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<br />061037 <br /> <br />',' '-I"-, \ <br /> <br />SUMMARY OF DOWDS JUNCTION LANDSLIDE ALERT <br />AND SURVEILLANCE IN THE SPRING OF 1985 <br /> <br />I NTRODUCTI ON <br /> <br />( <br /> <br />Concern for determining the extent and seriousness of the threat from <br />several landslides at this location was brought to the attention of the CGS <br />through Eagle County officials and OODES staff in March of 1985. This was <br />triggered by slide activity affecting both U.S. Highway 24 and Interstate 70 <br />early in the spring of 1985. At an early stage CGS met with the Colorado <br />Department of Highways (CDOH) District Engineer and staff. During this <br />meeting a plan for limited but immediate instrumentation and complete detailed <br />geological field study later in 1985 was agreed upon. <br /> <br />Increasing levels of concern from Eagle County and DODES prompted CGS to <br />make an office study to try and determine if more urgent action was needed. <br />This study documented a definite trend of steadily increasing soil moisture <br />over tile past 3 or 4 years in Eagle County. Recognition of this condition <br />plus considerable geological similarity between the Dowds slides and the <br />situation at Thistle, Utah in 1983 gave cause for concern. (The Thistle, Utah <br />slide had blocked the Spanish Fork River, created a lake and caused extensive <br />damage to public and private facilities and property.) This information was <br />presented to David Getches, Executive Director, Department of Natural <br />Resources who felt that it would be prudent to consider an increased level of <br />surveillance in addition to the more leisurely investigations already planned <br />by CDOH & CGS. Discussions between Mr. Getche~ and the Governor's office' <br />resulted in the Governor forming a Landslide Task Force to evaluate and <br />address the Dowds Junction situation. <br /> <br />( <br />.... <br /> <br />The Task Force met approximately weekly under the leadership of Ron <br />Cattany of the DNR. Through the committee various affected and contributing <br />agencies and individuals were identified a~d liaison established. A more <br />aggressive schedule of studying and monitoring the slides was devised and <br />undertaken, emergency response plans and exercises were implemented and <br />various contingencies were considered and discussed at length in the <br />meetings. The Task Force also assisted DDDES in planning and carrying out two <br />emergency exercises for the Dowds Junction area. <br /> <br />EXPLORATION DRILLING AND INSTRUMENTATION <br /> <br />To better understand and monitor the slides the Task Force initiated a <br />program consisting of four parts. <br /> <br />1. Exploratory core drilling was used to determine composition of the <br />slide, the depth to the basal shear surface and water conditions <br />within the slide masses. <br /> <br />2. In order to monitor changes of water level at certain key locations <br />some drill holes were completed as hydrologic observation wells. <br /> <br />- lA- - <br />