Dome interface and manhole system with the dome interface

Abstract

A system and method for draining water is provided. The invention achieves its objectives by a dome interface (200) between gravity (214, 224) and siphonic (212, 222) drainage circuits of a drainage system (100) for a fluid, a manhole system (200) comprising a dome interface, a drainage system comprising at least one manhole, wherein the least one manhole comprises a dome interface, and a method for adjusting a valve (340).

Description

[0001] TITLE: DOME INTERFACE

[0002] Background of the Invention

[0003] Field of the Invention

[0004] The invention relates to drainage in general and more specifically a system and a method for draining water, in particular surface water and sewer water.

[0005] Background Art

[0006] State of the art is reflected in drainage systems, such as municipal drainage systems, that transport waste waters from buildings and drains into a drainage system that leads to a recipient, typically a treatment plant or a pipe leading out at sea. Drainage systems are typically buried underground and has not been updated while the cities have grown in size. This has over time caused a growing capacity problem, leading in turn to flooded streets and basements. Heavy rainfalls puts the drainage systems under stress, and there is a growing risk of downstream flooding. When the drainage system reaches the limit of drainage during heavy rainfalls, the water is not drained away from the surface and may cause accidents for instance due to aquaplaning on roads. Another problem is related to backflow of water, as the water may flow back through the pipes and out of another gutter, creating a flood. This is especially undesirable if drainage from buildings are connected to the same system, as large water damage may occur to the building.

[0007] In a traditional drainage system for use in surface water, fluid from inlets is collected and guided in branch pipes and main pipes, typically via one or more manholes and collection tanks to a recipient, possibly including a water processing plant. The flow is based upon water flowing by its own weight, and is called "gravity flow" or "gravity drainage". Manholes, pipes and manifolds are open and allow air to be let into the drainage system and thereby the amount of liquid that the system can handle is limited. WO 2014 / 209133 discloses a system whereby the "gravity flow" is replaced by a "full current flow" wherein no gas is flowing together with the water. "Full current flow" is also known as "siphonic drainage" or "siphonic flow" in prior art. WO 2019 / 226055 discloses a system for drainage of surface water, the system comprises a number of tanks being connected to a main pipeline leading water to a recipient. Each tank has at least one outlet for leading water from the tank to the main pipeline, and a corresponding lid, the lid is limiting the outlet until the water is at a predetermined level in the tank. The system further comprises a check valve arranged downstream of the outlet of each tank, preventing water from entering the tank from the main pipeline, and at least one air bleeder valve and at least one siphonic drainage regulator arranged between a tank and the recipient.

[0008] These traditional systems are complex and parts such as check valves are subject to wear and require servicing.

[0009] WO2019226055A1 discloses, according to its abstract, a system for drainage of surface water, the system comprises a number of tanks being connected to a main pipeline leading water to a recipient.

[0010] CN217460811 U discloses, according to a translation of its abstract, a drainage device, and belongs to the technical field of drainage. Aiming at the back-overflow phenomenon in the existing drainage device, especially the back-overflow problem caused by the sudden increase of air pressure in a water outlet, the utility model provides the drainage device which comprises a container, an inner cover and an inner cylinder, a movable plate is arranged in the inner cylinder, the opening and closing of the inner cylinder can be controlled according to the pressure, the back- overflow of sewage and foul gas can be effectively prevented, and the safety of the drainage device is improved.

[0011] WO2017151 150A1 discloses, according to its abstract, a no overflow, siphonic overflow device for the prevention of water overflowing a vessel during an unattended filling operation through the use of a siphonic overflow device in place of the existing conventional overflow drain pipe connected to the conventional waste water pipe of a bathtub.

[0012] W020140131A1 discloses, according to its abstract, a drainpipe structure using an improved manhole, comprising: an improved manhole including a lower manhole and an upper improved manhole arranged on the lower manhole; a lower conduit connected to the lower manhole; and an upper conduit arranged above the lower conduit and connected to the upper improved manhole.

[0013] There is therefore a need for a method and a system to overcome the above- mentioned problems. Summary of the Invention

[0014] Problems to be Solved by the Invention

[0015] Therefore, a main objective of the present invention is to provide a system and method for draining water.

[0016] Means for Solving the Problems

[0017] The objective is achieved according to the invention by dome interface as defined in the preamble of claim 1 , having the features of the characterising portion of claim 1 , a manhole system as defined in the preamble of claim 9, having the features of the characterising portion of claim 9, an auxiliary drainage system as defined in the preamble of claim 13, having the features of the characterising portion of claim 13, a stormwater manhole as defined in the preamble of claim 15, having the features of the characterising portion of claim 15, a drainage system as defined in the preamble of claim 19, having the features of the characterising portion of claim 19, a method for starting operation of an auxiliary drainage system as defined in the preamble of claim 23, having the features of the characterising portion of claim

[0018] 23, a method for ending operation of an auxiliary drainage system as defined in the preamble of claim 24, having the features of the characterising portion of claim

[0019] 24, a method for adjusting a valve as defined in the preamble of claim 25, having the features of the characterising portion of claim 25.

[0020] A number of non-exhaustive embodiments, variants or alternatives of the invention are defined by the dependent claims.

[0021] In a first aspect of the invention, a dome interface between gravity and siphonic drainage circuits of a drainage system for a fluid is provided, wherein the dome interface comprises: a surface for receiving water from a gravity drainage circuit, a dome having an upper closed end and a lower open end, wherein the lower open end is provided above the surface, separated by a gap to allow fluid from the gravity circuit to flow through the gap and into an interior of the dome, a pipe having an upper and a lower end, wherein the upper end is located inside the dome above the gap, and the lower end is connected to the siphonic drainage circuit. The effect of this is that one can ensure siphonic flow from a gravity flow source while reducing the amount of air ingested into the siphonic flow, thus increasing the efficiency.

