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Dames & Moore, 1999 - USDA Forest Service

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25 pprn hardness as this is the minimum hardness allowed for WQC under the federal guidance when<br />

actual hardness values are below 25 ppm. The WQC and background values are summarized below.<br />

Metal<br />

Arsenic<br />

Cadmium<br />

Chromium<br />

Copper<br />

Lead<br />

Mercury*<br />

Selenium<br />

Silver<br />

Zinc<br />

Background<br />

Concentration<br />

( P m<br />

0.9<br />

0.07<br />

c0.2<br />

1.06<br />

0.54<br />

0.0006610.05<br />

~0.2<br />

4.04<br />

7.81<br />

*CWQC is based on total metals (0.00066 p&). AWQC is based on dissolved metals (0.05 pa).<br />

WQC<br />

(P@)<br />

(hardness 25 ppm)<br />

Based on 6.7 ppm, lead and silver background concentrations (0.54 pg/L and c0.04 pg/L) may exceed the<br />

WQC. The lead background value of 0.54 pg/L is likely enhanced due to the suspected laboratory<br />

contamination previously discussed. However, if 0.54 pg/L is considered background, the value exceeds<br />

the CWQC of 0.12 pg/L if hardness is 6.7 ppm. In the case of silver, the detection limit currently<br />

achievable by modification of standard methods is 0.04 pg/L. With a hardness of 6.7 ppm, this detection<br />

limit will exceed the AWQC of 0.030 pg/L. The background copper concentration (1.06 pg/L) is only<br />

slightly below the WQC at a hardness of 6.7 ppm. Based on a minimum hardness of 25 ppm, the<br />

statistically derived background values are below acute and chronic WQC.<br />

For those metals where WQC are not established, data were compared to MTCA Method B cleanup<br />

levels. Calculated background values did not exceed MTCA Method B cleanup levels.<br />

Adjacent and Downstream of Site<br />

WQC<br />

(P@)<br />

(hardness 6.7 ppm)<br />

AWQC<br />

3 60<br />

0.20<br />

60<br />

1.3<br />

3.1<br />

2.4<br />

144<br />

20<br />

0.030<br />

12<br />

AWQC<br />

360<br />

0.82<br />

180<br />

4.6<br />

14<br />

2.4<br />

440<br />

20<br />

0.32<br />

35<br />

CWQC<br />

190<br />

0.37<br />

57<br />

3.5<br />

0.54<br />

0.012<br />

49<br />

5<br />

NE<br />

32 -<br />

Listed below are the dissolved metals that were above the AWQC and CWQC during the five sampling<br />

events.<br />

Listed below are the dissolved metals that were above the State of Washington AWQC and CWQC, which<br />

are based on actual hardness values during the RI sampling events in 1997 and 1998.<br />

\U)M~SEAI\VOLI\COMMOMWRWPDATA\00J\REPORTS\HOLDEN-2UU 8-28<br />

17693-005-019Uuly 28, <strong>1999</strong>:10:24 AM;DW FINAL RI REPORT<br />

CWQC<br />

190<br />

0.14<br />

19<br />

1.1<br />

0.12<br />

0.0 12<br />

16<br />

5<br />

NE<br />

11<br />

0

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