Tank interceptor

Abstract: A tank interceptor for rain water and waste water includes a container which has an intermediate partition (22) dividing the chamber into a by-pass compartment (24) above the partition and a treatment compartment (26)below. An inlet is positioned adjacently above the partition and an outlet is also positioned adjacently above the partition, but spaced away from the inlet. The partition includes a raised portion (40) isolating the inlet from the outlet, such that liquid entering through the inlet and seeking to reach the outlet through the by-pass compartment (24) must overflow the raised portion (40) in order to do so. Openings are provided through the partition on the inlet side and the outlet side of the raised portion, and communicate the by-pass compartment (24) with the treatment compartment (26). The openings are such that liquid, without having to overflow the raised portion, can travel from the inlet to the outlet through the treatment compartment.

Description: This invention relates generally to separator tanks, sometimes called interceptors, adapted to receive primarily rainwater from a storm sewer or drain, and additionally to perform the function of separating and entrapping any oil- or gasoline-based materials and suspended solids that may enter, allowing the water fraction to discharge into municipal receiving sewers. US Patent No. 4,136,010 discloses a device of this kind which is equipped with various baffles and chambers operating in such a way as to collect specific components of the waste fluid and separate them from others. French Patent Application No. FR 2 694 748 discloses a digester for waste-water, comprising a flow passageway having an inlet and an outlet disposed at opposite ends thereof, a raised portion disposed in the passageway to isolate the inlet from the outlet, such that liquid entering through the inlet and seeking to reach the outlet through the passageway must overflow the raised portion in order to do so, and first and second openings in the floor of the passageway on the inlet side and the outlet side, respectively, of the raised portion, both openings communicating the passageway with a treatment compartment of the digester, the openings being such that liquid, without having to overflow said raised portion, can travel from the inlet to the outlet by passing through the first opening into the treatment compartment, thence through the treatment compartment, thence through the second opening into the passageway, thence to the outlet. In use, waste water containing sedimentary solids flow into the passageway, where the solids are diverted by the raised portion into the treatment compartment whilst the remaining waste water flows over the raised portion to the outlet. The treatment compartment contains a number of successive series-connected chambers extending between the first and second openings and, as the solid material travels through the successive chambers it is broken down by bacteriological action before being returned to the main flow. US Patent No. 4, 985,148 discloses a tank interceptor for rainwater and waste-water, comprising a container including a bottom wall, a side wall and a top wall, said walls defining an internal chamber, an inlet and an outlet extending through said side wall at spaced apart positions and interconnected inside the container by a passageway, said inlet and outlet being respectively adapted to permit liquid to flow into and out of the container, a raised portion being disposed in the passageway to isolate the inlet from the outlet, such that liquid entering through the inlet and seeking to reach the outlet through the passageway must overflow the raised portion in order to do so, and first and second openings in the floor of the passageway on the inlet side and the outlet side, respectively, of the raised portion, both openings communicating the passageway with a treatment compartment within said container, the openings being such that liquid, without having to overflow said raised portion, can travel from the inlet to the outlet by passing through the first opening into the treatment compartment, thence through the treatment compartment, thence through the second opening into the passageway, thence to the outlet. The tank interceptor of US Patent No. 4,985,148 is arranged to deal with materials entering the interceptor, including discharge from a service station, garage, machine shop, factory of the like, or oil that has spilled accidentally, these non-aqueous materials being collected within the interceptor. The aqueous fraction is allowed to leave the interceptor through the outlet and pass on to a storm sewer or the like, but the liquid fraction made up of oil or fat of animal, vegetable or mineral origin, gasoline and the like remains trapped within the treatment compartment until the same is pumped out. Further, any heavier-than-water materials sink to the bottom of the treatment compartment and are confined to a particular location from where they can also be pumped out at intervals. The interceptor of US Patent No. 4,985,148 