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Kathy Welt and Clrristine Johnston March 7, 1997 (DRAFT) Page 8 encountered, the direct discharges will likely become the dominant mine outflows, particulazly after the new, high capacity treatment facility is online in mid to late 1997. As a result of pumping water into the NW Panel sealed sump, and eventually the NE Panel sealed sump, groundwater discharges out the north ends of the panels is likely occurring and will continue. The amount of groundwater that will reach the North Fork as return flow is less than 25 gpm, as explained below under "Groundwater Quantity." In an attempt to better manage the mine water, MCC has initiated an inflow separation program. An example of this is the implementation of a french drain collection system for the B East Mains fault inflows. The quality of water coming out of the fault is adequate to meet MCC's NPDES discharge standards; however, prior to installing the french drain, as the fault water traveled to the NE Tailgate sump, it accumulated suspended solids in quantities that exceeded the TSS effluent limit. Therefore, MCC has segregated this water and may directly discharge it to the North Fork or reuse it in the mine. Similarly, the inflows from the 1 SE Headgate fault meet discharge standards and MCC may also directly discharge this water or reuse it in [he mine. MCC has appropriated the fault inflows and waters in the NW Panel sealed sump and will file in Colorado Water Court to decree these 1997 water rights (see "Water Rights," below). VI. SURFACE WATER QUANTITY PHCs The evaluation of surface water quantity/quality impacts is facilitated by considering four sepaza[e time intervals as follows: 1. Prior to March 1996, when the B East Mains fault inflows were experienced. 2. From March 1996 through October 1996, when pipelines from the B East Mains to the NW Panel sealed sump became operational. 3. From November 1996 until mid to late 1997, when a new, large capacity treatment system will be operational. 4. From mid to late 1997 onward (with the upgraded water treatment system in place). Table 1 contrasts North Fork diversions (via the Mount Gunnison pipeline) acrd retutn flows for these time periods, under both "typical" conditions (before the B East Mains fault was encountered) and after the B East Mains fault was encountered. Observations from Table 1 include: I. When contrasting calendar year 1996 with previous typical years, MCC's North Fork diversions were similaz. Minor increases can be attributed to increased production. 2. Total return flows to the North Fork in 1996 were considerably larger than in typical years because fault inflows were pumped to the surface and released to the North Fork. 3. When contrasting the specific timespan of March through October 1996 with the same timespan for typical years, return flows to the North Fork were far higher in 1996 even though North Fork diversions were roughly comparable. During this time, B East Mains fault inflows were being directed into the North Fork via the ponds, and the NW Panel sealed sump was not being utilized.