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METEORIC WATER MOBILITY PROCEDURE (MWMP) <br /> Standardized Column Percolation Test Procedure <br /> 1. Scope <br /> The purpose of the Meteoric Water Mobility Procedure (MWMP) is to evaluate the potential for dissolution <br /> and mobility of certain constituents from a mine rock sample by meteoric water. The procedure consists of <br /> a single-pass column leach over a 24 hour period using a mine rock sample to extraction fluid (effluent) <br /> ratio of 1:1. The extraction fluid is Type II reagent grade water(1). <br /> 2. Reference Documents <br /> 2.1 Meteoric Water Mobility Procedure, Bureau of Mining Regulation and Reclamation, Nevada Division <br /> of Environmental Protection, 9/19/90. <br /> 2.2 Standard Methods for the Examination of Water and Wastewater, 18th edition,APHA/AWWA/WEF, <br /> 1992, Method 1080. <br /> 3. Significance and Use <br /> 3.1 This procedure is intended as a means for obtaining extracts from mine rock samples. The extracts <br /> may be used to evaluate the final pH and release of certain constituents of mine rock exposed to meteoric <br /> events. <br /> 3.2 The pH of the extraction fluid used in this procedure is to reflect the pH of precipitation in the <br /> geographic region in which the mine rock is being evaluated (in this case, the State of Nevada). <br /> 3.3 This procedure is designed to mobilize potential contaminants present m the solids, so that the <br /> resulting extract can be used to assess leachate which could potentially be produced from mine rock in <br /> the field <br /> 3.4 This procedure produces extracts that are amenable to the determination of both major and minor <br /> (trace)constituents. When minor constituents are being determined, it is especially important that <br /> precautions be taken in sample storage and handling to avoid possible contamination of the samples. <br /> 3.5 This procedure may not be suitable for obtaining extracts from finely divided solids (such as clayey <br /> soils, sludges, mill tailings, etc.).An alternate extraction procedure may then be advised. <br /> 4.Apparatus <br /> 4.1 Extraction Device, PVC column of 15 cm (6 inch) O.D. of sufficient height to contain a minimum <br /> of 5 kg of minus 5 cm (2 inch) mine rock sample and sufficient additional height to contain applied <br /> extraction fluid should blinding (ponding) occur. (Approximately 8 kg of minus 5 cm solids per 30.5 cm of <br /> column height). For a 5 kg mine rock sample a 15 cm O.D. x 45 cm high column is recommended. <br /> Additional column height will be required for mine rock sample quantities greater than 5 kg. The bottom of <br /> the column must be sealed (bubble cap) and a solution discharge outlet situated above the sealed bottom <br /> of the column and below the"punch plate". A drawing of the extraction device is appended. <br /> 4.2 Glass Wool (inert) -glass wool is placed onto the"punch plate" before loading the mine rock charge <br /> into the column to minimize fines migration and onto the top of the mine rock charge after column loading <br /> to aid even extraction fluid distribution. <br />