A new method to identify and subsequently seal surface infiltration zones was tested by the U.S. Bureau of Mines at a stream near frostburg, MD, that partly overlies abandoned coal mine workings. Electromagnetic terrain conductivity surveys were performed within the stream channel to identify water-saturated zones at relatively shallow depths between 10 to 50 ft (3 to 15 m). Zones of increased conductivity were generally found to be positively associated with areas exhibiting significant loss of flow. Conversely, zones that exhibited declining conductivity delineated areas where flow losses were not significant. Using this information, an experimental grouting procedure was used to inject expandable polyurethane grout a few feet (less than 1 m) into the streambed over a 600-ft (180-m) section of the stream channel. Before grouting, the section exhibited a 38-pct flow loss; first-phase postgrouting data demonstrated a reduction to a 20-pct flow loss. The conductivity surveys represent a significant cost savings in gaging work necessary for delineating stream loss zones. The cost of grouting was 50 pct less than the costs associated with conventional rechannelization, clay lining, and rock rip-rapping techniques used in the same watershed.
Proceeds 1988 Symp. on Mng., Hydrology, Sediment. & Reclamation, Univ. Kentucky, PP. 79-84