Performance of engineered soil and trees in a parking lot bioswale

This article may be used for research, teaching and private study purposes. Any substantial or systematic reproduction, redistribution , reselling , loan, sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. A bioswale integrating an engineered soil and trees was installed in a parking lot to evaluate its ability to reduce storm runoff, pollutant loading, and support tree growth. The adjacent control and treatment sites each received runoff from eight parking spaces and were identical except that there was no bioswale for the control site. A tree was planted at both sites. Storm runoff, pollutant loading, and tree growth were measured. There were 50 storm events with a total precipitation of 563.8 mm during February 2007 and October 2008. The bioswale reduced runoff by 88.8% and total pollutant loading by 95.4%. The engineered soil provided a better aeration and drainage for tree growth than did the control's compacted urban soil. The superior performance of the bioswale demonstrated its potential use for large-scale application in parking lots and roadsides to reduce runoff and support tree growth. Introduction Increasing urbanisation has resulted in the construction of more roads and parking lots, significantly increasing the amount of impervious land cover in our towns and cities (Arnold and Gibbons 1996). Davis et al. found parking lots accounted for 5% of urban land use in the Upper Great Lakes region and 7% of the total urban area in Tippecanoe, Indiana (Davis et al. 2010a, 2010b). In metropolitan Sacramento, parking lots make up 12% of the urban land (Akbari et al. 2003). Impervious land cover alters the quantity and quality of surface runoff because of its effects on surface retention storage, rainfall interception, infiltration , runoff temperature, and contaminants. Large volumes of excess storm water runoff from urbanised areas cause flooding, water pollution, groundwater recharge deficits, destroyed habitat, beach closures, and toxicity to aquatic organisms (Greenstein et al. 2004, USEPA 2005). Runoff from …