The Northeast Ohio Regional Sewer District has reduced its raw sewage discharges into Lake Erie by 5o percent in recent years, but much work remains.
The sewer district, which treats 92 billion gallons of wastewater annually from Cleveland and 61 surrounding communities, discharged 4.5 billion gallons of raw sewage mixed with rainwater into the lake this year, said Kellie Rotunno, the sewer district’s director of engineering and construction.
“That’s half the levels of the 1970s but it’s still too much; it doesn’t comply with the (federal) Clean Water Act,” Rotunno said.
The sewer district is spending $3 billion over 25 years to reduce combined sewer overflows by 98 percent.
Combined sewer overflows, or CSOs, occur when rainfall overwhelms the city’s sewer system, which collects and treats sanitary sewage and stormwater in combined pipes.
CSOs are one of the most serious pollution problems facing the Great Lakes. The Northeast Ohio Regional Sewer District is under a federal court order to reduce its CSO volume of face stiff fines.
The district is digging 21 miles of deep storage tunnels, some of which will be 200 feet underground. Sewage and stormwater will be stored in those tunnels during heavy storms to prevent sewer overflows.
The sewer district is also investing heavily in green infrastructure — rain gardens, pervious surfaces and vegetated roofs — to reduce stormwater runoff.
Rotunno said installing green infrastructure instead of storage basins, so-called gray infrastructure, to capture excessive rain water could save the sewer district about $87 million. The green infrastructure will also beautify neighborhoods and commercial areas, she said.
The district must reduce stormwater runoff by 44 million annually to comply with federal regulations. That’s a tall order, Rotunno said, because 81 percent of the district’s service area is covered by pavement and other impervious surfaces.