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203.08 Embankment Construction Embankment construction shall consist of constructing the dam embankments, including preparation of the areas upon which they are to be placed; the placing and compacting of approved material within roadway areas where unsuitable material has been removed; and the placing and compacting of embankment material in holes, pits and other depressions within the dam area. Only approved materials shall be used in the construction of em- bankments and'backfills. Free running water shall be drained from the material before the material is placed on the dam. The type of relative compaction required shall be as called for on the plans or as designated. When embankment is to be placed and compacted on hillsides, or when new embankment is to be compacted against existing embankments, or when em- bankment is built 1/2 width at a time, the slopes .that are steeper than 4:1 when measured longitudinally or at right angles to the dam shall be continuously benched over those areas where it is required as the. work is brought up in layers. Benching shall be well keyed and where practical, a minimum of 8 feet wide. Each horizontal cut shall begin at the inter- section of the original ground and the vertical sides of the previous cuts. Material thus cut out shall be recompacted along with the new em- bankment material at the Contractor's expense. Where embankment is to be placed and compacted and end dumping is per- " witted, the slopes of the original ground or embankment shall be deeply plowed or cut into before starting end dumping. Unless shown otherwise on the plans or special provisions, where an em- bankment of less than 4 feet above subgrade is to be made, all sod and vegetable matter shall be removed for the surface upon which the embank- ment is to be placed, and the cleared surface shall be completely broken .up by plowing, scarifying or stepping to a minimum depth of 6 inches. This area shall then be recompacted. Sod not required to be removed shall be thoroughly disked before construction of embankment. Dam embankment of earth material shall be placed in horizontal layers not exceeding 8 inches (loose measurement) and shall be compacted as spec if iced before the next layer is placed. Effective spreading equipment shall be used on each lift to obtain uniform thickness prior to compacting. As the compaction of each layer progresses, continuous leveling and man- ipulating will be required to assure uniform density. Water shall be uniformly added or removed if necessary, in order to obtain L-lie required density. When the excavated material consists predominately of rock too large to be placed in 8 inch layers, the Engineer may permit the material to be placed in thicknesses up to the average rock dimension, but not to exceed 3 feet. Placing of occasional boulders of sizes larger than the maximum