Geosynthetics in roads and pavements

SILT FENCE

  

 

Introduction to the Problem  

Because accelerated erosion can result from 

denuded areas during construction, sediment 

control measures are needed to prevent 

construction-generated silt from being carried 

into nearby waterways or onto adjoining 

properties. Various types of sediment control 

measures are used to impede the flow of 

sediment-laden waters and to filter out 

sediment.   

 

Typical Solutions 

Sediment control structures composed of 

permeable material are placed so as to intercept 

sheet flow and low level channel flow from 

denuded areas.  These barriers serve (1) to 

decrease the velocity of moving water, and (2) 

to trap suspended sediment. Traditional 

measures include barriers made of straw, gravel 

or crushed stone, and brush.  

 

Improper use of filter barriers has been a major 

problem.  For instance, straw barriers have been 

used in streams and drainage ways where high 

water velocities and volumes have destroyed or 

impaired their effectiveness.  Another major 

problem has been that improper placement of 

the barriers has allowed undercutting and end 

flow, which have actually resulted in additions 

to rather than removal of sediment from runoff 

waters.  Finally, inadequate maintenance and 

cleaning efforts have tended to greatly lower the 

effectiveness of the barriers. 

 

Because of the problems noted above, straw 

barriers have generally shown low trapping 

efficiencies and high failure rates.   

 

Typical straw bale installation (failure)