WO2007021715A2

WO2007021715A2 - Arch-shaped corrugated leaching chamber

Info

Publication number: WO2007021715A2
Application number: PCT/US2006/030978
Authority: WO
Inventors: James B. Goddard; Stephen R. Helmrich; Terry M. Birchler
Original assignee: Advanced Drainage Systems, Inc.
Priority date: 2005-08-10
Filing date: 2006-08-04
Publication date: 2007-02-22
Also published as: US20070081860A1; US20070077122A1; WO2007021715A3; WO2007021715A9

Abstract

A flexible arch-shaped corrugated structure includes a plastic structure (1) that can be light weight and easy to handle, while at the same time having suitable strength for carrying loads. By suitably engineering the corrugations (40, 50), the need for structural ribs can be eliminated and thinner sidewalls can be used. The structure can include a series of vertically-oriented arched corrugations having surfaces that convexly arch or curve upwardly as well as laterally. Having both upward and lateral arched or curved features on the corrugations can provide increased strength to the corrugations and the structure. In a particular embodiment, the plastic structure is a leaching chamber. The structure can include access or inspection port structures (60) disposed at the ends of the structure. In one embodiment, the ports are dimensioned to mate with the opposing port of a like structure. In particular, the mated structures can articulate or rotate about the mated ports.

Description

FLEXIBLE ARCH-SHAPED CORRUGATED STRUCTURE

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 60/707,490, filed on August 10, 2005 (Attorney Docket No. 1652.2004-00O)₅ the teachings of which are incorporated herein by reference in its entirety.

BACKGROUND

Arch-shaped corrugated structures are useful for various applications, particularly where the structure is exposed to load forces. A typical application is a leaching chamber that can fabricated from a thermoplastic, such as high density polyethylene (HDPE). The leaching chamber is typically injection molded into its shape. Plastic leaching chambers are typically connected together in a series or an array and buried in a leaching field for dispersing waste water, sewage effluent, or storm water into the ground. The buried leaching chamber must resist loads from the overhead soil and possibly vehicular traffic.

Prior art leaching chambers are typically rigid structures. Thick sidewalls, plastic structural ribs, and other features, are generally used to increase the strength of the leaching chambers. That rigidity can cause the leaching chambers to fail prematurely. Indeed, many prior art chambers break during shipment or transport to the installation site, and during installation itself.

Leaching chambers are generally installed in accordance with state and local laws and regulations, as well as local customs. In particular, those laws, regulations, and customs dictate the width of the leaching field trench, and thus limit the width of the leaching chamber, generally to either 36 inches, 24 inches, or 18 inches. Most leaching chambers are between about five to six feet in length to be dimensioned and light enough for an individual worker to handle.

SUMMARY

Particular embodiments of a flexible arch-shaped corrugated structure include a plastic structure that can be light weight and easy to handle, while at the same time having suitable strength for carrying loads. In a particular embodiment, the plastic structure is a leaching chamber.

Prior art plastic leaching chambers have relied on thick sidewalls and structural ribs to strength the structure. The ribs, however, can place portions of the structure under tension when loaded and have been found to introduce failure points into the structure. Failures at those points tend to crack and propagate through the structure's wall to tear the structure. Based on the locations of prior art ribbing, those failures tend to occur at the sidewalls. Weight reductions can be realized by reducing the amount of structural ribs and decreasing the wall thickness. However, those weight-saving measures can decrease the strength of the leaching chamber.

By suitably engineering the corrugations, the need for structural ribs can be eliminated and thinner sidewalls can be used. Once installed, the flexible structure is strong but light. The resulting structure will flex before failing. When loaded, the structure is under compression. When failure does occur, the structure will fail at the crest of the corrugations by buckling, not at the sidewalls. In addition to flexing before failing, a flexible structure is better able to cover uneven ground.

Aspects of the invention include a structure having a base with an open bottom. The structure can be a chamber, and more particularly an arch-shaped leaching chamber. Also included are methods of fabricating the structure, such as by injection molding. The structure can include a plurality of alternating corrugations running along the structure's body, with each corrugation being arch shaped about a center longitudinal axis with the bottom of the arch being at the base and the crest of the arch being perpendicular to the base. Furthermore, the corrugations can include a peak corrugation having a radius when sectioned through the center longitudinal axis, with the radius varying along the arch from the base to the crest of the arch.

The structure can include a series of vertically-oriented arched corrugations having surfaces that convexly arch or curve upwardly as well as laterally. Having both upward and lateral arched or curved features on the corrugations can provide increased strength to the corrugations and the leaching chamber. In particular embodiments, the radius is larger at the base than at the peak of the arch.

