Title: Localization of extraneous water in pipeline networks Introduction

The present invention relates to detection of extraneous water in a pipeline network. More specifically, the invention comprises a method and a system for detecting where infiltration of extraneous water occurs in a sewer network and the amount thereof.

Background

Municipalities serve as supplier of produced and treated water and are responsible for spent water being treated in a proper manner before it runs out into nature.

Extraneous water enters such a "cycle". This may be water from precipitation that comes from downpipes, grids in the street or water that seeps into the pipeline network because of leaking pipelines and high groundwater. This is generally called extraneous water since it gets in where it is primarily not intended to be.

Extraneous water will come as an addition to consumer water that must be treated before it is discharged into nature, which will result in extra costs.

An estimate of the amount of extraneous water introduced in a municipality is around 50% or more than that represented by consumer water only. A municipality that is responsible for the treatment of the water must thus take this into account and dimension the pipeline network to have an overcapacity of at least 50% for produced water at the treatment plant. The costs associated with the treatment must also be dimensioned for this.

To relieve the resulting increased pressure on the pipeline network due to the ingress of extraneous water, measures are often taken to allow this water to run into the nearest stream or water course. This is at present a legal solution, but such discharges must be reported to the county governor with the estimated volume the overflow represents and the period in which the discharge will take place.

In many reports it is documented that precipitation in the coming years will increase along with the rate of development in densely built-up zones. A good deal of the area will be covered by asphalt, which means that much of the absorption effect normally found in nature will be absent. This will reinforce the accumulation of water masses at street level, and water from downpipes which previously ran out into nature will not have this possibility on asphalt. Many of the existing pipeline networks in towns and villages are open channels where inflow of extraneous water is a problem. Ideally, the optimal water volume that runs into the treatment plants is the same volume of water as that used by the consumer, i.e., wastewater that follows dedicated sewer pipes.

As will be understood, there is a need to be able to estimate the amount of extraneous water that enters the pipeline network. There is further a need to chart where extraneous water originates, so that necessary measures can be taken.

US 2009/201 123 Al describes a monitoring system in connection with manhole covers. The system includes sensors for detecting, inter alia, water level, and also alarm means to indicate when preset values are exceeded.

US 7221282 B l describes a wireless wastewater monitoring system. The solution includes sensors which, on detecting wastewater, initiate the system so that an alarm signal is transmitted via wireless means.

US 2004/084359 Al describes a monitoring system in connection with manhole covers for detecting and providing warning of high water level via wireless means. The prior art for providing warning of high water levels in manholes etc. does not allow for monitoring the manholes over time, so that the system can be calibrated with respect to normal water volume in each associated location that is to be monitored.

The present invention presents a method and a system for monitoring and detecting infiltration of extraneous water into a sewer network and for determining the location of the infiltration.

The solution is self-contained in that it does not require maintenance. It does not contain any exposed moving parts, and is not vulnerable to soiling. Furthermore, it requires little power in normal conditions.

Brief description of the invention

The present invention comprises a method for monitoring and detecting infiltration of extraneous water into a sewer network and the location of the infiltration, the method comprising:

- providing at least two self-contained sensor systems placed at different locations in the pipeline network to be monitored, each sensor system comprising one static level sensor connected to at least one wireless signal transmission module, and where the method is characterized in that it further comprises the steps of:

- calibrating the said sensor systems with respect to normal flow rate by measuring velocity and cross-section of flowing water in the pipeline network; - recording over time how long the water is in contact with said static level sensor(s) and collecting this data via said wireless signal transmission modules in order to establish trend analyses for increased water volume and location(s) thereof; and

- computing the amount of extraneous water that infiltrates into the pipeline network based on normal flow rate and the time during which the water is in contact with said level sensor(s). The invention also comprises a system having means for monitoring and detecting infiltration of extraneous water into a sewer network and the location of the infiltration.

The attached independent claims define the scope of protection of the invention, whilst the associated dependent claims define further embodiments.

Detailed description

The object of the present invention is as mentioned to monitor and detect infiltration of extraneous water into a sewer network. How this is solved is described in detail in the following with reference to the attached figures, wherein:

Figure 1 shows the load to which a sewer network is subj ected;

Figure 2 shows an example of deployed, self-contained sensor systems;

Figure 3 shows several static level sensors placed in connection with the sewer network to be monitored; and

Figure 4 shows an example of a trend analysis with accumulated time, where the water in the sewer network is more than 50% above normal water level.

Figure 1 shows the load to which a sewer network is subjected. Ideally, the load on a sewer network should be caused by sewage and consumer water. In practice, however, it is the case that surface water and water from, e.g., downpipes also enters the sewer network. Due to leaking sewage pipelines, groundwater pressure will also contribute to increased water volume in sewage pipes. At times, furthermore, accidents and uncontrolled industrial discharge will also contribute to an increase in the water volume that must be treated.

The inventive method for monitoring and detecting infiltration of extraneous water into a sewer network, and localization of the infiltration comprises several steps.

The first step is to provide at least two self-contained sensor systems placed at different locations in the pipeline network to be monitored. Figure 2 shows an example of a plurality of deployed self-contained sensor systems along the route of a sewer pipeline. Placing these systems at different spaced apart locations in the pipeline network provides a good basis for establishing trend analyses, and finding the cause of increased water volume at certain points in the network. In the figure six crosses are shown, each of which indicates a deployed independent sensor system. Previous empirical data for increased water level and flooding of manholes etc. will be able to give a picture of where each sensor system should be deployed.

