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Section 02210 <br /> EXCAVATION,BACKFILLING,AND COMPACTION FOR UTILITIES <br /> C. Granular Pipe Bedding <br /> A dense, well-graded aggregate mixture of sand, gravel, or crushed stone (mixed <br /> individually, in combination with each other, or with on-site soil) placed on a subgrade to <br /> provide a suitable foundation for pipe. Granular bedding material may also consist of <br /> poorly graded sands or gravels where fast draining soil characteristics are desired. <br /> D. Unyielding Material <br /> Rock, rib, ridge, :rock protrusion, or solid with cobbles in the trench bottom requiring a <br /> covering of finer grain material or special bedding to avoid bridging in the pipe or conduit. <br /> E. Unstable Material <br /> Material in the trench bottom which lacks firmness to maintain alignment and prevent <br /> joints from separating in the pipe, conduit, or appurtenant structure during backfilling. This <br /> may be material otherwise identified as satisfactory which has been disturbed or saturated. <br /> F. Lift <br /> A layer or course of soil placed on top of unprepared subgrade or a previously prepared or <br /> placed soil in a fill or backfill. <br /> G. Rock <br /> Rock is defined as any material which cannot be excavated with a track mounted 235 <br /> Caterpillar backhoe with a narrow bucket, and teeth, and requires the use of special <br /> buckets, rock teeth,jack-hammering, blasting and/or other special methods of excavation. <br /> H. Unsatisfactory Material <br /> Soil or other material identified as having insufficient strength or stability to carry intended <br /> loads on trench backfills without excessive consolidation or loss of stability. Also backfill <br /> material which contains refuse, frozen material, large rocks, debris and other material <br /> which could damage the pipe or cause the backfill not to compact. As a minimum, <br /> materials classified as PT, OH, or OL by ASTM D2487 are unsatisfactory. <br /> L Intermediate Backfill <br /> Backfill from 12 in. above pipe to limits as shown. <br /> J. Crushed Rock <br /> Manufactured crushed stone with at least 3 angular faces. <br /> Walnut Grove Sewer Project (Conformed) 02210-3 SA0160401 <br /> March 2008 n:Asa0160401\specs\wd conform\div 2\02210.doc <br />