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Sundance Coal/Animas Mine File -2- August 7, 1986 1. Monthly records of water depth and water quality (field parameters) for the Iuppa and refuse facility wells; 2. Periodic records of water depth and quality (field parameters) for the Sundance Coal Company well being monitored on a volunteer basis by the operator; and, 3. Full suite analyses of water samples from the above wells. Missing from the reports are the records for June 1986. The Iuppa well yields water characteristic of the Cretaceous Yermejo Formation in which the local mining was conducted at points slightly up dip and to the immediate east. The quality of this water remained constant for the year. The water is essentially unchanged from that sampled and analyzed for inclusion in the permit application in 1982 demonstrating no significant long term alteration in water quality has occurred due to the mining. On a short term basis, however, recent field parameters for the well water show a lessening in TDS relative to a period in late 1984 and early 1985 when some possible contamination of the well by a nearby septic tank was suspected. The Sundance Coal Company well, being voluntarily monitored by the operator produces water characteristic of the Cretaceous Trinidad Sandstone. Quality of this water has remained constant for the year. The recent analyses also bear close resemblance to that of water from the well included in the 1982 permit application. , Water from the refuse facility well showed little variation in quality during the past year. Earlier analyses of water from this well, however, do not show the same consistency. These earlier variations may be due, at least in part, to significant delay between time of sampling and analysis. Such delays are no longer the case. While conclusions about long term changes in the quality of this water are suspect, TDS values do seem to be declining. The selenium content of water from this well tends to be higher than for the other monitoring sites, occasionally reaching or exceeding recommended standards for human or livestock consumption. Water from this well, however, is not put to either use. The water from the refuse facility well differs in character from the both the Iuppa and Sundance Coal Company wells. In terms of TDS and dominant bicarbonate, it resembles water from t Tri a Sandstone penetrated by the Sundance well but contains relatively "c-w`m•ion. The drillers report for the well indicates some 16 feet or so of unconsolidated material was encountered before drilling a sandstone, presumably the Trinidad, in which the well bottomed at a depth of 60 feet. Possibly some modification of water characteristic of the Trinidad by cation exchange is occurring in the area of this well from contact with unweathered refuse material. This change, however, which serves only to soften the water involved, is not necessarily undesirable.