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Liming
the Pit
Basic
pit waste treatment involves aeration, liming and settling
and each step serves a purpose. The 1985
Fact Sheet created by the state for an earlier version
of the General
Water Pollution Control Permit explains the rationale.
Concerns
at the DEP were varied: how to manage heavy metals, how to
manage volatile hydrocarbons, and how to lessen the overall
contaminant level of the liquid pit waste.
Aeration's
main purpose is to promote the evaporation of the volatiles,
which for natural gas well drilling tend to be prevalent.
The four main volatile organic compounds of concern are benzene,
toluene, ethylbenzene and xylene (BTEX), though there are
numerous other volatiles, including some that are used sometimes
as drill mud additives (such as the biocide glutaraldehyde).
Liming,
which is done at the same time as aeration, serves two purposes:
to raise the pH (some pit waste can be very acidic) and to
precipitate out some of the heavy metals by a process called
hydroxide precipitation. We call it liming the pit because
lime (calcium carbonate) is most commonly used, but caustic
soda (sodium hydroxide) can also be used. A
web page explains the process well. (To use the chart
on that web page, Fe is iron, Cr is chromium, Cu is copper,
Zn is zinc, Ni is nickel, Cd is cadmium, Pb is lead, and Ag
is silver.)
The
final step is settling and the DEP's belief in 1985 was that
settling should be encouraged to last "at least 10, preferably
20 days." As the permit is written now, though, settling
is 5 days for category 1 pits, 10 days for category 2 pits,
and 20 days for category 3 pits.
While
this treatment process may work, we have concerns. Aeration
is meant to evaporate dangerous volatiles but there seems
to be a singular lack of concern for workers or those who
live near the well site. A visible mist floats above the pit
during the process and the time we saw it being done the operator's
employee wasn't wearing a protective mask or breathing apparatus.
Benzene is extremely toxic and is perhaps the most common
of dangerous wellfield contaminants. Glutaraldehyde (if it
was used as an additive) is not known to be carcinogenic (is
suspected) but can, upon exposure, create chemical hypersensitivity.
Our best guess is that a distance of at least 300 feet should
be maintained during aeration of a drill waste pit unless
protective gear is worn. Aeration occurs again when the liquid
pit waste is landsprayed. Protective gear should be worn then
also.
A
table showing pit constituents of five wells drilled in different
West Virginia counties appeared in the 1985 Fact Sheet, and
the values for metals after treatment are all low. To us,
suspiciously low. (We've transcribed part of that table and
it's
in the pitfluids.xls workbook along with the chloride
load and SAR worksheets.) Hydroxide precipitation uses pH
to target particular metals. Some metals, like iron, begin
to precipitate when the pH rises above 3. The iron test required
by the state in the General Water Pollution Control Permit
is to confirm that the hydroxide process has been effective.
Other metals, such as lead, don't begin to precipitate until
a pH of about 8.5, stop precipitating at 10 and begin to be
reabsorbed into the liquid as it becomes more basic.
The
state requires that pit pH be from 6 to 10 and the DMR for
the Berry well states that the pH during landspraying was
7.5. Lead would not have begun precipitating nor would other
toxic heavy metals cadmium and silver.
The
hydroxide process might be satisfactory except in cases where
a company has used additives, particularly weighing agents,
that contain heavy metals such as arsenic, lead or mercury.
As it is now, we think the state relies too heavily on liming
to deal with all situations.
Other
states and some Canadian provinces use load criteria for certain
metals, just like they do for salts and sodium. We believe
that this is a more sensible policy.
The
next chapter presents a short history of fracturing derived
from well reports filed with the state for several wells (including
the B800 well).
Go
to A Short History of Fracturing.
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