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the number 200 sieve. The rockfill should have awell-graded grain <br />• size distribution and length of individual particles should not exceed <br />three times the width. <br />Western Fuels proposes using waste rock comprised of sandstone <br />generated during mining. We believe this rock type is suitable for the <br />proposed structure as long as the gradations listed above are adhered to <br />during construction. We anticipate that some mechanical breakdown <br />will occur during handling. Modification of blasting patterns presently <br />being used may be necessary in order optimize the gradation of the <br />rockfill material. <br />3.3 CONSTRUCTION PROCEDURES <br /> <br />I• <br />The fill shall be maintained approximately horizontal throughout the <br />entire length. Rockfill material shall be dumped so as to provide the <br />best practical distribution of the material. The material shall be <br />dumped on top of the loose lift being constructed and spread to the <br />edge of the lift using a bulldozer or other bladed equipment. Material <br />should be spread across the loose lifr so as to fill the voids with the <br />finer material in the rockfill. The loose lift should have a relatively <br />smooth surface without large protruding rocks so effective compaction <br />can be achieved. Larger rocks should be pushed towards the outer <br />slope and oversized rocks should be pushed completely to the edges of <br />the fill. Water shall be added generously to assist with compaction of <br />the fill. The amount of water used should be at least 20% of the <br />volume of rock. <br />If the 90-ton haul trucks are used for compaction, rockfill shall be <br />placed in horizontal layers (lifts) not exceeding 18 inches in thickness. <br />If compaction is to be achieved using a vibratory steel drum roller with <br />a minimum static weight of 10 tons, lift thicknesses can be increased to <br />24 inches using the same procedures as outlined above. Lift thickness <br />may be varied once construction begins with the approval of a represen- <br />tative of our firm. A minimum of four compaction passes covering the <br />entire lift shall be completed, each pass overlapping a minimum of 1 <br />foot. More passes may be required at the request of our on-site <br />observer. <br />4 <br />