Sunday, February 27, 2011

Some Basic Sanity Checks on the NYT Radioactivity Piece


So, along with the NYT's big piece on radioactivity in drilling wastewater, they provide a spreadsheet of well results that they reviewed.  The above shows a screenshot of a portion of it.  All that I have done is sort the data by "Gross Alpha".  The rows represent different wells (mainly in Pennsylvania), and the "Gross Alpha" column is a measure of the amount of the radioactivity in the water, measured in Picocuries/Liter.

For background here, a Curie is the official international a widely-used unit for radioactivity, measured at 37 billion decays of individual atoms per second.  "Alpha" here refers to alpha radiation, which means nuclear fission events that release an alpha particle - a helium nucleus.  So a curie of gross alpha means 37 billion alpha particles per second.  A picocurie is one trillionth of this, so 37/1000 decays/second (ie one decay every twenty seven seconds).

So then, the worst well on which "Gross alpha" was measured was Sampson #147-2H, and it had 40,880 picoCuries/Liter (ie 1513 individual atomic nuclei decay and release an alpha particle, per liter of water, per second of time).

Here is the EPA standard for gross alpha in drinking water:


So that standard is 15 piC/L, and we have many wells with tens of thousands of piC/L.  The average of all the wells in the spreadsheet with a measurement for gross alpha is 4857piC/L, which is 323 times the EPA standard for drinking water.

So then the question is whether it's plausible that the drilling waste going into public waterways in Pennsylvania is diluted by a factor of more than a few hundred.

According to the Times article, 1.3 billion gallons of wastewater was produced in Pennsylvania in three years.  Presumably more was produced in 2010 than 2008, so let's just take 1 billion gallons/year as a round number.  Now, it's very unclear whether the 200 and some wells the Times provides data on are a random sample, or are in effect the worst cases out of thousands. This is a key issue and it's frustrating that the Times doesn't document it better (journalists!):
For proof that radioactive elements in drilling waste are not a concern, industry spokesmen and regulators often point to the results of wastewater tests from a 2009 draft report conducted by New York State and a 1995 report by Pennsylvania that found that radioactivity in drilling waste was not a threat. These two reports were based on samples from roughly 13 gas wells in New York and 29 in Pennsylvania.

But a review by The Times of more than 30,000 pages of federal, state and company records relating to more than 200 gas wells in Pennsylvania, 40 in West Virginia and 20 public and private wastewater treatment plants offers a fuller picture of the wastewater such wells produce and the threat it poses.

Most of the information was drawn from drilling reports from the last three years, obtained by visiting regional offices throughout Pennsylvania, and from documents or databases provided by state and federal regulators in response to records requests.
I cannot tell from this what the sampling properties of these ~200 wells are.  Let's, for now, assume the worst: that the data are a random sample, and that the notional 1 billion gallons/year was all at 5000 piC/L on average (rounding up the 4857 piC/L from the spreadsheet).  Now according to the Times, most of this went into two rivers:
In Pennsylvania, these treatment plants discharged waste into some of the state’s major river basins. Greater amounts of the wastewater went to the Monongahela River, which provides drinking water to more than 800,000 people in the western part of the state, including Pittsburgh, and to the Susquehanna River, which feeds into Chesapeake Bay and provides drinking water to more than six million people, including some in Harrisburg and Baltimore.
Here's a map of Pennsylvania rivers, for context:

Here are data for the flow of the Susquehanna at Marietta, PA which is close to the Maryland border:


So ballpark around 30,000 cubic feet per second in this river in the winter.  It will be more in spring and less in summer - let's take 20,000 cfs as a very ballpark number for an annual average.

Here's the flow of the Monongahela at Elizabeth, PA (which is just upstream of Pittsburgh):


So let's take that to be about 5000 cfs as an annual average (these graphs will only go back for 120 days, so we can only roughly project the annual picture - but I'm just trying to get the right order of magnitude here).

So, to summarize, the ballpark model here is 1 billion gallons/year of radioactive wastewater at 5000 pCi/L going into two rivers with a combined total flow of 25000 cubic feet per seconds, on average.  So now it's just unit math.  There are 365.25x24x3600 = 31557600 seconds in a year. There are 7.5 gallons in a cubic foot. So overall, the wastewater stream, as a fraction of the river flow, is 1,000,000,000/7.5/25,000/31,557,600 = 0.017%.  So diluted by the full river flows, the 5000 piC/L becomes 0.85 piC/L - which we may as well call 1 piC/L (given the limited accuracy of this calculation).

So on an average basis, this says the residents of Baltimore, etc, downstream on the Susquehanna are probably ok (the standard, recall, was 15 piC/L).  However, it would certainly seem like there would be huge potential for localities in Pennsylvania to exceed the safe standard.  In particular, the Mononghela purportedly had more of the waste, but only has a fifth the flow of the Susquehanna, so appears to have much higher potential for problems.   The major caveat here is the possibility that the NYT's reported spreadsheet of wells may be highly unrepresentative.  If they are the cherry-picked worst cases, the overall problem will be much less in scale than the above calculation indicates.

