I am writing quick step by ...

I am writing quick step by step calculation process, that will help you.

1. Compute the maximum flow in the main sewer pipe using Manning's equation for full pipe flow.

2.Compute the diameter of each siphon, Di, or the flow through each siphon, Qi, using Manning's equation for full pipe flow through each siphon

3.Compute the wall heights, yj (relative to main invert), in the inlet box. The walls separate the siphons from each other. The wall heights are the same height as the water depths, yj, in the main pipe corresponding to the discharge through the siphons. Here, Qj=1 is the discharge through siphon 1, Qj=2 is the discharge through siphons 1 and 2, and so on. Manning's equation for a partially full main pipe is used, but is solved backwards (numerically) in order to compute yj. We allow up to five siphons (four walls).

4. Compute the siphon invert elevations in the inlet chamber. According to Metcalf and Eddy, there is no loss in the inlet box for flow going from the main culvert to the first siphon since the flow travels in a straight path. However, for siphons 2 through n the flow must turn 90o to go over the chamber wall (a head loss of 1.5 velocity heads) and has an additional head loss of one velocity head as the flow enters siphon i. Therefore, for i=2 to n siphons and j=2 to n-1 walls.

I am not able to post equations properly. I will post a document to support all these steps tomarrow.