SGC Low Flow 2017 Mayflower Area Field Investigations. April 27, 2017

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1 SGC Low Flow 2017 Mayflower Area Field Investigations April 27,

2 Purposes of Presentation Provide background on Mayflower area Provide an update regarding SGC s field activities Provide a review of preliminary findings, including the innovative drone sampling program conducted in the Mayflower area in February and March 2

3 Background SGC in the Silverton Caldera The Caldera is highly mineralized, and acid rock drainage and poor water quality were prevalent long before the advent of mining The Caldera hosted dozens of mines and mills between the 1870 s and 1985 SGC was formed and acquired the Sunnyside Mine in 1985 and mined it from 1986 until 1991 using modern techniques and under the modern era of environmental regulation SGC closed the Mine in accordance with the law, its permits and a state approved consent decree and has spent over $15 million on reclamation and remediation SGC s 5 years of mining in the Silverton Caldera is not the cause of water quality problems in the Animas River SGC s activities in the Silverton Caldera, including major reclamation and remediation efforts spanning more than 30 years, have been a significant net positive for the environment 3

4 Background The Mayflower Area Includes 4 tailings impoundments constructed between 1936 and 1977, a time when there was limited regulation Multiple owners over 70 years, as area used for waste disposal by public and private parties, including impoundments #3 and #4 being used as a BLMapproved municipal landfill During SGC s brief 5 years of mining in the Silverton Caldera, SGC used only impoundment #4 SGC reclaimed the 4 impoundments in accordance with the law and its permits In September 2016, the Mayflower Area was illegally, and without basis and proper evaluation, made part of the Superfund listing SGC has challenged this illegal action in Court, and local landowners, Mountain States Legal Foundation, the National Mining Association, and the American Exploration and Mining Association have filed briefs supporting the Mayflower Area being removed from the Superfund listing As a significant contributor to the local collaborative efforts to improve water quality, SGC voluntarily undertook sampling programs in the Mayflower Area in 2015, 2016 and

5 Health and Safety The health and safety of all field personnel is the number one priority. All work was performed in accordance with site specific health and safety plans (HASPs). Field personnel did not enter flowing water if deemed unsafe. Over three thousand field hours worked in 2015, 2016, and early 2017 with no incidents. 5

6 Water Quality Data Samples were collected from the Animas River during February and March, 2017 using an Unmanned Aerial System (UAS or drone) to provide safe access. Results on March 21 and 22 are questionable due to road work. Sampling methods will be documented in a forthcoming 2017 Work Plan for the Mayflower Area but are consistent with previous work plans. 6

7 7

8 Water Quality Data Samples were collected from the following stations during February and March, 2017: Howardsville 4023 (A56) 4581 (A61) (A65) (A66) (A68) 8

9 Water Quality Data Samples collected from the Animas River were limited in volume due to the collection method - the drone used has a very small payload capacity. The February samples were analyzed for the dissolved forms of cadmium, copper, lead, manganese, and zinc. Total aluminum and iron were added in March. 9

10 Water Quality Data The following plots show all data collected by SGC for each metal, in spatial orientation from upstream to downstream. 10

11 Aluminum, Total 11

12 Cadmium, Dissolved 12

13 Copper, Dissolved 13

14 Iron, Total 14

15 Lead, Dissolved 15

16 Manganese, Dissolved 16

17 Zinc, Dissolved 17

18 Water Quality Data General observations for the February and March, 2017 data: In general, there is a spike at station 4581 (A61), an area where there is discharge from bedrock, and the values change very little at the downstream stations. Concentration increases appear to correlate with initial increase in Animas River flow rate. Flow at A68 in February was ~20 CFS; March flow was ~45 CFS. 18

19 February vs. March Groundwater Elevations Groundwater elevations in February and March were compared to assess potential relationships to March concentration increases in the Animas River. A potentiometric surface map for the alluvial aquifer was prepared for each time frame using Surfer software. 19

20 Groundwater Elevation Pressure transducers were deployed in Mayflower area 16 monitoring wells and 9 piezometers in November, Groundwater level data were downloaded in March Transducers recorded water levels every 8 hours during this period. 20

21 Wells/Piezometers 21

22 Groundwater Elevations General observations: Water levels in monitoring wells completed in the Mayflower Mill area and in alluvium under TP-1 began to increase in February Past groundwater observations and geophysics indicate this area is not connected to the river. Additionally, the groundwater levels in March were not in contact with the tails at TPs 1 & 2. Water levels in the other monitoring wells generally showed no rise in February. 22

23 February vs. March Groundwater Elevations The potentiometric surfaces for February and March were compared, using Surfer software, to estimate: Differences in the lateral extent of the alluvial aquifer. Net change in groundwater level elevations. 23

24 March 21 and February 14, 2017 Alluvial Aquifer Extent Comparison February 2017 Alluvial Aquifer Extent March 2017 Alluvial Aquifer Extent

25 March 21st Groundwater Elevations Minus February 14th Groundwater Elevations Groundwater Elevation Difference March 2017 Alluvial Aquifer Extent

26 February vs. March Groundwater Elevations Little difference in the estimated lateral extents of the alluvial aquifer from February to March. Relatively large water level increases occurred in: Isolated portion of the alluvial aquifer underlying the east end of Tailings Impoundment 1 (~8 ft), and Tailings Impoundment 3 (~16 ft). 26

27 February vs. March Groundwater Elevations Additional investigation is needed to assess whether increased groundwater levels in the alluvial aquifer are associated with increased concentrations in the Animas River. 27

28 2017 Investigations The following work is planned for the Mayflower area in 2017: Geophysical investigation of groundwater flow paths. Installation of additional monitoring wells. Continued monitoring of the Animas River and its inflows. 28

29 Questions? 29