Each sensor system comprises one static level sensor connected to at least one wireless signal transmission module. A static level sensor may in one embodiment be an electrode bar, whilst the wireless signal transmission module may be a battery-powered GSM module. Such a solution will not be vulnerable to soiling, and will at normal water levels be positioned such that the electrodes do not come into contact with the water.

Figure 3 shows several static level sensors placed across the sewer network to be monitored. In this example two level sensors are positioned about 50% above normal water level, whilst one is positioned about 100% above normal water level. What is normal water level will vary, and will depend on installation and location. Inflow from the catchment area for precipitation and the number of connection points will be of significance. Such parameters are the basis for estimating mean flow of water in a pipeline section, i.e., normal water flow at a given velocity and height, the latter determined from cross-section of the water in a pipe of a given dimension.

The invention should not, however, be understood to be limited to these heights and the number of level sensors used in each self-contained sensor system that are placed at different locations along the route of a sewer pipeline to be monitored. The heights that are chosen will be dependent on empirical data for water level and desired monitoring accuracy. The heights chosen must however be the same for all measuring points to be instrumented in the monitoring of the same sewer network. When the system is set up, it is calibrated with respect to normal flow rate. This is done by measuring velocity and cross-section of flowing water at normal water level in the pipeline network.

The water level in a sewer network will, as previously explained, vary depending on leaks, precipitation volume, discharge etc. When the system is operative, it is recorded over time how long, if at all, the wastewater is in contact with said static level sensor(s) and this data is transmitted via said wireless signal transmission modules to a central unit that establishes trend analyses for increased water volumes and location(s) thereof. Parameters for water flow and cross-section at normal conditions are recorded in the central unit where monitoring and computing takes place.

These parameters are used to compute the amount of extraneous water that infiltrates into the pipeline network based, inter alia, on normal flow rate and how long the water is in contact with said level sensor(s), i.e., the time the water is above a set normal level.

Figure 4 shows an example of a display of trend analyses for infiltrated extraneous water. An end user of the system, for example, the technical department in a municipality, will have presented date and time for high water level, i.e., how long the water is in contact with one or more level sensors (placed at different levels above normal water level at the location in which they are placed), and which sensor systems these are, i.e., the location in which the high water level occurs. The illustrated example shows a trend analysis with accumulated time where the pipeline network is more than 50% above normal water level. Data can be seen in the figure for different self-contained sensor systems (IK-368, IK-363, IK-377 etc.) that are placed at different locations along the route of the sewer pipeline that is to be monitored. When the water level at one or more locations rises to a

predetermined level above normal level, the static level sensors will record this, and data about which sensor system (i.e., location) and time (time period) will then be transmitted via a wireless signal transmission module (e.g., GSM) to a central unit that collects data from all the relevant sensor systems in order to form a complete picture of infiltrated extraneous water in a sewer network. Each sensor system can in addition transmit status info about battery level, faults etc.

The exemplary overview in Figure 4 provides useful information as regards where and when the water level is above a normal value. From this, it is possible to compute the amount of extraneous water that has to be treated before it can be discharged into nature, and not least where the extraneous water enters. The last- mentioned will identify leaks in sewer pipes, illegal discharge etc.

In the above description the steps included in the method for monitoring and detecting infiltration of extraneous water in a sewer network are described.

To be able to carry out this method, the present invention also comprises a system having means for monitoring and detecting infiltration of extraneous water into a sewer network and the location of the infiltration.

The system comprises at least two self-contained sensor systems placed at different locations in the pipeline network to be monitored, where each sensor system comprises one static level sensor connected to at least one wireless signal transmission module. The system further comprises means for calibrating the said sensor systems with regard to normal flow rate by measuring velocity and cross-section of flowing water in the pipeline network.

The system further comprises means for recording over time how long the water is in contact with said static level sensor(s), and means for collecting this data via said wireless signal transmission modules in a central unit for establishing trend analyses for increased water volume and location(s) thereof.

The system also comprises means in said central unit for computing the volume of extraneous water that infiltrates into the pipeline network based on normal flow rate and the time that the water is in contact with said level sensor(s).

Additional features of the system are described in the dependent system claims.

As mentioned, there may be different reasons why extraneous water infiltrates into a pipeline network. Regardless of the reason, it is desirable to minimize extraneous water introduced into a pipeline network since, inter alia, this increases costs associated with required treatment of wastewater in the pipeline network. The present invention contributes a useful tool for minimizing extraneous water.

By providing a method and a system for detecting infiltration of extraneous water in a sewer network and for determining the location of the infiltration, it will be possible to identify where undesirable surface water enters the pipeline network, for example, as a result of leaks, unauthorised connection of downpipes etc. Necessary and targeted measures can thus be implemented.

The trends of the water level in the pipeline network will provide a basis which will show where resources should be employed in order to reduce infiltration of extraneous water, and will furthermore indicate the proportion of extraneous water that is in a sewer network at any given time. This is an important tool for, inter alia, municipalities that are responsible for wastewater being treated properly before it runs out into nature again.