Browsing by Author "Alexander, E. Calvin, Jr."

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    Information Circular 36. Radium in the Mt. Simon-Hinckley Aquifer, East-Central and Southeastern Minnesota
    (Minnesota Geological Survey, 1992) Lively, R.S.; Jameson, Roy; Alexander, E. Calvin, Jr.; Morey, G.B.
    Studies conducted in the 1960s showed that radium was a fairly common constituent in ground water throughout much of the Midwest. Concentrations of 226Ra ranging from 1 to 80 pCi/L (picoCuries per liter) were found in northern illinois, Iowa, and eastern Wisconsin (Rowland and others, 1977). The high radium values were associated with water from deep sandstone aquifers of Cambro-Ordovician age, but not with aquifers above or below. Additional studies and reports of radium in the Cambro-Ordovician aquifers by Gilkeson and Cowart (1982, 1987), Hahn (1984), and Weaver and Bahr (1991) further delineated distribution patterns and have suggested sources for the observed concentrations. Radium is a naturally occurring radioactive element, formed by radioactive decay of uranium and thorium. The most abundant radium isotope, 226Ra, has a half-life of 1600 years and is part of the 238U decay series. Two other isotopes, 228Ra (half-life = 5.76 years) and 224Ra (half-life = 3.7 days), are part of the 232Th decay series. In 1976, the U.S. Environmental Protection Agency published regulations that established contaminant levels for radioactivity and radioactive nuclides in public water systems. The maximum contaminant level (MCL) for gross alpha activity was not to exceed 15 pCi/L and the combined 226Ra and 228Ra activity in the water was not to exceed 5 pCi/L (Federal Register, 1976). The U.S. Environmental Protection Agency is reviewing the contaminant levels for radioactive nuclides in drinking water. Testing of public water supplies by the Minnesota Department of Health showed that many communities in the southern half of Minnesota were not in compliance with the drinking water standards for radium. Sampling of some municipal wells indicated that high radium levels were chiefly associated with water from the Mt. Simon-Hinckley aquifer, a sandstone aquifer of Late Cambrian/Middle Proterozoic age. A few wells in the Jordan Sandstone of Late Cambrian age also showed elevated radium levels. Because these data were obtained from municipal wells in communities with known radium problems, it was difficult to detect a pattern or to isolate specific radium-producing horizons within the aquifer(s). Therefore, the Minnesota Geological Survey sampled water from sole-source Mt. Simon-Hinckley wells to identify the distribution of radium within the regional geologic framework. Base-level data were also acquired on other radionuclides, the age of the water, and the water chemistry. Sole-source Mt. Simon-Hinckley wells were selected for sampling based on existing water-well information, and included wells previously monitored by the Minnesota Department of Health. The study area extended north to south from the town of Hinckley to the Root River basin, and west to east from the Mankato area to the Mississippi River. Complete coverage could not be obtained because of a lack of sole-source Mt. Simon-Hinckley wells in the south-central part of the aquifer. Several Jordan aquifer wells were also selected for sampling. The data accumulated in this study provide a starting point for selecting mitigation strategies or for choosing appropriate sites for future wells.
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    Integration of Water Tracing and Structural Geology for the Delineation of Springsheds
    (Minnesota Ground Water Association, 2012-10) Ustipak, Kelsi; Green, Jeffery A.; Alexander, E. Calvin, Jr.
    Fountain, Fillmore Co., Minnesota, a small town self-identifed as “The Sinkhole Capitol of the U.S.A.,” is located on a large sinkhole plain in the Upper Ordovician Galena Group. Recent mapping of the structural setting in the Fountain area provides new constraints for the interpretations of flow paths in springsheds defined by three decades of dye traces (Runkel, 2012, private communication). The strata of the Galena Group are deformed into a low-angle, assymetric syncline that is plunging northwest. The Fountain East dye traces, initiated in May 2012, were designed to further refine springshed boundaries on the northern edge of the sinkhole plain and to delineate source areas for cold-water springs that feed Minnesota designated trout streams in the area, particularly Rice Creek. Two major springsheds were previously mapped in the Fountain East area: the Fountain Springshed, which drains northwest and forms the headwaters for Rice Creek; and the Mahoney Springshed that drains southeast to form the headwaters for Mahoney Creek. The newest tracing efforts begin to document a new springshed to the northeast of Fountain feeding Klomp’s Spring and ultimately Rice Creek. The integration of dye trace data, structural contours, and ArcGIS imagery contextualizes the regional subsurface flow and further provides evidence for the delineation of the Fountain, Mahoney and Klomp Springsheds. Knowledge of the structural setting of the Fountain East trace area is a significant step in answering broader questions regarding the hydrogeologic behavior of the Galena Group karst system and its role in the productivity of designated trout streams.
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    Karst Features of Minnesota
    (Minnesota Geological Survey, 2002) Alexander, E. Calvin, Jr.; Tipping, R.G.
