Current through August 26, 2024
(1) GENERAL. Water
suppliers for community and non-transient non-community water systems shall
monitor for the contaminants listed in s.
NR 809.24 for purposes of determining compliance with the
maximum contaminant levels as follows:
(a)
Groundwater sources shall be sampled at every entry point to the distribution
system which is representative of each well after treatment. Each sample shall
be taken at the same location unless, if approved by the department, conditions
make another location more representative of each source, treatment plant, or
within the distribution system.
(b)
Surface water sources or combined surface water and groundwater sources shall
be sampled at each entry point to the distribution system after treatment or at
points, if approved by the department, in the distribution system that are more
representative of each source after treatment. Each sample shall be taken at
the same location unless, if approved by the department, conditions make
another location more representative of each source, treatment plant or within
the distribution system.
(c) If the
public water system draws water from more than one source and the sources are
combined before distribution, the public water system shall be sampled at an
entry point to the distribution system during periods of normal operating
conditions when water representative of all sources is being used.
(d) Water suppliers for new public water
systems or public water systems that use a new source of water shall
demonstrate compliance with the MCLs specified in s.
NR 809.24 in accordance with the requirements in this
section. The water supplier shall also comply with the initial sampling
frequencies specified by the department to ensure the public water system can
demonstrate compliance with the MCLs. Routine and increased monitoring
frequencies shall be conducted in accordance with the requirements in this
section.
(2) MONITORING
FREQUENCY FOR VOLATILE ORGANIC CONTAMINANTS. The frequency of monitoring to
determine compliance with the maximum contaminant level for volatile organic
contaminants specified in s.
NR 809.24 shall be conducted as follows:
(a)
Initial monitoring.
1. Water suppliers for new community public
water systems or community public water systems with new sources shall
demonstrate compliance with the MCLs listed under s.
NR 809.24 for volatile organic contaminants prior to
initiating water service.
2. Each
water supplier for a community or a non-transient non-community water system
shall take 4 consecutive quarterly samples for each VOC contaminant specified
in s.
NR 809.24, beginning with the first quarter a new source
goes into service.
3. If the
initial monitoring under subds. 1. and 2. for the VOC contaminants listed in s.
NR 809.24, did not detect any VOC contaminant, then the
water supplier shall take one sample annually.
(b)
Routine monitoring. Each
water supplier for a community or a non-transient non-community water system
shall take annual samples for VOC contaminants specified in s.
NR 809.24.
(c)
Reduced monitoring.
1. After a minimum of 3 years of annual
sampling, under par. (a) 3. or (b) the department may allow water suppliers for
groundwater systems with no previous detection of any VOC contaminant specified
in s.
NR 809.24 to take one sample during each three year
compliance period.
2. After a
minimum of 3 years of annual sampling, under par. (a) 3. or (b) the department
may allow water suppliers for surface water systems with no previous detection
of any VOC contaminant specified in s.
NR 809.24 to take one sample during each three year
compliance period, if the surface water system meets criteria specified by the
department.
(3) WAIVER REQUESTS. Each water supplier for
a community or a non-transient groundwater system which does not detect a VOC
contaminant specified in s.
NR 809.24 may apply to the department for a waiver from
the requirements of sub. (2) (c) after completing all of the initial monitoring
under sub. (2) (a). For the purposes of this section, detection is defined as
>0.0005 mg/l, except for vinyl chloride for which detection is defined as
>0.0002 mg/L. A water supplier for a groundwater system shall reapply for a
waiver for each compliance period. A waiver shall be effective for no more than
6 years or 2 compliance periods.
(4) WAIVER EVALUATION. The department may
grant a waiver from sub. (2) (c) after evaluating the following factors:
(a) Knowledge of previous use including
transport, storage or disposal of the contaminant within the watershed or zone
of influence of the public water system. If a determination by the department
reveals no previous use of the contaminant within zone of influence for the
well, a waiver may be granted.
(b)
If previous use of the contaminant is unknown or it has been used previously,
then the following factors shall be used to determine whether a waiver is
granted.
1. Previous analytical
results.
2. The proximity of the
public water system to potential point or non-point source of contamination.
Point sources include spills and leaks of chemicals at or near a water
treatment facility or at manufacturing, distribution or storage facilities, or
from hazardous and municipal waste landfills and other waste handling or
treatment facilities.
