Note: Descriptions are shown in the official language in which they were submitted.
CA 0222647~ 1998-01-08
OIL TRAP FOR CATCH BAS IN
The present invention relates to devices for
trapping and removing oil contaminants from water which
flows into catch basins and other drainage openings.
The flow of water contaminated with oil into
storm sewers and other drainage systems poses an important
environmental concern. In various regions, regulations and
by-laws have come into force which prohibit the discharge
of water cont~;n;ng oil and grease into storm sewers. One
common source of contaminated water in storm sewer systems
is untreat:ed water which flows into such systems through
catch basins. As referred to herein, catch basins are
substantially vertical shafts which are provided to permit
water and other fluids to drain into storm sewer systems
and other drainage systems or water storage systems. Catch
basins are often square or rectangular in plan view, and
are usually covered with a steel grate.
Catch basins are generally provided in or near
parking lots and other paved surfaces in order to provide
drainage for water generated on such surfaces from rain and
from other sources. Often, water which drains into catch
basins frc,m paved surfaces is contaminated with oil. The
contamination can occur in various ways. For example,
motor oil, grease, transmission fluids and other oil-based
materials are frequently (and often inadvertently)
deposited on paved surfaces everyday by the vehicles which
pass over and stop on such surfaces, and these pollutants
are pickecl up by water which comes into contact with the
paved sur~aces. Additionally, water which comes into
contact wi-th vehicles, such as water used to wash vehicles,
often becomes contaminated with oil. The problem of oil-
contaminated surface drainage water is exacerbated when the
surface is near an area such as a gas station, a place
where vehicles are washed, or other industrial settings.
~ CA 0222647~ 1998-01-08
~.
In the past, various devices have been proposed
for the purposes of containing oil spills and oil-
contaminated water. For example, U.S. Patent No. 5,547,312
issued Auc3ust 20, 1996, to J. Schmitz Jr. describes an
apparatus for use with a sump for containing run-off
produced after washing vehicles. However no means for
trapping and removing oil contaminants from water is
disclosed.
10I~.S. Patent No. 5,181,802 issued January 26,
1993, to N. Thengs et al. describes an oil collector that
can be used to combat oil spills and that uses an oil-
absorbent material that is encased within a plurality of
parallel cylindrical stockings that form a mat which can
15then be ro:Lled up to form a section of a boom.
rJ.s. Patent No. 4,798,754 issued January 17, 1989
to L.S. Tomek describes an oil absorbent floor mat designed
to be placed under a motor vehicle or a machine. U.S.
20Patent No. 5,020,638 issued June 4, 1991 to P.N. Smith
describes a device for catching liquids dripping from a
vehicle which comprises a tray, an absorbent pad and a bag
assembly for containing the pad.
25None of the above patents appear to disclose a
device that is capable of removing oil based contaminants
from water which flows into catch basins. Thus, a device
which can remove at least some oil contaminants from water
which flows into a catch basin is desirable.
It is an object of the present invention to
provide an inexpensive oil trap for a catch basin or
similar structure installed in the ground, this trap
containing an oleophilic substance.
It is a further object of the invention to
provide an oil trap that comprises a trough structure,
CA 0222647~ 1998-01-08
including ~ bottom and inside and outside walls, and an oil
absorbing substance received by the trough.
In accordance with one aspect of the invention
there is provided an oil trap for a catch basin or similar
structure installed in the ground. The oil trap comprises
a continuous trough extending around a central opening.
The trough has a bottom, an inside wall extending
substantially upwards from the bottom and an outside wall
extending substantially upwards from the bottom and spaced
from the inside wall. The bottom has a plurality of holes
formed therethrough for permitting fluids to drain from the
trough. The trough is mountable within a catch basin or
similar st;ructure so that during use thereof at least a
portion of the fluids entering the catch basin or similar
structure will enter the trough. An oleophilic substance
is receive~d within the trough and extends substantially the
length of the trough such that in use at least a portion of
the fluids that enter the trough will come into contact
with the oLeophilic substance and be absorbed thereby.
