# Presentation: 659772

## Coliform Sample Siting Plan

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

## Coliform Sampling40 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.

## 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.

## Recommended Elements in Sample Siting Plan 

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

## Slide 5

## 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

## 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

## 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)]

## 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)]

## Recommended Elements in Sample Siting Plan [continued]

- Disinfection Procedures for:
- Well
- Storage tank
- Distribution system

## 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

## 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

## Slide 13

## 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

## Slide 15

## 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

## Slide 17

## 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

## 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)]

## 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

## 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)]

## 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

## 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)]

## 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

## 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)]

## Sampling Following a Positive - 5 to 7 Taps [concl’d]

- Five “Increased” Routine Samples [141.21(b)(5)]
- Systems that serve < 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

## 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

## 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)]

## 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

## 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

## “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 < 4,900 Persons
- May collect all required samples on a single day if they are taken from different taps [141.21(a)(4)]