Nitrosamines – Cost Analysis in the Game of Regulatory Roulette
- Erik Rosenfeldt, Ben Stanford, and Mark Bishop - Hazen and Sawyer
Nitrosamines are a class of drinking water contaminants typically associated with the chlorination of wastewaters or the chloramination of surface waters under the influence of wastewater. Considered probable human carcinogens, the drinking water concentration of NDMA estimated to result in an elevated 1 in 10,000 lifetime cancer risk level is 0.07 ?g/L (USEPA, 2008), but no federal MCL has been promulgated to date. Currently, the EPA is considering regulation of Nitrosamines in two related ways: Five nitrosamines are included on the third Contaminant Candidate List (CCL3), after also having been included in the second Unregulated Contaminant Monitoring Rule (UCMR2) program. Additionally, nitrosamines have been identified as a group for likely near term potential regulatory development, as part of the EPA’s approach for addressing groups of contaminants under the safe drinking water act, though no mention has been made of a maximum contaminant level.
Analysis of data from UCMR2 utilities revealed that nitrosamines were detected in 35% of finished water samples from Texas utilities, significantly greater than the national average of 9%. Eighteen utilities which took at least 10 nitrosamine samples in their distribution system detected the compounds in more than 50% of the collected samples. Additionally 52% of nitrosamine samples collected from Texas systems employing chloramines for residual disinfection detected the compounds at measurable levels. Significant concern has been raised regarding the long-term use of chloramines as a technique for compliance with existing disinfection byproduct (DBP) regulations due to the potential for nitrosamine formation. Thus, many utilities are at a crossroads: Do they continue with the use of chloramines, hoping that any potential regulatory action by the US EPA will not result in a nitrosamine MCL violation or do they upgrade the facility to provide enhanced removal of organic matter (e.g., activated carbon or ion exchange) to meet current and pending DBP regulations and perhaps avoid NDMA problems down the road?
With such a guessing game (“regulatory roulette”) in place, this talk will use the UCMR2 data to contextualize the issue in Texas, and then will provide concrete examples of a relative cost analysis for preemptive vs. reactive facility upgrades given the potential regulatory time frame of 4 to 5 years. Our initial cost estimates indicate that preemptive upgrades to GAC may be costly and unnecessary, and even if required in the future would still represent a cost savings to delay implementation for 4 years or longer. Detailed analysis of our cost estimates and several key points instrumental to understanding sources, formation mechanisms, and potential treatment technologies for controlling nitrosamines will be discussed. We will also discuss sampling and monitoring strategies for utilities wishing to assess the issue of potential NDMA/nitrosamine occurrence in their systems.
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