Where The Wastewater Goes

Gary Zrelak, director of operations for the Greater New Haven Water Pollution Control Authority, wielded a several-foot-long plastic pipe with a valve at the end, which he nicknamed the ​“sludge judge.”

He was on a catwalk over the water draining out of the last of three enormous tanks at the East Shore Water Pollution Abatement Facility, taking a core sample of the 14-foot-deep pool. 

As he expected, below the surface, the water was still brown, tinted with matter that was settling slowly to the bottom of the pool. But the top three feet of water were clear — almost ready to be released into the New Haven Harbor on a cold winter day.

The tank — and the two preceding it, and the entire facility that runs them — ​“is connected to everyone, every household and commercial building” in a substantial part of the greater New Haven area, Zrelak said. ​“They have a toilet, they’re coming here.”

The East Shore wastewater treatment plant at 345 East Shore Parkway — which employs 57 people in operations, collections, maintenance, lab work, industrial pretreatment, and solids handling — is the endpoint for a system of 550 miles of pipes and 30 pump stations that serves New Haven, East Haven, Hamden, Woodbridge, and a small part of North Branford, conveying wastewater of about 35 million gallons a day from almost 200,000 people in total. 

The pump stations are needed ​“because there’s hills and ridges that you have to get up over,” said Zrelak. But ​“treatment plants are always at the lowest elevation in the community, and that’s because water flows downhill.”

Pipe Dreams, Pipe Realities

New Haven’s sewer system traces its origins back to about 200 years ago, when the first sewer line in the city was installed in the early 1800s and ran along Chapel Street. At that time most people had outhouses, or toilets that ran sewage out of the house and possibly into ​“whatever brook was over there,” Zrelak said. ​“This is when the solution to pollution is dilution.” 

The city’s raw sewage ended up in its rivers, which ​“have some assimilation capacity. They could take some of that,” Zrelak said. ​“But as the density of the city keeps growing, you’re getting more and more” sewage. 

In the 1870s, construction of a citywide sewer system began in earnest, with 60 miles of storm and sewer pipe laid by 1892. When you walk down Ella T. Grasso Boulevard, for example, ​“you’re walking on top of an 84-inch brick arched sewer,” Zrelak said. 

This pipe, which originally conveyed both storm and sewer runoff, runs all the way down to City Point, where it originally drained directly into the harbor. That pipe and others like it in the system improved public health by getting raw sewage away from people’s backyards and out of the rivers. By 1926, the expanding sewer system comprised 155 miles of pipe.

The city was cleaner as a result — but the harbor was not.

A 1915 study by the U.S. Bureau of Chemistry, a precursor to the Food and Drug Administration, found that New Haven Harbor was polluted enough with untreated sewage that it prohibited oysters harvested there from interstate commerce. The U.S. Public Health service, around the same time, declared the shellfish from the harbor unsafe to eat in warm weather and advised people not to swim in it due to high levels of bacteria. The following year, the city started looking into creating treatment plants, and built three: one in City Point at the end of the Boulevard pipe, one at the end of East Street, and another in the Annex.

These plants did ​“primary” treatment, Zrelak said, which is essentially a mechanical process. Water carrying sewage flows into the plant; ​“you bring it into a tank and you settle it out,” separating water from sludge. This method, Zrelak said, removes about half of the pollutants in the water, but ​“what’s still going out in the end is like a gray water. Yeah, it’s cleaner, but it has all your soluble and dissolved organics.” And in New Haven — as in many other places — primary treatment only is ​“what went on from the start of when they started doing treatment up until the 1970s.”

Following the Clean Air Act of 1963, the Clean Water Act — first enacted in 1948 but significantly revised and strengthened in 1972 — ​“mandated secondary treatment” of wastewater, Zrelak said. Secondary treatment is a biological process, requiring a plant with capacity larger than the facilities the city was running at the time. 

In response, the city built the current East Shore Water Pollution Abatement Facility. It took flow from the Annex main directly. The treatment plants in City Point and East Street, meanwhile, were replaced by pump stations that then ran wastewater into a main running along the harbor to the new Annex facility.

