National Dam Safety Program. New Viburnum Tailings Dam (MO 31231), Mississippi - Kaskaskia - St. Louis Basin Iron County, Missouri. Phase I Inspection Report

摘要

The dam is being constructed of lead tailings on top of an earth starter dam. It impounds lead tailings. The St Louis District (SLD), Corps of Engineers, has classified this dam as having a high hazard potential. The SLD estimated damage zone length extends approximately 15 miles downstream of the dam. Within five miles downstream are several dwellings, a church, a quarry and the town of Courtois. The contents of a portion of the damage zone were verified by aerial reconnaissance. New Viburnum Tailings Dam is classified large size based on its present height of approximately 110 ft. The present storage capacity to the spillway crest is approximately 4750 ac-ft, of which approximately 4000 ac-ft is tailings. The large size dam classification includes dams higher than 100 ft, or having storage capacity greater than 50,000 ac-ft, whichever gives the larger classification. On the basis of the visual inspection, review of available data, and inspection of aerial photos, the dam is judged to be in poor condition. This judgement is based on observation of uncontrolled seepage and associated slumping at the downstream toe of the dam, the presence of a large, 20 to 30 ft diameter sinkhole on aerial photos of the dam taken in November 1980, and lack of knowledge on the remedial measures taken to repair the sinkhole. No evidence was noted of cracking, extensive erosion, deep seated slope instability, or settlement of the crest. During the field inspection in February 1981, we did not detect the presence of the sinkhole, but did observe a drain pipe flowing at the rate of about 125 gal/min, a zone of wet tailings, and uncontrolled seepage and slumping, in the area where the sinkhole existed in November 1980.