About 178,000 gallons of sewage was not treated by Aberdeen’s wastewater treatment plant during Tropical Storm Isaias due to the surge of water making its way into the system, coupled with residents’ illegal connections to the system, city officials said.
Though that sounds bad, director of public works Kyle Torster said the system worked much better than before, and that the diluted sewage was unlikely to make it into any named tributaries and Maryland waters. With the exception of this backup, the system has handled significant rains well this year, Torster said. That has not always been the case.
The city’s sewer system backed up on Aug. 4, when Isaias rolled through Maryland, between 9:45 a.m. to 2:30 p.m. near the areas of James and Rogers streets, according to a public service announcement from the city. The overflow in the collection system spilled into the stormwater system and ran through a few miles of stormwater drainage ditches toward Romney Creek. The affected streets were cleaned up by city crews, the posting states.
Over the course of the storm, 4 inches of rain fell on city property, some making its way to the city’s treatment plant, Torster said. One of the contributing reasons for the volume flowing through city pipes was residents’ illegal connections via sump pump and other means — hooked directly to the city’s lines and pumping rainwater into the sewer system.
“About 180,000 gallons did not even get to our sewage treatment plant to be processed — the collection lines were full,” Torster said. “Because of the illegal connections, you have storm water that residents push in through a sump pump, so you get rainwater mixed with sewage.”
Per the city’s code, illegal connections can be punished by fines, civil processes and even criminal prosecution, Torster said.
“Under the city code it is illegal for residents to connect storm sewer water or groundwater to the sewage system,” he said.
Aberdeen has two distinct systems for handling stormwater and wastewater, Torster explained, unlike Baltimore City, which handles both in one system. Stormwater is not treated in Aberdeen, whereas wastewater is.
The city has noticed a strong correlation between the volume of water rushing through city pipes and rain events, Torster told the city council at its Monday meeting, a correlation suggesting that residents had hooked pumps up to the wastewater system and overwhelmed it. The collection pipes were filled, causing the backup, though the city did not receive reports of any backups inside any homes.
On a typical day, the city processes about 2 million gallons of wastewater a day, but the flow rates at the peak of the storm were about 20 million gallons.
“We know that residents independently have contributed to this,” he said.
The city’s next step will be to find illegal connections to the system, though that process is difficult, Torster explained, without going into residents’ homes and checking their basements, where sump pumps are often located. Even with the backup, he said the wastewater system handled the storm effectively.
“Our next plan is trying to identify the illegal connections to remove sump pumps and stuff like that from the sewer lines,” he said.