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D. The alignments and excavation lines shown on the Drawings are subject to such changes <br />as may be found necessary by the Engineer to adapt the liner foundation excavation and <br />other features to the conditions disclosed by the excavation. <br />E. Accurate trimming of the slopes of the excavation will be required, and the excavation <br />shall conform to the established lines and grades. Loose rock shall be removed from <br />foundation contacts. <br />F. Foundation irregularities shall be reduced as determined by the Engineer to provide <br />satisfactory foundation contours. Any irregularities found in the liner foundation area, <br />including sandstone or carbonaceous materials, shall be overexcavated and removed to a <br />minimum depth of 3 feet and beyond the limits of the irregularity a minimum of 10 feet. <br />Suitable Zone I material shall be placed and compacted in the removal area to provide an <br />impermeable seal on the foundation surface. <br />3.6 STRIPPING FOR FOUNDATION OF LINER EMBANKMENT <br />As provided in Section 31 10 00, areas where liner embankment material is to be placed shall <br />first be stripped in accordance with the Drawings, these Specifications, and to the satisfaction of <br />the Engineer. <br />3.7 EXCAVATION BELOW STRIPPING FOR KEY TRENCH <br />The key trench shall be excavated in the liner embankment foundation to, at a minimum, the <br />lines and grades shown on the Drawings. The key trench shall be excavated to sound rock or to <br />firm material to the satisfaction of Engineer. Sound rock or firm material shall be determined <br />visually by the Engineer and shall be primarily claystone bedrock that appears uniform and <br />excavates in a relatively uniform manner. The material shall be non - yielding to rubber tire <br />pressure from scrapers and shall require a rock hammer to break it apart. The initial excavations <br />shall be observed by an engineer experienced with dam embankment construction or similar <br />bedrock material. All loose, soft, or deleterious material shall be removed from the rock surface <br />and pockets and depressions to the satisfaction of the Engineer. Special considerations are <br />required for the last 2 feet of excavation to reduce the potential of damaging the bedrock surface. <br />The last 2 feet of excavation shall be conducted with rubber tired equipment. <br />3.8 EXCAVATION BELOW STRIPPING OUTSIDE KEY TRENCH <br />Other areas of the liner embankment foundation where shown on the Drawings shall be <br />excavated to sound rock or to an otherwise suitable foundation to the satisfaction of the <br />Engineer. The last 2 feet of excavation shall be conducted with rubber tired equipment. <br />3.9 PROTECTION OF FOUNDATION MATERIALS <br />Liner foundation materials exposed during excavation for the liner embankment foundation and <br />the key trench, shall be protected from freezing and surface drying in accordance with the <br />requirements of Section 3123 23. <br />END OF SECTION <br />NCCI Pit #1 Reservoir Liner - Technical Specifications Excavation <br />312316 -5 <br />