This is old and not in California, so it's probably an underestimate, but $2 million per mile to put power lines underground. https://www.elp.com/articles/powe

This is old and not in California, so it's probably an underestimate, but $2 million per mile to put power lines underground. https://www.elp.com/articles/powergrid_international/print/volume-18/issue-2/features/underground-vs-overhead-power-line-installation-cost-comparison-.html https://www.elp.com/articles/powergrid_international/print/v...