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KLEINFELDER D. A motorized pug mill mixer capable of injecting water into the mixing chamber at a controlled rate (CAT RR-250 Soil Stabilizer, or approved equal) shall be used to initially break the 20 percent imported Ione clay clods and to mix the soil. .The mixer shall have a minimum mixing depth of 16 inches and shall be equipped with"bullet" cutting teeth. The mixing chamber shall be set to a depth of approximately 4 inches and the mixing bar shall rotate at a minimum speed of 160 rpm. A minimum of two passes (premixing) shall be made with the mixer without adding any moisture to break the 20 percent imported Ione clay clods. Premixing shall continue until a maximum of 10 percent is retained on a 3/4- inch sieve. Cobbles and cemented particles larger than 1-1/2 inches, and foreign material, shall be removed by the Contractor. E. The mixing chamber shall be set to a depth adequate to mix the 13-inch onsite selected soil layer with the 3-inch 20 percent imported Ione clay layer. Caution should be taken as not to mix the material with the foundation layer. A minimum of two passes shall be made with the mixer without adding any moisture to mix the 20 percent imported lone clay with the 80 percent onsite selected soil. The mixing bar shall rotate at a minimum speed of 160 rpm. F. A minimum of two additional passes shall be made with the mixer, in which moisture shall be uniformly added by injecting water into the mixing chamber. The prepared mixture shall be brought to a moisture content of 2 percent above optimum prior to the start of compaction. Mixing shall continue until a minimum of 98 percent of the mixed material passes the I- inch sieve and a minimum of 60 percent passes the No. 4 sieve, and the moisture content of the mixture is uniform. The Contractor shall not begin any compaction of the clay barrier layer until the Engineer approves the mixing of the layer. G. The clay barrier layer shall be compacted in 2 lifts of approximate equal thickness. Each lift shall be compacted to obtain a minimum relative compaction of 95 percent (ASTM D- 1557). Compaction shall be performed using a Caterpillar 825C sheep's foot compactor or approved equal. The finished surface of the clay barrier layer shall not be below the grade established by the Engineer, nor shall it be more than 0.15-foot above the grade. The measurements shall be taken from the bottom of the sheep's foot indentions. H. Areas which are not accessible to heavy construction equipment shall contain 35 percent import Ione clay and 65 percent onsite selected soil for the clay barrier layer. These areas are also required to meet all specifications as contained herein, except that the soils shall be mixed at a convenient location. These areas shall be compacted by any method, approved by the Engineer, which will produce a minimum relative compaction of 90 percent. Because of the consequences of having the barrier layer fail the CIWMB and RWQCB regulations, it is important that the evaluation of the clay spread be conservative. is GSM.-MD 3EI94 Page 17 of 24 Copyright 1994 Kleinfelder,Inc.