Low impact development (LID) systems, such as vegetated filter strips and bioretention cells, are designed to mimic pre-development hydrologic conditions and utilize the biophysical properties of soil to filter pollutants from stormwater runoff. Many LID designs use native soils, however, urban soils are typically degraded and compacted, losing their hydrologic function. Incorporation of locally-sourced soil amendments, such as compost and biochar, into urban soils can improve the physical properties of soil, but the impacts on water quality is less clear as amendments may act as either a sink or a source of pollutants. Most studies have used generalized recommendations for application rates ranging from 25-70% by volume, but higher application rates have not been proven necessary and are likely to export nutrients. A systematic comparison of the effects of different soil-amendments and application rates on water quality have not yet been studied. The objective of this study is to determine the optimal soil amendment for use in LID systems by analyzing the potential effects of sources and application rates on soil properties and water quality. To do this, a column experiment will be used to compare 4 soil amendments (Manure Compost, Mushroom Compost, Green Compost, and Biochar) blended with soil at 0, 5, 10, 25 and 50% by volume. To determine the leaching-potential, synthetic stormwater will be applied under flow-through conditions to simulate applications in various LID designs. The sorption-potential will be determined to evaluate the potential nutrient (NH4+, NO3-, PO4-3) and metal (Pb, Cu, As, Zn) mobility. The results of this study will inform cost-effective soil amendment sources and application rates for use in LID systems.
Lily Wetterlin
Lily Wetterlin is an M.S. student currently pursuing a degree in Watershed Science. She graduated from the University of Utah in 2018 with a B.S. in Geoscience and B.S. in Environmental & Sustainability Studies. After her undergraduate, she worked as a research associate for a variety of water quality studies within the Salt Lake Valley and most recently as an Environmental Specialist for a consulting firm. Lily's research at Utah State is investigating how to optimize the use of soil-amendments in native soil to improve runoff infiltration and water quality in Low Impact Development practices. Her future career goal is to work as a Water Quality Specialist in the intermountain west to protect and restore water bodies impacted by anthropogenic activities.
Erin Rivers