Coliform Sample Siting Plan

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Coliform Sample Siting Plan

• Ken Morin, P.E.
• BLM
• National Applied Resource Sciences Center

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Coliform Sampling40 CFR 141.21(a)(1)

• Routine monitoring. Public water systems must
  collect total coliform samples at sites which are
  representative of the water throughout the
  distribution system according to a written sample
  siting plan.
• These plans are subject to State review and
  revision.

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Coliform Sample Siting Plan

• Plan elements are not defined in the regulations.
• Very brief guidance is available from some
  States.
• New BLM Drinking Water Manual will provided
  detailed requirements.

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Recommended Elements in Sample Siting Plan

• Map showing the following
• Distribution system
• Storage
• Treatment
• Taps
• Identification name/number for each tap

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Recommended Elements in Sample Siting Plan
continued

• Break Distribution System into Zones if it is
  Looped or has Different Pressure Zones.
• Alternate Samples Between Zones
• Focus Samples At
• Dead ends
• Heaviest use taps

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Recommended Elements in Sample Siting Plan
continued

• Routine Sample Schedule
• Sample to be taken early in month/quarter
• Quarter defined as Jan. - March, etc.
• Sampling Procedures
• How to Fill Out Lab Form

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Recommended Elements in Sample Siting Plan
continued

• Description of Sampling that Must be Done if a
  Routine Sample Tests Positive 141.21(b)(2)
• Do Not Disinfect Following a Positive Routine
  Sample
• Actions to be Taken if a Repeat Sample Tests
  Positive 141.21(b)(4)

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Recommended Elements in Sample Siting Plan
continued

• Increased Routine Samples Must be Taken
  Regardless of Whether Any Repeat Sample Tests
  Positive 141.21(b)(5)
• Public Notification Requirements 141.21(g) and
  141.32
• Two positives in one month exceeds MCL
  141.63(a)(2)
• Failure to monitor for coliforms 141.21(g)(2)

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Recommended Elements in Sample Siting Plan
continued

• Disinfection Procedures for
• Well
• Storage tank
• Distribution system

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Recommended Elements in Sample Siting Plan
continued

• Water System Startup Procedures
• Opening and closing which valves
• Disinfection procedures for storage and
  distribution
• Satisfactory coliform result prior to opening
• Operational Testing Frequency

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Recommended Elements in Sample Siting Plan
continued

• Water System Shutdown Procedures
• Opening and closing which valves
• Draining distribution and storage
• Equipment to be brought back from the field

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Recommended Elements in Sample Siting Plan
concluded

• Recordkeeping Requirements
• State Reporting Requirements for
• Positive repeat coliform result
• Public notification postings
• Operational testing results
• State Certification Requirements

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Sampling Following a Positive - 1 Tap

• One Repeat Sample 141.21(b)(3)
• Four 100 mL samples
• first taken early in morning
• second taken 2 or 3 hours later
• third taken 2 or 3 hours after second
• fourth taken 2 or 3 hours after third
• Refrigerate or ice samples awaiting shipment to
  lab

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Sampling Following a Positive - 1 Tap concluded

• Five Increased Routine Samples 141.21(b)(5)
• Routine samples must be taken in month following
  the positive 40 CFR
  141.21(b)(5)
• Routine samples must be taken at regular time
  intervals throughout the month 141.21(a)(4)
• Therefore a sample must be taken every 5 or 6 days

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Sampling Following a Positive - 2 Taps

• Four Repeat Samples 141.21(b)(2)
• One sample from each tap taken early in morning
• One sample from each tap taken as late as
  possible the same day
• Repeat samples must be taken on the same day
  141.21(b)(3)

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Sampling Following a Positive - 2 Taps concluded

• Five Increased Routine Samples 141.21(b)(5)
• Routine samples must be taken at regular time
  intervals throughout the month 141.21(a)(4)
• one sample from each tap at the beginning of the
  month
• one sample from each tap at the middle
• one sample from original positive tap at the end
  of the month

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Sampling Following a Positive - 3 Taps

• Four Repeat Samples 141.21(b)(2)
• One sample from each tap taken early in morning
• One sample from the original positive tap taken
  as late as possible the same day
• Repeat samples must be taken on the same day
  141.21(b)(3)

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Sampling Following a Positive - 3 Taps concluded

• Five Increased Routine Samples 141.21(b)(5)
• Routine samples must be taken at regular time
  intervals throughout the month 141.21(a)(4)
• One sample from each tap at the beginning of the
  month
• One sample from original positive tap and any
  other tap at the middle of the month

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Sampling Following a Positive - 4 Taps

• Four Repeat Samples 141.21(b)(2)
• One sample from each tap
• Repeat samples must be taken on the same day
  141.21(b)(3)
• Samples are to be taken within 24 hours of
  notification of positive 141.21(b)(1)

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Sampling Following a Positive - 4 Taps concluded

• Five Increased Routine Samples 141.21(b)(5)
• Routine samples must be taken at regular time
  intervals throughout the month 141.21(a)(4)
• One sample from each tap at the beginning of the
  month
• One sample from original positive tap at the
  middle of the month

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Sampling Following a Positive - 5 to 7 Taps

• Four Repeat Samples 141.21(b)(2)
• One sample from original positive tap
• Other samples from any three different taps
• Repeat samples must be taken on the same day
  141.21(b)(3)
• Samples are to be taken within 24 hours of
  notification of positive 141.21(b)(1)

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Sampling Following a Positive - 5 to 7 Taps
concld

• Five Increased Routine Samples 141.21(b)(5)
• Systems that serve lt 4,900 persons may collect
  all required samples on a single day if they are
  taken from different taps 141.21(a)(4)
• One sample from original positive tap at the
  beginning of the month
• Four other samples any four different taps

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Sampling Following a Positive 8 or More Taps

• Four Repeat Samples to be Taken per 141.21(b)(2)
• Five Increased Routine Samples Taken From 5
  Different Taps on the Same Day 141.21(b)(5)
  (a)(4)
• One of the samples should be taken at the
  original positive tap

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Repeat Sample Collection

• Four Repeat Samples Must be Taken 141.21(b)(1)
• Samples to be Taken Within 24 Hours of Positive
  Result Notification 141.21(b)(1)
• Repeat Sample Locations 141.21(b)(2)
• All Repeats to be Taken on Same Day 141.21(b)(3)

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Repeat Sample Collection

• If Any Repeat Tests Positive Another Set of
  Repeats Must be Taken 141.21(b)(4) or
• Notify the State that the Coliform MCL has been
  Violated per 141.63 141.21(b)(4)
• State May Still Require Additional Sampling

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Repeat Sample Collection

• System with One Tap May Collect One Repeat Sample
  Each Day for Four Days or
• Collect a Single 400 mL Sample 141.21(b)(3)
• This should be a composite sample

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Increased Routine Sample Collection

• Five Increased Routine Samples Must be Taken in
  the Month Following a Positive Sample
  141.21(b)(5)
• Collect Samples at Regular Time Intervals
  Throughout the Month 141.21(a)(4)
• Except Systems that Serve lt 4,900 Persons
• May collect all required samples on a single day
  if they are taken from different taps
  141.21(a)(4)