Bonded multilayer manhole liner, method for manufacturing the same, and method of installation

Abstract

A manhole liner composite for rehabilitating and reinforcing a sewer structure. The liner composite includes a plurality of strips of a bonded liner material. Each of the strips of the bonded liner material comprises first and second structural fiberglass layers. A membrane layer is disposed between the first and second structural fiberglass layers and bonds the first and second structural fiberglass layers to form a unitary, single-piece strip of bonded liner material.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a liner material, particularly for an underground support structure, such as wastewater and stormwater structures, and for lining manholes and sewage pumping stations. More specifically, the present invention is directed to a bonded multilayer manhole liner, method for manufacturing the bonded multilayer manhole liner material, and method of installing the bonded multilayer manhole liner material.BACKGROUND OF THE INVENTION

[0002] Underground and above ground structures, such as sewer manholes, pump stations, wet wells, vaults, pipes, culverts and other structures, are frequently formed from brick, cement, and like cementitious and / or refractory materials. The manhole usually has a relatively long neck portion extending from the surface, and terminating in a lower sometimes flaring portion to which a sewer pipe communicates. The sewage flowing through the sewer pipe, over time, may damage the mortar which secures the bricks of the manhole together, or the cement with which the manhole is formed. Damage to the bricks and cement will permit ground water and subsurface water to infiltrate the manhole, with the result that the water treatment plant may become overloaded and unable to handle the amount of water which it receives during rain and other such occurrences. In that event, either untreated water is uncontrollably discharged, or the water treatment plant itself becomes unable to perform its function and needs to be taken out of service.

[0003] Typical sizes of manholes are 48" in diameter and overall averages 10 ft depth historically. Range, however, can be 48-72" diameter by 11-50 ft depth. Shapes also vary. Square and rectangular lift stations can be lined either with a liner inflated in place or in panels (this generally depends on the size, depth and accessibility). Lift / pump stations and wet wells also vary greatly in size and depth. For example, a lift station may be 13 ft W x 15 ft L x 35 ft D with panels. When lined with panels, they are cut 30" in width x whatever depth they need to be. A 3" overlap is allowed on each panel.

[0004] Typical sewer gas, primarily hydrogen sulfide (H2S), corrodes concrete in sewer systems because it is converted to sulfuric acid by bacteria, which then attacks the concrete in concrete structures and also attacks mortar in brick-and-mortar structures. This process of bacterial corrosion is known as microbially induced corrosion (MIC). The sulfuric acid produced by the bacteria is highly corrosive and reacts with the calcium compounds in concrete, leading to a breakdown of the concrete's structure. This corrosion can cause significant loss of concrete mass and can destroy the entire sewer structures and can also cause structural collapse, which is both dangerous and costly. H2S corrosion, produced by common sewer gas turns, concrete into powder. It basically disintegrates concrete.

[0005] Replacement of a manhole is a relatively expensive undertaking, because of the need to excavate the surrounding soil and remove the bricks and other materials. In addition, the sewer itself must continue to be usable during the procedure, or else homes and businesses will be unable to flush toilets, run taps, etc. For this reason, it is desirable to rehabilitate and / or reinforce the manhole in a way which avoids a need for replacement.

[0006] U.S. Pat. No. 5,265,981, the complete disclosure of which is incorporated herein by reference, discloses a method and apparatus for rehabilitation a manhole through use of a resin impregnated fiberglass liner which is inflated and cured in place while permitting the manhole to remain in service as it is being rehabilitated. That patent discloses the use of heated air to inflate the liner so that the surrounding walls of the manhole are engaged, after which the resin cures and secures the liner to the walls of the manhole. I have found that heated air can take a relatively long period to achieve sufficient resin cure. Particularly for deep manholes, the walls of the manhole and the surrounding soil act as a heat sink, which tends to cool the resin, so that additional time for curing is required because the surrounding material that also must be heated somewhat. However, making the existing liners and their inflation bladders totally conform to the curvatures inside structures that have flat offsets from the manhole ring and cover and chimney to the main cylinder of the structure is very difficult and problematic.

[0007] Conventionally, a manhole liner material consisting of two layers of structural fiberglass stitched to an intermediate non-porous felt membrane. The PVC membrane typically softens between 50°C / 122°F and 70°C / 158°F and melts at 160°C / 230°F. The liner, after installation and cure of the resin, achieves both a mechanical bond and an adhesive bond with epoxy resin applied to the fiberglass layers.

[0008] In view of the above, a need exists for a manhole liner material and a method for manufacturing that eliminates stitching together the fiberglass layers to the middle polymer layer, and a method for installing the resulting liner.SUMMARY OF THE INVENTION

[0009] According to a first aspect of the invention, a manhole liner composite is disclosed for rehabilitating and reinforcing a sewer structure, such as manholes. The liner composite includes a plurality of layers of a bonded liner material. Each of the layers of the bonded liner material comprises first and second structural fiberglass layers, and a polymer membrane layer disposed between the first and second structural fiberglass layers and bonding the first and second structural fiberglass layers so as to form a unitary, single-piece strip of the bonded liner material.

[0010] According to a second aspect of the invention, a method for making a manhole liner composite is disclosed for rehabilitating and reinforcing a sewer structure, such as manholes. The liner composite includes a plurality of layers of a bonded liner composite material. The method comprises the steps of separately feeding the layers of first and second structural fiberglass layers to bonding rollers, extruding a melted liquid polymer material by an applicator to flow smoothly between and over opposed surfaces of the first and second structural fiberglass layers, and pressing the first and second structural fiberglass layers and the melted liquid polymer material together by the bonding rollers, so as to effectively bond the three layers into a single-piece strip of the bonded liner composite material.

[0011] According to a third aspect of the invention, a method for installing a manhole liner for rehabilitating and reinforcing a sewer structure is disclosed. The method comprises the steps of manufacturing a strip of a bonded liner composite material, cutting the strip of the bonded liner composite material into a plurality of the strips of the bonded liner composite material, securing together the strips of the liner material to form the manhole liner composite, and making a liner complementary to the underground support structures.

