How to improve soil conductivity. Methods, materials, pros and cons.

Government-sponsored testing of various backfill grounding materials shows "coke breeze" as the number-one choice based on the conductivity as well as the cost. GTL Inc. completed tests for Fluor Daniel with results submitted to NEXRAD (Next Generation Weather Radar), a doppler weather radar project of a tri-agency (NWS, FAA, and U.S.A.F.). Findings indicate that of the three materials tested, only two were conductive when frozen with no moisture. Coke breeze was one of the two.

Backfill material is often used for mountain tops where grounding conditions are poor. Coke breeze offers a backfill solution since it can be compacted to 95% and offers the best conductivity at moisture levels between 5% and 20%. Above this level, the coke breeze came in a close second. The testing followed ASTM G 57-78 in performing the Wenner Four-Electrode Method of Soil Resistivity Measurement.

Coke breeze is a waste material from burning coke (byproduct from coal). It costs $0.024 per pound. The other tested materials cost as much as $1.06 per pound.