is also adapted to deal with inflow resulting from heavy rain during a storm. Such inflow would typically be a combination of storm drainage from an adjacent industrial property, garage or the like, as well as inflow from storm drains adapted to catch rainwater. When a large quantity of rainwater arrives at the interceptor of the prior invention, the interceptor automatically diverts most of this flow directly over the raised portion to the outlet, which passes it directly to a storm sewer. Only a portion of the flow of the incoming rainwater is allowed through the treatment compartment of the interceptor. The passageway between the inlet and the outlet is essentially sealed from communication with the remainder of the interior of the tank interceptor, except for the openings on opposite sides of the raised portion. Each opening communicates the passageway with the treatment chamber formed by the remainder of the interior of the container. Finally, the raised portion forms a weir which a weir within the passageway which; under relatively low entry flow rates, diverts all materials entering the interceptor through the first opening and into the treatment chamber. Under relatively high entry flow rates, part of the entering materials overflow the weir and are delivered by the passageway directly to the outlet by-passing the treatment chamber. We have realised that it is not necessary for the entire volume inside the interceptor tank (except for the passageway means) to be used as a treatment chamber. Also, it is considered desirable that the means providing the passageway be more fully accessible to personnel wishing to inspect the installation for damage, improper accumulations of materials, etc. Accordingly, it is an object of this invention to provide a tank interceptor having a treatment compartment in the bottom portion thereof and a convenient area where inspection personnel may stand. It is also an object of this invention to provide means defining a passageway or channel which is upwardly open, and which can be inspected directly by personnel. It is also an object of this invention to provide flexibility as to the relative positions and peripheral spacing of the inlet and the outlet of the separator tank. In order to achieve the above objects of this invention, we have now devised a tank interceptor for rainwater and waste-water of similar construction to the digester of US Patent No. 4, 985, 148 which is characterised in that a partition extends across the chamber and divides the chamber into upper and lower portions respectively defining a by-pass compartment and said treatment compartment, the partition having a top wall on which said passageway is provided, the inlet and outlet being positioned adjacently above the top wall of the partition, said raised portion being provided on said top wall between the inlet and outlet, an aperture extending through the top wall of the container into the by-pass compartment, the aperture being sized to allow passage of a worker wishing to inspect the by-pass compartment. A disadvantage of known tank interceptors is that under storm flow conditions any trapped oil or gasoline-based materials can be washed back into the sewer or drain together with any trapped solids. Thus, in a preferred embodiment, an elongate pipe extends downwardly from the second opening into the treatment compartment. In a preferred embodiment, the container at least is formed from concrete, so that it is strong and hard wearing. Furthermore, the construction of the container lends itself to the use of off-the-shelf concrete components. Embodiments of this invention will now be described by way of examples only and with reference to the accompanying drawings, in which: FIGURE 1 is a perspective view of an intermediate partition of a first embodiment of this invention within a cylindrical chamber, dividing the chamber into upper and lower compartments; FIGURE 2 is a perspective view of the said partition, to a larger scale; FIGURE 3 is a somewhat schematic view, to a smaller scale, of a complete tank interceptor installation in accordance with the first embodiment of this invention; FIGURE 4 is a vertical section through an alternative embodiment of tank interceptor in accordance with this invention; FIGURE 5 is a sectional view along the line V-V of Figure 4; FIGURE 6 is a vertical section through the tank interceptor of Figure 4, showing the interceptor in use under normal flow conditions; and FIGURE 7 is a vertical section through the tank interceptor of Figure 4, showing the interceptor in use under storm flow conditions. Attention is first directed to Figure 3, which shows a tank interceptor generally at the numeral 10, the interceptor being generally in the shape of a container 12 that has a bottom wall 14, a side wall 16 and a top wall 18. It will be noted that the bottom and top walls 14 and 18 are circular, flat and horizontal, whereas the side wall of the embodiment illustrated in Figure 3 is substantially cylindrical. The bottom wall 14, side wall 26 and top wall 18 define an internal chamber 20. A partition