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ABSTRACT Background and Aim: Considering the importance of environmental impact assessment of projects, an environmental impact assessment (EIA) of establishment of compost plant in Sanandaj was planed. The aim of this study was to assess positive and negative impacts resulted from establishment of the compost plants and provide managerial solutions to minimize environmental harmful impacts by use of modified Leopold Matrix and Scaling checklist methods which was an innovation in our study. Material and Methods: In this study, the present environmental situation was investigated. Considering the properties and kind of pollutions of this plant, after determination of assessment criteria, direct and indirect impacts of construction and exploitation of the plant on environmental elements were evaluated at short, medium and long term intervals. By expansion of Leopold Matrix into four parted matrix, in addition to the amount (importance) and extent of the impacts, the remaining duration of impacts on the environment was assessed as a separate factor. Results: The results of this study were presented in the form of two alternatives: No (performance of the project with no concern for environmental issue) and yes (performance of the project with application of the methods to reduce environmental harmful impacts). Conclusion: The resultant of the first alternative (No) was (-253). Therefore the project was rejected. After reducing the harmful impacts, the resultant was (+351) ant the project was accepted. Key word: compost plant, environmental impact assessment, four parted matrix, sanandaj Conflict of Interest: Nill Received: Jan 10, 2010 Accepted: March 13, 2010