Patent Application
20130087558
The present invention relates to an above-ground containment structure, and in particular a portable storage tank suitable for containing fluid or other solid or granular material.
Various industries and processes require a portable or movable storage tank or basin for storing product, both fluid and granular, on a temporary basis and in a cost effective manner. Several storage systems are known in the art. One conventional system includes a below-ground basin lined with a polymer material for retaining fluid. However, such basins or ponds are relatively expensive to form, requiring extensive excavation, and are prone to leakage and thus ground water and soil contamination. Other fluid retaining systems provide for a relatively large steel tank, which may be positioned below or above-ground. Such tanks are unwieldy and bulky, prone to rusting, and have not proven viable for relatively large volumes of fluid.
Another fluid retaining system includes an above-ground fluid retaining tank including a network of steel or concrete supports or walls. While such above-ground systems do not require extensive below-ground excavation, they are bulky and extremely heavy given the weight of the steel or concrete supports must counteract the outward forces generated by the weight of the fluid being retained. As such, the cost of transporting and installing the materials needed for such systems is relatively high given the total weight of the steel and concrete supports and walls. Likewise, the cost of dismantling and removing the steel and concrete supports and walls is likewise excessive. Thus, such conventional retaining systems are not truly portable, given the cost to assemble, and dissemble and remove such systems is excessive.
Such conventional fluid retaining systems are nevertheless needed and therefore used in a variety of industries and applications. One such industry that requires a readily available source of fluid is the natural gas and mining industry. Shale gas production has grown rapidly in the United States and elsewhere due in part to improved drilling and extraction methods. One extraction method is hydraulic fracturing, which involves the propagation of fractures in a rock layer caused by the presence of a pressurized fluid. Hydraulic fracturing is used to increase the rate at which fluids, such as natural gas or oil, can be extracted from rock layers or reservoirs.
Hydraulic fractures form naturally, such as in veins or dikes, and are one means by which gas and petroleum from source rock may migrate to reservoir rock formations. This fracturing process may be accelerated by injecting highly pressurized fracking fluid into a wellbore drilled into reservoir rock formations. The energy from the injection of the fracking fluid creates new channels in the rock, thereby increasing the extraction rates and ultimate recovery of the natural gas or other fuels. Thus, the created fractures provide a conductive path connecting a larger area of the reservoir to the well, thereby increasing the area from which natural gas or oil may be recovered from the targeted formation.
A hydraulic fracture is formed by pumping the fracking fluid into the wellbore at a rate sufficient to increase pressure downhole to exceed that of the fracture gradient of the rock. The rock is thereby cracked and the fracture fluid forced farther into the rock, thereby extending the crack. In order to prevent the formed fractures from closing when the injection process is stopped, a solid proppant (e.g., grains of sand or ceramic) is typically added to the fluid. The fracture is thus permeable enough to allow the flow of formation fluids (e.g, natural gas or oil) to the well.
In addition to proppants, the fracking fluid may also contain chemical additives, gels, foams, and compressed gases. However, water is the largest component of fracking fluid, typically accounting for approximately 98% of fracking fluids. Low-volume hydraulic fracturing used to stimulate high-permeability reservoirs may consume typically 20,000 to 80,000 gallons of fluid per well, while high-volume hydraulic fracturing, such as used in shale gas wells, may use two to three million gallons or more of fluid per well. Thus, fracturing operations require a relatively large and readily available source of water, such as from a fluid retaining basin or conventional tank.
The gas, oil or other substance is extracted from the wellbore along with wastewater, which may include the water and/or other components of the fracking fluid along with other naturally occurring elements such as salt, metals and other elements. Retaining basins or tanks are therefore also needed for containing the wastewater until it can be further processed or hauled away for treatment and/or disposal.
Conventional storage tanks and systems fail to provide an adequate solution for temporarily retaining large volumes of fluid, such as needed in the natural gas and oil industry. Such conventional tanks and systems are not easily assembled, dissembled or moved, and thus are not cost effective.
