graded, and the pad surface was graveled to control erosion and sediment and provide an all- weather operating
<br />surface. The completed thickener underflow borehole installations include the light -use road (6RT only), a soil
<br />material stockpile (pad and road); the drill -pad (lMN — 25 x 180 feet, 6RT- 70 x 70 feet); the 6 -inch cased
<br />boreholes, 14 -inch cemented surface casings, and covered 8 -foot diameter CMP culvert manholes with lightening
<br />protection.
<br />Pipeline installation involved removal and windrowing of soil materials from the pipeline construction corridor
<br />(maximum - 40 -foot wide); trenching in most areas; placement of suitable bedding materials; placement,
<br />connection, and pressure testing of the pipelines; backfilling and compaction of suitable fill materials around and
<br />over the pipelines; backfilling and compaction of the trench; regrading; replacement of soil materials; and
<br />revegetation of all disturbed areas. Where the pipelines pass under RCR27, the Twentymile Mine railroad spur,
<br />and Foidel Creek, the pipeline trench was expanded to provide room for horizontal boring equipment, and the
<br />pipelines were trenched or bored under these features. Because pipeline placement necessarily'involved activities
<br />within the Foidel Creek buffer zone, TCC requested and received a temporary variance from the regulatory
<br />requirements for operations within a buffer zone. The pipelines are a double HDPE pipe system in critical areas,
<br />with a 6 to 8 -inch carrier pipe inside a larger (maximum size - 10 -inch diameter) containment pipe, buried
<br />approximately 5 -feet deep. The 1MN pipeline extends approximately 1,800 feet, with the 6RT pipeline extending
<br />approximately 8,000 feet. Electronic moisture sensors, along with pump controls, and shut -off valves provide for
<br />timely detection, shut -off, and isolation of the pipeline in the event of pipeline leakage. Access /inspection manholes
<br />and pipe -tees for the moisture detection system are located at key points along the pipeline routes.
<br />When the new Washplant and Thickener were installed, a new Thickener Overflow Sump was constructed to
<br />contain minor amounts of washdown water and to serve as a temporary catch basin for the contents of the
<br />Thickener, if required for maintenance or under upset conditions. The Thickener Overflow Sump is located
<br />between the Refuse Conveyor and Sedimentation Pond D. The Thickener Sump is partially incised, incorporates a .
<br />compacted clay liner to minimize seepage, and is sized to fully contain the contents of the Washplant II Thickener
<br />(150,000 gallons) plus minor amounts of washdown water and incident precipitation for the design event.
<br />•Impoundment design, operation, and maintenance information for the Thickener is provided in Exhibit 8X. Given
<br />that the potential for both the Washplant I and Washplant II Thickeners to experience an upset or require
<br />maintenance at the same time is negligible, with completion of the Washplant H Thickener Overflow Sump, the
<br />Washplant I Thickener Overflow Sump was decommissioned, filled -in and replaced by a discharge pipe from the
<br />Washplant I Thickener to the new Washplant II Thickener Overflow Sump. As an incised and closed basin (ie: no
<br />outlet) the only potential inputs to the Sump are thickener overflow, washdown water, or minor incident
<br />precipitation, which are subsequently pumped back into the system by a portable floating pump installation. The 4-
<br />inch thickener overflow line has been extended to the new Thickener Overflow Sump (4,800 feet), allowing
<br />overflow from either thickener to be controlled by valves and routed to the Sump. Water level in the Sump is
<br />monitored and managed as part of the ongoing Washplant operations.
<br />Given the power and system control requirements for the Washplant, an associated Motor Control Center
<br />(MCC) /Office Building was constructed immediately adjacent to the Washplant. The MCC /Office Building houses
<br />electrical, control, and monitoring equipment for the Washplant and includes office space. The building consists of
<br />three connected modular steel containers (2 - 8 x 40 x 10 feet high, and 1 -8 x 20 x 10 feet high), located on the
<br />north side of the Overland Conveyor and Washplant II. The building sets on a reinforced concrete slab floor (20 x
<br />60 x 0.75 feet thick).
<br />A new Coal Sampling Station, located on the Overland Conveyor, to the west of Washplant II and Sedimentation
<br />Pond D, was installed to provide sampling capabilities prior to discharge to the BOB stockpile. The coal sampling
<br />system consists of an automated sweep sampler, which cuts samples from the coal stream on the Overland
<br />Conveyor at regular intervals, a small sample crusher, a sample splitter to reduce sample volume, and associated
<br />chute -work and control and dust collection systems. The coal sampling system is housed in a steel frame building
<br />with steel siding and roof (20 x 20 x 25 feet high), located on the south side of the Overland Conveyor. The
<br />isbuilding sets on a reinforced concrete slab floor (22 x 22 x 0.75 feet thick).
<br />A new 69 KV distribution line was extended approximately 300 feet from the existing 69KV line to a new
<br />substation location adjacent to the Overland Conveyer. Powerline construction involved the limited disturbance
<br />required to place 4 powerpoles, with pole placement avoiding the Foidel Creek buffer zone. Installation of the new
<br />TR 11 -77 2.05-32.4 07/20/11
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