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SECTION 02223 <br /> EXCAVATION BELOW NORMAL GRADE AND GRAVEL REFILL <br /> PART 1 -GENERAL <br /> 1.01 SCOPE OF WORK <br /> A. If in the opinion of the Engineer, the material at or below the normal grade of the <br /> bottom of the trench (0.7 feet below the invert of the pipe) is unsuitable for <br /> foundation, it shall be removed to the depth directed by the Engineer and replaced <br /> by drain rock, as specified in Section 02221 - Trenching, Bedding, and Backfill for <br /> Pipe. <br /> B. It shall be the Contractor's responsibility to provide trench safety systems such as <br /> sheeting and bracing in accordance with state and local regulations. <br /> 1.02 RELATED WORK <br /> A. Section 02221: Trenching, Bedding and Backfill for Pipe. <br /> PART 2 - PRODUCTS <br /> 2.01 MATERIALS <br /> A. Drain rock shall be 3/4 inch washed and graded limerock. The rock shall be graded <br /> so that 99% will pass a 3/4 inch screen and 80% will be retained on a No. 8 screen. <br /> Material meeting the Florida Department of Transportation Standard Specifications <br /> for No. 57 stone shall be acceptable. <br /> PART 3 - EXECUTION <br /> 3.01 EXCAVATION AND DRAINAGE <br /> A. Whatever the nature of unstable material encountered or the groundwater <br /> conditions, trench drainage shall be complete and effective. <br /> B. If the Contractor excavates below grade through error or for his own convenience, or <br /> through failure to property dewater the trench, or disturbs the sub-grade before <br /> dewatering is sufficiently complete, he may be directed by the Engineer to excavate <br /> below grade as set forth in the preceding paragraph, in which case the work of <br /> excavating below grade and finishing and placing the refill shall be performed at his <br /> own expense. <br /> 3.02 REFILL <br /> A. If the material at the level of trench bottom consists of fine sand or sand and silt <br /> which may work into the drain rock prohibiting effective drainage, the sub-grade <br /> material shall be removed to the extent directed and the excavation refilled with <br /> coarse sand, or a mixture graded from coarse sand to fine pea-stone, to form a filter <br /> layer preserving the voids in the gravel bed of the pipe. The composition and <br /> 08/12 02223-1 11-4179 <br />