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<br />The Cal orado Human Heal >fi Standard for cadmium Ss 10 ug/1. This standard 1s exceeded <br />~ loceily in same of the watts not aftaeted by mining. Otavi to sot ubil[ty appears to limit <br />eadmi um concentrations Tram 70 to 15 ug/i but is depart ant on other factors, sari, as <br />sulfate concentration, alkalinity, end pH. For wells and springs in spoil material at <br />Nucla, cadmium was not present above the detxti on limit of 5 ug/l, and fa probably <br />controlled Oy otavita solubility. At Nuela Eeat, cadmium concentrations should not <br />appreciably fncrease as a result of mi n{rg. <br />Nany of the samples appear to ba undersaturatsd with respect to fluorite. Those with 81'a <br />greaCer than sero are probably at equiltbrf7m with fluorite, and have fluoride <br />conaentrati one of about 7.4 mg/1, The Colorado Human Health Standard is 4.0 ng/1, and the <br />Agrtcultural Standard is 2.0 mg/1. Mining is not expected to cause an increase in <br />fluoride concentrations. <br />Barium eoneeMrati ons, where deCectabl e, may be Ti mi tad by bars ta. aolubtl7ty at about 10 <br />to 20 uq/1. If barite controls barium eoneentratl on s, there to a pH control. The <br />concentration of Darium, as predicted by Na calCUlati ons an CY7-Nl5 water, should ineroase <br />with decreasing pH, aspseia7 ly M th a pH lass then 6, St111, because of htgh sulfate <br />• eoneentratl ons, barium concentrations will remain low (pHREEQE predletad 12 mg/1 st pH <br />5.36). <br />At GW-N9, ane analysts reported a concentration of 500 ug/1. However, the earlier <br />ground-»ater quality anal yeas d10 not indite Ce that an analysis was parfonned Tor barium <br />in this sample, and recent analyses show that barium eontentratf ons era 20 ug/1. The <br />Colorado (feat th Standard for barf inn to 500 ug/lf there is no Agricultural Standard. <br />Again, no appreti eDle tnereases fn Dar/um eoneentrati ons are expected because of mining. <br />In suamary, the major ton chemistry appears to De Controlled by the solubtlStf ea of <br />calcite and gypsum, and, to a lesser extent, dot qoT te, As a rcsul t, the waters have a <br />iii gh TDS content. In acid-product ng horizons, carbonate ml nerals appear to be absent. <br />Concentrations of trace metals may also be aol ability controlled or limited. While it is <br />rclati vely~ simple to examine solubility Controls, it 1s more difficult to predict <br />concentrations, because of many intnracti ons between constituents, end the different paths <br />through which the ehemi atry can evolve. Still, the feet that controls are demonstrated by <br />the data strongly suggests that no aajor Changes in ehemi stry as a result of mf ni ny should <br />be expected. Nany o/ the trace metals appear to be controlled by the aoluDiliti va of <br />t7-49 Revtsed 04/17/88 <br />\J <br />REVISED MARCH 2006 Attachment 2.05.6(3)-2-58 <br />