DEVICE FOR THE INSTALLATION OF VACUUM CONSOLIDATION DEWATERING HORIZONTAL DRAINS FOR DEWATERING SLUDGE PONDS

Abstract

A device for installing horizontal drains in a coal combustion residual or other sludge pond consists of a trenching device that extends downwardly to the depth of required installation of the drains and an attachment through which the drains are fed during installation. The trenching device and attachment are mounted onto a carrier for floatation of the required equipment on the surface of a water-filled sludge pond. The carrier can be winched, hauled or driven across the surface of the sludge. A hydraulic system may be used to raise and lower the trenching device and attachment. The trenching device may be equipped with a chain driven blade mechanism or dredging device for the purpose of cutting a trench into the pond sludge, and a vibratory trenching device may be used to effectively liquefy the material to make the trenching device easier to pull or tow through the sludge in the pond.

Description

FIELD OF INVENTION

This invention relates to a device for the installation of horizontal drains below the surface of a sludge pond for the purpose of removing the water from (dewatering) the sludge. Various methods of using horizontal drains for dewatering sludge are generally known in the art and are referred to here as vacuum consolidation dewatering (VCD). This invention will describe a device used to install the drains below the surface of the sludge pond for the purpose of applying VCD.

BACKGROUND OF THE INVENTION

A variety of industries produce waste from operating processes that are accumulated in sludge ponds or tailing ponds, for example, coal combustion residuals (CCR) sediments in disposal ponds or impoundments. These ponds may require dewatering to mitigate their impact on the neighboring environment and human or animal health. Frequently local, state and federal governments may regulate aspects of managing these ponds and, in the case of CCR ponds, closure is also now required by U.S. environmental regulation.

CCR is known to be unstable when saturated. When saturated CCR is subject to shear strain, it densifies and expels water, resulting in a near total loss of shear strength. In this state, the material becomes a viscous fluid and may begin to slide or flow. This process may result in overtopping of impoundments and makes excavation and handling difficult to impossible. Reducing the water content of the CCR material by only a few percentage points has a dramatic effect on its behavior, allowing stable, near vertical cuts suitable for mass excavation.

Therefore, to facilitate closure, the ponds are sometimes dewatered by pre-drainage of the sludge to enhance strength and stability of the material and thereby provide a stable surface on which to operate earthmoving and grading equipment. VCD is one option for dewatering the sludge.

A typical VCD system consists of prefabricated drains made from plastic cores with a geotextile envelope or perforated plastic pipe or tube surrounded by a geotextile envelope, installed horizontally at a near-coplanar depth below the surface of the sludge pond. The drains are installed in a pattern throughout the area of the sludge pond that is to be dewatered. Herein is described a novel device useful in installing the horizontal drains.

SUMMARY OF THE INVENTION

A device that can be used to install horizontal drains in a sludge pond consists of a plow or other trenching device that extends to the depth of required installation into the pond and an attachment through which the drains are fed during installation. The trenching device and attachment are mounted onto a carrier that is capable of floating all of the associated equipment on the surface of a saturated and/or water-filled sludge pond, and can be winched or hauled across the surface of the sludge by winching devices. Various embodiments of the device may have a hydraulic system to raise and lower the trenching device apparatus and also, or alternatively, may include equipment for generating the power required to operate the hydraulic system.

Some embodiments of the device of the present invention include a location to carry the drain to be installed and storage for the required tools and hoses or pipes for connecting the drains to the vacuum and water pump unit that is part of the VCD system located near the drain installation area. In some embodiments, the device will also include a protected operator cab where the operator can either control the winches, or communicate with support staff. In such embodiments, the protected cab should provide adequate protection for the operator in the event that the winch cable should break.

In some embodiments the device could be towed behind suitable mechanized pond-compatible equipment in place of being moved by winches. A suitable hitching mechanism would be added to the device so that it could be connected to or trailed behind a pond-compatible mechanized vessel.

In some embodiments, the trenching device could have a chain driven blade mechanism or trenching device for the purpose of cutting a trench into the pond sludge. This embodiment could provide a reduced energy requirement of the equipment towing or of the winches pulling the VCD installation device across the surface of the sludge pond. The use of a blade mechanism or trencher may enable moving the device during installation (i.e., if the sludge is too hard or too solid, the towing equipment or the winches may be unable to move the trenching device across the pond, the chain trencher will solve that problem). A vibratory plow or trenching device may be used to effectively liquefy the material to make the trenching device easier to pull or tow through the sludge in the pond. This modification includes a vibrating device mounted to the shaft of the trenching device to vibrate the shaft during installation which will liquefy the sludge material of the pond making it easier to pull or tow the trenching device through the sludge.

