CA1149182A - Containment reservoir liner and method - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
This invention relates to a method of lining a con-tainment reservoir for a liquid, such as petroleum oil, and a liner for carrying out the method. The reservoir comprises a walled ground containment space or pit, opening upwardly, with the liquid impervious flexible liner generally following the contour of the space. The liner comprising a layer of pervious fabric material having on at least one of its sides layer of liquid impervious material, such as rubber, the liner being operable to prevent escape of liquid through the liner from the containment space. Means are provided coacting with the liner covered containment space for removing liquid from the reservoir.
A covering layer of pervious fabric material filters anything, including liquid, passing into the reservoir. A method of forming the reservoir from predetermined width strips of liner stock, and a method of retaining and salvaging oil spilled along railroad track environment is also disclosed.

Description

9~
1 This application is a division oE copending Canadian Patent Application Serial No. 34~,2~6 filed January 23, 1980.
This invention relates in general to reservoirs and more particularly to a method of lining a containment reservoir and a liner for carrying out the method. The liner comprises a layer of pervious fabric material and a layer of liquid imper~ious material, with the liner being operable to re-tain received liquid in the con~ainment space.

Background of the Invention Reservoirs formed with a flexible liner layed in or lining an earthen containment space, or lining a tank, are well known in the art. U.S. patents 3,872,007, 3,474,625 and 1,081,515 disclose various arrangements of formed reservoirs utilizing a flexible liner. However, these prior art reservoirs generally provide for the liner being a one piece affair, defining the entire containment space or reservoir, and have not been entirely satisfactory. Moreover, to applicant's knowledge, no one heretoEore has provided a containmen-t reservoir utili-zing a flexible liner material, and having a covering layer of20 pervious fabric material overlying the opening into the reservoir, for filtering liquid passing into the reservoir, and as is disclosed in applicant's invention.
Summary of the Invention The present invention provides a method of lining a containment reservoir and a liner for carrying out the method.
The liner comprising a layer of pervious Eabric material having on at least one of 7 ts sides a layer of impervious material such as rubber, with such liner being operable to resist or prevent escape of liquids from -the containment space.

Accordingly, an object of the invention is to provide a novel method of lining a containment reservoir for liquids, such as petroleum based oils.

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1 A further objec-t of the invention is to provide a novel method of the above type in which the containment space has a liquid impervious liner generally following the contour thereof in at leas-t one direction and with the liner comprising a layer of pervious fabric material and a layer o~ impervious material, such as rubber, with the impervious layer facing outwardly of the space, and with the liner being operable to resist escape of liquids from the space, through the liner.

A further object of the inventi.on is to provide a liner for carrying out the above wherein the liner comprises a non-woven polyester fabric material layer having a rubber coating bonded or secured to one side of the perv.ious layer, and forming thc impervious.layer of the liner.
A still further object of the invention is to provide a liner comprised of a plurality of strip sections, each of predetermined width, with the strip sections being joined at the junctures thereof, and forming the liner for the reservoir~
Other objects and advan-tages of the invention will be apparent from the following description taken in conjunction with the accompanying drawings wherein:

Brief Description af the Dr _ings FIGURE 1 is a top plan, broken, fragmentary view of a reservoir in combination with a railroad -track section, for containing liquids, such as petroleum based oil, that is in-advertently spilled from vehicles on the railroad track section, or during fueling of such vehicles, so as to prevent the seepage of the oil into the soil areas adjacent the track section, and to retain it in a reservoir disposed beneath the track section, for subsequent salvage.
FIG~RE 2 is a vertical transverse sectional view of the lined reservoir of FIGURE 1.

