Patent Description:
Pavements, which are also referred to as road surfaces, are paved surfaces that are intended for vehicular and foot traffic. Pavements include, for instance, roads, sidewalks, walkways, bridges, bicycle lanes, squares, plazas, parking lots, et cetera. These are generally provided on the ground, which provides the base on which such pavements are placed. Paved surfaces can for instance be surfaces that are provided with asphalt, stone tiles, concrete, rubber, or other hardened and/or durable surface materials. Generally, such materials provide a suitable, solid and durable base for transportation (e.g., walking or driving), but are less suitable for draining water (e.g., from precipitation such as rain or snow) and other waste products (e.g., dust, leaf litter, debris, et cetera). Accordingly, pavements are generally provided with drainage systems, which may include storm drains and/or drainage wells that are connected to bodies of water (such as lakes or rivers), reservoirs, and/or a sewage system. Such drainage systems can prevent flooding of pavements, and can assist in clearing the pavements of waste products. Drainage systems have to be maintained periodically to clear debris from their internal (overflow) reservoirs and to clear inlet grates and such. Furthermore, whilst drainage systems are essential for preventing flooding in populated areas, they may prevent water from reaching the soil, which would normally contribute to the water table (e.g., ground water), which may prevent soil erosion and may contribute to vegetation and crop growth, or the like.

Publication <CIT> discloses a rainwater filter device in which a storage area for filtered water is fluidly connected to a drain area for unfiltered water via an overflow edge Publication <CIT> discloses an apparatus to classify and separate turbid water and clean water as well as a filtering device which may be used together with said apparatus. A turbid rainwater flow enters the filtering device via a rainwater inlet and passes through a filter assembly comprising first, second and third filter elements which may be tubular in shape. A tilting calibrator is provided in an upper part of the second filter element and is pivotally connected to an end of a rod. The other end of the rod is pivotally connected to an upper part of the filtering device. The assembly formed by the tilting calibrator, the rod and the first, second and third filter elements is designed to adapt to the flow rate of rainwater according to its calibration. This assembly has multiple moveable components.

Publication <CIT> discloses a vortex type sewage treatment apparatus having a hopper-shape screen chamber provided inside a trough. An upper inflow pipe is connected to an upper hollow section of the trough to introduce rainwater comprising contaminants. A pollutant discharge pipe is provided at a lower hollow section of the through. A storm drain pipe communicating with a sewer for cleaned water is also provided at the upper hollow section of the through.

It is an object of the present disclosure, amongst other objects, to alleviate the aforementioned drawbacks of the drainage systems according to the state of the art.

Accordingly, the present disclosure provides a pavement drainage well for draining surface water, comprising a well housing with a surface water inlet configured to receive surface water from a paved surface, and a wastewater outlet configured to be connected to a sewer or other water body or reservoir, a filter unit located within the well housing between the surface water inlet and the wastewater outlet, the filter unit comprising a filter element forming at least part of a flow surface along which the surface water flows from the surface water inlet to the wastewater outlet, and a filtrate outlet configured to drain the filtrate collected by the filter unit from the drainage well.

By providing the filter unit between the inlet and the outlet of the drainage well, filtered water can be collected (i.e., the filtrate collected by the filter unit) which can subsequently be provided to the water table of the surrounding area, for instance via an infiltration reservoir or the like, or can be provided to agricultural processes or the like. Advantageously, the present drainage well has a low maintenance requirement because it is (a part of) the flow surface along which the surface water flows from the surface water inlet to the wastewater outlet of the well. A part of the surface water thereby cleans the exterior surface of the filter element, which makes the filter unit essentially self-cleaning. The present drainage well provides a significant amount of useful filtered water. Only a relatively small fraction of the surface water will be drained through the wastewater outlet, for instance to a sewer, together with further debris and contaminants in the water that did not pass the filter (i.e., the residue). Accordingly, the present drainage well has a positive effect on the environment by providing filtered water, and requires less maintenance as compared to drainage systems and/or associated filters according to the state of the art.

In particular, the flow surface is configured to guide the surface water from the surface water inlet to pass along and over the filter element towards the wastewater outlet. The flow surface is continuous from the surface water inlet to the wastewater outlet. The filter element forms at least part of such continuous flow surface over which the surface water flows from the surface water inlet to the wastewater outlet. The flow surface defines a continuous drainage channel from the surface water inlet to the wastewater outlet, the filter element forming at least a part of this continuous drainage channel while leaving free the continuous channel. In other words, the filter element may form a wall section of such continuous drainage channel.

