Patent Publication Number: US-2021188660-A1

Title: Modular underdrain systems

Description:
RELATED APPLICATIONS 
     This application claims priority to and is a continuation application of U.S. application Ser. No. 16/355,655, which was filed on 15 Mar. 2019 and is entitled “MODULAR UNDERDRAIN SYSTEMS,” which is hereby expressly incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to underdrain systems for use in filtration systems. 
     BACKGROUND 
     Underdrain systems for use in filtration systems are difficult to construct. Further, it is challenging to formulate an underdrain system that achieves proper water flow during the filtering state and/or proper water flow and airflow during a cleaning state. Accordingly, an improved underdrain system is desirable to overcome one or more of the foregoing challenges. 
     SUMMARY 
     Embodiments of the disclosed subject matter are provided below for illustrative purposes and are in no way limiting of the claimed subject matter. 
     Various embodiments of a modular underdrain system for use in a filter cell for filtering water are disclosed. The filter cell may comprise a filter chamber including filter media separated from an underdrain chamber by the modular underdrain system. The filter cell may further comprise a water injection mechanism for inputting water to be filtered into the filter chamber and water and air injection mechanisms for inputting cleaning water and air into the underdrain chamber. The modular underdrain system may comprise a plurality of modular components with each of the plurality of modular components comprising a depth dimension, a width dimension, and a length dimension with at least one of the plurality of modular components comprising an intermediate modular component. 
     One of the intermediate modular components may comprise a first peripheral side and a second peripheral side. The first peripheral side may be opposite the second peripheral side along the width dimension. The first peripheral side may comprise a first mating portion, and the second peripheral side may comprise a second mating portion. The second mating portion may be sized and shaped to engage with a first mating portion of an adjacent modular component. The first peripheral side may comprise at least one transfer orifice. 
     The intermediate modular component may comprise a modular component chamber bounded by an underdrain floor side and an internal side with the underdrain floor side being offset from at least a portion of the internal side along the depth dimension. The underdrain floor side may comprise a plurality of slots, and the internal side may comprise a metering pipe opening. 
     The intermediate modular component may also comprise a metering pipe sized to be positioned within the metering pipe opening. The metering pipe opening may comprise a distributor head for positioning within the modular component chamber and an outside portion for positioning outside of the modular component chamber. The outside portion of the metering pipe may comprise a set of one or more proximate orifices and a set of one or more remote orifices with the set of one or more proximate orifices being disposed closer to the modular component chamber along the depth dimension than the set of one or more remote orifices. 
     The at least one transfer orifice may comprise a first transfer orifice and a second transfer orifice with the first transfer orifice and the second transfer orifice being offset along the depth dimension. 
     The modular component chamber may comprise a first subchamber separated by a baffle from a second subchamber with the baffle limiting fluid flow between the first subchamber and the second subchamber. The intermediate modular component may further comprise a second metering pipe disposed at least partially within the second subchamber, the metering pipe being at least partially disposed within the first subchamber. The intermediate modular component may further comprise a second baffle spaced apart from the baffle along the length dimension of the intermediate modular component. 
     In various embodiments, when the modular underdrain system is in an installed state, the modular component chamber has a modular component chamber cross-sectional area bounded by the internal side and the underdrain floor side, and the intermediate modular component has an underdrain chamber cross-sectional area bounded by the internal side, the first peripheral side, a substrate to which the first peripheral side is attached, the second peripheral side, and a first peripheral side of the adjacent modular component, the modular component chamber cross-sectional area being 6% to 25% of the underdrain chamber cross-sectional area. 
     In various embodiments, a depth dimension of the first peripheral side is greater than a depth dimension of the second peripheral side. 
     In various embodiments, the first peripheral side comprises a foot for securing the intermediate modular component to the substrate. 
     In various embodiments, the intermediate modular component further comprises a seal positioned between the first mating portion and the second mating portion of the adjacent modular component. 
     In various embodiments, the set of one or more remote orifices comprises a remote end orifice disposed at an end of the metering pipe most remote from the modular component chamber. 
     Various embodiments of a modular underdrain system comprising a plurality of modular components are disclosed. Each of the plurality of modular components may comprise a depth dimension, a width dimension, and a length dimension. The plurality of modular components may comprise at least one intermediate modular component. The intermediate modular component may comprise a first peripheral side and a second peripheral side with the first peripheral side being opposite the second peripheral side along the width dimension. The first peripheral side may comprise a first mating portion, and the second peripheral side may comprise a second mating portion with the second mating portion being sized and shaped to engage with a first mating portion of an adjacent modular component. The first peripheral side may comprise at least one transfer orifice. 
     The intermediate modular component may comprise a modular component chamber bounded by an underdrain floor side and an internal side with the underdrain floor side being offset from at least a portion of the internal side along the depth dimension. The underdrain floor side may comprise a plurality of slots, and the internal side may comprise a metering pipe opening. 
     The intermediate modular component may also comprise a metering pipe sized to be positioned within the metering pipe opening. The metering pipe opening may comprise a distributor head for positioning within the modular component chamber and an outside portion for positioning outside of the modular component chamber. The outside portion of the metering pipe may comprise a set of one or more proximate orifices and a set of one or more remote orifices with the set of one or more proximate orifices being disposed closer to the modular component chamber along the depth dimension than the set of one or more remote orifices. 
     In various embodiments, the second mating portion comprises a tang, and the first mating portion of the adjacent modular component comprises an engaging slot. 
     In a number of embodiments, the at least one transfer orifice comprises a first transfer orifice and a second transfer orifice, the first transfer orifice and the second transfer orifice being offset along the depth dimension. 
     In various embodiments, the modular component chamber comprises a first subchamber separated by a baffle from a second subchamber, the baffle limiting fluid flow between the first subchamber and the second subchamber. 
     In a number of embodiments, when the modular underdrain system is in an installed state, the modular component chamber has a modular component chamber cross-sectional area bounded by the internal side and the underdrain floor side, and the intermediate modular component has an underdrain chamber cross-sectional area bounded by the internal side, the first peripheral side, a substrate to which the first peripheral side is attached, the second peripheral side, and a first peripheral side of the adjacent modular component, the modular component chamber cross-sectional area being 6% to 25% of the underdrain chamber cross-sectional area. 
     Various embodiments of a modular underdrain system comprising at least a first and a second intermediate modular component are disclosed. Each of the first and the second intermediate modular components each may comprise a depth dimension, a width dimension, and a length dimension. Each of the first and second intermediate modular components may comprise a first peripheral side and a second peripheral side with the first peripheral side being opposite the second peripheral side along the width dimension. The first peripheral side may comprise a first mating portion and the second peripheral side comprising a second mating portion with the second mating portion being sized and shaped to engage with a first mating portion of an adjacent modular component. The first peripheral side comprising at least one transfer orifice. 