3. The
environmental persistence and transport of the contaminants.
4. The number of persons served by the public
water system and the proximity of a smaller public water system to a larger
public water system.
5. How well
the water source is protected against contamination. Groundwater systems shall
consider factors such as depth of the well, the type of soil and wellhead
protection.
(5) WAIVER CONDITIONS AND MONITORING
ASSESSMENTS. A water supplier for a groundwater system shall take one sample at
each entry point during the time the waiver is effective. As a condition of the
waiver under sub. (4), water supplier for the groundwater system shall update
the monitoring assessment considering the factors listed in sub. (4). Based on
this monitoring assessment, the department shall reconfirm that the public
water system is non-vulnerable. If the department does not make this
reconfirmation within 3 years of the initial determination or each subsequent
determination, then the waiver is invalidated and the public water system is
required to sample during each compliance period as specified in sub. (2)
(b).
(6) MONITORING FOR DETECTED
COMPOUNDS. If vinyl chloride is detected at a level exceeding 0.0002 mg/L, or
any other VOC contaminant specified in s.
NR 809.24 is detected at a level exceeding 0.0005 mg/1 in
any sample, then:
(a) The public water system
shall be monitored quarterly for all VOCs under s.
NR 809.24 at each sampling location which resulted in a
detection.
(b) The department may
decrease the quarterly monitoring requirement specified in par. (a) if the
department has determined that the public water system is reliably and
consistently below the MCL. In no case may the department make this
determination unless a groundwater system has been sampled a minimum of 2
quarters and a surface water system has been sampled a minimum of 4 quarters.
(c) If the department determines
that the public water system is reliably and consistently below the MCL, the
department may allow the system to be monitored annually. Public water systems
which are monitored annually shall be monitored during the quarter which
previously yielded the highest analytical result.
(d) Water suppliers for public water systems
which have 3 consecutive annual samples with no detection of a contaminant may
apply to the department for a waiver as specified in sub.
(3).
(7) MONITORING WHEN
AN MCL IS EXCEEDED. Additional monitoring for volatile organic contaminants
shall be required as follows in order to maintain compliance.
(a) If a VOC contaminant specified in s.
NR 809.24 is detected at a level exceeding the MCL in any
sample, then the water supplier shall begin to take quarterly samples at each
entry point which exceeded a MCL.
(b) Water suppliers for public water systems
which exceed a MCL listed in s.
NR 809.24 shall be monitored quarterly. After a minimum
of 4 quarterly samples that show the public water system is back in compliance
and the department determines the public water system is reliably and
consistently below the MCL as specified in s.
NR 809.247(1), the water supplier for
the public water system shall be monitored at the frequency specified in sub.
(6) (c).
(8)
CONFIRMATION SAMPLES. The department may require a confirmation sample for
positive or negative results. The department may delete results of sampling
errors from any compliance calculation, or may require the collection of
additional samples to determine whether the result is or is not in error. When
a confirmation sample is required, the result shall be averaged with the first
sampling result and the average used for the compliance determination as
specified in s.
NR 809.247(1) (c)
(9) COMPOSITE SAMPLES. The department may
reduce the total number of samples a water supplier for a public water system
shall analyze by allowing the use of compositing. The following composite
sampling requirements shall be met:
(a)
Compositing may only be permitted for entry points within a single public water
system. Composite samples from a maximum of 5 entry points may be allowed, if
the detection limit of the method used for analysis is less than one-fifth of
the MCL.
(b) Compositing of samples
shall be done in the laboratory and analyzed within 14 days of sample
collection according to the procedures in s.
NR 809.243(1) Table E.
(c) If the concentration in the composite
sample is greater than 0.0002 mg/L for vinyl chloride or 0.0005mg/L for any
other contaminant listed under s.
NR 809.24, then a follow-up sample shall be taken and
analyzed for each contaminant detected within 14 days from each entry point
included in the composite.
(d) If
duplicates of the original sample taken from each sampling point used in the
composite are available, the water supplier may use these instead of
re-sampling. The duplicate shall be analyzed and the results reported to the
department within 14 days of collection.
(10) INCREASING MONITORING FREQUENCY. The
department may increase monitoring requirements if necessary to detect
contaminant variations within a public water system.
(11) DESIGNATION OF SAMPLING TIMES. Each
public water system shall be monitored during the month, quarter or year
designated by the department within each compliance period.