Accordingly, there is a need for a storage system that is relatively easy to assemble and disassemble, and which provides for the storage of fluids and granular materials on a temporary basis and in a cost effective and efficient manner. In particular, there is a need for a portable, above-ground retaining structure that can accommodate relatively large volumes of material, including fluid or granular materials, such as one million or more gallons of such material. The present invention solves some or all of the above-noted deficiencies of conventional retaining systems.
The present invention is directed to an above ground, portable storage tank system or containment structure that may be be utilized for various applications for containing or retaining fluids and granular materials.
An above-ground containment system according to an embodiment of the present invention includes a plurality of truss assemblies, one or more retaining bands, and a liner. Each the truss assemblies includes a first portion and an opposite second portion. The first portions of the truss assemblies are disposed in an arrangement defining a periphery of a storage area. Preferably, the storage area has a substantially circular or elliptical configuration in plan view. The second portions of the truss assemblies are disposed outwardly from the storage area. The band(s) is coupled to the second portions of the truss assemblies and encircles the storage area. The band tensionably maintains the plurality of tress assemblies in the arrangement. The liner has a peripheral portion coupled to the first portions of the truss assemblies and a central portion covering a base of the storage area.
In one embodiment, the containment system is capable of retaining at least about 50,000 thousand gallons of material in the storage area. More preferably, the system is capable of retaining at least about 2 million gallons of material is the storage area. In one implementation, the system is capable of retaining at least about 3 million gallons of material in the storage area.
In one embodiment, the band is high strength wire strand. The containment system may include a single retaining band, or alternatively two or more retaining bands that are coupled to the outer portions and encircle the storage area.
In one embodiment, the first portions of the truss assemblies include a planar panel portion angled outwardly and away from the base of the storage area. The second portions may include a plurality of support beams disposed substantially perpendicular to the base of the storage area.
In one embodiment, each of the second portions of the truss assemblies comprises a load transfer plate. The load transfer plates of the arranged truss assemblies collectively form a load transfer ring encircling the storage area. The band(s) is coupled to the load transfer ring.
In one embodiment the containment system includes a leakage monitoring system. In one implementation, the leakage monitoring system includes a perforated pipe extending across a portion of the base of the storage area, and a monitoring pipe. The liner covers the perforated pipe and monitoring pipe. The monitoring pipe includes a lower end coupled to the perforated pipe and an upper end disposed out of the storage area and accessible by a user.
The present invention is also directed to a truss assembly for a storage structure. The truss assembly includes a planar panel portion disposed in an arrangement with a plurality of additional truss assemblies to define a periphery of a storage area. A truss portion includes a first portion coupled to the planar panel portion and an opposite second portion. A load transfer plate is coupled to the second portion of the truss portion, and includes a retaining member configured to secure a tensioning band thereto. The load transfer plates of the truss assemblies disposed in the arrangement form a load transfer ring configured to receive the tensioning band.
In one embodiment, the truss assembly includes a puncture resistant liner coupled to the planar panel portion. The liner may be formed from a linear low-density polyethylene. In some embodiments, the truss assembly additionally includes a backing layer intermediate the liner and the planar panel portion. The truss assembly components may be formed from various materials, including but not limited to wood, wood composite, plastic, or metal.
The present invention also relates to a method of erecting an above-ground storage structure. The method includes the steps of: providing a plurality of truss assemblies, each of the truss assemblies including a first portion including a planar panel and an opposite second portion including a load transfer plate; positioning the plurality of truss assemblies so that the planer panels of the first portions of the truss assemblies define a periphery of a storage area, and the load transfer plates form a load transfer ring; coupling a band to the load transfer ring so that the band is surrounding the truss assemblies and the storage area; applying tension to the band so that the planar panels of the truss assemblies are aligned along the periphery of the storage area; and coupling a peripheral portion of a liner to the planar panels of the truss assemblies so that the liner is covering a base of the storage area. In preferred embodiments, the plurality of truss assemblies is positioned in one of a substantially circular or a substantially elliptical configuration in plan view.
