User notification, "The infiltration loading unit is not specified...." OR Pipe Surface Area vs Pipe Rise-Length for Infiltration Load Type

  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.

User notification: The infiltration loading unit is not specified. You must specify the loading unit. 

NOTE: if you encounter this user notification when computing the model after selecting or global editing the Infiltration Load Unit in the Conduit Flextable it's due to selecting units that are not applicable to the Infiltration Load Type you selected.

The Infiltration Load Unit field is shared among multiple infiltration load types, so in a flextable you will see all available units display, whereas in the properties gri dropdown for a single element it will only show units applicable to the conduit's selected infiltration type. For example, you can encounter the above error if the 'infiltration load type' is set to 'Surface Area' with "in-mile" as the infiltration loading unit, since that unit is only applicable to the "Pipe Rise-Length" Infiltration type. In order to resolve this user notification check the correct units from the properties grid dropdown then use that unit when editing from the Flextable.

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