The well housing may be an elongate housing, preferably rectangular, that is provided underground at a level below the paved surface. The housing is generally made of concrete, preferably reinforced concrete. The surface water inlet is provided at a location higher than the wastewater outlet, such that the transport of the surface water past the filter and to the outlet is provided by gravity. One or more storm drains can be connected to the drainage well, and/or a storm drain can be integrated with the drainage well. Preferably, the filter unit and/or the filter element are removably mounted in the well, so as to be replaceable. An access hatch, or the like, of the well housing is preferably sized to accommodate the removal of the filter unit and/or filter element. The filter element forms a channel arranged between the surface water inlet to the wastewater outlet. The channel may extend from the surface water inlet to the wastewater outlet. The channel may have a (partially or fully) cylindrical cross-section. Preferably, the channel narrows towards the wastewater outlet. The channel may have a frustoconical shape or a funnel shape. The channel has an inlet side and an outlet side, wherein the inlet side is closer to the surface water inlet than the wastewater outlet, and the outlet side is closer to the wastewater outlet than the surface water inlet. The inlet side may be flush with (part of) an interior wall of the well housing. The outlet side may be flush with (part of) the wastewater outlet.

The surface water inlet is oriented relative to the channel such that at least part of the surface water is guided to follow a substantially helical path through the channel. To that effect, the inlet may for instance direct the surface water perpendicularly to a central axis of the channel, and at a distance therefrom (i.e., in a tangential direction relative to the central axis), so as to provide the water with a swirl or rotation with respect to the channel. Accordingly, the filter element of the filter unit can function as a cyclone filter, wherein the centrifugal force acting upon the water aids in the water passing through the filter. The rotating path of the water along the filter element also increases the effective filter surface of the filter element, as the water tends to pass a large portion of the filter element.

Further preferably, the filter element comprises a filter plate with a filter mesh, preferably wherein the filter plate is made of stainless steel. Preferably, the filter mesh has a mesh size (i.e., pore size) of approximately between <NUM> to <NUM>. A more preferable mesh size is in the range of <NUM> to <NUM>, most preferably <NUM> to <NUM>. The mesh size may vary over the surface of the filter mesh, such that at one location on the filter mesh the mesh size differs from the mesh size at another location on the filter mesh.

Further preferably, the filter element comprises an adhesion plate provided behind the filter plate. A distance between the filter plate and the adhesion plate may decrease towards the surface water inlet. The adhesion plate may be perforated. Preferably, in a cross-section along the longitudinal direction of the filter element, the filter plate and the adhesion plate define an angle with respect to each other. The adhesion plate is preferably located closer to the filter plate at the inlet side of the filter element than at the outlet side of the filter element. When the water has passed through the filter plate, it tends to adhere to the adhesion plate. As the adhesion plate moves away from the filter plate towards the wastewater outlet, the water present on the adhesion plate tends to "pull" water through the filter plate due to cohesive attraction. Perforations in the adhesion plate may allow for a higher throughput.

Further preferably, the well housing is at least partially made of concrete. The concrete may be reinforced concrete. The filter unit may be mounted to the concrete material of the well housing, preferably by partially casting the filter unit, or particularly mounting brackets thereof, into the concrete material. Accordingly, a flush transition can be made between the inner wall of the well housing and the outer surface (i.e., filter surface) of the filter element of the filter unit. Alternatively or additionally, the filter unit may be cast into concrete to form the well housing around a prefabricated filter unit.

Preferably, the drainage well further comprises an overflow reservoir located between the surface water inlet and the filter unit, wherein an overflow outlet of the overflow reservoir provides the surface water to the filter unit. The overflow reservoir may be formed by a storm drain or the like, or a perforated basket placed under the inlet of the drainage well.

Further preferably, the surface water inlet is provided with an inlet cover, preferably made of metal. The inlet cover may for instance be an inlet grate or a manhole cover. The inlet cover prevents large items, persons and animals from entering the drainage well unintentionally.

Preferably, the drainage well further comprises a prefilter located between the surface water inlet and the filter unit. The prefilter may for instance be a filter grate through which the surface water passes, or a perforated basket or the like. The prefilter may be removable, for instance through an access hatch (e.g., manhole cover) to be periodically cleaned.