The present invention is directed to an above ground storage tank system or containment structure that may be be utilized in various industries and applications for the containment of materials, including both fluids and granular materials. The disclosed storage system is relatively portable or movable, and may be quickly and easily erected at a particular site, with little to no site preparation required. Once the need for storage at the particular site is met, the disclosed system may be easily disassembled and/or relocated to another site. The environmental impact at the site is therefore minimal. The disclosed system includes a plurality of truss assemblies or segments, which are coupled together and maintained in position via a retaining band or wire. Compared to conventional storage tanks and systems, and in particular non-movable or bulky conventional concrete storage systems, the system of the present invention provides the user with the flexibility to assemble and/or disassemble a storage structure quickly and easily, and for a fraction of the cost compared to other conventional systems.
Referring to
Referring again to
Referring again to
In a preferred embodiment, components of the truss assemblies 12 are formed from wood or engineered wood products. In other embodiments, components of the truss assemblies 12 may be constructed from other materials such as a polymer and polymer composites (e.g., a reinforced polymer composite), light gauge steel, cold formed steel, hot rolled steel, or another material having sufficient structural properties. Preferably, the truss assemblies 12 are relatively light weight and/or easily assembled or disassembled to facilitate ease of transport and positioning thereof. In one embodiment, the planar panels 26 are constructed of engineered wood sheeting; alternatively, the planar panels 26 are constructed of light gauge steel sheeting, or a polymer or polymer composite material.
The band(s) 18 is coupled to the second portions 24 of the truss assemblies 12, and encircles the arranged truss assemblies 12 and thus the storage area 16. The band(s) 18 tensionably maintains the truss assemblies 12 in the selected arrangement (e.g., such as arrangement A1). In one embodiment, each band 18 is a high strength steel tension band, such as utilized for pre-stressing and post tensioning precast concrete. In a preferred embodiment, the band is high strength 5 wire or 7 wire strand. For example, the band 18 may exhibit a tensile strength of 270,000 pounds per square inch or more.
As noted above, the containment system 10 may include more than one band 18, depending on the support required to resist the outwardly directed forces (shown by arrow F1 in
Referring to
Referring to
In one implementation, the backing layer 44 is formed from a flexible, permeable, non-woven material, such as a geotextile fabric. The geotextile backing material may be constructed of woven or non-woven material of various thicknesses, such as typically used in the earth moving and construction industries. The backing layer 44 may alternatively be constructed from another suitable material that provides adequate cushioning, adequate puncture protection, and adequate permeability and gas venting properties to protect the liner 20.
The liner system utilized may be constructed of a single layer or multiple layers of a scrim reinforced LLDPE or other similar material, such as typically used for landfill liners, pond liners, in-ground earthen impoundments, or the like. However, the liner system may alternatively be constructed of another suitable material capable of retaining fluid or granular material, providing adequate resistance to chemical degradation from the material being stored, and providing adequate puncture and ultra-violet resistance. The actual number of liner layers utilized is dependent on the material being stored, as well as on any storage regulations on such stored material.
With continued reference to
It should be understood that the specific dimensions and number of support beams 46, planar panels 26 and other components of the first portion 22, and/or braces 48 may vary depending on the structural capabilities necessary and required for a particular application. Thus, the specific configuration of the truss assemblies 12 may vary depending on the particular application and in order to provide adequate structural loading for the particular application.
