Can biased sampling create hazardous waste?

One of our current cases deals with a question that is critical to everyone in the waste business: can biased sampling make a non-hazardous waste “hazardous”? 

Approvals typically require waste management companies to manage wastes based on “representative samples”. Thirty years of guidance documents, and several cases, have also held that waste must be characterized as hazardous, or not, based on “representative samples”. Inaccurate and imprecise sampling can cause a solid waste to be inappropriately judged hazardous.

The Ministry of the Environment defines “representative sample” as

“a sample portion of material or waste that is nearly identical in content and consistency as possible to that in the larger body of material or waste being sampled.”

Taking representative samples of the whole waste is especially important because Regulation 347 defines, as non-hazardous waste, several types of waste that would individually fail a leachate test, including certain types of  spill cleanup materials and 2.5 cm of  residue in the bottom of an “empty” hazardous waste container. (Up to 25 kg, in a 1000 litre tote).

But the Ministry of the Environment argued in court this month that they can cherry pick “whatever interests them” out of a truck or pile of waste, even if it does not represent the truck or the pile as a whole. (This is called “biased sampling”.) And if what they choose to sample fails a TCLP, they say the waste is “hazardous”. And they are asking for penalties against senior company managers, personally.

This “hotspot” approach creates huge risks for waste generators, as well as waste management companies. The penalties for handling “hazardous waste” as non-hazardous can include jail, and very large fines, for both companies and individuals. Yet how can any company or individual know, in advance, which parts of their waste might “interest” the Ministry, or what an analysis of that part might show? Many non-hazardous wastes are heterogeneous, and will contain some amount of hazardous materials. What kind of sampling can anyone rely on, if representative sampling is not good enough?  And how can this sampling approach be reconciled with the exemptions for empty containers, spill cleanup materials, etc.?

The more that regulators jack up penalties for hazardous wastes, the more important it is that there be fair, objective and reliable ways to know what counts as “hazardous”. Abandoning representative sampling, in favour of cherry picking “whatever interests them”, would be a very dangerous step in the wrong direction.


    • DSS

      Quite right, Wilf. I think we agree that biased sampling cannot reliably answer the question, is this waste hazardous? It\’s improper for waste generators to use biased sampling, but even more so (in my view) for the Ministry of the Environment to do so.
      Thank you for your comment.

  1. The entire subject of "representative sampling" continues to be completely ignored by the MOE and any casual statistical analysis of field sampling methods would reveal the gross errors inherent but totally ignored in the resulting lab analyses. Duplicate lab results that vary by several hundred percent as they often do is a clear indication that the sample representativeness is way off thus proving the analytical result is essentially meaningless. The pass/fail system in Reg 153/04 is resulting in soils being declared "contaminated" when, in fact, proper sampling might show them to be "clean". It only takes one exceedence of an allowable limit on a site to prompt further (expensive) investigation and cleanup. Now, for the MOE to blatantly choose so-called "hot-spots" and prosecute these goes beyond the pale and any sense of common justice.

Leave a comment:


Required field