Preferably, the oleophilic substance is
contained within at least one sock constructed from a fluid
permeable material, the at least one sock being received
within the trough. Additionally, a fluid permeable rigid
guard can extend between the inside wall and the outside
wall of the trough over the at least one sock for
substantially the length of the trough to provide
protection for the at least one sock.
According to another aspect of the invention, an
oil trap for a catch basin or similar structure to be
installed in the ground comprises an upwardly opening
continuous trough member defined by an upwardly extending
inside wall, an upwardly extending outside wall, and a
bottom extending between said inside wall and said outside
wall. The trough has a number of holes formed
CA 0222647~ 1998-01-08
therethrough, and the trough is moun1able in a catch basin
so that at least a portion of the fluids entering the catch
basin wil] pass through the trough. At least one sock
containing an oil absorbing substance is received by the
trough such that the oil absorbing substance is distributed
substantially along the length of the trough.
Preferably, the oil trap is combined with a catch
basin. The oil trap can be mounted within the catch basin
adjacent a top thereof, wherein the oil trap has external
horizontal dimensions corresponding closely to internal
horizontal dimensions of the catch basin so that the
outside wall of the trough member runs substantially
parallel to and less than 1.5 inches from adjacent walls of
the catch basin. Conveniently, a sealant can provide a
waterproof seal between the outside wall and the adjacent
walls of the catch basin.
According to a further aspect of the invention,
an oil trap for installation in a catch basin or a similar
below growld structure comprises atrough extendingabout
and defining an open area and having a bottom, an inside
wall extending substantially upwards from an inner side of
the bottom, and an outside wall extending substantially
upwards from an outer side of the bottom and spaced from
the inside wall. The trough has holes formed therein for
permitting water to drain from the trough and the trough is
mountable within the catch basin or similar structure in
order to catch at least a portion of fluids entering the
catch basin or similar structure through a top end thereof.
The trap t~lso comprises an oil and petroleum absorbing
substance received within and extending along the trough
and supporl_ed thereby. Preferably, the trough has several
sides that extend around the open area and the absorbing
substance is contained within at least one sock constructed
from a fluid permeable fabric. An open top of the trough
can be covered by a substantially rigid mesh in order to
- -
CA 0222647~ 1998-01-08
.
protect the at least one sock and the absorbing substance
therein.
Further ~eatures and advantages will become apparent
from the following detailed description of the preferred
embodiment!; taken in conjunction with the accompanying
drawings.
In the drawings,
Figure 1 is a top view of an oil trap constructed
in accordallce with the invention;
I?igure 2 is a side elevation of the oil trap of
Figure 1;
E?igure 3 is a bottom view of the oil trap of
Figure 1;
E?igure 4 is a perspective view of a corner
section of the oil trap of Figure 1;
E?igure 5 is a perspective view of a straight
section of the oil trap of Figure 1;
E?igure 6 is an elevational view in cross-section
showing the oil trap mounted in a catch basin, the cross-
section of the oil trap being taken along the line VI-VI of
Figure 1; ~nd
E?igure 7 is a top view of an oil trap constructed
in accordallce with a further embodiment of the invention.
Referring to Figure 1 and Figure 2, an oil trap
device in accordance with the present invention is
indicated qenerally by the arrow 10. The oil trap device
10, which can be installed in a conventional catch basin,
includes a trough portion 12, one or more oil absorbing
,
CA 0222647~ 1998-01-08
socks 48, and optionally, a mesh guard 50. The trough 12
is a continuous trough with four sides 14, 16, 18 and 20.
Each side of the trough includes an outside, vertically
extending wall 22, and inside, vertically extending wall 24
and a horizontally extending bottom 26. The inside wall 24
defines a central opening 66.
Referring to Figure 3, which shows a bottom view
of the trough 12, a large number of apertures or holes 28
extend through the bottom 26 of the trough 12. As will be
explained in greater detail below, the numerous holes 28
are provided to permit water to drain through the bottom 26
of the trough 12. Conveniently, the holes 28 may be
circular :in form and approximately 3/16 of an inch in
diameter.
