2019-01-17_REVISION - C1982056 - Laserfiche WebLink

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to resolve this issue and provide an acceptable updated augmentation plan that includes the proposed passive treatment system proposed in this revision. Response: The existing Augmentation Plan was originally approved by the Water Court in 1981 (W-1502-78) and has subsequently been confirmed and validated by subsequent Water Court and Referee decisions (90CW99, 97CW76, 05CW12). The Augmentation Plan identifies the water rights and mechanisms that TC can utilize to address any downstream call by a senior water right holder. Until last year, the Yampa River had not been put under administration due to a downstream call. Even under last year's administration scenario, the Division of Water Resources (DWR) had not requested that TC implement our Augmentation Plan, so the Augmentation Plan has never been implemented or tested. While the DWR has questions about how the Augmentation Plan would function, and we are working with them to clarify the details, we have an approved Augmentation Plan with adequate supporting water rights to meet our obligations. The Passive Treatment System is simply a treatment mechanism which is designed and will be operated as a flow- through system with no or minimal storage capacity. The very limited evaporative loss from the System would be considered a consumptive use, and the existing Augmentation Plan addresses replacement of all consumptive uses, of which evaporative losses are a very small part. It will not affect any existing water right or the ability to address our obligations under the existing approved Augmentation Plan (available water rights could provide many times the cumulative amount of all consumptive uses), so there is no need to modify the Augmentation Plan to include this System. 5. Exhibit 49EE Appendices D and E do not appear to have been updated for the new location. The previous location was determined to a wetland, so the data does not likely have a strong correlation to the new location. Please provide data for the new location or explain why this would not be unnecessary. Response: Appendix D — Test Pitting Program, and Appendix E — Earthwork Specifications, are generally not location specific, and are designed to provide detailed information for System construction. Appendix F — Geotechnical Laboratory Test Results, is site specific and relates to the previous design location. Given the change in project location, TC plans to complete confirmation testing of foundation materials, guided by the plans in Appendix D, to verify that design parameters are still applicable, and to make any adjustments necessary based on site-specific material properties and characteristics. Given that the original and new project locations are similar upland areas, with the same surficial soil unit (D10 — Binco silty clay loam) and similar surficial geologic characteristics, there is good reason to believe that foundation material characteristics will be essentially the same or very similar. Appendix F will be replaced with the updated testing information from this confirmation sampling program. Unless there are significant variations in foundation material properties and characteristics, the specifications provided in Appendix E should remain valid. 6. The designs and exhibits provided by the mine's consultant appear to be a recommended scope of work not necessarily the operators proposed construction. The 2016 submission included Exhibit 49EE-Fl and F2 map of the 6M7V Passive Water Treatment System signed by a TC engineer. Please provide this level of labelled detail and clary and speck exactly what TC is proposing to construct. Response: The drawing set provided by CH2M includes detailed scaled plan view and cross-section drawings with stationing, grade lines, and structural details. The drawings combined with the Earthwork Specifications (Appendix E) and project material take -offs and cost estimate (not provided in the permitting package since costing information is considered confidential) provide sufficient detail for earthwork estimating and construction. TC has provided this information to prospective contractors, and has obtained construction bids, based on the existing information. Note that the referenced drawing (Exhibit 49EE-F1, F2, and 173) was a single drawing sheet providing less information than the current design package.