[0012] Other aspects of the invention, including apparatus, devices, systems, methods, processes, and the like which constitute part of the invention, will become more apparent upon reading the following detailed description of the exemplary embodiments.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings are incorporated in and constitute a part of the specification. The drawings, together with the general description given above and the detailed description of the exemplary embodiments and methods given below, serve to explain the principles of the invention. In such drawings:

[0014] FIG. 1 is a fragmentary cross-sectional view of a bonded liner material according to an exemplary embodiment of the present invention;

[0015] FIG. 2 illustrates a process of manufacturing the bonded manhole liner material according to the exemplary embodiment of the present invention;

[0016] FIG. 3 is an enlarged view of the circled region of FIG. 2; and

[0017] FIG. 4 illustrates a liner installed in an underground support structure from the bonded liner material according to the exemplary embodiment of the present invention.DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0018] Reference will now be made in detail to the exemplary embodiments and exemplary methods as illustrated in the accompanying drawings, in which like reference characters designate like or corresponding parts throughout the drawings. It should be noted, however, that the invention in its broader aspects is not necessarily limited to the specific details, representative materials and methods, and illustrative examples shown and described in connection with the exemplary embodiments and exemplary methods.

[0019] This description of exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description, relative terms such as "horizontal," "vertical," "front," "rear," “upper”, “lower”, "top" and "bottom" as well as derivatives thereof (e.g., "horizontally," "downwardly," "upwardly," etc.) should be construed to refer to the orientation as then described or as shown in the drawing figure under discussion and to the orientation relative to a vehicle body. These relative terms are for convenience of description and normally are not intended to require a particular orientation. Terms concerning attachments, coupling and the like, such as "connected" and "interconnected," refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. The term "operatively connected" is such an attachment, coupling or connection that allows the pertinent structures to operate as intended by virtue of that relationship. The term “integral” (or “unitary”) relates to a part made as a single part, or a part made of separate components fixedly (i.e., non-moveably) connected together. Additionally, the word “a” and “an” as used in the claims means “at least one” and the word “two” as used in the claims means “at least two”.

[0020] FIGS. 1-3 depict a bonded manhole liner composite material 30 according to an exemplary embodiment of the present invention. A cohesive liner material that does not fray or unravel during cutting or sewing enables the creation of a custom-made liner L, shown in FIG. 4, for sewage manholes, pump stations, culverts, and stormwater catch basins, formed from a cementitious and / or brick material. Such structures usually have circular or a curvilinear wall defining a chamber. The resin impregnated liner L is lowered into the structure as a unit, inflated with air and heated with steam, and the resin ultimately polymerized so as to harden in situ and to bond to the circular or curvilinear wall. When utilizing steam and air pressure to cure the manhole liner L, the manhole liner L is typically cured from 180 - 200°F so the increased softening and melting point of the polymer material of the invention is advantageous for the liner L.

[0021] As shown in FIG. 1, the bonded liner material 30 includes a first structural fiberglass layer 16, a second structural fiberglass layer 20, and a non-porous, flexible and chemical-resistant membrane layer (or barrier) 23 disposed between the first and second structural fiberglass layers 16 and 20, respectively. Preferably, according to the exemplary embodiment, 24 oz. or 18 oz. structural fiberglass layers are employed on both sides of the membrane layer 23, with the selected weight based upon the size and condition of the structure to be reinforced. According to the exemplary embodiment, both the first and second structural fiberglass layers 16 and 20 are structurally identical. A thermoplastic olefin elastomer (TPO), such as SP-20010, available from ESquared, is employed for the membrane layer 23, as it offers superior chemical resistance and bonding properties compared to polyvinyl chloride (PVC).

[0022] FIGS. 2 and 3 depict a machine 14 for manufacturing the bonded manhole liner composite 30 according to the exemplary embodiment of the present invention. The bonded manhole liner composite 30 includes a first structural fiberglass layer 16, a second structural fiberglass layer 20, and a non-porous and chemical-resistant polymer membrane layer situated between the first and second structural fiberglass layers 16 and 20, respectively. Preferably, according to the exemplary embodiment, 24 oz. and 18 oz. structural fiberglass layers are employed. The weight of the layers 16 and 20 is identical, with the selected weight based upon the size of the structure to be reinforced. Preferably, a thermoplastic olefin elastomer (TPO) is employed for the membrane layer 23, as it offers superior chemical resistance and bonding properties compared to polyvinyl chloride (PVC).

[0023] The machine 14 for manufacturing the bonded manhole liner composite 30 comprises rollers 15 and 21 supplying layers of the first and second structural fiberglass layers 16 and 20, respectively. Each of the first and second structural fiberglass layers 16 and 20 passes first and second systems of feeding pulleys 18 and 19, respectively. The feeding pulleys 18 and 19 feed the first and second structural fiberglass layers 16 and 20 toward bonding rollers 261and 262, which bond the first and second structural fiberglass layers 16 and 20 with a liquid polymer material 22, as best shown in FIGS. 2 and 3, by pressing the first and second structural fiberglass layers 16 and 20 into the liquid polymer material 22. The liquid polymer material 22 is supplied from an applicator 24. The liquid polymer material 22 is formed from melted polymer pellets, with the molten material extruded between the first and second structural fiberglass layers 16 and 20 from the applicator 24. The membrane layer 23 is no less than 10 mils thick, although a minimum of 15 mils is preferred to assure a mechanical bond with the fiberglass of fiberglass layers 16 and 20 and the solidified polymer of membrane 23. According to the exemplary embodiment, the polymer pellets are melted in the applicator 24, and the melted polymer is maintained in the applicator 24 at 350-400°F and applied preferably at 370°F. The liquid polymer material 22 cools and solidifies after the fiberglass layers 16 and 20 have been impressed into it by the rollers, and the solidified polymer forms the impermeable membrane layer 23 that is a non-porous and chemical-resistant membrane layer of the bonded manhole liner composite 30. The impermeable membrane 30 preferable is 15 mils thick. The thickness of the membrane 23 increases the resistance to sewer gas.

[0024] A process of manufacturing the bonded manhole liner composite 30 follows.

[0025] First, the rollers 15 and 21 separately supplying the layers of the first and second structural fiberglass layers 16 and 20, respectively, are provided. The first and second structural fiberglass layers 16 and 20 are separately fed toward the bonding rollers 261and 262, by the first and second feeding pulleys 18 and 19, respectively. Immediately before the fiberglass layers 16 and 20 are pressed toward each other by the bonding rollers 261and 262, the liquid polymer material 22 is extruded from applicator 24, allowing the melted thermoplastic polyolefin to flow smoothly between and over the opposed surfaces of the first and second structural fiberglass layers 16 and 20. The melted polymer material 22 solidifies upon cooling, forming a continuous, uninterrupted membrane layer 23. Preferably the membrane layer 23 is at least 15 mils 0.0 inch (one mil is one thousandth of an inch) thick, which is sufficient to secure the fiberglass within the polymer material without creating openings that would allow passage of fluids, air, steam, and the like. The membrane 23 is sufficiently thick to accommodate the fiberglass bonded to the opposite sides thereof.

