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  1. Home
  2. Silver Bow Creek - Butte Area
  3. Current Site Status

Cleanup Schedule by Operable Unit

During cleanup, a site can be divided into a number of distinct areas depending on its complexity. These areas, called operable units (OUs), may address geographic areas, specific problems, or areas where a specific action is required. Examples of typical operable units include construction of a groundwater pump and treatment system or construction of a cap over a landfill.

Cleanup Schedule by Operable Unit
MilestoneStart DateCompletion Date
OU 00 - SITEWIDE
Administrative Order of Consent (EPA Performed) 04/01/1988
Administrative Order of Consent (EPA Performed) 03/31/1989
Administrative Order of Consent (EPA Performed) 05/04/1990
Administrative Order of Consent (EPA Performed) 06/07/1990
Administrative Order of Consent (EPA Performed) 06/20/1990
Administrative Order of Consent (EPA Performed) 06/26/1990
Administrative Order of Consent (EPA Performed) 07/03/1990
Administrative Order of Consent (EPA Performed) 05/31/1991
Administrative Order of Consent (EPA Performed) 08/02/1991
Administrative Order of Consent (EPA Performed) 05/12/1992
Administrative Order of Consent (EPA Performed) 06/30/1992
Administrative Order of Consent (EPA Performed) 03/17/1994
Consent Decree (EPA Performed) 04/19/1999
Consent Decree (EPA Performed) 10/26/2000
Consent Decree (EPA Performed) 01/24/2005
Consent Decree (EPA Performed) 09/11/2013
Unilateral Administrative Order (EPA Performed) 03/31/1989
Unilateral Administrative Order (State Performed) 06/05/1989
Unilateral Administrative Order (EPA Performed) 05/17/1990
Unilateral Administrative Order (EPA Performed) 09/25/1991
Unilateral Administrative Order (EPA Performed) 11/20/1991
Unilateral Administrative Order (EPA Performed) 08/10/1992
Unilateral Administrative Order (EPA Performed) 06/17/1993
Unilateral Administrative Order (EPA Performed) 08/11/1994
Unilateral Administrative Order (EPA Performed) 10/16/1995
Unilateral Administrative Order (EPA Performed) 03/29/1996
Unilateral Administrative Order (EPA Performed) 06/11/1996
Unilateral Administrative Order (EPA Performed) 01/12/2000
Unilateral Administrative Order (EPA Performed) 04/11/2000
Removal (EPA Performed)02/22/198809/30/1988
Removal (EPA Oversight)04/14/198810/15/1988
Removal (EPA Oversight)06/05/198912/11/1989
Removal (State Performed)09/30/198911/21/1989
Removal (EPA Oversight)06/19/199004/15/1994
Removal (EPA Oversight)12/10/199101/17/1992
Removal (EPA Performed)04/29/199210/30/1992
Removal (EPA Oversight)10/08/199212/02/1992
Five-Year Review (EPA Performed) 03/23/2000
Five-Year Review (EPA Performed) 09/30/2005
Five-Year Review (EPA Performed) 06/27/2011
Five-Year Review (EPA Performed) 08/30/2016
Five-Year Review (EPA Performed) 08/30/2021
Five-Year Review Estimated Aug - Oct 2026
Cleanup Schedule by Operable Unit
MilestoneStart DateCompletion Date
OU 01 - STREAMSIDE TLNGS (SBC)
Combined Remedial Investigation/Feasibility Study (State Performed)09/29/198309/30/1991*
Combined Remedial Investigation/Feasibility Study (State Oversight)09/30/1991*11/29/1995
Record of Decision (EPA Performed) 11/29/1995
Explanation of Significant Differences (EPA Performed) 08/31/1998
Remedial Design (EPA Oversight)05/06/199605/06/1997*
Remedial Design (State Performed)05/06/1997*02/15/2002
Remedial Design (State Performed)08/10/199804/19/1999*
Remedial Design (State Performed)04/19/1999*04/16/2004
Remedial Design (EPA Oversight)10/14/200705/05/2008
Remedial Design (State Performed)01/08/200806/28/2009
Remedial Design (State Performed)04/30/201007/08/2013
Remedial Action (EPA Oversight)08/13/199812/04/2003
Remedial Action (State Performed)04/16/200408/24/2009
Remedial Action (State Performed)08/21/2008Estimated Dec 2026
Remedial Action (State Performed)07/15/2009Estimated Dec 2026
Remedial Action (State Performed)07/08/2013Estimated Dec 2026
Operation and MaintenanceEstimated Jan 2027 
Cleanup Schedule by Operable Unit
MilestoneStart DateCompletion Date
OU 02 - AREA I
Combined Remedial Investigation/Feasibility Study (State Performed)05/27/198801/23/1990
Cleanup Schedule by Operable Unit
MilestoneStart DateCompletion Date
OU 03 - BERKELEY PT/MINE FLDNG (BUTTE)
Consent Decree (EPA Performed) 08/14/2002
Combined Remedial Investigation/Feasibility Study (EPA Performed)06/30/198805/04/1990*
Record of Decision (EPA Performed) 09/29/1994
Remedial Design (EPA Oversight)04/10/199609/03/1996
Remedial Design (EPA Oversight)03/06/199703/27/2002
Remedial Action (EPA Oversight)09/03/199611/25/1996
Remedial Action (EPA Oversight)03/27/2002 
Cleanup Schedule by Operable Unit
MilestoneStart DateCompletion Date
OU 04 - WARM SPRINGS PONDS (SBC)
Removal (EPA Oversight)07/03/199001/11/1995
Combined Remedial Investigation/Feasibility Study (State Performed)09/07/198803/22/1990*
Combined Remedial Investigation/Feasibility StudyEstimated Dec 2026Estimated December 2028
Record of Decision (EPA Performed) 09/28/1990
Explanation of Significant Differences (EPA Performed) 06/24/1991
Remedial Design (EPA Oversight)10/24/199106/30/1992
Remedial Action (EPA Oversight)06/30/1992Estimated Dec 2029
Cleanup Schedule by Operable Unit
MilestoneStart DateCompletion Date
OU 05 - REDUCTION WORK TAILINGS (SBC)
Combined Remedial Investigation/Feasibility Study (State Performed)05/27/198802/15/1989
Cleanup Schedule by Operable Unit
MilestoneStart DateCompletion Date
OU 06 - TRAVONA MINE (BUTTE)
Removal (EPA Oversight)03/31/198907/15/1996
Cleanup Schedule by Operable Unit
MilestoneStart DateCompletion Date
OU 07 - ROCKER (SBC)
Consent Decree (EPA Performed) 11/07/2000
Combined Remedial Investigation/Feasibility Study (EPA Performed)09/07/198808/02/1991*
Record of Decision (EPA Performed) 12/22/1995
Explanation of Significant Differences (EPA Performed) 09/29/2014
Remedial Design (EPA Oversight)04/22/199604/09/1997
Remedial Action (EPA Oversight)04/09/1997 
Cleanup Schedule by Operable Unit
MilestoneStart DateCompletion Date
OU 08 - SOILS (BUTTE)
Consent Decree (EPA Performed) 09/16/2020
Unilateral Administrative Order (EPA Performed) 07/21/2011
Removal (EPA Oversight)10/20/199509/21/2006
Removal (EPA Oversight)06/01/200009/21/2006
Combined Remedial Investigation/Feasibility Study (EPA Performed)02/15/198906/30/1992*
Combined Remedial Investigation/Feasibility Study (EPA Performed)04/17/2024Estimated Sept 2026
Record of Decision (EPA Performed) 09/21/2006
Record of Decision Amendment (EPA Performed) 02/04/2020
Explanation of Significant Differences (EPA Performed) 07/18/2011
Remedial Design (EPA Oversight)09/16/2011Estimated 2027
Remedial Action (EPA Oversight)09/16/2011Estimated 2035
Cleanup Schedule by Operable Unit
MilestoneStart DateCompletion Date
OU 10 - BUTTE RESIDENTIAL SOILS
Removal (EPA Oversight)08/11/199409/21/2006
Removal (EPA Oversight)05/09/200106/27/2002
OU 11 - LOWER AREA ONE
Removal (EPA Oversight)05/13/199208/31/2002
Cleanup Schedule by Operable Unit
MilestoneStart DateCompletion Date
OU 12 - WSP/INACTIVE AREA
Feasibility Study (EPA Oversight)01/15/199106/30/1992
Combined Remedial Investigation/Feasibility StudyEstimated Dec 2026 
Record of Decision (EPA Performed) 06/30/1992
Remedial Design (EPA Oversight)08/22/199305/18/1994
Remedial Action (EPA Oversight)05/18/1994Estimated 2029
Cleanup Schedule by Operable Unit
MilestoneStart DateCompletion Date
OU 13 - WEST SIDE SOILS
Unilateral Administrative Order (EPA Performed) 08/19/2019
Combined Remedial Investigation/Feasibility Study (EPA Performed)08/21/2018Estimated January 2026
Combined Remedial Investigation/Feasibility Study (EPA Oversight)08/26/2019Estimated January 2026
Record of Decision Estimated March 2027
Remedial DesignEstimated March 2027Estimated 2029
Remedial ActionEstimated 2029 

*NOTE: This date may not reflect the actual start or actual completion of the milestone. Either the lead for this activity changed, the project was phased, or the project did not fit the normal definitions of activities tracked in this table.

NOTE: Dates and estimated dates will not display for all milestones. Estimated dates only display for milestones planned within the next three fiscal years. Estimated dates and start dates will not display for the following enforcement milestones: Administrative Order of Consent, Consent Decree and Unilateral Administrative Order. Start dates will not display for the following document milestones: Five-Year Review, Record of Decision, Record of Decision Amendment, Explanation of Significant Differences and Partial NPL Deletion.

DISCLAIMER: The data on this page are derived from the Superfund Enterprise Management System and are solely for informational purposes. The data cannot be relied upon to create any substantive or procedural rights or requirements enforceable by any party in litigation with any member of the public, states, tribes, the United States or any federal agency. EPA reserves the right to change these data at any time without public notice.

Silver Bow Creek - Butte Area

  • Background
  • Community Engagement Calendar
  • Community Resources
  • Current Site Status
    • Cleanup Schedule by Operable Unit
    • Performance Measures
  • Documents
  • Frequently Asked Questions
  • Non-EPA Site Contacts
  • Proposed Plan for Lead Cleanup
    • Factsheet
  • Public Information Repositories
  • Redevelopment
  • Risks
  • Sampling and Monitoring
  • Tips for Reducing Lead Exposure in the Butte Community
Contact Us About the Butte Area-Silver Bow Creek Site
Contact Us About the Butte Area-Silver Bow Creek Site to ask a question, provide feedback, or report a problem.
Last updated on October 9, 2025
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