[0022] In one embodiment, the upper end of the pipe defines an area that is smaller than an area defined by the gap. The effect of this is that this further improves exclusion of air from entering the siphonic flow.

[0023] In one embodiment, the dome interface further comprises a valve for throttling the upper end of the pipe. This makes it possible to adjust the flow rate through a dome interface, which is useful when several manholes are connected in series, each having a dome interface.

[0024] In one embodiment, the surface is further provided with at least one means from the group comprising means for slowing down the water, means for reducing turbulence, means for coalescing bubbles and means for centrifugal separation, for improved air separation from the water. This improves the siphonic flow rate.

[0025] In one embodiment, the gap is provided with means for closing when the water is at a first lower level, and means for opening when the water is at a second upper level. This further improves reduction of air ingested into the siphonic flow.

[0026] In one embodiment, the dome is provided with valve that open in a direction perpendicular to a flow direction of water through the valve. The technical effect of this is that forces due to the flow will not act on the valve so as to close the valve.

[0027] In one embodiment, the dome interface further comprises means for lowering a pressure inside the dome temporarily during opening of at least one of the gap and the valve. This reduces the pressure acting on valve parts until the valve has been opened, and is especially beneficial for valves where the forces due to the flow act on the valve along the direction of opening.

[0028] In one embodiment, the means for lowering a pressure inside the dome is a valve admitting air inside the dome.

[0029] In a second aspect of the invention, a manhole system is provided, comprising a dome interface, wherein the manhole system further comprises: an attachment with an inlet pipe assembly to a upstream drainage, wherein the inlet pipe assembly comprises an inlet pipe for siphonic drainage surrounded by an inlet pipe for gravity drainage, and an attachment with an outlet pipe assembly to a downstream drainage, wherein the outlet pipe assembly comprises an outlet pipe for siphonic drainage surrounded by an outlet pipe for gravity drainage, wherein the inlet pipe for siphonic drainage is connected to the outlet pipe for siphonic drainage, forming part of a siphonic drainage system, which is connected to the pipe of the dome interface, the inlet pipe for gravity drainage is connected to the surface for receiving water, and the outlet pipe for gravity drainage is blocked inside the manhole with a block, to ensure all water from the inlet pipe for gravity reaches the surface for receiving water.

[0030] The effect of this is that new or existing manholes can be upgraded for more efficient siphonic flow.

[0031] In one embodiment, the manhole system further comprises a raised threshold at least partially surrounding the surface for receiving water to ensure a minimum water level inside the manhole before water flows to the surface for receiving water. This ensures a minimum water level, thus reducing exclusion of air from entering the siphonic flow.

[0032] In one embodiment, the manhole system further comprises an overflow path for excessive water inside the manhole to overflow into the outlet pipe for gravity drainage. This provides added safety in case there should be a problem with the siphonic drainage system.

[0033] In one embodiment, the manhole system further comprises a raised part provided inside the inlet pipe for gravity drainage, for directing water to the surface. This provides further efficiency in transferring water to the surface and then to the dome interface. This raised part can be formed as a saddle for convenient and stable positioning on and at least partially around a siphonic pipe for simplified retrofit in existing manholes.

[0034] In a third aspect of the invention, a drainage system is provided, comprising at least one manhole, wherein the least one manhole comprises a dome interface. In one embodiment, the drainage system further comprises a valve provided on a siphonic drainage circuit, to prevent implosion by admitting air when the under pressure exceed a threshold.

[0035] In a fourth aspect of the invention, an auxiliary drainage system is provided, comprising an auxiliary drainage pipe having an upper and a lower end, wherein the auxiliary drainage pipe is provided with an upper valve at the upper end and a lower valve and the lower end, wherein the lower valve is positioned near a recipient, preferably as a gooseneck, wherein the auxiliary drainage system further comprises at least one auxiliary drainage branch pipeline comprising a proximal end fluidically connected to the auxiliary drainage pipe, and a distal end connected to a siphonic drainage pipe of a respective manhole system via a check valve, wherein the auxiliary drainage system, when filled with water, operate as a siphonic system, and extract water from the siphonic or gravity drainage pipe, thus providing added capacity.

[0036] The technical effect of this is to provide added capacities such as in emergencies, and the means for use of such systems.

[0037] In a fifth aspect of the invention, a method for starting operation of an auxiliary drainage system, comprising the steps: a closing the lower valve and opening the upper valve; b fill the auxiliary drainage pipe with water from a manhole system near the upper end of the auxiliary drainage pipe; and c when the auxiliary drainage pipe is substantially filled with water, closing the upper valve and opening the lower valve.

[0038] The technical effect is that the system quickly enters siphonic flow.

[0039] In a sixth aspect of the invention, a method for ending operation of an auxiliary drainage system according to claim 15, comprising the steps: a closing the lower valve.

[0040] The technical effect is that the system is closed controllably and can quickly re-enter siphonic flow.

[0041] In a seventh aspect of the invention, a method for adjusting a valve for throttling an upper end of a pipe, in a drainage system comprising at least two manholes, wherein the least one manhole comprises a dome interface, comprising the steps: a) start with all valves in the manholes in an open position, b) starting at a second to lowermost manhole as a present manhole for adjustment, c) throttle a respective valve until a manhole below the present manhole reaches a sufficient capacity for drainage, and d) progress to a manhole upstream of the present manhole as the new present manhole for adjustment.

