Integrating Sediment Compatibility into SMP Media Design

Abstract

Green infrastructure, also known as stormwater management practices (SMPs), are quickly revolutionizing the civil engineering field as engineers seek to mitigate the effects of climate change, such as sewage overflow and flooding. The ability of soil media to store, filtrate, and infiltrate stormwater heavily influences the performance of bioinfiltration and bioretention systems, popular types of SMPs. This two-year study combines concepts from water resources engineering and geotechnical engineering to assess the performance of five bioinfiltration systems (SMP A, LO1, LO2, LO3, and LO4), analyze laboratory and field measurements of saturated hydraulic conductivity (K_sat), and conduct a comprehensive filter design laboratory study. Results from this study indicate no significant change in the performance of SMP A over a six-year study period including particle size distribution, plasticity, bulk density, soluble chlorides concentration, and field spot infiltration rates. Analysis between laboratory and field measured K_sat in SMP A reveal no significant difference between the two. Additionally, HYDRUS 1D models of LO1, LO2, LO3, and LO4 modeled recession rates similar to observed rates in the field (with the exception of LO2). Lastly, preliminary results from the laboratory study suggest many benefits to designing bioinfiltration media to behave as an effective graded filter to incoming sediments. Selecting sediment-compatible media retains incoming sediments at or near the surface, thus reducing the need for extensive maintenance to reverse sediment clogging. Instead, more localized, predictable maintenance can be performed – thus saving time and costs. Overall, screening proposed SMP media for sediment compatibility using preliminary design charts can improve the longevity and resiliency of these systems.