Temporal Soil Dynamics in Bioinfiltration Systems

Abstract

Bioinfiltration systems for stormwater management rely on the ability of the engineered media to adequately infiltrate, filtrate, and store water to reduce runoff volumes and improve water quality. However, the potential clogging of the soil over time due to the migration of fines and deposition of sediment and debris has raised concerns regarding system longevity. To quantify temporal and spatial changes in textural and hydraulic properties of bioinfiltration media infiltrating runoff from an interstate, a comprehensive field and laboratory study was completed for two sites over a two-year period. Despite observed sediment deposition within both basins, there were no statistically significant trends in the saturated hydraulic conductivity of the media over the study period. Soil core sampling and analysis confirmed fines did not migrate through the soil column. Susceptibility to future clogging of the well-graded, loamy sand used at both sites was evaluated based on the collected data and permeability and retention criteria commonly used in geotechnical design of graded filters. Based on the results of this study and the current literature, soils proposed for use in bioinfiltration systems should be evaluated for filter compatibility with the anticipated sediment load and include maximum limits on the plasticity index to help enhance system lifespan and reduce necessary maintenance.