2014-02-13_REVISION - M1977493 - Laserfiche WebLink

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Page 3 of 4 Closure of Historic Decant System Page 3 -2 of the OMM states that the historic decant system will be closed with grout in the future. DRMS supports this idea, but will require that the plan for abandonment of these features be submitted to DRMS as a TR for approval prior to construction, and that the results of the closure be provided to DRMS following abandonment. Monitoring of Decant Pond Operation Section 5.2.1 of the OMM, Decant Pond Operation, states that the success of the tunnel system to act as an emergency spillway to safely route extreme flood events relies on maintaining the level of the decant pond according to the operating limits outlined in this section; the 800 -foot beach width, 2,000 acre -feet of flood storage, or 6 -feet below the dam crest. However, there is no reference or discussion of how these parameters are physically measured to ensure the "prescribed upper operating level" is maintained at or below this level. Please clarify how each of these parameters will be physically measured/monitored, recorded and reported. Monitoring and Inspection of the TSF Section 5.3.1.1 of the OMM states that there is no instrumentation associated with the subdrain system, however monitoring of flow from the subdrains could be an important indicator of the safety and performance of the TSF. DRMS recommends that Climax implement some means to monitor the flow from the subdrain outfalls, and that this data should be included in the monitoring and reporting for the TSF. Section 6.1 of the OMM states that all piezometers and the inclinometer are, or will be, automated. Is there any remaining ability to manually measure these monitoring points? DRMS would like to see the ability to manually measure these monitoring points to confirm the automated data periodically if at all possible. Due to the importance and scope of the monitoring, recording and reporting requirements for the TSFs detailed in sections 6 and 7 of the OMM, it may be useful to somehow summarize the monitoring and reporting activities proposed in the OMM, perhaps in a table or some other format. The monitoring summary should include, but not necessarily be limited to: Listing of instrumentation to be monitored and locations — piezometers, inclinometer, survey monuments, etc. Parameters to be monitored — beach width, pool elevation, subdrain outflow, etc. Frequency of monitoring — daily, monthly, event based, annually, etc. Type and frequency of reporting Examination and interpretation of monitoring data Climax will need to commit to maintaining all monitoring, reporting, and evaluation reports and data on site for the "life of operation" for review by DRMS upon request. Climax will also be required to submit to DRMS within 30 working days of the inspection, the annual TSF inspection/evaluation report, certified by the engineer of record for the TSF, stating that the TSF is being constructed, maintained and monitored as designed and in accordance with the approved plan and applicable regulations. Plan(s) for extend period(s) of inactivity for TSF Does Climax envision any changes to the submitted plans for TSF monitoring and maintenance if the operation were to enter into period(s) of extended inactivity (greater than 12 months)? Upset Condition or Emergency Notification Procedures DRMS would like to see some discussion of, or reference to, possible TSF trigger conditions or scenarios that would require "emergency" actions and notifications by Climax in accordance with Rule 8.1 and 8.2. What is the notification process and timeline for an "upset ", "slowly developing" or emergency situation? It was noted that