For most of the plant’s history, the city ran it under its Water Pollution Control Authority, even as it processed sewage from neighboring towns connected to the sewage system. But ​“inequities,” said Zrelak, in how different towns were charged — and how they paid — for their sewage service led first to a lawsuit between cities and then to serious talk about regionalizing the sewer system. With oversight from the state Department of Energy and Environmental Protection (DEEP), coordination among the municipalities resulted in the creation of the Greater New Haven Water Pollution Control Authority (GNHWPCA) in 2005.

A standalone nonprofit entity, the GNHWPCA issued a bond to buy the plant from the city and has been running it ever since, collecting revenue directly from property owners who have sewer hookups, billing them based on their water consumption. The authority is responsible for the entire system, which requires maintenance and upgrades, and sometimes involves responding to pipe failures.

In July 2020, a sewer main in Hamden collapsed, resulting in the spilling of 2.1 million gallons of raw sewage into the Mill River. The main failed due to ​“a lot of corrosion,” said Roger Reynolds, senior legal director at Save the Sound, which sued in 2021 for damages from the spill. The case was settled in 2022.

The lawsuit also resulted in collaboration between the GNHWPCA and Save the Sound. ​“Once we brought the suit we kept talking,” Reynolds said. It was a ​“collaborative atmosphere” that resulted in the GNHWPCA putting in sufficient safeguards to prevent another such spill. Reynolds recalled that about $200,000 were earmarked for bioswales to contain runoff, and the GNHWPCA spent above that to complete the project. 

“That was all positive, and they were good to deal with,” Reynolds said.

The East Shore plant itself has made numerous upgrades since it went online in the 1970s, in response to changes in environmental regulations, concerns from the community, and preparation for climate change. In the late 1990s it installed covers and scrubbers to mitigate odors. In 2014 it built its own electrical building to be able to continue running for four days even if the power grid goes down during a storm. More upgrades are coming in the foreseeable future. But its three-step process to turn raw sewage into two products — sludge that can be incinerated and water that can be released in the harbor — has remained largely the same since its beginning.

Pumped, Scraped, Consumed, Treated

When wastewater first enters the facility, it does so underground, about 30 feet below sea level, from the three mains that are the confluence of 550 miles of pipes. That water then gets pumped up and into three aboveground basins that are 14 feet above sea level. The first step in treating the water happens in these basins. 

Each basin has three bays, and each bay has ​“an endless chain on both sides of the loop with a fiberglass flight, a scraper,” Zrelak said, that ​“scrapes the bottom of the tank up to a trough.” The trough runs to pumps that bring the sludge into gravity thickeners, machines that separate out even more water, until the sludge is ​“about 5 percent,” or roughly the consistency of a ​“McDonald’s milkshake,” Zrelak said.

The scrapers also collect fats, oils, and grease (FOG) that have floated to the top of the water. ​“We have a highly technical term for it; we call it scum,” Zrelak said. The source of the scum is FOG from homes and restaurants pouring it down the drain. FOG ​“is a big issue in wastewater here.” Especially in cold water, it congeals in pipes, causing blockages that sometimes back the sewage ​“out a manhole” or ​“into somebody’s home.” Crews are constantly cleaning pipes at various points in the system, and restaurants are mandated to have grease traps. The FOG that makes it into the facility make the pumps work harder. 

“You make that nice Sunday morning breakfast, or fried eggs and fried bacon, and you got that nice grease in the pan when you’re done — what are you doing with that?” Zrelak said. Instead of washing it down the drain, the grease can be put in a can until it solidifies; then it can be thrown away. At the plant, some of the oil is added to the sludge before it’s incinerated.

The 14-foot elevation of the basins isn’t arbitrary. It’s at ​“the 100-year flood mark,” Zrelak said, ​“the standard to which this building was built back in the ​’70s.” With mounting evidence of climate change and sea level rise, standards have changed. A facility built today would accommodate for the 100-year flood level ​“plus three feet,” Zrelak said. The East Shore facility has compensated by building three-foot barricades, which is ​“approaching the 500-year flood mark for our area,” Zrelak said.

The three basins also have covers on them, installed in 1998 to control the odor. This is due, Zrelak said, to the basins’ proximity to a series of condominiums, visible through the trees in the blocks behind the plant. Before the GNHWPCA installed the covers, the condo residents had a ​“view of the pool,” Zrelak said wryly. They also had a whiff of the off-gassing from the basins that intensified in the summer. A particular gas, hydrogen sulfide — ​“that rotten egg smell,” Zrelak said — needed to be contained as a ​“good neighbor” policy. The covers cost $8 million, and the neighboring odor control facility, which does more odor remediation, ​“costs us around $250,000 a year in electricity and chemicals.”

