Patent Publication Number: US-11021848-B1

Title: Riser sections and risers made therefrom

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. application Ser. No. 14/853,533 filed Sep. 14, 2015, which is a continuation of U.S. application Ser. No. 13/523,089 filed on Jun. 14, 2012, the disclosures of which are incorporated herein by reference for all purposes. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to riser sections, risers made therefrom and more particularly, to risers for use in wastewater treatment (WWT) systems or other buried structures. 
     BACKGROUND OF THE INVENTION 
     In WWT systems such as septic systems, aerobic wastewater treatment systems, etc., the main tank(s) are buried at a desired depth, depending upon the grade of the home or residence using the WWT system and other factors. Accordingly, there is a need in the WWT systems for risers, which extend from the buried tank to slightly above grade to allow access to the tank(s) for periodic cleanout, inspection of air diffusers, etc. Because the tank(s) are buried at different depths, it has been common in the industry to make riser sections; e.g., fiberglass, plastic, concrete, metal, etc. with different lengths. These different length riser sections are then connected in end-to-end relationship to achieve a desired overall length of the riser, which extends from the buried tank to about grade. 
     The problem with the use of these riser sections is they are not stackable or nestable, so that shipping large numbers of these riser sections becomes expensive. It is also recognized that these riser sections must have sufficient structural strength as to not collapse from the weight of surrounding soil. 
     SUMMARY OF THE INVENTION 
     In one aspect of the present invention, there is provided nestable, or stackable riser sections, which can be shipped much more economically. 
     In another aspect, the present invention provides a nestable riser section, having a first smaller diameter end, and a second larger diameter end. 
     In another aspect of the present invention, there is provided a nestable riser section, which can be easily molded using a single size mold. 
     A further aspect of the present invention is the provision of a riser section, which can be used to form risers with different size access openings at the end of the riser at, near or above grade. 
     Still a further aspect of the present invention is that there is provided a riser made from riser sections that has an access cover or hatch, which can be self locking and self sealing. 
     Another aspect of the present invention is that individual riser sections can be connected in end-to-end relationship without the necessity of screws, bolts or other type fasteners. 
     In yet another aspect of the present invention, there is provided a riser made up of riser sections for which no sealing means, e.g. caulking, O-rings or the like are necessary. 
     These and further features and advantages of the present invention will become apparent from the following detailed description, wherein reference is made to the figures in the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an environmental view showing a series of riser sections according to one embodiment of the present invention forming a riser extending from a buried tank to about grade. 
         FIG. 2A  is an isometric view of one embodiment of a riser section of the present invention. 
         FIG. 2B  is an isometric view, similar to  FIG. 2A  of another embodiment of the riser section of the present invention. 
         FIG. 2C  is an elevational view, party in section, showing riser sections shown in  FIG. 2B  connected together to form a riser. 
         FIG. 3  is a top plan view of the riser section shown in  FIG. 2 . 
         FIG. 4  is an elevational view, partly in section, taken along the lines  4 - 4  of  FIG. 3 . 
         FIG. 5  is an enlarged, detailed view showing the riser sections shown in  FIGS. 1-3  connected together to form a riser. 
         FIG. 6  is an elevational view, partly in section, of the riser sections shown in  FIGS. 1-5  nested or stacked. 
         FIG. 7  is a top, plan view of another embodiment of a riser section of the present invention. 
         FIG. 8  is an elevational view, partly in section, of the riser section shown in  FIG. 7 . 
         FIG. 9  is an enlarged, detailed showing the riser sections shown in  FIGS. 7 and 8  connected together to form a riser. 
         FIG. 10  is an elevational view, partly in section, of the riser sections shown in  FIGS. 7-9  nested or stacked. 
         FIG. 11  is an environmental view showing a series of riser sections according to another embodiment of the present invention forming a riser extending from a buried tank to about grade. 
         FIG. 12  is an elevational view, partly in section, of the risers sections used in the embodiment of  FIG. 11  nested or stacked. 
         FIG. 13  is an exploded, elevational view, partly in section, of a portion of the riser made using the riser sections shown in  FIG. 12 . 
         FIG. 14  is an elevational view, partly in section, showing how one end of the riser sections of  FIG. 12  can be connected together to form a riser. 
         FIG. 15  is an exploded, elevational view, partly in section, of another embodiment of a riser section of the present invention. 
         FIG. 16  is an elevational view, party in section of another embodiment of a riser section of the present invention. 
         FIG. 17  is an exploded, elevational view, partly in section of a riser made using another embodiment of the present invention. 
         FIG. 18  is an elevational view, partly in section, showing one form of the riser sections of the embodiment of  FIG. 17  nested or stacked. 
         FIG. 19  is an elevational view, partly in section, showing both forms of the riser sections of the embodiment of  FIG. 17  nested or stacked. 
         FIG. 20  is an environmental view, partly in section showing a series of riser sections according to another embodiment of the present invention, forming a riser extending from a buried tank to about grade. 
