Note: Descriptions are shown in the official language in which they were submitted.
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STORM WATER TREATMENT DEVICE
FIELD OF INVENTION
This invention relates to an improvement in a storm water treatment
device which is designed to capture and isolate floatable debris carried in
the storm water and additionally separate particulate materials (which are
generally heavier than water) and free oils (which are generally lighter than
water) from the storm water. This device incorporates a separation
treatment unit within its housing which improves the separation
performance of this device when compared to prior art separation devices.
This is accomplished by passing the storm water through a series of
coalescing plates which are installed in the device to be at a specific angle
io or slope and at a predetermined spacing from each other.
BACKGROUND OF THE INVENTION
With the advent of the petroleum age and the ever increasing
popularity of the automobile, most ground water which becomes run off
is water from parking lots, etc. contains substantial amounts of petroleum
products. Likewise with the increase in urban development and higher
population densities, storm water runoff from these areas will usually
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contain a quantity of particulate material (hereafter referred to as
suspended solids), a quantity of floating debris and a quantity of non-
emulsified liquids which are in most cases petroleum derivatives. Public
awareness of the presence of contaminants increasingly drives regulating
s bodies to pass laws which limit the amount of contaminants found in a
sample of storm water. The public is aware that the contaminated storm
water eventually flows into lakes and rivers and thus the resultant negative
reaction to the presence of the contaminants in the storm water. Because
of the demonstrated lack of suitable equipment to remove these
io contaminants on a large scale from storm water, environmentalists have
been searching for some means to provide some method of separating
these contaminating materials from the storm water. In the past some kind
of device is usually placed in storm water runoff path which attempt to
remove suspended solids and non-emulsified oils from storm water by
is gravitational separation as well as capture coarse floating debris such as
leaves, paper cups, plastic bottles, etc. by screening etc. A large portion
of those contaminants found in storm water runoff will attach themselves
to the fine particulates (suspended solids). Traditionally the removal of
fine particulates and free oils is carried out in large containments also
2o known as settling tanks or ponds where separation occurs due to gravity.
The separation efficiency of these settling devices depends on the depth of
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water in the pond or tank and the length of detention time the storm water
is allowed to remain in those tanks/ponds.
SUMMARY OF THE INVENTION
s This invention provides a vault with one or more chambers, one or
more inlets, one or more outlets and a permanent pool. Storm water will
enter the vault via the one or more inlets and be passed through a screen to
capture and retain large particles of floating debris, thence through a
treatment device in which liquids lighter than water and suspended solids
m are separated from storm water (and each other). The treated storm water
(which now forms part of the pool) is allowed to exit the vault through the
provided outlet or outlets. The treatment device comprises a series of
plates separated from one another by the same distance, and each plate is
mounted on a slant in the treatment device so as to slope downwardly at
is the same angle. The plates are thus held in the treatment device in such
way as to force the stonm water to flow downwardly as it passes
therethrough. As the storm water is forced to flow downwardly each of
the fine particles will continue to settle (by the force of gravity) in the
area
between the plates until its path encounters a plate. The particle is then
2o carried downwardly along the surface of the plate (by gravity and the flow
of the storm water) and ultimately falls to the bottom of the vault where the
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particles accumulate. Concurrently, globules of free oil and/or liquids
lighter than water will continue to rise until the lighter particles encounter
the lower surface of a plate. The globules will slide upwardly along the
lower surface of the plates until they reach the surface of the permanent
s pool. Note that particle agglomeration of the lighter and heavier particles
may occur during the separation process. Access ports are provided as
needed in the vault for periodic inspection and to permit removal of
floating debris, liquids lighter than water, and settled particulate material
from the storm water pool.
io
PERTINENT PRIOR ART
U.S. Patent 5 928 524
This patent describes a multichambered separation tank employing
several stages of separation. In the first instance, all coarse debris is
is removed by debris plates and the preconditioned water is passed through a
coalescing unit in which the plates are very closely spaced. In chamber 32
the oil and grit are separated by coalescing unit 48. Both contaminants are
deposited in chamber 32 and remain there through the operation of the
separator 10.
U.S. Patent S 520 825
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This patent describes an oil-water separation device which uses a
sloping coalescing plate separator to separate the immiscible oil particles
from the water carrying the oil particles. Water flows upwardly through
the plates of the separation device. No mention is made of separation of
s grit particles in the water undergoing treatment.
U.S. Patent 5 049 278
This patent shows a sloping coalescing plate separating device in
which the water (containing sludge) to be treated flows upwardly through
the plates of the separation device. In Figure 3 sludge particles fall
io downwardly under the influence of gravity into hopper 13. No mention is
made of any oil particles which may or may not be suspended in the water
undergoing treatment.
