| OCR Text |
Show three- thousand yards above the canyon bottom, f r a c t u r e lines appeared in the entire basin. A massive s l i d e swept down the slope and d i r e c t l y onto the administration b u i l d i n g , v i r t u a l l y demolishing the structure. Management personnel estimated the damage at $ 225,000. COMMENTS One, or several, rounds of a r t i l l e r y f i r e may not always trigger a large slide. The key shot has t o be placed in j u s t the right location. Knowledge of normal f r a c t u r e l i n e locations is e s s e n t i a l . Under favorable conditions, f r a c t u r e lines can propogate a long distance. A year before, 25 January, 1964, a major natural slide occurred at the same place. Considerable damage was also done t o the administration building at that time. ( See No. 64- 3) No. 65- 5 HOMESTAKE LAKE. COLORADO 31 January 1965 WEATHER FACTORS The amount of snowfall in the area p r i o r to 31 January was above normal. Soil Conservation records show that the snow pack was at 130% of normal for the Upper Colorado River Basin. During the last six days of January, f i f t y - e i g h t inches of new snow f e l l on the h i l l s around the valley. Fourteen inches f e l l on the 30th alone. ACCIDENT SUMMARY During the winter of 1965, employees of the Berco Company ( subcontractors of the Morrison Knudson Construction Company) were engaged in extensive tunneling operations in the v a l l e y f l o o r near Homestake Lake. Three parallel tunnels were being driven into the slope along one side of the valley. These " Coyote Tunnels," were t o be used in May, 1965, to plant a large dynamite charge - 1,100,000 pounds - which was intended to provide earth f i l l for a dam. Because of a t i g h t construction schedule, contractors were working through the w i n t e r , around the clock. On the night of 30 January, six employees were working the graveyard s h i f t; two men were working in each t u n n e l . D. H. and L. K. were working in Tunnel Three. L. K. l e f t the tunnel at 2: 30 a. m. ( 31 January) to dry out his clothes in another short tunnel about s i x t y feet from number three. While drying his boots and socks, L. K. heard what sounded l i k e a gust of wind and noticed snow blowing into the tunnel. A huge avalanche had released two thousand feet up the mountain, carrying f i v e to ten thousand cubic 123 |
