content_image/458866.jpg
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. 

<img src='content_image/458866.jpg'>

No load reduction in screens and grit and grease removal tanks shall be taken into consideration in the design of WWTP units. 

## 3.3.4.6 Distribution Chamber for Primary Clarifiers 

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. 

