Hydrostatic Pressure Associated with Various Levels of Backed-up Water and Sediment on Silt Fences

Silt fence is used on construction sites, roadways, and other locations where water and sediment needs to be stopped prior to leaving an area of disturbed soil. As silt fence continues to receive water and sediment over a single or multiple storm events, failure can occur. In order to stop this failure, the hydrostatic pressures exerted on the fence and posts must be known. This research project was designed to test the hydrostatic pressures exerted on Silt-Saver silt fence along with two other approved silt fences in the state of Georgia. The fences will be exposed to various levels of water and sediment with the hydrostatic pressure being measured. Three silt fences were tested on an indoor testing apparatus where multiple water flows and sediment concentrations could be used to test the hydrostatic pressure on the three fences being tested. Besides the indoor tests on the testing apparatus, a larger scale test was conducted with various water flows and sediment loads to determine the hydrostatic pressures exerted on silt fence with multiple post spacing. The larger testing set-up allowed for multiple post to be tested and pressures measured across an installation. At the time of this abstract submission, the testing has just begun with results being expected by the time of the annual conference. According to the manufacture of Silt-Saver silt fence, the hydrostatic pressure should be reduced on the post as water and sediment accumulate behind the silt fence until it reaches the second stage of the fence. When water reaches the second stage, the pressure is reported to be reduced therefore allowing better stability of the silt fence. The Silt-Saver fence will be tested against two approved silt fences in Georgia.