~ eferring now to Figures 1, 4 and 5, one
embodiment of the trough 12 will hereinafter be described.
In a preferred embodiment, the trough 12 is comprised of
four ident;ical corner trough sections, one of which is
indicated by the arrow 30 in Figure 4, and four identical
straight trough sections, one of which is indicated by the
arrow 32 :in Figure 5. The corner sections 30 and the
straight sections 32 can be formed from a suitable rigid
plastic, ;uch as PVC. In order to allow the corner
sections 30 and the straight sections 32 to be connected
together, each corner section 30 includes two connecting
members 34 which are integrally attached to two ends 35 of
a corner trough member 36. The connecting members 34 are
dimensioned to slidably receive an end 41 of a straight
section 32 and snugly engage the outer surface of the
received end 41. Preferably a silicone sealant and/or
bonding agent is placed between the inside surface of the
connecting member 34 and the outside surface of the
received end 41 of a straight section 32 to strengthen the
joint between the two and also to make the joint
impermeable to water. The connecting members also include
CA 0222647~ 1998-01-08
downwardly opening channels 38 for engaging the upper edges
40 of the inside and outside walls of the received end 41
of the straight section. When the end 41 of the straight
section 32 is received by the connecting member 34, the
inside surface 42 of the straight section 32 is
substantially flush with the inside surface 37 of the
corner portion 36.
Each straight section 32 includes elongate ribs
46 extending along its inside surfaces below and parallel
to the top peripheral edges 40 of the straight section 32.
The ribs ~16 serve to strengthen the straight section 32.
In one pre~erred embodiment the top edges of the inside and
outside wc3.11s of the straight section are approximately
4.25 inch,es (11 centimetres) apart and the trough is
approximat~31y 2 inches (5 centimetres) deep.
Referring to Figures 1 and 2, in combination with
the trough portion 12, the oil trap of the present
invention comprises one or more oil absorbing, elongate
flexible socks or tubes 48 which are laid along and
received within the trough 12. The socks 48 extend the
entire perlmeter or for most of the perimeter of the trough
12 and have a transverse cross-sectional area slightly less
than the area defined by the inside surfaces of the trough
12 such th,at fluids entering the trough 12 will generally
come into contact with the socks 48 before draining out of
the trough 12. In the embodiment of the invention
illustrated in the figures, two socks 48 are received
within the trough member 12.
The socks 48 are comprised of a liquid permeable
flexible fabric shell which is stuffed with a substance
having o]eophilic and hydrophobic properties. One
oleophilic and hydrophobic substance that is suitable for
use in the socks 48 is 3M Brand Oil Sorbent (trade-mark).
CA 0222647~ 1998-01-08
The oil trap 10 of the present invention
optionally can include a plurality of substantially rigid
mesh guards 50 which are placed over the four sides 14, 16,
18 and 20 o~ the trough 12 to protect the socks 48 ~rom
sticks, stones and other debris that may fall onto the trap
10. In the embodiment illustrated in the figures, four
elongate mesh guards 50 are provided. The guards 50 are
each made of a resilient elongated section of galvanized
metal mesh or rigid plastic mesh and have a semi-
cylindrical shape which permits the guards 50 to beinstalled on the sides 14, 16, 18 and 20 of the trough 12
over the tubes 48. When the mesh guards 50 are installed
on the trough 12, their elongate edges rest against and are
supported by the inner surfaces of the inside walls 24 and
outside wLlls 22 of the trough 12. Preferably, the
transverse distance between the two elongate edges o~ each
mesh guard 50 is such that the guards 50 must be compressed
slightly to install them on the trough 12 so that once the
guards 50 are installed, their elongate edges are urged
outwards against the walls of the trough 12. The force of
the edges of the guards 50 along the walls of the trough 12
aids in keeping the guards 50 in place, yet permits them to
be easily removed so that the oil absorbing socks 48 can be
removed and replaced or cleaned when necessary.
