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referred to on page 133 as the "effective" porosity, and is used on that page in a calculation of the <br />spoil saturation rate. <br />The Division accepts the Collom Lite spoil saturation calculation on page 133, with the changes <br />requested elsewhere in this letter to the surface water infiltration rate and subtracting pitwall <br />seepage from the spoil saturation calculation. Based on the adequacy of the calculation of spoil <br />saturation on page 133 (with the requested changes), and the inadequacy of the calculation of <br />spoil saturation on page 137 (due to its use of total porosity), the Division requests that you delete <br />the second, third, fourth, and fifth paragraphs from page 137. These paragraphs contradict the <br />calculation on page 133, making the prediction of spoil saturation unclear. Also, some of the <br />information in these paragraphs on page 137 repeats information that is provided on page 133, <br />resulting in the spoil saturation analysis not being concise. Rule 2.03.2(1) requires information <br />in the permit application to be clear and concise. <br />7. No further comments are necessary regarding the source of water (adjacent unmined rock, or land <br />surface) that will saturate the Collom Lite spoil below the premining piezometric elevation. <br />8. Please change the 7,290-foot elevation noted in the next to the last paragraph on page 133 as the <br />low point on the Collom Lite highwall to 7,275 as the low point is noted elsewhere on that page. <br />9. Page 137, in referring to mining impacts, says: "no significant change to local or regional water <br />quality is expected". To support your conclusion of no significant change, please add to the <br />permit application a mass-balance calculation of the TDS concentration that will result from the <br />mixing of pit spoil spring discharges with alluvial ground water in Little Collom Gulch and <br />Collom Gulch. <br />10. Please provide a calculation of potential spoil spring discharge from the downdip end of the spoil <br />in Little Collom X Pit that will result from snowmelt and rain infiltrating from the surface into the <br />spoil. <br />2.05.6(3)(b) Hydrologic Controls <br />1. Response is adequate. <br />2. As previously requested, please add to the analysis (currently on page 133) a calculation of <br />annual pitwall seepage at the downdip end of Collom Lite Pit. In the analysis, please predict the <br />spoil spring discharge rate by subtracting pitwall seepage from pit inflow. This method of <br />analysis is shown at the end of the attached Exhibit A. <br />4.05.13 Surface Water and Ground Water Monitoring <br />4. If, as your response says, well MLC-04-01 C is inappropriate for an alluvial ground water point of <br />compliance because of possible upstream non-mining impacts, then please either add an <br />additional well to the monitoring plan for distinguishing non-mining impacts, or propose another <br />well as an alluvial ground water point of compliance. Our letter of April 22, 2011 explained the <br />potential for activities proposed by PR-03 to negatively impact the quality of alluvial ground <br />water in Collom Gulch. Rule 4.05.13(1)(b) requires one or more points of compliance for any <br />coal operation that, in the judgment of the Division, has the potential to negatively impact the <br />quality of groundwater for which quality standards have been established by the Colorado Water <br />Quality Control Commission (CWQCC). Rule 4.05.13(1)(b)(i(A) requires a point of compliance <br />for potentially impacted ground water that is subject to the CWQCC's standards. Collom Gulch <br />