COLIFORM SITE SAMPLING PLAN

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COLIFORM SITE SAMPLING PLAN

• Gary Carlson
• Drinking Water Program
• U.S. EPA Region 8

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Coliform Site Sampling Plan

• Required under 40 CFR 141.21(a) for Public Water
  Systems (PWS)
• PWS either community or non-community system
  for the provision to the public of piped water
  for human consumption
• - at least 15 service connections, or
• - regularly serves an average of at least 25
  individuals daily at least 60 days out of the
  year

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Coliform Site Sampling Plan

• The goal of bacteriological sampling should be to
  achieve the highest probability of detecting any
  bacteriological contamination of the distribution
  system possible

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Coliform Site Sampling Plan

• PWS required to submit plan which is
  representative of water throughout the
  distribution system
• Distribution system is that part of the water
  system after collection, treatment, and storage
  of water, that is used to distribute water

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Coliform Site Sampling Plan

• Sampling location is generally at a service (any
  location receiving water from the distribution
  system).
• Sampling locations shown on site sampling plan
  are representative of the entire distribution
  system with no areas that are left unsampled over
  a period of time.

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Coliform Site Sampling Plan

• Samples should be taken from residences as well
  as from public and commercial locations.

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Coliform Site Sampling Plan

• Why is a site sampling plan required?
• - To ensure bacteriological samples are
  representative of the distribution system
• - A plan documents sampling sites for
  reference (sampler and regulator)
• - A site plan facilitates planning in case of
  contamination

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Coliform Site Sampling Plan

• A site sampling plan should include
• - An overall sketch or drawing of the entire
  distribution system, including storage and
  booster disinfection locations
• - Layout of distribution system lines (mains,
  laterals, and service connections)
• - Points of identification such as streets and
  residential addresses