1989 Total Coliform Rule: Requirements and Rationale

1
1989 Total Coliform RuleRequirements and
Rationale

• Tom Grubbs
• EPA Office of Ground Water and Drinking Water
• June 13, 2007

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Purpose and Objectives

• Purpose
• To gain a common understanding of the basic TCR
  requirements and the rationale for those
  requirements
• To highlight which requirements may result in
  variations in implementation and the level of
  public health protection provided by the TCR
• Objectives
• Understand rationale and assumptions underlying
  key provisions of the current Total Coliform Rule
  and begin a discussion of how the rule is being
  implemented now and why and whether it is serving
  its intent
• Start to frame questions that might be addressed
  by the Advisory Committee, if constituted

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General Purpose of 1989 TCR

• Help ensure integrity of distribution system (DS)
  
• Indicate breaches in DS and possible fecal
  contamination
• Indicate effectiveness of treatment
• SWTR complements TCR by including treatment
  technique requirements and disinfection residual
  requirements in DS
• Disinfectant residuals measured at TC sample
  locations
• GWR will complement TCR when implemented
• 2006 GWR requires 1) source fecal indicator
  monitoring if TC detected in DS 2) corrective
  actions if fecal contamination is detected in
  source

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What is a Coliform?
Indicator Organisms indicate potential presence
of disease-causing organisms There are hundreds
of pathogens and many cannot be detected or are
expensive to measure
Total Coliform Ubiquitous in Ambient Environment
E. coli
Pathogenic E. coli Some of which are not
detectable by Total Coliform detection methods
Fecal Coliform Fecal Coliform or E. coli Fecal
Contamination
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Basis for Indicator Framework

• Total Coliform as an Indicator
• Advantages
• Total coliforms (TC) are numerous in environment
  and serve as general Indicator of a breach in
  water system integrity
• TC are a conservative indicator of potential
  contamination
• Provides basis for investigation
• Analytical methods are common, simple, and low
  cost
• Fecal indicators, i.e. fecal coliform and E.
  coli, can be examined and analyzed directly from
  TC samples
• Indication of fecal contamination shows more
  immediate concerns and requires prompt
  investigation
• Limitations
• TC provides no definitive linkage to public
  health risk
• Absence of TC does not mean absence of risk
• TC may grow and release in distribution systems
  (biofilm) and mask indicator value (i.e., dont
  know if TC positive is coming from either DS
  breach or biofilm)

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1989 TCR Components

• Routine monitoring and sample siting plans
• Repeat monitoring routine/repeat samples
• Analytical methods
• Non-acute (monthly)/acute Maximum Contaminant
  Level (MCL)
• Public Notification
• State response/involvement with positive samples,
  MCL violations

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Determining Coliform Maximum Contaminant Level
Violations
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Routine Monitoring Requirements (1)

• Systems must develop written sample siting plans
• Representative of DS
• Subject to State review/revision
• Presence/absence (rather than concentration
  measure)
• Test all TC for fecal coliform or E. coli
• Number of samples are based on population served
  and system type
• Sanitary survey for systems taking lt 5
  samples/month

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Routine Monitoring (2)

• Sampling frequency based on population served
• Total of 34 population categories, for example
• lt 4900 people 5 samples/month (conditions for
  lower frequency allowed - see next slide)
• 8,501-12,900 10 samples/month
• 96,001-130,000 100 samples/month
• 450,001-600,000 210 samples/month
• gt3,960,001 480 samples/month

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Special Routine Monitoring Provisions for
Systems Serving lt 4,100 (all based on State
approval)

• Systems may take lt 5 samples/month if systems
  have periodic sanitary surveys (e.g., lt1000 one
  sample/month, 3301-4100 4 samples/month)
• Monthly monitoring for NCWS serving lt 1000 people
• Systems may collect all samples on a single day
  if taken from different sites