     Each of the first and second intermediate modular component may comprise a modular component chamber bounded by an underdrain floor side and an internal side with the underdrain floor side being offset from at least a portion of the internal side along the depth dimension. The underdrain floor side may comprise a plurality of slots, and the internal side may comprise a metering pipe opening. 
     Each of the first and second intermediate modular components may also comprise a metering pipe sized to be positioned within a metering pipe opening. The metering pipe may comprise a distributor head for positioning within the modular component chamber and an outside portion for positioning outside of the modular component chamber. The outside portion of the metering pipe may comprise a set of one or more proximate orifices and a set of one or more remote orifices with the set of one or more proximate orifices being disposed closer to the modular component chamber along the depth dimension than the set of one or more remote orifices. 
     In various embodiments, when the first mating portion of the first intermediate modular component is engaged with the second mating portion of the second intermediate modular component a combination of the underdrain floor side of the first intermediate modular component and the underdrain floor side of the second intermediate modular component define a substantially flat surface. 
     The modular drain system may further comprise a hold down member positioned on or adjacent to the substantially flat surface. 
     The modular underdrain system may further comprise a terminating modular underdrain component devoid of transfer orifices for engaging with the second intermediate modular component. The modular underdrain system may further comprise a starter strip for engaging with a third intermediate modular component. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only examples of the invention thereof and are, therefore, not to be considered limiting of the invention&#39;s scope, particular embodiments will be described with additional specificity and detail through use of the accompanying drawings in which: 
         FIG. 1  is a cross-sectional view of one embodiment of a portion of a filter cell, including a modular underdrain system, in a filtering state; 
         FIG. 2  is a cross-sectional view of the portion of the filter cell of  FIG. 1  shown in a media cleaning state; 
         FIG. 3  is a cross-sectional view of a larger portion of the filter cell of  FIG. 1  shown without filter media, water, or air disposed therein; 
         FIG. 4A  is a top perspective view of a segment of an intermediate modular component shown in  FIGS. 1-3 ; 
         FIG. 4B  is a bottom perspective view of the segment (i.e., a portion) of the intermediate modular component depicted in  FIG. 4A ; 
         FIG. 4C  is a front elevational view of the segment of the intermediate modular component shown in  FIG. 4A ; 
         FIG. 4D  is a rear elevational view of the segment of the intermediate modular component shown in  FIG. 4A ; 
         FIG. 4E  is a side elevational view of the segment of the intermediate modular component shown in  FIG. 4A ; 
         FIG. 5A  is a front exploded view of the segment of the intermediate modular component shown in  FIG. 4A ; 
         FIG. 5B  is a perspective exploded view of the segment of the intermediate modular component shown in  FIG. 4A ; 
         FIG. 6A  is an elevational, cross-sectional view of the segment of the intermediate modular component taken across the line  6 A- 6 A in  FIG. 4C ; 
         FIG. 6B  is an elevational, cross-sectional view of the segment of the intermediate modular component taken across the line  6 B- 6 B in  FIG. 4C ; 
         FIG. 7  is a top perspective view of the segment of the intermediate modular component shown in  FIG. 4A  with the underdrain floor side omitted; 
         FIG. 8A  is an elevational side view of a metering pipe of the intermediate modular component of  FIG. 4A ; 
         FIG. 8B  is a cross-sectional side view of the metering pipe taken across the line  8 B- 8 B shown in  FIG. 8A ; 
         FIG. 9  is a top perspective view of one embodiment of a segment of a terminating modular component for use in a modular underdrain system; 
         FIG. 10A  is a top perspective view of a segment of one embodiment of a starter strip for use in connection with a modular underdrain system; 
         FIG. 10B  is a side view of the segment of the starter strip shown in  FIG. 10A ; 
         FIG. 10C  is a front view of the segment of the starter strip shown in  FIG. 10A ; 
         FIG. 11A  is a side cross-sectional view of the filter cell shown in  FIG. 3  taken across a width dimension of the filter cell; 
         FIG. 11B  is an enlarged view of the region  11 B shown in  FIG. 11A ; 
         FIG. 11C  is an enlarged view of the region  11 C shown in  FIG. 11A ; 
         FIG. 11D  is an enlarged view of the region  11 D shown in  FIG. 11A ; 
         FIG. 12A  is a side cross-sectional view of the filter cell shown in  FIG. 3  taken across a length dimension of the filter cell; 
         FIG. 12B  is an enlarged view of the region  12 B shown in  FIG. 12A ; 
         FIG. 12C  is an enlarged view of the region  12 C shown in  FIG. 12A ; 
         FIG. 13A  is a top perspective view of one embodiment of a hold down member for use in a modular underdrain system; 
         FIG. 13B  is an elevational side view of the hold down member shown in  FIG. 13A ; 
         FIG. 14A  is a top perspective view of a segment of an alternative embodiment of an intermediate modular component; 
         FIG. 14B  is a top perspective view showing two segments of the alternative embodiment of the intermediate modular component of  FIG. 14A  shown in mating engagement; and 
         FIG. 15  is a partial cross-sectional view of one embodiment of a filter cell including two or more adjacently positioned intermediate modular components along a length dimension. 
     
    
    
     In accordance with common practice, the various features illustrated in the drawings may not be drawn to scale. Accordingly, the dimensions of the various features may be arbitrarily expanded or reduced for clarity. In addition, some of the drawings may be simplified for clarity. Thus, the drawings may not depict all of the components of a given apparatus (e.g., device) or method. Finally, like reference numerals may be used to denote like features throughout the specification and figures. 
     DETAILED DESCRIPTION 
     Various aspects of the present disclosure are described below. It should be apparent that the teachings herein may be embodied in a wide variety of forms and that any specific structure, function, or both disclosed herein is merely representative. Based on the teachings herein, one skilled in the art should appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways, even if that combination is not specifically illustrated in the figures. For example, an apparatus may be implemented, or a method may be practiced, using any number of the aspects set forth herein whether disclosed in connection with a method or an apparatus. Further, the disclosed apparatuses and methods may be practiced using structures or functionality known to one of skill in the art at the time this application was filed, although not specifically disclosed within the application. 
