Abstract:
A method of operating a horizontal filter well. Water is transported into a well from at least one roughly horizontally arranged train and distributed further from there. Pressurized water is forced through the horizontal filter train in the reverse flow direction, as a means to free the horizontal filter train of blockages. The pressurized water exits through the inlet orifices of the horizontal filter train and passes into the aquifer. A vertical well provided in the vicinity of the horizontal filter train suctions off the water exiting from the horizontal filter train, along with impurities removed from the horizontal filter train.

Description:
BACKGROUND INFORMATION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to a horizontal filter well system and a method of same. More particularly, the invention relates to reverse-flow method of cleaning horizontal filter trains. More particularly yet, the invention relates to a method of removing impurities from the area surrounding the horizontal filter trains. 
         [0003]    2. Description of the Prior Art 
         [0004]    Horizontal filter wells are known in the everyday world. After years of operation, the inlets of the one or more horizontal filter trains in a well may become blocked. The inlets can be opened and freed of the obstructions by reversible flow or backwashing with pressurized water. The disadvantage of this conventional method is that the period is relatively short before the horizontal filter trains need to be cleaned again. As a result, the longer the horizontal filter well is operated, the shorter the intervals between cleanings become. Eventually, it becomes uneconomical to operate the horizontal filter well. 
         [0005]    It is an object of the invention to provide a well system and a method of operating such a system, that greatly increases the operating time during which the horizontal well trains are functioning properly. It is a further object to provide such a system and method that improves the economic performance of such horizontal well filters over a longer period of time. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    The object is achieved by a method and a well system that use pressurized water in a reverse-flow direction to clean groundwater inlets in a horizontal filter train. More particularly, the method and system provide the use of a vertical well, sunk into the ground near the horizontal filter train, the vertical well pumping the reverse-flow water away from the underground and, along with the reverses-flow water, by collecting and pumping out impurities that were forced out of inlets in the horizontal filter train. 
         [0007]    The invention proposes to extract the released contaminants while cleaning the horizontal filter trains. The method and system according to the invention extract contaminants that have been expelled from the horizontal filter train during a cleaning operation. Without such an extraction, impurities near the horizontal filter train remain in the ground nearby the horizontal filter train and are subsequently pulled back in, so that they re-enter the horizontal filter train relatively quickly. The method according to the invention pumps water out of a vertical well that is sunken near the horizontal filter train whenever the horizontal filter train is cleaned by backwashing. This pumping action creates a flow of water through the substrate into the vertical well. The term “substrate” as used herein refers to the area in the ground that is in the vicinity of the horizontal filter train. The impurities are thus flushed away from the horizontal filter train and removed from substrate through the vertical well. This increases the interval between cleanings of the horizontal filter train, which greatly increases the period of economic operation of the horizontal filter well. 
         [0008]    Preferably, the water that is pumped from the vertical well is maintained in a closed loop, so as to minimize contact with underground water supply. The water coming from the vertical well is filtered and immediately reusable for backwashing the horizontal filter train. 
         [0009]    Alternatively, the method may pump water from the vertical well, which is laden with impurities, and store it in a reservoir for later treatment. This is especially desirable, if a cleaning agent is added to the pressurized water to improve its cleansing effect when backwashing the horizontal filter train. This wastewater full of cleaning agents may, for example, be stored temporarily in a tank truck, which serves as the aforementioned reservoir, and subsequently be transported to a suitable treatment plant. 
         [0010]    Cleaning the horizontal filter train improves the pumping capacity of this horizontal filter train, which had previously continuously decreased. The pumping capacity is affected, however, not only by blocked inlets in the horizontal filter train itself, but also by the fact that, cracks and other small cavities in the surrounding earth, through which the water flows into the horizontal filter train, are closed or blocked. The cleaning operation on the horizontal filter train, during which water is pumped through the vertical well, also advantageously results in a “cleaning” or loosening of the surrounding earth. For this purpose, a high-pressure injection train is arranged horizontally in the ground near the horizontal filter train. In the case of two adjacent horizontal filter trains, which, for example, are arranged at a 90° angle, the high-pressure injection train is arranged at an angle that approximately bisects the angle formed by the two horizontal filter trains, in order to achieve the most uniform effect on the two adjacent horizontal filter trains. The injection material, which is forced into the substrate by the high-pressure injection train, loosens the earth and breaks up sedimentation that has settled in the spaces that exist in the substrate, so that groundwater is subsequently able to flow through the spaces that have now been reopened. 
         [0011]    The vertical well near the aforementioned horizontal transport train, including a specially sunken vertical well, is provided near the high-pressure injection train. This vertical well is used to pump the injection material or also the loosened sedimentation in the underground from the underground. Here, too, the water coming from this vertical well is either filtered and reused, that is, is pumped in a closed loop during the cleaning process, or, alternatively, temporarily stored and then transported to a treatment plant. 
