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TR-12 described a water treatment plant which was never delivered, <br /> due to problems with the supplier. In reporting to the Division <br /> on the non-delivery of the water treatment plant, Mid-Continent <br /> indicated that a review would be made of both our assumptions and <br /> the design plans before we proceeded further on the plant. <br /> Having done so, Mid-Continent has determined to make changes in the <br /> system we propose to install . The system we wish to install, like <br /> the system proposed previously, involves routing the mine water <br /> down to the coal preparation plant for removal of solids by <br /> mechanical and chemical means. We believe the system, as proposed <br /> in this request for technical revision, is in fact a better system <br /> than we'd previously proposed in having fewer possibilities for <br /> mechanical malfunction. In addition to the plant itself, the <br /> system includes a screen underground to remove coarse solids, and <br /> use of the 020 "Picnic Pond" for settling the flocculated fine <br /> solids. <br /> The design parameters for the system are based on weekly samples <br /> of water leaving the mine, measured for flow and TSS, over a 17 <br /> month period, from March, 1989 to August, 1990. As indicated on <br /> Table 1, flow and TSS are quite variable. Flows range from 57 to <br /> 755 gallons per minute (gpm) , averaging 325 gpm. Solids range from <br /> 0 to 11,000 parts per million (ppm) , averaging 1775 ppm. The <br /> system is designed to handle a maximum flow of 1 ,000 gpm, and <br /> maximum solids of 15, 000 ppm. Table 2 indicates flow and content <br /> through the system, as illustrated in the flow diagram, Attachment <br /> 1 . A volume survey of the 020 pond, with estimated retention time <br /> (4 .92 hours) at 1,000 gpm is included as Attachment 2 . <br /> General Overview <br /> - Present system. Mine drainage flows out of the tunnel <br /> adit through the existing "white pipe" . Presently, all <br /> flows are conveyed to the three-pond series above outf all <br /> 016. <br /> Flocculant is mixed and added to the pond inflow. <br /> The "white pipe" extends under the haul road, and <br /> terminates at a ditch which extends beside the permanent <br /> tunnel fill pile. Mine water flows down the ditch to the <br /> 016 pond. <br /> Mid-Continent proposes to continue using the 016 pond <br /> system. A valve box, situated in the tunnel portal yard, <br /> allows us to route flows to the ponds, the plant, or <br /> both. It is anticipated that the ponds will be used <br /> during periods of high flow, during plant maintenance, <br /> periods when the plant is idle, or in the event of <br /> malfunction in the plant system. <br /> 2 <br />