galvanized steel and are attached to the base support channels  54   a ,  54   b  of each brace assembly  34  via at least one cable clamp  62 . The support cable  56 , which preferably has an loop at both a first end and a second end, is wrapped around a bolt, the bolt being secured to an assembled base channel  54   a ,  54   b . However, in an alternative embodiment, the support cable  56  may be operably attached to the base plate  50  rather than the base support channels  54   a ,  54   b.    
   As illustrated in  FIGS. 8 and 9 , the support cable  56  preferably is secured to, via a first brace clamp  62 , and extends from, a first brace assembly  34   a  that is attached to a first wall  32   a , and reaches across the inner chamber  36  to a second brace assembly  34   b  located at the opposing second wall  32   b , whereupon the support cable  56  is preferably secured by a second cable clamp  62 . Any slack in the support cable  56  extending across the inner chamber  36  is preferably removed so that when the support cable  56  is secured to the first and second brace assemblies  34   a ,  34   b , the support cable  56  is taut. Tautness in the support cable  56  assists in the ability of the brace assemblies  34   a ,  34   b  to resist any outwardly forces that may be exerted against the walls  34   a ,  34   b  so as to prevent the walls from tipping or sliding outwardly. 
   While the invention has been described in connection with one or more embodiments, it will be understood that the invention is not limited to those embodiments. On the contrary, the invention includes all alternatives, modifications, and equivalents as may be included within the spirit and scope of the appended claims.