         [0012]    In addition to the aforementioned method steps, the horizontal filter trains may be cleaned mechanically in the conventional manner, for example, by means of a cleaning lance and with pressure, which is a commonly known method. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0013]    The present invention is described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. 
           [0014]      FIG. 1  is a plane elevational view of the horizontal filter train. 
           [0015]      FIG. 2  is a plane elevational view of the well shaft, indicating a plurality of horizontal filter trains and showing injection sites on the RSFA. 
           [0016]      FIG. 3  is a vertical cut through a portion of a horizontal filter train and RSFA. 
           [0017]      FIG. 4  is a top plane view of the well shaft, showing a plurality of horizontal filter trains, high-pressure injection trains, and vertical wells. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0018]    In the drawings, a horizontal filter well is generally designated by  1 , a well shaft by  2 , and a well house  3  arranged above it. Several horizontal filter trains  4  open into the well shaft  2  below, whereby in  FIG. 1  only one such horizontal filter train  4  is shown. The horizontal filter train  4  has a plurality of inlets  5 , which are shown as slots in  FIG. 1  and through which water from the surrounding layers of earth flows into the horizontal filter train  4 . 
         [0019]    The horizontal filter train  4  is connected inside the well shaft  2  to a reversing single-train flange adapter  6 , hereinafter referred to as RSFA. The RSFA  6  has a connection for a pressurized water line  7  on its upper face end. Pressurized water is pumped by pressure pump  8  through the pressurized water line  7  into the RSFA  6 . 
         [0020]    To clean the horizontal filter train  4 , pressurized water is pumped through the pressurized water line  7  into the RSFA  6  by a pressure pump  8 . From the RSFA  6  it flows into the horizontal filter train  4  and exits the horizontal filter train  4  through the inlets  5 , moving into the surrounding layers of earth. The pressurized water flows through the horizontal filter train  4  in a direction that is the reverse of the direction of normal flow of water into the horizontal filter train. During this reverse flow process, impurities or debris which are clogging or restricting the size of the inlets  5  are flushed from the inlets, with the result that these inlets  5  become open again. The debris being expelled from the horizontal filter train  4  is shown schematically in  FIG. 1  as a nebulous agglomeration surrounding the far end of the train. 
         [0021]    A vertical well  9  is sunken adjacent to the horizontal filter train  4 . This vertical well  9  has openings that are crude, compared to the inlets  5  of the horizontal filter train  4 . A pumping operation of this vertical well  9  pumps away the pressurized water that was used to flush out the horizontal filter train  4 , and also pulls debris or impurities into the vertical well  9 , which are then pumped out. This achieves a long-lasting cleaning effect for the horizontal filter train  4 . In addition, the area around the horizontal filter train  4  is cleaned of debris, which, if left there, would re-clog the inlets  5  within a relatively short period following the cleaning process. 
         [0022]    The water that was previously used for cleaning the horizontal filter train  4  is pumped up through and out of the vertical well  9 . Subsequently, it may be fed through a closed-loop line I 1  to the pressure pump  8 , whence it may be pumped through the pressurized water line and the RSFA  6  back into the horizontal filter train  4  to be re-used as a cleaning fluid. Alternatively, the water pumped from the vertical well  9  may be pumped into a temporary reservoir, such as a tank truck, via a discharge line  12  for subsequent water treatment. Subsequent water treatment may be desirable, particularly if a cleaning agent is added to the pressurized water. Cleaning agents may be pumped from tanks  14  via appropriate lines to injection sites  15 , where they are injected into the RSFA  6  and, together with the pressurized water, subsequently flow into the horizontal filter train  4 . The three tanks  14 , which are shown merely by way of example, illustrate that different additives may be mixed with the pressurized water. These additives shall be referred to as “cleaning agents” hereinafter, regardless of their properties and effects. 
         [0023]    A plurality of valves  16  are shown schematically in  FIG. 1 , whereby not all valves  16  are marked with the reference numeral. The valves allow one to control the flow of the water. The water may be pumped, for example, through a circuit line or to the discharge line  12 . Thus, for example, water that is pumped from the vertical well  9  may initially be pumped into a centrifuge  17 . The centrifuge  17  is used to remove debris and impurities from the water that have been pumped up through the vertical well  9 . The purified or filtered water may then be pumped from the centrifuge  17  to the pressure pump  8  and made available there again for cleaning the horizontal filter train  4 . Advantageously, the pressure pump  8  builds up a pressure of more than  5  bars, which ensures reliable cleaning of the inlets  5  of the horizontal filter train  4 . 