[0026] The thermoplastic polyolefin (TPO) membrane barrier 23 is produced by extrusion coating of the TPO resin into a homogenous film before adhering onto the fiberglass layers 16 and 20. The hot melt process is designed to achieve a high level of adhesion of the TPO membrane barrier 23 without adhesives. The TPO polyolefins resins balance flexibility, impact strength and higher melting point (142°C / 287°F, DSC method) to withstand the CIPP (i.e.,cured-in-place-pipe) curing process. An inflatable liner 11 of the present invention is a cured-in-place liner. CIP is a term commonly used in the industry meaning cured-in-place. The softening point of the membrane barrier 23 is between 70°C / 158°F and 80°C / 176°F.

[0027] The material layers 16, 20, 22 are pressed together using the bonding rollers 261and 262, effectively bonding the three layers 16, 20, 22 into a single-piece strip of bonded manhole liner composite (or a cohesive one-ply liner fabric) 30 that does not fray or unravel during cutting or sewing, enabling the creation of custom-made liners for sewage manholes, pump stations, culverts, or stormwater catch basins. When the fiberglass layers 16 and 20 are juxtaposed to the liquid polymer material 22, not all of the fiberglass of layers 16 and 20 are immersed into it. When the liquid polymer material 22 cools, it solidifies and fiberglass of layers 16 and 20 are now attached, with the result that a one-piece composite is created As a result, a small portion of the fiberglass of layers 16 and 20 is submerged (or immersed) in liquid polymer material 22 that later solidifies and becomes the solidified membrane layer 23, as indicated by overlaps 25 in FIG. 1.

[0028] As noted above, the thermoplastic polyolefin (TPO) membrane barrier is produced by extrusion of the TPO resin onto the fiberglass layers, resulting in a homogenous film adhering to the first and second fiberglass layers 16, 20 and their fibers. The thermoplastic polyolefin (TPO) employed in the exemplary embodiment is a polymer blend that provides a balance between pliability and impact resistance along with the thermal resistance. An exemplary TPO is available from ESquared of Hillside, New Jersey as product SP-20010. The hot melt extrusion process achieves a high level of adhesion of the TPO to the fiberglass layers without requiring adhesives, stitching or similar mechanisms for binding the TPO to the fiberglass.

[0029] The ratio of fluid polymer to fiberglass is as follows:

[0030] a. two layers of 47.40 OSY (ounces per square yard) FG (fiberglass) each = 94.8 OSY total FG weight 8.61 to 1 ratio (the 47.4 number = 5600 series liner - lighter fiberglass weight);

[0031] b. two layers of 60.60 OSY FG each = 121.2 OSY total FG weight 11 to 1 ratio (the 60.60 number = our 6800 series liner - heavier weight fiberglass).

[0032] In weight 11 ounces (15 mils) of polymer is applied.

[0033] The resulting liner composite 30 reduces the time required for pulling, cutting and stitching the layers together. Taping and gluing individual layers has been eliminated completely. The resulting bonded manhole liner composite 30 may be rolled through guide rollers 27 onto a new larger spool 32, where it may then be used in the manufacturing of liners L using bonded liner material 30, as illustrated in FIG. 4. The bonded liner material 30 may be saturated onsite with resin and overlapped to form a single monolithic structure, with fewer fins or wrinkles resulting from using a single-piece ply material. The bonded material 30 of the present invention requires less epoxy resin to fully saturate than the existing liner materials, as a result of the elimination of felt fibers imbedded in the membrane of existing liner materials. Specifically, existing liners require approximately 1.3 times more resin to saturate than the disclosed composite 30. This is likely caused by the fiberglass felt used in prior art liners. The fiberglass felt fibers absorbed a lot of resin. The liner composite 30 according to the present invention has no felt and therefore requires less epoxy resin to saturate, yielding a stronger composite after curing in place.

[0034] Thus, the three separate pieces 16, 20, 23 are transformed into a single-piece bonded material 30. What was two layers of fiberglass fabric 16 and 20 and liquid polymer material 22 are transformed into one single piece of bonded material 30. The fiberglass fabrics 16 and 20 are partially immersed into the heated liquid polymer material 22. The heated liquid polymer material 22, after cooling, becomes the non-porous membrane 23. Particularly, as the heated liquid polymer material 22 cools, it solidifies and the fiberglass layers 16 and 20 and the membrane layer 23 become a unitary, one-piece (or single-piece) bonded material 30. Curing of the liner is a matter of time and temperature. The liner may be ambient cured, especially when lining large flat surfaces, such as found in square pumping stations.

[0035] At least one, and typically both, of two opposite surfaces of the single-piece 3-ply bonded liner material 30 of the present invention may later be impregnated with resin and heat-bonded to the walls of the manhole or structure to be reinforced. In other words, only two outer sides (or surfaces) of the single-piece bonded liner material 30 are impregnated and saturated with resin. The liner composite 30 of the present invention is a fiberglass-polymer-fiberglass composite. In the past, 3 layers were stitched together. According to the present invention, the polyolefin 22 in liquid form is applied to surfaces of the fiberglass 16, 18 and they are pressed together. When the polymer 22 cools, the layers 16, 18, 22 are bonded together. The liner composite 30 can be shipped to the job site, impregnated with resin, lowered into the manhole and then heated to bond to outer fiberglass layer to the wall of the manhole.

[0036] FIG. 4 depicts a liner assembly 10, according to the exemplary embodiment of the present invention, for rehabilitating and reinforcing a host structure S after any or all of the portions of the underground support structure have deteriorated, and for lining sewage pumping stations. The liner assembly 10 comprises an inflatable liner 11, made of the liner material 30 according to the exemplary embodiment of the present invention.

[0037] Liner 11 has a continuous, preferably cylindrical, chimney section 12C configured to engage an inner peripheral surface of the chimney portion of the host structure, a continuous, preferably cylindrical, side wall (or barrel section) 12B configured to engage the inner peripheral surface of the host structure, a flattop section 5, and a bottom wall 3 configured to engage the floor of the host structure. A longitudinal axis XC of the chimney section 12C is offset relative to a longitudinal axis XBS of the barrel section 12B, as best shown in FIG. 4. The liner 11 is fluidly connected to an inflation device, such as an air pump. When inflated, the liner 11 achieves a cylindrical or prismatic shape, such as cuboid. Moreover, when inflated, the barrel section 12B contacts the inner peripheral surface of the chamber portion. As pressure increases within the liner 11, the liner 11 fully inflates. The pressurized, heated air forces the bottom wall 3 of the liner 11 towards and into engagement with the floor of the host structure.

