Dames & Moore, 1999 - USDA Forest Service

The data collected at P-5 were compared to ,WQC and for those metals where WQC is not available, ro
surface water background and MTCA Method B cleanup levels for surface water. The following PCOCs
were identified at P-5:.
May 1997 1 July 1997 I September1997 1 May 1997
Cd, Cu, Pb, Zn, pH I Cd, Cu, Pb, Zn. pH I. cd I Cd, Cu, Pb, Zn. pH
Similar to 4-1, dissolved aluminum, barium, thallium and uranium concentrations are above surface water
background in May. Aluminum and barium continue to exceed background concentrations in July.
Manganese is above background from May to September. Concentrations were not above available
MTCA Method B levels.
Cadmium and zinc consistently are above WQC from May to September. Copper and lead is above WQC
in May and July. The PCOCs identified match PCOCs identified at several Railroad Creek stations
downstream of P-5.
The concentrations of dissolved metals at P-5 generally were lower than concentrations at P- 1 in May due
to surface water run on into the drainage from snowmelt. In July, concentrations were similar with the
exception of dissolved iron which decreased. In September, dissolved metal concentrations at P-5 were
similar to P-1 with the exception of copper, iron, and zinc which decreased,
At P-5, dissolved aluminum, cadmium, copper, iron, lead, and zinc decreased from May to September
1997 similar to the trend identified at P-1. The cation concentrations (calcium, potassium and sodium)
increased during the same timeframe. Field measurements indicated that pH values changed from acidic
(4.9 SU) in May to neutral (6.7 SU) in September.
Increased concentrations of dissolved aluminum, cadmium, copper, manganese, and zinc at P-5 were
detected in 1998 as compared to May 1997. The increased concentrations are likely related to the timing
of the sampling event and position on the hydrograph. Stream flows were slightly higher in 1998 (3.8
cfs) than 1997 (3.42 cfs).
The data collected weekly from May 18, 1997 to June 16, 1997 indicated a steady decline of dissolved
aluminum, cadmium, copper, and zinc. Dissolved aluminum and copper decreased significantly (50 to
70%) from June 16, 1997 to July 12, 1997. Lead and iron concentrations from May 18 to June 16 were
relatively stable. Stream flows continually decreased during the timeframe of the weekly sampling.
The data fiom May 1997 and May 1998 both indicated similar trends of metal concentrations decreasing
and increasing from P-1 to P-5 (trend is metal dependent). The data fiom P-5 also shows that the influx
of surface water from the portal drainage to Railroad Creek introduces concentrations of aluminum,
cadmium, copper, lead, manganese, and zinc that are above background or WQC with the actual
concentration dependent upon season and stream flow. The portal drainage is a recognized source for
metals into Railroad Creek: Comparison to WQC shows that metals that exceed WQC for surface water
in the portal drainage at P-1 and P-5, primarily cadmium, copper, and zinc in May and July, coincide with
WQC exceedances in downstream Railroad Creek stations. The fate and transport of metals in and from
the portal drainage are further discussed in Section 6.0.
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