Well Drilling Contractors & Geology Near Sioux Falls, South Dakota

Depth (Feet)	Formation Type	Description	Characteristics
0 – 2 ft	FILL	Mostly silty sand or silty clay; dark brown or black; some sites report gravel or asphalt cap; urban fill.	Color: Brown or black Hardness: Soft
2 – 5 ft	FILL to CLAYEY SAND / SILTY CLAY LENS	Fine to medium silty sand and/or silty clay, variably mottled; alluvial or glacial in origin.	Color: Brown, dark brown, gray Hardness: Soft to medium
5 – 10 ft	GLACIAL OUTWASH / SILTY SAND	Silty, medium to coarse sand with occasional clay or gravel lenses. Partially water bearing at base.	Color: Light gray, tan, brown Hardness: Medium
10 – 17 ft	COARSE SAND/GRAVEL AQUIFER	Medium to coarse sand, some gravel, often moist to wet, main water-bearing zone; can extend to 22 ft.	Color: Gray brown to tan Hardness: Loose to moderately firm
17 – 22 ft	SAND AND GRAVEL (AQUIFER BASE)	Coarse sand and gravel, saturated, high permeability, principal aquifer for wells in this area.	Color: Gray, tan, or brown Hardness: Loose

Depth (Feet)

Formation Type

Description

Characteristics

0 – 2 ft

FILL

Mostly silty sand or silty clay; dark brown or black; some sites report gravel or asphalt cap; urban fill.

Color: Brown or black
Hardness: Soft

2 – 5 ft

FILL to CLAYEY SAND / SILTY CLAY LENS

Fine to medium silty sand and/or silty clay, variably mottled; alluvial or glacial in origin.

Color: Brown, dark brown, gray
Hardness: Soft to medium

5 – 10 ft

GLACIAL OUTWASH / SILTY SAND

Silty, medium to coarse sand with occasional clay or gravel lenses. Partially water bearing at base.

Color: Light gray, tan, brown
Hardness: Medium

10 – 17 ft

COARSE SAND/GRAVEL AQUIFER

Medium to coarse sand, some gravel, often moist to wet, main water-bearing zone; can extend to 22 ft.

Color: Gray brown to tan
Hardness: Loose to moderately firm

17 – 22 ft

SAND AND GRAVEL (AQUIFER BASE)

Coarse sand and gravel, saturated, high permeability, principal aquifer for wells in this area.

Color: Gray, tan, or brown
Hardness: Loose

Well Drillers Near Sioux Falls, South Dakota