    Southeastern Minnesota is part of the Upper Mississippi Valley Karst (Hedges and Alexander, 1985) that includes southwestern Wisconsin and northeastern Iowa. Karst lands in Minnesota are developed in Paleozoic carbonate and sandstone bedrock. A significant sandstone karst has developed in Pine County (Shade and others, 2001). Most surficial karst features such as sinkholes are found only in those areas with less than fifty feet of sedimentary cover over bedrock surface (Gao and others, 2002). Since the early 1980s, the Minnesota Geological Survey and Department of Geology and Geophysics at the University of Minnesota have been mapping karst features and publishing various versions of their results in the form of 1:100,000 scale County Geologic Atlases. In the mid 1990s, the Minnesota Department of Natural Resources was assigned responsibility for the hydrogeology portions of the County Atlases and is now responsible for the karst mapping. Dalgleish and Alexander (1984), Alexander and Maki (1988), Witthuhn and Alexander (1995), Green and others (1997), Shade and others (2001), and Tipping and others (2001) published sinkhole distribution maps for Winona, Olmsted, Fillmore Counties, Leroy Township, Pine and Wabasha Counties respectively. Published Atlases of Washington, Dakota, and the counties of the Twin Cites Metro area contain limited information on sinkhole occurrences. A karst feature database of Southeastern Minnesota has been developed that allows sinkhole and other karst feature distributions to be displayed and analyzed across existing county boundaries in a GIS environment. The central DBMS is a relational GIS-based system interacting with three modules: spatial operation, spatial analysis, and hydrogeological modules. Data tables are stored in a Microsoft ACCESS 2000 DBMS and linked to corresponding ArcView shape files. The current Karst Feature Database of Southeastern Minnesota was put on a Citrix Window 2000 server accessible to researchers and planners through networked interfaces. The karst inventory points were point features such as sinkholes, springs, and stream sinks extracted from the karst feature database of Southeastern Minnesota. Both inventory points and karst feature database are updated on regular basis. This research was supported with funding from the Minnesota Department of Health.
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    Measurement of Flow through the Unsaturated Zone Using a Prototype Funnel Lysimeter
    (Water Resources Research Center, University of Minnesota, 1994-05) Alexander, E. Calvin, Jr.; Foster, Michael B.; Misra, D.; Nieber, John L.
    Prototype funnel lysimeters were constructed using 2-m dia. tree transplanting equipment. This equipment offers a possible means for quantitative, practical, and cost-effective measurement of flow in the unsaturated zone at the meter scale. The objective of this investigation was to develop and test the funnel lysimeter as a practical field methodology to conduct controlled quantitative tracer tests on large undisturbed soil samples. The steps to achieve this objective were to develop a working prototype, conduct tracer tests at sites with different field soils and a repacked soil in the laboratory, determine the characteristics of tracer breakthrough curves for the test soils, and assess the degree to sample disturbance caused by the lysimeter installation process. Lysimeters were installed by temporarily excavating a 2-m(3) soil sample using the tree transplanter and then replacing the sample after the installation of a sump and funnel-shaped impermeable liner. Tracer experiments were then carried out by applying solutes at the surface and sampling from the sump using an automatic sampler. Seven funnel field lysimeters were installed in Minnesota over two field seasons in three different soil types. Experiments identified two distinct flow types: preferential and matrix flow. In a typical field experiment with the preferential-flow soil, discharge at the lysimeter sump occurred within 15 minutes of the start of a six minute tracer application; discharge of the tracer stated after 23 minutes. For the matrix-flow soil, discharge to the sump typically took several hours to respond to tracer application. Drainage to the sump in the same cycle was composed of 100% antecedent water. The installation method does not lead to major disturbance of the soil but is more effective in sandy soils. The experimental results indicate that the funnel lysimeter methodology is suited for wide application in subsurface hydrology because of its large sample size, a time scale resolution of minutes, and mass balance control. Essential technological improvements to the lysimeter and further tracer experiments are required to fully define the lysimeter flow characteristics.
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    OFR 07-07, Bedrock geology, topography, and karst feature inventory of Steele, Dodge, Olmsted and Winona Counties
    (Minnesota Geological Survey, 2007) Tipping, R.G.; Mossler, J.H.; Alexander, E. Calvin, Jr.; Gao, Y.; Green, Jeffrey A.; Alexander, S.C.
    Final Project Report Regulating contaminant sources and addressing remediation of contaminated sites is difficult in sensitive karst areas because of the unpredictable nature of groundwater movement in solution-weathered bedrock. In this project, the Minnesota Departments of Health, Natural Resources and the Minnesota Pollution Control Agency partnered with the Minnesota Geological Survey and the Department of Geology and Geophysics – University of Minnesota, to develop better tools to understand and manage point and non-point sources on contamination in karst terrains. Contaminant Management in the Karst Region Contract with MGS, also includes summary information for 319 Karst Demonstration Project
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    RI-61 Hydrogeology of the Paleozoic bedrock in southeastern Minnesota
    (Minnesota Geological Survey, 2003) Runkel, A.C.; Tipping, R.G.; Alexander, E. Calvin, Jr.; Green, Jeffrey A.; Mossler, J.H.; Alexander, S.C.
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    South Orion Township Dye Trace
    (2021-09) Barry, John D.; Larsen, Martin R.; Stacken, Jacob C.; Stacken, Adele C.; Stacken, Ansel A.; Alexander, E. Calvin, Jr.; Green, Jeffrey A.