1 FIGUR~ 3 is an enlarged view of a section of the top portion of the reservoir of the FIGURES 1 and 2, illustrating details oE the structure.
FIGURE 4 is an enlarged, vertical sectional view of the liquid impervious liner utilized in the reservoir oE FIGURES 1-3, and is taken generally along line ~-4 of FIGURE 2, looking in the direc-tlon of the arrows.
E'IGtJRE 5 is an enlarged vertical sectional view taken genera~ly along the plane of line 5-5 of FIGURE 2, looking in the direction of the arrows, and illustrating the pervious layer of fabric ma~erial overlying -the open top of the reservoir o~
FIGURES 1-3.
FIGURE 6 is a view generally similar to that of FIGURE 1, and illustrating another embodiment of containment reservoir in association with a section of railroad track.
FIGURE 7 is an enlarged, transverse sectional view of the reservoir of FIGURE 6.
Descrip-tion of Preferred Embodiments Referring now to FIGURES 1 throuyh 5, there is illustrated the combination of a containment reservoir 10 formed in accordance with the invention, and a railroad track section 11. The railroad track section comprises ~paced rails 12 and 13 which are supported in the conventional manner on ties 14 which in this case, are shown as wood ties 14.
However, any suitable type of tie structure, including concrete ties may be used. The railroad track sec-tion 11 is adapted to carry conventional railroad equipment including diesel powered locomotives. Containment reservoir 10 formed in accordance with the invention extends beneath and laterally of track section 11. Reservoir 1~ comprises a space or pit 16 in the ground, opening upwardly and encompassing -the railroad track section 11 for a predetermined portion of the length thereof. The walls of the containment space 16 in the embodiment illustrated, are sloping downwardly and inwardly ~FIGURE 2) so that any liquid in the reservoir drains downwardly toward a central drain area 20 of the space, the latter area preferably comprising generally ~ertically oriented walls 21 which merge with the diagonal defining side wall surfaces 16a of the space 16~
In accordance with the invention, the walls of space 16 are covered with a liner 22 so as to restrict or prevent escape of liquid from the containment space into the surrounding ground area. The liner comprises a layer 2~ (FI~URES 3 and 4) of pervious fabric material, such as for instance a non-woven polyester fabric. A preferred fabric material is known in the trade as "Bidim" engineering fabric manufactured by Monsanto Textile Company of St. Louis, Mo. This "Bidim" fabric is a random entanglement of polyester filaments, and is of relatively low fabric density, which enables li~uids to pass completely through the "Bidim" layer. The "Bidim" fabric is manufactured by needle punching of direct spun polyester filaments which may be continuous filaments The fabric has nearly the same tensile strength in all directions and therefore withstands large local deformation, and possesses excellent puncture resistance, while still being of a highly porous nature. The fabric will generally retain or hold back particles larger than about 70 microns, while permitting smaller liquid-borne fines to pass through without clogging the fabric. Moreover, there is negligible change in the physical properties of the "Bidim"
fabric from below zero temperatures to temperatures as high ll32 1 as 4000F. The l'Bidim" conventionally comes in various standard widths in roll form, such as for instance 13 ~t. 6 in.
wide, or approximately 17 ft. 4 in. wide. Fabrlc layer 24 may be anywhere from approximately 60 to 190 mils in thickness.
The liner 22 also comprises a layer 25 of material impervious -to li~uid, such as rubber, with the impervious layer in the embodiment illustrated in FIGURES 1-3, facing outwardly of the ccntainment space. The impervious layer 25 can be applied to the layer of pervious fabric material by conventional calender~
ing processes, known in the rubber art, resulting in a liner which while highly flexible, is impervious to the flow o~ liquid therethrough~ The thickness y of the impervious layer 25 may be approximately one-third the thickness x of the pervious layer 24. ~lowever, 6-10 mils of rubber also impregnates into the pervious layer and thus is securely fastened or bonded thereto. The rubber is preferably resistant to oil degradation (e.g. Nitrile Rubber). The rubber is calendered onto strips of the fabric of predetermined width ~e.g. 60 inches~ and length (approximately 984 feet) and then such rubber coated fabric strips are fastened together or joined by conventional adhesive means, and cured, and then cut, to form a predetermined width and length of coated fabric stock ~e.g. 19 feet wide x 100 feet long~ which is subsequently packaged for tràns-portation to and use at the site where the reservoir is to be installed.
The liner may be laid down in strip form as afore-mentioned, from rolls of liner stock material, and ~ith the strips being preferably overlapped as at 26 (FIGURE 7) for providing a lined containment reservoir of any desired size.
The overlapping preferably occurs in a downward direction as 1 illustrated, and preferably on oblique or vertical portions of the containment space. The overlapped sections o~ the coa-ted fabric are preferably secured together by suitable and known adhesive means, which can be applied at the site, so that there is no chance for liquid to seep between the junct~re portions and escape from the reservoir into the surrounding ground area.
Leading from the drain portion 20 of the containment reservoir is at least one passageway 28 (a plurality of such passageways being illustrated in FIGURE 1) for draining the reservoir. Such passageways communicate through the liquid impervious liner as by means of ports or punc-ture openings 29 (FIGUR~ 2) in the liner and passageway 28 preferably slopes downwardly toward a transversely extending larger further passageway 30 running generally parallel (FIGURE 1) to the reservoir and associated track section. Passageways 28 and 30 are preEerably lined as by means of tile or concrete or any other suitable material, for preventing the liquid received from the con-tainment reservoir from passing or seeping into the surrounding ground areas.
~ Communicating with passageway 30 are vertical shafts 32, providing access to the passageway 30, with such shafts being preferably covered by manhole covers 32a. It will be seen that upon removal of the covers 32a, access is provided to the shafts 32 opening or communicating via an opening in the top of passageway 30, with the respective shaft 32. Liquid that is caugh~ in the reservoir 10 will drain by gravity down through drain section 20, down passageway 28 into passageway 30, where it may be removed by gravity flow to a more remote location or a storage facility (not shown). Passageways 32 provide access to drain passageways 28 and 30 for clean out purposes.