Certainly, it seems that Pennsylvania drinking water treatments plants should all be doing continuous monitoring of radioactivity levels henceforth.  Geiger counters are not expensive.  This is something citizen groups could probably aspire to figure out, rather than waiting for the government to get around to it.

15 comments:

Csiki Attila-József said...

it seems to me that it's a random sample. They have measured 200. They couldn't have had any idea about which are the worst 200 prior of measuring them.

Fixed Carbon said...

Stuart: I would concentrate on low flow periods in this analysis. During low flows and with higher sediment loads, currents are non-turbulent and mixing is less. Thus, slugs of the waste water will travel without begin diluted. I heard a talk about this a few years ago at UCD. This is why hydrologists and env. health experts get really nervous with "dilution is the solution" for rivers.

Hypnos said...

Luckily the Pennsylvania Republica administration has the solution for this: suspend environmental regulations, stop monitoring.

If you can't see it, it can't harm you.

Contemporary conservative thinking is tantamount to magic.

http://www.post-gazette.com/pg/11056/1127950-113.stm#ixzz1F1458whB

Lars-Eric Bjerke said...

“For background here, a Curie is the official international unit for radioactivity, measured at 37 billion decays of individual atoms per second.”

The SI unit for radioactivity is Becquerel.

http://en.wikipedia.org/wiki/SI_base_units

Robert said...

and a pico (p) is 0.000000000001

Stuart Staniford said...

Lars - I guess you're right, it's not an SI unit.

Robert: Pico is 10^-12, which is one trillionth, as I said.

Robert said...

Sorry, I missed that. My x-ray technician/radiologist career began in 1948 and lasted over 50 years. Among other things it included relatively primitive fluroscopy and inserting radium needles with a needle holder. I discovered T D Luckey around 1981 and developed an ongoing interest in radiation hormesis and the subsequent controversies, The data relevant to millirad and single digit rad exposures (old timers often prefer rads over grays) is buried in a sea of noise. However I believe that at low levels there is more evidence for hormesis than there is for the linear no-threshold model. This of course is also relevant to radiation produced by nuclear power and burning coal. Years ago there was an amusing controversy over the use of microrad vs millirads vs rads The claim was that some writers preferred big numbers to frighten the uninitiated.

BOP said...

Of concern is the NYT report that water treatment plants do not test for the level of radioactivity on the incoming waste water and also do not test the outgoing "treated" water stream.

Not sure how you can draw conclusions for or against if there is inadequate data collection in the first place. Given the potential for significant impacts the monitoring inadequacy is surprising.

p-roc's mom said...

Well, that explains why my grandfather's well water was radioactive. He lived out in the countryside, by Pequea, PA, near the Susquehanna, and all his water came from his well. He didn't know his well water was radioactive until my uncle made himself some iced tea with the well water and tried to take it to work with him - at the Peach Bottom nuclear plant, where the standard radiation check at the front door flagged him.

My uncle didn't seem too worried about it, so I assume it wasn't a terribly high level, and my grandfather passed away a while ago, so it's not an issue for him anymore, but it does raise the issue of how many other people out in rural PA are drinking radioactive water without knowing it.

Stuart Staniford said...

p-roc's mom - wow, I hadn't thought of that possibility. We live on that same geology (we are near the northern edge of the Marcellus also on the Allegheny plateau) and it's standard to get radon tests in houses here (ours was clear), but it hadn't occurred to me to test the well water. Maybe I should.

Mr. Sunshine said...

Ahhh .. radon. A real problem here in Colorado's gas country, too ... and as I recall, 4 picocuries/liter is the federal 'safe' limit. Which, per my doctor, is about the same as smoking a half a pack of cigarettes per day as far as long term cancer risks go. Probably should check my well, too.

Robert said...

Bernard Cohen on radon and other matters

http://www.phyast.pitt.edu/~blc/

Mr. Sunshine said...

The pitt site links look like a wordperfect documents that were posted without conversion to html .. interesting, but almost impossible to read.

Radon in Eagle, Colorado new home basements averaged 400 pc/l when tested a few years ago... lots of $$ made by people selling little fans :)

Robert said...

??.
-- Item #9 is legible. It was published in one of the two major peer reviewed radiology journals at my suggestion. There was also a rebuttal by a prominent radiologist. See also
http://en.wikipedia.org/wiki/Bernard_Cohen_%28physicist%29
Dr. Cohen studied radon for decades. He went to great effort to answer critics. I am uncertain as to his current activity. He is about 86 years old.

Gary said...

I think Tad Patzek's comments on this story are illuminating.

http://patzek-lifeitself.blogspot.com/2011/02/radioactivity-in-water-and-natural-gas.html