16 of 49 Construction of Giresun Wastewater Treatment Plant  Tender Dossier Volume 3 Employer’s Requirements  Section 05: Earth Works, Pipe Works and Ground Improvement  5.3.3.6 Gas system  5.3.4 Pipe markers  Natural gas shall be made available by the Contractor for the heating of buildings if required in the  herewith Employer’s Requirements. Gas pipelines shall meet the requirements of local standards and  regulations.  Water, wastewater and surface water pipes, manhole elements and fittings shall be marked either by  carving and painting text or by thermally transferred water resistant paint.  Pipe marks shall have the following information:   The name of the Municipality   The name of the water and sewerage administration   The name of the pipe factory   The pipe class, diameter and production date.  5.3.5 Pipe materials  5.3.5.1 General  Generally all pipes, valves and pipe fittings installed shall conform to the relevant international norms  and standards. The Contractor shall, if required, forward to the Engineer certificates showing that the  materials have been tested and comply with the requirements of this specification and the relevant  standard.  Pipes shall be ordered in the maximum lengths available to minimize the number of joints. The Con- tractor shall be responsible for the supply of all materials in sufficient quantities and shall immediately  prior to placing any order, especially for imported goods, ascertain the required quantities.  In the following is listed the pipe materials that are found appropriate and relevant for installation in  the wastewater treatment plants and pipelines to be constructed and depending on the media to be  transported.  Pipes materials to be used at the plant  Pipes to be used at the plant  Connection pipes between units  :HDPE PE100, GRP (for pipes with diameter > 1600 mm)  Process air  : Stainless steel 1.4404  Drop legs for process air pipes  : Stainless steel 1.4404  Aeration grid pipework below water  : HDPE or PVC Biogas pipes  : Stainless steel 1.4404  Sludge pipes  : HDPE (section outside the buildings)  Sludge pipes  : Stainless steel 1.4404 (section inside the buildings)  Discharge, overflow and drainage pipes  : Corrugated PE, GRP  Service water pipes  : PPRC Sewage pipes inside the buildings : HDPE PE100  5_Vol3_d4.3_Section 5 Earth and pipe works_en_GIR_rev6.docx 