- FAD Section 8.1 - Waterborne Disease Risk Assessment Program
- FAD Section 8.2 - Cross Connection Control Program
FAD Section 8.1 - Waterborne Disease Risk Assessment Program
2007 FAD Requirements
As a condition of filtration avoidance, in accordance with the SWTR, a public utility must demonstrate that it has not been the source of a waterborne disease outbreak. The 2002 FAD required the City to maintain a system to detect the presence of waterborne disease outbreaks and to report any evidence of such an outbreak.
The City has a Disease Surveillance Program, the overall objective of which is to track the incidence of, and gather relevant epidemiological data on, two waterborne diseases: giardiasis and cryptosporidiosis. Key objectives of the City's Disease Surveillance Program include tracking the incidence of disease, and developing and maintaining systems to detect disease outbreaks and determine the possibility of waterborne transmission. It is important to know the endemic rates for giardiasis and cryptosporidiosis, as well as any possible association between these diseases and the NYC water supply. By knowing the endemic rate, any unexpected or unusual indicators of disease would allow the appropriate protective steps to be taken by health care professionals and water supply consumers. Surveillance that may help reveal early evidence of a possible waterborne disease outbreak could prevent disease from occurring on a widespread basis.
The City's 2006 Long-Term Watershed Protection Program includes a Waterborne Disease Risk Assessment Program (WDRAP) (Section 2.7.1). Section 8.1 of the 2007 FAD requires that the City implement and continue to operate the WDRAP in accordance with their long-term plan. Specifically, the 2007 FAD requires that the City: implement the Cryptosporidium Action Plan (CAP) when concentrations of Cryptosporidium oocysts detected in source water exceed trigger levels; provide syndromic surveillance system information, upon request by the regulators, in response to any water quality "event"; notify regulators when there is indication of significant levels of gastrointestinal (GI) illness that may be water supply related; and work with NYSDOH and EPA on developing a Turbidity Action Plan (TAP).
Evaluation of the NYC Water System's Performance
The City has met all the requirements of this FAD program. The WDRAP has continued to operate and assess City-wide conditions on a regular basis. The City submits an annual report and an interim report on the implementation and findings of this program.
The CAP protocol, which was developed and issued in 2002, is regularly reviewed and revised as needed. The last revision occurred on January 30, 2009. The CAP is an event-based protocol which is triggered by the recovery of Cryptosporidium oocysts in conjunction with other water quality and operations information. A single activation of the CAP occurred in November 2008 as a result of a laboratory error. High numbers of oocysts were reported in a sample from the New Croton Reservoir as a result of a manipulation error. However, the CAP was activated until the error was confirmed. De-escalation was simplified by the fact that there was no risk to the public.
NYSDOH and EPA have not requested syndromic surveillance information for identifiable water quality events since the 2007 FAD has been implemented. In the past, the New York City Department of Health and Mental Hygiene has issued Health Alerts when turbidity levels in the Kensico Reservoir could potentially impact the quality of water delivered to the City. No such alerts have been issued since 2005.
WDRAP has not identified any significant signs of community GI illness that could be attributed to the drinking water supply. Major and/or transient disease signals frequently coincide with localized and multi-site occurrences of norovirus on a seasonal basis.
The TAP was developed to establish an organized response to elevated turbidity levels in the source water of the City's drinking water supply prior to turbidity levels reaching the SWTR limit of 5 NTU. Turbidity is often used as a surrogate indicator of protozoan intrusions and, therefore, any response to unusual turbidity would be done with consideration of the implementation of the CAP. The final version of the TAP was issued in 2009, and was last revised April 2011. The TAP has been activated a number of times since adoption, and has worked well to ensure that key parties are informed when turbidity levels are elevated, and that consistent action is taken to address potential water quality issues.
NYSDOH and EPA believe that the City has a very strong and effective waterborne disease risk assessment and surveillance program. This program is key to assessing that the City's water is not a source of a waterborne disease outbreak, as required by the SWTR for filtration avoidance.
FAD Section 8.2 - Cross Connection Control Program
2007 FAD Requirements
Cross connections in the distribution system of a water supply can be a serious source of contamination. The City's 2006 Long-Term Watershed Protection Program contains a detailed inspection and reporting schedule for a Cross Connection Control Program (Section 2.7.2). The 2007 FAD requires the City to implement a Cross Connection Control Program in accordance with its long-term plan. Requirements of the 2007 FAD include: respond to cross connection control complaints, initiate enforcement for non-compliant hazardous premises, approve backflow preventer plans, accept backflow preventer plans with self-certification, issue Notices of Violation for failure to test annually, review requests for exemption from cross connection control requirements, and perform full inspections of potentially hazardous premises.
Evaluation of the NYC Water System's Performance
The City has a very active cross connection control program, which has exceeded all the performance goals set by the 2007 FAD. The importance of this program has been demonstrated during some cross connection incidences that have occurred in the last five years. Since the beginning of the 2007 FAD term, cross connection investigations were activated by the following incidences:
- In January 2007, elevated pH readings in water from a sampling station in Staten Island led to an investigation. No cross connections were discovered, and an off-line concretelined 72-inch main adjacent to the sample station was identified as the source of the high pH water;
- In May 2007, the City received a report that ethylene glycol had entered the water supply for a high school in Manhattan through a cross connection with the school's air conditioning units. The problem was identified as a failed backflow prevention device in the school. Samples taken from nearby hydrants did not indicate that the City's water supply, outside of the school, had been impacted;
- Also in May 2007, a routine distribution water sample taken in Queens was found to contain tetrachloroethylene (PERC). Additional samples were confirmed for detection of PERC, and the City launched an intensive effort to find the source of the contamination. Cross connections were discovered at a car wash, but it was not clear that the facility was the source of the PERC. Flushing cleared the area of contamination, and inspections of "High Hazard" facilities continued in the area for several months.
- In November 2007, elevated conductivity was detected in water from sampling stations in Brooklyn. A car wash that was cross connected to a private well was found to be the source of the high conductivity. These latter two cross connection incidences prompted the City to focus on car wash inspections, inspecting approximately 130 car washes in all five NYC boroughs over the next few months.
- In April 2010, routine sampling detected unusual water quality that led to the discovery of cross connections at the Hutchinson Metro Tech Center in the Bronx. Backflow preventers were installed incorrectly at the facility and failed to work when a main break occurred in the area;
- In May 2010, complaints from a residence in Queens led to the detection of propanol and other contaminants in drinking water in the area. The City's cross connection inspectors found the source at a nearby vacant hotel with a defective check valve between the fire suppressant and potable water systems; and
- In June 2010, propylene glycol from an air conditioning system contaminated the water supply for a school in Queens, sickening a number of students. A reduced pressure zone backflow preventer installed on the service line to the school prevented contamination of the City's supply.
In all these cases, the City's cross connection control team, along with other NYCDEP staff, responded quickly to determine the nature, extent, and source of the contamination, and to minimize potential exposure of consumers to contaminated water.
Through inspections of potential sources of cross connections and follow-up enforcement to ensure backflow prevention devices are installed where necessary, the Cross Connection Control Program is also an important tool for preventing contamination of the City's water once it reaches the distribution system. During 2010, the City contracted with a consulting firm to perform cross connection control inspections, review plans for new installations, and prepare enforcement notices. While use of this contractor has helped the City address a backlog of inspections of potentially hazardous properties that were identified in 1998, the City is now left with a significant amount of follow-up work to ensure cross connection control is installed where necessary. NYSDOH and EPA feel that this program is a critical additional barrier to protecting the City's unfiltered water supply and encourage the City to provide the resources necessary to address this work load.