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Special Routine Monitoring Provisions for
Systems Serving lt 4,100 (all based on State
approval)

• States may allow reduced monitoring for GWS free
  of sanitary survey defects unlikely to be
  contaminated
• CWS serving lt 1000 people may have sampling
  reduced to quarterly
• NCWS serving lt 1000 people may have sampling
  reduced to annual
• Systems must collect gt 5 samples in month
  following a total coliform-positive sample
• Unless State performs site visit and determines
  that additional sampling and/or correction is not
  needed or
• State determines why the total coliform sample
  was positive and establishes that the system has
  corrected or will correct the problem

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Rationale for Routine Monitoring Provisions

• Written sampling plan by system with approval by
  State to ensure sample sites are representative
  while recognizing access limitations
• Ongoing sampling on regular basis needed to
  assess potential for acute risk
• More samples for larger systems to help achieve
  representativeness
• Simplified pre 1989 population-based monitoring
  approach by reducing number of population size
  categories from 84 to 34
• Cost saving provisions for systems lt 1,000 people
• Reduced monitoring (lt1/month) allowed where State
  determines risk and potential affected population
  are low
• States have knowledge on least vulnerable GWS
• Increased monitoring required to at least five
  samples during month after a TC sample to
  increase confidence that there is absence of
  contamination

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TCR Repeat Monitoring Requirements

• If any ROUTINE or REPEAT sample is total
  coliform-positive, the system
• Must test the total coliform-positive sample for
  either E. coli or fecal coliforms
• Must collect (another) set of REPEAT samples
  unless the MCL has already been violated and the
  system has notified the State

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TCR Repeat Monitoring Requirements

• Within 24 hours of learning of a total
  coliform-positive ROUTINE or REPEAT sample,
  system must collect at least 3 REPEAT samples and
  test for TC
• Required to sample original tap, within 5 service
  connections upstream and downstream of original
  tap
• If the total coliform-positive sample occurs at
  the end of the distribution system, the State may
  waive the /- 5 service connection requirement
  and take repeat samples from the same tap
• Systems that collect 1 ROUTINE per month must
  collect a 4th REPEAT sample at a location of
  systems choice
• State may grant exceptions for 24 hour
  requirement

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Rationale for Repeat Monitoring

• Repeat monitoring required within 24 hours to
  increase likelihood of capturing contamination
  event
• States may grant exceptions based on feasibility
  or diagnostic determination by State
• Repeat samples required to assess extent/degree
  of contamination
• One extra repeat sample for systems serving
  lt1,000 people to compensate for lower monthly
  routine sampling requirements
• At least five samples during month after a TC
  sample
• To help ensure higher likelihood that systems
  with low routine monitoring frequency are no
  longer contaminated
• State may increase of samples to assess
  corrective action and current microbial quality
  of water

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Non-Acute MCL

• The results of ROUTINE and REPEAT samples are
  used to calculate compliance
• Compliance determined each month a system serves
  water to the public or each month that sampling
  occurs (for those systems on reduced monitoring)
• System in compliance if
• 0-1 total coliform-positive samples (lt40
  samples/mo)
• lt5.0 total coliform-positive samples (40
  samples/mo)

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Acute MCL

• System is in violation if a routine sample is
  total coliform-positive AND one or more repeat
  samples are total coliform-positive AND any of
  the total coliform-positive samples are also
  positive for either fecal coliform or E. coli
• The results of ROUTINE and REPEAT TC and FC/EC
  samples are used to calculate compliance
• System can have an acute MCL violation without an
  non-acute violation and vice versa

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MCL Compliance Rationale (1)

• Monthly determinations address concerns about
  long-term operation, distribution system
  integrity, and acute health effects
• TC occurrence used to define non-acute MCL
  violation since it indicates a pathway of
  potential fecal contamination even though the
  fecal contamination may not be present
• 5 number based on needing at least 2 positives
  out of 40 samples to have a statistically
  significant finding
• To compensate for smaller numbers of samples
  being collected in small systems, 2 out of 5
  samples must be positive for compliance
  determination based on repeat sampling

