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Section 780.21(c) Continued. <br />I <br />surface elevation of each hole is shown on Map 6, Kerr Mine Area <br />Geology; lithologic loge of each hole are shown in Exhibit 22, <br />Drill Aole Logs. A stratigraphic cross-section through each of the <br />seven holes is shown on Map 41, stratigraphic Croae-Section M - <br />Leaching Study. Average spacing between drill holes is 1,300 feet. <br />A batch system of spoil leaching was used in which each sample is <br />successively wetted until the E.C. readings of the leachate are <br />below the desired limit. In this case, the desired limit is 533 <br />micro mhos per cm, which is the baseline E.C, of the groundwater in <br />the area to be disturbed by mining. Ground water quality is more <br />fully discussed under Section 779.15, <br />Each sample was prepared for analysis according to the following <br />technique: <br />• 1) Grind spoil sample to less than O.Smm; <br />2) Weigh out 2.50 grams of ground sample; <br />3) Add 80 ml of distilled water to sample, stir thoroughly by <br />hand; <br />4) Cover sample, let stand for 24 hours; <br />5) Extract leachate sample from spoil/water mixture with a <br />Buechner type funnel until leachate stops dripping; <br />6) Measure and record volume and E.C. value of leachate sample. <br />7) Rewet spoil sample with 80 ml distilled water; <br />8) Chop spoil/water mixture with spatula and mix thoroughly in a <br />food blender for 60 seconds; <br />9) Repeat steps 5-8 until E.C, is less than 533 umhos. <br />Room temperature must be maintained at a constant 25°C. <br />Following the extraction phase of the leaching study experiment, <br />all leachate samples derived from a single overburden sample were <br />• combined and analyzed for the constituents shown in Table 65, <br />780-1I8 <br />