11 of 49 Construction of Giresun Wastewater Treatment Plant  Tender Dossier Volume 3 Employer’s Requirements  Section 05: Earth Works, Pipe Works and Ground Improvement  pneumatic caissons etc. Any such support shall be deemed to be included in the relevant prices for ex- cavations for structures, installation of pipes and cables, etc.  Due to the presence of groundwater and the close vicinity of buildings it is expected that much of the  wastewater pipeline trench excavations shall need to be sheet piled curtain or revetment.  The excavation, pipe connection and then trench filling shall be done in a safe way. Safety and securi- ty measures will be taken. The ditch should not flow, slip, or collapse.  At 1.5 m deep deeper ditches are excavated for safety of life and property.  The decision to make a slope or a revetment economic comparison and job depends on its feasibility  and subject to the Engineer’s approval.  In addition, the trench on the pipe does not slip depending on the slope, soil-holding curtains will be  constructed.  5.2.7.6 Sheeting and Bracing  The Contractor shall be responsible for the design, installation, and maintenance during construction,  and where appropriate, removal of all support works needed for trenches and other excavations. The  Contractor shall submit to the Engineer for approval, details of his proposal for excavation support  which details shall include such Drawings, calculations or other explanatory matter as the Engineer  may require, but such approval shall not relieve the Contractor of his responsibilities under the Con- tract. No excavation work may proceed until the Engineer’s approval has been given to the Contrac- tor’s proposals.  The Contractor shall not remove temporary works supporting the excavations until in the opinion of  the Engineer the Permanent Work is sufficiently advanced to permit such removal which shall be exe- cuted under the personal supervision of a competent foreman. Where the removal of excavation sup- port works is considered by the Engineer to endanger existing structures thus making them liable to  subsidence damage, the Contractor shall leave such support works in place, removing only the mini- mum necessary to allow the reinstatement of the surfaces.  Works for pit sheeting and bracing close to private or public properties, structures and utilities shall be  carried out with low vibration and low concussion.  5.2.7.7 Stripping of topsoil  Topsoil is by definition the top layer of soil that can support vegetation, which shall be retained for  later re-use. Stripping of all topsoil shall be carried out in the immediate areas to be occupied by the works, includ- ing areas of excavation where material from excavation may be used in fill, areas to be occupied by  temporary works, or any other areas as directed by the Engineer. Stripped topsoil shall be stored in a  location agreed with the Engineer and shall not exceed 2 m in height. Stored topsoil shall be kept free  of weeds and grasses.  5.2.8 Preparation of Foundation  The work under this description shall consist of preparing the foundation, which is to be the base for  structures, buildings, roads, pipes etc.  All foundations shall be free of loose material, remolded debris or other deleterious and organic mate- rials, all to the satisfaction of the Engineer.  Any foundation areas shall be well-graded for proper drainage and said grading shall be maintained at  all times.  5_Vol3_d4.3_Section 5 Earth and pipe works_en_GIR_rev6.docx 