Abstract
Stormwater quality in three urban watersheds in Denver that have been undergoing rapid infill redevelopment for about a decade was evaluated. Sampling was conducted over 18 months, considering 15 storms. Results: (1) The first-flush effect was observed for nutrients and total suspended solids (TSS) but not for total dissolved solids (TDS), conductivity, pH, and fecal indicator bacteria; (2) though no significant differences on event mean concentration (EMC) values were found among the three basins, local-scale EMCs were higher than traditional city-wide standards, particularly some metals and nutrients, most likely because of the significantly higher imperviousness of the studied urban basins compared to city averages; (3) peak rainfall intensity and total rainfall depth showed significant but weak correlations with some nutrients and metals, and TDS; (4) antecedent dry period were not correlated with water quality, except for phosphorus and lead; (5) contrary to what was expected, total coliforms and Escherichia coli were not correlated with TSS; and (6) no significant correlations between water quality and land-use or zoning categories were found. It was concluded that locally focused stormwater monitoring can aid data-driven decision-making by city planners where redevelopment is occurring at local “neighborhood scales”, particularly for the implementation and management related to green infrastructure and water-quality regulations.
Highlights
This study focuses on the “Berkeley neighborhood” in the City of Denver, which is experiencing rapid infill redevelopment
Statistical methods utilized include a suite of descriptive statistics, Anderson–Darling test for normality, Pearson correlation, Box-Cox transformation where applicable, one-way Analysis of Variance (ANOVA), and Analysis of Covariance (ANCOVA), all conducted in Matlab
Due to high variability in analyzed samples, it was determined that no significant differences existed between local, neighborhood-scale event mean concentration (EMC) among the three sites, as supported by ANOVA
Summary
Urban stormwater pollution is considered a worldwide concern, because of its effects on the environment and human health (e.g., Reference [1]). As cities grow in size, more pollutants are mobilized during storms and discharged into urban river systems where they can cause serious environmental problems [2]. Müller et al [3] recently developed the most up-to-date review of source pollutants in cities, concluding that atmospheric deposition, vehicular transportation-related activities, and metallic building structures are the major contaminant sources in urban stormwater. Cities worldwide continue growing in size and population, i.e., traffic and pollution from vehicles (e.g., Reference [4]); they change their imperviousness over time, as new constructions take place, a process that directly affect urban stormwater quantity and quality [5,6]
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