Year Established: 2013 Start Date: 2013-03-01 End Date: 2015-02-28
Total Federal Funds: $22,292 Total Non-Federal Funds: $45,887
Principal Investigators: Ishi Buffam, Dominic Boccelli
Abstract: A significant issue many urban centers face is the direct discharge of untreated sewage into receiving waters due to overburdened and antiquated combined sanitary and stormwater sewers. While conventional grey infrastructure approaches to mitigating combined sewer overflows (CSOs) tend to be disruptive and costly, the use of low impact development (LID) can mitigate overflow events and the associated deleterious impacts, while contributing other co-benefits. Vegetated (green) roofs – a type of LID – have been demonstrated to improve stormwater retention and provide energy savings, but also serve as a source of organic carbon, nutrients, and metals through runoff. Early studies using biochar – a type of activated carbon – within the green roof soil mix suggest that an amended soil mix could improve the effluent water quality from vegetated roofs. The objective of this project is to improve our understanding of the water quality benefits associated with the use of a biochar-amended soil mix within vegetated roof technology. Our central hypothesis is that biochar can enhance the ability of vegetated roofs, which can already reduce the quantity of CSOs, to improve effluent water quality loadings (i.e., organic carbon, nutrients, and metals) through direct influence on water chemistry as the runoff passes through the amended green roof medium. We will test our central hypothesis and associated objectives by: 1) evaluating the abiotic capabilities for nutrient and stormwater runoff retention due to enhanced sorption properties of biochar-amended soil medium via column reactors; 2) evaluating biotic and abiotic capabilities for nutrient and stormwater runoff retention due to enhanced sorption properties of a biochar-amended soil medium in vegetated green roof plots; and 3) developing a computational model for representing the hydraulic and water quality performance of vegetated roofs with and without biochar. The proposed research is creative and original because the study evaluates a low-cost option for improving the effluent water quality of vegetated roof technology, which is becoming increasingly more important as part of green-engineered solutions for stormwater management. The research program is transformative in that the research will not only demonstrate the water quality improvements associated with a biochar-amended green roof, but will also result in a modeling component that can be used within an integrated assessment framework both within and beyond the Ohio River Valley. As a result, the positive impact of this project will be a significant step forward in developing a more integrated infrastructure solution for storm water management by illustrating the potential impacts of biochar-amended vegetated roofs on CSO and nutrient management in urban environments.