NYC-WTC_000233682

NYC 9/11 Public Portal Document

response guidelines

• Notifications within utility. • Drinking water primacy agency. • Emergency response agencies.

i • • State/local public health agency. Local law enforcement agency. • National Response Center. • Other state and federal o • FBI. assistance providers. t II 1 i

t i

• Identify sites and initiate site • Estimate affected area and isolate • Characterize affected area. characterization. if possible. • Revise public health protection • Begin analysis of available • Implement appropriate public measures as necessary. water quality data. health protection measures. • Provide alternate water supply. s • Interview consumers in area • Plan for alternate water supply. • Plan remediation activities. p with high numbers of • Analyze samples. complaints. • Perform site characterization at • Consult external information additional investigation sites. sources. B

A threat warning arising from unusual water quality data is significantly different from the other threat warnings previously discussed and thus should be handled differently during the threat evaluation. In determining whether or not the threat is ‘possible,’ it is necessary to evaluate the anomalous data relative to an established baseline. Furthermore, it is important to consider operational conditions, or potential impacts from changing source water quality or distribution system blending as possible explanations for the unusual water quality or complaint. If the unusual water quality data is determined to be significantly different from the baseline, and cannot be explained by other factors, then t contamination may be considered a possibility.

Presumably, the unusual water quality data will be associated with a particular location in the system, which will help in the identification of investigation sites that will be the focus of site characterization activities. At this stage, it is important to verify the anomalous water quality data through additional testing using independent equipment. For example, if an incident was triggered by a rapid decrease in the free chlorine residual, as detected by online electrochemical monitors, additional testing could be performed with colormetric field kits to confirm the results. Additional rapid field testing might also help to determine the bounds of the affected area. Furthermore, specific information about particular contaminants should be considered at the ‘credible’ stage as it might be used to identify potential contaminants that would impact the water quality parameter with anomalous readings. For example, contaminants with acidic functional groups might result in reduced pH.

76 Interim Final - August 2004

CITY_21MC100_0 04992415

NYC-WTC_000233758