If a landfill’s liner springs a leak, harmful chemicals can leach into the groundwater, making it unsafe to drink. Joe Lourigan is a hydrogeologist with the Department of Natural Resources, or DNR, which regulates and monitors landfills across the state. There are many types of environmental monitoring that can go into landfill safety. But Lourigan says groundwater safety is the DNR’s s primary concern around landfills:
“Probably the one we talk about the most is the groundwater monitoring because it is the indication of the quality of the groundwater around the facility, and of course we’re all concerned about that because of the need, the use of groundwater for drinking, so we want to be very protective of that as a natural resource.”
Monitoring wells are drilled all around a landfill and are regularly checked for contaminants. The most common contaminants from household waste are volatile organic compounds like gasoline or butane. Industrial landfills can have industry specific contaminants like heavy metals or coal ash. If a landfill is found to have sprung a leak, a few measures are possible.
“The next thing would be to delineate the degree and extent of impacts to make sure we understand how far out it has gone and that its not going out or traveling through the groundwater farther away from the limits of waste or the landfill,” said Lourigan. “A lot of times with landfills what we find is that if we put a cap on the landfill and stop the infiltration of water through the waste, that improves groundwater quality significantly.”
Lourigan says problems like these are fairly common across the state. The problem landfills are mostly older, before current guidelines were put in place, and the leaky ones are mostly known. It’s rarer for new issues to emerge on modern landfills.
Landfill owners are required to do their own monitoring, although most choose to hire outside consultants to do the work. The DNR only monitors a landfill directly in circumstances where the owner cannot monitor themselves, most often because they are no longer financially able to do so.
The DNR is also heavily involved in siting new landfills. Dane County is in the preliminary stages of the multi-year process. The county landfill has about nine years left of space, and it’s going to take most of that time to prepare a new site. The process is actually two parallel processes. On one hand, a prospective landfill owner must navigate the local concerns and municipal laws that vary place by place. But at the same time, they have to follow the state guidelines laid down by the DNR. The first step is an initial site inspection.
“So department staff would go out the site where they want to construct the landfill and evaluate locational setbacks and what might be in the area, to identify what might be potential constraints to development in the area. So things the departmental staff would look for is things like wetlands, water supply wells, surface water bodies, and those types of things,” said Lourigan. Next comes an initial site report, which includes the planned layout of the landfill. “The department reviews that and makes an evaluation on whether or not the department thinks the site has potential as a landfill, to give the applicant some initial feedback on what the chances are that where they want to install the landfill could be done, before they go ahead and spend a lot of money on doing additional investigations,” said Lourigan. “If the applicant wants to continue pursuing it, they would have to do a geotechnical investigation on the property and in the project area.”
The geology concerns can be wide ranging. Landfills are heavy, and have to have strong foundations much like large buildings. But the predictability of water flow underneath the landfill is also of concern. The monitoring wells have to be able to accurately measure what is coming out of the landfill, and that requires certain types of soil and bedrock. The geology report gets bundled with environmental surveys and local compliance into what’s called the feasibility report.
“When we get to the feasibility report stage of the siting process, that’s probably the lion’s share of the work that goes into landfill siting,” said Lourigan. With that report comes a period of public comment. The comments can guide the DNR in how they approach the landfill down the line. “I think its important for us to be aware what impacts an existing landfill is having around a surrounding community so that when we go out for an inspection we can be cognizant of that kind of stuff and we can address that with the landfill owner,” said Lourigan.
The final step is an operational plan, in which the landfill owner provides a plan on how the landfill will be monitored for leaks. This includes setting aside money to monitor a landfill even after its closure. So a landfill has to show the state how it will close before it is even allowed to break ground. “At least for 40 years after site closure, the landfill is required to provide proof of owner financial responsibility to the department, so that when the landfill owner becomes unviable financially, then the department could pick up that sampling,” said Lourigan.
Landfilled waste has a unique problem. Unlike recycling, which is processed and sorted, when you throw something away, no one ever really looks at it again. That means that often we have no idea what is getting put into a landfill. Once it goes into a trash bag, it never comes out.
Last year, the DNR undertook a report last year to study the makeup of the trash in our landfills. It’s called the waste characterization study. Casey Lamensky is a solid waste coordinator for the DNR. She lays out the reasons for the study. “Getting this data helps us see trends over time of what is being generated, and it kind of falls into a few different categories. One is materials being generated that we have the infrastructure to divert… The other is to see the streams that we don’t currently have the infrastructure to divert, so that we can make the case to develop it here.”
The most recent waste study was released this summer. It found that, compared to a similar report a decade ago, the amount of food thrown away has doubled. In 2009, approximately 10% of the waste was food waste. by 2020, that percentage had risen to 20% of all trash.
“We did see when comparing with Iowa in 2018 and Vermont in 2019, statewide waste studies, food waste at around the same amount, so it definitely is a rising trend,” said Lamensky.
Food waste is a problematic trash item, since when it degrades in a landfill, it releases methane. Methane is a potent greenhouse gas, so now landfills are required to capture some of the methane, and either sell it or burn it. But the capture methods are imperfect, and some amount of methane still leaks out into the atmosphere.
But besides methane production, an increase in food waste would still be cause for concern. Landfill space is valuable and limited, and having one fifth of it taken up by useable items is something that Lamensky is hoping this report helps address: “Landfill space is hard to site and expensive and valuable so we don’t to fill that space unnecessarily we want to use it for things that really do need to be landfilled.”
Recyclable materials are another area of concern. Approximately another 20% of what we throw away is recyclable, mostly plastics and paper. The DNR also undertook a survey to find out why people throw recyclables away. They came back with some results that might explain people’s behavior.
“We found that for recycling, the two highest reasons were inconvenience and the belief that materials separated for recycling are ending up in the landfill anyways,” said Lamensky.
Since 2011, it is illegal to put televisions in landfills in Wisconsin. That measure reduced the amount of TVs in the trash by 85%. Similar recycling campaigns around medical sharps and aerosol cans also yielded reductions. “Since 2009 we’ve seen a great increase in the ability to recycle asphalt shingles, which were the number one component of construction and demolition waste stream, and a top 10 component of the municipal waste stream, so it went from being 30% of the construction and demolition waste stream down to just 10%,” said Lamensky.
The study monitored Wisconsin landfill usage in 2020, when the pandemic disrupted individual habits – which makes meaningful generalizations about the change in trash habits difficult. Still, Lamensky says that we are in line with national trends.
The DNR hopes that these types of waste characterization studies can happen in regular intervals, so that landfills and governments can keep an eye on trends in the make-up of our trash.