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I. FIELD OF THE INVENTION
The present invention relates to a storm water filtration system for use
with conventional storm water collection sewers. The filtration system is
designed for installation within a right-of-way, e.g., behind the curb of
a street, or within the inlet storm system of a parking area. Treated
storm water from the system will discharge to existing, conventional
inlets and storm sewers. The filtration system will treat storm water
runoff without blocking or inhibiting the evacuation of storm water
through the sewer, therefore avoiding any possible liability due to flood
damage.
II. DESCRIPTION OF THE PRIOR ART
Presently, storm water is collected through a series of grated or recessed
inlets placed in pavement and/or curb sections, and then conveyed via
storm sewer piping to an outfall in an existing drainage way or stream.
There is no treatment or attempt to remove sediment, trash or other
pollutants. This arrangement quickly conveys storm water away from
structures and property and avoids water or flood damage and protects life
and limb. However, it also contributes to the pollution of surface and
subsurface water supplies: oils, greases, solvents, sediments, trash,
etc., are washed from impervious areas, such as streets and parking lots,
as well as storage yards rooftops, etc., by the storm water and are
discharged with that water into streams, lakes and ground water recharge
areas, contributing to the accumulative pollution of the water supply.
Moreover, the sight of waste material, such as food and beverage
containers, floating on streams and waterways is a visible reminder to the
public of contamination and pollution of the water supply.
There are large urban areas where development has progressed to a point
where storm runoff is conveyed entirely across pavement, roof tops and
parking lots, without the benefit of the natural filtering which occurs
when storm water runs over grasslands or vegetated areas. Because of the
density and value of development in these urbanized areas, it is important
to remove the storm water and avoid water/flood damage liability.
Moreover, given that rainfall amounts of up to eight inches an hour can
occur, removal must be accomplished quickly and unfailingly. It is,
therefore, unacceptable to place filter apparatus in storm water
conveyance ways because of the risk of overloading/plugging and resultant
inhibition of flow.
The prior art contains disclosures of sewage systems in which filters are
provided to prevent sediment and solid waste materials entering the main
sewer line and some of these include a removable basket in which the
filtered-out solid material is retained to facilitate cleaning and
replacement. However, in the prior art, the filters are essentially in
line with the main flow of water into the sewer and so, when full, can
obstruct the flow of water and cause flooding or damage.
U.S. Pat. No. 658,639 (Guion) discloses a receiving basin for a sewer
system which is divided by a vertical screen G into compartments A and H.
A removable metal basket I is normally housed in compartment A and
incoming water is directed into that basket I, which retains sediment.
Water can pass through foraminous sides of the basket I into the
compartment H of the basin which contains filtration material and hence to
the sewer.
U.S. Pat. No. 664,945 (Guion) discloses a kitchen sink comprising a chamber
formed by a casing 7 mounted below the sink and housing a removable filter
vessel 11 into which the sink discharges. The filter vessel 11 is
foraminous to allow water to pass through it to an outlet for the chamber
and thence to a receptacle 15 from which a siphon withdraws it to the
drain.
U.S. Pat. No. 1,746,121 (Levy) discloses a catch basin for a sewer in which
the basin 12 is provided, between its inlet 10 and the sewer, with a
removable basket 16 into which incoming water is directed and which
retains solid materials.
U.S. Pat. No. 809,201 (Lutz) discloses a receiving basin for a sewage
system that receives surface water from streets. The receiving basin is
intended to catch sediment in the water and prevent it from being carried
into the sewer. The basin houses a removable basket B into which incoming
surface water is directed. The basket B has a main, screened opening Q
through which surface water passes from the basket through the basin, and
subsidiary outlets R and S. Subsidiary outlet S allows water to escape
around the basket if the basket is full of sediment.
U.S. Pat. No. 2,615,526 (Lane) discloses a catch basin for a sewer which is
provided with a removal filter basket B formed of a screen 27, angle irons
24 and 25 and sheets 28 and 29.
U.S. Pat. No. 2,102,310 (Egan) discloses a removable receptacle 4 for
insertion within a receiving basin of a sewer. The receptacle 4 has a
spiral arrangement of discharge ports through which incoming water can
flow to the sewer.
U.S. Pat. No. 4,419,232 (Arntyr) discloses a filter device for outdoor
drains in roadways, etc., comprising a grating 12, below which is mounted
a course-filtering, wire basket 2 and below that a fine filtering bag 3 of
flexible water-permeable cloth or fabric.
