Apparatus And Method For Ballast Leachate Evaporation For Exposed Landfill Covers

Abstract

The invention disclosed herein includes apparatus and a method for collecting leachate and storing it to provide ballast on top of landfill covers at a landfill. A control berm is built on top of the exposed landfill cover forming a barrier for ponding leachate. Leachate is collected from the waste interred at the landfill through known leachate collection system methods and apparatus and transported for deposit on the top surface of a landfill cover thereby resulting in the impoundment and ponding of the leachate on top of the landfill cover and providing ballast to keep the landfill cover in place and minimizing, if not preventing, wind uplift or shearing of the cover.

Description

BACKGROUND

The use of Exposed Geomembrane Covers (EGC) has been implemented throughout the various waste handling and management industries as temporary or final covers placed on top and around landfills in the early 1990's. They have been designed and installed in landfill environments using various material types of geomembranes, liners, and even artificial turf. One major issue, concern, and design challenge is proper anchoring and ballast to protect the ballast covers from damage, partial or complete dislodgement due to wind uplift. Current methods for protecting and securing EGC ballast covers from wind uplift is expensive and does not serve any other need. Due to the high cost of installation and ballast covers plus other design challenges landfill owners and operators are skeptical to the use of exposed ballast covers. The invention disclosed herein provides incentives to promote the installation and use of leachate ballast covers or modification of existing exposed ballast covers while providing advantages as described herein.

The collection and removal of liquid leachate in leachate evaporator ponds has been successfully used at landfill facilities and in industries handling contaminated liquids in arid and very dry areas of the United States where liquid evaporation is at its highest potential. However, at times available land for the location and construction of a leachate pond is limited or not available or where there are state and local permitting challenges. The concept and invention disclosed herein resolve the design challenges of exposed cover ballast and available land for leachate ponds. The invention will allow landfill facilities to store leachate on-top of existing landfill waste footprints to create more effective ballast on the surface of exposed landfill covers and in-turn more efficient evaporation of leachate due to an increase in the surface area of the liquid exposed to the atmosphere. This new ballast design and method for EGC or other landfill covers allows owners and operators of waste facilities to increase the amount and rate of leachate evaporation while avoiding third party construction, transportation and handling costs associated with the collection, removal, transportation, and off-site disposal of leachate. The invention reduces the cost of expensive anchoring and ballast for traditional exposed covers of geomembrane or artificial turf and significantly off-sets significant transportation and rising treatment costs at wastewater treatment plants (WWTP). The invention can also be retrofitted to any approved landfill final closure cover or temporary closure cover.

The invention disclosed herein provides an alternative to the handling of leachate and treatment of contaminated liquids that are proving to be huge issues for landfill facilities. Recent environmental concerns of handling leachate producing increasing amounts of perfluoroalkyls and polyfluoroalkyls substances (PFAS), foam, odor, and other contaminates have resulted in WWTP's rejecting further treatment. Additionally, current leachate evaporator pond designs and functions are at times inadequate and have various limitations. The inventive embodiments of the leachate ballast exposed covers disclosed herein provide the environmental industry with solutions to exposed cover ballast design issues and leachate treatment concerns that are cost effective while maintaining landfill compliance. The inventive embodiments provide improved solutions that are economical, operationally friendly and effective.

SUMMARY OF INVENTION

The invention disclosed herein includes apparatus and a method for collecting leachate and storing it to provide ballast on top of exposed landfill covers at a landfill. A control berm is built on top of the exposed landfill cover forming a barrier for ponding leachate liquid. Leachate is collected from the waste interred at the landfill through known leachate collection system methods and apparatus and transported or deposited on the top surface of a landfill cover thereby resulting in the impoundment and ponding of the leachate on top of the landfill cover and providing ballast to keep the landfill cover in place and minimizing, if not preventing, wind uplift or shearing of the cover. By impounding and storing the leachate liquid in this fashion, the surface area of the leachate and air boundary interface is greatly increased over typical sized retention ponds, thereby providing for increased evaporation rates of leachate. As leachate is evaporated, additional liquid leachate may be transferred to the impoundment area on top of the cover providing the ability for continuous evaporation operations, while also maintaining ballast for preventing wind uplift, wind shear, or other damage to the landfill cover on which the liquid leachate is impounded.

