Case histories are presented where polyethylene encasement and cathodic protection have been used
together to effectively conwol external corrosion of ductile iron pipelines in very corrosive soils. This
practical and cost effective strategy capitalizes on the synergistic effects of these two established
corrosion control techniques. Pipeline designs dating back to at least the 1970s for over 300 miles of
construction have included this corrosion control methodology. The case histories include both
impressed current and galvanic anode protection. Non-invasive surface electrical potential
measurements and record reviews were used to determine locations for excavations to inspect the
condition of the pipe and polyethylene encasement.