The larger corrugation portion at the bottom can provide greater strength for resisting backfill. More particularly, the radius of the sectioned peak corrugation can be continuously variable along the arch from the base to the peak. The radius blends into the side walls of the corrugations, which can be slightly angled for strength purposes. e structure s corrugat ons can e fabricated from p astic. In particular, the corrugations can have a wall thickness of less than about 0.1 inches and are not connected with structural ribs. The wall thickness can further be relatively uniform, with the variation in thickness being less than 10%. The peak corrugations can include openings to facilitate the flow of a flowable medium, such as air, storm water, or sewage effluent between the inside of the structure and the outside of the structure. The peak corrugations can further include louvers to define the openings and to inhibit the intrusion of external material, such as soil, into the structure. The louvers can, in particular, be formed as protrusions on the peak corrugations. The louvers can include louvers with louver members that laterally extend across the laterally curving surfaces of the corrugations, resulting in laterally oriented arched louver members. In particular, the louvers can be formed to include a frame structure formed on the peak corrugations, the louvers being within the frame structure. The lateral arch of the louver members on the laterally curving surfaces of the corrugations can also have increased strength for resisting the lateral thrust of backfill and can have increased leaching surface area, in comparison to louvers that are merely straight.

The corrugations can include valley corrugations or troughs between adjacent peak corrugations. Each valley corrugation can also have a plurality of formed louvers defining openings along a portion of the valley corrugations. In addition, a plurality of the valley corrugations can include a pair of stacking features. Each stacking feature can include a stacking column extending vertically downward from the valley corrugation and a stacking pocket above the valley corrugation and vertically aligned with the stacking column. The stacking feature can further include a rail transitioning the stacking pocket to the top of the valley corrugation. The structure (in particular a leaching chamber) can further include at least one inspection port formed in the body. In one embodiment, the inspection port can be disposed at the crest of a valley corrugation.

The ends of the structure can include end flanges that can be overlapped and locked with end flanges on adjacent leaching chambers. The end flanges can be generally arched shaped in a vertical orientation. One end flange on a chamber can include an upwardly extending post, and the opposite end flange can include a mating downwardly facing socket for providing pivotal engagement between adjacent leaching chambers. The side walls of the end flanges can have a curved or tapered contour to allow the end flanges to slide over each other during lateral pivoting of the leaching chambers relative to each other. In some embodiments, the end flanges can have a curved contour forming a dome like structure, resulting in a post and dome locking feature.

The mating ends of the chambers can include access or inspection ports, which can be circular in shape and function as post and dome structures disposed at the crests of the ends. That is, mated leaching chambers can articulate or rotatably pivot about the inspection port structures within a fixed range of angles. By positioning the inspection ports at the ends of the leaching chamber, a potential structural weakness at the corrugations can be removed and disposed at the end joint that can be stiffened through overlapping.

A plurality of arch-shaped structures can be joined into a series or an array of structures. In particular, leaching chambers can be joined together to form a leaching field.

A particular leaching field can include a first leaching chamber and a second leaching chamber, which may be alike. Each leaching chamber can have like end flanges, the end flanges including a first end flange having a first inspection port structure and a second end flange having a second inspection port structure. The first leaching chamber is mated with the second leaching chamber such that the first inspection port structure of the first leaching chamber overlaps the second inspection port structure of the second leaching chamber. At a particular joint, the first inspection port structure and the second inspection port structure are opened to allow access to the interior of the leaching field.

In addition, the longitudinal axis of the first chamber can be at an angle relative to the longitudinal axis of the second chamber. More specifically, the first and second leaching chambers can rotational pivot about the mated inspection port structures.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features, and advantages of the invention, including various novel details of construction and construction of parts, will be apparent from the following more particular drawings and description of embodiments, in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. It will be understood that the particular details embodying the invention are shown by way of illustration only and not as a limitation of the invention. The principles and features of this invention may be employed and varied in numerous embodiments without departing from the scope of the invention.

FIG. 1 is a perspective view of a particular leaching chamber.

FIG. 2 is a top view of the leaching chamber of FIG. 1. FIG. 3 is a first end view of the leaching chamber 1 of FIG. 1.

FIG. 4 is a right side view of the leaching chamber 1 of FIG. 1.

FIG. 5 is a second end view of the leaching chamber 1 of FIG. 1.

FIGS. 6A-6B illustrate the interconnection of adjacent leaching chambers of FIG 1. FIG. 7 is a cross-sectional view along line A-A of FIG. 4.

FIG. 8 is a foreshortened cross-sectional view along line B-B of FIG. 4.

FIG. 9 A is a load/defection curve for a commercial embodiment of the leaching chamber of FIGs. 1-8.

FIG. 9B is a load/defection curve for a competitor's commercially-available Quick 4 leaching chamber.

FIG. 10 is a perspective view of a leaching chamber having inspection port ends.

FIG. 11 is a side view of the leaching chamber 100 of FIG. 10.

FIG. 12 is a top view of the leaching chamber 100 of FIG. 10.

FIGS. 13A-13B illustrate the interconnection of adjacent leaching chambers of FIG 10.

FIG. 14 is a cross-sectional diagram of nested chambers taken along line C-C in a valley corrugation of FIG. 4.

