19 of 74  Construction of Giresun Wastewater Treatment Plant  Tender Dossier Volume 3 Employer’s Requirements  Section 3: Plant Description  For emergency situations, a bypass line at downstream of the grit and grease removal tanks shall be  provided and this line shall be connected to treated effluent discharge line. The bypass of this unit  shall be controlled by means of the weir type penstock. Overflow penstock shall be channel type weir  penstock with double spindle and fully watertight. It shall be proportioning and electrically driven  actuators. The width of the overflow weir shall be designed and constructed by considering the second  stage maximum flow rate. The hydraulic height of the overflow penstock shall be adjusted by  considering the first stage maximum flow rate. Therefore, this unit shall work as bypass when this  penstock is open, otherwise it shall work as overflow. Operation of the penstocks shall be controlled  by the ultrasonic level sensor.  Outlet channel of grit and grease removal tank shall be designed the following scenarios:  i) Wastewater should be transferred to primary clarifiers at normal operational conditions  ii) If primary clarifiers are out of operation, wastewater shall be directly transferred to  biological treatment units.  iii) If primary clarifiers and biological treatment units are out of operation, the whole amount  of the incoming wastewater shall be directly by-passed.  The drainage pit shall be designed and constructed on the bottom of each grit removal tank. This  drainage pit shall be equipped with the drainage valve that is extended spindle and manual operated.  Minimum number of grit&grease removal tank for Stage 2  : 2 tanks  Minimum retention time at maximum flow  : 5 minutes  Minimum storage capacity and type container  : in accordance with 7.8.29  Minimum number of the containers  : 3 items  Minimum number of grit classifiers  : 2 units  No load reduction in screens and grit and grease removal tanks shall be taken into consideration in the  design of WWTP units. The distribution chamber shall be designed, constructed and equipped regarding the requirements set  in Table 2-1.  The distribution chamber shall receive the wastewater from the outlet structure of the grit and grease  removal tank and distribute it evenly to the primary clarifiers. A bypass system as described at the  outlet of the grit and grease removal tank can be considered at this chamber. The structure shall be  made of reinforced concrete. The penstocks or valves shall be electrical actuator in accordance with  the specifications given in Section 7.8.8 and 7.8.18. The operation status of the penstocks should be  monitored and controlled by the SCADA system. Chambers designed and constructed for the needs of  Stage 2 should be isolated by an appropriate material/construction assuring the isolation until  installation of penstocks proposed for Stage 2. The sprinkler system shall be designed and installed above the inlet channel of the primary clarifier  tank and distribution chamber of the primary clarifier tank to prevent and/or remove the surface  accumulation in this area. The treated water should be used for this purpose.  3_Vol3_d4.3_Section 3_Plant Description_GIR_rev08  3.3.4.6 Distribution Chamber for Primary Clarifiers