UNITED STATES ENVIRONMENTAL AGENCY
WSG58
Date Signed: December 19, 1990
MEMORANDUM
SUBJECT: Final SNC Definition for the TCR and Proposed SNC
Definition for the SWTR
FROM: Connie Bosnia, Chief (signed by Connie Bosnia)
Drinking Water Branch, ODW (WH-55OE)
TO: Drinking Water/Ground Water Protection Branch Chiefs
Regions I - X
During the Drinking Water Branch Chief's Meeting, held during the week of December
3, 1990, agreement was reached on the SNC definition for the Total Coliform Rule (TCR). We
could not come to a consensus on the SNC definition for the Surface Water Treatment Rule
(SWTR). However, the discussions at the meeting prompted us to propose the approach in this
memo.
Final SNC Definition for the TCR:
The definition for SNCs for the TCR is provided as Attachment 1. Implementation of this
definition will be done using a transition plan that will phase-in the new definition over two
quarters. For the first calendar quarter of 1991, (data due to FRDS June 1, 1991, SNC list run
July 1, 1991), two SNC lists will be generated. The first SNC list will use the current definition.
The States and Regions will be required to take timely and appropriate actions against the
systems on this list. A second SNC list will be run using the new definition to give States and the
Regions an idea of the impact that the new SNC definition will have. For the second calendar
quarter of 1991, (data due to FRDS September 1, 1991, SNC list run October 1, 1991), the new
SNC definition will be used.
For the reporting periods beginning January 1991, April 1991 and July 1991, SNC
determination (using the new SNC definition) will be done using violation data from the new
TCR and the current coliform rule. For the purpose of SNC determination, violations of the
current coliform rule will translate to violations of the new TCR as follows. Monitoring and
Reporting (M&R) violations, Major and Minor, from the current rule will count as Major
Routine and Minor Routine. MCL violations of the current rule will count as Monthly MCL
violations.
For the reporting period beginning January 1991, the current SNC definition will be used
with violation data from the current coliform rule and the new TCR. For the purpose of SNC
determination, violations of the new TCR will translate to violations of the current coliform rule
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as follows. Minor Repeat and Minor Routine M&R violations from the new TCR will count as
Minor M&R violations. Major Repeat and Major Routine M&R violations from the new TCR
will count as Major M&R violations. MCL violations under the new TCR consist of Monthly and
Acute violations. Both will count simply as MCL violations.
In discussions on the new SNC definition, questions were raised as to how to treat a PWS
which monitors at different frequencies during a one year period. Currently, if a system on
quarterly monitoring has a violation and the State then elects to put that system on monthly
monitoring, if the system incurs another violation, our policy dictates that the system becomes an
SNC. This is because we currently use the most stringent criteria (the quarterly criteria) for SNC
determination.
As of January 1, 1991, we will change the above approach because we believe it does not
take into account the added protection to public health provided by an increased monitoring
frequency. Starting January 1, 1991, the "current monitoring frequency" rather than the
"monitoring frequency with the most stringent SNC criteria" will be used in SNC determination.
In the above case, then, the system would be allowed 4 MCL violations because it would be
evaluated under the criteria for systems on monthly monitoring.
Proposed SNC Definition for the SWTR:
As stated earlier, during the Branch Chief's Meeting we were unable to come to a
consensus on a final SNC definition for the SWTR. (Attachment 2 is the proposed SNC
definition for the SWTR.) Disagreement centered around unfiltered systems. Specifically, the
Branch Chiefs wanted more discussion of the method(s) we will use to ensure that unfiltered
systems that are required to filter install filtration in a timely manner. In this memorandum we
propose an enforcement protocol to deal with unfiltered systems that are required to install
filtration.
We believe that the SWTR is high priority and that we should aggressively implement
and enforce its requirements. Our SNC definition should reflect this priority. Moreover, once we
identify a system as an SNC, it must be addressed in a timely and appropriate manner. Our
guidance on timely and appropriate actions states that systems identified as SNCs must be
addressed by appropriate actions within six months of becoming SNCs. Timely and appropriate
actions consist of State or Federal Administrative Orders AOs, State or Federal Civil Referrals,
criminal cases, or Bilateral Compliance Agreements (BCAs). BCAs must be signed by both
parties and must include a compliance schedule.
The proposed SWTR SNC definition states that if a PWS is unfiltered and required to
filter, and fails to install filtration by June 29, 1993 or within 18 months of the State
determination that filtration is required (whichever is later) the PWS becomes a SNC. However,
if an appropriate action is in place by the deadline for the installation of filtration, the system will
be listed as an addressed SNC. Regions and States should monitor systems" progress towards
compliance with the SWTR.
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We believe that it is appropriate for systems of different sizes to be addressed by different
appropriate actions. For example, we do not believe it is appropriate to address a major system
with a BCA. While BCAs are appropriate actions, they are not independently enforceable.
Therefore, States and Regions should not use BCAs for systems that serve more than 10,000
persons. However, smaller systems can be addressed by any appropriate action.
Implementing the SWTR is high priority and SWTR SNCs must be addressed as soon as
possible to send a message to the States and the systems. Informing States and systems of our
enforcement priorities will enable them to better use scarce resources.
Please comment on the SNC definition for the SWTR by January 11, 1991. We are
especially concerned that we receive your input on the enforcement approach we propose for
unfiltered surface water systems that are required to filter. We will develop a detailed policy on
the issues in this memorandum that will include guidance to the Regions.
Please call Clive Davies at (202) 260-1421 or Betsy Devlin at (202) 564-2245 with any
questions.
Attachments
cc: Office of Enforcement (Kathy Summerlee)
Bob Blanco
PWSS Enforcement Coordinators, Regions I - X
Wade Miller (ASDWA)
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REVISED BREAKDOWN OF M/R VIOLATIONS - TCR
ROUTINE:
Major: A system that fails to take all (takes no samples) of the required routine samples
per compliance period.
Minor: A system that fails to take some (but not all) of the required routine samples in a
compliance period.
REPEAT:
Major: A system that does not conduct follow up monitoring after a total
coliform-positive sample (i.e., takes no repeat samples and/or conducts no
speciation for fecal/E. coli.
Minor: A system that fails to take some of the required repeat samples and/or a system
that fails to speciate at least one (but not all) total coliform-positive samples for
fecal/E. coli).
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Attachment 1 - TCR SNC Definition
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PROPOSED SNC DEFINITION FOR THE TCR
SNCs (Tier 1):
• Systems on Monthly Monitoring:
a system that has 4 or more combined MCL or major repeat M/R
violations in any 12 consecutive months,
-or-
a system that has 6 or more combined MCL or major repeat or major
routine M/R violations in any 12 consecutive months,
-or-
a system that has 10 or more combined MCL or M/R violations (major or
minor) in any 12 consecutive month,
• Systems on Quarterly Monitoring:
a system that has 3 or more combined MCL and/or major repeat or major
routine M/R violations in any 4 consecutive quarters,
• Systems on Annual Monitoring:
a system that has 2 or more MCL and/or major repeat or major routine
M/R violations in any 2 consecutive years,
Tier 2:
• Systems on Monthly Monitoring:
a system that has 2 or 3 combined MCL or major repeat M/R violations in
any 12 consecutive months,
-or-
a system that has 4 or 5 combined MCL or major repeat or major routine
M/R violations in any 12 consecutive months,
-or-
a system that has 5 to 9 combined MCL or any M/R violations (major or
minor) in any 12 consecutive months,
Attachment 1 - TCR SNC Definition
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• Systems on Quarterly Monitoring:
a system that has 1 or 2 combined MCL and/or major repeat or major
routine M/R violations in any 4 consecutive quarters,
• Systems on Annual Monitoring:
a system that has any violation of the TCR major repeat or major routine
M/R requirements and/or MCL,
Tier 3:
• All other MCL and/or M/R violators (for all monitoring frequencies).
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Draft -for Review Purposes Only
Attachment 2 - SWTR SNC Definition
PROPOSED SNC DEFINITION FOR THE SWTR
Unfiltered Systems
SNCs (Tier 1):
• A system informed of the requirement to filter before Jan., 1992 that does not
install filtration by June 29, 1993,
-or-
• A system informed of the requirement to filter after December 1991 that does not
install filtration within 18 months of being informed that filtration is required,
-or-
• A system that has 3 or more M/R violations in any 12 consecutive months,
Tier 2:
• A system that has 2 M/R violations in any 12 consecutive months, Tier 3:
• All other violators.
Filtered Systems
SNCs (Tier 1):
• A system that has 4 or more treatment technique violations in any 12 consecutive
months,
-or-
• A system that has a combination of 6 violations including treatment technique
violations and M/R violations in any 12 consecutive months,
Tier 2:
A system that has 2 or 3 treatment technique violations in any 12 consecutive
months,
-or-
A system that has a combination of 3, 4 or 5 violations including treatment
technique violations and M/R violations in any 12 consecutive months,
Tier 3:
• All other violators.
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