The odor isn’t fully dissipated even after that. ​“I am told by people who use the park” — that is, East Shore Park, which borders the plant to the south — ​“that sometimes there are odors,” said Laura Cahn, chairwoman of New Haven’s Environmental Advisory Council. She stuck a balanced tone. ​“I hope the technology will improve,” she added, though ​“obviously we are not going to stop needing sewers.”

The human nose can detect hydrogen sulfide in increments of parts per billion, Zrelak said. ​“I think evolutionarily, you wanted to make sure you weren’t hanging out where you were going to the bathroom. So that’s an offensive smell to you,” and ​“we want to be a good neighbor.” Lingering in the air above the reality floated the question of whether, in a more perfect world, there would have been a ​“buffer zone” between the plant and residential buildings, especially given that the plant is itself built on fill that used to be a marsh. As it is, the physical proximity of the plant to residential and recreational places can’t now be changed easily.

The water that flows out of the primary tanks is gray water — water with soluble particles in it that have to be dealt with. It also has what Zrelak called ​“the raggy material, the toiletries. It’s everything” — tampons, condoms, and most of all, wipes. ​“They all say they’re flushable,” but that means only that ​“it’s going to make it out of your toilet.” Farther along the line, ​“they’re getting stuck on the propellers in our pumps, they’re clogging them up.” And if they make through the pumps and pipes, they get raked into a dumpster in the wastewater treatment facility. 

“We are not a manufacturing facility,” Zrelak said. ​“Anything you see here, it came from people in the system. What you flush down the toilet, dump down the drain, this is where it ends up, and then we’ve got to remove it.” The contents of the dumpster will end up in a landfill.

Meanwhile, the gray water that flows off the weir at the end of the primary basins journeys through pipes into the larger, secondary tanks, where it turns brown. This water is suffused with bacteria — which makes the gray water turning brown ​“a biological system,” Zrelak said, that the plant can use to help treat the water.

“We raise about 300,000 to 400,000 pounds of bacteria here” in the secondary tanks, Zrelak continued. ​“I tell the kids we’re farmers.”

The tanks hold 10.6 million gallons of volume, including the bacteria, and ​“we give them all the air they want to breathe down there, and we feed them all the food they want to eat” in the form of the soluble waste in the water. ​“They’re going to consume it. About 50 percent of it is going to get respired off as carbon dioxide in water, and the other 50 percent is going to get converted into cell structure — the biomass of the bacterial population.” That means that ​“we took something that was soluble, and dissolved, and converted it into a solid particle that we could now bring down into the clarifiers” — tanks that separate solids from liquids using gravity — ​“and settle. So now we can remove them from the water. That’s our magic that goes on here,” and ​“it’s completely natural.”

The musty smell from the secondary tanks makes sense; the bacteria in the tanks are the same ​“decomposers” that are ​“on the forest floor breaking down leaves, they’re in your lawn breaking down the grass clippings, and they’re over here breaking down the organic wastes” in the water, Zrelak said.

The other chemical compound in the wastewater that the bacteria consume is nitrates — the main culprit in algal blooms that often deplete the oxygen in seawater and thus kill other sea creatures. In the tank, ​“when the bacteria consume it, they release it off as nitrogen gas, into the atmosphere,” harmlessly; Earth’s atmosphere is about 78 percent nitrogen.

The bacteria consume the organic waste in the water through aerobic respiration, that is, consumption that uses oxygen, and nitrates through anaerobic respiration, that is, consumption that happens when there isn’t enough oxygen for aerobic respiration. By monitoring and controlling the size of the bacteria population in the tanks and the oxygen levels in the tanks, the plant staff can get the bacteria to process both the organic waste and the nitrates in the water, which brings the water much closer to the cleanliness standards set by the Clean Water Act to release it into the harbor.

But the water flows into a final set of tanks before that happens. As the water moves from the center to the edge of the tank, a last round of suspended material settles out. That’s when the the top three feet of water in the tank are, at last, clear to the eye. 

It receives a chemical treatment of sodium hypochloride, not unlike what happens in a swimming pool. 

