field evaluation of rain garden flow and pollutant treatment

• Published in: Water, air, and soil pollution air, and soil pollution, 2005-10, Vol.167 (1-4), p.123-138
• Main Authors: Dietz, M.E, Clausen, J.C
• Format: Article
• Language: English
• Subjects: Applied sciences; Biological and medical sciences; Biological treatment of waters; Biotechnology; Copper; Environment and pollution; Environmental impact; Environmental monitoring; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Gardens; Gardens & gardening; High flow; hydrochemistry; Industrial applications and implications. Economical aspects; Lead; Nitrogen; nitrogen content; Other wastewaters; Overflow; phosphorus; Pollutant removal; Pollutants; Pollution; pollution control; Pollution detection; Rain; Redox potential; Retention; Runoff; Samples; Statistical analysis; Statistical methods; Storm runoff; Stormwater; Wastewaters; Water analysis; water pollution; Water sampling; water temperature; Water treatment and pollution; Zinc
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1007/s11270-005-8266-8

Rain gardens have been recommended as a best management practice to treat stormwater runoff. However, no published field performance data existed on pollutant removal capabilities. Replicated rain gardens were constructed in Haddam, CT, to capture shingled-roof runoff. The gardens were sized to store the first 2.54 cm (1 inch) of runoff. Influent, overflow and percolate flow were measured using tipping buckets and sampled passively. Precipitation was also measured and sampled for quality. All weekly composite water samples were analyzed for total phosphorus (TP), total Kjeldahl nitrogen (TKN), ammonia-nitrogen (NH sub(3)-N), and nitrite+nitrate-nitrogen (NO sub(3)-N). Monthly composite samples were analyzed for copper (Cu), lead (Pb) and zinc (Zn). Redox potential was measured using platinum electrodes. Poor treatment of NO sub(3)-N, TKN, organic-N, and TP in roof runoff was observed. Many Cu, Pb and Zn samples were below detection limit, so statistical analysis was not performed on these pollutants. The only pollutants significantly lower in the effluent than in the influent were NH sub(3)-N in both gardens and total-N in one garden. The design used for these rain gardens worked well for overall flow retention, but had little impact pollutant concentrations in percolate. These results suggest that if an underdrain is not connected to the stormwater system, high flow and pollutant retention could be achieved with the 2.54 cm design method.