LINE B-2-3 AND B-2-4 - Laserfiche WebLink

13-01 13-02 13-03 13-04 SECTION 13 - TRENCH BACKFILL General: The provisions of this section apply to the backfilling of all ~renchs in conjunction with the proper .installation of underground conduits and appurtenances. Crushed Rock or Gravel: If specified as bedding or if an unexpected condition is discovered which in the opinion of the Engineer requires the use of crushed rock or gravel, the Contractor shall over-excavate to a depth specified by the Engineer and backfill with crushed rock or gravel. a. Material: Crushed rock or gravel shall be uniformly graded with ~ passing a 1-1/2" sieve and not more than 10% passing a No. 8 sieve and shall be hard, sound, and durable and shall not slake or disintegrate in water. b. Installation: Crushed rock or gravel shall be placed in the trench bottom by any convenient method, taking care to avoid damage to 'the sides of the trench. The crushed rock or gravel surface upon which the conduit i~ to be laid shall be firm, thoroughly compacted and true to grade. Select Backfill: Select backfill materials shall be clean, firm, natural sand or quarry waste. It shall be of such size that 95% to 100% will pass a 1" sieve, 45% to 100% will pass a No. 4 sieve, 10% to 90% will pass a No. 30 sieve, and not more than 10% will pass a No. 200 sieve when tested in accordance with the ASTM Standard Specifications, Serial Designation D422-61T, Tentative Method for Grain-size Analysis of Soils, with subsequent amendments, and none of the material shall be larger than 2-1/2". Representative samples of the select backfill material to be imported shall be submitted in advance of construction operations for testing and approval by the Engineer, and no such material shall be used in the work until it has been approved by the Engineer. The material shall not slake or disintegrage under the action of water, whall have a minimum Sand Equivalent of 25, and shall drain readily after flooding to a relative compaction of not less than that specified on the drawings as determined by the latest revision of Test Method No. California 216 'of the Department of Transportation of the State of California. Backfill: Backfill of trench with corrugated metal pipe shall mean the bac~ in that portion of the trench from the top of the selected backfill material to the ground surface. Backfill of trench with cast-in-place concrete shall mean the full depth of trench. a. Material: Select native excavated material may be used as backfill, only if specifically approved by the Engineer. CDS.1.12 13-1