2020-12-02_PERMIT FILE - M2020061

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10/8/2020 Federal Register::National Oil and Hazardous Substance Pollution Contingency Plan:Partial Deletion of the California Gulch Superfund... D&RGW's 1996 Final Stockpiled Fine Slag Feasibility Study(1996 OU3 FS)focused on the AV Smelter Slag Pile's existing fine slag subpile and fine slag potentially generated from future ballast production.Based upon the 1993 SFS and 1993 D&RGW CD,the remedial action objective for the stockpiled fine slag was to:prevent leaching of metals of concern in concentrations that would have an adverse impact on soils,surface or ground water near the slag piles.The 1996 OU3 FS provided a detailed analysis of the three retained remediation alternatives(no action,institutional controls,and resource utilization)from the 1993 SFS as applied to the stockpiled fine slag.The result of the 1996 OU3 FS for the stockpiled fine slag was a Proposed Plan with a No Action Alternative for the stockpiled fine slag subpile of the AV Smelter Slag Pile.In September 1996,the Proposed Plan was issued with a preferred alternative of"No Action,"with a contingency for future utilization of the slag. OU3 Selected Remedy The EPA issued the Stockpiled Fine Slag—Arkansas Valley Smelter Slag Pile ROD for OU3 on May 6,1998 (1998 OU3 ROD).Based on consideration of CERCLA requirements,detailed analyses of alternatives,and public comments,the EPA determined that a No Action alternative was the appropriate remedy.The No Action alternative leaves the stockpiled fine slag in its existing condition with no control or cleanup planned. The No Action alternative includes a provision,denoted as a contingency,for future utilization of the slag,if it is encapsulated prior to its use or reuse.The 1998 OU3 ROD also provides a provision to use the slag in the future if regional market demand exists for the material as a component in construction materials. The 1998 OU3 ROD did not require maintenance of the fine slag piles.Any future use of the slag would require encapsulation prior to reuse.Encapsulation can include the use of fine slag in concrete or asphalt aggregate,as a road base,or as backfill(so long as the slag is chemically bound or physically separated from an exposure by a barrier consisting of a different material). Sampling in the Poverty Flats rail yard property and the Harrison Avenue property shows levels of lead in soils above levels that would allow for unlimited use and unrestricted exposure,i.e.,above the residential action level established for OU9,Residential Populated Areas of the Site.In addition,the Mineral Belt Trail, which was constructed on the former railroad easement,acts as a cap for fine slag and residual slag remains in other parts of OU3.Thus,the August 6,2014 ESD(2014 OU3 ESD)addresses the need for ICs,and documents the decision to require ICs for OU3.In addition,the use of the term"contingency"for fine slag utilization in the 1998 OU3 ROD is clarified in the 2014 OU3 ESD.Fine slag can be used for future commercial purposes by following the requirements set out in the 1998 OU3 ROD. OU3 Cleanup Standards As the final determination in the 1998 OU3 ROD was No Action ROD,no cleanup standards were identified for fine slag in the record of decision.The OU12 remedy addresses site-wide surface water and groundwater contamination. OU3 Response Actions No response actions were taken pursuant to the No Action ROD.The ICs established by the City and County ordinances were response actions that were incorporated into the OU3 remedy by the ESD.Lake County,on March 3,20o9,and the City of Leadville,on May 7,2013,implemented ICs in the form of local ordinances, amending the Land Development Codes and adopting regulations that protect both engineered and non- engineered remedies at OU3.A best management practice handout is provided to all applicants applying for https://www.federalregister.gov/documents/2016/02/09/2016-02601/national-oil-and-hazardous-substance-pollution-contingency-plan-partial-deletio... 13/16