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had reduced volumes and the zone above the longwall had higher volumes. <br />In the sealed areas above the longwall, the volumes were calculated <br />for both the A-seam and B-seam workings assuming 60% extraction. <br />Using the flows and the volumes, the timetable was calculated for <br />filling the mine. As a check, the volume between 7320' and 7425' <br />was calculated to fill in 63 days. The observed time was 60 days. <br />The water level is expected to reach the main portal seals elevation <br />of 7572' in November, 1487, at which time the total inflow is expected <br />to be down to 43.8 gpm. As the flow rate decreases, the filling time <br />table slows. The calculations show a uniform inflow-outflow at 7652' <br />which would result in a head of 80' on the portal seals. <br />*Calculation based on the assumption that inflows are typical of seepage <br />through a sand filter. <br />Q = Ak(h/L) Darcy's Law of Seepage <br />Q = Discharge (gpm) <br />A = Filter Areas {remains constant as h varies) <br />k = Coefficient of permeability (Remains constant as h varies) <br />h = Energy loss across filter (head in feet from intersection with <br />creek) <br />L = Length of flow through filter (remains constant as h varies) <br />Conclusion Q2 = @1(h2/hl) <br />Assumed intersections with Creek: <br />LOCATION ELEVATION <br />• North Thompson Creek 7550 <br />Shear Zone 7600 <br />Middle Thompson Creek 7680 <br />MATER AUGMENTATION PLAN FOR NORTH TNOMPSON CREEK <br />Due to permanent cessation at the North Thompson Creek Mines flow <br />monitoring en North Thompson Creek and Middle Thompson Creek was dis- <br />continued in 1986. This monitoring was designed to assess augmentation <br />needs sn the creeks. Monitoring through 1985 did not establish deple- <br />tion to the creeks from mining activity; therefore, an augmentation <br />plan based upon observed stream depletion can not be developed. <br />Pumping from the ltl Mine was discontinued in June 1986. To continue <br />to be able to augment the stream flow during mine filling, the #3 <br />Mine seals were designed to allow discharge of mine water. A pipeline <br />was installed to discharge water from inflow lib (near Sample 2 Figure <br />3.6.1-7). This pipeline was completed September 4, 1986. Inflows <br />studies in May 1985 and June 1986 showed 75 gpm from inflow N8. When <br />the free discharge from the pipe started in September 1986, a discharge <br />of 30 gpm was measured and by the end of 1986 the flow was down to <br />18 gpm. Water will continue to be discharged from the #~3 Mine on <br />a continuous basis. The flow is expected to slightly increase when <br />the mine water level reaches the portals. <br />• <br />4-115b (New 3/25187) <br />