     By way of introduction, the following brief definitions are provided for various terms used in this application. Additional definitions will be provided in the context of the discussion of the figures herein. As used herein, “exemplary” can indicate an example, an implementation, and/or an aspect, and should not be construed as limiting or as indicating a preference or a preferred implementation. Further, it is to be appreciated that certain ordinal terms (e.g., “first” or “second”) can be provided for identification and ease of reference and may not necessarily imply physical characteristics or ordering. Therefore, as used herein, an ordinal term (e.g., “first,” “second,” “third”) used to modify an element, such as a structure, a component, an operation, etc., does not necessarily indicate priority or order of the element with respect to another element, but rather distinguishes the element from another element having a same name (but for use of the ordinal term). In addition, as used herein, indefinite articles (“a” and “an”) can indicate “one or more” rather than “one.” As used herein, a structure or operation that “comprises” or “includes” an element can include one or more other elements not explicitly recited. Thus, the terms “including,” “comprising,” “having,” and variations thereof signify “including but not limited to” unless expressly specified otherwise. Further, an operation performed “based on” a condition or event can also be performed based on one or more other conditions or events not explicitly recited. As used in this application, the terms “an embodiment,” “one embodiment,” “another embodiment,” or analogous language do not refer to a single variation of the disclosed subject matter; instead, this language refers to variations of the disclosed subject matter that can be applied and used with a number of different implementations of the disclosed subject matter. An enumerated listing of items does not imply that any or all of the items are mutually exclusive and/or mutually inclusive, unless expressly specified otherwise. 
     In the figures in the specification for this application, a reference numeral without a suffix (e.g., the suffix may comprise a lowercase letter or a hyphen followed by a number) may refer to one or more of a particular item, which may include a group of items. A reference numeral with a suffix comprising a hyphen followed by a number (e.g.,  110 - 1 ,  110 - 2 ,  110 - 3 , etc.) refers to a specific one of a group of items. In this case, the reference numeral without the suffix refers to all of the items in the group; when reference is made to a specific one of the items, a suffix comprising a hyphen followed by a number will be utilized. When multiple items in a group are present in a single figure, not all such items may be labeled with a reference numeral to avoid the undue proliferation of reference numerals on the figure. In addition, it should be noted that the general reference number (i.e., the reference number without a suffix) may be used in the figure and in the specification to refer to the items in the group or a reference numeral with the suffix may be used to refer to a specific item in the group. A reference numeral with a suffix comprising a lowercase letter (e.g.,  100   a ,  100   b ,  100   c , etc.) references an item that is a variation of the item bearing the reference numeral without the suffix (i.e., similar but not identical to the item bearing the reference numeral without the suffix). A suffix comprising a hyphen and a number and a suffix may be utilized together with the same reference numeral, when a specific instance of a variation is referenced. 
     For this application, the phrases “secured to,” “connected to,” “coupled to,” and “in communication with” refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, and thermal interaction and may also include integral formation. The phrase “attached to” refers to a form of mechanical coupling that restricts relative translation or rotation between the attached objects. The phrases “pivotally attached to” and “slidably attached to” refer to forms of mechanical coupling that permit relative rotation or relative translation, respectively, while restricting other relative motion. 
     The phrase “attached directly to” refers to a form of attachment by which the attached items are either in direct contact, or are only separated by a single fastener, adhesive, or other attachment mechanisms. The term “abut” refers to items that are in direct physical contact with each other, although the items may be attached, secured, fused, or welded together. The term “integrally formed” refers to a body that is manufactured integrally (i.e., as a single piece, without requiring the assembly of multiple pieces). Multiple parts may be integrally formed with each other if they are formed from a single workpiece. The term “offset” signifies that a center point of a first referenced object or feature and a center point of a second referenced object or feature are not aligned along one or more axes 
       FIG. 1  is a cross-sectional view of one embodiment of a portion of a filter cell  100 , including a modular underdrain system  112 , in an installed state and also in filtering state. The filter cell  100  comprises a depth dimension  116 , a length dimension  120 , and a width dimension  118 . It should be noted that the width dimension  118  of the filter cell  100  is not necessarily greater or smaller than the length dimension  120  of the filter cell  100 . 
     The illustrated filter cell  100  comprises a filter chamber  110  and an underdrain chamber  111  separated by the modular underdrain system  112 . A filtering water injection mechanism (illustrated subsequently) may be utilized to inject water  130  into the filter chamber  110  for filtration of the water  130  during a filtering state of the filter cell  100 . Also, an air injection mechanism (illustrated subsequently) may be utilized to inject air into the underdrain chamber  111  during a cleaning state of the filter cell  100 , which will be discussed in connection with  FIG. 2 . Also, a cleaning water injection mechanism (illustrated subsequently) may be utilized to inject water into the underdrain chamber  111  during a cleaning state of the filter cell  100 , which cleaning state will be discussed in connection with  FIG. 2 . 
     Referring still to  FIG. 1 , filter media  132  may be disposed within the filter chamber  110 . Particulate matter in the water  130  is captured by the filter media  132  during the filtering state, as water  130  flows in the manner indicated by the water flow arrows  130   a . In an alternative embodiment, other types of fluids, besides water  130 , may be filtered utilizing the filter cell  100 . 
     A plurality of intermediate modular components  140  of the modular underdrain system  112  are illustrated in  FIG. 1 . Each intermediate modular component  140  may comprise a modular component chamber  142 , a first peripheral side  144  and a second peripheral side  146 . One or more upper transfer orifices  156  and one or more lower transfer orifices  158  may be disposed in the first peripheral side  144  to enable fluid to flow through the transfer orifices  156 ,  158 . The transfer orifices  156 ,  158  enable the transfer of water  130  or another fluid, such as air, between the intermediate modular components  140  along the width dimension  118 . 
     Each first peripheral side  144  may comprise a first mating portion  150 , and each second peripheral side  146  may comprise a second mating portion  152 . The first mating portion  150  is shaped and sized to engage with a second mating portion  152  of an adjacent intermediate modular component  140 . The second mating portion  152  is shaped and sized to engage with a first mating portion  150  of an adjacent intermediate modular component  140 . A mating seal  153  may be positioned between the first mating portion  150  and the second mating portion  152  to form a media-tight seal under normal operating conditions of the filter cell  100 . The mating seal  153  may comprise, for example, a gasket, a sealant, caulking, or grout. As illustrated in  FIG. 1 , the first mating portion  150  may comprise a recess shaped to receive a protruding portion of the second mating portion  152 . Of course, in alternative embodiments, the first mating portion  150  may comprise a protrusion, and the second mating portion  152  may comprise a recess. In yet other alternative embodiments, each of the first and second mating portions  150 ,  152  may comprise, for example, a plurality of mating protrusions and recesses. 