         FIG. 21  is a partially exploded, elevational view, showing in greater detail, connection of the riser sections shown in forming the riser of  FIG. 20 . 
         FIG. 22  is an elevational view, partly in section, of a first, stacked set of connecting rings used in connecting the riser sections shown in  FIGS. 20 and 21 . 
         FIG. 23  is a view similar to  FIG. 22  showing a modified form of the connecting rings used in connecting the riser sections shown in  FIGS. 20 and 21 . 
         FIG. 24  is partial elevational view, partly in section, showing another embodiment of a riser section of the present invention. 
         FIG. 25  is a partial, elevational view showing the connectors of the riser sections of  FIG. 24  prior to engagement. 
         FIG. 26  is a view of the connectors taken along the lines  26 - 26  of  FIG. 24 . 
         FIG. 27  is a partial, top, planar view of the riser sections of  FIG. 24  shown in the position depicted in  FIG. 25 . 
         FIG. 28  is a top, planar view of the riser sections of  FIG. 24  shown in the position depicted in  FIG. 26 . 
         FIG. 29  is a partial, elevational view, partly in section, showing another embodiment of the riser section of the present invention. 
         FIG. 30  is a partial, top, planar view of the riser section shown in  FIG. 29 . 
         FIG. 31  is an enlarged, top, planar view of a portion of the riser section shown in  FIG. 30 . 
         FIG. 32  is a partial, elevational view, partly in section, showing the details of the connection assembly used in the embodiment shown in  FIG. 29 . 
         FIG. 33  is a partial, top, planar view, partly in section, showing another embodiment of the riser section of the present invention. 
         FIG. 34  is a partial, elevational view of the riser section shown in  FIG. 33 . 
         FIG. 35  is a cross-sectional view taken along the lines  35 - 35  of  FIG. 34 . 
         FIG. 36  is a cross-sectional view taken along the lines  36 - 36  of  FIG. 34 . 
         FIG. 37  is a cross-sectional view taken along the lines  37 - 37  of  FIG. 34 . 
         FIG. 38  is a view similar to  FIG. 36  showing the riser sections prior to being connected. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     As used in the present invention, the term “stackable” or “nestable” refers to a structure of similar size and/or configuration, which can fit together in a separable manner; i.e., a series of structures wherein respective ones of said structures can fit into or on respective others of said structures. While, in general, the riser sections of the present invention will have a circular cross-section, it will be appreciated that other tapered stackable configurations could also be used. 
     The terms “engagement,” “engagement assembly,” “connection,” “connector assembly,” “connector” or similar words and terms as used herein refer to any formation(s), part, group of parts, whether forming part of the riser sections or separate therefrom, which are useful in connecting the individual riser sections together to form a riser. 
     While the present invention will be described with respect to a buried tank forming part of a WWT system, it will be understood that it is not so limited. For example, the riser sections of the present invention can be used to form risers for lift stations, to an underground shelter; e.g., storm shelter, or any other underground on buried structure. 
     Referring first to  FIG. 1 , there is shown a portion of a buried tank  10  forming part of a WWT system, buried at a distance D below ground level G. A riser shown generally as  12  extends from an opening  14  in tank  10  to slightly above ground level G. Riser  12  is made up of a series of riser sections  15  connected together, so as to achieve a length at least equal to the distance D and, as can be seen, slightly greater than distance D to extend above ground level G. A cover  16  is attached to the top of riser  12 , cover  16  being selectively removable to access the interior of tank  10  through riser  12 . 
     Referring now to  FIG. 2 , one of the riser sections  15  is shown in an isometric view. Riser section  15  has an annular radially inwardly extending lip, shown generally as  17 , having an upper, annular, axially facing surface  17 A, and a radially outwardly extending, annular flange  18 , flange  18  and lip  17  being connected to opposite ends of a generally frustoconical wall  20 . Wall  20  has a series of circumferentially spaced, vertically extending recesses  21  having vertical walls  21 A. While recesses  21  are shown as being spaced at 90° intervals to one another, it will be understood that fewer such recesses can be used to allow for connection of lateral piping (not shown) connected to riser  12 . Indeed, such recesses  21  can be dispensed with if desired. 
     Projecting upwardly from surface  17 A of lip  17  are a pair of headed keys  22 , keys  22  being circumferentially displaced 180° from one another. Also formed in lip  17  are a pair of keyholes  24 , keyholes  24  being spaced at 180° from one another and accordingly, at 90° from keys  22 . There is an annular groove  19  in surface  17 A for the receipt of an O-ring or similar seal. 
     Referring now to  FIG. 3 , it can be seen that flange  18  has a pair of keyholes  26 , keyholes  26  being generally coplanar with one another and with keys  22  and circumferentially spaced at about 180°. 
     Referring now to  FIG. 4 , it can be seen that the bottom surface  18 B of flange  18  has a key  30  similar to keys  22 . Although only one such key  30  is shown in  FIG. 4 , as can be seen from  FIG. 3 , there are two such keys  30  displaced 180° from one another, keys  30  being generally coplanar with keyholes  24 . 
