In the spring, we published an episode where we talked to two researchers where they described how wastewater testing can act as a coronavirus early warning system.
Since this show, this research has rocketed from a handful of labs at an unprecedented speed to many college campuses around the country as a frontline public health tool. Yes, wastewater was coming to the rescue. However, there was a problem. There was no official guidebook for implementing, using, or even communicating wastewater epidemiology on this scale.
We talk to Clemson University, the University of South Carolina, and Susquehanna University about this unprecedented effort.
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Transcript
Robert Osborne:
This is the Outfall, we share unique stories behind our waterworld and infrastructure. I’m Robert Osborne. In the spring, we published an episode where we talked to two researchers where they described how wastewater testing can act as a Coronavirus early warning system. It’s a radar. Since this show, this research has rocketed from a handful of labs at an unprecedented speed to many college campuses around the country as a frontline public health tool. Yes, wastewater to the rescue.
Robert Osborne:
However, there was a problem. As you’ll hear, there was no official guidebook or playbook for implementing, using, or even communicating wastewater epidemiology on this scale. We talked to three colleges about their efforts. Let’s start close to home with Clemson University.
Dr. David Freedman:
So what we did was crafted a plan whereby we would collect samples starting in late May before Memorial Day, while the university was under lockdown. And then that would give us a baseline to be able to judge what would happen as the university moved into different phases of operation. The initial plan was that we would monitor the headworks at the campus. If we saw an uptick in activity that we would then go upstream and start sampling manholes that service specific areas of the campus.
Robert Osborne:
This is Dr. Freedman, he is a professor and chair Clemson’s Department of Environmental Engineering and Earth Science. He is also leading Clemson’s efforts on wastewater surveillance on campus. The university campus actually has their own wastewater treatment plant, but like many other campuses, many students live off-campus. In Clemson’s case three-fourths of the students live off campus. Dr. Freedman helped push to include these off-campus students into the surveillance program by measuring wastewater at the city’s wastewater treatment plants. One of them is called the Cochran Road Plant, but this push provided something unexpected.
Dr. David Freedman:
The interesting thing that happened was we had several weeks of monitoring done on the campus and as expected during the lockdown where the flow rate through the campus headworks was a little under 50% of normal, the levels were close to or below detection. So then we went out to Cochran Road expecting to find a similarly low level of activity. And to my surprise, the first sample that we got back from Cochran Road was in the millions of copies per liter, which is a level that is consistent with a fairly large number of infected individuals and a fairly significant transmission rate. So right off the bat, where we were expecting to see a low prevalence of the virus in wastewater in the community treatment plant, we started off at a very, very high level.
Robert Osborne:
Around this same time, the City of Clemson was debating a mask ordinance. Dr. Freedman presented some of these initial results, which helped to pass the ordinance even before students all returned.
Dr. David Freedman:
Over the summer from late June when the mask ordinance was passed until the beginning or so of August, the levels in Cochran Road, in spite of them going up and down, the longer-term trend there was down and we were headed in the right direction there. You could infer that the mask ordinance was starting to make some inroads on the rate of transmission. And then students started to come back to Clemson. We, of course, started the semester virtually, but then there’s still students who rent apartments on an annual lease were showing up in August and we started to see levels go back up again. And then as we headed into September, when the dorm started filling up, that’s when the levels in the Cochran Road facility went up again and it’s also when we saw a major uptick in activity in the campus wastewater.
Dr. David Freedman:
In my view, it’s consistent with the fact that the virus well-established among the student population and to a lesser extent among the employees, and the faculty, the permanent residents. But yeah, the levels that we’re seeing are consistent with levels in other communities where there’s active transmission occurring. The really great value about the wastewater data is that it is a window into what’s happening on the entire campus or in the other wastewater treatment plants, what’s going on in the community. So we see the sum of all contributions. The university is doing a fair amount of testing, but it’s on the order of 5% of the population. And so there’s only so much coverage you can get at 5%, whereas the wastewater gives us a picture of the whole situation. And there’s something I like to say in which may sound silly, but I think it’s correct and that’s the wastewater doesn’t lie.
Robert Osborne:
In October, Clemson University had a peak of 5.2 million virus copies per liter. What? What Does that mean? Is that bad? What is the potential range of results?
Dr. David Freedman:
People from the get go are rightfully wanting to know, well, what did those levels mean? When you report levels of, for example, what does a copy per liter mean? What is it that you measuring and then copies in the tens of thousands or hundreds of thousands, or even millions of copies per liter? What exactly does that mean? So I think it’s been an interesting challenge to try to communicate that information in a way that’s informative without sounding alarmist. I came up with a system based on results reported for other communities, especially in Europe. Barcelona and in Paris, which were quite a ways ahead of the US in terms of their rollout of wastewater surveillance as a tool.