One of more load transfer plates 50 are coupled to and extend between the support beams 46 of the second portion 24 of each truss assembly 12. The load transfer plate(s) 50 is preferably formed from wood or engineering wood products, but may alternatively be formed from another material such as plastic, light gauge steel, composite materials, or some other material having adequate structural properties. Preferably, the load transfer plate 50 is formed from a relatively light weight material which permits a sufficient amount of flexure or curvature to account for the curved configuration of the outer portion of the truss assembly, as best shown in
In one embodiment, the load transfer plate(s) 50 is connected to and extends across the support beams 46. Preferably, each truss assembly 12 includes at least an upper load transfer plate 50 proximate to a top portion 52 of the truss assembly 12, and a lower load transfer plate 50 proximate to a bottom portion 54 of the truss assembly 12. One or more intermediate load transfer plates 50 may be provided intermediate the upper and lower load transfer plates 50, as shown in
As best shown in
The various loops of the bands 18 provide the necessary support required to resist the outwardly directed forces F1 or hoop stress generated by the fluid or granular material being contained in the storage area 16. Once the bands 18 are installed and an initial stress is imparted to each of the bands 18, the backing layer 44 may be draped over the top panel 30 and outer faces 28 of the planar panels 26 of the truss assemblies 12. The liner 20 is then placed within the storage area 16, and unrolled or positioned therein so that the entire base 40 of the storage area 16 is covered by the liner 20. The outer portion 36 of the liner 20 is coupled to and/or overlaps the backing layer 44, and thus is coupled to and/or overlaps the planar panels 26 and top panels 30 of the truss assemblies 12, such as shown in
In preferred embodiments, the storage area 16 has either a circular or elliptical configuration, as shown in
Preferably, the truss assemblies 12 are prefabricated off site, and then transported to the site as assembled and discrete segments to minimize on site construction time. The truss assemblies 12 may be placed directly on the ground or another suitable surface, which will ultimately serve as the base of the storage area 16. Preferably, the truss assemblies 12 are positioned on a relatively flat area. Alternatively or additionally, the ground G may be leveled or smoothed, with any larger rocks, brush or vegetation removed, in preparation for locating the containment system 10. A sand bedding S or other similar material suitable for quickly leveling the ground G may alternatively or additionally be utilized, as shown in
It should be understood that the sand bedding S or other level material, and/or other ground preparations required prior to assembly and installation of the system 10, are minimal compared to site preparation requirements for conventional storage systems. For example, the sand bedding S for system 10 may have a depth of only several inches, depending on the conditions of the surface of the ground G. By comparison, a conventional above-ground storage tank typically requires a sub-base including structural fill (e.g., stone) having a depth of 8 feet or more in order to support the high forces and weight of the resulting tank. Conventional above-ground tanks, when filled with fluid, transfer virtually all of the weight from the material being stored downwardly or vertically relative to the ground. For example, a conventional above-ground tank may easily transfer a downward or vertical force on the ground exceeding 6000 pounds per square foot. By contrast, the disclosed system 10 transfers a substantial portion of the force from the weight of the stored material outwardly or horizontally, transferring the horizontal forces F1 outwardly and to the load transfer rings 56 and bands 18, as described above. Thus, the system 10 results in a substantial decrease in the downward forces (e.g., system 10 may transfer a vertical force of only 600 pounds per square foot, or 1/10 the vertical forces exhibited by a conventional tank of comparable size and storage holding capabilities).
When the truss assemblies 12 are properly positioned relative to each other at the desired site location, such as in a circular arrangement A1, the load transfer plates 50 are aligned to form load transfer rings 56, as described above. The specific size of the truss assemblies 12 and overall system 10 may vary depending on the particular application. For example, the truss assemblies 12 may have a height of about 12 feet or more, with the storage area 16 having a diameter of about 200 feet or more. Larger or smaller storage areas may be provided as desired. Thus, the height and width of the truss assemblies 12 may vary depending on the desired size of the storage area 16. Moreover, the angle at which the planar panels 24 are disposed relative to the base 40 of the storage area 16 (and thus the resulting configuration of the truss assemblies 12) may also vary depending on the size and load requirements for the system 10.
