Scientists say excessive nitrogen in waterways threatens ecosystems by sucking up dissolved oxygen. As a result, Rhode Island environmental officials tasked wastewater treatment plants with reducing nitrogen discharges. Now, as plants work to comply with that directive, it’s proving to be costly.
Last month, the city of East Providence officially broke ground on a $52.5 million project to upgrade its collection system and treatment plant. About half the money will go toward constructing a facility designed to cut nitrogen discharges in half. To pay for it, rates are expected to increase 27 percent to $584 annually for the average customer by 2014.
Elsewhere, the Narragansett Bay Commission, which serves 10 communities, is in the midst of a $59 million project to install a nitrogen-removal system at its Fields Point treatment plant. The commission is also designing an estimated $37 million project to reduce nitrogen discharges at the Bucklin Point plant. The projects will contribute to a rate increase that also stems from a larger project to separate sewer and stormwater lines.
In East Greenwich, the town opened a new nitrogen-reduction facility about three years ago. The facility, which reduces nitrogen discharges from 15 milligrams per liter to 5 mpl, came with an $8 million price tag. Sewer rates doubled and customers “were not happy,” Assistant Superintendent Shawn O’Neill said.
“It’s very difficult to make this fly with the taxpayers of your town when they don’t understand wastewater treatment from Adam,” he said.
Costly or not, plant operators have little choice under a 2004 state law that directed wastewater plants, as a whole, to cut nitrogen discharges by half. The R.I. Department of Environmental Management gave treatment plants individual reduction targets based primarily on where they discharged treated water.
“We picked a phased approach where we felt we got the largest reduction for the amount of investment,” said Angelo Liberti, chief of surface water protection at DEM.
Six treatment plants in the state have completed projects to meet their targets. Another two have largely completed the work required. Planning is in the works at two plants and construction under way at another two.