Date of Award

Spring 2006

Project Type

Thesis

Program or Major

Civil Engineering

Degree Name

Master of Science

First Advisor

Thomas P Ballestero

Second Advisor

Stephen H Jones

Third Advisor

Robert M Roseen

Abstract

This study was undertaken to address concerns that current stormwater management practices could be degrading water quality by inadvertently providing habitat, nutrients, and transport mechanisms for fecal indicator bacteria. Concentrations of Escherichia coli (EC) and Enterococcus (ENT) were evaluated in the influent, effluent, and retained water of 11 stormwater management devices. All devices received equal portions of influent from a single stormwater outfall that handled runoff from a 3.55-hectare asphalt parking lot. During storm events, influent and effluent water samples were obtained from flow-weighted composite samples, thereby representing the microbial event mean concentration. Retained water samples were obtained from grab samples taken during dry weather periods between rainfall events. Bacteria were enumerated using membrane-filtration techniques.

EC concentrations were below the EPA’s primary contact recreational water standard of 235 cfu/100mL in 98% of all samples collected in the influent and effluent. Concentrations in the influent exceeded the equivalent ENT standard of 104 cfu/100mL in 67% of the events, with a median concentration of 560 cfu/100mL. Effluent concentrations of ENT exceeded the limit in at least 25% of events for all devices. Slight statistical differences (p

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