~ s mentioned above, the oil trap 10 of the
present invention is designed to be mounted in a catch
basin. Referring to Figure 6, a cross-sectional view of
the oil trap 10 mounted in a conventional catch basin 52 is
shown. The catch basin 52 includes a cover grate 54 which
is level w:ith the surrounding ground 56, and which includes
a series c\f elongate parallel openings 58 through which
water can drain into the catch basin 52. The catch basin
52 comprises a vertical, square shaft which may lead to a
storm sewer system.
CA 0222647~ 1998-01-08
The oil trap 10 is mounted in the catch basin 52
such that the mouth of the continuous trough 12 opens
upwards and lies in a generally horizontal plane. The
trap 10 i~; preferably mounted so that it is a few inches
below the bottom of the catch basin cover S4. In one
preferred embodiment, the top of the trap 10 is located
about six inches below the adjacent ground level 56. The
dimensions of the outer perimeter o~ the oil trap 10 are
such that the outside walls 22 of the trough 12 are snugly
received by the walls 60 of the catch basin 52.
Preferably, any gap which is present between an upper
peripheral edge 64 of the outside wall 22 and the walls 60
of the catch basin 60 is less than 1.5 inches (3.81
centimetre3). A silicone sealant may be placed around the
junction formed between the top peripheral edge 6~ of the
outside wall 22 and the walls 60 of the catch basin 52 in
order to ~;eal any gaps and ensure that fluid that flows
along the walls 60 flows into the trap 10.
E3rackets are preferably used to mount the oil
trap 10 iirl a catch basin. In the embodiment shown in
Figure 6, eight L-shaped brackets 62, which are fastened
two per side to the concrete walls 60 of the catch basin
52, support the underside of the trough 12. The L-shaped
brackets 62 can be fastened to the concrete walls of the
catch basin 52 in a variety of different ways. In one
preferred ~embodiment, the L brackets 62 are mounted to the
walls 60 by charge-driven concrete nails. The brackets 62
could alternatively be attached to the wall 60 by self-
tapping concrete screws set in predrilled holes, or by
screws att~ched to anchors which have been inserted into
predrilled holes. A suitable adhesive could also be used.
The L bra~kets 62 can, if desired, be attached to the
bottom of the trough 12 by bolts secured with nuts, said
bolts passing through predrilled holes provided through the
bottom 26 of the trough 12. In the alternative, it can
simply res-t; on the brackets, thus permitting the trap to be
CA 0222647~ 1998-01-08
removed easily from the catch basin.
Referring to the figures, the operation of the
oil trap 10 of the present invention will now be described.
As mentioned above, catch basins such as the catch basin 52
illustratecL in Figure 6 are often located in or near
parking lots and other paved surfaces in order to provide
drainage for water generated on the surfaces, either by
rain or from other sources. The water entering the catch
basin 52 will often be contaminatecL with oil and grease
which has been deposited on a paved surface in a variety of
ways, such as from dripping oil pans and leaking
transmissions, or from oil which has been washed off cars
and other vehicles. The oil trap 10 of the present
invention is provided to remove at least some of the oil
cont~m; n~n~s from at least some of the water which enters
the catch basin 52.
It will be appreciated that water entering the
catch basin 52 from the surrounding surface 56 will
generally enter the catch basin 52 by falling downwards
into the bc~sin at or near the edges of the opening that is
defined by the basin. In other words, water entering the
catch basin 56 will generally enter the basin at or near
the top ecLges of the walls 60 of the basin. As such, a
large perc,entage of the water flowing into the catch basin
52 will flc)w downwards along the walls 60, or within a few
inches of the walls 60, especially near the top of the
basin. As the trough 12 of the trap 10 generally extends
outwards from the walls 60 of the basin (approximately 4.25
inches (11 centimetres) in one preferred embodiment), a
large percentage of the water entering the catch basin 52
will generally pass through the mesh guards 50 and into the
oil trap 10.
~!~ost of the water entering the oil trap 10 will
come into contact with the oil absorbing socks 48 before
CA 0222647~ 1998-01-08
. ~ .
11
the water can drain out of the trap 10. The water may come
into contact with the socks 48 by landing right on top of
the socks 48 after passing through the mesh guards 50.