[0042] The technical effect is that the system comprising a plurality of manholes can be tuned for efficient flow when upstream manholes provide siphonic flow.

[0043] The present invention attains the above-described objective by a dome interface between gravity and siphonic drainage circuits of a drainage system.

[0044] Effects of the Invention

[0045] The present invention comprises a technological advantage over known systems and methods by use of a dome interface, that provides an interface between gravity and siphonic drainage systems.

[0046] The present invention provides several further advantageous effects: it makes it possible to connect the gravity drainage system into the siphonic drainage system with few or no moving parts, it is efficient in reducing or avoiding air ingestion into the siphonic drainage system, letting it operate efficiently, it avoids complexities and moving parts such as check valves, if necessary, it is easy to adjust using a throttling valve, it reduces or in cases also avoids hydraulic hammers, and instead achieves smooth self regulation.

[0047] Brief Description of the Drawings

[0048] The above and further features of the invention are set forth with particularity in the appended claims and together with advantages thereof will become clearer from consideration of the following detailed description of an [exemplary] embodiment of the invention given with reference to the accompanying drawings.

[0049] The invention will be further described below in connection with exemplary embodiments which are schematically shown in the drawings, wherein: Fig. 1A shows a typical drainage system, wherein manholes can be upgraded with a system according to an embodiment of the invention,

[0050] Fig. 1 B shows an embodiment wherein gravity drainage is augmented with siphonic drainage by adding a pipe inside existing pipes, Fig. 2A shows a cross section of a dome interface,

[0051] Fig. 2B shows a variant of the dome interface of Fig. 2A,

[0052] Fig. 3 shows a cross section of a manhole provided with a dome interface,

[0053] Fig. 4 shows an auxiliary drainage system,

[0054] Fig. 5A shows an embodiment of a stormwater manhole system, and Fig. 5B shows an alternative embodiment of a stormwater manhole system.

[0055] Description of the Reference Signs

[0056] The following reference numbers and signs refer to the drawings:

[0057] Detailed Description of the Invention

[0058] Various aspects of the disclosure are described more fully hereinafter with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.

[0059] The invention will be further described in connection with exemplary embodiments which are schematically shown in the drawings, wherein Fig. 1A shows a typical drainage system 100, wherein manholes 200 can be upgraded with a system according to an embodiment of the invention. Manholes 200 collect water from sources 102 via branch pipelines 103 and upstream manholes, and lead the collected water downstream, possibly via further manholes down to a recipient 104. A manhole is connected to upstream manholes via upstream drainage pipes 110, and downstream manholes via downstream drainage pipes 120.

[0060] Fig. 1 B shows an embodiment wherein gravity drainage is augmented with siphonic drainage by adding a pipe inside existing pipes, so that the upstream drainage pipe 110 comprises an upstream pipe 112 for siphonic drainage inserted inside an upstream pipe 114 for gravity drainage and / or the downstream drainage pipe 120 comprises an downstream pipe 122 for siphonic drainage inserted inside an downstream pipe 124 for gravity drainage.

[0061] The present invention builds upon the existing infrastructure by adding further functionality into manholes.

[0062] Principles forming the basis of the invention

[0063] The inventor has recognised that drainage systems that also comprise siphonic drainage, the interface between gravity and siphonic drainage systems can be the cause of excessive air being ingested into the siphonic drainage parts and thus cause the siphonic drainage to switch into gravity drainage. This leads to reduction in capacity and can be undesirable.

[0064] The inventor has found that a structure comprising a raised pipe covered by a dome or a bell jar, will provide an improved interface between gravity and siphonic drainage circuits on a drainage system.

[0065] Fig. 2A shows a cross section of a dome interface 300, which comprises a surface 310 for receiving water from a gravity circuit 114, 224, and a dome 320 having an upper closed end 322 and a lower open end 324, wherein the lower open end is provided above the surface, separated by a gap 326 to allow fluid from the gravity circuit 124 to flow through the gap 326 and into an interior of the dome 320, a pipe 330 having an upper 322 and a lower 324 end, wherein the upper end is located inside the dome above the gap, and the lower end is connected to the drainage circuit.

[0066] The surface 300 is shown as flat but could have any shape as long as it allows water to flow over the surface and past the gap 326 and into the dome 320. The surface 300 is also important in defining a lower part of the gap. In embodiments, the surface also plays a role in further reducing air ingestion. Water flow admitted into the manhole through the gravity circuit can contain air and bubbles. By letting this flow cross the surface before reaching the gap, the calmer flow will let air and bubbles escape the water before the water reaches the gap. A surface that is wide and / or smooth compared to the inlet pipes will improve the air water-separation. In embodiments, the surface can be provided with further features such as baffles and spirals to further improve air separation from the water, such as by further calming or slowing down the water, reducing turbulence, coalescing bubbles or centrifugal separation.

[0067] The gap 326 is provided at a lower part of the dome interface. This is preferred in order to reduce air ingestion. Air bubbles will naturally escape upwards, especially large bubbles with large buoyancy, and thus escape the gap. Finely dispersed small bubbles will take longer time to ascend, then again these represent an equally tiny air volume and will therefore have no practical impact on siphonic drainage flow.

[0068] The dome 320 is shown as having a domed upper closed end 322 and a lower open end 324. The dome shape is convenient, but the technical effect will still be present with, say, a flat upper end. The term dome in this context should be understood as any structure with a closed upper end that will admit a pipe. The open end 324 defines the upper part of the gap 326. The dome is positioned above the surface 310 so to define the gap 326. It may be fixed to the surface using legs or separators, or fixed to the pipe 330 or to any other parts of the manhole by means that is within the skill of a person skilled in the art. The drawings show the gap extending around the entire 360°, which will be efficient in admitting as much water as possible across the gap. Nevertheless, it is within the scope of the invention to have a gap that is interrupted in parts, such as support or attachment structures.