DETAILED DESCRIPTION In a particular embodiment of the invention, the flexible arch-shaped corrugated structure is a plastic leaching chamber, which has an open bottom and louvered opening side walls for dispersing effluent from inside the structure to the ground. Leaching chambers can also be used to disperse storm water. Similar structures can be used in other applications as well, including grain aeration and fish channels. In other application, the side walls may not have louvered openings, such as in culverts.

FIG. 1 is a perspective view of a particular leaching chamber. The leaching chamber 1 has an open bottom and is generally arch shaped with a center axis 5. The chamber has a total length TL, a width W, and a height H. The leaching chamber 1 includes a first end flange 10 at a first end and a second end flange 20 at a second end. The first and second end flanges 10, 20 are complementary so that the first end flange 10 of one chamber can mate with the second end flange 20 of an adjacent chamber to form a serial chain of chambers for a leaching field as understood by those of ordinary skill in the art.

In particular, the ends of the leaching chamber can include end flanges that can be overlapped and locked with end flanges on adjacent leaching chambers. The end flanges 10, 20 are generally arched shaped in a vertical orientation. As shown, the end flanges 10, 20 feature a post and dome interconnect, which is described in more detail in U.S. Design Patent Nos. 403,047, issued on December 22, 1998 to Gray, the teaching of which are incorporated herein by reference. A post structure 12 is located at the crest of the first end flange 10 and a dome structure 22 is located at the crest of the second end flange 20. Thus, the second end flange 20 overlaps the first end flange 10 of adjacent chambers. The first end flange 10 also includes latching grooves 14 and the second end flange 20 includes a lip structure 24.

A base flange 30 acts as feet for the leaching chamber 1. When installed, the base flange is set on the surface of a prepared trench. An elevated flange 32 is fabricated on the base flange 30 adjacent to the first (overlapped) end flange 10. When two like chambers are mated, the base flange 30 adjacent to the second (overlapping) end flange 20 is received in the gap under the elevated flange 32.

The leaching chamber 1 also includes a plurality of alternating peak corrugations 40 and valley corrugations or troughs 50 along its length. The corrugations 40, 50 include respective sidewalls 45, 55 with opening louver features 140 having a height h for dispersing effluent or storm water from inside the chamber 1. The distal louvered corrugations are connected to the respective end flanges 10, 20 via a first end transition corrugation 15 and a second end transition corrugation (not shown).

The louver features 140 are formed onto and follow the profile of the corrugations 40, 50. In particular the amount of material absent from the corrugation sidewalls due to the louver slots is replaced by a structural louver frame. In contrast, prior art louvers are generally formed by simply perforating the sidewall, which introduces a structural weakness in the corrugations.

Also shown is an inspection port 60 located at the crest of a valley corrugation. When a leaching field is installed, selected inspection ports 60 can be cut out for later access. It should be understood that the number and position of access ports can be a design choice.

FIG. 2 is a top view of the leaching chamber 1 of FIG. 1. The laying length LL of the chamber is defined as the longitudinal distance between the centers of the post structure 12 and the dome structure 22. This view better illustrates the first end transition corrugation 15 and the second end transition corrugation 25. Also note that the corrugations do not have a fixed contour. Also note that there is no external ribbing between corrugations, as is frequently used in prior art leaching chambers. Internal ribbing between corrugations is also not used. lhis view also illustrates tabs 34 on the second end of the base flange 30. As will be illustrated below, the structure of the ends permits interconnected chambers to articulate or swivel a through a small angle so that a series of interconnected chambers can follow a nonlinear path. Other swivel connectors can also be used, such as those described in U.S. Patent No. 6,592,293 to Gray, U.S. Patent No. 6,592,293 to Hedstrom et al. and in co-pending U.S. Application No. 10/619,060 by Hedstrom et al., the teachings of which are incorporated herein by reference in their entirety. Of course, non-swivel connecting joints can also be employed.

The latching grooves 14 on the first end flange 10 and the lip 24 on the second end flange 20 are used to connect end caps to terminate a series of chambers.

FIG. 3 is a first end view of the leaching chamber 1 of FIG. 1. In addition to illustrating the arch shape along the center line 5 and the post connector structure 12, details of the peak corrugation louvers 140 are shown. Note that the louvers 140 include louver members 142a, 142b, ..., 142y, 142z. Those louver members protrude from the corrugation side wall.

FIG. 4 is a right side view of the leaching chamber 1 of FIG. 1. This view further illustrates the contours of the corrugations and details of the ends.

As shown, the leaching chamber 1 includes a series of vertically-oriented arched corrugations having surfaces that convexly arch or curve upwardly as well as laterally. The side walls of the leaching chamber between the corrugations can include louvers for allowing the passage of liquids from the leaching chamber. In addition, the corrugations can also include louvers with louver members that laterally extend across the laterally curving surfaces of the corrugations, resulting in laterally oriented arched louver members.

