17 of 74  Construction of Giresun Wastewater Treatment Plant  Tender Dossier Volume 3 Employer’s Requirements  Section 3: Plant Description  Contractor shall be in accordance with the specifications given in Section 7.8.25. The screening press  and perforated screens shall be cleaned with hot water (minimum 60$^{0}$C). The screen building shall  contain one squatting wastewater closet, one urinal bowl and one sink.  The screens shall be made from stainless steel 1.4404 in order to prevent corrosion.  The cleaning mechanisms of the fine screens shall be automatically operated by water level sensors  (ultrasonic level or radar type sensor) located upstream and downstream of the screens (level  difference). In addition to this, the cleaning mechanisms for the fine screens shall be operated by time  intervals. Time intervals must be adjustable from the SCADA. An area to be used for container station with sufficient service water taps shall be provided for  handling and washing the containers. Water used for cleaning purposes of containers shall be properly  gathered from the bottom drainage pipe and should be conveyed to the inlet pumping station.  The fine screens, with their screening containers, screening press and conveyors shall be located in a  building with frost-free conditions. . The requirements for the drainage, foul air collection and clean  water supply system stated in Section 3.3.4.34 and 3.3.4.35 should be met for the building inner area. The fine screens shall be locally controlled and operate as autonomous units. The operation status,  however, should be monitored and controlled by the SCADA system. Furthermore, water levels in  front of and behind the fine screens should be monitored from SCADA.  Details of the fine screens are:  Fine screens: 3.3.4.5 Grit and Grease Removal Tanks  Minimum number of fine screen channel for Stage 2  : 3 channels + 1 spare channel (with all  equipped)  Maximum bar aperture  : 6 mm  Maximum velocity through hole at maximum flow  : 1.0 m/s (in the case of 50% clogging)  Minimum storage capacity and type container  : in accordance with 7.8.29.  Minimum number of the containers  : 3 items After the inlet pumping station or fine screen (as the case may be), the wastewater shall flow to  combined aerated grit chambers and grease removal tanks. Aerated grit and grease removal tanks shall be designed, constructed and equipped regarding the  requirements set in Table 2-1. The maximum flow (Q$_{WW;h}$) of the related stage requirements shall be  met for the unit. The grit chamber and grease removal tanks shall be constructed as rectangular concrete structures.  Length/Width ratio of the grit and grease removal unit (only grit section) shall be minimum 10.  A diffuser system for the creation of coarse bubbles shall be mounted on the wall over the grit  hoppers. The diffuser in grit chamber proposed by the Contractor shall be in accordance with the  3_Vol3_d4.3_Section 3_Plant Description_GIR_rev08 