This invention generally relates to systems and methods for detecting underground, i.e., below ground surface, cross-bores.
Drilling operations using trenchless Horizontal Direction Drilling (HDD) and moles are increasingly commonly being used for or in the installation of pipelines such as for natural gas distribution, for example, without the need for open trenches. Unfortunately, such operation and associated equipment can result in contact and rupture of other existing utility lines during the drilling process.
Existing utilities in the path of a new installation are commonly identified and located before the drilling operation. Most available locating technologies are focused on detecting metallic pipes or pipes buried with a tracer wire. Sewer lines, however, are generally non-metallic and are commonly not installed with tracer wires. Thus, HDD installations have been known to occur wherein a gas pipe has unintentionally been installed through a sewer line and the operator is unaware of the situation. Such an installation can create or result in a blockage in the sewer line and the sewer line cleaning process can cause damage to the gas pipe such as to result in a gas leakage through the sewer line, for example.
Several technologies exist or have been proposed to locate sewer lines before and during the installation of new pipes, including:
(a) Locating Sewer Lines Prior To New Pipe Installation:
(b) Locating Sewer Lines During Pipe Installation:
Thus, there is a need and a demand for systems and methods that can detect underground cross-bores, such as sewer pipes, such that a contact or hit of a sewer line and allow the operator to remedy the situation and perform corrective actions; thereby preventing future potential incidents and reducing the percentage of such hits which at least initially go undetected.
Accordingly, it is one object of this invention to provide a system and method for detecting an underground cross-bore.
This and other objects of the invention are addressed in one aspect of the invention by a system that includes a mechanical sensing device attached to an underground travel element to form a combination adapted for underground travel. The mechanical sensing device senses at least an initial underground condition wherein the combination is ensconced in an underground bore. The mechanical sensing device also senses a second underground condition wherein the sensing device senses entry into a pipe cavity. The mechanical sensing device then provides a signal identifying entry into a pipe cavity.
In particular embodiments, the apparatus can be attached to the pipe, e.g., polyethylene (PE) pipe, during pullback of the pipe after the initial drilling stage. Such a cylindrical unit can desirably be a low-cost and easy to use mechanical or spring system. Such a system can be activated when it moves from a confined soil to a cross-bore such as a void space such as a sewer pipe void; thus serving to locate such a sewer lateral and providing a real-time signal or alarm identifying a cross-bore hit.
In one specific embodiment, the cylindrical unit has arms with springs disposed around its perimeter. The arms are in a closed position when confined in soil. When the unit encounters a void space such as inside a sewer pipe, the spring arms open and an electronic signal indicating arm movement can be recorded or sent to the surface such as via a signal wire or wireless system.
In accordance with another aspect of the invention, there is provided a method for detecting an underground cross-bore. One such method involves transporting underground a combination of a mechanical sensing device attached to an underground travel element wherein the mechanical sensing device senses at least an initial underground condition wherein the combination is ensconced in an underground bore and a second underground condition wherein the sensing device identifies entry into a pipe cavity, with the mechanical sensing device providing a signal identifying entry into a pipe cavity.
These and other objects and features of this invention will be better understood from the following detailed description taken in conjunction with the drawings, wherein:
The underground cross-bore detection arrangement 100 involves the underground transportation of a combination 110 such as formed by a mechanical sensing device 112 attached or otherwise appropriately coupled to or with a selected underground travel element 114. As described in greater detail below, mechanical sensing devices in accordance with certain preferred aspects of the invention are effective to sense at least a first underground condition wherein the combination is ensconced in an underground bore and a second underground condition wherein the sensing device senses entry into a pipe cavity, with the mechanical sensing device providing a signal identifying entry into a pipe cavity. Further, suitable underground travel elements in accordance with selected embodiments of the invention can include, without unnecessary limitation, a drill head, a mole or a pipe, for example.
As shown the underground cross-bore detection arrangement 100 may also include an above-ground base unit 116, such as may include a receiver such as to receive signals such as provided or resulting from the mechanical sensing device 112.
Turning to
As shown in
The cylindrical base or body portion 212 can desirably be or have the same diameter as the HDD drill head or other desired underground travel element onto which the device 210 can desirably be mounted. In the illustrated embodiment, the first end 214 is open ended forming an open end 220 such as suitable for pipe end attachment of the device 210. The opposed second end 216 includes a pull ring 222, as further discussed below.
Adjacent the second end 216, the device 210 includes at least one mechanical arm 224. The movement of the arm 224 desirably can produce or result in an ON/OFF signal which can be stored or transmitted (wired or wireless) to the surface indicating the position of the mechanical arm.
While the mechanical sensing device 210 shown in
The mechanical arms 224 are closed when the device 210 is in soil, as shown in
As identified above, the movement of the arm(s) 224 desirably can produce or result in an ON/OFF signal which can be stored or transmitted (wired or wireless) to the surface indicating the position of the mechanical arm(s). An ON/OFF electronic signal can be sufficient to indicate if the apparatus has encountered a void such as representing a sewer lateral when some or all the springs are opened inside the sewer pipe. Further calibration of the sensor will filter false signals in soil and provide an indication of the size of the sewer line when the spring system is moved back in the soil.
