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TRENCHING & BACKFILL 02 2020-6 <br />project will be accepted for consideration as follows. The amount of <br />material passing a #200 sieve shall not exceed 12% and no plastic fines <br />shall be present. <br />3. Mix Proportions <br />a. CDF shall be a mixture of cement, Class F pozzolan, aggregate, air <br />entraining agent and water. CDF shall be batched by a ready mixed <br />concrete plant and delivered to the job site by means of transit mixing <br />trucks except for <br />b. The actual mix proportions shall be determined by the producer of the <br />controlled density fill to meet job site conditions, minimum and maximum <br />strengths, and unit weight. Entrained air content shall be a minimum of <br />4.0%. The actual entrained air content shall be established for each job <br />with the materials and aggregates to be used to meet the placing and unit <br />weight requirements. Entrained air content may be as high as 20% for <br />fluidity requirements. <br />4. Mix Design <br />a. Mix design shall meet the Engineer's approval. <br />PART 3 - EXECUTION <br />3.01 GENERAL TRENCHING AND EXCAVATING <br />A. Trenches may be excavated either by hand, or mechanically. Trenches shall be <br />cut with vertical sides, and shall be of sufficient width to provide adequate space <br />for working therein; such space shall be a minimum clear distance of six (6) <br />inches of shoring and a maximum of nine (9) inches clear of shoring on each side <br />of the pipe barrel when the pipe is properly placed and aligned in conformity with <br />the plans. Glory hole excavation or vee trenches will not be allowed. Trench <br />sides shall be parallel to and at equal distance from the center-line of the pipe, <br />when aligned in conformity with the plans. <br />B. Excavated material shall be loaded into trucks immediately upon removal from <br />the trench to prevent stockpiling on roadways or walkways. <br />C. Where the excavated trench exceeds the widths specified above, furnish higher <br />strength pipe, or other methods of construction as approved by the Engineer, to <br />adequately provide for the increased loading, which the trench widening will <br />cause. Stepped trenches shall meet the approval of the Engineer. <br />D. Pipe trenches shall be excavated to a depth below the bottom of the pipe <br />sufficient to provide for pipe bedding materials as required by Section 3.02. <br />E. Where a trench has been excavated below the designed grade, the bottom of the <br />trench shall be refilled to proper subgrade with approved material well compacted <br />in place, in an approved manner.