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The third stage will require placing earthen materials over the top of the fly ash grout. Soil and <br /> earthen material will be excavated from above the feature near the western margin of its rim. <br /> The estimated dimensions of the area within the feature requiring earthen materials is twenty one <br /> feet (21') by sixteen feet (16')by four feet (4') depth. When placed within the feature, the <br /> earthen material will be compacted by tamping it by hand. The volume of earthen materials <br /> needed is estimated to be fifty cubic yards (50 yd3). Excavation of earthen materials will be <br /> accomplished in a manner so that no cut slopes steeper than 2.5H : IV are left upon completion <br /> of excavation. The material will be placed within the feature so that the top of the material forms <br /> a flat surface. <br /> When excavation is completed, the surface of the excavation area will be left in a roughened <br /> condition. This cut surface will be seeded and mulched, as described in Section 20.0 of the <br /> General Bid Specifications, 1996. OWNER will provide the seed, CONTRACTOR will <br /> provide certified weed free straw mulch, chemical fertilizer, labor and tools. <br /> The fourth stage of the closure involves introduction of fly ash grout into a small active vent on <br /> the eastern margin of the feature. The vent will be excavated to a minimum depth of three feet <br /> (3') to determine whether a larger opening exists below. This vent will be filled with fly ash <br /> grout to refusal. It is estimated that five cubic yards (5 yd3) of grout will be needed to <br /> accomplish this task. <br /> The final stage of filing the feature will require the placement of fly ash grout over the earthen <br /> fill. The estimated dimensions of this grout cover are thirty feet(30')by twenty feet(20'). The <br /> thickness of the grout will be one and one half feet (1.5') at the downhill portion of the feature, <br /> and three feet (3') at the uppermost edge of the feature. The top (surface) of the grout will be <br /> completed at a consistent grade, falling from south (uphill) to north (downhill. The total volume <br /> of grout need for this stage of construction is estimated to be fifty cubic yards (50 yd3) <br /> NOTE that the total estimated volume of fly ash grout necessary to complete this closure is <br /> eighty seven cubic yards (87 yd3). If additional grout materials beyond this estimation are <br /> necessary to complete the closure to these specifications, the additional material will be paid <br /> under Task 3, Provide and Install Additional Fly Ash Grout, per Specifications. <br /> A surface water diversion ditch will be constructed on the uphill side of the feature. The <br /> diversion will be approximately sixty five feet(65')in length. It will begin twenty feet (20') <br /> uphill, and ten feet (10') to the east of the feature, and will be constructed so that water flows to <br /> the gully immediately west of the feature. The ditch will be V shaped, having a minimum depth <br /> of two feet (2') as measured on the down hill side of the ditch, and a minimum width at its crest <br /> of four feet (4'). PROJECT MANAGER will mark the location of the ditch in the field prior to <br /> construction. The material cut to create the ditch can be used as part of the earthen cap <br /> constructed as part of this closure. <br />