[0038] Liner 11 may be formed from the bonded manhole liner composite 30 of the present invention so as to be complementary to the underground support structures, such as sewer and stormwater structures, and the manholes and sewage pumping stations. Respective edges of the layers of the liner material 30 plies are secured together by stitching, such as vertical liner stitches S, as shown in FIG. 4, or adhesive bonding along one or more vertical liner seams 13 and 17. The liner 11 further comprises a horizontal chimney seam 7 securing the chimney section 12Cto the flattop section 5 of the liner 11, and a horizontal barrel seam 4 securing the flattop section 5 to the barrel section 12B of the liner 11, as best shown in FIG. 4.

[0039] When applied to large round sewage pump stations or flat rectangular pumping stations, the liner material 30 is completely smooth and flat against the surfaces, free of fins or wrinkles. This improved process allows for the efficient and rapid production of custom liners. Moreover, whereas the existing membranes utilized 10 mils of solid vinyl, the membrane layer of the present invention features no less than 15 mils of synthetic membrane, offering enhanced resistance to sewer gasses and chemicals. Thus, the membrane layer 23 of the present invention is 1.5 times thicker than existing membranes. That alone gives more sewer gas resistance.

[0040] Additionally, the liner material 30 of the present invention eliminates the need for polyester felt to be embedded into the membrane layer 23. The felt of the membrane of the existing liner materials absorbs more epoxy resin, making it more costly to the installer and the end user. The felt is also not nearly as strong as fiberglass alone. The reason for the felt in the first place was to cause the layers of the existing liner materials to bond together to ensure that the membrane could not be pushed off the wall from hydrostatic head pressure of infiltration of ground water coming through the walls of the structure.

[0041] The liner material 30 of the present invention contains all of the elements of the liner provided on a roll as a single-piece material, making it more efficient to manufacture and install. This streamlines the manufacturing process by not handling three rolls of material. There are no taping edges or glue tacking edges together for handling. The membrane 23 is now at least 15 mils thick, whereas the felt / PVC membrane of the existing liner materials was 10 mils of PVC with 5 oz felt embedded into each side. The membrane layer 23 of TPO according to the present invention is thicker and is embedded into the fiberglass layers. Thus, the single-piece liner material 30 of the present invention requires less epoxy resin for installation, as it does not incorporate polyester felt fibers in its manufacture. Also, the liner made of the liner material 30 according to the present invention is easier to install and takes less resin.

[0042] The membrane layer 23 of the present invention is embedded into the fiberglass itself rather than a separate layer. The two weakest elements of the existing liner materials are the polyester felt and excess resin. The less resin used, the stronger the liner. The less polyester felt used, the stronger the liner. The fiberglass layers 16 and 20 and the membrane layer 23 are key elements to the strength, durability and success of the composite 30.

[0043] Thus, the bonded manhole liner composite 30 of the present invention significantly enhances both the manufacturing and installation processes of the liner for an underground support structure. The bonded manhole liner composite 30 of the present invention can be fabricated in the factory into a manhole liner, pumping station liner, and the like using one or more strips of liner material 30, thus reducing labor requirements. This design eliminates the need for multiple layers to be handled on the cutting table, simplifies cutting, removes the necessity for taping raw edges, and facilitates easier handling at the sewing station. During installation on-site, the liner according to the present invention can either be inflated into position or hand-laid in panels within large structures, such as rectangular sewage pump stations or large-diameter round structures.

[0044] The composite 30 is not susceptible to common / typical domestic sewer gases and, once installed, protects the structure from further deterioration. This is a significant benefit of lining sewer structures with the liner composite material 30 of the present invention. Also on all these structures, not only infiltration problems are solved, but also problems of significant deterioration from sewer gases.

[0045] The foregoing description of the exemplary embodiment of the present invention has been presented for the purpose of illustration in accordance with the provisions of the Patent Statutes. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. The embodiments disclosed hereinabove were chosen in order to best illustrate the principles of the present invention and its practical application to thereby enable those of ordinary skill in the art to best utilize the invention in various embodiments and with various modifications as suited to the particular use contemplated, as long as the principles described herein are followed. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains. Thus, changes can be made in the above-described invention without departing from the intent and scope thereof. It is also intended that the scope of the present invention be defined by the claims appended thereto.

Examples

Embodiment Construction

[0018]Reference will now be made in detail to the exemplary embodiments and exemplary methods as illustrated in the accompanying drawings, in which like reference characters designate like or corresponding parts throughout the drawings. It should be noted, however, that the invention in its broader aspects is not necessarily limited to the specific details, representative materials and methods, and illustrative examples shown and described in connection with the exemplary embodiments and exemplary methods.

[0019]This description of exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description, relative terms such as "horizontal," "vertical," "front," "rear," “upper”, “lower”, "top" and "bottom" as well as derivatives thereof (e.g., "horizontally," "downwardly," "upwardly," etc.) should be construed to refer to the orientation as then described or as shown in the drawing ...

FIELD OF THE INVENTION

[0001] The present invention relates to a liner material, particularly for an underground support structure, such as wastewater and stormwater structures, and for lining manholes and sewage pumping stations. More specifically, the present invention is directed to a bonded multilayer manhole liner, method for manufacturing the bonded multilayer manhole liner material, and method of installing the bonded multilayer manhole liner material.BACKGROUND OF THE INVENTION

[0002] Underground and above ground structures, such as sewer manholes, pump stations, wet wells, vaults, pipes, culverts and other structures, are frequently formed from brick, cement, and like cementitious and / or refractory materials. The manhole usually has a relatively long neck portion extending from the surface, and terminating in a lower sometimes flaring portion to which a sewer pipe communicates. The sewage flowing through the sewer pipe, over time, may damage the mortar which secures the bricks of the manhole together, or the cement with which the manhole is formed. Damage to the bricks and cement will permit ground water and subsurface water to infiltrate the manhole, with the result that the water treatment plant may become overloaded and unable to handle the amount of water which it receives during rain and other such occurrences. In that event, either untreated water is uncontrollably discharged, or the water treatment plant itself becomes unable to perform its function and needs to be taken out of service.

[0003] Typical sizes of manholes are 48" in diameter and overall averages 10 ft depth historically. Range, however, can be 48-72" diameter by 11-50 ft depth. Shapes also vary. Square and rectangular lift stations can be lined either with a liner inflated in place or in panels (this generally depends on the size, depth and accessibility). Lift / pump stations and wet wells also vary greatly in size and depth. For example, a lift station may be 13 ft W x 15 ft L x 35 ft D with panels. When lined with panels, they are cut 30" in width x whatever depth they need to be. A 3" overlap is allowed on each panel.

