Why Sewage Plants Are Especially Vulnerable to Climate Change
Approximately 11 billion gallons of untreated (or only semi-treated) waste spilled into waterways after Sandy, according to a new report from the environmental group Climate Central. The vast majority of that overflow occurred in the rivers and bays surrounding New York and New Jersey. Forgive us if we order sparkling the next few days.
Sewage treatment plants are "especially vulnerable" to problems in the climate change era, write the report authors. Unlike housing and transportation, which are nice to have near the coast but technically movable, the very function of sewage plants all but requires them to locate near waterways. A low-lying placement lets gravity do some of the work piping waste into plants, and proximity to water makes it easy to flush the plants of treated sewage.
When a storm surge arrives, the plants have little choice but to re-route sewage — untreated or only partially treated — directly into the water to avoid flooding. Otherwise the facilities are at risk of flooding from the inside, too, if water builds up in the discharge pipes. That's on top of the general problems of power outages, not to mention damage that could occur to pumps and holding tanks.
Four of the five worst Sandy-related sewage overflows occurred in New York and New Jersey, according to Climate Central. (The fifth, on O Street in Washington, D.C., was mostly the result of excessive rain.) A five-foot wall of water caused 840 million gallons of untreated sewage to flood a plant in Newark. At least 2.2 billion gallons of semi-treated sewage made its way into the Rockaway Channel from the Bay Park sewage facility on Long Island.
The best part of the overflows may be how well officials handled them. The Climate Central team writes that plant workers "did everything they could to minimize damage" — with most plants resuming treatment within hours of the storm's conclusion. Even with such a strong response, some spillage was reported as recently as January, several months after the storm, and damage estimates reached $2 billion in New York and another billion in New Jersey, just for repairs.
So what can be done? The answer begins, in part, with the combined water-waste sewers that exist in many older cities across the country. Combined sewers are a particular hazard because they increase the chance that waste will intermingle with storm water and be sent, untreated, out to sea. In New York alone there are 966 combined sewage outfalls, according to the Environmental Protection Agency, many of them forming nearly a ring around the Manhattan coast [PDF].
For years the EPA has been trying to raise awareness of the combined sewers that serve some 40 million Americans. The agency has outlined nine control measures to limit the danger posed by combined sewers — risks that range from public health hazards to beach closures. Ultimately, though, it's up to the states to implement these efforts, and generating public interest can be a challenge. Still some places have been up to the challenge.
Coastal cities wishing to move in this direction might look to Portland, Oregon, as a model. In late 2011, the city completed a 20-year combined sewage system overhaul that eliminated at least 94 percent of annual overflows to nearby waterways. Portland's pipe program had a $1.4 billion price tag, so addressing the problem elsewhere will require a significant taxpayer commitment. City residents prefer to keep sewage out of sight and out of mind (as the photography of Michael Cook showed us earlier this week), but probably not as much as they prefer to keep it out of water.