This is a photo taken during construction of the SPS that may help explain how the Overflow Tank is connected to the overall SPS system.   Look carefully at each section for an explanation.

Wetwell

Electrical conduit for power and control to Pumps #1 and #2

This green pipe was part of the old Sewer Treatment Plant and was removed.

Force Main from Wetwell to Hotel

Overflow Tank

Outlet piping from Pump #3

New piping connection from Pump #3 to Outlet Valve       (yellow line)

Drain Valve

(see below)

The grey line indicates new piping that was installed, but not yet in the photo.  This piping connects the “Drain Valve” directly into the Overflow Tank.  The purpose of this piping is to allow the Force Main to be drained back into the Overflow Tank for the possibility of future maintenance.  The Drain Valve is normally closed, thereby isolating the Force Main from the tank.

Note that the Pump #3 Outlet Valve is normally closed.  This is to prevent sewage being pumped from the wetwell to the Hotel from being drained into the Overflow Tank.  The only time the Outlet Valve should be opened is when it is intended to pump fluid from the Overflow Tank.  Since this valve is closed, the power to Pump #3 must be locked out at the Disconnect Switch.

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