The present disclosure also relates to a filter unit according to the above, which is sized to be installed in existing drainage wells. Accordingly, the present disclosure provides a filter unit configured to be installed within a well housing of a drainage well, between a surface water inlet and a wastewater outlet of the well, wherein the filter unit comprises a filter element configured to form at least part of a flow surface along which surface water (taken in by the well) flows from the surface water inlet to the wastewater outlet, and wherein the filter unit is configured to be connected to a filtrate outlet that is configured to drain the filtrate collected by the filter unit from the drainage well.

According to a second aspect of the present disclosure, a pavement surface water infiltration system is provided. The system comprises a pavement drainage well according to any of the preceding embodiments, and an infiltration reservoir connected to the filtrate outlet for receiving the filtrate from the filter unit. Hence, the system making use of the drainage well of the present disclosure benefits the water table of the surrounding area without polluting it. A balanced water table (e.g., ground water level) can prevent subsidence of buildings in the vicinity, and may benefit the ecosystem, such as the vegetation in the area.

At least part of the infiltration reservoir may have an open structure. Preferably, the infiltration reservoir is lined with a porous material, such as geotextile or a mesh material or the like. Accordingly, the filtered water (i.e., the filtrate collected by the filter unit) can be provided to the surrounding soil at a controlled rate. The use of filtrate instead of direct surface runoff prevents blockage of the reservoir, such that the effective lifetime of the reservoir is significantly prolonged.

Preferably, the system further comprises a venting duct connected with the infiltration reservoir and the well housing, wherein an outlet of the venting duct at the well housing is located above the surface water inlet, such that surface water does not directly enter the venting duct.

According to a third aspect of the present disclosure, a method for providing infiltration in the vicinity of a paved surface is provided, comprising the steps of:.

Preferably, the system comprises the venting duct, and the method further comprises a step of connecting the venting duct to the infiltration reservoir and the well.

Preferably, the step of connecting the surface water inlet of the well to the paved surface comprises connecting the water inlet of the well to an existing storm drain of the paved surface.

Preferably, the paved surface is a pavement, such as a road, for pedestrian or vehicle traffic.

The step of burying the pavement drainage well may comprise burying the well under or adjacent to the paved surface.

Preferably, the step of burying the infiltration reservoir comprises burying the reservoir at a level lower than the filtrate outlet of the well.

The above method according to the third aspect, and the preferred embodiments thereof, are able to provide infiltration in environments that are in need of increased infiltration, such as urban environments and other built-up environments wherein precipitation may be prevented from sufficiently reaching the water table (e.g., seeping into the ground). For instance, in urban and built-up environments, barriers may exist that prevent the precipitation from reaching the soil beneath. These barriers are generally paved surfaces (e.g., roads, parking areas, footpaths, bicycle lanes, et cetera), or other structures (e.g., bridges, foundations, buildings, walls, et cetera). The present method thus benefits infiltration in such areas, thereby preventing damage to vegetation and buildings, and possibly the paved surface itself, due to lack of infiltration which may for instance cause subsidence or soil erosion.

The above will further be elucidated by illustrative examples according to the figures, wherein:.

The following reference numbers are used throughout:.

In <FIG>, a pavement drainage well <NUM> for draining surface water <NUM> is illustrated. The pavement drainage well <NUM> comprises a well housing <NUM> with a surface water inlet <NUM> that is configured to receive surface water <NUM> from a paved surface <NUM>, and with a wastewater outlet <NUM> that is configured to be connected to a sewer <NUM>. A filter unit <NUM> is located within the well housing <NUM> between the surface water inlet <NUM> and the wastewater outlet <NUM>. The filter unit <NUM> comprises a filter element <NUM> forming at least part of a flow surface <NUM> along which the surface water <NUM> flows from the surface water inlet <NUM> to the wastewater outlet <NUM>. The pavement drainage well <NUM> further comprises a filtrate outlet <NUM> configured to drain the filtrate <NUM> collected by the filter unit <NUM> from the well <NUM>.

An access hatch <NUM> is provided at a top surface of the well <NUM>. The access hatch <NUM> may be provided with openings <NUM> (illustrated as a grating in <FIG>), in particular when the well <NUM> is implemented as a storm drain <NUM>.

<FIG> present cross-sectional views along the arrows indicated in <FIG>.