Having both upward and lateral arched or curved features on the corrugations can provide increased strength to the corrugations and the leaching chamber. The corrugations can have sidewalls having flat surfaces. The lateral arch of the louver members on the laterally curving surfaces of the corrugations can also have increased strength for resisting the lateral thrust of backfill and can have increased leaching surface area, in comparison to louvers that are merely straight. FIG. 5 is a second end view of the leaching chamber 1 of FIG. 1. In addition to illustrating the arch shape along the center line 5 and the dome connector structure 22, details of the peak corrugation louvers 140 are shown. As shown in FIG. 3, the louvers 140 include louver members 142a, 142b, ..., 142y, 142z. Again, those louver members protrude from the corrugation side wall. FIGS. 6A-6B illustrate the interconnection of adjacent leaching chambers of FIG. 1. As shown a first chamber IA and a second chamber IB interconnect by overlapping end flanges. As shown in FIG. 6 A, the first chamber IA is installed in place with its first end flanges 1OA exposed. The second chamber IB is installed by placing its second end flange 2OB over the first end flange 1OA of the first chamber IB, with the dome structure 22B aligned over the post structure (not shown) of the first chamber IA. Note that the second chamber IB is elevated at a vertical angle.

As shown in FIG. 6B, the interconnection is completed by tilting the second chamber IB down so that the second chamber base flange 3OB is received under the elevated flange 32 A of the first chamber IA. Note that the joint, particularly the gap below the elevated flange 32 A, allows for articulated movement of the connected chambers. Latches or other suitable engageable structures on the ends of the leaching chambers can be used to help hold the mated chambers together.

Although two like leaching chambers IA, IB are shown being mated, other structures can also be mated with a leaching chamber. For example, one or more angle couplers, similar to those described in the above-referenced U.S. Patent No. 6,592,293 to Hedstrom et al., can be serially attached to a leaching chamber.

FIG. 7 is a cross-sectional view along line A-A of FIG. 4. This illustrates a typical peak corrugation louver structure 140 and valley corrugation louver structure 52 of FIG.1. Referring to the peak corrugation louver structure 140, a base louver 142a transitions into the base flange 30 and a top louver 142z extends from the main corrugation sidewall. Between the base louver 142a and the top louver 142z are a plurality of interior louvers, of which the two adjacent to the base louver 142a and the top louver 142z are shown. The louvers 140 are designed to allow flow of effluent or storm water from within the chamber and to inhibit backfill from entering the chamber.

The first louver 142a and the interior louvers 142b, 142y includes a respective lip 144a, 144b, 144y along the inside of their top surfaces 146a, 146b, 146y. The top louver surfaces 146 run parallel to the base flange 30. The lips 144 extend above the top louver surface 146 by a first distance dl and are separated from the next louver by a second distance d2.

The bottom surfaces 48 of the interior louvers 142b, 142y and the top louver 142z run at an angle Θl relative to the adjacent top louver surfaces 146a, 146y. The bottom surfaces 148 are thus separated from the prior louver top surface 146 by a third distance d3. The interior louvers have an inside height of d4, including the lip, and an outside height of d5. As sήown, the louvers have an inside-to-outside width d6, which is greater than the thickness of the side wall.

In a specific embodiment, the chamber wall thickness is nominally 0.10 inches. For the louvers, dl is 0.030 inches, d2 is 0.110 inches, d3 is 0.152 inches, d4 is 0.130 inches, d5 is 0.083 inches, d6 is 0.250 inches (including the sidewall thickness) when measured perpendicular to the arch, and Θl is 4.0 degrees. Other dimensions can be substituted to meet other engineering requirements. For example, although the louver surfaces is offset and extends from the corrugation side walls by about 0.15 inches, other approaches to the infiltration structures could be used. FIG. 8 is a foreshortened cross-sectional view along line B-B of FIG. 4. The view shows a representative horizontal cross-section of a peak and valley corrugation.

The particular arc of the peak corrugation 40 is continuously variable from the bottom of the corrugation to the crest. The peak corrugation is, in particular, a linear blended surface between the horizontal plane (at the base flange 30) and the vertical plane (at the crest of the chamber arch). More specifically, the arc is only measurable as a radius (but still variable) if the corrugation is sectioned perpendicular to the chamber's arch. In the illustrated view, the curve is an incidental ellipse. Also, when sectioned horizontally as shown, the thickness of the louvers is variable. If a cross-section were taken perpendicular to the chamber arch (i.e. passing through the center axis 5 (FIG. I)), then the louver thickness would be equal to άβ (FIG. 7).

The laterally curving surfaces of the corrugations has a radius that becomes smaller with an increase in elevation, starting at the bottom on a lateral plane and ending at the top on a vertical plane. That change in dimensions results in corrugations having portions that are larger at the bottom and smaller at the top. The larger corrugation portion at the bottom can provide greater strength for resisting backfill. The radius blends into the side walls of the corrugations, which can be slightly angled for strength purposes. Again, note that the louvers protruded from the corrugations.

