June 10, 2009

As of June 2009, more than 1.9 million cubic yards had been shipped from the Milltown site to the BP ARCO waste repository at the Anaconda Superfund site. More than two million cubic yards will shipped in total.

At the repository, roughly 80,000 cubic yards of reservoir sediments are scooped daily from one train with 45 rail cars. The Milltown sediments are loaded into dump trucks and hauled to "cells" - bermed areas that already contain old contaminated smelter waste anywhere from 10 to 50 feet thick. There, the reservoir sediments are spread two feet thick over the smelter waste and seeded.


The daily process of unloading, spreading, and seeding sediments will continue through late 2009. All in all, the material from Milltown will cover less than a quarter of the waste repository, or about 800 out of 4,000 total acres.

Under BP-ARCO's plan, this layer of Milltown sediments will form the final cap on the waste underneath. The idea is that once established, the grassy soil cap will soak up most of the annual precipitation, preventing infiltration and contamination of groundwater. (And if successful, it will cut down on the chronic dust storms that originate at the repository.) With the reservoir sediments on dry land instead of underwater, they won't be subject to the type of physical conditions that released arsenic and contaminated groundwater at Milltown.

But will it work? That remains to be seen. It's true that compared to the yellowish smelter waste, Milltown sediments look like rich brown topsoil, but the Milltown material is nonetheless loaded with arsenic, copper and zinc. Is there enough organic matter in the sediment to compensate for the high metals levels? Will vegetation on this material be robust over time? These questions will require careful monitoring for many years to ensure that these sediments will successfully grow grass in the long run. Whatever the outcome, BP-ARCO is ultimately responsible for revegetation at this site - and it will be up to EPA, citizens and local county government to hold the company responsible.

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