2015-02-12_REVISION - C1981014 - Laserfiche WebLink

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George V. Patterson, Energy Fuels Coal, Inc. Page 9 February 12, 2015 c) Impacts to Groundwater Quantity The PHC section of the PAP predicts the following impacts to groundwater quantity: • Minor reductions in down - gradient groundwater flows • Possible dewatering of abandoned mines in the Vento seam • Localized reductions in the piezometric surface • Localized alteration of groundwater flow patterns • Possible increases in recharge as a result of mine dewatering hi the letter of October 24, 2014, that accompanied the TR43 application, EFCI referenced these five predicted impacts and discussed each of them in qualitative terms. EFCI also provided historical water level data from MW 16, MW23 and MW65. The Division agrees with the general assertion made by EFCI, that the monitoring data that has been presented supports the predictions, however this is not sufficient for approval of TR43. As was laid out in the opening paragraph of this letter, the operator should provide a detailed analysis showing, among other things, that onsite impacts have been minimized and offsite impacts prevented, and should include... an evaluation of any impact trends which may exist in the available data. In the context of impacts to groundwater quantity, this will require that EFCI collect monitoring data from MWNW. There is no doubt that the Southfield Mine has had an impact on groundwater quantity within the coal seam and mine workings areas, but the extent of the impact is not well characterized. EFCI have previously submitted several reports from Bishop - Brogden Associates, Inc (BBA) pertinent to the discussion of groundwater quantity at the site, these reports are dated February 3, 1987,8 July 19, 2013,9 and November 11, 2014.10 In the opinion of the Division, a misconception is evident in the earliest of these reports. It has persisted and has led to confusion in the ongoing discussion of groundwater at the site. In the 1987 report BBA characterized the hydrogeology of the site based on water levels measured in five monitoring wells (MW8, MW 10, MW16, MW23 and MW65) on May 20, 1986. These five points were plotted on a map and contour lines were interpolated between them to produce figure 5 (1987 BBA report). This figure has the title "Ground Water Elevations" which is misleading. The individual points on the figure are more accurately labeled as "Elevation of potentiometric surface ". BBA used the contour lines of the projected potentiometric surface to infer a head gradient (and consequent groundwater flow direction) to the north east, parallel to Newlin Creek. Based on this analysis BBA characterized the groundwater in the Vermejo formation as "tributary to the surface stream system ", with a recharge zone to the west of the Chandler syncline, in the Wet Mountains; discharge where the formation outcrops to the east; and with a continuous potentiometric surface in between. This same conceptual model underlies the figure on page 2 of the 2014 report, which has red arrows pointing upwards from the mined area labeled "Expected Water Level Recovery ". The Division feels that a more accurate conceptual model is employed in section 2.04.7 of the PAP ( "Hydrology Description "). The model is described in a 4 page section of the permit text, pages 2.04.7 -8 through -11. The key points are summarized below: