Deer Island Sewage Treatment Plant

Deep beneath the waters of Deer Island, one of the largest wastewater treatment plants in the United States was under construction—an ambitious project meant to clean up Boston Harbor and protect the environment. But behind the engineering feat lies a much darker story.

In this episode, we explore the construction of the Deer Island Sewage Treatment Plant and the dangerous conditions workers faced while building massive underwater tunnels. We focus on the tragic deaths of two divers who lost their lives deep below the surface, operating in a pressurized, high-risk environment where one mistake could be fatal.

Sources:

https://www.loe.org/shows/segments.html?programID=15-P13-00023&segmentID=7

https://www.southcoasttoday.com/story/news/state/1999/07/22/two-workers-die-in-sewage/50511841007/

https://theworld.org/stories/2015/06/10/death-tunnel

https://www.mwra.com/your-sewer-system/sewer-treatment-facilities/deer-island-wastewater-treatment-plant

Transcript

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This project was supposed to save Boston Harbor. Instead, it cost men their lives. Welcome back to the Crash Lessons Podcast. I'm your host, Robin, and today we're going to take a look into one of Boston's biggest environmental wins, the Deer Island Sewage Treatment Plant. What was meant to be a landmark achievement, achievement in engineering and environmental restoration quietly became the setting for one of the most preventable tragedies in the project's history. So let's get into it. Why was Boston Harbor such a mess in the first place? For more than a century, Boston's system was great at collecting sewage and terrible at treating it. Starting in the 1880s, the region piped waste into the harbor islands and let the tide carry it away. First Moon Island, then nut and deer by 1940. So pollution piled up in the water and on the beaches. By the 1970s to 80s, closures of shellfish beds, sludge discharges, and storm overflows made the harbor a national embarrassment. The Clean Water Act put teeth behind cleanup, and court orders in the mid-1980s forced Massachusetts to rebuild the whole system, setting the stage for Deer Island's massive upgrade in the mistake that followed. Deer Island is located in Boston's Harbor and the location of the wastewater treatment plant. And we love to hear that. But we also know that good things aren't really the topic of this podcast. So we're going to talk about something great and how it turned not so great. Uh before we get into the not so fun part of the story. In 1884, the first sanitary sewer system was opened on Moon Island, which is one of the islands in the Boston Harbor, where it collected raw sewage from 18 cities in the Boston area and released it 500 feet from the shore. By 1889, the Metropolitan Sewage District was established, and over the next 15 years, they had built one of the best sewage systems in the country. The only issue was that they were still releasing the raw sewage collected from the cities into the ocean. 1940 came around, and now there were three points within the harbor from where they were collecting and releasing the raw sewage back into the Atlantic the Atlantic Ocean, Deer Island, Nut Island, and Moon Island. After all of the raw sewage was being released into the ocean, had contaminated the shellfish shellfish beds, and they had decided they needed to build treatment plants so that they weren't just releasing the raw sewage into the ocean and killing the environment. So there was the first law around dumping raw sewage passed in 1948, which really didn't do what it was intended. This law didn't give the federal government very much power, nor did it prohibit pollution. So it was hard to enforce this law when the government didn't have the power to, you know, enforce it really. Although with the implementation of this law, it did encourage people to do better and bring on the build of a better sewage system. It is not good enough to actually solve the problem at hand. Basically, it was just asking people to help out. If they didn't want to do their part, they wouldn't get any get in any trouble. The original Moon Island plant was then converted to overflow while the Nut Island plant opened in 1951. And then in 1968, the Deer Island plant opened. But these plants weren't really regulated and were still releasing sewage into the harbor that was harming the environment. Also, the pollution of Boston and surrounding area was just con pollution. It was the pollution was growing, but the population was continuing to grow, so it was just adding more to the problem every day. Since the current lot, um, and I put quotations around the law because it wasn't much of a law, clearly wasn't working. So another law was passed, the Clean Water Act in 1972. This law gave the federal government the ability to do what needed to be done to make sure the waters got the proper cleaning and treatment that it needed. Things didn't start happening right away though, naturally. It wasn't until the Metropolitan District Commission was sued for violating the Clean Water Act in December of 1982, which forced the court to set some pretty strict deadlines, but it got things in motion for sure. Um, just need to light a fire under their ass. In 1985, the Metropolitan Sewage District had a little rebranding and became the MWRA, which stands for Massachusetts Water Resources Authority. The MWRA spent the next 15 years fixing the water treatment system. All sewage would be treated and then released at the seafloor 9.5 miles or 15.3 kilometers from the shore. And so all of this brings us to the 1990s when the real trouble begins. The plant was made up of three pump stations that would lift the wastewater about 150 feet to the main treatment clarifiers where gravity would remove about half of the pollutants. Then the second treatment would use oxygen to activate microorganisms that consume the organic matter. The sludge left over from the treatments would be put in a 130-foot high egg-shaped digester, and the methane gas produced by the digester was actually burned to make steam and used to heat the treatment process as well as the plant. There were vertical riser shafts that led up to diffuser outlets on the seafloor, which is how the stream was released into the ocean. The pressure from the federal court to get the project done on time, or they would be in a direct violation of federal law, was ultimately what caused the fatalities. I want to talk a bit about what led them to making the decision and why a decision they did with removing the plugs, which ultimately led to the deaths. Before we get into what actually went wrong, it's important to understand just how high risk and complicated the final step really was. So that's so when I said at the beginning, like they were so close to getting through this without having anything bad happen. I mean, they were at the final step. Everything was like built, but they just needed to remove the plugs. Almost 10 miles long, carved deep into bedrock and sitting hundreds of feet below the ocean floor. When it was built, it had full ventilation, lighting, rescue lines, and safety systems running the entire length. But once construction wrapped up, all of that got pulled out, leaving the tunnel essentially a sealed airless concrete tube. No oxygen, no extraction fans, no backup systems, nothing. Anytime you send workers, especially divers, into a confined space, you're already playing with danger. But sending them nine miles into a tunnel with no breathable atmosphere, where a single equipment failure means instant unconsciousness, pushes the high the risk into a whole different category. At that distance, you can't just get out. You can't even turn around easily. It's not a tunnel you walk out of. It's a tunnel you escape from only if everything works perfectly. At this point in the project, it had worked it had to work perfectly. This wasn't optional maintenance. Removing the plugs was a final step that would allow allowed the entire$3.8 billion treatment system to actually operate. Until those plugs came out, the whole project was basically a giant, beautiful machine with no power cord still unplugged. With the power cords still unplugged. That's why the engineers were desperate. They had a legal clock running, winter storms approaching, contractors gone, no ventilation left, and no safe plan approved. Every decision was being made with pressure coming from above and deadlines closing in from all sides. This wasn't just a construction task. It was an engineering emergency. And when you mix urgency with a tunnel that long, that deep, and that dangerous, you get the situation these five divers walked into. So let's talk about the plan for the outfall tunnel and treatment for the plant. Um as was well thought. So let's talk about the oh, they messed that up, sorry. Um was well planned out by a group of engineers, um, and there were even multiple environmental studies conducted to choose the best design and location for the sewage treatment plant. The problem was the plan for when the outfall tunnel was completed, and to be quite frank, it was more so the lack of plan at all. They literally had not planned for what they were going to do. Once all of the construction was done to build the tunnel, all of the safety lines and everything was removed. During construction, they had ventilation systems in place and life support, which was removed when they were finished. Then they needed to remove the plugs. And instead of treating this process like an engineering task, they treated it like an operation or maintenance task. And because they were so pressured to have this done on time, they didn't stop to redesign a safe way of getting it done. The plugs were giant concrete barriers that were put in place to act as seal between the tunnel and the literal ocean. So if they didn't put the plugs in, then, well, everyone would have just drowned during the construction process of the tunnel. And now that it is done, the plugs needed to be removed. A big problem that overshadowed the safety of removing these plugs was the deadline for getting the project finished and up and running. This was literally a court order, so if they did not get this done on time, they would have been in violation of federal court orders and would result in some pretty big penalties. Financially, they were risking fines up to tens of thousands of dollars per day. They risked environmental lawsuits, and at this point the project had cost them$3.8 billion. So they were just very eager to get it done and get it up and running. It sounds like they had originally planned for the removal of these plugs when there was still ventilation in the tunnel, but that was but it was removed right after construction. So I'm not sure why they removed the ventilation so quickly before they had the chance to remove the plugs, but they did, and then they had to come up with another idea. They didn't take much time to think the plan through when they decided to hire five commercial divers and send them into this 9.5 mile-long tunnel with a with pressurized vehicles or Humvees as their air source. And I'm gonna talk a bit about the Humvee in a moment here because this was not something that was proven to work. Uh the air system they were relying on was not only improvised, it had never been tested in a real-world environment. And in a tunnel that had absolutely no oxygen left in it, that is basically a death sentence if anything fails. The system was supposed to mix liquid oxygen and liquid nitrogen into breathable air, but it had never been proven safe, never been used in a confined space this long, this deep, or this isolated. It meant the divers were trusting their lives to a machine no one had verified under pressure in an oxygen-starved tunnel, where even a momentary drop in oxygen levels would knock them unconscious almost instantly. There was no backup ventilation, no secondary line, no emergency escape route. If the system failed, there was no surviving it. And that's exactly why the setup was so incredibly dangerous. Instead of taking more time to come up with a logical plan for the plug removal, they almost just found a workaround and just went with it so it didn't cause any further delays. I have seen the system described as experimental, and this doesn't mean that they didn't know it was a dangerous task. It just means that they would rather risk people's lives than miss their deadline. Okay, so this takes us to July 21st, 1999, and they were just doing the finishing touch touches. The construction of the tunnel had been completed, and the last step was to remove the plugs that were put in during place, during put in place during