Ned Black, US EPA R9 CERCLA EcologistchannelingJohn Hillenbrand,US EPA R9 CERCLA MiningCoordinator

Cordero

NPL Superfund Steps

• Remedial Investigation = – Nature and Extent, – Conceptual site model, – Risk based cleanup goals = 0.2 mg/kg MeHg in fish

• Feasibility Study = – Options for cleanup

• Record of Decision =– What is the action we going to take at this site

Mercury Levels in Fish vs Mine Sources in Watershed

Lake Hg Concentration Gold Minesin fish (mg/kg) in Basin

Patagonia 0.2 52

Arivaca 1.0 -1.5 0

Pena Blanca 1.3 -1.5 2

Our Challenges/Assumptions at Hg Sites*

• Successful remediation requires source control• Hg methylation and subsequent biomagnification in

the food web can be hyper efficient• Air deposition Hg won’t be ignored• Dollars for removals and remediation are scarce• Stakeholders** prefer we spend $$ on successful

projects *Not a complete list** e.g., Citizens, Congress, HQ Bean Counters