U.S. Pat. No. 4,793,728 (Ellis) discloses a subsurface water drainage
system comprising a fabric filter tube 18 arranged parallel to a pavement
14 to be drained and connected at its discharge end 34 to the main sewer.
III. OBJECTS OF THE PRESENT INVENTION
It is an object of the present invention to overcome both the lack of
filtration and the danger of inhibiting the removal of storm runoff
existing under present arrangements.
It is a further object of the invention to provide a system for removing
trash, and other pollutants from storm water run-off without the use of
extensive acreage devoted to slow sand filter treatment beds, which could
require one-half acre of filter bed to treat each 30 acres of storm
receiving land. This size filter bed is expensive to provide, particularly
in urban areas.
IV. SUMMARY OF THE PRESENT INVENTION.
The present invention provides a storm water filtration system for use with
conventional storm water collection sewers, including an inlet filtration
system comprised of a filter basin, a removable filtration basket housed
within the basin and ancillary connections to the conventional storm
collection system. The inlet filtration system would be placed upstream of
the conventional storm water inlets.
The filter basin is preferably poured in place and is configured to drain
to the conventional storm inlet via an outlet in the basin and a pipe
connector. The filter basin may have a recessed cavity upstream of the
outlet, which may house a removable filter cartridge. This optional filter
cartridge is of a material selected to remove particular storm water
constituents, such as solubilized organic or inorganic pollutants.
The filtration basket holds the filter media, is perferably constructed of
metal and is adapted to receive a forklift assembly of a conventional
waste-disposal collection vehicle. The basket has a hinged metal lid
arranged to swing open when the basket is inverted over the waste-disposal
vehicle's waste holding cavity. The configuration of the filter basin and
therefore the weight/volume of the anticipated load controls the material
and strength requirements of the basket.
The filtration system of the present invention is installed adjacent to
storm water inlets to provide a level of treatment of the storm water
runoff prior to its discharge to a storm sewer. The filtration systems of
the present invention will normally be constructed to discharge to the
conventional basin of a storm sewer, though in certain applications it may
be desirable to discharge directly into the sewer line downstream of the
storm sewer inlets. As storm sewer inlets are also located at low points,
it may be necessary to locate filtration systems on both sides of a sewer
inlet.
The installation of the invention in existing urbanized areas will require
removal of existing curb, sidewalk and pavement. The structure will be
located adjacent to the existing inlet and is designed to discharge
directly to the inlet. Therefore, the installation will require cutting
into the existing inlet for the physical connection, or designing new
inlets to incorporate this unit.
In general, the installation of a sufficient number of these filtration
systems would greatly enhance the quality of the runoff from urbanized
watersheds.
V. BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described, by way of example only, with reference
to the accompanying drawings, wherein like reference characters refer to
like parts throughout the several views, and in which:
FIG. 1 is an exploded perspective view of a storm-water filter assembly
embodying the invention;
FIG. 2 is an exploded and sectional rendering of the interior features of
the embodiment shown in FIG. 1;
FIG. 3 shows schematically the installation and maintenance of the
embodiment shown in FIGS. 1 and 2;
FIG. 4 is a detailed perspective view of the trash trap door of the
embodiment shown in FIGS. 1 and 2;
FIG. 5 is a cut-a-way view showing the embodiment of FIGS. 1 and 2
installed adjacent to a conventional storm sewer system; and
FIG. 6 is a perspective view of the lower parts of the embodiment shown in
FIG. 2.
VI. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE PRESENT
INVENTION
In FIG. 5, a conventional below-ground storm sewer line 11 receives runoff
water from a below-ground receiving chamber 12, which, in turn, is fed by
a receiving basin 13 installed below ground, e.g., adjacent to a curb 15
and under the pavement 17 of a road 19 (see FIG. 3). The receiving basin
13 has an upper inlet 21, which receives runoff water from the roadway 19
and as lower outlet 23 communicating with the receiving chamber 12 for
transmitting the runoff water to the sewer line 11.
A filter assembly 25 embodying the invention, and best seen in FIGS. 1 and
2, is mounted below the roadway 19 adjacent to the receiving basin 13,
preferably on the upgrade side of the basin 13. The filter assembly 25
comprises a concrete, poured-in situ, basin 27 providing an open-topped
chamber in which is accommodated a removable filter basket 29.
