USGS

Biodegradation of Chlorinated Ethenes at a Karst Site in Middle Tennessee

Table 3. Geologic and hydrologic units at the study site

 

Stratigraphic unit

Lithology1

Thickness at study site2 (meters)

Hydrogeologic characteristics at study site2

Regolith

Low permeability clay

1 to 6

Shallow water-bearing zone near top of bedrock.

Lebanon Limestone

Relatively pure limestone with beds averaging 5.1 to 7.6 cm in thickness. Limestone beds are separated by partings of calcareous shale ranging from 0 to 1.3 cm in thickness.

6 to 24

Leaky confining unit

Upper Ridley Limestone

Relatively pure, massively bedded limestone with little insoluble material. Beds ranging from 10 to 120 cm in thickness.

31

Karst aquifer

Thin-Bedded Member

Relatively pure limestone with beds 1.3 to 10 cm in thickness. Limestone beds are separated by thin partings of calcareous shale.

9

Confining unit

Lower Ridley Limestone

Similar to upper part of the Ridley Limestone

6

No water-bearing zones

Pierce Limestone

Thinly bedded limestone. Beds average 5.1 cm in thickness. One or more units of massively bedded limestone may be present. Limestone beds are separated by thin partings of calcareous shale as much as 1.3 cm in thickness.

9

Confining unit

1 From Wilson, 1949.

2 From J.J. Farmer and E.F. Hollyday, U.S. Geological Survey, written commun., 1999.


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