Assessing the Impact of Soil Media Characteristics on Stormwater Bioinfiltration Device Performance: Lab and Field Studies

Bioinfiltration devices are a potentially effective option for the treatment and discharge of stormwater runoff from urban areas. However, the performance of these systems and other infiltration devices can be affected by factors such as texture, structure and degree of compaction of the media during their construction. The main goal of this study is to provide insight on media characteristics of a poorly operating biofilter facility located in Tuscaloosa, AL. Double ring infiltrometer tests and soil compaction measurements were conducted along a large biofilter to determine the in-situ characteristics of the media. Infiltration observations were also made during actual rain events. The effects of different compaction levels on the infiltration rates through the soil media were examined during laboratory column tests for comparison to the field observations. Similar tests were also conducted examining compaction effects of the media after mixing with varying amounts of filter sand to investigate restoration options. These results indicate that soil compaction has dramatic effects on the infiltration rates; therefore care needs to be taken during stormwater treatment facilities construction to minimize detrimental compaction effects.