The basin 27 has a bottom wall 31 in which is formed a downwardly disposed
chamber 33, having at one or both of its ends an opening 35 below the
bottom wall 31 which provides an outlet from the basin 27. A screen 36 is
mounted in the, or each, opening 35. Optionally, the other end of the
chamber 33 may have a second screened opening 38 (FIG. 6) for a purpose
described below.
The basin 27 further comprises front, back, left and right side walls, 37,
39, and 41 and 43, respectively, disposed essentially vertically. An upper
portion of the front wall 37 is omitted, for a purpose described below.
Within the basin 27 is removably housed the filter basket 29, which
comprises essentially a metal box, having a lid 45, front, back and side
walls 47, 49, 51 and 53, respectively, and a base 55. The lid 45 is
advantageously of steel and is connected to the back wall 49 by, e.g., a
pair of hinges 57, which are welded to the wall 49 and lid 45. An upper
portion of the front wall 47 is omitted to form a slotted opening 59,
which is in register with the upper omitted portion of the front wall of
the basin 27 when the basket 29 is housed in the basin 27 and provides a
water inlet to the basket 29 and basin 27. The upper edge of the front
wall 47 provides a support for the lid 45 when the lid 45 is closed.
A trap door 61, see FIG. 4, preferably formed of a light, buoyant plastics
material, is hinged, as at 63, to the interior of the front wall 47 of the
basket 29 for closing the opening 59.
Two lifting channels 63 and 65 are provided along the upper edges of the
side walls 51 and 53 of the basket 29 and are open at their front ends to
allow the basket 29 to be engaged by the tines of a conventional solid
waste collection vehicle 66 for installation and removal, as shown in FIG.
3.
The base 55 of the basket 29 has an opening 67, FIG. 2, which is in
register with the channel 33 when the basket 27 is installed in the basin
13. A grill 69 extends across the opening 67 to prevent large, solid
debris from passing through it. A filtration media (not shown) of, for
example, washed, course, sand, gravel or sand/gravel mixture is contained
within the basket 29 and a replaceable filter cartridge 71, FIG. 6, e.g.
of activated carbon, or resin bead mixture, is housed in the chamber 33
below the grill 69.
If the water level in basket 27 rises, the trap door 61 floats on the
surface of the water and eventually closes the opening 59, preventing
backwash of solid materials collected in the basket 27. When the trap door
61 is closed, or flow through the filter assembly is otherwise obstructed,
storm water runs past the opening 59 of the assembly 25 and passes
directly to the receiving basin 13, so there is no risk of the filter
assembly 25 causing flooding when it is too full to allow passage of water
through it.
At a suitable time, the basket 29 is removed from the basin 27 by means of
the conventional waste-disposal collection vehicle 66 (FIG. 3), the tines
of which can be inserted into the lifting channels 63 and 65. Thereafter,
the basket 27 is lifted from the basin 29 and inverted over the vehicle
receptacle. The debris and spent filtration media fall past the open lid
45 into the vehicle 66. Thereafter the basket 29 can be recharged with
fresh filtration media. Also at this time, the channel 33 in the basin 27
is exposed to enable the filter cartridge 71 to be replaced also.
The sand or other filtration media 69 removes large, floating items of
trash, such as paper, cardboard, cigarette butts, and larger suspended
solids, such as grit, salts and disintegrated motor tires. The filter
cartridge 71 is intended to remove pollutants dissolved, or intimately
mixed into the sewer water, such as motor oils and greases, or
improvidently discharged chemicals. If the location at which the filter
assembly 25 is to be installed is known to be at risk from a particular
pollutant, e.g. motor oils and greases, the filter cartridge 71 can be
selected to target that particular pollutant.
Several of the filtration assemblies 25, as described, can be used in
sewers along, e.g., a roadway, each receiving the storm water from a
particular section of roadway. The outlets 35 of each basin 27 can be
connected to a common pipe communicating with the receiving basin 13.
Alternatively, using the embodiment shown in FIG. 6, the assemblies 25 can
be arranged in series with the outlet 35 of each chamber 33 connected to
the screened opening 38 of the chamber 33 of the next down-stream assembly
25.
The assembly 25 can be retrofitted to existing systems with minimal
expense, requiring only the excavation of part of the sidewalk, curb and
pavement and no acquisition of new land. Certainly, the assembly 25 is a
considerably more economic use of land than the provision of the
filtration beds for the treatment of storm water.
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