Dames & Moore, 1999 - USDA Forest Service

parameters did not indicate seasonal differences. The data were compared to RI data where appropriate and
were relatively consistent between historical data and the RI.
5.3.6.2 Upstream Data
Samples were collected during the RI at CC-1 in May, July, and September 1997 to assess seasonal
variability of metal concentrations and in May 1998. The data were included in the background surface
water quality assessment discussed in Section 5.3.1. Summarized sample data are provided in Table 5.3-34.
Sample data and associated WQC are summarized for each sampling event in Tables 5.3-23 through 5.3-'27.
Background values are summarized in Table 5.3- 1.
The metal concentrations at CC-I do not appear to increase or decrease in response to seasonal variations.
Field measurements did not indicate significant variability between sampling events.
5.3.6.3 Adjacent to Tailings Piles
Samples were collected in Copper Creek at station CC-2 prior to the confluence with Railroad Creek during
May, July, and September 1997 and May 1998. Samples were analyzed for the same analytical suite as the
CC-1 samples. Comparison of CC-2 data to WQC indicated that metal concentrations were below the
AWQC and CWQC, with the exception of lead. The detection limit for lead (7 pg/L) during May 1997 was
above the AWQC (6.6 p a) and CWQC (0.26 pg/L) in the dissolved fraction. The result was qualified as
not detected during data validation due to laboratory contamination. The result for lead in the total fraction
in May 1997 showed that lead was not detected in this hction above the chronic or acute criteria. The
comparison of total to the dissolved concentrations indicate that lead results for May 1997 are not above the
criteria. The lead result in September 1997 was slightly above the chronic criteria (0.3 vs. 0.21 pa).
Dissolved lead in May 1998 was below AWQC and CWQC. Generally data from 1998 were similar to
data collected in 1997. Concentrations of total aluminum, iron, and manganese were 5 times greater in
1998 than 1997; however, the dissolved concentrations were similar. For those metals that do not
currently have water quality criteria assigned, concentrations were below background values and MTCA
B levels. Measurements for pH at CC-2 ranged from 6.1 to 8.1 SU, similar to measurements at CC-1 (6.0 to
8.0 SU).
The results of CC-2 are comparable to the CC-1 results. In addition, the metal concentrations between
stations do not indicate seasonal variations. PCOCs were not identified for Copper Creek.
5.3.7 Other Railroad Creek Tributaries
Samples were collected from Holden Creek, Big Creek, and TenMile Creek and the data were
incorporated into the background surface water quality assessment discussed in Section 5.3.1. The
statistically derived background values are summarized in Table 5.3.1. Detailed data summaries for
Holden Creek, Big Creek, and TenMile Creek are included in Tables 5.3-36through 5.3-38.
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