Surface Water Treatment Rule Objective Criteria Compliance

FAD Section 2 - Surface Water Treatment Rule Objective Criteria Compliance

The Objective Criteria include numeric requirements for turbidity, fecal coliform bacteria, and disinfection byproducts and also include requirements for system operations. The water system must provide adequate disinfection and must also have redundant disinfection system components. Under the 2007 FAD, the City must continue to meet all of the Objective Criteria in order to maintain its filtration avoidance status for the Catskill/Delaware water supply. The 2007 FAD also obligates the City to conduct a monitoring program and to report results in accordance with applicable State and federal regulations.

Evaluation of the NYC Water System's Performance

NYSDOH has evaluated the City's compliance with the Objective Criteria for maintaining filtration avoidance through review of the City's monthly monitoring reports and conducting annual inspections of water system infrastructure, treatment processes, and instrumentation. The SWTR specifies that compliance monitoring for source water quality shall be conducted immediately prior to the first or only point of disinfectant application. For the City's Catskill/Delaware water supply, under normal operating conditions, sampling of source water is performed at the Catskill Lower Effluent Chamber (CATLEFF) and at Delaware Shaft 18 (DEL18). Both CATLEFF and DEL18 are located near the south end of the Kensico Reservoir. As noted in Table 1, the City has satisfied the Objective Criteria's numeric requirements for source water turbidity and coliform bacteria for the Catskill/Delaware system.

Table 1. Catskill/Delaware System source water turbidity and fecal coliform levels 2007-2010.

	Catskill Lower Effluent Chamber		Delaware Shaft 18
Year	Maximum 4- Hour Turbidity Measurement (NTU)(1)	Maximum Percent of Fecal Coliform Samples >20 CFU/100mL(2)	Maximum 4-Hour Turbidity Measurement(NTU)(1)	Maximum Percent of Fecal Coliform Samples >20 CFU/100mL(2)
2007	3.4	1.7	2.0	0.0
2008	4.4	1.1	2.2	2.2
2009	3.6	1.1	3.1	2.2
2010	4.3	0.6	2.7	0.0

Notes:

(1): To maintain filtration avoidance status, the Catskill/Delaware system's 4-hour compliance readings must exhibit turbidity levels no greater than 5 NTU, unless it is determined that the turbidity was caused by an unusual orunpredictable event. No more than two events of turbidity greater than 5 NTU in twelve months or five events in120 months are allowed.

(2): To maintain filtration avoidance status, the Catskill/Delaware system must exhibit fecal coliform concentrations no greater than 20 CFU/100 mL in at least 90% of samples collected prior to disinfection in the previous 6 months of water service to the public.

In addition, the City has not exceeded the levels allowed for disinfection byproducts in the distribution system (i.e. 12-month running averages of 80 µ/L for total trihalomethanes and 60 µ/L for haloacetic acids). For the first five-year period, the running averages, evaluated quarterly, for total trihalomethanes and haloacetic acids have ranged from 36 - 43 µ/L and 34 - 45 µ/L, respectively. The City has also satisfied the system operation and reporting requirements as defined by the SWTR, and therefore has met the Objective Criteria required to maintain filtration avoidance status for the Catskill/Delaware system.

NYSDOH has issued seven Notices of Violation (NOVs) to the City during the first five-year period (Table 2). These were all monitoring violations. For example, the SSC (10 NYCRR Part 5, Subpart 5-1, section 5-1.30(c)(2)) requires the City to monitor the turbidity of its raw water every four hours. In accordance with the City's State-approved Standard Operating Procedure (SOP) for raw water turbidity monitoring, they are allowed a ten-minute window around those four hour time points within which they must collect their sample. In April 2008, there were ten instances when these turbidity compliance samples were not collected within the allowed time frame. This happened again for individual samples on: April 21, 2009; May 17, 2009; and December 27, 2010.

The remaining three violations were also related to raw water turbidity, but were incurred because the samples that the City collected were not representative of the source water. On March 10, 2010, roller gate operations caused a temporary spike in turbidity, which occurred near the collection of a turbidity compliance sample. This constituted a monitoring violation under SSC section 5-1.30(c)(2), because that four-hour compliance sample was not representative of the source water turbidity. On January 31, 2011, and the period of February 1 - 11, 2011, due to unusual water flows through DEL18, a chlorine residual could be detected at the raw water sampling location. However, according to federal regulation 40 CFR 141.71(a)(2), the source water turbidity must be measured prior to the first point of disinfection. Therefore, turbidity samples that contain a measurable chlorine residual cannot be considered representative of the source water.

NYSDOH required the City to submit Corrective Action Plans to document the steps taken to remedy the protocols, operations, and site conditions that led to these monitoring violations. At CATLEFF, these steps include adding a new transfer switch for a generator at the CATLEFF site, to allow easier site access during power outages. At DEL18, the City is in the process of installing a new chlorine solution pipe and modifying the raw water sampling intake location. The City continues to work collaboratively with the NYSDOH to minimize future occurrences of these violations.

Table 2. Catskill/Delaware System violations of 10 NYCRR Subpart 5-1 during first five-year period of the 2007 FAD.

Violation Number	Date(s)	Applicable Code Section	Remarks
2008-2008	April 1-30, 2008	5-1.75(a) - Additional Sampling Requirements	Failure to follow State-approved SOP
2009-2109	April 21, 2009	5-1.75(a) - Additional Sampling Requirements	Failure to follow State-approved SOP
2009-2110	May 17, 2009	5-1.75(a) - Additional Sampling Requirements	Failure to follow State-approved SOP
2010-2111	March 10, 2010	5-1.30(c)(2) - Raw Water Turbidity Monitoring	Failure to collect a representative sample
2011-2112	December 27, 2010	5-1.30(c)(2) - Raw Water Turbidity Monitoring	Failure to collect a representative sample
2011-2113	January 31, 2011	5-1.30(c)(2) - Raw Water Turbidity Monitoring	Failure to collect a representative sample
2011-2114	February 1-11,2011	5-1.30(c)(2) - Raw Water Turbidity Monitoring	Failure to collect a representative sample