The filter element <NUM> forms a channel <NUM> from the surface water inlet <NUM> to the wastewater outlet <NUM>. Surface water <NUM> introduced through the surface water inlet <NUM> flows over the channel <NUM> formed by the filter element <NUM> to, on the one hand, the wastewater outlet <NUM> and, on the other hand, to filtrate outlet <NUM>. The filter element <NUM> ensures separation of coarse and particulate matter (illustrated as a leaf), including contaminating substances that stick to such particulate matter, from most of the water which forms the filtrate <NUM>.

The channel <NUM> is illustrated with a cylindrical cross-section, though the channel <NUM> may have various geometric shapes connecting the surface water inlet <NUM> to the wastewater outlet <NUM>. For example, in <FIG>, the filter element <NUM> is shown as having a flat shape. Various constructions of the well <NUM> are envisioned, as long as the incoming surface water <NUM> is (at least partially) guided along (i.e., over) the surface of the filter element <NUM> towards the wastewater outlet <NUM>. The filter element <NUM> and/or the channel <NUM> it forms, defines an interface between a continuous drainage channel connecting the surface water inlet <NUM> to the wastewater outlet <NUM> and the filtrate outlet <NUM>.

The filter element <NUM> of the pavement drainage well <NUM> of <FIG> may also comprise the filter plate <NUM> having the filter mesh <NUM> and may further comprise the adhesion plate <NUM> with or without perforations <NUM>.

In <FIG>, it can be seen that the channel <NUM> narrows towards the wastewater outlet <NUM>. The surface water inlet <NUM> is oriented relative to the channel <NUM> such that at least part of the surface water <NUM> follows a substantially helical path <NUM> through the channel <NUM>. A helical path <NUM> is also illustrated in the well <NUM> of <FIG>. The helical path <NUM> may be initiated by the form of the surface water inlet <NUM>. For example, the surface water inlet <NUM> may be configured to direct incoming surface water <NUM> along a tangential path, e.g. relative to a vertical direction of the channel <NUM> in the well <NUM>.

The filter element <NUM> comprises a filter plate <NUM> with a filter mesh <NUM>. The filter plate is <NUM> can be made of stainless steel.

The filter element <NUM> also comprises an adhesion plate <NUM> provided behind the filter plate <NUM>. The adhesion plate <NUM> is arranged behind the filter plate <NUM> as seen relative to the flow direction of filtrate originating from the surface water <NUM> through the filter element <NUM>. A distance <NUM> between the filter plate <NUM> and the adhesion plate <NUM> decreases towards the surface water inlet <NUM>. The adhesion plate <NUM> is illustrated with perforations <NUM> which serve to increase filtrate <NUM> throughput.

<FIG> illustrate the working principle of the filter element <NUM> comprising the filter plate <NUM> with its filter mesh <NUM> and an adhesion plate <NUM>. Due to forces of adhesion (related to wetting), water is attracted to the surface of the filter mesh <NUM> and thereby passes through the filter mesh <NUM> and may reach the adhesion plate <NUM> arranged behind the filter mesh <NUM>. Due to forces of cohesion (related to surface tension), more water is drawn towards the adhesion plate <NUM>. As the water falls down due to gravity, an increased separation distance <NUM> between the filter plate <NUM> and the adhesion plate <NUM> can accommodate increasing amounts of filtrate <NUM>. The perforations <NUM> in the adhesion plate <NUM> may further increase the capacity of the filter element <NUM> to withdraw filtrate or water <NUM> from the surface water <NUM> passing along the filter element <NUM>.

<FIG> and <FIG> illustrate a pavement drainage well <NUM> with integrated storm drain <NUM>. A storm drain <NUM> generally comprises an overflow reservoir <NUM>, which allows particular matter or other debris to settle. The overflow reservoir <NUM> may thus perform the function of a prefilter <NUM>. The illustrated well <NUM> comprises an overflow reservoir <NUM> arranged between the surface water inlet <NUM> and the filter unit <NUM>. An overflow outlet <NUM> of the overflow reservoir <NUM> provides the surface water <NUM> to the filter unit <NUM>. The overflow reservoir <NUM> is illustrated as a bucket with openings forming overflow outlets <NUM>. In an alternative embodiment (not illustrated), the bucket or overflow reservoir <NUM> can be made of a perforated sheet material, such as stainless steel, to perform a prefilter function.

The overflow reservoir or bucket <NUM> is provided with a handle <NUM> for easy removal from the well <NUM> for emptying of the overflow reservoir <NUM> and other maintenance.

