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42,05 APPLICATION FOR PERMIT FOR SURFACE OR UNDERGROUND MINING ACTIVITIES -- <br />MINIMUM REQUIREMENTS FOR OPERATION AND RECLAMATION PLANS. <br />2.05.6 Mitigation of Surface Coal Mining Operation Impacts. (Cont'd.) <br />(3) (b) Civ) (Cont'd.) <br /> <br /> <br />Coal Basin, 6 out of 26 parameters monitored <br />increased (conductivity, Fl, Fe, Mn, K, Na), <br />pH, and suspender solids decreased, and the <br />remainder were stable between pre- and post- <br />mining values (page 376). Any significant <br />change in groundwater quality detected by the <br />present and proposed groundwater monitoring <br />(described in Section 2.04.7) should be negat- <br />ed due to dilution. <br />Surface Water Effects - Permit and Adjacent <br />Area <br />Streams within and adjacent to the permit <br />area, described in Section 2,04.7 are not ex- <br />pected to be adversely impacted due to subsi- <br />dence, based upon monitoring experience (refer <br />to Volume 4). The major ephemeral drainages <br />of Steven's Gulch and East Roatcap Creek will <br />be protected by a Subsidence Control Plan (see <br />Section 2.05.6) during future permit terms be- <br />neath 800 ft. of overburden. In areas of <br />greater than 800 ft. overburden, the predict- <br />ed character and nature of subsidence should <br />not impact these resources, Monitoring data <br />obtained to date (CWI Hydrology-Subsidence Re- <br />ports, 1982 and 1983) have detected no in- <br />crease in sediment load or decrease in stream <br />flow. As described in the Subsidence Study <br />for the Orchard Valley Atine (Geo-Hydro Con- <br />sulting, Inc., Appendix 3), abrupt changes in <br />stream gradient, reversal of stream gradients, <br />or impounding of streams is not predicted to <br />occur. Tension cracks could develop to the <br />surface in the tributary drainages. The sig- <br />nificance of flow disruption due to subsidence <br />cracks is diminished due to the flow charac- <br />teristics of the ephemeral streams. These <br />streams flow in response to precipitation <br />events, usually substantial rainstorm or sud- <br />den snowpack melting, During ephemeral flow, <br />these streams are typically charged with con- <br />siderable amounts of sediments, (refer to Vol- <br />ume 4 - Stream Quality Data). Crane (1927) <br />_9dde~1 l2 /26 /84 <br />Added 02/26/85 <br />Revised 10/01/87 <br />133 <br />