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Excavation shall be as described elsewhere in these specificarions and as shown on the drawings. <br />Install foundation and bedding as shown in the drawings and as specified herein, according to <br />conditions in the trench bottom. Provide a firm, stable, and uniform bedding for the pipe barrel <br />and any protruding features of its joint. Provide a minimurn 4 inch thickness of bedding unless a <br />greater thiclrness is specified. <br />When rock or unyielding material is present in the trench bottom, increase the thickness of <br />bedding material to 6 inches minimum. <br />Where the trench bottom is unstable or shows a"quick" tendency, excavate all unstable material <br />as a minimum, and replace with a foundation of material per Table I. Place and compact this <br />foundation material in accordance with the drawings. Control of quick and unstable trench <br />bottom conditions may also be accomplished with the use of appropriate geofabrics applied to <br />the satisfaction of the ENGINEER and in strict accordance with the manufacturer's <br />recommendations. For severe conditions, the ENGINEER may require a special foundation such <br />as piles, sheeting, or concrete mats. Correction of unstable trench bottom shall not result in <br />increased cost to OWNER. <br />Minimize localized loadings and differential settlement wherever the pipe crosses other utilities <br />or subsurface structures. Provide a cushion of bedding material between the pipe and any such <br />point of localized loading. <br />If the trench bottom is excavated below intended grade, fill the over-excavation with compatible <br />foundation or bedding material and compact to a density not less than the minimum densities <br />given in the drawings. <br />If trench sidewalls slough off during any part of excavating or installing the pipe, remove all <br />sloughed and loose material from the trench. <br />All pipe line excavation made in one day shall have the pipe installed and backfilled the same <br />day. Excavation of trench days ahead of pipe laying will not be peimitted. <br />Excavations for pipe line appurtenances shall be backfilled as soon as is feasible. <br />Place pipe and fittings in the trench with the invert conforming to the required elevations, slopes, <br />and alignment. Ensure uniform pipe support. In special cases where the pipe is to be installed to <br />a curved alignment, maintain angular joint deflection or pipe bending radius, or both, as <br />indicated in the drawings. <br />Adjustment in grade shall be made by scraping away or filling in along the full length of the pipe <br />with approved bedding material, properly compacted, and not by wedging, blocking up the <br />conduit, or supporting the conduit on mounds of earth. <br />The width of trench excavation is set forth in the drawings and sha11 not be exceeded in the area <br />from the bottom of the trench to a point 12" above the top of the pipe. <br />81 <br />