U.S. Patent 4 883 603
This patent is directed to separating coarse grained and
is agglomerated pigment particles from a liquid having the above named
contaminants in addition to fine grained agglomerated particles. The
patent utilizes a mufti plate coalescing device wherein the plates are
mounted on a slope and the water path is directed upwardly through the
slanting coalescer plates. The particles are separated so that the fine
ao grained particles rise to the top of the vessel 1 and the coarse grained
particles drop to the bottom of the same vessel.
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BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a sectional elevation view of the separation device of
this invention.
s FIGURE 2 is a plan section view of the separation device of Figure
1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Figures 1 and 2 show a double chambered tank 10 having a pair of
io chambers 12 and 14 separated by a bulkhead 16. Tank 10 is provided
with two manholes 18 and 20 for access to inlet chamber 12 and outlet
chamber 14 to provide for inspection and pump out of the separated
contaminants. Covers 22 and 24 prevent intrusion into chambers 12 and
14.
is Chamber 12 is provided with an inlet for pipe 26 which carries
contaminated water into chamber 12 of the separation device 10.
A ladder 28 is mounted from the ceiling 30 to allow inspection
personnel to gain access to chamber 12 during operation of the separator
10. A coarse screen 32 is mounted on ladder 28 to separate coarse
2o floating debris (plastic and paper cups, bottles, etc.) from passage to the
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separating device 34. The screen extends completely across the surface 36
of the water contained in chamber 12.
The separation device 34 consists of a containment vessel 38
mounted on brackets 39 in chamber 12 in which a plurality of coalescing
s plates 40 are mounted within vessel 38 at a predetermined slope (about
45 ° ) with a predetermined separation (usually about 4"). The plates
40
extend nearly the entire width of the chamber 12 and the separation device
34 is mounted with the lower portion 42 thereof being formed into a large
duct 45 which passes through bulkhead 16 into chamber 14.
io Bulkhead 16 is provided with a pair of vents 44 which equalize the
pressure in the chambers 12 and 14.
Ladder 46 provides means for inspection personnel to check the
operation of the separation device 10 and determine if pumping the
separated sediment 48 in chamber 14 is necessary.
is Chamber 14 is provided with a control box 50 just below outlet 52
wherein outlet pipe 54 is mounted.
The operation of the device is as follows: Separation device 10 is
filled with clean water to level 36 before any storm water is allowed to
enter via pipe 26.
Zo When contaminated run off water enters the inlet chamber 12 via
pipe 26, all coarse debris is captured by screen 32 and kept upstream of
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the coalescing separation device 34. Water bearing oil, sludge and grit
moves across chamber 12 to coalescer 34 where the storm water enters the
unit 34 at opening 35 and flows downwardly between coalescing plates 40
until the water reaches lower portion 42 of the separation device 34 where
s it passes through bulkhead 16 and into chamber 12.
By this time, fine particles or particles such as oil will have
agglomerated and risen to surface 36 of the water in chamber 12.
Meanwhile, particles of a coarser nature especially those having a specific
gravity greater than 1 will drop to the lower portion 42 of separation
io device 34 and be carried through bulkhead 16 by the storm water flow and
into chamber 14 where the sediment forms layer 48 on the floor of
chamber 14.
The treated water now flows across chamber 14 and into box 50 and
exits via pipe 54. The outlet to pipe 54 establishes the water surface level
is 36 of the device 10.
The advantages of the separation device of this invention will be
immediately apparent to those skilled in the art.
Unlike prior art separators where the water flows upwardly through
the coalescing plates of the separation device, the water in applicant's
ao device flows downwardly through the coalescing plates 40. In storm water
run off situations where the bulls of the contamination in the water is grit
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and sludge, the downward flow of the water undergoing treatment acts as a
catalyst in the separation of this type of contaminant.
Oil contaminant is separated in device 34 and rises to level 36 of
chamber 12 where it is held for removal when the floating layer of oil
s becomes su~cient to warrant pumping.
Meanwhile, the sediment 48 builds up in the chamber 14 where it is
held until the level is sufficient to warrant removal.
Applicant believes that it is possible to provide for the separation of
the lighter and heavier particles in a single chambered vault. However,
io applicant feels that excellent separation of the contaminants of the storm
water may be obtained using the dual chambered device described
previously. Operating and maintenance personnel will find the dual
chambered vault more convenient for pumping the separated storm water
contaminants from the dual chambers.
is While alternative structures will become readily apparent to those
skilled in the art which will provide for separation of the storm water
contaminants, applicant prefers to limit the ambit of this invention to the
scope of the following claims.
