Emerging Contaminants and Landfill Leachate – Understanding the data and managing landfill performance
Gary J. DiPippo, P.E. & Kirstie L. Shurie
Cornerstone Environmental Group, LLC – A Tetra Tech Company
Recently, we’ve been thinking about emerging contaminants and landfill leachate. At the April 2018 NJ SWANA and the May 2018 Federation of New York Solid Waste Associations conferences, we had the opportunity to be part of presentations on emerging contaminants in landfill leachate given by Kirstie Shurie and Patrick Bell. After the presentations, we were struck by the conference participants’ interest in the emerging contaminants of poly and perfluorinated alkyl substances (PFAS) and 1,4 dioxane.
Why so much interest?
Could it be because of high-profile cases of PFAS in the water supplies of Newburgh or Hoosick Falls, NY?
Or that the NYSDEC performed a statewide survey in 2016 of potential sources of PFAS, is testing for PFAS and 1,4 dioxane at landfills and is sending out requests for testing these compounds to responsible parties for remediation sites?
Or maybe it’s that the NJDEP sent letters to over 50 facilities that are potential sources of PFAS, or because the MIDEQ on May 18, 2018, announced plans for a state-wide survey of PFAS and started sending letters to 1,380 public water supply systems.
Whatever the reason for the interest level, it got us thinking about PFAS and 1,4-dioxane in landfill leachate.
Why landfill leachate?
Well, think about it. Is the public clamoring for more landfills, ever closer to where they live?
And, these contaminants will be found in landfill leachate given their presence in so many common products. Even a well-run sanitary landfill, with state-of-the-art environmental controls, is likely to be blamed for contamination problems before, say, water-proof clothing or food wrappers. We’ll get back to this in a minute.
Meanwhile, it’s important to understand the issues faced when testing for these emerging contaminants. For 1,4-dioxane, a particularly important consideration is the method of analysis. 1,4-dioxane is miscible and not very volatile, so it’s quite hard to extract from a water sample for analysis. Regulatory standards for comparison are quite low, in the fraction of a part per billion range. So, while there are three USEPA-approved methods for testing for 1,4-dioxane in water and wastewater, they can give measurably different results:
At one site, we had the opportunity to get results from three different methods of analysis for the same sample (see graph). The results are quite different, as you can see, especially for Method 8270 without SIM or isotope dilution (i.e., poor recovery). Of course, someone will joke that we should be using Method 8270. Let’s be clear that we need scientifically defensible data to make informed decisions.
For PFAS, the problems can be different. First, comparison standards are all in the parts per trillion (ppt) range. Some examples of guidance and regulatory limits (many still in development) for PFOA and PFOS in groundwater and drinking water are:
At these low levels, sampling technicians cannot sample groundwater monitoring wells with the usual suite of tools, such as Teflon tubing, waterproof field books, Sharpie® markers, adhesive paper products, waterproof clothing, sunscreen, and aluminum foil. The potential for cross-contamination is substantial, and if it happens, further complicates interpretation of results.
Where can you find PFAS?
Good segue to waterproof clothing and food wrappers. Here are some interesting statistics. First, from the USEPA in a study that estimated the total amount of PFAS “artifacts” (i.e., PFAS that will be shed from various products) that could be present in a “hypothetical, typical American home.”
Let us try to put this in perspective. The USEPA has published a lifetime health advisory level for combined PFOS and PFOA of 70 ppt in drinking water, and you’ll note in the prior tabulation, adoption by some states of this level. The USEPA guidance for performing risk assessments assumes an adult will consume 2.5 liters of water per day and an exposure duration of 26 years. At the 70 ppt level, an adult would consume 0.064 milligrams of these two PFAS compounds per year. So, get your carpets cleaned commercially, and you have a source of PFAS in your home that could last you 1,100 years, hypothetically at least.
Where can you find 1,4-dioxane?
Now let’s look at 1,4-dioxane, with typical groundwater/drinking water limits at about 0.4 parts per billion (ppb). The ATSDR has some statistics on 1,4-dioxane in consumer products. The FDA studied 1,4 dioxane in cosmetics in the late 1990s and found concentrations ranging from 5,000 to 112,000 ppb. An updated study by a consumer group (Campaign for Safe Cosmetics) in 2009 found lower levels in the range of 270 to 35,000 ppb. In a laundry pre-soak spray, 1,4-dioxane was found at a concentration of 15%! And, in a study of household aerosol products in Japan, 1,4-dioxane was found in a concentration range of 0.17 to 2.25%.
When we think about all the products in which PFAS or 1,4-dioxane can be found, and understand they basically all end up in a landfill, that’s why we’ve been thinking about emerging contaminants in landfill leachate. Is the mere presence of these contaminants in leachate what is important? Or, is it an understanding of the concentrations and the landfill performance?
It’s the latter.
And, what does this mean to the current regulatory efforts to characterize these contaminants in the environment? To us, it means we have an opportunity to collect good data, and use it to make sound policy that is based on scientific inquiry, research, and facts, and not on politics and hyperbole.
To be clear, we are not suggesting there is zero risk associated with PFAS and 1,4-dioxane or that as environmental professionals we think it unimportant to test for them. Not at all. What we are saying is our profession should understand what it knows before making decisions. We will definitely be watching this carefully to navigate the future in the most scientifically-based way possible.
Categories: Environmental Planning & Compliance, Landfill Engineering and Design, Solid Waste, Uncategorized
Posted By Gary DiPippo, PE at 9:53 AM | 1 Comment on Emerging Contaminants and Landfill Leachate – Understanding the data and managing landfill performance
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