     Referring now to  FIG. 5 , several riser sections  15  are shown connected together. To this end, it will be appreciated and as seen in  FIG. 5 , the flanges  18  of adjacent riser sections  15  are in abutment as are lips  17  of adjacent riser sections  15 . To connect successive sections  15 , keys  22  of one section are brought in to register with keyholes  24  of a second riser section. In like fashion, keys  30  of one riser section are brought into register with keyholes  26  of the adjoining riser section. It will be appreciated that the heads of the keys  22  will fit through the larger diameter portion of the keyholes  24 , while the heads of the keys  30  will fit through the larger diameter portion of the keyholes  26 . Once the keys  22 ,  30  are inserted into the keyholes  24 ,  26 , respectively, slight rotation of the abutting sections  14  forces the heads of the keys under the smaller openings of the keyholes, effectively locking the sections together. To effect sealing between the adjacent sections  15 , O-rings  34  and  36  are received in registering groove  19  in the abutting surfaces of flanges  18  and the abutting surfaces of lips  17 , respectively. Although O-rings are shown as the sealing means between the adjacent sections  14 , it will be appreciated that caulking, gaskets or other sealing means can be employed. 
     Referring now to  FIG. 2B , there is shown a slightly modified form of the riser section in  FIG. 2A . The riser section as shown in  FIG. 2B  differs from that shown in  FIG. 2A  in that instead of keys  22  and keyholes  24  and lip  17  of the embodiment shown in  FIG. 2A , in the embodiment shown in  FIG. 2B , the keys and keyholes have been replaced by circumferentially spaced holes L in lip  17 . Likewise, instead of flange  18  of the embodiment shown in  FIG. 2A  having alternating keys and keyholes, in the embodiment of  FIG. 2B , the keys and keyholes are replaced by a plurality of circumferentially spaced holes F. 
     As can be seen in  FIG. 2C , the riser sections of  FIG. 2B  are connected together by the use of nut/bolt assemblies N. In all other respects, the embodiment shown in  FIG. 2B  is substantially the same as that shown in  FIG. 2A . 
     One of the features of the embodiment of the present invention shown in  FIGS. 1-5  is that, the lips  17  and the flanges  18  provide reinforcement. Accordingly, the walls  20  of the sections  15  need not be thick, meaning that the sections are light-weight and require less material greatly minimizing their cost of manufacturing and shipping. In other words, lips  17  and flanges  18  resist external pressure from soil that surrounds the riser sections  15 , forming riser  12  when in place. 
     In connecting successive riser sections together, and as shown in  FIG. 5 , and assuming that the larger or flanged end of the riser section  15  were to be connected, the keys  30  on the flange of one riser section would be received in the keyholes  26  of an adjacent riser section such that the headed portion of the keys extended through the larger diameter end of the keyholes. With a slight twist, the two riser sections would then be locked together. 
     Referring now to  FIG. 6 , there is shown one of the advantages of the riser sections of the present invention. As shown, five riser sections  15  are shown in a stacked or nested arrangement for shipping. Because of the unique design of the riser sections of the present invention, they easily nest in one another, minimizing the amount of vertical volume that they occupy and accordingly, greatly reducing storage and/or shipping costs. For example, prior art riser section, since they are cylindrical, must be stacked in end-to-end relationship. Accordingly, and with reference to  FIG. 6 , it will be appreciated that if five prior art risers having a height H were stacked one upon another, they will occupy approximately five times the vertical volume occupied by five riser sections of the present invention, having an equal vertical height H. 
     While in the description above, the riser sections have been described in connection with forming a riser, which will extend between a buried tank or the like to slightly above grade, it will be recognized that the riser formed can, at its uppermost end, be at about grade; i.e., slightly below grade, at grade, or slightly above grade. Furthermore, it will be understood that the riser sections can be used to form risers which extend significantly above grade if such is needed. Also longitudinally extending tubular members made of riser sections  15  may be formed; e.g., to connect one buried structure to another buried structure. 
     In the embodiments discussed in  FIGS. 1-6 , while the use of a key and keyhole has been described as a means to connect individual riser sections to form a riser, it will be understood that the individual keys and/or the keyholes could be made with camming surfaces, such that when the key was inserted in the keyhole, a twisting action to connect individual riser sections together would result in the abutting surfaces of the riser sections being cammed together in water tight sealing engagement with one another. Accordingly, and as mentioned above, sealing means such as caulkings, O-rings, gaskets, etc., may not be unnecessary. Also, the locking formations, camming formations, etc. could be designed such that they included formations which acted like ratcheting mechanisms; i.e., when moved in one direction they cannot reverse direction, thereby ensuring that the riser sections would not separate from one another. 
