Green roofs absorb and retain large amounts of rainfall and are effective at controlling and retaining stormwater. And now one more city structure has obtained one — the Jamaica Wastewater Treatment Plant.
A variety of hearty plants has been placed in a unique soil which sits on a drainage layer, absorbing rainfall and lessening the amount that makes its way into the sewer system that discharges into Jamaica Bay.
During heavy rain, the city’s sewer system often reaches capacity and must discharge a mixture of stormwater and wastewater, called a combined sewer overflow, into surrounding waterways.
The green roof can soak up to 13,000 gallons of stormwater annually, which will reduce runoff and the intensity of combined sewer overflows that damage the bay.
The large and small flowering plants, which include mountain sedum and white, tasteless and orange stonecrop, can withstand drought and are easy to care for.
The installation took approximately one month this past summer, at a cost of $30,000, according to Farrell Sklerov, a spokesman for the Department of Environmental Protection.
The entire roof is approximately 6,000 square feet, about half of which is covered with plants. For the first year, maintenance will be conducted by the general contractor. Within this period, the contractor will protect and maintain the plantings on the green roof, including watering, weeding, fertilizing and more. After the plants are well rooted, extended care is not necessary, Sklerov said.
“It’s really important that we avail ourselves of all opportunities to create green roofs,” said City Councilman James Gennaro (D-Fresh Meadows), chairman of the Environmental Protection Committee. “They help manage stormwater better and create less runoff. They are helpful in cooling down buildings by covering their tops with vegetation and mitigating the urban heat island effect.”
The urban heat island effect is the phenomenon in which temperatures are often a few degrees higher in cities than they are in surrounding rural areas with fewer buildings and less paved ground.
The addition of the green roof is part of the NYC Green Infrastructure Plan, which calls for $2.4 billion worth of such projects over the next 20 years in order to reduce combined sewer overflows and increase buildings’ absorption of ultraviolet light. Green roofs also improve insulation, interior cooling and energy efficiency.
“The city spends billions managing wastewater and air pollution and other issues associated with stormwater and the urban heat island effect and burning fossil fuels to generate electricity,” Gennaro asserted. “I believe green roofs are well worth the cost. It will produce positive tangible effects from this project and others like it.”
Green roofs are not the only way the DEP, which oversaw the project, is trying to better protect the city’s natural environment. It has also restored wetlands, eelgrass and oyster beds, as well as made investments in nitrogen reduction technology.
Opened in 1903, the Jamaica plant serves more than 700,000 residents, according to the DEP, treating an average of 80 million gallons of wastewater a day, and up to 200 million during wet weather.
The DEP treats the approximately 1.3 billion gallons of wastewater that New Yorkers produce every day. It is collected through 7,400 miles of sewers that push it downhill by gravity or through pumping into larger sewers called interceptors, which lead it directly to the city’s 14 wastewater treatment plants.