Dames & Moore, 1999 - USDA Forest Service
Dames & Moore, 1999 - USDA Forest Service Dames & Moore, 1999 - USDA Forest Service
,' sulfate discharged from the portal w tly exceeds the mass of copper, zinc, iron and cadmium discharged at any given time. 6.5.1.2 Waste Rock Piles Air Movement Like mine workings, differences in temperature are important considerations in determining weathering processes (Figure 6.5-6). In summer, the inter& of the pile is anticipated to be cooler than the ambient temperature and there is no process to drive oxygen deep into'the pile. Oxygen enters the pile from the surface driven by diffusion leading to oxidation in the immediate pile surface only. The decrease in temperatures in the winter potentially creates optimal conditions for convective air flow (Figure 6.5-6). Warmer temperatures in the pile are created by heat generated by the oxidation processes. The temperature difference allows air to be drawn into the base of the pile providing further oxygen for oxidation. The process is self-perpetuating and indicates that winter can result in significant increases in internal temperatures.' This also allows oxidation rates to accelerate and encourages weathering products to accumulate. In the spring, melting of snow results in flushing of accumulated salts by cold water (Figure 6.5-6). This can c&l internal temperatures, and coupled with rising ambient temperatures, serves to reduce oxidation rates. -,- " Water Flow . The locations of the waste rock piles are shown on Figure 6.1-la. Four waste rock piles are discussed and include the west and east waste rock piles, and the 800- and 1 100-level portal waste rock piles. Waste rock ; piles associated with the 300, 500 and 700 portals are located on bedrock and are relatively small. There was no field evidence of seep discharge or surface water overland flow observed at these piles; therefore, they are not further discussed. , In the spring, upslope snowmelt run-on flows as overland flow and infiltrates on the slopes south of the waste rock piles and within each rock pile. Weathering products accumulated during the winter are leached. In general, groundwater moves downslope in the alluviaUreworked till unit and in the soiUfill material, and discharges either as seep overland flow or as groundwater baseflow into Railroad Creek (Figure 6.5-4). ' The spring conceptual groundwater flow path is to the north and northeast from the waste rock piles toward the intermittent drainage for the 800- and 1100-level waste rock piles, and toward Railroad Creek for the east and west waste rock piles, as shown on Figure 6.5-7. Some portion of groundwater flow is presumably diverted into the abandoned Railroad Creek channel. Groundwater in the alluvium/till that flows h m the west waste rock pile appears to emerge as intennittent seeps, SP-6 and SP-15E, and continues as overland flow to the lagoon (Figures 6.1-3a). Groundwater from the east waste rock pile appears to emerge as an intermittent seep (SP-8). Surface water flow from SP-8 flows overland across tailings pile 1 and is expressed as seep SP-19 before flowing into the Copper Creek diversion (Figure 6.1-3a). . \\DM-SEA I WVOLI\~OMMOMWP\~W)~\~~I~~~~~M).Q~ 6-29 17693-005019Uuly 27.1999;4:11 PM;DRAFT FINAL R1 REPORT
In the fall, groundwater flow is reduced and flows in a more northeasterly direction, indicating less input from valley side slopes and more influence from the downvalley groundwater flow component (Figure 6.5- 8). Seep discharge was not observed, but the movement of groundwater through the abandoned Railroad Creek channel presumably continues. Waste Rock Leachate Chemistry The chemistry of waters seeping from the vicinity of the waste rock piles is very similar to the P-1 discharge and the mill building when considering ratios of key elements. The main feature of the waters, as measured at SP-8, SP-15, and SP-14 (lower) are that they contain relatively high copper and zinc to sulfate ratios (0.1 movmol) and low iron to sulfate ratios (40" moYmol) when compared to the tailings pile seepage (e.g., SP-2, SP-3, SP-4 and SP-5) (CdS04 ~n/~04
- Page 734 and 735: SOURCES: SRK 'nfi""On Limited Air M
- Page 736 and 737: Figure 6.5-5 DAMES & MOORE 1997 POR
- Page 739 and 740: SOURCE: Base map information from U
- Page 741 and 742: SOURCE: SRK Oxidation limit Mn++ Fe
- Page 743: Direct Precipitation IXMES & MOORE
- Page 746 and 747: Infiltration of Snowmelt and Interm
- Page 748 and 749: Notes: Water Runon and Direct Preci
- Page 750 and 751: Surface Water Runon and Direct Prec
- Page 752 and 753: SOURCE: SRK L DAMES ,& MOORE A DAME
- Page 754 and 755: SOURCE: SRK 10 -i DAMES & MOORE + H
- Page 756 and 757: (* 6.0 TRANSPORT AND FATE OF COMPOU
- Page 758 and 759: 1 I .J Quartz-rich layeis of 40 per
- Page 760 and 761: Crystalline crusts were observed in
- Page 762 and 763: I ( 4. -.- h .*, Evidence of signif
- Page 764 and 765: Predicted saturation indices (SI) f
- Page 766 and 767: Another iron sulfide mineral at the
- Page 768 and 769: . .. . .I.- ..9 6 If water flow is
- Page 770 and 771: pH Control on Precipitation~Dissolu
- Page 772 and 773: summer. Efflorescence occurs when w
- Page 774 and 775: 6.4.1 Evidence of Iron Sulfide Mine
- Page 776 and 777: to the underground mine workings, r
- Page 778 and 779: The pH to copper relationship (Figu
- Page 780 and 781: 6.5.1 Air and Water Movement Associ
- Page 782 and 783: .._/ not originating from the under
- Page 786 and 787: decreases also, aiding in the disso
- Page 788 and 789: .: ._..I $ . .,'. Seasonal s , - We
- Page 790 and 791: . ., Miring of Seeps with Railroad
- Page 792 and 793: through diffusion. This is indicate
- Page 794 and 795: MlNTEQA2 indicates that the seep wa
- Page 796 and 797: In order to. provide comparative fl
- Page 798 and 799: main source of zinc load (82 percen
- Page 800 and 801: ,:..' -- . source areas was estimat
- Page 802 and 803: Monitoring of seeps from drill hole
- Page 804 and 805: ,' .... . control and buffering by
- Page 806 and 807: , ; . ..' , . .. .. -. . ..&. .< .
