Atlantic Richfield Company
Butte, Montana

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Butte Treatment Lagoons

What you should know

In 2001, completion of the Butte Treatment Lagoons (BTL) marked the end of nearly a decade of work to remove contaminated tailings from Lower Area One (the area north of I-90 and east of Montana Street).

The Butte Treatment Lagoons (click image for larger view)

In 2001, completion of the Butte Treatment Lagoons (BTL) marked the end of nearly a decade of work to remove contaminated tailings from Lower Area One (the area north of I-90 and east of Montana Street). After contaminated soils were removed, clean soils were transported in and Silver Bow Creek was reconstructed. Since its construction, the BTL system has captured and treated contaminated water before discharging it to Silver Bow Creek within applicable or relevant and appropriate requirements (ARARs).

When constructed, the BTL system captured ground water from Lower Area One. Today, in addition to capturing ground water at Lower Area One, the system treats ground water from the Metro Storm Drain Sub-drain, West Camp Pumping system, Missoula Gulch base flow and the captured ground water from the Butte Reduction Works.

The charts below show influent and effluent concentrations for Contaminants of Concerns at the BTL. Influent water, measured at CT-IN04, is the concentration before any treatment has occurred. Effluent water, measured at CT-EFS7, is the water after lime is added, metals have been reduced by precipitation and the water is about to return to Silver Bow Creek. Samples are taken at CT-IN04 and CT-EFS7 every three days.

In the fall of 2010, the Atlantic Richfield Company began upgrades to the BTL system which will include site utilities upgrades, a new automatic sampling building, upgrades to site operations building which houses the lime addition system and more.

For further information, visit our Reports and Publications page to download related documents.