Prepared By:

Atlantic Richfield Company

Document Type

Government Report

Publication Date

Winter 12-7-2022

Subject Area



The purpose of this memorandum is to request a temporary variance of Montana’s Circular DEQ-7’s total recoverable concentration based numeric surface water compliance standards to the equivalent dissolved-phase federal ambient water quality criteria and for a temporary variance for arsenic, lead, and mercury to the aquatic life standard instead of the human health standard (hereinafter referred to as temporary variance performance standards), as allowed per the Butte Priority Soils Operable Unit Consent Decree Appendix D, Attachment B.1 Section (EPA, 2020). This temporary variance will be effective upon Environmental Protection Agency’s (EPA) approval, in consultation with Montana Department of Environmental Quality (DEQ), of the request and upon commencement of Further Remedial Element Scope of Work (FRESOW) remedial actions within the Blacktail and Silver Bow Creek corridor and terminate upon completion of the associated projects operational and functional period and commencement of the Compliance Determination Period.

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Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.