Particular chambers can have a peak corrugation profile that is similar to a successful pipe profile disclosed on U.S. Patent No. 6,644,357 to Goddard, the teachings of which are incorporated herein by reference. Unlike a pipe, however, the chamber does not require a fixed diameter. Instead, the particular peak corrugations have an arch-shape that is larger in diameter at the base than at the crest.

As shown in FIG. 8, the peak corrugations 40 and the valley corrugations 50 have respective louvered opening features 140, 150. Note that the louver features is a formed feature that follows the contour of the corrugations. This shaping of the louvers increases the amount of open area provided at the corrugations.

At the peak corrugation 40, the louver feature 140 includes a protruding frame 148 and center support member 149. In particular, the approximate amount of sidewall material removed to form the open areas between the louvers in the peak corrugation is replaced by material in the frame 148 and center support 149. The valley corrugations 50 have similar louver features 150. Although the valley corrugations 50 have center supports 159, outer support is provided by the sidewall itself 158. Also shown is a brace 157 for base of the valley louver center support 159. In a particular embodiment, the frame 148 and center supports 149, 159 have a thickness equal to the thickness of the louvers, άβ (FIG.7).

In a particular embodiment of the above-described leaching chamber 1, the leaching chamber has a total length (TL) of 63.16 inches, a laying length (LL) of 60.00 inches, a width (W) of 34.50 inches, a height (H) of 13.00 inches, and a height to the highest louver opening (h) of 7.13 inches. The overall chamber weighs about 15.3 pounds. With respect to the above- referenced U.S. Patent No. 6,644,357, the peak corrugations have a 36-inch pipe profile at its base and transitions to a 24-inch pipe profile at its crest. Further dimensions are given in Table 1 , below.

Table 1

A leaching chamber manufactured in accordance with the above disclosure (ARC-36 H- 10) has been compared with samples of other low- weight commercially-available leaching chambers. The results between the ARC-36 H-IO embodiment and the Quick 4 chamber from Infiltrator Systems, Inc. are summarized in Table 2, below:

Table 2

Note that the disclosed ARC-36 chamber resists loads much better than the competing products. It requires 5 times the load of the Quick 4 chamber to deflect 3% and over 3 times the load to deflect 6%. For the ARC-36, the first failure point occurs when the crown buckles. In the Quick 4 product, there are preliminary failures before the chamber fails. The distinctions are illustrated by load/deflection curves.

FIG. 9A is a load/defection curve for the ARC-36 chamber of Table 2. The curve was plotted from actual measurement data. Note that up until the failure point Al at 5573 pounds, the load/deflection curve is smooth. Even after the failure point, the curve remains smooth before leveling off. This indicates that, even after buckling, the chamber remains as a integral structure.

FIG. 9B is a load/deflection curve for the Quick 4 chamber of Table 2. Again, the curve was plotted from actual measurement data. The Quick 4 chamber fails at a load of 6509 pounds at point Ql, but there is an earlier break at about 5500 pounds at point Q2. After the main failure, the curve falls off sharply and reveals further breaks at least at points Q3, Q4, Q5, Q6, and Q7, indicating that the chamber has lost structural integrity.

While the above-disclosed leaching chamber operates well for its intended purpose, it requires a trench width of at least 36 inches. Some localities require narrower trenches, such as 24 inches or 18 inches. As narrow chambers where designed, it was found that the location of the inspection port in the body of the chamber tended to weaken the chamber. To solve that problem, the inspection port was moved from the body of the chamber to the ends.

FIG. 10 is a perspective view of a leaching chamber having inspection port ends. Like the leaching chamber 1 of FIGS. 1-8, the leaching chamber 100 has an open bottom and is generally arch shaped with a center axis 105. The chamber has a total length TL', a width W, and a height H'. The leaching chamber 100 includes a first end flange 110 at a first end and a second end flange 120 at a second end. The first and second end flanges 110, 120 are complementary so that the first end flange 110 of one chamber can mate with the second end flange 120 of an adjacent chamber.

The first end flange 110 includes a first inspection port structure 112 at the crest of the arch and the second end flange 120 includes a second inspection port 122 at the crest of the arch. Access to the interior of an installed leaching field is attained by cutting out one of more inspection ports. It should be recognized that the first inspection port 112 functions as a post and the second inspection port 122 functions as a dome in a post-dome configuration. That is, when two chambers are mated, the second inspection port 122 of one chamber overlaps the first inspection port 112 of another chamber.

