Patent Application
20140263004
This invention relates generally to storm water inlets, and more specifically to a storm water inlet having a precast porous concrete filter, and to a method of making a storm water inlet with a precast porous concrete filter.
Streets, parking lots, and other paved surfaces for vehicular and pedestrian traffic are designed and built with storm drains or storm water inlets to drain the storm waters that these surfaces collect. On streets such drains often are located periodically along curbs and shoulders. Paved surfaces are typically graded in such a manner so that water falling onto the surface should flow to one or more of the storm drains. This prevents water from collecting on the surface and the attendant problems associated with flooding, such as inhibiting the flow of traffic, and spillover onto adjacent lands and structures.
A typical storm water inlet has a surface opening that sits above a vertical-walled chamber called a catch basin, which is connected to a sewer system by one or more pipes entering the chamber through openings in the vertical walls. In a common design the catch basin sits on the edge of a roadway inside of the curb, and the surface opening is covered with a grate. This grate enables water to flow into the catch basin but prevents large objects from passing into the catch basin and blocking the sewer pipe. Other designs are built into the curb and have a simple “fall-in” opening in the curb. Still other designs have a combination of these or other features. In virtually all storm water inlet designs, the catch basin is intended to collect debris that is washed in by the force of flowing water. As a result, storm water inlets require periodic maintenance to remove the collected debris collected in the catch basin. For this purpose access to the interior compartment of the catch basin is provided through removal of the grate covering the surface opening or a manhole cover where no such grate is present.
Storm water is frequently laden with trash, leaves and other organic debris, as well as sand, gravel, and other forms of sediment collected from streets, parking lots, and other paved areas. As storm water flows over a street or parking lot to a storm sewer, it also gathers other solid and fluid contaminants deposited on the surface, including oil, grease, fuel, hydraulic fluid, and metals from the vehicles that traverse these paved surfaces. Federal, state, and local standards for regulation of storm water runoff place ever-stricter limits on the discharge of organic, metallic, and other contaminants into downstream waterways. Storm water runoff that passes into many storm drains frequently fails to meet the applicable standards due to the excessive dissolved or suspended contaminants such as petroleum-based materials and metals that wash into the drains with the storm water. This problem has led to a plethora of prior art devices and systems for filtering and/or purifying storm water runoff water that passes into a storm drain.
One class of devices involves a barrier or other filter medium placed around, over, or on top of the drain opening at or above the surface level of the drain. Typical of such devices are those disclosed in U.S. Pat. No. 5,403,474, U.S. Pat. No. 5,632,888, U.S. Pat. No. 5,725,782, U.S. Pat. No. 6,010,622, and U.S. Pat. No. 6,749,366. In many of these prior art devices, the filters are placed or protrude above the level of the drained surface, creating an obstruction, or are only temporary installations designed to address acute runoff conditions during, for example, construction, etc.
In another class of devices, an absorbent filter medium is placed or suspended below the storm water inlet to filter and remove oil, grease, and other non-volatile organic contaminants that enter with the runoff. Such devices are exemplified in the disclosures of U.S. Pat. No. 5,820,762, U.S. Pat. No. 5,849,198, U.S. Pat. No. 6,368,499, and U.S. Pat. No. 6,872,029, as well as U.S. Patent App. Pub. No. US 2008/0023408 A1. Still another class of devices involves placing a basket or trap, alone or in combination with other filter devices and/or media, in or below the storm water inlet, as exemplified in the disclosures of U.S. Pat. No. 5,232,587, U.S. Pat. No. 5,284,580, U.S. Pat. No. 5,720,574, U.S. Pat. No. 6,080,307, U.S. Pat. No. 6,106,707, U.S. Pat. No. 6,287,459, U.S. Pat. No. 6,531,059, U.S. Pat. No. 6,797,162, U.S. Pat. No. 6,884,343, U.S. Pat. No. 7,083,721, U.S. Pat. No. 7,094,338, U.S. Pat. No. 7,270,747, and U.S. Pat. No. 7,922,916, as well as U.S. Patent App. Pub. No. US 2002/0057944 A1. Many of these devices have one or more drawbacks, including a bypass for overflow conditions that allows runoff to evade treatment entirely during excess flow conditions, or a catch mechanism formed of an open grate or mesh that allows small particulates and/or dissolved and suspended materials to pass unimpeded into downstream sewage systems and waterways.