[0069] The pipe 330 comprises an upper 322 and a lower 324 end. The upper end 322 of the pipe 330 extends to a position inside the upper closed end 322 of the dome 330. The raised position is a position above the upper part of the gap, and together with the rest of the dome interface, ensures that the dome interface reduces or entirely avoids air ingestion into the siphonic circuit. Thus, the dome interface is an interface between the gravity circuit that is open to air, and the siphonic circuit where air should be avoided. The lower end 324 of the pipe 320 is connected to the siphonic drainage circuit. In the drawings, the pipe is shown as crossing the surface 310 and connecting to the siphonic circuit below the surface. It is fully within the scope of the invention to use different geometries, such as the pipe turning sideways and connecting to the siphonic drain circuit provided aside instead of below.

[0070] In use, the water flows onto the surface and the water level is raised until the water level submerges the gap and then the upper end of the pipe. At that point, experiments show that siphonic flow starts, and sucks water from the surface past the gap and into the siphonic drainage circuit. To maintain the siphonic flow, it is desirable to balance the area of the gap with the effective area of the pipe. Experiments have shown that it is preferable in a system with multiple dome interfaces that the effective area of the pipe should be smaller than the area of the gap, and to adjust these to the typical water flow into the inlet to the surface, the upper end of the pipe of the dome interface can be provided with a throttling valve. That way, the gap can be sized for future growth in flooding, while the adaption to current conditions can be adapted with the throttling valve. Typically, the valve is adjusted less frequently than annually.

[0071] To adjust the throttling valves of a system with more than one manhole system 200, one starts with the vales in a fully open position. During rainfall, if one manhole system is unable to drain sufficient amounts of water, the valve immediately upstream of said manhole is throttled until the manhole is again able to drain sufficient amounts of water to keep up with the rainfall.

[0072] Fig. 3 shows a cross section of a manhole system 200 provided with a dome interface 300, wherein the dome interface is the embodiment shown in Fig. 2A. The manhole system 200 further comprises an attachment 210 with an inlet pipe assembly to a upstream drainage 110, wherein the inlet pipe assembly comprises an inlet pipe 212 for siphonic drainage surrounded by an inlet pipe 214 for gravity drainage, and an attachment 220 with an outlet pipe assembly to a downstream drainage 120, wherein the outlet pipe assembly comprises an outlet pipe 222 for siphonic drainage surrounded by an outlet pipe 224 for gravity drainage, wherein the inlet pipe 212 for siphonic drainage is connected to the outlet pipe 222 for siphonic drainage, forming part of a siphonic drainage system, which is connected to the pipe 320 of the dome interface 300, the inlet pipe 214 for gravity drainage is connected to the surface 310 for receiving water, and the outlet pipe 224 for gravity drainage is blocked inside the manhole with a block 223, to ensure all water from the inlet pipe for gravity reaches the surface 300 for receiving water. The outlet pipe for siphonic drainage is provided with a block 223, ensuring no direct flow from the inlet pipe 214 for gravity drainage into the outlet pipe 224 for gravity drainage. The block can be provided as part of the manhole outlet assembly 220.

[0073] In order to further limit the air ingestion into the siphonic drainage system, the inventor has realised that the manhole system can be provided with a raised threshold 230 that provides a threshold before the water reaches the surface 310. The upper end 232 of the raised threshold 230 defines a water level 234 inside raised threshold, indicated by a short line. The threshold can surround the surface or be provided on the side between the inlet pipe for gravity drainage 214 and the surface 310. This also provides a water retention effect and delays water drainage. This delay means any rainwater will have time to pick up the rate of flow before starting the siphonic flow at a more optimum flow rate.

[0074] In case of blockage, damage or other problems, it is desirable to provide the manhole with a second means for draining water. An overflow path 240 is formed by an overflow threshold 242, which is raised to a position above the raised threshold 230. Fig. 3 shows a situation where the water level 204 inside manhole 200 has exceeded the overflow threshold 242, and water flows along a an overflow path 244 and into the outlet pipe for gravity drainage 244 and then the downstream pipe for gravity drainage 124. In preferred embodiments, the block 233 is provided upstream from the overflow path, for a more compact solution.

[0075] It has been realised that it is advantageous to provide the manhole inlet assembly 210 with a raised part 216 in order to more efficiently direct the water coming through the inlet pipe 214 for gravity drainage and to the surface 310. In embodiments, this raised part is provided like a saddle over the inlet pipe 212 for siphonic drainage. The block 223 can be attached to the raised part 216, and can also be part of it as a single combined unit.

[0076] In practice, water in the upstream gravity drainage pipe is led into the siphonic drainage pipe by use of the dome interface. The upstream siphonic drainage pipe continues substantially unbroken into the siphonic drainage pipe, but is joined by the siphonic output from the dome interface. Typically, the upstream siphonic drainage pipe comes from an upstream manhole system, whereas the upstream gravity drainage pipe is fed by sources 102 via branch lines 103 below the upstream manhole system. Drainage systems 100 may have a siphonic system already installed, operating as disclosed by prior art. If not, the siphonic pipes can easily be installed inside the existing pipe networks, thus separating the siphonic and the gravity flows. To install a manhole system 200 according to an embodiment of the invention into an existing manhole, the manhole inlet assembly 210 is connected to the upstream drainage 110, and the manhole outlet assembly 220 is connected to the downstream drainage 120.

