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SNOWMASS COAL COMPANY NO.1 MINE SEEPAGE CONTROL, TREATMENT AND RECLAMATION PLAN SEBPAGE CONTROL During a site inspection on April 28, 1988 seeps were noted in the vicinity of the No. 1 mine portals. The seeps, which were obviously high in iron content, were surfacing along the rip rap bank of North Thompson Creek and running into the creek. On April 30th excavation work was started to investigate the source of and to contain the seeps. By May 6, 1988 all of the seepage coming from the No. 1 Mine portal area wsa contained in a french drain system and wsa being piped to on site ponds. Access to the portal area was first established by installing a 42-inch culvert in North Thompson Creek. A backhoe wea used to excavate the face of the portals and a front end loader was used to haul the excavated material from the portal area to an ad- jacent stockpile area. The eastern portal, rock elope, was un- covered first. The seal was exposed for inspection and water was noted leaking around its upper right corner at the rate of about eight gallons per minute. Controlling the water from this portal had no effect on the seeps which were surfacing along the rip rap bank upstream of this area. Excavation continued upstream, to the west, towards the area where the seeps were first noted. The next feature excavated was an old air shaft which was constructed of a large diameter, 8' to 9', corrugated metal pipe, CMP, bedded in pea gravel. Mine water had seeped up through the old air shaft and partially filled the CMP. The extensive pea gravel bedding allowed the mine water a free flow path to the creek. The CMP was removed along with most of its pea gravel bedding. It was fairly obvious that the source of the seeps had been the old air shaft and CMP. Further investigation around the area failed to find additional seeps which might flow into North Thompson Creek. A perforated pipe and gravel packed french drain system was installed across the front of the portal area to collect the drainage from the area. The french drain system, although free flowing, allows water to pond in the old air shaft at the elevation of the invert of the pipe leading to the ponds. Because of this there was a chance some seepage would find its way from the french drain directly to the creek. In order to assure that all of the seepage was collected in the french drain system, a bentonite filled trench was constructed between the french drain and the creek. In order to provide for long term access to the portal area a bridge was installed across North Thompson Creek and the culvert installed previously was removed. The bridge is an old railroad