More recently there has been a trend toward more complex systems using multiple filter media, incorporating plantings and other living materials, or having extensive underground mechanical operations. Such devices are exemplified in the disclosures of U.S. Pat. No. 6,277,274, U.S. Pat. No. 6,569,321, U.S. Pat. No. 6,719,910, U.S. Pat. No. 7,080,480, U.S. Pat. No. 7,625,485, U.S. Pat. No. 7,632,403, U.S. Pat. No. 7,638,066, U.S. Pat. No. 7,833,412, and U.S. Pat. No. 7,837,868, as well as U.S. Patent App. Pubs. No. US 2003/0047502 A1, No. 2006/0157423 A1, No. 2006/0163147 A1, No. 2008/0121579 A1, No. 2008/0121594 A1, No. 2008/0245710 A1, No. 2009/0039022 A1, No. 2010/0108617 A1, No. 2010/0150654 A1, No. 2010/0025313 A1, and No. 2011/0247973 A1.
A need therefore remains for a simple, effective filter device that can be retroactively fitted to a storm water inlet, wherein the device does not protrude or extend above street level or otherwise cause an obstruction on the surface being drained, that is capable of removing large objects, sediment and other suspended particulates, and metal and petroleum-based contaminants, and that does not allow storm water to bypass the treatment element entirely during any conditions. These needs are provided for by the present invention, as set forth in the description and claims that follow.
The problems encountered in effectively treating storm water runoff in a storm water inlet are resolved in many respects by the present invention.
In a first aspect, the invention is a filter for a storm water inlet having a surface opening for receiving storm water runoff containing liquids and solids. The opening discharges the runoff into an interior compartment below the opening having a substantially vertical interior wall or walls defining a cross-sectional area. The filter includes one or more molded, porous filter elements, and the filter element or elements are formed such that the filter substantially fills the entire cross-sectional area of the interior compartment.
In a second aspect, the invention is a storm water inlet, including a surface opening for receiving storm water runoff containing liquids and solids and discharging the runoff into an interior compartment below the opening. The interior compartment has a substantially vertical interior wall or walls defining a cross-sectional area. The storm water inlet further includes a filter formed of one or more molded, porous filter elements, wherein the element or elements are formed such that the filter substantially fills the entire cross-sectional area of the interior compartment.
In a third aspect, the invention is method of adding a filter to a storm water inlet that comprises a surface opening for receiving storm water runoff comprising liquids and solids and discharging said runoff into an interior compartment below the opening, wherein the interior compartment has a substantially vertical interior wall or walls defining a cross-sectional area. The method includes determining the shape of the cross-sectional area of the interior compartment, and casting and hardening a porous material to form one or more filter elements, wherein the filter element or elements form a filter that substantially fills the entire cross-sectional area of the interior compartment below the surface opening, and substantially all runoff entering the interior compartment will encounter the filter.
The foregoing summary and the following description will be better understood when reviewed in conjunction with the drawing figures, of which:
Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.
Pervious concrete (also known as also referred to as porous concrete, permeable concrete, no-fines concrete, gap-graded concrete, or enhanced-porosity concrete) is a form of concrete with an open-pore structure that even after curing allows water to penetrate and pass through the hardened material. Mix designs for pervious concretes will vary depending on the application and operating conditions, but pervious concrete mixes are characterized generally by low water/cement ratio, low slump, narrowly graded coarse aggregate, and little or no fine aggregate compared to standard, non-pervious mixes. It is held together by cementitious paste at the coarse aggregate contact points and has an open-pore structure since there is limited paste and fine aggregate to fill the resulting voids.
Generally, a pervious concrete mix according to aspects of the present invention contains the following basic ingredients: water, a cementitious material including portland cement and optionally a supplementary cementitious material, aggregate, and optionally one or more typical concrete mix additives, such as water reducers, retarders, viscosity modifiers, fibers, bonding agents, etc. A pervious concrete mix design may include from 375 lbs/yd3 to 700 lbs/yd3 of cementitious material and 2000 lbs/yd3 to 3000 lbs/yd3 of aggregate sized for pervious concrete, with a water to cementitious material ratio of 0.20 to 0.45. These materials and amounts may be varied by those of skill according to the demands and requirements of a particular application and are not intended to limit of this or any other embodiment of the invention except as expressly described or claimed. An ideal pervious concrete mix is characterized as having an oily or metallic sheen on the cementitious paste, and a consistency such that a handful of the paste, when squeezed, will neither stick excessively nor separate completely from the hand, leaving only a scattering of aggregate and paste on the surface.
A general description of pervious concrete mix designs may be found in Design Guide 211 published by the American Concrete Institute (ACI). Other exemplary pervious concrete mix designs have been published by, for example, the California Nevada Cement Promotion Council, the Indiana Ready Mixed Concrete Association, the National Concrete Pavement Technology Center at Iowa State University, and the National Ready Mixed Concrete Association, among others. Variation from these published and other known pervious concrete mix designs by those of skill may be required to obtain a desired porosity, in view of available materials, or to obtain a desired strength in view of acceptable porosity, without departing from the present invention.
