University of Illinois Extension

Quiz

Instructions for Conducting Percolation Tests 905 Appendix A, Illustration G

  1. Instructions for Conducting Percolation Tests 905 Appendix A, Illustration G
    At least 3 separate percolation tests must be performed with the holes being separated by a distance of ____ feet.
    1. 10
    2. 20
    3. 25
    4. 50
      Number and Location of Percolation Tests. Select an area where the seepage field will be located. When digging the holes, avoid animal burrows, large root channels, etc. At least 3 separate percolation tests shall be performed at the site of each proposed disposal area. The percolation test holes shall be at least 50 feet apart. At least one hole shall be located at the lowest elevation of the proposed absorption field area. The 2 holes with the highest results shall be used to determine percolation rate.
  2. Instructions for Conducting Percolation Tests 905 Appendix A, Illustration G
    An 18 hour waiting period between presoaking and the percolation test may be waived if
    1. The soil is mostly sand.
      On the day prior to conducting the percolation test, carefully fill the hole with water and keep it full for at least 4 hours. The percolation test shall be conducted on the day following this presoaking at least 18 hours after presoaking is completed but prior to 30 hours after presoaking is completed. Cover the hole during this 18-30 hour waiting period. In sandy soils with greater than 70% sand and less than 15% clay (sand and loamy sand), after the 4 hour presoak, a percolation test may be attempted without the 18 hour waiting period. If the percolation test results are greater than 45 minutes for a 6 inch drop in water, the test must be repeated after the 18 hour waiting period. If the percolation test results are 45 minutes or less, the percolation rate shall be used to size the system.
    2. The soil is mostly silt.
    3. It has rained within two hours of the test.
    4. It has rained within one hour of the test.
  3. Instructions for Conducting Percolation Tests 905 Appendix A, Illustration G
    The only acceptable results from the percolation test are from
    1. The last 12 inches of drop in water.
    2. The last 8 inches of drop in water.
    3. The last 18 inches of drop in water.
    4. The last 6 inches of drop in water.
      Measure the last 6 inch drop in water level at thirty minute intervals until all the water has seeped away. Warning: Under no conditions shall measurements be taken from water filled to the top of the hole or on water 12 inches deep in the hole. Such results are completely invalid and will not be accepted. Results from the last 6 inches of drop in water are the only results that will be accepted.
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