During construction of a project, the ground is disturbed and for a period of time left as exposed soil. When it rains, there is no grass or vegetative cover to prevent erosion of the exposed soil. A heavy rainfall can produce serious amounts of erosion of these soils and if not captured before this contaminated runoff enters a watershed, the streams and lakes downstream will become heavily contaminated with these sediments. This leads to serious degradation of the watersheds downstream. To prevent this, regulations require that measures are installed on the site and that the water be treated prior to downstream discharge to prevent release of this sediment laden water.
Over the years various apparatus and methods have been used to clean this water and many have shortcomings. To insure that the majority of the contaminants are removed, the water in a pond or container is slowly released through a filter means or other outlet control as cleaned water. One problem with filtration is that the finer, or the more restrictive the filter media, the better it works, but the quicker it becomes occluded. To overcome this, a greater surface area of filter media can be used, but that takes up space and very often is impractical and costly.
Currently sediment control and storm water ponds have used a single layer of filter fabric around a pipe to filter the water as it flows out of the pond. This cleaning method has a huge limitation. Moreover, with heavy sediment loads such systems become clogged and stop up very quickly.
The present invention is a means and apparatus for solving the foregoing problem by using a spiral wound cartridge comprising four or more layers wound such that there is a large amount of filter surface area achieved in a relatively small circumference.
The four layers include an inlet layer that will receive dirty water from the top side, the bottom side and the sidewall of the filter.
The preferred form of the invention comprises a spiral wound cartridge configured with four layers, two processing layers (one of which is an inlet layer and the second is the outlet layer) and two filtration layers. These four layers are configured in a spiral, such that the water is able to freely flow into the inlet layer, which is open to the pond or container, as aforesaid. The water also flows through an output layer which is connected to the center tube where it is piped outside of the pond or container as filtered water.
The spiral layers are configured so that the water cannot go from the inlet layer to the outlet layer without first passing through the filter layer. In the preferred form of the invention, the inlet layer has a filter layer on each side of it and the outlet layer does as well. This optimizes uses of the drainage media layers and allows for more surface area of the filtering layers in a smaller spiral.
The invention also incorporates the use of a standpipe. The filter fits on the standpipe and can be easily replaced during maintenance.
In the preferred form of the invention, the media layer is simply a layer of filter cloth that is inexpensive yet effective. The preferred form of the invention has a plastic media that allows water to flow to the drainage layer.
The water can enter the inlet layer from the side as well as the top or bottom of the spiral. The outlet layer must have a layer of fabric between it and the water in the container or pond, however it can be sealed at any point where there is no fabric or there is concern of breakage or damage such as at the top or bottom of the spiral.
This filter can be configured to receive dirty water from outside of the spiral and clean the water as it flows inside the spiral. The filter could also, in another form, receive dirty water at the center of the spiral and clean the water as it flows outward.
The preferred embodiment of the invention is shown in
The two filtration layers 11 and 13 are in contact with a face of the inlet layer 10 and are either effectively sealed by overlapping each other, or are sealed by other means, such that the only way for water to enter the outlet layer 12 is by passing the water through a filtration layer 11 or 13. By wrapping all of the layers in a spiral, the inlet drainage layer 10 is in contact with a filtration layer 11 or 13 on both sides of the layer 10, and the outlet layer 12 is in contact with a filtration layer 11 or 13 on both sides of the spiral as well.
In the preferred form of the invention, the outlet layer 12 is in communication with the central outlet conduit 14. The water then passes through perforations 15 located in the central outlet conduit 14, where the outlet layer 12 is in contact with the central outlet conduit 14.
In the preferred form of the invention the top of the central conduit 14 is sealed closed so that no unfiltered water can enter the outlet conduit. The central outlet conduit 14 is then in fluid communication with either a drain or other means for allowing the filtered water to be removed from the pond via pipe 18, 22.
The cartridge (the spiral) 16 is located on a standpipe 17 which is perforated such that water draining into the central outlet conduit 14 via holes 15 can enter the perforated standpipe 17 and flow out of the container or pond 23. There is preferably a seal that seals the central outlet conduit 14 to the pipe 18, 22 to prevent leakage. The perforated standpipe 14, 17 is, therefore, connected to an outlet conduit 18 which is in communication with the treated water outlet 22 of the container or pond 23. In the case of a pond, the container outlet conduit 18 passes through a weir 21 to get to the treated water outlet 22.
