Dames & Moore, 1999 - USDA Forest Service

greater than two times the 90' percentile value (background) and less than ten percent of the sample
concentrations may be above the 90' percentile value in a data set. PCOCs were identified where metal
concentrations were (1) greater than 2 times background, or (2) more than 10% of the sample
concentrations in a data set were above background, and (3) concentrations were above MTCA Method A
cleanup levels or MTCA Method B cleanup levels if Method A levels were not available. Exceptions to
the PCOC assessment were cations (calcium, magnesium, potassium, and sodium), aluminum, and iron as
there are no available cleanup levels provided for these metals. Calcium, magnesium, potassium, and
sodium are considered nutrient metals and were not considered as PCOCs. lron and aluminum were
considered PCOCs if the results were above background as noted above.
5.2.2 Holden Village
5.2.2.1 Historical Soil Samples
Seven surficial soil samples (HV-IA, HV-2A, HV-3A, HV4A, HV-5A, HV-6A, HV-7) were collected in
1994 by the USBM in Holden Village. One surface soil sample (HW-1 A) was collected in the area near the
current USFS guard station west of Holden Village. Sample locations are shown in Figure 5.2-3 and the
data are provided in Table 5.2-3.
Concentrations of aluminum, beryllium, chromium, copper, iron, lead, mercury, nickel. silver, and zinc
were above background levels in several samples, however with the exception of beryllium, all were
below MTCA cleanup levels. Beryllium concentrations were slightly above background (0.2 mgkg) and
the MTCA Method B level (0.23 m ag) in samples HV-4A (0.32 mgkg) and HV-6A (0.29 mgkg). lron
concentrations above background (24,100 mgkg) ranged from 26,200 to 28,400 mgkg and were detected
in samples HW-lA, HV-3A, HV-4A, and HV-6A. Aluminum concentrations ranged from 21,400 mgkg
to 25,100 mgkg and were above background (20.900 mgkg) in samples HV-]A, HV-3A, HV4A, and
HV-6A.
Sample HW-1A contained arsenic (25.2 mgkg) above background and the MTCA Method A (20 mgkg)
level.
5.2.2.2 RI ~ 6i1 Samples
Seven surficial soil samples (DMSS-1, DMSS-2, DMSS-3, DMSS-4, DMSS-5, DMSS-6, DMSS-7) and a
field duplicate (DMSS-6X) were collected in September 1997 in and around Holden Village. The
samples were analyzed for metals. Sample locations are shown in Figure 5.2-1 and analytical data are
summarized in Table 5.2- 1.
Concentrations of aluminum, barium, beryllium, chromium, copper, iron, lead, molybdenum, nickel,
silver, and zinc were detected in one or more samples above background concentrations. However, with
the exception of beryllium, the concentrations were below MTCA levels. Beryllium concentrations were
slightly above background (0.2 mgkg) and the MTCA Method B level (0.23 mg/kg) in samples DMSS-1
(0.3 mg~kg), DMSS-3 (0.3 mgkg), DMSS-6 (0.3 mgkg), and DMSS-6X (0.3 mg/kg). Iron
concentrations above background (24,100 mgkg) ranged from 24,600 to 29,600 mgkg and were detected
in samples DMSS-2, DMSS-3, DMSS-4, DMSS-5, DMSS-6, and DMSS-6X. Aluminum was above
background (20,900 mgkg) in samples DMSS-3, DMSS-6, and DMSS-6X and ranged from 23,500
1 m@g to26.300 m@g.
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