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Appendix C

Protocol for boxing in pollution sources using bacterial loading and optical brightener sampling

Bacterial loading

Optical brightener

Sampling period

Preferred course of action

high

low

pos

neg

wet

dry

Yes

Yes

Yes

Most likely the result of failing septic systems. Follow the dry weather flow and box in using O.B. and bacterial loading.

Yes

Yes

Yes

Could be caused either by humans or other warm blooded animals. Follow the dry weather flow and box in using bacterial loading

Yes

Yes

Yes

Inconclusive, because there are so many potential sources. Wait and gather dry weather data.

Yes

Yes

Yes

Most likely the result of marginal or failing septic systems. Either wait to gather dry weather data, or box in using O.B. and bacterial loading

Yes

Yes

Yes

Most likely the result of marginal septic systems. Follow the dry weather flow and box in using O.B. sampling. Because these systems are more likely to fail during periods of high ground water, volume flows and rainfall events should be closely monitored to try and pick up episodic slugs of bacterial loading

Yes

Yes

Yes

No evidence of pollution at that time. Wait and gather wet weather data and continue periodic monitoring.

Yes

Yes

Yes

No evidence of pollution at that time. Continue periodic monitoring.

Yes

Yes

Yes

Most likely the result of marginal or failing septic systems. Either wait to gather dry weather data, or box in using O.B. sampling

Yes

High bacterial loading in the summer and not in the winter usually indicates either lessened seasonal groundwater dilution and/or increased usage by humans or other warm blooded animals during the summer months

Yes

High bacterial loading in the winter during periods of high groundwater and little or no bacterial loading in the summer during periods of low groundwater usually indicates inadequate separation of groundwater from septic systems. Box in using O.B. and bacterial loading during periods of high groundwater.

It should be noted that the term “marginal septic systems” refers not only to those septic systems that just partially treat waste water, but also to those septic systems that can only treat human waste by the separation and then improper disposal of grey water.

Next: Appendix D