According to one embodiment, the containment system 10 includes a leakage monitoring well or system. In one implementation, the monitoring system includes a section of perforated pipe 60 extending across the base 40 of the storage area 16. Referring to
The perforated pipe 60 is preferably angled downwardly within the channel C and along its longitudinal axis, so that an end 64 of the perforated pipe 60 is slightly lower than the opposing end 66 thereof. In this way, any fluid that collects or migrates into the perforated pipe 60 flows downwardly to the lower end 64. Referring to
The monitoring pipe 70 may be disposed between the backing layer 44 and the liner 20, as best shown in
Any fluid that collects in the perforated pipe 60 is channeled downwardly and flows toward end 64, and is then visible through the monitoring pipe 70. Alternatively or additionally, the user may readily lower an appropriate gauge, fluid detection equipment, or absorbent material into the monitoring pipe 70 to the end 64 of the perforated pipe 60. Any fluid present at the end 64 of the perforated pipe 60 is readily detected. Thus, a cost efficient leakage monitoring system may be easily provided for the containment system 10.
After the truss assemblies 12 are in positioned in the predetermined arrangement (e.g., arrangement A1), the high strength steel tension wires are positioned around the arranged truss assemblies, with opposing ends of the wires connected to form the bands 18. The bands 18 are coupled to the load transfer ring(s) 56, as described above, so that the bands 18 surround the truss assemblies 12 and the storage area 16. The bands 18 and load transfer ring(s) 56 are distributed over the exterior or second portions 24 of the truss assemblies 12, so that the outwardly directed forces F1 or hoop stresses imparted on the truss assemblies 12 by the weight of the fluid or material ultimately disposed within the storage area 16 may be resisted. Upon coupling the bands 18 to the load transfer rings 56, the bands 18 are initially minimally pre-tensioned or pre-stressed in order to seat and further align the planar panels 26 of the truss assemblies 12 in their desired arrangement. As the bands 18 are further tensioned and tightened around the load transfer rings 56, the truss assemblies 12 are drawn into relatively tight engagement with each other.
Once the truss assemblies 12 are fully seated via the pre-tensioned bands 18, the backing layer 44 may be installed on the truss assemblies 12, followed by the liner system (e.g., such as liner 20). The liner 20 is coupled to the top panels 30 and planar panels 26 as noted above. Thus, the liner 20 covers the planar panels 26 and also defines the base 40 of the storage area 16. The particular configuration of the liner system, including the number of layers of liner to be utilized and installed, is determined in part by the material being stored, environmental regulations for storing such material, and other structural and safety considerations, as noted above.
Once the containment system 10 has been installed on site, the storage area 16 may be filled with material (fluid or granular) as needed for the particular application. As the storage area 16 of the system 10 is filled with the material, a horizontal load from the weight of the material is transferred outwardly (shown by outwardly extending forces F1 in
The containment system 10 may be utilized on the site until storage at the site is no longer required. After the system 10 is no longer needed at the site, and the storage area 16 is emptied of any material therein, the system 10 may be easily disassembled and relocated to a different site and/or stored for future use. The liner system (e.g., backing layer 44 and liner 20) may be transported away for further use, or discarded. The bands 18 may then be unstressed and removed from the load transfer rings 56, and either salvaged or discarded. The truss assemblies 12 may then be disassembled and/or relocated to another site, where the system 10 may be readily reassembled for further use.
Having generally described the invention, the same will be more readily understood through reference to the following example, which is provided by way of illustration and is not intended to be limiting of the present invention.
1.25 Million Gallon (30,000 bbl) Design Specifications:
Panel Configuration:
7 Strand Steel Pre-stressing/Post-tensioning Cables:
Liner System:
System Features:
It should be understood that the example disclosed above is provided for purposes of illustration only, and the present invention is not so limited. A larger or smaller containment system may be provided as required by the particular application. For example, as disclosed above, a storage tank able to contain 3 million gallons or more of material may be provided. Accordingly, the specific dimensions and system capabilities noted in the example above are exemplary only.
All publications and patents mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference in its entirety. While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth.
This application is based on U.S. Patent Application Ser. No. 61/545,956, filed Oct. 11, 2011, entitled “Temporary Above Ground Tank System Fabricated of Trusses and High Strength Steel Strand,” which application is incorporated herein by reference in its entirety and to which priority is claimed.
| Number | Date | Country | |
|---|---|---|---|
| 61545956 | Oct 2011 | US |
