United States
Environmental Protection
Agency
Office of Water
4601
EPA 570/9-91-026FS
January 1995
EPA The Phase I Rule
"VOCs have been
found in about
20 percent of the
nation's water
supplies."
The Phase I Rule was published in the Federal Register on Wednesday, July 8, 1987.
It became effective on January 9, 1989. This rule, also called the Volatile Organic
Chemicals Rule or the VOC Rule, set water quality standards for 8 VOCs and required
all Community and Non-Transient, Non-Community water systems to monitor for and, if
necessary, treat their supplies for these chemicals. VOC monitoring requirements were
revised on January 30, 1991 to synchronize them with other VOC monitoring require-
ments established in the Phase II Rule. Monitoring requirements for Phase I VOCs were
synchronized under the Standardized Monitoring Framework, a monitoring framework
established by Phase II in January 1, 1991. Monitoring under this framework started in
January 1, 1993.
VOCs are among the most widely used chemicals. They are usually found in
groundwater, where they may remain for long periods of time. VOCs have been found in
about 20 percent of the nation's water supplies.
Water Quality Standards
Maximum Contaminant Levels
VOC
MCL (mg/L)
Benzene 0.005
Carbon Tetrachloride 0.005
1,2-Dichloroethane 0.005
Para-Dichlorobenzene 0.075
1,1-Dichloroethylene 0.007
1,1,1-Trichloroethane 0.20
Trichloroethylene 0.005
Vinyl Chloride 0.002
mg/L = milligrams per liter.
Maximum Contaminant Level Goals (MCLGs): For each chemical, EPA
has set a non-enforceable health goal which water systems should try to
achieve. Water containing a chemical in an amount equal to or below its MCLG
is not expected to cause any health problems, even over a lifetime of drinking
this water.
Maximum Contaminant Levels (MCLs): MCLs for each chemical are set
as close to their MCLGs as is technically and economically feasible, and are
protective of public health.
Table 1. Monitoring Dates
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
Previously, monitoring requirements for the eight VOCs in this rule were
phased-in by system size, with monitoring beginning according to Table 1. On
January 1, 1993, monitoring requirements were synchronized with the
Standardized Monitoring Framework, which was developed to simplify monitoring for all
present and upcoming regulated chemicals. Table 2 presents the monitoring require-
ments under the Standardized Framework.
• Sampling - Ground water systems must sample at entry points to the
distribution system which are representative of each well after any applica-
tion 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 lab.
• Initial sampling frequency - All systems must take four consecutive
quarterly samples in the initial compliance period, unless there are prior
sample results taken between January 1, 1988 amd December 31, 1992 that
may be "grandfathered" for t^is 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.
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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 the
VOCs. For VOCs, the trigger level is detection above a concentration of 0.0005
milligrams per liter (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 susceptability waiver based on the occurrence of VOCs in initial samples
and either the use of the VOC in that area or on the results of a vulnerability
assessment.
Unregulated contaminant monitoring - Under the Phase I Rule, systems were
required to monitor for 51 other contaminants, using the same starting dates given
in Table 1. Many of these "unregulated" contaminants have now become regluated;
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.
For More Information
Call the Safe Drinking Water Hotline
at 1-800-426-4791
Table 2.
Current Standardized VOC Monitoring Frequencies
Source
Surface
Ground
Source
Surface
Ground
Surface
Ground
Surface
Ground
Size(Conn.)
N/A
N/A
>500
<500
>500
<500
N/A
N/A
Waiver
no
no
Waiver
yes
yes
no
no
no
no
no
no
Monitoring Frequency
4 quarterly samples
4 quarterly samples
Occurrence
N/A
no detect
no detect
no detect
no detect
no detect
detect
detect
Monitoring Frequency
State Discretion
1 sample/6 years
1 sample/ year
1 sample/ year
1 sample/ year :
1 sample/ year l
quarterly 2
quarterly 2
NOTES:
1 State may reduce to 1 sample during each 3 year compliance period after 3 years. 2 State may reduce to annual after "reliably and consistently" less than MCL.
Variances and Exemptions
Systems which cannot meet the MCLs for VOCs are eligible for variances only if the
system has installed the best treatment available technology, defined for these chemicals
in 40 CFR 141.61. Other factors, including health concerns, the installation of POU/POE
devices or provsion of bottled water, also must be considered before a variance is granted.
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