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2005
Author(s): Dietz, M.E., and J.C. Clausen.
Title: “A Field Evaluation of Rain Garden Flow and Pollutant Treatment”
Journal (Issue): Water, Air, and Soil Pollution, 167: 123-138.
Study Type: Field
Description: One of the first published papers on field performance of rain gardens. Two rain gardens in Haddam, CT, received rooftop runoff. Samples were analyzed for total phosphorus, nitrogen species, and heavy metals. Inflow, overflow, and percolate flow were measured, and redox potential was measured. Poor treatment of nitrate, total Kjeldahl nitrogen, and total phosphorus found in rooftop runoff was observed. Total phosphorus concentrations were higher in the effluent than in the influent. Many of the samples run of heavy metals fell below the detection limits. NH3-N was the only pollutant that was significantly lower in the effluent than the influent for both gardens, and 1 garden had significant values for total nitrogen. The rain gardens worked well for overall flow retention, but had minimal impact on reducing pollutant concentrations. In areas where rain gardens could be installed without underdrains, they would be very effective in reducing pollutant loads.
Author(s): Dussaillant, A.R., A. Cuevas, and K.W. Potter.
Title: “Raingardens for Stormwater Infiltration and Focused Groundwater Recharge: Simulations for Different World Climates”
Journal (Issue): Water Science & Technology: Water Supply, 5(3-4): 173-179.
Study Type: Modeling
Description: A simple numerical model was developed to model rain gardens to predict recharge rates for different climates (humid, semi-arid, and arid). Water is modeled over 3 layers: (1) root zone, (2) middle storage layer, and (3) site subsoil. A Green-Ampt equation was coupled with a surface water balance to continuously simulate recharge, runoff, and ET, for 5 year periods. For the Green-Ampt equation, RECARGA model was used. The results showed that the optimum ratio of area of rain garden to contributing impervious area was 10-20% for a humid (Madison, WI [rainy season only]) and semi-arid (Santiago, Chile) climate, and closer to 5% for an arid climate (Reno, NV).
Author(s): Hsieh, C., and A.P. Davis.
Title: “Evaluation and Optimization of Bioretention Media for Treatment of Urban Storm Water Runoff”
Journal (Issue): Journal of Environmental Engineering, 131(11): 1521-1531.
Study Type: Laboratory and Field
Description: Synthetic runoff was applied to 18 bioretention columns with different media mixtures and configurations and 6 existing bioretention cells to measure infiltration rate and pollutant removals for oil/grease, lead, total suspended solids, total phosphorus, nitrate, and ammonium. Two on-site experiments were conducted during a rainfall event to compare it to the laboratory investigation.
Author(s): Hsieh, C., and A.P. Davis.
Title: “Multiple-Event Study of Bioretention for Treatment of Urban Storm Water Runoff”
Journal (Issue): Water Science & Technology, 51(3-4): 177-181.
Study Type: Laboratory
Description: Synthetic runoff was passed through a bioretention test column once per week for 12 weeks to analyze performance for consecutive events. The results showed excellent removal efficiencies for TSS, oil/grease, and lead (>99%), and total phosphorus removals ranged from 47-68% (increased slightly throughout monitoring period). Nitrate concentrations increased during the first 5 weeks of the study and were higher than the influent, but then they were displaying removal efficiencies of 9-20% afterwards. This was due to nitrate in the mulch leaching out. This study confirmed long-term effectiveness of a bioretention column for water quality improvement.
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