Inlet and Exit Weir Tank Design Program

The purpose of the inlet and exit tank program is to determine the dimensions of the weir tanks attached to the inlet and exit channels, to calculate the dimensions of the circular ports in the tanks that deliver water from the channels to the waste and distribution system, and to configure the design for the distribution and waste system which includes a drainage channel running along the inlet channel side of the sedimentation tank. Each tank has a z-dimension equal to the z-dimension of the corresponding channel. However, the tanks are currently being redrawn as extensions of the channels; not separate objects.

The Inlet Weir Tank

Sometimes it is necessary to shut off the flow of water into the sedimentation tank in order to clean it, make repairs or alterations, or to close it off if the plant is producing an excess of treated water. For this purpose, the inlet weir tank is needed to funnel the excess water to the waste system. The functionality of the tank allows for the sedimentation tank to be shut off, while leaving the rest of the components of the plant unaffected.  The weir in front of the tank controls the height of the water in the tank.  The inlet tank contains one vertical pipe which sends water to the waste channel.  

The Exit Weir Tank

The exit weir tank acts as a passage to either the waste line or the distribution tank. Depending on the quality of the treated water and the functionality of the plant, one of the two passage ways is plugged to prevent the water from traveling down that pipe. The weir tank attaches to the end of the exit channel and works with the exit weir to control the flow to the storage tank and control the overall water level throughout the entire plant. The dimensions of the exit channel weir tank are identical to those of the inlet channel weir tank.

The Waste and Distribution Pipe System

The waste and distribution system consists of one pipe stemming from the inlet weir tank to a tee and two pipes coming out of the exit weir tank that each connect to elbows in opposite directions. The inner pipe in the exit weir tank connects to an elbow that faces the inlet weir tank. There is a pipe that connects the elbow facing the inlet weir tank to the inlet tee. This part of the system accounts for the waste passage and outputs to the drainage channel on the inlet channel side of the sedimentation tank. The outer pipe in the exit weir tank leads to an elbow that connects to the distribution tank. The inlet pipe, inlet tee, exit pipes and elbows have all been elevated to the same elevation as the sedimentation tank drain valves so that all drainage occurs at the same height. An elbow must also be put in place that wraps around the inlet channel edge of the sedimentation tank and rotated 45 degrees to allow for minimum splashing of the waste water when it flows into the drainage channel.

The Drainage Channel

The drainage channel will run along the sedimentation tank on the side of the inlet channel.  The channel will allow waste water from both inlet and exit channel tanks to run out to waste.  It will be fed from an elbow connected to the inlet channel tank tee. The elbow will be rotated at 45 degrees from the base of the drain channel to minimize splashing and must allow for the exiting waste water to flow in the direction of the all drained waste water.