Date of Award

5-2014

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biosystems Engineering

Committee Member

Dr. Charles V. Privette, III, Committee Chair

Committee Member

Dr. Calvin B. Sawyer

Committee Member

Dr. John C. Hayes

Abstract

Accelerated erosion and highly turbid stormwater runoff from construction sites are known to cause a variety of environmental and economic problems. To reduce turbidity and keep eroded sediment on site, this research was conducted to evaluate the potential for turbidity reduction using polyacrylamide (PAM) flocculants with sediment control best management practices (BMPs).

Previous research has shown significant turbidity reduction when applying granular PAM to linear sediment control BMPs. Numerous studies indicate that PAM loses efficacy if it becomes wet and then dries. This makes PAM reapplication a necessary part of maintaining sediment control BMPs using PAM and suggests that further research is warranted.

The longevity of PAM when it is applied and reapplied to sediment tube ditch checks was evaluated. No statistical differences were observed between freshly applied PAM and PAM which endured a three-, five-, or ten-day waiting time between reapplication and runoff event. However, the two trials of the ten-day test yielded the highest effluent turbidities that were observed.

Research on a South Carolina Department of Transportiation (SCDOT) construction site analyzed the impact on turbidity of rock ditch checks (RDCs) and rock ditch checks with washed #57 stone on the upstream face (RDC-WS), both with and without granular PAM. It was observed that RDCs alone tended to increase turbidity of runoff between 116% and 282%. For RDC-WS the observed increase to turbidity was smaller, between 3% and 43%. Both types of check were treated with 100 grams of granular Applied Polymer Systems Silt Stop® #705 PAM and turbidity reduction of runoff was consistently observed, though it varied between 12% and 67% for average turbidity and between 46% and 82% for peak turbidity.

Based on these results, when PAM is used with sediment control BMPs, it should be reapplied after every rain event of 0.5 inches or greater, or every 5 days if no such event occurs. This should ensure effective PAM is constantly present to reduce turbidity of runoff during a storm event.

Included in

Engineering Commons

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