Appendix R

Typical Resistivities of Soils and Rocks

Material Ohm-Meters Ohm-Cent. Ohm-Feet

Wet to moist clayey soils 2 to 3 200 to 300 5 to 10

Wet to moist silty clay & silt soils 3 to 15 300 to 1,500 10 to 50

Well-fractured to slightly fractured

bedrock with moist cracks 15 to 150 1,500 to 15,000 50 to 500

Sand and gravel with silt 150 to 800 15,000 to 80,000 500 to 3,000

Slightly fractured bedrock with

dry soil filled cracks 300 to 2,500 30,000 to 250,000 1,000 to 8,000

Sand and gravel with layers

of silt 300 to 2,500 30,000 to 250,000 1,000 to 8,000

Massive bedrock 2,500 plus 250,000 plus 8,000 plus

Coarse dry sand and gravel 2,500 plus 250,000 plus 8,000 plus