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Hydrologic Impact
Published in Mritunjoy Sengupta, Environmental Impacts of Mining, 2021
The surficial aquifer is unconfined and rises or falls in response to rainfall and discharges to streams and underlying aquifers. The water level of the surficial aquifer lies below the land surface generally from about 4 to 10 ft in the area of most of the gypsum stacks.
Hydrologic Impact
Published in M. Sengupta, Environmental Impacts of Mining, 2018
The surficial aquifer is unconfined and rises or falls in response to rainfall and discharges to streams and underlying aquifers. The water level of the surficial aquifer lies below the land surface generally from about 4 to 10 ft in the area of most of the gypsum stacks.
Value of groundwater to public supply in west-central Florida
Published in International Journal of Water Resources Development, 2022
There are five aquifers in Florida; the three that fall within our study area are the Surficial, Intermediate and Floridan aquifer systems (Figure 1) (Florida Department of Environmental Protection, 2015). The Surficial Aquifer System (SAS) is unconfined and can be found within unconsolidated sand, shelly sand and shell. Its thickness is mostly < 15 m but reaches 122 m in Indian River and St. Lucie Counties. Unlike the SAS, the Intermediate Aquifer System (IAS) is confined and is comprised of permeable layers of sand, shell and limestone separated by clay confining units. It is the main source of water for Sarasota, Charlotte and Lee counties. Lastly, the Floridan Aquifer System (FAS) is hosted within Late Palaeocene to early Oligocene limestone and confined by low-permeability Miocene clays. In west-central Florida the confining layer is absent. The actual volume of FAS is unknown, but its average thickness is 1000 m. FAS is by far the largest of all and is the main source of water for SWFWMD (Ferguson & Hampton, 2019).
Field-scale bioremediation of arsenic-contaminated groundwater using sulfate-reducing bacteria and biogenic pyrite
Published in Bioremediation Journal, 2018
Ming-Kuo Lee, James A. Saunders, Theodore Wilson, Eric Levitt, Shahrzad Saffari Ghandehari, Prakash Dhakal, James Redwine, Justin Marks, Zeki M. Billor, Brian Miller, Dong Han, Luxin Wang
There are four major hydrogeologic units that are generally recognized in the state of Florida: the surficial aquifer system, the intermediate confining unit, the Floridan aquifer system, and the sub-Floridan confining unit. The surficial aquifer system is made up of undifferentiated terrace-marine and fluvial deposits in the northern Florida panhandle and normally consists of clayey sands and gravels near the coast. Specifically in the study area, the surficial aquifer is mainly composed of quartz sand and gravel with occasional clayey sand and sandy clay lenses and extends from the surface to a depth of approximately 6–7.6 m. In the surficial aquifer, the water table typically occurs at approximately 1.5 m below the surface. Due to the shallow groundwater table and flat topography, modeling results show that groundwater flow direction can change with precipitation events (Starnes 2015). Historically at the site, groundwater flow direction has been to the northwest and west from the site and it migrates at an average rate of about 20 m per year. Organic material that manifests as dark brown zones is present in the surficial aquifer (Schmidt and Clarke 1980). There is a 0.9–1.5 m thick, laterally continuous layer of organic material in the quartz sand at a depth of about 1.5–3 m. This layer has been observed to thicken to the north (Schmidt and Clarke 1980). Groundwater from the surficial aquifer discharges into local streams or springs, or it may migrate into the deeper Floridan aquifer system where the two aquifer systems are hydraulically interconnected.
Three-dimensional hydrostratigraphical modelling of the regional aquifer system of the St. Maurice Delta Complex (St. Lawrence Lowlands, Canada)
Published in Canadian Water Resources Journal / Revue canadienne des ressources hydriques, 2018
Guillaume Légaré-Couture, Yves Leblanc, Michel Parent, Karine Lacasse, Stéphane Campeau
The paleodelta of the St. Maurice River is the largest aquifer in the region. The delta forms a wide sand-dominated fan over a thin layer of silty marine sediments on the east side of the river, and over a thick layer of pre-LGM deposits on the west side. Over the northern part of the delta, the unconfined surficial aquifer is thin and is less productive and not exploited, except for erosion channels where the sediment is thicker and the sands better sorted. The surficial aquifer has a much greater thickness in the southern part of the delta. Borehole FE-16-12 (Figure 7) contains almost 40 m of sand of varying grain sizes. A wood sample found at 29.8 m depth in the upper delta surface was dated at 8920 ± 50 BP (10.05 cal ka BP; Beta-318526). This date provides an age for the beginning of the construction of the St-Maurice delta in the Lake Lampsilis.