Additionally in some embodiments, the carrier may have tracks to aid in moving the VCD installation device across dry sections of sludge rather than dragging the carrier across the sludge surface. These tracks may or may not be mechanized or self-propelled.

In yet another embodiment, the VCD installation device may include the simultaneous installation of drains at multiple depths in the sludge below the pond surface. Some ponds may be more effectively drained by the installation of drains at multiple depths below the surface. The trenching device may be modified to include the option of installing drains at different depths, for example, one drain may be installed at a depth of ten feet below the surface and a second drain at five feet below the surface.

Alternately, the trenching device may be modified to install drains at more than two depths below the surface simultaneously (i.e., drains could conceivably be installed every foot below the surface extending the full length of the trenching device shaft). For example, a fifteen feet long trenching device shaft could be modified to include drain installation at depths of fifteen feet below the surface and one ft. above that extending to the surface, i.e., installation of drains at fifteen feet below the surface, fourteen feet, thirteen feet, twelve feet, etc., extending to one foot below the surface.

The foregoing has outlined rather broadly certain aspects of the present invention in order that the detailed description of the invention that follows may better be understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures or processes for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.

DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIG. 1A is a diagram showing the side view of one embodiment of a VCD installation device having both a towing hitch and winch connections for moving the device;

FIG. 1B is a diagram showing the top view thereof;

FIG. 2A is a diagram showing the side view of the VCD installation device having the hitch and winch options shown in FIG. 1 in addition to a track over the carrier for the purpose of assisting with moving the installation device across solid sludge surface. These tracks may or may not be mechanized or self-propelled;

FIG. 2B is a diagram showing the top view thereof;

FIG. 3A is a diagram of the VCD installation device having the hitch and winch options shown in FIG. 1 in addition to a cutting blade preceding the trenching device in order to help dig a trench through any difficult-to-traverse materials;

FIG. 3B is a diagram showing the top view thereof;

FIG. 4A is a diagram of the VCD installation device having the hitch and winch options shown in FIG. 1 and both the track and cutting blade options depicted in FIG. 3 and FIG. 4;

FIG. 4B is a diagram showing the top view thereof;

FIG. 5A is a diagram of the VCD installation device having the hitch and winch options shown in FIG. 1 and having the option of installing drains at multiple depths below the surface of the pond;

FIG. 5B is a diagram showing the top view thereof;

FIG. 6A is a diagram of the VCD installation device having the hitch and winch options shown in FIG. 1 and having the option of a vibratory trenching device where a vibrating device is mounted on the trenching device shaft to impart vibrating energy to the trenching device during installation;

FIG. 6B is a diagram showing the top view thereof; and

FIG. 7 is a diagram of the VCD installation device having the hitch and winch options shown in FIG. 1 and having the option of a trencher in place of the trenching device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to improved methods and systems for, among other things, the installation of vacuum consolidation dewatering horizontal drains for dewatering sludge ponds. The configuration and use of the presently preferred embodiments are discussed in detail below. It should be appreciated, however, that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of contexts other than device for the installation of vacuum consolidation dewatering sludge ponds. Accordingly, the specific embodiments discussed are merely illustrative of specific ways to make and use the invention, and do not limit the scope of the invention.

Embodiments of the present invention include a device for the installation of the prefabricated drains in a horizontal, co-planar pattern below the surface of a sludge pond with the intent of putting a vacuum on the horizontal drains to withdraw water from the sludge pond material to dewater the sludge to the level of the drains below the pond surface.

Referring now to FIG. 1A and FIG. 1B which shows one embodiment of the VCD installation device 100 comprising a trenching device 101 that extends below the surface of the pond to a depth 120 of 1-15 feet and a drain/hose downtube 102 through which the drain 106 or hose 108 passes to be installed at depth 120 beneath the pond surface. The trenching device 101 and downtube 102 can be raised and lowered below the surface using the hydraulic system 104 which is powered by the motor 110. The drain 106 and hose 108 are in coils on reels that are mounted on a feeder and unroll during installation as the VCD installation device 100 moves across the pond so that the drain 106 or hose 108 may be fed down the downtube 102 for installation at a certain depth 120. The trenching device 101, downtube 102, feeders, hydraulic system 104, and motor are mounted on a carrier 112 so that the entire VCD installation device 100 can float on the water surface of a sludge pond.

The VCD installation device 100 may be winched across the surface of the pond using the winch connections 114 on the device. Alternately, the VCD installation device 100 may be towed across the surface of the pond behind a suitable piece of heavy equipment using a hitch 116 on the device. In addition, either the hitch 116 or winch connection 114 can be used to haul the VCD installation device 100 to the next point at which a drain 106 should be installed into the pond.