[0077] In a variation of the dome interface 200 disclosed earlier, the gap 326 is adjustable and opens only when there is sufficient water to start the siphonic flow. The determination of sufficiency can be by for instance flow rate or by water level. The dome interface 200 is then provided with means for closing the gap 326 when the water is at a first lower level, and means for opening the gap 326 when the water is at a second upper level. Typically, the first lower level is a level above a threshold where air is drawn into the siphonic drainage system.

[0078] In a system where the gap opens by raising the dome, there is a risk that the pressure will force the dome down, thus closing the gap, especially in the period before the gap is fully open. There are several ways round this problem, such as lowering the pressure difference between the inside and the outside of the dome.

[0079] One solution is to use a valve 328 where the closing member, such as a plate, is moved substantially perpendicular to the force, so that the force due to the pressure difference is not a force that acts on the closing member to close the gap.

[0080] Fig. 2B shows one such embodiment where the valve 328 uses a closing member slidably positioned against an opening provided on the surface of the dome. In a first closed position, the closing member is positioned so that it closes against the opening, and is opened by sliding the closing member along the surface of the dome, until the opening is uncovered. Once the opening is uncovered, the pressure difference decreases, and it becomes easier to open the gap and also keep the gap in an open position.

[0081] In a further improvement, the low pressure inside the dome is temporarily relieved by admitting air into the inside of the dome. Once the conditions for opening the flow of water into the dome has been established, typically by a dome pressure control system 350, a valve 352 admits air to the inside of the dome, and the gap is opened and / or the closing member is brought into the open position, and the air admittance is stopped. Tests show that the amount of air sucked into the siphonic drainage system is so small that the siphonic flow is not interrupted. The combination with the opening of the closing member is also beneficial in that it further lowers the pressure difference between the inside and the outside of the dome, further improving the process of opening the gap without the risk of unintended closing.

[0082] It has been found that the system disclosed herein is able to create a sufficient under pressure that can be used to drain overflowing manholes during flooding.

[0083] Fig. 4 shows an auxiliary drainage system 140 comprising an auxiliary drainage pipe 152 having at each end an upper valve 154 and a lower valve 156, wherein the lower valve 156 is positioned near the recipient 104, wherein the auxiliary drainage system further comprises at least one auxiliary drainage branch pipeline 162. The auxiliary drainage system is adapted for deployment on the ground, such as along a road. Each auxiliary branch pipeline 162 comprises a proximal end fluidically connected to the auxiliary drainage pipe 152, and a distal end connected to the siphonic drainage pipe 212, 222 of a respective manhole as shown in Fig. 3 via a check valve 164.

[0084] The term “near recipient” in this context means in a position that ensures the water is directed to the recipient while also low enough with respect to the opposite proximal end that the difference in height will ensure flow.

[0085] The auxiliary drainage system is adapted for deployment on the ground, such as along a road. This means the water level in the siphonic drainage pipe 212, 222 should not be more than about 10 m below the auxiliary drainage pipe 152 so that the under pressure in the auxiliary drainage pipe 152 should be able to raise the water from the siphonic drainage pipe and into the auxiliary drainage pipe.

[0086] In use, the lower valve 156 of the auxiliary drainage pipe is closed, and the pipe is filled with water from the first manhole. The check valves 164 prevent water from flowing into the siphonic drainage pipes. When the pipe has been filled with water, the lower valve 156 of the auxiliary drainage pipe is opened, and the upper valve 154 is closed. At this point, the auxiliary drainage system will operate as a siphonic system, and will extract water from the siphonic drainage pipes, thus providing added capacity. Preferably the auxiliary drainage system outlet is provided with a gooseneck 157 outlet, preferably submerged below the water level of the recipient. This ensures water remains in the gooseneck, acting as a water lock.

[0087] When the inflow of water into the system ends, it is desirable to keep the pipe full. Preferably, when the inflow ends, the lower valve 156 of the auxiliary drainage pipe is closed, thus keeping the pipe filled with water, ready for a rapid start when water again starts flowing in. During rapid start, only a little water might be needed to fill the pipe, or if sufficiently full, the lower valve 156 of the auxiliary drainage pipe is opened, and the upper valve 154 is closed, starting the siphonic flow.

[0088] The auxiliary drainage system will in parts be subjected to a strong under pressure. It is strongly desirable that the system is dimensioned for this, possibly protected by valves, to avoid implosion and damages.

[0089] Figs. 5A and 5B show other embodiments of a manhole suitable for stormwater and sewage, hereafter called stormwater manhole. The stormwater manhole 400 comprises an inlet assembly 420, a collection chamber 410, a first outlet assembly 430, with a water lock mechanism 434, an outlet accumulator or retention chamber 436, and swan neck pipe 440, and a second outlet assembly or final outlet 450 with means to prevent air from returning to the pipe 454, 456, 458.

[0090] Inlet assembly

[0091] The inlet assembly 420 comprises a wide upper pipe 422 to allow air to escape. In the instances where this is directly connected to houses, an air bleeder (not shown) can be used to let the air in and to avoid sucking out the water into the water locks in the houses. A hatch (not shown) can also be fitted to the pipe, just above the narrowing of the pipe. This will make it easy to remove any inorganic waste that are too large to pass through the lower part of the pipe.

[0092] The upper wide inlet pipe 422 transitions via a constriction 424 into a lower narrower pipe 426.

