AN EVALUATION OF GEOTEXTILES FOR TEMPORARY SEDIMENT CONTROL

The performance of geotextiles for sediment control was evaluated in t he field and laboratory. Runoff samples collected in the field indicat ed that essentially no sediment removal was attributable to filtration by the fabric. Silt fences also had little influence on the turbidity of the discharged runoff. Total suspended solids removals of 68 to 90 % were found in flume tests in which silt fences were installed. The r emoval efficiency was correlated with the average detention time of th e impounded runoff behind the fence, Flow rates through the fences und er field conditions were two orders of magnitude less than would be ca lculated using standard ASTM index characteristics of the fabrics. Thi s discrepancy resulted from clogging of the fabric with sediment and f rom the turbulent flow through the fabric openings at the hydraulic he ads on the fabrics when used as silt fences.