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Please use this identifier to cite or link to this item: http://hdl.handle.net/11299/108892

Title: A Hydrogeologic and Mapping Investigation of the St. Lawrence Formation in the Twin Cities Metropolitan Area
Authors: Runkel, A.C.
Mossler, J.H.
Tipping, R.G.
Bauer, E.J.
Issue Date: 2006
Publisher: University of Minnesota
Series/Report no.: OFR
06-4
OFR
06-5
Abstract: This report summarizes the results of a two year project conducted by the Minnesota Geological Survey to map the Upper Cambrian St. Lawrence Formation and investigate its hydrologic properties in the Twin Cities Metropolitan area (TCMA). Funding was provided by the Minnesota Department of Health. Final products are a map delivered in electronic format that can be used with Arcview 3.2 GIS software, and this informal report. Our hydrogeologic study indicates that the St. Lawrence Formation commonly has a moderate to high horizontal hydraulic conductivity across all of the study area. In conditions of shallow burial beneath younger bedrock it is most similar in the development of secondary pores and measured hydraulic properties to fractured carbonate rock aquifers. Discrete intervals with secondary pores have a high horizontal hydraulic conductivity whereas rock between these intervals are orders of magnitude lower in conductivity. The properties of the St. Lawrence Formation in a vertical direction are not as wellunderstood, but available data are consistent with the traditional classification of the formation as an aquitard. However, the integrity of the formation as an aquitard in a vertical direction, particularly under conditions of shallow burial such as where it is uppermost bedrock, has not been rigorously tested, and may be markedly variable across the TCMA. This is chiefly because vertical fractures play an important role in determining aquitard integrity, and the distribution of such fractures is poorly understood. Suggestions for additional research that might lead to a better understanding of aquitard integrity are made at the end of this report.
Description: Minnesota Geological Survey (MGS) Open File Report 06-04 (pdf report) and Open File Report 06-05 (ArcView apr and files for map and map pdf)
URI: http://purl.umn.edu/108892
Appears in Collections:Open-File Reports

Files in This Item:

File Description SizeFormat
index[1].txtReadme1.62 kBTextView/Open
ofr_06_04[1].pdfOFR06-4 Project Report 8.36 MBPDFView/Open
ofr_06_05[2].pdfOFR06-5 Map Showing Location of St. Lawrence Formation7.16 MBPDFView/Open
ofr06_4_5_cstl[1].zipSupplementary GIS data and Project data16.04 MBZIPView/Open

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