On Friday Mappa, who manages Bridgeport’s outdated wastewater treatment system, led a handful of City Council members on a tour of the West Side plant. She will also participate Saturday morning in an online “workshop” to answer outstanding questions that legislative body has about a proposed $395 million facilities upgrade. A divided council earlier this month tabled a vote authorizing the Water Pollution Control Authority obtain a $276.5 million loan and receive $118.5 million in federal grants to expand the West Side plant’s capacity and design a future overhaul of the East End treatment site. After holding bills steady for several years, the WPCA increased the average household’s current yearly sewer cost to $490. And under what Mappa has called a worst-case scenario, that amount would rise to $816 by 2027 and $1,064 by 2033 to help pay back the $276.5 million loan.