Wednesday, August 12, 2015

Cleaning UP the Animas and San Juan Pollution

Cleaning Up the "Yellow Goo"
Can the EPA clean up the riverbeds?

Riverbed Retention of Spill Particulates [image-The Guardian]
Four Corners Map Animas and San Juan Rivers [map_source]
Although the local residents are relieved to see the yellow plume gradually clearing, anyone who has seen what's been left on the riverbeds should still remain concerned.

There is little to be gained from republishing reports of the pollution of the Animas and San Juan Rivers [Southwestern Colorado and Northwestern New Mexico]. The large scale map [left] will introduce the general area impacted by the spill of retired gold mine pollutants for blog visitors unfamiliar with the region.

For visitors unfamiliar with the story of this spill, here is reporting and photos from The GuardianColorado Spill In Animas River -The Guardian .

The point of this post concerns a proposal to mitigate the spill residue which is clearly being retained by the respective riverbeds. 

Although there is an understandable insistence on restoring the water quality in both rivers as quickly as possible, this eagerness may be undercutting the possibility of long term mitigation approaches offering a much more thorough outcome. The intermediate goal of rapidly restoring usable water quality may, actually, be making the impact of the settled pollution on the riverbed more permanent.

The timing of the spill is fortunate. This year's monsoon season has produced enough rainfall to create a very robust level of flow in both rivers, tending to move the pollution plume down river rapidly.

While this good fortune will result in clearing the water fairly rapidly, the heavy metal particulates now lodged in the respective riverbeds is apparently being considered a "necessary evil" in the EPA's overall mitigation plan. If a sizable percentage of this particulate residue could be dislodged fairly quickly, these river flows could move it downstream.

These heavy metal particulates will continue to cause a serious environmental hazard long after the flowing water has returned to its pre-spill quality and clarity. The specific elements revealed in the testing of these river waters do not bid well for the long term impact on edible river fish stocks and, potentially, on potable water being drawn from wells near the riverbeds.

Take a look at this article about the longer term impacts associated with such particulate metal pollutants. The metal compounds listed in the chart are very close to what the river water tests have detected.

Dislodging the Metal Particulates on the River Beds
An imperfect solution with positive benefits

A significant amount of these pollutants being retained on the river beds can be dislodged and flushed down stream. This means that these particulates will wind up lodged somewhere downstream but at a much reduced concentration. Further, this approach will not completely clear these retained particulates from the rivers in which the pumps are employed, but the process will reduce the current concentration substantially.
Clearing the Animas and San Juan river beds [MeanMesa]

This plan will require a number of fairly powerful pumps mounted on a small, floating barges which can be navigated along the contaminated rivers. The barges can be "piloted" by laborers via ropes extending to one or both of the banks of the rivers being cleared. The total depth of the pump assembly below the water surface of the river must be very shallow -- say, 6" to 8" -- in order to maximize the areas where the barges can be deployed.

Additionally, a similar pump and barge with a discharge hose long enough to reach river banks can be used to manually dislodge pollutants from the edges of the rivers. The process would be conducted manually.

The political obstacle would develop with the prospect of re-introducing the yellow trace in the river water as the riverbed pollutants are dislodged. This contamination would not last as long as the initial plume and would produce a visible reduction of the pollutant's more durable impact on the riverbeds.

Much of the environmental damage has already been done by the initial spill discharge, but this approach would serve to reduce the longer term, lingering and recurring impact from the metal particulates lodged in the riverbeds.

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