Date of Graduation

Fall 12-18-2015

Document Type

Project

Degree Name

Master of Science in Environmental Management (MSEM)

College/School

College of Arts and Sciences

Department/Program

Environmental Management

First Advisor

Allison Luengen, Ph.D

Abstract

Urban stormwater runoff is a major non-point source of pollutants release into the environment. Pollutants of concern include sediments; heavy metals; polycyclic aromatic hydrocarbons (PAHs); petroleum hydrocarbons; and chlorinated organic compounds, such as pesticides and polychlorinated biphenyls. Conventional stormwater management practices are designed to dispose of the runoff as quickly as possible, not to treat the pollutants. Low Impact Development (LID) concept is an alternative approach to the conventional framework that attempts to recreate hydrologically functional landscape mimicking pre-development regimes. This research paper assesses the effectiveness of two LID technologies, bioretention and permeable pavements in treating PAHs and common urban runoff metals such as lead, copper and zinc. Select case studies are used to synthesize data collected in the field and in the laboratory. Both technologies appear to be effective at treating metals with the exception of copper. Bioretention removal rates for dissolved zinc and lead range from 77-99% and 7-88% respectively. Removal rates for the same constituents by permeable pavements range from 40-97% and 30-80% respectively. Removal rates for dissolved copper by bioretention and permeable pavements range from export of 26% to removal of 70% and export of 40% to removal of 90% respectively. A clear mechanism behind dissolved copper leaching has not been determined. Bioretention is consistently effective at attenuating PAHs with removal rates ranging from 90-95%. No studies were found that evaluated the ability of permeable pavements to attenuate PAHs. Leaching of nitrogen and phosphate has been reported for both technologies, which presents a concern for nutrients overload. Long-term studies of both technologies in semi-arid climates are limited and require further research to demonstrate their effectiveness. Ongoing maintenance is essential for the continued long-term performance of bioretention and permeable pavements in attenuating pollutants. Making a single statement regarding which of the two technologies is better at producing cleaner effluent is not justified, since both are effective with some exceptions. Most likely, the use of both of these control measures in the treatment train set up would produce the most beneficial results.

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