Hydrogeology of a drift-filled bedrock valley near Lino Lakes, Anoka County, Minnesota
Journal of Research of the U.S. Geological Survey
By: T.C. Winter and H.O. Pfannkuch
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Abstract
The bedrock surface of east-central Minnesota is dissected by an intricate network of valleys. Outside the bedrock valley at site B, 3 mi (4. 8 km) from site A, 100 ft (30 m) of drift overlies the bedrock surface. Observation wells were installed at the two sites to determine the vertical ground-water movement between the various aquifer units and the lateral movement between the two sites. An aquifer test of the lowest valley-fill aquifer at site A showed that the observation well completed in the same aquifer as the pumping well responded immediately; whereas a lag of about 100 min occurred between the lower valley fill and uppermost body of sand and gravel. This indicates that the hydraulic connection between these two layers is poor at the immediate site. Test results show that the lower sand-and-gravel aquifer has a transmissivity between 14,000 and 27,000 ft2/d (1,300 and 2,500 m2/d). Although the hydraulic gradient is vertically downward in the valley, much of the drift fill is poorly permeable. This suggests that the quantity of downward-percolating water reaching the lowest valley-fill aquifer is relatively small at the test site. Because valley cut through a number of bedrock aquifers in the region, they could potentially be an important avenue of contamination from land-surface waste. In addition, the vast network of bedrock valleys in the Twin Cities area might cause contaminants to disseminate rather rapidly throughout a large area.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Hydrogeology of a drift-filled bedrock valley near Lino Lakes, Anoka County, Minnesota |
| Series title | Journal of Research of the U.S. Geological Survey |
| Volume | 4 |
| Issue | 3 |
| Year Published | 1976 |
| Language | English |
| Publisher | U.S. Geological Survey |
| Publisher location | Washington, D.C. |
| Contributing office(s) | Minnesota Water Science Center |
| Description | 10 p. |
| First page | 267 |
| Last page | 276 |
| Country | United States |
| State | Minnesota |
| County | Anoka County |
| Online Only (Y/N) | N |
| Additional Online Files (Y/N) | N |
| Google Analytic Metrics | Metrics page |