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reports and page numbers in Volume X that pertain to the pre-subsidence survey mentioned on <br />revised page 2.05-114. The information contained in the pre-subsidence survey must be detailed <br />enough to determine the degree of material damage or diminution of value of the dam structures <br />should it occur. <br />The Division has no further concerns. In their December 28, 2006 response, BRL stated that the <br />two geotechnical reports in Volume X were the pre-subsidence survey. However, the Division <br />believed that the information that was presented in Volume X did not fully describe the current <br />condition of the dam and asked BRL to consider submitting a complete pre-subsidence survey for <br />the Bruce Park Dam. BRL submitted a pre-subsidence survey in the January 30, 2008 submittal. <br />25. On revised page 2.05-117, under Rule 2.05.6(6)(1)(v)(B), mention is made ofthe seismic <br />monitoring program. However, the purpose of this monitoring program is to measure the strength <br />of the seismic wave at various points, not to measure whether there has been an effect of the <br />seismic wave, or of subsidence for that matter, on the two dam structures. In support of the Rule <br />2.05.6(6)( )9(v) requirement for a description of the measures to be taken to determine material <br />damage or diminution of value, please propose a monitoring program that will demonstrate <br />baseline conditions and measure the structural effects ofsubsidence and seismicity on the Bruce <br />Park main dam and saddle dam. <br />The Division has no further concerns. BRL supplied Exhibit 18 in the May 12, 2008 submittal <br />which details the seismic monitoring plan. The monitoring frequency will be continuous and any <br />seismic event with a peak horizontal acceleration of greater than 0.05 g measured at the Terror <br />Creek monitoring site will result in an inspection by Bowie of the Bruce Park Dam and the <br />adjacent landslide. Quarterly reports to the Division will document and discuss all data recorded <br />over the reporting period. <br />26. The Division understands that the seismic data currently being gathered at the Bowie No. 2 Mine <br />will be provided to the Division as part of the PR-10 adequacy review. The Division would like to <br />receive the preliminary seismic data as soon as possible to see what magnitudes are being <br />generated by the mine. The adequacy review will progress more smoothly and more efficiently if <br />BRL, the Division and other concerned agencies and parties are working with the same <br />information. <br />The Division has no further concerns. In the submittal dated December 28, 2006, BRL provided a <br />Microseismic Monitoring Report for the 3`d quarter of 2006. The Microseismic Monitoring Report <br />for the 4th quarter of 2006 was submitted to the Division on March 12, 2007. The Division had <br />reviewed both reports and, in the Division's adequacy review letter dated June 6, 2007, had <br />requested revisions to the report format. BRL responded with new format reports for the third and <br />fourth quarters of 2007. The Division reviewed both reports and found the new format acceptable. <br />27. In reviewing the information on Map 14B, Map 27 and the "Station Locations "figure on the <br />second page of the Exhibit 18 report, it appears that the closest that longwall mining will get to a <br />seismometer is 4500 feet by the end of 2006. Assuming that PR-10 is approved by the end of <br />2006, please explain how BRL intends to show that seismic events recorded at a seismometer that <br />is no closer than 4500 feet away from the generating longwall mining event can be used to predict <br />the seismic effect on the Bruce Park Dam from events that are generated by longwall mining that <br />9