Dames & Moore, 1999 - USDA Forest Service

RC-8 during September did not contain cadmium concentrations near this concentration. Lead (0.5 p a)
was just above the CWQC (0.42 pg/L) in September 1997.
The comparison of RC-3 data collected during the Rl to area background concentrations indicate that
dissolved aluminum and manganese concentrations are above background for these metals during most of
the sampling events. Aluminum ranged from 40 to 70 pg/L. Manganese ranged from 6.48 to 15 pa.
Area background concentrations for aluminum and manganese are 37.4 pg/L and 2.42 pg/L, respectively.
The concentrations of aluminum and manganese at RC-3 during the fall are similar to RC-10 for
aluminum, but the concentration of manganese decreases from RC-10 to RC-3. Metal concentrations
were not above MTCA Method B cleanup levels for those metals without WQC. Comparison of RC-3
data to WQC is discussed in the following paragraphs.
Copper (I0 pg/L) was above AWQC (3.4 pg/L) and CWQC (2.6 pg/L) in May 1997. The data from May
1998 indicated similar results. The concentration of copper (12.6 pg/L) was above CWQC (2.4 pg.L) and
AWQC (3.0 p a). Zinc was above WQC in April and May 1997 and May 1998. The concentration of
zinc (41 pglL) in April was just above CWQC (39 p@) and just below the AWQC (42 pg/L). However.
this may be related to the potential introduction of zinc during the field filtration process. The
concentration of zinc (38 CLgn) in May 1997 was above CWQC and AWQC (24 and 27 pgL,
respectively). In May 1998, the zinc concentration (45 p a) was above the CWQC and AWQC (22 and
24 pg/L, respectively).
Iron cdncentrations continue to decrease from RC-5 to RC-3. Dissolved copper, cadmium, iron,' and zinc
concentrations also generally decreased from RC-5 (RC-5A) to RC-3. The pH, specific conductance, and
alkalinity remained similar between downstream stations and stations adjacent to the mine. Measured pH
ranged from 5.8 to 8.1 SU, similar to upstream measurements.
Seasonal.water quality and flow relationships also remained similar at downstream stations compared to
stations adjacent to the mine, with trace metals showing a general increase in spring, and iron, alkalinity,
hardness and specific conductance decreasing with increasing flow.
Organics
TPH and PCBs were analyzed at RC-3 and were not detected. PCB analysis was eliminated from sampling
events after July 1997 based on the results of the previous sampling events. TPH was analyzed in
September 1997 and not detected. This analysis was eliminated for future sampling rounds.
5.3.3.5 Railroad Creek Summary
Samples were collected from Railroad Creek upstream (RC-I, RC-6, and RC-I I), adjacent to (RC-4, RC-7,
and RC-2), and downstream (RC-5, RC-SA, RC-10, RC-8, and RC-3) of the Site to evaluate area
background- surface water quality in Railroad Creek hd assess the influence of the.mine on the water
quality in Railroad Creek.
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17693-005-019Uuly 28. 1999;11:09 AM:DRAFT FINAL RI REPORT