By incorporating the disclosed ballast leachate evaporation apparatus and method with existing and proposed waste site designs, waste site owners can now benefit by installing EGC earlier to capture savings from leachate treatment. This cost savings approach to increase stability for exposed covers can off-set all exposed cover costs through eliminating third party treatment, transportation, and disposal of on-site leachate. By creating this incentive earlier in operation, owners can also show earlier benefits resulting from: better methane gas collection, reduced leachate generation, reduced carbon dioxide (CO2) and greenhouse gas emissions and reduced landfill gas odors. The ponded leachate as part of the ballast located on top of the existing landfill can be retrofitted and pumped directly into current leachate recirculation trenches. This invention also allows new horizontal or vertical leachate recirculation trenches and to be installed under the evaporation ponds where the ballast leachate is pumped into the recirculation trenches to additionally control off-site costs and treatment.

The details of one or more implementations are set forth in the drawings included in this application and which are further described below. Other features, objects, and advantages of the inventive embodiments disclosed herein will be apparent from the description and figures.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of this disclosure and its features, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a cross-sectional view of a typical landfill with an embodiment of the ballast leachate evaporation apparatus and method according to the present disclosure;

FIG. 1A illustrates a magnified cross-section view of a control berm installation at a typical landfill with an embodiment of the ballast leachate evaporation apparatus and method according to the present disclosure;

FIG. 2 illustrates a cross-section of a typical landfill with an embodiment of the ballast leachate evaporation apparatus and method according to the present disclosure; and,

FIG. 3 illustrates a cross-section of a typical landfill with a top ballast/control berm embodiment of the ballast leachate evaporation apparatus and method according to the present disclosure.

DETAILED DESCRIPTION

FIG. 1 depicts a cross-section view of a typical landfill 10 with a previously installed base liner 20 and top or exposed cover 30, which may also be referred to as final cover. In an embodiment, berm 40 or multiple or multiple berms 40 are placed on a portion of the top cover to form an evaporator pond 50 providing for the impoundment of liquid leachate or other fluids on a top of landfill 10. In the depicted embodiment, liquid leachate 45 is impounded in evaporator pond 50 to a desired depth which operates to provide ballast weight to restrict, if not remove, the effect of wind uplift or wind shear from tearing or damaging top cover 30. The impounded leachate 45 contained in evaporator pond 50 is exposed to atmosphere and is evaporated. As leachate 60 evaporates from pond 50, additional leachate collected from landfill 10 or any other available source may be pumped or deposited into pond 50 to maintain ballast weight on top cover 30 and for continuous evaporative operations.

Control berm 40 may be formed or constructed from clay material, sand, soil, rubble, waste materials, asphalt plastics, metals, concrete or other known materials capable of being formed into berm 40 for the purpose of creating an evaporative pond for impounding leachate, water and other fluids 45 for the apparatus and method disclosed in this application. Berm 40 may be formed as desired and covered with a berm liner 22 (as shown in FIG. 1A) to assist in retaining the berm 40 shape and position, as well as acting to prevent seepage or transmission of leachate 45 into berm 40.

FIG. 1A is a magnified cross-section view of control berm 40 constructed on top of cover 30 which overlays landfill 10. Berm 40 may be formed or constructed from clay material, sand, soil, rubble, waste materials, asphalt plastics, metals, concrete or other known materials capable of being formed into berm 40 for the purpose of creating an evaporative pond for impounding leachate, water and other fluids 45 for the apparatus and method disclosed in this application. Berm 40 may be formed as desired and covered with a berm liner 22 to assist in retaining the berm 40 shape and position, as well as acting to prevent seepage or transmission of leachate 45 into berm 40. Piping and/or Trenches 70 may be located in landfill 10 and acts to collect landfill gas from under pond 50 from landfill 10. Piping or Trenches 70 may also be used for leachate recirculation were liquid leachate 45 is pumped from the evaporation pond 50 and distributed back into landfill 10 (known in the industry as Leachate Recirculation). Liquid leachate 45 that is collected from the base liner 20 or Landfill 10 or from other on-site leachate storage or treatment areas is pumped, drained or otherwise directed into pond 50 to act as ballast on top of cover 30. In the depicted embodiment, berm weld 60 is placed along the outer side of the berm 40 around the outer periphery of berm 40. Berm weld 60 provides additional stabilization to berm 40 while also acting as a ballast to retain berm liner 22 in place relative to cover 30 and protecting the edges and portions of berm liner 22 from the effects of wind, wind uplift and other environmental exposure. Berm 40 may be formed or constructed from clay material, sand, soil, rubble, waste materials, asphalt plastics, metals, concrete or other known materials capable of being formed into berm 40. Berm weld 60 shall be constructed and formed with known industry technology used to join and connect berm liner 22 to cover 30.

FIG. 2 is a cross-section view of a typical landfill with exposed cover 32 covering an excavated pond 50 on top of landfill 10. In the depicted embodiment, pond 50 is formed on a top surface of landfill 10 using existing landfill 10 material as berms for creating the sidewalls of pond 50. Exposed cover 32 is anchored into landfill 10 forming an impenetrable fluid barrier for impounding leachate 45 or other fluids in pond 50. A second cover 30 covers the sloped sides of landfill 10. Piping may be located in landfill 10 and acts to collect and drain leachate 45 and/or other fluids and gases from landfill 10 for collection in one or more storage tanks, ponds or other containment vessels. Liquid leachate 45 by then be pumped, drained or otherwise transferred into pond 50 to act as ballast on top of cover 32. The impounded leachate 45 contained in evaporator pond 50 is exposed to atmosphere and is evaporated. As leachate 45 evaporates from pond 50, additional leachate collected from landfill 10 or any other available source may be pumped or deposited into pond 50 to maintain ballast weight on cover 32 and for continuous evaporative operations. In an embodiment, a leachate recirculation system 90 may be used to distribute and recirculate leachate 45 from pond 50 and back into landfill 10 via piping 96. Leachate 45 is distributed into one or more horizontal or vertical trenches 91 which include fill material 92 which allows for leachate to infiltrate and collect into trenches 91 and then migrate into landfill 10. Fill material 92 may comprise a variety of suitable materials such as shredded tire chips, gravel or other porous media placed into trenches 91 during construction of trenches 91. Piping 94 transports leachate 45 into the trenches 91 of leachate recirculation system 90 for migration and percolation of leachate 45 into landfill 10. In an embodiment, pipe inlet 96 is positioned to allow for attachment of a pump or other mechanical mechanism to intake and transmit leachate 45 residing in pond 50 into piping 94 via pipe inlet 96. In an embodiment, pipe inlet 96 is positioned above the liquid surface of leachate 45 residing in pond 50, so when pump operations are stopped the elevation pressure differential prevents suction pressure from potentially reversing the flow of leachate 45 back into pond 50 due to siphoning. Gravity flow or mechanical pumping apparatus may be used to transport leachate 45 from pond 50 into trenches 91 of leachate recirculation system 90 for migration and percolation of leachate 45 into landfill 10 as is commonly known in the art as “leachate recirculation.”

FIG. 3 is a cross-sectional view of control berm 40 constructed on top of cover 30 which overlays landfill 10. Berm 40 may be formed or constructed from clay material, sand, soil, rubble, waste materials, asphalt plastics, metals, concrete or other known materials capable of being formed into berm 40 for the purpose of creating an evaporative pond for impounding leachate, water and other fluids 45 for the apparatus and method disclosed in this application. Berm 40 may be formed as desired and covered with a berm liner 22 to assist in retaining the berm 40 shape and position, as well as acting to prevent seepage or transmission of leachate 45 into berm 40. A top berm 42 may be constructed along the top central portion of landfill 10 and may be formed or constructed from clay material, sand, soil, rubble, waste materials, asphalt plastics, metals, concrete or other known materials capable of being formed into top berm 42 for the purpose of creating two or more evaporative ponds for impounding leachate, water or other fluids 45 according to the apparatus and method disclosed in this application. Piping may be located in landfill 10 and acts to collect and drain leachate 45 and/or other fluids and gases from landfill 10 for collection in one or more storage tanks, ponds or other containment vessels. Liquid leachate 45 by then be pumped, drained or otherwise transferred into directed into ponds 80,82 to act as ballast on top of cover 30. In the depicted embodiment, berm weld 60 is placed along the outer side of the berm 40 around the outer periphery of berm 40. A berm weld (as shown in FIG. 1A) may also be utilized to provide additional stabilization to berm 40 while also acting as a ballast to retain berm liner 22 in place relative to cover 30 and protecting the edges and portions of berm liner 22 from the effects of wind, wind uplift and other environmental exposure. Berm weld 60 shall be constructed and formed with known industry technology used to join and connect berm liner 22 to cover 30.

