5 of 74  Construction of Giresun Wastewater Treatment Plant  Tender Dossier Volume 3 Employer’s Requirements  Section 3: Plant Description  3 Plant Description  3.1 Layout Considerations  Giresun Municipality stated that approximately 2.2 ha area in Batlama region was determined as  wastewater treatment plant area. Existing elevations of plant area change between 5.00 and 25.00 m.  The available surface area is approximately 2.2 ha. The required head of the pumps shall be determined according to the BOPEL (bottom elevation of  pipeline) of the main collector with 1000 mm diameter as -1.94 masl and the WWTP inlet structure  water level. The WWTP inlet structure water level is calculated by taking account the head loss  through the treatment plant and the site elevation. In order to provide gravitational transmission between the units in the plant, it is necessary to apply  pumping at the inlet. Wastewater taken from the new collector to be built within the other Work  Contract in the scope of the IPA packages is designed to be ended in the inlet structure to be  constructed in the WWTP site. Site elevation changes between 5-25 m in that part and approximately 2 ha part remains in the flat  area. The retaining wall shall be constructedin order to maintain safety both during construction and  operation of the plant. The approximate required length of the retaining is 300 m length which is  shown on the conceptual design general layout drawing given in Volume 5.  A conceptual layout of the proposed wastewater treatment plant is presented in Volume 5.  This layout  is given just for information purpose. The layout to be implemented by the Contractor shall be  the responsibility of him. The tenderer is free to design and location of all units targeting the  optimization of the construction and operational works. There is very high topographic slope at the south-west part of the plant area. In order to increase  stability and work-labor safety in this area; the geotechnical precautions such as floor nails, steel  mesh, retaining walls, shotcrete etc. are recommended as a result of the geotechnical survey. The  methodology of excavation and the geotechnical precautions are subject to the Engineer’s approval.  The Contractor shall prepare the methodology of excavation, the plant units excavation application  projects-geotechnical projects and preparation of required excavation as stated in the methodology of  excavation.These projects are subject to the Engineer’s approval. All structure design and construction shall be appropriate to the limited plant area. The compact units  shall be designed regarding both constructional and operational phase.  Tanks and other process structures shall be constructed in accordance with the hydraulic profile  avoiding any unnecessary pumping in the process. Pipes shall either be buried or located inside  buildings and tanks or be arranged in a way that does not disfigure the desired neutral appearance of  the plant. Moreover, to the extent possible, all equipment shall be installed in buildings for aesthetical  reasons and to reduce noise to a minimum. Specific requirements for structures, buildings, architecture  and landscaping are also given in the Employer’s Requirements, Sections 9 and 10.  3_Vol3_d4.3_Section 3_Plant Description_GIR_rev08 