     Normal operating conditions in the filter cell  100  range from −8 feet of water to +25 feet of water (−3.5 pounds per square inch (PSI) to 11 PSI). In various embodiments, vacuum pressure may be applied to the underdrain chamber  111  to induce water flow through the filter cell  100 . In alternative embodiments, no vacuum pressure is utilized, and water  130  may flow through the filter cell  100  solely based on the force of gravity or a pump. In various embodiments, one or more of vacuum pressure, a pump, and gravity may be utilized for directing water  130  through the filter cell  100 . 
     As used herein, the term “media-tight” with reference to a seal or a fit refers to a seal or a fit that is sufficiently tight to prevent the passage of filter media  132  through the seal or fit in normal operating conditions. Individual portions of Filter media  132  have a smallest dimension of 0.008 inches or greater. 
     Each first peripheral side  144  may comprise a foot  183 . A fastener  181  may be utilized to secure the foot  183  to a substrate  182 . 
     Each intermediate modular component  140  may comprise one or more metering pipes  170 . Each metering pipe  170  may comprise a distributor head  172  disposed within the modular component chamber  142 . The portion of each metering pipe  170  outside of the modular component chamber  142  may be referred to as the outside portion  171 , and may comprise one or more proximate orifices  176  and one or more remote orifices  178 . The one or more proximate orifices  176  are closer to the modular component chamber  142  than the remote end  173  of the metering pipe  170 , while the remote orifices  178  may be closer to the remote end  173  of the metering pipe  170 . A remote end orifice  178 - 1  at the remote end  173  comprises one of the one or more remote orifices  178  and may be disposed at the remote end  173  of the metering pipe  170 . 
     It should also be noted that one or more baffles  143  may be positioned within each modular component chamber  142 . The baffles  143  limit the flow of fluid (e.g., air  128  and water  130 ) between subchambers, separated by the baffles  143 , within the modular component chamber  142 . The baffles  143  aid in even distribution of the water  130  through the metering pipes  170  in a case where there are multiple metering pipes  170  in a single modular component chamber  142 , as will be illustrated subsequently. 
     In a filtering state of the filter cell  100 , injected water  130 , as indicated by the water flow arrows  130   a , flows through the filter chamber  110  (with particulate matter being captured by the filter media  132 ), passes into the modular component chamber  142  through slots (discussed subsequently), passes from the modular component chamber  142  into the distributor head  172  and through the metering pipe  170 , and exits from the metering pipe  170  via one or more of the proximate and remote orifices  176 ,  178 . Thus, the apertures in the distributor head  172 , the proximate and remote orifices  176 ,  178 , and the slots serve as a restriction to limit water flow through the filter cell  100 . Accordingly, the number and size of the orifices  176 ,  178 , apertures in the distributor head  172 , and the slots may be used to regulate water flow through the filter cell  100  to, for example, regulate the time in which the water  130  is disposed within the filter chamber  110 . 
       FIG. 2  is a cross-sectional view of the portion of the filter cell  100  of  FIG. 1  shown in an installed state and also in a media cleaning state. As indicated previously, the filter cell  100  comprises a depth dimension  116 , a width dimension  118 , and a length dimension  120 . 
     Periodically, it may be necessary to clean the filter media  132  as particulate matter accumulates on the filter media  132 . Thus, an air injection mechanism, illustrated subsequently, may be utilized to inject air  128  into the underdrain chamber  111 . A cleaning water injection mechanism, illustrated subsequently, may be utilized to inject water  130  into the underdrain chamber  111  during the cleaning state. Air  128  and water  130  may flow through one or more of the proximate and remote orifices  176 ,  178  (including the remote end orifice  178 - 1  at the remote end  173 ) of the metering pipes  170 . The mixture of air  128  and water  130  may then proceed generally along a depth dimension  116  through the metering pipes  170  and exit the distributor heads  172  into the modular component chamber  142 . Thereafter, the air  128  and water  130  may flow through slots (which will be illustrated subsequently) in the modular component chamber  142  and enter into the filter chamber  110 . The air  128  and water  130  striking the filter media  132  may serve to dislodge captured particulate matter. This flow pattern is illustrated with the airflow and water flow arrows  128   a ,  130   a  shown in  FIG. 2 . 
     Restricted flow caused by the size and positioning of the proximate and remote orifices  176 ,  178 , the openings in the distributor head  172 , and the slots in the modular component chamber  142  limit the flow of air  128  into the filter chamber  110 , thus resulting in an air blanket  180  disposed adjacent to the modular component chamber  142 . A mixture of air  128  and water  130  may occur, for example, below the air blanket  180 , within the filter chamber  110 , within the metering pipes  170 , and within the modular component chamber  142 . It should also be noted that the upper transfer orifices  156  facilitate the movement of air  128  between the intermediate modular components  140 , as illustrated in  FIG. 2 . Furthermore, the lower transfer orifices  158  enable water  130  to flow between the intermediate modular components  140  during the cleaning state. 
     In the case where there are multiple metering pipes  170  disposed within a modular component chamber  142 , baffles  143  within each modular component chamber  142  may be utilized to even the flow of air  128  through the slots into the filter chamber  110 . Without the baffles  143 , even distribution of the air  128  through the filter chamber  110  is difficult to achieve, for example, causing more air  128  to pass through one side of the modular underdrain system  112  such that only a portion of the filter media  132  may adequately be cleaned during the cleaning state. 
       FIG. 3  is a cross-sectional view of a larger portion of the filter cell  100  of  FIG. 1  shown without filter media  132 , water  130 , or air  128  disposed therein. The filter cell  100  and the modular underdrain system  112  in in  FIG. 3  are shown in an installed state. As indicated in  FIG. 3 , the modular underdrain system  112  comprises a plurality of intermediate modular components  140  each extending along a length dimension  120  of the filter cell  100 . As indicated previously, each intermediate modular component  140  may comprise, for example, one or more proximate and remote orifices  176 ,  178 , and one or more upper and lower transfer orifices,  156 ,  158 . 
     Each intermediate modular component  140  may also comprise an underdrain floor side  206 , in which are disposed a series of slots  210 . The slots  210  may be laser cut and must be sufficiently narrow such that the filter media  132  cannot pass through a slot  210 . The slots  210  will be discussed in additional detail subsequently. In various alternative embodiments, each slot  210  may comprise a series of circular openings, or openings of other shapes, again being sufficiently narrow to preclude the passage of filter media  132  through the slot  210 . The intermediate modular components  140  may be made, for example, of stainless steel. 
