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The Events Pond is intended to be kept dry and only used to temporarily store any upset overflow <br />from the plant's containment sump system. The Events Pond is designed to have more than <br />adequate capacity to store run -on from the pond's catchment area for the 100 -year, 24 -hour storm <br />plus 110% of the volume of the largest single tank (one of the thickeners). <br />- Please provide some statement as to how Climax will satisfy section 7.3.2(2) of the rule. (Section <br />2.9) <br />Response: Similar to other recently completed projects, Climax will provide a certified verification <br />by a registered professional engineer (in accordance with Rule 7.3.2(2)) that the facility was <br />constructed in accordance with the approved design plans. As described in Section 2.9, CH2MHi11, <br />as the design engineer and Construction Manager, will have overall responsibility for ensuring the <br />facilities are constructed in accordance with the plans and specifications, and will maintain a set of <br />as -built construction drawings for the project. <br />- What kind of leak detection/monitoring /containment is being used on the supply and return lines to <br />and from the plant to the Mayflower TSF (Section 2.6.2). <br />Response: The supply pipeline from the Mayflower Barge Pump Station to the Feed Tank at the <br />PDWTP will consist of an existing section of 42 -inch diameter steel pipeline, previously known as <br />the Mill Water Return Line, and a new section of 36 -inch diameter welded steel pipeline extending <br />to the Feed Tank. At the completion of construction the entire line will be inspected and pressure <br />tested prior to putting the line into service. The pipeline is not expected to leak. However, Climax <br />also will implement several additional mechanisms to prevent, detect, and mitigate leakage along the <br />pipeline should it ever occur. <br />The vast majority of the supply pipeline, including most of the existing 42 -inch pipeline, is located <br />above 5 Dam and the 5 Dam Seepwater Pump Station (Figure 2 of TR -19). If a leak in the pipeline <br />were to occur above this point, water that migrates to the surface would naturally flow into and be <br />contained by the Mayflower TSF and Climax's process water system, thereby not posing an <br />increased environmental threat to the surrounding areas. The small portion of pipeline between the 5 <br />Dam Seepwater Pump Station and the PDWTP Pipeline Terminal occurs along the pipeline /West <br />Interceptor access road where a leak would be readily noticeable and contained by the roadway back <br />towards the PDWTP. <br />The supply pipeline is being designed with flow meters at both the pump barge and at the feed tank. <br />Flow totalizer readings from each flow meter will be monitored and a significant variation in the <br />readings, which may indicate leakage or a loss from the system, will trigger further investigation of <br />the pipeline and/or the flow monitoring system. <br />As a best management practice Climax also conducts daily visual inspections of all active pipelines <br />during each shift, and will include inspections of the entire supply pipeline route during each shift <br />when that pipeline becomes operational. These frequent visual inspections of the ground surface <br />above and adjacent to the pipeline provide for immediate detection and response should a leak occur. <br />Together with the other protective measures described above, the visual inspections of the supply <br />line are a key component to a comprehensive monitoring/mitigation system to prevent potential <br />environmental impacts. <br />2 <br />