1995-08-11_REVISION - M1977493 ‎(10)‎

• Permit No: M1977493
• IBM Index Class Name: REVISION
• Doc Date: 8/11/1995
• Doc Name: EPP-III
• From: CMC
• To: DMG
• Type & Sequence: TR7
• Email Name: ACS
• Media Type: D
• Archive: No

01/11/1995 08:36 2168648136 MVTECHNOLOGIES, INC. PAGE 09
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much more effective in actually neutralizing acid production than either
silicates or phosphates. This particular shale is not contributing to the
acid generation problem at the present time; however, it could be a
contributor in the future.
The other seven samples (88049-3, 88049-4, 88049-6, 88049-7. 88049-8, 88049-9.
and 88049-10) represent the active acid-producing materials at the McNulty
dump. The paste pH values range from 5.6-6.5, only slightly acidic, and
indicate some acid generation. All seven of the samples contain large
quantities of pyrite. The pyrite is mostly in a finely divided state and
disseminated throughout the matrix of the rock. Pyrite in this form has more
exposed surface area and quickly oxidizes to form acid. Thus, most of the
acid generation potential of the pyrite in the rock will be realized.
Coupled with the high acid generation potential of the rock is the lack of
neutralizers. None of the seven rock samples contain any carbonate
neutralizers. The few neutralizers available ere silicates and phosphates and
as these few neutralizers are eventually overwhelmed by the large volume of
acid produced., site conditions will worsen and affect both water quality and
reclamation efforts severely. All seven of the samples that represent the
majority of the rock stored at the dump are net acid producers.
The sulfur forms data (Table b) show the samples to be slightly weathered
(except for 88049-1) and contain large quantities of sulfides (except for
88049-1 and 88049-2). Only samples 88049-2 and 88049-3 do not contain fairly
large concentrations of sulfate sulfur, a good indicator of acid generation.
As the pyrite is oxidized, acid sulfate salts are formed and stored on the
rock surfaces. 'these acid sulfate salts bec xw solubilized by infiltrating
water. The acid then solubilizes metals in the rock such as iron and
manganese and carries this to the lowest point of the McNulty dump where it
emerges as acid mine drainage (AMID).
There is more than sufficient pyrite available in all of the samples to serve
as feedstock for the iron-oxidizing bacteria Thiobacillus ferrooxidans. The
bacteria uses the reduced (ferrous) iron as its primary energy source.. A by-
product of the metabolic process is acid which is either leached or converted
to an acid salt. The ferrous iron is oxidized to ferric iron, itself a very
strong oxidant. The ferric iron will oxidize even more ferrous iron and other
metal sulfides and produce more acid. The process, catalyzed by T.
ferrooxidans, will continue until all pyrite is oxidized. The catalytic
efgect of the bacteria is such that acid production is increased by as much as
10 times over normal abiotic oxidation.
Bacterial enumeration testing done in 9K media revealed the presence of T.
ferrooxidans in all but two of the samples. Sample 88049-3 had T.
ferrooxidans present in the range from 100-999 bacteria per milliliter and
sample 88049-1 had them present in the range from 1,000-9,999 bacteria per
milliliter of soil extract water. Sample 88049-4 had them in the range from
100,000-999,999 per milliliter. Finally, sample 88049-6 and 88049-7 had the
bacteria present in excess of 1,000,000 bacteria per milliliter of soil
extract water. Even water sample 88049-B (acid seepage) tested positive for
T. ferrooxidans in the range from 1,000-9,999 bacteria per milliliter.