Issue 3 - the Montana Secretary of State Website

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monitoring plan for department review and approval. Ground water sampling and
the associated analyses and determinations are all fundamental aspects of the
ground water monitoring required by 75-10-207(4), MCA. The assessment
monitoring program in New Rule XL(5)(b) contains the elements of a ground water
assessment monitoring plan. Because department review and approval of a ground
water monitoring plan is required by Montana law, the findings requirements of 75-
10-107, MCA, do not apply. It is necessary for the department to review the
assessment monitoring program developed pursuant to (5)(b), and the statistically
significant change in an alternative list parameter pursuant to (6), to ensure the
ground water monitoring program meets the requirements of New Rule XLI.
Concerning a statistically significant change in an alternative list parameter
triggering assessment monitoring, in 40 CFR 258.54(a)(2), EPA allows the
department to use an alternative list of inorganic indicator parameters in place of
some or all of the metals in Appendix I. One of those parameters is pH. pH is a
measure of acidity. An increase in acidity is demonstrated by a decrease in pH.
Therefore, for pH, a statistically significant increase in acidity will be indicated by a
statistically significant decrease in pH. Because acids are highly reactive solvents,
heavy metals that are potentially harmful to human health are stripped off by higher
acidity and made more available to come into contact with people.
For pH, then, a statistically significant decrease is the appropriate measure
for determining whether assessment monitoring should be triggered. However, EPA
designated only a statistically significant increase in a constituent or parameter as
triggering assessment monitoring. Yet, as noted above, pH is an inorganic indicator
parameter that could be required to be monitored for on an alternative list. It would
be unreasonable for EPA to allow the department to use pH as an alternative list
indicator parameter for detection monitoring, and then not to have a consequence
for a statistically significant decrease. The omission of decreased pH from triggering
a consequence, while allowing it to be used as an alternative parameter, means that
EPA's regulation is not comparable and does not address the same circumstances
as New Rule XL(6). Therefore, New Rule XL(6) is not more stringent than the
comparable EPA regulation. Because the department did not wish to subject a unit
owner or operator to the increased cost of assessment monitoring, when decreased
pH was detected, unless the department had determined that it was necessary, the
department proposed to require assessment monitoring only when it was necessary
to protect health or the environment. Therefore, the department declines to revise
the language as requested in the comment.
Concerning department review of a demonstration of a statistically significant
change revealed by detection monitoring, it is necessary for the department to
review the demonstration, developed pursuant to (7) concerning a statistically
significant decrease from background levels for a pH, to determine whether
assessment monitoring is required. The department has prepared findings,
pursuant to 75-10-107, MCA, concerning the stringency of the requirement in (7) for
department approval. See Stringency Findings for this rule. Therefore, the
department declines to revise the language as requested in the comment.
The department notes that the word "total" in Appendix I, and a reference to
the word "total" in footnote 2, were stricken in response to Comment No. 54.
Montana Administrative Register 3-2/11/10