Geophysical Surveys for Detecting Anomalous Conditions, Algiers Canal Levees, New Orleans, Louisiana

摘要

This report presents the results of a geophysical study performed to locate buried debris within the levees on the west side of Algiers Canal approximately 8 km (5 miles) south of downtown New Orleans, LA. The levees are located adjacent to industrial and metal fabricating businesses. Reportedly, metallic debris, rubber hoses, concrete chunks, large pockets of shells, and other rubble have been found in these levees. A concern arose that debris and/or unmarked utilities located beneath or buried near the toe of the levees could affect the performance of the levee during flooding events. If a pipe or conduit exists under or within the levee, a possibility exists that it may fill with water during a flood event. If it does, and the conduit fails, it is possible that it may cause the levee to collapse either by piping material from within the levee or cause slope stability problems. It is also possible that buried utilities can act as potential seepage paths through the levee during high-water events. Buried debris and utilities need to be accurately located so that they can be removed or, in the case of a buried utility, re-routed or filled with grout. An electromagnetic (EM) induction survey using a Geonics EM31 terrain conductivity meter was conducted along the crest, slopes, and toes of the levee to locate anomalous conditions indicative of buried material. EM31 anomalies, presumed to be the location of buried debris, were mapped, and their coordinates tabulated for further interrogation.