Liquid purification or separation – Structural installation – Grated inlet surface drain
Reexamination Certificate
1999-06-29
2001-08-14
Lithgow, Thomas M. (Department: 1724)
Liquid purification or separation
Structural installation
Grated inlet surface drain
C210S238000, C210S474000
Reexamination Certificate
active
06274036
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a filter, and more particularly to a removable filter for sewage basins.
BACKGROUND OF THE INVENTION
In order to prevent severe flooding from heavy rains or melted snow, most municipalities have built underground drainage systems. Water flows into the underground drainage basin by passing through a basin grate, usually placed on one side of a road, before it is released into an underground sewer line. Such basin grates are often provided with an overflow slot which receives the runoff and directs it to the sewer system when the runoff is at a greater rate than the catch basin can handle.
Ideally, the water entering the drainage basin should be free of any solid debris or other environmental contaminants. Such solid debris and environmental contaminants can cause blockage in the system which can result in flooding as well as causing damage to the basin and sewer line if allowed to pass through freely.
In addition, recent state and federal legislation has required a reduction in water pollution and debris and dirt in the runoff. One source of water pollution is the solid debris and environmental contaminants which are carried by the flow of water to, and released into drainage basins. A great deal of particulate matter can be picked up for instance when a source of the water is in an area in which the ground has been disturbed, such as is the case at most construction sites. Consequently, many governmental agencies are requiring developers to provide some means of preventing the runoff which enters the drainage system from carrying with it debris and particulate matter.
In order to filter the runoff that enters a drainage basin at construction sites, filters have been placed, usually above ground, around the grate of the drainage basin. Not only are these devices an eyesore, but they also tend to greatly impede the flow of water into the drainage basin because of either the debris which the filter collects or the filter itself. Such impedance could cause the exact flooding which these basins are meant to prevent. Underground basin filters such as that disclosed in U.S. Pat. Nos. 5,575,925 and 5,372,714 solve some of these problems but they do not include a means of filtering the water which enters the drainage system through the overflow slot.
U.S. Pat. No. 5,632,888 discloses a catch basin filter which includes means for filtering water flowing through the overflow slot but the filter shown in the patent is different to install and to remove for cleaning or replacement.
There exists a need then for an underground filter which can be easily manufactured and which can be readily mounted in place to separate and prevent solid debris from entering a drainage basin, not permitting any portion of the water flow to enter the drainage basin either through the grate or the overflow slot without passing through the filter.
SUMMARY OF THE INVENTION
The invention is a filter for a drainage basin comprising a filter bag formed with two sidewalls which are joined at their edges and with an open top so that when the sidewalls are separated a filter bag is formed through which water may pass. A debris dam joined to the upper edge of one of the sidewalls fits into the overflow slot when the filter bag is positioned within a catch basin to prevent unfiltered runoff from entering the drainage basin through the curb overflow slot. The filter bag is secured to be positioned under a drainage basin grate. The sidewalls which constitute the boundaries of the filter bag are made of a semi-permeable geosynthetic material through which water may pass, however solid debris is trapped. Rigid rebar handles are inserted in loops formed at the top of the sidewalls. These handles remain above the drainage basin grate when the filter is in place to keep the filter bag in the proper position and to facilitate removal of the filter for cleaning or replacement.
Water, solid debris, and environmental contaminants flow through the drainage basin grate. Solid debris and environmental contaminants are separated from the water, as the water is allowed to pass through the filter bag while the debris and other contaminants are trapped within the bag. The debris dam prevents debris from entering the sewer system through the overflow slot. The debris and contaminants accumulate in the filter bag until such time as the filter is removed and the contents dumped from the filter bag. The filter may also be washed after removal. The filter may again then be installed along the opening of the drainage basin.
One advantage of the present invention is that debris and contaminants may be prevented from entering a drainage basin without causing excessive impedance to the flow of water into the basin.
Another advantage of the present invention is that the filter can be easily installed, removed, and reused.
Yet another advantage of the present invention is that unfiltered water is prevented from entering the drainage basin through the curb overflow slot.
Still another advantage of the present invention is that the filter easily collapses to occupy only a small space when not in use.
Still yet another advantage of the present invention is that it is easily and inexpensively manufactured.
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Gifford, Krass, Groh Sprinkle, Anderson & Citkowski, P.C.
Lithgow Thomas M.
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