1 The containment space 16 is filled ~i~h a lump-like material of rela-tive large or coarse size~ such as rai~way bed ballast 35, comprising stones or the like conventionally utilized in conjunction with a railroad track installation.
Such ballast bed~ has very little if any, fines; to prevent clogging of the bed. Such highly porous layer~ 35 of ballast will readily pass therethrough liquid cau~ht b~ the reservoir.
The space 16 is of sufficient depth to preferably provide a minimum of 8 inches depth of ballast layers beneakh ties 14.
It will be seen that the upper end of the reservoir on its sides is preferably defined in part by generally vertical earthen side wall sections 36, which are covered by sections 38 of the liner material. Such upper wall sections 38 of the liner preferably extend horizontally as at 38a for a predetermined width, and then are retained in position as by means of the adjacent soil, to hold the respective upper end wall liner section 38 in position. It will be understood of course that means other than abutting soil could be provided for anchoring or holding the upper sections of the liner in place. The portion of liner 22 in the containment or pit area, is positively maintained in position hy the weight of the ballast supported on the liner, but since the liner is of puncture resistant material as aforementioned, such ballast does not injure the liner.
In this embodiment of reservoir, the ties 14 are embedded in the ballast in the conventional manner of supporting railroad ties, and thus are held in predetermined position and support the track members 12 and 13 thereon.

In order to filter liquid, such as fuel and/or lubricating oils that may drip down from the diesel locomoti~es 1 or other vehicles on track section 11, prior -to the liquid passing into the containment space, and to prevent plugginy of the porous ballast layer 35, the top of the reservoir is preferably covered by a layer 40 of flexible pervious fabric material, such as the aforementioned "Bidim" fabric, with said upper layer 40 extending from the aforedescribed upper sections 38 of the liner 22, to the .respective rail members 12 or 13, as well as across the space intermediate the rail members 12 and 13. As best shown in FIGURE 2, layer 40 may be tucked in~ardly and downward].y as at 41, adiacent liner sections 38.

In order to maintain the top pervious layer of fabric matexial in place covering the top of the reservoir, the strip of material intermeaiate the track or rail members 12 and 13, and on either side thereof for a predetermined distance out-wardly therefrom, are weighted down by preferably metal grating 42~ w~ich is preEerably of articulated construction, and which hold the sections of pervious filter layer ma-terial 40 in position covering the -top end of the reservoir. Laterally outwardly from the grating sections 42, the pervious layer 40 can be covered with a relatively thin layer 44 oE aggregate material, s~lch as the aforementioned ballast material, or some other porous layer, for weighting the pervious fabric layer 40 down a~ainst the ballast layer 35. As liquid, such as petroleum based fuel oil drips down, say for instance, from a diesel locomotive, it will pass through the grat.ing 42 or the par-ticle weigh down layer 44, and then through the porous fabric filter layer 40 down into the ballast filled reservoir, where the oil drains down to the drain section 20, then by gravity down through passageway 28 to further passageway 30, where it can drain for instance by gravity to a remote storage facility, to be reclaimed.

1 While the porous layer 40 will pass liquid, such as the aforementioned oil therethrough, it will not pass material such as sand from the locomotive or train mechanisms passing over the track section ll, and thus any sand or o-ther particles larger than about 70 microns will collect on the top o~ the filter layer 40, and will not pass into the reservoir. Thus the oil act~lally feeding through the reservoir into drain portion 20 thereof will not be contaminated by sand, or other fines. Moreover, clogging of the reservoir will be materially delayed or prevented since the liquid will have been filtered by filter layer ~0 as well as the ballast layer 35 in the formed reservoir. The thickness of the porous layer 40 can be of any selected -thickness, as for instance from approximately 60 mils up to say for in~tance l90 mils, depending on the thickness of non-woven fabric tha-t is provided in the fabric stock rolls for filter layer 40. However, a thickness of approximately 75 to 90 mils has been found to be satisfactory, and is preferred. In any event, the non-woven fabric material is extremely porous and readily passes liquid therethrough, with the thickness being chosen depending in part on the tear andJor burst streng-th of the material that the installa-tion may require.
Referrin~ now to FIGURES 6 and 7, there is shown a further embodiment of reservoir construction lO' for use with a railroad track section. In this embodiment, the ground containment space 16' has side wall surfaces 36' of a much greater slope as compared to the greater portion of the side wall surfaces of the first described reservoir structure, with the lower drain section 20' of the reservoir being disposed along one lateral side of the reservoir as best shown in 1 FIGURE 7. It will be seen that "lapping" of the liner stock occurs as aforementioned in this embodiment, on the bottom wall surface 46 of the reservoir, and with the slope of the bottom wall being such tha-t any possibility of leakage or seepage of the liquid from the reservoir at the adhesively connec-ted overlapping juncture of the liner stock sec-tions is positively eliminated, thus insuring that li~uid will run down toward the drain section 20' of the reservoir. This embodiment of reservoir is substantially deeper as compared to the first embodiment.
In other respec-ts, the reservoir embodiment of FIGURES 6 ~nd 7 may be generally similar to that of the first described embodiment with any liquid draining down from railroad vehicles o~ the track section ll' passing through the grating 42 and/or ballast layer 44, through the pervious uppèr filter ~' '~ f6~V~
layer~ 40 down through the ballast layer~ 35, in the retainer space 16' and down to the drain section 20l, where it ~ill flow by gravity through the passageways 28 and 30 whereupon it can be removed.
While a particular type of non-woven pervious fabric material has been identified (and more specifically "Bidim"
fabric) as the material for the liner 22 and the filter layer 40, it will be understood that while that is the preferable pervious liner material for the construction of the containment reservoirs of the invention, it may not be the only material having similar characteristics, that would be useable in practicing the invention. The ~lexible liner 22 of the reservoir aids in distributing the s-tress from `the trac~ section 11 over a wider area, and improves the load bearing characteristics of the soil area in which the reservoir is located.