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MCL Compliance Rationale (2)

• Fecal coliform or E.coli occurrence used to
  define acute violation since many pathogens are
  of direct fecal origin
• Acute violation based on at least one fecal/E.
  coli positive and two TC positives (routine and
  repeat) because of potential sample measurement
  error and remediation cost implication
• Concern for acute risk to public addressed by
  system being required to immediately notify
  State State can then determine what action is
  necessary

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MCL Compliance Rationale (3)

• Measurement for fecal coliform (FC) or E. coli
  for acute violation detremination
• Allows for FC because it is more protective than
  E. coli and costs less (at time of promulgation)
• Allows for E. coli to better target potential
  presence of human pathogen
• Note Since promulgation in 1989 low cost methods
  for EC determination have been developed (see
  methods discussion)

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Analytical Methods

• Total coliform (100 mL analyzed for
  presence/absence)
• 1989 methods - membrane filter technique,
  multiple tube fermentation, presence-absence
  coliform test, Minimal medium ONPG-MUG (Colilert)
• Since 1989, six additional methods added
• Fecal coliform method specifies how to analyze
  TC-positive sample for fecal coliform
• E. coli 10 methods listed after 1989
• Invalidation criteria included in rule

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Analytical Methods Rationale

• Total coliform
• Standardized volume analyzed to ensure uniform
  sensitivity of measurement
• Presence/absence (rather than pre 1989
  concentration based standard) assumed more
  relevant indicator for potential contamination
  occurrence
• Simplified interpretation of data and follow up
• Added new methods as developed
• Fecal coliform/E. coli Allowed for flexibility
  and development of new and lest costly methods
  for E. coli
• Invalidation criteria needed to control previous
  widespread practice of invalidating routine total
  coliform-positive samples when repeat samples
  were TC-negative

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Public Notification and Reporting Requirements

• Monthly MCL violation
• Non Acute - Notify public per Public Notification
  Rule Tier 2 Public Notification (within 30-days
  of learning of a violation)
• Acute - Notify public per Public Notification
  Rule Tier 1 Public Notification (within 24
  hours)
• Systems with routine or repeat samples that are
  fecal coliform or E.coli positive (regardless of
  violation determination) must notify State by the
  end of the day they are notified of the result
• Monitoring violations must be reported to the
  State within 10 days after the system discovers
  the violation

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Public Notification and Reporting Requirements
Rationale

• Monthly MCL violation
• Alerts consumer of potential contamination to
  system
• Non-acute violation does not require immediate
  notification since no immediate evidence of fecal
  contamination
• Acute MCL violation requires short term
  notification since fecal contamination indicates
  that pathogens posing acute risk may be present
• Systems with routine or repeat samples that are
  fecal coliform or E.coli positive notify State by
  the end of the day they are notified of the
  result to allow for appropriate State action
• Monitoring violations generally seen as less
  significant, so more time to report

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State Involvement

• States must approve systems taking lt 5 samples
  per month if they undergo periodic sanitary
  surveys
• At least every five years (or every 10 years if
  it is a NCWS using protected and disinfected GW
  as determined by the State)
• Note under IESWTR and GWR, sanitary surveys
  required for all systems within 3 years for CWS
  (up to 5 years for GWS if certain conditions are
  met) and 5 years for NCWS
• Notification of FC and EC by system before
  violation determination
• Violation notification by system to State much
  quicker than for other rules to recognize
  potential for acute risk

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State Involvement Rationale

• Rationale for sanitary survey provisions
• Provides means for lowering monitoring costs to
  small systems while helping ensure they are still
  adequately protected with minimal monitoring
  provisions
• Systems notify State early to allow for
  system-specific responses to potentially acute
  pathogens
• State can take into account system knowledge