CITY COUNCIL'S messy killing of the deal for UIL Holdings Corp. to buy the city-owned Philadelphia Gas Works is a nasty gift that just keeps on giving. This week, the Public Utilities Commission, the state agency charged with overseeing the state's utilities, including their safe operation, renewed its concerns about the city's aging cast-iron gas mains, and suggested that the $18 million payment that PGW makes to the city each year should be directed to gas-main replacement.