construction. The plugs were to block off the diffuser which connected to the seafloor so that they were constructing the tunnel. Seawater did not get inside. But since the construction was all done in the tunnel in the tunnel and all the equipment and ventilation had been removed that there was no more oxygen, the plan was this. Have five commercial divers drive nine miles into the outfall tunnel using an untested air supply to retrieve the plugs so the outfall tunnel could fill up with seawater and the plant could release sewage. Seems pretty simple and straightforward, other than the part where I mentioned that they were using an untested air supply, which is going to prove to be a very bad mistake. Because the tunnel was so long, by the time they got to the end of the tunnel, they would have run out of oxygen in just their tanks. So the engineer they hired came up with the idea to mix liquid oxygen and liquid nitrogen in the tunnel and turn into breathable air when they did run out. Just to quickly clarify one thing, they had to hire an engineer at the end of the project specifically for removing the plugs because they did not include it in the original plans. In the transcript I was reading from Living on Earth, which is linked in my sources, they had referred to the engineer with this idea as a hotshot engineer. They also mentioned that there were a few engineers who came in and toured the place, but after a quick look, they said there was no amount of money that would entice them to want to take this job. So it obviously clearly was not an easy task, and it was definitely a very sketchy one for sure. So five five commercial divers, five men, were sent into the tunnel with a converted Humvee truck. Timothy Nordine, William Hughes, Dave Riggs, DJ Gillis, and Donald Hosford. A Humvee truck, if you didn't know, is a military four-wheel drive truck. The tunnel was far too long for the men to walk the whole way down, so especially with there being no air in the tunnel and a limited supply, not to mention the tools and equipment that they had to carry with them for the plug removal. They also needed to bring in the improvised air system, the untested, the untested improvised air system, um which was mounted to the Humvee truck. Near the end of the tunnel, the diameter got to be about five feet. So the truck would only go so far, and then three of the divers would be attached to hoses that attach to the truck, attached to the oxygen supply, while the other two divers stayed at the truck to watch the oxygen and make sure everything went smoothly. And they weren't make sure they weren't running out of oxygen or anything. Once they walked the rest of the way to the plugs, they had to actually crawl into a small tunnel to then reach the plugs. While they were deep in the tunnels and crawling around, they ended up getting entangled at one point, so they decided to take a moment and straighten themselves out. While doing this, one of the men looks over and sees another diver collapse. So he rushes over to him to switch on the emergency valve and then calls back to the truck to find out what the oxygen percentage is at. The level of oxygen in the air that they were breathing. The oxygen we breathe is 21%. Anything under 16 is fatal. So he called out to the guys at the truck asking what the oxygen percentage was at the end. They replied back, it's 8.9. Then the line went dead. Haas, Riggs, and DJ were the men at the plugs, and they rushed back to the Humvee to try and um revive Billy and Oh, I got his name wrong. Hold on, sorry. Um Billy and Timothy. I put time for some reason. Um unfortunately they were unable to revive them and still risk their own safety further. But making sure they got enough out but making it so that they could get everybody out of the tunnel. They weren't gonna leave the men there. These men weren't just workers, they were fathers, husbands, and experts in their field. They trusted the system to keep them safe, and that trust was broken. The job to remove the plugs in the end was not successful, and the three men three surviving men were taken to the hospital to be examined, where they were found to be okay. Investigation began immediately. Work on the outfall tunnel was halted the day of the accident while officials examined what failed in the oxygen starved tunnel, where two divers died after an apparent air supply failure, roughly 400 feet underground. What investigators found pointed to a chain of decisions at the end of an over-budget, behind schedule mega project. The tunnel's life support life support infrastructure had been removed even though the diffuser plugs still needed to come out. The team then relied on an improvised, untested breathing system in a confined space with no ambient oxygen. An environment where any drop in O2 could cause immediate unconsciousness. After the fatalities, regulators required a fundamentally different approach before anyone re-entered the tunnel. MWRA engineers designed an offshore ventilation plan using a jack-up barge and casein over a diffuser, pulling fresh air through the tunnel and out to the atmosphere. With full ventilation in place, crews safely removed the remaining 52 plugs in about five days, allowing the project to proceed. The cleanup ultimately finished and the outfall came online, but the victory was marked by loss. Survivors reported long-term psychological trauma, and the episode became a case study in how deadline pressure, cost overruns, and unproven tech can turn a near finish into a tragedy. Probably the biggest problem with this task, the completion of the plant and removal of the plugs, was the timeline and money they had to do it. The MWRA all gathered together and took the issue of money off the table to come up with a better idea of removing the plugs. And in the end, they come up came up with a way to get fresh air back into the tunnel and got the plugs removed. It sucks that in the end, all of the people who worked together to make this come to life are burdened by the deaths that came with it. If they had just put their differences aside and put a bit more thought or time into the final step, they would be able to celebrate the accomplishment. Because this was a big thing for the city of Boston's surrounding area. So that's it. So yeah, that wraps up today's episode. And I hope you guys liked it. And that's it.