Investigation of sand boils near Ware, IL, Middle Mississippi River, Preston Levee District

Abstract

During flooding in 2011, 2013, and 2016 on the Middle Mississippi River between St. Louis and Cape Girardeau, MO, high-energy sand boils developed at the land side levee toe. These recent floods varied from moderate to major events but were well below the design flow line for the levees. This report documents a case study of internal erosion at a levee site in southern Illinois near the town of Ware, which is located in the Preston Drainage and Levee District. Site specific geotechnical data from the Ware site were used to identify parameters, such as top stratum thickness, Unified Soil Classification System (USCS) soil types, engineering properties, geologic depositional environments, stratigraphy, and hydraulic gradients, that influence seepage and poor levee performance. An underlying assumption for this study was that sand boils discovered at the Ware site after the flooding in 2013 were formed during a single flood event. However, sand boils are typically associated with chronic seepage related to underlying site geology, levee orientation with the geology, and blocked exit conditions. Thus, seepage problems tend to progress over time in terms of their severity and response to medium to large flood events.

A Sand Boil Database for Piping Risk Management in the Po River, Italy

“…In this case, thus, the flood event did not induce any uplift effect at the toe, with the development of new cracks within the top stratum; rather, the piping activity observed therein is very likely to be attributed to the reactivation of a pre-existing sand boil, that can be triggered by lower local gradients. Indeed, as also observed by Kelley et al [9] for to the Mississippi River, in chronic seepage areas, sand boil activity can form at lower levels of flooding because of the accumulated effects of internal erosion at these locations. The effect of a pre-eroded soil volume on the initiation of piping has been also investigated by García Martínez et al [36] using an FE approach, with reference to a well-documented cross-section of the Po River close to the delta.…”

“…All sand boils are typically monitored on site "manually", by technicians of AIPo who are in charge of surveying critical cross-sections, detecting sand boil activations/reactivations during high-water events and implementing emergency actions to stop erosion progression, whenever necessary. In this respect, it must be observed that the growing need for an accurate, possibly automated identification of surface evidence of backward erosion piping worldwide has encouraged in recent years the application of sophisticated techniques, such as satellite or drone imagery together with machine learning models (e.g., [9,22,42]), which are meant to facilitate capturing sand boil activity and local predisposing conditions. necessary.…”

“…necessary. In this respect, it must be observed that the growing need for an accurate, possibly automated identification of surface evidence of backward erosion piping worldwide has encouraged in recent years the application of sophisticated techniques, such as satellite or drone imagery together with machine learning models (e.g., [9,22,42]), which are meant to facilitate capturing sand boil activity and local predisposing conditions.…”

“…As an example, the 2011 Mississippi flooding resulted in the activation or reactivation of many large, high-energy sand boils, together with numerous small to medium size sand boils [8]. Furthermore, in recent years, hundreds of medium to large sand boils have been reported to reactivate along some specific segments of the Mississippi, for moderate to major flood events related to water levels well below the design flood [9].…”