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RESPONSE: Drill holes SR14 and SR61 have been confirmed as being sealed and reclaimed. Concerning MW -NW, the DRMS <br />approved MW -NW for the groundwater monitoring program and DBMS needs to support the approval. <br />On page 2.05.6 -41 the mine inflow rate is estimated as 330 Acre feet per year. Using the <br />previously quoted figure of 5,700 Acre feet as the maximum volume of the mine cavity, the mine <br />would be expected to refill completely in 17 years. <br />It is noted that the analysis of BBA suggests that the rate of mine inflow was overestimated. Without a <br />data point in the mine workings none of the assumptions that underlie any of the estimates or models <br />can be verified, and the rate at which the mine is refilling will remain a matter of conjecture. <br />RESPONSE: The DRMS' above reference to 330 acre feet per year of mine inflow and that the mine would be expected to <br />completely refill in 17years is out of context. The calculations shown on Page 2.05.6 -41 of the PAP (permit) were generated <br />from data compiled in the early years of the mining operations at Southfield. Mining records from the Annual Hydrology <br />Reports (AHR's) document that approximately 85% of the mine inflow water was pumped and metered for accuracy <br />throughout the mining operations. Review of the records from 1985 through 2000, which was the active mining period of EFCI <br />at Southfield, document that the highest recorded mine inflow during any one year was 135.3 acre feet, which occurred in <br />1985. During subsequent years, the inflow rate steadily decreased down to 10.3 acre feet at the close of mining operations in <br />Year 2000. <br />i) Please provide monitoring data from MWNW, in accordance with the approved water <br />monitoring plan described in Exhibit 25. This data should be used in a detailed analysis of <br />the impact of the Southfield Mine on groundwater quantity. The analysis should also <br />include the data collected from the other groundwater monitoring points and be used to <br />validate any modeling conclusions. (If it is determined that NIWNW must be replaced, the <br />Division would appreciate the opportunity to discuss an alternative location for the new <br />monitoring well) <br />ii) Please clarify the lowest elevation that could be measured if MWNW were clear, and <br />whether or not this is the floor of the mine, (5855' was the elevation discussed in TR35 <br />adequacy correspondence and given on page 2.05.6 -53 of the PAP; 5860.5' was used in the <br />2013 Summary Report by BBA) <br />iii) Please provide a discussion of well MW16 explaining the fact that the recorded water level <br />dropped below 120' below ground surface (bgs) numerous times between 1979 and 2000, <br />but that since 2000 the well has often been reported as dry with the depth to water <br />indicated as 110' bgs (according to Exhibit 25, the depth of MW16 is 136' and the <br />screened interval is from 106'- 136'). <br />i) Moniioring well MW -NW is being monitored within 20 vertical feet of the Southfield mine workings (353 bgs). Given <br />the weak roof conditions in the P North mine section, where MW -NW is located it is likely that the 20 vertical foot reach <br />is an open void, (a rooffall, typical of the P North Section) ifso, the 20 foot void would be part ofthe mine workings in <br />the area of MW-NW. Nonetheless, it has been proven that MW-NW is open to water flow to the mine workings at a flow <br />rate exceeding 100 gallons per minute. <br />Concerning the Division's comment about the passibility of a new well in a new location, installing <br />another monitor well at Southfield would be conhwdictory to the Boulay June 2013 Memo (Page 13), wherein it states, <br />Additional monitoring of the coal zone is not warranted --- since groundwater is already known to be of <br />degraded quality and unlikely that it would be put to beneficial use, this would provide little additional <br />information - - - ". <br />12 <br />