When I returned from a four-year assignment to Saudi Arabia, I found myself back in the US Geological Survey’s National Center in northern Virginia, initially without much to do. Rather quickly I got a call from a geophysicist friend in our Denver office, who had just the opposite problem. He had been asked to help solve a pollution problem in Arkansas, and was overloaded with too many other responsibilities. Could I help? Sure.
I quickly found myself at Fort Chaffee in Western Arkansas. This fort had been used during World War II to house German Army prisoners. Part of the Fort area was still being used to train tank battalions - we would hear truly unnerving sounds from the other side of tree stands that separated us from their training areas. I finally understood the point of tanks.
We were working in a section that the US Army wanted to turn over to the State of Arkansas for a park. However, since the turnover would involve transferring liability, the State of Arkansas wanted to be assured that the former camp’s landfill was safe, and not polluting the local ground water. Uhhh. What landfill? No one knew where the old landfill was - it had been covered over and forgotten 50 years earlier.
By looking at old records the hydrologists had narrowed down where this old landfill might be, and we began a survey using an EM-31 unit – you guessed it, and electromagnetic device that could map conductivity down to about 6 meters (20 feet).
Our survey was a success - at least insofar as we were able to locate the old landfill - but we also detected a conductivity plume slowly leaking out of it (see figure). Feeling very satisfied with our success in just one day of surveying, we finished and headed back to a motel. “Meet you in 30 minutes for dinner,” I asked?
“Make that at least an hour,” both hydro-techs said at the same time... “and be sure to take off all your clothes and check every square inch of your skin for ticks.” I had inadvertently been working in the Galactic Center of ticks in the universe. I found 19 ticks on me - seven already dug into my skin. Geophysics, for me, is ‘way easier.
A conductivity map of part of Fort Chaffee, AK, with red representing the seeping pollution plumes from the World War II German POW camp landfill.
Everyone has probably heard of towns in the eastern US where the tapwater suddenly starts smelling like gasoline. Or perhaps you remember the headlines where the entire population of Minneapolis was told to NOT drink their tapwater "for a few weeks," because it was loaded with Clostridium. That’s short for Clostridium dificiles, a nasty bacterium that among other things causes gas gangrene and really bad diarrhea. Been there, felt that.
Water quality has become so important that the USGS even has a dedicated website for toxics in surface and groundwater: http://toxics.usgs.gov/ “Toxics” as used here can include biological contamination and chemical contamination. Sometimes contamination can be at barely detectable levels - but if this includes endocrine-interrupting chemicals or dioxins, then we are talking about some very dangerous stuff. Things like these in our drinking water could potentially have life-changing consequences on entire communities.
These are just some examples of groundwater contamination - plumes of foreign material moving through an aquifer, ruining it. Mitigating (fixing) something like this can be a real problem, and sometimes requires just shutting down an entire well-field. If it’s a bacterial contamination, geophysical methods won’t help you track it. If it’s something like gasoline, or oil - technically a NAPL (Nonaqueous Phase Liquid), then geophysical methods CAN help map and track it.
NAPL's come in at least three main flavors:
- "DNAPL" is a Dense NAPL - one of a group of organic substances that are relatively insoluble in water and more dense than water. DNAPLs like bunker oil tend to sink vertically through sand and gravel aquifers to the underlying layer.
- There are LNAPLs - Light NAPLs, such as gasoline and benzenes.
- And finally PAHs - Polycyclic Aromatic Hydrocarbons, like chlorinated solvents. The Nose Knows right away when you encounter any of these.
Did I mention that many of these are known carcinogens? Trust me, you do not want ANY of these, in ANY quantity, in your drinking water.
I love rivers. Before I moved west to the Cascades, I used to kayak in the Potomac River - that was, until parts of it became so clogged with discarded Cabomba (an aquarium-plant that became invasive weeds) that I could sit still in the kayak and not move downstream. The weeds held me still unless I paddled hard.
I also have kayak'd in the Columbia River that separates Washington from Oregon. Once I received a phone call from the Acting Scientist-in-Charge that there had been another eruption at Mount St Helens. I stopped paddling to talk with him on the chief scientist cell-phone, and noticed that I was drifting upstream.
"Uhhh, Willy. I'm in my kayak, but I'm drifting upstream," I said.
"Oh, that's because ocean tides are felt all the way up to Bonneville Dam," he replied. Later the up-coming tide and the down-going current met at a log boom protecting a marina near Interstate-205... and formed a terrifying whirlpool, at least two meters across, that nearly got me.
As I said, I love rivers - but you never know what kind of surprises they may have in store.
There is one other form of groundwater pollution, and like E. coli or endocrine-interrupting chemicals, it is not easy to detect. I’m talking here about mercury and radioactive isotopes. Some of these may be dangerous while not readily detectable (even with radiation counters).
I currently work in Vancouver, Washington, adjacent to the Columbia River. As the chief scientist for volcano hazards - the senior manager in the Cascades Volcano Observatory at the time - I once received a package from the USGS headquarters office of the Water Resources Discipline. The cover letter asked me to take samples of water from the drinking fountains in our building and send them back. The cover letter, however, also asked that I report the source of that water. Intrigued, and having a rare hour of relatively free time on my hands, I called around and got the Clark County Water Utility District. They told me that the water came from a well-field in volcanic basalt in the northern part of the county.
“Why,” I asked? “We’re right next to the Columbia River!"
The reply startled me. I was told that there was a huge mine in Canada whose tailings drained mercury into the headwaters of the Columbia River - which then ran past the Hanford Nuclear site near Kennewick, Washington.
I always carry bottled water when I kayak. “So?”
“So there are chemical pollutants from all the mines and old industrial facilities located along the river’s length over the past century - and at one time there was even measurable plutonium in the Columbia River.”
Plutonium. Microgram for microgram, this may be the most toxic metal on Earth. After an immensely expensive Super Fund cleanup of the Hanford Super Fund site near Kennewick, the Columbia River is a lot safer today than it was even 15 years ago.
From my life experience, however, I have a permanently heightened awareness of water pollution, and now understand why so many of the human population living on the planet does not have access to safe drinking water.
For me, water quality has become personal.