     The underdrain floor sides  206  of the intermediate modular components  140  define a substantially flat surface  96 . In various embodiments, substantially flat signifies that there are no apertures or gaps greater than 2 inches across each of the width and length dimensions  118 ,  120 , and no variation in the substantially flat surface greater than 2 inches along the depth dimension  116  of the filter cell  100 . 
     A first end seal  192  may be held in place by a hold down member  190 , which is secured by a plurality of hold down brackets  191 . At the opposite end of the intermediate modular components  140 , a second hold down bracket (not shown in  FIG. 3 ) may comprise a part of the modular underdrain system  112 . The first end seal  192  may form a media-tight seal adjacent to the hold down member  190 . The first end seal  192  may comprise, for example, grout or a gasket. Also, one embodiment of a starter strip  95  may be positioned on one side of the modular underdrain system  112 . The starter strip  95  will be explained in detail subsequently. 
     In addition, one embodiment of an air injection mechanism  103  is also illustrated. The air injection mechanism  103  comprises a main conduit  200  positioned within a flume  147  with risers  202  extending from the main conduit  200 . As noted previously, the air injection mechanism  103  injects air  128  into the filter cell  100  during a cleaning state. More specifically, the air injection mechanism  103  injects air  128  into the underdrain chamber  111 . It should be noted, once again, that the air injection mechanism  103  shown in  FIG. 3  is only illustrative, and air injection mechanisms of many types may be utilized in connection with the filter cell  100 . 
     One embodiment of a filtering water injection mechanism  102  for injecting water  130  to be filtered into the filter chamber  110  is also illustrated. The filtering water injection mechanism  102  may comprise a gravity and/or pump driven system for injecting water  130  into the filter chamber  110 . In addition, a vacuum system (not shown) may be positioned within the underdrain chamber  111  (or elsewhere) for drawing water  130  through the filter cell  100  or toward the underdrain chamber  111 . In an alternative embodiment, a filtering water injection mechanism may comprise one or more troughs (not shown) that may be filled by a set of one or more conduits, with the water spilling from the one or more troughs into the filter chamber  110 . 
     In addition, the filter cell  100  may also comprise a cleaning water injection mechanism  104 . The cleaning water injection mechanism  104  may comprise a gravity-driven and/or pump-driven mechanism for injecting water  128  into the underdrain chamber  111  in the cleaning state. In various embodiments, the cleaning water injection mechanism  104  delivers water into the flume  147 . In the embodiment illustrated in  FIG. 3 , the cleaning water injection mechanism  104  is disposed within or adjacent to the flume  147 . Because of the perspective of the view provided in  FIG. 3 , the cleaning water injection mechanism  104  is referenced but not visible in  FIG. 3 . One embodiment of the cleaning water injection mechanism  104  is, however, visible, for example, in  FIG. 11A . 
       FIGS. 4A-4E, 5A-5B, 6A-6B, and 7  depict various views of a segment (i.e., portion) of an intermediate modular component  140   a . The segment of the intermediate modular component  140   a  illustrated in  FIGS. 4A-4E and 5A-5B  comprises only a portion of the intermediate modular components  140  illustrated in  FIGS. 1-3 . The segment of the intermediate modular component  140   a  includes a depth dimension  116   a , a width dimension  118   a , and a length dimension  120   a . The segment of the intermediate modular component  140   a  is included in these figures in order to more clearly illustrate the components of the intermediate modular components  140 . In practice, an intermediate modular component  140  may be longer or shorter along the length dimension  120   a  than the intermediate modular components  140  or the segment of the intermediate modular components  140   a  illustrated in the figures. The illustrations provided serve only as examples and are not exhaustive of the proportions or dimensions of the intermediate modular components  140 . While the segment of the intermediate modular component  140   a  is discussed in connection with these figures, the discussion applies equally to an intermediate modular component  140 . 
       FIGS. 4A-4E and 5A-5B  will be discussed concurrently. The segment of the intermediate modular component  140   a  comprises a first peripheral side  144 , an underdrain floor side  206 , a second peripheral side  146 , an internal side  207  (sometimes referred to as an intermediate plate member  207 ), and one or more metering pipes  170 . The underdrain floor side  206  and the internal side  207  define a modular component chamber  142 . One or more baffles  143  may be positioned within the modular component chamber  142 . The baffles  143  may define a series of subchambers, which will be discussed subsequently. 
     As indicated previously, the first peripheral side  144  may comprise one or more upper transfer orifices  156  and one or more lower transfer orifices  158 . As indicated previously, the transfer orifices  156 ,  158  enable air  128  and water  130  to flow between segments of the intermediate modular components  140   a . The upper transfer orifices  156  are disposed closer to the modular component chamber  142  along the depth dimension  116   a  than the lower transfer orifices  158 . A relative position of the upper transfer orifices  156  and the lower transfer orifices  158  along the depth dimension  116   a  may be ascertained with reference to a center point of each transfer orifice  156 ,  158  (regardless of the size of each transfer orifice  156 ,  158 ) along the depth dimension  116   a . During the cleaning state when an air blanket  180  is present, the lower transfer orifices  158  may enable water  130  to move between segments of intermediate modular components  140   a , while the upper transfer orifices  156  enable air  128  to move between segments of intermediate modular components  140   a . The first peripheral side  144  may further comprise a first mating portion  150  for engaging with a second mating portion  152  of a segment of an adjacent intermediate modular component  140   a  or a terminating modular component (which will be explained subsequently). The first peripheral side  144  may include a foot  183  comprising openings  222  in which fasteners may be positioned to secure the intermediate modular component  140  to a substrate  182 . 
     The underdrain floor side  206  comprises a series of slots  210 . As indicated previously, the slots  210  may be arranged in various configurations other than the configuration shown in the figures. For example, the slots  210  may be arranged diagonally with respect to a length dimension  120   a  or extend along a length dimension  120   a  of the segment of the intermediate modular component  140   a . Also, each slot  210  may comprise a series of smaller openings, such as circular or square openings. As noted previously, the slots  210  must be sufficiently small to prevent passage of filter media  132  through the slots  210 , but allow water  130  and air  128  to pass through the slots  210 . In one embodiment the slots  210  have a width  229  of 0.007 inches plus or minus 0.001 inches. In applications in which either a gravel support bed or direct media is utilized within the filter chamber  110 , the slots  210  could be up to 0.125 inches in width  229 . Thus, the width  229  of the slots  210  may be affected by the type of filter media  132  employed within the filter cell  100 . 