The storm drain of <FIG> is provided with an inlet cover <NUM> in form of hatched inlet grate. Inlet covers or access hatches <NUM> are preferably made of metal such as cast iron. When the inlet cover or hatch <NUM> is opened, settled debris can be cleared from the overflow reservoir <NUM>. Further, the overflow reservoir <NUM> may be removable arranged onto the filter unit <NUM>, for example as illustrated.

The filter unit <NUM> and/or the filter element <NUM> of the well <NUM> of <FIG> may correspond to those of the well <NUM> of <FIG>.

In the illustrated embodiments, the well housing <NUM> is at least partially made of concrete. The filter unit <NUM> is mounted to the concrete of the well housing <NUM>, preferably by partially casting the filter unit <NUM> into the concrete. As is particularly clear from <FIG> and <FIG>, the filter unit <NUM> may be arranged or cast into the concrete well housing <NUM>, with an access hatch or inlet cover <NUM> arranged at the top. Prior to casting, the filter unit <NUM> may be modularly assembled.

As particularly clear from <FIG>, the filter element <NUM> may be removably arranged in the well <NUM>. For example by being supported onto the surface water inlet <NUM> and/or the wastewater outlet <NUM>. When the hatch <NUM> is opened, the filter element <NUM> can be removed, serviced, or replaced.

<FIG> illustrates how the pavement drainage well <NUM> can be employed in a pavement surface water infiltration system <NUM>. The pavement surface water infiltration system <NUM> comprises the pavement drainage well <NUM> according to the present disclosure as well as an infiltration reservoir <NUM> connected to the filtrate outlet <NUM> for receiving the filtrate <NUM> from the filter unit <NUM> of the well <NUM>.

At least part of the infiltration reservoir <NUM> has an open structure <NUM> from which water can infiltrate surrounding soil <NUM>. The infiltration reservoir <NUM> can be lined with a porous material <NUM>, such as geotextile.

The system <NUM> further comprises a venting duct <NUM> connected with the infiltration reservoir <NUM>, for example with a top surface thereof, and the well housing <NUM>. An outlet <NUM> of the venting duct at the well housing <NUM> is located above the surface water inlet <NUM>.

The system <NUM> shown in <FIG> provides infiltration in the vicinity of paved surface <NUM>. Surface water <NUM> is drained from the paved surface <NUM> into storm drains <NUM>, which lead to the surface water inlet <NUM> of a pavement drainage well <NUM>. The surface water <NUM> is filtered in the pavement drainage well <NUM> as it is guided through the filter unit <NUM>, in particular through the filter element <NUM> which separates the incoming surface water <NUM> into filtrate <NUM> and wastewater <NUM>. The filtrate <NUM> is guided to the infiltration reservoir <NUM> via the filtrate outlet <NUM>, while the wastewater <NUM> is guided to a sewer <NUM> via the wastewater outlet <NUM>.

Claim 1:
Pavement drainage well (<NUM>) for draining surface water, comprising:
a well housing (<NUM>) comprising a surface water inlet (<NUM>) configured to receive surface water from a paved surface (<NUM>), and a wastewater outlet (<NUM>) configured to be connected to a sewer (<NUM>);
a filter unit (<NUM>) located within the well housing (<NUM>) between the surface water inlet (<NUM>) and the wastewater outlet (<NUM>), the filter unit (<NUM>) comprising a filter element (<NUM>) forming a channel (<NUM>) that is at least part of a continuous flow surface (<NUM>) along which the surface water is configured to flow from the surface water inlet (<NUM>) to pass along and over the filter element (<NUM>) towards the wastewater outlet (<NUM>), wherein the flow surface (<NUM>) defines a continuous drainage channel connecting the surface water inlet (<NUM>) to the wastewater outlet (<NUM>); and
a filtrate outlet (<NUM>) configured to drain the filtrate collected by the filter unit (<NUM>) from the pavement drainage well (<NUM>),
wherein the filter element (<NUM>) and/or the channel (<NUM>) formed by the filter element (<NUM>) defines an interface between the continuous drainage channel and the filtrate outlet (<NUM>), and the surface water inlet (<NUM>) is oriented relative to the channel (<NUM>) formed by the filter element (<NUM>) such that at least part of the surface water follows a substantially helical path (<NUM>) through the channel (<NUM>).