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cuttings from the temporary cuttings pits in the shafts, grading of disturbance areas to blend with the surrounding <br />terrain, soil material replacement, and reseeding with the appropriate permanent revegetation seed mixture <br />(Pastureland Mixture for Shaft site and road, and Rangeland Mixture for Pipeline corridor). Boreholes will be <br />plugged and sealed in accordance with applicable State Engineer requirements, and pipelines will be cut-off below <br />grade, capped, and buried in-place. <br />WMD Stabilization Boreholes (MR11-253) <br />In order to address immediate safety and operational concerns associated with localized ground stability issues, TC <br />drilled two stabilization boreholes in the 17 -Left Gateroad to allow concrete to be pumped into gateroad and <br />crosscut areas, forming a series of supplemental support pillars. <br />Activities associated with this ground stabilization effort included; <br />• Establishment of temporary drainage and sediment control measures <br />• Soil material removal and placement in a temporary stockpile <br />• Construction of a short temporary access road <br />• Construction of a 200' x 300' drill pad <br />• Drilling and casing of 2 boreholes from the pad <br />• Set-up of a portable concrete batch plant on the existing 18 -Left Shaft Pad, or direct delivery of pre -mixed <br />concrete to the borehole site <br />• Extension of a temporary concrete transfer line on the ground surface between the batchplant and the drill - <br />site <br />• Pumping of concrete down the drillholes into the underground workings <br />• Plugging and sealing of the drillholes <br />• Reclamation and restoration of all related temporary surface disturbance <br />The location and configuration of the proposed activities are shown on Figure 49U -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 I -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 batch -plant 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 />MR14-283 2.05-45.21 10/30/14 <br />