_GENERAL DOCUMENTS - C1981017 (262)

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of Soto DEPARTMENT OF NATURAL RESOURCES * David H.Getches,Executive Director MINED LAND RECLAMATION DIVISION f 876 D"ID C.SHELTON, Director Richard D.Lamm Governor February 17, 1984 Mr. Doug Bowman Mid-Continent Resources, Inc. P.O. Box 158 Carbondale, Colorado 81623 Re: Quantification of Sediment Generated by Road System File No. C-017-81 Dear Mr. Bowman: I have completed an extensive analysis of the water quality data contained in the Coal Basin Mines permit application and in your letter of December 23, 1983 in order to quantify the road system sediment yield. In your letter, you came up with a sediment yield estimate of approximately 3 tons/acre/year. Using the data from both sources, I calculated several estimates of the road system sediment yield that varied between 1 .4 tons/acre/year to 22.8 tons/acre/year. At that point, it became evident to me that the actual contribution of sediment from the road system cannot be quantified without installing a more sophisticated monitoring system. In order to determine whether a road drainage monitoring system is warranted, I conducted a t-test on the Total Suspended Solids (TSS) data from all 10 stream monitoring sites. This analysis shows whether there are any statistical differences in TSS levels between the stations and between undisturbed and disturbed drainages. No significant differences were found at the 1% level . Therefore, I do not feel that any additional monitoring is necessary at present. During my next inspection, I will discuss my methods of data analysis in more detail . If you have any questions in the interim, please don't hesitate to call me. 4incerely m Herron Reclamation Specialist JH/mt Doc. No. 9473 423 Centennial Building, 1313 Sherman Street Denver, Colorado 80203 Tel. (303)866-3567