[0093] If the narrow section of the pipe 426 were to become blocked, it could trigger an alarm that would alert and activate a shut-off valve on the main water line inside the house. This would prevent more water from filling the blocked outlet. The lower part is narrow and normally the same size as the outlet pipe and leads into a collection chamber 410. This helps start siphonic flow by reducing air resistance and promotes continuous water flow.

[0094] Collection Chamber

[0095] The collection chamber 410 connects to the lower narrow part of the inlet assembly 420. It has an air valve 412 at the top to control air entry to maintain pressure balance and avoiding vacuum conditions that will drain water out completely or cause the system to implode due to the under pressure. To start a full-flow drainage whenever desired, a compressor can be connected to press air into the collection chamber for a sufficient time to fill the outlet pipe enough to start a full flow.

[0096] First Outlet Assembly

[0097] The outlet from the collection chamber forms a first outlet assembly 430 that comprises a water lock, like a ll-bend 434. This acts as a seal to prevent air from traveling forward from the collection chamber 410 into the pipe. When the collection chamber empties water, air comes in from inlet assembly 420, and the pressure in the collection chamber is approx. 1 bar, the standard atmospheric pressure. The outlet pipe’s diameter should preferably be the same as the diameter of the inlet pipe (lower part) to increase the speed of water flowing through the entire system.

[0098] Retention Chamber

[0099] Placed after the first outlet, a retention chamber 436 is placed below the collection chamber. It collects or accumulates water during flow and returns sufficient water to the water lock when the flow has ended, thus maintaining a water seal. In the figure shown, the retention chamber is places so low that it effectively forms part of the ll- bend and some water is shown extending into the retention chamber.

[0100] Swan Neck

[0101] The swan neck 440 pipe is fed from the retention chamber 436 and is positioned so that it is provided with a threshold level 442 that is just above the inlet in the manhole to ensure that the air does not siphon back to the system and the negative pressure within the system is maintained.

[0102] In a variation on the swan neck pipe’s positioning, when an additional inlet pipe 428 is connected to the collection chamber 410, the swan neck 440 pipe is placed above this additional inlet. The swan neck 440 pipe is placed higher than the highest inlet pipe.

[0103] Second Outlet Assembly

[0104] Placed after the swan neck pipe, a second outlet assembly 450 or final outlet is provided at a depth lower than the first outlet 432 and the ll-bend 434. It keeps outside air from entering the system while releasing the water into a recipient or treatment facility. The outlet is needed to prevent outside air from entering the system 400. Such means 454 may be, for example, a second outlet ll-bend 454, check-valve, motor-valve 458, sub-surface. This is important because both the inlet and the outlet to the pipe must be blocked so that a negative pressure is maintained within the swan neck pipe. However, the diameter of the last part of the outlet can be increased, which will lower the outlet speed and avoid a lot of splashing, if desired. The end recipient is normally directly led into a bell valve but may be anything that has the capacity to accommodate the amount of water from the system in a stream, river, large culvert, tunnel and the like.

[0105] This forms a full-flow system because the pipe is always in siphonic mode. This is a major advantage — it doesn’t need to switch between gravity and full-flow drainage. The pressure stays lower than atmospheric, allowing consistent high-capacity drainage without interruption.

[0106] Fig. 5B shows a variation of the stormwater manhole shown in Fig. 5A, wherein the upper part may, in addition to the hatch and air bleeder at the top, have an additional narrow pipe at the bottom to allow for smaller volume of water to drain into the collection chamber. This figure shows 3 inlets terminated at different heights. It may be an advantage if these terminate at the same height.

[0107] The stormwater manhole may also comprise an auxiliary inlet pipe 427 - placed much higher than original inlet - to allow for smaller volume of water to drain into it through gravity flow to provide a pressure surge so that the collection chamber causes the system to switch to full flow even more quickly with use of less water. The auxiliary pipe 427 is typically smaller than the pipe 426 and helps increase the pressure in the collection chamber with much less water. Also, water can be collected through one or more pipes, shown as inlet assembly 410 together with a second inlet pipe 428.

[0108] Best Modes of Carrying Out the Invention

[0109] Figs. 1 A and 1 B show a safety valve 105 provided on the drainage system. The purpose is to protect the drainage system from under pressures that could lead the drainage pipes to implode. The use of these safety valves can be combined with the embodiments disclosed above and will avoid implosion related damages.

[0110] In some preferred embodiments, all branch lines leading in to a manhole are directed to the dome interface, while the entire drainage pipes between manholes are dedicated to siphonic flow, thus without space taken up by pipes 114, 124 for gravity drainage. This leaves a large cross section for siphonic drainage and thus a improvement in capacity.

[0111] For improved efficiency, manholes feeding gravity flow water downstream, are in embodiments provided with a gooseneck pipe that have the inlet close to the bottom of the manhole, rising up to a height that defines when flow starts, and then descends towards a manhole provided with a dome interface. When the water level in the manhole exceeds the top of the gooseneck, siphonic flow will start. When the water level falls below the inlet, air is ingested and the flow is reduced, until the gooseneck is filled with water and the flow stops. A submerged outlet is preferred.

[0112] More preferably, the gooseneck pipe inlet opening is provided with means to retain water in the gooseneck when the water level decreases below a threshold. Such means can be valves, electromechanical valves or ball valves where the ball is raised by the water level inside the manhole, thus uncovering the inlet, and when the water level falls below the threshold, the ball closes the inlet.

[0113] Preferably the gooseneck is provided with a check valve to prevent backflow into the manhole.

[0114] In an alternative, the manhole is sealed. Where air normally exchanges freely with ambient air through a lid, the lid is closed and substantially air tight in this embodiment. Tests have shown that with a manhole having an inlet pipe for water into the manhole, the inlet pipe is positioned submerged below a level at which the gooseneck pipe starts flowing, the gooseneck will be able to enter siphonic flow and a check valve is no longer needed for preventing backflow into the manhole.