Dr. David Freedman:
There are great data sets there that looked at the prevalence of the virus in wastewater in relation to new cases and using that as a guide, as well as some results from cities like Boston and New Haven, which also were out front in this area. I’ve come up with a system of levels of concern to try to communicate what the concentration numbers can mean. You can guesstimate a theoretical limit that if everybody using the sewer system was shedding the virus at the highest rate that’s been reported in the medical literature, then we would end up with copies in the neighborhood of maybe 30 million copies per liter. So when you’re up in the tens of millions, you really got a lot of infected individuals.
Robert Osborne:
Next, University of South Carolina shares their story. USC is a similar size university, but the results have been different.
Dr. Sean Norman:
I guess we started very early, a little bit before the semester started so before the move-in date, we started testing sewage. We did have a backlog of some of the equipment or back order some of the equipment that we wanted to use for campus sample. And that was due to a rush of orders from universities around the country, trying to order autosamplers to be able take composite samples. So we started out our process here doing a kind of mix between composite, because we did have a few composite samplers that I was able to borrow from some colleagues on campus. So we were able to do a combination of composite samples, as well as grab samples. We have now since moved toward using all composite samplers. We’ve ordered up a bunch of composite samplers, and those have come in, so we’ve been using autosamplers across campus.
Dr. Sean Norman:
So we started doing this, I guess, early in the semester, right around move-in time and similar to what we’re doing on a larger scale statewide that we’re monitoring the campus twice a week at multiple locations. We have 11 locations around campus, that’s kind of a rolling location. As we see, and able to determine trends at some sites. Once we see there doesn’t appear to be any prevalence of a virus in certain sites, we shift those autosamplers to some other areas on campus to try to monitor and evaluate different areas of campus. So we’ve been doing this twice a week since early August.
Robert Osborne:
This is Dr. Sean Norman. He’s an associate professor in the Department of Environmental Health Sciences at the University of South Carolina. He’s also leading USC’s wastewater epidemiology effort.
Dr. Sean Norman:
We did go through a spike toward late August, early September when we were having several new cases identified every day and that was reflected in our sewage data as well. We saw spikes occurring roughly around the same time as we were getting pretty high spikes in case counts. That’s obvious if you look at our USC COVID Dashboard, you can see those cases, and then the same thing happened to sewage. Now I can say now, currently, our case counts are very, very low of active cases, and that is all reflected in the sewage.
Dr. Sean Norman:
Many of our sites have gone down to below detection limit and those sites that are still detecting some of virus are very, very low, which seems to be similar to what you’re seeing in the case count data on the COVID Dashboard. I mean, constant conversation with the administration, sending updates. And when we get updates in the sewer surveillance, I send those data to other people, who then if there is a need to, they deploy a kind of a rapid response or they call it a go team, that’s able to go in and test the saliva for individuals that are in certain buildings. And then, so we use it for kind of targeted individual level testing.
Robert Osborne:
Next we talk with Susquehanna University, where they share their story of how they adapted wastewater testing to campus life. Susquehanna is a private university in Pennsylvania that has an enrollment of a little more than 2000 undergraduate students.
Dr. David Richard:
So we’re doing these every two days on these 30 sampling stations. We are primarily sampling residences, dorm rooms or dorm buildings. We have pretty good resolution on them. Some we have better resolution than others because of the one sewer pipe might serve 200 students in one building, or serve 30 students in another building. So we’re somewhat restricted by the architecture of our sewage system. What we’re then doing when we get a hot wastewater test is… Oh, I should say, the samples are taken to an off-campus lab for analysis, PCR analysis. When we get a hot wastewater test, what we do is we call the students back into the dorm. So we have a communication system already set up for that, and we arrange for them to get personal tested the next morning. And so we have a team of they’re actually some of our athletic trainers, who will then set up camp outside of the dorm building.
Dr. David Richard:
Students will file out at their appointed time and get their throat swabs. Those things go off to another institution that is running the individual tests for us there. So we have three, I think so far, dorm buildings go hot on us covering probably several hundred students. And so we’ve been running these tests and to some extent, I think it’s been going pretty well. We had a couple of confusing results we managed to work through in the end. We have identified students who are hot using this test and have been able to then isolate those students away from everybody else for the up to 14-day isolation period. And so, yeah, I’m sure you can imagine there’s lots of logistics with not only the sampling process. Some days we have problems with low flow, other days we have problems with a blockage.