The void content of pervious concrete may range from about 15% to about 35% by volume of the cured material. The lower limit of void content in a pervious concrete according to aspects of the present invention can be as low as at least 10% by volume, preferably at least 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20% by volume. The upper limit of void content in the pervious concrete according to aspects of the present invention can be up to 35% by volume or more, preferably up to 34%, 33%, 32%, 31%, 30%, 29% m, 28%, 27%, 26%, or 25% by volume. Such void fractions typically correspond to water drainage rates of about 2 gal/ft2-min to about 18 gal/ft2-min. A pervious concrete according to aspects of the present invention may have a hydraulic conductivity (coefficient of permeability) of about 30 in/hr up to about 900 in/hr, with 480 in/hr (0.34 cm/sec, corresponding to about 5 gal/ft2-min or 200 L/m2-min) being typical.
In a first aspect, the present invention is a filter for a storm water inlet having a surface opening which receives storm water runoff from the surface being drained and discharges the runoff containing liquids and dissolved and suspended solids into an interior compartment below the surface opening. Although the present invention filter can be used in many different types of storm water inlets, the filter is particularly well suited for use in precast, concrete curbside storm inlets that are commonly designed into the sides of paved streets. As a result, by way of example, the filter of this invention will be described in conjunction with typical curbside storm water inlets in order to set forth the best mode contemplated for the practice of the present invention.
Referring now to
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A common design feature of these storm water inlets is the vertical interior wall or walls of the precast concrete catch basin extending below the surface opening of the inlet to the bottom of the basin. These walls, as shown in figures
In a further aspect, the present invention is a storm water inlet incorporating the filter of the invention. Accordingly, the inlet has a surface opening that receives storm water runoff comprising liquids and solids and discharges the runoff into an interior compartment below the surface opening. The interior compartment of the inlet has a substantially vertical interior wall or walls that define a cross-sectional area. Finally, the inlet includes a filter comprising one or more molded, porous filter elements, the element or elements being formed such that the filter substantially fills the entire cross-sectional area of the interior compartment when positioned therein.
Referring now to
In a preferred embodiment of the storm water inlet of the present invention, the vertical wall or walls of the interior compartment of the catch basin form a substantially circular, elliptical, or rectangular cross-sectional area. It is also preferred that the interior compartment comprises a catch basin having one or more outlet openings connected to a storm sewer. A preferred storm water inlet according to the invention is provided with a means for access to the interior compartment for installing and removing the filter. Such means may include a manhole with a removable manhole cover and/or a feature wherein the grate covering the surface opening may be removed or opened to provide access to the interior compartment of the catch basin.
As shown in
In a further aspect, the present invention is a method of adding a filter to a storm water inlet having a surface opening that receives storm water runoff comprising liquids and solids and discharges the runoff into an interior compartment below the surface opening. The interior compartment of the inlet has a substantially vertical interior wall or walls defining a cross-sectional area. The method according to the invention includes the steps of determining the shape of the cross-sectional area of the interior compartment, and casting and hardening one or more filter elements comprising a porous material, preferably a pervious concrete, to form a filter that substantially fills the entire cross-sectional area of the interior compartment, such that substantially all runoff entering the interior compartment will encounter the filter.
The filter can be precast and installed in the catch basin or formed in place in the basin. Thus in one embodiment, the inventive method may further include the steps of forming a mold or combination of molds for casting the one or more filter elements to form the filter that will substantially fill the entire cross-sectional area of the interior compartment, casting and hardening the porous material, preferably a pervious concrete, in the one or more molds to form the one or more filter elements, and installing the one or more filter elements within the interior compartment of storm water inlet.
As shown in
These and other aspects of the invention provide advantages over known catch basin filters. Because the filter fills a cross-section of the catch basin, and in a preferred embodiment is sealed against the catch basin walls, virtually no runoff can bypass treatment by the filter. Large objects, debris, and trash will be retained in the upper end of the catch basin nearer the maintenance access where they can be collected more conveniently during maintenance than from the bottom of the catch basin. Moreover, the liquid component carrying dissolved and suspended contaminants is provided with the beneficial treatment of concrete filtration, which simultaneously removes organic, metallic, and biological contaminants. The pervious concrete filter elements are durable, robust, and themselves require little to no maintenance save for replacement after their expected service life of several years.
While preferred embodiments of the invention have been shown and described herein, it will be understood that such embodiments are provided by way of example only. Numerous variations, changes and substitutions will occur to those skilled in the art without departing from the spirit of the invention. Accordingly, it is intended that the appended claims cover all such variations as fall within the spirit and scope of the invention.
This application claims the benefit of priority to provisional application Ser. No. 61/782,424 filed Mar. 14, 2013, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61782424 | Mar 2013 | US |