[0115] The diameter of the gooseneck can be smaller than the inlet pipe into the manhole, since siphonic flow provides far greater flow rates than for gravity flow.

[0116] Preferably, the gooseneck pipe entry comprises a dome interface.

[0117] In an application, a system with a stormwater and wastewater is envisaged. Typically, such a system comprises

[0118] 1. An inlet basin

[0119] 2. Full-flow pipe

[0120] 3. Mechanism for creating negative pressure.

[0121] 4. Outlet pipe with water locking mechanism to prevent air form returning into the pipe.

[0122] Such a system can relieve existing drainage systems or wastewater systems that have, for various reasons, become too small to perform their task. Typically, increasing rainfall and to many new houses have been connected to an existing wastewater system. The inlet basin is typically existing manholes or any tank that collects stormwater or wastewater. Full-flow pipe can be laid on the ground or buried shallowly or can be put in an existing pipe. The inlet must be lower than the outlet to allow siphonic flow, especially for stormwater.

[0123] It should be noted that:

[0124] 1 . The advantage of this solution is that no regulation is needed. The inlet level should preferably be lower than the outlet. Water flows when the water level in the basin is higher than the outlet and stops when levels equalize. As the inlet fills, flow capacity increases a maximum flow happens when the inlet is full.

[0125] 2. For wastewater, a minimum water velocity, for instance 0.8 m / s, should preferably be maintained to avoid sedimentation of the pipe.

[0126] A motorized valve is placed at the end of a pipe. Sensors measure the water level in the inlet basin and the speed of water flowing through the pipe. These sensors are connected to a controller that adjusts the motorised valve to keep the water level within a set range:

[0127] • Lower limit: gives the desired minimum water velocity Upper limit: The valve opens fully (100%) to let more water through.

[0128] To ensure full water flow in a pipe, it must be 100% filled. This can be done by using a vacuum pump connected to the full-flow pipe to remove air, with both ends submerged or the outlet connected to a motorised valve. Once filled, the air valve is closed, and the system is ready for use.

[0129] Alternatively, two small pipes can be installed in the full-flow pipe — one for filling with water and the other for releasing air. When the pipe is full, bout the air and the water valves is closed, and the system is ready for use.

[0130] If the basin is made airtight with a vent pipe in the lid, a compressor can be connected to the vent pipe and increase the pressure and force the water through the pipes. When the pipe is full, the compressor is removed, and the system is ready for operation. The tube should be filled before use and there are different ways to do it.

[0131] The outlet from the pipe forms a water lock, like a U-bend. This acts as a seal to prevent outside air from traveling back from outlet and into the pipe. End recipient is normally directly led into a bell valve but can be anything that has the capacity to accommodate the amount of water from the system in a stream, river, large culvert, tunnel and the like.

[0132] Alternative Embodiments

[0133] A number of variations on the above can be envisaged. For instance, the exits of the pipes can be provided with gates to prevent backflow and ingress of debris.

[0134] In a variation for simple systems, the stormwater manhole system could have a direct pipe connection between the inlet assembly 420 and the first outlet assembly 430, essentially short circuiting the collection chamber 410. Preferably one still employs inlet pipe wide part for air separation 422 and inlet pipe constriction 424 to remove air, and optionally inlet pipe narrow part for liquid flow 426. One may use non-return means 454, but one can also eliminate the second outlet U-bend 454, the auxiliary drainage pipe gooseneck outlet 157 and the valve 458 at the outlet into the recipient. Industrial Applicability

[0135] The invention according to the application finds use in drainage systems, in particular drainage systems for draining rainwater where the existing infrastructure uses gravity flow and has insufficient capacity to handle flow from rainwater.

Claims

Claims1 . A dome interface (200) between gravity (214, 224) and siphonic (212, 222) drainage circuits of a drainage system (100) for a fluid, wherein the dome interface (200) comprises: a surface (300) for receiving water from a gravity drainage circuit (114, 214), a dome (320) having an upper (322) closed end and a lower (324) open end, wherein the lower open end is provided above the surface (300) , separated by a gap (326) to allow fluid from the gravity circuit to flow through the gap and into an interior of the dome (320), a pipe (330) having an upper (332) and a lower (334) end, wherein the upper end is located inside the dome (320) above the gap (326), and the lower end is connected to the siphonic drainage circuit (112, 122, 212, 222).

2. The dome interface (200) according to claim 1 , wherein the upper (332) end of the pipe (330) defines an area that is smaller than an area defined by the gap.

3. The dome interface (200) according to one of claims 1 or 2, further comprising a valve (340) for throttling the upper end (332) of the pipe (320).

4. The dome interface (200) according to one of claims 1 - 3, wherein the surface (300) is further provided with at least one means from the group comprising means for slowing down the water, means for reducing turbulence, means for coalescing bubbles and means for centrifugal separation, for improved air separation from the water.

5. The dome interface (200) according to one of claims 1 - 4, wherein the gap (326) is provided with means for closing when the water is at a first lower level, and means for opening when the water is at a second upper level.

6. The dome interface (200) according to claim 1 , wherein the dome (320) is provided with valve (328) that open in a direction perpendicular to a flow direction of water through the valve (328).

7. The dome interface (200) according to one of claims 5 or 6, further comprising means (350) for lowering a pressure inside the dome (320) temporarily during opening of at least one of the gap (326) and the valve (328)8. The dome interface (200) according to claim 7, wherein the means for lowering a pressure inside the dome (320) is a valve (352) admitting air inside the dome (320).

