As previously mentioned, 2019 was a bad year for coliform in the Prudence Island water supply. In July and August, coliform was detected in the distribution system, and in the Indian Spring #4 well, which supplies the majority of water consumed on Prudence in the summer.
In September, many more samples were positive, including in the Army Camp well, which supplies the remainder of Prudence Island’s water.
Clearly, there was systematic bacterial contamination. Whenever such problems occur, a Level 2 Assessment (L2A) is triggered. This is a fancy way of saying that someone has to come and look and try to establish the root cause of the problem.
In August 2019, Robert Ferrari of Northeast Water Solutions, Inc., performed L2A #6. The assessment found problems or associated action items:
- Pressure drops due to line breaks
- Well casing of Indian Spring #4 not properly seated, allowing groundwater intrusion
- Iron oxide fouling of the vent screens of Indian Springs #4
The report also contained 3 other action items which were unlikely to be related to the bacterial contamination.
Astute readers will notice that, thus far, no explanation was proposed for the positive coliform results on Army Camp well. L2A #8, performed by Rob Ferrari, found that the sampling tap had a potential “defect”, and additional corrective actions were proposed.
To summarize 2019, the two important corrective actions proposed to rectify the causes of 2019’s coliform contamination were repairs to the IS#4 well, and the repair of the sampling tap at Army Camp well. By May of 2020, these repairs were complete.
(To satisfy anyone interested in identifying the cause of every positive test result, there was a positive coliform sample on John Oldham Road in March, 2020, taken during a line repair. It is generally accepted that the sampling location was to blame.)
If these defects explained everything, we would be hoping for an uneventful 2020 summer and fall. Unfortunately, that is not what occurred.
Once again, in the 2020 season, coliform pervaded the system, including both water wells. This triggered L2A #10 (if you are wondering what happened to L2A #9, it was a mere process issue), in which it was observed that there are not backflow preventers on the wells. It seems that there will be an attempt to put backflow preventers on the wells themselves, perhaps on the assumption that contaminants entered the well because of backflow or backsiphonage, resulting in the positive well samples. It immediately occurs to me that this explanation is unsatisfactory for the following reasons:
- The well pump has a check valve in it, which would prevent this flow, unless said valve malfunctioned… and it would have had to occur to both wells to explain both positive samples
- The water that could have flowed back into the wells is our drinking water. A sufficient supply that wouldn’t defy gravity would have had to have come from the other well or Big Blue, and should be free of contaminants.
So we’re still searching for an explanation of how contamination got into the distribution system in large quantities, yet again. Once again, we’re searching for another mole to whack, another possible way for things too small to be seen to gain entrance to miles of aging pipes.
To be continued…