Referring now to FIG. 2A and FIG. 2B which shows an alternative embodiment of the device described above and shown in FIG. 1A and FIG. 1B with the addition of a rolling belt or track 130 that is mounted on the surface of the carrier in a continuous loop front to back so that if the device is winched or hauled across a dry sludge pile extending above the water surface of the pond, the tracks 130 will grip the sludge and roll, allowing easier travel of the VCD installation device 100 whereas with no rolling track the bottom surface of the carrier 112 would be dragged across the abrasive solid sludge. Alternately, some sludge ponds are relatively dry where a limited amount, or no, free water is present. In these ponds, the VCD installation device 100 would be dragged across the surface of that pond. However, if the rolling tracks 130 are included on the carrier 112, then the VCD installation device 100 will roll easier, with less resistance, across the relatively dry pond surface. The rolling tracks 130 prevent the wearing or abrading of the bottom surface of the carrier 112 because the bare bottom of the device is not being dragged across the dry pond surface which may be abrasive. The rolling tracks may also be mechanized to self-propel the device across the pond surface.

Referring now to FIG. 3A and FIG. 3B which shows another alternative embodiment of the device described above and shown in FIG. 1A and FIG. 1B with the addition of a cutting blade or chain trencher 124 which can be used to dig or trench the sludge in the pond to the required depth 120. Some sludge material could be too strong or hard to plow through and will need to be dug out to make a path for the installation of the drain 106 or hose 108. In addition to the chain trencher 124 there is also a required motor 126 and chain drive 128 required to drive the chain trencher 124 to dig the hole for drain 106 or hose 108 installation. In some embodiments, the chain trencher 124 may be configured with a circular saw blade instead of a cutting chain where the radius of the required depth of the VCD drain installation is the radius of the circular saw blade.

Those skilled in the art will recognize that the devices described above and shown on FIG. 1A and FIG. 1B, FIGS. 2A and 2B, and FIGS. 3A and 3B could be included in one device such as shown in FIG. 4A and FIG. 4B.

Referring now to FIG. 5A and FIG. 5B which shows another embodiment of the device described above and shown in FIG. 1A and FIG. 1B with the addition of an option to simultaneously install the drains 106 or hoses 108 at multiple depths below the surface of the pond. Multiple downtubes 102, 134 are used to install drains 106 or hoses 108 at varying depths 120, 136 below the surface. Although the installation of drains 106 or hoses 108 is shown at two depths, those skilled in the art will appreciate that there could be drain 106 or hose 108 installations at a number of depths, such as at depths varying by one foot extending along the entire length of the trenching device shaft. For example, a fifteen foot long trenching device shaft could be modified to include drain installation at depths of fifteen feet below the surface and one ft. above that extending to the surface, i.e., installation of drains 106 or hoses 108 at fifteen feet below the surface, fourteen feet, thirteen feet, twelve feet, etc., extending at one foot intervals to 1 foot below the surface. This embodiment could also include the track 130, cutting blade 124 or vibratory trenching device 132 modifications shown in FIG. 2A and FIG. 2B, FIG. 3A and FIG. 3B and FIG. 6A and FIG. 6B, respectively.

Referring now to FIG. 6A and FIG. 6B which shows another embodiment of the device described above and shown in FIG. 1A and FIG. 1B with an option to modify the trenching device 101 by attachment of a vibrating device 132 to depart vibrational energy to the trenching device 101 during installation. During installation, the vibrating energy of the vibrating trenching device 101 will cause the sludge to liquefy to a certain extent which allows the VCD installation device 100 to be more easily pulled or towed through the sludge. This embodiment could also include the track 130 option shown in FIG. 2, and/or the option of installing of drains 106 or hoses 108 at multiple depths 120, 136 below the surface of the pond as shown in FIG. 5A and FIG. 5B.

Referring now to FIG. 7 which shows another embodiment of the device described above except that the trenching device 101 has been replaced by a trencher 138 which can be used to dig the sludge pond and make a path for the drains 106 or hoses 108 to be installed. Using a trencher 138 to make a path or trench in the sludge pond to install the drains 106 or hoses 108 reduces the drag on the VCD installation device 100. Some sludge material could be too strong or hard to plow through and a trencher 138 could be used to dig a path for the installation of the drains 106 or hoses 108. The trencher 138 may also require less energy to move the carrier 112 across the pond by reducing the drag on the overall VCD installation device 100.