     Referring now to  FIGS. 7-10 , there is shown another embodiment of the riser sections of the present invention. Referring first to  FIG. 7 , a riser section shown generally as  40  comprises an annular, frustoconical wall  42 , an annular, radially inwardly extending lip  44 , projecting from one end of wall  42  and an annular, radially outwardly projecting flange  46 , extending from the other end of wall  42 . Upper, axial facing surface  48  of lip  44  has a seal ring groove  50 . As in the case of the riser sections shown in  FIGS. 1-6 , riser sections  40  are provided with recesses  52  for the same purpose described above with respect to riser sections  14 . Projecting radially inwardly from lip  44  are a series of a circumferentially spaced tabs  56 , each of tabs  56  having an intermediate section  58  attached to the inner edge of and generally coplanar with lip  44 , and oppositely spaced, free flaps or wings  60  attached to the ends of intermediate section  58 . As best seen in  FIG. 8 , flaps  60  are not coplanar with intermediate section  58 , but project axially upwardly relative to surface  48  of lip  44 . 
     In a similar fashion, a plurality of circumferentially spaced tabs  70  project radially outwardly from the outer edge  72  of flange  46 . Like-tabs  56 , tabs  70  have an intermediate portion  74 , which is attached to and generally coplanar with flange  46 . Likewise, each of tabs  70  has a pair of spaced flaps or wings  76 , which project axially downwardly from flange  46 . As will be seen hereafter, flaps  60  and  76  form ramps or camming surfaces to allow adjacent riser sections  40  to be connected in end-to-end relationship to form a riser. 
     It can be seen with reference to  FIG. 7 , that tabs  56  and tabs  70  are staggered relative to one another, vis-à-vis their circumferential spacing. With reference to  FIG. 9 , it will be appreciated that, during assembly, flanges  46  on adjacent section  40  are brought together such that tabs  70  on one riser section are positioned in the free spaces between the tabs  70  on the adjacent riser section  40 . Thus, flanges  46  can be brought into abutment. It will now be seen from  FIG. 9  that if there is relative rotation between adjacent sections  40 , the ramps or camming surfaces formed by the flaps  76  of the tabs  70  of one riser section  40  will be forced under the ramps or camming surfaces formed by the flaps  76  of the adjacent riser section  40 . Continued rotation will force the intermediate sections  74  over one another, as shown in  FIG. 9 . Likewise, this relative rotation between adjacent sections  40  will cause a like result with respect to tabs  56  on lips  44 . In this way, it will be appreciated that the adjacent sections  40  will be securely locked together. It will be appreciated that any form of sealing; e.g., O-rings, caulk or the like can be employed. 
     Referring now to  FIG. 10 , it can be seen that once again, the riser sections  40  can be stacked or nested with the same result as described above with respect to the stacking or nesting of the riser sections  14  described in  FIG. 6 . 
     Referring now to  FIGS. 11-14 , there is shown a riser and riser sections according to another aspect of the present invention. Referring first to  FIG. 11 , a riser shown generally as  100 , made up of riser sections shown generally as  102 , extends from a buried tank or other structure  104  to slightly above ground level G, there being a removable lid or cover  106  on the uppermost section of riser  100 . With reference to  FIG. 12 , there is shown a stack or nest of riser sections  102 . 
     Referring now to  FIG. 13 , there is shown in detail how the riser sections  102  are connected. Each riser section  102  has a peripheral, frustoconical wall  106 . The smaller diameter end of riser section  102  has an annular radially inwardly extending rib portion  108  from which there is a radially inwardly projecting annular lip  110 , lip  110  having a series of circumferentially spaced holes  112 . Rib  108  has an annular groove  114  in which is received an annular seal ring  116 . To connect the smaller diameter end of successive riser sections  102  together, an annular ring  122  which is generally cross-shaped in cross-sectional configuration is employed. Thus, ring  122  has a generally horizontally extending arm  124  and a generally vertically extending arm  126 , arms  124  and  126  being substantially perpendicular to one another. The ends of vertical arm  126  are received in registering grooves  114  of successive riser sections  102  (see  FIG. 14 ), the abutting, small ends of risers sections  102  being secured together by a nut/bolt combination  128  received through the registering holes  112  in lips  110  of riser sections  102 . 
     The larger diameter end of riser section  102  includes an annular, radially outwardly extending rib  130  which projects outwardly from wall  106 , rib  130  having an annular, radially outwardly extending flange  132  having a series of circumferentially spaced holes  134 . Rib  130  has an annularly extending, axially facing groove  136  in which is received a seal ring  138 . To connect the large diameter ends of riser sections  102  together, a ring  140  having a cross-shaped cross-section with a horizontal arm  142  and a vertical arm  144  is used. As is shown in  FIG. 15 , to assemble the large diameter ends of the riser sections, the vertical arms  144  of the ring  140  are received in the registering grooves  136  of the ribs  130  and a nut/bolt combination  129  is received through each of the registering holes  134  in the flanges  132  as shown in  FIG. 15 . 
       FIG. 15  shows another embodiment of the present invention which is a variation of that shown in  FIGS. 13 and 14 . In  FIG. 15 , ring  160  has an H-shaped cross-section forming axially facing, annularly extending grooves  162 , seal rings  164  being received in grooves  162 . An assembly flange  166  extends outwardly from frustoconical wall  106 A and has a series of circumferentially spaced holes  168 . Each of the ends of the riser sections  159  has an axially projecting, annularly extending splines  170 , splines  170  being received in grooves  162  when respective riser sections  159  are secured together by means of nut/bolt assembly (not shown) extending through holes  168  in flanges  166 . 
       FIG. 16  shows yet another embodiment of the present invention wherein the riser sections shown generally as  171  have at each end a rib  172  and radially outwardly extending flange  174 . Formed in rib  172  is an annular groove  176 . When sections  171  are connected, a seal ring  178  is sealingly engaged in registering grooves  176 , the sections  171  being compressed together by a nut/bolt combination  180 . 
     It will be understood that with respect to the embodiments shown in  FIGS. 15 and 16 , that there will be a similar connector assembly comprised of the ribs, cross-shaped connecting rings, etc. on the smaller diameter ends of the riser sections, the ribs, projections, etc. being radially inwardly from the smaller diameter end, as opposed to radially outwardly from the larger diameter end as shown in  FIGS. 15 and 16 . 
     It will be understood that the embodiments shown in  FIGS. 13-16 , like the other embodiments described above are nestable or stackable so as to minimize storage and transportation costs. 
     Referring now to  FIGS. 17-19 , there is shown another embodiment of the riser sections of the present invention. The riser sections shown in  FIGS. 17-19  differ from those described above in that alternating riser sections have, at each end, either a male portion of a connector assembly or a female portion of a connector assembly. Referring now to  FIG. 17 , there is shown an exploded view of a riser shown generally as  190 . Riser  190  is comprised of female riser sections  192  which have female connector assembly or engagement ends and male riser sections  194  which have male connector assembly or engagement ends. Finally, riser sections  192  have a generally frustoconical wall  196  with a first end having an annular, radially inwardly extending rib  198 , a radially, inwardly extending, annular lip  199 , and an annular groove  200 , a seal ring  202  being received in groove  200 . Lip  199  has a series of circumferentially spaced holes  204  for a purpose to be described hereafter. 
     The larger end of riser section  192  has an annular radially outwardly extending rib  206  having an annular, radially outwardly extending lip  207  with a series of circumferentially spaced bolt holes  208 , and an annular axially facing groove  210 , a seal ring  212  being received in groove  210 . 
     Male riser section  194  has a generally frustoconical wall  214 , the smaller diameter end of riser section  194  having an annular, radially inwardly extending lip  216  with a series of circumferentially spaced bores or openings  218 . There is also an axially projecting, annularly extending rib  220 . The larger diameter end of riser section  194  has an annular, radially outwardly extending flange  222  having a series of circumferentially spaced bolt holes  224  and an annular, axially facing rib  226 . 
     To connect riser sections  192  and  194 , and with respect first to the larger ends thereof, annular ribs  226  are received in annular grooves  210 , ribs  226  engaging seal ring  212 . When seated together, a bolt  240  is received through registering holes  208  and  224  and is threadedly connected to a nut  242  whereby the larger ends of the risers  192  and  194  are compressed together and are in fluid tight engagement by virtue of seal  212 . 
     To connect the smaller ends of risers  192  and  194 , rib  220  of riser  194  is received in groove  200  of riser  192  and a nut/bolt combination  230  received in registering holes  204  and  218  in riser sections  192  and  194 , respectively, urge rib  220  into engagement with seal  202 , thereby providing a fluid tight seal. 
     Although, as noted, the riser sections differ in that female riser sections  192  are provided with receiving formations, i.e., grooves  200  and  210  forming a female part of a connector or connecting apparatus, male riser sections  194  have projecting formations in the form of ribs  226  and  220 . In other words, the respective ends of the riser sections have formations which are projecting as to one end and receiving as to other such that one riser section forms part of a connector or connector assembly having a female or receiving portion while an adjacent riser section has a connector or connector assembly comprised of a male or projecting formation. 
     It can also be seen that while the individual riser sections  192  and  194  differ in their connecting assemblies at their respective ends, each riser section is stackable. Thus, with reference to  FIG. 18 , the riser sections having the receiving or female formations forming part of the connector assembly are stackable with respect to one another whereas, as seen in  FIG. 19 , the riser sections can be alternated and still be stackable. In other words, with respect to  FIG. 19 , riser sections  192  and  194  can be alternately stacked. This is a clear advantage when the riser sections are being manually carried to the installation site. 
     Referring now to  FIGS. 20-23 , there is shown another embodiment of the riser sections and riser of the present invention. Referring first to  FIG. 20 , there is shown a riser  240  made up of riser sections  242 , riser  240  extending from a buried tank  244  to slightly above grade, indicated as G, riser  240  having a removable lid  246  thereon. As noted above, by removing lid  246 , one can access the interior of tank or vessel  244  through riser  240 . A feature of the riser  240  and for that matter, the riser sections  242 , shown in  FIGS. 20-23  is that rather than having to connect the small diameter ends to small diameter ends and large diameter ends to large diameter ends of the respective riser sections, in the embodiment shown in  FIGS. 20 and 21 , the riser sections can be connected such that the small end of one riser section is connected to the large end of an adjacent riser section and so on. Riser section  242  has a frustoconical wall  248  which terminates at its smaller end in a radially inwardly extending, annular lip  250 . Lip  250  has an annular extending, axially facing groove  252  and a series of circumferentially spaced holes  254 . The opposite, larger diameter end of frustoconical wall  248  is provided with an annular, radially outwardly extending lip  256 , lip  256  having an annular, axially facing groove  258  and a plurality of circumferentially spaced holes  260 . Positioned between lip  256  of one riser section and lip  250  of an adjacent riser section is a connecting ring  270  shown more clearly in  FIG. 22 . Connecting ring  270  has an annularly extending base  272  having a first side  274  and a second, opposite side  276 . Extending from side  274  is an annular, axially projecting rib  278  while a similar rib  280  extends from surface  276 . As can be seen, annular ribs  278  and  280  are concentric with respect to one another, rib  280  being radially innermost, rib  278  being radially outermost relative to base  272 . 
     Referring again to  FIG. 21 , it can be seen how ring  270  can be used to connect successive riser sections  242  together. In this regard, annular rib  278  is received in groove  258  of flange  256  while rib  280  is received in groove  252  of lip  250 . Through the use of bolt  290 /nut  292  assemblies, ring  270  can be used to connect successive riser sections  242 . In this regard, the bolts  290  are received through registering holes  294  in rings  270  and  254  in lip  250  as well as in registering holes  296  in ring  270  and  260  in lip  256 . When the nut/bolt combination is tightened, sections  242  are connected together as shown in  FIG. 21 . Thus, it is able to connect a smaller end of a riser section to a larger end of a riser section in successive steps to create the desired riser length. It will be readily apparent that not only are the riser sections  242  stackable, but, as shown in  FIG. 2 , the connecting rings  270  are likewise stackable.  FIG. 23  shows a slightly modified version of the connecting rings  270 . The rings  270 A shown in  FIG. 23  are structurally similar to rings  270  with the exception that the base has a first, radially outermost portion  300  and a second radially innermost portion  302 , both of which are annular, radially innermost portion  302  of the base being angled relative to section  300  of the base to provide greater stiffness of the connecting ring  270 . 
     Referring now to  FIGS. 24-28 , there is shown yet another embodiment of the riser sections of the present invention. Riser sections  300  are, in some respects, similar to the riser sections shown in  FIGS. 13 and 14 . In this regard, the riser sections  300  have a frustoconical wall  302  which terminates at its larger end in a radially, outwardly extending annular rib  304 , rib  304  being provided with an annular, axially facing groove  306  in which is positioned a seal ring  308 . A positioning ring shown generally as  310  is generally cross-shaped in transverse cross-section having vertical legs  314  which are received in grooves  306  and horizontal legs  312  which are positioned between portions of the ribs  304  of the adjacent riser sections  300 . 
     In order to lock sections  300  together, each end of the sections  300  is provided with a series of circumferentially spaced, axially projecting hooks or dogs shown generally as  320 . As best seen with reference to  FIGS. 24 and 27 , the hooks are connected to and radially outwardly of annular rib  304 . The hooks or dogs  320  are generally circumferentially spaced around the periphery of the riser sections  300  and have an axially projecting leg portion  322  from which laterally projects a foot portion  324  having an inclined surface  326  giving foot portion  324  a wedge shape. In the position shown in  FIGS. 25 and 27 , the dogs or hooks  320  are positioned such that they are circumferentially spaced from one another. However, upon relative rotation between the adjoining riser sections as indicated in  FIG. 26 , the inclined surfaces  326  will ride over another, camming the riser sections  300  together. This is best seen by the direction of arrows A and B showing one section  320  being rotated in the direction of A while the adjacent section  320  is being rotated in the direction of arrow B. This camming action forces the vertical legs  314  of cross-shaped ring  306  into tight engagement with the seal  308 . A clear feature of the embodiment shown in  FIG. 24  is that no additional fasteners, e.g., nut/bolt assemblies, are required to connect the adjacent riser sections together. 
     It will be understood that although only the connector assembly at the larger diameter end of the riser sections shown in  FIGS. 24 and 28  have been described, a similar connector assembly will be at the opposite, smaller diameter end of the riser section, the difference being that instead of the rib and other connecting pieces being positioned radially outwardly of the larger diameter end of the riser sections as shown in  FIGS. 24-28 , the rib and other connecting pieces of the connector assembly will be positioned radially inwardly of the smaller diameter end of the riser section. 
     Turning next to  FIGS. 29-32 , there is shown another embodiment of the riser section of the present invention. The riser section shown generally as  400  has a frustoconical wall  102 , a first, annular, radially inwardly extending flange  404 , at the first end  401  of riser section  400 , flange  404  having an annular, axially facing clip groove  406 . Riser section  400  further has a second, annular, radially outwardly extending flange  408  located at the second end  403  of riser section  400 . Flange  408  has an annular, axially facing clip groove  410  (see  FIG. 32 ). Groove  410  faces in the direction of first end  401  of riser section  400  while groove  406  faces in the direction of second end  403  of riser section  400 . There is an annular seal ring groove  412  formed in flange  408  on the side opposite clip groove  410 . Likewise with respect to flange  408 , there is a seal ring groove on the flange  404  on the side opposite of clip groove  406 . As can be seen, a seal ring  414  fits into registering grooves  412  when successive riser sections are connected. 
     In a similar fashion, radially inwardly extending flange  404  on first end  401  of riser section  400  has an annular groove  406  and a seal ring groove/seal ring combination shown generally as  412 . 
     Riser sections  400  are connected to one another by a series of clips shown generally as  500 . As can be seen in  FIG. 32 , clips  500  have a body portion  502  and first and second laterally extending fingers  504  and  506 . Fingers  504  and  506  are elastic with respect to body portion  502 . Finger  504  has an inwardly extending dog  508  while finger  506  has an inwardly extending dog  510 , dogs  508  and  510  defining a slot therebetween. Since fingers  504  and  506  are elastic with respect to body  502 , it will be appreciated that the slot width formed by dogs  508  and  510  can be expanded. Accordingly, assuming that clips  500  have the configuration shown in  FIG. 32  while unconnected to the riser sections, it will be appreciated that they can be laterally slid over the engaged flanges  408  until the dogs  508  and  510  engage the grooves  410  of the adjacent riser sections. In effect, clips  500  can be snapped over the engaged flanges  408  of adjacent riser sections, thereby compressed together by the force exerted by the elastic fingers  504  and  506 . 
     It will be understood and as seen in the drawings, to connect the other ends of the riser sections  400  together, the same procedure is employed with an exception of course being that at the smaller end of the riser section  400 , the clips are on the inside of the walls of the riser section  400  such that the clips extend radially inwardly as opposed to the clips connecting the larger areas of the riser sections which extend radially outwardly. In all other respects, the connection method is the same. 
     Referring now to  FIGS. 33-38 , there is shown another embodiment of the riser section of the present invention. The riser section shown generally as  600  has a frustoconical wall  602  terminating at one end in an annular, radially outwardly extending lip  604 . As thus seen with reference to  FIG. 35 , lip  604  has an annular, axially facing surface  606  which is undercut for reasons to be described hereafter. 
     There are a plurality of latch assemblies shown generally as  608  at circumferentially spaced intervals adjacent end  610  of the riser section  600 . Each latch assembly  608  has a body portion  612  having portions  614  which connect to the wall  602  of riser section  600 . Each latch  608  is provided with elastic fingers  616  extending axially from and connected elastically to body portion  612 . As best seen in  FIG. 38 , each finger  616  has a radially inwardly extending dog  618  having an undercut surface  620  which is complementary to undercut surface  606  of lip  604 . As can also be seen in  FIG. 37 , finger  616  has a chamfered surface  630  for reasons to be discussed hereafter. 
     To connect the end  603  of adjacent riser sections together, it is only necessary to align the end faces of the riser sections and then compressively urge them together. In this regard, and with reference to  FIGS. 36 and 38 . It will be seen that, in  FIG. 38 , as the adjacent riser sections  600  are urged together, the chamfered surface  630  on fingers  616  will engage the edge of lip  606  forcing fingers  616  radially outwardly as shown in  FIG. 38 . Further movement of the two adjacent riser sections together will force fingers  616  even further radially outwardly until the point where lip  606  is underneath dog  618  and undercut surfaces  620  and  606  are in engagement. Since the fingers are elastically connected to body  612 , they will then move radially inwardly and the undercut surfaces will exert a wedging effect forcing the two riser sections together. In this regard, and as noted in  FIG. 34 , the lip portion  604  has a seal ring groove in which is received seal ring  640 . Seal ring  640  being received in registering grooves of lips  604 . 
     Although in the description of  FIGS. 33-38 , the riser section  600  has been described with respect to connection of the larger end of the riser section, it will be appreciated that the same types of connection assemblies can be placed on the smaller end but that they will be located on the inside of the riser sections. In other words, latches would be attached to the inside walls of the riser sections. However, in all respects, the connection assembly would be the same as displayed in  FIGS. 33-38 . 
     Other than the riser sections of the present invention being nestable or stackable and therefore much more economical to ship and store, it will be appreciated that most of the riser sections can be formed from a single mold, which can turn out multiple, same height riser sections. Furthermore, the individual riser sections can be made quite short; e.g., three to twelve inches in length and thus becomes quite easy to provide a desired height riser between a buried tank and grade. 
     It will be appreciated that, although as described above, the riser sections are connected with interlocking keys/keyhole, camming surfaces, nut/bolt assemblies etc., the riser sections could employ other fasteners if desired. However the connection is made between individual sections to form a riser, the desirably is some ability or structure to compress abutting end surfaces of the individual sections together, so that a water tight seal is obtained, either with or without a separate seal member. 
