2011 journal article

Field Evaluation of Bioretention Indicator Bacteria Sequestration in Wilmington, North Carolina

JOURNAL OF ENVIRONMENTAL ENGINEERING, 137(12), 1103–1113.

By: J. Hathaway n, W. Hunt n, A. Graves n & J. Wright n

co-author countries: United States of America 🇺🇸
author keywords: Storm water; Bioretention; Biofiltration; Indicator bacteria; E. coli; Enterococci
Source: Web Of Science
Added: August 6, 2018

Although bioretention has been shown to remove or sequester a wide range of pollutants, relatively little study has been performed to evaluate its ability to sequester indicator bacteria. Two adjacent bioretention areas in Wilmington, North Carolina, were studied. The primary difference in the design of the two systems was soil depth. One bioretention cell was constructed with 25 cm of fill soil (Bioretention-S) and one with 60 cm of fill soil (Bioretention-D). The systems performed differently for indicator bacteria on the basis of multiple performance evaluation metrics. Bioretention-D showed concentration reductions of 70% and 89% for E. coli and enterococci, respectively. Effluent concentrations from Bioretention-D compared well to US EPA target values and other studies in literature. Conversely, Bioretention-S showed concentration “reductions” of -119% and -102% for E. coli and enterococci, respectively. Effluent concentrations from Bioretention-S were substantially higher than USEPA target values and other studies in literature. Multiple factors were evaluated to determine the cause of performance differences between the two cells. The 25 cm of fill soil in Bioretention-S exhibited poorer runoff detention, likely because of higher soil water flux and decreased contact time relative to Bioretention-D. These differences seemingly led to diminished indicator bacteria sequestration. The results of this study suggest soil depth and hydraulic loading are important design parameters for bioretention implemented to sequester microbes.