When 33 potential bidders expressed interest in August in vying for Philadelphia Gas Works as part of the city’s anticipated sale of the largest municipally-owned gas utility in the country, Ballard Spahr‘s Gregory L. Seltzer knew his client was in good shape.

But for Seltzer, who began working with the city of Philadelphia 13 months ago after his firm won an RFP to help shepherd the deal, the trickiest work was about to begin.