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Colowyo, C3981 -019, PR3 adequacy No. 3 10 July 22, 2011 <br />saturated (15% effective porosity between particles, plus 5% partially saturated particles.) A <br />value of 20 0/a is consistent with the values of 20% that is referred to on page 133 as the <br />"effective" porosity, and is used on that page in a calculation of the spoil saturation rate. <br />The Division accepts the Collum Lite spoil saturation calculation on page 133, with the <br />changes requested elsewhere in this letter to the surface water infiltration rate and subtracting <br />pitwall seepage from the spoil saturation calculation. Based on the adequaev of the calculation <br />of spoil saturation on page 133 (with the requested changes), and the inadequacv of the <br />calculation of spoil saturation on page 137 (due to its use of total porosity), the Division <br />requests that you delete the second, third, fourth, and fifth paragraphs from page 137. These <br />paragraphs contradict the calculation on page 133, making the prediction of spoil saturation <br />unclear. Also, some of the information in the referenced paragraphs on page 137 repeats <br />information that is provided on page 133, resulting in the spoil saturation analysis not being <br />concise. Rule 2.03?(1 )requires information in the permit to be clear and concise. <br />The response is adequate. <br />8. Please change the 7,290-foot elevation noted in the next to last pat agnaph on pine 13 ', as the <br />low point on the Collum Lite highwall should he 7,275 as the low point is noted ciscwhcrc on <br />page 1 33. <br />The response is adequate. <br />9. The words "no significant change to water quality" in the eighth paragraph on page 134 appear <br />to contradict the statement in the second paragraph on page 132 that spoil leachate will likely <br />have the same characteristics as water in the Streeter fill well or Streeter pond, or Seneca 11 <br />Mine spoil springs described by Williams and Clark, 1994. The Streeter well and Seneca 11 <br />Mine spoil springs have TDS concentrations above 3,000 mg/1(page 119 of the Rule 2 section <br />of Colowyo's PR -02 volume); undisturbed Williams Fork ground water in the Collom area <br />have TDS concentrations generally below 2,000 mg/I (Table 2.04.7 -41 of Colowyo's PR -03 <br />submittal). Please change the wording in the eighth paragraph on page 134 so that it is <br />consistent with the statement in the second paragraph on page 132. Also, please change on <br />page 134 the wording "base environment" to "basic environment ". <br />Page 1 37, in referring to mining impacts. says: "no significant change to local or regional <br />water quality is expected ". I o support your conclusion of no significant change, please add to <br />the permit application a mass - balance calculation of the TDS concentration that will result from <br />the mixing of pit spoil spring discharges with alluvial ground water in Little Collom Gulch and <br />Collom Gulch. <br />Please add to section 2.05.6(3)9a) a calculation of the TDS concentration that would result <br />from mixing of the predicted 0.52 cfs spoil spring discharge with Collom Gulch valley fill <br />water in Section 32, T5N, R93 W. (The 0.52 cfs spoil spring discharge is discussed in comment <br />2 of 2.05.6(3)(b), below.) Please use in the calculation TDS concentrations of 2,000 mg/l for <br />