Improving stormwater infiltration with pneumatic air fracturing
Date
2024
Authors
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Publisher
University of Delaware
Abstract
Infiltration basins are one example of stormwater infrastructure where infiltration must be maintained for the system to perform as designed. Unfortunately, sediment buildup and sometimes low-permeability native subsurface geological media within a few feet of the ground surface impede operation. When infiltration capacity is limited, pneumatic air fracturing may improve and maintain sufficient stormwater infiltration and, in some cases, encourage plant root growth. Here, we evaluate the utility of pneumatic air fracturing to remediate stormwater infiltration basins that drain poorly. Pneumatic air fracturing was conducted in 2020 and 2022 at two basins managed by the Delaware Department of Transportation. Using side-by-side control and treated sections, short and long-term improvements (0 – 33 months) in media properties and stormwater infiltration were assessed at shallow and deeper depths (0 – 100cm) using dynamic cone penetrometer, saturated hydraulic conductivity, and dyed water infiltration tests. Results indicate that pneumatic air fracturing significantly reduces the effects of compaction, resulting in an immediate reduction in soil penetration resistance of 67 ± 9%. Saturated hydraulic conductivity also increases, and while these increases diminish with time, they are 100 ± 30% after 12 months. However, these benefits are primarily at > 20 cm depth, at least at these test sites. For both basins, pneumatic air fracturing fixed the perpetual water-logged surface conditions that diminished basin performance. This is the first application of decompaction with pneumatic air fracturing to infiltration basins to increase stormwater infiltration in the US. We discuss the possibility of using similar pneumatic air fracturing on other infiltration basins where the loss of infiltration capacity is a concern.
Description
Keywords
Best management practices, Compaction, Infiltration basins, Pneumatic air fracturing, Saturated hydraulic conductivity