Because the inspection ports are circular structures, the mated chambers can pivot about the mated inspection ports 112, 122 though a fixed angular range. FIG. 11 is a side view of the leaching chamber 100 of FIG. 10. Except for structural differences to accommodate the inspection ports, the chamber 100 is similar to the chamber 1 of FIGS. 1-8. The laying length LL' of the chamber is defined as the longitudinal distance between the centers of the first inspection port 112 and the second inspection port 122. Note that the inspection port structure 112 at the first end is disposed on a larger length first end flange 110 as compared to the leaching chamber of FIG. 1. That additional span if repeated at the opposite end could introduce a weakness into the joint. To counteract that possibility, there is a peak corrugation at the second end that is intersected by the second inspection port structure 122. That corrugation adds strength to the joint without the need for a structural rib. FIG. 12 is a top view of the leaching chamber 100 of FIG. 10. Note that the first end

132 of the base flange 130 is contoured to receive a second end 134 of another base flange 130. The received second end is held in place by tabs 116 extending from the first end flange 110. FIGS. 13A-13B illustrate the interconnection of adjacent leaching chambers of FIG. 10. Note that assembly is similar to that shown in FIGs. 6A-6B, except that the post 12 is replaced by a first (overlapped) inspection port 112 and the dome 22 is replaced by a second (overlapping) inspection port 122. To access the interior of the chamber, the mated inspection ports 112, 122 are cut out.

In a particular embodiment of the above-described leaching chamber 100, the leaching chamber has a total length (TL') of 67.25 inches, a laying length (LL') of 60.00 inches, a width (W) of 22.00 inches, a height (H) of 11.623 inches. Note that the resulting 22- inch chamber is nearly as tall as the previously described 36-inch chamber, which results in a more favorable arch profile.

It should be understood that the dimensions given above are approximate or nominal dimensions, which can vary due to changes in material properties or manufacturing techniques. The performance of the manufactured product can be enhanced by designing for even distribution of plastic throughout the part. In a particular embodiment, the actual sidewall thickness varies by less than 10% of the maximum thickness.

The chambers are typically shipped from a factory to a distribution center by being stacked on pallets. It is advantageous to stack many chambers on a single pallet. The rigidity of prior art leaching chambers can cause breakage during transport. It is not unusual for 10% of prior art chambers on a pallet to be cracked during shipment. The flexibility and profile of the above-disclosed chambers allows them to be more reliably transported, and in greater numbers per pallet.

FIG. 14 is a cross-sectional diagram of nested chambers taken along line C-C in a valley corrugation of FIG. 4. As shown, two chambers IA, IB are stacked, such as for shipping or storage. Each valley corrugation includes a pair of stacking columns 162A, 162B extending downward from the underside of the corrugation and a pair of stacking pockets 164 A, 164B on the topside of the corrugation. As shown, the stacldng columns 162 A, 162B are tube shaped and can be longer than the distance separating the surface of the peak corrugations from the surface of the valley corrugations. The stacking pockets 164A, 164B are delimited from the corrugation surface by a rail 166 A, 166B formed into the corrugation. When stacked, the bottom of the top stacking column 162B rests in a respective pocket 164 A of the next lower chamber IA, with the rail 166 A guiding and holding the column 162B in the pocket 164 A.

Because the arch shape and corrugations decrease in size away from the base, the chambers can be closely stacked. The stacking pockets 164 guide the columns 162 so that they are vertically aligned. With a pallet suitably constructed to transfer the column load to the pallet, a stack of at least 60 chambers can be shipped without damage. Even if the load is not directly transferred, the only chamber that typically suffers damage is the bottom chamber, which carries the load of all chambers above it, and generally only when the plastic is exposed to sufficient heat to weaken its stacking pocket 164.

The flexibility of the above-disclosed chambers also reduces the risk of damage due to rough handling of individual chambers. Instead of resisting twisting and bending forces, which can break prior art chambers, the above-disclosed chambers move with the forces by flexing. While the corrugations themselves are strong, the chamber can flex around its center axis. In particular, the chamber can be easily twisted so that the opposing ends are at about 45 degrees relative to each other. Once the forces are removed, the chamber returns to its nominal shape.

While particular embodiments of the leaching chambers are injection molded from high density polyethylene (HDPE), other manufacturing techniques can be used. In addition, the leaching chambers can be fabricated from another suitable polymer, such as polypropylene, or another material, such as concrete, metal, or ceramics, or combinations of materials.

While this invention has been shown and described with references to particular embodiments, it will be understood by those skilled in the art that various changes in form and details may be made to the detailed embodiments without departing from the scope of the invention as defined by the appended claims.

Claims

CLAIMS We claim:

1. A structure having a base with an open bottom, comprising: a plurality of alternating corrugations, each corrugation being arch shaped about a center longitudinal axis with the bottom of the arch being at the base and the crest of the arch being perpendicular to the base; and the corrugations including a peak corrugation having a radius when sectioned through the center longitudinal axis, the radius varying along the arch from the base to the crest of the arch.

2. The structure of Claim 1 wherein the radius is continuously variable along the arch from the base to the peak.

3. The structure of Claim 1 wherein the radius is larger at the base than at the peak of the arch.

4. The structure of Claim 1 wherein the peak corrugation includes an opening to facilitate the flow of a flowable medium between the inside of the structure and the outside of the structure.

5. The structure of Claim 4 wherein the peak corrugation further includes louvers to define the openings and to inhibit the intrusion of external material into the structure.

