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0-6638-1 Report Abstract

Performance Testing of Coagulants to Reduce Stormwater Runoff Turbidity

Jett McFalls, Young-Jae Yi, Beverly Storey, Michael Barrett, Desmond Lawler, Brad Eck, David Rounce, Ted Cleveland, Holly Murphy, Desirae Dalton, Audra Morse, and George Herrmann, May, 2014

On December 1, 2009, the US Environmental Protection Agency (EPA) published a rule in the Federal Register establishing non-numeric and, for the first time, numeric effluent limitation guidelines (ELGs). The numeric ELGs included a turbidity limit of 280 nephelometric turbidity units (NTU) and sampling requirements for stormwater discharges from construction sites that disturb 20 or more acres of land at one time. At that time, the EPA required Texas to implement these new requirements when the Texas Commission on Environmental Quality (TCEQ) renewed their Texas Construction General Permit (CGP) in 2013. Due to litigation regarding the initial numeric ELG implementation, the EPA put numeric ELGs on hold in 2011 and on April 13, 2013, proposed to withdraw the numeric ELG as a requirement.

This project was initiated in 2010 to prepare the Texas Department of Transportation (TxDOT) for changes to the CGP regarding the monitoring and sampling of their construction site to meet the anticipated numeric ELG requirements. The scope of the project was modified due to EPA’s actions. However, in light of anticipated future numeric limits, the project’s monitoring and testing experiments proceeded to 1) determine “typical turbidity” representative of TxDOT’s construction site discharges, 2) collect performance data on innovative erosion and sediment control measures that might be expected to achieve the discharge standard, and 3) provide update to TxDOT’s Stormwater Managements Guidelines for Construction Activities.

Keywords: Effluent Limitation Guidelines, Stormwater, Turbidity, Flocculants, Coagulants, ELG, Erosion Control, Sediment Control

ENTIRE REPORT (Adobe Acrobat File – 1.8 MB)