seen in broken lines at the numeral 22 divides the chamber 20 into a by-pass compartment 24 above the partition 22 and a treatment compartment 26 below the partition 22. In the embodiment illustrated in Figures 1, 2 and 3, the partition 22 has a top surface 28, the major portion of which lies substantially in a single horizontal plane, except for a raised portion which will be described subsequently. The side wall 16 has an inlet opening 30 adjacently above the top surface 28 of the partition 22, and has an outlet opening 32 adjacently above the top surface 28 and spaced peripherally away from the inlet opening 30. Connected to the inlet opening 30 is a conduit 34 through which liquid can be admitted to the compartment 24 above the partition 22. Likewise, a conduit 36 is connected to the outlet opening 32 and is adapted to allow liquid to flow out of the by-pass compartment 24. As particularly seen in Figure 1, the flat top surface 28 of the partition 22 is configured to include a raised portion shown generally at 40 which isolates the inlet opening 30 from the outlet opening 32, such that liquid entering through the inlet opening 30 and seeking to reach the outlet opening 32 through the by-pass compartment must overflow the raised portion 40 in order to do so. More particularly, the raised portion 40 has the shape of an elongate weir with a sloping sidewall 42 in the direction of the inlet opening 30. The sloping sides serve to minimize turbulence in the liquid. Still more particularly, the raised portion 40 shown in Figure 1 is essentially trapezoidal in cross-section, and has two arms 44 and 46 which are disposed substantially radially with respect to the cylindrical side wall 16, meeting at a part-circular hub 48 which includes a part-frusto-conical side wall 50 and also defines a central opening 52 through the partition, the opening being sealable by a man-hole cover. Still referring to Figure 1, the interceptor includes a first opening 54 through the partition 22 on the inlet side of the weir constituted by the raised portion 40, and has a second opening 56 on the outlet side of the raised portion 40, the second opening 56 also extending through the partition 22. The openings 54 and 56 are such that liquid, without having to overflow the raised portion 40, can travel from the inlet opening 30 to the outlet opening 32 by passing through the first opening 54 into the treatment compartment below the partition 22, thence through the treatment compartment, thence through the second opening 56 into the by-pass compartment 24, thence directly to the outlet opening 32. It is to be noted that the second opening 56 can be located anywhere on the portion of the top surface 28 of the partition 22 which is on the "outlet" side of the weir constituted by the raised portion 40. As illustrated in Figure 2, the preferred embodiment of the invention includes a drop pipe 60 connected to and extending downwardly from the first opening 54 and having a T-shape 62 at the bottom, in order to distribute entering liquid in opposite directions within the treatment compartment. Similarly, the second opening 56 communicates with and is connected to a riser pipe 64 which allows upflow of liquid from the treatment compartment to the by-pass compartment. Returning to Figure 3, it will be noted that the interceptor includes an access man-hole 66 located eccentrically with respect to a cylindrical extension 68, which in turn is located eccentrically with respect to the main interceptor container 12, and extends upwardly from the top wall 18 thereof. The eccentricities are in the same direction, so that a vertical ladder may be provided for a worker wishing to climb down through the man-hole opening and to stand on the partition 22. Referring to Figures 4 and 5 of the drawings, there is shown a second embodiment of tank interceptor and like parts are given like reference numerals. The configuration of tank interceptor in accordance with this invention lends itself to manufacture from concrete components. Thus, in the embodiment of Figures 4 and 5 the side-wall 16 of the container 12 comprises upper and lower conventional concrete pipes 70, 71 mounted end-to-end, the upper pipe 70 resting on a flange (not shown) which extends from the lower pipe 71 in the conventional manner. During manufacture the bottom wall 14 is cast onto the lower pipe 71 by standing the pipe on a flat surface and pouring concrete into the bottom of the pipe. When the concrete sets, it forms an integral bottom wall 14. Likewise, the partition 22 is cast onto the upper pipe 70 by arranging a profiled mould normal to the axis of the pipe adjacent the lower end thereof. The pipe is then inverted and concrete poured into the pipe to cover the mould. When the concrete sets, the mould can be removed, thereby forming a partition 22 having a profiled surface facing inwardly towards the opposite end of the pipe. The raised portion or so-called weir 40 comprises a semicircular-section of concrete pipe which is arranged on locations that are cast on the portion 22. Opposite ends of the weir 44 extend