2001-12-11_PERMIT FILE - C1982056A (5)

Home Browse Search

FCB Treatment Facility The FCB Treatment Facilit}~ teas modified from its initial design to allow better utilization of the three cells. The .initial design allowed for using two out of three cells at any one time. The interpond piping was modified to use all three cells to allow for increased detention time. The piping system has the following components: 1) influent pipe from dewatering borehole(s); 2) interpond piping; and 3) discharge lines from westem most pond. All of the interpond and discharge piping is 12 inches in diameter. The water from the facility discharges into Fish Creek. A chemical injection system is used to inject sodium hydroxide into the mine influent prior to it entering the first settling cell. The treated influent then flows from the eastern cell into the middle cell and then discharges out of the western cell. See Map 32 for the flow path of the mine water discharge. If needed, an acid drip can be used in the westem most cell to treat the effluent to ensure compliance with the discharge permit. The build up of settled material will be monitored on a periodic basis and the cell cleaned as necessary. The water quality, i.e. efficiency of removing iron, will be monitored to determine when the cell should be cleaned out. The removed material will be hauled to TCC's surface facilities area and placed there. It is anticipated that the material will be placed above the spoil aquifer level and encapsulated in clay. This will minimize leaching of iron into the spoil aquifer. The construction of the FCB Treatment Facility required a combination of cutting and filling. Prior to any construction, the site was cleared of organic material. All embankments were constructed to a 3:1 slope. Bentonite or local clay was added to the embankment material and pond bottom to prevent seepage. The bentonite or local clay and soil was wetted and rolled to provide a good seal. The area was seeded with an approved perennial seed mixture, i.e. pastureland mixture (Table 53, Volume IV). Preparation Plan & Emergency Discharge Sump The Prepazation Plant Emergency Discharge Sump is located in the preparation plant facilities area dotvnslope from the main preparation plant building and thickener tank as shown on Map 24. The sump is an incised structure. Surface and near surface materials in the pond area have a relatively high clay content, which will minimize seepage. Sump outslopes were constructed at 3H1:1V or less and interior slopes will not exceed 2H:1V. The sump, which is approximately 40 feet by 55 feet with a maximum depth of 6 feet and a capacity of approximately 0.32 acre-feet is designed as anon-discharging sump and is sized to contain the full capacity of the preparation plant thickener tank and both direct precipitation and surface runoff within the sump area from the 10-year, 24-hour storm event. Under normal conditions, fluid Flow within the preparation plant occurs within aclosed-loop system, with no discharge and additions of water to compensate for entrained water contained within the clean coal products or coal refuse. 'Normally, any spillage or washdown water in the plant will flow to sumps or closed drains and be recycled r,wfrl to the preparation plant fluid circuit.CHowever, wash down water can be piped to the Pit 2 area~Under emergency '~° conditions such as an extended power outage, however, the Emergency Discharge Sump rovides secondary storage capacity for the preparation plant thickener and any potential spillage. As a nondischarging structure, the sump did not have either a principal or emergency spillway- Any precipitation, which accumulates in the sump is normally lost through evaporation.' Discharge to the pond or any significant accumulations of precipitation is removed from the sump and pumped back to the preparation plant fluid circuit. Since the pond is utilized on an emergency basis, installation of a permanent pump cannot be justified. TCC utilized one or more portable pumps as necessary to pump water accumulations from the Emergency Discharge sump to the preparation plant.. The sump receives water periodically pumped from the reclaim tunnel sump. The volume of water pumped from the reclaim ttmnel is not significant as it is associated with wash down water or water from the coal. ~~ In the event the material placed in the emergency discharge sump cannot be pumped back into the preparation plant it will be pumped to Pond E. It is not anticipated that this will happen frequently during the life of the operation. , Permit Renewal No. 3 Tab 1 Page 4 1/15/00