Specifications - Laserfiche WebLink

Home Browse Search

1 1 � , os 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 07/06 and bracing to prevent any caving or moving of the ground. DEWATERING, DRAINAGE AND FLOATATION A. The Contractor shall construct and place all drainage piping, structural fill and bedding rock, in- the -dry. In addition, the Contractor shall make the final 24 inches of excavation for this work in- the -dry and not until the water level is a minimum of twelve inches below proposed bottom of excavation. B. The Contractor shall, at all times during construction, provide and maintain proper equipment and facilities to remove promptly and dispose of properly all water entering excavations and keep such excavations dry so as to obtain a satisfactory undisturbed subgrade foundation condition until the fill and structure to be built thereon have been completed to such extent that they will not be floated or otherwise damaged by allowing water levels to return to natural elevations. C. Dewatering shall at all times be conducted in such a manner as to preserve the natural undisturbed bearing capacity of the subgrade soils at proposed bottom of excavation. D. Wellpoints may be required for predrainage of the soils prior to final excavation for some of the deeper in- ground structures, and for maintaining the lowered groundwater level until construction has been completed to such an extent that the structure or fill will not be floated or otherwise damaged. Wellpoints shall be surrounded by suitable filter sand and no fines shall be removed by pumping. Pumping from wellpoints shall be continuous and standby pumps shall be provided. E. The Contractor shall furnish all materials, permits and equipment and perform all work required to install and maintain the drainage systems he proposes for handling groundwater and surface water encountered during construction of structures and compacted fills. F. If requested by the Engineer, the Contractor's proposed method of dewatering shall include a groundwater observation well at each structure to be used to determine the water level during construction of the structure. Locations of the observation wells shall be at structures as approved by the Engineer prior to their installation. The observation wells shall be extended to 6 inches above finished grade, capped with screw -on caps protected by 24" x 24" wide concrete base, and left in place at the completion of this Project. G. Prior to excavation, the Contractor shall submit his proposed method of dewatering and maintaining dry conditions to the Engineer for approval. However, such approval shall not relieve the Contractor of the 02221 -3 05 -5564