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1 <br /> Water will be obtained from the gravel quarry by using clean five-gallon buckets. The water will <br /> then be transferred into narrow mouth polypropylene bottles. The bottles will be sealed and <br /> transported to the CGRS field office.The water will be filtered to 120µm prior to use. <br /> A modified form of ASTM D4874-95 will be used to perform the leaching tests. This ASTM <br /> method is use for determining inorganic concentrations that would potentially leach from a column <br /> apparatus filled with fly ash and native soil. The purpose of the leaching experiment is to simulate, <br /> to the extent possible, the interaction of the fly ash placed in contact with the native material at the <br /> ' Varra test site under saturated conditions. The following are modifications to ASTM D4874-95 <br /> (ASTM method attached as Appendix BY <br /> The column is constructed of plexiglass, 762 mm (30 in.), with an inside diameter of 76.2 mm (3 <br /> in.). The cylinder wall is approximately 6 mm thick (1/4 in). The endplates are constructed of <br /> stainless steel and are attached to the column by three, 6 mm threaded rods. A port with a valve is <br /> attached to the bottom and top of the endplates. A ceramic plate, with a nominal pore diameter of <br /> 70 to 120 µm is used at both ends of the endplates. The ceramic plate thickness is about 6 rim, with <br /> a diameter equal to the inside diameter of the column. Tubing used with the apparatus is about 6 <br /> mm outside diameter and is constructed of polypropylene. The tubing attaches to the bottom port <br /> ' and the constant head source, and to the top port for sample collection. Flow through the column is <br /> from bottom to top, or in the up-flow mode. <br /> ' The column will be filled with fly ash and native material (sand and gravel)obtained from the Varra <br /> gravel operations facility. Prior to filling the column with fly ash (a combination of Class F silo ash <br /> with gypsum and Cherokee 4 fly ash with sodium) and native material, a divider will be placed in <br /> ' the column to allow a vertical separation of the materials. This divider will be removed as the <br /> column is filled. Approximately 70 percent of the column will be filled with fly ash and the <br /> remainder of the column will be filled with the sand and gravel. The rational for the 70% fly ash/30 <br /> ' % soil ratio is that the proposed large scale disposal of fly ash will entail leaving about 30% of <br /> native material in the disposal cells as a permeable channel. This will allow more uniform <br /> groundwater flow through the disposal area as indicated by analytical solutions. Harr (1962) <br /> presents an analytical solution for the case of a partially penetrating no flow cutoff wall, very <br /> ' similar to the proposed pilot trench. Using this solution, the trench was simulated as a no flow cut- <br /> off wall with a depth of penetration into the aquifer of fifty percent (ten feet as anticipated in field <br /> conditions). The analytical solution indicated that a head difference of less than 0.01 feet across the <br /> ' trench would be sufficient to cause the ground water flow to bypass the trench as underflow. The <br /> results of simulations using the TWODAN analytical groundwater flow model and the analytical <br /> solution presented by Harr, indicate that the trench would have minimal impacts on the ground <br /> ' water flow patterns. These simulations also indicate that for the most part, ground water would <br /> flow around or under the trench rather than through the trench. <br /> ' The total sample volume in the column is approximately 3,474 cubic centimeters (212 in`). <br /> Assuming a dry bulk density of 1.3 grams per cubic centimeters, the mass of the sample is about <br /> 4,516 grams (10 pounds). Once the column is filled, the divider will be removed from the column, <br /> and the ceramic plate and endplates will be assembled. The columns will be filled in five separate <br /> ' equal layers and will be compacted to the expected field density (anticipated at .9 and 1.65 grams <br /> per cubic centimeter for ash and soil respectively). After the column is filled the tared mass will be <br /> determined. <br /> ' Water obtained from the gravel pits at the Varra facility will be used as the reagent water to saturate <br /> the column from a constant head source. The constant head source in this case will be a water <br /> ' reservoir pressurized to 20 psi using helium. The reagent water will be submitted for laboratory <br /> analyses to determine the same properties and analytes of interest that will be measured in the <br /> column effluent. <br /> ' Varra Companms <br /> Quality Assurance Projeci Plan <br /> Page 7 <br />