Details:

Journal Title:
Ecological Engineering
Personal Author:
Shrestha, Paliza ; Hurley, Stephanie E. ; Wemple, Beverley C.
Shrestha, Paliza ; Hurley, Stephanie E. ; Wemple, Beverley C. Less -
NOAA Program & Office:
OAR (Oceanic and Atmospheric Research) ; Sea Grant
OAR (Oceanic and Atmospheric Research) ; Sea Grant Less -
Sea Grant Program:
LCSG (Lake Champlain Sea Grant)
Description:
Water quality performance of eight roadside bioretention cells in their third and fourth years of implementation were evaluated in Burlington, Vermont. Bioretention cells received varying treatments: (1) vegetation with high-diversity (7 species) and low-diversity plant mix (2 species); (2) proprietary SorbtiveMedia™ (SM) containing iron and aluminum oxide granules to enhance sorption capacity for phosphorus; and (3) enhanced rainfall and runoff (RR) to certain cells (including one with SM treatment) at three levels (15%, 20%, 60% more than their control counterparts), mimicking anticipated precipitation increases associated with climate change. A total of 121 storms across all cells were evaluated in 2015 and 2016 for total suspended solids (TSS), nitrate/nitrite-nitrogen (NOx), ortho-phosphorus (Ortho-P), total nitrogen (TN) and total phosphorus (TP). Heavy metals were also measured for a few storms, but in 2014 and 2015 only. Simultaneous measurements of flow rates and volumes allowed for evaluation of the cells’ hydraulic performances and estimation of pollutant load removal efficiencies and EMC reductions. Significant average reductions in effluent stormwater volumes (75%; range: 48–96%) and peak flows (91%; range: 86–96%) was reported, with 31% of the storms events (all less than 25.4 mm (1 in.), and one 39.4 mm (1.55 in.)) depth completely captured by bioretention cells. Influent TSS concentrations and event mean concentrations (EMCs) was mostly significantly reduced, and TSS loads were well retained by all bioretention cells (94%; range: 89–99%) irrespective of treatments, storm characteristics or seasonality. In contrast, nutrient removal was treatment-dependent, where the SM treatments consistently removed P concentrations, loads and EMCs, and sometimes N as well. The vegetation and RR treatments mostly exported nutrients to the effluent for those three metrics with varying significance. We attribute observed nutrient exports to the presence of excess compost in the soil media. Rainfall depth and peak inflow rate had consistently negative effects on all nutrient removal efficiencies from the bioretention cells likely by increasing pollutant mobilization. Seasonality followed by soil media presence, and antecedent dry period were other predictors significantly influencing removal efficiencies for some nutrient types. Results from the analysis will be useful to make bioretention designers aware of the hydrologic and other design factors that will be the most critical to the performance of the bioretention systems in response to interactive effects of climate change.
Keywords:
[+]
Runoff Sediments Water Quality Stormwater management
Source:
Ecological Engineering 112: 116-131, 2018
DOI:
https://doi.org/10.1016/j.ecoleng.2017.12.004
Sea Grant Document Number:
LCSG-R-18-002
Document Type:
Journal Article
Funding:
Grant no. NA10OAR4170063
Place as Subject:
Burlington (Vt.)
Rights Information:
CC BY-NC-ND
Compliance:
Library
Main Document Checksum:
[+]
urn:sha256:ddd22d36245786f01658491fbc924a28d6e7c2c1f8fb5c91982be9fc30bf2aef
Download URL:
https://repository.library.noaa.gov/view/noaa/43794/noaa_43794_DS1.pdf
File Type:

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