Tales Of Our Times: Combating Pollutant Plumes In Groundwater Is Slow-Going

Tales of Our Times
New Mexico Citizens
for Clean Air & Water

Combating Pollutant Plumes In Groundwater Is Slow-Going

The U.S. EPA delivered unwelcome news five months ago about Española’s stubborn problems at the “North Railroad Avenue Plume Superfund Site”.

A letter from the EPA told the New Mexico Environment Department that the problems of it now belong to the NMED. The details of the case keep shifting, which makes the primary lesson clearer: Cleaning up pollution messes is immensely harder than avoiding them from the start.

The story goes back more than 50 years and has been actively pursued by the EPA for the last 30 years, until last August. The Norge Town laundromat and dry cleaners began business some 50 years ago at 113 North Railroad Ave. in Española, 20 miles north of Los Alamos. The Norge Town business followed the national practice of the time by dumping used dry cleaning solvents on the ground beside the shop. The location was extra bad, since the bad stuff dumped there went into the ground within some city blocks of the Rio Grande. By many pathways, groundwater seeps towards the Rio.

In 1989, dry cleaning solvents—chiefly perchloroethylene (“PERC” in the trade)—began showing up in two of Española’s city wells, which permanently ended their use as drinking water supplies. During the last 30 years, the EPA’s Superfund program has spent upwards of $5 million working to track and remove solvents and limit their spreading to other wells and to the Rio Grande. Over the 50 years, the chlorinated solvents have seeped into three different water tables at different depths, which flow in slightly different directions. Dry cleaning fluids are now found at three depths—shallow, mid-levels, and deepest levels (180 to 260 feet deep). Solvents have been extracted from groundwater. Concentrations have been reduced. Yet, some are higher, which likely points to some different source.

A list of techniques for removing pollutants from the ground reads like science fiction. Remedies range from no-tech to high-tech. On the low end are zoning changes. An option several steps up the scale is to install permeable barriers underground that chemically react with the plume to form harmless products. Other methods put various materials into the plume to speed the cleanup. Additives can be “oxidants” that oxidize the bad stuff, “detergents” that help sweep out the bad stuff, and even nutrients and microbes that feast on the bad stuff. That’s right, certain bugs think a helping of perchloride is roast rack of lamb. Bugs may seem crazy, but bioremediation works.

Cleanup generally goes faster when pumping is used. That is, the polluted water is pumped from below ground to the surface, to be treated and sent back. But don’t be fooled by words like “speed” and “faster”. Cleanup is not like a whirly wash-and-rinse cycle. Any remedy creeps along on the groundwater’s scale of time. Plans are laid out for 30 years, as in 30-year mortgage. Of course, any plan includes regular sampling of the plume to track progress, which requires drilling more wells.

Not far south of Española, the Los Alamos National Laboratory, the Department of Energy, and the NMED know a good deal about a separate pollutant plume that haunts the local aquifer. In 2005, the lab discovered a plume of hexavalent chromium creeping along below Los Alamos County. As with dry cleaners, the plume’s story followed the prevailing practice of 50 years ago. In the pattern of those times, the lab’s power plant used hexavalent chromium as a rust inhibitor and dumped it beside the plant. Towns today see the problems left from the poor ways that were used so many places far and wide, and nearby, too.

Española and Los Alamos confront different problems, having similar aspects. Ideas might pop up from the towns’ exchanging thoughts about efforts to date, including cost. For all I know, the towns may already be well down this road.