2011-01-24_REPORT - C1980005

• Permit No: C1980005
• IBM Index Class Name: REPORT
• Doc Date: 1/24/2011
• Doc Name: 2009 AHR Review Response
• From: Seneca Coal Company
• To: DRMS
• Annual Report Year: 2009
• Permit Index Doc Type: Hydrology Report
• Email Name: SLB
• Email Name: SB1
• Media Type: D
• Archive: No

we use (M379.2), with a MDL of 0.02 mg/l, is the most sensitive that
they are aware of. There are other considerations in regards to
sulfide analysis that we will discuss below in Item 13.b.
In regards to mercury, Seneca runs two different mercury tests, a high
level test with a MDL of 0.2 ug/l (for streams and NPDES sites) and a
low level test with a MDL of 0.0002 ug/l (for NPDES sites only). The
high level test costs $15.00, while the low level test costs $56.25,
and requires a use of a trip blank (at the same cost) for each
sampling event. The low level test also requires laborious `clean
hands' sampling techniques. The low level test was required by the
CDPHE, starting in 2007, on our NPDES outfalls to determine if there
was a `Reasonable Potential' (RP) to require further sampling and
permit limits. The CDPHE performed a RP analysis in 2010 on all Seneca
outfalls, except Outfalls 005 (Seneca II-W), 011, 013 and 014 (Yoast);
which did not have the required number of samples to perform the RP
analysis. They concluded that there was no RP for mercury, and dropped
mercury monitoring requirements. Our pages 7 to 11 are the monitoring
requirements in the most recent NPDES permits. Note that Outfalls 002,
003 and 004 are a separate NPDES permit for the Peabody Sage Creek
Mine. No outfalls currently require mercury testing, except for the
MN... series on our pages 10 and 11, which are the outfalls mentioned
above that did not have enough samples yet to perform the RP. For
these reasons (no RP and expensive, laborious test), we feel that it
is unnecessary to continue performing the low level mercury test.
Item 13.b. You asked about the discrepancies in some sulfide data.
The sulfide data presented in Appendix D is the total of both the
ionized (S-) and un-ionized (H2S) forms of hydrogen sulfide. The un-
ionized form is the potentially toxic form, and is what the CDPHE
water quality standard is based upon. To calculate the un-ionized
form, we use the procedure outlined on our pages 13 and 14. The
results of those calculations are presented in Tables 14 and 16 of the
AHR. That is why those values are different than the values found in
Appendix D. Our page 12 comes from the 2004 Seneca II AHR. That was
the last AHR which described the sulfide calculation procedure. We
will include this discussion in future AHR's.
Finally, in regards to the elevated MDL (0.2 mg/1) you noted for
sulfide. The normal MDL for sulfide is 0.02 mg/l. Per ACZ Labs, this
test is a colorimetric test. If the sample has any color (or
turbidity), then the sample must be diluted, resulting in an elevated
MDL. That was the case in the sample you may have noted. A sample from
Seneca Coal Company • P.O. Box 670 • Hayden, Colorado 81639
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