For example, in the embodiment shown in
As further shown in
As identified above, the mechanical sensing device 210 may include or have associated therewith, such as in or as a portion of the main body 212, features such as to permit storage or transfer, electronically or otherwise, of signals or data obtained or gathered by the device 210. Such features in accordance with particular embodiments can, for example, include: one or more memory cards such as to record signals received from the mechanical sensing device, a transmitter to transmit signals from underground to aboveground such as to an aboveground receiver.
Turning now to
The underground cross-bore mechanical sensing device 310, rather than incorporating and relying on one or more mechanical arms instead includes at least one pressurized bag 324 appropriately disposed at or about a perimeter portion of the cylindrical base or main body 312 of the device 310 and which base can be attached or mounted to a selected underground travel element, such as described above. In the illustrated embodiment, the device 310 is shown as including eight such pressurized bags 324 evenly spaced about the perimeter of the cylindrical base. As with the mechanical arm-including embodiment of the device described above which can include various selected number of arms, such a pressurized bag-including device embodiment can include various selected number of pressurized bags.
As shown in
In further specific embodiments, the pressure change in each bag as a result of exposure to a cavity or open volume such as the inside a sewer pipe desirably can produce or result in an ON/OFF signal which can be stored or transmitted (wired or wireless) to the surface and which signal can, if desired, also identify the specific pressurized bags which have expanded, e.g., are exposed to a cavity or open volume such as inside a sewer pipe.
Turning now to
The underground cross-bore mechanical sensing device 410, rather than incorporating and relying on one or more mechanical arms 224 as with the above-described embodiment device 210 or one or more pressurized bags 324 as with the above-described embodiment device 310 instead includes a load cell 424 such as can be mounted to, on or with a selected underground travel element, such as mounted behind a drilling head, with the load cell 424 effective to monitor loads, such as the load required to break the wall of the sewer pipe. The load cell measurements will display a relatively high reading during the HDD or mole penetration through the wall, followed by a zero or near zero reading when the drill head does not meet resistance such as once exposed to the void or open area 420 such as the pipe cavity provided or resulting from the sewer pipe 422. The load cell measurements will display an intermediate reading during the HDD penetration through a sand backfill or the like 442, such as disposed about the underground pipe 422.
In practice, load cells for use in the measurement of soil resistance are commercially available in cone penetrometer test devices (CPT) where they provide “real time” data to characterize the soil resistance as the instrumented cone is driven into the soil.
The pressure cell signal can be appropriately transmitted (wired or wireless) to a read out box at the surface.
Those skilled in the art and guided by the teachings herein provided will appreciate that the invention can desirably provide or result in numerous and various advantages including, for example:
It will be appreciated that at least in selected embodiments, the mechanical sensing devices and methods of the invention serve to detect hits or contacts with underground bores, such as sewer pipes, only after a hit or contact with the particular underground bore. That is, in such embodiments, the devices and methods of the invention do not necessarily serve to prevent such hits or contacts. Nevertheless, such application of the mechanical sensing devices and methods of the invention can serve to allow the operator to remedy the situation and perform corrective actions; thereby preventing future potential incidents and reducing the percentage of hits which go undetected.
Moreover, the operation can with practice and use be appropriately calibrated such as to permit the ready identification of false signals such as may result from natural voids, such as may exist or be present in various soil formations. It will be further appreciated that wireless transmission of signals through the soil can be affected by the depth and soil type.
Moreover, through the ability to attach the mechanical sensing device of the invention to various underground travel elements such as, for example, a drilling head or a pipe during pullback, the invention presents a safe and economic solution to the need to detect incidents of pipe encroachments during HDD and mole operations.
In accordance with particular embodiments, mechanical systems of the invention are:
As will be appreciated by those skilled in the art and guided by the teachings herein provided, through the practice of the invention and the implementation of the cross-bore detection tool thereof, safety for homeowners can be improved and the installation of distribution gas lines in difficult areas where sewer lines intersect can be enhanced.
The invention illustratively disclosed herein suitably may be practiced in the absence of any element, part, step, component, or ingredient which is not specifically disclosed herein.
While in the foregoing specification this invention has been described in relation to certain preferred embodiments thereof, and many details have been set forth for purpose of illustration, it will be apparent to those skilled in the art that the invention is susceptible to additional embodiments and that certain of the details described herein can be varied considerably without departing from the basic principles of the invention.
Number | Name | Date | Kind |
---|---|---|---|
4694913 | McDonald | Sep 1987 | A |
20020166396 | McGrew | Nov 2002 | A1 |
20060220651 | Clark | Oct 2006 | A1 |
20100018305 | Maute | Jan 2010 | A1 |
20120055711 | Brannigan | Mar 2012 | A1 |
20140138084 | Al-Mulhem | May 2014 | A1 |
Number | Date | Country | |
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20150000979 A1 | Jan 2015 | US |