         [0024]    A high-pressure injection train  18  is also shown in  FIG. 1 . In the schematic illustration, the high-pressure injection train  18  appears to lie directly opposite the horizontal filter train  4 . In reality, however, the high-pressure injection train  18  extends at an angle between two horizontal filter trains  4 , as shown particularly clearly in  FIG. 4 , bisecting the angle formed by two horizontal filter trains  4 . 
         [0025]    A reservoir  19 , which contains injection material, is provided next to the well house  3 . This injection material may also be pumped to the pressure pump  8 , for example, using a rotary pump  20 . The pressure pump  8  subsequently pumps the injection material into the high-pressure injection train  18  via the pressurized water line  7  and the RSFA  6 . Connector flanges are provided on the RSFA  6  and the corresponding trains  4  and  18 . The RSFA  6  is shifted inside the well shaft  2  and connected via the connector flanges to the horizontal filter train  4  and/or high-pressure injection train  18 . A locking slide  21  is preferably arranged between the RSFA  6  and the respective trains  4  and  18 . The locking slide  21  may be operated remotely, for example, by a handwheel  22  in the well house  3 , as shown schematically in  FIG. 1 . 
         [0026]      FIG. 2  illustrates a method of operating the horizontal filter well for water catchment. For purposes of illustration only, the RSFA  6  is shown mounted on one of the three horizontal filter trains  4  shown in  FIG. 2 . In particular, an RSFA  6  may connected to each of the horizontal filter trains  4 . 
         [0027]    In the embodiment depicted in  FIG. 2 , three water lines  24  lead from the horizontal filter trains  4  or the RSFAs  6  to a water main  25 . Each of the horizontal filter trains  4  are arranged offset  900  to one another, so that a fourth horizontal filter train  4  in fact exists, but is not visible due in the cross-sectional view in  FIG. 2 , because it is aligned with the horizontal filter train  4  that is shown in the center of the well shaft  2 . A water-supply line  24 , also not shown in  FIG. 2 , also runs from this fourth horizontal filter train  4  to the water main  25 . 
         [0028]    In the embodiment shown in  FIG. 2 , the well shaft  2  can be operated using a so-called “dry” operating method in which the water level of the groundwater drawdown cone  27  does not adjust in the well shaft  2  itself, but rather adjusts in the RSFA  6  or in the water-supply lines  24  of the individual horizontal filter trains  4 . An immersion pump  26  is provided in the each RSFA  6 , which pumps water from the relevant horizontal filter train  4  to the water main  25 . Each of the four horizontal filter trains  4  has its own flange adapter in the form of an RSFA  6 . This arrangement particularly allows each horizontal train  4  to be individually pumped and sampled. 
         [0029]      FIG. 3  shows a cross-sectional cut through the lower area of the well shaft  2  and a portion of the RSFA  6 . The mounting flange  23  may be used not only to connect an additional horizontal filter train  4 , but also to insert a cleaning tool directly opposite the horizontal filter train  4  into the RSFA  6 . The tool may be guided through the RSFA  6  into the horizontal filter train  4 , so that this train may be cleaned from the inside in a conventional manner, either mechanically using the cleaning tool or using compressed air or pressurized water. A camera may also be introduced here and guided into the horizontal filter train  4 . 
         [0030]    The water level inside the RSFA  6  is marked with  27 . A water probe  28  is used to protect the immersion pump  26  from dry operation, and to ensure that water is always available at an inlet  29  of this immersion pump  26 . The water probe  28  may be used to either analyze the water or at least determine the height of the water level  27 , so that, if the water level  27  should sink, pumping in this horizontal filter train  4  is slowed or stopped. 
         [0031]    Injection sites  15  are used to inject cleaning agents into the pressurized water during the reverse-flow operation of the RSFA  6 , that is, during the cleaning of the horizontal filter train  4 . Each of the injection sites has a mounting flange. During the pumping operation of the well, sensors may be inserted into these injection sites  15 , for taking measurements during the pumping operation. Such measurements would be different, for example, from the measurements taken by the water probe  28 . Furthermore, the RSFA  6  also has a relatively small drain connection  30  below the mounting flange  23 , by means of which the RSFA  6  can be completely drained. 
         [0032]      FIG. 4  schematically shows the layout of a well shaft  2  having four horizontal filter trains  4 , each of which is offset by 90° from the other, as well as four high-pressure injection trains  18 , each of which extends into the well shaft at an angle that bisects the angle formed by adjacent horizontal filter trains  4 . Schematic representations of vertical wells  9  are shown distributed around this horizontal filter well  1 . During cleansing or regeneration operations on the horizontal filter well  1 , water, cleaning agents, impurities and, if necessary, also injection material may be pumped out through these vertical wells  9 . It is understood that the embodiments described herein are merely illustrative of the present invention. Variations in the construction of the horizontal filter well and in the method steps may be contemplated by one skilled in the art without limiting the intended scope of the invention herein disclosed and as defined by the following claims.