     The internal side  207  may comprise one or more metering pipe openings  227 , in which a metering pipe  170  may be positioned. In one embodiment, the first peripheral side  144 , the underdrain floor side  206 , and the second peripheral side  146  may be integrally formed, while the internal side  207  may be separately formed. As illustrated, fasteners  220  may be used to secure the internal side  207  to the underdrain floor side  206 . A first lateral chamber seal  224  and a second lateral chamber seal  225  may be utilized to create a media-tight seal for the modular component chamber  142  (i.e., between the internal side  207  and the first peripheral side  144  and the second peripheral side  146 ). The fasteners  220  may also be employed to secure baffles  143  within the modular component chamber  142 . 
     The second peripheral side  146  comprises a second mating portion  152  for engaging with a first mating portion  150  of an adjacent segment of an intermediate modular component  140   a  or a starter strip  95 . As noted above, both the first and second mating portions  150 ,  152  may be configured in various ways to form a media-tight fit when used in connection with a mating seal  153 . It should be noted that the mating seal  153  may comprise a gasket, sealant, caulking, grout, or any other type of material capable of forming a media-tight seal. 
     As indicated previously, one or more metering pipes  170  may be positioned at least partially within the modular component chamber  142 . In particular, a distributor head  172  of each metering pipe  170  may be positioned within the modular component chamber  142 . The distributor head  172  may comprise, in various embodiments, a distributor head plate  242 , a plurality of fasteners  240 , and distributor head spacers  228 , which will be explained in greater detail hereafter. A locking nut  230  may be used to secure the distributor head  172  within the modular component chamber  142 . The metering pipe  170  may comprise a set of one or more proximate orifices  176  and a set of one or more remote orifices  178 . A center point of each of the proximate orifices  176  (along the depth dimension  116   a ) are positioned closer to the distributor head  172  (or the modular component chamber  142 ) than a remote end  173  of the metering pipe  170 . In contrast, a center point of each of the remote orifices  178  (again along the depth dimension  116   a ) is positioned closer to the remote end  173  of the metering pipe  170  than to the distributor head  172  (or the modular component chamber  142 ). As noted above, one of the remote orifices  178  comprises a remote end orifice  178 - 1  which is located at the remote end  173  of the metering pipe  170 . 
       FIGS. 6A, 6B, and 7  will be discussed concurrently. It should be noted that  FIG. 6A  is an elevational, cross-sectional view of the segment of the intermediate modular component  140   a  taken across the line  6 A- 6 A in  FIG. 4C ;  FIG. 6B  is an elevational, cross-sectional view of the segment of the intermediate modular component  140   a  taken across the line  6 B- 6 B in  FIG. 4C ; and  FIG. 7  is a top perspective view of the segment of the intermediate modular component  140   a  shown in  FIG. 4A  with the underdrain floor side  206  omitted to better illustrate subchambers. 
     As illustrated in these figures, the segment of the intermediate modular component  140   a  may comprise a first baffle  143 - 1  and a second baffle  143 - 2 , which divide the modular component chamber  142  into a first subchamber  145 - 1 , a second subchamber  145 - 2 , and a third subchamber  145 - 3 . It should be noted that the number of baffles  143  and subchambers  145  may be varied within the scope of the disclosed subject matter. 
     The baffles  143  limit the flow of fluid (e.g., water  130  and air  128 ) between the subchambers  145 . This limitation results in, for example, a more even distribution of air  128  during the cleaning state such that a large portion of the air proceeding up through an associated metering pipe  170  (through the distributor heads  172 ) will remain within the associated subchamber  145  and exit from the associated slots  210  within the subchamber  145 . In the absence of the baffles  143 , the air  128  may move to a side or portion of the filter cell  100 , resulting in uneven distribution of the cleaning effect of the air  128 . 
     Referring now to  FIGS. 8A-8B ,  FIG. 8A  is an elevational side view of a metering pipe of the intermediate modular component of  FIG. 4A , and  FIG. 8B  is a cross-sectional side view of the metering pipe taken across the line  8 B- 8 B shown in  FIG. 8A . Each metering pipe  170  may comprise an outside portion  171  (the portion of the metering pipe  170  outside of the modular component chamber  142  when attached thereto) and a distributor head  172 . The distributor head  172  comprises a distributor head plate  242 , an offset portion  243 , one or more fasteners  240  and one or more distributor head spacers  228 . The one or more fasteners  240  are used to secure the distributor head  172  to the offset portion  243 . One or more distributor head spacers  228  are positioned between the offset portion  243  and the distributor head plate  242  to define one or more lateral apertures  260  (between the distributor head spacers  228 ) through which air  128  and water  130  may pass into and out of the metering pipe  170 . The outside portion  171  may comprise one or more proximate orifices  176  and one or more remote orifices  178 . As noted, the remote end orifice  178 - 1  at the remote end  173  is one of the remote orifices  178 . As indicated previously, a locking nut  230  may be used to secure the metering pipe  170  to the internal side  207  at least partially within the modular component chamber  142 . 
     The metering pipe  170  may be embodied in various ways other than as shown in the figures. For example, the metering pipe  170  may be devoid of lateral apertures and may include one or more apertures on other positions on the metering pipe  170 , such as on the top of the metering pipe  170  (i.e., an opening on the end of the metering pipe  170  opposite the remote end  173 ). Also, the positioning, number and size of the proximate and remote orifices  176 ,  178  may be varied within the scope of the disclosed subject matter. 
       FIG. 9  is a top perspective view of one embodiment of a segment of a terminating modular component  140   b  for use in a modular underdrain system  112 . It should be noted that the term “segment” indicates that the segment of the terminating modular component  140   b  comprises only a portion of a terminating modular component. Thus, in practice, a terminating modular component may be longer or shorter than the illustrated segment of the terminating modular component  140   b , and may include, for example, different numbers of subchambers  145  and/or metering pipes  170 . Thus, while the segment of the terminating modular component  140   b , is discussed in connection with  FIG. 9 , the discussion applies equally to a terminating modular component. 
     The segment of the terminating modular component  140   b  is similar to the segment of the intermediate modular component  140   a  with the exception that transfer orifices  156 ,  158  are omitted from the segment of the terminating modular component  140   b . This is because the segment of the terminating modular component  140   b  is designed to be positioned at an outside edge of the modular underdrain system  112 . The transfer orifices  156 ,  158  are designed to enable air  128  and water  130  to transfer between adjacent modular components. As a result, the transfer orifices  156 ,  158  are omitted from the first peripheral side  144   a  of the segment of the terminating modular component  140   b . Beyond the absence of the transfer orifices  156 ,  158 , the segment of the terminating modular component  140   b  and the segment of the intermediate modular component  140   a  may otherwise be identical or similar in various embodiments. 
