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Prior to NEI accepting a feedstock material, the owner of the feedstock will <br /> provide ABA NNP and TCLP analytical results to determine the need for special <br /> handling or containment. NEI will conduct regular ABA and TCLP testing of the <br /> feedstock, at the material owner's expense, during milling to ensure the feedstock <br /> material character remains consistent throughout milling. In the event the material <br /> character changes, the handling and containment will change accordingly. <br /> Feedstock sampling will occur for every 20,000 tons of material to be <br /> received. A series of grab samples will be taken from within the stockpile at the <br /> source location as well as along the periphery so that up to a 1,000-pound sample <br /> containing a mixture of coarse and fine material is obtained. This sample will be <br /> crushed, blended, and split to produce a representative sample for further analysis. <br /> The following analytical tests will be conducted on all feedstock and byproduct <br /> material to understand the potential environmental effects and subsequent <br /> appropriate storage, handling and/or disposal of byproduct material: <br /> • TCLP to determine if the material needs to be handled or stored as hazardous <br /> waste. The results of this testing will be compared to the limits identified in <br /> the Code of Federal Regulations (CFR) 40 #261.24 and the Regional <br /> Screening Levels (RSLs) as defined by the <br /> USEPA (httr)s://www.epa.ciov/risk/regional-screening-levels-rsls-users- <br /> uide). <br /> • Acid base accounting (ABA) to determine the Net Neutralization Potential <br /> (NNP). <br /> No designated chemicals will be used in milling. GTM relies on a ball mill and <br /> shaker tables that process the slurry via gravity separation. The slurry fines pass <br /> through a dewatering screen. The water is tested for pH, and continues on to <br /> recirculate. The concentrate is collected in 55-gallon drums and prepared for <br /> shipping to the refiner. <br /> [6.4.21(6)] Designated Chemical and Material Handling <br /> Description of Designated Chemicals <br /> Milling activities are enclosed in a metal building. Designated chemicals will <br /> not be used during milling; therefore, disposal or detoxification processing for mill <br /> chemicals will not be necessary. <br /> Feedstock material has the potential to have been toxic and/or acid forming <br /> while stockpiled on the mine site from which it was extracted. The purpose of the <br /> mill is to remove these legacy stockpiles from the valley, thus reducing toxic and/or <br /> acid forming source material from the watershed and environment. ABA and TCLP <br /> will be performed at a minimum to determine the need for special handling or <br /> storage prior to and during milling. <br /> Byproduct material will also be characterized via ABA/NNP and TCLP, also to <br /> determine the need for special handling and storage as well as to determine <br /> candidacy for a beneficial end use. Byproduct material that passes TCLP and has an <br /> ABA NNP >+20 will be candidate for beneficial end use. <br /> Material Handling <br /> Both feedstock and byproduct material will be stored in three-sided concrete <br /> storage bins that have a 2% center sloping concrete floor. The concrete sides will <br /> Page 17 of 23 <br />