[0004] Typical sewer gas, primarily hydrogen sulfide (H2S), corrodes concrete in sewer systems because it is converted to sulfuric acid by bacteria, which then attacks the concrete in concrete structures and also attacks mortar in brick-and-mortar structures. This process of bacterial corrosion is known as microbially induced corrosion (MIC). The sulfuric acid produced by the bacteria is highly corrosive and reacts with the calcium compounds in concrete, leading to a breakdown of the concrete's structure. This corrosion can cause significant loss of concrete mass and can destroy the entire sewer structures and can also cause structural collapse, which is both dangerous and costly. H2S corrosion, produced by common sewer gas turns, concrete into powder. It basically disintegrates concrete.

[0005] Replacement of a manhole is a relatively expensive undertaking, because of the need to excavate the surrounding soil and remove the bricks and other materials. In addition, the sewer itself must continue to be usable during the procedure, or else homes and businesses will be unable to flush toilets, run taps, etc. For this reason, it is desirable to rehabilitate and / or reinforce the manhole in a way which avoids a need for replacement.

[0006] U.S. Pat. No. 5,265,981, the complete disclosure of which is incorporated herein by reference, discloses a method and apparatus for rehabilitation a manhole through use of a resin impregnated fiberglass liner which is inflated and cured in place while permitting the manhole to remain in service as it is being rehabilitated. That patent discloses the use of heated air to inflate the liner so that the surrounding walls of the manhole are engaged, after which the resin cures and secures the liner to the walls of the manhole. I have found that heated air can take a relatively long period to achieve sufficient resin cure. Particularly for deep manholes, the walls of the manhole and the surrounding soil act as a heat sink, which tends to cool the resin, so that additional time for curing is required because the surrounding material that also must be heated somewhat. However, making the existing liners and their inflation bladders totally conform to the curvatures inside structures that have flat offsets from the manhole ring and cover and chimney to the main cylinder of the structure is very difficult and problematic.

[0007] Conventionally, a manhole liner material consisting of two layers of structural fiberglass stitched to an intermediate non-porous felt membrane. The PVC membrane typically softens between 50°C / 122°F and 70°C / 158°F and melts at 160°C / 230°F. The liner, after installation and cure of the resin, achieves both a mechanical bond and an adhesive bond with epoxy resin applied to the fiberglass layers.

[0008] In view of the above, a need exists for a manhole liner material and a method for manufacturing that eliminates stitching together the fiberglass layers to the middle polymer layer, and a method for installing the resulting liner.SUMMARY OF THE INVENTION

[0009] According to a first aspect of the invention, a manhole liner composite is disclosed for rehabilitating and reinforcing a sewer structure, such as manholes. The liner composite includes a plurality of layers of a bonded liner material. Each of the layers of the bonded liner material comprises first and second structural fiberglass layers, and a polymer membrane layer disposed between the first and second structural fiberglass layers and bonding the first and second structural fiberglass layers so as to form a unitary, single-piece strip of the bonded liner material.

[0010] According to a second aspect of the invention, a method for making a manhole liner composite is disclosed for rehabilitating and reinforcing a sewer structure, such as manholes. The liner composite includes a plurality of layers of a bonded liner composite material. The method comprises the steps of separately feeding the layers of first and second structural fiberglass layers to bonding rollers, extruding a melted liquid polymer material by an applicator to flow smoothly between and over opposed surfaces of the first and second structural fiberglass layers, and pressing the first and second structural fiberglass layers and the melted liquid polymer material together by the bonding rollers, so as to effectively bond the three layers into a single-piece strip of the bonded liner composite material.

[0011] According to a third aspect of the invention, a method for installing a manhole liner for rehabilitating and reinforcing a sewer structure is disclosed. The method comprises the steps of manufacturing a strip of a bonded liner composite material, cutting the strip of the bonded liner composite material into a plurality of the strips of the bonded liner composite material, securing together the strips of the liner material to form the manhole liner composite, and making a liner complementary to the underground support structures.

[0012] Other aspects of the invention, including apparatus, devices, systems, methods, processes, and the like which constitute part of the invention, will become more apparent upon reading the following detailed description of the exemplary embodiments.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings are incorporated in and constitute a part of the specification. The drawings, together with the general description given above and the detailed description of the exemplary embodiments and methods given below, serve to explain the principles of the invention. In such drawings:

[0014] FIG. 1 is a fragmentary cross-sectional view of a bonded liner material according to an exemplary embodiment of the present invention;

[0015] FIG. 2 illustrates a process of manufacturing the bonded manhole liner material according to the exemplary embodiment of the present invention;

[0016] FIG. 3 is an enlarged view of the circled region of FIG. 2; and

[0017] FIG. 4 illustrates a liner installed in an underground support structure from the bonded liner material according to the exemplary embodiment of the present invention.DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0018] Reference will now be made in detail to the exemplary embodiments and exemplary methods as illustrated in the accompanying drawings, in which like reference characters designate like or corresponding parts throughout the drawings. It should be noted, however, that the invention in its broader aspects is not necessarily limited to the specific details, representative materials and methods, and illustrative examples shown and described in connection with the exemplary embodiments and exemplary methods.

[0019] This description of exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description, relative terms such as "horizontal," "vertical," "front," "rear," “upper”, “lower”, "top" and "bottom" as well as derivatives thereof (e.g., "horizontally," "downwardly," "upwardly," etc.) should be construed to refer to the orientation as then described or as shown in the drawing figure under discussion and to the orientation relative to a vehicle body. These relative terms are for convenience of description and normally are not intended to require a particular orientation. Terms concerning attachments, coupling and the like, such as "connected" and "interconnected," refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. The term "operatively connected" is such an attachment, coupling or connection that allows the pertinent structures to operate as intended by virtue of that relationship. The term “integral” (or “unitary”) relates to a part made as a single part, or a part made of separate components fixedly (i.e., non-moveably) connected together. Additionally, the word “a” and “an” as used in the claims means “at least one” and the word “two” as used in the claims means “at least two”.

[0020] FIGS. 1-3 depict a bonded manhole liner composite material 30 according to an exemplary embodiment of the present invention. A cohesive liner material that does not fray or unravel during cutting or sewing enables the creation of a custom-made liner L, shown in FIG. 4, for sewage manholes, pump stations, culverts, and stormwater catch basins, formed from a cementitious and / or brick material. Such structures usually have circular or a curvilinear wall defining a chamber. The resin impregnated liner L is lowered into the structure as a unit, inflated with air and heated with steam, and the resin ultimately polymerized so as to harden in situ and to bond to the circular or curvilinear wall. When utilizing steam and air pressure to cure the manhole liner L, the manhole liner L is typically cured from 180 - 200°F so the increased softening and melting point of the polymer material of the invention is advantageous for the liner L.

