Laserfiche WebLink
Information to Support Denison BL MEnuironinenta /Assessment Remand <br />Denison Sunday Miles Group <br />Association (NMA) contacted the American Society of Testing Materials <br />(ASTM) to undertake a standardization program for the method. A <br />cooperative program was developed and solutions for metals analysis <br />were preserved and sent to the U.S. Geologic Survey (USGS) Laboratories <br />in Denver to determine the reproducibility and repeatability of the <br />leaching. Based on this process, ASTM developed the Standard Test <br />Method for Column Percolation Extraction of Mine Rock by the Meteoric Water <br />Mobility Procedure (ASTM Method E2242). A copy of the ASTM method <br />was provided in the E'nvil-onmenlal Geoclemislrylnvesliga101,- ofRock <br />andSoil1Ylalerial(CDM 2009). <br />The purpose of the MWMP is to evaluate the potential for dissolution and <br />mobility of certain constituents from a mine rock sample by meteoric <br />water. Alternatively, the synthetic precipitation leachate procedure <br />(SPLP) and toxicity characteristic leachate procedure (TCLP) were <br />developed for use in the assessment of waste disposal facilities rather <br />than minin operations. The TCLP (EPA Method 1311) evaluates metal <br />mobility in a sanitary landfill, while the SPLP (EPA Method 1312) was <br />developed to evaluate the fate and transport of metals in an engineered <br />land disposal facility from which municipal solid waste is excluded. <br />The MWMP procedure consists of a single -pass column leach over a <br />24 -hour period using an extraction fluid (effluent) to mine rock ratio of <br />1:1. The extraction fluid is Type II reagent grade water. The ratio of <br />liquid to solid material used for the MWMP is more characteristic of <br />conditions in the and west; the SPLP uses a ratio of 20:1 while the MWMP <br />has a ratio of 1:1. The use of a 20:1 solution to solid ratio in the SPLP test <br />causes a dilution of any potential trace metals that are dissolved from the <br />sample, which decreases the sensitivity of the SPLP test to identify <br />potentially deleterious elements released from the sample. The SPLP <br />extraction fluid is slightly different from the MWMP extraction fluid <br />because it uses Type II regent grade water that has been adjusted to a pH <br />of 5.0 (to simulate meteoric water in the western US) to simulate natural <br />precipitation. However, Type II reagent grade water has a very low <br />buffering capacity to resist changes in pH, and therefore the acid addition <br />provides only negligible acidity in the extract solution. In leaching tests of <br />mine rock, it is the mine rock itself that exerts the dominant control on the <br />pH of the extraction fluid. <br />Comment 2 6W21 i e.• 4. L I Denison has concluded that "development rock areas where <br />cadmium locally exceeds the wildlife screening criteria are very small, relative to <br />home and /or foraging ranges ", "Threatened or endangered species, or suitable <br />habitat for those species, are not present... Therefore, complete mitigation of <br />potential risks to all individual wildlife organisms is not warranted. ", and "It is <br />unlikely that potential adverse effects to wildlife related to direct contact risks <br />Final Sunday Mines BLM Remand Letter.doc 13 <br />