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  2. Bonita Peak Mining District
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Operable Units

Below, EPA has provided a list of the remedial actions selected pertaining to each operable unit.

EPA issues Records of Decision (RODs) to explain which cleanup methods will be used at Superfund National Priorities List sites. EPA has two primary documents that it may use to identify changes to the remedies selected in RODs. EPA uses a ROD Amendment when it needs to make a fundamental change to the remedy. EPA publishes an Explanation of Significant Differences (ESD) for significant changes.

During cleanup, complex sites may be divided into several distinct areas to make the response more efficient. These areas, called operable units (OUs), may address geographic areas, specific problems, or medium (e.g., groundwater, soil) where a specific action is required. The remedies are displayed for the OU numbers indicated in the original decision document. OU numbers may change over time.

EPA is working to improve data quality. The information presented on this page is undergoing review for accuracy and completeness, and may be subject to change.

OU IDNameDecision DocumentCleanup Technologies Selected
in the Decision Document
00SITEWIDENot applicable 
01OU1 SITEWIDE - REMEDIALRecord of Decision
May 20, 2019
Consolidate (onsite)
Dewatering
Institutional Controls
Drainage/Erosion Control (dike/berm/levee)
Excavation
Monitoring (leachate)
Monitoring (surface water)
Cap (engineered cap)
Cover (evapotranspiration)
Cover (soil)
Drainage/Erosion Control (ditch)
Drainage/Erosion Control (other, not otherwise specified)
Monitoring (liquid waste)
01OU1 SITEWIDE - REMEDIALRecord of Decision
April 30, 2021
Residuals Treatment/Disposal (onsite)
Cover (evapotranspiration)
Drainage/Erosion Control (ditch)
Cap (engineered cap)
Containment (other, not otherwise specified, onsite)
Institutional Controls
Consolidate (onsite)
Excavation
Monitoring (groundwater)
Dewatering
Leachate Control
02OU2 MAYFLOWERNo decision document 
03OU3 BONITA PEAK GROUNDWATER SYSTEMNo decision document 
04OU4 BEN FRANKLIN MINENo decision document 
05OU5 LONDON MINENo decision document 

Bonita Peak Mining District

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Contact Us About the Bonita Peak Mining District
Contact Us About the Bonita Peak Mining District to ask a question, provide feedback, or report a problem.
Last updated on April 21, 2026
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