6.1.3 Sample Collection and Analysis
If flow is present during a dry weather outfall inspection, a sample will be collected and analyzed for the
required permit parameters’. The general procedure for collection of outfall samples is as follows:
1. Fill out all sample information on sample bottles and field sheets
Put on protective gloves (nitrile /latex/other) before sampling
3. Collect sample with dipper or directly in sample containers. If possible, collect water from the
flow directly in the sample bottle. Be careful not to disturb sediments.
4. Ifusing a dipper or other device, triple rinse the device with distilled water and then in water to
be sampled (not for bacteria sampling)
5. Use test strips, test kits, and field meters (rinse similar to dipper) for most parameters (see
Table 6-1)
6. Place laboratory samples on ice for analysis of bacteria and pollutants of concern
7. Fill out chain-of-custody form for laboratory samples
8. Deliver samples to City of Nashua Wastewater Treatment Facility Laboratory or contracted
laboratory.
9. Dispose of used test strips and test kit ampules properly
10. Decontaminate all testing personnel and equipment
In the event that an outfall is submerged, either partially or completely, or inaccessible, field staff will
proceed to the first accessible upstream manhole or structure for the observation and sampling and
report the location with the screening results. Field staff will continue to the next upstream structure
until there is no longer an influence from the receiving water on the visual inspection or sampling.
Field test kits or field instrumentation are permitted for all parameters except indicator bacteria and any
pollutants of concern. Field kits need to have appropriate detection limits and ranges.
In the past, the City has contracted with the Nashua River Watershed Association for sample collection
and analysis and associated standard operating procedures.
6.2 Follow-up Ranking of Outfalls
Nashua will update and re-prioritize the initial outfall rankings based on information gathered during dry
weather screening. The rankings will be updated periodically as dry weather screening information
becomes available.
Outfalls where relevant information was found indicating sewer input to the MS4 or sampling results
indicating sewer input are highly likely to contain illicit discharges from sanitary sources.
Such outfalls will be ranked at the top of the High Priority Outfalls category for investigation. Other
outfalls may be re-ranked based on any new information from the dry weather screening.
Hic it Discharge Detection and Himination Plan 15
