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~~:'L i [ ( f i, ...,,_.. .---.".'.. 000661 LANDSLIDE AREAS 1) Dowds Junction slides, Ea Ie Count. This was the site of a State ands ide a ert in 1985. There are four major old slides in this area. These slides showed varyin9 de9rees of activity which increased in 1984 and 1985 with heavy snowmelt runoff. Immediate danger was to transportation and utility facilities. More serious but problematical threats were backwater and flood-release effects if serious damming of the Eagle River occurred. To evaluate and cope with this threat the Governor's Office formed the Dowds Junction Landslide Task Force. WORK COMPLETED. Based on existing information, the Task Force constructed worst case and most probable scenarios for a major slide blocking the Eagle River. From these, various mitigation and emergency response options were formalized, and emergency exercises involving local, State and Federal Agencies were held. The Task Force also recommended instrumental monitoring, drilling, and detailed geologic studies. These were initiated in 1985 and continued into 1986, and will become the basis for long-range mitigation efforts. Specific work to date includes A) core drilling of three of the slides, B) establishment of numerous EDM monitoring stations, C) preparation of detailed geologic maps and sections, 0) installation of inclinometers and water level observation wells, E) construction of a rock buttress and improved surface drainage on the "Highway Slide" on 1'leadow 110untain, F) completion of a detailed geologic map with cross sections. WORK IN PROGRESS. Readings, are being continued on all instrument statlons established in'1985. Two additional deep holes were drilled, one each on the Meadow Mountain Intermediate Slide and the Whiskey Creek Slide. The Task Force has also requested recommendations for possible surface drainage and subdrain systems to control the slides. These were formulated during the summer of 1986. FUTURE PLANS. We should continue annual monitoring and field inspections, and seek necessary funding for implementation of any engineering mitigation that is recommended by the Landslide Task Force. SOURCES OF FUNDING: SGF, LCF, SEF, CDOH, USGS. 2) Creek landslides, Gunnison Count. These three very large o an s 1 es ave een nown to t e S and under surveillance since about 1974. Alarming evidence of increasing activity was noted during the summer and fall of 1984 and prompted us to put this at the top of our list of priority study areas. Funding from the USGS Landslide Program made it possible to contract for detailed topographic maps and begin detailed mapping of the slides during the winter of 1985-86. Within a few weeks of completing work maps of this area, two of the slides accelerated and began encroaching on the stream and roadway. Availability of the detailed mapping and the knowledge derived in its preparation enabled us to advise the COOH and others in a timely fashion that minimized the eventual cost of the slide damage. - 2 - I