9. A manhole system (200) comprising a dome interface according to one of claims 1 - 4, wherein the manhole system (200) further comprises: an attachment 210 with an inlet pipe assembly to a upstream drainage (110), wherein the inlet pipe assembly comprises an inlet pipe (212) for siphonic drainage surrounded by an inlet pipe (214) for gravity drainage, and an attachment (220) with an outlet pipe assembly to a downstream drainage (120), wherein the outlet pipe assembly comprises an outlet pipe (222) for siphonic drainage surrounded by an outlet pipe (224) for gravity drainage, wherein the inlet pipe (212) for siphonic drainage is connected to the outlet pipe (222) for siphonic drainage, forming part of a siphonic drainage system, which is connected to the pipe (320) of the dome interface (300), the inlet pipe (214) for gravity drainage is connected to the surface (310) for receiving water, and the outlet pipe (224) for gravity drainage is blocked inside the manhole with a block (223), to ensure all water from the inlet pipe for gravity reaches the surface (300) for receiving water.

10. The manhole system (200) according to claim 9, further comprising a raised threshold (230) at least partially surrounding the surface (310) for receiving water to ensure a minimum water level inside the manhole (200) before water flows to the surface for receiving water.11 . The manhole system according to one of claims 9 or 10, further comprising an overflow path (240, 242, 244) for excessive water inside the manhole to overflow into the outlet pipe (124, 224) for gravity drainage.

12. The manhole system according to one of claims 9 - 11 , further comprising a raised part (216) provided inside the inlet pipe (214) for gravity drainage, for directing water to the surface (310).

13. An auxiliary drainage system (140), comprising an auxiliary drainage pipe (152) having an upper and a lower end, wherein the auxiliary drainage pipe is provided with an upper valve (154) at the upper end and a lower valve (156) and the lower end, wherein the lower valve (156) is positioned near a recipient (104), wherein the auxiliary drainage system further comprises at least one auxiliary drainage branch pipeline (162) comprising a proximal end fluidically connected to the auxiliary drainage pipe (152), and a distal end connected to a siphonic drainage pipe (212, 222) of a respective manhole system (200) via a check valve (164), wherein the auxiliary drainage system (140), when filled with water, operate as a siphonic system, and extract water from the siphonic drainage pipe (212, 222), thus providing added capacity.

14. The auxiliary drainage system (140) according to claim 13, wherein the siphonic drainage pipe (212, 222) is operatively connected to a manhole system according to one of claims 9 - 12.

15. A stormwater manhole (400) system, comprising: a stormwater manhole (410), an inlet assembly (420) having an outlet provided inside the stormwater manhole (410), a first outlet assembly (430), comprising: an outlet pipe (432) having a first end operatively connected to a lower part of the stormwater manhole (410), a swan neck (440) having a first end in fluid communications with a second end of the outlet pipe (432), characterised in that the swan neck (440) defines a threshold level (442) which defines a fluid level in the stormwater manhole (410) that is above the outlet of the outlet of the inlet assembly (420).

16. The stormwater manhole (400) system according to claim 15, further comprising a retention chamber (436) provided between the second end of the outlet pipe (432) and the swan neck (440).

17. The stormwater manhole (400) system according to claim 15 or 16, further comprising a second outlet assembly (450) in in fluid communications with a second end of the swan neck (440), wherein the second outlet assembly (450) comprises: a non-return means (454) to prevent air flowing back to the swan neck (440), and a recipient outlet (458) into a recipient.

18. The stormwater manhole (400) system according to claim 17, wherein the non-return means (454) is at least one of a second outlet ll-bend (454), a check valve (458) and a motor valve (458).

19. A drainage system comprising at least one manhole according to one of claims 9 - 12, wherein the least one manhole comprises a dome interface according to one of claims 1 - 8.

20. The drainage system according to claim 18, further comprising a valve (105) provided on a siphonic drainage circuit (112, 122, 212, 222), to prevent implosion by admitting air when the under pressure exceed a threshold.21 . The drainage system according to claim 19 or 20, further comprising an auxiliary drainage system (140) according to claim 13, wherein the distal end of the auxiliary drainage branch pipeline (162) is operatively connected to the siphonic drainage pipe (212, 222) of the manhole system (200) via a check valve (164).

22. The drainage system according to claim 19 - 21 , further comprising a stormwater manhole (400) according to one of claims 15 - 18 in fluid communication with a pipe (214, 225) for gravity drainage connecting two manholes according to one of claims 9 - 12.

23. A method for starting operation of an auxiliary drainage system (140) according to claim 15, comprising the steps: a closing the lower valve (156) and opening the upper valve (154); b filling the auxiliary drainage pipe (152) with water from a manhole system near the upper end of the auxiliary drainage pipe (152); and c when the auxiliary drainage pipe (152) is substantially filled with water, closing the upper valve (156) and opening the lower valve (154).

24. A method for ending operation of an auxiliary drainage system (140) according to claim 15, comprising the step: a closing the lower valve (156).

25. A method for adjusting a valve (340) according to claim 3 for throttling an upper end (332) of a pipe (320), in a drainage system comprising at least two manholes according to one of claims 9 - 12, wherein the least one manhole comprises a dome interface according to one of claim 3 - 8, comprising the steps: a) start with all valves in the manholes in an open position, b) starting at a second to lowermost manhole as a present manhole for adjustment, c) throttle a respective valve until a manhole below the present manhole reaches a sufficient capacity for drainage, and d) progress to a manhole upstream of the present manhole as the new present manhole for adjustment.

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