     The second mating portion  152  of the segment of the terminating modular component  140   b  is shaped and sized to engage with a first mating portion  150  of an adjacent segment of an intermediate modular component  140   a . The terminating modular component will be discussed further in connection with  FIGS. 11A and 11B . 
       FIGS. 10A-10C  comprise various views of a segment of one embodiment of a starter strip  95   a  for use in connection with a modular underdrain system  112  and will be discussed concurrently. It should be noted that the term “segment” indicates that the segment of the starter strip  95   a  comprises only a portion of a starter strip  95 . Thus, in practice, a starter strip  95  may be longer or shorter than the illustrated segment of the starter strip  95   a . Thus, while the segment of the starter strip  95   a  is discussed in connection with these figures, the discussion applies equally to a starter strip  95 . 
     The illustrated segment of a starter strip  95   a  comprises a wall mounting plate  288  including one or more openings  289  for receiving fasteners to secure the segment of the starter strip  95   a  to a wall of a filter cell  100 . The segment of the starter strip  95   a  may also comprise a first mating portion  150  for engaging with a second mating portion  152  of a segment of an adjacent intermediate modular component  140   a . The segment of the starter strip  95   a  may also comprise a foot  284  having openings  286  for receiving fasteners for securing the segment of the starter strip  95   a  to a substrate  182  of a filter cell  100 . 
     The segment of the starter strip  95   a  may be embodied in various ways other than as illustrated in the figures. For example, the first mating portion  150  of the segment of the starter strip  95   a  may comprise a protruding portion rather than a recessed portion. 
       FIGS. 11A-11D  comprise various cross-sectional views of the filter cell  100  shown in  FIG. 3  taken across a width dimension  118  of the filter cell  100  and will be discussed concurrently. As indicated previously, the filter cell  100  may comprise a depth dimension  116 , a width dimension  118 , and a length dimension  120 . The filter cell  100  and the modular underdrain system  112  in  FIGS. 11A-11D  are shown in an installed state. The filter cell  100  in these figures is shown devoid of air  128 , water  130 , and filter media  132 . 
     As illustrated, the filter cell  100  may comprise a modular underdrain system  112 . The modular underdrain system  112  may comprise a filtering water injection mechanism  102  an air injection mechanism  103  and a cleaning water injection mechanism  104 . The filtering water injection mechanism  102  may include a pump, a vacuum, and/or gravity driven mechanisms for injecting water  130  into the filter cell  100 . The cleaning water injection mechanism  104  may comprise a pump or gravity driven mechanism for injecting water  128  into the underdrain chamber  111  in the clean date. 
     An embodiment of the air injection mechanism  103  comprising a main conduit  200  and a plurality of risers  202  disposed within a flume  147  is also illustrated. The risers  202  distribute air  128  throughout the modular underdrain system  112  when the filter cell  100  is in a cleaning state. 
     A hold down member  190  and one or more hold down brackets  191  are also illustrated. The hold down member  190  and one or more hold down brackets  191  limit movement of an underlying seal along a depth dimension  118 , as will be illustrated and explained in connection with  FIGS. 12A-12B . The illustrated hold down brackets  191  and hold down member  190  merely comprise illustrative embodiments of potential designs for these components. The hold down member  190  will be discussed subsequently in additional detail. 
     The modular underdrain system  112  may comprise a starter strip  95  and a plurality of modular components, such as a first intermediate modular component  140 - 1 , an adjacent intermediate modular component  140 - 3 , a second intermediate modular component  140 - 2 , a last intermediate modular component  140 - 4 , and a terminating modular component  140   c . A first mating portion  150 - 1  of the starter strip  95  is shown in engagement with a second mating portion  152 - 1  of the first intermediate modular component  140 - 1  with an inter-positioned first mating seal  153 - 1 . A first mating portion  150 - 2  of the adjacent intermediate modular component  140 - 3  is engaged with a second mating portion  152 - 2  of the second intermediate modular component  140 - 2  with an inter-positioned second mating seal  153 - 2 . A first mating portion  150 - 3  of the last intermediate modular component  140 - 4  is engaged with a second mating portion  152 - 3  of the terminating modular component  140   b  with an inter-positioned third mating seal  153 - 3 . 
     A peripheral side  144 - 3  of the terminating modular component  140   b  is in a media-tight engagement with a terminating seal  300 . The terminating seal  300  may comprise, for example, grout or another mechanism for creating a media-tight seal with the peripheral side  144 - 3  of the terminating modular component  140   b . The terminating seal  300  may also provide support to the peripheral side  144 - 3  of the terminating modular component  140   b  to counterbalance fluid pressure applied to the peripheral side  144 - 3  of the terminating modular component  140   b  when in operation. 
     Referring now to the second intermediate modular component  140 - 2 , which is illustrated specifically in  FIG. 11C . In this figure, an underdrain chamber cross-sectional area  310  and a modular component chamber cross-sectional area  312  are illustrated. The underdrain chamber cross-sectional area  310  is bounded by the internal side  207 - 1 , the first peripheral side  144 - 2  of the second intermediate modular component  140 - 2 , the substrate  182  to which the first peripheral side  144 - 2  is attached, the second peripheral side  146 - 1  of the second intermediate modular component  140 - 2 , and a first peripheral side  144 - 1  of the adjacent intermediate modular component  140 - 3 . The modular component chamber cross-sectional area  312  is the cross-sectional area of the modular component chamber  142  of the second intermediate modular component  140 - 2 . In various embodiments, the modular component chamber cross-sectional area  312  is 6% to 25% of the underdrain chamber cross-sectional area  310 . When the intermediate modular component  140  is configured in this manner, improved air and water flow patterns are achieved during both the filtering state and the cleaning state. 
       FIGS. 12A-12C  comprise various cross-sectional views of the filter cell  100  shown in  FIG. 3  taken across a length dimension  120  of the filter cell  100 . More specifically, the cross-sectional view is taken across the second intermediate modular component  140 - 2  of the modular underdrain system  112 . As discussed previously, the filter cell  100  comprises a depth dimension  116 , a width dimension  118 , and a length dimension  120 . The filter cell  100  and the modular underdrain system  112  in  FIGS. 12A-12C  are shown in an installed state. 
     In these figures, a wall mounting plate  288  of a starter strip  95  is illustrated. In addition, one embodiment of an air injection mechanism  103  at least partially positioned within a flume  147  is also illustrated. One embodiment of a filtering water injection mechanism  102  is also illustrated. 