     In many of the embodiments discussed above, radially projecting lips, ribs, flanges, etc. impact structural stability. It will be appreciated, however, that axially extending ribs or the like on the frustoconical walls of the riser sections could also be employed to impart sufficient structural integrity. In other words, certain of the riser sections could be formed without flanges, lips, ribs or the like at opposite ends of the tapered walls forming the riser sections and connection between the riser sections would be accomplished by formations projecting as to one and receiving as to the other, which were formed on the axially facing ends of the frustoconical walls forming the riser sections. In this manner, there would be substantially no radially projecting ribs, lips, flanges, etc., whether inwardly or outwardly. 
     Virtually any type of formation projecting as to one and receiving as to the other, or connecting assembly can be employed to connect adjacent ends of the individual riser sections together. However, it is desired that the individual sections be produceable from a single mold, although such is not necessary. 
     As noted above, one advantage of some of the riser sections of the present invention is that a riser can be formed of monolithic pieces. In other words, the riser sections not only form an axial portion of the riser, but the riser sections are connectible to one another by virtue of structures or formations formed on the ends of the individual riser sections which engage to connect them together, as described above. Accordingly, in such cases, as shown, fasteners such as screws, nuts and bolts, etc., could be eliminated. 
     One of the problems with prior art riser sections which are almost universally connected by means of fasteners such as nut/bolt assemblies, is that these fasteners, because they are made of metal, are prone to corrode and break, meaning that the individual riser sections may leak because the abutting faces of the individual sections are no longer being held together. Furthermore, in the installation, the use of monolithic riser sections of the present invention reduces the number of parts that an installer needs. It will be remembered that, particularly in the case of WWT systems, the WWT system may be installed at a remote location. For efficiency, this necessitates that the installer have all the parts needed to connect the riser sections to form the desired height of the riser. It is not uncommon for an installer, when at a WWT system site, to not have the necessary fasteners, meaning that a further trip must be made to obtain such fasteners so that the individual sections can be connected. 
     One of the many advantages of the riser sections of the present invention is that inventory can be reduced and accordingly, storage space reduced. For example, if the riser sections are all made with a 3″ to 5″ vertical height, only riser sections falling within that range need be stored in inventory. 
     Although as noted above, if a single, desired height riser section is all that is desired, only a single mold is necessary to produce the individual riser sections. However, it is not intended that the present invention be limited to the use of one size mold. For example, if it was desired to have a family of riser sections instead of a single vertical height riser section, multiple molds could be employed, each of the molds having different tapers, such that even though the riser sections would have different heights, they could still be connected together because their ODs at the smaller end and the larger end would still mate; i.e., be in register. Thus, one could form a family of riser sections; e.g., 2″, 5″, 12″, meaning that there would be three different molds of three different tapers, the goal being that the small ends of the riser sections, regardless of their height, would connect together and the large end of the riser sections, regardless of their height, would also connect together; i.e., the small ends of the smallest riser sections and the small ends of the largest riser sections in the family would be in register with one another when they are being connected together as would be the case with the large diameter ends of the riser sections. 
     Although the riser sections can be made over a wide range of height and diameters, generally, the diameter of the riser sections at the small end of the tapered wall would generally be about 10″ or greater, while the diameter of the tapered wall sections on the large end could be as large as 38″ or larger. 
     Although as described above, the riser formed from the riser sections of the present invention has a lid fastened at the upper end of the riser about at grade, it will be understood that it can be made with the same connecting formations used with individual riser sections. Further, the lids could be made in different heights so that almost the exactly desired height of the riser, including the hatch or cover could be achieved. Also, the lids could be made in such a way that individual lid portions could be connected together much in the same way that the individual riser sections are connected together. 
     It can thus been from the above that the riser sections of the present invention can be connected together using a wide variety of connector assemblies or connectors to form risers of desired length. For example, the riser sections can be connected as shown in  FIGS. 1-6  using flange-to-flange and lip-to-lip engagement and employing nut/bolt assemblies and/or key-keyhole arrangements, the latter requiring slight relative rotation between adjoining riser sections. Additionally, individual riser sections can be connected together using camming tabs which extend radially inwardly and radially outwardly from opposite ends of individual riser sections, the camming tabs being engaged to force the riser sections together by relative rotation of the individual riser sections. Additionally, the riser sections can be connected by using certain riser sections having male connections at both ends while other riser sections having female connections at both ends. The riser sections can also be connected together using various connecting assemblies such as rings of various shape which are received in grooves and/or have grooves in which are received splines extending from the individual riser sections. The riser sections can also be connected by camming hooks which project axially from the ends of the riser sections, the camming hooks being engageable by relative rotation of the adjacent riser section. Although specific embodiments of the invention have been described herein in some detail, this has been done solely for the purposes of explaining the various aspects of the invention, and is not intended to limit the scope of the invention as defined in the claims which follow. Those skilled in the art will understand that the embodiment shown and described are exemplary, and various other substitutions, alterations and modifications, including but not limited to those design alternatives specifically discussed herein, may be made in the practice of the invention without departing from its scope.