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<br />cables are to be installed parallel in the same trench. Unless <br />otherwise specified in the plan, all cables in the same location and <br />running in the same general direction shall be installed i,n ,the same <br />trench. ' .. '.- .H. <br /> <br />When rock excavati on is encountered, the rock sha 11 be removed to <br />a depth of at least 3 inches below the required cable depth and it <br />shall be replaced with bedding material of earth or sand containing no <br />mineral aggregate particles that would be retained on a 1/4 inch <br />sieve. The Contractor shall ascertain the type of soil or rock to be <br />excavated before bidding. All excavated shall be unclassified. <br /> <br />3.4 Installation in Trenches. The Contractor shall not use a cable <br />plow for installing the cable. Mechanical cable laying equipment may <br />be used in conjunction with a trenching machine if specified on project <br />plans and specifications: and it should provide for physical <br />inspection of cable prior to backfilling. Sharp bends or kinks in the <br />cable shall not be permitted. <br /> <br />Cables shall be unreeled in place alongside or in the trench and <br />shall be placed along the bottom of the trench. The cable shall not be <br />unreeled and pulled into the trench from one end. <br /> <br />Where two or more cables are laid parallel in the same trench, <br />they shall be placed laterally a minimum distance of 3 inches apart, <br />and the trench shall be widened sufficiently to accomplish this. <br /> <br />Cables crossing over each other shall have a minimum required <br />depth below finish grade. <br /> <br />Not less than one foot of cable slack shall be left on each side <br />of all connection, insulating transformers, light units, and at all <br />other points where cable is connected to field equipment. The slack <br />cable shall be placed in the trench in a series of S curves. <br />Additional slack cable shall be left in runway light bases, handholes, <br />manholes, etc., where it is required to bring the cable above ground <br />level to make connections. The amount of slack cable shall be <br />stipulated by the Engineer, or as shown in the plans and specifications. <br /> <br />3.5 Backfilling. After the cable has been installed, the trench shall <br />be backfilled 3 inches deep, loose measurement, and shall be either <br />earth or sand containing no mineral aggregate particles that would be <br />retained on a 1/4 inch sieve. This layer shall not be compacted. The <br />second layer shall be 5 inches deep, loose measurement, and shall <br />contain no particles that would be retained on a one inch sieve. The <br />remainder of ,the backfill shall be excavated of imported mineral and <br />shall not contain stone or aggregate larger than 4 inches maximum <br />diameter. The third and subsequent layers of the backfill shall not <br />exceed 8 inches in maximum depth, loose measurement. <br /> <br />The second and subsequent 1 ayer shall be thoroughly tamped and <br />compacted to at least the density of the adjacent undisturbed soil and <br />to the satisfaction of the Engineer. If necessary to obtain the <br />