Note: Maximum Surcharge Height Over Crown Explanation
Here is an example of how the Maximum Surcharge Height over the Node Crown is calculated. Consider a manhole with an invert of 10 feet, one incoming pipe (Pipe A), one outgoing pipe (Pipe B), both pipes with a diameter of 2 feet, but the invert of Pipe A is 10 feet and the invert of Pipe B is 11 feet. What is the Maximum Surcharge height if the HGL at the node is 17 feet?
HGL at Node ---- 17 feet
Maximum Surcharge Height Over Crown is 4 feet
Node Crown --- 13 feet Pipe B Crown --- 13 feet
Pipe A Crown --- 12 feet
Pipe B Invert --- 11 feet
Pipe A Invert --- 1o feet MH Invert --- 10 feet