University of Illinois Extension

Quiz

Practice Problems: Sizing Commercial Subsurface Seepage Systems 1

Sizing of subsurface seepage systems is done by applying the soil loading rate to the average daily flow, or the number of bedrooms for residential settings.

The soil loading rate can be calculated by using either a percolation (perc) test or a soil evaluation.  The procedure for conducting percolation tests is found in section 905, Appendix A, Illustration G of the administrative code.

Information on using soil evaluations and loading rates is found in Section 905, Appendix A, Illustration M

Information on calculations for gravel trenches is found in Appendix A, Illustration H, Exhibit A.  Exhibit B is used for gravelless pipe.

Commercial practice problems.

A factory will be built employing 30 people and will have showers. There will be no additional sewage discharge.   Trenches will be dug in at 24 inches. Results from a soil evaluation shows soil groups 5A at 0 to 24 inches, 5D at 24 to 33 inches, 3B at 33 to 48 inches, and 4C at 48 to greater than 60 inches.
  1. Practice Problems: Sizing Commercial Subsurface Seepage Systems 1

    What is the loading rate?

    gallons/day
  2. Practice Problems: Sizing Commercial Subsurface Seepage Systems 1

    What minimum size of septic tank is required?

    gallons
  3. Practice Problems: Sizing Commercial Subsurface Seepage Systems 1

    What linear feet of gravel trench is required for a 24 inch trench?

    linear feet
  4. Practice Problems: Sizing Commercial Subsurface Seepage Systems 1

    What linear feet of 22 inch chamber would be required?

    feet