No KCAL9, that's not what the results mean. Part 3

Is soil that contains 1000 ppm of lead - as detected by a Niton XL2 XRF - a hazardous waste?

Probably not.  But I cannot say for sure without running a TCLP on the soil.

But it contains 100 ppm of lead!  The regulatory limit for lead as a hazardous waste is 5 ppm!  That's 200 times more lead in that soil than a hazardous waste!

Whales are aquatic.  Fish are aquatic.  Whales are not fish.

XL2 XRF reports a ppm for lead.  TCLP reports a ppm for lead.  These ppm results mean two different things.  You cannot use the XL2's ppm to state "hazardous waste."

And here is where it gets really wacky!

The XL2 is telling us a ppm based on surface area and depth.  I do not know how this correlates to a ppm we use in environmental determination of regulatory compliance or cleanup levels.  I am going to assume that the ppm reported aligns with mg/kg - the standard way we discuss ppm when looking at lead in soil.

So let's just accept that a reading of 1000 ppm determined by Randy Paige when using the XL2 in the yard near the bike detected 1000 mg of lead per kg of soil.

1000 mg is 200 times more than 5 mg (the hazardous waste threshold).

Yeah...but..1000 mg per kilogram of soil versus 5 mg per liter of liquid (the leachate).

They do not correlate.  With one exception...

If we were to run a totals constituent analysis on that soil, and we obtained 1000 mg/kg of lead, this would cause us to consider the soil as possibly being a hazardous waste.  This is due to a concept we call "the rule of 20."

If a waste is 100% solid, as defined by the TCLP method, then the results of the total constituent analysis may be divided by twenty to convert the total results into the maximum leachable concentration. This factor is derived from the 20:1 liquid-to-solid ratio employed in the TCLP.

So now we have ourselves a dilemma.

If the ppm reported by the XL2 correlates to a totals analysis result in mg/kg.  1000 ppm detected by the XL2 is way above "the maximum theoretical concentration in the leachate could have" which is 20 times the TC regulatory value of 5 mg/L - or 100 ppm.

If the soil contains less than 100 ppm of lead from a totals analysis, then theoretically, because of the 20 to 1 dilution - it could not leach more than 5 mg of lead per liter of leachate.

Too many numbers Bowman!  Boring!

Okay...so work with me here.  We are told 1000 ppm in the backyard by the bike. Let's assume that 1000 ppm reported by the XL2 meter is the same result we would get if we took a soil sample to a laboratory.  1000 ppm is greater than 100 so we cannot rule out this soil - in this backyard - by this bike - does not meet the definition of a hazardous waste.

Here we get wacky!

The EPA threshold for lead in the soil of residential property is 400 ppm.

But...400 is four times higher than 100 - the theoretical value!  How can the EPA say that up to 400 ppm is a safe level for children?

Because what makes something a hazardous waste relates to risk of a particular health impact and not the health impact that is present.

Confused?


No KCAL9, that's not what the results mean.  Part 4