6. The structure of Claim 1 wherein the corrugations are plastic.

7. The structure of Claim 1 wherein the corrugations are not connected with structural ribs.

8. The structure of Claim 1 wherein the corrugations have a wall thickness of about 0.1 inches.

9. A corrugated plastic chamber having a base with an open bottom, comprising: an arch-shaped plastic body having a length and opposing ends; a plurality of alternating corrugations running along the length of the body, each corrugation being arch shaped about a center longitudinal axis with the bottom of the arch being at the base and the crest of the arch being perpendicular to the base; and the corrugations including a plurality of peak corrugations, each having a radius when sectioned through the center longitudinal axis, the radius varying along the arch from the base to the crest of the arch.

10. The chamber of Claim 9 wherein the radius is continuously variable along the arch from the base to the peak.

11. The chamber of Claim 9 wherein the radius is larger at the base than at the peak of the arch.

12. The chamber of Claim 9 wherein each of the peak corrugations includes an opening to facilitate the flow of a flowable medium between the inside of the chamber and the outside of the chamber.

13. The chamber of Claim 12 wherein each of the peak corrugations further includes louvers to define the openings and to inhibit the intrusion of external material into the chamber.

14. The chamber of Claim 9 wherein the corrugations are not connected with structural ribs.

15. The chamber of Claim 9 wherein the corrugations have a wall thickness of about 0.1 inches.

16. The chamber of Claim 9 wherein the corrugations have a wall thickness that does not vary by more than 10%.

17. A leaching chamber for burial in the ground, comprising: an arch-shaped plastic body having a length and opposing ends; a plurality of alternating corrugations running along the length of the body, each corrugation being arch shaped about a center longitudinal axis with the bottom of the arch being at the base and the crest of the arch being perpendicular to the base; the corrugations including a plurality of peak corrugations, each peak corrugation having: a radius when sectioned through the center longitudinal axis, the radius varying along the arch from the base to the crest of the arch; and a plurality of openings along a portion of the peak corrugation.

18. The leaching chamber of Claim 17 wherein the radius is continuously variable along the arch from the base to the peak.

19. The leaching chamber of Claim 17 wherein the radius is larger at the base than at the peak of the arch.

20. The leaching chamber of Claim 17 wherein the peak corrugation openings facilitate the flow of an effluent from the inside of the leaching chamber to the outside of the leaching chamber.

21. The leaching chamber of Claim 20 wherein the peak corrugation further includes louvers to define the openings and to inhibit the intrusion of soil into the structure.

22. The leaching chamber of Claim 21 wherein the louvers formed on the peak corrugations.

23. The leaching chamber of Claim 22 further comprising a frame structure formed on peak corrugations, the louvers being within the frame structure.

24. The leaching chamber of Claim 17 wherein the corrugations are not connected with structural ribs.

25. The leaching chamber of Claim 17 wherein the corrugations have a wall thickness of about 0.1 inches.

26. The leaching chamber of Claim 17 wherein the corrugations have a wall thickness that does not vary by more than 10%.

27. A leaching chamber for burial in the ground, comprising: an arch-shaped plastic body having a length and opposing ends; a plurality of alternating corrugations running along the length of the body, each corrugation being arch shaped about a center longitudinal axis with the bottom of the arch being at the base and the crest of the arch being perpendicular to the base, the corrugations including; a plurality of peak corrugations, each peak corrugation having: a radius when sectioned through the center longitudinal axis, the radius continually varying along the arch from the base to the crest of the arch, wherein the radius is larger at the base than at the crest; a plurality of formed louvers defining openings along a portion of the peak corrugation; a plurality of valley corrugations between adjacent peak corrugations, each valley corrugation having a plurality of formed louvers defining openings along a portion of the valley corrugations.

28. The leaching chamber of Claim 27 wherein the corrugations are not connected with structural ribs.

29. The leaching chamber of Claim 27 wherein the corrugations have a wall thickness of about 0.1 inches.

30. The leaching chamber of Claim 27 wherein the corrugations have a wall thickness that does not vary by more than 10%.

31. The leaching chamber of Claim 27 wherein a plurality of the valley corrugations includes a pair of stacking features .

32. The leaching chamber of Claim 31 wherein each stacking feature includes: a stacking column extending vertically downward from the valley corrugation; and a stacking pocket above the valley corrugation and vertically aligned with the stacking column.

33. The leaching chamber of Claim 32 wherein the stacking feature further includes a rail transitioning the stacking pocket to the top of the valley corrugation.

34. The leaching chamber of Claim 27 further comprising at least one access port formed in the body.

35. The leaching chamber of Claim 34 wherein the access port is disposed at the crest of a valley corrugation.

36. The leaching chamber of Claim 34 wherein there are a pair of access ports, one access port at each end of the body.

37. A method of manufacturing a structure having a base with an open bottom, comprising: forming a plurality of alternating corrugations, each corrugation being arch shaped about a center longitudinal axis with the bottom of the arch being at the base and the crest of the arch being perpendicular to the base; and forming the corrugations to include a peak corrugation having a radius when sectioned through the center longitudinal axis, the radius varying along the arch from^' the base to the crest of the arch.

