2013-07-16_REVISION - C1982056 (2)

Home Browse Search

16 Based on the PAP, TC is committed to conducting Pond surveys at Ponds B, C, D, E, F, G, and T every 3 years, with 1999 being year number one. Based on the Division's review, pond surveys were required to be conducted in 2004, 2007, 2010, and 2013. These surveys are in addition to quarterly pond inspections. Please provide the Division with the results of these inspections. If TC feels that the required inspections are no longer required, please provide the Division with proper justification to omit such survey commitments. Response: In 2004, TC reviewed the intent and requirement to conduct pond surveys, and discussed related practical and safety concerns with the CDMG inspector assigned to the Mine at the time. Given the inlet conditions and configuration of TC's sedimentation ponds, any sediment build -up which might occur, which could affect pond capacity, would normally occur within the pond inlet area, creating a sediment "delta" in this area. Typical climatic factors and runoff conditions result in essentially all of our active pond structures filling during spring runoff, with water levels declining significantly during late summer and into the fall. As water levels decline later in the year, sediment "deltas" in the pond inlet areas are exposed and their extent can be readily assessed to evaluate any pond maintenance requirements (note that all ponds are over - designed relative to required capacity, so there is a significant safety margin). The referenced pond surveys (Pags 2.05 -77 through 78), would require someone to go out on the ponds in a boat to take "sounding" measurements at various locations. Given the obvious safety concerns associated with this approach, and that late - season observations represented a reasonable alternative approach, it was agreed that this approach would be acceptable, and became the standard going forward. TC has used this approach for a number of years, and has scheduled and conducted pond maintenance based on the late - season visual observations (typically conducted annually in conjunction with the quarterly pond inspections) of sediment accumulations in the pond inlet areas. In order to make the referenced permit text consistent with this practice, the text has been revised. Copies of the revised pages accompany these responses for replacement in the PAP. 17. Pages 2.05 -128 and 131 lists the current NPDES permits associated with the Foidel Creek Mine Please revise the text to include all NPDES permits currently active at the site. Response: The referenced text has been reviewed and updated, as appropriate. Copies of the revised pages accompany these responses for replacement in the PAP. 18. Page 2.05 -129 states that all stream buffer zones will be identified on Map 29. No stream bt ffer zones were identified on Map 29. Please revise the text to identify the correct location of the stream buffer zones or revise Map 29 to reflect the currently approved text. Response: Map 29 previously showed stream buffer zone areas, as well as those areas where a variance from the buffer zones requirements had been approved. As a result of successive changes to this Map, the stream buffer zone information had been lost. This information has been added back in to the Map, and copies of the revised Map accompany these responses for replacement in the PAP. 19. Page 2.05 -134 identifies the year 1999 as a date that no significant inflows ./coin Trout Creek Sandstone has occurred and no evidence of communication between mined through faults and the Trout Creek Sandstone has occurred. Please confirm if any up to date mine inflow data shows that this statement is current and remains correct. Response: Ongoing groundwater monitoring and annual mine inflow studies, as documented in the Annual Hydrology Reports, indicate no significant changes in mine inflows from the Trout Creek