EVALUATION OF A RECENT MINE COLLAPSE, PICHER MINING DISTRICT, OTTAWA COUNTY, OKLAHOMA

A recent underground lead/zinc mine collapse in March, 2005 adjacent to U.S. Highway 69 in Ottawa County, Oklahoma, resulted in an evaluation by the U.S. Geological Survey, U.S. Army Corps of Engineers, Oklahoma Conservation Commission, and Oklahoma State University to access the possible damage that could occur if an additional mine collapse occurs. The collapse feature is a plug-type, approximately 3 meters in diameter, 2 meters deep, and located approximately 30 meters east from the edge of the highway. An older collapse feature, located between the recent collapse and the highway, is in the same general vicinity and is as close as 5 meters from the edge of the highway. The only current information available on the extent and location of the shallow mine excavations are subsurface maps and exploration boreholes. Since the subsurface maps were last updated, other subsurface mining excavations may have occurred that could pose an additional hazard to the highway. Surveys utilizing InSAR and tripod-mounted LIDAR were utilized to determine if subsidence prior to collapse could be observed and to monitor changes in the collapse feature. Shallow boreholes were drilled and SONAR data collected to determine the location, extent, and area of the subsurface mining excavations. This approach provided useful information and allowed the creation of subsurface profiles that delineated the mines subsurface extent and its structural integrity in the proximity of the highway.