38. A method of manufacturing a corrugated plastic chamber having a base with an open bottom, comprising: forming an arch-shaped plastic body having a length and opposing ends; forming a plurality of alternating corrugations running along the length of the body, each corrugation being arch shaped about a center longitudinal axis with the bottom of the arch being at the base and the crest of the arch being perpendicular to the base; and forming the corrugations to include a plurality of peak corrugations, each having a radius when sectioned through the center longitudinal axis, the radius varying along the arch from the base to the crest of the arch.

39. A method of manufacturing a leaching chamber for burial in the ground, comprising: forming an arch-shaped plastic body having a length and opposing ends; forming a plurality of alternating corrugations running along the length of the body, each corrugation being arch shaped about a center longitudinal axis with the bottom of the arch being at the base and the crest of the arch being perpendicular to the base; forming the corrugations to include a plurality of peak corrugations, each peak corrugation having: a radius when sectioned through the center longitudinal axis, the radius varying along the arch from the base to the crest of the arch; and a plurality of openings along a portion of the peak corrugation.

40. A method of manufacturing a leaching chamber for burial in the ground, comprising: forming an arch-shaped plastic body having a length and opposing ends; forming a plurality of alternating corrugations running along the length of the body, each corrugation being arch shaped about a center longitudinal axis with the bottom of the arch being at the base and the crest of the arch being perpendicular to the base, the forming of the corrugations including; forming a plurality of peak corrugations, each peak corrugation having: a radius when sectioned through the center longitudinal axis, the radius continually varying along the arch from the base to the crest of the arch, wherein the radius is larger at the base than at the crest; a plurality of formed louvers defining openings along a portion of the peak corrugation; forming a plurality of valley corrugations between adjacent peak corrugations, each valley corrugation having a plurality of formed louvers defining openings along a portion of the valley corrugations.

41. A chamber structure having end flanges, each end flange fabricated to mate with a corresponding end flange of a like chamber structure, comprising: a first end flange having a first access port structure; and a second end flange having a second access port structure. , ^₁ . _Λ , . , _{Λ a}

42. 1 he chamber structure of Claim 41 wherein the end flanges are arch shaped and the first access port structure is disposed at the crest of the first end flange and the second access port structure is disposed at the crest of the second end flange.

43. The chamber structure of Claim 42 wherein the access port structures are circular.

44. The chamber structure of Claim 41 further comprising: a plurality of alternating corrugations, each corrugation being arch shaped about a center longitudinal axis with the bottom of the arch being at the base and the crest of the arch being perpendicular to the base; and the corrugations including a peak corrugation having a radius when sectioned through the center longitudinal axis, the radius varying along the arch from the base to the crest of the arch.

45. The chamber structure of Claim 44 wherein the radius is continuously variable along the arch from the base to the peak.

46. The chamber structure of Claim 44 wherein the radius is larger at the base than at the peak of the arch.

47. The chamber structure of Claim 44 wherein the one of the access port structures bisects a peak corrugation.

48. A leaching field comprising: a first leaching chamber and a second leaching chamber, each leaching chamber having like end flanges, the end flanges including a first end flange having a first inspection port structure and a second end flange having a second inspection port structure; and the first leaching chamber mated with the second leaching chamber such that the first inspection port structure of the first leaching chamber overlaps the second inspection port structure of the second leaching chamber. _v.

49. The leaching^' Held of Claim 47 wherein the first inspection port structure and the second inspection port structure are open to allow access to the interior of the leaching field.

50. The leaching field of Claim 47 wherein the longitudinal axis of the first chamber is at an angle relative to the longitudinal axis of the second chamber.

51. The leaching field of Claim 47 wherein the first and second leaching chambers can rotational pivot about the mated inspection port structures.

52. The leaching field of Claim 47 wherein the first and second leaching chambers further comprise: a plurality of alternating corrugations, each corrugation being arch shaped about a center longitudinal axis with the bottom of the arch being at the base and the crest of the arch being perpendicular to the base; and the corrugations including a peak corrugation having a radius when sectioned through the center longitudinal axis, the radius varying along the arch from the base to the crest of the arch.

53. The leaching field of Claim 51 wherein the radius is continuously variable along the arch from the base to the peak.

54. The leaching field of Claim 51 wherein the radius is larger at the base than at the peak of the arch.

55. The leaching field of Claim 52 wherein the first inspection port structure bisects a peak corrugation.

56. A method of manufacturing a chamber structure having end flanges, each end flange fabricated to mate with a corresponding end flange of a like chamber structure, comprising: fabricating a first end flange having a first access port structure; and fabricating a second end flange having a second access port structure.

57. A method of installing a leaching field comprising: providing a first leaching chamber and a second leaching chamber, each leaching chamber having like end flanges, the end flanges including a first end flange having a first inspection port structure and a second end flange having a second inspection port structure; and mating the first leaching chamber with the second leaching chamber such that the first inspection port structure of the first leaching chamber overlaps the second inspection port structure of the second leaching chamber.