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sloughing of the topsoil layer, we recommend that the top of the cut slopes be situated at least 20 feet from the • edge of the gas line easement or the power pole foundations. We have assumed that the pit excavations will be filled in with the overburden spoils or other waste materials and recommend that the final slope configuration be 3(H) to 1(V) or flatter. Based on our experience with similaz proiects, we believe that the finished slopes constructed to a 3(H) to 1(V) slope configuration should be stable as long as the fill materials are adequately. compacted and drainage is provided. We recommend that the spoils and other waste material be compacted to at least 85% of the maximum modified Proctor density. HAUL ROAD F:ECOMhIENDATIONS Based on our experience with similaz projects, we recommend that a minimum of 5 feet of soil cover be provided over the existing gas line to prevent damage to the gas line due to heavy truck traffic. The upper 2 feet of fill materials placed in the embankment should consist of the sands and gravels, whereas, the deeper fill materials can consist of other overburden soils. All fill materials placed in the roadway embankment should compacted to at least 95% of the maximum modified Proctor density near optimum moisture content in accordance with ASTM D1557. Based on our experience with similar projects and [he subsurface conditions encountered at this site, we believe that the construction and use of the proposed haul roads will not have a detrimental affect on the existing gas line • or power poles, as long as the roadways and pit excavations aze constructed in accordance with the above recotnnrendation:s and properly maintained. If the recommendations given above aze followed during the mining operations, we do no[ believe that strain gages will be necessary along the gas pipe line. SITE RECLAMATION The following rccotnmendations should be followed to reduce the potential off-site or on-site impacts related to the reclamation of the site from a geotechnical standpoint. 1) Positive: surface drainage features should be constructed azound the perimeter of the reined areas so that the surface runoff is directed away from the top of the cut and the reclaimed fill slopes. Surface drainage may be taken across the reclaimed surfaces as long as the flows aze confined to properly designed drainageways. 2) The topsoil removed from the excavations and stockpiled at the site should be spread out evenly across the finished slopes shonly after they have reached the desired grades. Based on .a final slope configuration of 3(horizontal) to ](vertical), we recommend that the topsoil layer be no greater than 4 inches in thickness. The depth of replaced topsoil can be greater for flatter slope configurations. • Job No. 004304 Northwesr Colorado Cortcultancc, Inc. Page 6