When the water finally enters the harbor — spilling over the weir at the end of the final treatment tank, into a trough that feeds pipes that extend out to the edge of the shipping channel in the harbor — the total suspended solids in the water are under 30 parts per million.

Meanwhile, the sludge created at each point in the cleaning process is piped back across the street to the main facility. There, a centrifuge and a press squeeze water out of all of it, making a sludge pancake that is 25 percent solid waste material. That’s solid enough that the plant’s incinerator can burn it to ash, which then goes to a landfill.

Stress Tests

Most of the time, most days out of the year, the East Shore facility produces clean wastewater according to current standards. There are a few stressors on this system, however. A heavy rainstorm can tax the plant’s capacity by bringing it up to 100 million gallons of water in a day to process instead of the usual 30 to 35 million gallons. When that happens, not all of the water can be treated the same. 

“Everything still goes through the primary tank,” Zrelak said, removing half of the waste. But after that, any water over a 60-million-gallon-per-day threshold skips the secondary tanks and is blended together with the cleaner water in the third tank, chemically treated, and released into the harbor, with higher levels of organic matter and nitrates than usual.

The secondary tanks have to be skipped because the bacteria wouldn’t have time to process all of it, and because additional water would dilute the bacteria population. ​“If you get a rain event and we were doing 100 million gallons through here” through all three tanks, ​“you would be washing so much of your bacteria out that not only would you be failing for that day, but the next few days, while you reestablish your bacteria population again,” Zrelak said.

“People talk badly about it,” Zrelak continued. ​“But when we built these plants, we designed them for the normal dry weather flow. We take as much as we can” when rainstorms bring a lot more water, ​“and we’re going to be taking even more.” Upgrades in the works will ​“eliminate it from going out uncontrolled.” But even now, with the primary cleaning and the disinfectant, ​“that’s a lot better than raw sewage going out there.”

Climate change has put another stress on the GNHWPCA system overall, which is ​“an old system, a stressed system,” Reynolds said, even as the GNHWPCA puts ​“appropriate systems in place.” With rising sea levels and the threats of more intense storms, more rainfall, and hurricanes, the plant’s harbor location, essential to its function, makes it vulnerable. But addressing it ​“is not very easy,” Zrelak said. Moving the plant isn’t obviously feasible, especially given the elaborate network of pipes that feed into it. Expanding the facility to accommodate more rainwater is likewise difficult, as the plant tightly borders the harbor, a power plant, East Shore Park, and a residential neighborhood. 

Overall, the GNHWPCA has ​“done a decent amount of work with green infrastructure with our team in the past,” Reynolds said, a point echoed by Cahn. ​“I know they’re getting better infrastructure,” she said, and ​“obviously we are not going to stop needing sewers.” For Cahn, part of the answer to the question falls on everyone. In addition to the plant preparing for the future, ​“people need to be much more careful. We need to stop throwing out things where they don’t belong. We need to stop irrigating our lawns,” ​“start composting,” and ​“stop watering Astroturf. We need to do all kinds of things to take better care of the environment and then we will have fewer problems.”

At the plant, an upgrade involving a holding tank to disinfect overflow during a storm is on the horizon that will allow the plant to process 160 million gallons a day in a big weather event. The East Street pump station will receive a $60 million upgrade. And yet someday, more than 20 years from now, in some way or another, either the entire plant needs to rise in elevation — which is highly unlikely — or, at the end of the chain, ​“we’ll have to build a pump station and pump it out,” Zrelak said.

Either way, the problems of climate change encroaching on the plant have the same feeling of inevitability as the wastewater flowing in from New Haven and beyond. ​“It’s all coming to us,” Zrelak said.

And then there’s the chance that New Haven is hit by a hurricane that pushes enough water into the harbor to flood the tanks altogether, as happened during Hurricane Sandy farther south in New York and New Jersey. That requires shutting down the facility to prevent an electrical explosion. ​“You don’t want to have to replace the building,” Zrelak said. Once the flood has passed, ​“we’re not going to be able to turn it right back on.” 

The problem isn’t far from Zrelak’s mind. He was at the plant during Sandy and recalled the forecast initially calling for a direct hit on Connecticut. ​“If that thing had come up straight” along the coastline, instead of banking west, ​“it would have been a whole different story here,” he said.