- Page 808 and 809: -- (i,e., portal drainage) for cadm
- Page 810 and 811: TABLE 6.0-1 KEY OF SITE FEATURES 8
- Page 812 and 813: TABLE 6.0-1 KEY OF SITE FEATURES 8
- Page 814 and 815: TABLE 6.0-1 KEY OF SITE FEATURES 8
- Page 816 and 817: T.bk abi Losding WNlatlons - R d W
- Page 818 and 819: TABLE 6.6-3 LOADING CALCULATIONS -
- Page 820 and 821: J O NO. ~ 17693-005-019 Draft Final
- Page 824 and 825: Approximate -1 % Grade for 15OPLeve
- Page 826 and 827: LEGEND SP14 Seep sample location P-
- Page 828 and 829: Oxidant I ZnS H20 (transport mechan
- Page 830: Figure 6.3-4a I SOURCE: SRK Figure
,'<br />
sulfate discharged from the portal w tly exceeds the mass of copper, zinc, iron and cadmium discharged at<br />
any given time.<br />
6.5.1.2 Waste Rock Piles<br />
Air Movement<br />
Like mine workings, differences in temperature are important considerations in determining weathering<br />
processes (Figure 6.5-6). In summer, the inter& of the pile is anticipated to be cooler than the ambient<br />
temperature and there is no process to drive oxygen deep into'the pile. Oxygen enters the pile from the<br />
surface driven by diffusion leading to oxidation in the immediate pile surface only.<br />
The decrease in temperatures in the winter potentially creates optimal conditions for convective air flow<br />
(Figure 6.5-6). Warmer temperatures in the pile are created by heat generated by the oxidation processes.<br />
The temperature difference allows air to be drawn into the base of the pile providing further oxygen for<br />
oxidation. The process is self-perpetuating and indicates that winter can result in significant increases in<br />
internal temperatures.' This also allows oxidation rates to accelerate and encourages weathering products<br />
to accumulate.<br />
In the spring, melting of snow results in flushing of accumulated salts by cold water (Figure 6.5-6). This<br />
can c&l internal temperatures, and coupled with rising ambient temperatures, serves to reduce oxidation<br />
rates.<br />
-,- " Water Flow<br />
. The locations of the waste rock piles are shown on Figure 6.1-la. Four waste rock piles are discussed and<br />
include the west and east waste rock piles, and the 800- and 1 100-level portal waste rock piles. Waste rock<br />
; piles associated with the 300, 500 and 700 portals are located on bedrock and are relatively small. There<br />
was no field evidence of seep discharge or surface water overland flow observed at these piles; therefore,<br />
they are not further discussed.<br />
,<br />
In the spring, upslope snowmelt run-on flows as overland flow and infiltrates on the slopes south of the<br />
waste rock piles and within each rock pile. Weathering products accumulated during the winter are leached.<br />
In general, groundwater moves downslope in the alluviaUreworked till unit and in the soiUfill material, and<br />
discharges either as seep overland flow or as groundwater baseflow into Railroad Creek (Figure 6.5-4).<br />
' The spring conceptual groundwater flow path is to the north and northeast from the waste rock piles toward<br />
the intermittent drainage for the 800- and 1100-level waste rock piles, and toward Railroad Creek for the<br />
east and west waste rock piles, as shown on Figure 6.5-7. Some portion of groundwater flow is presumably<br />
diverted into the abandoned Railroad Creek channel. Groundwater in the alluvium/till that flows h m the<br />
west waste rock pile appears to emerge as intennittent seeps, SP-6 and SP-15E, and continues as overland<br />
flow to the lagoon (Figures 6.1-3a).<br />
Groundwater from the east waste rock pile appears to emerge as an intermittent seep (SP-8). Surface water<br />
flow from SP-8 flows overland across tailings pile 1 and is expressed as seep SP-19 before flowing into the<br />
Copper Creek diversion (Figure 6.1-3a).<br />
. \\DM-SEA I WVOLI\~OMMOMWP\~W)~\~~I~~~~~M).Q~<br />
6-29<br />
17693-005019Uuly 27.<strong>1999</strong>;4:11 PM;DRAFT FINAL R1 REPORT