Groundwater flow, velocity, and age in a thick, fine-grained till unit in southeastern Wisconsin

Field characterization of hydraulic conductivity in a heterogeneous alpine glacial till

“…One widespread type of deposit, glacial till, consists of poorly sorted sediment laid down directly by retreating ice. A number of previous hydrogeologic studies throughout Europe and North America have focused on tills that were deposited by continental ice sheets (e.g., Hendry, 1988;Simpkins and Bradbury, 1992;Nilsson et al, 2001;Cuthbert et al, 2010). These tills are often compacted and clay-rich and therefore have very low hydraulic conductivity.…”

Characterizing the hydrogeology of a complex clay-rich aquitard system using detailed vertical profiles of the stable isotopes of water

“…The uppermost several meters of surficial aquitards are frequently oxidized and fractured. Investigations show that significant solute migration occurs in these fractured and oxidized zones (D'Astous et al, 1989;Hendry et al, 1986;Hendry and Schwartz, 1988;Jorgensen and Fredericia, 1992;McKay et al, 1993;McKay and Fredericia, 1995;Simpkins and Bradbury, 1992). In some cases, there is further evidence of hydraulically conductive fractures extending many meters below the visibly weathered zone (Keller and van der Kamp, 1986;McKay and Fredericia, 1995;Ruland et al, 1991).…”

“…The K of fractured media is typically inferred from additional evidence, such as detectable tritium levels at depths greater than the active flow zone, or from field observations of hydraulic responses (McKay and Fredericia, 1995). Many investigations of clay-rich aquitards in more northern climes rely on the distribution of stable isotopes of water (d 18 O, d 2 H) to provide information on groundwater flow, solute transport mechanisms, hydraulic conductivity, and the timing of climatic and geologic events Cherry, 1986, 1989;Fontes et al, 1986;Hendry, 1982;Hendry and Wassenaar, 1999;Remenda et al, 1996;Simpkins and Bradbury, 1992). These studies rely on the fact that water in glacially deposited clay sediments originally had d 2 H and d 18 O values significantly less than that of modern precipitation.…”

The Influence of Anthropogenic Contamination on the Groundwater Chemistry of a Semi-confined Aquifer (The Wielkopolska Buried Valley Aquifer, Poland)

“…In regions where the intensive exploitation of groundwater does not take place, contamination may take places when a natural downward gradient occurs. The contamination of groundwater may appear even if the aquifer is overlain by a thick confining layer (Simpkins and Bradbury 1992). This is particularly the case in long-term sources of contamination influence, which date back even as far as previous centuries (e.g.…”