Liquid purification or separation – Processes – Including geographic feature
Reexamination Certificate
2000-04-24
2001-09-25
Simmons, David A. (Department: 1724)
Liquid purification or separation
Processes
Including geographic feature
C210S164000, C210S232000, C210S477000
Reexamination Certificate
active
06294095
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to filter systems, and more particularly to a filtration system for storm water drains for filtering silt from wastewater flowing into street curb drains.
A storm sewer system helps prevent flooding by diverting rain and melted snow into the nearest river or creek through a network of underground pipes. Surface water enters the storm sewer system through curb-side street drains and flows by gravity to the outfalls, where the water is discharged into a creek or river. Since pollutants can enter the storm sewer system through street drains, local waterways can be damaged when debris is carried into the drain along with the surface water. This is a particular problem in areas where new construction is taking place. Regardless of how thoroughly builders may maintain a construction project, silt is likely to accumulate on the streets and is blown into the curb-side street drains, and into the water system, by rain and/or large street-washing trucks.
A street curb drain typically includes a storm water catch basin, a fixed frame with a catch basin inlet and a grate covering the drain opening. Examples of silt catching devices for use with street drains are shown in U.S. Pat. Nos. 4,419,232 and 5,575,925. The devices include a silt filtering bag which is constructed of a fabric designed to capture the silt while allowing the water to flow therethrough. In U.S. Pat. No. 5,575,925, the filter bag includes a plurality of lift flaps which are designed to extend between the grate covering and the catch basin inlet so that the grate covering sandwiches the flaps in place against the catch basin for supporting the filter bag in the catch basin.
One disadvantage of this silt catching device is that it requires the edges of the filter bag to be placed at street level. Thus, the fabric edges of the bag are exposed to vehicular traffic and may become frayed and/or ripped. Whe n the bag is ready to be emptied, there may be no fabric or not enough fabric to handle the weight of the silt-filled bag thereby causing the bag to fall into the drain. In this event, a person must be lowered into the drain and remove the silt with buckets which are passed to people at the street level to clean out the drain. The cleaning out of a silt-filled drain is a difficult and time-consuming task.
Another disadvantage of silt catching devices is that the filter bag may be too deep and too wide for the catch basin. Thus, during a hard rain, the sack may press against the sides of the drain thereby preventing water from passing, through the sack and causing the streets to flood. A further disadvantage of current silt-catching devices is that the design and location of such devices at street level may force silt to build up in the street while affording minimal overflow capabilities during hard rain. Therefore, there is a need for a simple, readily accessible silt trap system which effectively catches the silt and allows the silt to be safely and easily removed.
SUMMARY OF THE INVENTION
In accordance with the present invention, a silt filtration system is provided for use with storm water catch basins for filtering silt from wastewater flowing into street curb drains. The silt filtration system is designed to be used with a street curb drains of the type which include a storm water catch basin having a fixed frame with a drain opening at the top of the catch basin and a grate covering the drain opening. The silt filtration system is uniquely configured to allow for the quick and easy removal of the silt captured by the system. Because the silt filtration system of the present invention is specifically designed to fit beneath the grate, it is located entirely beneath the street level and is not exposed to vehicular traffic or the elements. Thus, the system may be used repeatedly and moved to different locations as needed, such as, by way of example, to new phases of a construction project.
The silt filtration system of the present invention comprises a base frame adapted to fit within the fixed frame at the top of the catch basin of the curb drain. The base frame includes a pair of spaced apart end rails which are mounted beneath the grate and rest on a series of bumps or ridges located on the fixed frame of the catch basin on which the grate covering, normally rests. The end rails are connected by a pair of spaced apart side rails which extend between the end rails to form the base frame. The silt filtration system also includes a pair of lengthwise support bars or rods which are removably positioned within the base frame and supported by a plurality of holders or brackets attached to the base frame. Each holder includes a recess for receiving and supporting the lengthwise bars therein. In addition, the system includes a pair of transverse support bars or rods which are removably positioned over the lengthwise support bars and supported by the side rails.
The lengthwise and transverse bars of the present invention are designed to suspend a filter bag within the catch basin for capturing the silt in the water flowing into the catch basin. The filter bag of the present invention includes two pairs of opposite sides and an open top end. Each side of the bag includes a pocket or sleeve at the top end for receiving the lengthwise support bars and the transverse support bars. Because of the unique combination and configuration of the frame mountable beneath the grate and the two pairs of support bars, the entire system is advantageously located beneath the grate and below the street level.
In the preferred embodiment of the present invention, the base frame of the present invention is substantially rectangular shaped and is constructed of a rigid, durable material, such as by way of example, steel. Each end rail is substantially L-shaped and includes a first portion and a second portion. The first portion is adjacent to the drain opening and mountable to the fixed frame of the catch basin. The second portion is attached to the first portion and extends downwardly into the catch basin. In the preferred embodiment, the side rails are connected to the second portion of the end rails and are positioned a predetermined distance below the first portion of the end rails and the drain opening. Each holder recess is substantially v-shaped and extends below the side rails for supporting the lengthwise support bars thereon in substantially horizontal alignment with the side rails. In use, the transverse support bars are positioned over the lengthwise support bars and rest on the side rails to suspend the filter bag in the catch basin. In the preferred embodiment, each side rail includes a raised portion for holding the transverse support bars in place adjacent to the end rails.
The filter bag of the subject invention is constructed of any suitable fabric or material which allows water to flow therethrough while capturing silt within the bag and is preferably constructed of a general use, high-strength, high-modulus fabric, such as, by way of example, the woven geotextile fabric known as GTF-200 manufactured by LINQ Industrial Fabrics, Inc. In the preferred embodiment, the width of the filter bag narrows as it descends into the catch basin for advantageously preventing the bag from pressing against the sides of the return basin and blocking the water from passing through the sides of the sack. In addition, the subject invention may include a means for deflecting silt and/or sediment and the like to flow over the grate and into the filter bag for increasing the effectiveness of the subject invention. In the preferred embodiment, the means is an elongated rail or deflector positioned on the grate adjacent to the curb.
The present invention may also include a method for installing the silt filtration system on a street curb drain and removing the silt from the drain. In the preferred embodiment, the steps for installing the silt filtration system begin with lifting the grate from the drain and placing the base frame on the fixed frame of the catch basin on which the grat
Erosion Control Services, Inc.
Kennesy Covington Lobdell & Hickman, LLP
Lawrence Frank M.
Simmons David A.
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