| Table 1. Monitoring Phase I Schedule
|
System Size
(Population) |
Monitoring to begin
no later than |
| Over 10,000 | January 1, 1988 |
| 3,300 to 10,000 | January 1, 1989 |
| Less than 3,300 | January 1, 1991 |
Monitoring requirements for the eight VOCs in this rule were phased in by system size according to the schedule in Table 1. On January 1, 1993, the Phase II Rule synchronized the monitoring requirements with the introduction of the Standarized Monitoring Framework, which was developed to standardize the monitoring schedule for chemicals currently regulated and those expected to be regulated.
- Sampling - Ground water systems must sample at entry points
to the distribution system which are representative of each well after any
application of treatment. Surface water systems shall sample at points within
the distribution system which are representative of each source or at entry
points to the distribution system after any application of treatment. Samples
must be analyzed by a State-certified laboratory.
- Initial sampling frequency - All systems must take four
consecutive quarterly samples in the initial compliance period, unless there
were prior samples taken between January 1, 1998 and December 31, 1992
that may be "grandfathered" for this requirement. Under 40 CFR 141.62(e)(2)
States must designate the year in which each system will perform its initial
sampling. If the State allows the system to use grandfathered data, the
system must not have detected any results at or above 0.0005 mg/L. If this
is the case, the system shall begin annual sampling in 1993.
- Repeat sampling frequency - If a system does not detect VOCs
in any initial samples, then the State may allow a system to decrease its
monitoring frequency beginning in the second compliance period as described
below.
- Ground water systems must take at least one sample annually.
After 3 years of annual sampling with no detection, sampling may be further
reduced to once every 3 years.
- Surface water systems must sample annually
- Trigger to increase monitoring - If VOCs are detected or if
the MCL is exceeded in any initial or repeat sample, the system must resume
quarterly monitoring for VOCs. For VOCs, the trigger level is detection
above a concentration of 0.0005 mg/L. The system must begin quarterly
sampling starting in the next calendar quarter until the State determines the
system is "reliably and consistently below the MCL."
- Vulnerability Assessments - Monitoring may also be reduced
if the system obtains a use or susceptibility waiver. This waiver is based on the occurrence of VOCs in initial samples and the extent to which the VOC was used in that area, or the extent to which local geology and soils are vulnerable to contaminants moving into the ground water. This is determined by conducting a vulnerability assessment.
- Unregulated contaminant monitoring - Under the Phase I Rule,
systems are required to monitor for 51 other contaminants, using the same
starting dates given in Table 1. Since passage of the Phase I Rule, many of these "unregulated" contaminants have become regulated. Only 14 of the original 51 are still "unregulated." No MCLs have been set for these contaminants, and systems only need to report the results of this monitoring to the State. Systems must repeat their sampling for unregulated contaminants every 5 years.
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