Patent Application
20090208289
A rotatable drain grate in an opening into a sewer system which when closed retains trash and debris upstream from the opening while permitting slow flow of water, and which pivotally opens when confronted with high rates of water flow to allow overflow water into the sewer while restraining the heavier debris.
Storm drains such as are found in gutters and drainage channels, receive trash, cuttings, trimmings and other debris constantly throughout the year and are subject to clogging. Despite regular sweeping upstream from the opening, considerable amounts of trash will enter the drain system, while still permitting the slow flow of water. Ground water run-off frequently carries petroleum products with it. Such pollutants include oil, gasoline, greases, etc. that originate in streets, parking lots, service garages, etc. Pollution and contamination of waterways is damaging to human health and the environment. It is important to try to eliminate these pollutants from the water run-off before it reaches the water table. One physical property of these pollutants that can be exploited in trying to separate them from the water run-off is that most of them float (i.e., they are less dense than water). Prior efforts to remove such petroleum pollutants from water run-off have been less than completely successful. To maintain freshwater systems, most cities and counties have regulations that require the removal of some of the pollutants from the storm-water runoff before entering their storm sewer systems. In order to meet these regulations, facilities typically install on-site pollution traps to filter the storm-water runoff. These pollution traps are sometimes referred to as “oil/grit separators.”
Serious trouble arises when later storms or other circumstances present water to these systems at high rates of flow while they are congested with the accumulated trash. Clogging of this system can result in upstream flooding, or the washing downstream of the accumulated material. To avoid this situation, throughout the year maintenance crews are sent to clear out trash and debris that has entered the system through the openings. This is a considerable expense, and in the event that a storm strikes before the system is cleared, serious damage can occur despite those earlier efforts.
Most conventional pollution traps provide only “first flush” filtration during the typical local storm event, but permit bypassing the filtration stage for larger storms. In fact, many jurisdictions require bypassing, some even at typical storm water flows. Bypassing filtration is a problem because most pollutants are more easily picked up and transported by storm water during higher flow periods. Unfortunately, just when the traps are needed most, a lot of pollutants bypass them and are delivered into the storm sewer systems. And most pollution traps that do not provide for bypassing accommodate the larger flows because they are oversized, which adds significantly to the cost to build, install, and maintain them.
In addition, most filter systems included in the catch basin of storm sewer systems which, under low flow conditions, often act as biological incubators that add to the microbial contamination of storm water runoff. Such bacterial pollutants, unlike chemical ones, are dynamic, continue to grow exponentially, and may quickly reach dangerous level. Some filter systems use chemicals, which can be damaging to the environment.
Therefore, what is needed is a means to be installed in the drain opening of a catch basin of a typical storm drain system to trap, block or reduce the entry of unwanted leaves, litter and similar debris without interfering with the flow of rainwater through filtration system and into the storm sewer system. Also needed is a filtration system that will powerful, cost effective and durable system for water filtration with antimicrobial action.
Accordingly, it is an object of this invention to provide a sewer water gate to be located at the opening to a subsurface catch basin of a storm drain system that will exclude trash and debris from the system while still permitting a flow of water, but which will partially open to allow full access for water (and entrained material) when the rate of flow is sufficiently high while still obstructing the flow of heavier materials. When fully closed, the gate will permit the trash upstream from it to be removed by routine collection sweeping, so as to remove trash that otherwise would later be driven into the system by storm runoff. Another object of this invention is to provide a sewer water gate system that includes a filter system that reduces the buildup of microbial contamination from storm water runoff.
Referring to
Side brackets 120 and 140 are opposingly affixed to lower gate screen 160 by means of standard cap screws 165. Lower gate screen 160 is sized to span the horizontal distance between the left and right sides of a sewer drain opening, such that when gate system 100 is installed, lower gate 160 effectively blocks debris and other solid matter entering the sewer drain opening at the gutter level. In this preferred embodiment, lower gate 160 is constructed of 10-gauge, 0.75 inch expanded metal stainless steel. Also shown in
Upper gate 200 and rotatable means 230 form the rotatable gate portions of the water gate of the invention. In this preferred embodiment, rotatable means 230 is comprised on a standard hinge commonly known as a piano hinge, which is sized to substantially span the distance between side bracket 120 and side bracket 140 while permitting the hinge action to freely move without contacting either side bracket 120 or side bracket 140. Rotatable means 230 is also constructed of 1×1 inch stainless steel. Although rotatable means 230 is comprised of a piano hinge in this embodiment, such hinge is not a limitation of the invention, other types of rotatable means may be used, including other types of hinges, springs, or other devices. The only requirement is that the rotatable means be adaptable to being affixed to upper bracket 180 and to rotatably support upper gate 200. However, a hinge has certain advantages over a spring, that being that the hinge need not be manually reset. Upper gate 200 is comprised of 0.375 inch lexan-polycarbonite screen, having openings for the passage of water. As shown in
Gate system 100 additionally includes bias means 240 for biasing rotatable upper gate 200 in a closed position. In this preferred embodiment, bias means 240 comprises a pair of magnets selected with sufficient magnetic strength to cause upper gate 200 to rotate to a closed position when the pressure of the water and debris drops below a selected level. Referring to
Referring now to
Although preferred embodiments of the invention have been described herein in detail, it will be understood that those skilled in the art can make modifications thereto without departing from the spirit of the invention or the scope of the appended claims. For example, filter means 280 could also be comprised of a material that absorbs hydrobarbons.
