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iiiiiiiiiiiniiiiii TO: Harry Ranney 26 Feb 1997 FROM: Jim Burnell SUBJ: Hamilton Mine Groundwater Review At Larry Routten's request, I have reviewed the Groundwater portion of the Probable Hydrologic Consequences discussion for the Hamilton Mine's Mid-Term Review. As you undoubtedly recognize, there is precious little to go on in the way of water data for the site. Groundwater is monitored in three different settings. They are as follows: a) The bedrock aquifer underlying the coal-bearing sequence - the Burro Canyon Aquifer, monitored in wells BW-1, 2, and 3, is sampled to monitor the impact of the mining on the water level and water quality. One of these wells, (BW-3) is upgradient of the activities, one well (Bw-1) is apparently cross-gradient, and one well (BW-2) is clearly down-gradient of the mining-related activities. The monitoring program shows wells BW-1 and 3 to be little impacted by the mining activities. Well BW-2 - the down- gradient well - has been dry actually since before mining was started. Hence, it is difficult to say if mining has had an impact on this aquifer. Because the water-bearing unit is 100 feet or more below the coal-bearing strata, separated from it by largely impermeable layers, it seems unlikely that any significant impact would occur, despite the clearly worst-case comments in the PHC that mining could decrease the piezometric levels and degrade the water quality. One could probably say that, but there has been little evidence that either has occured to date. b) Springs and seeps in and around the permit area were identified and have been monitored as sites SP-1 through 6. According to the narrative, these springs also emanate from the Burro Canyon formation. They have been dry essentially since before mining started. So, the conclusions to be drawn from the springs and seeps is essentially the same as that from the bedrock wells discussed above. c) The third mode of groundwater occurrance monitored is alluvial groundwater in several spots. Well AW-3 was drilled within "Section 33 Creek," an unnamed ephemeral stream channel in the midst of the mined area. Wells AW-4 and 5 are in the channel of Braimers Draw where it enters Naturita Creek. Braimers Draw drains the western half, essentially, of the permit area. AW-4 is located on the up- gradient side of an irrigation ditch - the Reed Chatfield ditch - which (apparently) intersects and crosses the streambed. Wells AW-6 and 7 are sunk in the alluvium of Naturita Creek, a small flow that lies downstream (and North) of the permit area. My