[0021] As shown in FIG. 1, the bonded liner material 30 includes a first structural fiberglass layer 16, a second structural fiberglass layer 20, and a non-porous, flexible and chemical-resistant membrane layer (or barrier) 23 disposed between the first and second structural fiberglass layers 16 and 20, respectively. Preferably, according to the exemplary embodiment, 24 oz. or 18 oz. structural fiberglass layers are employed on both sides of the membrane layer 23, with the selected weight based upon the size and condition of the structure to be reinforced. According to the exemplary embodiment, both the first and second structural fiberglass layers 16 and 20 are structurally identical. A thermoplastic olefin elastomer (TPO), such as SP-20010, available from ESquared, is employed for the membrane layer 23, as it offers superior chemical resistance and bonding properties compared to polyvinyl chloride (PVC).

[0022] FIGS. 2 and 3 depict a machine 14 for manufacturing the bonded manhole liner composite 30 according to the exemplary embodiment of the present invention. The bonded manhole liner composite 30 includes a first structural fiberglass layer 16, a second structural fiberglass layer 20, and a non-porous and chemical-resistant polymer membrane layer situated between the first and second structural fiberglass layers 16 and 20, respectively. Preferably, according to the exemplary embodiment, 24 oz. and 18 oz. structural fiberglass layers are employed. The weight of the layers 16 and 20 is identical, with the selected weight based upon the size of the structure to be reinforced. Preferably, a thermoplastic olefin elastomer (TPO) is employed for the membrane layer 23, as it offers superior chemical resistance and bonding properties compared to polyvinyl chloride (PVC).

[0023] The machine 14 for manufacturing the bonded manhole liner composite 30 comprises rollers 15 and 21 supplying layers of the first and second structural fiberglass layers 16 and 20, respectively. Each of the first and second structural fiberglass layers 16 and 20 passes first and second systems of feeding pulleys 18 and 19, respectively. The feeding pulleys 18 and 19 feed the first and second structural fiberglass layers 16 and 20 toward bonding rollers 261and 262, which bond the first and second structural fiberglass layers 16 and 20 with a liquid polymer material 22, as best shown in FIGS. 2 and 3, by pressing the first and second structural fiberglass layers 16 and 20 into the liquid polymer material 22. The liquid polymer material 22 is supplied from an applicator 24. The liquid polymer material 22 is formed from melted polymer pellets, with the molten material extruded between the first and second structural fiberglass layers 16 and 20 from the applicator 24. The membrane layer 23 is no less than 10 mils thick, although a minimum of 15 mils is preferred to assure a mechanical bond with the fiberglass of fiberglass layers 16 and 20 and the solidified polymer of membrane 23. According to the exemplary embodiment, the polymer pellets are melted in the applicator 24, and the melted polymer is maintained in the applicator 24 at 350-400°F and applied preferably at 370°F. The liquid polymer material 22 cools and solidifies after the fiberglass layers 16 and 20 have been impressed into it by the rollers, and the solidified polymer forms the impermeable membrane layer 23 that is a non-porous and chemical-resistant membrane layer of the bonded manhole liner composite 30. The impermeable membrane 30 preferable is 15 mils thick. The thickness of the membrane 23 increases the resistance to sewer gas.

[0024] A process of manufacturing the bonded manhole liner composite 30 follows.

[0025] First, the rollers 15 and 21 separately supplying the layers of the first and second structural fiberglass layers 16 and 20, respectively, are provided. The first and second structural fiberglass layers 16 and 20 are separately fed toward the bonding rollers 261and 262, by the first and second feeding pulleys 18 and 19, respectively. Immediately before the fiberglass layers 16 and 20 are pressed toward each other by the bonding rollers 261and 262, the liquid polymer material 22 is extruded from applicator 24, allowing the melted thermoplastic polyolefin to flow smoothly between and over the opposed surfaces of the first and second structural fiberglass layers 16 and 20. The melted polymer material 22 solidifies upon cooling, forming a continuous, uninterrupted membrane layer 23. Preferably the membrane layer 23 is at least 15 mils 0.0 inch (one mil is one thousandth of an inch) thick, which is sufficient to secure the fiberglass within the polymer material without creating openings that would allow passage of fluids, air, steam, and the like. The membrane 23 is sufficiently thick to accommodate the fiberglass bonded to the opposite sides thereof.

[0026] The thermoplastic polyolefin (TPO) membrane barrier 23 is produced by extrusion coating of the TPO resin into a homogenous film before adhering onto the fiberglass layers 16 and 20. The hot melt process is designed to achieve a high level of adhesion of the TPO membrane barrier 23 without adhesives. The TPO polyolefins resins balance flexibility, impact strength and higher melting point (142°C / 287°F, DSC method) to withstand the CIPP (i.e.,cured-in-place-pipe) curing process. An inflatable liner 11 of the present invention is a cured-in-place liner. CIP is a term commonly used in the industry meaning cured-in-place. The softening point of the membrane barrier 23 is between 70°C / 158°F and 80°C / 176°F.

[0027] The material layers 16, 20, 22 are pressed together using the bonding rollers 261and 262, effectively bonding the three layers 16, 20, 22 into a single-piece strip of bonded manhole liner composite (or a cohesive one-ply liner fabric) 30 that does not fray or unravel during cutting or sewing, enabling the creation of custom-made liners for sewage manholes, pump stations, culverts, or stormwater catch basins. When the fiberglass layers 16 and 20 are juxtaposed to the liquid polymer material 22, not all of the fiberglass of layers 16 and 20 are immersed into it. When the liquid polymer material 22 cools, it solidifies and fiberglass of layers 16 and 20 are now attached, with the result that a one-piece composite is created As a result, a small portion of the fiberglass of layers 16 and 20 is submerged (or immersed) in liquid polymer material 22 that later solidifies and becomes the solidified membrane layer 23, as indicated by overlaps 25 in FIG. 1.

[0028] As noted above, the thermoplastic polyolefin (TPO) membrane barrier is produced by extrusion of the TPO resin onto the fiberglass layers, resulting in a homogenous film adhering to the first and second fiberglass layers 16, 20 and their fibers. The thermoplastic polyolefin (TPO) employed in the exemplary embodiment is a polymer blend that provides a balance between pliability and impact resistance along with the thermal resistance. An exemplary TPO is available from ESquared of Hillside, New Jersey as product SP-20010. The hot melt extrusion process achieves a high level of adhesion of the TPO to the fiberglass layers without requiring adhesives, stitching or similar mechanisms for binding the TPO to the fiberglass.

[0029] The ratio of fluid polymer to fiberglass is as follows:

[0030] a. two layers of 47.40 OSY (ounces per square yard) FG (fiberglass) each = 94.8 OSY total FG weight 8.61 to 1 ratio (the 47.4 number = 5600 series liner - lighter fiberglass weight);

[0031] b. two layers of 60.60 OSY FG each = 121.2 OSY total FG weight 11 to 1 ratio (the 60.60 number = our 6800 series liner - heavier weight fiberglass).

[0032] In weight 11 ounces (15 mils) of polymer is applied.

[0033] The resulting liner composite 30 reduces the time required for pulling, cutting and stitching the layers together. Taping and gluing individual layers has been eliminated completely. The resulting bonded manhole liner composite 30 may be rolled through guide rollers 27 onto a new larger spool 32, where it may then be used in the manufacturing of liners L using bonded liner material 30, as illustrated in FIG. 4. The bonded liner material 30 may be saturated onsite with resin and overlapped to form a single monolithic structure, with fewer fins or wrinkles resulting from using a single-piece ply material. The bonded material 30 of the present invention requires less epoxy resin to fully saturate than the existing liner materials, as a result of the elimination of felt fibers imbedded in the membrane of existing liner materials. Specifically, existing liners require approximately 1.3 times more resin to saturate than the disclosed composite 30. This is likely caused by the fiberglass felt used in prior art liners. The fiberglass felt fibers absorbed a lot of resin. The liner composite 30 according to the present invention has no felt and therefore requires less epoxy resin to saturate, yielding a stronger composite after curing in place.

[0034] Thus, the three separate pieces 16, 20, 23 are transformed into a single-piece bonded material 30. What was two layers of fiberglass fabric 16 and 20 and liquid polymer material 22 are transformed into one single piece of bonded material 30. The fiberglass fabrics 16 and 20 are partially immersed into the heated liquid polymer material 22. The heated liquid polymer material 22, after cooling, becomes the non-porous membrane 23. Particularly, as the heated liquid polymer material 22 cools, it solidifies and the fiberglass layers 16 and 20 and the membrane layer 23 become a unitary, one-piece (or single-piece) bonded material 30. Curing of the liner is a matter of time and temperature. The liner may be ambient cured, especially when lining large flat surfaces, such as found in square pumping stations.

[0035] At least one, and typically both, of two opposite surfaces of the single-piece 3-ply bonded liner material 30 of the present invention may later be impregnated with resin and heat-bonded to the walls of the manhole or structure to be reinforced. In other words, only two outer sides (or surfaces) of the single-piece bonded liner material 30 are impregnated and saturated with resin. The liner composite 30 of the present invention is a fiberglass-polymer-fiberglass composite. In the past, 3 layers were stitched together. According to the present invention, the polyolefin 22 in liquid form is applied to surfaces of the fiberglass 16, 18 and they are pressed together. When the polymer 22 cools, the layers 16, 18, 22 are bonded together. The liner composite 30 can be shipped to the job site, impregnated with resin, lowered into the manhole and then heated to bond to outer fiberglass layer to the wall of the manhole.

[0036] FIG. 4 depicts a liner assembly 10, according to the exemplary embodiment of the present invention, for rehabilitating and reinforcing a host structure S after any or all of the portions of the underground support structure have deteriorated, and for lining sewage pumping stations. The liner assembly 10 comprises an inflatable liner 11, made of the liner material 30 according to the exemplary embodiment of the present invention.

[0037] Liner 11 has a continuous, preferably cylindrical, chimney section 12C configured to engage an inner peripheral surface of the chimney portion of the host structure, a continuous, preferably cylindrical, side wall (or barrel section) 12B configured to engage the inner peripheral surface of the host structure, a flattop section 5, and a bottom wall 3 configured to engage the floor of the host structure. A longitudinal axis XC of the chimney section 12C is offset relative to a longitudinal axis XBS of the barrel section 12B, as best shown in FIG. 4. The liner 11 is fluidly connected to an inflation device, such as an air pump. When inflated, the liner 11 achieves a cylindrical or prismatic shape, such as cuboid. Moreover, when inflated, the barrel section 12B contacts the inner peripheral surface of the chamber portion. As pressure increases within the liner 11, the liner 11 fully inflates. The pressurized, heated air forces the bottom wall 3 of the liner 11 towards and into engagement with the floor of the host structure.

[0038] Liner 11 may be formed from the bonded manhole liner composite 30 of the present invention so as to be complementary to the underground support structures, such as sewer and stormwater structures, and the manholes and sewage pumping stations. Respective edges of the layers of the liner material 30 plies are secured together by stitching, such as vertical liner stitches S, as shown in FIG. 4, or adhesive bonding along one or more vertical liner seams 13 and 17. The liner 11 further comprises a horizontal chimney seam 7 securing the chimney section 12Cto the flattop section 5 of the liner 11, and a horizontal barrel seam 4 securing the flattop section 5 to the barrel section 12B of the liner 11, as best shown in FIG. 4.

[0039] When applied to large round sewage pump stations or flat rectangular pumping stations, the liner material 30 is completely smooth and flat against the surfaces, free of fins or wrinkles. This improved process allows for the efficient and rapid production of custom liners. Moreover, whereas the existing membranes utilized 10 mils of solid vinyl, the membrane layer of the present invention features no less than 15 mils of synthetic membrane, offering enhanced resistance to sewer gasses and chemicals. Thus, the membrane layer 23 of the present invention is 1.5 times thicker than existing membranes. That alone gives more sewer gas resistance.

[0040] Additionally, the liner material 30 of the present invention eliminates the need for polyester felt to be embedded into the membrane layer 23. The felt of the membrane of the existing liner materials absorbs more epoxy resin, making it more costly to the installer and the end user. The felt is also not nearly as strong as fiberglass alone. The reason for the felt in the first place was to cause the layers of the existing liner materials to bond together to ensure that the membrane could not be pushed off the wall from hydrostatic head pressure of infiltration of ground water coming through the walls of the structure.

