Keywords

Sediment control, stormwater runoff, silt fence, filter fabric, tilted test bed, simulated rainfall, turbidity

Abstract

Silt fence is one of the most widely used perimeter control devices and is considered an industry standard for use in the control of sediment transport from construction sites. Numerous research studies have been conducted on the use of silt fence as a perimeter control, including a number of studies involving controlled laboratory flume tests and outdoor tests performed in the field on construction sites with actual monitored storm events. In field tests, due to the random and uncontrollable nature of real storm events and field conditions, studies have shown difficulty in evaluating silt fence performance. These field studies have shown the need for performance testing of silt fence in a more controlled environment, which can also simulate the actual use and performance in the field. This research, which is a continuation of ongoing research on silt fence fabrics at UCF Stormwater and Management Academy, was conducted in order to evaluate silt fence performance under simulated field conditions. Presented in this thesis are evaluation of two silt fence fabrics, a woven (ASR 1400) fabric and nonwoven (BSRF) fabric. Both fabrics were installed separately on a tilted test bed filled with a silty-sand soil and subjected to simulated rainfall. Previous field studies on the performance of silt fence fabrics have evaluated the turbidity and sediment removal efficiencies only after the rain event, with the assumption that the efficiency values represent the true overall performance of silt fence. The results of this study revealed that the turbidity and suspended sediment performance efficiencies of silt fence were significantly affected by the time of sampling. The performance efficiencies during rainfall remained less than 55 percent, however, after the rainfall event ended, the performance efficiencies increased over time, reaching performance efficiency upwards of 90 percent. The increase in efficiency after rainfall was due to the constant or decreasing ponding depth behind the silt fence, increased filtration due to fabric clogging, and sedimentation of suspended particles. The nonwoven fabric was found to achieve higher removal efficiencies and flow-through rates both during and after the rain event when compared with the woven fabric. However, over the entire test duration (during and after rainfall combined), the projected overall efficiencies of both fabrics were similar. The projected overall average turbidity performance efficiencies of the woven and nonwoven silt fence fabrics was 80 and 78 percent, respectively. Both fabric types also achieved comparable overall average suspended sediment concentration efficiencies of 79 percent. This result leads to the conclusion that silt fence performance in the field is dependent on three main processes: filtration efficiency occurring during the rain event, filtration and sedimentation efficiency occurring after the rainfall event, and flow-through rate of the silt fence fabrics. Decreases in the flow-through rate lead to increases in the overall efficiency. This thesis quantifies the different mechanisms by which these processes contribute to the overall efficiency of the silt fence system and shows how these processes are affected by different conditions such as the degree of embankment slope and rainfall intensity.

Notes

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Graduation Date

2014

Semester

Spring

Advisor

Chopra, Manoj

Degree

Master of Science in Environmental Engineering (M.S.Env.E.)

College

College of Engineering and Computer Science

Department

Civil, Environmental, and Construction Engineering

Degree Program

Environmental Engineering

Format

application/pdf

Identifier

CFE0005158

URL

http://purl.fcla.edu/fcla/etd/CFE0005158

Language

English

Release Date

May 2014

Length of Campus-only Access

None

Access Status

Masters Thesis (Open Access)

Subjects

Dissertations, Academic -- Engineering and Computer Science; Engineering and Computer Science -- Dissertations, Academic

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