(A) General.
(1) Excavation work shall be performed in a safe and proper manner with suitable precautions being taken against all hazards. Excavation work shall be performed in accordance with all applicable provisions of the OSHA standards for excavation safety.
(2) Excavations shall provide adequate working space and clearance for the work to be performed, including for the installation and removal of concrete forms.
(3) In no case shall excavation faces be undercut for extended footings.
(4) Subgrade surfaces shall be clean and free of loose material of any kind when concrete is placed thereon.
(5) All suitable excavated material meeting the requirements of general fill may be used as backfill or in the formation of embankments or engineered fill. All unsuitable material shall be removed from the site unless otherwise allowed by the town. Stockpiles shall be graded and shaped for proper drainage and shall be protected from erosion.
(B) Underground utilities. Utilities shall be located in areas of work prior to the commencement of work. If utilities are to remain in place, then adequate means of support and protection during earthwork operations shall be provided. Should unknown or unidentified piping or other utilities be encountered during excavation, the contractor shall consult the applicable utilities immediately for directions. The contractor shall cooperate with the town and other utility companies in keeping respective services and facilities in operation. The contractor shall repair damaged utilities, both known and unknown, to the satisfaction of the town utility owner.
(C) Sheeting and shoring. Except where banks are cut back on a stable slope, an excavation for structures and trenches shall be properly sheeted, braced and shored as necessary to prevent caving or sliding and to provide protection for workers and the work. Sheeting, bracing and shoring shall be designed and built to withstand all loads which might be caused by earth movement or pressure and shall be rigid, maintaining its shape and position under all circumstances. Sheeting and shoring shall comply with all applicable requirements of the OSHA standards for excavation.
(D) Unsuitable bearing material. Materials encountered at design elevations which are considered inadequate for suitable bearing shall be removed and replaced. The removal shall be to a depth as required to reach suitable bearing material. Fill material shall consist of either structural backfill or concrete.
(E) Subgrade stabilization.
(1) Subgrades for concrete structures shall be firm, dense and thoroughly compacted and consolidated, shall be free from mud, shall be sufficiently stable so as to remain firm and intact under the feet of workers and shall be reinforced with crushed stone or gravel per the structure’s details.
(2) Subgrades for concrete structures which are otherwise solid but become mucky on top due to construction operations shall be reinforced with crushed stone or gravel.
(F) Dewatering.
(1) The contractor shall provide and maintain adequate dewatering equipment to remove and dispose of all surface water and groundwater entering excavations, trenches or other parts of the work. Each excavation shall be kept dry during subgrade preparation and continually thereafter until the structure to be built or the pipe to be installed therein is completed to the extent that no damage from hydrostatic pressure, flotation or other cause will result.
(2) All excavations which extend down to or below the static groundwater elevation shall be dewatered by lowering and maintaining the groundwater surface beneath such excavations a distance of not less than 12 inches throughout the time the excavation remains open.
(3) Surface water shall be diverted or otherwise prevented from entering excavated areas or trenches to the greatest extent practicable without causing damage to adjacent property.
(4) Water shall be disposed of in such a manner as will not cause injury to public or private property nor be a nuisance or menace to the public. The contractor shall be responsible for any and all permits and approvals thereof necessary for disposal of the water.
(Ord. 2010-3, passed 10-6-2010)