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<br /> <br /> <br /> <br />1 <br />1 <br />1 <br /> <br />1 <br /> <br />Ll <br />1 <br /> <br />1 <br /> <br /> <br />1 <br /> <br />iii iiiiiiiiiiiii iii <br />TECHNICAL MEMORANDUM <br />To: Henry Bazbe <br />Mountain Coal Company <br />From: Wright Water Engineers, Inc. <br />Emest Pemberton, P.E. and Jonathan M. Kelly, P.E. <br />Re: Pre-Mining Stream Channel Conditions on Deep Creek <br />Date: July 28, 2000 <br />INTRODUCTION <br /> <br />ocre2z~ <br />Oivisian of Itlinerals an, <br />This report describes an analysis of the channel hydraulic characteristics and sediment transport <br />parameters for the study reach on Deep Creek, between the Upper and Lower gaging stations. <br />The study reach is approximately 8300 feet in length and ranges in elevation from 7180 feet to <br />7590 feet. Ernie Pemberton and Jonathan Kelly of WWE and Dave Nicewicz of West Elk Land <br />Surveying conducted field observations of Deep Creek in this reach on June 19, 2000. West Elk <br />Land Surveying performed the survey of the thalweg profile and typical cross sections of the <br />channel. The attached eight photographs show typical views of channel conditions. <br />The detailed surve} of the channel and this evaluation of existing channel characteristics <br />represent pre-mining conditions for establishing a base for any projected changes due to mining. <br />Longwall mining has the potential to affect stream channels by inducing differential subsidence, <br />which can increase or decrease the stream channel gradient. The magnitude of the subsidence is <br />expected to be less than that observed in previously mined areas due to an overburden depth in <br />excess of 3000 feet. <br />A plot of the stream thalweg profile based on the survey for the study reach is shown on Drawing <br />1. Also shown on Drawing 1 are six channel cross sections located in the study reach. <br />SUMMARY OF FIELD OBSERVATIONS <br />Deep Creek channel at several locations within the study reach is shown on the attached Photo 1 <br />through Photo 8. An upstream view of Deep Creek at the Lower gage is shown on Photo 1. The <br />dead logs strewn across the channel as shown on Photo 1 aze similar to channel conditions at <br />many locations throughout the study reach. The large cobble and boulder size rocks up to 1 to 2 <br />feet in diameter are very common along with sand size sediments in the streambed. A sample of <br />the sand size sediments was collected near the gauge, which visually was a fine to medium size <br />Wrighl Water Engineers, Inc., 2490 W. 26°~ Avenue, Ste. 100A, Denver, CO 80271 <br />Tel. 303/460-1700; Fax. 303/480-1020. e-mail:knvright@wrighlwater.com <br /> <br />