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The location and configuration of the proposed activities are shown on Figure 49W -F1, WMD Stabilization <br />Boreholes. <br />Temporary drainage control and sediment control measures for these activities include placement of a 36 -inch x 80 <br />foot CMP culvert in the borrow ditch for County Road 27 to allow road runoff to pass under the temporary access <br />road (culvert is sized to match the existing downgradient culvert crossing under the road), construction of a temporary <br />diversion ditch and catch basins upgradient of the drill pad to intercept and route any natural runoff around the pad, <br />and placement of straw wattles downgradient of the pad to intercept and control any runoff that escapes the pad. <br />Temporary drainage and sediment control measures will be in -place before any other activities proceed. <br />Available soil materials will be recovered from both the short access road segment and the pad area and placed in a <br />temporary stockpile upgradient of the pad. With a road area of approximately 40 x 240 feet, a pad area of <br />approximately 200 x 300 feet, and an average soil recovery depth of approximately 1 -foot, approximately 2,600 bcy <br />of soil material will be recovered and stockpiled. Pad construction will involve cut and fill grading of the pad area to <br />establish a level surface approximately 200 x 300 feet. A temporary cuttings pit, with a capacity of approximately 60 <br />cy, will be excavated during pad construction, and the excavated material will be incorporated into the cut/fill balance. <br />The pad will be constructed so that surface runoff from the pad area will be retained on the pad (ie: the pad surface <br />will be sloped to drain to the cuttings pit). <br />Two boreholes, approximately 13- inches in diameter and 1,425 feet in depth will be drilled from the pad to intercept <br />the 17 -Left gateroad. During drilling operations, any excess cuttings will be removed from the cuttings pit and <br />trucked off -site by a qualified contractor, in order to maintain adequate buffer capacity in the pit and avoid any <br />discharge. The boreholes will be cased with up to 8- 5/8 inch steel casing and the casing will be grouted in the hole. <br />A temporary concrete batch plant will be set -up on the existing 18 -Left Shaft Pad, and a temporary concrete transfer <br />line will be laid on the ground surface between the batchplant and the boreholes. Concrete will be pumped through <br />the transfer line and down the boreholes into the 17 -Left gate -road, where it will be transferred through an <br />underground line to the area of instability to establish supplemental support pillars. <br />Once concrete pumping operations are completed, the temporary transfer line and batchplant will be moved off -site, <br />and the boreholes and associated disturbance areas will be reclaimed. Boreholes will be plugged and sealed in <br />accordance with applicable State Engineer requirements. Any residual cuttings in the cuttings pit will be allowed to <br />dry-out, and the cuttings pit will be completely backfilled. The pad area and road will be regraded to their <br />approximate original configuration and to blend with the surrounding terrain, the temporary diversion ditch will be <br />removed, stockpiled soil material will be replaced, and all disturbance areas will be reseeded with TC's standard <br />Pastureland Seed Mixture, or an alternate seed mix, if requested by the surface landowner. <br />MRl 1 -253 2.05-45.21 05/02/11 <br />