From Bicycles to Wooden Beams: The Weird Stuff Found in City Sewage
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Version 0 of 1. Q. We all know the urban legend about baby alligators being flushed down the toilet, and the all-too real issue with wet wipes, but what other weird things end up in the sewer system? A. Of the nondegradable debris the city has to remove from sewage before treatment, wipes make up about 80 percent, said Vincent Sapienza, the commissioner of the Department of Environmental Protection. The other 20 percent occasionally includes some head-scratchers. On a recent morning, Mr. Sapienza led a small group on a tour of the Newtown Creek Wastewater Treatment Plant in Greenpoint. Situated along the Superfund-listed waterway of the same name, the Newtown Creek plant is the largest of the department’s 14 treatment facilities. It is designed to handle as much as 700 million gallons of wastewater each day. Several stories underneath the treatment plant’s surface, a river of locally sourced sewage flows through a grate designed to catch nondegradable debris. A large “rake” pulls the debris up to ground level, where it deposits the captured material on a platform for landfill disposal. Zainool Ali, the plant’s superintendent, said the recent building boom in North Brooklyn has led to an uptick in construction materials. He laughed while recalling a long wooden beam that had recently been caught in the grate; a twisted piece of metal, possibly once part of a guardrail, lay on the floor nearby. While potentially amusing, these foreign items can cause serious damage to the plant’s infrastructure. Autumn can be a particularly trying time: the Newtown Creek plant filters enough leaves to fill a 30-yard Dumpster every 30 minutes, Mr. Ali said. So how did these materials end up in the sewage system? In some areas, including wide swaths of southern Brooklyn and eastern Queens, street-level runoff is piped directly into local waters. The majority of the city, however — including the areas served by the Newtown Creek plant — uses a “combined” sewer system, which mixes this runoff with household waste. One advantage of the combined system is that it captures pollutants like gasoline and motor oil — not to mention wooden beams and metal rails — that manage to find their way into runoff drains. The downside is that too much rain or melting snow can cause the combined system to exceed capacity. When that happens, the system has no choice but to release untreated sewage directly into nearby waterways, an event called an “overflow.” The city has sought to mitigate this problem in recent years by increasing the combined system’s capacity. The system still averages around one overflow per week, releasing just under 20 billion gallons of raw sewage – most of it excess stormwater – directly into surrounding waterways each year. The system now retains more than 80 percent of the sewage that enters it on rainy days, up from 30 percent in 1980. While the design explains most of the weird, larger stuff that ends up against the grate, from time to time the Newtown Creek plant will receive an item that baffles even the most experienced veteran. The most recent example: a child’s bicycle, fully intact. “We have no idea how it got in,” Mr. Ali said. |