(A) General. All excavation shall be made in a manner and to the widths as will give ample room for properly constructing and inspecting the structures they are to contain and for the sheeting, timbering, pumping and draining as may be required within the limits shown in Standard NPW-2. Except where otherwise specified, excavation slopes shall be flat enough to avoid slides that will cause disturbance of the subgrade or damage to adjacent areas, intercept and collect surface runoff both at the top and bottom of cut slopes. All excess excavated material and all excavated material which is unsuitable shall be removed from the site and replaced with suitable material.
(B) Sheeting and bracing. Place and maintain the sheeting and bracing as may be required to support the sides of the excavation or to protect pipes and structures from possible damage and to provide safe working conditions. The contractor shall be responsible for the adequacy of all sheeting and bracing used and for all damage resulting from sheeting and bracing failure or from placing, maintaining and removing it. All sheeting and bracing shall be removed upon completion of work. The town may permit sheeting to be left in place at the request and expense of others for the purpose of preventing injury to structures or property. Any sheeting or bracing left in place shall be cut off at least two feet below the finished ground surface.
(C) Rock excavation. All rock encountered within the limits of excavation shall be excavated. Rock shall be excavated so that generally there will be a clear space of at least 12 inches from the outside barrel of the pipe to the side of the trench. Isolated points of rock shall not come nearer than six inches to the pipe. At the trench bottom, the rock shall not come nearer than six inches to the pipe. In addition, sufficient rock shall be removed at joints to facilitate proper installation. Rock shall be fully removed at least 15 feet in advance of the laying of the pipe.
(D) Protection of subgrade for all excavations. To minimize the disturbance of the bearing materials and provide a firm foundation.
(1) Excavation shall be carried out below subgrade in limited areas, should disturbed soil or material with natural low bearing capacity be encountered. Stabilizing of these areas shall be done with select backfill or coarse aggregate as required. Soils disturbed through the operations shall be excavated and replaced with select backfill or coarse aggregate, as required.
(2) Provide positive protection against penetration of frost into materials below the bearing level during work in winter months.
(Ord. passed 6-21-2011)