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1 SECTION 02221 <br /> s UTILITY TRENCHING & BACKFILLING <br /> 4 <br /> s <br /> 6 PART 1 : GENERAL <br /> 7 <br /> 8 1.01 DESCRIPTION <br /> s <br /> 10 The work of this section consists of trenching and backfilling for the construction an <br /> 11 installation of pipelines, conduits and cables. All trenching will be open cut. It includes <br /> 12 all clearing and grubbing, drilling and blasting, construction of cribbing and cofferdams, <br /> 13 dewatering, incidental work, and providing specified backfill. <br /> 14 <br /> 15 1.02 DEFINITION <br /> 1s <br /> 17 Materials used in backfill, as shown in trench details, are defined as follows: <br /> 18 <br /> 19 A. Bedding (BD): When rock, unstable material or wet trench is encountered at the excavated <br /> 20 grade for utility installation, bedding is required. Materials shall be predominantly sand and <br /> 21 gravel, having a plasticity index less than 6. Bedding may be omitted if, in the opinion of <br /> 22 the Engineer, the excavated trench bottom will adequately support and not damage the <br /> 23 utility line. <br /> 24 <br /> 25 1. BD-1: Gradation as follows: <br /> 2s <br /> 27 Sieve size Percent Passing <br /> 28 <br /> 29 No. 4 100 <br /> 30 No. 8 55 - 80 <br /> 31 No. 40 15 - 30 <br /> 32 <br /> 33 2. BD-2: Gradation as follows: <br /> 34 <br /> 35 Sieve Size Percent Passing <br /> 36 <br /> 37 1/2-inch 100 <br /> 38 No. 4 50 - 80 <br /> 39 No. 40 10 - 25 <br /> 40 <br /> 41 3. BD-3: Gradation as follows: <br /> 42 <br /> 43 Sieve Size Percent Passing <br /> 44 <br /> 45 1-1/2-inch 100 <br /> 46 1/2-inch 45 - 75 <br /> 47 No. 40 5 - 15 <br /> UTILITY TRENCHING & BACKFILLING <br /> 042894 02221-1 <br />