Stormwater runoff from automobile trafficked areas introduces significant loads of pollutants to receiving water bodies leading to an adverse long term effect. To control runoff pollutants from parking lot, a filtration treatment system with a layered filter media activated carbon, composite, vermiculite and zeolite was installed. The removal of the pollutant constituents was evaluated in this study. During a monitoring period of eighteen months eleven runoff samples were collected from the influent and effluent sections and analyzed for the mentioned pollutant parameters. The mean influent annual load of TSS. Cu and Zn were 2600, 2.1 and 3.5 kg respectively. For the monitoring period mean removal efficiencies of 85% for TSS, 75% for Cu, 73% for Zn, 83% for 16 EPA PAHs, 70 to 98% for individual PAHs, 93% for mineral oil, 71% for NH4-N and 52% for TOC were achieved. Greater than 60% of the Cu load was removed within the filter chambers, but >60% of Zn and TSS loads were removed in the sedimentation tank, oil separator and geotextile filter mainly due to filtration, precipitation and sorption to sediments. Furthermore, except for chrysene heavier molecular weight PAH compounds were effectively removed than lighter molecular weight PAH compounds. The treatment mechanisms include: filtration, precipitation, adsorption and cation exchange. (C) 2011 Elsevier BM. All rights reserved.