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A Hydrogeologic and Mapping Investigation of the St. Lawrence Formation in the Twin Cities Metropolitan Area
Runkel, A.C.; Mossler, J.H.; Tipping, R.G.; Bauer, E.J. (University of Minnesota, 2006)
 

Title 
A Hydrogeologic and Mapping Investigation of the St. Lawrence Formation in the Twin Cities Metropolitan Area

Issue Date
2006

Publisher
University of Minnesota

Type
Report

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.

Appears in Collection(s)

Series/Report Number
OFR
06-4
OFR
06-5

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)

Suggested Citation
Runkel, A.C.; Mossler, J.H.; Tipping, R.G.; Bauer, E.J.. (2006). A Hydrogeologic and Mapping Investigation of the St. Lawrence Formation in the Twin Cities Metropolitan Area. University of Minnesota. Retrieved from the University of Minnesota Digital Conservancy, http://purl.umn.edu/108892.


Content distributed via the University of Minnesota's Digital Conservancy may be subject to additional license and use restrictions applied by the depositor.