oa Delineation Of Pipeline River Crossing Using Cable And Pipe Locator With Real-Time Differential Gps

The location and depth of cover over pipeline river crossings must be checked periodically to ascertain that<br>the pipeline remains undisturbed and adequately covered. We have developed a technique to determine<br>pipeline plan location and depth of cover utilizin, Q a combination of electromagnetic detection and<br>echosounding with real-time navigation, in this case differential GPS. The technique offers an alternative<br>to acoustic location methods where small pipe size or the presence of acoustically opaque sediments<br>prevent pipe detection. In addition, the technique can be used in fast-flowing rivers or in heavy marine<br>traffic where anchoring is an unlikely option. We have successfully applied the method to locate and<br>profile a 168 mm steel pipeline crossing under the Fraser River, near Vancouver, Canada.