Additionally, water in the trough 12 can come into contact
with the socks 48 while it is waiting to drain out of the
trough 12. As mentioned above, the socks 48 contain a
material which is both oleophilic (oil loving) and
hydrophobic (water repelling), meaning that the socks 48
have a very high absorbed oil/absorbed water ratio. As a
result, much of the oil and grease which contaminate water
that comes into contact with the socks 48 will be separated
from the water and absorbed or trapped by the socks 48. At
the same t:ime, very little water will be absorbed by the
socks 48. Thus, water leaving the trap 10 will generally
contain less oil contaminants than water entering the trap
10 .
Water which enters the trap 10 will generally
leave the trap by f lowing out of the trough 12 through the
plurality c)f holes 28 which are located in bottom 26 of the
trough 12. However, during periods of continued heavy
water f low, such as a rain downpour, the f low of water out
through the holes 28 may not equal the f low of water into
the trough 12, and the level of water in the trough 12 will
rise to a point where it flows over the top edge of the
inside wal:L 24 of the trough 12, through the large hole 66
and down into the storm sewer. It also is possible that
some water entering the catch basin 52 may by-pass the oil
trap 10 completely and go straight down the hole 66 without
ever coming into contact with the socks 48, especially
during periods of heavy rain. However, the hole 66 is
normally required to ensure that during periods of heavy
water f low the catch basin 52 will not become backed up as
a result of the trap 10.
The socks 58 of the trap 10 periodically have to
be removed so that they can be cleaned and then replaced,
CA 0222647~ 1998-01-08
-
12
or replace~ with new socks 58. In order to maintain the
trap 10, the cover 54 of the catch basin 52 is opened, the
mesh guards 50 are removed from the trap 10, the socks 58
are then removed ~rom the trough 12 and replaced with
either clean or new socks, the mesh guards 50 are replaced,
and then the cover 54 is closed. The frequency with which
the socks 58 have to be cleaned (which involves draining
the absorbed oil from the socks) or replaced will depend on
the degree of oil contamination affecting the water which
passes through the trap 10 and the amount of contaminated
water that enters the catch basin.
If desired, an additional mesh guard 68 (see
Figure 7) c~an be placed over the centre hole 66 of the trap
10 to stop sticks and other debris from entering the storm
sewer system. The peripheral edges of the guard could rest
on the upper edge of the inside wall 24 of the trough 12.
The mesh guard 68 can also be installed directly below the
centre hole 66 with its edges on all four sides resting on
the brackets 62. Alternatively the mesh guards 50 and the
centre mesh guard 68 could be replaced with a single guard
that covered the whole oil trap 10.
It will thus be appreciated that the oil trap 10
of the present invention can be installed in a catch basin
to assist in removing oil contaminants from water entering
the catch basin. Although the oil trap 10 illustrated in
the figures and described above is square, it will be
appreciated that the trap could be rectangular or round or
a variety of other shapes in plan view to accommodate
different catch basin sizes and shapes. Additionally, the
trap could be used in drainage openings other than catch
basins, such as manholes, particularly manholes with covers
or tops that are not sealed. The trough 12 could be
constructed in a variety of ways other than that disclosed
above, for example, the trough could be semi-cylindrical in
cross-section. The trough could be formed from one or more
" CA 0222647~ 1998-01-08
.
~.
13
pieces of galvanized steel or the trough could be formed
from a unitary piece of resilient vinyl or plastic
material. The dimensions of the trough and the holes
therethrough could be varied to best fit the specific
location and application of the trap. Additionally, the
oleophilic and hydrophobic material placed in the trough 12
need not necessarily be contained in socks. For example,
the material could be contained in mats which are rolled up
and then placed in the trough 12.
While various embodiments of this invention have
been illustrated in the accompanied drawings and described
above, it will be evident to those skilled in the art that
changes and modifications may be made therein without
departing from the essence of this invention. All such
modifications or variations are believed to be within the
scope of the invention as defined by the claims appended
hereto.
