Dames & Moore, 1999 - USDA Forest Service

In general, concentrations in the upstream stations did not fluctuate with seasonal or stream flow variations.
Iron and hardness were inversely proportional to stream flow. Metal concentrations at the adjacent and
downstream stations were generally higher than the upstream locations. The widest variation occurred in
May. Concentrations were often similar by September. Concentrations for most metals increased
downstream of RC-1 at RC-4. Concentrations fiom RC-4 to RC-2 were similar or slightly decreased with
the exception of iron, which increased substantially at RC-7. Concentrations generally decreased from RC-
2 down to RC-3. Cadmium, copper, iron, and zinc concentrations are plotted from upstream station RC-6 to
downstream station RC-3 on Figures 5.3-10 through 5.3-13. Field measurements for pH, specific
conductance, and dissolved oxygen were similar fiorn upstream to downstream stations in Railroad Creek.
Samples collected fiom the south banks at RC-4 and RC-2 in 1997 were compared to samples collected
across the width of the creek. Concentrations of aluminum, cadmium, copper, manganese, and zinc detected
on the south bank of RC-4 during May 1997 were above concentrations detected across the creek width.
Concentrations in July and September were similar between the bank and creek width samples, with the
exception of copper. Data collected fiom the south bank at RC-2 were similar to data collected fiom the
width of the creek.
The south bank results from RC-4 and RC-2 were compared to state and federal WQC. Metals above WQC
in May, June, and July were generally comparable to the metals above WQC in samples collected across the
creek width. The September 1997 data compared to state WQC indicates that copper and zinc at RC-4 and
zinc at RC-2 are above WQC. The data from RC-4 indicates that copper is also above federal WQC during
this timeframe.
The weekly sampling performed at RC-2 indicated a continued decrease for most metals over time and with
decreasing stream flows.
Copper, cadmium, iron and zinc were identified as PCOCs in surface water in Railroad Creek at the stations
adjacent to and downstream of the Site. Aluminum and manganese concentrations were greater than
background concentrations.at stations adjacent to and downstream of the Site. The highest concentrations of
metals in 1997 correlated with the highest flow in Railroad creek measured in MayIJune 1997. In several
cases, metal concentrations measured in 1998 in stations adjacent and downstream of the Site were higher
than concentrations detected in 1997. The higher concentrations are likely related to the sampling event
occurring nearer the initial hydrograph rise (Section 4.0). Metal concentrations did not exceed MTCA
Method B cleanup levels (for constituents without WQC) at any stations on Railroad Creek.
5.3.4 Portal Drainage
Samples were collected from the 1500-level main portal drainage at two stations, P-1 and P-5. P-1 is
located at the exit of the mine portal and P-5 is located at the confluence with Railroad Creek and,upstream
of RC-4 (Figure 5.3-1 and 5.3-2). The data is summarized in Table 5.3-30. Additionally, one sample (VP-
1) was collected from the 1500-level ventilator portal located west of the portal. Data are summarized on
Table 5.3-30a.
5.3.4.1 Exit of Mine Portal (P-1)
.a Surface water grab samples were collected from the mine drainage at the 1500-level main portal opening (P-
I) during May, July, and September 1997 aid May 1998 to assess the water quality and seasonal variations
\DM-SEA I\VOLI\COMMOMWP\WPDATA\~~~\REPORTSWOLDEN-ZUUU~.~OE 5-3 1 DAMES & MOORE
17693-005-019Uuly 28. 1999.1 1:09 AMDRAFT FINAL RI REPORT