[0041] The liner material 30 of the present invention contains all of the elements of the liner provided on a roll as a single-piece material, making it more efficient to manufacture and install. This streamlines the manufacturing process by not handling three rolls of material. There are no taping edges or glue tacking edges together for handling. The membrane 23 is now at least 15 mils thick, whereas the felt / PVC membrane of the existing liner materials was 10 mils of PVC with 5 oz felt embedded into each side. The membrane layer 23 of TPO according to the present invention is thicker and is embedded into the fiberglass layers. Thus, the single-piece liner material 30 of the present invention requires less epoxy resin for installation, as it does not incorporate polyester felt fibers in its manufacture. Also, the liner made of the liner material 30 according to the present invention is easier to install and takes less resin.

[0042] The membrane layer 23 of the present invention is embedded into the fiberglass itself rather than a separate layer. The two weakest elements of the existing liner materials are the polyester felt and excess resin. The less resin used, the stronger the liner. The less polyester felt used, the stronger the liner. The fiberglass layers 16 and 20 and the membrane layer 23 are key elements to the strength, durability and success of the composite 30.

[0043] Thus, the bonded manhole liner composite 30 of the present invention significantly enhances both the manufacturing and installation processes of the liner for an underground support structure. The bonded manhole liner composite 30 of the present invention can be fabricated in the factory into a manhole liner, pumping station liner, and the like using one or more strips of liner material 30, thus reducing labor requirements. This design eliminates the need for multiple layers to be handled on the cutting table, simplifies cutting, removes the necessity for taping raw edges, and facilitates easier handling at the sewing station. During installation on-site, the liner according to the present invention can either be inflated into position or hand-laid in panels within large structures, such as rectangular sewage pump stations or large-diameter round structures.

[0044] The composite 30 is not susceptible to common / typical domestic sewer gases and, once installed, protects the structure from further deterioration. This is a significant benefit of lining sewer structures with the liner composite material 30 of the present invention. Also on all these structures, not only infiltration problems are solved, but also problems of significant deterioration from sewer gases.

[0045] The foregoing description of the exemplary embodiment of the present invention has been presented for the purpose of illustration in accordance with the provisions of the Patent Statutes. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. The embodiments disclosed hereinabove were chosen in order to best illustrate the principles of the present invention and its practical application to thereby enable those of ordinary skill in the art to best utilize the invention in various embodiments and with various modifications as suited to the particular use contemplated, as long as the principles described herein are followed. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains. Thus, changes can be made in the above-described invention without departing from the intent and scope thereof. It is also intended that the scope of the present invention be defined by the claims appended thereto.

Examples

Embodiment Construction

[0018]Reference will now be made in detail to the exemplary embodiments and exemplary methods as illustrated in the accompanying drawings, in which like reference characters designate like or corresponding parts throughout the drawings. It should be noted, however, that the invention in its broader aspects is not necessarily limited to the specific details, representative materials and methods, and illustrative examples shown and described in connection with the exemplary embodiments and exemplary methods.

[0019]This description of exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description, relative terms such as "horizontal," "vertical," "front," "rear," “upper”, “lower”, "top" and "bottom" as well as derivatives thereof (e.g., "horizontally," "downwardly," "upwardly," etc.) should be construed to refer to the orientation as then described or as shown in the drawing ...

Claims

1. A manhole liner composite for rehabilitating and reinforcing a sewer structure, the liner composite includes a plurality of strips of a bonded liner material, each of the strips of the bonded liner material comprising:first and second structural fiberglass layers; anda membrane layer disposed between the first and second structural fiberglass layers and bonding the first and second structural fiberglass layers to form a unitary, single-piece strip of the bonded liner material.

2. The manhole liner composite as defined in claim 1, wherein the membrane layer is a non-porous, flexible and chemical-resistant membrane layer.

3. The manhole liner composite as defined in claim 2, wherein the membrane layer is made of a thermoplastic polyolefin.

4. The manhole liner composite as defined in claim 3, wherein the thermoplastic polyolefin has a melting point of 140 C° to 145 C°.

5. The manhole liner composite as defined in claim 4, wherein the membrane layer is at least 15 mils thick.

6. The manhole liner composite as defined in claim 1, wherein a portion of each of the layers of fiberglass is immersed into the membrane layer.

7. The manhole liner composite as defined in claim 6, wherein the membrane layer overlaps each of the layers of fiberglass.

8. The manhole liner composite as defined in claim 1, wherein each of the first and second structural fiberglass layers has weight of 47.40 OSY or 60.60 OSY.

9. The manhole liner composite as defined in claim 1, wherein at least one of two opposite surfaces of the single-piece bonded liner material of the present invention is impregnated with resin.

10. The manhole liner composite as defined in claim 1, wherein the plurality of strips of bonded liner material are stitched together along edges of the strips of the liner material to form the manhole liner composite.

11. A method for making a manhole liner composite for rehabilitating and reinforcing a sewer structure, the liner composite includes a plurality of layers of a bonded liner composite material, the method comprising the steps of:separately feeding the layers of first and second structural fiberglass layers to bonding rollers;extruding a melted liquid polymer material by an applicator between and over opposed surfaces of the first and second structural fiberglass layers; andpressing the first and second structural fiberglass layers and the melted liquid polymer material together to bond the three layers into a single-piece strip of bonded liner composite material.

12. The method as defined in claim 11, further comprising the step of solidifying the melted liquid polymer material between the first and second structural fiberglass layers, the solidified liquid polymer material defining a membrane layer of a bonded liner composite material.

13. The method as defined in claim 11, wherein each of the strips of first and second structural fiberglass layers is separately fed to the bonding rollers by first and second feeding pulleys.

14. The method as defined in claim 11, wherein the melted liquid polymer material is maintained in the applicator at 350-400°F.

15. The method as defined in claim 11, wherein the melted liquid polymer material is a thermoplastic polyolefin.

16. The method as defined in claim 15, wherein the thermoplastic polyolefin has a melting point of 140 C° to 145 C°.

17. The method as defined in claim 11, wherein a portion of each of the layers of fiberglass is immersed into the liquid polymer material.

18. The method as defined in claim 12, wherein the solidified membrane layer is at least 15 mils thick.

19. The method as defined in claim 11, wherein each of the first and second structural fiberglass layers has weight of 47.40 OSY or 60.60 OSY.

20. The method as defined in claim 11, further comprising the step of impregnating at least one of two opposite surfaces of the single-piece bonded liner material with resin.

21. A method for installing a manhole liner for rehabilitating and reinforcing a sewer structure, the method comprising the steps of:manufacturing a strip of a bonded liner composite material;cutting the strip of the bonded liner composite material into a plurality of the strips of the bonded liner composite material;securing together the strips of the liner material to form the manhole liner composite; andinstalling the liner complementary to the underground support structure.

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