AW System Upgrade in Bridgeport, CT: EDI Keeps Solving Unique Challenges

The City of Bridgeport, CT is another example of EDI’s ability to provide unique solutions to its clients. The City of Bridgeport WWTP has six tanks with 113,562 m3/day capacity, with a peak flow of up to 189,270 m3/day. The city is part of ‘Long Island Sound’ protected water body cooperation effort that sets stringent discharge limits. The operating company running the plant for the city was struggling to meet those discharge limits; due to their 17-year-old ceramic disc diffuser aeration system that was failing both structurally and mechanically. The city was not only losing more than half a million dollars in annual ‘nutrient credit’, they were also facing penalties for not meeting their discharge permit. On top of that, inefficient energy usage was costing them money.

The city was waiting for the state revolving fund to take on the very competitive bid that EDI offered for a system upgrade. But it was taking a long time. To help the city with the funding issue, EDI came up with a unique payment mechanism with the operating company. It was an eight-year lease agreement that allowed the city to take on the project by making payments from their operating budget savings. Based on EDI’s model, the proposal stated that the city would be able to save over $250,000 per year from energy, against an annual installment payment of around $130,000 to EDI for the system upgrade.

Once the financing challenges for the project were sorted out, EDI faced the challenge to execute the project according to the city’s preference. The city agreed for only three days downtime for their tanks. Thus, EDI came up with the unique solution to put a fixed grid diffuser system with EDI’s high oxygen transfer efficiency MiniPanelTM fine bubble diffusers; installed over the top of the existing installation of the ceramic disc diffusers. EDI pre-assembled the laterals, de-watered the tank, installed the laterals on top of the ceramic diffusers, and watered the tanks back – all in the extremely cold weather of March 2017, when any remaining water in the tank used to turn into ice overnight. Against all skepticism, EDI pulled-off this task that everyone thought would be impossible. In addition, the new system can be served with one blower; whereas the previous system required two - with a third blower running occasionally. That reduced the power usage from 540 hp. to around 210 hp.

Glen Wylie, the Vice President of Infrastructure Services of EDI, confirmed that since the upgrade, actual savings are reaching well over the promised $250,000. The City of Bridgeport is currently in talks with EDI to upgrade another six-tank 37,854 m3/day plant that they have across the street.