Additional waste treatment options may be used in conjunction with the various embodiments of the invention disclosed herein. For example, precipitates, dissolved solids or suspended solids remaining in pond 50 after liquid leachate 45 has evaporated may be removed by the landfill operator and taken to a waste treatment facility for further processing or landfilling. Optionally, leachate 45 collected from landfill 10, and prior to transfer into pond 50, may be treated with known wastewater treatment techniques such as filtration, rapid sand filtration, cartridge, and/or activated carbon filtration to treat leachate 45 prior to impoundment in evaporative pond 50. Such pre-impoundment processing would assist in the removal and recovery of suspended and dissolved solids from leachate 45 and reduce the volume of suspended and dissolved solid residue that collects on in the pond 50 after evaporation of liquid leachate 45.

Additional leachate treatment options may be used in conjunction with the various embodiments of the invention disclosed herein. For example, ponded leachate used as ballast to the evaporation ponds may be pumped from the ponds to enhance leachate recirculation were approved at any such waste facility. The ponded ballast leachate will be controlled and pumped to any currently installed leachate recirculation systems. Additionally, new leachate recirculation horizontal trenches or vertical trenches can be installed under and prior to the Ballast Leachate Evaporation Exposed Landfill Cover. A piping system and network will distribute the pumped ballast leachate into the leachate recirculation system.

Additional leachate evaporation treatment options may be used in conjunction with the various embodiments of the invention disclosed herein. For example, incorporating Enhanced Leachate Evaporation with Heat Induced Acceleration Process options as disclosed in U.S. Provisional Patent Application Ser. No. 63/092,311 filed Oct. 15, 2020, and entitled “ Enhanced Leachate Evaporation Heat Induced Acceleration Process” the disclosure of which has been incorporated by reference herein. These enhanced heat induced options include heat generated from one or more heat sources such as lamps, industrial high strength lights, heated air captured from landfill gas flare operations, flame/flare fueled from landfill gas or natural gas, which are proximally located to the leachate pond to accelerate evaporation of the leachate contained in the leachate pond.

It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in this specification, the singular forms “a”, “an” and “the” include plural referents unless the content clearly indicates otherwise.

Although the present disclosure has been described in detail, various changes, substitutions, and alterations may be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure.

Claims

1. A leachate treatment ballast system comprising: a leachate pond for impounding a leachate comprising one or more berms located on a top surface of a top cover covering a portion of a landfill wherein the leachate in the leachate pond provides ballast weight to substantially retain the top cover in place on the covered portion of the landfill.

2. The system of claim 1 further wherein the leachate pond comprises one or more trenches formed in a portion of the landfill.

3. The system of claim 1 further comprising: piping to collect leachate, gas or other fluids located within the landfill.

4. The system of claim 1 further comprising: at least one heat source to accelerate evaporation of the leachate impounded in the leachate pond.

5. The system of claim 1 further comprising: a leachate collection system wherein at least one trench located within a portion of the landfill receives leachate which is transported via piping from the leachate pond.

6. The system of claim 6 wherein the trench is filled with one of a gravel or a chipped tire pieces.

7. The system of claim 6 further comprising piping located within the trench.

8. The system of claim 1 further comprising a top berm located along a top central portion of the landfill.

9. The system of claim 1 further comprising a berm weld.

10. The system of claim 1 further comprising a berm liner.

11. The system of claim 1 further comprising at least one enhanced heat source for exposing heat energy to the leachate pond for accelerating leachate evaporation.