Dames & Moore, 1999 - USDA Forest Service

The portal drainage was sampled at the 1500-level main portal (P-I) and directly prior to the portal drainage
confluence with Railroad Creek (P-5). Dissolved aluminum. cadmium, copper, iron, and zinc decreased
from spring to fall. Manganese decreased slightly at P-l and increased slightly at P-5. The pH was acidic in
the spring and neutral in the fall. During the same sampling evenf concentrations of dissolved aluminum,
cadmium, copper, iron, manganese, and zinc generally decreased from P-l to P-5 in the spring, remained
constant in the summer, and were constant or decreased in the fall. The data from P-5 indicate that the
portal drainage introduces concentrations of aluminum, cadmium, copper, iron, lead, manganese, and zinc
into Railroad Creek that are above background with the actual concentration dependent upon season and
stream flow. The data for P-1 and P-5 were compared to surface water quality criteria (WQC and MTCA
Method B cleanup levels). P- 1 was compared to groundwater quality criteria (WAC 173-200 and MTCA
Method B cleanup levels) as well. PCOCs identified based on surface water comparison included
cadmium, copper, lead, zinc and pH. PCOCs identified at P-1 based on groundwater quality criteria
included arsenic, beryllium, cadmium, copper, iron, lead. zinc, sulfate, total dissolved solids. and pH.
The PCOCs are summarized by sampling event in Section 5.3.4. The fate and transport of metals in and
from the portal drainage are further discussed in Section 6.0.
A grab sample (VP-I) was collected from water discharging from the 1500-level ventilator portal.
Generally, the concentrations of dissolved metals were orders of magnitude lower than the corresponding
portal drainage samples. The pH was neutral (6.4 SU). The data appeared to indicate that the sample
collected was more indicative of meteoric water possibly resulting from snowmelt.
Water quality in the Copper Creek diversion was assessed. The Copper Creek diversion is the outflow from
the hydroelectric plant and is used as a source of water for a dipping pond associated with a sauna utilized
intermittently by residents and guests of Holden Village. Concentrations of cadmium, copper, iron,
manganese, and zinc during the spring were above upstream Copper Creek concentrations. The data were
compared to WQC. Cadmium, copper and zinc were identified as PCOCs in May (spring). Water quality at
the diversion is included in the human health risk discussion in Section 7.0.
Water quality in Copper Creek upstream of apparent Holden Mine influences and adjacent to the tailings
piles was assessed. The data from the upstream location was compiled with other data,in the background
surface water quality assessment. The data collected from CC-2 (adjacent to the tailings piles) was
compared to WQC and background values. Metals detected at CC-2 were not above WQC or background.
Additionally, concentrations between upstream and downstream stations on Copper Creek do not indicate
seasonal variations. PCOCs were not identified in Copper Creek.
5.4 GROUNDWATER
Groundwater samples were collected from groundwater monitoring wells located in Holden Village, west
of Holden Village near the baseball field, on the Site downgradient of the maintenance yard, in tailings
piles 1,2, and 3, downgradient of tailings pile 3, and from a single well located at Lucerne. Samples were
also collected from lysimeters located in tailings piles 1 and 3. The samples were collected during two
sampling events conducted in May 1997 and September 1997. Sample locations are shown on Figure
5.4-1.
As part of the groundwater quality assessment, samples were also collected from seeps located on the Site
and along Railroad Creek upgradient, adjacent to, and downgradient of the Holden Mine. The seeps were
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