Robert Osborne:
This is David Richard, professor of biology, who is overseeing their COVID response. What has not been discussed so far are the limitations, trying to sample in an existing sewer system. Sewer systems weren’t made to monitor wastewater like this, and Chris Bailey, who’s the Director of Facilities discuss this and how they’re adapting their system to this type of monitoring.
Chris Bailey:
No one designed a sewer system with this in mind, with the idea that we would be opening up the system and taking ongoing samples from a running waste stream. It’s kind of a put and forget type of system. People build sewer systems to do one functionality and that’s move your waste away from your property and into a treatment facility. So we already had a good idea, we’d already done some survey work to know what was going to work, where we put these. And some of the physical makeups are, where can we isolate the residential space? So in cases where we have shared sewer lines, we have to find a place where only the waste is falling out from one residence hall. Because again, that resolution gets worse and worse, the larger and larger population we’re monitoring. We could put one at the end of our main outfalls to our campus, but that doesn’t give us really any actionable information. It would just tell us somewhere on your campus, you have a student who is expressing virus into the sewer system.
Robert Osborne:
Susquehanna has focused not only on testing, but how they’re going to respond to the positive test. Now, knock on wood, this has been successful for them.
Chris Bailey:
As we know, as the epidemiologists are telling us, the faster we can respond to known positives and likely positives, the better chance we have of containing outbreaks. We’re going to have positive students, the number of support that. We have 2000 students, we know, given the population, given where we are in the country, we are going to have and we have had a number of positive students, but it’s really our ability to quickly surround them in terms of identifying them, their close contacts, isolating them, and making sure that we break that continual spread and reduce the likelihood that they’re going to then transmit it to other people. The faster we can respond, the better we are. And we’re really building our system to that point of response and accuracy. So far so good. We’re 50% there for the semester and we have had a number of positives, but the system seems to be getting better and better as we go along. So I’m confident that at this point, we have the right tools at least to give us the best chance to get through the semester and make it a success.
Robert Osborne:
Wastewater surveillance will not be disappearing any time soon. In fact, it may be here to stay for a while.
Dr. Sean Norman:
I think it’s going to turn out to be a tool that is routinely used for public health. This pandemic has really set sewage into mainstream and I think people are seeing what you can actually gain from monitoring sewage. Whether it is used for infectious diseases, which the protocols that we’re optimizing now are for a particular virus at the back end, the analysis part, but the front end of the sampling will be the same, regardless of what type of infectious agent or drug or pharmaceutical that you might be interested in monitoring. So I see it proceeding forward and continuing, there’s still a lot of science to be done and understanding the process and that requires a lot of different types of expertise. Engineers who can talk about hydraulic retention time, epidemiologists, microbiologists. So I think over the next few years, we’re going to see teams to come in together to try to see how far we can take sewer surveillance.
Robert Osborne:
As we were putting together this episode, Dave, and Amy, and I discuss what thought the implications were for wastewater surveillance.
Robert Osborne:
I guess you have to remember this wastewater, it’s a tool, right? It’s not the tool. It’s just part of everything else, testing, mask wearing, social distance, it’s everything, right?
Amy Anderson:
Yeah. Yeah. Well, and it gives you a piece of data and it gives you an early warning sign as compared to positive tests. But if anything, we’ve seen people don’t necessarily change their behavior based on data. So we can’t have high expectations.
David Ladner:
Yeah, that’s right. That’s a huge take home message for me from this whole pandemic. I guess when the pandemic first started, I was kind of thinking, well, okay, we’ve got all these data coming in. Johns Hopkins has their awesome map showing COVID cases. And if you start having COVID cases in your county, then everyone is going to start behaving better. It’s great that we have all this data about cases, but it didn’t necessarily change anybody’s behavior like you just said. And I guess when the wastewater epidemiology came about, I was sort of seeing it as I sort of forgot that and was thinking, “Okay, we’ll be testing the wastewater and if we have a high case numbers, then the university will respond and we’ll act accordingly.”
David Ladner:
And I guess that was kind of a naive thought because the same kind of thing, “Did we really respond? Did we really act accordingly?” I almost feel like the best we can hope for is that a few people did respond. The mask ordinance is a great example. If a hundred people responded and decided to wear their mask, because there was more warning about the levels that were out there, then that was success.
Robert Osborne:
That’s a great point.
David Ladner:
If they kept themselves healthy or if it slowed the spread to some degree, then that was useful. And then it’s just a question of can you quantify the utility of it? And I’m not sure.
Robert Osborne:
Thanks again, to all our guests for making time and talking with us. We have links to the Clemson Wastewater Dashboard and other university dashboards in the show notes. Do you have a good story idea? Go to our website theoutfall.com and leave us a comment, we’d love to hear from you.