As contaminated water enters the container or pond 23, it must first fill the pond until it reaches a level 20 where water can begin entering the bottom of filter cartridge 16. Water may enter from the bottom or sides of the filter and ultimately when the water rises to level 19 it could enter the inlet layer 10 at the top side of the spiral. The water then flows into the inlet layer 10 and because initially there is no water in the outlet layer 12, it must flow through one or both of filtration layers 11 and 13. The filtered water that has passed through the filtration layers 11 or 13 is the only water that can enter the outlet layer 12.
The cartridge 16 is removable. In other words, the cartridge 16 can be lifted off of the standpipe 17 and the sealing means 24 is an o-ring. The cartridge can easily be removed and a fresh cartridge inserted very quickly and easily.
One very important feature of the invention is that the water in the pond can enter the spiral filter at the top side of the filter (
The top and bottom edges 10a, 10b and 10c etc. of input layer 10 are exposed to water in the pond (assuming there is water at the level of these edges). Typical edges bear reference numbers 10a, 10b, and 10c.
However, layers 11, 12 and 13 will not receive water direct from the pond as their edges (
Thus, the foregoing can be summarized by saying that whenever the input layer 10 is exposed to water in the pond, whether it be at a side wall or at the top or bottom, the layer 10 is exposed so it will receive water from the pond.
However, whenever any layer, other than layer 10, is exposed to water in the pond, the exposed area is sealed to prevent entry of water directly from the pond.
Nothing said in the last few paragraphs modifies what has been said earlier namely that layers 11, 12 and 13 will receive water from the pond indirectly via layer 10.
There are numerous forms that the layers 10 and 12 may take and I will set forth two of those forms.
In one of said forms: (a) the strips 10 and 12 may be made of polypropylene cloth and have a thickness of 0.3 inches and a width of 30 inches; and (b) the filter strip 12 is made of high grade geotextile fabric which has a thickness of 0.3 inches and a width of 30 inches.
Another form that the layers 10 and 12 may take is described in the next four paragraphs.
Inlet layer 10 and outlet layer 12 may be made of permeable material that maintains the shape of said layers so that said layers appear empty. In one form of the invention, however, said layers comprise two separate plastic materials: two layers of a relatively rigid high density polyethylene (HDPE) drainage material that provides structure to said layers and an ethyl vinyl acetate (EVA) material that fills the space between said layers. In the current mode of that invention, said HDPE material is Poly-flex (a registered trademark). Drainage Net, and said interior filter material is Matala.™
Poly-flex Drainage Net is a high-density polyethylene product between 0.25 and 0.50 inches thick, consisting of two sides. Each side has one series of ridges 31 (
Matala mat is placed between the two layers of Poly-flex Drainage Net that define inlet layer 10 and outlet layer 12. Matala is a proprietary material developed using the plastic EVA, which is extruded from nozzles to form spaghetti-like strands that adhere to one another. Said strands create a matrix with large amounts of open void space, through which water can flow freely. Because of the properties of EVA, Matala mats are both flexible and compressible, allowing them to be wrapped in a spiral between layers of Poly-flex Drainage Net. The mats used in one form of the invention may vary in thickness between ¾ of an inch and 1½ inches.
In one modified form of the invention, the outlet conduit of the cartridge 16 is elevated to a level above the cartridge and is open on top such that should the filter become occluded or there be a severe storm the pond will not overflow the top of the weir 21. This allows unfiltered water to flow directly into the treated water outlet conduit 18, to the outlet 22.
In another modified form of the invention the top and/or bottom of the cartridge are sealed and thereby limit how the water is able to enter the inlet layer 10.
A third form of the invention is one where the filter is operated in the reverse where the water enters in layers 12, is filtered through layers 11 and 13, and the outlet layer is 10.
A fourth form of the invention comprises keeping the diameter of pipe 17, 18 and 22 small enough to create a siphon effect that will tend to increase the rate of flow through the system.
I claim the benefit of my prior copending provisional application Ser. No. 60/925,949, filed Apr. 24, 2007. The present application is also a continuation-in-part of my prior copending application Ser. No. 11/030,939 filed Jan. 9, 2005 and Ser. No. 11/522,150 filed Sep. 16, 2006.
Number | Date | Country | |
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60925949 | Apr 2007 | US |
Number | Date | Country | |
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Parent | 11030939 | Jan 2005 | US |
Child | 12148749 | US | |
Parent | 11522150 | Sep 2006 | US |
Child | 11030939 | US |