This guidance addresses additional sampling requirements under the Ground Water Rule (40CFR 141.400). Please refer to the additional information sources (last question) for other requirements under this rule.
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- Does this replace my regular bacteria sampling?
No. The total coliform rule requires regular sampling in your distribution system. The new Ground Water Rule requires sampling of the source water prior to any storage or treatment.
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- Do I need special bottles to collect a source sample?
Yes. You must use the same sample bottles that you use for your regular bacteria samples. Note that these samples should be taken and handled the same as your other bacteria samples (< 10 degrees Celsius and processed within 30 hours of collection.)
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- Do I need a special analysis request form to go with my Ground Water Rule source samples?
Yes. A special form for these samples will be available linked to your Master Sampling Schedule.
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- I operate a seasonal facility. When should I do my Investigative Monitoring E. coli sampling?
As a seasonal system, you still need to collect six source water samples and have them analyzed for E. coli during the time that you are open and serving water. For example, if you are open May to October, collect one sample every month. If you are only open June to September, space out sampling to every two to three weeks.
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- I installed a chlorinator (or UV) as a precautionary measure only, or for pre-oxidation treatment (iron, arsenic, sulfide, etc). Do I still need to do six months of E. coli sampling?
Systems currently disinfecting may request a waiver from the six months of Investigative Monitoring requirements provided the following conditions are met:
- Installation of disinfection treatment occurred on or after January 1, 2006; and
- Prove three years of clean bacteria results prior to the installation of disinfection/oxidation.
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- How do I take a source sample if I have a tablet chlorinator at the wellhead?
Suspend chlorination, flush the well line until no residual is detected, collect the sample(s) for E. coli, and reinstate chlorination. Water flushed from the well line must be discharged to a dry area, at least 50 feet from any surface water such as a stream or wetland.
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- What if my well tests positive for E. coli?
The presence of fecal contamination such as E. coli is an acute health hazard, which may cause illness and even death in sensitive populations. Therefore, New Hampshire rules require that as soon as you receive a report from the laboratory indicating the presence of E. coli, and NO later than 24 hours from such a report, the water system owner must:
- Notify DES Drinking Water and Groundwater Bureau bacteria program at (603) 271-2542, AND fax copy of the lab results to us at (603) 271-3490.
- Notify your customers that all drinking water must be boiled for at least two minutes prior to consumption. DES will issue a Boil Water Order and provide you with detailed instructions on how to carry out the public notice. Note that large water systems may qualify for a localized boil order notice pending review and approval from Drinking Water and Groundwater Bureau.
- Follow the boil order and resampling instructions provided by DES. After the problem has been identified and corrected and two consecutive sets of clean samples have been submitted, DES will lift the Boil Order.
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- Can I use UV to meet 4-log (99.99%) disinfection?
No. UV cannot be approved at this time for 4-log virus inactivation as there is currently no protocol to validate UV at the required dosage of 186 mJ/cm2. 4-log virus inactivation may be achieved by chlorination, ozone or membrane filtration. However, UV can continue to be used to provide disinfection for total coliform bacteria as long as all other well construction, system maintenance, and operational issues have been addressed.
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- What’s next after I finish IM monitoring?
After December 1, 2009, all groundwater systems that do NOT treat to 4-log treatment will be triggered into sampling each well to test for E. coli after a hit in the routine bacteria sampling. Future actions will depend on whether the triggered sample is clean or not. As long as your samples show no E. coli, no additional sampling is required, aside from your routine bacteria samples, and you may continue with your existing treatment and/or operations the same as before the Ground Water Rule. Thus, it is important to use proper sampling techniques so that you don’t inadvertently contaminate your samples.
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