Storm‐Damaged Saline‐Contaminated Boreholes as a Means of Aquifer Contamination

Abstract

Saline water from a storm surge can flow down storm-damaged submerged water supply wells and contaminate boreholes and surrounding aquifers. Using data from conventional purging techniques, aquifer test response analysis, chemical analysis, and regression analysis of chloride/silica (Cl/Si) ratio, equations were derived to estimate the volume of saline water intrusion into a well and a porous media aquifer, the volume of water needed to purge a well shortly following an intrusion event, and the volume of water needed after delay of several or more months, when the saline plume has expanded. Purging time required is a function of volume of water and pumping rate. The study site well is located within a shoreline community of Lake Pontchartrain, St. Tammany Parish, in southeastern Louisiana, United States, which was impacted by two hurricane storm surges and had neither been rehabilitated nor chlorinated prior to our study. Chemical analysis of water samples in fall 2005 and purging of well and aquifer in June 6, 2006, indicated saline water had intruded the well in 2005 and the well and aquifer in 2006. The volume of water needed to purge the study well was approximately 200 casing volumes, which is significantly greater than conventionally used during collection of water samples for water quality analyses.

Vertical Saltwater Intrusion in Coastal Aquifers Driven by Episodic Flooding: A Review

“…Following vertical SWI, water resources managers are faced with the challenge of meeting potable water demands. To remediate wells contaminated by salt and potentially bacteria, extensive aquifer pumping, and chlorination are often performed (Carlson et al., 2008; Kaihotsu et al., 2017; Van Biersel et al., 2007). Disaster response efforts to reduce aquifer recovery times and restore potable water supply by pumping salinized groundwater and chlorinating wells can complicate flushing dynamics (Carlson et al., 2008; Illangasekare et al., 2006; Van Biersel et al., 2007).…”

“…To remediate wells contaminated by salt and potentially bacteria, extensive aquifer pumping, and chlorination are often performed (Carlson et al., 2008; Kaihotsu et al., 2017; Van Biersel et al., 2007). Disaster response efforts to reduce aquifer recovery times and restore potable water supply by pumping salinized groundwater and chlorinating wells can complicate flushing dynamics (Carlson et al., 2008; Illangasekare et al., 2006; Van Biersel et al., 2007). For instance, active pumping wells can draw saline water radially inward and influence the pattern of saltwater fingering (Figure 1e).…”

Prioritizing water availability study settings to address geogenic contaminants and related societal factors

“…Since 2000, seven hurricanes category 1 or higher have made landfall in North Carolina with damage estimates ranging from $5.3 to 27.8 billion (Smith, 2020 ). The effects of these storms on groundwater wells are studied primarily in terms of salinity (Anderson Jr & Lauer, 2008 ; Carlson et al, 2008 ; William, 2002 ), and there is a gap in knowledge surrounding geogenic constituent behavior during and post hurricane. Furthermore, coal combustion residual storage areas in the region are susceptible to flooding post hurricane, and the release of hazardous materials has been linked to events such as Hurricane Florence (Vengosh et al, 2019 ).…”

Comparison of Numerical Techniques Used for Simulating Variable-Density Flow and Transport Experiments

“…The second experiment was designed to simulate the transport of a dense plume in a freshwater aquifer. Such transport scenarios can occur near a leaking landfill discharging dense leachate into ambient groundwater (Oostrom et al 1992) or can occur when open dug wells (which are common in developing countries) or poorly constructed deep boreholes are inundated by seawater during catastrophic events such as tsunamis or hurricanes (Ilangasekare et al 2006;Carlson et al 2008). In this sinking plume experiment, a uniform freshwater flow field was first established to represent the ambient groundwater flow condition.…”

“…Stabledensity configuration problems usually involve a less-dense layer of fluid overlying a more-dense fluid layer; examples include saltwedge experiments (or analytical/numerical solutions) that consider lateral movement of salt water beneath a natural groundwater flow system (Cheng et al 1998;Simpson and Clement 2004;Goswami and Clement 2007;Abarca and Clement 2009), and salt-pool experiments that consider the upward movement of saltwater under pumping conditions (Oswald and Kinzelbach 2004). Unstable-density configuration problems involve a more-dense fluid overlying a less-dense fluid; examples include sinking dense leachate plumes in freshwater aquifers (Oostrom et al 1992;Simmons et al 1999;Simmons et al 2002;Hogan 2006), rising freshwater plumes in saline aquifers (Peterson et al 1978;Brakefield 2008), and sinking saltwater plumes that evolve from large-scale inundation events such as tsunamis and hurricanes (Ilangasekare et al 2006;Carlson et al 2008).…”