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Seismic-refraction study of suspected drift-filled bedrock valleys in Ramsey County, Minnesota

Water-Resources Investigations Report 85-4107

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Abstract

Seismic-refraction surveys were made across suspected buried drift-filled bedrock valleys believed to occur near two sites of known groundwater contamination--the Twin Cities Army Ammunition Plant (TCAAP) near New Brighton and the former Koppers Coke Plant, in St. Paul, Ramsey County, Minnesota. Refraction data were collected along two lines at each site; each line traversed the axis of a suspect valley. Drift-filled bedrock valleys were though to incise the Prairie du Chien-Jordan aquifer to an altitude between 500 and 560 ft above sea level at the TCAAP site. The interpretation of one seismic profile indicates that a valley probably does not exist under the area surveyed; the modeled depth profile shows the bedrock surface ranging between altitudes of about 700 to 780 ft. Interpretation of a second seismic profile just south of the TCAAP indicates that a shallow valley may exist under the northern half of the line; the modeled depth profile shows that the bedrock surface declines from an altitude of about 780 ft to about 690 ft over a horizontal distance of 400 ft. (USGS)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Seismic-refraction study of suspected drift-filled bedrock valleys in Ramsey County, Minnesota
Series title:
Water-Resources Investigations Report
Series number:
85-4107
Edition:
-
Year Published:
1985
Language:
ENGLISH
Publisher:
U.S. Geological Survey,
Description:
iv, 20 p. :ill., maps ;28 cm.