Method and apparatus for detecting leaks in buried pipes by using a selected combination of geophysical instruments
First Claim
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1. A method for detecting and locating leaks in buried pipes by radar and induction comprising:
- transmitting a ground penetrating radar signal into a subsurface region;
receiving a return radar signal for said subsurface region;
processing said return radar signal to create a processed return radar signal;
transmitting an inductive signal into said subsurface region;
receiving a return inductive signal from said subsurface region;
processing said return inductive signal to create a processed return inductive signal; and
, combining said processed return radar signal and said processed return inductive signal to detect and locate a leak in said subsurface region.
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Abstract
A method and apparatus for detecting and locating leaks in buried pipes is disclosed in which ground penetrating radar, induction, acoustic, and vacuum excavation systems are selected based on soil conditions and then employed in selected combinations. The conductivity and wave speed of the soil are used in the selection process and in the process of detecting and locating a leak based on the measurements obtained from the selected combination of detection systems.
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Citations
31 Claims
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1. A method for detecting and locating leaks in buried pipes by radar and induction comprising:
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transmitting a ground penetrating radar signal into a subsurface region;
receiving a return radar signal for said subsurface region;
processing said return radar signal to create a processed return radar signal;
transmitting an inductive signal into said subsurface region;
receiving a return inductive signal from said subsurface region;
processing said return inductive signal to create a processed return inductive signal; and
,combining said processed return radar signal and said processed return inductive signal to detect and locate a leak in said subsurface region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 13)
identifying from said processed return radar signal and said processed return inductive signal a first region within said subsurface region having a first wave speed and a first conductivity;
identifying from said processed return radar signal and said processed return inductive signal a second region within said subsurface region disjoint from said first region and having a second wave speed and a second conductivity; and
,detecting a leak in said second region if (1) said second wave speed is less than said first wave speed and if (2) said second conductivity is greater than said first conductivity.
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10. The method of claim 1 wherein said combining step further comprises the steps of:
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identifying from said processed return radar signal and said processed return inductive signal a first region within said subsurface region having a first wave speed and a first conductivity;
identifying from said processed return radar signal and said processed return inductive signal a second region within said subsurface region disjoint from said first region and having a second wave speed and a second conductivity; and
,detecting a leak in said second region if (1) said second wave speed is less than said first wave speed and if (2) said second conductivity is greater than said first conductivity and if (3) a vacuum excavator indicates the presence of a leak in said second region.
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13. The method of claim 1 or claim 11 further comprising the step of applying vacuum excavation.
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11. A method for detecting and locating leaks in buried pipes by radar, induction, and acoustic listening comprising:
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transmitting a ground penetrating radar signal into a subsurface region;
receiving a return radar signal from said subsurface region;
processing said return radar signal to create a processed return radar signal;
transmitting an inductive signal into said subsurface region;
receiving a return inductive signal from said subsurface region;
processing said return inductive signal to create a processed return inductive signal;
receiving an acoustic signal with an acoustic listening device;
processing said acoustic signal to create a processed return acoustic signal;
combining said processed return radar signal, said processed return inductive signal, and said processed acoustic signal to detect and locate a leak in said subsurface region. - View Dependent Claims (12, 14, 15)
identifying from said processed return radar signal and said processed return inductive signal a first region within said subsurface region having a first wave speed and a first conductivity;
identifying from said processed return radar signal and said processed return inductive signal a second region within said subsurface region disjoint from said first region and having a second wave speed and a second conductivity; and
,detecting a leak in said second region if (1) said second wave speed is less than said first wave speed and if (2) said second conductivity is greater than said first conductivity and if (3) said processed acoustic signal indicates the presence of a leak in said second region.
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15. The method of claim 11 wherein said combining step further comprises the steps of:
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identifying from said processed return radar signal and said processed return inductive signal a first region within said subsurface region having a first wave speed and a first conductivity;
identifying from said processed return radar signal and said processed return inductive signal a second region within said subsurface region disjoint from said first region and having a second wave speed and a second conductivity; and
,detecting a leak in said second region if (1) said second wave speed is less than said first wave speed and if (2) said second conductivity is greater than said first conductivity and if (3) said processed acoustic signal indicates the presence of a leak in said second region and if (4) a vacuum excavator indicates the presence of a leak in said second region.
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16. An apparatus for detecting a leak in a buried pipe, comprising:
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a ground penetrating radar transmitter for transmitting a radar signal into a subsurface region;
a radar receiver for receiving a return radar signal from said subsurface region;
a radar signal processor for processing said return radar signal to create a processed return radar signal;
an inductive signal transmitter for transmitting an inductive signal into said subsurface region;
an inductive receiver for receiving a return inductive signal from said subsurface region;
an inductive signal processor for processing said return inductive signal to create a processed return inductive signal; and
,a data processor for combining said processed return radar signal and said processed return inductive signal to detect and locate a leak in said subsurface region. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
processing circuitry for identifying from said processed return radar signal and said processed return inductive signal a first region within said subsurface region having a first wave speed and a first conductivity and for identifying from said processed return radar signal and said processed return inductive signal a second region within said subsurface region disjoint from said first region and having a second wave speed and a second conductivity; and
,detection circuitry for detecting a leak in said second region if (1) said second wave speed is less than said first wave speed and if (2) said second conductivity is greater than said first conductivity.
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18. The apparatus of claim 16 wherein said radar signal processor uses a layer model of said subsurface region.
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19. The apparatus of claim 16 wherein said radar signal processor further comprises processor circuitry for detecting an angular change in a straight pipe radar image.
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20. The apparatus of claim 16 wherein said radar signal processor uses multistatic transmitter-receiver geometry.
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21. The apparatus of claim 16 wherein said inductive signal transmitter uses transient fields.
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22. The apparatus of claim 16 wherein said inductive signal transmitter uses single-frequency fields.
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23. The apparatus of claim 16 further comprising an acoustic listening device receiving an acoustic signal and wherein said data processor further combines said acoustic signal with said processed return radar signal and said processed return inductive signal to detect and locate a leak in said subsurface region.
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24. The apparatus of claim 16 further comprising a vacuum excavator for verifying a leak detected and located by said data processor.
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25. A method for detecting a leak in a pipe buried in soil comprising:
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determining the conductivity of said soil;
determining the wave speed of said soil;
selecting a first leak detector and a second leak detector based on said conductivity and said wave speed;
applying said first leak detector to said soil to receive a first return signal;
applying said second leak detector to said soil to receive a second return signal; and
, combining said first return signal and said second return signal to detect said leak.- View Dependent Claims (26, 27, 28, 29, 30, 31)
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Specification