~9~32 1 The method of forming the reservoir and the structure of the reservoir itself results in an economical yet eff~ctive reservoir, for catching and reclaiming liquids and preventing their passage into adjacent land areas, thereby preventing in-troduction of undesirable materials into adjacent land areas and thence into rivers and streams which of course would result in pollution of public waterways.
In laying the filter layer 40 on the top of the reservoir, the width of filter stock can be laid over the tracks (before application of the grating ~2 and weight ballast 44) and then a railway vehicle can be brought onto the track section 11 to run over the underlying layer of filter fabric, whereupon the wheels of the vehicle will slice through the fabric and gravity will cause the severed fabric sections to fall in proper position between rails 12 and 13 and laterally thereoE, after which -the grating ~2 and ballast layer 44 can be placed on the top of such severed sections of fabric to weigh the latter down.
Grating 42 and ballast layer 4~ additionally prevent a slippery condition from existing at the reservoir, since they provide a

2~ relatively good footing irrespective of being exposed to the oil caught by the reservoir.
From the foregoing discussion and accompanying drawings it will be seen that the invention provides a novel relatively economical containment reservoir for liquids, such as oil, which comprises a walled containment space opening upwardly, with the space containing a liquid impervious liner generally following the contour thereof, with the liner com-prising a layer of pervious fabric material ana a layer of liquid impervious material, and with the liner being operable to pre-vent escape of liquid through the liner from the containment 1 space. The invention also provides a containment reservoir in which means is provided coacting with the lined containment space for facilitating removel of -the liquid -therefrom, as well as a novel struc-tural arrangement utilizing stock liner material in strip form for readily cons-tructing a liner for any necessary size of reservoir, and facilitating the movement of the materials to the location of use in construction of the reservoir. The invention also provides a novel method of lining an earthen containment space, and a method of collecting liquid from along a railroad track section.

The terms and expressions which have been used are used as terms of descrlption and not of limitation, and there is no intention in the use of such terms and expressions of excluding any equivalents of any of the features shown or described, or portions thereof, and it is recognized that various modifi-cations are possible within the scope of the invention claimed.

Claims (4)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method of lining an earthen containment space having sloping defining walls, flexible liquid impervious liner generally following the contour of the containment space to define a reservoir, comprising, providing liner stock in flexible strip form having a filtering layer of liquid pervious fabric material having on at least one of its sides a layer of liquid impervious material, such as rubber, laying down a plurality of strips of the liner material with the impervious layer facing outwardly of the reservoir space and with the liner strips overlapping, adhesively securing the overlapped junctures of the liner strips together so as to restrict escape of liquid from said containment space, extending said liner material upwardly to the level of the adjoining surface and horizontally outwardly therefrom,with the liner generally conforming to said sloping walls of the earthen containment space, and including the step of filling the reservoir with lump material directly onto the liner, to provide a layer of ballast material therein, and then covering the ballast material with a layer of porous fabric material through which liquid can pass into the reservoir and into contact with the ballast, and further including the step of providing for removal of liquid by draining from the containment space.

2. A method in accordance with claim 1 wherein removal is accomplished by providing a communicating passage with the reservoir adjacent the bottom thereof.

3. A method in accordance with claim 2 including providing a drain area along the bottommost area of the reservoir for collecting liquid by gravity in such drain area for subsequent removal therefrom.

4. A method in accordance with claim 3 including providing passageway drain means which in turn communicate with said drain area for removing liquid from said reservoir.