While the present device has been disclosed according to the preferred embodiment of the invention, those of ordinary skill in the art will understand that other embodiments have also been enabled. Even though the foregoing discussion has focused on particular embodiments, it is understood that other configurations are contemplated. In particular, even though the expressions “in one embodiment” or “in another embodiment” are used herein, these phrases are meant to generally reference embodiment possibilities and are not intended to limit the invention to those particular embodiment configurations. These terms may reference the same or different embodiments, and unless indicated otherwise, are combinable into aggregate embodiments. The terms “a”, “an” and “the” mean “one or more” unless expressly specified otherwise.

When a single embodiment is described herein, it will be readily apparent that more than one embodiment may be used in place of a single embodiment. Similarly, where more than one embodiment is described herein, it will be readily apparent that a single embodiment may be substituted for that one device.

In light of the wide variety of plowing methods and systems available, the detailed embodiments are intended to be illustrative only and should not be taken as limiting the scope of the invention. Rather, what are claimed as the invention are all such modifications as may come within the spirit and scope of the following claims and equivalents thereto.

None of the description in this specification should be read as implying that any particular element, step or function is an essential element which must be included in the claim scope. The scope of the patented subject matter is defined only by the allowed claims and their equivalents. Unless explicitly recited, other aspects of the present invention as described in this specification do not limit the scope of the claims.”

While the present system and method has been disclosed according to the preferred embodiment of the invention, those of ordinary skill in the art will understand that other embodiments have also been enabled. Even though the foregoing discussion has focused on particular embodiments, it is understood that other configurations are contemplated. In particular, even though the expressions “in one embodiment” or “in another embodiment” are used herein, these phrases are meant to generally reference embodiment possibilities and are not intended to limit the invention to those particular embodiment configurations. These terms may reference the same or different embodiments, and unless indicated otherwise, are combinable into aggregate embodiments. The terms “a”, “an” and “the” mean “one or more” unless expressly specified otherwise. The term “connected” means “communicatively connected” unless otherwise defined.

When a single embodiment is described herein, it will be readily apparent that more than one embodiment may be used in place of a single embodiment. Similarly, where more than one embodiment is described herein, it will be readily apparent that a single embodiment may be substituted for that one device.

In light of the wide variety of methods for device for the installation of vacuum consolidation dewatering horizontal drains for dewatering sludge ponds known in the art, the detailed embodiments are intended to be illustrative only and should not be taken as limiting the scope of the invention. Rather, what is claimed as the invention is all such modifications as may come within the spirit and scope of the following claims and equivalents thereto.

None of the description in this specification should be read as implying that any particular element, step or function is an essential element which must be included in the claim scope. The scope of the patented subject matter is defined only by the allowed claims and their equivalents. Unless explicitly recited, other aspects of the present invention as described in this specification do not limit the scope of the claims.

Claims

1. A method for installing a drain into a sludge pond, comprising: cutting a trench in a sludge pond at a single depth with a trenching device attached to a amphibious carrier;passing a drain into the trench through a downtube coupled with the trenching device; andtransporting the amphibious carrier across the sludge pond.

2. The method of claim 1, further including removing water from the sludge pond through the drain with a vacuum.

3. The method of claim 1, further including removing water from the sludge pond through the drain with a water pump.

4. The method of claim 1, further including multiple downtubes for simultaneous installation of co-planar drains at multiple depths.

5. The method of claim 1, further including transporting the carrier across the sludge pond with a winch.

6. The method of claim 1, further including cutting a trench in the sludge pond with a chain driven blade attached to the trenching device.

7. The method of claim 1, further including liquefying sludge in the sludge pond with a vibrator attached to the trenching device.

8. The method of claim 1, further including transporting the carrier across dry sections of sludge with tracks attached to the carrier.

9. A device, comprising: a trenching device that cuts a trench in a sludge pond extending downwardly from a carrier to a single depth;a downtube through which drain may be passed into the trench coupled with the trenching device; anda amphibious carrier for transporting the trenching device across the sludge pond.

10. The trenching device of claim 9, further including vacuum attached to the drain to remove water from the sludge pond.

11. The trenching device of claim 9, further including a water pump attached to the drain to remove water from the sludge pond.

12. The trenching device of claim 9, further including multiple downtubes for simultaneous installation of co-planar drains at multiple depths.

13. The trenching device of claim 9, wherein the winch is attached to a motorized vessel.

14. The trenching device of claim 9, wherein the trenching device is equipped with a chain driven blade to assist in cutting a trench in the sludge pond.

15. The trenching device of claim 9, wherein the trenching device is equipped with a vibrator to liquefy sludge in the sludge pond as the trenching device cuts the trench in the sludge pond.

16. The trenching device of claim 9, wherein the carrier is equipped with tracks to aid in moving the carrier across dry sections of sludge.