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., <br />D -1.1 9-7g <br />DATE: <br />INTER-OFFICE <br />January 30, 1984 <br />CORRESPONDENCE <br />~II ~I~II~~I~~~~~ ~II <br />999 <br />T0: Ed Johnson R EC EIV E D cc: G. M. Stubblefield <br />E. C. Johnson <br />Ft~ 2 ~98~ W' E. Sowards <br />FROM: Larry Johns n r-, H. B. Humphries <br />~-~ ~L. <br />~dINED LAND RECLA~AATION DIVISIOPI <br />SUBJECT: SWELL FACTOR STUDY Colo. UBDt. of Natural Re50~JfCBS <br />Following are the results of our swell factor study which we initiated this <br />fall. As you recall, in July of this year we submitted a plan to the state for <br />verification of the 25% overburden swell factor which we have projected for the <br />Trapper Mine. In that plan I outlined four study areas which included two in <br />Ashmore Pit and one each in Derringer and Enfield Pits. North-south cross <br />sections were constructed through these areas combining data from our recent <br />aerial survey and from our past pit survey records. (Exhibit 1 - Plan Map) <br />After measuring and tabulating the cross sectional areas, the swell factor was <br />calculated by the following formula: <br />7. Swell Factor = [(A /A )-1]100 <br />(Exhibit 2 - Illustration) <br />Ashmore Pit showed a combined swell factor of 14.7Y, with A-1 and A-2 equal- <br />ing 24.2Y. and 7.9Y. respectively. Derringer Pit resulted in a swell factor of <br />24.8% and Enfield Pit produced a swell of 24.6Y.. The overall swell factor of <br />the four areas combined Is 21.1Y.. Dropping the east area in Ashmore Pit (A-2) <br />gives an overall combined factor of 24.6 Y.. (Tables 1 6 2) <br />TABLE ] <br />Pit Area Swell Factor <br />Ashmore 1 (A-1) 24.2 <br />Ashmore 2 (A-2) 7.9 <br />Derringer 24.8 <br />Enfield 24.6 <br />Weighted Average 21.1 <br />Ashmore 1 (A-1) 24.2 <br />Derringer 24.8 <br />Enfield 24.6 <br />Weighted Average 24.6 <br /> <br />