     A first end seal  192 - 1  and a first end pipe  320 - 1  are positioned at one end of the modular underdrain system  112 , and a second end seal  192 - 2  and a second end pipe  320 - 2  at an opposite end of the modular underdrain system  112  along the length dimension  120 . The first end seal  192 - 1  and second end seal  192 - 2  may be formed of grout, gasket or any other mechanism capable of forming a media-tight seal with the starter strip  95 , intermediate modular components  140  and the previously illustrated terminating modular component  140   c . The first end pipe  320 - 1  and the second end pipe  320 - 2  comprise conduits that may serve as spacers that mitigate displacement of the first end seal  192 - 1  and the second end seal  192 - 2  along a depth dimension  116 . The first end seal  192 - 1  and the first end pipe  320 - 1  are held in place by a first hold down member  190 - 1  and a set of one or more first hold down brackets  191 - 1 . The second end seal  192 - 2  and the second end pipe  320 - 2  are held in place by a second hold down member  190 - 2  and a set of one or more second hold down brackets  191 - 2 . 
       FIGS. 13A-13B  comprise various views of one embodiment of a hold down member  190  for use in a modular underdrain system  112 . As illustrated, the hold down member  190  has an L-shaped side profile. In alternative embodiments, for example, the hold down member  190  may have a U-shaped, an I-shaped, a rectangular-shaped, or a square-shaped side profile. 
       FIG. 14A  is a top perspective view of a segment of an alternative embodiment of an intermediate modular component  140   d . As indicated previously, the term “segment” indicates that only a portion along a length dimension of the alternative embodiment of the intermediate modular component  140   d  is illustrated. In practice, the alternative embodiment of the intermediate modular component may be shorter or greater along a length dimension than the illustrated segment of the alternative embodiment of the intermediate modular component  140   d . The illustrated alternative embodiment includes a different version of a first mating portion  150   a  and a second mating portion  152   a . The first mating portion  150   a  may comprise an engaging slot shaped, sized, and positioned for engagement with the second mating portion  152   a , which may comprise a tang. 
       FIG. 14B  is a top perspective view showing two segments of the alternative embodiment of the intermediate modular component  140   d - 1 ,  140   d - 2  of  FIG. 14A  shown in engagement. As illustrated, a second mating portion  152   a  of a segment of the first intermediate modular component  140   d - 1  is shown engaged with a first mating portion  150   a  of a segment of the second intermediate modular component  140   d - 2 . In addition, a mating seal  153  is positioned between the segment of the first intermediate modular component  140   d - 1  and the segment of the second intermediate modular component  140   d - 2 . In alternative embodiments, the mating seal  153  may be located at different positions, such as on one side of the second mating portion  152   a  and adjacent to the first mating portion  150   a . Also, it should be noted that in connection with all embodiments, multiple mating seals may be used for a first mating portion and a second mating portion. As indicated previously, the first mating portion and second mating portion may be configured in various ways to enable mutual engagement. 
       FIG. 15  is a partial cross-sectional view of one embodiment of a filter cell  100   a  including an alternative embodiment of a modular underdrain system  112   b . As indicated previously, a filter cell  100   a  may comprise a depth dimension  116 , a width dimension  118  and a length dimension  120 . The illustrated modular underdrain system  112   b  may include two or more adjacently positioned intermediate modular components  140   e - h  along a length dimension  120 . Further, the illustrated filter cell  100   a  also includes first and second offset seams  404 ,  406 . In particular, a first intermediate modular component  140   e  is positioned adjacent to a second intermediate modular component  140   f  at a first offset seam  404 . A third intermediate modular component  140   g  is positioned adjacent to a fourth intermediate modular component  140   h  at a second offset seam  406 . The first and second offset seams  404 ,  406  are offset along the length dimension  120  of the filter cell  100 . 
     In addition to the first hold down member  190 - 1  and the first hold down bracket  191 - 1 , the modular underdrain system  112   b  includes a first seam hold down member  193 - 1  positioned over the first offset seam  404  (with at least one second hold down bracket  191 - 2  for retaining the first seam hold down member  193 - 1  in position), and a second seam hold down member  190   b  positioned over the second offset seam  406  (with at least one third hold down bracket  191 - 3  for retaining the second seam hold down member  193 - 2  in position). In addition, a first hold down seal  400  may be interposed between the first seam hold down member  193 - 1  and the first offset seam  404 , and a second hold down seal  402  may be interposed between the second seam hold down member  193 - 2  and a second offset seam  406  to prevent or mitigate leakage through the seams  404 ,  406 . 
     It should be noted that the position of offset seams  404 ,  406  may alternate in consecutive modular components along the width dimension  118  between a seam disposed underneath the first seam hold down member  193 - 1  and the second seam hold down member  193 - 2 . In alternative embodiments, all of the seams are disposed underneath a single hold down member  193 - 1 , obviating the need for a second seam hold down member  193 - 2 . 
     Also, additional hold down brackets may be employed at opposing ends of the first seam hold down member  193 - 1  and the second seam hold down member  193 - 2 , which are not visible in this figure. In addition, fasteners (not shown) with one or more fastener seals or caulking may be utilized to maintain the first seam hold down member  193 - 1  and the second seam hold down member  193 - 2  in place. 
     The foregoing disclosure and associated figures provide only examples of the disclosed and claimed subject matter. Limitations associated with the description and figures are not to be imputed to the claims. For example, in various alternative embodiments, the first peripheral side  144  and the second peripheral side portion  146  are equal in length along the depth dimension  116   a . In yet other alternative embodiments, the second peripheral side  144  is greater in length than the first peripheral side  146  along the depth dimension  116   a . In addition, a modular component  140 ,  140   a - h  may comprise one or multiple metering pipes. Also, each of the one or more upper transfer orifices  156 , lower transfer orifices  158 , proximal orifices  176 , and remote orifices  178  may have various shapes, such as circular, elongated, round, in the shape of a slot, elliptical, octagonal, square, or rectangular. In various embodiments, the modular component chamber  142  is sealed such that fluid (e.g., air  128  and/or water  130 ) may enter and exit the modular component chamber  142  only through the slots  210  and through the metering pipe  170  during normal operating conditions of the modular underdrain system  112  when the modular underdrain system  112  is in an installed state. As used herein, a “modular component,” in singular or plural form, encompasses at least intermediate modular components  140 ,  140   a - h , starter strips  95 , and terminating modular components  140   c . Thus, an “adjacent modular component,” in singular or plural form, encompasses at least an adjacent intermediate modular component  140 ,  140   a - h , an adjacent starter strip  95 , and an adjacent terminating modular component  140   c.    
     The previous description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the disclosure. Thus, the present disclosure is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed.