Compliance with the MCLs of Section
611.300 or
611.301 (as
appropriate) must be determined based on the
analytical results obtained at each sampling point.
a) For suppliers that monitor at a frequency
greater than annual, compliance with the MCLs for antimony, arsenic, asbestos,
barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel,
selenium, or thallium is determined by a running annual average at each
sampling point.
1) If the average at any
sampling point is greater than the MCL, then the supplier is out of
compliance.
2) If any one sample
would cause the annual average to be exceeded, then the supplier is out of
compliance immediately.
3) Any
sample below the method detection limit must be calculated at zero for the
purpose of determining the annual average.
BOARD NOTE: The "method detection limit" is different from
the "detection limit," as set forth in Section
611.600. The "method detection
limit" is the level of contaminant that can be determined by a particular
method with a 95 percent degree of confidence, as determined by the method
outlined in appendix B to 40 CFR 136, incorporated by reference at Section
611.102.
4) If a system fails to collect the required
number of samples, compliance (average concentration) will be based on the
total number of samples collected.
b) For suppliers that monitor annually or
less frequently, compliance with the MCLs for antimony, arsenic, asbestos,
barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel,
selenium, or thallium is determined by the level of the contaminant at any
sampling point. If confirmation samples are required by the Agency, the
determination of compliance will be based on the average of the annual average
of the initial MCL exceedance and any Agency-required confirmation samples. If
a supplier fails to collect the required number of samples, compliance (average
concentration) will be based on the total number of samples
collected.
c) Compliance with the
MCLs for nitrate and nitrite is determined based on one sample if the levels of
these contaminants are below the MCLs. If the levels of nitrate or nitrite in
the initial sample exceed the MCLs, Section
611.606 requires confirmation
sampling, and compliance is determined based on the average of the initial and
confirmation samples.
d) Arsenic
sampling results must be reported to the nearest 0.001 mg/l.
