12 of 49 Construction of Giresun Wastewater Treatment Plant  Tender Dossier Volume 3 Employer’s Requirements  Section 05: Earth Works, Pipe Works and Ground Improvement  Foundations, except where limited by structures, which are to receive fill or structures shall be scari- fied and loosened by means of a disc harrow or plough or other approved methods to a depth of no  more than 200 mm unless such loosening is not needed in the opinion of the Engineer. Scarifying shall  be done approximately parallel to the center line of the fill.  If any unsound material occurs in the bottom of any excavation, the Contractor shall remove it and  dispose it all to the satisfaction of the Engineer. Unless otherwise specified or ordered by the Engineer,  the Contractor shall fill the voids so formed with concrete grade C15 or with suitable granular material  to the approval of the Engineer.  After removal of all unsuitable materials, the entire foundation area shall be graded, moisture condi- tioned and thoroughly compacted to the required compaction degree.  The period between completion of preparation of foundation and the construction of the overlaying  works shall be kept as short as possible.  Fill material shall not contain roots, frozen material, organic or otherwise unsuitable materials.  No fill material shall be placed in any of the permanent works until its foundation has been prepared as  specified.  Fill materials shall be handled, placed, spread and compacted in such a manner as to avoid segregation  of the fill and to obtain a stable, homogeneous compacted structure.  When organizing his work, the Contractor shall take due account of the climatic conditions, which  may be expected in the area. In case the placed material by any cause become unacceptable, the Con- tractor shall remove such material or shall process it until all specifications are met. Such work shall  be performed at no additional cost to the Employer.  Unless otherwise specified or approved, the material used for backfill and fill shall be excavated mate- rial of particle size not exceeding 75 mm.  Backfill against the permanent works shall be selected, and free from boulders, cobbles, rock frag- ments and the like greater than 50 mm nominal size.  Imported fill materials shall comprise the following materials all in accordance with the relevant  norms:  Where fill will be used below structures and building floors, the material shall consist of durable grav- el, broken stone, crushed concrete or sand with a particle size not exceeding 10 mm. The grading of  the material shall be such that there is no migration of fines into the fill.  The natural ground over which filling is to be placed shall be cleared of all loose boulders, grass, pro- ductive soil, mud, bushes, trees, roots, other vegetation and other unsuitable material.  Unless otherwise specified, fill shall be spread by machine or manually in successive horizontal layers  of not more than 200 mm loose depth and compacted to 95% Standard Proctor.  5.2.9.2 Placing and Compaction of Fill and Backfill   Sand in fraction 0.1-2 mm;  Gravel in fraction 2-75 mm; and   Boulders in fraction 75-100 mm.  5.2.9.1 Fill Materials in General  5.2.9 Backfilling and filling  5_Vol3_d4.3_Section 5 Earth and pipe works_en_GIR_rev6.docx 