Dames & Moore, 1999 - USDA Forest Service

5.3.4.3 Historical Portal Drainage Data
Surface water samples associated with the 1500-level main portal drainage were collected intermittently at
two locations (P-1 and P-5) between 1982 and 1991 and again between 1992 and 1996. Only a few
concurrent monitoring dates were conducted for both stations. A summary of the data is presented in Table
5.3-31.
Historical concentrations of copper, lead, iron, and cadmium at P-1 and P-5 were generally within the same
order of magnitude as the RI data during similar seasonal dates. Copper, zinc, and lead appeared to have a
direct relationship with flow, i.e., their concentrations were higher during high stream flow than during low'
flow conditions at P- 1.
The USGS collected samples from the P-1 and P-5 locations concurrently in July 1994, July 1995, May
1996, and September 1996. The trends noted in this historical data were comparable to the trends
detected in the RI data. Concentration of dissolved aluminum, copper, iron, manganese, and zinc
decreased from P-1 to P-5 in May and September. Concentrations of these metals remained constant
between the two stations in July. Measurements for pH were acidic in the spring and neutral by fall.
5.3.4.4 Ventilator Portal
A grab sample (VP-1) was collected from water discharging from the 1500-level ventilator portal. 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. The data were not compared to
WQC. However, the metal concentrations were compared to surface water background for dissolved
metals. Metal concentrations in the sample were below background.
5.3.5 Copper Creek Diversion
Samples were collected from the Copper Creek diversion (CC-D, CC-Dl) during April, May, July, and
September 1997 and May 1998 (Figure 5.3-1). The sample identification was originally designated as
CC-D in April and revised to CC-Dl for the remainder of the RI. There are no specific background water
quality conditions for the diversion; however, water quality at the point of diversion in Copper Creek is
assumed to be similar to CC-1. Data were compared to the Copper Creek upgradient station (CC-I) and
to WQC. The data are summarized in Table 5.3-32.
Water quality in the diversion was similar to CC-1 for all constituents except cadmium (1.76 p&), copper
(145.8 pgk), iron (230 p@), manganese (7.95 pa), and zinc (172 pg/L) during the 1997 MayIJune
sampling round which were one or more orders of magnitude above concentrations detected at CC-1. In
addition, the results for these metals from the MayIJune round were higher than results from the July and
September 1997 sampling events. This is explained by the inflow of seeps and site runoff into the Copper
Creek diversion during the MayIJune period.
The data were compared to WQC. Cadmium, copper and zinc were above AWQC and CWQC in May.
The data were also compared to MTCA Method B cleanup levels for those metals without WQC. MTCA
Method B levels were not exceeded. The measured pH in the field ranged from 5.5 to 7.15 SU, with a one
time event (September) where pH was outside of the water quality criteria for pH (6.5 to 8.5 SU).
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17693-005-019Uuly 28, 1999:11:09 Ah4;DRAFT FINAL RI REPORT