from respective points on the wall of the pipe 70 on opposite sides of the inlet opening 30. The opening 54 through the partition 22 on the inlet side of the weir 44 is disposed substantially concentrically with the weir 44, so that liquid entering the tank through the inlet 30 forms a vortex around the opening 54. A plastics drop pipe 60 extends downwardly from the opening 54, the lower end of the drop pipe being connected to a T-fitting 62. The second opening 56 through the partition 22 on the outlet side of the weir 44 is much greater in diameter than said first opening 54, so that it can be used as a passageway to gain access to the treatment chamber 26. A plastics riser pipe 64 extends downwardly from the second opening 56 into the treatment chamber 24. The inlet and outlet openings 30,32 in the wall of the pipe 70 comprise annular elastomeric seals which seal against conventional inlet and outlet drainage pipes 34,36 attached thereto. The top wall 18 comprises a conventional, circular, concrete reducing slab having an eccentric aperture, the slab resting on the upper end of the upper pipe 70. The cylindrical extension comprises a plurality of small diameter concrete pipes 68 extending end-to-end upwardly from the eccentric aperture in the slab, the number of pipes being used depending on the depth at which the container 12 is buried underground. A man-hole cover 66 closes the upper end of the cylindrical extension 68. The operation of the tank interceptor of Figures 4 and 5 will now be described. However, it will be appreciated that the operation of the tank interceptor of Figures 1 to 3 is essentially the same. Referring to Figure 6 of the drawings, after installation and hook-up, the interceptor would be filled with clean water, up to a level L which is slightly below the bottom of the partition 22, this being a level which is above the bottoms of the drop pipe 60 and the riser pipe 64. The garage, service station or the like with which the interceptor is associated may produce a certain amount of waste-water mixed with oil, grit, etc., and this can find its way into the sewer which connects with the inlet opening 30. When there is no rain, the only material which can reach the interceptor would be that produced by the operation of the service station or the like. This flow will be relatively low, and will pass through the first opening 54 and down the drop pipe 60 to the T-fitting 62, thus entering the treatment compartment below the partition 22, without having to overflow the weir 40. As aqueous and non-aqueous materials flow into the treatment compartment 26, there will be some gravity flow of water through the riser pipe 64 and out of the outlet opening 32. As non-aqueous materials enter, oil and other light liquids will rise to the surface of the treatment chamber 26, where they form a trapped layer 0. Any sediment will settle to the bottom of the chamber 26, to form a layer S. As more light liquids enter, the layer 0 will continue to increase in thickness, but only water will pass through the riser pipe 64 and out of the outlet opening 32 until the oil layer becomes so thick that the interface between the oil and the water descends to the bottom of the riser pipe 64. From time to time, the treatment chamber 26 will be inspected through the opening 56. When it is noted that a large quantity of oil-based material has collected above the water in the treatment compartment, this material can be pumped out. In an alternative embodiment a sensor and alarm may be provided to indicate when the oil needs to be pumped out. Referring to Figure 7 of the drawings, imagine now that a rain storm occurs, and that suddenly the flow rate at which materials arrive at the interceptor increases by a factor of 20. This will certainly overflow the weir 40, and practically the entire overflow will pass from the inlet opening 30 to the outlet opening 32 through the by-pass compartment (above the partition 22). During the by-pass of the torrent of rain water, some of it will pass downwardly through the pipe 60, causing water already in the treatment compartment 26 to be displaced upwardly through the riser pipe 64 and out of the outlet opening 32. However, so long as the oil layer O in the treatment compartment is not thick enough to equal the vertical height of the riser pipe 64, then only water or aqueous liquids will pass upwardly through the riser pipe 64 and out of the outlet opening. Thus, none of the oil or other light liquids in the trapped layer O will be washed out of the treatment chamber under storm flow conditions. Furthermore, none of the sediment in the chamber will be washed back into suspension. It will be understood from the above description that each of the interceptors shown in the Figures is designed to prevent oil and solids from discharging into municipal receiving sewers. As such, each interceptor constitutes an important spill-containment device, capable of retaining oil and other lighter-than-water liquids securely stored within the unit in a way that prevents them from being flushed into the municipal receiving sewers.

Claims: A tank interceptor (10) for rainwater and waste-water, comprising: a container (12) including a bottom wall (14), a side wall (16) and a top wall (18), said walls defining an internal chamber, an inlet (30) and an outlet (32) extending through said side wall 916) at spaced apart positions and interconnected inside the container (12) by a passageway, said inlet (30) and said outlet (32) being respectively adapted to permit liquid to flow into and out of the container (12), a raised portion (40) being disposed in the passageway to isolate said inlet (30) from said outlet (32), such that liquid entering through the inlet (30) and seeking to reach the outlet (32) through the passageway must overflow the raised portion (40) in order to do so, and first and second openings (54,56) in the floor of the passageway on the inlet side and the outlet side, respectively, of the raised portion (40), both openings (54,56) communicating the passageway with a treatment compartment (26) within said container (12), the openings (54,56) being such that liquid, without having to overflow said raised portion (40), can travel from said inlet (30) to said outlet (32) by passing through the first opening (54) into the treatment compartment (26), thence through the treatment compartment (26), thence through the second opening (56) into the passageway, thence to the outlet (32), characterised in that a partition (22) extends across the chamber and divides the chamber into upper and lower portions respectively defining a by-pass compartment (24) and said treatment compartment (26), the partition (22) having a top wall (28) on which said passageway is provided, said inlet (30) and said outlet (32) being positioned adjacently above the top wall (28) of the partition (22), said raised portion (40) being provided on said top wall (28) between said inlet (30) and said outlet (32), an aperture extending through the top wall (18) of the container into the by-pass compartment (24), the aperture being sized to allow passage of a worker wishing to inspect the by-pass compartment (24). A tank interceptor as claimed in claim 1, characterised in that the partition (22) includes a passageway (52, 56) between the by-pass and treatment compartments (24,26), the passageway being sized to allow passage of a worker wishing to inspect the treatment compartment (26). A tank interceptor claimed in claim 2, characterised in that the passageway extends through a said opening (56) in the partition (22). A tank interceptor as claimed in any preceding claim, characterised in that an elongate pipe (64) extends downwardly from said second opening (56) into the treatment compartment (26). A tank interceptor as claimed in any preceding claim, characterised in that an elongate pipe (60) extends downwardly from said first opening (54) into the treatment compartment (26). A tank interceptor as claimed in any preceding claim, characterised in that the top wall of the partition (22) is inclined towards said opening (54) on the inlet side of the raised portion (40). A tank interceptor as claimed in any preceding claim, characterised in that the top wall of the partition (22) is inclined towards said opening (56) on the outlet side of the raised portion (40). A tank interceptor as claimed in any preceding claim, characterised in that the container is formed from concrete. A tank interceptor as claimed in any preceding claim, characterised in that the partition (22) is formed from concrete.

Inventors: MONTEITH JOSEPH GORDON, MONTEITH, JOSEPH GORDON
Applicants: CEPTOR INTERNAT LTD X, X-CEPTOR INTERNATIONAL LIMITED
Application year: 1995
Main classification: E03F5
IPC codes: E03F5, E03B3