Product(s): SewerGEMS, CivilStorm Version(s): 08.11.05.58 Environment: N\A Area: Layout and Data Input

# Problem

For a conduit, what is the difference between Pipe Surface Area and Pipe Rise-Length for Infiltration Load Type? Which should I use if want to take into account both the length and diameter of the pipe when computing infiltration (flow seeping into the pipe).

# Solution

With the "surface area" method, the intended infiltration loading unit is an area such as square feet. The "Infiltration Rate per Loading Unit" that you enter is then applied based on the surface area of the pipe.

With the "Pipe Rise-Length" method, the infiltration loading units are diameter and length. So with "in-mile" selected for example, the "Infiltration Rate per Loading Unit" that you enter is applied to every inch of diameter per every one mile of pipe. So if the "infiltration rate per loading unit" is 1 cfs, the infiltration loading units"in-mile" and the pipe 8 inches, one tenth of a mile long, the infiltration flow rate of the pipe would be 8 * 0.1 * 1 cfs = 0.8 cfs.